JPH10316805A - Composition for calendering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene resin material having the same flexibility and calendering processability as those of a soft polyvinyl chloride resin and not causing the migration of a plasticizer, a smell and pollution on incineration. SOLUTION: This composition for calendering comprises (A) high pressure low density polyethylene having a melt index of 0.2-10 g/10 min, a density of 0.915-0.930 g/cm<3> and the main peak value of the DSC melting point in a range of 104-117 deg.C, (B) an ethylene-α-olefin copolymer having a melt index of 0.2-10 g/10 min, a density of 0.86-0.910 g/cm<3> , a Mw/Mn of <=3.0 and the main peak value of the DSC melting point in a range of 40-105 deg.C and produced in the presence of a polymerization catalyst comprising a metallocene catalyst, and (C) at least one kind of lubricant selected from carboxylate esters and having a melting point of 40-110 deg.C, in an A/B weight ratio of 80/20 to 10/90 and in a C/(A+B) weight ratio of (0.2-3)/100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The composition of the present invention is particularly useful as a substitute for a soft vinyl chloride film or sheet. In addition, soft vinyl chloride can be used as a food packaging bag application or coating material that is not used due to problems such as odor and extraction / migration, or as a material for lamination processing with films or sheets of other materials. And a composition of a polyethylene resin. Further, this material can be efficiently processed into a film or a sheet by a calender molding method using a usual calender molding machine.

[0002]

2. Description of the Related Art To date, low-density polyethylene, soft vinyl chloride, and the like are typical examples of inexpensive, flexible, and hard-to-break soft film and sheet materials. Originally, vinyl chloride resin is a hard material.
By mixing as much as 60 parts by weight of plasticizer, very flexible and transparent sheets and films have been produced. However, films and sheets containing a large amount of plasticizer to provide flexibility have the disadvantage that the plasticizer has an odor, and its surface has the disadvantage that the plasticizer gradually migrates and becomes sticky. Is limited. Also,
There is a problem of pollution when this material is incinerated and disposed of, and there is a strong demand for replacement with other non-polluting materials.

[0003] Along with rubber, vinyl chloride resin is the most suitable material for calender molding. A material suitable for calendering is an amorphous resin having a wide processing temperature range and a melt strength in the processing temperature range. On the other hand,
Polyethylene, which is a crystalline resin, has been regarded as a material unsuitable for the calendering method because the viscosity is rapidly lowered by heating. Therefore, almost all of the films and sheets are manufactured by an inflation molding method or a T-die molding method. Further, among the polyethylenes, even the flexible high-pressure low-density polyethylene has limitations in improving the flexibility and transparency. For this reason, softening such as mixing a copolymer of vinyl acetate monomer or ethylene propylene rubber with ethylene has been performed. However, recently, polyethylene having a density lower than 0.915 and excellent in transparency and flexibility has been technically and industrially manufactured, and its practicality has increased as an alternative material to soft vinyl chloride.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to transfer common plasticizers such as phthalic acid ester type and epoxy type used for softening vinyl chloride, odor and pollution during incineration. It is intended to have the same flexibility and calendering processability as soft vinyl chloride by using polyethylene, which is easy to recycle, without any material.

Low-density polyethylene is a material that has been attracting attention from the processing industry that uses calender molding as a substitute for soft vinyl chloride. However, industrial processing of polyethylene by calendering has not been performed, and the present inventors have aimed at making the polyethylene material more flexible and capable of performing calendering easily in order to meet this demand. .

[0006]

SUMMARY OF THE INVENTION The present invention relates to a structure of a polyethylene resin so as to have a flexibility similar to that of soft vinyl chloride, free from migration and odor, and capable of being calendered. As a result of intensive research, at least two types of ethylene resins (A) shown below,
A composition comprising (B) and at least three components of a lubricant (C), wherein (A) / (B) is in the range of 80/20 to 10/90% by weight and the amount of (C) is (A) + 0 for (B).
The present inventors have found that a composition characterized by a content of 2 to 3% by weight can achieve the object, and have reached the present invention.

The component (A) of the present invention has a melt index of 0.2 to 10 g / 10 min, a density of 0.915 to 0.930 g / cm ³ , and a main peak value of the melting point of DSC of 104 to 104. High pressure low density polyethylene in the range of 117 ° C.

(B) has a melt index of 0.2 to
10g / 10min, density 0.86 ~ 0.910g /
It is an ethylene-α-olefin copolymer having a cm ³ , Mw / Mn of 3.0 or less, a DSC main peak value in the range of 40 to 105 ° C., and a metallocene catalyst as a polymerization catalyst.

(C) at least one lubricant selected from carboxylic esters having a melting point in the range of 40 to 100 ° C.

[0010] More specifically, the high-pressure low-density polyethylene (A), which is a component of the present invention, is characterized by having long-chain branches. The production method is such that the polymerization temperature is 130 to 30 using an organic peroxide or oxygen as a polymerization initiator.
It is obtained by subjecting ethylene to radical polymerization under the conditions of about 0 ° C. and a polymerization pressure of 500 to 3000 kg / cm ² . The resin has a melt index value of 0.2 to 10 g / 10 min at 190 ° C. under a load of 2.16 kg according to the ASTM D1238 test method. It is more preferably 0.5 to 7 g / 10 min, particularly preferably 1.5 to 6.0 g / 10 min. If the melt index is low, the spreadability during calendering is poor, and if the melt index is high, the drawdown becomes large. Also, JIS-
The density according to the K7112 test method is 0.915 to 0.930.
g / cm ³ . Particularly preferably 0.915 to
0.925 g / cm ³ . This density is also an index of the crystallinity of the resin.If the density is too low, the practical heat resistance of the film or sheet will be insufficient, and if the density is too high or the long chain branching is small, The required melt viscosity is insufficient. The melting point of the resin is J
It is the value of the main peak of the melting point of DSC when the temperature is raised at a rate of 10 ° C./min by the test method described in IS-K7121, and the form of branching can be estimated from the relationship between the density and this melting point. That is, those having many branches and complicated branching have a lower melting point than the straight-chain linear ones at the same density.
In the present invention, the value of the main peak of the melting point of DSC is 104 to 1
17 ° C range, more specifically, 0.930g density
/ Cm ³ , the main peak value is 117 ° C., and the density is 0.
The main peak value at 915 g / cm ³ is 104 ° C., and the relationship between them is almost linear. These selected characteristic values are also characteristics of the polyethylene having a long chain branch used in the present invention, and indicate that the viscoelasticity of the resin in the molten state in the calendering process is suitable for it.
In addition, by using this polyethylene, the transparency and heat sealing strength of the target product such as a film or sheet, such as heat sealing, are improved, and further, in the secondary processing involving heating, a product obtained by using (B) alone. In this case, the curl phenomenon and shrinkage, which are particularly noticeable when the film is stretched, are also improved.

In the present invention, it is important that the polyethylenes (A) and (B) are well mixed when melt-mixed. From this, it is more preferable that the melting point of the resin (A) is JIS- According to the test method described in K7121
A DSC whose main peak value of the melting point of DSC at a rate of ° C / min is in the range of 105 to 112 ° C is used.

The α-olefin used as a copolymerization monomer of the ethylene-α-olefin copolymer (B) using a metallocene catalyst as a polymerization catalyst as a constituent of the present invention is 4-methylpentene-1, hexene -1 or octene-1. Among them, particularly preferred is octene-1 having a high softening effect in a small amount. The copolymerization amount is 9 to 30% by weight. The type and amount of the monomer determine the density and melting point of the resulting polymer, and even when mixed with the above-mentioned high-pressure method polyethylene, improve flexibility, transparency, calendering workability, etc. without deteriorating its characteristics. Used for The metallocene catalyst referred to here is also called a single-site catalyst or a Kaminski catalyst from the inventor's name.This catalyst has a high polymerization activity for ethylene, sharpens the molecular weight distribution of the polymer, and improves the crystallinity. Enhance. The index of this distribution is Mw / Mn
(The ratio of the weight average molecular weight Mw to the number average molecular weight Mn). If this value exceeds 3, the workability of the film or sheet intended for the present invention and the heat resistance, solvent resistance, extraction resistance and the like in the use thereof will be reduced. The value of Mw / Mn is more preferably in the range of 2.0 to 3.0. Also, in the present invention, 190
° C, melt index of 2.16 kg load is 0.2 ~
The density according to the JIS-K7112 test method is 0.86 to 0.910 g / cm ³ , and the melting point of the resin is 10 ° C./min according to the test method described in JIS-K7121.
A DSC whose main peak value of the melting point of the DSC when heated at a rate of min is in the range of 40 to 105 ° C is used. The density and the melting point have a substantially linear relationship. If the melt index of the polymer used is low, the bank stability and spreadability during calendering are inferior, and if it is high, the drawdown becomes large. The density substantially indicates the crystallinity of the resin, and a resin having a low value does not have a melting point and the film or sheet is easily blocked. Higher ones have less flexibility,
In addition, the stability of the bank on the roll during calendering is deteriorated. From the above, a more preferable value is
The melt index is 0.5 to 7 g / 10 min, the density is 0.87 to 0.89 g / cm ³ , and the main peak value of the melting point of DSC is in the range of 50 to 100 ° C.

The combination of the two polyethylenes is important in calenderability, and the weight ratio of the two is particularly in the range of (A) / (B) = 80/20 to 10/90% by weight, and more preferably (A / B). A) / (B) = 60 / 40-2
0/80% by weight. If (A) is more than this range, the condition width during calendering becomes narrow, and machining becomes difficult. Even when the content of (B) is large, the stability at the time of processing is similarly deteriorated. Further, the combination is determined not only by the ratio but also by many factors such as the characteristics of the respective resins, the melt index to be combined, the density, the melting characteristics, the processing equipment and the processing conditions, and accordingly adjustment may be required in some cases.
A particularly preferred combination of (A) and (B) is (A) /
(B) = 70/30 to 30/70% by weight;
This is a so-called completely compatible state where the peak of the melting point of the DSC of the mixture obtained by melt-mixing the two is almost one, and the peak of the crystallization temperature is almost one.
Also, some adjustment is required depending on the type and amount of the lubricant having the effect of improving processability.

Next, at least one lubricant selected from carboxylic esters having a melting point of (C) in the range of 40 to 100 ° C., more preferably 50 to 85 ° C., generally means an external lubricating effect. Specific examples thereof include aliphatic carboxylic acids such as acrylic acid, crotonic acid, isocrotonic acid, fumaric acid, maleic acid, succinic acid, and aconitic acid, and oxycarboxylic acids such as lactic acid, malic acid, tartaric acid, and citric acid. Acid and myristyl alcohol having 14 to 22 carbon atoms,
Aliphatic alcohols such as palmityl alcohol, stearyl alcohol, behenyl alcohol, 12 hydroxystearyl alcohol, or ethylene glycol,
Esters with aliphatic polyhydric alcohols such as glycerin, and succinic saturated fatty acid monoglyceride and citric acid saturated fatty acid monoglyceride of these complex compounds are listed. Among them, particularly preferred is an ester using citric acid as the carboxylic acid as a material having a good balance between the affinity for the polyethylene resin and the external lubricating effect (removability from the metal roll).

These are not only used alone but also when used in combination, and are highly effective. These raw materials, carboxylic acids and alcohols, are generally made from animal and plant fats and oils, and thus are industrially purified but sold as a mixture instead of a single fatty acid. The lubricant used in the present invention is also a mixture obtained from them, and does not cause any problem.

It is important that the temperature and the range of the melting point of the selected lubricant are equal to or lower than the melting point of the polyethylene (A), and equal to or higher than that of the polyethylene (B). The action of these lubricants is
It enhances the slip property of the molten resin with respect to the mixing roll and the calender roll to stabilize the bank, and also prevents the resin from adhering to various metal rolls such as an annealing roll, a stretching roll, and a take-up roll of the mixing roll and the calender. Furthermore, blocking of the wound film or sheet is prevented. In addition, the use of well-known metal soaps as a supplement also increases the effect.

At this time, if the melting point of the lubricant is too low, for example, if the lubricant is liquid at normal temperature, it tends to bleed on the surface of the film or sheet as a product, and it is not preferable because it is liquid at normal temperature.

The compounding amount of these lubricants is the above (A) +
(B) 0.2 to 3% by weight, more preferably 0.1 to 3% by weight.
5 to 1.5% by weight. If the amount is less than this, the effect is insufficient, and if the amount is too large, bleeding or blooming is easily caused, and the physical properties of the product are reduced.

Next, an average particle diameter of 7
10% by weight or less of an inorganic filler having a particle diameter of not more than 10%, more preferably 5% or less, having an average particle diameter of not more than 5 microns. By blending this inorganic filler, the surface of the film or sheet which is a product when the composition of the present invention is calendered becomes rough, and the contact area is reduced, so that the product has no slimy feeling and the matte effect To prevent blocking and to make it translucent or matte, and there are many applications where these properties are practically required. Well-known inorganic fillers are effective in meeting these requirements. As a specific example, carbon black is effective if it is black. In the white color, silica, calcium carbonate, talc, hydrotalcite, titanium oxide, aluminum hydroxide, magnesium hydroxide and the like are used. In order to obtain the desired effect by mixing these, it is necessary to select the particle size and amount. Since the thickness of the film or sheet is small, it is inconvenient if the particle size of the filler is large. On the other hand, if the amount is large, the reinforcing effect is exerted, and the desired softening is hindered.

In addition to the composition of the present invention, it is well known as an antioxidant for preventing thermal deterioration during processing of the resin and subsequent deterioration due to oxidation, as a common-sense additive to polyethylene resin. Heat stabilizers such as benzophenone-based UV absorbers and benzotriazole-based UV absorbers that are well known as phenolic antioxidants, phosphoric acid antioxidants, or UV absorbers for preventing deterioration from ultraviolet rays A light stabilizer, a foaming agent, or the like can be added to achieve the effect.

In the composition of the present invention, the respective components may be melt-mixed in the calendering process described below. However, in order to enhance the melt-mixing efficiency in the calendering process described below, the components are melt-mixed homogeneously in advance and pelletized. Is more preferred.

Next, the calender molding method will be briefly described. The calendering machine used for processing the composition of the present invention into a film or a sheet is a known general machine. Usually, a melt mixer such as a Banbury mixer, an intensive mixer, or an extruder for melting the resin is provided in order to hang the resin on a calender roll, and the resin, the additive, or the resin composition thereof is melt-mixed. Next, the melt is transferred to a mixing roll (receiving roll) to store a certain amount of the melt, and then transferred to the next mixing roll (supply roll) in an appropriate amount. Further, an appropriate amount of resin is supplied to the calender roll from the supply roll. The calender roll is usually composed of three to six rolls, and plays a role of gradually spreading the supplied resin into a film or sheet shape. It consists of a series of mechanical devices that wind the film or sheet formed here from a take-off roll through an annealing roll or a cooling / stretching roll. However,
In some cases, the steps of the receiving roll and the supply roll are omitted and used. Normally, in the case of shrink wrapping or when making a thin film, the film is stretched to a desired thickness by a cooling / stretching roll portion. Additives that are easily decomposed in the processing steps of these films and sheets, for example, a foaming agent, may be blended in a receiving roll or a supply roll.

[0023]

Next, the present invention will be described with reference to several examples and reference examples. The calender equipment (1 set) used here was a 5-blade 5-liter intensive mixer with two blades, a mixing roll (receiving roll) of 305Φ, and a mixing roll (supply roll) of 200Φ, 200
Φ 6 composite calender rolls, 85 Φ 6 take-off rolls, 9 200 Φ annealing and cooling rolls, pinch rolls and winder rolls.

Examples 1-4 As a high-pressure low-density polyethylene, a melt index (hereinafter abbreviated as MI): 4.5, density: 0.922, D
SC method main peak melting point (hereinafter abbreviated as mp): 110 ° C, D
SC method main peak crystallization temperature (hereinafter abbreviated as cp): 93 ° C
Of the pellet (A1) was used. As an ethylene-α-olefin copolymer using a metallocene catalyst as a polymerization catalyst,
MI: 1.6, density: 0.895, mp: 93 ° C, c
p: 78 ° C., octene-1: 14.5% by weight copolymer, M
A pellet (B1) having w / Mn = 2.6 was used.

3.5 kg of each of (A1) and (B1) was prepared at the ratios shown in Table 1, and the lubricant mp: 57
C., 1 part of citrate distearate relative to the resin, and Irganox 1076 and Irgafos 168 (product of Ciba-Geigy) as the heat stabilizer were added to the resin at 0.1 parts.
Added in parts.

These were put in an intensive mixer and melted and kneaded for 5 minutes. When the resin temperature reached 165 ° C., the mixture was transferred to a receiving roll having a temperature of 150 ° C. and continued to be mixed. From here, the resin in the molten state was appropriately transferred to a supply roll at a temperature of 150 ° C., and the resin was further supplied from here to the calender roll portion by an appropriate amount. The temperature of the calender roll at this time was selected from the range of 155 ° C. to 120 ° C. and the temperature at which the ratio of the resin (A1) and the resin (B1) was the best. The thickness of the rolled resin at the calender roll exit is 2
At 50 microns, this was guided to a take-off roll set at 120-100 ° C, then passed through an annealing roll-cooling roll set at 80-30 ° C and wound up on a winder roll as a film with a final thickness of 100 microns.

Table 1 shows the workability of the above-described calendering step and the characteristics of the obtained film.

Reference Example 1 The same kind and amount of heat stabilizer as in Example 1 were added to each of the resins (A1) and (B1) used alone in Example 1 and pellets having the same ratio as in Examples 1 to 4. , Except that
The lubricant of the component (C) was not added, and the mixture was kneaded under the same conditions using a 2-blade 5-liter intensive mixer. During discharge from here, the molten resin adhered to the blades, and workability was poor first. On the next receiving roll and supply roll (A
1) In the single system, the bank was not stable at a low temperature, and the mold release was poor at a high temperature. On the other hand, in the case of (B1) alone, the bank was relatively stable, but the release from the roll was poor and the work was difficult. The blend system of (A1) / (B1) had the same tendency as described above. These molten resins are used for 20
It was supplied to six composite calender rolls of 0Φ, but the work was interrupted because the bank was unstable or did not release stably from the rolls.

REFERENCE EXAMPLES 2 AND 3 To each of the resins (A1) and (B1) used in Example 1, the same kind and amount of a lubricant and a heat stabilizer as in Example 1 were added, and a 5-liter intensive mixer was used. And kneaded under the same conditions. Emissions from here were fine. On the next receiving roll and supply roll, the bank was not stable at a low temperature in the (A1) single system at the low temperature, whereas the bank was relatively stable in the (B1) single system, but the workability was poor due to insufficient release from the roll. Was bad. These molten resins were supplied to a composite calender roll. However, even under the conditions considered to be appropriate processing conditions, the (A1) single system did not stabilize the bank and caused rolling unevenness.
In the (B1) system, although the bank was stable, uniform release was difficult, and wrinkles occurred due to partial stretching. Table 1 also shows the characteristics of the good parts of the film obtained from this.

[0030]

[Table 1]

Examples 5 to 9 As the high-pressure low-density polyethylene, pellets (A2) having an MI of 4.0, a density of 0.916, an mp of 106 ° C., and a cp of 88 ° C. were used. As an ethylene-α-olefin copolymer using a metallocene catalyst as a polymerization catalyst, MI:
3.0, density: 0.902, mp: 98 ° C, cp: 81
C, octene-1: 12% by weight copolymerization, Mw / Mn =
2.4 pellets (B2) were used.

To 100 parts by weight of the (A2) / (B2) = 50/50% by weight mixed pellets, citric acid / stearic acid monoglyceride was added as a lubricant at a ratio shown in Table 2 and added to the mixture. Irganox 1076 and Irgafos 168 (a product of Ciba Geigy) were added as heat stabilizers to the resin in an amount of 0.1 part.

These are melt-kneaded in a twin-screw extruder,
Pelletized. Temperature of this pellet: 145 ° C
Of a 6-inch mixing roll. At this time, the stability of the bank on the roll, the releasability when the resin thickness is rolled to 250 microns and the roll is taken out of the roll as a sheet, and the bleed resistance of the lubricant to the sheet surface as characteristics of the obtained sheet The sheets were evaluated for blocking resistance and the results are shown in Table 2.

[0034]

[Table 2]

Example 11 Pellets (A3) having a MI of 1.5, a density of 0.921, an mp of 110 ° C. and a cp of 98 ° C. were used as high-pressure low-density polyethylene. As an ethylene-α-olefin copolymer using a metallocene catalyst as a polymerization catalyst, MI:
5.0, density: 0.870, mp: 63 ° C, cp: 43
° C, octene-1: 24% by weight copolymer, Mw / Mn =
2.4 pellets (B3) were used.

With respect to 100 parts by weight of the mixed pellets (A3) / (B3) = 50/50% by weight, as a lubricant,
0.5 part of citrate distearate was added, and 0.1 parts each of Irganox 1076 and Irgafos 168 (product of Ciba-Geigy) as a heat stabilizer were added to the resin. Silica (Mizukasil P802: average particle size = 2.5 microns)
3.0 parts by weight of Mizusawa Chemical Industry Co., Ltd.) with respect to the resin and 0.1 part by weight of calcium stearate for dispersing the resin were added to the resin, and the mixture was put into the intensive mixer used in Example 1. When the resin temperature reaches 160 ° C. after melt-kneading for 4 minutes, the resin is transferred to a receiving roll at a temperature of 140 ° C., and the resin in a molten state is appropriately transferred from here to a supply roll at a temperature of 140 ° C., and a calender of an appropriate amount from here. The resin was supplied to the roll part. The temperature of the calender roll at this time was 138/138/138/133.
/ 128/123 ° C. The thickness of the rolled resin at the calender roll exit is 230 microns and this is 10
Lead to a take-off roll set at 0 ° C., then 80
After passing through an annealing roll to a cooling roll set at ３０30 ° C., a film having a final thickness of 100 μm was wound up by a winder roll. The workability in this step was good, and the resulting film was translucent, non-glaring, translucent and translucent and of commercial value.

[0037]

As described above, according to the present invention, it is possible to obtain a polyethylene resin composition having excellent calenderability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 23:00 B29L 7:00

Claims (3)

[Claims] 1. A composition comprising at least two types of ethylene-based resins (A) and (B) and at least three components of a lubricant (C), wherein (A) / (B) is 80 / 2
0-10 / 90% by weight, the amount of (C) is (A) +
(B) 0.2 to 3% by weight of the calendering composition. (A) has a melt index of 0.2 to 10 g / 10 min and a density of 0.915.
~0.930g / cm ^3, the high-pressure low-density polyethylene value of the main peak of the melting point of the DSC is in the range of one hundred and four to one hundred seventeen ° C.. (B) has a melt index of 0.2 to 10 g.
/ 10 min, density 0.86 to 0.910 g / c
m ^3, Mw / Mn of 3.0 or less, in the range value of the main peak is 40 to 105 ° C. of the melting point of the DSC, and an ethylene -α- olefin copolymer a metallocene catalyst as a polymerization catalyst. (C) is at least one lubricant selected from carboxylic esters having a melting point in the range of 40 to 100 ° C. 2. A calendering composition comprising the calendering composition according to claim 1 and 10% by weight or less of an inorganic filler having an average particle size of 7 μm or less. 3. The composition for calender molding according to claim 1, wherein the carboxylic acid ester of the lubricant (C) is a citrate ester.