JPH0713172B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a resin composition which provides a packaging material which is flexible, has excellent bending fatigue resistance, and has excellent gas permeation resistance.

B. Conventional Technology Ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) is widely known as a melt-moldable thermoplastic resin with excellent gas permeation resistance, oil resistance, solvent resistance, aroma retention, etc. ,
Used for films, sheets, containers, etc. in various packaging fields.

However, EVOH has the drawbacks of being hard, brittle, and lacking in flexibility, so that it is rarely used alone and is widely used mainly as a laminate with other thermoplastic resins. Even so, the laminated packaging material having the EVOH layer cannot be kept excellent in gas permeation resistance due to cracks and pinholes in the EVOH layer due to, for example, strong vibration and bending fatigue due to transportation.

C. Problems to be Solved by the Invention The present invention is intended to provide a resin composition which can be a packaging material that is flexible, has excellent flex fatigue resistance, and has excellent gas permeation resistance.

D. Means for Solving the Problems As a result of intensive investigations by the present inventors, an EVOH-based copolymer containing a polyether component as a component constituting a polymer (hereinafter, an EVOH-based copolymer containing only a polyether component is described. It is found that the above object can be achieved by blending EVOH not containing a polyether component as a component constituting a polymer (hereinafter simply referred to as EVOH not containing a polyether component) with The present invention has been completed.

E. Effect of the Invention The packaging material comprising the resin composition according to the present invention is excellent in gas permeation resistance, oil resistance, solvent resistance, and aroma retention, and is more flexible than conventional laminated packaging materials using EVOH. In addition to being extremely useful in various packaging fields, especially as a flexible laminated packaging material, it can be widely used as a single item.

F. More Detailed Description of the Invention A typical EVOH used in the present invention has an ethylene content of 20 to 60 mol%, preferably 25 to 55 mol%, and a degree of saponification of vinyl acetate component.
It is 95% or more, preferably 98% or more. 20 ethylene content
When it is less than mol%, not only the moldability is deteriorated, but also the gas permeation resistance under high humidity is deteriorated. When the ethylene content is more than 60 mol%, the gas permeation resistance is greatly deteriorated. If the saponification degree is less than 95%, the flexibility is increased, but the gas permeation resistance is deteriorated, which is not preferable. In addition, other copolymerizable unsaturated monomers may be contained within a range that does not impair the characteristics of EVOH.

The ethylene content of EVOH containing a polyether component is 20
-60 mol% means the content of ethylene in EVOH excluding the polyether component. The ethylene content and saponification degree of EVOH containing a polyether component and EVOH containing no polyether component blended therewith can be arbitrarily selected within the above range, but the ethylene content and the saponification degree are also equal to or close to each other, for example. The difference in ethylene content is 20 mol% or less, preferably 10 mol% or less, and the difference in saponification degree is 3
% Or less, preferably 2% or less.

Examples of the polyether component include those mainly composed of oxyalkylene units such as oxyethylene units, oxypropylene units, oxyethylene-oxypropylene units, and oxytetramethylene units. Among them, oxypropylene units and oxyethylene units are particularly preferable. Oxypropylene units are preferred. Furthermore, in the polyether component, a polymethylene unit, an amide group, a urethane group,
It may contain an ester group, a phenyl group or the like.

The weight ratio of the EVOH component and the polyether component of the EVOH copolymer containing the polyether component in the present invention is 10% by weight, preferably 20% by weight or more, from the viewpoint of imparting flexibility and impact resistance. On the other hand, the content of the polyether component is 90% by weight or less, preferably 80% by weight or less, from the viewpoint of dispersibility at the time of blending with EVOH containing no polyether component or interaction.

The method for producing the EVOH-based copolymer containing the polyether component in the present invention will be described in detail below.

In the first type, polyether and EVOH form a block copolymer, and when polyether is represented by P and EVOH is represented by E, it is represented by PE or EPPE.
Such a block copolymer can be produced, for example, by the following method. A method in which vinyl acetate / ethylene is copolymerized in the presence of a polyether having a mercapto group at one end (one or both ends) and then saponified by a conventional method, or ethylene having a mercapto group at the end (one end) is used. Examples thereof include a method of polymerizing a polyether having a polymerizable double bond at its terminal (one terminal or both terminals) in the presence of a vinyl alcohol copolymer.

Here, the polyether having a polymerizable double bond at the terminal is represented by the general formula [However, R is hydrogen or a methyl group, R ¹ and R ² are hydrogen or an alkyl group having 1 to 10 carbon atoms, R ³ is hydrogen, and 1 to 10 carbon atoms.
Alkyl group, alkyl ester (having 1 to 10 carbon atoms in the alkyl) group, alkylamide (having 1 to 10 carbon atoms in the alkyl)
10) represents a group or the like, and n represents an integer of 1 to 100. ] (Meth) allyl ether type compounds (eg, polyoxyethylene (meth) allyl ether, polyoxypropylene (meth) allyl ether, etc.) or a general formula (However, R, R ¹ , R ² and R ³ are the same as above), or a (meth) allyl ether type compound or a general formula [Wherein R ⁴ is hydrogen, an alkyl group having 1 to 10 carbon atoms or X is an alkylene group having 1 to 10 carbon atoms, a substituted alkylene group,
A phenylene group, a substituted phenylene group and m each represent 0 or an integer of 1 or more. R ¹ , R ² and R ³ are the same as above. ] A (meth) acrylamide type compound having a double bond at one end (eg, polyoxyethylene (meth) acrylic acid amide, polyoxypropylene (meth) acrylic acid amide, etc.) or a general formula [However, R, R ¹ , R ² , R ³ , X, m and n are the same as above]
(Meth) acrylic acid ester type (for example:
Polyoxyethylene (meth) acrylate, polyoxypropylene (meth) acrylate, etc., or general formula [However, R ¹ , R ² , R ³ , X, m, and n are the same as above], such as vinyl ether type (eg, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, etc.).

In the second type, polyether is added as a graft polymer of EVOH in a graft form. Such a graft copolymer can be obtained, for example, by copolymerizing ethylene and vinyl acetate with a polyether having a polymerizable double bond at the terminal and saponifying by a conventional method.

In the third type, EVOH is attached in the form of a graft as a branched polymer of polyether. Such a graft copolymer can be obtained, for example, by copolymerizing ethylene and vinyl acetate in the presence of a polyether having a mercapto group in the side chain and saponifying the copolymer. The above-mentioned methods are mentioned as typical examples, but the present invention is not limited to these methods.

The EVOH-based copolymer containing the polyether thus obtained is blended with the EVOH containing no polyether component. Blend ratio contains polyether component
Depending on the type of polyether in the EVOH-based copolymer, the weight ratio, the addition form, and the required performance, in general, EVOH containing no polyether component is 95 to 50% by weight, and the polyether is The EVOH-based copolymer contained is preferably 5 to 50% by weight. As the blending method, known methods such as a method using a Banbury mixer and a melt blending method using a single-screw or twin-screw extruder can be adopted. Further, during this blending, other additives such as an antioxidant, an ultraviolet absorber, a lubricant, a plasticizer, an antistatic agent, a colorant and the like can be blended within a range where the effects of the present invention are not impaired. .

The resin composition of the present invention thus obtained can be easily molded by a well-known melt molding method, and can be molded into any molded article such as a film, a sheet, a tube or a bottle. Also other thermoplastics such as polypropylene,
When two or three layers of polyethylene, polyethylene terephthalate, polyamide, polystyrene, etc., or more than two layers are used, they can be formed by a known method such as multi-layer coextrusion, co-injection extrusion lamination, coating or the like. When three or more layers are used, the composition of the present invention is preferably used as an intermediate layer.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

G. Examples Examples 1-3 500 g of polyoxypropylene allyl ether having a molecular weight of 3000 and having a polymerizable double bond at both ends (Unisafe PKA-5018 manufactured by NOF Corporation) and benzoyl peroxide 4
mg was charged into a reactor equipped with a stirrer having a capacity of 1, and thioacetic acid was continuously added at room temperature at a rate of 13 g / hour for 3 hours while stirring. Then, unreacted thioacetic acid was removed from the reaction system under reduced pressure at 30 to 45 ° C. Next, 100 g of methanol and 1.1 g of sodium hydroxide were added, and the mixture was stirred under a nitrogen stream at 60 ° C. for 2 hours, and then acetic acid was added to neutralize excess sodium hydroxide. The mercapto group of the mercapto-modified polyoxypropylene thus obtained was titrated with I ₂ to yield 6.56 × 10 ^-4 eq / g.
And both ends having a double bond were almost quantitatively mercaptoized.

Next, in a polymerization tank equipped with a stirrer and having a cooling coil inside with a capacity of 50, 14.5 kg of vinyl acetate and 31 g of mercaptoated polyoxypropylene were charged, and after replacing the air in the polymerization tank with nitrogen, the temperature was raised to 60 ° C. Raise the temperature and charge ethylene to 43
It was set to kg / cm ² . Then, the polymerization initiator 2,2'-azobis-
14 g of (2,4-dimethylvaleronitrile) was dissolved in 300 ml of methanol and added, and then mercapto-polyoxypropylene was added at a rate of 440 g / hour for 4 hours to carry out a polymerization reaction. The polymerization rate of vinyl acetate was 42%. Then, the copolymerization reaction liquid was supplied to the expelling column, and unreacted vinyl acetate was removed from the top of the column by introducing methanol from the lower part of the column, and then a saponification reaction was carried out by a conventional method using sodium hydroxide as a catalyst. Then, after thoroughly washing with acetone and washing with water, it was immersed in a dilute aqueous solution of acetic acid and then dried at 60 to 105 ° C. under a nitrogen stream. EVOH thus obtained
The system copolymer is a block copolymer in which EVOH is added to both ends of polyoxypropylene, and its composition was analyzed by NMR. As a result, ethylene content was 30.8 mol%, polyoxypropylene content was 31% by weight, and vinyl acetate component was used. Saponification degree 99.1%
It was. Also, under the conditions of 190 ° C and 2160g load, ASTM D-
Melt index measured by the method of 1238-65T (hereinafter M
It is 120g / 10 minutes.

Next, this copolymer (Copolymer A), ethylene content 32.1 mol%, saponification degree of vinyl acetate component 99.5%, MI 0.61 g / 10 min
Compositions obtained by blending EVOH (EVOH No. 1) at various ratios were obtained, and these were film-formed by extrusion, and Young's modulus of the film, flex fatigue resistance and oxygen permeation amount were measured.

Extrusion film formation is carried out under the conditions of an extruder temperature of 180 to 220 ° C and a T die temperature of 215 ° C using a film forming machine having an extruder and a T die.
A film having a thickness of 15μ was obtained.

The Young's modulus was measured under the conditions of 20 ° C. and 65% RH for 7 days, using a sample as a sample, and according to ASTM D-638, an autograph was conducted under the conditions of a tensile rate of 200% / min. Carried out.

For the flex fatigue resistance test, a gel boflecks tester (manufactured by Rigaku Kogyo Co., Ltd.) was used, and a sample piece of 12 in x 8 in diameter was used. With a cylindrical shape, gripping both ends, initial gripping interval 7in, gripping interval at maximum bending 1in, first stroke Add a 440 ° angle twist at Repeated reciprocating motion of linear horizontal motion was performed at a speed of 40 times / min under the conditions of 20 ° C and 65% RH.

The oxygen gas permeation amount is measured by OX-TRAN manufactured by Modern Control.
100 was used and the humidity control was performed for 7 days under the conditions of 20 ° C., 65% RH and 20 ° C., 85% RH. The sample used for the measurement is
It is a sample in which the number of times of reciprocating reciprocation was variously changed in the bending fatigue resistance test.

To measure the number of pinholes, overlay the sample on blotter paper, apply the dye (red) on it, rub it with a roller, remove the sample, and check the number of pigments on the blotter paper.
Was done.

The results of these measurements are shown in Tables 1 and 2.

Comparative Examples 1-2 Instead of the resin compositions of Examples 1 to 3, the ethylene content was changed.
32.1 mol%, saponification degree of vinyl acetate component 99.5%, MI 0.61
When using a single EVOH (EVOH No.1) g / 10 min (Control Example 1) and when using a single EVOH (EVOH No.2) with an ethylene content of 31.5 mol% and a saponification degree of vinyl acetate component of 99.6% The same evaluation was performed for (Control Example 2). The results are also shown in Tables 1 and 2.

Examples 4 to 6 A vinyl acetate 25.0 kg and thioacetic acid 3.9 g were charged into a stirrer-equipped polymerization tank having a volume of 50 and a cooling coil inside, and the air in the polymerization tank was replaced with nitrogen, and then the temperature was raised to 60 ° C. The temperature was raised and ethylene was charged to adjust the pressure to 60 kg / cm ² . Then, 100 g of a polymerization initiator 2,2'-azobisisobutyronitrile was dissolved in 1 of methanol and added, and then 11.7 g of thioacetic acid / methanol solution was added at a rate of 500 ml / hour for 8 hours for polymerization. The reaction was carried out. The polymerization rate of vinyl acetate was 40%.
Then, the copolymerization reaction liquid was supplied to the expelling column, and unreacted vinyl acetate was removed from the top of the column by introducing methanol from the lower part of the column, and then a saponification reaction was carried out by a conventional method using sodium hydroxide as a catalyst. Next, the saponified product was thoroughly washed with water, further washed with acetone, and then dried under reduced pressure at 40 ° C.

Next, EVOH6 with a mercapto machine at the end obtained by the above method.
0 kg, polyoxypropylene allyl ether with a polymerizable double bond at one end and a molecular weight of 1500 (NOF Corporation)
Unisafe PKA-5014) (2.5 kg) and solvent dimethylsulfoxide (20 kg) were charged in the polymerization tank, the air in the tank was replaced with nitrogen, and the temperature was raised to 60 ° C to prepare a uniform solution.
Then, 500 ml of a methanol solution containing 100 g of 2,2'-azobisisobutylnitrile was added and the reaction was carried out for 5 hours.
Next, the reaction liquid was charged little by little into acetone 200 while stirring to deposit an EVOH-based copolymer. Then, after thoroughly washing with acetone, it was immersed in a dilute aqueous solution of acetic acid and then dried at 60 to 150 ° C. under a nitrogen stream. The EVOH copolymer thus obtained is a block copolymer in which polyoxypropylene was added to one end of EOVOH, and its composition was analyzed by NMR.As a result, the ethylene content was 44.2 mol% and the polyoxypropylene content was 24% by weight. %, The saponification degree of the vinyl acetate component was 99.4%. The MI was 230 g / 10 minutes.

Next, the copolymer (Copolymer B) and ethylene content 45.1 mol%, saponification degree of vinyl acetate component 99.5%, MI 2.8 g / 10 min E
VOH (EVOH No. 2) was blended in various proportions to obtain a composition, which was subjected to extrusion film formation in the same manner as in Examples 1 to 3, and the Young's modulus of the film, flex fatigue resistance and oxygen permeation amount were measured. The results of these measurements are shown in Tables 3 and 4.

Control Examples 3 to 4 Instead of the resin compositions of Examples 4 to 6, the ethylene content was changed.
45.1 mol%, saponification degree of vinyl acetate component 99.5%, MI 2.8g
/ 10 min EVOH (EVOH No.3) alone (Control Example 3) and ethylene content 44.3 mol%, saponification degree of vinyl acetate component 99.3%, MI9.5g / 10 min EVOH (EVOH No.4) ) The same evaluation was carried out when a single product was used (Corresponding Example 4). The results are also shown in Tables 3 and 4.

Examples 7 to 9 In a polymerization tank equipped with a stirrer and having a volume of 50 and a cooling coil inside, 11.0 kg of vinyl acetate, polyoxypropylene allyl ether having a molecular weight of 3000 and having a polymerizable double bond at both ends (NOF Corporation). Unisafe PKA-5018) 7.46 kg, methanol 4.7 kg and polymerization initiator 2,2'-azobis- (2,
4-Dimethylvaleronitrile) 45 g was dissolved in 500 ml of methanol and charged, the ethylene pressure was set to 37 kg / cm ² , and the temperature was 60 ° C.
The copolymerization was carried out for 6.8 hours. Polymerization rate of vinyl acetate is 40
It was in%. Then, the copolymerization reaction liquid was supplied to the expelling tower,
Unreacted vinyl acetate was removed from the top of the tower by introducing methanol from the bottom of the tower, and then a saponification reaction was carried out using sodium hydroxide as a catalyst by a conventional method. Then, after thoroughly washing with acetone and washing with water, it was immersed in a dilute aqueous solution of acetic acid and then dried at 60 to 105 ° C. under a nitrogen stream. The EVOH-based copolymer thus obtained has polyoxypropylene added in a graft form as a branch polymer of EVOH,
As a result of NMR analysis of the composition, the ethylene content was 37.6 mol%, the polyoxypropylene content was 49 wt%, and the saponification degree of the vinyl acetate component was 99.4%. The MI was 0.51 g / 10 minutes.

Next, the copolymer (Copolymer C) was blended with ethylene content 37.8 mol%, saponification degree of vinyl acetate component 99.4%, and EVOH (EVOH No. 5) of MI 1.3 g / 10 min at various ratios. The composition was obtained, and a film was formed in the same manner as in Examples 1 to 3, and the thickness was 15 μm.
The Young's modulus, flex fatigue resistance and oxygen permeation amount of the film were measured. The results are shown in Tables 5 and 6.

Control Example 5 Instead of the resin compositions of Examples 7 to 9, the ethylene content was changed.
37.8 mol%, saponification degree of vinyl acetate component 99.4%, MI 1.3g
Similar evaluations were carried out when using a single EVOH (EVOH No. 5) for 10 minutes. The results are also shown in Tables 5 and 6.

Examples 10 to 12 fully dehydrated poly (oxyethylene-oxypropylene) having a molecular weight of 3000 (Nilube 75DE manufactured by NOF CORPORATION)
60, weight ratio of oxyethylene / oxypropylene 75/2
5) 4.5 kg, 480 g of methylenebis (4-phenylisocyanate), 64 g of thioglycerol and 36 g of acetic acid in a volume of 10
Was charged in a reaction vessel equipped with a stirrer and stirred at 80 ° C. for 3 hours to synthesize a polyether having a mercapto group in its side chain.

Next, in a polymerization tank with a stirrer having a capacity of 50 and a cooling coil inside, 14.5 kg of vinyl acetate and 55 g of polyether having a thiol group in the side chain were charged, and the air in the polymerization tank was replaced with nitrogen. After that, the temperature was raised to 60 ° C., ethylene was charged, and the pressure was set to 43 kg / cm ² . Then, 14 g of a polymerization initiator 2,2′-azobis- (2,4-dimethylvaleronitrile) was added,
Then, a polyether having a thiol group in the side chain was added at a rate of 404 g / hour for 5 hours to carry out polymerization. The polymerization rate of vinyl acetate was 39%. Then, the copolymerization reaction liquid was supplied to the expelling column, and unreacted vinyl acetate was removed from the top of the column by introducing methanol from the lower part of the column, and then a saponification reaction was carried out by a conventional method using sodium hydroxide as a catalyst. Then, after thoroughly washing with acetone and water, dip treatment in dilute acetic acid aqueous solution, and then under nitrogen stream at 60 to 105 ° C
Dried in. The EVOH copolymer thus obtained is EVOH
Is added as a branched polymer of polyether in a graft form, and its composition was analyzed by NMR.
The content was 1.8 mol%, poly (oxyethylene-oxypropylene) 35% by weight, and the degree of saponification of the vinyl acetate component was 99.3%. The MI was 170 g / 10 minutes.

Next, the copolymer (Copolymer D), ethylene content used in Examples 1 to 32.1 mol%, and saponification degree of vinyl acetate component
99.5%, MI 0.61 g / 10 min EVOH (EVOH No. 1) was blended in various proportions to obtain compositions, which were then used in Examples 1-3.
The film was extruded in the same manner as above, and the Young's modulus, flex fatigue resistance and oxygen permeation amount of the film having a thickness of 15 μm were measured. The results are shown in Tables 7 and 8.

Control Examples 6 to 7 Instead of the resin compositions of Examples 10 to 12, the ethylene content was 31.4.
Mol%, saponification degree of vinyl acetate component 99.5%, MI 1.2g / 10
Minute EVOH (EVOH No.6) used alone (Comparative Example 6)
The same evaluation was carried out for a case where a single EVOH (EVOH No. 7) having an ethylene content of 32.3 mol%, a saponification degree of a vinyl acetate component of 99.6% and an MI of 3.5 g / 10 min (Control Example 7) was used. The results are also shown in Tables 7 and 8.

Example 13 Using the copolymer A shown in Examples 1 to 3, a laminated film of 5 layers of 3 types (inner layer / adhesive layer / intermediate layer / adhesive layer / outer layer) was measured as a sample. The film forming machine is an extruder for inner and outer layers,
The extruder for the intermediate layer and the extruder for the adhesive layer each consist of one unit and the T-die for the five layers, and the molding temperature is 160-220 ° C. for the inner and outer layers.
Extruder for middle layer 180-220 ℃, Extruder for adhesive operation 120-220
C., T-die 225.degree. The intermediate layer was a blend of 25 parts by weight of copolymer A and 75 parts by weight of EVOH (EVOH No. 1) shown in Comparative Example 1, and the inner and outer layers contained 1-octene as a copolymerization component, and the copolymerization component was 3.3 mol. %, A linear low density polyethylene with an MI of 1.6 g / 10 min, the adhesive layer is a modified ethylene with a vinyl acetate content of 33% by weight and a maleic anhydride modification degree of 1.5% by weight.
It is a vinyl acetate copolymer (MI 2.0 g / 10 minutes). The thickness of the laminated film was 12 μm for the intermediate layer, 30 μm for each of the inner and outer layers, and 5 μm for each of the adhesive layers.

Next, in the same manner as in Examples 1 to 3, a bending fatigue resistance test and an oxygen gas permeation amount were measured. The results are shown in Table 9.

Comparative Example 8 As an intermediate layer in Example 13, the copolymer A and EVOH No.
A laminated film was obtained in the same manner as in the same example except that EVOH No. 1 alone was used in place of the blended product of 1, and the bending fatigue resistance test and the oxygen gas permeation amount were measured. The results are also shown in Table 9.

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Claims (5)

[Claims] 1. An ethylene-vinyl alcohol copolymer 95 to 50% by weight which does not contain a polyether component as a component constituting a polymer, and an ethylene-vinyl alcohol copolymer which contains a polyether component as a component constituting a polymer. A resin composition comprising 5 to 50% by weight of a polymer. 2. An ethylene-vinyl alcohol copolymer containing a polyether component as a component constituting a polymer is a block copolymer of a polyether component and an ethylene-vinyl alcohol copolymer component. The resin composition according to claim 1. 3. An ethylene-vinyl alcohol copolymer containing a polyether component as a component constituting a polymer, wherein the polyether component is graft-added as a branch polymer of the ethylene-vinyl alcohol copolymer. The resin composition according to claim 1. 4. A patent in which an ethylene-vinyl alcohol copolymer containing a polyether component as a component constituting a polymer is graft-added as an ethylene-vinyl alcohol copolymer component as a polyether branch polymer. The resin composition according to claim 1. 5. The resin composition according to any one of claims 1 to 4, wherein the polyether component is composed of oxypropylene units.