JPH0157136B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing vinyl chloride polymer compositions containing carbon black. In recent years, there has been increasing interest in conductive plastics for use as electromagnetic shielding materials in electronics-related equipment that requires antistatic properties. Furthermore, carbon black is the most commonly used conductive material, except for special applications where transparency is required, because it is less expensive than other materials. However, conductive plastic materials made of vinyl chloride polymer as a matrix and carbon black dispersed therein are suitable for precision molding due to the dimensional stability of the molded product, except for soft materials containing a large amount of plasticizer. Moreover, although it is relatively inexpensive, its use is currently extremely limited. The reasons for this are, firstly, that the decomposition temperature of vinyl chloride polymer is low, making it impossible to mold it in the region of low melt viscosity like other polymers, and secondly, it is necessary to obtain conductivity. Generally, it is necessary to blend 8 to 15 percent by weight or more of carbon black, and it takes a considerable amount of kneading time to uniformly disperse it in the polymer, and the accompanying exothermic decomposition of the polymer can be avoided. There are some things that are missing. Also, as can be said for any polymer, carbon black, whose bulk specific gravity is extremely small and individual particles are around several hundred angstroms in size, especially carbon black for conductive materials, is extremely difficult to blend with polymers. It is a difficult task and is often avoided due to the work environment. On the other hand, it is also possible to add and mix carbon black to vinyl chloride monomer and then polymerize it to obtain a vinyl chloride polymer containing carbon black, but if the vinyl chloride polymer containing carbon black has a high degree of polymerization. However, the molding conditions range is not wide due to the large amount of heat generated by kneading, and in the case of a low degree of polymerization, Applications are limited due to the low mechanical strength of the molded product. As a result of intensive research in order to solve the above-mentioned problems, the inventors of the present invention have obtained carbon black by uniformly dispersing carbon black in vinyl chloride monomer or wetting it with vinyl chloride monomer, and then polymerizing the vinyl chloride monomer. By mixing a carbon black-containing vinyl chloride homopolymer with a vinyl chloride copolymer obtained by a suspension polymerization method or a bulk polymerization method having a higher degree of polymerization than the carbon black-containing vinyl chloride homopolymer, a preliminary preparation can be made. A carbon black-containing chloride with excellent processability that is suitable for extrusion molding, injection molding, etc., without the need for uniform dispersion treatment of carbon black such as kneading, and therefore without decomposition of the vinyl chloride polymer due to long-time kneading, etc. The present invention was achieved by obtaining a vinyl polymer composition. That is, the present invention provides a carbon black-containing vinyl chloride homopolymer obtained by adding and mixing carbon black to a vinyl chloride monomer and polymerizing the vinyl chloride homopolymer to a higher degree than the vinyl chloride homopolymer obtained by suspension polymerization or bulk polymerization. A method for producing a vinyl chloride polymer composition is characterized in that a small amount of a vinyl chloride copolymer is mixed at a certain temperature. The carbon black-containing vinyl chloride monopolymer used in the present invention is a vinyl chloride monopolymer made from carbon black produced by various manufacturing methods, including graphite such as furnace black, thermal black, and channel black (hereinafter collectively referred to as carbon black). After uniformly mixing and dispersing, bulk polymerization,
It is obtained by polymerization using methods such as suspension polymerization or emulsion polymerization. Next, in the present invention, the vinyl chloride copolymer to be blended with the carbon black-containing vinyl chloride polymer has a higher degree of polymerization than the carbon black-containing vinyl chloride polymer, and is produced by suspension polymerization or bulk polymerization. It is essential to obtain it legally. Furthermore, in the present invention, the vinyl chloride copolymer having a high degree of polymerization obtained by the above-mentioned suspension polymerization method or bulk polymerization method is obtained by adding carbon black to a monomer mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer. It may be added and polymerized in the same manner. Therefore, in the present invention, a vinyl chloride copolymer with a high degree of polymerization also means a vinyl chloride polymer containing carbon black during polymerization. Other monomers that can be copolymerized with vinyl chloride include olefin compounds such as ethylene and propylene; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated carboxylic acids and their esters such as acrylic acid and methacrylic acid; Examples include salts; unsaturated nitriles such as acrylonitrile; and vinyl halides other than vinyl chloride such as vinylidene chloride, but are not limited to these. The amount of this copolymerizable monomer is not particularly limited as long as it does not impair the properties of the vinyl chloride polymer. Next, the blending ratio of the carbon black-containing vinyl chloride polymer and the copolymers with a high degree of polymerization to be blended with it is determined by the ratio of the polymer components excluding the carbon black content of the former carbon black-containing chloride polymer. Per 100 parts by weight of vinyl polymer,
The latter copolymers may be present in an amount of 100 parts by weight or less;
It is preferably 3 parts by weight or more, generally 10 to 30 parts by weight. In this range, when blending and molding a vinyl chloride copolymer with a higher polymerization degree than the carbon black-containing vinyl chloride polymer or a carbon black-containing vinyl chloride copolymer, the former carbon black-containing Even if the average degree of polymerization of the polymers constituting the latter copolymers exceeds the average degree of polymerization of the polymer components in the vinyl chloride polymer, it is easy to obtain uniform conductivity when the melt viscosity is low. A molded product can be obtained. In order to use the vinyl chloride polymer composition obtained by the present invention particularly as a conductive material, the carbon black content may generally be adjusted to 5% by weight or more. The average degree of polymerization referred to in the present invention is based on JIS K-6721.
Due to the viscosity of copolymers,
It is expressed as a viscosity average degree of polymerization converted to vinyl chloride homopolymer. Polymerization data of carbon black-containing vinyl chloride polymers and examples of blends of these carbon black-containing vinyl chloride polymers are shown below, but the invention is not limited to these examples in any way, and In addition to various stabilizers, plasticizers, rubber components such as MBS, reinforcing agents such as chlorinated polyethylene and EVA, and carbon black, which can be added when molding ordinary vinyl chloride polymers, are added. Needless to say, it can be used in the same way. Sample Nos. 1 to 4 After thoroughly drying the inner wall of the polymerization can with an internal volume of 65,
After charging 1.5Kg of the polymerization reactor and purging the inside of the polymerization tank with nitrogen.
The pressure was reduced to 70 mmHg, and a predetermined amount of monomers such as vinyl chloride listed in Table 1 were introduced. After stirring for 20 minutes to mix Ketschien Black EC and the monomers, 20 g of Gohsenol KH-20 (partially saponified polyvinyl acetate, manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.), Metrose 90SH-100 (hydroxypropyl methyl cellulose, Shin-Etsu Chemical Co., Ltd.) 35 liters of deionized water in which 30 g of Polymer Co., Ltd. was dissolved and the polymerization initiator shown in Table 1 were introduced into a polymerization vessel. Polymerization was continued while stirring at the temperature shown in Table 1, and when the pressure inside the tank decreased to a predetermined pressure, unreacted monomers were purged to terminate the polymerization. The entire amount of the polymer slurry obtained by this suspension polymerization was dehydrated using a centrifugal dehydrator and then dried, and the polymerization rate and carbon black content were determined from the weight of the polymer. Sample No. 5 Put 200 g of Kettchen Black EC into a polymerization can with an inner volume of 5 and thoroughly dry the inner wall of the polymerization can. After purging the interior of the polymerization can with nitrogen, reduce the pressure to 70 mmHg and add 2.26 kg of vinyl chloride, 0.24 kg of propylene, and the starting material. Diisopropyl peroxydicarbonate as agent
11.0g was introduced. After raising the temperature inside the polymerization vessel to 46.5℃, it was held for 6 hours and 40 minutes until the pressure inside the polymerization vessel decreased.
When the pressure decreased to 7.0 Kg/cm ² , unreacted monomers were purged and the vacuum was maintained for an additional 10 minutes to remove adsorbed monomers. 1.26 kg of carbon black-containing vinyl chloride polymer powder was obtained by bulk polymerization. Polymerization data is also listed in Table-1.

【table】

[Table] Examples 1 to 5 and Comparative Example 1 Carbon black-containing polyvinyl chloride polymers obtained by suspension or bulk polymerization of Samples No. 2 to No. 5 were added to the carbon black-containing polyvinyl chloride polymer of Sample No. 1. Vinyl chloride-vinyl acetate copolymer or vinyl chloride-propylene copolymer and the average degree of polymerization obtained by suspension polymerization are blended with 820 vinyl chloride-vinyl acetate copolymer at the mixing ratio shown in Table 2, Roll molded. In addition, an example in which the carbon black-containing vinyl chloride polymer of sample No. 1 was roll-molded alone was used as a comparative example. As stabilizers, 2.0 parts by weight of dibutyltin mercaptan, 2.0 parts by weight of epoxy soybean oil, and 0.5 parts by weight of stearic acid were added to 100 parts by weight of the resin component excluding carbon black. Knead on a steam roll at 157℃, calculate the time required to wrap it around the roll,
After wrapping, kneading was continued for 5 minutes to create a sheet with a thickness of 1.1 mm. The flow characteristics of a small section of the sheet were measured using a Koka type flow tester, and the sheet was
The Kratschberg flexibility temperature and volume resistivity were determined for a 1.0 mm thick sheet that was pressed at 165°C for 20 minutes. The results obtained are listed in Table-2. Note that the flow characteristics were shown using a 1〓×10 nozzle at a temperature at which the resin flow rate was ×10 ⁻³ cm ³ /sec.

[Table] Examples 1 and 2 are examples in which a vinyl chloride/vinyl acetate copolymer containing carbon black is used as a copolymer component, and Example 3 is an example in which a vinyl chloride copolymer containing no carbon black is used as a copolymer component. This is an example using a polymer. Examples 4 and 5 are examples in which a vinyl chloride propylene copolymer containing carbon black is used as a copolymer component, and especially the latter Example 5 is an example in which a copolymer obtained by a bulk polymerization method is used. be. In each of the examples in which these copolymer components were blended, the roll winding time was shorter than in the comparative example in which the copolymer components were not blended and roll-formed, and the flow characteristics of the roll sheet sections were shorter. Things are also getting better. In addition, the softening temperature tends to be somewhat high, and the volume resistivity shows a value that depends on the carbon black content in the polymer composition.
No effect of blending was observed. Incidentally, the string-like extrudates of the flow tester exhibited gloss and uniform thickness in each of the Examples, but in the Comparative Examples, there was not much optical selection.

Claims (1)

[Scope of Claims] 1. A carbon black-containing vinyl chloride homopolymer obtained by adding and mixing carbon black to a vinyl chloride monomer has a higher polymer content than the vinyl chloride homopolymer obtained by a suspension polymerization method or a bulk polymerization method. A method for producing a vinyl chloride polymer composition, which comprises mixing a small amount of a vinyl chloride copolymer with a certain degree of polymerization. 2. The manufacturing method according to claim 1, wherein the carbon black-containing vinyl chloride homopolymer has an average degree of polymerization of 400 or more. 3. The manufacturing method according to claim 1, wherein the copolymerization monomer of the vinyl chloride copolymer with a high degree of polymerization is an olefin compound, vinyl esters, unsaturated carboxylic acids, esters or salts thereof. 4. A patent claim in which the amount of vinyl chloride polymer with a high degree of polymerization (excluding carbon black content) is 3 to 100 parts by weight per 100 parts by weight of vinyl chloride polymer containing carbon black (excluding carbon black content). The manufacturing method according to scope 1. 5 Content of vinyl chloride polymer composition is 5% by weight
The manufacturing method according to claim 1, which is the above.