JPS5975939A - Production of vinyl chloride polymer composition - Google Patents

Abstract

PURPOSE:To obtain the titled compsn. suitable for use as an electromagnetic shielding material and having excellent processability, etc., by mixing a carbon black-contg. vinyl chloride polymer with a small quantity of a vinyl chloride polymer having a degree of polymerization lower than that of the above polymer. CONSTITUTION:At least 5wt% carbon black such as furnace black is uniformly dispersed in vinyl chloride monomer. The monomer is polymerized by bulk polymn., suspension polymn. or emulsion polymn. to prepare carbon black- contg. vinyl chloride polymer having an average degree of polymn. of 500 or above. 3-100pts.wt. vinyl chloride polymer having a degree of polymn. lower than that of said carbon black-contg. vinyl chloride polymer, pref. a degree of polymn. of 100-500 and optionally stabilizer, plasticizer, etc. are blended with 100pts.wt. (excluding the quantity of carbon black) said carbon black-contg. vinyl chloride polymer to obtain the desired vinyl chloride polymer compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vinyl chloride polymer composition containing carbon black.

In recent years, there has been increasing interest in conductive plastics for use in electronics-related equipment and electromagnetic shielding materials that require 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, as a conductive plastic, a material made of vinyl chloride polymer as a matrix and carbon black dispersed therein is suitable for precision molding due to the dimensional stability of the molded product, except for soft applications that contain plasticizer in many vertical directions. 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, so it is impossible to mold it in the low melt viscosity region like other polymers, and secondly, it is necessary to obtain conductivity. In order to achieve this, it is generally necessary to blend carbon black in an amount of 8 to 15 weight or more, and it takes a considerable amount of kneading time to uniformly disperse it in the polymer, which reduces the heat generated by the polymer.・Decomposition is unavoidable and also leads to a decrease in conductivity. Furthermore, as is the case with any polymer, it is extremely difficult to blend carbon black with polymers, especially carbon black for conductive materials, which has an extremely small bulk specific gravity and each particle is around several hundred angstroms. It is a difficult task and is often avoided due to the work environment.

On the other hand, carbon black is added to vinyl chloride monomer.
After mixing, it is possible to polymerize to obtain a vinyl chloride polymer containing carbon black, but in order to obtain a vinyl chloride polymer containing carbon black with a high degree of polymerization, it is necessary to perform polymerization at the above-mentioned stage of the vinyl chloride polymer. Although it is significantly improved compared to blending carbon black, it cannot be said that the range of molding conditions is wide because the heat generated by crosstalk is large, and if the degree of polymerization is low, the mechanical strength of the molded product is even lower. There are restrictions on

As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a carbon black-containing vinyl chloride polymer obtained by uniformly dispersing carbon black in a vinyl chloride monomer and then polymerizing a vinyl chloride monomer, By mixing a vinyl chloride polymer having a lower degree of polymerization than the vinyl chloride polymer with a polymer obtained by polymerizing a vinyl chloride monomer in which a vinyl chloride polymer is uniformly dispersed, a treatment step for uniformly dispersing carbon black such as pre-mixing is not necessary. The present invention has been achieved by obtaining a carbon black-containing vinyl chloride polymer composition that is suitable for extrusion molding, injection molding, etc. and has excellent processability and is free from decomposition of the polymer due to long-term crosstalk. That is, the present invention involves mixing a small amount of a vinyl chloride polymer having a lower degree of polymerization than the vinyl chloride polymer into a carbon black-containing vinyl chloride polymer obtained by adding and mixing carbon black to a vinyl chloride monomer. This is a characteristic method for producing a vinyl chloride polymer composition.

The carbon black-containing vinyl chloride polymer used in the present invention is carbon black produced by various manufacturing methods such as furnace black, thermal black, channel black, or graphite (hereinafter collectively referred to as carbon black), and vinyl chloride monomer alone, ／Mo／? - and other monomers copolymerizable with the monomer (also referred to as vinyl chloride monomer in this invention). This is a polymer obtained by 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; Salts; examples include, but are not limited to, unsaturated dichloromethane such as acrylonitrile and vinyl halides other than vinyl chloride such as vinylidene chloride. In addition, a vinyl chloride polymer having a lower degree of polymerization than the carbon black-containing vinyl chloride polymer mentioned above refers to a monomer containing chloride and a vinyl monomer alone or a mixture of a vinyl chloride monomer and other monomers that can be copolymerized with the monomer. In addition to polymers obtained by polymerizing by bulk polymerization, suspension polymerization, or emulsion polymerization (also referred to as vinyl chloride monomer), carbon black can also be added and mixed with the monomer (6). A carbon black-containing vinyl chloride polymer (also referred to as a low degree of polymerization vinyl chloride polymer in the present invention) is used.

Next, the average degree of polymerization of the carbon black-containing vinyl chloride polymer and the low-degree of polymerization vinyl chloride polymer blended with the polymer is 500 or more, compared to the polymer constituting the former carbon black-containing polymer. The latter polymers are 10
Preferably, the value is between 0 and 500. In addition, the average degree of polymerization referred to in the present invention is based on JIBK-6721,
For copolymers, the viscosity average degree of polymerization is also expressed in terms of a vinyl chloride homopolymer. Average degree of polymerization 50
0 or more carbon black-containing vinyl chloride polymer (hereinafter also referred to as a high degree of polymerization component) and an average degree of polymerization of 100 to 500.
The blending ratio of the vinyl chloride polymer (including carbon black-containing vinyl chloride polymer) is the ratio of the vinyl chloride polymer portion excluding the carbon black contained, and is the ratio of the low polymerization degree component per 100 parts by weight of the high polymerization degree component. is preferably 100 parts by weight or less, preferably 6 parts by weight or more, generally 10 to 30 parts by weight of the low polymerization degree component per 100 parts by weight of the high polymerization degree component.

In order to use the vinyl chloride polymer composition obtained according to the present invention as a conductive material, the carbon black content is generally adjusted to 5% by weight or more. In addition, various stabilizers, plasticizers, rubber components such as ABS, MBS, reinforcing agents such as chlorinated polyethylene 7, EVA, etc. may be added to these carbon black-containing vinyl chloride polymers, or carbon black may be further added. Needless to say, substances that can be added during molding of ordinary vinyl chloride polymers can also be used in the same way.

Hereinafter, polymerization data of carbon black-containing vinyl chloride polymers and examples of blends of these carbon black-containing vinyl chloride polymers will be shown, but the present invention is not limited to these examples.

A polymerization can with a jacket and a paddle-type stirrer having an internal polymerization volume of 65 liters for Samples 41 to A8 was used. After thoroughly drying the inner wall of the polymerization can,
Ketjen Black EC (manufactured by Lion Akzo) 1.5
After charging Kf and replacing the inside of the polymerization reactor with nitrogen, 70+a+H
The pressure was reduced to f and predetermined amounts of vinyl chloride monomer or vinyl chloride monomer and propylene as shown in Table 1 were introduced.

After stirring for 20 minutes to mix Ketjenblack EC and the monomers, Gohsenol KH-20 (partially saponified polyvinyl acetate, manufactured by Nippon Gosei Kagaku Kogyo ■) 20? , 65 liters of deionized water in which Metrose 90SH-I DO (hydroxypropyl methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd.) 602 had been dissolved and dispersed, and the polymerization initiators shown in Table 1 were introduced into the polymerization vessel in the specified amounts. Polymerization is carried out under stirring at the polymerization temperature listed in Table 1, and the polymerization is terminated when the pressure inside the reactor drops to a predetermined pressure. After purging unreacted monomers, the polymer slurry is centrifuged (9). was transferred to dehydrated and dried. After drying, the weight was measured to determine the polymerization rate and carbon black content in the polymer. The polymerization rate represents the ratio of the total weight of the polymer to the weight of the charged monomers minus the weight of the charged Ketjen Black EC, and the carbon black content represents the ratio of the weight of the charged carbon black to the total weight of the polymer.

Polymerization of Sample A9 Polymerization was carried out at the same polymerization temperature as Sample A6 at 5° without adding Ketjen Black EC in the polymerization can used for polymerizing Samples 1 to 4B. In addition, the dispersant is KH-20.
, 90SH-100 is used for 52. The main physical properties of the obtained polymer are also listed in Table 1.

1. Margin (10) Examples 1 to 9. Comparative Examples 1-5 and Reference Examples 1-2 Sample A1
~Average degree of polymerization of A4 and A7 1000.670 and 8
Samples A5, A<S, A8 and A9 average polymerization IE of about 450 and 490 carbon black-containing vinyl chloride polymers, vinyl chloride homopolymer Alternatively, a vinyl chloride-ethylene copolymer (E430 manufactured by Sankagaku Co., Ltd. with a polymerization degree of 457:8) was used as a low polymerization degree component and blended with the composition shown in Table 2. As stabilizer components, 2.0 parts by weight of diptyltin mercaptan, 2.0 parts by weight of epoxy soybean oil, and 0.5 parts of stearic acid were added to 100 parts by weight of the resin component excluding carbon black. Knead with a steam roll at 157°C, determine the time (seconds) required for wrapping around the roll,
After rolling 4, kneading was continued for 5 minutes to produce a sheet with a thickness of 1.1 cm. The flow characteristics of a small section of the sheet were measured using a Koka type flow tester, and the sheet was tested at 165°C for 2 hours.
12) (11) The Kratschberg flexibility temperature and volume resistivity were determined for a 1 inch thick sheet that had been pressed for 0 minutes. The results obtained are listed in Table 2.

In addition, the results when Samples 1 to A4 and A7, which are carbon black-containing vinyl chloride polymers used as high polymerization degree components, were used alone are shown as Comparative Examples 1 to 5, respectively, and as low polymerization degree components. The results when the carbon black-containing vinyl chloride polymer sample A5 used was used alone and the results when 15.5 weight percent of Ketjen black EC was blended with the vinyl chloride polymer sample M9, which was also used as a low degree of polymerization component. The results are shown in Reference Example 1. It is also listed in Table 2 as Reference Example 2.

In addition, the flow characteristics are 1φ in the Koka type flow tester.
Resin flow rate is 2 x 10-'c using x10 nozzle
It is expressed as the temperature at which j/sθC is obtained.

(13) Examples 1 to 4 and Comparative Example 1 in Table 2. From the results of Examples 5 to 7, Comparative Examples 2 to 4, and Example 8.9 and Comparative Example 5,
The time required for winding into a roll (N1) is longer when blending and molding a vinyl chloride polymer with a low degree of polymerization or a vinyl chloride polymer containing carbon black than when molding with a high degree of polymerization component of a vinyl chloride polymer containing carbon blank alone. is short, and the flow temperature of those roll sheet pieces is low,
It is clear that moldability is considerably improved. Moreover, there is hardly any decrease in the softening temperature due to blending.

In addition, the string-like extrudates in the flow tester were obtained with a glossy and uniform thickness in each of the Examples, but in each Comparative Example, the thickness was uniform but not very shiny, and in Reference Example 2, The thickness is uneven, there are occasional bends and cuts, and of course there is no luster. In Reference Example 1, a string-like extrudate was obtained from each of the pots of the Examples, but the mechanical strength such as the softening temperature was insufficient.

(15) Although the volume resistivity depends on the amount of carbon black contained and is not affected by blending, in the case of Reference Example 2, there was a large variation depending on the measurement specimen.

patent applicant Sun Arrow Chemical Co., Ltd. (16)

Claims (1)

[Claims] 1) [A small amount of a vinyl chloride polymer having a lower degree of polymerization than the vinyl chloride polymer is mixed with a carbon black-containing vinyl chloride polymer that is polymerized by adding carbon black to a vinyl chloride monomer. A method for producing a vinyl chloride polymer composition, characterized in that: 2) The average degree of polymerization of the carbon-containing vinyl chloride polymer is 50
The manufacturing method according to claim 1, wherein the amount is 0 or more. 3) The average degree of polymerization of the vinyl chloride polymer, which has a low degree of polymerization, is 1.
00 to 500. The manufacturing method according to claim 1. 4) Vinyl chloride polymer (excluding carbon black content) with a low degree of polymerization relative to 100 parts by weight of carbon blank-containing vinyl chloride polymer (excluding carbon black content) S-・5) Vinyl chloride Claim 1, wherein the carbon black content of the polymer composition is 5% by weight or more.
Manufacturing method described in section.