JPS614736A - Rendering resin molding antistatic - Google Patents

Abstract

PURPOSE:To obtain a molding which can retain an excellent antistatic quality without causing foaming or decomposition during molding, by contacting a molding obtained from a specified resin (composition) with an N2-containing compound (solution). CONSTITUTION:A molding is obtained by molding a composition comprising a copolymer resin prepared by copolymerizing C2H4 with 1-12mmol/g of a resin of at least one unsaturated carboxylic acid (derivative) at 150-300 deg.C and 50- 6,000atm in the presence of a free-radical generator or a resin composition containing this resin and, optionally, at most 75wt%, based on the total resin composition, other thermoplastic resins or elastomers (e.g., PP or diene elastomer). This molding is immersed in or coated with at least one N2-containing compound selected from among amine compounds and quaternary ammonium salt of formulas I -IV (wherein R<1-10> are each a 16C or lower organic group, l, m, and n are each 1-6, X is a halogen, SO4, or the like, and a >=1) or an aqueous or organic solvent solution of said compound in a 0.01-100M concentration at room temperature-80 deg.C for 1sec-30min.

Description

[Detailed description of the invention] The present invention relates to a method for preventing static electricity on resin molded products.

Many efforts have been made over the years to prevent static electricity in plastic molded products. In particular, with the recent development of precision electronic equipment parts such as ICs, great care must be taken to prevent electrostatic charging during packaging and transportation.
Sufficient packaging materials are not yet available.

As packaging materials for second-class electronic equipment products and parts, so-called molded products consisting of conventionally used molded products,
There is so-called wrap packaging that uses films, etc., and while foamed styrene molded products are often used for the former, vacuum molded products or injection molded products are also used.

Conventionally, conductive carbon black has been added to resins to prevent static electricity in secondary objects and wrap materials, but this is expensive and requires the use of black packaging materials to make them opaque. - In addition, the added carbon black tends to peel off and contaminate the packaged product or parts, so it is not a very desirable method.

On the other hand, antistatic agents are also added or kneaded into resin molded products, but the antistatic agents used scatter into the atmosphere and are difficult to maintain performance over a long period of time. Furthermore, its antistatic ability is affected by the humidity in the atmosphere. For example, under high humidity conditions, a surface resistivity of about 108 to 1QIOΩ and good conductivity may be exhibited, but under low humidity conditions, it will not absorb moisture. The amount of absorption decreases, the conductivity decreases, and a surface resistance close to insulation resistance of about 10 14 to 10 15 Ω is exhibited, resulting in a state in which the necessary antistatic ability is not exhibited.

In addition, coating or kneading type packaging materials have the disadvantage that they lose conductivity even when washed with water, and the conductivity does not recover.The resulting effect is unstable, making it difficult to use for high-end electronic equipment or husbandry. It is said that it is not suitable for use in parts such as

There is also a method of imparting conductivity to the surface of the film by depositing metal on a transparent plastic film, but this method is expensive and not very practical.

As described above, the methods for preventing static electricity on plastic molded products currently in use have their own drawbacks, and there is no preferred method.

The present inventors first reacted a specific ethylene-unsaturated carboxylic acid copolymer with a specific amine compound and a quaternary ammonium salt, and obtained a resin in which the amount of the nitrogen-containing compound was 1.3 mmol/7 resin or more. Although we have discovered and reported that the above resin exhibits excellent conductivity, it is generally highly hygroscopic, and if it is stored in a normal manner, it will absorb a large amount of moisture from the air, and if it is directly molded, A satisfactory molded product could not be obtained due to foaming, and a special vented molding machine was required. Furthermore, the resin had the drawback of poor thermal stability and easy decomposition when the molding temperature was set high, requiring severe molding conditions.

As a result of intensive research in order to avoid foaming and decomposition during molding, the present inventors have molded a resin or resin composition that is a copolymer of ethylene and unsaturated carboxylic acid and/or its derivatives, and formed a predetermined molded product. After that, the molded article is brought into contact with the nitrogen-containing compound selected from the group consisting of an amine compound and a quaternary ammonium salt, and the carboxylic acid groups on the surface of the molded article and its vicinity are reacted with the amine compound and/or the quaternary ammonium salt. The present inventors have discovered that, by doing so, a molded article that is free from foaming and exhibits excellent antistatic properties can be obtained, and has thus arrived at the present invention.

The resin (A) that is a copolymer of ethylene and an unsaturated carboxylic acid and/or its derivatives is a resin that is a copolymer of ethylene and one or more unsaturated carboxylic acids and/or its derivatives selected from the group shown below. It is usually copolymerized at 150-300°C and 50-6000 atm in the presence of a free radical generator. At this time, the monomers include vinyl acetate, styrene, allyl alcohol, vinyl chloride, glycidyl methacrylate, N,N-dimethylamine acrylate, vinyl ethyl ether, vinyl methyl ether, vinyl butyl ether, propylene, isobutylene and other α-olefins, butadiene, A diene compound such as isoprene may also be present in the resin. .

In the present invention, unsaturated carboxylic acids and/or derivatives thereof include, for example, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, and lower alkyl esters thereof. Lower alkyl is a hydrocarbon group having at most 8 carbon atoms, such as methyl, ethyl, propyl, and hexyl.

Particularly preferred examples include methyl or ethyl esters of acrylic acid, methacrylic acid, maleic anhydride and the like.

In addition, the content of the unsaturated carboxylic acid and/or its derivative in the above copolymer is generally 1 mmol/g resin (expressed as the number of mmol per unit resin amount, the same applies hereinafter) to 12 mmol/7, It is preferably 1.3 mmol/g to 10 mmol/g, more preferably 2.0 to 8 mmol/g.
．． 0 mmol/q1, most preferably 2.5-5.0 mmol/9.

These resins may partially contain metals such as Na, 7n, and Mg. The metal contained in the resin is at most 2.0% by weight.

Next, the copolymer may be molded as it is and treated with an amine compound and/or a quaternary ammonium salt, or a composition in which other resins are blended in advance may be molded and treated.

As the resin component (C) used in the above copolymer, it is preferable to use a thermoplastic resin or an elastomer.
Examples include high, medium and low pressure polyethylene, polypropylene, ethylene-vinyl acetate copolymers and their hydrolysates,
polymethacrylic acid ester, polyacrylic acid ester,
Thermoplastic resins such as polystyrene, ionomers, polycarbonates, polyamides, and polyesters; (1) Lastomers include diene-based, olefin-based, ester-based, urethane-based, styrene-based, nitrile-based, and chlorinated olefin-based.

The amount of resin used in these formulations depends on the degree of conductivity imparted to the intended treated molded product and the copolymer resin (A
), varies depending on the type of resin component (C), so generally, at most 75% of the entire resin composition, although not limited to
% by weight, preferably at most 60% by weight or less.

Furthermore, other additives such as weathering stabilizers, antioxidants, slip agents, and antistatic agents may be added to the resins and resin compositions of the present invention, if necessary.

These ethylene copolymer resins or compositions containing other resins are molded, and then the resulting molded products, such as films, sheet fibers, injection molded products, blow molded products, etc., are treated with amine compounds and/or quaternary ammonium. In a salt or a solution containing an amine compound and/or a quaternary ammonium salt, at a temperature that does not deform or deteriorate the molded product, usually from room temperature to below the boiling point of the solvent, generally from room temperature to 80°C for 1 second to 30 minutes. You can immerse it or apply a liquid.

The treatment method is to immerse the resin molded product in a treatment solution,
Alternatively, the treatment can be carried out by passing it over a roller whose lower part is immersed in a treatment solution, but the method is not particularly limited to this.

After the treatment, it may be washed with running water and dried.

The amine compound and quaternary ammonium salt used for imparting conductivity are those containing ammonia or an organic group having at most 16 carbon atoms.

More specifically, ■ RI R2R3N ■ (RI R2R3RION)8X R1-10 are hydrogen atoms or organic groups having at most 16 carbon atoms, and R1-1G may be the same or different from each other, and R1-1G may be the same or different from each other, and At least two arbitrary hydrocarbon groups may form a ring.

The organic group may include a hydroxyl group, a halogen element, an alkoxy group, a carbonyl group, an ester group, an amide group, and the like. 1. m and n are numbers from 6 to 6, x is a counter anion such as OH, halogen, SO4, 0104, etc., and a represents a number of 1 or more depending on its ionic valence. Preferably R1
-10 is a hydrogen atom or an aliphatic group having at most 6 carbon atoms.

Regarding (1), (2), and (2), preferred are those in which at least R1 is a hydrogen atom or an aliphatic organic group in which at least R2 is a hydroxyl group. Particularly preferred are compounds containing at least two amine groups or containing a nitrogen atom in a six-membered ring at most. In addition, (2) is preferable, and those having a hydroxyl group in RlG are particularly preferable. Specific preferred examples include ethanediamine, N-methylethanediamine, N,N-dimethylethanediamine, propanediamine, N-methylpropanediamine, N,N-dimethylpropanediamine, pyrrolidine, imidazolidine, piperidine, Methylpiperidine, imidazole, piperazine, morpholine, tetramethylammonium salt, tetraethylammonium salt, benzyltrimethylammonium salt,
β-Hydroxy ■Tiltrimethylammonium salt. Specific preferred examples include ethanediamine, N-
Methylethanediamine, N,N-dimethylethanediamine, propanediamine, N-methylpropanediamine,
N,N-dimethylpropanediamine, ethylamine, diethylamine, propylamine, dipropylamine, monoethanolamine, jetanolamine, triethanolamine, N-(β-hydroxyethyl)ethanediamine, pyrrolidine, imidacilline, piperidine, methylpiperidine , imidazole, piperazine, morpholine,
These include tetramethylammonium salt, tetraethylammonium salt, benzyltrimethylammonium salt, choline, choline chloride, and the like.

One or more of these amine compounds and/or quaternary ammonium salts □ can be added directly or with water, alcohol,
0.0 for solvents such as ethers, esters, ketones, and hydrocarbons.
It is used after being dissolved in a concentration of 0.01 to 100 molar, preferably 0.1 to 10 molar, particularly preferably 0.5 to 5 molar.

Such treatment significantly reduces the surface resistivity of the molded product, but the level depends on the content of the unsaturated carboxylic acid and/or its derivative in the resin used for molding, the type and concentration of the amine compound and quaternary ammonium salt, It changes depending on the processing temperature and time. However, the value of volume resistivity does not decrease significantly, although it depends on the thickness of the molded product.

The desired value of surface resistivity varies depending on the application, and 1013Ω is effective when the purpose is to prevent dust adhesion and antifouling, but 10L2Ω is effective for packaging and transporting precision electronic equipment.
Hereinafter, it is preferably 1Q11Ω or less.

The conductive resin molded product obtained in this way has an antistatic effect when the carboxylic acid forms an ammonium salt in the surface layer, and this layer absorbs or occludes water, becomes conductive, and exhibits an antistatic effect. Unlike the conventional method of simply coating or kneading an antistatic agent into the surface layer, moisture absorption or occlusion occurs through chemical ionic bonds in the surface layer.
Its antistatic effect is significantly improved, and since the effect is confined to the surface layer of the molded article, a sustained electrical conductivity is obtained and there is no adverse effect on the packaged article.

The method of the present invention can be applied to various molded products.

For example, it can be applied to molded products formed by all known molding methods such as film molding, sheet molding, extrusion molding, compression molding, spinning, injection molding, and blow molding, and furthermore, after the above molding, further stretching, lamination, vacuum molding, etc. Air pressure molding, foaming,
A process such as stamping may be applied to the molded product after passing through/j. Furthermore, it is effective even if it is processed after it has been made into products such as ropes, strings, and cloth. Furthermore, as shown in the comparative example, even when the treatment of the present invention is applied, the surface resistivity cannot be sufficiently reduced if the resin used for molding has a low unsaturated carboxylic acid content.

The present invention will be explained below with reference to Examples. In the example, a set of five test pieces (10 cm x 10 cm x 2 mn+) was prepared, and each test piece was immersed in a predetermined solution for a predetermined time, washed and dried, and its surface resistivity σ (Ω) was determined. The results obtained by measurement were averaged for each set and the results are shown.

Generally, the surface state is measured by measuring the surface resistivity, and in the above description, this physical property has been explained, but in general, the antistatic property of the surface is as long as the surface resistivity is 1011Ω or less. It is known that no damage occurs due to the accumulation of static electricity on the surface.

The surface resistivity σ (Ω) was measured as follows.

That is, Yokogawa Hewlett-Packard Super Insulation Resistance Meter 4
329A and resistance cell 16008A were used, and the measurements were made after being left in a constant temperature and humidity chamber at 50% relative humidity and 22°C. Also M
1 was measured at 190°C under 9 loads on 2.16.

Example 1-4 Ethylene-acrylic acid copolymer (acrylic acid content 3.
0 mmol/g, MI320) 60 parts by weight, high pressure low density polyethylene (methyl methacrylate 0.5 mmol/g)
q@Right, MI8) After mixing 40 parts, it was formed into a 30μ film.

The obtained film was immersed for 2 minutes at 35° C. in a 3 molar/water-methanol 1:1 mixed solution using the compounds shown in the table below. The immersed film was immediately passed through a running water tank at room temperature, dried with a blower, and wound up.

The results are shown in the table below.

Examples 5 to 8 Ethylene-methacrylic acid copolymer (Methacrylic acid content: 2.0 mmol/g, ML, 11) was molded into a 30μ film.

The obtained film was immersed in a 5 molar aqueous solution of the compound shown in the table below in the same manner as in Example 1, then washed and dried.

Example 9 Ethylene-acrylic acid copolymer (acrylic acid-containing 3.
0 mmol/g, MI320) 60 wt., high pressure low density polyethylene (methyl methacrylate 0.5 mmol/g)
g containing, MI8) 40W, 30μ after mixing fia part
It was formed into a film.

The obtained film was immersed in a 3 molar β-hydroxyedyltrimethylammonium hydroxide aqueous solution at 40° C. for 1 minute. The immersed film was immediately passed through a running water tank at room temperature, dried with a blower, and wound up.

As a result, an odorless film with surface resistivity of 3.4×10 8 Ω and excellent transparency was obtained.

Comparative Example 1 A 30μ film of high pressure low density polyethylene (MI3) was treated in the same manner as in Example 1. Surface specific resistance 101
It was 6Ω or more.

Comparative Example 2 In Example 1, 3 parts by weight of ethylene-acrylic acid copolymer (acrylic acid content: 3.0 mmol/g, MI320) was used.

The surface resistivity was 1.2×101”Ω.

Examples 10 and 11, Comparative Example 3 0.5 m thick press sheets of ethylene-methacrylic acid copolymers with different methacrylic acid contents were made and treated in the same manner as in Example 1.

Example 12, Comparative Example 4 A press sheet of the ethylene-acrylic acid copolymer resin used in Example 1 (10 cm x 10 cm x Q, 5
m thickness, material (C)) was treated with jetanolamine by the method shown in Example 1 to obtain sample F4 (A).
2).

On the other hand, when 10 kg of the same resin and 3 o's of water were put into the 3001 reaction tank, 4. ．． 32Kg of jetanolamine,
Add 1 mm above and below the chamber, react at 120'C for 6 hours, cool to room temperature, wash twice with acetone, and press sheet in the same way from □ of the resin with 1.9 mmol/g resin of jetanol amination. Comparative Example 4) to obtain sample (B). JIS from the above samples (A>, (B) and (C)
A tensile test (tensile speed 200 s/m1n) was conducted on the sample using a No. 2 dumbbell, and the results are shown in the table below along with the surface resistivity values of each sample.

The resin shown in Comparative Example 4 had a melting peak stop temperature of 98°C.
Also, a weight decrease was observed from 162°C. 1 more
When held at 50°C for 5 minutes, it turned yellow. In contrast to the lack of thermal stability and the narrow temperature range from melting to decomposition, which poses molding problems, the method of the present invention improves the physical properties of the resin, such as rigidity, strength, and elongation. It is clear that it can be easily molded without reducing the properties and can be imparted with electrical conductivity.

Claims (1)

[Claims] 1. A copolymer resin (A) containing ethylene and 1 mmol or more of an unsaturated carboxylic acid and/or a derivative thereof per 1 g of the resin (A) described below, or a resin composition (B) containing the above resin (A). After molding, the resulting molded product is brought into contact with at least one nitrogen-containing compound or a solution containing the nitrogen-containing compound selected from the group consisting of amine compounds and quaternary ammonium salts. Anti-static method for products.