JPH0441536A - Resin composition - Google Patents

Abstract

PURPOSE:To provide a resin composition excellent in flexibility, impact resistance, heat sealability, etc., by mixing an olefin/vinyl acetate copolymer saponificate resin with a specified silane-modified polyolefin resin in a specified weight ratio. CONSTITUTION:5-95wt.% olefin/vinyl acetate copolymer saponificate resin (e.g. ethylene/vinyl acetate copolymer saponificate resin) is mixed with 95-5wt.% polyolefin resin (e.g. polyethylene) modified with an unsaturated silane compound (e.g. vinyltriacetoxysilane) or a glycidylated silane compound (e.g. gamma- glycidoxypropyltrimethoxysilane) to produce a resin composition. The obtained resin composition can be desirably used for food packaging materials, pharmaceutical packaging materials, cosmetic packaging materials, containers requiring gas barrier properties, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a resin composition, and more specifically, it has excellent melt moldability, gas barrier properties, and mechanical strength, has no pinholes or cranks, and can be molded into a container. The present invention relates to a saponified olefin-vinyl acetate copolymer resin composition which is free from local thickness deviations, has excellent heat stretchability and adhesive properties, and has good heat release properties.

[Conventional technology]

Conventionally, ethylene-vinyl acetate saponified resin (hereinafter referred to as E
VOH (sometimes abbreviated as VOH) takes advantage of its characteristic gas barrier properties and is intended for use in foods and drugs that require barrier properties (shielding properties) against oxygen, such as food packaging materials, cosmetic packaging materials, and drug packaging materials. Used for packaging materials.

However, EVOH is hard and very brittle and breaks easily, and since it has a hydroxyl group in its molecule, it is sensitive to water and water vapor, and has the drawback that its gas barrier properties are significantly deteriorated by moisture absorption.

In order to solve this drawback, a multilayer laminate is used in which EVOH is laminated with one or more polyolefin polymers such as polyethylene and polypropylene, or one or more polymers such as polyester, polystyrene, and polyvinyl chloride.

These lamination methods include the so-called co-extrusion molding method, dry lamination molding method, extrusion lamination molding method, solution coating molding method, etc. in which polyolefin, EVOH, and their adhesive resin are extruded from each extruder and laminated. As a result, molded products in the shape of sheet films and bottles have been obtained.

Regarding sheets, in order to make packaging containers, the original fabric of the EVOH multilayer laminate is subjected to secondary processing such as thermoforming such as vacuum forming or pressure forming.

Most of these are molded under molding conditions that match the resin with the lowest melting point among the materials constituting the multilayer laminate. Therefore, EVOH, which has a high melting point, tends to have fine voids (so-called voids) and cracks in its layer during secondary processing.

Further, due to the high crystallization speed of EVOH, such voids and cracks, as well as local thickness unevenness, etc. occur. In particular, in deep drawing, since the drawing ratio is large, such a phenomenon tends to occur at corners, and therefore there is a limit to its use.

On the other hand, in bottle molding, such a phenomenon tends to occur when a parison is expanded and molded into a bottle shape.

In addition, pinholes easily occur in film due to bending motion during the distribution stage, and EVOH
In some cases, the gas barrier properties of

If racks, pinholes, uneven thickness, etc. occur like this,
Oxygen barrier properties may be significantly reduced, appearance may be poor, and the adhesive resin and EVOH may peel between the eyebrows, resulting in limitations or difficulties when used as packaging containers.

As a method to solve such problems, a method of blending polyamide resin with EVOH (Japanese Patent Application Laid-Open No. 59-20
No. 345, No. 62-106944 and No. 62
-22840), and also a mixture of glycerin, various glycols, and hydroxyl group-containing plasticizers (JP-A-538
8067), EVOH copolymerized with a pyrrolidone ring
(Japanese Unexamined Patent Publication No. 62-11644), a method of crosslinking EVOH with silane (Japanese Unexamined Patent Application No. 51-20946, 6
No. 0-144304, No. 60-170672,
61-290047, 61-290048),
There has been a method of blending EVOH with lithium chloride and an aromatic or aliphatic amide or a polyhydric alcohol compound (JP-A-61-281147, JP-A-61-283643, JP-A-61-283644).

However, all of these had the following problems and were not fully satisfactory. That is, when a polyamide resin is blended with EVOH, the polyamide and EVOH react during melt molding to generate gel fisheye. Moreover, in order to solve these problems, a special polyamide resin is required, which poses a problem in terms of cost.

Method of improving impact strength by mixing EVOH with ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, etc.
-81448, 62230840), etc. However, even with these, problems such as gel formation and insufficient impact strength existed, and these were not satisfactory.

On the other hand, glycerin, various glycols, and hydroxy group-containing plasticizers have poor compatibility with EVOH, so the problem is that the plasticizer bleeds over time and the adhesive strength with the adhesive resin layer decreases over time. was there.

Also, add ionomer to EVOH and mix uniformly.
A method for improving gas barrier properties (Japanese Patent Publication No. 5065544) and a method for obtaining a layered distribution structure by blending low-density polyethylene with a carbonyl group-containing thermoplastic polymer consisting of EVOH, an ionomer, and polyamide (Japanese Patent Publication No. 5141657) ) etc. are also known. Even with this method of mixing acid-modified polyolefin resin, which is the so-called adhesive resin of EVOH, the compatibility is poor, so even if flexibility can be imparted by mixing, the tensile strength and tear strength are lower than that of EVOH. The problem is that it is actually inferior.

In addition, terpolymer copolymerized with pyrrolidone rings in the molecule absorbs moisture more easily than EVOH, and gas barrier properties decrease due to moisture absorption, and moreover, pinholes, cracks, and uneven thickness easily occur, and these can be prevented. was still insufficient. The method of subjecting EVOH to silane crosslinking has a problem in that it is difficult to control the crosslinking, and often gels and fisheyes occur frequently during melt molding.

In addition, the method of blending EVOH with a lithium chloride compound and an aromatic or aliphatic amide or polyhydric alcohol compound often causes poor dispersion when blending the lithium chloride compound with EVOH, or uses a raw sheet. When performing heating stretching such as container forming,
When trying to obtain a stretched film, there were problems such as voids being generated in the lithium chloride particle portion due to stretching, and conversely, cranks and pinholes were generated, and the method was still unsatisfactory.

On the other hand, attempts have been made to increase the ethylene content of EVOH in order to improve bending fatigue resistance and mechanical strength, but with this method, the gas barrier properties deteriorate due to the increased ethylene content. However, there were restrictions on its use.

Therefore, during thermoforming of containers using EVOH multilayer laminates, pinholes and cranks in the EVOH layer.

No uneven thickness (EVOH with excellent gas barrier properties)
was desired.

[Problem B to be Solved by the Invention] Although EVOH has extremely excellent gas barrier properties as described above, when forming an EVOH multilayer laminate into a container, pinholes form in the EVOH layer.

Cracks, uneven thickness, etc. occurred, resulting in a significant loss of the gas barrier properties inherent to EVOH.

Therefore, it is an object of the present invention to provide a method for thermoforming a multilayer laminate of saponified olefin-vinyl acetate copolymer into a container or the like without impairing the gas barrier properties of saponified olefin-vinyl acetate copolymer resin such as EV○H. It is an object of the present invention to provide a resin composition that prevents pinholes, cracks, and uneven thickness that occur in the resin composition, and has excellent bending fatigue resistance and adhesive strength.

[Means to solve the problem]

The present invention has been made to solve the above problems, and its gist is as follows: (a) Olefin-vinyl acetate copolymer saponified resin 5-
95% by weight and (b) unsaturated silane compound or glycidyl group-containing silane compound modified polyolefin resin 95
It is a resin composition consisting of ~5% by weight.

In the resin composition of the present invention, there are various types of saponified olefin-vinyl acetate copolymer resins used as component (a), such as saponified olefin-vinyl acetate copolymers, propylene-vinyl acetate copolymers, and propylene-vinyl acetate copolymers. There are saponified products of polymers, saponified products of butene and vinyl acetate copolymers, etc., and saponified products of ethylene-vinyl acetate copolymer (ie, EVOH) are particularly preferred because they are easy to polymerize. EVOH has an ethylene content of 15 to 60 mol% and a saponification degree of 90%.
Those having the above compositions are preferably used.

EVOH with an ethylene content of less than 15 mol% has poor melt moldability, and the degree of saponification of the vinyl acetate component is 90%.
Gas barrier properties may also deteriorate when the amount is less than 100%. Among these EVOH, those having an ethylene content of 25 to 50 mol% and a saponification degree of 96% or more are particularly suitable. In addition to ethyl acetate and vinyl acetate (or saponified vinyl alcohol), unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, and maleic acid, or their alkyl esters, propylene, butene, and α-decene , α-olefin such as α-octadecene may be included as a comonomer in small amounts.

On the other hand, there are various unsaturated silane compounds or glycidyl group-containing silane compound-modified polyolefin resins used as component (b) in the resin composition of the present invention.
These can be obtained by known methods. For example, Japanese Patent Publication No. 62-23779, No. 62-15580
No. 62-23979, No. 57-2669
Publication No. 6.

As described in JP 63-39427, JP 61-155412, etc., and even WO 39100501, there is a method of copolymerizing a polyolefin resin and a silane compound at high pressure in the presence of a radical polymerization initiator. JP 63-172712, JP 48-171
Obtained by a method of grafting a silane compound onto a polyolefin resin in the presence of an organic peroxide (radical polymerization initiator) using an extruder etc. as described in Publication No. 1, JP-A No. 47-8389, etc. be able to. There is no particular restriction on the amount of grafting, but for example, the amount of unsaturated silane compound or glycidyl group-containing silane compound in the polyolefin resin is 0.05 to 5% by weight (in terms of silicon), preferably 0.1 to 1% by weight (in terms of silicon). ) are preferably used. The polyolefin resins used here include high density, medium density, and low density polyethylene, ionomer, polypropylene homopolymer, and ethylene-density polyethylene.
These include propylene block or random copolymers, ethylene and α-olefin copolymers having 3 to 12 carbon atoms, and the like.

・This ethylene and α-olefin copolymer having 3 to 12 carbon atoms is, for example, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-4-methylpentene-1 copolymer, ethylene-hexene-1 copolymer, etc. 1 copolymer, modified polypropylene blended with ethylene-propylene rubber, modified polybutene-1, modified poly-4 methylpentene, ethylene-vinyl acetate copolymer, and the like.

In addition, there are various unsaturated silane compounds and glycidyl group-containing silane compounds that modify the above-mentioned polyolefin resin, and examples of unsaturated silane compounds include vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, etc. There are vinyl group-containing silane compounds, and glycidyl group-containing silane compounds include:
Examples include γ-glintoxypropyltrimethoxysilane.

Note that component (b) in the composition of the present invention consists of an unsaturated silane compound or a glycidyl group-containing silane compound-modified polyolefin resin as described above, but in order to improve the melt flowability of the resulting composition, unmodified Polyolefin resins may be mixed. In this case, the ratio of the unmodified polyolefin resin to the silane compound-modified polyolefin resin varies depending on various circumstances and cannot be determined unambiguously, but in general, the ratio of the unmodified polyolefin resin to the silane compound-modified polyolefin resin is Setting the amount of unmodified polyolefin resin to 80% by weight or less is important for the olefin component (a).
This is desirable in terms of maintaining compatibility with the saponified vinyl acetate copolymer resin and gas barrier properties.

The resin composition of the present invention is composed of the above-mentioned (a) component and (b) component, and the mixing ratio of the (a) component is 5 to 9.
5% by weight, preferably 20-90% by weight, (b) component 9
5 to 5% by weight, preferably 80 to 10% by weight. Here, if the proportion of the silane compound-modified polyolefin resin, which is the component (b), is too large, sufficient gas barrier properties will not be exhibited and the product will not be usable.

On the other hand, if it is too small, mechanical strength and adhesive strength will decrease.

The resin composition of the present invention has a melting index (M F RJI
S- according to 675B load 2.16 kg, temperature 2
(measured at 30°C) is not particularly limited and is selected depending on the molding method, but in the case of extrusion molding, a range of 0.1 to 50 is appropriate. The resin composition of the present invention can be molded into film sheet tubes, bottles, etc. by known melt molding methods and compression molding methods.

Films and sheets formed from the resin composition of the present invention can be used as they are, but they can also be laminated with other layers to form a multilayer laminate. for example,
Such lamination methods include the so-called dry lamination molding method, which uses a dry lamination adhesive such as urethane-based or acrylic-based adhesive, and laminates the single-layer product 3 of the resin composition of the present invention and other thermoplastic resin layers, or the sanding method. Co-extrusion lamination, co-extrusion (feed block, multi-manifold method), co-injection molding, co-extrusion pipe molding, or coating is carried out by dissolving the resin composition of the present invention in a solvent. There are various methods for coating, such as solution coating moldability.

The multilayer laminate thus obtained may be further reheated and stretched using a vacuum forming machine, compression molding machine, stretch blow molding machine, etc., or the multilayer laminate described above may be uniaxially or biaxially A heating stretching operation can be performed using a stretching machine.

Other thermoplastic resins to be laminated to the resin composition of the present invention include polyethylene resins, polypropylene resins, copolymers of ethylene and α-olefins having 3 to 12 carbon atoms,
Polyolefin resins such as ionomer resins, as well as polystyrene resins, polyethylene terephthalate resins, and polyvinyl chloride resins.

There are thermoplastic resins such as polycarbofoot resin and polyamide resin. The above-mentioned copolymers of ethylene and α-olefin having 3 to 12 carbon atoms include ethylene-butene-1 copolymer, ethylene-4-methylpentene-1 copolymer, ethylene-hexene-1 copolymer, and ethylene-hexene-1 copolymer. - Modified polypropylene blended with propylene rubber etc., modified polybutene modified poly-4 methylpentene, or unsaturated carboxylic acid or its anhydride grafted to the above-mentioned polyolefin polymer under organic peroxide, or other Also included are those copolymerized with polymers (for example, methyl methacrylate, ethyl acrylate, etc.).

The layer structure of the multilayer laminate is A/B/C, C/B/A/B/, where the resin composition of the present invention is layer A, the adhesive resin layer is layer B, and other thermoplastic resins are layer 0. C, C/B/metal'4
/ A / B / C etc. are mentioned as typical examples. Here, even if the thermoplastic resins of both outer layers are different,
Moreover, the same resin may be used. The adhesive resin layer may be a so-called dry lamination adhesive such as the urethane-based acrylic adhesive or polyester adhesive described above, or a known adhesive resin in the coextrusion molding method. For example, there are resins in which unsaturated carboxylic acid, acid anhydride, or ester monomers are grafted or copolymerized to polyolefin resins.

These grafting methods can be obtained by melt-grafting a polyolefin resin with an organic peroxide and modifying the above-mentioned components, or by dissolving a polyolefin resin in hot xylene and grafting the above-mentioned components with an organic peroxide. Examples of unsaturated carboxylic acids, acid anhydrides, and ester monomers include methacrylic acid, acrylic acid, ethacrylic acid, glycidyl methacrylate, and 2-hydroxyethyl acrylate.
2-hydroxyethyl methacrylate diethyl maleate, monoethyl maleate, di-n-butyl maleate,
Maleic acid, maleic anhydride, fumaric acid 7 fumaric anhydride, itaconic acid, itaconic anhydride, 5-norbornene-2°3-anhydride, citraconic acid 3 citraconic anhydride.

Crotonic acid 1 Crotonic acid anhydride, acrylonitrile,
methacriconitrile. Sodium acrylate.

These include calcium acrylate and magnesium acrylate. For these graft polymers, U.S. Patent No. 4026
It is described in detail in JP-A No. 967, JP-A No. 3953655, JP-A-5198784, JP-A-44-15423, JP-A-49-4822, and the like.

The blending method for obtaining the resin composition of the present invention is not particularly limited, but it is preferable to pelletize using a Ribo-Flender, high-speed mixer, kneader, Berekiza mixing roll, etc., and then dry. on the other hand,
Each of the components (a) and (b) may be directly supplied to a molding machine for molding.

The resin composition of the present invention basically consists of component (a) and component (b).
However, if desired, other additives 1 for use with the thermoplastic resin can be blended. Examples of such additives include 25-dibutylhydroquinone, 2,6-butyl-p-cresol; 4,4'-thiobis-(6-butylphenol) as an antioxidant; 2.2methylene-bis(4-methyl-6-t
-butylphenol); octadecyl-3-(3", 5
"Di-L-butyl-1'-hydroxyphenyl)propinate, 4,4'-thiobis-(6-butylphenol), ethyl-2-cyano-3,3 as ultraviolet absorber
-diphenylacrylate; 2(2゛-hydroxy-5
-methylphenyl)benzotriazole; 2-hydroxy-4-octoxybenzophenone, dimethyl phthalate, glycerin, dipropylene glycol as a plasticizer,
Triethylene glycol, diethylene glycol diethyl phthalate, wax, liquid paraffin, phosphate ester, monostearate, sorbitan monopalmitate as an antistatic agent, sulfated oleic acid, polyethylene oxide, carbowax, ethylene bisstearamide as a lubricant. , butyl stearate, etc., and carbon black as a coloring agent.

Examples include phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, red iron oxide, etc., and fillers such as glass fiber, ashest, mica, ballastonite, calcium silicate, aluminum silicate, calcium carbonate, etc. Moreover, many other polymeric compounds can also be blended to the extent that the effects of the present invention are not inhibited.

[Function] The resin composition of the present invention eliminates the drawbacks of the saponified olefin-vinyl acetate copolymer resin without impairing its inherent gas barrier properties.

[Examples] Next, the present invention will be explained in more detail based on Examples and Comparative Examples.

Examples 1 to 6 and Comparative Examples 1 to 5 (1) Preparation of silane compound-modified polyolefin resin A Kobe Steel KTX-37 co-directional twin-screw vented extruder (dice temperature 200'C) was used. Rex low density polyethylene L170 (MI=7. Density=0.
917), dicumyl peroxide (Kayacumil D manufactured by Kayaku Akzo) was added as an organic peroxide, and the amount of vinyltrimethoxysilane or T-glycidoxypropyltrimethoxysilane manufactured by Toshi Silicone was added as a silane compound. The silane compound-modified resins shown in Table 1 were obtained by adding different amounts and heating and kneading. The amount of silane grafted was determined using a fluorescent X-ray measuring device manufactured by Rigaku Denki Co., Ltd. after extracting unreacted silane compounds with isopropyl alcohol under reflux for 5 hours.

(2) Silane compound modified polyolefin resin and EVOH
The silane compound-modified resin obtained in (1) above and EVOH were mixed at a temperature of 210"C using a Kobe Steel KTX-37 type extruder with a twin-screw vent in the opening direction, and the resin shown in Table 2 was mixed with EVOH. A composition was obtained.

The resin composition thus obtained was molded into a 1-thickness molding machine at a temperature of 220"C using a T-die molding machine with an inner diameter of 40 mm manufactured by Yoshii Iron Works.
00 μm film was created, and about this film,
Oxygen permeation was measured using Modern Control's 0XTRAN-10150A, film impact strength was measured using a Toyo Seiki pendulum type film impact tester, and tensile elongation was measured according to JIS K-6760. Elmendorff tear strength was measured in each case according to Z-1702. These results are also shown in Table 2.

(Leaving space below) (3) (Evaluation of heat seal strength) Using a heat seal tester TP701 manufactured by Tester Sangyo, wipe each film obtained in (2) above and apply a pressure of 2
) g/cal, heat sealing temperature was varied under the conditions of heat sealing time of 1 second to obtain samples for heat seal evaluation having a width of 15 mm.

Next, this heat seal strength was determined by T-peeling at a peeling speed of 300 m/min using Tensilon manufactured by Toyo Seiki ■. These measurement results are summarized in Table 3 with the temperature at which the heat sealing strength is 500g/15m width or more.
Shown below.

Example 7 Two films obtained under the conditions of Example 1 were stacked and adhered under the heat sealing conditions described above. Next, the peel strength of the films heat-sealed at different temperatures was determined, and the temperature at which the heat-seal strength was 500 g/15W width or more was determined.

The results are shown in Table-3. As can be seen from Table 3, a film with high adhesive strength was obtained even when heat-sealed at a low temperature.

Examples 8 to 12 The heat seal strength of the films obtained under the conditions of Examples 2 to 60 was evaluated in the same manner as in Example 7, respectively. The results are shown in Table-3.

Comparative Examples 6 to 10 The heat seal strength of the films obtained under the conditions of Comparative Examples 1 to 5 was evaluated in the same manner as in Example 7, respectively. The results are shown in Table-3.

(Blank below C) [Effects of the Invention] The resin composition of the present invention is more flexible than conventional saponified olefin-vinyl acetate copolymer resins.

It has excellent impact strength and heat sealability, and is effectively used as food packaging materials, pharmaceutical packaging materials, cosmetic packaging materials 1, and containers that require gas barrier properties.

Patent applicant: Showa Denko Co., Ltd.

Claims (4)

[Claims] (1) A resin composition comprising (a) 5-95% by weight of a saponified olefin-vinyl acetate copolymer resin and (b) 95-5% by weight of an unsaturated silane compound or glycidyl group-containing silane compound-modified polyolefin resin. (2) (a) The saponified olefin-vinyl acetate copolymer resin has an ethylene content of 15 to 60 mol% and a saponification degree of 90%.
The resin composition according to claim 1, which is the saponified ethylene-vinyl acetate copolymer resin described above. (3) The resin composition according to claim 1, wherein the unsaturated silane compound or glycidyl group-containing silane compound-modified polyolefin resin (b) contains an unmodified polyolefin resin. (4) (b) The unsaturated silane compound or glycidyl group-containing silane compound-modified polyolefin resin is a polyolefin resin grafted with 0.05 to 5% by weight (in terms of silicon atoms) of a silane compound. resin composition.