JPH0635526B2 - Conductive resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conductive resin composition having excellent heat resistance, thermal stability, impact resistance, and good moldability.

(Prior Art) In the field of electronics, it has high conductivity in recent years,
Materials with excellent heat resistance, thermal stability, impact resistance, and good workability are required. Such materials include, for example:
For electronic devices, there are electromagnetic wave shielding materials that prevent electromagnetic interference and packaging materials for high-performance ICs.

As a material having conductivity, there is a composition in which a conductive material such as carbon black or metal powder is mixed with a thermoplastic resin such as polyethylene, polypropylene or vinyl chloride. In particular, a conductive resin composition using a vinyl chloride resin as a thermoplastic resin is widely used because it has good moldability, excellent mechanical strength, and is relatively inexpensive.

However, when such a conductive resin composition is used in the field of electronics, it is necessary to add a large amount of a conductive substance such as carbon black or metal powder in order to obtain a desired conductive effect. For example, even when a conductive material having a high conductivity effect such as Ketjen Black EC manufactured by Akzo is used, if 10 parts by weight of Ketjen Black EC is mixed with 100 parts by weight of vinyl chloride resin, the volume resistivity value becomes 10 ¹ ~10 ⁸ Ω · cm, and the is blended 20 parts by weight 10 ^0-1
It becomes 0 ³ Ω · cm. Therefore, in order to obtain a sufficient conductive effect, at least 10 parts by weight must be blended. When the conductive resin composition is used as an electromagnetic wave shielding material, higher conductivity is required, and therefore, the addition of the above conductive substance is required.

The conductive resin composition to which such a large amount of conductive material is added has a low fluidity when melted, and thus is difficult to mold. Physical properties such as heat resistance, thermal stability, and impact resistance of the molded product also deteriorate. In particular, carbon black acts to impede the thermal stability of vinyl chloride resin. Therefore,
Addition of a large amount of carbon black reduces the thermal stability of the conductive resin composition.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide excellent heat resistance, thermal stability, impact resistance, and good moldability. It is to provide a conductive resin composition.

(Means for Solving Problems) The present invention relates to a conventional carbon black-containing vinyl chloride resin by copolymerizing vinyl chloride with a polymerizable organosilicon compound and blending carbon black into the resulting copolymer. Compared with the above, it was completed based on the knowledge of the inventor that the fluidity at the time of melting is remarkably improved, the moldability is improved, and the heat resistance, thermal stability, and impact resistance can be maintained.

The conductive resin composition of the present invention contains a copolymer of a polymerizable organosilicon compound and vinyl chloride and carbon black, and thereby the above-mentioned object is achieved.

Organosilicon compounds, such as polysiloxanes, are used as internal lubricants in thermoplastic resins such as vinyl chloride resin. The thermoplastic resin containing polysiloxane has improved fluidity when melted due to the lubricating effect of polysiloxane, and has good moldability. Therefore, in the present invention, it was considered to improve the moldability of the conductive resin composition by using such an organosilicon compound. The bleeding is severe only by mixing the organic silicon compound with the vinyl chloride resin,
Therefore, the molded product becomes dirty. Therefore, by copolymerizing vinyl chloride and a polymerizable organosilicon compound and compounding the resulting copolymer with carbon black, a conductive resin composition with less bleed and good moldability can be obtained. It was Since the organosilicon compound is incorporated into the skeleton of the copolymer chain, phenomena such as bleeding do not occur easily. Moreover, since it is a copolymer mainly composed of vinyl chloride, the obtained conductive resin composition is excellent in heat resistance, heat stability and impact resistance.

In the copolymer, the polymerizable organosilicon compound unit is 0.1 ~
It is contained in an amount of 4% by weight, preferably 0.5 to 3.5% by weight. When it is less than 0.1% by weight, the moldability is hardly improved. If it exceeds 4% by weight, bleeding becomes severe and the molded product becomes dirty.

As the polymerizable organosilicon compound, polydimethylsiloxane having a polymerizable group capable of copolymerizing with vinyl chloride at the terminal is used, and examples thereof include polydimethylsiloxane having a methacryloxy group or an acryloxy group mycoloider vinyl group at the terminal. .

The copolymerization method of the polymerizable organosilicon compound and the vinyl chloride resin includes suspension polymerization method, emulsion polymerization method, solution polymerization method,
There is a bulk polymerization method. In particular, according to the suspension polymerization method, a fine particle copolymer is obtained, and this copolymer is easily mixed uniformly with carbon black. Therefore, the heat resistance, heat stability, and impact resistance of the obtained conductive resin composition are better than those of other polymerization methods. Therefore, it is preferable to adopt the copolymerization method by the suspension polymerization method. By the suspension polymerization method,
The copolymer is synthesized as follows.

Polymerizable organosilicon compound in the polymerization reactor with jacket,
Ion-exchanged water, a suspension stabilizer such as polyvinyl alcohol, a radical polymerization initiator and, if necessary, a polymerization degree reducing agent are added and suspended. Then, after eliminating the air in the can, vinyl chloride is pressed in. The inside of the can is heated by the jacket to start the copolymerization. Since heat is generated by the copolymerization reaction, the polymerization reaction is stopped at the desired degree of polymerization while cooling from the jacket. Unreacted vinyl chloride is removed to the outside of the can to obtain a slurry copolymer. The copolymer is dehydrated and dried, and then classified to obtain a fine particle copolymer.
In such a copolymerization reaction operation, the entire amount of the polymerizable organosilicon compound may be charged into the polymerization vessel before the reaction,
Moreover, you may add sequentially and continuously.

The copolymer thus obtained further contains carbon black for imparting conductivity. Carbon black is contained in the copolymer by kneading with a conventional mixer to give a conductive resin composition. Examples of carbon black include acetylene black, furnace black, thermal black, and lamp black. Commercially available products include Ketjen Black EC (trademark), Conductex 975 (trademark), Pentaku EBX (trademark), and Cappot CSX-150 (trademark). In particular, Ketjenblack EC and Cappot CSX-150 are conductive. It is preferable because it is excellent. Carbon black is contained in an amount of 5 to 40 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the copolymer. If the amount is less than 5 parts by weight, the desired conductive effect cannot be obtained. If it exceeds 40 parts by weight, the fluidity at the time of melting will be reduced, making molding difficult. Moreover, the physical properties such as heat resistance, thermal stability, and impact resistance of the molded product also deteriorate.

The copolymer blended in the conductive resin composition of the present invention,
An amount of a simple substance copolymerizable with vinyl chloride and / or a polymer capable of a graft reaction with vinyl chloride may be incorporated into the skeleton by the reaction. Such a monomer and / or polymer is blended in an amount of 10 parts by weight or less with respect to 100 parts by weight of vinyl chloride. When it exceeds 10 parts by weight, the ratio of the above-mentioned monomer and / or polymer to vinyl chloride becomes high, and the heat resistance, heat stability and impact resistance of the obtained conductive resin composition deteriorate. Monomers copolymerizable with vinyl chloride include α-, such as ethylene and propylene.
Examples include olefins, alkyl vinyl ethers, alkyl (meth) acrylates, vinyl esters and alkyl vinyl esters. Examples of the polymer that can be graft-reacted with vinyl chloride include a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and acrylic ester, polyvinyl acetate, and chlorinated polyethylene.

(Examples) The present invention will be described below with reference to Examples.

Example 1 (1) Synthesis of Copolymer Inside a jacketed polymerization reaction vessel equipped with a stirrer (pressure resistance 60 kg / c
A polymerizable organic silicon compound represented by the formula I, ion-exchanged water, a poval-based dispersant, and an organic peroxide as a radical polymerization initiator were put in and suspended in m ² G and an internal volume of 160 liters). . After sealing and removing the air in the can,
Vinyl chloride was pressed in. The inside of the can was heated to 74 ° C by the jacket, and the copolymerization reaction was carried out at this temperature for 10 hours, then the reaction was stopped. After completion of the polymerization reaction, unreacted vinyl chloride was removed into the can to obtain a slurry copolymer. The copolymer was dehydrated and dried, passed through a 42-mesh sieve to remove coarse particles, and only the fine-particle copolymer was recovered. 0.5% by weight of the polymerizable organosilicon compound in the obtained copolymer.
It contained 99.5% by weight of vinyl chloride, and its average degree of polymerization was 500.

I. FM 0721 (manufactured by Chisso Co., average molecular weight 5000) n = 60 to 65 (2) Blending of carbon black Carbon black, a stabilizer and a lubricant were blended in the following proportions to the copolymer obtained in (1). .

Copolymer 1500 g (100 parts by weight) Ketjen Black EC (carbon black, manufactured by Akzo) 300 g (20 parts by weight) Dibutyltin mercapto (stabilizer) 20 g (1.3 parts by weight) Dibutyltin malate (stabilizer) 10 g (0.7 parts by weight) Part by weight) Amide-based lubricant 23 g (1.5 parts by weight) Monoglyceride-based lubricant 23 g (1.5 parts by weight) A predetermined amount of the copolymer was placed in a 10 liter Henschel mixer and uniformly dispersed at 100 ° C. The above stabilizer and lubricant were added to this and mixed at 100 ° C for 10 minutes. The mixture was cooled to give a conductive resin composition.

(3) Physical Properties Test of Conductive Resin Composition 300 g of the composition obtained in (2) was kneaded with an 8-inch twin roll to obtain a sheet having a thickness of 0.5 mm. This sheet was sandwiched between ferrotype plates and pressed into a smooth plate with a thickness of 1 mm. Using this molded plate, the fluidity, heat resistance, thermal stability, impact resistance, conductivity, and bleed resistance of the conductive resin composition during melting were tested as follows.

Flowability during melting: The above sheet was cut into 2 mm square pieces and placed in a high-lower flow tester. The flow rate of the composition per unit time was measured under the conditions of a pressure of 150 kg / cm ² and a temperature of 180 ° C. using a 1φ × 10 mm nozzle.

Heat resistance; ASTM D-648 (load 18.6k)
Heat resistance was tested by the method of g).

Thermal stability: The above sheet was heated in a gear oven at 180 ° C, and the thermal stability was evaluated from the time required for foaming.

Impact resistance: The molded plate was used as a test piece of 2 cm × 2 cm, and the impact resistance was evaluated under the following conditions using a DuPont impact tester.

Hammer 1 / 2R Hammer base Flat weight 300g Drop height 2.5cm Measurement temperature 20 ℃ Impact was applied to the test piece under the above conditions, and the impact resistance was numerically compared based on the following criteria. Similar values were obtained for 12 test pieces, and the average value was calculated.

3: Not cracked 2: Cracked 1: Cracked but not scattered 0: Scattered conductivity: The molded plate was used as a test piece with a width of 10 mm and a length of 70 mm.
Both ends 10 mm in the length direction of the test piece were washed with methanol. Apply silver paste paint to the washed part, 20 ℃, 50RH%
Left for 24 hours in the atmosphere. After that, a DC voltage was applied to the coated part and the volume resistivity was measured to evaluate the conductivity.

Bleedability: the above-mentioned molded plate in an atmosphere of 20 ° C and 50RH%
After standing for 48 hours, the protruding state of the lubricant etc. on the surface of the molded plate was visually observed. The surface condition was divided into the following three stages, and the bleeding property was evaluated.

A: No embossing B: Small amount of embossing C: Large amount of embossing Physical properties evaluated in this way are shown in Table 1.

Example 2 A copolymer was synthesized in the same manner as in Example 1 except that 2.0% by weight of the polymerizable organosilicon compound and 98.0% by weight of vinyl chloride were contained in the copolymer, and the obtained copolymer was obtained. A carbon black, a stabilizer and a lubricant were blended into the united material (average degree of polymerization of 500) to obtain a conductive resin composition. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Example 3 except that the compound represented by the formula II was used as the polymerizable organosilicon compound and 96.0% by weight of vinyl chloride was contained in the copolymer in an amount of 4.0 parts by weight of the polymerizable organosilicon compound. A copolymer was synthesized in the same manner as in 1, and carbon black, a stabilizer and a lubricant were added to the obtained copolymer (average degree of polymerization: 500) to give a conductive resin composition. A physical property test was performed on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 1.

II. FM 0711 (manufactured by Chisso Co., average molecular weight 1000) m = 7 to 11 Example 4 Using a compound represented by the formula III as the polymerizable organosilicon compound, 2.0% by weight of the polymerizable organosilicon compound in the copolymer and chlorination A copolymer was synthesized in the same manner as in Example 1 except that 98.0% by weight of vinyl was added, and the obtained copolymer (average degree of polymerization: 500) was mixed with carbon black, a stabilizer and a lubricant. It was a conductive resin composition. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 1.

III l, m, and n are integers PS408 (manufactured by Chisso Co., viscosity 50cs) Example 5 2.0% by weight of ethylene was used as a monomer copolymerizable with vinyl chloride, and a polymerizable organosilicon compound was used.
A copolymer was synthesized in the same manner as in Example 1 except that 2.0 wt% and 96.0 wt% of vinyl chloride were contained, and the obtained copolymer (average degree of polymerization: 500) was supplemented with carbon black, a stabilizer and A lubricant was blended to obtain a conductive resin composition. Ethylene was pressed into the polymerization reactor together with vinyl chloride. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 1.

Example 6 Except that 3.0% by weight of EVA shown below as a polymer capable of graft-reacting with vinyl chloride, 2.0% by weight of a polymerizable organosilicon compound and 95.0% by weight of vinyl chloride were contained in the copolymer. A copolymer was synthesized in the same manner as in Example 1, and the obtained copolymer (average degree of polymerization: 500) was mixed with carbon black, a stabilizer and a lubricant to give a conductive resin composition. EVA was put in a polymerization reaction can together with the polymerizable organosilicon compound. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1.
The results are shown in Table 1.

EVA: Copolymer of ethylene and vinyl acetate, Levapren 450N (manufactured by Bayer GmbH, West Germany) Copolymer chain has a vinyl acetate unit content of 45% by weight and a melt index of 2.

Example 7 In the copolymer, 2.0% by weight of propylene as a monomer copolymerizable with vinyl chloride, 3.0% by weight of EEA shown below as a polymer capable of graft reaction with vinyl chloride, a polymerizable organosilicon compound 2.0 wt% and vinyl chloride 93.
A copolymer was synthesized in the same manner as in Example 1 except that the content was 0% by weight. The resulting copolymer (average degree of polymerization 50
Carbon black, a stabilizer and a lubricant were mixed with 0) to prepare a conductive resin composition. Propylene was pressed into the polymerization reactor together with vinyl chloride. EEA was put in a polymerization reaction can together with the polymerizable organosilicon compound. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 1.

EEA: a copolymer of ethylene and ethyl acrylate,
A-708 (manufactured by Mitsui Polychemical Co., Ltd.) The ratio of ethyl acrylate units in the copolymer chain is 40% by weight, and the melt index is 7.

As is clear from Table 1, as the compounding amount of the polymerizable organosilicon compound with respect to vinyl chloride increases, the fluidity at the time of melting improves, and the heat resistance, heat stability, and impact resistance are improved. However, bleeding occurs when the amount of the polymerizable organosilicon compound is 4% by weight. Also, formula II, II
Even when the polymerizable organosilicon compound represented by the formula I is used, the fluidity and impact resistance during melting are improved. A composition obtained by copolymerizing a polymerizable organosilicon compound and a monomer other than vinyl chloride has improved fluidity during melting, and a composition obtained by graft-reacting another polymer has improved heat resistance.

Comparative Example 1 A conductive resin composition was prepared in the same manner as in Example 1 except that a vinyl chloride homopolymer (polymer 500) was used in place of the copolymer of the polymerizable organosilicon compound and vinyl chloride. Obtained. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2 A copolymer obtained by synthesizing a copolymer in the same manner as in Example 1 except that the copolymer contained 5.0% by weight of a polymerizable organosilicon compound and 95.0% by weight of vinyl chloride. A polymer (average degree of polymerization: 500) was mixed with carbon black, a stabilizer and a lubricant to prepare a conductive resin composition. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3 Instead of the copolymer of the polymerizable organosilicon compound and vinyl chloride, a copolymer of ethylene and vinyl chloride (the proportion of ethylene in the copolymer was 2% by weight and the degree of polymerization was 480) was used. A conductive resin composition was obtained in the same manner as in Example 1 except that it was used. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 2.
Shown in.

Comparative Example 4 Instead of a copolymer of a polymerizable organosilicon compound and vinyl chloride, a graft polymer of EVA and vinyl chloride (the proportion of EVA in the graft polymer is 3% by weight and the degree of polymerization is 500) is used. A conductive resin composition was obtained in the same manner as in Example 1 except that it was used. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 5 Vinyl chloride homopolymer used in Comparative Example 1 (degree of polymerization: 500)
A conductive resin composition was prepared in the same manner as in Example 1 except that 2 parts by weight of polydimethylsiloxane (KF-96, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity: 50 cs) was added to 98 parts by weight. Obtained. A physical property test was conducted on this conductive resin composition in the same manner as in Example 1. The results are shown in Table 2.
Shown in.

As is clear from Table 2, the conductive resin compound using a vinyl chloride homopolymer, a copolymer of ethylene and vinyl chloride, and a graft polymer of EVA and vinyl chloride is more excellent than the composition of the present invention. ， The fluidity during melting is extremely low.
A composition containing 5% by weight of a polymerizable organosilicon compound is
It has good fluidity when melted and has excellent heat resistance, thermal stability, and impact resistance, but bleeding is severe. In addition, the composition obtained by blending polydimethylsiloxane with a homopolymer of vinyl chloride has lower fluidity when melted than that of the composition of the present invention, and is inferior in heat resistance, thermal stability, and impact resistance. Is intense.

(Effects of the Invention) As described above, the conductive resin composition of the present invention has good flowability during melting and thus has good moldability and excellent heat resistance, thermal stability, and impact resistance. Bleed phenomenon hardly occurs. Moreover, it has high conductivity. Therefore,
The composition of the present invention can be effectively used for a recording medium such as a magnetic disk.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mutsuaki Nakamura 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan (72) Inventor Akira Nishizawa 3-12 Moriya-cho, Kanagawa-ku, Yokohama Address: Within Victor Company of Japan, Ltd. (72) Noboru Kawai, 3-12 Moriya-cho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture: Address: Within Victor Company of Japan (72) Toshiaki Hamaguchi, 3--12 Moriya-cho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Address inside Victor Company of Japan (72) Inventor Toshio Akai 3-12 Moriya-cho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Inside Victor Company of Japan (56) Reference JP-A-61-42519 (JP, A) 61-44952 (JP, A) JP 61-118451 (JP, A) JP 59-166514 (JP, A)

Claims (5)

[Claims] 1. A conductive resin composition containing a copolymer of a polymerizable organosilicon compound and vinyl chloride and carbon black. 2. The conductive resin composition according to claim 1, wherein the polymerizable organosilicon compound unit is contained in the copolymer in a range of 0.1 to 4% by weight. 3. The conductive resin composition according to claim 1, wherein the polymerizable organic silicon compound is a polydimethylsiloxane having a terminal polymerizable group with vinyl chloride. 4. The conductive resin composition according to claim 1, wherein the carbon black is contained in the range of 5 to 40 parts by weight with respect to 100 parts by weight of the copolymer. 5. The vinyl chloride, in addition to the polymerizable organosilicon compound and vinyl chloride, is a monomer copolymerizable with vinyl chloride and / or a polymer graft-reactive with vinyl chloride. The conductive resin composition according to claim 1, which is obtained by mixing and reacting with 100 parts by weight in the range of 10 parts by weight or less.