JPH0213902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene-based composite film, in particular a film based on a polypropylene polymer, which has good adhesion to printing inks, adhesion to metal thin films, and adhesion to organic polymers.
The present invention also relates to an easily adhesive film with improved processability. Plastic films (including sheets; the same shall apply hereinafter) used for food packaging, textile packaging, etc. are adaptable to high-speed printing, reduce residual solvent,
Characteristics such as low-cost ink and water-based ink adhesion and suitability for direct coating processing have also become desirable. For example, water-based inks are expected to be used more widely in the future because they do not have the problem of environmental pollution caused by organic solvents. As such an ink, for example, one using a cellulose derivative as a binder (trade name "cellophane" ink) is known. However, special organic solvent-based inks are used to print polypropylene films that are currently commercially available, and each ink must be stored and managed separately. There was a problem in that many types of inks and adhesives had to be prepared during the bag-making process, such as the need to store and manage the anchor coating agent for laminating the bag. In order to provide printability, there has also been an attempt to improve the adhesion of the film by coating the film surface with a resin liquid. However, the process becomes complicated, the price increases, and it is a wasteful method. In addition, polypropylene films have poor metal deposition properties and poor adhesion to metal foils.
Primer processing is also applied to cover this, but the primer tends to cause deterioration of the deposited metal, impeding printability and adhesion to the deposited surface, and the primer treatment is only necessary. It is also uneconomical. Polypropylene film has various drawbacks as described above, but it has poor adaptability to water-based inks that have been developed in recent years and direct coating with various polymers. This is extremely advantageous because it is possible to prevent environmental pollution caused by the oxidation process, eliminate pretreatment steps, save materials, and reduce residual solvent. The present invention has been made with attention to these circumstances, and includes improvements in printing ink adhesion, metal thin film adhesion,
The object of the present invention is to provide a polypropylene composite film that has good adhesion properties such as organic polymer adhesion properties. A composite film that has succeeded in achieving the above objectives is a base film containing a polypropylene polymer, and at least one side of the base film contains an (acrylic acid amide derivative)-(α-olefin) copolymer (acrylic acid based amide derivative)-(α-olefin) copolymer (acrylic acid Content ratio of amide derivative: 1 to 50 mol %): 1 to 60 parts by weight, Poly α-olefin polymer consisting of 100 to 60 parts by weight of poly α-olefin and 0 to 40 parts by weight of polybutadiene: 99 to 40 parts by weight The gist is that a covering layer consisting of parts is laminated. Specific examples and application examples of the present invention will be described below. First, the polypropylene polymer constituting the base film (hereinafter referred to as layer A) is composed of two or more α-olefins selected from (1) polypropylene, and (2) α-olefin having 2 or more carbon atoms, preferably 10 or less carbon atoms. Copolymers of olefins (at least one of which is propylene), (3) the polymers of (1) and (2) above, and polymers with good compatibility with these, such as polyethylene, ethylene/propylene copolymers, polybutene. -1, ethylene/butene copolymer, polyolefin-based monopolymer or a mixture with a copolymer such as poly-4-methylpentene-1, etc.; Consolidation is used. In this case, it is desired that the content ratio of the propylene component is 50% by weight or more; such a polypropylene polymer is poor in the above-mentioned properties (printing ink adhesion), and the improvement effect of the present invention is extremely significant. Next, the components of the coating layer (hereinafter referred to as layer B) laminated on at least one side of layer A will be explained.
The B layer is (1) (acrylic acid-based amide derivative)-(α-
(2) polyα
- 100-60 parts by weight of olefin and 0 parts of polybutadiene
-40 parts by weight of polyα-olefin polymer: 99 to 40 parts by weight, and these will be explained below in order. First, acrylic acid-based amide derivatives include acrylamide, methacrylamide, and all those in which hydrogen in the amide group is substituted with a hydrocarbon residue, etc., but a particularly representative example is acrylamide. ,
N-methylacrylamide, N,N-dimethylacrylamide, N-ethylacrylamide, N,
N-diethylacrylamide, N-n-propylacrylamide, N-isopropylacrylamide, N-isobutylacrylamide, N,N-di-n-butylacrylamide, N-hexylacrylamide, N-octylacrylamide, N-
lauryl acrylamide, N-octadecyl acrylamide, N-cyclohexylacrylamide, N-benzylacrylamide, N-phenylacrylamide, N-methyl-N-phenylacrylamide, N-tolylacrylamide, methacrylamide, N-methylmethacrylamide, N
-Ethylmethacrylamide, N,N-diethylmethacrylamide, N-n-propylmethacrylamide, N,N-di-n-butylmethacrylamide, N-octylmethacrylamide, N-cyclohexylmethacrylamide, N-benzylmethacrylamide , N-phenylmethacrylamide, and the like. On the other hand, examples of the α-olefin include ethylene, propylene, butene-1, pentene-1, methylpentene-1, and the like. In the copolymer of the acrylic acid amide derivative and α-olefin selected in this way, the content ratio of the acrylic acid amide derivative is 1 to 50 mol%.
The particularly preferred range is 1.
~20 mol%. At this time, this copolymer is
The value of intrinsic viscosity in xylene solution at 120℃ is
From the viewpoint of mixing stability with other components (specifically, the poly-α-olefin polymer described below) and extrusion stability, 0.1 to 4.5 dl/g is preferred. If the content of the acrylic acid amide derivative is less than 1 mol%, adhesion to printing inks, metal vapor deposited films and foils, and even plastic products, especially chlorine-containing resins, will not be sufficiently exhibited. If the amount is exceeded by mol%, blocking resistance, lubricity, scratch resistance, transparency, extrusion stability, etc. will decrease, and in particular, heat treatment after adhesion may reduce adhesive strength and reduce high-speed extrusion. Defects such as deterioration are exposed. Polyα- in polyα-olefin polymers
As the olefin, homopolymers or copolymers formed from α-olefins having 2 to 10 carbon atoms (for example, polypropylene, polybutene-1, poly-4
- methylpentene-1, ethylene/propylene copolymer, ethylene/butene-1 copolymer, propylene/butene-1 copolymer, propylene/4-methylpentene-1 copolymer, etc.), or mixtures thereof with each other. is used, but the melt index (230℃) is 0.5 to 30g/10min, especially 1.0 to 15g/10min.
The 10 minute one will be awarded. The other component, polybutadiene, further enhances the adhesion improvement effect of polyα-olefin, but
When the molecular weight is less than 500, migration is severe, resulting in a significant decrease in adhesion and occurrence of blocking, as well as a decrease in scratch resistance. On the other hand, if the molecular weight exceeds 20,000, the transparency will decrease, so
It is recommended to select from the range ~20000. However, a more preferred range is 800 to 10,000. The blending ratio of polyα-olefin and polybutadiene is 100 to 60 parts by weight of the former and 0 to 40 parts by weight of the latter.
Although it is not inconvenient to achieve the purpose of the present invention without adding polybutadiene, 40 parts by weight should be
If the weight part is exceeded, the transparency will deteriorate when laminated on layer A, and characters and figures printed from layer B side will be printed on layer A.
This is not preferable because the aesthetic appearance when viewed from the layer side deteriorates. The blending ratio of the acrylamide copolymer and polyα-olefin polymer is 1 to 60% for the former.
99 to 40 parts by weight of the latter can be recommended. The reason for this is that when the former is less than 1 part by weight, the printing ink adhesion, metal thin film adhesion, and organic polymer (especially chlorine-containing resin) adhesion as B layer are insufficient; This is because if the adhesive strength exceeds 50%, the transparency will be lowered, the extrusion stability will be lowered, and the adhesive force will be lowered due to heat history after bonding, and in any case, commercial productivity and commercial value will be significantly deteriorated. The chemical composition of the composite film according to the present invention is as clarified in the above explanation, and the A layer,
Although there are no restrictions on the method of forming layer B and the method of laminating it, the method described below is most preferred. That is, to obtain a composite film consisting of layer A and layer B of the present invention, coextrusion, melt extrusion lamination, heating stretching with a roll stretching machine and adhesion simultaneously, or longitudinal stretching of either one and composite adhesion of the other. In addition, methods such as longitudinal stretching, adhesion, and subsequent stretching in a direction perpendicular to the above-mentioned direction can be employed. Of course, these combinations may be performed as appropriate, or applied means other than those described above may be used. When biaxially stretching, there is no particular restriction.To carry out sequential biaxial stretching, the unstretched film is usually first stretched vertically in the longitudinal direction of the film using a roll stretching machine, and then stretched vertically in the longitudinal direction of the film using a tenter. Although a method of transverse stretching is used, the transverse stretching may be followed by longitudinal stretching in the reverse order. In the case of simultaneous biaxial stretching, either the tenter method or the inflation method can be used. In either method, the stretching ratio, stretching temperature, and
A stretching speed can be used to stretch the unstretched film of the present invention. It should be noted that the A layer and B layer used in the present invention, or the composite film formed by laminating them, may be unstretched or stretched, but from the viewpoint of glossiness or machine suitability, it may be It is desirable that the paper be stretched to . Therefore, the composite film of the present invention includes one in which the A layer and the B layer are entirely uniaxially stretched, one in which the B layer is uniaxially stretched and the A layer is biaxially stretched, and one in which the A layer is uniaxially stretched and the B layer is uniaxially stretched. These include those that are biaxially stretched, those in which the A layer is biaxially stretched and the B layer is unstretched, and those in which the B layer is biaxially stretched and the A layer is unstretched. If I were to state this more specifically,
When abbreviated biaxial stretching as BO, uniaxial stretching as UO, and unstretched as NO, NO-A layer/NO-B layer, UO-A
Layer/NO-B layer, UO-A layer/UO-B layer, NO-
A layer/UO-B layer, BO-A layer/NO-B layer, BO
-A layer/UO-B layer, BO-A layer/BO-B layer,
Various designs such as NO-A layer/BO-B layer, UO-A layer/BO-B layer, etc. can be made. The above design examples are all two-layer composite films, but if necessary, three or more layer composite films can be designed.
It can also be manufactured. However, when used for bag making, two or three layers are sufficient. A layer and B
There is no need to set any particular restrictions on the thickness of each layer, and there is almost no limit on the thickness of the A layer in particular.
Regarding the B layer, it is desirable to design it so that the final thickness is 0.1 to 30 μm, preferably 0.4 to 15 μm.
Depending on the application, it is also possible to design it to be even thicker. That is, if the thickness of layer B is less than 0.1 μm, the adhesion stability deteriorates, and if the thickness exceeds 30 μm, the transparency is impaired, which limits the application. The most preferable thickness is 10 μm or less. The composite film of the present invention constructed as described above has (1) adhesion to an adhesive containing a cellulose derivative or printing ink using this as a binder; and (2) adhesion to various adhesives such as acrylic, vinyl chloride, and vinylidene chloride. Adhesion with polymer or copolymer-based adhesives or printing inks using these as binders (3) It exhibits excellent adhesive properties with metal vapor deposited layers and metal foils, so take advantage of these properties. For example, it can be provided as various composite products as described below. As an example, the adhesion with printing ink using a cellulose derivative as a binder will be described as follows. As the cellulose derivative, nitrified cotton (nitrocellulose) is preferred, but other examples include cellulose ethers such as methylcellulose, ethylcellulose, and hydroxyethylcellulose, and cellulose esters such as cellulose propionate. In addition to these cellulose derivatives, there are polyamide resins made of condensates of polymerized fatty acids and polyamines, rubber derivatives such as cyclized rubbers and chlorinated rubbers, ester rubbers such as rosin and glycerin esters, and amine resins such as urea and melamine resins. However, the present invention is not limited thereto. For example, when nitrified cotton is contained as a binder, the degree of nitrification is usually 9 to 12.5% and the degree of polymerization is 20 seconds to 1/20 seconds according to the Hercules method, which exhibits the characteristics of nitrocellulose. Inorganic or organic pigments and dyes are further used in the mixture containing the above-mentioned cellulose derivatives, such as titanium white, yellow lead, copper powder, phthalocyanine blue, etc., as appropriate depending on the color. These mixtures are diluted with alcohols, esters, ketones, and various organic solvents such as ethylbenzene acetate, toluene, and xylene.
Use after adjusting the viscosity. Further, volatile varnish or the like may also be used as a coloring agent. Such printing ink is overprinted once or several times over part or the entire surface of the B layer. These printing ink layers adhere extremely well to the film and are well resistant to rubbing, scratching, and peeling with adhesive tape, etc., so that even if other polymers or films are laminated, the ink and film will remain intact. Practical strength at an interface is, for example, 45g/15mm for packaging materials, although it varies depending on weight, shape, properties, etc.
It means a width of at least 100 g/15 mm, preferably at least 100 g/15 mm. The film used in the present invention exhibits extremely good adhesion to printing inks containing cellulose derivatives by corona discharge treatment, which is not the case with conventional polypropylene films. Another characteristic effect of the present invention is that a higher processing effect can be obtained by using the same power as the conventional corona discharge power (for polypropylene film), and Whereas the polypropylene film had the disadvantage of increasing corona discharge power consumption and always showing a plateauing phenomenon at a certain level, the B layer of the composite film of the present invention has a processing effect that is almost proportional to the power consumption. There is also the advantage of being able to The structure of the composite film according to the present invention is as described above, but an antistatic agent, a lubricant, an anti-blocking agent, a dye, a pigment, a weathering agent, an ultraviolet inhibitor, and various stabilizers are added to the A layer and the B layer. It is free to add.
For example, when synthetic zeolite is incorporated into either or both of layer A and layer B (generally layer B), antistatic properties and slipperiness are improved. That is, synthetic zeolite is a highly hygroscopic component, and by adsorbing moisture in the atmosphere, the moisture content of the film increases, which is thought to reduce electrical resistance and exhibit antistatic properties. In order to achieve this effect, synthetic zeolite must be
It is desirable to have an average particle size of 0.2 to 20 μm and to contain it in the B layer at a ratio of 0.05 to 6% by weight, for example. If the average particle size of the synthetic zeolite is less than 0.2 μm, the effects of antistatic properties, anti-blocking properties, etc. will be poor. Moreover, when it exceeds 20 μm, transparency tends to decrease. If the amount is less than 0.05% by weight, the above effects will not be exhibited, while if it exceeds 6% by weight, transparency will tend to decrease. The composite film constructed as described above is mainly used as a packaging material, but in this case, a printing ink layer, an adhesive layer, or a resin (especially chlorine-containing resin) layer is formed on the B layer side, and It is preferable to form a bag after laminating a polymer having a lower melting point than layer A. Other uses include films or tapes for covering metal products and plastic products. Next, Examples and Comparative Examples of the films of the present invention will be described, and the characteristics of the films produced were measured according to the following measuring method. (1) Transparency (haze) According to JIS K6714. (2) Adhesiveness of printing ink Commercially available cellophane tape was brought into close contact with the printed surface and then peeled off at high speed, and the size of the area where the printing ink remained was determined. Cellophane ink CL-C (manufactured by Dainippon Ink Co., Ltd.) was used as the printing ink, and the evaluation was based on the following criteria. Evaluation point Peeling rate 5 0% 4 ~10% 3 ~20% 2 ~50% 1 50% or more (3) Adhesion of vapor-deposited Al Commercially available cellophane tape was adhered to the Al-deposited surface.
It was tested and evaluated in the same manner as (2). The peeling directions were the orientation direction of the film resin (vertical) and the direction perpendicular thereto (horizontal). “Immediately” in Table 1
means "immediately after Al deposition", and "after treatment" means "after aging at 40° C. and 90% RH for 48 hours". (4) Lamination strength Regarding the printing ink, printing was performed on layer B, and then low density polyethylene was melt-extruded and laminated, and the lamination strength of the printed area was measured. The test results are shown as the average strength value (n=5) when the laminate layer was peeled off at a speed of 200 mm/min using a 90-degree peeling method. Regarding Al vapor deposition, the results of a similar test on a product that was extruded and laminated in the same manner after forming a 500 μm Al vapor deposited layer are shown. 3g/m ² for PVDC coat
A similar laminate is applied to the PVDC coated surface of
Next, the results of a similar test are shown. (5) Durability of bags (in the case of printing ink) After printing on layer B and laminating low-density polyethylene by melt extrusion, using an automatic filling and packaging machine, conditions of 180°C and 200 pieces/min. The bag was made with A steel plate was then placed on the top flat plate of the bag, and while pressure was gradually applied from above the steel plate, the critical pressure at which air began to leak from the bag was measured, and the influence of the adhesive force between the base material and the ink was measured. (6) Adhesion of flour to bags We investigated the adhesion of bread crumbs to the heat-sealed part of bags when bread crumbs were automatically filled and packaged.
The evaluation is in 4 stages, with no adhesion at all being ◎
○ indicates that there is no adhesion to the extent that it poses a practical problem, △ indicates that some adhesion is observed, and × indicates that there is adhesion to the extent that it causes damage to the seal portion. Example 1 Isotactic polypropylene (MI=3.0
g/10 minutes), synthetic zeolite powder (particle size: 2.5μ
A layer was prepared by adding 0.2% by weight of m) and 1.0% by weight of an alkylamine ethylene oxide adduct. On the other hand, a composition () was prepared by mixing 30 parts by weight of N,N-diethylacrylamide/propylene copolymer (34.4 parts by weight/65.6 parts by weight) and 70 parts by weight of polypropylene. A composition (2) was also prepared using a mixture of polypropylene and polybutadiene (weight ratio 4/1) instead of the polypropylene. Then, 0.3% by weight of silicon dioxide and 0.05% by weight of erucic acid amide were added to these compositions () and (), respectively, and these were laminated as B layer on one side of A layer by coextrusion method, A layer: 760 μm, B layer: A 40 μm unstretched composite film was obtained. Next, the film was stretched 4.5 times in the longitudinal direction at 135°C, and further stretched 9.0 times in the transverse direction at 150°C to form a biaxially stretched film, and then the B layer side was subjected to corona discharge treatment to increase the surface wetting tension. is 45 dynes/cm
A composite film was obtained. Printing on B layer, Al vapor deposition,
It was coated with PVDC and laminated with low-density polyethylene, and then made into a bag. The results of each test are shown in Table 1 below. Example 2 In the combination of layer A and composition (2) of Example 1, exactly the same treatment and evaluation were performed for the case where no synthetic zeolite was added to layer A. Example 3 In Example 2, 0.2% by weight of synthetic zeolite having a particle size of 4 μm was mixed in layer B, and the same treatment and evaluation were performed. However, as the printing ink, an aqueous acrylic ink diluted with a water-isopropanol solvent was used. Example 4 In Example 1, the ink was changed to a water-based ink, and the same treatment and evaluation were performed. Comparative Example 1 Similar evaluations were performed on the film of Example 1, which had been subjected to the same stretching and corona discharge treatment. Comparative Example 2 A layer was formed with the same composition as the base material of Example 1.
Axially stretched. Next, an ethylene/vinyl acetate copolymer was melt-extruded laminated on one side of the film to form a layer B having a thickness of 15 μm. The B layer is subjected to corona discharge treatment,
Wet tension was set to 43 dynes/cm. Layer B was subjected to the same treatment as in Example 1 and evaluated in the same manner. 【table】

Claims (1)

[Scope of Claims] 1 At least one side of a base film containing a polypropylene polymer contains an (acrylic acid amide derivative)-(α-olefin) copolymer (content ratio of acrylic acid amide derivative: 1 to 50 moles) %): 1 to 60 parts by weight, and a coating layer consisting of 99 to 40 parts by weight of a polyα-olefin polymer consisting of 100 to 60 parts by weight of polyα-olefin and 0 to 40 parts by weight of polybutadiene. An easily adhesive film characterized by: 2. The easily adhesive film according to claim 1, wherein the coating layer contains 0.05 to 6% by weight of synthetic zeolite having an average particle size of 0.2 to 20 μm.