JP3076094B2 - Polypropylene resin laminate for thermoforming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, appearance Ru <br/> relates to a good oxygen barrier properties of excellent thermal molding polypropylene resin laminate. A container obtained by subjecting this sheet to vacuum forming, pressure forming, and matched die forming is excellent in gloss and transparency, and is useful as a food container.

[0002]

2. Description of the Related Art Propylene homopolymers are used for pudding containers and confectionery trays because of their excellent heat resistance, mechanical properties and chemical stability.

However, since polypropylene lacks gas barrier properties, there is also a use in which it is laminated with an oxygen-blocking resin such as nylon, saponified ethylene-vinyl acetate copolymer, polyethylene terephthalate, etc. No. 11263, JP-A-54-160481,
No. 49-39678, etc.). These are methods for producing gasoline tanks and soy sauce containers by hollow molding.

[0004]

A laminated film of a polypropylene film and an oxygen-barrier resin (hereinafter referred to as a barrier resin) film is thermoformed (vacuum forming, pressure forming, matched die forming) under the same conditions as a polypropylene single film. ), The container is wrinkled and the appearance is poor.

[0005] This is because the softening temperature of the barrier resin is higher than that of the propylene homopolymer, and the thermoforming temperature (180 to 210 ° C) of the propylene polymer alone film does not reach the softening temperature of the barrier resin. This is because uniform elongation cannot be obtained during molding. When thermoforming a laminated film of a propylene homopolymer and a barrier resin without impairing the appearance, it is necessary to heat to a temperature higher than the thermoforming temperature of the propylene homopolymer alone, but polypropylene has a melt viscosity of Since the film is low, dripping of the film is large and thermoforming becomes difficult.

On the other hand, a container obtained by thermoforming a propylene polymer film is required to have excellent gloss and transparency.

[0007] It is an object of the present invention to provide a polypropylene resin laminate film having a surface appearance with good gloss and transparency and capable of obtaining a container having excellent gas barrier properties by a thermoforming method.

[0008]

According to the present invention, there is provided a film formed from a polypropylene resin composition containing the following components (A), (B) and (C) on one or both sides of an oxygen-barrier resin film layer. It is intended to provide a thermoformed polypropylene resin laminate in which layers are laminated.

(A) 20 to 70% by weight of a propylene homopolymer having a melt flow rate (MFR) of 0.3 to 10 g / 10 minutes and a density of 0.906 g / cm ³ or more;
(B) 100 parts by weight of a polypropylene resin consisting of 80 to 20% by weight of an ethylene-propylene random copolymer having an MFR of 0.3 to 10 g / 10 minutes and an ethylene content of 0.5 to 6.0% by weight, (C) The nucleating agent is 0.01 to
A polypropylene resin composition blended at 1 part by weight.

The propylene homopolymer of the component (A) The component (A) of the present invention has an MFR of 0.3 to 10 g / 10
Min, preferably 0.5-5 g / 10 min and a density of 0.9
06 g / cm ³ or more, preferably 0.907 to 0.915
g / cm ³ of propylene homopolymer. If the MFR is lower than the above range, the film forming speed is reduced, and if the MFR is higher than the above range, the melt tension is insufficient, and the sheet is easily sagged during thermoforming, making thermoforming difficult. Further, the impact resistance of the container is lowered, so that it is not suitable. If the density is lower than the above range, the gloss of the container after the thermoforming is reduced, which is inappropriate. If the mixing ratio of the component (A) is below the above range, the gloss of the container after thermoforming is insufficient, and if it is higher, the transparency is insufficient, which is inappropriate.

(B) Ethylene-propylene random copolymer
Ethylene is a polymer component (B) - propylene random copolymer, MFR is well below the range of the molding speed is lowered, the easily drips film during thermoforming insufficient melt tension which exceeds, It is unsuitable because the impact resistance of the obtained container is lowered. If the ethylene content is lower than the above range, the effect of improving transparency is insufficient, and if it is higher, the rigidity of the container decreases, which is not preferable. If the proportion of the component (B) is less than the above range, the transparency is insufficient, and if it is greater, the gloss of the container after thermoforming is insufficient.

(C) Nucleating agent As the nucleating agent , talc, a metal salt of an organic carboxylic acid, a metal salt of an aromatic phosphoric acid, dibenzylidene sorbitol and derivatives thereof can be used. Of these, p
Aluminum salt of t-butylbenzoic acid, sodium bis (4-t-butylphenyl) phosphate, phosphoric acid-2,
Sodium 2'-methylene-bis (4-6-di-tert-butylphenyl), 1,3,2,4-di-p-methyl-benzylidenesorbitol, 1,3,2,4-di-p-ethyl The method of adding benzylidene sorbitol is suitable. When the amount of the nucleating agent is less than the above range, the transparency is insufficient, and when the amount is more than the above range, no further effect of improving the transparency is obtained, which is economically disadvantageous.

Optional Components In the present invention, in addition to the above-mentioned components (A), (B) and (C), additional components may be added within a range that does not significantly impair the effects of the present invention. These additional components include antioxidants used for normal polyolefins,
Various auxiliary agents such as a neutralizing agent, an ultraviolet absorber, an air bubble inhibitor, a dispersant, an antistatic agent, a lubricant, a molecular weight modifier (peroxide), other various resins and elastomers, and a colorant can be exemplified. .

The method for producing the above composition used in the present invention includes a commonly used mixer or kneader such as a Henschel mixer, a super mixer, a V blender, a tumbler mixer, a ribbon blender, a Banbury mixer, a kneader blender or an extruder. It is preferable to mix the mixture for a predetermined time using an extruder, and to form pellets using an ordinary extruder.

Barrier Resin The barrier resin used in the present invention is ethylene-
Saponified vinyl acetate copolymer, polyvinyl alcohol resin, polyvinylidene chloride resin, copolymer of vinylidene chloride and acrylate, polyethylene terephthalate, polybutylene terephthalate, polyamide resin, acrylonitrile resin can be used, A commercially available product can be used as it is.

[0016] As a method for producing the laminate film used in the laminate film present invention,
T using multi-manifold or feed block
A mold die multi-layer extrusion sheet molding machine can be used, and the present invention is not limited to the scope of the present invention. Alternatively, a laminate film of a barrier resin alone or a propylene homopolymer is separately prepared, and the (A),
A method of laminating with a molten film of a polypropylene composition containing the components (B) and (C) is also possible. As the adhesive resin, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, and maleic anhydride-grafted polypropylene can be used.

As a method of cooling the film, a metal touch roll (two or three) is desirable because it can improve the gloss of the film surface, but a method of pressing the metal roll with an air knife or the like can also be used.

The thickness of the gas barrier resin film layer is generally 5 to 100 μm, preferably 20 to 50 μm, and is 2 to 35%, preferably 5 to 20% of the total thickness of the laminated film.
Account for%. The thickness of the polypropylene resin film layer is generally 100 to 2500 μm, preferably 300 to 100 μm.
0 μm. The thickness of the adhesive resin layer is 5 to 100 μ
m, preferably 8 to 35 μm. The thickness of the laminate film is 250 to 2200 μm, preferably 300 to 12 μm.
00 μm.

[0019] thermoforming method of the laminate film of the thermoforming present invention, a vacuum using a normal differential pressure, pressure, molding method of vacuum pressure can be used. In particular, when forming a deep drawing container, plug assist may be performed.

The heating method for thermoforming may be either indirect heating (far infrared heater or the like) or direct heating (hot plate or the like). Also, press molding such as a match mold can be used.

The shape of the container includes trays, cups, dishes and the like.

[0022]

By laminating the gas barrier resin layer with polypropylene, sagging of the film during thermoforming can be prevented, and the thermoforming cycle can be improved.

Furthermore, since the ethylene-propylene random copolymer having a lower melting point than the propylene homopolymer is blended with the propylene homopolymer, the thermoformed product obtained has excellent surface gloss.

Further, since the nucleating agent is blended, the transparency of the laminate film and the container is good.

[0025]

EXAMPLES The present invention will be specifically described below with reference to examples.

(Example 1) MFR 1.7 g / 10 min (measured by the method of JIS-K7210; the same applies hereinafter) and density of 0.9075 g / cm ³ (measured by the method of JIS-K7112; the same applies hereinafter) 50 parts by weight of a propylene homopolymer (trade name: Mitsubishi Polypropylene PY230 manufactured by Mitsubishi Yuka Co., Ltd.)
MFR 1.8g / 10min, ethylene content 3.2% by weight
50 parts by weight of a propylene-ethylene random copolymer (trade name: Mitsubishi Polypropylene EX6 manufactured by Mitsubishi Yuka Co., Ltd.) and 1,3,2,4-di-p-methyl-benzylidene sorbitol (trade name: Shin Nihon Rika ( Gel All MD)
0.2 parts by weight with a super mixer manufactured by Kawata Corporation
Then, the mixture was melted and kneaded with an extruder having a screw diameter of 50 mm heated to 230 ° C. to obtain a propylene polymer composition.

The composition was placed in a feed block having three layers and five layers from an extruder having a screw diameter of 90 mm heated to 250 ° C. to form both outer layers. Separately, a saponified ethylene-vinyl acetate copolymer (trade name: Eval F manufactured by Kuraray Co., Ltd.) was placed in a feed block from an extruder having a screw diameter of 40 mm as a barrier resin to form an innermost layer. Further, maleic anhydride-grafted polypropylene “Modic P300F” (trade name) manufactured by Mitsubishi Yuka Co., Ltd. was put into the two intermediate layers of both outer and innermost layers of the feed block from an extruder having a screw diameter of 40 mm as an adhesive resin. . These are width 75
It was extruded with a 0 mm T-die, sandwiched between two casting drums (having hard chrome plating) in which hot water at 60 ° C was circulated, and cooled and solidified to produce a five-layer laminated film. . The layer thickness of the laminated film is 450 μm for each layer of the resin composition, 50 μm for the layer of the barrier resin, and 50 μm for each layer of the adhesive resin (total thickness 1050 μm).

The oxygen permeability of this laminated film was measured. Table 1 shows the results.

Next, the laminated film was heated by a far-infrared heater using a compressed air molding machine manufactured by Asano Laboratory Co., Ltd. to form a cylindrical container having a compressed air pressure of 3 kg / cm ² and a diameter of 8 cm and a depth of 4 cm. At this time, the heater temperature was changed to change the film temperature to 150 ° C. (temperature at which the barrier resin was not softened) and 1
Molding was performed at 60 ° C. (temperature at which the barrier resin was softened).

The appearance of the container was visually observed to determine the presence or absence of wrinkles and the degree of transparency.

The results are shown in Table 1.

Comparative Examples 1 to 3 Films and containers were formed in the same manner as in Example 1 except that the composition shown in Table 1 was used instead of the propylene polymer composition of Example 1.

The films and containers were evaluated. Table 1 shows the results.

Comparative Example 4 A laminated film and a container were formed in the same manner as in Example 1 except that the oxygen-barrier resin (barrier resin) was not used. The laminated film and the container were evaluated. Table 1 shows the results.

Comparative Examples 5 to 6 A laminated film and a container were formed in the same manner as in Comparative Example 4 except that the composition shown in Table 1 was used instead of the propylene polymer composition of Comparative Example 4.
The laminated film and the container were evaluated. Table 1 shows the results.

Examples 2 to 6 Containers were molded in the same manner as in Example 1 except that the compositions shown in Table 2 were used instead of the propylene polymer composition of Example 1. This container was evaluated. Table 2 shows the results.

(Comparative Examples 7 to 10) A container was molded in the same manner as in Example 1 except that the composition shown in Table 2 was used instead of the propylene polymer composition of Example 1. This container was evaluated. Table 2 shows the results.

Example 7 The propylene polymer composition of Example 1 was extruded with a T-type die having a width of 750 mm using a 90 mm screw diameter extruder heated to 250 ° C., and cooled and solidified with the same casting drum as in Example 1. At the same time, a vinylidene chloride-based barrier resin film (Saran UB manufactured by Asahi Kasei Corporation) was simultaneously sandwiched to form a laminated film. This laminated film was formed into a container in the same manner as in Example 1 and evaluated. Table 3 shows the results.

Comparative Example 11 A container was formed in the same manner as in Example 7 except that the composition shown in Table 3 was used instead of the propylene polymer composition of Example 7. This container was evaluated. Table 3 shows the results.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

The container obtained by thermoforming the polypropylene resin laminate film for thermoforming of the present invention has excellent appearance, transparency and gas barrier properties.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hitoshi Inagaki 1 Tohocho, Yokkaichi-shi, Mie Mitsubishi Yuka Co., Ltd. Inside Yokkaichi Research Institute (56) References JP-A-56-25445 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B29C 51/00-51/46

Claims (1)

(57) [Claims] 1. A thermoforming polypropylene resin in which a film layer of a polypropylene resin composition containing the following components (A), (B) and (C) is laminated on one or both sides of an oxygen-barrier resin film layer. Laminate. (A) 20 to 70% by weight of a propylene homopolymer having a melt flow rate of 0.3 to 10 g / 10 minutes and a density of 0.906 g / cm ³ or more; and (B) a melt flow rate of 0.3 to 10 g. / 10 minutes, ethylene content of 0.5 to 6.0% by weight
A polypropylene resin composition comprising (C) 0.01 to 1 part by weight of (C) a nucleating agent in 100 parts by weight of a total of 80 to 30% by weight of a propylene random copolymer.