JPH11140243A - Ethylene copolymer composition, antistatic agent and thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of not only improving surface characteristics but also improving antistatic performances and providing a molded product having transparency and high antistatic performances such as a film by compounding a specific organic carboxylic acid therein. SOLUTION: This composition comprises (A) an ethylene-unsaturated carboxylic acid copolymer, (B) alkanolamines and (C) an organic carboxylic acid having 2-7 acid equilibrium constant (pKa) and carboxyl groups. The component B is preferably compounded in an amount so as to provide 0.01-1 equiv. for carboxyl groups in the component A and 0.01-2 molar ratio of the carboxyl groups in the component C to amino groups in the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-chargeable ethylene copolymer composition having low humidity dependence and an antistatic agent comprising the composition. The present invention also relates to a thermoplastic resin composition provided with an antistatic property by blending such an antistatic agent.

[0002]

2. Description of the Related Art In electronic precision parts such as ICs, utmost care is taken to prevent static electricity during work, and naturally, the generation of static electricity during packaging and transport also adversely affects products. For this reason, it is necessary to prevent this, and accordingly, materials for packaging and transporting these components, typically films, etc., are also strongly required to have antistatic properties.

[0003] Various antistatic materials have been proposed to meet such demands, but no satisfactory antistatic materials have yet been obtained. For example, a resin molded product containing conductive carbon black shows good conductivity, but the molded product itself becomes opaque, and carbon black particles peel off due to vibration or impact during transportation, contaminating electronic precision components. There is a disadvantage that.

[0004] Further, in the case of a molded article of a resin composition containing an antistatic agent or a molded article coated with an antistatic agent on the surface, the antistatic agent distributed on the surface of the resin molded article absorbs moisture. It is thought to exert its effect, and thus temporarily exhibits a low surface resistivity of about 10 ⁶ to 10 ¹⁰ Ω under high humidity and shows good conductivity, but does not adsorb moisture under low humidity. Since it is sufficient, it does not show a sufficient antistatic effect. In addition, when the surface of the resin molded product is washed with water, its surface resistivity becomes about 10 ¹⁴ to 10 ^15, and it has a drawback that it not only becomes substantially an insulator but also has no sustained antistatic performance. ing.

Further, the fact that an ionomer obtained by highly neutralizing an ethylene / unsaturated carboxylic acid copolymer with an alkali metal such as potassium or sodium has antistatic properties is disclosed in, for example, JP-A-60-240704. Are known. However, such ionomers also have a problem of insufficient surface resistivity under low humidity, and have not always been satisfactory.

[0006] An ionomer composition obtained by reacting an alkanolamine with an ethylene / unsaturated carboxylic acid copolymer, which does not have such a drawback, has been proposed in Japanese Patent Publication No. 1-24406. In this proposal, it has been clarified that the composition has solved the above-mentioned various problems, specifically, transparency, low humidity dependency, having excellent performance in terms of conductivity persistence and the like. It is shown. However, even such a composition has a problem that the surface is whitened due to bleeding of the alkanolamine compound and reaction with carbon dioxide in the atmosphere.

[0007]

The inventors of the present invention have conducted intensive studies to eliminate such disadvantages and achieve desired antistatic properties and good surface properties. As a result, the above-mentioned ethylene / unsaturated carboxylic acid copolymer was obtained. It has been found that by blending a specific organic carboxylic acid with a system composed of a compound comprising alkanolamines and alkanolamines, it is possible to improve not only the surface properties but also the antistatic performance. That is, a molded article such as a film molded from such a resin composition has transparency, high antistatic property and its durability,
Not only does the antistatic performance exhibit low humidity dependency, but it also exhibits highly reliable antistatic performance in which bleeding of the amine compound onto the surface and whitening due to carbon dioxide gas are suppressed.

[0008]

The present invention relates to an ethylene-unsaturated carboxylic acid copolymer (A), an alkanolamine (B) and an organic carboxylic acid having a carboxyl group having an acid equilibrium constant (pKa) of 2 to 7. The present invention relates to an ethylene copolymer composition comprising an acid (C). The present invention also relates to an antistatic agent comprising such an ethylene copolymer composition. The present invention further relates to a thermoplastic resin composition obtained by blending the above ethylene copolymer composition with another polymer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Action] The present invention relates to an organic carboxylic acid having an alkanolamine (B) and an acid equilibrium constant (pKa) in a specific range, in an ethylene / unsaturated carboxylic acid copolymer (A). This is characterized in that (C) is mixed in combination, whereby the antistatic property under low humidity conditions can be significantly improved.

It is known that the composition of the ethylene / unsaturated carboxylic acid copolymer (A) and the alkanolamines (B) exhibits antistatic properties, as mentioned above in the prior art. According to the present invention, by further blending a specific organic carboxylic acid (C), 23 ° C./5
The surface resistance under low humidity of 0% RH can be suppressed to a value lower by one order or more (see Table 1 in Examples described later).

In addition, in the composition of the ethylene / unsaturated carboxylic acid copolymer (A) and the alkanolamine (B), stickiness due to bleeding of the alkanolamine (B) on the surface and whitening of the surface are caused. However, according to the present invention, all of these problems could be eliminated by using the specific organic carboxylic acid (C) in combination (described later). See Table 3 for examples that do).

The ethylene copolymer composition of the present invention not only exhibits excellent antistatic properties per se, but also a molded article such as a film molded from a resin composition containing the same,
Not only shows transparency, high antistatic properties and its durability, low humidity dependency of antistatic performance, but also has the advantage that bleeding of amine compounds on the surface and whitening by carbon dioxide gas are suppressed. It is.

[Ethylene Copolymer] The ethylene / unsaturated carboxylic acid copolymer (A) used in the present invention is not limited to a narrowly defined copolymer consisting only of ethylene and unsaturated carboxylic acid, and may optionally contain other copolymers. May be a multi-component copolymer obtained by copolymerization of the above components. Further, an ionomer partially neutralized with metal ions may be used.

Here, unsaturated carboxylic acids include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monoethyl maleate,
Maleic anhydride, itaconic anhydride and the like can be exemplified as typical examples. Of these, acrylic acid or methacrylic acid is most preferred.

The optional copolymerization components include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, isobutyl methacrylate, dimethyl maleate, and maleic acid. Examples thereof include unsaturated carboxylic acid esters such as diethyl acid, vinyl esters such as vinyl acetate and vinyl propionate, and carbon monoxide.

The polymerization composition of the ethylene / unsaturated carboxylic acid copolymer preferably has an unsaturated carboxylic acid content of 2 to 30% by weight, particularly 5 to 25% by weight. % By weight, especially in the range of 0 to 30% by weight. That is, if the content of the unsaturated carboxylic acid is too small, it is difficult to obtain a composition having good performance, and if the content is too large, the resin becomes brittle and the field of use is limited.

The ethylene copolymer (A) has a melt flow rate at 190 ° C. and a load of 2160 g of 0.1 to 1500 g / 10 min, especially 1 to 1500 g / 10 min.
It is preferable to use one with 500 g / 10 min. When a material having a very low mettle flow rate is used, a high temperature is required when melt-blending with an alkanolamine, which may cause thermal degradation and undesired side reactions. If the melt flow rate is too high,
This is because it is difficult to obtain a formed product having excellent mechanical strength and the like.

These ethylene copolymers can be obtained by high-pressure radical copolymerization of the above monomers.

As the ethylene copolymer (A), a copolymer in which a part of the carboxyl group is neutralized with a monovalent metal such as lithium, sodium and potassium and a polyvalent metal such as magnesium, calcium and zinc is used. Can be used. These may have a degree of neutralization of, for example, about 50% or less. However, in general, if partially neutralized with metal ions, the melt viscosity increases, and the above-mentioned problems occur. In this case, it is generally preferable to use a low ionized product.

[Alkanolamines] The alkanolamines (B) used in the present invention are compounds having at least one substituted or unsubstituted alkanol group directly bonded to a nitrogen atom. As a typical example,
Formula _{R (3-n) N (} R 1 OH) n or R _(3-n) N [(R ₂ O)
_m H] _n (R is a hydrogen atom, a substituted or unsubstituted alkyl group,
Each of R ₁ and R ₂ is a substituted or unsubstituted alkylene group, n is an integer of 1 to 3, and m is an integer, for example, 1 to
It is an integer of about 10, and when there are a plurality of groups, each may be the same or different. ) Can be mentioned.

More specifically, monoethanolamine,
Diethanolamine, triethanolamine, mono (isopropanol) amine, di (isopropanol) amine, tri (isopropanol) amine, N-methyldiethanolamine, N-ethyldiethanolamine, N,
N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine, aminoethylethanolamine, 3-amino-1,2-propanediol, di (polyoxyethylene) laurylamine, di (poly) Oxyethylene) stearylamine, di (polyoxyethylene) oleylamine and the like can be given as typical examples. Among them, low-molecular-weight alkanolamines such as diethanolamine, triethanolamine and methyldiethanolamine are most preferable from the viewpoint of compatibility with the ethylene copolymer (A) and thermal stability.

An appropriate amount of the alkanolamines (B) is 0.01 to 0.01% in terms of amino groups / carboxyl groups (molar ratio) based on the total carboxyl groups of the ethylene copolymer (A).
It is preferable to select so as to fall within a range of １1, especially 0.1 to 0.9. That is, if the amount of the component (B) is too small, sufficient antistatic performance cannot be obtained, and if the component (B) is used excessively, problems such as bleeding and whitening tend to occur. It is considered that at least a part of such alkanolamines (B) reacts with a carboxyl group of the ethylene copolymer (A) to form an ammonium salt and form an ionomer.

[Organic Carboxylic Acid] In the present invention, an organic carboxylic acid having a carboxyl group having an acid equilibrium constant (pKa) of 2 to 7, preferably 3 to 6, in addition to the above components (A) and (B). C) is used. When there are a plurality of acid equilibrium constants, the smallest one is within the above range.

More specifically, formic acid (pKa: 3.5)
5), acetic acid (pKa: 4.56), propionic acid (pK
a: 4.67), butanoic acid (pKa: 4.63), pen
Formic acid (pKa: 4.68), hexanoic acid (pKa:
4.63), heptanoic acid (pKa: 4.66), palmi
Formic acid (pKa: 4.64), stearic acid (pKa:
4.69), an aliphatic monocarboxylic acid such as succinic acid (p
Ka₁: 4.00, pKa _Two: 5.24), glutaric acid
(PKa₁: 4.13, pKa_Two: 5.03), adipi
Acid (pKa₁: 4.26, pKa_Two: 5.03),
Meric acid (pKa₁: 4.31, pKa_Two: 5.0
8), suberic acid (pKa₁: 4.35, pKa _Two:
5.10), azelaic acid (pKa₁: 4.39, pK
a_Two: 5.12), malic acid (pKa₁: 3.24, p
Ka_Two: 4.71), terephthalic acid (pKa) ₁: 3.5
4, pKa_Two: 4.46) or an aliphatic or aromatic di.
Carboxylic acid, crotonic acid (pKa: 4.69), acrylic
Phosphoric acid (pKa: 4.26), methacrylic acid (pKa:
4.66) and unsaturated carboxylic acids such as anisic acid (pK
a: 4.09), m-aminobenzoic acid (pKa₁: 3.
12, pKa_Two: 4.74), m-, p-chlorobenzoic acid
Acid (pKa₁: 3.82, pKa_Two: 3.99), Hide
Roxybenzoic acid (pKa₁: 4.08, pKa_Two: 9.
96) and the like, citric acid (pKa₁: 2.
87, pKa_Two: 4,35, pKa_Three5.69)
Polycarboxylic acids and derivatives thereof can be mentioned.
Rosins can also be used.

In place of the above organic carboxylic acids, those having an acid equilibrium constant smaller than the above range, for example, oxalic acid (pKa ₁ :
When an organic carboxylic acid such as 1.04, pKa ₂ : 3.82) is used, it reacts violently with alkanolamines to form a salt, resulting in insufficient dispersion in the resin component, Is not preferable because the physical properties thereof are significantly reduced. On the other hand, if the acid equilibrium constant is larger than the above range, the alkanolamines cannot be completely restrained in the resin component, and the surface properties of the composition are undesirably deteriorated.

Of the above organic carboxylic acids, use of higher fatty acids, especially stearic acid, is most preferable in consideration of performance, workability, cost and the like.

The compounding amount of the organic carboxylic acid (C) is as follows:
The carboxyl group of the component (C) and the amino group of the alkanolamines (B) are selected so that the molar ratio of carboxyl group / amino group is 0.01 to 2, especially 0.1 to 1.5. Is preferred. That is, if the amount of the component (C) is too small, a sufficient effect of improving the surface properties cannot be expected. If the amount is excessive, the component (C) itself causes whitening and impairs transparency. It is not preferable.

[Composition] The ethylene copolymer composition of the present invention is obtained by heating and mixing the ethylene copolymer (A), the alkanolamines (B) and the organic carboxylic acid (C). The order of mixing these three components is arbitrary. For example, a method of mixing (A) and (B) and then mixing (C), a method of mixing (A) with (C) and then mixing (B), After blending (B) and (C), a method of blending with (A) can be adopted.

The method of heating and mixing includes a single screw extruder, a twin screw extruder, a Banbury mixer,
A thermoplastic resin melt mixing method using a kneader or the like, or a solution mixing method in a dispersion medium such as water can be adopted. In the melt mixing method, when the resin temperature is too high, not only the thermal deterioration and coloring of the composition become severe, but also when the primary amine is used as (B), an acid amide forming reaction tends to occur. Therefore, it is desirable to melt-knead at 200 ° C. or less. On the other hand, the solution mixing method has an economic disadvantage since it is necessary to remove the solvent.

Various additives can be added to the ethylene copolymer composition of the present invention as long as the object of the present invention is not impaired. Examples of such additives include antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, flame retardants, flame retardant aids, foaming agents, crosslinking agents, tackifiers, pigments, dyes, and others. Antistatic agents, inorganic fillers, fiber reinforcing agents, and the like.

In order to improve the physical properties of the ethylene copolymer composition of the present invention while essentially retaining the properties of the ethylene copolymer composition,
A polymer as described later can be blended in an arbitrary ratio.

The ethylene copolymer composition of the present invention can be used as an antistatic improver for imparting antistatic properties to various polymers. In an embodiment of mixing and using such other polymer, for example, per 100 parts by weight of the ethylene copolymer composition of the present invention, the other polymer can be blended at a ratio of 1 to 10,000 parts by weight. . In particular, when it is desired to minimize the influence on the physical properties of the other polymer and achieve its antistatic property, the other polymer 1
It is preferred that the ethylene copolymer composition of the present invention is blended in an amount of 1 to 40 parts by weight, particularly 5 to 30 parts by weight, per 100 parts by weight.

Examples of the other polymer include polyolefin resin, styrene resin, polyamide, polyester, polycarbonate, polyacetal, polymethyl methacrylate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyvinyl chloride, and the like.
One or a combination of two or more of polyvinylidene chloride, polyvinyl alcohol, polyolefin elastomer, various rubbers and the like can be exemplified.

More specifically, polyolefin resins include high-pressure polyethylene, linear medium / low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, polypropylene produced in the presence of a single-site catalyst or a multi-side catalyst. , Poly-1-butene, poly-4
-Methyl-1-pentene, ethylene produced by a high-pressure method
Examples thereof include a vinyl acetate copolymer and an ethylene / unsaturated carboxylic acid ester copolymer. The styrene-based resin is a homopolymer or a copolymer of styrene, and typical examples thereof include an ABS resin and polystyrene. The ABS resin is a general term for rubber-reinforced styrene-based polymers synthesized by various production methods such as a blending method, a grafting method, or a graft blending method, and includes polybutadiene, styrene / butadiene copolymer rubber, and acrylonitrile. -Monomers such as styrene, α-methylstyrene, vinyltoluene, acrylonitrile, ethyl acrylate, methyl methacrylate, and maleimide anhydride are added to rubber components such as butadiene copolymer rubber and ethylene-propylene copolymer rubber. Graft copolymerization in combination of two or more species can be given as a typical example. Examples of the polystyrene include not only a homopolymer of styrene but also a copolymer of styrene and the above other monomer. Polyamides such as nylon 6, nylon 66, nylon 6.66, nylon 11, nylon 12, nylon 6T-6I, and polyesters such as polyethylene terephthalate, polybutylene terephthalate,
Examples thereof include wholly aromatic polyesters and polyester ether elastomers.

[0035]

Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited to only these examples. Ethylene / unsaturated carboxylic acid used in the following Examples and Comparative Examples (hereinafter referred to as acid copolymer)
[(A) component], an amine compound [(B) component], and an organic fatty acid [(C) component] are shown.

Component (A)

[Table 1]

Component (B)

[Table 2]

Component (C)

[Table 3]

Thermoplastic resin

[Table 4]

The physical properties in Examples and Comparative Examples were measured by the following methods. Physical property measurement method

Surface resistivity evaluation method: A composition prepared by a twin-screw extruder was subjected to
The film was processed with an inflation film to produce a film having a width of 200 mm and a thickness of 50 μm. After the obtained sample film was allowed to stand in a thermo-hygrostat set at 23 ° C./50% relative humidity for 24 hours or more, the surface resistivity was measured by the following device. ASTM D257 Mitsubishi Chemical Hiresta IP

Surface physical properties Stickiness Evaluation method: Leave the sample in the air for one week,
When the ET film is attached, the stickiness is evaluated. ：: No wetting or adhesiveness was observed at all. ×: Adhesion is recognized at the same time as it becomes extremely wet. 2. Coloring Evaluation method: The sample is allowed to stand in the air for one week, and the appearance is visually evaluated. ：: Colorless and transparent without any coloring. ×: Coloring such as whitening or redness Amine odor evaluation method: The sample was allowed to stand in the air for one week, and the presence or absence of amine odor on the resin surface was evaluated. ：: Almost no amine odor. ×: Severe amine odor.

Examples / Comparative Examples The compositions having the compositions shown in the table were melt-blended at 180 ° C. and a screw rotation speed of 150 min-1 using a 30 mm Φ twin screw extruder manufactured by Thermo Plastics Co., Ltd. As for the method of compounding the mixture, a salt of an amine compound and a low-molecular fatty acid was prepared in advance using a kneader, and the salt was dry-blended and then melt-blended under the above conditions. The physical properties of the obtained heat-mixed composition after being formed into a film were evaluated and summarized. Table 1 summarizes the compositions of the examples and Table 2 summarizes the evaluation results.

Example 1 In Example 1, the amount of the amine compound 1 having an amino group equivalent to 60 mol% with respect to the carboxyl group of the acid copolymer 1 and the amount of the low molecular fatty acid equivalent to 30 mol% were determined. 1 is blended. Table 2 shows the evaluation results. The composition of Example 1 has good surface resistivity and good surface properties.

Examples 2 and 3 Examples 2 and 3 are compositions obtained by mixing acid copolymers 2 and 3 in place of acid copolymer 1 in Example 1. Table 2 shows the evaluation results. The compositions of Examples 2 and 3 have the same surface resistivity and surface properties as those of Example 1.

Examples 4 to 6 Examples 4 to 6 are compositions obtained by mixing amine compounds 2 to 4 in place of amine compound 1 in Example 1. Table 2 shows the evaluation results. The compositions of Examples 4 to 6 have the same surface resistivity and surface properties as those of Example 1.
However, the composition shown in Example 4 was used to avoid coloring.
Prepared at low temperature of ° C.

Examples 7 and 8 Examples 7 and 8 differ from Example 1 in that
This is a composition in which low molecular fatty acids 2 and 3 are blended in place of the above. Table 2 shows the evaluation results. The compositions of Examples 7 and 8 have the same surface resistivity and surface properties as those of Example 1.

Comparative Example 1 In Comparative Example 1, low-molecular fatty acid 1 was not used in Example 1. Table 2 shows the evaluation results. In the composition of Comparative Example 1, the surface physical properties were significantly deteriorated due to bleeding of the amine compound, and although the antistatic property was temporarily good, the antistatic property was easily reduced by wiping with cloth or washing with water.

Comparative Examples 2 and 3 Comparative Examples 2 and 3 were the same as Examples 2 and 3 except that low-molecular fatty acids 2 and 3 were not used. Table 2 shows the evaluation results.
In the compositions of Comparative Examples 2 and 3, similarly to the composition of Comparative Example 1, the surface properties were significantly deteriorated due to the bleeding of the amine compound,
Although the antistatic property is temporarily good, the antistatic property is easily reduced by wiping with a cloth or washing with water.

Comparative Example 4 In Comparative Example 4, low-molecular fatty acid 4 was used in Example 1. Table 2 shows the evaluation results. In the composition of Comparative Example 4, the amine compound and the low molecular weight fatty acid 4 react to form a salt,
It will whiten violently. Insufficient antistatic properties are also obtained.

Further, the composition shown in Example 1 was blended with various thermoplastic resins and evaluated in the same manner. Mixing is 40mm
180 ° C using a single screw extruder at a screw rotation speed of 30
Melt and kneaded at 〜40 rotations. The compositions and evaluation results are shown in Tables 3 and 4, respectively.

Examples 9 and 10 In Examples 9 and 10, the composition shown in Example 1 was prepared by mixing the thermoplastic resin 1 with the ethylene copolymer composition / thermoplastic resin in a weight ratio of 15/85 and 30. / 70. The evaluation results are shown in Table 4, and showed good surface physical properties and surface resistivity.

Examples 11 and 12 In Examples 11 and 12, the composition shown in Example 1 was added to thermoplastic resins 2 and 3 so that the weight ratio of ethylene copolymer composition / thermoplastic resin was 15/85. Was blended in. The evaluation results are shown in Table 4, and showed good surface physical properties and surface resistivity.

Comparative Examples 5 to 7 In Comparative Examples 5 to 7, the ethylene copolymer composition was not used in Examples 9 to 12. The results are shown in Table 4, but none of them has antistatic performance.

[0055]

[Table 5]

[0056]

[Table 6]

[0057]

[Table 7]

[0058]

[Table 8]

[0059]

According to the present invention, there is provided an ethylene copolymer composition having excellent antistatic properties, low antistatic properties with low humidity dependency, and excellent effects. Can be. The molded article obtained from such a composition has the feature that there is no trouble due to bleeding or whitening on the surface and that the surface specific resistivity hardly decreases even when the molded article surface is washed with water or wiped with a cloth. I have. Therefore, it can be used not only as a molded article based on such an ethylene copolymer, but also as an antistatic agent for various polymers. A polymer prepared by blending these copolymer compositions can be widely used as a molded article having improved antistatic performance while having the inherent properties of each polymer. Thus, the ethylene copolymer composition of the present invention, or various polymers blended with these ethylene copolymer compositions, can be produced by various molding methods such as injection molding, blow molding, extrusion molding, press molding, vacuum molding, and air pressure. It can be formed into sheets, films, containers, rods, tubes, pipes, and molded articles of various shapes by molding or the like. Such molded articles can be used, for example, as packaging materials, building materials, foam materials, agricultural films, and the like.

Claims (5)

[Claims] 1. An ethylene / unsaturated carboxylic acid copolymer (A), an alkanolamine (B) and an acid equilibrium constant (p
An ethylene copolymer composition comprising an organic carboxylic acid (C) having a carboxyl group having 2 to 7 Ka). 2. The ethylene according to claim 1, wherein the alkanolamine (B) is blended in a ratio of 0.01 to 1 equivalent to the carboxyl group of the ethylene / unsaturated carboxylic acid copolymer (A). Copolymer composition. 3. The ethylene according to claim 1, wherein the carboxyl group of the organic carboxylic acid (C) and the amino group of the alkanolamine (B) are blended in a molar ratio of 0.01 to 2. Copolymer composition. 4. An antistatic agent comprising the ethylene copolymer composition according to claim 1. 5. A thermoplastic resin composition comprising another polymer and the ethylene copolymer composition according to claim 1.