JPH0770378A - Resin composition - Google Patents

Abstract

PURPOSE:To provide a multilayer construction improved in appearance, gas permeability and intralaminar and inter-laminar peeling resistance by using a layer made of a mixture prepared by mixing polyethylene with an ethylene/ vinyl acetate saponificate, a propylene/vinyl acetate copolymer saponificate and an unsaturated-carboxylic-acid-modified polyolefin. CONSTITUTION:A polyolefin (A) is mixed with an ethylene/vinyl acetate copolymer saponificate (B) having an ethylene content of 20-65mol% and a degree of saponification of the vinyl acetate component of 96% or above, a propylene/ vinyl acetate copolymer saponificate (C) having a propylene content of 20-98mol%, a degree of saponification of 20% or above and a melt index of 0.1-100g/10min and a polyolefin (D) modified with an unsaturated carboxylic acid or its derivative in such amounts that the A:B ratio is 60:40 to 99.1 :0.1, and 0.3-30 pts.wt. component C and 0.5-60 pts.wt. component D are present per 100 pts.wt. total of components A and B. The obtained compounded resin is molded into a layer of a multilayer constitution, such as an interlayer of a tri-layer construction.

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 a beautiful appearance, excellent gas permeation resistance, no intra-layer peeling property and excellent inter-layer peeling resistance.

[0002]

2. Description of the Related Art 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,
The fact that the quality of the contents is affected by the invasion of these gases cannot be used or can be used only for an extremely short time.

In order to improve the gas permeation resistance of polyolefins, for example, it has been proposed to blend polyolefin with a saponified ethylene-vinyl acetate copolymer having gas permeation resistance (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.

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 per 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, the content of ethylene is 100 parts by weight in total of 60:40 to 99.1: 0.1 saponified polyolefin: ethylene-vinyl acetate copolymer. Ratio of 68 to 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 to 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.

[0006]

DISCLOSURE OF THE INVENTION The present invention improves intralayer delamination, which is considered to be caused by such poor compatibility, has large delamination resistance, and is excellent in gas permeation resistance. It is intended to provide a resin composition which gives a molded product having a beautiful appearance and having no wavy pattern.

[0007]

The present inventors have found that the polyolefin (A), the saponified ethylene-vinyl acetate copolymer (B) (hereinafter referred to as EVOH), the propylene content 2
A polyolefin modified with 0-98 mol% and a saponification degree of a vinyl acetate component of 20% or more (C) (hereinafter referred to as S-EVOH) and an unsaturated carboxylic acid or a derivative thereof. When a resin composition composed of the resin (D) is used for molding,
The present invention has been completed by discovering that a film having no delamination, a large resistance to delamination, and a high gas permeation resistance, and having a beautiful appearance with no wave pattern can be obtained.

The polyolefin (A) referred to in the present invention means
High-density, medium-density or low-density polyethylene, vinyl acetate, acrylic acid ester, or polyethylene obtained by copolymerizing butene, hexene, α-olefins such as 4-methyl-1-pentene, ionomer resin, polypropylene homopolymer, ethylene Graft-polymerized polypropylene, or ethylene, butene, hexene,
It includes polypropylene copolymerized with α-olefins such as 4-methyl-1-pentene, modified polypropylene blended with a rubber-based polymer, poly-1-butene, poly-4-methyl-1-pentene, and the like. Of particular importance to the present invention are polypropylene resins and then polyethylene resins.

The EVOH (B) referred to in the present invention includes any one as long as it hydrolyzes a vinyl acetate unit in a copolymer of ethylene and vinyl acetate, but has compatibility with polyolefin. Poor ones have relatively few ethylene units and a high degree of saponification (hydrolysis) of the vinyl acetate component. In particular, the ethylene content is 20 to 65 mol%, preferably 20 to 60 mol%, most preferably 20 to 50 mol%, and the vinyl acetate component has a saponification degree of 9
6% or more, particularly 99% or more, is particularly important as an application target of the present invention, because an excellent film can be obtained by using it in combination with a polyolefin. Also, EVOH (B) melt flow index (MI)
(Measurement under load of 2160 g at 190 ° C: However, if the melting point is around 190 ° C or exceeds 190 ° C, it is 216
Measured under a load of 0 g at a plurality of temperatures equal to or higher than the melting point and plotted on a semilogarithmic graph with the reciprocal of absolute temperature plotted as the horizontal axis and the melt index as the vertical axis, and the value extrapolated to 190 ° C.) 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 (B) referred to in the present invention may be modified with a copolymerization monomer in the range 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, S-EVOH (C) is a specially developed and newly developed special EVOH for the purpose of significantly improving the compatibility of the polyolefins (A) and EVOH (B). Propylene content 20-98
It is a propylene-vinyl acetate copolymer saponified product having a mol% and a saponification degree of the vinyl acetate component of 20% or more. This S-E
By using VOH (C), the compatibility of the polyolefin (A) and EVOH (B) and the delamination strength are significantly improved. The reason for this is not clear,
It is considered that the presence of the propylene component in S-EVOH (C) improves the compatibility of the polyolefin (A) and EVOH (B), and the ethylene content of the S-EVOH (C) is 20 to 20%. An ethylene-vinyl acetate copolymer saponified product having 98 mol% and a saponification degree of 20% or more may be added, and S-EVOH (C) is used as the ethylene-propylene-vinyl acetate copolymer saponified product. May be. Particularly, the propylene content of 30 mol% or more is effective for improving the compatibility. The more effective degree of saponification of the vinyl acetate component is 30 mol% or more, especially 40% or more. The upper limit of the saponification degree is not particularly limited, but those having a saponification degree of substantially 100% can also be used.

S-EV having a propylene content of less than 20 mol% or a saponification degree of the vinyl acetate component of less than 20%
OH (C) has poor compatibility with polyolefin. Also,
S-EVOH with a propylene content of 98 mol% or more
Since (C) has a poor compatibility with EVOH, it scorches during molding and causes abnormal flow, resulting in a markedly poor appearance. Also S-E
The melt index (MI) of VOH (C) is 0.1 /
10 minutes or more, preferably 0.5 g / 10 minutes or more, 1
The amount is 00 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) referred to in the present invention may be modified with an unsaturated carboxylic acid or its derivative,
Such modifying acid monomers include α, β unsaturated carboxylic acids, their esters and their anhydrides, and acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, monomethyl or ethyl esters of maleic acid and fumaric acid, anhydrous Examples thereof include maleic acid and itaconic anhydride. These acid monomers may be used alone or in combination.

Further, S-EVOH (C) has an ethylene content of 20 to 98 mol% and a vinyl acetate component having a saponification degree of 2
The saponification product (E) of ethylene-vinyl acetate copolymer, which is 0% or more, is 99: 1 to 1: 9 in a weight ratio of (C) :( E).
It may be added in a ratio of 9. Furthermore, S-EVO
H (C) is propylene: ethylene = 99: 1 to 1:99
It may be used as a saponified product of an ethylene-propylene-vinyl acetate copolymer copolymerized at a ratio of.

When melt-molding a composition comprising polyolefin (A) and EVOH (B), S-EVOH
(C) is preliminarily treated with polyolefin (A) or E
The effect of the present invention becomes more remarkable when VOH (B) or both (A) and (B) is blended and pelletized and then blended with the above composition and melt-molded. S-
As an example of blending EVOH (C) with EVOH (B) in advance, S-EVO is added to 100 parts of EVOH (B).
The thing which mix | blended 5-100 parts of H (C) is mentioned. In this way, S-EVOH (C) was previously
When blended with (B), the effect is great even if the amount of S-EVOH (C) added is reduced.

The polyolefin resin (D) modified with an unsaturated carboxylic acid or a derivative thereof as used in the present invention means an acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid or the like. Saturated carboxylic acid, its ester or its anhydride; methyl acrylate, methyl methacrylate, ethyl acrylate,
At least one kind selected from the group consisting of propyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate, glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate, unsaturated carboxylic acid derivatives such as sodium methacrylate; The polyolefin resin modified by the unsaturated carboxylic acid or its derivative or its blend.
Preferred examples of the polyolefin resin include polyethylene, polypropylene, ethylene-vinyl acetate, and acrylic acid ester copolymer.

The mixing ratio of each component of the resin composition of the present invention is as follows. Polyolefin (A) and EVOH
The composition ratio of (B) is as follows: polyolefin (A): EV
The weight ratio of OH (B) is 60:40 to 99.1: 0.
1, particularly in the range of 65:35 to 99.7: 0.3 is particularly important in terms of the effect of the present invention.

The amount of S-EVOH (C) added is 0.3 parts by weight or more, practically 0.3 to 30 parts by weight, based on 100 parts by weight of the total amount of polyolefin (A) and EVOH (B). , Particularly 0.3 to 20 parts by weight, more preferably 0.
It is used in the range of 3 to 10 parts by weight. If the amount is less than 0.3 parts by weight, the effect of improving compatibility is not observed, which is not preferable. The upper limit is not always necessary, but 30 parts by weight or less is practically sufficient.

The proportion of the polyolefin resin (D) modified with an unsaturated carboxylic acid or its derivative is 0.5 to 60 parts by weight based on 100 parts by weight of the total amount of the polyolefin (A) and EVOH (B). It is preferably 1 to 50 parts by weight.

The blending method for obtaining the composition of the present invention is not particularly limited, and a method of dry-blending four types, that is, S-EVOH (C) is added to all or one of polyolefin (A) or EVOH (B). Examples thereof include a method of preliminarily blending in each part, a method of dry blending a pulverized product of each resin, and a method of blend pelletizing the above composition. Examples of means for blending the respective components for obtaining the composition of the present invention include a ribbon blender, a high speed mixer co-kneader, a mixing roll, an extruder and an intensive mixer.

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, Although the mechanism for preventing delamination is not clear, the rheological effect of polyolefin and EVOH in the molten system,
S-E in the state where the dispersion action is complicatedly combined
It is presumed that the synergistic effect of VOH (C) and modified polyolefin resin (D) acts effectively.

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. The following are specific examples of the additive.

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-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 and the like.

Lubricants: ethylene bis stearamide, butyl stearate, etc.

Coloring agents: carbon black, phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, red iron oxide and the like. Filler: glass fiber, asbestos, mica, ballastonite, calcium silicate, aluminum silicate,
Calcium carbonate, etc. Also, many other polymer compounds can be blended to the 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 is well-known melt extrusion molding machines, compression molding machines, transfer molding machines, injection molding machines, blow molding machines, thermoforming machines, rotational molding machines, dip molding machines. The same effect as that of the film can be obtained by molding into any molded product such as a sheet, a tube, a bottle, a cup, etc.

When the resin composition of the present invention is used as one layer of a multi-layer structure, it may have any 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, the polyolefin is represented by A, the EVOH is represented by B, and the adhesive is represented by AD, the following layer constitution is obtained. AD here
It is preferable to use the modified polyolefin (D) used in the present invention. 2 layers A / F 3 layers A / F / B, F / B / F, F / AD / B 4 layers F / B / AD / A, A / F / AD / B 5 layers 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 may be replaced with scraps 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.

Since the multi-layer structure having the above-mentioned layer structure contains EVOH having excellent gas barrier properties, it is particularly required for food packaging materials and medical products (pharmaceutical products, pharmaceutical products, which require gas barrier properties).
It is useful as a packaging material such as medical equipment. Especially EVO
A multilayer structure composed of at least two layers of the H (A) layer and the resin composition (F) layer is preferable because it is excellent in gas barrier.

Polyolefin (A), E in the present invention
In a resin composition comprising VOH (B), S-EVOH (C) and modified polyolefin (D), S-EVO
It is important to use both H (C) and modified polyolefin (D). (A), (B) to (C) or (D)
When blending only these, the delamination resistance of the polyolefin layer and the blended resin composition layer is poor, which is not preferable. By using (C) and (D) in combination, it is possible to obtain a resin composition having improved delamination resistance and not only a good appearance but also excellent gas permeation resistance.

[0034]

EXAMPLES Hereinafter, the present invention will be described more specifically by way of examples.
The parts mean parts by weight. Examples 1 to 8 Two-kind three-layer coextruded films were prepared in which the inner and outer layers were low-density polyethylene and the middle layer was a resin blend composition. The resin composition of the intermediate layer is low density polyethylene (A) (melt flow index ASTM-D-1238, 2.1 g /
10 minutes), EVOH (B) (ethylene content 32.5 mol%, saponification degree of vinyl acetate component 99.9%, melt flow index 1.4 g / 10 minutes), S-EVOH
(C) (Propylene content 74 mol%, saponification degree of vinyl acetate component 82%, melt flow index 2.5 g
/ 10 min) and maleic anhydride-modified polyethylene (D) (adhesive resin) (ADMER L manufactured by Mitsui Petrochemical Co., Ltd.)
F-500), and after dry blending with the blending ratio shown in Table 1, diameter is 40 mm, L / D = 24, compression ratio is 3.8.
The pellets (F) were obtained by melt-extruding with an extruder having a full flight type screw. An extruder having a screw having a diameter of 45 mm and a L / D = 22 for the low-density polyethylene layer as the inner and outer layers, and a blend composition (F) for the middle layer having a diameter of 3
Coextrusion was performed using an extruder having a screw of 5 mm and L / D = 23 using a type 2 three-layer die having a temperature of 220 ° C. to obtain a film having a blend layer thickness of 20 μ and a total thickness of 60 μ. Appearance of the obtained coextruded film, adhesive strength of the low density polyethylene layer and the blend layer (90 ° peeling,
Tensile speed 100 mm / min), Oxygen gas permeation amount (Moden Control OX-TRAN)
10-50A, 20 degreeC, 0% RH) was measured. The results are shown in Table 1 and Table 2.

[0035]

[Table 1]

[0036]

[Table 2] In Table 2, "excellent" in appearance means a state in which no wavy pattern, satin pattern, or phase separation is observed in the external appearance of the coextruded film.

Comparative Example 1 Low density polyethylene (melt flow index AST
MD-1238, 2.1 g / 10 minutes) with a diameter of 45 m
It was charged into an extruder having a screw of m and L / D = 22, and a single layer film formation was carried out using a flat die having a width of 550 mm. The film forming temperature was set at 190 to 220 ° C. for the extruder and 220 ° C. for the die, and a film having a thickness of 60 μm was obtained. Table 4 shows the measurement results of the amount of oxygen permeation.

Comparative Example 2 The same procedure as in Example 1 except that maleic anhydride-modified polyethylene (adhesive resin) was not used in the blend resin composition of the intermediate layer in Example 1, and two layers of polyethylene and blend resin were used. A coextruded film of was obtained. The appearance was poor, and the peeling strength was 50 g / 15 mm, and the delamination resistance was poor.

Comparative Example 3 A coextruded film of 2 types and 3 layers was obtained in the same manner as in Example 4 except that maleic anhydride-modified polyethylene (adhesive resin) was not used in the blend layer. A wavy pattern and a satin finish were found on the film surface, and the appearance was very poor.

Comparative Example 4 The low density polyethylene 10 used in Example 1 was used as the intermediate layer.
A two-kind three-layer coextruded film was obtained in the same manner as in Example 1, except that the blend composition was 0 part, 70 parts of EVOH used in Example 1 and 20 parts of S-EVOH used in Example 1. The oxygen gas permeation amount was the best, but the appearance was poor due to intra-layer delamination. Comparative Example 1 above
The results of ~ 4 are summarized in Tables 3 and 4.

[0041]

[Table 3]

[0042]

[Table 4] In Table 4, the appearance "poor" means a state in which the coextruded film has a wavy pattern or a satin pattern.

Example 9 Polypropylene resin (A) (melt flow index ASTM-D-1238, 0.5 g / 10 min) was used in place of low density polyethylene resin (A) in Example 4, and maleic anhydride was used. Modified polyethylene (D)
(Adhesive resin) (ADMER LF-5 manufactured by Mitsui Petrochemical Co., Ltd.
00) was replaced with maleic anhydride modified polypropylene adhesive resin (D) (ADMER QF-500). Otherwise, in the same manner as in Example 4, a coextruded film of polypropylene resin for the inner and outer layers and a blended resin composition for the intermediate layer was prepared. Appearance is good, peel strength 595g / 15mm, oxygen gas permeation rate 20.1cc / m
^{It was 2} · day · atm.

Comparative Example 5 Example 9 was repeated except that maleic anhydride modified polypropylene (adhesive resin) was not used in the blend layer.
A two-kind three-layer coextruded film was obtained in the same manner as in. A wavy pattern and a satin finish were found on the film surface, and the appearance was poor. Peel strength 520g / 15mm, oxygen gas permeation amount 20.3c
It was c / m ² · day · atm.

Example 10 A two-kind three-layer coextrusion sheet having a polypropylene resin as the inner and outer layers and a resin blend composition as the intermediate layer was prepared. The composition of the intermediate layer is polypropylene (A) (melt flow index ASTM-D-1238, 0.5 g / 10 minutes) 10
0 part, 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-EVO
H (C) (Propylene content 74 mol%, Saponification degree of vinyl acetate component 82%, Melt flow index 2.5
g / 10 minutes) 10 parts and maleic anhydride modified polypropylene (D) (adhesive resin) (ADME manufactured by Mitsui Petrochemical Co., Ltd.)
RQF-500) with a blend ratio of 5 parts. Polypropylene (A) has a diameter of 65 mm, L / D = 22 with an extruder equipped with a single screw, the temperature of 200 to 240 ° C., the blended resin composition has a diameter of 40 mm, L / D =
Extruder equipped with 26 single screw 160-220
Feed block die (width 600m)
m) at 240 ° C., intermediate layer thickness 100 μ, total thickness 1
A sheet of 000μ was obtained. The obtained sheet had no wavy pattern or satin finish, and had a good appearance without peeling within layers.

Comparative Example 6 S-EVOH (C) was changed to one having an ethylene content of 74 mol%, a vinyl acetate component having a saponification degree of 82%, and a melt flow index of 4.9 g / 10 min. In the same manner as in Example 1, a coextruded film of two types and three layers was obtained. As shown in Table 4 of the measurement results of the film, no wavy pattern or satin finish was observed on the film surface, which was good, but the amount of the adhered substance on the inner surface of the die after the single-layer film formation was large at about 1.0 g.

[0047]

Industrial Applicability The resin composition of the present invention is a composition having excellent gas permeation resistance and no intra-layer peeling property, and the molded product obtained from this composition has no wavy pattern and has a beautiful appearance. Moreover, the delamination resistance is excellent.

Claims (1)

[Claims] 1. (A) Polyolefin, (B) ethylene content of 20 to 65 mol%, saponified ethylene-vinyl acetate copolymer having a saponification degree of vinyl acetate component of 96% or more, (C) propylene content. A resin composition comprising 20 to 98 mol% and a saponification product of a propylene-vinyl acetate copolymer having a vinyl acetate component saponification degree of 20% or more, and (D) a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof.