JP2593952B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Technical Field of the Invention The present invention relates to a resin composition having a beautiful appearance, excellent gas permeation resistance, no delamination in layers, and excellent delamination resistance.

B. Conventional technology Because polyolefins are inexpensive, have excellent mechanical properties, are easy to process, and have good properties such as excellent transparency, excellent water vapor permeability, and excellent safety and health. Widely used as packaging materials for food, cosmetics, toiletry products, chemicals, etc. However, oxygen gas,
Due to the high gas permeability of carbon dioxide, etc., those that affect the quality of the contents due to the penetration of these gases cannot be used or can be used only for a very short period of time. .

In order to improve the gas permeation resistance of polyolefin, for example, it has been proposed to blend a gas-permeable saponified ethylene-vinyl acetate copolymer with polyolefin (JP-A-49-38984). However, in this method, in order to increase the adhesion between the blend and the polyolefin, the blend weight ratio of the polyolefin is 50% by weight based on the total weight.
In this case, the adhesiveness with polyolefin becomes strong at this time, but in the blend layer, the compatibility of polyolefin and saponified ethylene-vinyl acetate copolymer is poor, so that a flow abnormality occurs during molding, Bad appearance. Further, JP-A-53-39380 discloses a saponified ethylene-vinyl acetate copolymer 25 having a melt index three times or more higher than that of polyolefin per 100 parts by weight of polyolefin.
~ 60 parts by weight, ethylene content 70 ~ 98 mol%, saponification degree 20
% Or more of saponified ethylene-vinyl acetate copolymer
It is proposed to use parts by weight. However,
When the blended material layer is used for the external appearance, a matte pattern and a wavy pattern are formed, and the external appearance is remarkably impaired, which is not practical.

C. Problems to be Solved by the Invention The present invention improves the delamination in the layer which is considered to cause such poor compatibility, and has a large delamination resistance.
Another object of the present invention is to provide a resin composition which is excellent in gas permeation resistance, has no wave pattern, and obtains a molded article having a beautiful appearance.

D. Means for Solving the Problems The present inventors have proposed polyolefin (A), saponified ethylene-vinyl acetate copolymer (B) (hereinafter referred to as EVOH), ethylene content of 68 to 98 mol%, vinyl acetate A saponified ethylene-vinyl acetate copolymer (C) (hereinafter referred to as "S-EVOH") having a saponification degree of 20% or more, and a polyolefin resin (D) modified with an unsaturated carboxylic acid or a derivative thereof. When molded using a resin composition, there is no delamination, high delamination resistance, and excellent gas permeability resistance, and it is possible to obtain a film with a beautiful appearance without wave patterns. We have completed the present invention.

The polyolefin (A) referred to in the present invention is a copolymer of high-, medium-, or low-density polyethylene, vinyl acetate, acrylate, or α-olefins such as butene, hexene, and 4-methyl-1-pentene. Polyethylene, ionomer resin, polypropylene homopolymer, polypropylene graft-polymerized with ethylene, or polypropylene copolymerized with α-olefins such as ethylene, butene, hexene, 4-methyl-1-pentene, and modified by blending rubber-based polymer Polypropylene, poly 1-butene, poly 4-methyl-1-pentene, and the like. Of particular importance for the present invention are polypropylene resins, followed by polyethylene resins.

The EVOH (B) in the present invention includes any one as long as the vinyl acetate unit in the copolymer of ethylene and vinyl acetate is hydrolyzed, but has poor compatibility with polyolefin. These have relatively few ethylene units and a high degree of saponification (hydrolysis) of the vinyl acetate component. In particular, those having an ethylene content of 20 to 65 mol%, preferably 20 to 60 mol%, optimally 20 to 50 mol%, and a saponification degree of the vinyl acetate component of 96% or more, especially 99% or more Since an excellent film can be obtained when used in combination with polyolefin, it is particularly important as an application object of the present invention.

In addition, the melt flow index (MI) of EVOH (B)
(Measured at 190 ° C. under a load of 2160 g) is 0.1 g / 10 min or more, preferably 0.5 g / 10 min or more, and 100 g / 10 min or less, preferably 50 g / 10 min or less, and optimally 30g / 10min or less.

The EVOH (B) referred to in the present invention may be modified with a copolymer monomer in a range of 5 mol% or less. Examples of the modifying monomer include propylene, 1-butene, 1-hexene, 4-methyl-1- Pentene, acrylate,
Methacrylic acid esters, maleic acid, fumaric acid, itaconic acid, higher fatty acid vinyl esters, alkyl vinyl ethers, N- (2-dimethylaminoethyl) methacrylamides or quaternized products thereof, N-vinylimidazole or quaternized products thereof, N-vinylpyrrolidone, N,
Examples thereof include N-butoxymethylacrylamide, vinyltrimethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane.

In the present invention, S-EVOH (C) is a specially selected and newly developed special EVOH for the purpose of significantly improving the compatibility of polyolefin (A) and EVOH (B).
It is a saponified ethylene-vinyl acetate copolymer having an ethylene content of 68 to 98 mol% and a saponification degree of the vinyl acetate component of 20% or more. Particularly effective for improving compatibility is the ethylene content
It is at least 70 mol%, more preferably at most 96 mol%, most preferably at most 94 mol%. The more effective degree of saponification of the vinyl acetate component is 30 mol% or more, especially 40% or more. Although the upper limit of the degree of saponification is not particularly limited, those having a degree of saponification of substantially 100% can also be used.

If the ethylene content is less than 68 mol% or the degree of saponification of the vinyl acetate component is less than 20%, the compatibility with polyolefin is poor. If the ethylene content is 98 mol% or more, EV
Burning due to poor compatibility with OH, flow abnormalities occur, and appearance is significantly deteriorated.

The ethylene content of S-EVOH (C) is the EVOH of (B).
It is preferably at least 5 mol%, optimally at least 10 mol%, higher than the ethylene content of
The MI of S-EVOH (C) is 0.1 / 10 minutes or more, preferably 0.5 /
It is 10 minutes or more, 100 g / 10 minutes or less, preferably 50 g / 10 minutes or less, and most preferably 30 g / 10 minutes or less.

The S-EVOH (C) according to the present invention may be modified with an unsaturated carboxylic acid or a derivative thereof, and the acid monomer for modification is an α, β unsaturated carboxylic acid, an ester thereof or an anhydride thereof, Examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, monomethyl or ethyl esters of maleic acid and fumaric acid, maleic anhydride, and itaconic anhydride. These acid monomers are used alone or in combination.

When polyolefin (A) is melt-molded from a composition comprising EVOH (B), S-EVOH (C) is previously blended with polyolefin (A) or EVOH (B) or both (A) and (B). The effects of the present invention become even more pronounced if the blended pellets are blended with the composition and melt-molded.

As an example of preliminarily blending S-EVOH (C) with EVOH (B), 5 parts of S-EVOH (C) are added to 100 parts of EVOH (B).
100100 parts are included. Thus, when S-EVOH (C) is previously blended with EVOH (B), the effect is large even if the amount of S-EVOH (D) is reduced.

The polyolefin resin (D) modified with an unsaturated carboxylic acid or a derivative thereof according to the present invention is an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, and the like. ,
Ester or anhydride thereof; methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate, sodium methacrylate And the like. Polyolefin resins modified with at least one unsaturated carboxylic acid selected from the group consisting of: Here, as the polyolefin resin, polyethylene, polypropylene, ethylene-vinyl acetate, acrylate copolymer, and the like are preferable.

The mixing ratio of each component of the resin composition of the present invention is as follows.

The composition ratio of polyolefin (A) and EVOH (B) is 6 by weight ratio of polyolefin (A): EVOH (B).
The range of 0:40 to 99.1: 0.1, especially 65:35 to 99.7: 0.3 is particularly important in terms of the effect of the present invention.

The addition amount of S-EVOH (C) is the same as that of polyolefin (A).
Practically 0.3 to 100 parts by weight of the total amount of EVOH (B)
30 parts by weight, especially 0.3 to 20 parts by weight, more preferably 0.3
Used in the range of ~ 10 parts by weight. If the amount is less than 0.3 part by weight, the effect of improving compatibility is not seen, which is not preferable. Although there is no upper limit, 30 parts by weight or less is sufficient for practical use.

The mixing ratio of the polyolefin resin (D) modified with the unsaturated carboxylic acid or its derivative is 0.5 to 60 parts by weight, preferably 1 to 100 parts by weight of the total amount of the polyolefin (A) and the EVOH (B). 5050 parts by weight.

The blending method for obtaining the composition of the present invention is not particularly limited, and a method of dry blending the four, S-EVOH
A method in which (C) is previously blended with all or a part of polyolefin (A) or EVOH (B), or
Examples of the method include a method of dry-blending the pulverized product of each resin and a method of blending the above composition into a blend pellet.

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

In the present invention, by using S-EVOH (C) and modified polyolefin (D) in combination, the compatibility of the polyolefin (A) and EVOH (B) in the melt-molded product is remarkably improved, and the wave pattern is further improved. Although the mechanism for preventing the occurrence of matte and preventing in-layer delamination is not sufficiently clear, S-EVOH (C) and S-EVOH (C) are used in a state where the rheological effect and dispersing action in a molten system of polyolefin and EVOH are combined in a complicated manner. It is presumed that the synergistic effect of the modified polyolefin resin (D) is acting effectively.

In addition, the resin composition of the present invention may contain, for example, other additives commonly used in polyoff-in. Examples of such additives include antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, coloring agents, fillers, or other high molecular compounds, which are used in the present invention. Blending can be performed within a range where the effect is not inhibited. Specific examples of the additives include the following.

Antioxidants: 2,5-di-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-octoxybenzophene Non etc.

Plasticizer: dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester and the like.

Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, carbowax and the like.

Lubricants: ethylene bis stearamide, butyl stearate and the like.

Coloring agent: carbon black, phthalocyanine, quinacridone, indoline, azo pigment, titanium oxide, red iron oxide, etc.

Filler: glass fiber, asbestos, mica, ballastonite, calcium silicate, aluminum silicate, calcium carbonate, etc.

Many other high molecular compounds can also be blended to such an extent that the effects of the present invention are not impaired.

The resin composition of the present invention is not limited to film molding, but includes a known melt extrusion molding machine, compression molding machine, transfer molding machine, injection molding machine, blow molding machine, thermoforming machine, rotary molding machine, date molding machine, and the like. Use, sheets, tubes, bottles,
The same effect as that of a film can be obtained by molding into an arbitrary molded article such as a cup.

When the resin composition of the present invention is used as one layer of a multilayer structure, it can have an arbitrary layer structure of two or more layers. As a suitable example of the layer constitution, when the resin composition of the present invention is represented by F, polyolefin is represented by A, EVOH is represented by B, and the adhesive is represented by AD, the following layer constitution is obtained. Here, it is preferable to use the modified polyolefin (D) used in the present invention as AD.

2-layer A / F 3-layer A / F / B, F / B / F, F / AD / B 4-layer F / B / AD / A, A / F / AD / B 5-layer F / AD / B / AD / F, A / F / B / AD / A, A / F / B / F / A 6 layers A / F / AD / B / AD / A 7 layers A / F / AD / B / AD / F / A In such a multilayer structure, the resin composition of the present invention can be replaced by a scrap of the multilayer structure. It is also possible to use a mixture of scraps of other polyolefin moldings.

As a multilayer molding method, generally, when using a number of extruders corresponding to the type of resin layer, using this extruder,
The best method is the so-called co-extrusion, in which the flow of the resin melted in the extruder is simultaneously extruded in a superposed layer state. As another method, a multi-layer molding method such as extrusion coating and dry lamination may be employed.

Since the multi-layer structure having the above-mentioned layer structure contains EVOH having excellent gas barrier properties, food packaging materials and medical products (pharmaceuticals, medical devices, etc.) that require gas barrier properties in particular.
Useful as packaging material. In particular, a multilayer structure composed of at least two layers of the EVOH (B) layer and the resin composition (F) layer is preferable because it is excellent in gas barrier.

Polyolefin (A), EVOH (B),
In the resin composition comprising S-EVOH (C) and modified polyolefin (D), it is important to use both S-EVOH (C) and modified polyolefin (D). (A),
When only (C) or (D) is blended with (B), delamination resistance between the polyolefin layer and the blended resin composition layer is poor, which is not preferable. By using (C) and (D) in combination, the delamination resistance is improved,
A resin composition having not only a beautiful appearance but also excellent gas permeation resistance can be obtained.

Hereinafter, the present invention will be described more specifically with reference to examples. Parts mean parts by weight.

E. Examples Examples 1 to 8 Two- and three-layer coextruded films in which the inner and outer layers were low-density polyethylene and the intermediate layer was a resin blend composition were produced. The resin composition of the intermediate layer is low-density polyethylene (A) (Melt Flow Index ASTM-D-1238, 2.1 g / 10 min), EVO
H (B) (ethylene content 32.5 mol%, saponification degree of vinyl acetate component 99.9%, melt flow index 1.4 g / 10
), S-EVOH (C) (ethylene content 74 mol%, saponification degree of vinyl acetate component 82%, melt flow index
4.9 g / 10 min) and maleic anhydride-modified polyethylene (D) (adhesive resin) (ADMER LF-50 manufactured by Mitsui Petrochemical Co., Ltd.)
0), and was melt-extruded with an extruder having a full flight type screw having a diameter of 40 mm, L / D = 24, and a compression ratio of 3.8, to obtain a pellet (E). The inner and outer low-density polyethylene layers
An extruder having a screw of 45 mm and L / D = 22. The blend composition (E) of the intermediate layer was prepared by an extruder having a diameter of 35 mm and a screw of L / D = 23. Co-extrusion using a layer die, the thickness of the blend layer is 20
μ, a film having a total thickness of 60 μ was obtained. Appearance of the obtained co-extruded film, adhesive strength between low-density polyethylene layer and blend layer (90 ° peeling, tensile speed 100 mm / min), oxygen gas permeation (OX-TRAN 10-50A manufactured by ModernControl, 20 ° C., 0 ° C.)
% RH) was measured. The results are shown in Table 1.

Comparative Example 1 Low Density Polyethylene (Melt Flow Index ASTM
-D-1238, 2.1 g / 10 min) was charged into an extruder having a screw having a diameter of 45 mm and a L / D = 22, and a single-layer film was formed using a flat die having a width of 550 mm. Deposition temperature is controlled by the extruder
The film was heated at 190 to 220 ° C. and the die at 220 ° C. to obtain a 60 μm thick film. Table 1 shows the measurement results of the oxygen permeation amount.

Comparative Example 2 Coextruding two and three layers of polyethylene and a blended resin in the same manner as in Example 1 except that maleic anhydride-modified polyethylene (adhesive resin) was not used in the blend resin composition of the intermediate layer. I got a film.

The appearance was poor, and the peel strength was 50 g / 15 mm, and the delamination resistance was poor.

Comparative Example 3 Example 4 was repeated except that no maleic anhydride-modified polyethylene (adhesive resin) was used in the blend layer.
In the same manner as described above, a coextruded film of two types and three layers was obtained.

Wavy patterns and satin were observed on the film surface, and the appearance was very poor.

Comparative Example 4 The intermediate layer was made of the low-density polyethylene 10 used in Example 1.
A coextruded film of two and three layers was obtained in the same manner as in Example 1 except that the blend composition was 0 parts, 70 parts of EVOH used in Example 1, and 20 parts of S-EVOH used in Example 1. Although the oxygen gas permeation amount was the best, the layer was delaminated and the appearance was poor.

Comparative Examples 5 to 6 In Example 1, S-EVOH was not used for the blend layer, and a non-modified polyolefin resin was used in the amount shown in Table 1, and the other two layers were used in the same manner as in Example 1. Was obtained.

The resulting film has wavy pattern and satin finish on the surface,
The appearance was very poor, the layer was peeled off, and the peel strength was poor.

Example 9 A polypropylene resin (A) (melt flow index ASTM-D-1238, 0.5 g / 10 minutes) was used in place of the low density polyethylene resin (A) in Example 4, and a maleic anhydride-modified polyethylene (A) was used. D) (Adhesive resin)
(ADMERLF-500 manufactured by Mitsui Petrochemical) instead of maleic anhydride-modified polypropylene adhesive resin (D) (ADMER QF
−500). Others are the same as in Example 4,
A coextruded film of two types and three layers of a polypropylene resin for the inner and outer layers and a blended resin composition for the intermediate layer was obtained.

The appearance was good, and the peel strength was 595 g / 15 mm and the oxygen gas permeation amount was 20.1 cc / m ² · day · atm.

Comparative Example 5 A coextruded film of two and three layers was obtained in the same manner as in Example 9 except that no maleic anhydride-modified polypropylene (adhesive resin) was used in the blend layer.

Wavy patterns and satin were observed on the film surface, and the appearance was poor. Peel strength 520g / 15mm, oxygen gas permeation 20.3cc / m ²・
It was day / atm.

Example 10 A coextruded sheet of two and three layers in which the inner and outer layers were a polypropylene resin and the intermediate layer was a resin blend composition was prepared. The composition of the intermediate layer is 100 parts of polypropylene (A) (Melt Flow Index ASTM-D-1238, 0.5 g / 10 min), EVOH (B)
(Ethylene content 32.5 mol%, saponification degree of vinyl acetate component 99.9%, melt flow index 1.4 g / 10 min) 30
Parts, S-EVOH (C) (ethylene content 74 mol%, saponification degree of vinyl acetate component 82%, melt flow index 4.
9 g / 10 min) 10 parts and maleic anhydride-modified polypropylene (D) (adhesive resin) (ADMER QF-5 manufactured by Mitsui Petrochemical)
00) has a blend ratio of 5 parts. Polypropylene (A)
Is an extruder having a diameter of 65 mm and an L / D = 22 uniaxial screw at a temperature of 200 to 240 ° C., and the blended resin composition has an extruder having a diameter of 40 mm and an L / D = 26 uniaxial screw. 1
As the temperature of 60 ~ 220 ℃, feed block die (width 6
00mm) at 240 ° C, the thickness of the intermediate layer is 100μ and the total thickness is 1000μ
Sheet was obtained. The obtained sheet was a sheet having no corrugation, satin finish and good appearance without delamination.

F. Effect of the Invention The resin composition of the present invention is a composition excellent in gas permeation resistance and has no in-layer peeling property, and a molded product obtained from this composition has no wavy pattern and a beautiful appearance. Moreover, it has excellent delamination resistance.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-142053 (JP, A) JP-A-57-32952 (JP, A) JP-A-53-39380 (JP, A)

Claims (1)

(57) [Claims] (A) Polyolefin (B) Saponified ethylene-vinyl acetate copolymer having an ethylene content of 20 to 65% by mole and a saponification degree of a vinyl acetate component of 96% or more (C) Ethylene content 68 (A): a saponified ethylene-vinyl acetate copolymer having a saponification degree of the vinyl acetate component of 20% or more and (D) a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof; (B) weight ratio of 60: 40-99.1
The amount of (C) is 0.3 to 30 parts by weight based on 100 parts by weight of the total of (A) and (B), and the amount of (D) is the total of (A) and (B). The resin composition is 0.5 to 60 parts by weight based on 100 parts by weight.