JPH0859911A - Resin composition - Google Patents

Abstract

PURPOSE: To obtain a resin composition excellent in gas barrier properties under high humidity, hot-water resistance, drawability and softness and free from whitening after retort cooking when used as a material for a retort container. CONSTITUTION: This resin composition is composed of (A) a saponification product of an ethylene-vinyl acetate copolymer, having ethylene content of 20-65mol.% and saponification degree of >=90mol.% in terms of the vinyl acetate component and (B) a polymer obtained by reacting (A) a polyolefin-based resin containing an epoxy group with (b) a polyamide having a polymerization degree of 80-1000. Further, the compounding weight ratio of (A):(B) is (99.8-50):(0.2- -50).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having excellent gas barrier properties under high humidity and having improved hot water resistance, stretchability and flexibility.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl acetate copolymers are widely used for various purposes such as films, sheets, containers and fibers because they are excellent in various properties such as oxygen barrier property and mechanical strength. However, since the saponified product of the copolymer has a high hygroscopicity, the physical properties such as flexibility of the molded product are greatly changed due to changes in humidity and temperature in the external environment, and particularly, the oxygen-blocking property has a large humidity dependency under high humidity. However, there is a problem that the oxygen barrier property at the time is lowered. In addition, since the stretchability and flexibility of the molded product are insufficient, stretching unevenness occurs during processing such as drawing, and pinholes etc. occur during use of the molded product, limiting the use as a packaging material. is the current situation. As such measures, for example, a saponified film of ethylene-vinyl acetate copolymer, a sheet is laminated with a waterproof resin such as a polyolefin to prevent moisture permeation from the outside, or a polyolefin is blended with the saponified chemical. Attempts have been made to improve water resistance, stretchability and flexibility.

However, in the former method, the laminating operation is indispensable, and even if such a processing is performed, it is difficult to avoid the moisture permeation from the edge portion, and the sufficient purpose cannot be achieved. Further, in the latter method, since the compatibility between the polyolefin and the saponified product of the ethylene-vinyl acetate copolymer is poor, abnormal flow occurs during molding, resulting in poor appearance. Further, although the combination of various additives has been devised to eliminate the drawback, it is not an essential solution.

Further, polyolefin is inexpensive, has excellent mechanical properties, is easy to process, and has excellent properties such as excellent transparency, water vapor permeation resistance, and safety and hygiene. Therefore, it is widely used as a packaging material for foods, cosmetics, toiletries, chemicals and the like. However, since the gas permeability of oxygen gas, carbon dioxide gas, etc. is large, it is not possible to use those that affect the quality of the contents due to the invasion of these gases, or it is only possible to use for a very short time. Met.

In order to improve the gas permeation resistance of polyolefin, for example, it has been proposed to blend polyolefin with a gas permeation resistant saponified ethylene-vinyl acetate copolymer (JP-A-49-38984). However, in this method, in order to improve the adhesiveness between the blend and the polyolefin, the blending weight ratio of the polyolefin must be 50% by weight or more based on the total weight.
Although the adhesiveness with the polyolefin is strong, the compatibility of the polyolefin and the saponified product of the ethylene-vinyl acetate copolymer is poor in the blend layer, which causes abnormal flow during molding, resulting in poor appearance.

Further, in the invention described in JP-A-53-39380, 25 to 60 parts by weight of a saponified ethylene-vinyl acetate copolymer having a melt index three times or more higher than that of polyolefin is added to 100 parts by weight of polyolefin, ethylene. 70 to 98 mol% content, 20% saponification degree
The above saponified ethylene-vinyl acetate copolymer 5 to 40
It is proposed to use parts by weight. However,
When the blend layer is used as the outer layer, a satin finish and a wavy pattern are formed, which significantly impairs the appearance and cannot be put to practical use.

Further, in the invention described in JP-A-3-72539, ethylene is added to 100 parts by weight of a total of 100 parts by weight of polyolefin: ethylene-vinyl acetate copolymer saponified product 60:40 to 99.1: 0.1. Content of 68-98 mol%, saponification degree of 20% or more, saponification product of ethylene-vinyl acetate copolymer 0.3 parts by weight or more, and polyolefin 0.5-6 modified with unsaturated carboxylic acid or its derivative.
It is proposed to use 0 parts by weight. However, although the compatibility of this blend is improved, it is still insufficient.

[0008]

The present invention is based on ethylene-
It is an object of the present invention to provide a resin composition having improved gas barrier properties, hot water resistance, stretchability and flexibility of a saponified vinyl acetate copolymer under high humidity.

[0009]

Means for Solving the Problems The above-mentioned object is ethylene-
Saponified vinyl acetate copolymer (A) (hereinafter referred to as EVOH) or EVOH (A) and polyolefin (C)
The epoxy group-containing polyolefin resin has a degree of polymerization of 80 to
It is achieved by providing a resin composition containing polymer (B) reacted with 1000 polyamides.

The EVOH (A) referred to in the present invention is obtained by saponifying a vinyl acetate component in a copolymer of ethylene and vinyl acetate, having an ethylene content of 20 to 65 mol% and a saponification degree of the vinyl acetate component. It is important to be 90% or more. The preferred range of ethylene content is 20 to 60 mol%, and more preferably 20 to 50 mol%. The preferable range of the degree of saponification is 99% or more. Also EVOH
Melt flow index (MI) of (A) {190
℃, measured under a load of 2160g: However, the melting point is 190
About 190 ° C or more than 190 ° C, it is measured at a plurality of temperatures above the melting point under a load of 2160 g, and the reciprocal of absolute temperature is plotted on the abscissa and the melt index (logarithm) on the abscissa in a semilogarithmic graph. Extrapolated value} is 0.1
g / 10 minutes or more, preferably 0.5 g / 10 minutes or more, and 100 g / 10 minutes or less, preferably 50 g / 10
Minutes or less, optimally 30 g / 10 minutes or less.

The EVOH (A) referred to in the present invention may be modified with a comonomer in an amount of 5 mol% or less. Examples of the modifying monomer include propylene, 1-butene, 1-hexene and 4-methyl. -1-Pentene, acrylic acid ester, methacrylic acid ester, maleic acid, fumaric acid, itaconic acid, higher fatty acid vinyl ester, alkyl vinyl ether, N- (2-dimethylaminoethyl) methacrylamide or its quaternary compound, N- Vinylimidazole, or its quaternary compound, N-vinylpyrrolidone, N, N-butoxymethylacrylamide,
Examples thereof include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane and the like.

In the present invention, the polymer (B) means an epoxy group-containing polyolefin resin (a) having a degree of polymerization of 80 to 80.
It is a polymer obtained by reacting 1000 polyamides (b), and particularly preferably a graft polymer. The polymer, particularly the graft polymer, for example, a polyolefin-based resin, an epoxy group-containing ethylenically unsaturated monomer peroxide, heat, light, using an initiator such as ionizing radiation,
It is produced by mixing a modified olefin polymer obtained by graft polymerization with polyamide in a molten state. In such a reaction, a Brabender, a bath blender, a single screw extruder, a Weiner and a Frederer type twin screw extruder and the like are used. The degree of polymerization of the polyolefin-based resin used is selected to be 350 to 45000, preferably 500 to 10000. The MI (230 ° C., load 2160 g, the same applies hereinafter) of the polyolefin resin is practically about 0.1 to 50 g / 10 minutes.

Examples of the epoxy group-containing ethylenically unsaturated monomer include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, vinyl glycidyl ether, hydroxyalkyl acrylate or hydroxyl methacrylate glycidyl ether. The modification amount is 700 to epoxy equivalent.
It is 10,000, more preferably 1,000 to 5,000.
Here, the epoxy equivalent is represented by g of a resin containing 1 g equivalent of an epoxy group. When the epoxy equivalent is less than 700, there are disadvantages such as vigorous thickening and gelation and deterioration of moldability. On the other hand, when it exceeds 10,000, E
The transparency and mechanical properties of the composition are unsatisfactory, probably due to poor compatibility with VOH.

Examples of the olefin monomer constituting the polyolefin resin include ethylene, propylene and butylene. Specific examples of the olefin resin include polyethylene (low density, medium density, high density) and ethylene. -Propylene copolymer, ethylene-α-olefin copolymer such as ethylene-butylene copolymer, ethylene-
Acrylic ester copolymer, ethylene-vinyl acetate copolymer, butyl rubber and the like can be mentioned, but particularly preferably,
Low density polyethylene, ethylene-propylene copolymer,
An ethylene-acrylic acid ester copolymer is used.
The polyolefin-based resin may be copolymerized with a small amount of another unsaturated monomer within a range not impairing the object of the present invention. Further, in the present invention, the MI of the epoxy group-introduced olefin polymer is 0.1 to 50 g.
/ 10 minutes is preferable, and more preferably 0.5 to 15 g / 1
0 minutes.

It is important that the polyamide used in the present invention has a degree of polymerization of 80 to 1000, preferably 100 to 600. The weight ratio of the epoxy group-containing polyolefin resin (a) and the polyamide (b) is
(A) :( b) = 99.8 to 50: 0.2 to 50 is preferable, and more preferably 99.8 to 60 to 0.2 to 40.
Is.

The polyamide used in the present invention is produced by a known method such as polyaddition of lactam, polycondensation of aminocarboxylic acid, polycondensation of diamine and dicarboxylic acid.
Specific examples of the polyamide raw material include lactams such as ε-caprolactam, enantolactam, capryllactam, lauryllactam, α-pyrrolidone and α-piperidone, 6-aminocaproic acid, 7-aminoheptanoic acid and 9-aminononanoic acid. , Ω-amino acids such as 11-aminoundecanoic acid, adipic acid, glutaric acid, pimelic acid, speric acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, hexadecenedioic acid, eicosane Dionic acid, eicosadienedionic acid, diglycolic acid, 2,2,4-trimethyladipic acid, xylylenedicarboxylic acid, 1,4
Dibasic acids such as cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, hexamethylenediamine,
Tetramethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,
2,4 (or 2,4,4) -trimethylhexamethylenediamine, bis- (4,4'-aminocyclohexyl)
Examples include methane and diamines such as metaxylylenediamine. Further, monoamines such as laurylamine and oleylamine may be appropriately used for the purpose of controlling the molecular weight.

In the present invention, the above EVOH
By blending (A) and the polymer (B), the gas barrier property is excellent even under high humidity, and the hot water resistance is
Stretchability and flexibility are improved. The blending ratio of EVOH (A) and polymer (B) is (A) :( B) = 99.8-5.
0: 0.2 to 50, preferably (A) :( B) = 90 to 6
It is 0: 5 to 40. If the amount of (A) is too large, the gas barrier properties under high humidity, flexibility, etc. will not be improved, and if the amount of (B) is too large, the gas barrier properties of (A) will be impaired. .

In the present invention, the EVOH (A) and the polymer (B) may be blended with a polyolefin (PO) (C). Polyolefin (C) is EVOH
Uniform mixing with (A) is usually difficult, and it is difficult to obtain a molded product having excellent properties. However, in the present invention, such a polyolefin component (C) is used as EVOH.
Even if blended with (A), there is no inconvenience, and the excellent properties (mechanical properties, heat resistance, heat sealability, etc.) of the polyolefin component (C) can be imparted.

The resin composition comprising the EVOH (A), the polymer (B) and the polyolefin (C) of the present invention has excellent gas barrier properties and flexibility under high humidity, and further has (A) and (B). The compatibility of (C) and (C) is also good, and various mechanical strengths are also excellent.

In the resin composition of the present invention (A),
The blending ratio of (B) and (C) is 50 to 99.5% by weight of (A), preferably 60 to 95% by weight, and (B) is 0.1 to 0.1%.
15% by weight, preferably 0.5 to 10% by weight, (C) is 0.4 to 50% by weight, preferably 4.5 to 35% by weight.

Here, the polyolefin (C) means high density, medium density or low density polyethylene, vinyl acetate, acrylic acid ester, butene, hexene,
Polyethylene copolymerized with α-olefins such as 4-methyl-1-pentene, ionomer resin, polypropylene homopolymer, polypropylene grafted with ethylene, or ethylene, butene, hexene, 4-
Polypropylene copolymerized with α-olefins such as methyl-1-pentene, modified polypropylene blended with rubber polymer, poly-1-butene, poly-4-methyl-
1-Pentene etc. are included. Of particular importance to the present invention are polypropylene resins and then polyethylene resins.

The blending method for obtaining the resin composition of the present invention is not particularly limited, and a method of dry blending (A)-(B) or (A)-(B)-(C),
A method of preliminarily blending (B) with all or a part of the polyolefin (C) or EVOH (A), a method of dry blending a pulverized product of each resin, a method of blend pelletizing the above composition, and the like are available. can give.

Examples of means for blending the respective components for obtaining the resin composition of the present invention include a ribbon blender, a high speed mixer co-kneader, a mixing roll, an extruder and an intensive mixer.

The resin composition of the present invention may be blended with other conventional additives such as polyolefin. Examples of such additives include antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, and other polymer compounds, which are used in the present invention. It is possible to blend within a range in which the action and effect are not impaired. Specific examples of the additives include the following. Antioxidant: 2,5-t-butylhydroquinone, 2,
6-di-t-butyl-p-cresol, 4,4'-thiobis- (6-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), octadecyl- 3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,
4'-thiobis- (6-t-butylphenol) and the like.

UV absorber: ethylene-2-cyano-
3,3'-diphenyl acrylate, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole,
2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2- Hydroxy-4-octoxybenzophenone and the like.

Plasticizer: dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphoric acid ester and the like. Antistatic agent: pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins,
Polyethylene oxide, carbowax, etc. Lubricants: ethylene bis stearamide, butyl stearate, etc.

Coloring agents: carbon black, phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, red iron oxide and the like. Fillers: glass fiber, asbestos, mica, ballastonite, calcium silicate, aluminum silicate,
Calcium carbonate, etc. Also, many other polymer compounds can be blended within a range that does not impair the action and effect of the present invention. The resin composition of the present invention, when molded into a film, exhibits remarkable effects, but is not limited to film molding, and a well-known melt extrusion molding machine, compression molding machine, transfer molding machine, injection molding machine, blow molding machine, heat The same effect as that of the film can be obtained by using a molding machine, a rotation molding machine, a dip molding machine, or the like to form any molded product such as a sheet, a tube, a bottle, a cup, a tape, a tube, or a container.

When the resin composition of the present invention is used as one layer of a multilayer structure, it may have any layer structure of two or more layers. As a suitable example of the layer structure, when the resin composition of the present invention is represented by F, the polyolefin is represented by A, the EVOH is represented by B, and the adhesive is represented by AD, the following layer structure is obtained.

2-layer A / F 3-layer A / F / B, F / B / F, F / AD / B, A / F
/ A, F / A / F, F / AD / A 4 layers F / B / AD / A, A / F / AD / B, A / F /
AD / A 5 layers F / AD / B / AD / F, A / F / B / AD /
A, A / AD / F / AD / A, A / F / B / F / A, A
/ B / F / AD / A 6 layers A / F / AD / B / AD / A 7 layers A / F / AD / B / AD / F / A

Further, in such a multilayer structure, the resin composition of the present invention can be substituted by scrap of the multilayer structure. Further, scraps of other polyolefin molded bodies can be mixed and used. As a multi-layer molding method, generally, the number of extruders corresponding to the type of resin layer is used, this extruder is used, and in the layer state in which the flows of the resin melted in the extruder are superposed. The method carried out by so-called coextrusion in which coextrusion is performed is the best. As another method, a multilayer molding method such as extrusion coating or dry lamination can be adopted.

Further, it is possible to improve the physical properties of the molded product such as the above-mentioned film or multilayer structure by stretching if necessary. In the present invention, the composition is melt-molded to produce a molded product such as a film as a raw material. The molded product such as the film obtained as described above is subjected to a moisture conditioning process such as moisture absorption or drying, if necessary, and then subjected to stretching. The stretching may be uniaxial stretching or biaxial stretching. The effect of the present invention is exerted when the stretching is performed at the highest possible ratio. In the case of uniaxial stretching, it is preferably 1.5 times or more, particularly preferably 2 times or more. In the case of biaxial stretching, the area magnification is preferably 1.5 times or more, particularly preferably 2 times or more, and further preferably 4 times or more.

Examples of the stretching method include a roll stretching method, a tenter stretching method, a tubular stretching method and a stretching blow method.
Among draw forming and vacuum forming, those having a high draw ratio can be adopted. In the case of biaxial stretching, either a simultaneous biaxial stretching method or a sequential biaxial stretching method can be adopted. Stretching temperature is 40 ~
It is selected from the range of about 150 ° C. After the stretching is completed in this way, heat setting is then performed. The heat setting can be carried out by a well-known means, and while maintaining the stretched molded product (film etc.) in a tensioned state, the temperature is 50 to 160 ° C., preferably 80 to 160 ° C.
Heat treatment is performed at 160 ° C. for about 2 to 600 seconds.

The obtained stretch-molded product (film, etc.) is subjected to cooling treatment, rolling treatment, printing treatment, dry laminating treatment, solution or melt coating treatment, bag-making processing, drawing processing, box processing, tube processing, splitting, if necessary. Processing etc. can be performed. A film obtained from the composition of the present invention,
Sheets or containers are useful as various packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

[0034]

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 6 Various polyolefins (C), EVOH (A) (ethylene content: 28 mol%, saponification degree of vinyl acetate component: 99.8)
%, Melt flow index 1.2 g / 10 mi
n) and the graft polymer (B) are shown in Table 1. After dry blending with a blend ratio, the diameter is 40 mm, L / D = 24,
Pellets (F) were obtained by melt extrusion with an extruder having a full flight type screw with a compression ratio of 3.8. The composition (F) was extruded from a T-die at an extrusion temperature of 220 ° C. to a thickness of 2
A 0 μ film was formed. (However, a 180 μ film was used for stretchability evaluation)

(1) The obtained film was 20 ° C. × 65%
The humidity was adjusted to RH and 100% RH and the gas barrier property was measured (10/50 type, manufactured by Mokon Co.). As a result, good gas barrier property was exhibited even under high humidity. In addition, the number of cycles until pinholes were generated was measured using a Gelbo flex tester. (2) As for the stretchability, when subjected to simultaneous biaxial stretching (stretching ratio 3 × 3 times) by applying a pantograph type biaxial stretching machine at a stretching temperature of 70 ° C., good stretchability with less cracks, unevenness and uneven thickness was obtained. Indicated.

(3) A sheet was prepared by using the composition (F) as an intermediate layer and applying it to a feedblock type 3 type 5 layer coextrusion apparatus. The sheet is composed of both outermost polypropylene layers (Mitsubishi Noblen MA-6) of 800μ, adhesive resin layers (Mitsubishi Yuka's "Modic P-300F": maleic anhydride modified polypropylene) of 50μ each, and an intermediate layer (F). Is 50 μ. The sheet was subjected to a vacuum pressure air molding machine (stretching speed 9 × 10 ⁵ % / min, drawing ratio 1 stretched area ratio 7 times), and thermoformed (SPPF molding) at 150 ° C. The obtained molded product had good transparency and appearance, and was free from cracks and uneven thickness.

(4) Further, the composition (F) was used as an intermediate layer, and an outer layer: nylon 6 (MI = 48 g / 10 minutes) adhesive layer: maleic anhydride modified polypropylene (MI = 5.7).
g / 10 minutes), inner layer: propylene (MI = 8 g / 10
Min), a multi-layer film of 4 types and 4 layers was applied, and the retort suitability was evaluated. The thickness ratio of each layer is as follows: outer layer / intermediate layer (F) / adhesive layer / outer layer = 20 μ / 10 μ / 5 μ / 20 μ
Is. The appearance of the film after retorting at 120 ° C. for 30 minutes was good without delamination and whitening.

Comparative Examples 1 to 6 Film formation was carried out in the same manner as in Example 1 except that the graft polymer (C) was not used. The gas barrier properties, flexibility, stretchability and hot water resistance were all poor as compared with Example 1. The conditions and results are shown in Table 1.

Comparative Example 7 A film was formed in the same manner as in Example 1, except that polypropylene grafted with polyamide was used in place of polypropylene having epoxy groups grafted with polyamide in Example 1. The flexibility, stretchability, and hot water resistance were poor as compared with the examples. The conditions and results are shown in Table 1.

[0041]

[Table 1]

Example 7 A film was formed in the same manner as in Example 1 except that the polyolefin (C) was not used. The gas barrier property, flexibility, stretchability and hot water resistance were as good as those in Example 1. The conditions and results are shown in Table 1.

[0043]

EFFECT OF THE INVENTION A resin composition having excellent gas barrier properties under high humidity, hot water resistance, stretchability and flexibility can be obtained. Further, when used as a material for a retort container, there is no whitening after the retort.

Claims (2)

[Claims] 1. (A) Ethylene having an ethylene content of 20 to 65 mol% and a saponification degree of a vinyl acetate component of 90% or more.
The degree of polymerization of the saponified vinyl acetate copolymer and (B) the epoxy group-containing polyolefin resin (a) is 80 to 1,000.
Consisting of a polymer obtained by reacting the polyamide (b) of
(A) :( B) = resin composition whose weight ratio is 99.8-50: 0.2-50. 2. A resin composition according to claim 1, which is blended with a polyolefin (C), wherein (A) :( B) :( C) =
A resin composition having a weight ratio of 50 to 99.5: 0.1 to 15: 0.4 to 50.