JP3062639B2 - Method for improving conductivity of resin molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the conductivity of a resin molded product.

[0002]

2. Description of the Related Art As a conventional method for improving the conductivity of a resin molded product, there is a method of kneading carbon black, carbon fiber, conductive mica and the like into a raw material of the resin molded product.

However, in such a conventional method for improving the conductivity of a resin molded product, the conductivity cannot be improved unless a large amount of a conductive substance such as carbon black is kneaded into the raw material of the resin molded product. However, deterioration of the physical properties of the resin molded body could not be avoided. In addition, there is also a problem of coloring such as black, and its use is limited.

[0004]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the conventional method and reduces the conductivity of the resin molded article without impairing the physical properties of the resin molded article and without causing a coloring problem. It is an object to provide a method which can be significantly improved.

[0005]

According to the present invention, a complex of an alkylene oxide polymer and a soluble electrolyte salt is kneaded into a raw material of a resin molded product, molded, and then subjected to a heat treatment on the surface of the molded product. Solution to the Problems

[0006] That is, the method of the present invention is characterized in that the raw material of the resin molded product contains at least one alkylene oxide polymer selected from the group consisting of homopolymers, block copolymers and random copolymers of alkylene oxide monomers. And a complex with a soluble electrolyte salt are kneaded into the mixture, the kneaded product is molded, and the surface of the obtained molded body is subjected to heat treatment.

In the present invention, since the cations and anions of the soluble electrolyte salt in the complex kneaded in the resin can move through the ether-bonded oxygen in the alkylene oxide polymer, the resin has an ion conductive property. Occurs, and the resistance value decreases. This further exerts a synergistic effect with the surface modification effect by the heat treatment performed after molding, and it is possible to obtain a high-quality resin molded article having significantly improved conductivity as compared with the conventional case.

Further, when coating is performed after molding, an electrostatic coating method which is a highly efficient coating method is preferable. However, conventionally, electrostatic coating on a resin having a high resistance value is impossible, and a conductive primer is used. It has been common practice to conduct electrostatic coating after the molded article is made conductive by using a method such as kneading or kneading carbon black, conductive mica or the like into a resin. However, these methods have problems in paint adhesion and mechanical strength of the molded article. Since the resin molded body having improved conductivity by the method of the present invention has conductivity suitable for electrostatic coating, it also enables highly efficient electrostatic coating after molding.

In the present invention, as a raw material of a resin molded product, a polyolefin resin such as polyethylene or polypropylene;
Any resin having a high surface resistance such as a BS resin, an acrylic resin, a polyamide resin, a polyvinyl chloride resin, a polycarbonate resin, a polyacetal resin, and a phenol resin can be used.

The alkylene oxide polymer used in the complex kneaded into the raw material of the resin molded product is at least one selected from the group consisting of homopolymers, block copolymers and random copolymers of alkylene oxide monomers. It is a kind of alkylene oxide polymer, usually adding an alkylene oxide to the following active hydrogen compound (ring opening)
It has been polymerized.

Examples of the active hydrogen compound include monohydric alcohols such as methanol and ethanol, ethylene glycol,
Dihydric alcohols such as propylene glycol and 1,4-butanediol, polyhydric alcohols such as glycerin, trimethylolpropane, sorbitol, sucrose and polyglycerin, monoethanolamine, ethylenediamine, diethylenetriamine, 2-ethylhexylamine, hexa Examples include amines such as methylene diamine, and phenolic active hydrogen-containing compounds such as bisphenol A and hydroquinone.

Examples of the alkylene oxide monomer include ethylene oxide, propylene oxide, 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, and 1,2-epoxyoctane. , 1,2-epoxynonane or the like having 2 to 9 carbon atoms
Α-olefin oxide, and α having 10 or more carbon atoms
Any of olefin oxide, styrene oxide and the like can be used, but ethylene oxide, propylene oxide and 1,2-epoxybutane are particularly preferable.

In the polymerization reaction, a basic catalyst such as sodium methoxide, sodium hydroxide, potassium hydroxide, lithium carbonate, triethylamine and potassium tert-butoxide, and an acidic catalyst such as perchloric acid and boron trifluoride are used. Particularly, a basic catalyst is preferably used.

The number average molecular weight of the alkylene oxide polymer is preferably from 500 to 100,000.

Further, the soluble electrolyte salt forming a complex with the alkylene oxide polymer includes lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium perchlorate, lithium thiocyanate, sodium bromide, and the like. Sodium iodide, potassium thiocyanate,
Examples thereof include inorganic ion salts such as potassium iodide, and organic ion salts such as an alkali metal or alkaline earth metal salt of trifluoromethanesulfonic acid, and the amount thereof is 5 to 100 parts by weight of the alkylene oxide polymer.
It is preferably 10 parts by weight.

The amount of the complex of the above-mentioned alkylene oxide polymer and soluble electrolyte salt is 0.1 to 10 parts by weight, especially 0.1 to 3 parts by weight, based on 100 parts by weight of the resin molding material. preferable. If it is less than 0.1 part by weight, no improvement in conductivity is observed. Addition of more than 10 parts by weight is preferable for improving the conductivity, but causes deterioration of the mechanical properties of the resin, and thus has no great advantage.

As a method for forming a complex between the alkylene oxide polymer and the soluble electrolyte salt, a single solvent having high compatibility with the alkylene oxide polymer such as water, methanol, methyl ethyl ketone, tetrahydrofuran, acetone, methylene chloride or the like is used in advance. It is preferable to dissolve a soluble electrolyte salt in a mixed solvent, uniformly mix the solution and the alkylene oxide polymer to prepare a complex solution, and then remove the solvent to obtain a complex.

As a method of kneading the complex of the alkylene oxide polymer and the soluble electrolyte salt into the raw material of the resin molded product, any commonly used method such as a twin-screw extruder type or a hot roll type can be used. As the molding method of the molded article, any of the commonly used methods such as injection molding, extrusion molding, calendering, compression molding, and SMC method can be used.

In order to heat-treat the obtained resin molded body,
Using an electric furnace, a hot air drying furnace, etc., the resin molded body is
The treatment is performed at 150 ° C, preferably 80 to 120 ° C, for 1 to 60 minutes, preferably 3 to 30 minutes. It is also possible to perform a heat treatment simultaneously with the molding.

The plasma treatment, which is a method for modifying the surface of the resin molded product, does not hinder the method of the present invention at all. It works in a preferred direction in terms of lowering. When the plasma treatment is used in combination, it may be performed before or after the heat treatment.

[0021]

EXAMPLES Examples of the synthesis of alkylene oxide polymers are shown below.

Synthesis Example 1 (Synthesis of alkylene oxide polymer B-1) Using 212 g of diethylene glycol as a starting material, 4 g of potassium hydroxide as a catalyst, and 1,78 g of ethylene oxide
After reacting 8 g at 120 ° C. for 8 hours in a 5-liter autoclave, desalting and purification were carried out to obtain 1,950 g of an ethylene oxide homopolymer having a number average molecular weight of 1,000 (calculated from a hydroxyl value).

Synthesis Example 2 (Synthesis of alkylene oxide polymer B-2) Using 212 g of diethylene glycol as a starting material, 12 g of potassium hydroxide as a catalyst and 1,8 of ethylene oxide
After reacting 94 g and 1,894 g of propylene oxide in a 5-liter autoclave at 120 ° C. for 8 hours, desalting and purification were carried out, and the number average molecular weight was 4,000.
3,980 g of an ethylene oxide-propylene oxide random copolymer (calculated from the hydroxyl value) was obtained.

Synthesis Example 3 (Synthesis of alkylene oxide polymer B-3) Using 368 g of glycerin as a starting material, 4.8 g of potassium hydroxide as a catalyst, and 2032 g of ethylene oxide in a 5-liter autoclave at 120 ° C. for 8 hours. After the reaction, desalting and purification were performed, and the number average molecular weight was 600
2,390 g of an ethylene oxide homopolymer (calculated from the hydroxyl value) was obtained.

Synthesis Example 4 (Synthesis of alkylene oxide polymer B-4) Using 184 g of glycerin as a starting material, 12.0 g of potassium hydroxide as a catalyst, 1,2-epoxybutane 3,8
16 g in a 5 liter autoclave at 130 ° C.
For 4 hours, followed by desalting and purification to obtain 3,940 g of a 1,2-epoxybutane homopolymer having a number average molecular weight of 2,000 (calculated from a hydroxyl value).

Synthesis Example 5 (Synthesis of alkylene oxide polymer B-7) Using 92 g of glycerin as a starting material, 21 g of potassium hydroxide as a catalyst, 10 liters of 1,382 g of ethylene oxide and 5,526 g of 1,2-epoxybutane After reacting at 120 ° C. for 8 hours in an autoclave, desalting and purification were performed to obtain 6,990 g of an ethylene oxide-1,2-epoxybutane random copolymer having a number average molecular weight of 7,000 (calculated from a hydroxyl value). .

Synthesis Example 6 (Synthesis of alkylene oxide polymer B-11) Using 182 g of sorbitol as a starting material and 9 g of potassium hydroxide as a catalyst, 1,409 g of ethylene oxide was first added at 120 ° C. in a 5-liter autoclave at 120 ° C. For 1,2 epoxybutane 1,40
After reacting 9 g at 120 ° C. for 7 hours, desalting and purification were carried out to obtain 2,990 g of an ethylene oxide-1,2-epoxybutane block copolymer having a number average molecular weight of 3,000 (calculated from a hydroxyl value).

Table 1 shows examples of alkylene oxide polymers that can be used in the present invention.

[0029]

[Table 1]

Example 1 Alkylene oxide polymer (B-3) 5 obtained in Synthesis Example 3
25 g of lithium perchlorate in 10 g of methanol
A solution dissolved in 0 g was added, and the mixture was stirred to obtain a uniform solution, and then methanol was topped under reduced pressure to obtain a complex.

10 g of this complex and 1 k of polypropylene resin
g was kneaded at 180 ° C. for 10 minutes using a twin-screw extruder, and the obtained pellets were formed using an injection molding machine (Hypershot manufactured by Niigata Iron Works).
(30 mm × 230 mm × 3 mm) was placed in an electric dryer, and heat-treated at 120 ° C. for 5 minutes to obtain a test piece.

Example 2 Alkylene oxide polymer (B-4) 5 obtained in Synthesis Example 4
25 g of lithium perchlorate in 10 g of methanol
After adding a solution dissolved in 0 g and stirring to form a uniform solution, methanol in the solution was topped under reduced pressure to obtain a complex.

5 g of this complex and 1 kg of polypropylene resin
Was kneaded at 180 ° C. for 10 minutes using a twin-screw extruder,
Molding was performed in exactly the same manner as in Example 1, and the resulting molded body (230
mm × 230 mm × 3 mm) in an electric dryer.
A heat treatment was performed at 0 ° C. for 10 minutes to obtain a test piece.

Example 3 Alkylene oxide polymer (B-7) 5 obtained in Synthesis Example 5
25 g of potassium thiocyanate in 2 g of acetone
A solution dissolved in 00 g was added, and the mixture was stirred to form a uniform solution, and then acetone was reduced in pressure to obtain a complex.

3 g of this complex and 1 kg of polypropylene resin
Was kneaded at 180 ° C. for 10 minutes using a twin-screw extruder,
Molding was performed in exactly the same manner as in Example 1, and the resulting molded body (230
mm × 230 mm × 3 mm) in an electric dryer.
A heat treatment was performed at 00 ° C. for 30 minutes to obtain a test piece.

Example 4 Alkylene oxide polymer (B-10) 50 shown in Table 1
0 g in 25 g of lithium perchlorate
g, and the mixture was stirred to obtain a uniform solution. Then, methanol was added under reduced pressure to obtain a complex.

2 g of this complex and 1 kg of polypropylene resin
Was kneaded at 180 ° C. for 10 minutes using a twin-screw extruder, and was molded in exactly the same manner as in Example 1 to obtain a molded product (230 m
m × 230 mm × 3 mm) was heated at 110 ° C. for 10 minutes. Next, the surface of the molded body was subjected to a plasma treatment for 1 minute at a gas flow rate of 6.75 liter / minute, 89 volume% of oxygen, 11 volume% of nitrogen, a pressure of 0.2 mmHg, a temperature of 40 ° C. and an output of 1,200 W for 1 minute. It was created.

Comparative Example 1 1 kg of a polypropylene resin was mixed with a twin-screw extruder for 180
Kneaded at 10 ° C. for 10 minutes, and molded in exactly the same manner as in Example 1. The molded body (230 mm × 230 mm × 3 mm) was heated at 110 ° C.
For 10 minutes to obtain a test piece.

Comparative Example 2 A test piece was prepared in exactly the same manner as in Example 4 except that the heat treatment was not performed.

The surface resistance values of the test pieces obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured. The measurement is YHP
(Yokogawa Hewlett Packard) Super Insulation Resistance Meter 4
Using a 329A type, applying a voltage of 30
Performed seconds later. Table 2 shows the results.

[0041]

[Table 2]

The test pieces obtained in Examples 1 to 4 and Comparative Examples 1 and 2 had almost no difference in physical properties and appearance.

Example 5 The test piece obtained in Example 1 was grounded and the static voltage was
Urethane coating was performed with a coating machine (μμBEL30φ manufactured by Ransberg Gemma Co., Ltd.) at 30 kV, a reciprocating stroke of 400 mm, a spray distance of 300 mm, and a conveyor speed of 2.2 m / min.

Example 6 The test piece obtained in Example 4 was grounded and the static voltage was
Urethane coating was performed with a coating machine (μμBEL30φ manufactured by Ransberg Gemma Co., Ltd.) at 30 kV, a reciprocating stroke of 400 mm, a spray distance of 300 mm, and a conveyor speed of 2.2 m / min.

Comparative Example 3 The test piece obtained in Comparative Example 1 was grounded,
Urethane coating was performed with a coating machine (μμBEL30φ manufactured by Ransberg Gemma Co., Ltd.) at 30 kV, a reciprocating stroke of 400 mm, a spray distance of 300 mm, and a conveyor speed of 2.2 m / min.

Comparative Example 4 The test piece obtained in Comparative Example 2 was grounded,
Urethane coating was performed with a coating machine (μμBEL30φ manufactured by Ransberg Gemma Co., Ltd.) at 30 kV, a reciprocating stroke of 400 mm, a spray distance of 300 mm, and a conveyor speed of 2.2 m / min.

Table 3 shows the film thickness and the coating efficiency of the paints electrostatically coated in Examples 5 and 6 and Comparative Examples 3 and 4.

[0048]

[Table 3]

The film thickness was measured with the naked eye by observing the cross section with a microscope. The coating efficiency was determined from the relationship between the weight difference before and after coating and the absolute dry weight of the discharged paint according to the following equation. TP in the formula indicates a test piece.

(Equation 1)

[0050]

According to the present invention, a resin molded article having a significantly improved conductivity without substantially impairing the physical properties and hue of the resin by using a resin which has been known to have a problem in conductivity. Can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 23/02 H01B 1/06 A H01B 1/06 C08L 101/00 C08L 71:02 (72) Inventor Takao Nomura Toyota City, Aichi Prefecture 1 Toyota Town Inside Toyota Motor Corporation (72) Inventor Michiyuki Kono 14-1 Korihondoricho, Neyagawa-shi Shuichi No., Taura Port Town, Yokosuka City, Kanagawa Prefecture Kanto Automobile Industry Co., Ltd. (72) Inventor Ryosuke Sasaki No., Taura Port Town, Yokosuka City, Kanagawa Prefecture Kanto Automobile Industry Co., Ltd. (56) A) JP-A-3-95802 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 1/20 C08J 3/20 C08J 7/00 301 C08L 101/16 C08J 5/00 C08L 23/02 H01B 1/06 C08L 71:02

Claims (3)

(57) [Claims] 1. A resin molding material comprising at least one alkylene oxide polymer selected from the group consisting of homopolymers, block copolymers and random copolymers of alkylene oxide monomers, and an electrolyte soluble in these. A method for improving the conductivity of a resin molded product, comprising kneading a complex with a salt, molding a kneaded product thereof, and subjecting the surface of the obtained molded product to heat treatment. 2. The method for improving conductivity according to claim 1, wherein the heat treatment is performed at 60 to 150 ° C. for 1 to 60 minutes. 3. An alkylene oxide polymer and a soluble electrolyte
The amount of the complex with the salt is reduced to 100 parts by weight of the resin molded material raw material.
3. The method according to claim 1, wherein the amount is 0.1 to 10 parts by weight.
Conductivity improvement method.