JPH0476040A - Resin composition - Google Patents

Abstract

PURPOSE:To improve stretching properties, gas barrier properties, and resistance to hot water, oil and impact by mixing a specified ethylene-vinyl alcohol copolymer with a specific aliph. copolyamide. CONSTITUTION:A polyamide having an m.p. of 120-200 deg.C and obtd. by copolymerizing 25-80wt.% caproamide with 75-20wt.% at least two aliph. polyamides at random is allowed to react with an agent for modifying terminal group contents (e.g. acetic acid) to give an aliph. copolyamide having a relative viscosity (JIS K6810, in 98% sulfuric acid, in 1% concn., and at 25 deg.C) of 1.7-4.0 and contents of terminal carboxyl group [X] and terminal amino group [Y] satisfying the formula (wherein the unit of [X] and [Y] is mol/g-polymer). 40-5wt.% said copolyamide is mixed with 60-95wt.% saponified ethylene-vinyl alcohol copolymer having an ethylene content of 25-60mol% and a degree of saponification of 90mol% or higher.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to a saponified ethylene-vinyl alcohol copolymer and a specific aliphatic copolymer polyamide that have stretchability, gas barrier properties, hot water resistance, oil resistance and The present invention relates to a resin composition that has excellent impact resistance and is particularly suitable for continuous molding of packaging materials.

[Conventional technology]

Saponified ethylene-vinyl alcohol copolymer (hereinafter referred to as E
VOH (abbreviated as VOH) has extremely low oxygen gas permeability, excellent oil resistance, and transparent molded products can be easily obtained by ordinary melt molding processing methods, so it is used for films, sheets, tubes, plastic containers, etc. Useful as packaging material. However, on the other hand, EV OH has disadvantages such as high moisture permeability due to its hydrophilic properties, lack of hot water resistance, hardness and brittleness, low impact strength, and extremely poor stretchability, so its use has not been expanded. Limited. As one of the means to improve the above-mentioned drawbacks of conventional EVOH, a method of mixing polyamide with EVOH (Japanese Patent Publication No. 44
24277, JP 48-22833, JP 50-121347, JP 60-24813, JP 60-24814, JP 64-9238.
Public bulletin) has been proposed. According to this method, the disadvantages of EVOH such as lack of hot water resistance, hardness and brittleness with low impact strength, and extremely poor stretchability can be improved.

[Problem to be solved by the invention]

However, although the compositions made of EVOH and polyamide used in these materials exhibit many desirable properties as packaging materials and molded articles with high commercial value can be obtained, they actually have serious drawbacks. The reason is that when EVOH and polyamide are mixed in a molten state, a chemical reaction occurs between the two, and as a result, the viscosity of the mixed composition increases, resulting in a gel with intense coloration. That is, because of this disadvantageous phenomenon, compositions made of EVOH and polyamide are difficult to be continuously molded and cannot be applied to continuous manufacturing processes for practical products such as films, sheets, and tubes. Although the mixture of EVOH and polyamide has extremely excellent characteristics as described above, at present it has not been put into practical use due to some fatal flaws.

Therefore, the present inventors conducted intensive studies to obtain a resin composition that maintains the EVOH improvement effect of polyamide and does not exhibit the increase in viscosity when melted as shown by mixed compositions of EVOH and polyamide. It has been found that the above object can be achieved when a specific aliphatic copolymerized polyamide is selected as the polyamide for the purpose of the present invention, and the present invention has been achieved.

[Means to solve the problem]

The present invention relates to an ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 60 mol% (tJI 60 to 95% by weight) and a polyamide of 5 to 40% by weight, and in which the polyamide is caproamide and at least two different aliphatic The melting point obtained by randomly copolymerizing polyamide is 12
The resin composition is characterized in that the temperature is in the range of 0 to 200°C, and the terminal carboxyl group content [X] and terminal amino group content [Y] satisfy the following formula (I).

[Y]<[X]+0.5xlO-'...(I)
(However, the units of [X] and [Y] are 11 ol/g of polymer) The EVOH used in the present invention has an ethylene content of 25 to 60 mol%, preferably 25 to 55 mol%, more preferably 25 to 50 mol%. Although the degree of saponification of vinyl acetate in terms of mol% is not particularly limited, it is a saponified ethylene-vinyl alcohol copolymer of 90 mol% or more, preferably 95 mol% or more.

When the ethylene content is less than 25 mol%, the molding temperature becomes close to the decomposition temperature, making molding difficult. On the other hand, when the ethylene content is 60 mol% or more, extrudability is good but gas barrier properties are poor. Further, EV'OH having a degree of saponification of less than 90% is undesirable since it can produce containers with fewer cracks and pinholes during molding, but has insufficient dimensional stability and gas barrier properties.

In the polyamide used in the present invention, the amount of caproamide units in the copolymer must be 25 to 80% by weight, preferably 25 to 75% by weight, and more preferably 30 to 75% by weight. Copolyamides containing less than 25% by weight of caproamide units have little effect on improving the stretchability, hot water resistance, impact resistance, etc. of EVOH;
If it exceeds 0% by weight, the melt-molding processing temperature of the mixed composition of EVOH and polyamide becomes high, which makes continuous molding difficult due to generation of gelled products and coloring, which is not preferable. The two different aliphatic polyamides used in the present invention are those produced by polycondensation reactions of aminocarboxylic acids or lactams having 6 to 12 carbon atoms, dibasic acids having 6 to 12 carbon atoms, and diamines having 4 to 10 carbon atoms. It refers to polyamide produced by polycondensation reaction, and nylon 6 is excluded here.

The content of the aliphatic polyamide is 20 to 75% by weight, preferably 25 to 75% by weight, more preferably 25 to 75% by weight.
It is 70% by weight. The composition ratio of the polyamide used in the present invention is not particularly limited, but in order to add hot water resistance, the total copolymer should contain a component having 10 or more carbon atoms in an amount of 2% by weight or more, preferably 5% by weight or more. is preferred.

Examples of the ternary copolymer polyamide used in the present invention include nylon 6, nylon 66, nylon 11, and nylon 1.
Examples include a terpolymer consisting of two types selected from 2 and nylon 610. Especially nylon 6, 66, 12,
Nylon 6, 66, 610, nylon 6, 610, 12
The ternary copolymerized nylon is preferred in the present invention. By using ternary copolymerization, the polyamide used in the present invention maintains the oil resistance, stretchability, toughness, cold resistance, etc. possessed by polyamide, has excellent hot water resistance, and exhibits increased viscosity during melt molding. It has excellent flexibility and effectively exhibits its effects as a low cost. Quaternary copolymerization is not preferred because of poor hot water resistance. However, a small amount of other quaternary or more components may be copolymerized or other polyamide components may be blended to the extent that the effect is not impaired.

Of course, two or more types of terpolymers used in the present invention may be blended.

The melting point of the polyamide used in the present invention is 120 to 200°C, preferably 125 to 190°C, more preferably 1
The temperature is 30-185°C. If the melting point is less than 120''C, the extrudability is good, but the hot water resistance is poor, which is not preferable.

On the other hand, if it is 200° C. or higher, the processing temperature is too high, and coloring and gelation occur during melt molding, making continuous molding difficult, which is not preferable.

do not have.

The polyamide used in the present invention has carboxyl groups and amino groups as terminal groups, and the amounts of each of the terminal carboxyl groups and amino groups must satisfy the formula (I). That is, in polyamides obtained by polymerizing lactams, aminocarboxylic acids, dibasic acids, and diamines, the content of terminal carboxyl groups in the molecule is adjusted to be greater than the content of terminal amino groups; Group content [X] (mol/g polymer) and amino group content [
Y] (mol/g・polymer) and the formula Y<X+0
．． 5X10-5, preferably Y≦X + 0.7 X
It is necessary that the relational expression 10-5 holds true. And, desirably, the absolute value of the amino-based material [Y] (mol/g polymer) is 7X 10-5 mol/g polymer or less, preferably 5 x 10-5 mol/g polymer or less, more preferably, 4 XIO-5mol/g
- Polymer or lower is more suitable. If there are too many terminal amino groups, there will be no effect of improving continuous film formation, which is not preferable. On the other hand, although having a small number of terminal amino groups is preferable from a usage standpoint, it poses difficulties in resin production.
It is a good idea to keep it to a level where it becomes a polymer. Although not particularly specified, the carboxyl group content [
10XIO as the absolute value of X] (mol/g polymer)
-'mol/g + polymer or less, preferably 7X 1
It is preferably 0-5 mol/g of polymer or less, more preferably 5 x 10-' mol/g of polymer.

The above-mentioned terminal group amount adjusting agent is not particularly specified, but
Usually, a carboxylic acid having 2 to 23 carbon atoms or a diamine having 2 to 20 carbon atoms is used. Specifically, carboxylic acids having 2 to 23 carbon atoms include fatty acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, undecanoic acid, lauric acid, stearic acid, and oleic acid. Group monocarboxylic acids, alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid, aromatic monocarboxylic acids such as benzoic acid, ethylbenzoic acid, and phenylacetic acid, carbon atoms 2 to 20
The diamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine,
dodecamethylene diamine, tridecamethylene diamine,
Examples include aliphatic diamines such as hexadecamethylene diamine and octadecamethylene diamine, alicyclic diamines such as cyclohexane diamine and methylcyclohexane diamine, and aromatic diamines such as xylene diamine. In addition to the above monocarboxylic acids, aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutamic acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, undecadionic acid, and dodecanedioic acid; Dicarboxylic acids such as alicyclic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid can also be used or used in combination. The amount of terminal regulator used is not particularly limited, but usually the amount of carboxyl group is 0.1 to 18 (meq, / mol) more than the amount of amino group.
, preferably 0.2-18 (meq, / mol)
, more preferably 0.2 to 15 (meq, / mo
l) Use in excess. The amount of terminal regulator used is 0.1 (m
If the amount is less than 15 (meq, /' mol), no improvement in continuous film forming property will be observed, and if it is more than 15 (meq, /' mol), the degree of polymerization will increase slowly, which is unfavorable for production.

The degree of polymerization of the polyamide used here is not particularly limited, but the relative viscosity measured at 25°C at a concentration of 1% in 98% sulfuric acid according to JIS K6810 is 1.7 to 4.
0, preferably 2.0 to 4.0, more preferably 2
．． A range of 0 to 3.5 is selected. The method of polymerizing the copolyamide used in the present invention is not particularly limited, and melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid phase polymerization, and a combination of these methods can be used. Usually, melt polymerization is preferably used.

The amount of polyamide added to EVOH is 5-40% by weight, preferably 7-30% by weight, more preferably 7-40% by weight.
It is 25% by weight. If the amount added is less than 5% by weight, the effect of improving moldability is not sufficient, and cranks and unevenness are likely to occur.

On the other hand, if it exceeds 40% by weight, the gas barrier properties will be greatly reduced, making it unusable as a gas barrier container. The method of blending EVOH and polyamide is not particularly limited, but includes a method of tri-blending EVOH and polyamide and pelletizing and drying the mixture using a single-screw or twin-screw extruder with sufficient kneading power. The composition of the present invention is mainly used for packaging materials such as films, sheets, tubes, and plastic containers, but it may of course be used for other purposes as well. When molding the composition of the present invention, ordinary extrusion molding, blow molding, injection molding, etc. can be applied. For example, to produce a single film from the composition of the invention,
Usually, it is first extruded in a molten state from the T-Gui head of an extruder, and then cooled and solidified on a casting drum using a known casting method, typically an air knife casting method, an electrostatic application method, a vacuum chamber method, etc. Obtain an unstretched film. Next, this unstretched film is stretched by a small amount (both in one direction. Normally, sequential biaxial stretching in the order of longitudinal stretching → lateral stretching is preferably used in terms of productivity. Of course, unstretched and simultaneous biaxial stretching are also possible. It has very good stretchability.In addition, it is preferable to perform heat treatment after stretching in order to maintain dimensional stability and hot water resistance, and tension heat treatment or relaxation heat treatment is effective. The packaging material made of polyamide used has oil resistance, transparency,
It has excellent gas barrier properties and impact resistance, especially hot water resistance, and has high utility value when used alone, but it is possible to add even more film properties by laminating other thermoplastic resins thereon. The film properties of such laminated films vary depending on the type of thermoplastic resin laminated. For example, laminating polyolefin resin can significantly reduce water and vapor permeability, and laminating polyester can significantly improve heat resistance and allow high-temperature resistance. It can withstand retort processing. In the case of these laminated films as well, it is preferable to stretch them under appropriate conditions to take advantage of their good stretchability. In addition to the same advantages as the above-mentioned film, the sheet formed from the composition of the present invention has the advantage that the sheet has excellent deep drawability.1. When a tube or a hollow molded product (container) is molded by blow molding, biaxial stretch blow molding is possible, and the advantage is that the molded product has excellent dimensional stability and creep resistance. In addition, when molding a sheet or a blow-molded product, other thermoplastic resins can be laminated as in the case of the above-mentioned film.

Note that the composition of the present invention may contain other components such as a heat stabilizer, a crystal nucleating agent,
Antioxidants, lubricants, fillers, plasticizers, etc. can be added.

The present invention will be explained in further detail by giving examples below. In addition,
Each evaluation was measured according to the method described below.

(I) Oxygen permeable film was heated to 0XY-T at 20°C and 1100% RH.
It was measured using R8he 100 (manufactured by Modern Controls). Unit is per sheet: cc/rd
・Per 24hr and thickness 0.1mm: cc/m
・24hr 10.1mm.

(2) Boiling test A film (I00 μm thick) was boiled (held in boiling water for 30 minutes) and then taken out and changes in the film were observed.

The evaluation was as follows: No change before and after treatment: ○; Film edges partially melted or poor flatness: Δ; Film melted: ×.

(3) The state of the stretchable film was observed. Evaluation is uniformly stretched,
Good transparency: ○; Slightly uneven stretching: △; Film tearing or uneven stretching occurred during stretching, resulting in poor stretching.

(4) Melt-extrude the composition with thickening gel properties from an extruder to continuously obtain 200μ
An unstretched film was produced, and after the start of film formation, the time until countless gelled substances appeared on the film surface and film formation became impossible was measured.

Note that parts and percentages in the examples indicate parts by weight and percentages by weight, respectively.

(5) Measurement of terminal group amount Carboxyl groups were measured by dissolving polyamide in benzyl alcohol and titrating with 0.05N potassium hydroxide. Amino groups can be obtained by dissolving polyamide in phenol and adding 0.0
It was measured by titration with 5N-hydrochloric acid.

Examples 1 to 8 For EV OH having an ethylene content of 33%, a degree of saponification of 99%, and a melting point of 170°C, terminal regulators (benzoic acid, stearic acid, leicic acid, hexamethylene) were added to polyamides A to C shown below. Table 1 shows the evaluation results obtained by adding diamine) in the amounts shown in Table 1.

Polyamide A (nylon 6/66/12)...ε-
A copolymer polyamide obtained by melt polymerizing caprolactam, equimolar salts of hexamethylene diamine and adipic acid, and aminododecanoic acid.

Polyamide B (nylon 6/66/610)...ε
- A copolymerized polyamide obtained by melt polymerizing caprolactam, an equimolar salt of hexamethylene diamine and adipic acid, and an equimolar salt of hexamethylene diamine and sebacic acid.

Polyamide C (nylon 6/610/12)...
A copolymer polyamide obtained by melt polymerizing ε-caprolactam, an equimolar salt of hexamethylene diamine and sebacic acid, and aminododecanoic acid.

From Table 1, it can be seen that each composition did not generate gelled substances in the film even after continuous molding for 20 hours or more, and the film had excellent flatness and transparency, and had good stretchability and gas barrier properties.

Comparative Example 1 The polyamide of Example to which no terminal regulator was added was evaluated, and the results are shown in Table 2. Although satisfactory performance was obtained to some extent, no improvement in continuous film formation was observed compared to the case in which an end regulator was added.

Comparative Example 2 0.05 (meq/
The samples to which molybdenum was added were also evaluated in the same manner, and the results are shown in Table 2. Similar to the case in which no terminal regulator was added, no improvement in continuous film formation was observed.

Comparative Example 3 The polyamide of Example to which 9 (meq/mol) of hexamethylene diamine was added as an end regulator was evaluated in the same manner, and the results are shown in Table 2. Although the performance was satisfactory to some extent, the effect of improving continuous film-forming property was not observed as with those with a large amount of carboxyl groups.

Comparative Examples 4 to 8 The polyamides of Examples whose blending amount in EV OH is outside the scope of the present invention and those whose copolymerization amount of caproamide units are outside the scope of the present invention were evaluated in the same manner, and the results were evaluated. Shown in Table 2. The unstretched film with a large amount of nylon (Comparative Example 4) had inadequate gas barrier properties, and the film with a small amount of nylon (Comparative Example 5) had inadequate stretchability. High melting point (Comparative Examples 6 and 7)
After 7 hours from the start of film formation, a gelled substance was generated on the film, making it impossible to form a film. Furthermore, in Comparative Example 7, the stretchability was also inadequate. The one with a low melting point (Comparative Example 8) had inadequate hot water resistance and oxygen permeability.

(Blank below next summer) [Effects of the invention] The resin composition of the present invention has excellent gas barrier properties, stretchability,
It is a resin that suppresses gelation during continuous molding and is relatively inexpensive. Here, the excellent gelation suppressing effect is thought to be due to the low melting point of the polyamide used in the present invention, which allows the molding temperature to be lower than usual, and also because the terminal reactivity is suppressed by the terminal regulator.

Claims (1)

[Scope of Claims] Consisting of 60 to 95% by weight of a saponified ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 60 mol% and 5 to 40% by weight of polyamide, and the polyamide is different from caproamide by at least two types. It is obtained by randomly copolymerizing aliphatic polyamide and has a melting point in the range of 120 to 200°C, and further has a terminal carboxyl group content [
A resin composition characterized in that the terminal amino group content [Y] and the terminal amino group content [Y] satisfy the following formula (I). [Y]<[X]+0.5×10^-^5...(I) (However, the units of [X] and [Y] are mol/g polymer.)