JPH0676531B2 - Resin composition and laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Fields of Industrial Application The present invention has excellent transparency and gas barrier properties, and has flexibility such as drop impact resistance, bending resistance, air back protection, skin pack packaging suitability and shrink film suitability. The present invention relates to a resin composition having excellent properties and a laminate containing at least one layer of this composition.

B) Prior Art Saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) is a thermoplastic resin having extremely excellent transparency, gas barrier property, oil resistance, and aroma retention compared to other resins. It is used in the gas barrier film of the above, as a gas barrier layer of a gas barrier container. However, a multilayer film and a container having EVOH as a gas barrier layer often have a problem due to the high rigidity of EVOH. For example, a multi-layer film filled with contents or a container may be easily broken or broken when dropped, a pin hole may be generated in the multi-layer film filled with contents due to bending or vibration during transportation, and an air bag of the multi-layer tube may occur. , Wrinkles during skin pack packaging, stretchability as a film for shrink wrapping,
Examples include the problem of insufficient contractility. Therefore, a method of blending EVOH with another thermoplastic resin to improve these drawbacks has been considered. For example, blending EVOH with ethylene-carboxylic acid vinyl ester copolymer or ethylene-acrylic acid ester copolymer improves flex resistance (JP-A-61-220839), and EVOH has α, β-unsaturation. Carboxylic acid or carboxylic anhydride-modified ethylene-
It is known that blending a carboxylic acid vinyl ester copolymer and an ethylene-acrylic acid ester copolymer improves the impact resistance of EVOH (JP-A-61-83035).
However, with these methods, EVOH's bending resistance and impact resistance are
Although it is improved, the transparency, which is a feature of EVOH, is impaired, and it has not been put to practical use in applications that require transparency.

As a composition having good transparency, a composition composed of EVOH and polyamide can be mentioned, but the deterioration of the gas barrier property due to blending is large, the thermal stability at the time of molding is poor, and the problem of gel formation in a short time is encountered. However, this composition has not been put into practical use.

Further, by blending EVOH with a partially saponified ethylene-vinyl acetate copolymer (hereinafter referred to as partially saponified EVA), and by using the blend, interlayer adhesion between EVOH and polyolefin is imparted. Japanese Patent Publication No. 51-4851 and Japanese Patent Application Laid-Open No. 60-161447, and Japanese Patent Application Laid-Open No. 60-161447 show that low-temperature sealing property is imparted and molding processability is improved.
52-73984, 52-77160, 52-101162, 54-53089, 5
As described in 4-156082, when a molded article such as a film is manufactured according to the method described in these prior arts, the flexibility is insufficient, the thermal stability is poor, and the net tin is severe and the moldability is poor. There are problems such as being present, and there is a pattern such as stripes and satin on the film surface, and it is the current situation that it has not been put to practical use. As disclosed in the present invention, a melt index (hereinafter referred to as MI) (a value measured under the conditions of 190 ° C. and a load of 2160 g), the content of the vinyl alcohol component, and EVOH satisfying a specific relationship with EVOH. It is not known at all that a resin composition having excellent transparency can be obtained only by blending partially saponified EVA.

For this reason, it has not been possible to obtain a transparent resin composition or a laminate having improved flexibility such as EVOH drop impact resistance, flex resistance, air backproofing property, skin pack suitability, shrink film suitability, etc. .

C. Problems to be Solved by the Invention As described in the prior art, EVOH transparency, drop impact resistance, flex resistance, air back protection, skin pack suitability, shrink film characteristics, etc., without deteriorating the gas barrier property, etc. It has been desired to put into practical use a resin composition or a laminate having the above flexibility.

D. Means for Solving the Problems The inventors of the present invention have made earnest studies to develop an excellent resin composition having transparency, flexibility, and gas barrier properties.
When partially saponified EVA was blended with EVOH and formed into a film, there were many lines and satin, and the transparency was poor. Furthermore, the net quinc was large and the moldability was poor. However, a detailed examination of a wide range of blends of EVOH and partially saponified EVA revealed that EVOH with a specific MI and vinyl alcohol component and a partial partially saponified EVA with a specific MI and vinyl alcohol component were blended at a specific ratio. It was found that a film excellent in transparency, film film surface and moldability was obtained only in such a case, and the present invention was completed.

Hereinafter, the present invention will be described in more detail. The EVOH (A) used in the present invention has an ethylene content of 25 to 50 mol% and a saponification degree of the vinyl acetate component of 90% or more, preferably 95% or more. If the ethylene content is less than 25 mol%, the molding temperature will be close to the decomposition temperature and molding will be difficult. Ethylene content of 50
If it exceeds mol%, the gas rearing property becomes unsatisfactory, which is not preferable. Further, EVOH having a vinyl acetate component with a saponification degree of less than 90% is not preferable because it has a poor gas barrier property.
The MI of EVOH used in the present invention is 15 g / 10 minutes or less, preferably 7 g / 10 minutes or less. EVOH with MI over 15g / 10 minutes
When partially blended with partially saponified EVA, the net quinque during molding becomes large and molding failure occurs. The MI of EVOH is preferably 0.1 g / 10 minutes or more, more preferably 0.5 g / 10 minutes or more.

The EVOH referred to in the present invention may be modified with a copolymerizing monomer in the range of 5 mol% or less, and examples of the modifying monomer include propylene, 1-butene, 1-hexene,
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) methacrylamides or quaternary compounds thereof, N-vinylimidazole or quaternary compounds thereof, N-vinylpyrrolidone, N, N-butoxymethylacrylamide, vinyltrimethoxysilane, vinylmethyldimethoxy Examples thereof include silane and vinyldimethylmethoxysilane.

The partially saponified EVA (B) used in the present invention has an ethylene content of 82 to 94 mol% and a vinyl acetate component saponification degree of 20 to 98.
%, Preferably the ethylene content is 84 to 92 mol%, the saponification degree is 30%, and more preferably 40% or more. The saponification degree is preferably 97% or less. 82 mol% ethylene content
If it is less than 100%, thermal stability becomes poor in blending with EVOH. When the ethylene content of partially saponified EVA exceeds 94 mol%, the blending effect of drop impact resistance, bending resistance, air backproofing property, suitability for skin pack, suitability for shrink film, etc. does not appear. The degree of saponification is 20%
If it is less than 1, the transparency will be poor. The MI of partially saponified EVA can be used in any range as long as it satisfies the formula (1), but a partially saponified EVA having MI of 100 g / 10 min or less is preferable because molding is easy. It is more preferably 30 g / 10 minutes or less, and most preferably 20 g / 10 minutes or less. MI of partially saponified EVA (B)
Is preferably 0.1 g / 10 minutes or less, more preferably 0.5 g / 10 minutes.

The blending ratio of EVOH (A) and partially saponified EVA (B) is 60 to 95% by weight for the former and 5 to 40% by weight for the latter, preferably 70 to 90% by weight for the former and 10 to 10% for the latter. 30% by weight.

Further, in the present invention, M of EVOH (A) and partially saponified EVA (B)
A specific EVOH or partially saponified EVA having a P value of 40 or less, preferably 15 or less, which is obtained from the following formula (1) from I, blending ratio and vinyl alcohol content is used.
The P value is preferably 0.6 or more, more preferably 0.8 or more.

M = M _A / M _B (when M _A ≧ M _B ) M = M _B / M _A (when M _A <M _B ) M _A : Resin A MI M _B : Resin B MI VA _A : Resin Content of vinyl alcohol component of A (mol%) VA _B : Content of vinyl alcohol component of resin B (mol%) B: Content of resin B (wt%) P value calculated by the formula (1) is transparent It is very important for the transparency, and the smaller the P value, the better the transparency, and when the P value exceeds 40, the transparency becomes poor. This is clear when the composition is formed into a single layer, and a film made of a composition having a P value of 40 or more has a large amount of streaks and satin, and its transparency is significantly lowered. We also found that the occurrence of streaks and satin is determined by the magnitude relationship between M _A and M _B. That is, when M _A > M _B , satin occurs, and when M _A > M _B , streaks tend to occur. Furthermore, the transparency of the composition is EVOH and partially saponified EV.
EVOH and partially saponified EVA depending on vinyl alcohol content of A
The smaller the difference in vinyl alcohol content, the better the transparency. Furthermore, the transparency of the composition is EVOH and partially saponified EV.
Depending on the blending ratio of A, the smaller the blending ratio of partially saponified EVA, the better the transparency. EVOH and partially saponified EVA
The MI value of M has a great influence on the film surface, and the P value obtained from the formula (1) by the MI ratio, the difference in vinyl alcohol content and the blending ratio has a great influence on the transparency. It was unexpected because it was unknown before.

The blending method of EVOH and partially saponified EVA in the present invention includes a method using a Banbury mixer, a single-screw or twin-screw extruder, a Brabender plastograph, etc., but each component is directly supplied to various molding machines for molding. Molding may be performed while kneading with a machine. Further, it is preferable to add a plasticizer to the extent that it does not bleed out when kneading these, because the softening effect is increased by the synergistic action of the partially saponified EVA and the plasticizer. Examples of plasticizers include glycerin, diglycerin, 1,2 propanediol, 1,3 propanediol, 1,2 butanediol, 1,3 butanediol, 2,
Alcohol plasticizers such as 3 butanediol, 1,4 butanediol, 1,2,6 hexanetriol, diethanolamine and diethylene glycol are preferred, and dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphoric acid Esters and amide compounds such as laurinamide, o, p-toluenesulfonamide and N-ethyl-o, p-toluenesulfonamide can also be used.

Further, other additives (various resins, heat stabilizers, antioxidants, coloring agents, etc.) can be freely used within the range that the effects of the present invention are not impaired. As a heat stabilizer,
Hydrotalcite-based compounds, heat stabilizers for polyvinyl chloride such as metal soaps, lead salt-based compounds, organic silver-based compounds, hindered phenol-based compounds, hindered amine-based compounds, sulfide-based compounds, and phosphite-based compounds are used. Hydrotalcite-based compounds are particularly effective.

The resin composition of the present invention is preferably used in a laminate. At this time, the resin composition of the present invention can be used in any of the intermediate layer, the outermost layer and the innermost layer. The resin to be laminated with the resin composition of the present invention is not particularly limited, but generally a resin having good transparency is preferable, for example, low density polyethylene, linear low density polyethylene, polypropylene,
Ethylene-propylene copolymer, polyolefin such as polybutene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, copolymer mainly composed of olefin such as ionomer, polyethylene terephthalate, polycarbonate, polyamide, polystyrene ,
Examples thereof include polyvinyl chloride. this house,
Linear low density polyethylene, ethylene-vinyl acetate copolymer, and polyamide are preferable.

When the interlayer adhesion between these resins and the resin composition of the present invention is not sufficient, it is preferable to provide an adhesive resin layer. The adhesive resin is not particularly limited as long as it does not cause delamination at a practical stage, but is preferably a polyolefin polymer such as polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content 45
(Wt% or less), ethylene-acrylic acid ester or methacrylic acid ester copolymer (acrylic acid ester, methacrylic acid ester content of 45 wt% or less) chemically with an ethylenically unsaturated carboxylic acid or its anhydride (for example, addition reaction). , A modified polyolefin-based copolymer obtained by bonding (by a graft reaction) is used. It is also possible to blend these adhesive resins in either of the two layers or both layers instead of providing them between the layers.

The resin composition of the present invention can be formed into a film, a sheet, a tube, a pipe, a bottle or the like as a laminate, and the thickness constitution of each layer is not particularly limited, but the resin composition of the present invention is transparent. The physical layer is preferably used in a thickness of 300 μm or less, more preferably 200 μm or less.

The method for laminating the resin composition of the present invention is not particularly limited, and examples thereof include a coextrusion method, an extrusion lamination method, a dry lamination method, and the like. It is suitable because it can be exhibited.

The laminate thus obtained is used as a film with excellent drop impact resistance, a tube with excellent air backlash prevention, a bag with imprinting with excellent bending resistance, suitability for skin pack, and excellent shrink film properties. can do.

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

E. Examples Example 1 The ethylene content was 44 mol% and the saponification degree of the vinyl acetate component was
Melt index (MI) measured according to ASTM D1238 65T under conditions of 99%, 190 ° C and 2160g load is 5.5g / 10min E
70 parts by weight of VOH and 88 mol% of ethylene content, saponification degree of vinyl acetate component of 80%, MI of 4.8 g / 10 minutes partially saponified EVA30
The blended pellet was made into a weight part by a 30φ different-direction twin-screw extruder (P value = 10.4). Using this pellet, a film having a thickness of 25 μm was formed into a film by a 40φ single-screw extruder. Film surface of the obtained film, moldability, haze,
The loop stiffness, flex resistance, Young's modulus, and oxygen gas transmission rate (OTR) were evaluated.

The evaluation of the film surface was visually conducted on lines, satin and spots in Table 1
The evaluation was carried out in five stages of A to E shown in. Further, the moldability was evaluated in five stages of A to E shown in Table 1 for the net quin.

The haze was measured using a Poitsk integrating sphere type light transmittance meter manufactured by Nippon Seimitsu Optical Co., Ltd.

Loop stayness is a loop stay funnel tester manufactured by Toyo Seiki Co., Ltd. The repulsive force when compressing a film with a width of 15 mm into a loop with a length of 60 mm and compressing it until the loop diameter becomes 20 mm at 20 ° C and 65% RH. It was measured under the conditions. The loop stability is important as a property of the air backproof property, and it is considered that a composition having a small loop stability has a good air backproof property.

The flex resistance was evaluated using a gel boflex tester manufactured by Rigaku Kogyo Co., Ltd., and a 12-inch x 8-inch film was used.
3.5 inch cylindrical shape, gripping both ends, initial gripping distance 7 inches, gripping distance at maximum bending 1 inch, add a twist of 440 ° at the first 3.5 inches of stroke, then 2.5 inches horizontal diameter The number of pinholes of the film was obtained after repeating the reciprocating motion which is a dynamic motion at a speed of 40 times / min 300 times under the conditions of 20 ° C. and 65% RH.

Young's modulus was measured according to ASTM D-882-67 under the conditions of 20 ° C and 65% HR. Young's modulus is important for skin pack suitability and shrink film suitability. That is, it can be said that a composition having a low Young's modulus that can be stretched with a smaller force is suitable for the skin pack packaging including the stretching step and the shrink film packaging.

Oxygen gas transmission rate (OTR) is measured by Modern Control O
It was measured using X-TRAN 10-50A under the conditions of 20 ° C. and 65% RH.

The results of each evaluation are shown in Table 2. This composition has good film surface, moldability and transparency, and has excellent loop stiffness, flex resistance, Young's modulus and other flexibility and gas barrier properties. There is.

Examples 2 to 11 The same evaluations as in Example 1 were performed using EVOH and partially saponified EVA shown in Table 2. The evaluation results are shown in Table 2. These compositions have good film surface, moldability and transparency, and are excellent in loop stiffness, flex resistance, flexibility represented by Young's modulus, and gas barrier properties.

Comparative Example 1 The ethylene content was 44 mol% and the saponification degree of the vinyl acetate component was
EVOH with 99% and MI of 5.5 g / 10 min was formed into a film with a film having a thickness of 25 μ using a 40 φ single-screw extruder. The same evaluation as in Example 1 was performed on this film. The results are shown in Table 2, and this film has large loop stability, flex resistance (number of pinholes generated), and Young's modulus, and lacks flexibility.

Comparative Examples 2 to 11 The same evaluations as in Example 1 were performed using EVOH and partially saponified EVA shown in Table 2. The evaluation results are shown in Table 2.

In Comparative Example 2, the values of loop stiffness and Young's modulus are large, the number of pinholes generated is large, and flexibility is lacking.

Comparative Example 3 has a large OTR value and lacks gas barrier properties.

In Comparative Example 4, the netquine was large and the moldability was poor.

In Comparative Examples 5 and 6, the OTR value lacks gas barrier properties.

In Comparative Example 7, the number of pinholes was large, because the film had a lot of spots and was not at a practically usable level.

In Comparative Example 8, the values of loop stiffness and Young's modulus are large, the number of pinholes generated is large, and flexibility is lacking.

In Comparative Example 9, since the partially saponified EVA has a low saponification degree, haze is large and transparency is poor.

In Comparative Examples 10 and 11, the P value is 40 or more, and the generation of streaks and satin is prone to occur, and thus the haze is large and the transparency is poor.

Example 12 The ethylene content was 44 mol% and the saponification degree of the vinyl acetate component was
99%, MI 5.5g / 10min EVOH 70 parts by weight and ethylene content 8
8 mol%, saponification degree of vinyl acetate component is 80%, MI is 4.8g / 10
30 parts by weight of partially saponified EVA and 3 parts by weight of glycerin were pelletized in the same manner as in Example 1 to form a film.
A film of μ was obtained. The film forming property was good. The haze of this film is 2%, the transparency is good, the loop stability is 100 mg, the Young's modulus is 40 kg / mm ² , and even after 300 gel gel flex tests, pinholes do not occur and good flexibility is obtained. Showed sex. The OTR was 2.2cc / m ² day atm and the bus barrier property was good.

Example 13 The ethylene content was 44 mol% and the saponification degree of the vinyl acetate component was
99%, MI 5.5g / 10min EVOH 70 parts by weight and ethylene content 8
9 mol%, saponification degree of vinyl acetate component is 95%, MI is 4.8 g /
A 15μ thick intermediate layer (P value = 10.4) consisting of 30 parts by weight of partially saponified EVA for 10 minutes, and 4-layers each having a thickness of 30μ on both sides of the intermediate layer.
Methyl-1-pentene was used as a copolymerization component, the copolymerization component was contained in an amount of 3.2 mol%, and MI had a surface layer consisting of linear low-density polyethylene of 2.1 g / 10 min. Three extruders each having a laminated film of 85μ in total thickness, which are arranged through an adhesive resin layer made of a maleic anhydride-modified ethylene-vinyl acetate copolymer having a vinyl acetate content of 20% by weight and a maleic anhydride content of 0.5% by weight. It was obtained by a coextrusion method using a multilayer die head for three kinds of five layers. The composition used for the intermediate layer was a pellet previously blended by an extruder. A gel voflex test is performed on the obtained laminated film until the occurrence of pinholes in the laminated film is recognized, and the oxygen gas permeation amount at each stage until the occurrence of pinholes is 20 ° C. and 65% RH. It was measured under the conditions. The sample after bending fatigue at each stage was formed into a 12 inch × 8 inch flat surface, and the measurement was performed at the center thereof. The measurement results are shown in Table 3. In the bending fatigue test process until the pinhole was generated, there was almost no change in the oxygen permeation amount. In addition, no pinhole was observed until after 7,000 cycles of the bending fatigue test, and after 7100 cycles, it was confirmed that one pinhole had already occurred at the time of inspecting the presence or absence of a pinhole. Moreover, no delamination between the layers was observed. The haze of the film was 4%, the transparency was good, and no lines or satin were observed.

Comparative Example 12 The same evaluation as in Example 13 except that the resin blended with EVOH of the intermediate layer in Example 13 had an ethylene content of 89 mol% and MI was changed to 6 g / 10 min ethylene-vinyl acetate copolymer. Done. The measurement results are shown in Table 3. The result of the bending fatigue test was as good as that of Example 13, but the haze of the film was 25% and the transparency was lacking.

Example 14 The ethylene content was 44 mol%, and the saponification degree of the vinyl acetate component was
99%, MI 5.5g / 10min EVOH 70 parts by weight and ethylene content 8
9 mol%, saponification degree of vinyl acetate component 95%, MI 4.8g / 10
Of 50 parts by weight of partially saponified EVA with an average thickness of 50μ (P value = 10.4) and vinyl acetate content of 5 on both sides of the intermediate layer.
70% by weight of ethylene-vinyl acetate copolymer, 30% by weight of vinyl acetate content, 30% by weight of maleic anhydride-modified ethylene-vinyl acetate copolymer having a vinyl acetate content of 0.5% by weight, each having an average thickness of 300 μm A container having inner and outer layers (10 l in internal volume) was obtained by co-extrusion and direct blow molding using two extruders and a two-layer, three-layer multi-layer die head. The composition used for the intermediate layer was pellets blended by a random extruder. Fill this container with 10 l of water and
Although it was dropped three times from the height of m, it did not break and showed good drop impact resistance.

Comparative Example 13 The same molding as in Example 14 was performed except that EVOH was used alone in the intermediate layer in Example 14, and the same drop test was performed. The container broke in the first drop.

Example 15 The ethylene content was 44 mol%, and the saponification degree of the vinyl acetate component was
99%, MI 5.5g / 10min EVOH 70 parts by weight and ethylene content 8
9 mol%, saponification degree of vinyl acetate component is 95%, MI is 4.8 g /
An intermediate layer (P value = 10.4) having an average thickness of 20 μm consisting of 30 parts by weight of partially saponified EVA for 10 minutes, and an average thickness of ethylene-vinyl acetate copolymer having a vinyl acetate content of 8% by weight on both sides of the intermediate layer. Each has a surface layer of 150μ, between each layer vinyl acetate content of 20 wt%, maleic anhydride content of 0.5 wt% maleic anhydride-modified ethylene-adhesive resin layer having an average thickness of 15μ consisting of vinyl acetate copolymer Average thickness of all layers arranged through
A tube of 350 μm (content of 250 ml) was obtained by a direct blow method by using three extruders and a three-layer five-layer die head. As the composition used for the intermediate layer, pellets preliminarily blended by an extruder were used. When the center of the obtained tube was cut at a width of 15 mm and compressed by a loop stay funnel tester by 10 mm, the repulsive force was 650 mg.

Example 14 In Example 15, the intermediate layer had an ethylene content of 44 mol%, a vinyl acetate component saponification degree of 99%, and an MI of 5.5 g / 10 min EVOH.
When a loop stability test was conducted in the same manner as in Example 14 except that was used alone, the repulsive force was 1500 mg.

F. Effect of the Invention The resin composition of the present invention does not deteriorate transparency and gas barrier properties as compared with EVOH alone, and the flexibility is dramatically improved, and a laminate containing at least one layer of the composition has a drop impact resistance. It can be used as a laminate having excellent properties, flex resistance, air pack prevention property, skin pack suitability and shrink film suitability.

Claims (2)

[Claims] 1. An ethylene content of 25 to 50 mol%, a saponification degree of a vinyl acetate component of 90% or more, a melt index (190
Saponified ethylene-vinyl acetate copolymer (A) 60 to 95 having a value of 15 g / 10 minutes or less)
% Of ethylene, 82 to 94 mol% of ethylene content, 40 to 5% by weight of partially saponified ethylene-vinyl acetate copolymer (B) having a degree of saponification of vinyl acetate component of 20 to 98%, and a resin (A ) And the melt index of the resin (B), the content of the vinyl alcohol component, and the content of the resin B, the P value obtained by the following formula (1) is 40 or less. M = M _A / M _B (when M _A ≧ M _B ) M = M _B / M _A (when M _A <M _B ) M _A : Melt index of resin A (however, M _A ≦ 15 g / 10
Min) M _B: Resin B has a melt indenyl try VA _A: content of vinyl alcohol component in resin A (mol%) VA _B: content of vinyl alcohol component in resin B (mol%) B: The content of the resin B (weight%) 2. The resin composition according to claim 1, at least 1.
A laminate including layers.