JPH10212379A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin compsn. which has both flexibility and improved gas barrier properties by compounding a polyamide resin, an ethylene-vinyl alcohol copolymer, and at least one substrate selected from among arom. carboxylic esters and olefinic elastomers. SOLUTION: This compsn. comprises a polyamide resin (A) selected from among 11-nylon, 12-nylon, etc., an ethylene-vinyl alcohol copolymer (B) having an ethylene content of 20-65mol% and a degree of saponification of 95mol% or higher, and at least one substance (C) selected from among arom. carboxylic esters having a b.p. of 160 deg.C or higher at 2mmHg (e.g. ethyl or methyl benzoate) and olefinic elastomers (e.g. an ethylene-propylene copolymer, an ethylene- propylene-diene copolymer, or a mixture of such a copolymer with polyethylene or polypropylene) in a wt. ratio of A/B of (95/5)-(5/95) and in a wt. ratio of (A+B)/C of (100/2)-(100/40).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition comprising a mixture of a polyamide resin, an ethylene-vinyl alcohol copolymer (EVOH) and a third component and having excellent heat stability and melt moldability. Further, the present invention relates to a resin composition which is excellent in laminating processability with rubber and which is suitable for supplying a molded product suitable for imparting barrier properties without impairing the flexibility of rubber even when laminated.

[0002]

[Prior art]

(Part 1): EVOH is excellent in melt moldability, gas barrier properties, fragrance retention, oil / solvent resistance, and antistatic properties, and polyamide resin is excellent in impact resistance, flexibility, and high-temperature wet heat resistance. Heretofore, it has been proposed that a molded product comprising a composition obtained by mixing the two is used as a film, sheet, or bottle for food packaging, medicine, and agricultural chemicals.

However, as is well known, both polyamide resin and EVOH have poor thermal stability, and there is a problem of gel formation when molding is continued for a long time. However, in the case of a mixture of polyamide resin and EVOH, this is further accelerated and the molding is accelerated. You may see gel formation after the start time. Furthermore, a mixture of polyamide resin and EVOH has a large die swell during molding, especially in a polyamide resin in which the ratio of the number of methylene groups to the number of amide groups is 9 ≦ CH ₂ / NHCO, so that the melt molding increases the thickness unevenness of the film and sheet. There is also a problem of poor sex, and improvement is demanded.

As a method for improving the thermal stability, it has been proposed to increase the ratio of the carboxyl group to the amide group at the terminal of the polyamide to an excess of carboxyl groups. However, the required thermal stability improving effect has not yet been obtained. On the other hand, there is no known technique for improving melt formability.

(2) Conventionally, acrylonitrile-butadiene copolymer rubber (N) is used for applications requiring flexibility and gas barrier properties such as a freon hose for an automobile air conditioner, a diaphragm for an expansion tank of a hot water supply and heating system, and the like.
Rubber products having excellent gas barrier properties such as BR) and butyl rubber have been used, but in recent years in various fields, rubber alone has not been able to cope. For example, for Freon hoses, it is essential to reduce gas leakage from hoses in order to prevent the stratospheric ozone layer from being destroyed by Freon gas.
It is said that it is necessary to reduce it to 1/10 or less,
NBR and other rubber hoses cannot be used. Conventionally, butyl rubber is used for the diaphragm of the expansion tank of the hot water supply and cooling / heating systems, and the pressure of the nitrogen gas decreases over time. Although it is necessary, the use of this type of expansion tank has been growing rapidly in recent years, and in order to avoid the trouble of adjusting the encapsulation, the nitrogen gas permeability of the rubber has been increased in order to greatly extend the adjustment period or eliminate the need for adjustment. 1/5 to 1/10
It is necessary to reduce it below.

As a method for improving the barrier properties of rubber, it has been easily conceived to combine rubber and gas barrier resin, and the use of various barrier resins has been proposed.
Some proposals have been made regarding the use of EVOH or nylon. For example, JP-A-58-197040,
JP-A-60-18331 and JP-B-62-29242 disclose that EVOH is laminated with rubber in a single layer or a multilayer of polyamide and other resins.
OH is used alone and is inferior in low-temperature strength, low-temperature flexibility, and high-temperature wet heat resistance. Also, JP-A-53-63614
Proposes laminating a mixture of EVOH and polyamide with rubber, but the examples are EVOH alone or EOH.
Only blends of VOH and modified polyethylene are described. JP-B-44-24277 and JP-A-50-121347 disclose blends of EVOH and polyamide. Although all of these publications describe the use of 6-nylon, the specification and examples thereof do not. There is no description about 11 nylon or 12 nylon. In addition, EVOH and 6-nylon systems tend to generate gel during molding, and are inferior in flexibility and high-temperature wet heat resistance.

In addition, Japanese Patent Application Laid-Open No. 63-114645 discloses that the ratio of the number of methylene groups to the number of amide groups is 6.6 ≦ CH ₂ / NH
Although a blend of a nylon resin and EVOH that satisfies CO ≦ 10 is disclosed, this configuration has insufficient flexibility.

[0008]

[Problems to be solved by the invention]

<First Problem> The conventional technology for mixing EVOH and polyamide resin does not sufficiently solve the thermal stability, and the solution to the melt molding defect is not completely known. This solution is the first solution of the present invention. It is an issue of. <Second Problem> A second object of the present invention is to provide flexibility, for example, to improve the gas barrier property without impairing the flexibility of rubber by compounding a mixture of EVOH and polyamide with rubber.
It is an issue of.

[0009]

Means for solving the first problem include (A) a polyamide resin and (B) EVO.
H is to be mixed with at least one selected from (C) aromatic acid esters and olefin-based elastomers. Means for solving the first and second problems is to select 11-nylon and / or 12-nylon as the polyamide resin (A), and blend (B) and (C) with it. That is.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, details of means for solving the first problem will be described.

The (B) EVOH used in the present invention has an ethylene content of 20 to 65 mol%, preferably 25 to 50 mol%, and a saponification degree of the vinyl acetate portion of 95 mol% or more, preferably 99.0 mol%. These are mentioned above. If the ethylene content is less than 20 mol%, the gas barrier property at high humidity decreases, and if it exceeds 65 mol%, the gas barrier property also decreases. If the degree of saponification is less than 95 mol%, the gas barrier property also decreases. The melt index (MI) of EVOH (at 190 ° C. under a load of 2160 g) is preferably 0.5 to 20 g / 10 min.

The polyamide resin (A) used in the present invention includes nylon 6, nylon 10, nylon 11, nylon 12, nylon 6.6, nylon 6.9, nylon 6.9, nylon 6.11, and nylon 6.1. 12, Nylon 6 / 6,6, Nylon 12,12 or the like, or a mixture of two or more thereof. The mixing ratio {(A) / (B)} of (A) polyamide resin and (B) EVOH in the present invention is 95/5 to 5/95 by weight ratio,
Preferably 10/90 to 80/20, more preferably 25/75
７０70/30. If the mixing ratio of EVOH is less than 5%, the gas barrier properties will be insufficient. On the other hand, if the mixing ratio of the nylon resin is less than 5%, impact resistance and flexibility are poor.

The present invention is characterized in that an aromatic acid ester or a polyolefin-based elastomer is mixed and used as the third component. By mixing these third components, the heat stabilization of the mixture of EVOH and the polyamide resin is first performed. Poor quality and / or poor melt moldability, that is, gel generation and / or thickness variation can be solved.

As the aromatic acid ester (C) used in the present invention, benzoic acid esters such as methyl benzoate, ethyl benzoate, and 2-ethylhexyl benzoate, and derivatives thereof can be used. / 2m
Those with mHg are preferred.

As the olefin elastomer of the present invention, a copolymer of ethylene and propylene (EPM), a copolymer of ethylene, propylene and a diene monomer (EPDM), or a mixture of these copolymers with polyethylene or polypropylene. Things can be used.

In the present invention, the weight ratio of the third component (C) to the total weight of (A) EVOH and (B) polyamide resin is {(A) + (B)} / (C) = 100/2 to 100
/ 40. If the weight ratio of the third component is less than 2/100, poor heat stability and / or poor melt moldability will not be improved, and if the weight ratio exceeds 40/100, the barrier properties will be insufficient.

The reason why the mixing of these third components improves the thermal stability of EVOH and the polyamide resin and the mixed melt moldability is mainly that EVOH is mainly used for EVOH.
It is presumed that this is due to the effect of improving the compatibility between OH and the polyamide resin, and the polyolefin-based elastomer is mainly due to the effect of reducing the reaction between EVOH and the polyamide resin.

Next, the means for solving the first and second problems of the present invention will be described in detail.

The present inventor has attempted to solve the above-mentioned problems by providing 11
A mixture of nylon or 12-nylon and EVOH having excellent gas barrier properties was examined. 11-nylon and 12-nylon are excellent in flexibility and high-temperature wet heat resistance, but are inferior in gas barrier properties. On the other hand, EVOH has excellent gas barrier properties, but is inferior in flexibility and high-temperature wet heat resistance. Therefore, by mixing 11-nylon or 12-nylon with EVOH, it is expected that excellent physical properties supplementing the respective disadvantages will be obtained. However, as is well known, nylon resin and EVO
When H is mixed and melted, there is a drawback that thermal stability is poor, such as generation of a gel, and operation cannot be performed for a long time.
In the mixing of 2-nylon and EVOH, a large die swell additionally causes a problem that the thickness of the tube, sheet or film is fluctuated in the longitudinal direction. Therefore, the present inventor has conducted intensive studies on such poor melt moldability, that is, the improvement of gel generation and thickness variation, and as a result, further mixing a specific third component with a mixture of 11-nylon or 12-nylon and EVOH. And found that the present invention was completed.

That is, the first and second objects of the present invention are (A) at least one selected from 11-nylon and 12-nylon and (B) EVOH with (C) an aromatic acid ester and an olefin-based elastomer. It is solved by blending at least one member selected from the group consisting of:

Here, as the 11-nylon or 12-nylon, homopolymers and copolymers of ω-aminoundecanoic acid, ω-aminododecanoic acid or ω-laurolactam, and 12.12 nylon can be mentioned. These nylon resins are mainly used alone, but may be mixed. (A) / (B), ｛(A) +
(B) The mixing ratio of｝ / (C) is as described above.

As a method for melt-molding the resin composition of the present invention, methods such as extrusion inflation film formation, extrusion cast film formation, T-die sheet molding, tube molding, compression molding, injection molding, and transfer molding can be used.

As for the mixing of (A) EVOH, (B) polyamide resin and (C) third component, any method can be adopted as long as the three components are mixed before molding, but (A) + ( B) + (C) is formed after being melt-mixed and pelletized, or the melt-mixed pellet of (A) + (C) is mixed with the pellet of (B) and then formed, or (B) + (C) It is preferable that the melt-mixed pellets and the pellets of (A) are mixed and then molded.

The molding temperature is preferably from 180 to 260 ° C, more preferably from 200 to 240 ° C. When the temperature exceeds 260 ° C., the aromatic acid ester volatilizes, which is not preferable. If necessary, the composition of the present invention may be a carboxylic acid-modified polyolefin, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 40% by weight (EVA), an EVA saponified product, etc., as long as the gas barrier property is not impaired. May be added.

The molded article comprising the resin composition of the present invention has excellent gas barrier properties, flexibility, impact resistance, and high-temperature wet heat resistance, and can be used alone as sheets, films, tubes, bottles, containers, and various molded articles. Alternatively, it can be used in the fields of foods, medicines, industrial supplies, and the like, in a multilayer structure with various plastics and rubbers.

(A) A molded article made of the resin composition of the present invention using 11-nylon or 12-nylon as a polyamide resin is flexible, has excellent gas barrier properties, and resistance to high-temperature, high-humidity heat. It is used mainly in combination with rubber, such as an inner layer tube or an intermediate layer of a diaphragm, but other uses are of course possible.

The vulcanization of rubber is generally 150 to 180.
C., which is carried out by steam heating for about 4 to 6 hours, but the molded article made of the resin composition of the present invention is extremely excellent in high-temperature, wet-heat resistance, and shows no melting deformation even after vulcanization. .

The molded article comprising the resin composition of the present invention may be used alone or as long as it does not impair flexibility.
Or, of course, it can be used in multiple layers with various resins including 12-nylon. Coextrusion molding, lamination processing, etc. can be used for multilayering. Next, the resin composition of the present invention will be further described by way of examples.

[0029]

【Example】

Example 1 Ethylene content: 44.5 mol%, degree of saponification: 99.5 mol%, MI (at 190 ° C. under a load of 2160 g) 5.5 g / 1
To a tumbler mixed pellet of 50 parts by weight of 0 minute EVOH and 50 parts by weight of 6/12 copolymerized nylon (copolymerization ratio 6/12 = 90/10), 4 parts by weight of 2-ethylhexyl paraoxybenzoate was added by an extruder hopper. While the extruder (4
0 mmφ, L / D = 28), and melt-blended and pelletized at 230 ° C. using a pelletizing apparatus including a die, a cooling water tank, and a cutter. Pellet molding was smooth and the thickness of the strand discharged from the die was uniform in the flow direction.

Using these pellets, an extruder (40 mm
φ, L / D = 28), a film having a thickness of 50 μm was formed at an extrusion temperature of 230 ° C. using a film forming machine including a T-die and a take-off machine. The film preparation was smooth without thickness fluctuation and gel generation. The oxygen permeability of this film was measured using OXTRAN 10 / 50A manufactured by Modern Control.
Was measured at 20 ° C. and 65% RH using
It was 8.6 cc · 20 μ / m ² · day · atm.
The oxygen permeation rate of the used 6/12 copolymer nylon film was 240 cc · 20 μ / m ² · day · atm.
Met.

Comparative Example 1 Ethylene content 32.0 mol%, degree of saponification 99.6 mol%, MI (190 ° C., under load of 2160 g) 1.3 g / 1
Example 1 A tumbler mixed pellet of 70 parts by weight of EVOH pellets and 30 parts by weight of 12-nylon pellets was prepared in Example 1.
Pelletization was performed at an extrusion temperature of 230 ° C. using the same apparatus as in the above. The thickness of the strands drawn from the die fluctuated in the flow direction, and the strands were frequently cut, making it difficult to achieve continuity. Using these pellets, 5
When a film having a thickness of 0 μm was formed, continuous film formation was possible, but a gel was observed in the obtained film, and the film had a thickness fluctuation in the flow direction, and was of no commercial value.

Example 2 Ethylene content 47.5 mol%, degree of saponification 99.6 mol%, MI (190 ° C. under 2160 g load) 14 g / 10
Of tumbler mixed with 80 parts by weight of EVOH, 20 parts by weight of 6-nylon and 25 parts by weight of ethylene-propylene copolymer rubber at 250 ° C. in the same apparatus as in Example 1.
And pelletized. Pellet molding was smooth and the thickness of the strand discharged from the die was uniform in the flow direction. Using the pellets, a 50 μm film was formed at an extrusion temperature of 250 ° C. using the same film forming machine as in Example 1. The film was good without any discoloration, no thickness variation and no gel formation. The oxygen permeability of the obtained film was 7.3 cc · 20 μ / m ² · day · atm. The 6-nylon single film used had an oxygen permeability of 130 cc · 20 μ / m ² · day · atm.

Comparative Example 2 Pellets were formed in the same manner as in Example 2 except that the ethylene-propylene copolymer rubber was omitted. Although the strand was yellowed, there was no unevenness in the flow direction, and the take-up was smooth. When a film having a thickness of 50 μm was formed using the pellets in the same apparatus as in Example 1, yellowing further advanced, and a gel was observed.

Example 3 ω-Laurolactam Ring-Opening Polymer 12-Nylon 40
Polymerized part, ethylene content 44.2 mol%, degree of saponification 99.
4. 5 mol%, MI (190 ° C., 2160 g load measurement)
An extruder (40) was added while adding a tumbler mixed pellet of 60 parts by weight of EVOH and 30 parts by weight of an ethylene-propylene copolymer rubber from an extruder hopper.
mmφ, L / D = 28), and a melt-mixed pellet was formed at 220 ° C. using a pelletizing apparatus including a die, a cooling water tank, and a take-off cutter. Pellet molding was smooth and the thickness of the strand discharged from the die was uniform in the flow direction. Using these pellets, an extruder (40 mmφ, L / D
= 28), and a 50 μm thick film was formed at an extrusion temperature of 220 ° C. using a film forming machine including a T-die and a take-off machine. The film preparation was smooth without thickness fluctuation and gel generation.

This film and a control with a thickness of 300
μm butyl rubber and 860 μm thick NBR,
According to ASTM D1434, nitrogen gas permeability at 35 ° C. (cc · 20 μ / m ² · day · atm), 7
Freon 12 gas permeability at 0 ° C (cc · 20μ / m
^The following results were obtained by measuring ( ² · day · atm). Sample Nitrogen gas permeability Freon 12 gas permeability Film of Example 3 70 180 Butyl rubber 18000 Not measured NBR Not measured 16000

Example 4 60 parts by weight of 11-nylon of a condensation polymer of ω-aminoundecanoic acid and 2-ethylhexyl paraoxybenzoate 10
Parts by weight of melt-blended pellets, ethylene content 32.0 mol%, degree of saponification 99.6 mol%, MI (190 ° C, 216
0 g load measurement) EVOH pellet 4 of 1.3 g / 10 min
0 parts by weight of the tumbler mixture was melt-mixed and pelletized at 220 ° C. in the same pelletizing apparatus as in Example 3. The strand molding was smooth, and the thickness of the strand discharged from the die was uniform in the flow direction. Using these pellets, a film having a thickness of 50 μm was formed at an extrusion temperature of 220 ° C. using the same film forming machine as in Example 3. Preparation of the film was smooth without any thickness fluctuation and gel generation. The gas permeability of the obtained film was as follows. Sample Nitrogen gas permeability Freon 12 gas permeability Film of Example 4 120 140

Comparative Example 3 60 parts by weight of 11-nylon of a condensation polymer of ω-aminoundecanoic acid, an ethylene content of 32.0 mol%, and a saponification degree of 9
9.6 mol%, MI (190 ° C, 2160g load measurement)
A tumbler-mixed pellet of 40 parts by weight of EVOH of 1.3 g / 10 minutes was subjected to 220 ° C. in the same pelletizing apparatus as in Example 3.
When the melt-mixing pelletization was performed, the thickness of the strand discharged from the die fluctuated in the flow direction, the strand was frequently cut, and it was difficult to make the strand continuous. Using these pellets and the same film forming machine as in Example 3,
When an attempt was made to produce a film having a thickness of 50 μm at an extrusion temperature of 220 ° C., continuous production of the film was possible, but the resulting film had thick and thin spots, a gel was observed, and was of no commercial value.

Comparative Example 4 Using the same film forming machine as in Example 3, 1
2-Nylon alone is used to form a film and the thickness is 300 μm
Was obtained. The gas permeability of this film was low in gas barrier performance as follows. Sample Nitrogen gas permeability Freon 12 gas permeability 12-nylon film 4700 3900

Comparative Example 5 Using the same film forming machine as in Example 3,
A single film was formed with VOH to obtain a film having a thickness of 300 μm. The film was formed smoothly, and a gel-free film having a uniform thickness was obtained. The gas barrier properties of this film were excellent as follows, but were expected to be extremely hard and impair the flexibility of the rubber. When a 1-mm-thick unflowed NBR was pasted on both sides of this film and then steam-vulcanized, the EVOH layer was melted and deformed, resulting in uneven thickness. Sample Nitrogen gas permeability Freon 12 gas permeability EVOH film 0.6 0.7

[0040]

The resin composition of the present invention has excellent melt moldability, excellent gas barrier properties, and excellent resistance to high-temperature wet heat.
Further, the molded product obtained by using 11-nylon and 12-nylon as the polyamide resin is flexible and extremely excellent in improving the gas barrier properties of rubber by laminating with rubber.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B32B 25/08 B32B 25/08

Claims (3)

[Claims] 1. A resin composition comprising (A) a polyamide resin, (B) an ethylene-vinyl alcohol copolymer, and (C) at least one selected from an aromatic acid ester and an olefin-based elastomer. 2. (A) / (B) = 95 / 5-5 / 95
(Weight ratio), {(A) + (B)} / (C) = 100 /
The resin composition according to claim 1, wherein the ratio is 2 to 100/40 (weight ratio). 3. The resin composition according to claim 1, wherein (A) the polyamide resin is at least one selected from 11-nylon and 12-nylon.