JPH03106953A - Resin composition and multilayered structure - Google Patents

Abstract

PURPOSE:To improve the thermal stability, melt moldability, and laminatability with rubber, and obtain a molded article excellent in the barrier properties by compounding a polyamide resin a saponificated ethylene-vinyl acetate copolymer, and a specific third component. CONSTITUTION:A resin compsn. is prepd. by compounding: a polyamide resin (A) pref. comprising nylon 11 and/or nylon 12; a saponificated ethylene-vinyl acetate copolymer (B) having an ethylene content of 20-65mol% and a saponification degree of the vinyl acetate part of 95mol% or higher in such an amt. that the ratio of A to B is (95:5)-(5:95); and a third component (C) selected from the group consisting of an arom. acid amide, an arom. acid ester, and an olefinic elastomer in such an amt. that (A+B)/C is 100/2-4.

Description

[Detailed Description of the Invention] A. The present invention relates to a resin composition having excellent thermal stability and melt moldability, which is composed of a mixture of a polyamide resin, an ethylene-vinyl alcohol copolymer (EVOH), and a third component. Furthermore, the present invention relates to a resin composition that has excellent lamination processability with rubber, does not impair the flexibility of the rubber even when laminated, and is suitable for providing molded articles suitable for imparting barrier properties.

L Ichihong LL Unhong (Part 1): EVOH has excellent melt moldability, gas barrier properties, fragrance retention, oil and solvent resistance, and antistatic properties, and polyamide resin has excellent impact resistance, flexibility, and high temperature and humidity properties. Due to their excellent thermal properties, molded products made from a mixture of the two have been proposed for use as films, sheets, and bottles for food packaging, pharmaceuticals, 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 if they are kept in shape for a long time, but polyamide resin and EVOH
This process is further accelerated in the case of mixtures of 1 and 2, and gel formation may be observed several hours after the start of molding. Furthermore, the mixture of polyamide resin and EVOH has a ratio of methylene groups to amide groups of 9≦CH. / NHCO's polyamide resin has a large die swell during molding, which makes the film
There is also a problem of poor melt moldability, such as increased thickness unevenness of the sheet, and improvements are desired.

As a method for improving thermal stability, a proposal has been made to increase the ratio of carboxyl groups to amide groups at the end of polyamide, but it is difficult to sufficiently increase the ratio of carboxyl groups in the production of polyamide. However, the necessary thermal stability improvement effect has not yet been achieved. On the other hand, no technology for improving melt moldability is known.

(Part 2): Conventionally, Freon hoses for automobile air conditioners,
Rubber products with excellent gas barrier properties such as acrylonitrile-butadiene copolymer rubber (NBR) and butyl rubber are used for applications that require flexibility and gas barrier properties, such as diaphragms of expansion tanks in hot water supply and cooling/heating systems. However, in recent years, in various fields, we have reached the point where rubber alone cannot handle the situation. For example, regarding Freon hoses, in order to prevent the destruction of the stratospheric ozone layer due to Freon gas,
It is essential to reduce gas leakage from hoses, and it is said that it is necessary to reduce the Freon 12 gas permeability of hoses to less than 1/5 to 1/1a of the current level, but with NBR and other rubber hoses, It is impossible to respond.

In addition, butyl rubber has traditionally been used for the diaphragms of expansion tanks in hot water supply and cooling/heating systems, and as the pressure of the nitrogen gas in the tank decreases over time, the nitrogen gas is filled in and adjusted every few months to a year. However, the use of this type of expansion tank has rapidly increased in recent years, and in order to avoid the trouble of sealing and adjusting, the adjustment period can be significantly extended or the adjustment is not required. 1/5 ~
There is an urgent need to reduce it to below 1/1O.

As a method to improve the barrier properties of rubber, it was easily conceived to combine rubber and gas barrier resins, and the use of various barrier resins has been proposed, and there are also some proposals for the use of EvOH or nylon. Can be seen. For example, JP-A-58-197040, JP-A-60
- 18331, Jikosho 62-29242 has EVO
It has been disclosed that H is laminated with rubber in a single layer or in a multilayer with polyamide or other resin, but in both cases, EVOH is used alone and is inferior in low-temperature strength, low-temperature flexibility, and high-temperature, moist-heat resistance.

Furthermore, JP-A-53-63614 proposes laminating a mixture of EVOH and polyamide with rubber;
The examples only describe EVOH alone or a blend of EVOH and modified polyethylene. In addition, JP 1977-24277 or JP 50-1213
No. 47 discloses a blend of EVOH and polyamide y, but although both publications mention the use of 66-nylon, there is no mention of 11 nylon or 12 nylon in their specifications and examples. Also EVOH
and 6-nylon type materials tend to generate gel during molding and are inferior in flexibility and high 7AL moisture heat resistance.

In addition, in JP-A No. 63-114645, the ratio of the number of methylene groups to the loss of amide groups is 6.6≦CI, / IIHcO≦
A blend of nylon resin and EVOH that satisfies 10 has been disclosed, but this configuration has insufficient flexibility.

C. The first problem that we are trying to solve is that the conventional technology for mixing EVOH and polyamide resin is not sufficient to solve the problem of thermal stability.
It is completely unclear how to solve the defective melt molding, and this solution is the first subject of the present invention.

The second problem of the present invention is to impart flexibility and improve gas barrier properties without impairing the flexibility of the rubber by, for example, compounding a mixture of EVOH and polyamide with rubber.
This is an issue.

D. The means for solving the first problem is to use (A) a polyamide resin, (B) EVOH, and (C) an aromatic acid amide, an aromatic acid ester, and an olefin elastomer. At least one kind is blended.

Moreover, the means for solving the first problem and the second problem is to select 1l-nylon and/or 12-nylon as the polyamide resin of (A), and blend (B) and (C) thereto. That's true.

Next, the details of the means for solving the first problem will be described first.

(B) EV O H used in the present invention has an ethylene content of 20 to 65 mol%, preferably 25 to 50 mol%,
Saponification degree of vinyl acetate moiety is 95 mol% or more, preferably 99
．． Examples include those containing 0 mol% or more. If the ethylene content is less than 20 mol%, the gas barrier properties at high humidity will decrease,
If it exceeds 65 mol%, the gas barrier properties will still deteriorate. Furthermore, if the degree of saponification is less than 95 mol%, the gas barrier properties will also decrease. Further, the melt index (M I ) of EvOH (at 190° C. under a load of 2160 g) is preferably 0.5 to 20 g/to.

(A) polyamide resin used in the present invention includes nylon 6, nylon 10, nylon 11, nylon 12, nylon 6.6, nylon 6.9, nylon 6.10, nylon 6゛.11, nylon 6.12, Nylon 6/6
・One or a mixture of two or more selected from Nylon 6, Nylon 12, Nylon 12, etc. can be used.

(^) Polyamide resin and (B) EV in the present invention
The mixing ratio of OH ((A)/(B)) is 9 by weight.
5/5 to 5/95, preferably 10/90 to 80/
20, and even 25/75-70/: {O.

If the mixing ratio of EVO is less than 5%, gas barrier properties will be insufficient. On the other hand, if the mixing ratio of nylon resin is less than 5%, impact resistance and flexibility are poor.

The present invention is characterized by the use of a mixture of aromatic acid amide, aromatic acid ester, or polyolefin elastomer as the third component, and by mixing these third components, EVOH and polyamide resin can be produced for the first time. Poor thermal stability and/or poor melt moldability of the mixture, ie, gel formation and/or thickness variation, can be solved.

The <C> aromatic acid amide or aromatic acid ester used in the present invention is benzenesulfonic acid ethylamide,
Benzene sulfonic acid amide and its derivatives such as benzene sulfonic acid butylamide, or benzoic acid amide and its derivatives such as benzoic acid ethylamide, benzoic acid butylamide, benzoic acid 2-ethylhexylamide, or methyl benzoate, ethyl benzoate, and 2-ethylhexyl benzoate. Benzoic acid esters and their derivatives such as
iHg is 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 is used. can.

In the present invention, the weight ratio of the third component (C) to the total weight of (A) E V O H and (B) polyamide resin is {
(A) + (B) ) / (C) = 100/
It is 2 to 100/40. The weight ratio of the third part is 27
If it is less than tGo, poor thermal stability and/or poor melt moldability will not be improved, and the weight ratio will be 40/100.
Exceeding this will result in insufficient barrier properties.

The reason why mixing these third components improves the thermal stability and mixed melt moldability of EVOH and polyamide resin is as follows.
For aromatic acid amides and aromatic acid esters, this is mainly due to the effect of improving the compatibility between EVOH and polyamide resin, and for polyolefin elastomers, this is mainly due to the effect of reducing the reaction between EVOH and polyamide resin. I'm guessing.

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

In order to solve the above problems, the present inventors studied a mixture of it-nylon or 12-nylon and EVOH, which has excellent gas barrier properties. 1l-nylon and 12-
Nylon has excellent flexibility and high temperature, humidity and heat resistance, but has poor gas barrier properties. On the other hand, EvOH has excellent gas barrier properties, but is inferior in flexibility and high temperature, humidity and heat resistance. Therefore, it is expected that by mixing 11-nylon or 12-nylon with EVOH, a material with excellent physical properties that compensate for the drawbacks of each can be obtained. However, as is already well known, when nylon resin and EVOH are mixed and melted, there are disadvantages such as generation of gel and poor thermal stability, which prevents long-term operation. Due to the large die swell, there is a problem in that the thickness varies in the length direction when forming tubes, sheets, or films.

Therefore, as a result of intensive studies to improve such poor melt moldability, that is, gel formation and thickness fluctuation, the inventor of the present invention has found that a specific third component is further mixed into the mixture of 11-nylon or 12-nylon and EVOH. The present invention was completed based on the discovery that improvements can be made.

That is, the first and second problems of the present invention are (A) 1
Solved by blending at least tW selected from 1-nylon and 12-nylon and (B) EVOH with at least one selected from (C) aromatic acid amide, aromatic acid ester, and olefin elastomer. Ru.

Here, as 11-nylon or 12-nylon, ω
Examples include homopolymers and copolymers of -aminoundecanoic acid, ω-aminododecanoic acid or ω-laurolactam, and I2.12 nylon. These nylon resins are mainly used alone, but they may also be mixed.

(A) / (B), C (person) + (B) ) / (
The mixing ratio of C) is as described above.

Methods for melt-molding the resin composite of the present invention include extrusion inflation film forming, extrusion casting film forming, T-die molding,
Methods such as tube molding, compression molding, injection molding, and transfer molding can be used.

(A) E v O H and (B) polyamide resin and (C)
Regarding mixing of the third component, any method can be adopted as long as the three components are mixed prior to molding, but (A
) + (B) + (c) is melt-mixed into pellets and then molded, or melt-mixed pellets of (A) + (C) and (B)
pellets are mixed and then formed, or (B)+
It is preferable to mix the melt mixed pellets (C) and the pellets (A) and then mold them.

The molding temperature is preferably 180 to 260°C, preferably 200°C.
~240°C. If the temperature exceeds 260°C, the aromatic acid amide or aromatic acid ester will volatilize, which is not preferable. If necessary, the composition of the present invention may contain carboxylic acid-modified polyolefin, as long as the gas barrier properties are not impaired.
An ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content of 3 to 40% by weight, a saponified EVA product, or the like may be added.

The molded article made of the resin composition of the present invention has gas barrier properties,
It has excellent flexibility, impact resistance, high temperature, humidity and heat resistance, and can be used as sheets, films, tubes, bottles, containers, and various molded products, either alone or in multiple layers with various plastics and rubbers, for food, medicine, and industrial products. It can be used in fields such as

(A) A molded product made of the resin composition of the present invention using 11-nylon or 12-nylon as the polyamide resin is flexible, has excellent gas barrier properties, and high temperature and humidity resistance, and is suitable for use in inner tubes of Freon hoses or diaphragms. It is mainly used in combination with rubber, such as in an intermediate layer, but other uses are of course possible.

Vulcanization processing of rubber is generally carried out by steam heating at 150 to 180'C for about 4 to 6 hours, but the molded product made of the resin composition of the present invention has extremely excellent high temperature, moist heat resistance, and can be vulcanized. No melt deformation is observed even after processing.

In addition to being used alone, the molded product made of the resin composite of the present invention can be used as a 11- or 12-
-Of course, it can be used in multiple layers with various resins including nylon. Coextrusion molding, lamination processing, etc. can be used for multi-layering.

Next, the resin composition of the present invention will be further explained by giving examples.

Example 1 Ethylene content 32.0 mol%, saponification degree 99.6 mol%
, M I (190℃, under 2160g load > 1.3g
/10 minutes EvoH 70 parts by weight and 12-nylon 3
While adding 6 parts by weight of benzenesulfonic acid butylamide to 0 parts by weight of the mixed pellet in the extruder hopper, the extruder (
Melt-mix pelletization was performed at 230° C. using a pelletizing device consisting of a die, a cooling water tank, and a cutter. The pellet forming process went smoothly, and the thickness of the strand discharged from the goo was uniform in the flow direction.

Using this pellet, extruder (40 φ, L/D=2
8) A film having a thickness of 50 μm was prepared at an extrusion temperature of 230° C. using a film forming machine consisting of a T-die and a take-off machine. Film production was smooth with no thickness variation or gel formation. The oxygen permeability of this film was measured using Modern Control OXTRAN 1G/50A.
When measured at 20°C and 65%RH, it was 2.5cc・2
It was 0 μ/1 day-aLg+.

The oxygen permeability of the 12-nylon film used was 7800 cc·20μ/1·day-at*.

Comparative example l Ethylene content 32.0 mol%, saponification degree 99.6 mol%
, Ml (190°C, under 2160g load) lJg/10 min A tumbler mixed pellet of 70ii parts of EvOH pellets and 30 parts by weight of 12-nylon pellets was pelletized using the same equipment as in Example 1 at an extrusion temperature of 230°C. Ta.

The thickness of the strand taken from the goo fluctuated in the flow direction, resulting in frequent strand breakage and difficulty in making it continuous. Using this pellet, 50μ
- When we created a film, it was possible to continuously form the film, but gel was observed in the film obtained.
In addition, there was a thickness variation in the flow direction, and the product had no commercial value.

Example 2 Ethylene content 44.5 mol%, saponification degree 99.5 mol%
, Ml (190℃, under 2160g load) 5.5g/
10 minutes (7) EVOH 50 parts by weight, 6/12 copolymerized nylon (copolymerization ratio 6/12 = 90/1G) 501
While adding 4 parts by weight of 2-ethylhexyl roseoxybenzoate to the tumbler-mixed pellets using the extruder hopper, pelletization was carried out using the same equipment and under the same conditions as in Example 1.

Pellet molding went smoothly, and the thickness of the strands discharged from the goo was uniform in the flow direction. Using this pellet, a film was formed using the same apparatus and under the same conditions as in Example 1.

Film production was smooth with no thickness variation or gel formation. When the oxygen permeability was measured in the same manner as in Example 1,
It was 18.6cc・20u/ta″・day-atm.

The oxygen permeability of the 6/12 copolymerized nylon film used was 240 cc.20 μ/1.day-at-.

Example 3 Ethylene content 47.5 mol%, saponification degree 99.6 mol%
, Ml (190° C., under a load of 2160 g) for 14 g/10 minutes, tumbler mixed pellets containing 80 parts by weight of EvOH, 20 parts by weight of 6-nylon, and 25 parts by weight of ethylene-propylene copolymer rubber were mixed in the same apparatus as in Example 1. 2 5
Pelletization was performed at 0'C. Pellet molding went smoothly, and the thickness of the strands discharged from the die was uniform in the flow direction. Using this pellet, a 50 μm film was produced using the same film forming machine as in Example 1 at an extrusion temperature of 250°C. The film was in good condition with almost no discoloration, no thickness variation, and no gel formation. The oxygen permeability of the obtained film was 7.3cc・20μ/1lday●a
It was ti.

The oxygen permeability of the 6-nylon single film used was 130 cc·20 μ/Im″·day-atm.

Comparative Example 2 Pelletization was performed from Example 3 except that the ethylene-propylene copolymer rubber was removed. Although the strands were yellowing, there were no uneven thicknesses in the machine direction, and the collection was smooth. When this pellet was used to form a 50 μm film using the same apparatus as in Example 1, yellowing further progressed and gel was observed.

Example 4 12-nylon 60, a ring-opened polymer of ω-laurolactam
Parts by weight, ethylene content 32.0 mol%, saponification degree 99.
6 mol%, Ml (190°C, 2160g load measurement) 1
．． While adding 6 parts by weight of benzenesulfonic acid butylamide to the mixed pellets of 3 g/10 minutes of EVOH40 weight ratio from the extruder hopper, the extruder (40 same φ, L/D=
28), the mixture was melted and mixed into a bed at 230° C. using a pelletizing device consisting of a die, a cooling water tank, and a take-off cutter. The pellet forming process went well, and the thickness of the strands discharged from the gun was uniform in the flow direction. Using this pellet, extrusion temperature 2
A film with a thickness of 300 μm was produced at 30°C. Film production was smooth with no thickness variation or gel formation.

Using this film and as a control, butyl rubber with a thickness of 300μ and NBR with a thickness of 860μ, the ASTM Dl
Nitrogen gas permeability at 35°C (c
c・20g/1・day-atm) s Freon 12 gas permeability at 70°C (cc・20μ/1・d
This film was then molded into a predetermined shape using a vacuum thermoforming machine, and unvulcanized butyl rubber excipients were laminated on both sides of the film, which was then vulcanized at 150°C for 4 hours to cause swelling. Diaphragm for tanks (average total thickness 1.
0ms, and the average thickness of the intermediate layer film was 75μ. The obtained diaphragm has almost the same flexibility as a diaphragm made of butyl rubber alone, and its gas permeability has also been improved to about 176.

Example 5 Using pellets with the same composition as in Example 4, an extruder (40
φ, L/D=26), melted and mixed at 230℃ using a tube forming machine consisting of a circular goo, a sizing device, a cooling device, and a take-off device to obtain an outer diameter of 12.5 φ and a wall thickness of 500μ. - created a tube. Tube preparation went smoothly without any variation in thickness, and no gel was generated. A braid-reinforced NBR layer was formed on the outer layer of this tube, and the tube was vulcanized by steam heating to produce a Freon hose with a total wall thickness of 5.0 mm. No melt denaturation was observed in the inner tube layer. The hose also had almost the same flexibility as a hose without a tube. Next, according to ASTM D 188G, lOO℃
When comparing the permeation amount of Freon-12 gas over 72 hours, the permeation amount of the tube-equipped hose was 1/12 that of the hose without the tube.

Example 6 12-nylon 40, a ring-opened polymer of ω-laurolactam
Parts by weight, ethylene content 44.2 mol%, saponification degree 99.
5 mol%, Ml (190°C, 2160g load measurement) 5
．． A tumbler-mixed pellet containing 60 parts by weight of 5 g, 710 minutes of EVOH and 30 parts by weight of ethylene-propylene copolymer rubber was melt-blended into pellets at 220° C. using the same pelletizing apparatus as in Example M4. The molding process was smooth, and the thickness of the strands discharged from the die was uniform in the flow direction. Using the pellets, a film having a thickness of 50 μm was produced using the same film forming machine as in Example 4 at an extrusion temperature of 220° C. The film production was smooth with no thickness variation or gel formation. The gas permeability of the obtained film was excellent as shown below.

Example 7 60 parts by weight of 11-nylon condensation polymer of ω-aminoundecanoic acid and 2-ethylhexyl paraoxybenzoate lO
Parts by weight of melt-mixed pellets, ethylene content 32.0 mol%, saponification degree 99.6 mol%, MI (190°C, 216 mol%
0g load measurement) EvOH pellets for IJg/tG 4
0 parts by weight of the tumbler mixture was melt-mixed and pelletized at 220° C. using the same pelletizing apparatus as in Example 4. Strand formation went smoothly, and the thickness of the strand discharged from the goo was uniform in the flow direction. Using these pellets, a film having a thickness of 50 μm was produced using the same film molding machine as in Example 4 at an extrusion temperature of 220° C. Film production went smoothly without any thickness variation or gel formation. The gas permeability of the obtained film was as follows.

Comparative Example 3 Condensation polymer of ω-aminoundecanoic acid with 11-nylon 60% by weight, ethylene content 32.0 mol%, saponification degree 9
9.6 mol%, Ml (190°C, 2160g load measurement)
The tumbler mixed pellets of 1.3 g/to of EVOH40 were heated at 220°C using the same pelletizing device as in Example 4.
When melt-mixing pelletization was performed, the thickness of the strands discharged from the goo fluctuated in the flow direction, resulting in frequent breakage of the strands, making it difficult to make them continuous. Using this pellet, using the same film molding machine as in Example 4,
When we tried to make a film with a thickness of 50ul at an extrusion temperature of 220°C, it was possible to make the film continuously, but the resulting film had thick spots and gel was observed.
It had no commercial value.

Comparative Example 4 Using the same film forming machine as in Example 4,
2-Produce a film using nylon alone to a thickness of 300 μm
I got this film. The gas permeability of this film was low as shown in the table below.

Comparative Example 5 Using the same film forming machine as in Example 4,
A single film was formed using VOH, and a film with a thickness of 300 μι was obtained. I got r rum. The film production went smoothly, and a gel-free film of uniform thickness was obtained. Although this film had excellent gas barrier properties as shown below, it was expected to be extremely hard and impair the flexibility of the rubber. When unvulcanized NBR with a thickness of 1 mm was pasted on both sides of this film and steam vulcanization was performed, it was U raw! The resin composition of the present invention has excellent melt-shaping properties, excellent gas barrier properties, and excellent high-temperature, moist-heat resistance.Furthermore, the resin composition of the present invention has excellent melt-shaping properties, excellent gas barrier properties, and excellent high-temperature, moist-heat resistance. The material is flexible and is particularly good for laminating with rubber to improve the gas barrier properties of rubber.

Claims (6)

[Claims] (1) A resin composition comprising at least one selected from (A) a polyamide resin, (B) an ethylene-vinyl alcohol copolymer, and (C) an aromatic acid amide, an aromatic acid ester, and an olefin elastomer. (2) (A)/(B) = 95/5 to 5/95 (weight ratio)
So, ((A)+(B))/(C)=100/2~100
/40 (weight ratio). (3) (A) at least one selected from 11-nylon and 12-nylon, (B) ethylene-vinyl alcohol copolymer, (C) aromatic acid amide, aromatic acid ester, and olefin elastomer A resin composition comprising at least one species. (4) (A)/(B) = 95/5 to 5/95 (weight ratio)
So, ((A)+(B))/(C)=100/2~100
4. The resin composition according to claim 3, which has a molecular weight of /40. (5) A multilayer structure having at least one layer made of the resin composition according to any one of claims 1 to 4. (6) A multilayer structure comprising at least two layers: a layer comprising the resin composition according to claim 3 or 4 and a rubber layer.