JPS647096B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ethylene-α olefin copolymer resin composition. More specifically, it is made by mixing an ethylene-α-olefin copolymer with a relatively high molecular weight and an ethylene-α-olefin copolymer with a relatively low molecular weight, and has excellent processability, impact strength, and tensile strength. The present invention relates to an ethylene-α-olefin copolymer resin composition that has excellent mechanical strength such as environmental stress cracking resistance, cold resistance, and creep resistance, as well as excellent chemical properties such as chemical resistance. Conventionally, low-density polyethylene produced by a high-pressure method (hereinafter referred to as high-pressure polyethylene) has good rheological properties and physical and chemical properties as a melt, so it can be used in films, sheets, pipes, hollow containers, etc.
It has been used for various purposes such as injection molded products, steel pipe coating materials, and foam molding materials. It is true that the rheological properties of the melt are good, so when it is used for extrusion processing or injection molding, the productivity is good and the power consumption is relatively low.For example, in the case of blown film processing, bubble stability is achieved. On the other hand, the mechanical strength of the molded product: for example, the mechanical strength of the molded product: Since its strength and impact strength are relatively low, it cannot be used in a thinner form, and since the price of petrochemical raw materials has skyrocketed, its fields of use have been restricted. Furthermore, there are many fields in which it is used as a film, and in such cases, in addition to the demand for low-temperature heat-sealability due to the advancement of automatic packaging systems in recent years, heat-sealing is required because the contents are filled at the same time as heat-sealing. In some cases, the seal strength is required when the seal part is not yet cooled and solidified (this property is called hot-tack property), and when packaging oils, the seal strength is required when the oil is attached to the seal part (this property is called hot-tack property). However, high-pressure polyethylene still lacks such hot-tack and dirt-sealing properties. In addition, in fields where hollow containers, pipes, and injection molded products are used, environmental stress cracking resistance is still insufficient, which sometimes causes trouble, and there is also a tendency to be easily attacked by chlorinated water, etc., and creep rupture resistance. There are problems such as the fact that it cannot be used for pipe applications with high internal pressure because of its extremely insufficient properties.
In addition, in the field where it is used as a steel pipe coating material, its cold resistance is still insufficient and it is not suitable for use in extremely cold regions, and in the field where it is used as a wire covering material, it has low environmental stress cracking resistance and water tree resistance. At present, problems still occur from time to time because the phenomenon is still insufficient. In order to improve these drawbacks, manufacturers of high-pressure polyethylene have made great efforts in the past, and although some improvements have been made, they are still not at a satisfactory level, and research efforts are still being continued day and night. On the other hand, in order to improve this drawback, there are methods of copolymerizing ethylene with other polymerizable monomers such as vinyl acetate, and so-called ionomer resins in which metal salts are formed after copolymerizing ethylene with (meth)acrylic acid. A method of converting is used. However, among these methods, the method using ethylene-vinyl acetate copolymer reduces the tear strength, rigidity, and heat resistance of the film, and causes problems such as corrosion of the extruder and odor due to deacetic acid removal during processing. Or,
There are still many problems such as blocking and cold blowing phenomena due to the sticky surface of the film. Furthermore, methods using ionomer resins have problems such as decreased thermal stability and weather resistance and are expensive. On the other hand, there are also proposals to solve this problem by blending high-density polyethylene, other α-olefin resins such as polypropylene, polybutene, and rubbers with high-pressure polyethylene, but none of them have been successful. There are still unsatisfactory situations in which improvements in one property lead to defects in others. On the other hand, as a resin having a density comparable to that of high-pressure polyethylene, a resin obtained by copolymerizing ethylene and α-olefin under medium-low pressure using a transition metal catalyst is known. (hereinafter abbreviated as ethylene-α-olefin copolymer). Among these, those produced using vanadium catalysts have only a low degree of crystallinity, and have problems in heat resistance, weather resistance, and mechanical strength. On the other hand, products produced under normal polymerization conditions using titanium-based catalysts generally have a narrow molecular weight distribution, and compared to high-pressure polyethylene, due to the narrow molecular weight distribution, they have relatively good mechanical strength, but The rheological properties of the film are poor, for example, a large amount of power consumption is required during inflation processing, the discharge amount is reduced, bubble stability is poor, and the film surface becomes shark-skin-like when processing at high speeds. There are many problems in processing, such as the formation of shark skin and loss of commercial value. Similarly, during blow molding, there are problems such as a large amount of power consumption, a decrease in the discharge amount, a lack of stability of the parison, and a loss of commercial value due to the surface of the molded product becoming a shark skin. . In addition, during injection molding, it has poor fluidity under high pressure compared to high-pressure polyethylene, so it is necessary to significantly increase the processing temperature, which is disadvantageous in terms of thermal energy.
Furthermore, there are secondary problems such as deterioration of the resin. Attempts have been made in recent years to solve these problems by modifying extruders, screws, dies, etc., but this requires a large amount of cost and the technology is still insufficient. Furthermore, when forming a film using an ethylene-α-olefin copolymer with such a narrow molecular weight distribution, for example, by inflation processing, there are problems such as a small discharge rate, a large amount of electrical energy required, and a lack of bubble stability. In addition to the above problems, the mechanical strength of the obtained film was difficult to balance in the machine direction (MD) and transverse direction (TD), and the tear strength in the MD direction was inferior to that of high-pressure polyethylene. Transparency also has the problem of being inferior to high-pressure polyethylene because the crystallization rate is faster than that of high-pressure polyethylene and melt flow failure is more likely to occur. Furthermore, when attempting to produce products under normal polymerization conditions using chromium-based catalysts, there is a problem in that it is difficult to obtain low-density products because the copolymerizability of ethylene and α-olefin is generally inferior to that of titanium-based catalysts. Products manufactured using, for example, chromium-titanium catalysts for the purpose of improvement generally have a broader molecular weight distribution than those manufactured using titanium catalysts, and although processability is somewhat improved, mechanical strength is poor. This results in a significant deterioration in physical properties compared to high-pressure polyethylene, and there are other problems such as poor transparency in films, sheets, bottles, etc. Furthermore, in order to improve the transparency of the ethylene-α-olefin copolymer, if a large amount of α-olefin is copolymerized to further reduce the density, the conventional technology produces a sticky polymer with significantly reduced mechanical strength. The problem is that you can only obtain merging. According to the findings of the present inventors, when ethylene and α-olefin are polymerized using a transition metal catalyst under medium-low pressure, the composition distribution of the resulting polymer is not uniform, and short chain branching (terminal methyl group is excluded) with respect to molecular weight. In general, lower molecular weight substances tend to have more short chain branches, while higher molecular weight substances tend to have fewer short chain branches. This is considered to be because α-olefin tends to act as a chain transfer agent, and α-olefin tends to act on catalyst active sites where molecular weight regulators (eg, hydrogen, etc.) tend to act. (See Reference Example 1) As a result, for example, when polymerizing an ethylene-α-olefin copolymer by increasing the concentration of α-olefin in an attempt to significantly lower the density, the short chain branching of the low-molecular-weight copolymer only increases unnecessarily. Although the density decreases, this low-molecular-weight material with many short chain branches becomes a component that becomes bathable in solvents and causes the polymer to become sticky, resulting in only a polymer with low mechanical strength. It is. This tendency can be confirmed by using a catalyst that provides a relatively wide molecular weight distribution.
This is particularly noticeable when olefins are copolymerized. This is thought to be one of the reasons why the mechanical strength of ethylene-α-olefin copolymers with a wide molecular weight distribution is low. As mentioned above, when trying to produce a resin with a density similar to that of high-pressure polyethylene by copolymerizing ethylene and α-olefin under medium and low pressure using a transition metal catalyst, it is important to have good processability and good mechanical properties. It is difficult to provide strength and transparency at the same time.
For example, if the molecular weight is lowered for the purpose of improving processability, the mechanical strength will drop significantly and the features of the copolymer will be lost, and even if the molecular weight distribution is expanded, the mechanical strength will similarly drop significantly. (See Reference Example 2)
Furthermore, the transparency deteriorates and the surface of the molded product becomes sticky, making it difficult to achieve both processability and physical properties. The reality is that no ethylene-α-olefin copolymer has been provided. As mentioned above, although high-pressure polyethylene has good rheological properties and excellent processability, it has the problem of relatively low mechanical strength. Resins that have a density similar to that of high-pressure polyethylene obtained by polymerization have a narrow molecular weight distribution, so while they have excellent mechanical strength, they have the problem of poor processability, but this difference is essentially It is thought that this is mainly due to the molecular structure of the resin. In other words, high-pressure polyethylene is obtained by radical polymerization in an autoclave or tubular reactor under a high pressure of about 1500 to 4000 kg/ ^cm2 and at a high temperature of about 150 to 350°C, and its molecular structure is extremely Although it is complex and is an ethylene homopolymer, short chain branches consisting of alkyl groups having 1 to 6 carbon atoms are generally observed, and this short chain branching affects the crystallinity of the resin and therefore The density will be controlled. The distribution of short chain branches (distribution of short chain branches with respect to molecular weight) of such high-pressure polyethylene is relatively uniform, and both the low molecular weight product and the high molecular weight product have a substantially average number of branches. Furthermore, a major feature of high-pressure polyethylene is that it has complex long chain branches in addition to the short chain branches mentioned above. Although it is difficult to identify this long chain branch, it is generally thought that it is an alkyl group having a carbon number of several thousand or more since it has the same length as the main chain, and is different from the above-mentioned short chain branch. The presence of these long chain branches has a great effect on the melt rheological properties of the resin, and is one reason why high-pressure polyethylene has good processability. On the other hand, a resin having a density similar to that of high-pressure polyethylene obtained by copolymerizing ethylene and α-olefin under medium-low pressure using a transition metal catalyst is produced by copolymerizing ethylene and α-olefin in the presence of a transition metal catalyst in an autoclave or a tubular reactor. It is obtained by copolymerizing ethylene and α-olefin under medium-low pressure of ~150Kg/ ^cm2 at relatively low temperatures of 0 to 250℃, usually 30 to 200℃, and its molecular structure is comparable. It's simple. Such an ethylene-α-olefin copolymer is characterized by almost no long chain branching, which characterizes high-pressure polyethylene, and the branching is only short chain branching. Unlike high-pressure polyethylene, this short chain branching is not generated through a complicated reaction process during polymerization, but is controlled by the type of α-olefin used in the copolymerization. For example, ethylene and butene-1
When copolymerized, the short chain branches are generally ethyl branches. Occasionally, dimerization of butene-1 is expected to result in hexyl branching. Such short chain branching will control the crystallinity and therefore the density of the resin. In addition, the distribution of short chain branches is influenced by the properties of the transition metal catalyst used in copolymerization, the type of α-olefin, the polymerization method, and the polymerization temperature, but unlike in the case of high-pressure polyethylene, it is not uniform and generally has low The molecular weight substances tend to have more short chain branches, and the higher the molecular weight substances have fewer short chain branches, and the distribution is wide.
(See Reference Example 1) Therefore, a resin having a density comparable to that of high-pressure polyethylene obtained by copolymerizing ethylene and α-olefin under medium-low pressure using a transition metal catalyst has come into practical use. Nowadays, the conventional method of distinguishing that polyethylene resins with a density of 0.910 g/cm or more and 0.935 g/cm or less is high-pressure polyethylene is inappropriate; It should be done with or without long chain branching. In addition, some low-density polyethylene that does not substantially have long chain branches can be obtained by polymerizing using a transition metal catalyst under high pressure and high temperature similar to that used to obtain high-pressure polyethylene. Density polyethylene is also included in the ethylene-α-olefin copolymer referred to in the present invention. The presence or absence of long chain branching has begun to be elucidated to a considerable extent using solution theory methods. For example, light scattering methods have been used to investigate the presence or absence of long chain branching in linear polyethylenes (using Ziegler catalysts under medium and low pressures) that exhibit the same weight average molecular weight. High-density polyethylene obtained by homopolymerizing ethylene)
In the case of [η] of the sample polyethylene with respect to ^the intrinsic viscosity number [η] _l of Since the spread inside is small,
g ^* 〓 becomes smaller. Generally, high-pressure polyethylene
g ^* 〓 often shows 0.6 or less. Although this method is useful, in practice it can be relatively easily and clearly distinguished based on the correlation between the melt index and the intrinsic viscosity of the resin. This relationship is shown in Reference Example 3, and due to the presence of long chain branches, high-pressure polyethylene tends to have a much lower intrinsic viscosity than the ethylene-α-olefin copolymer having the same melt index. . High-pressure polyethylene and ethylene-α-olefin copolymers, which are distinguished in this way, are essentially characterized by the presence or absence of long chain branching, which affects the rheological properties and crystallization behavior of the melt as well as the mechanical and optical properties of the solid. It is thought that this will make a big difference. The present inventors have solved the above-mentioned problems of polyethylene resin, and it has processability equivalent to or better than high-pressure polyethylene, and has tear strength, impact strength, environmental stress cracking resistance, cold resistance, creep resistance, In order to provide a polyethylene resin with excellent physical properties such as chemical resistance, transparency, and heat-sealing properties, we have conducted extensive research to improve the density, intrinsic viscosity, short chain branching degree, type of α-olefin, and even ( The relatively high molecular weight ethylene-α-olefin copolymer whose weight average molecular weight)/(number average molecular weight) was specified, density, intrinsic viscosity, short chain branching degree, type of α-olefin, and (weight The relatively low molecular weight ethylene-α-olefin copolymer with the specified average molecular weight)/(number average molecular weight) is compared with the short chain branching degree of the relatively high-molecular-weight ethylene-α-olefin copolymer and the relative By mixing the ethylene-α-olefin copolymer, which has a relatively low molecular weight, with the short chain branching degree within a specific range, it has extremely superior processability compared to conventional technology. It was discovered that a polyethylene resin composition having physical properties such as tear strength, impact strength, environmental stress cracking resistance, cold resistance, creep resistance, chemical resistance, transparency, and heat sealing properties could be obtained, and the present invention was completed. did. That is, the present invention has a density of 0.895 g/cm ³ or more.
0.935g/ ^cm3 or less, intrinsic viscosity 1.2dl/g or more
Ethylene with a concentration of 6.0 dl/g or less and a short chain branching number (short chain branching degree) per 1000 carbon atoms of 7 or more and 40 or less,
Copolymer with α-olefin having 3 to 18 carbon atoms
A: 10% by weight or more and 70% by weight or less, density is 0.910
g/cm3 ^or more and 0.954g/ ^cm3 or less, the intrinsic viscosity is 0.3
dl/g or more and 1.5 dl/g or less, copolymer B of ethylene with a short chain branching number of 5 or more and 35 or less per 1000 carbon atoms and α-olefin with a carbon number of 3 or more and 18 or less B 90% by weight or less 30% by weight In this case, (degree of short chain branching of copolymer A)/(degree of short chain branching of copolymer B) is 0.6 or more and The intrinsic viscosity of polymer B is 1.5
Copolymer A and copolymer B are selected so that the density is 0.910 g/cm ³ or more and 0.935 or less.
less than g/ ^cm3 , melt index is 0.02g/10
min or more and 40g/10 min or less, melt flow ratio is 35 or more
The present invention relates to an ethylene-α olefin copolymer resin composition with excellent strength and a strength of 250 or less. The first feature of the present invention is that, compared to high-pressure polyethylene, it is a relatively low-density polyethylene that has the same or better workability and has significantly superior tensile strength, impact strength, environmental stress cracking resistance, and creep rupture resistance. The present invention is capable of providing a polyethylene resin composition. The second feature of the present invention is that, as mentioned above, it has excellent mechanical strength and higher rigidity than high-pressure polyethylene, and it can provide transparency comparable to that of high-pressure polyethylene, so it can be used, for example, in film applications. When used for this purpose, the same performance can be achieved even if the film thickness is made 10 to 20% thinner than that of high-pressure polyethylene, and resources can be saved. The third feature of the present invention is that it has better extrusion processability than the comparatively low-density ethylene-α-olefin copolymer of the prior art. The point is that it can be used without modification. The fourth feature of the present invention is that compared to conventional low-density ethylene-α-olefin copolymers, even those with a low melt index have better fluidity during actual processing, resulting in less bubbles. Excellent stability, mechanical strength in MD direction,
The advantage is that it is easier to balance the TD direction, so a homogeneous product can be obtained. The fifth feature of the present invention is that compared to conventional low-density ethylene-α-olefin copolymers, a non-sticky resin composition can be obtained even at a lower density, so flexibility and impact properties are required. It is also suitable for various purposes. The sixth feature of the present invention is that a high quality resin can be provided substantially by a polymer blending method.
The advantage is that it is easy to create a grade structure that meets the diversifying needs of customers. The above-mentioned features are advantages of the present invention over the prior art. The present invention will be explained in more detail below. The relatively high molecular weight ethylene-α-olefin copolymer (hereinafter referred to as copolymer A) used as a component of the mixture in the present invention is a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms. As α-olefin, which is a polymer and a copolymerization component,
A compound represented by the general formula R-CH=CH ₂ (in the formula, R represents an alkyl group having 1 to 16 carbon atoms), and specific examples include propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1,4-methylpentene-1,4-methylhexene-1,4,4-
Examples include dimethylpentene-1. Among these α-olefins, propylene-based α-olefins have relatively little improvement effect in the present invention, and α-olefins having 4 or more carbon atoms are preferred, particularly butene-1, pentene-1,
1, hexene-1, octene-1,4-methylpentene-1, etc. are preferred in terms of monomer availability, copolymerizability, and quality of the resulting copolymer. Note that two or more of these α-olefins can also be used in combination. The density of these ethylene-α-olefin copolymers depends on the type of α-olefin that is a copolymerization component, the α-olefin content, and the intrinsic viscosity of the copolymer, but for the purpose of the present invention, the density The density is preferably 0.895 g/cm ³ or more and 0.935 g/cm ³ or less, and more preferably the density is 0.895 g/cm ³ or more and 0.930
g/cm ³ or less. If the density is less than 0.895 g/cm ³ , the copolymer may adhere to walls during production, making production difficult. As a result, it is necessary to increase the density of the low molecular weight component, which is undesirable because the obtained resin composition can only provide a film with poor transparency, and the density is 0.930 g/
cm ³ or more, the α-olefin content of the copolymer becomes extremely small, and when the present invention is carried out using the copolymer with such a density, the mechanical strength or, for example, the MD of a film, decreases. This is not preferable because it becomes difficult to balance the direction and TD direction, and the heat sealing properties deteriorate. Furthermore, the number of short chain branches per 1000 carbon atoms of the copolymer (hereinafter abbreviated as short chain branching degree). In this case, if R is a straight chain alkyl group, the number of methyl groups at the branch end - CH ₃ /1000C is It represents the degree of chain branching, and when R is a branched alkyl group, for example, α-olefin is 4-methylpentene-
In the case of 1, the branch is an isobutyl branch, and the degree of short chain branching is half the number of methyl groups at the branch end)
is preferably 7 or more and 40 or less, more preferably 10 or more and 40 or less. Short chain branches in the ethylene-α-olefin copolymer are generated by the α-olefin and mainly play the role of inhibiting crystallization of the ethylene chain and lowering the density, but the effect differs depending on the type of α-olefin. In addition to simply inhibiting crystallization, it is thought to have some kind of contribution to the generation of interlamellar molecules, which ultimately affects mechanical strength and thermal properties. Therefore, when the short chain branching degree is 7 or less, when implementing the present invention, the mechanical strength, for example, in the case of a film, its MD direction, TD
This is undesirable as it makes it difficult to maintain directional balance and deteriorates heat sealing properties.If the degree of short chain branching is 40 or more, there will be problems in producing the copolymer and the transparency of the resin composition obtained by mixing will deteriorate. Therefore, it is not desirable. The molecular weight of the ethylene-α-olefin copolymer is preferably 1.2 dl/g or more and 6.0 dl/g or less, more preferably 1.2 dl/g or more and 4.5 dl/g or less in terms of intrinsic viscosity.
dl/g or less. If the intrinsic viscosity is 1.2 dl/g or less, the mechanical strength of the resin composition obtained by carrying out the present invention will be low, which is not preferable, and it is not preferable that the limiting viscosity is 6.0 dl/g.
With the above, it becomes relatively difficult to mix sufficiently with the molecular weight components, and the resulting resin composition will not only have spots and spots, but also deteriorate its fluidity, and furthermore, it will reduce its transparency. Undesirable. Note that the value of (weight average molecular weight)/(number average molecular weight), which is a measure of molecular weight distribution obtained by gel permeation chromatography (hereinafter abbreviated as GPC) measurement of the copolymer, is 2 or more and 10 or less. It is preferably 3 or more and 8 or less.
If the ratio (weight average molecular weight)/(number average molecular weight) is less than 2, it is difficult to produce such a copolymer, which is undesirable. This is undesirable because it reduces strength and causes blocking when formed into a film, for example. The relatively low molecular weight ethylene-α-olefin copolymer (hereinafter referred to as copolymer B) used as another component of the mixture in the present invention is a combination of ethylene and α-olefin having 3 to 18 carbon atoms. α-olefin, which is a _copolymer of
16 alkyl group),
Specific examples include propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1,4 methylpentene-1,4 methylhexene-1,4,4 -dimethylpentene-1, etc. Among these α-olefins, propylene has relatively little improvement effect in the present invention, and α-olefins having 4 or more carbon atoms are preferred, particularly butene-1, pentene-1, hexene-1, octene-1,4 methylpentene-
1 and the like are preferred in terms of monomer availability, copolymerizability, and quality of the resulting copolymer. In addition, these α-
Two or more olefins can also be used in combination. The density of these ethylene α-olefin copolymers B is preferably 0.910 g/cm ³ or more and 0.954 g/cm ³ or less, more preferably 0.915 g/cm ³ or more and 0.949
g/cm ³ or less. If the density is less than 0.910 g/cm ³ , the mechanical strength of the resin composition obtained by carrying out the present invention may decrease, or, for example, it may cause blocking due to bleeding of low-density, low-molecular-weight components to the surface of the film. undesirable, density
If it exceeds 0.954 g/cm ³ , the transparency of the resin composition obtained by carrying out the present invention will deteriorate or the density will become too high, which is not preferable. Further, the degree of short chain branching of the copolymer is preferably 5 or more and 35 or less, more preferably 7 or more and 30 or less. If the degree of short chain branching is less than 5, the crystallization rate will be high because it is a relatively low molecular weight component, which will deteriorate the transparency of the resin composition obtained by carrying out the present invention, which is undesirable, and if it is more than 35, the mechanical This is not preferable because it causes a decrease in strength and, for example, blocking in the case of a film. In addition, the molecular weight of the copolymer is 0.3 in terms of intrinsic viscosity.
It is preferably dl/g or more and 1.5 dl/g or less, more preferably 0.4 dl/g or more and 1.5 dl/g or less. If the intrinsic viscosity is less than 0.3 dl/g, the mechanical strength and transparency of the resin composition obtained by carrying out the present invention will decrease, which is undesirable, while if it is 1.5 dl/g or more, the resin composition obtained by carrying out the present invention will This is not preferred because the fluidity of the composition becomes poor. The value of (weight average molecular weight)/(number average molecular weight) determined by gel permeation chromatography (GPC) of the copolymer is preferably 2 or more and 10 or less, more preferably 3 or more and 8 or less. . If the value of (weight average molecular weight)/(number average molecular weight) is 2 or less, it is difficult to produce such a copolymer, which is undesirable, and if it is 10 or more, the mechanical stability of the resin composition obtained by implementing the invention is This is undesirable because it tends to reduce the strength and cause the film to become sticky. Such an ethylene-α-olefin copolymer is obtained by copolymerizing ethylene and an olefin having 4 to 18 carbon atoms under medium and low pressure using a transition metal catalyst. There are no particular restrictions on catalysts or polymerization methods as long as they do not detract from the spirit of the present invention. Examples of catalysts include so-called Ziegler-type catalysts and Phillips-type catalysts, and examples of polymerization methods include so-called slurry polymerization and gas phase polymerization. and solution polymerization. Among these, they are advantageous for the present invention in terms of carrier-supported Ziegler catalyst activity and copolymerizability. To give a specific example, inorganic compounds such as metal and silicon oxides, hydroxides, chlorides, carbonates, and mixtures and double salts of metals and silicon are effective as supports for carrier-supported Ziegler catalysts. Magnesium, titanium oxide, silica, alumina, magnesium carbonate, divalent metal hydroxychloride, magnesium hydroxide, magnesium chloride, magnesium alkoxide, magnesium haloalkoxide, double oxide of magnesium and aluminum, double oxide of magnesium and calcicum, etc. can give. Among these, magnesium compounds are particularly preferred. Among them, the following carriers are most preferable in the relatively low density polyethylene resin composition of the present invention because they are non-sticky, have good slurry properties, and have very little polymer adhesion to the polymerization tank. (See Special Publication No. 55-23561).
That is, the general formula RnAlX _3-o (where R has 1 to 1 carbon atoms)
20 alkyl, aryl, alkenyl groups,
X represents a halogen atom, and n represents a number of 0≦n≦3. ) and/or the general formula R′mSiX _4-n (where R′ is an alkyl group, aryl group, or alkenyl group having 1 to 20 carbon atoms, X is a halogen atom, and m is 0 ≦m≦4
Indicates the number of ) and the general formula R″Mgx and/or R″ ₂ Mg (where R″ is an alkyl group having 1 to 20 carbon atoms, an aryl group,
It represents an alkenyl group, and X represents a halogen atom. ) is reacted with an organomagnesium compound represented by ) in a solvent, and the resulting solid product is isolated. On the other hand, examples of transition metal compounds supported on the carrier include titanium compounds, vanadium compounds, and zirconium compounds. Specifically, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium trichloride, and general formula an alkoxyhalogenated titanium compound or an aryloxyhalogenated titanium compound represented by Ti(OR ¹ ) ₄ -pXp (in the formula, R ¹ is a carbon hydrogen group, X is a halogen, and P represents a number of O<P<4); Vanadium tetrachloride, vanadium oxytrichloride, zirconium tetrachloride, general formula Zr( ^OR2 )4-
Alkoxy zirconium halides or aryloxy zirconium halides represented by qXg (in the formula, R ² is a hydrocarbon group, X is a halogen, and q represents a number satisfying 0<q<4) can be mentioned. Among these, when titanium compounds and/or vanadium compounds are used, the slurry properties are good without stickiness, and there is very little polymer adhesion to the polymerization tank. Preferable (Special Publications 1977-
(See Publication No. 23561). Among these, titanium compounds are most preferred in terms of weather resistance, heat resistance, and the like. Further, the carrier-supported Ziegler catalyst in the present invention is represented by the general formula Ti(OR ³ ) _4-rXr (in the formula, R ³ is a hydrocarbon group, X is a halogen, and r represents a number of 0≦r≦4). Also included are reactive compounds of transition metal compounds such as titanium tetrahalide, alkoxytitanium compounds, aryloxytitanium compounds, alkoxyhalogenated titanium compounds, or aryloxyhalogenated titanium compounds and organomagnesium compounds. On the other hand, in the polymerization reaction, the organometallic compound component that forms the catalyst system together with the carrier-supported Ziegler catalyst is triethylaluminum, tri-n-
Trialkyl aluminum such as n-propyl aluminum, tri-i-butyl aluminum, tri-n-butyl aluminum, tri-n-hexyl aluminum, diethyl aluminum monochloride, di-n-propyl aluminum monochloride, di-i-butyl aluminum monochloride,
Di-n-butylaluminum monochloride, di-
Dialkyl aluminum monohalides such as n-hexyl aluminum monochloride, ethyl aluminum dichloride, n-propylaluminum dichloride, i-butyl aluminum dichloride,
Alkylaluminum dihalides such as n-butylaluminum dichloride and n-hexylaluminum dichloride, ethylaluminum sesquichloride, r-propylaluminum sesquichloride, i-butylaluminum sesquichloride, n
Examples include organoaluminum compounds such as -butylaluminum sesquichloride and n-hexylaluminum sesquichloride, as well as organometallic compounds such as zinc. These organometallic compounds may be used alone or in combination of two or more. A relatively high molecular weight ethylene-α olefin copolymer A obtained by a normal medium-low pressure polymerization method using such a catalyst and a relatively low molecular weight ethylene-α olefin copolymer A
When mixing olefin copolymer B to obtain the composition of the present invention, (1) (degree of short chain branching of copolymer A)/(degree of short chain branching of copolymer B) is 0.6 or more;
Copolymers A and B having a short chain branching degree of more preferably 0.8 or more, most preferably 1.0 or more
It is important to select from the viewpoint of mechanical strength.
On the other hand, regarding transparency, (degree of short chain branching of copolymer A)/(degree of short chain branching of copolymer B) is 0.6 or more and 1.7
It is important that: (Short chain branching degree of copolymer A)/(short chain branching degree of copolymer B) is 0.6
If it is less than 1.7, it is undesirable to use less than 1.7 because it may become difficult to maintain the mechanical strength of the resulting composition, or in the case of a film, it may become difficult to maintain the balance in the longitudinal and lateral directions, the heat sealing properties may deteriorate, and the film may become sticky. This is not preferred because the transparency of the resulting composition deteriorates. (2) (Intrinsic viscosity number of copolymer A)/(Intrinsic viscosity number of copolymer B) is 1.5
Copolymer A and copolymer B so that the ratio is 5.2 or more, more preferably 2.5 or more and 5.2 or less.
It is important to choose. (Intrinsic viscosity number of copolymer A)/(Intrinsic viscosity number of copolymer B) is 1.5
Below this, the melt flow ratio will not increase and processability will deteriorate, which is not preferable. (3) Furthermore, the density of the resulting composition is preferably 0.910 g/cm ³ or more and 0.940 g/cm ³ or less, more preferably 0.915 g/cm ³ or more and 0.929 g/cm ³ or less. If the density is less than the lower limit, the mechanical strength of the composition will decrease or the film will become sticky, which is undesirable, while if it exceeds the upper limit, the transparency will deteriorate, which is undesirable. (4) Furthermore, the melt index of the resulting composition is preferably 0.02 g/10 minutes or more and 50 g/10 minutes or less, more preferably 0.05 g/10 or more and 40 g/10 minutes or less, and 0.1 g/10 minutes or less. It is most desirable that the amount is at least 30 g/10 minutes. Further, the melt flow ratio is preferably 35 or more and 250 or less, more preferably 35 or more and 200 or less, and most desirably 35 or more and 150 or less.
Further, the product of the melt index and the melt flow ratio is preferably 4 or more, and more preferably 7 or more. If the melt index or melt flow ratio is below the lower limit, the extrusion processability will deteriorate, which is undesirable. If the melt index or melt flow ratio exceeds the upper limit, the stability of the bubble during inflation processing may be lacking,
This is not preferable because the mechanical strength decreases. In order to provide a composition with excellent processability and mechanical strength, which is a feature of the present invention, it is important to appropriately balance the melt index and melt flow ratio; the lower the melt index, the lower the melt flow ratio. must be large, and this constraint is expressed as the product of melt index and melt flow ratio. For example, in the case of a composition with a melt index of about 1 g/10 min, even if the melt flow ratio is about 50 to 60, the melt index is 0.05, which has the same processability as high-pressure polyethylene of the same melt index.
For compositions with a melt flow ratio of about 50 g/10 min, processability deteriorates extremely and a melt flow ratio of 80 or more is required. The melt index and melt flow ratio of such compositions are appropriately set based on the requirements of the final use of the composition, but their adjustment depends on the relative high temperature used to obtain the composition. Intrinsic viscosity numbers and (weight average molecular weight)/(number average molecular weight) values of ethylene-α-olefin copolymer A with a relatively low molecular weight and ethylene-α-olefin copolymer B with a relatively low molecular weight and copolymer A This is determined by the mixing ratio of polymer B. Copolymer A
and copolymer B, respectively [η]A
(dl/g), [η]B(dl) mixing ratio (weight fraction W _A ,
When W _B (W _A + W _B = 1), the intrinsic viscosity number [η] + (dl/g) of the composition obtained by mixing is approximately as follows: [η] T≒ [η] _A W _A + [η] The melt index is determined by _B W _B , and the melt index is almost uniquely determined by this [η] _T. On the other hand, the melt flow ratio generally increases as the value of [η] _A / [η] _B increases, but since it depends on W _A and W _B , it is difficult to express it unambiguously. [η] _A , [η] _B , W _A ,
Determine W _B. (5) In order to obtain a composition that satisfies the above (1), (2), (3), and (4), the mixing ratio of copolymer A and copolymer B should be 70% by weight or more than 10% by weight of copolymer A. % or less copolymer B90
Less than or equal to 30% by weight is preferred, and the copolymer
A: 20% by weight or more and 65% by weight or less Copolymer B: 80% by weight
It is more preferably 35% by weight or less, and most preferably 30% to 60% by weight of copolymer A, and 70% to 40% by weight of copolymer B.
The mixing ratio of the copolymers is appropriately selected depending on the degree of short chain branching, density, intrinsic viscosity, and molecular weight distribution of the copolymers A and B used, as well as the density, melt index, and melt flow ratio of the target composition. However, if the proportion of copolymer A is below the lower limit and the proportion of copolymer B is above the upper limit, the resulting composition
ESCR, impact strength, tear strength, and cold resistance are inferior, which is a feature of the present invention (degree of short chain branching of copolymer A)/
High strength is achieved by making (short chain branching degree of copolymer B) 0.6 or more.
It is not preferable to set the value to be 0.6 or more and 1.7 or more because the transparency, etc. that would otherwise be achieved is difficult to achieve. If the proportion of copolymer A exceeds the upper limit and the proportion of copolymer B falls below the lower limit, the processability of the resulting composition will deteriorate, which is not preferred. It should be noted that, unless departing from the spirit of the present invention, the mixing of each of the relatively high molecular weight ethylene-α olefin copolymer A and the relatively low molecular weight ethylene-α olefin copolymer B is limited to one type each. There is no reason why, for example, two or more ethylene-α-olefin copolymers having characteristics in line with the gist of the present invention may be used as relatively high-molecular-weight ethylene-α-olefin copolymer A, and relatively low-molecular-weight ethylene-α-olefin copolymers A. Similarly, two or more types of ethylene-α-olefin copolymers may be used as the certain ethylene-α-olefin copolymer B. In the present invention, there are no particular restrictions on the mixing method for producing the polyethylene resin composition, and any known method can be used. For example, after producing copolymer A and copolymer B individually, batch melt-kneading methods using two rolls or a Banbury mixer, CIM (manufactured by Japan Steel Works) or FCM (manufactured by Shindo Steel Works) can be used.
A continuous melt-kneading method using a twin-screw kneader or a single-screw extruder such as Copolymer A and Copolymer B can be dissolved separately or together in a solvent, and after mixing, the solvent is removed to obtain a mixture. Mixing methods are common. In particular, when copolymers A and B are obtained by high-temperature solution polymerization, it is advantageous in terms of the process to mix copolymers A and B in a high-temperature solution state and then remove the solvent to obtain a composition. It is also possible to mix by a method called two-stage polymerization or multi-stage polymerization. In this method, for example, after polymerizing for a certain period of time under polymerization conditions that yield copolymer A, only the polymerization conditions are changed so that copolymer B can be obtained using the same catalyst. This is a method of mixing by polymerizing until the mixing ratio is reached. In this case, copolymers A and B may be polymerized in any order. When such a two-stage or multi-stage polymerization method is used, copolymer A and copolymer B are easily molecularly dispersed, so that it is an ideal mixing method. In any case, various mixing methods that provide a uniform composition can be employed depending on the purpose. When the polyethylene-based resin composition of the present invention thus obtained is subjected to extrusion molding or injection molding, it is a low-density ethylene-α-olefin copolymer (usually linear low-density polyethylene,
It has significantly better processability than LLDPE (also known as LLDPE), and is comparable to high-pressure polyethylene.It also has good mechanical strength, such as ESCR, expansion force, impact strength, tear strength, and cold resistance. This makes it possible to reduce the wall thickness of molded products, making them suitable for a wide range of applications. Various additives commonly used in the industry, such as oxidation stabilizers, lubricants, antiblocking agents, antistatic agents, light stabilizers, and coloring pigments, can be added to the composition of the present invention, as necessary. It is also possible to blend small amounts of other polymeric compounds without departing from the spirit of the invention. Next, definitions of physical property values used in the present invention are shown below. (1) Intrinsic viscosity number means [η] of tetralin at 135℃. [η] = 11.65 × log R R = t/to t: Number of seconds of falling at a concentration of 0.2 dl/g to: Number of seconds of falling of only tetralin (2) Density According to the method specified in JIS-K-6760. However, if copolymer B (low molecular weight component) has a high degree of short chain branching, it will be treated as a low-density product, and according to the regulations, it will be necessary to perform annealing at 100°C for 1 hour. The specifications for high-density products were uniformly followed (annealing at 100°C for 1 hour was not performed). (3) Short chain branching degree: Using the ^C14 labeled product described in the following literature:
Obtained using FT-IR difference spectrum method. [“Characterization and Physical Properties of Polymers” Published by Kagaku Doujin (Kagaku Special Issue 43) Edited by Mitsuru Nagasawa et al. Published July 10, 1971, P, 131-P, 146] Quantitative formulas for each branch type are shown.

[Table] K7.25μ (extinction coefficient) is determined by the difference spectrum method using an ethylene polymer with almost the same molecular weight distribution and the same [η] as the sample as a reference. The influence of the terminal methyl group was excluded. α-Olefin R-CH=CH If R in CH ₂ is a straight-chain alkyl group, the number of methyl groups at the branched end - CH ₃ /
If 1000C represents the degree of short chain branching and R is a branched alkyl group, for example, if the component olefin is 4-methylpentene-1, the branch will be an i-butyl branch, and a short chain branch will be formed with half the number of methyl groups at the branch end. degree. (4) Melt Index (MI) According to the method specified in ASTM-D1238 Condition E. (5) Melt flow ratio (MFR) Under ASTM-D1238 condition F, first MI _21.6 (load 21.6
Kg (expressed in grams per 10 minutes at 190°C). Melt flow ratio = MI _21.6 / MI (MFR) (6) Rigidity (expressed in Olzen bending stiffness) Conforms to ASTM D747. Pressing conditions: ASTM-DI898C test piece: 25 x 70 x 1 mm thickness Span distance: 25 mm Measurement temperature: 20°C (7) Impact properties Tensile impact strength Conforms to ASTM-D1822 regulations. Pressing conditions: ASTM D1898C method Test piece: S-shaped dumbbell, 1mm thickness Annealing: Boiling water for 1 hour Measurement temperature: 20℃ (8) Molecular weight distribution ( _W / _O ) GPC method (gel permeation chromatography) Toyo Soda HLC-811 Column: TSK-GEL (GMSP+G7000H ₄ +
GMH x 2) Solvent: 1,2,4-trichlorobenzene (TCB) Temperature: 145℃ Detector: Differential refractometer Flow rate: 1mlt/min Concentration: 15mg/10c.c.TCB Measurement for standard polystyrene sample The data is shown below.

[Table] (9) Environmental stress cracking resistance (ESCR) As specified by ASTM D1693. Displayed in F ₅₀ (hr) (However, Antarox-CO630 concentration: 10 wt% Sample specifications: 3 mm x 0.5 mm notch) (10) Chlorine water resistance Test liquid: 0.2% chlorine water Liquid amount: For pressed sample Amount to reach 1.2mg/ ^cm2 (replace daily) Temperature: 40℃ Evaluation: Perform a 10-step evaluation on the sample after a certain period of time. 1: Good 10: “Blistering” occurs on the entire surface (11) Transparency (Haze value) Pressing conditions: 180℃ x 10 minutes, rapidly cooled in ice water Specifications: 100μ thickness Haze measurement: Internal haze (12) Brabender Torque Using Lavender Plastograph Jacket: W50 type (filling amount 45g) Temperature: 190℃ Rotor rotation speed: 60rpm Displays the torque after 30 minutes in kg-m. (13) Spiral flow length Injection molding machine: Nikko 5oz injection molding machine Mold: Spiral mold (7.5mmφ semicircle, 2000mm
Length) Molding conditions: Resin temperature 250℃ Mold temperature 40℃ Injection pressure 840Kg/cm Perform injection molding under ^two molding conditions and measure the spiral flow length. Next, the present invention will be explained in detail using Examples, but the present invention is not limited to the Examples unless the gist of the invention is exceeded. Example 1 (1) Synthesis of organomagnesium compound 500 equipped with a stirrer, reflux condenser, and dropping funnel
16.0 g of ground magnesium for Grignard was placed in a 4-neck ml flask, and the system was sufficiently purged with nitrogen to remove air and moisture. A dropping funnel was charged with 68 ml (0.65 mol) of n-butyl chloride and 300 ml of n-butyl ether, and about 30 ml of the mixture was added dropwise to the magnesium in the flask to start the reaction. After the reaction started, the dropwise addition was continued at 50°C for 4 hours.
After the dropwise addition was completed, the reaction was continued for an additional 1.5 hours at 60°C.
Thereafter, the reaction solution was cooled to room temperature, and unreacted magnesium was separated using a glass filter. When n-butylmagnesium chloride in this n-butyl ether was hydrolyzed with 1N sulfuric acid and the concentration was determined by back titration with 1N sodium hydroxide (using phenolphthalein as an indicator), the concentration was 1.96 mol. / It was. (2) Synthesis of solid catalyst component A 500 ml four-necked flask equipped with a stirrer, dropping funnel, and thermometer was sufficiently purged with nitrogen to remove air and room air. 130ml of n-butyl ether solution of n-butylmagnesium chloride synthesized in (1)
30 ml (0.26 mol) of silicon tetrachloride was added dropwise to (0.26 mol) from a dropping funnel at 50℃ over 2 hours, and then 60℃
The reaction was continued for an additional hour. The produced white solid was separated, washed with n-heptane, and dried under reduced pressure to obtain 31.5 g of a white solid. 100ml of 10g of this white solid
The mixture was placed in a four-neck flask, immersed in 50 ml of titanium tetrachloride, and reacted at 100°C for 1 hour with stirring. After the reaction was completed, the product was washed with n-heptane, and the washing was repeated until no titanium tetrachloride was observed in the washing solution, followed by drying under reduced pressure to obtain 7.9 g of a solid catalyst component. 14 mg of titanium atoms were supported per 1 g of this solid catalyst component. Example 2 Ethylene-α olefin copolymer A in Example 1
Polymerization was carried out using organoaluminum compounds as catalysts and cocatalysts produced by the method and varying the type of α-olefin and polymerization conditions as shown in Table 1. The density, intrinsic viscosity number, short chain branching degree, and (weight average molecular weight)/(number average molecular weight) of the obtained ethylene-α olefin copolymer are also shown in Table 1. These are provided in the examples below as a component of the mix.

[Table] Example 3 Ethylene-α-olefin copolymer B in Example 1
Polymerization was carried out using the catalyst produced by the above method and an organoaluminum compound as a co-catalyst, while changing the type of α-olefin and polymerization conditions as shown in Table 2. The density, intrinsic viscosity, short chain branching degree, and (weight average molecular weight)/(number average molecular weight) of the obtained ethylene-α olefin copolymer are also shown in Table 2. These are provided in the examples below as a component of the mix.

[Table] Example 4 Ethylene-α-olefin copolymer A in Example 1
Polymerization was carried out using an organoaluminum compound as the catalyst and cocatalyst produced by the method, and changing the type of α-olefin and polymerization conditions as shown in Table 3. The density, intrinsic viscosity number, short chain branching degree, and (weight average molecular weight)/(number average molecular weight) of the obtained ethylene-α olefin copolymer are also shown in Table 3. These are provided in the examples below as a component of the mix.

[Table] Example 5 Ethylene-α-olefin copolymer B in Example 1
Polymerization was carried out using the catalyst produced by the method and an organoaluminium compound as a co-catalyst, while changing the type of α-olefin and polymerization conditions as shown in Table 4. The density, intrinsic viscosity number, short chain branching degree, and (weight average molecular weight)/(number average molecular weight) of the obtained ethylene-α olefin copolymer are also shown in Table 4. These are provided in the examples below as a component of the mix.

[Table] Example 6 Using the catalyst obtained in Example 1 and triethylaluminum as a co-catalyst, polymerization was carried out for 90 minutes under the polymerization conditions in the first stage as shown in Table 5, and then the polymerization conditions (H ₂ Only the partial pressure (partial pressure and ethylene partial pressure) were changed as shown in Table 5 and polymerization was continued for 123 minutes.
The ethylene/butene-1/hydrogen molar ratio of the liquid phase was kept constant during both the first and second stages of polymerization. The amount of polymerization in the first and second stages was determined from the amount of ethylene feed. The composition was approximately 45% by weight of high molecular weight components and 55% by weight of low molecular weight components. Immediately before the end of the polymerization in the first stage, a portion of the produced polymer was extracted and subjected to measurement of the density, intrinsic viscosity, degree of short chain branching, and (weight average molecular weight)/(number average molecular weight) of the polymer obtained in the first stage. Furthermore, the same measurements were performed on the hole polymer obtained through the first and second stages, and the values of the intrinsic viscosity and short chain branching degree of the polymer produced in the second stage were calculated from the values of the first stage polymer and the whole polymer. This value is also shown in Table 5. The density of the final hole polymer was 0.920g/
^cm3 , melt index 0.7g/10min, melt flow ratio 65, intrinsic viscosity 1.6dl/g, short chain branching degree 25
It was hot. Using the obtained whole polymer, fluidity and solid state physical properties were measured. The results are shown in Table 9. In the following examples, a method for mixing a relatively high molecular weight ethylene-α olefin copolymer A and a relatively low molecular weight ethylene-α olefin copolymer B is shown below. (a) Mixing using a Banbury kneader (hereinafter referred to as Banbury mixing) Copolymer A and Copolymer B are mixed at a predetermined weight ratio to give a total amount of 1.0 kg. This is mixed in a Banbury kneader with a rotor speed of 150~
Knead for 5 minutes at 230 rpm. Perform sufficient nitrogen substitution to ensure that the resin temperature does not exceed 250°C. (b) Mixing in a solution state (hereinafter abbreviated as solution mixing) Copolymer A and copolymer B were mixed at a predetermined weight ratio to make a total amount of 100 g. Charge this into autoclave 2. xylene 2 as solvent
The mixture was charged, the temperature was raised to 200°C under stirring, and the solution was blended for 1 hour. Thereafter, it is cooled to below the boiling point, precipitated in methanol 10, and dried for 48 hours in a vacuum dryer at a temperature of 80°C to obtain a composition.

【table】

[Table] Example 7 Using the catalyst obtained in Example 1 and triethylaluminum as a co-catalyst, polymerization was carried out for 100 minutes under the polymerization conditions in the first stage as shown in Table 6, and then the polymerization conditions (H ₂ min. pressure and ethylene partial pressure).
Polymerization was continued for 150 minutes with changes as shown in the table.
The ethylene/butene-1/hydrogen molar ratio of the liquid phase was kept constant during both the first and second stages of polymerization. The amount of polymerization in the first and second stages was determined from the amount of ethylene feed. The composition was approximately 50% by weight of high molecular weight components and 50% by weight of low molecular weight components. Immediately before the end of the polymerization in the first stage, a portion of the produced polymer was extracted and subjected to measurement of the density, intrinsic viscosity, degree of short chain branching, and (weight average molecular weight)/(number average molecular weight) of the polymer obtained in the first stage. Furthermore, the same measurements were performed on the hole polymer obtained through the first and second stages, and the values of the intrinsic viscosity and short chain branching degree of the polymer produced in the second stage were calculated from the values of the first stage polymer and the whole polymer. This value is also shown in Table 6. The density of the final hole polymer was 0.923g/
^cm3 , melt index 0.6g/10min, melt flow ratio 55, intrinsic viscosity 1.10dl/g, short chain branching degree 25
It was hot. The obtained whole polymer was subjected to injection molding and the physical properties of the molded product were measured. The results are shown in Table 10.

【table】

[Table] Example 8 Ethylene-α olefin copolymer A-1 obtained in Example 2 and ethylene-α obtained in Example 3
Olefin copolymer B-1 was blended at 50% by weight and Banbury kneaded.
A composition having density, MI, and MFR as shown in the table was obtained. The physical properties of this composition are also shown in Table 7. Table 7 shows conventional high-pressure polyethylene (commercial product: Sumikasen F101-1) for comparison.
Examples of Comparative Example 1 using Sumitomo Chemical Co., Ltd.) and a conventional low-density ethylene-α-olefin copolymer (Comparative Example 2) are shown. As is clear from Table 7, the resin composition of the present invention has lower Brabender torque (superior workability) than high-pressure polyethylene, and is significantly superior in tensile impact strength, ESCR, rigidity, and tensile strength. I know that there is. In addition, it can be seen that the Brabender torque is significantly lower (much better processability) than the conventional low-density ethylene-α-olefin copolymer, and the tensile impact strength and tensile strength are significantly better.

【table】

[Table] Example 9 Ethylene-α-olefin copolymer A'-1 obtained in Example 4 and ethylene-α-olefin copolymer A'-1 obtained in Example 5
α-olefin copolymer B'-1 was blended at 50% by weight, and Banbury kneading was performed to obtain a composition having the density, melt index, and melt flow ratio shown in Table 8. The physical properties of this composition are also shown in Table 8. For comparison, Table 8 shows conventional high-pressure polyethylene (manufactured by Sumitomo Chemical Co., Ltd., commercially available product: Sumikasen).
Comparative Example 3 using G701) and a conventional low-density ethylene-α-olefin copolymer (Comparative Example 4) are also shown. As is clear from Table 8, the resin composition of the present invention has better fluidity during injection molding than high-pressure polyethylene, and is significantly superior in tensile impact strength, rigidity, ESCR, and tensile strength. In addition, the conventional low density ethylene
It can be seen that the fluidity during injection molding is much better than the α-olefin copolymer, and the tensile impact strength and ESCR are also much better.

【table】

[Table] Examples 10 to 13 Various ethylene-α-olefin copolymers A obtained in Example 2 and various ethylene-α-olefin copolymers B obtained in Example 3 were prepared as shown in Table 9. The composition was adjusted by adjusting the mixing ratio to obtain a composition having density, MI, and MFR as shown in Table 9. The physical properties of this composition are also shown in Table 9. Table 9 shows the results of preparing a similar composition using a two-stage polymerization method (Example 6) and, for comparison, the results of expanding the molecular weight distribution using a conventional method for producing a low-density ethylene-α-olefin copolymer. As a model for this case, examples (Comparative Examples 5, 6, and 7) where the lower molecular weight material has more branches and the higher molecular weight material has fewer branches are also shown. As is clear from Table 9, the composition of the present invention is a composition in which the branching of the high molecular weight substance is more than that of the low molecular weight substance, or almost equal to that of the low molecular weight substance, as is clear from the branching degree distribution index. (see Examples 6 and 10 and Comparative Examples 5 and 6, and also Example 13 and Comparative Example 7), the tensile impact strength and tensile strength are significantly higher than the model composition of the prior art. It turns out to be excellent. In addition, referring to Comparative Example 2 in Table 7 and Comparative Example 5 in Table 9, it is found that the molecular weight distribution (the larger the MFR is, the more the distribution is As the area (are wide) is enlarged, it can be seen that the tensile impact strength and tensile strength decrease significantly.

【table】

[Table] Examples 14 to 16 Various ethylene-α-olefin copolymers A obtained in Example 4 and various ethylene-α-olefin copolymers B obtained in Example 5 were prepared as shown in Table 10. The composition was adjusted by adjusting the mixing ratio to obtain a composition having the density, melt index, and melt flow ratio shown in Table 10. The physical properties of this composition are also shown in Table 10. Table 10 shows the results of preparing a similar composition using a two-stage polymerization method (Example 7) and, for comparison, the results of expanding the molecular weight distribution using the conventional method for producing low-density ethylene-α-olefin copolymers. Examples (Comparative Examples 8, 9, and 10) in which a lower molecular weight substance has more branches and a higher molecular weight substance has fewer branches are also shown as models for this case. As is clear from Table 10, the composition of the present invention has more branches in the high molecular weight body and less branching in the low molecular weight body, as is clear from the branching degree index. (Example 7, 14,
(See Example 15 and Comparative Examples 8 and 9, and see Example 16 and Comparative Example 10) It is found that the tensile impact strength, ESCR, and tensile strength are significantly superior to the prior art model compositions. In addition, referring to Comparative Example 4 in Table 8 and Comparative Example 9 in Table 10, it is found that the conventional method for producing low-density ethylene-α-olefin copolymers has a high molecular weight distribution (large melt flow) while keeping the density and melt index the same. It can be seen that the tensile impact strength, ESCR, and tensile strength decrease over a wide range (the distribution is wide).

【table】

[Table] Examples 17 to 19 Various ethylene-α-olefin copolymers A obtained in Example 2 and various ethylene-α-olefin copolymers B obtained in Example 3 were prepared as shown in Table 11. The composition was adjusted by adjusting the mixing ratio to obtain a composition having density, MI, and MFR as shown in Table 11. The physical properties of this composition are also shown in Table 11. In addition,
For comparison, we used an example of conventional high-pressure polyethylene (Comparative Example 1) and a model for expanding the molecular weight distribution using the conventional method for producing low-density ethylene--olefin copolymers. An example where the higher the molecular weight, the less branching (Comparative Example 11) and an example where the intrinsic viscosity of the low molecular weight component is too small even if the branching degree distribution index is in accordance with the gist of the present invention (Comparative Example 12; Example 18
) are also shown in Table 11. As is clear from Table 11, if the branching degree distribution index is selected, the transparency will be as good as that of high-pressure polyethylene, and the tensile impact strength and tensile strength will be significantly superior to that of high-pressure polyethylene. I understand. Furthermore, referring to Example 18 and Comparative Example 12, it can be seen that if the intrinsic viscosity of the low molecular weight component is too small, the tensile impact strength and transparency are adversely affected.

【table】

[Table] Examples 20 to 22 Various ethylene-α-olefin copolymers A obtained in Example 4 and various ethylene-α-olefin copolymers B obtained in Example 5 were prepared as shown in Table 12. The composition was adjusted by adjusting the mixing ratio to obtain a composition having the density, melt index, and melt flow ratio shown in Table 12. The physical properties of this composition are also shown in Table 12. In addition, as a comparative example, a low molecular weight An example of a case where the molecular weight substance has more branches and a higher molecular weight substance has less branching (Comparative Example 13), and an example where the intrinsic viscosity of the low molecular weight component is too small even if the branching degree distribution index is in accordance with the gist of the present invention. Example (Comparative Example 14; see Example 21) is also included in the 12th
Shown in the table. As is clear from Table 12, if the branching degree distribution index is selected, the transparency will be as good as that of high-pressure polyethylene, and the tensile impact strength, tensile strength, and ESCR will be far superior to high-pressure polyethylene. I know that there is. Furthermore, referring to Example 12 and Comparative Example 14, it can be seen that if the intrinsic viscosity of the low molecular weight component is too small, it affects the tensile impact strength and transparency.

【table】

[Table] Comparative example 1 Commercially available high-pressure polyethylene (Sumikasen
F101-1 (manufactured by Sumitomo Chemical Co., Ltd.) was used for a series of physical properties and blow molding. The results are shown in Tables 7 and 11. Comparative Example 2 Under polymerization conditions as shown in Table 13 using the catalyst produced in Example 1 and triethylaluminum as a cocatalyst, low density ethylene of the prior art was
An α-olefin copolymer was obtained. The density of the obtained copolymer is 0.920 g/cm ³ , MI is 1.0 g/10 min, MFR
was 30. The physical properties of this copolymer were measured and the results are shown in Table 7.

[Table] Comparative example 3 Commercially available high-pressure polyethylene Sumikasen G701
(manufactured by Sumitomo Chemical Co., Ltd.) and subjected to a series of physical properties and injection molding. The results are shown in Tables 8 and 12. Comparative Example 4 A conventional low-density ethylene-α-olefin copolymer was obtained using the catalyst produced in Example 1 and triethylaluminum as a co-catalyst under the polymerization conditions shown in Table 14. The density of the obtained copolymer is
The melt index was 0.924 g/cm ³ and the melt flow ratio was 30. The physical properties of this copolymer were measured and the results are shown in Table 8.

[Table] Comparative Examples 5, 6, 7, 11 Various ethylene-α-olefin copolymers A obtained in Example 2 and various ethylene-α-olefin copolymers B obtained in Example 3 are shown in Table 9. Alternatively, as a model when the molecular weight distribution is expanded using the conventional method for producing low-density ethylene-α-olefin copolymers using the mixing ratio shown in Table 11, the lower the molecular weight, the more branched, and the higher the molecular weight, the more branched. A composition having a density, MI, and MFR as shown in Table 9 or Table 11 was prepared. The physical properties of this composition are shown in Table 9 or Table 11. Comparative Example 12 Various ethylene-α-olefin copolymers A obtained in Example 2 and various ethylene-α-olefin copolymers B obtained in Example 3 were mixed at the mixing ratio shown in Table 11 to adjust the degree of branching. Even if the distribution index is in accordance with the gist of the present invention, the composition in which the intrinsic viscosity index of the low molecular weight component is too small is adjusted to create a composition having the density, MI, and MFR as shown in Table 11. Obtained. The physical properties of this composition are also shown in Table 11. Comparative Examples 8, 9, 10, 13 Various ethylene-α olefin copolymers A obtained in Example 4 and ethylene-α obtained in Example 5
As a model, when the molecular weight distribution is expanded using the conventional method for producing low-density ethylene-α-olefin copolymers with olefin B at the mixing ratio shown in Table 10 or Table 12, the lower the molecular weight, the higher the molecular weight. , the higher the molecular weight, the less branching there is. The composition was adjusted to obtain a composition having the density, melt index, and melt flow ratio as shown in Table 10 or Table 12. The physical properties of this composition are shown in Table 10 or
Shown in Table 12. Comparative Example 14 The various ethylene-α-olefins A obtained in Example 4 and the various ethylene-α-olefins B obtained in Example 5 were mixed in the proportions shown in Table 12 to achieve a branching degree distribution index of the present invention. Even if the main idea was followed, the composition was adjusted when the intrinsic viscosity of the low molecular weight component was too small, and a composition having the density, melt index, and melt flow ratio as shown in Table 12 was obtained. . This composition is also shown in Table 12. Reference Example 1 Using the catalyst of Example 1 and diethylaluminum monochloride as a co-catalyst, ethylene and butene-1 were copolymerized under the polymerization conditions shown in Table 15.
Samples with the specifications shown in Table 16 were obtained. The sample was subjected to molecular weight fractionation using a column fractionation method, and the distribution of the degree of short chain branching relative to the molecular weight was determined, as shown in FIG.

【table】

[Table] In the column fractionation method, approximately 5 g of the sample was deposited on Celite 745 as a carrier in xylene, and then packed into a column. Next, the column was heated to 130°C, and the mixing ratio of butylcellosol-xylene was changed to gradually increase the dissolving power while flowing into the column.
Separation was performed from low molecular weight to high molecular weight. Methanol was added to the flow liquid as a precipitant, and the polymer was recovered and dried under reduced pressure to obtain each fraction. In addition, Irganox 1076 was added as a stabilizer to prevent polymer decomposition during column fractionation operation.
100 ppm was added to the original sample, and N ₂ gas was flowed through the column to block oxygen. Press sheets (approximately 100 to 300 microns thick) were prepared using each of the obtained fractions, and the degree of short chain branching was determined by Fourier transform infrared absorption spectrum measurement. On the other hand, the molecular weight ( ) of each fraction obtained was determined from the intrinsic viscosity number ([η]) measured in tetralin at 135° C. from the following relational expression. [η] = 5.1×10 ^-4・n ^{0.725Reference} Example 2 Melt index (MI) of ethylene-α-olefin copolymer produced by conventional technology
The relationship between this and the tensile impact strength was determined using the melt flow ratio as a parameter, and is shown in FIG. It can be seen that when the molecular weight distribution becomes wider (indicated by the value of melt flow ratio (MFR) in the figure, the larger the melt flow ratio, the wider the molecular weight distribution), the tensile impact strength decreases significantly. When these ethylene-α-olefin copolymers were subjected to molecular weight fractionation using the same method as in Reference Example 1, all of them showed the same tendency as in Reference Example 1, with 50% by weight of low molecular weight components and 50% by weight of high molecular weight components. As a result of conveniently calculating (degree of short chain branching of high molecular weight component)/(degree of short chain branching of low molecular weight component) when dividing into two categories where the molecular weight component is close to 50% by weight, which sample The value was also less than 0.5. Reference Example 3 The correlation between the melt index (MI) and the limiting viscosity ([η]) of the resins was determined for the conventional high-pressure polyethylene and the medium-low pressure linear high-density polyethylene, and is shown in Figure 3. Indicated. The relationship between the melt index and the intrinsic viscosity of high-pressure polyethylene and linear high-density polyethylene is shown in the figure. They were clearly differentiated along the dashed-dotted dividing line, and high-pressure polyethylene showed a tendency to have a significantly smaller intrinsic viscosity than linear high-density polyethylene having the same melt index. When the relationship between the melt index and the intrinsic viscosity was determined for the ethylene-α-olefin copolymer of the present invention, all of the examples belonged to the region of linear high-density polyethylene shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a typical example of the distribution of short chain branches with respect to the molecular weight of an ethylene-α-olefin copolymer according to the prior art. FIG. 2 is a diagram showing the relationship between melt index (MI) and tensile impact strength of an ethylene-α-olefin copolymer according to the prior art using melt flow ratio (MFR) as a parameter. Figure 3 shows the melt index (MI) of the resin, which provides a means to distinguish between high-pressure polyethylene and medium-low pressure normal polyethylene.
FIG. 3 is a diagram showing the correlation between In the figure, bordering on the dividing line indicated by a dashed-dotted line,
The left side is a region of high pressure polyethylene of the prior art, and the right side is a region of medium and low pressure normal polyethylene.

Claims (1)

[Claims] 1. The density is 0.895 g/cm ³ or more and 0.935 g/cm ³ or less,
The intrinsic viscosity is 1.2 dl/g or more and 6.0 dl/g or less, and the number of short chain branches per 1000 carbon atoms (short chain branching degree) is 7.
Ethylene with a carbon number of 3 to 18 and α with a carbon number of 3 to 18
Copolymer A with olefin 10% by weight or more 70% by weight
The density is 0.910 g/cm ³ or more and 0.954 g/cm ³ or less, the intrinsic viscosity is 0.3 dl/g or more and 1.5 dl/g or less, and the number of short chain branches per 1000 carbon atoms is 5 or more and 35 or less. of ethylene and α-olefin having 3 to 18 carbon atoms and 90% to 30% by weight of copolymer B, in which case (degree of short chain branching of copolymer A)/(copolymer Copolymer A and copolymer are mixed so that the short chain branching degree of copolymer B) is 0.6 or more, and (intrinsic viscosity number of copolymer A)/(intrinsic viscosity number of copolymer B) is 1.5 or more and 5.2 or less. The density obtained by selecting coalescence B is 0.910 g/ ^cm3 or more and less than 0.935 g/ ^cm3 , and the melt index is 0.02 g/10 minutes or more and 50 g/10 minutes or less,
An ethylene-α olefin copolymer resin composition with excellent strength and a melt flow ratio of 35 or more and 250 or less. 2 (degree of short chain branching of copolymer A)/(copolymer B
The ethylene-α olefin with excellent transparency and strength according to claim 1, wherein copolymer A and copolymer B are selected and mixed so that the short chain branching degree) is 0.6 or more and 1.7 or less. Copolymer resin composition. 3. The ethylene-α olefin copolymer based resin according to claim 1 or 2, wherein (weight average molecular weight)/(number average molecular weight) of copolymer A and copolymer B is 2 or more and 10 or less. Composition. 4 Ethylene-α according to claim 1, 2 or 3, wherein copolymer A and/or copolymer B is an ethylene-butene-1 copolymer
Olefin copolymer resin composition. 5. Ethylene-α olefin copolymer system according to claim 1, 2 or 3, wherein copolymer A and/or copolymer B is an ethylene-4-methylpentene-1 copolymer. Resin composition. 6. Ethylene according to claim 1, 2 or 3, wherein copolymer A and/or copolymer B is an ethylene-hexene-1 copolymer.
α-olefin copolymer-based resin composition.