JPS6050377B2 - Method for producing vinyl chloride polymer composition with high volume resistivity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vinyl chloride polymer composition having a high volume resistivity.

Vinyl chloride polymer (hereinafter abbreviated as PVC) is originally a plastic with a high volume resistivity and is commonly used as an electrical insulating material, but its volume resistivity decreases due to trace amounts of metal compounds mixed in during its manufacturing process. .

For example, sodium ion N is a common causative metal.
I can give you a. Since it is common practice to use a caustic sorter in the vinyl chloride purification process, it is extremely difficult to avoid contamination of trace amounts of sodium ions (Na) into the vinyl chloride. Furthermore, it is actually impossible to completely prevent the contamination of other metal ions. It is also known to increase the volume resistivity by adding clay, but this has the effect of reducing other properties and does not result in a PVC composition with satisfactory performance. As a result of detailed study on a method for obtaining PVC with high volume resistivity, the present inventors found that if a specific amount of a copolymer of alkyl vinyl ether and maleic anhydride is added at a specific time during suspension polymerization of vinyl chloride, The inventors have discovered that the volume resistivity of the resulting PVC is greatly improved, and have arrived at the present invention.

That is, the present invention uses a copolymer of alkyl vinyl ether and maleic anhydride in an amount of 10 to 50% relative to the raw material monomer.
00 ppm vinyl chloride is added after the start of polymerization and before the dehydration step of the polymerization suspension.

Copolymers of alkyl vinyl ether and maleic anhydride used in the present invention include copolymers of alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, and stearyl vinyl ether, and maleic anhydride. Copolymers can be mentioned.

It is not clear why the volume resistivity of the resulting PVC improves when a specific amount of such a copolymer of alkyl vinyl ether and maleic anhydride is added, but the reason is that the carboxylic acid groups of the copolymer have metal ions, especially sodium ions, Na. It can be thought that this is to shield the . Regarding the polymerization degree of the molecule of the copolymer of alkyl vinyl ether and maleic anhydride used in the present invention, the specific viscosity of a 1% methyl ethyl ketone solution of the copolymer measured at 25° C. is 0.05 to 4.5.

Further, the monomer ratio in the copolymer of alkyl vinyl ether and maleic anhydride is not particularly limited, but is preferably 30 to 70 mol% and 70 to 30 mol%, respectively, and particularly preferably a substantially equimolar ratio. In the case of an aqueous suspension polymerization method, in order to uniformly disperse the copolymer in PVC, it is preferable to add the copolymer after the start of polymerization of vinyl chloride and before the dehydration step of the polymerization suspension. In particular, in the case of aqueous suspension polymerization, if it is added after the polymerization has progressed and the polymerization rate exceeds 20% and the formation of polymer particles has finished, the formation of coarse polymer particles, general increase in particle size, etc. This is preferable because it avoids the phenomenon of
In addition, when adding to the polymerization suspension obtained after the completion of polymerization, it is desirable to stir sufficiently after addition in order to uniformly disperse the copolymer of alkyl vinyl ether and maleic anhydride. In the present invention, the amount of the copolymer of alkyl vinyl ether and maleic anhydride added is 10 to 5000 ppm, particularly preferably 20 to 1000 ppm, based on the raw material monomer. At less than 10 ppm, the volume resistivity ratio is only slightly improved, and at 5000 ppm
If it exceeds m, other physical properties of the obtained PVC deteriorate, making it impractical.

The method for producing the vinyl chloride polymer composition of the present invention is carried out together with suspension polymerization of vinyl chloride. Preferably, in the suspension polymerization, any dispersant commonly used in the polymerization of vinyl chloride polymers may be used, such as partially saponified polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose,
Hydroki. Examples include ethylcellulose and gelatin, and these can be used alone or in combination.

As for the polymerization catalyst, any catalyst commonly used for bulk and suspension polymerization of vinyl chloride may be used, such as lauroyl peroxide, t-butyl peroxypivalate,
There are organic peroxides such as diisopropyl peroxydicarbonate, azonitrile such as α・α″-azobis, isobutyronitrile, 2,2″-azobis-2,4-dimethylvaleronitrile, and these can be used alone or in combination. Can be used.

In the present invention, in addition to vinyl chloride, olefins such as ethylene and propylene, which are monomers copolymerizable with vinyl chloride, vinyl esters such as vinyl acetate and vinyl propionate, acrylic acid, methacrylic acid and their esters, maleic acid, etc. Acids, fumaric acid and its esters, and alkyl vinyl ethers may coexist.

For the above-mentioned suspension polymerization and post-treatment of vinyl chloride, conventionally known conditions can be used, except for the addition of a copolymer of alkyl vinyl ether and maleic anhydride.

The composition obtained by the production method of the present invention may optionally contain plasticizers, other resins, stabilizers, lubricants, fillers, ultraviolet absorbers, antioxidants, pigments, flame retardants, and hydrogen chloride neutralizers. etc. can be optionally added in a conventionally known blending ratio.

Examples of plasticizers that can be added include phthalate esters, adipate esters, phosphate plasticizers, polyester plasticizers, trimellitic acid esters, and chlorinated paraffins.

Examples of other resins that can be added include resins mainly composed of vinyl chloride (which may be homopolymerized resins, copolymerized resins with other monomers, or graft copolymerized resins), or ethylene vinyl. Any resin may be added as long as it is compatible with vinyl chloride resin, such as acetate copolymer resin.

Conventionally known substances can be used as fillers, flame retardants, and hydrogen chloride neutralizers, such as antimony trioxide, ammonium bromide, guanidyl nitrogen compounds,
Borax, ammonium sulfate, calcium carbonate, kaolin,
Examples include gypsum, titanium oxide, magnesium hydroxide, and calcium silicate.

Stabilizers include lead-based stabilizers such as tribasic lead sulfate and lead stearate, metal soap stabilizers such as calcium stearate and zinc stearate, octyltin mercaptide,
Examples include organotin stabilizers such as dibutyltin malate,
Further examples include co-stabilizers such as epoxy stabilizers, organic phosphite esters, aminocrotonate esters, 2-phenylindole, pentaerythritol, sorbitol and phosphite chelators.

Examples of lubricants include hydrocarbon lubricants such as natural paraffin, liquid paraffin, and polyethylene wax, fatty acid lubricants such as stearic acid, fatty acid amide lubricants such as stearamide, ester lubricants such as ethylene glycol monostearate, and stearyl alcohol. Examples include higher alcohol-based lubricants such as, and metal soap-based lubricants such as calcium laurate. Examples of UV absorbers include benzophenone-based UV absorbers such as 2,4-dihydroxypenzophenone, benzotriazole-based UV absorbers such as 2-(2''-hydroxy-5''-methylphenyl)benzotriazole, and salicylic acid ester-based UV absorbers such as phenyl salicylate. can give.

As an antioxidant, 2,2″-methylene bis(4
-methyl-6-tert-butylphenol), monophenol-based antioxidants such as 2,6-ditertiary-butylphenol, and hydroquinone-based antioxidants such as 2,5-ditertiary-butylhydroquinone.

Examples of pigments include carbon black, titanium oxide, barium sulfate, and the like.

The composition produced according to the present invention is prepared by adding various necessary additives, such as plasticizers, stabilizers, fillers, lubricants, flame retardants, pigments, etc., using a conventionally known method using a Panbury mixer, a Henschel mixer, etc. After simply mixing them uniformly, they are molded by various conventionally known molding methods and put into practical use.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

None of these are intended to limit the scope of the invention. In addition, throughout the Examples and Comparative Examples, vinyl chloride-based polymer compositions (hereinafter simply referred to as PVC) were used.

) was measured by the following method. Also, parts represent weight. (a) Volume resistivity: 50 parts of dioctyl phthalate (DOP) and 3 parts of tribase (tribasic lead sulfate) were added to 1 part of PVCl, and the mixture was kneaded for 7 minutes with a mixing roll at 150°C and taken out. , a sheet with a weight of 0.5 was obtained.

A DC voltage of 500 rT1V was applied to this sheet to determine the volume resistivity (according to the method of JIS K6723).The value is expressed in Ωα. (b) Light transmittance: 2 parts of tin mercaptide and 0.5 part of stearic acid were added to the PVCl beaten part.

This mixture was kneaded with a mixing roll at 150'C for 10 minutes to obtain a sheet of 1.2 to 1.3 tons, which was then pressed to form a sheet.
It was set to 0 Tnm. The total light transmittance of this sheet is JISK
The measurement was carried out using an integrating sphere type light transmittance measuring device manufactured in accordance with Japanese Patent No. 16717. Numerical values are expressed as fractions (%).
(c) Haze value: Measured in the same manner as the light transmittance.

Values are expressed as fractions (%). (d) Particle size distribution: P
The VClOO portion was placed in a Tyler sieve and subjected to two crushing blows, and the weight of the PVC remaining on each sieve was measured to determine the particle size distribution.

Values are expressed in weight fraction (Wt%). Example 1 3000 ml of deionized water was placed in a stainless steel polymerization tank with an internal volume of 7 d.
K9, vinyl chloride 2000k9, t-butyl peroxypivalate 0.6kg, hydroxypropyl methylcellulose 0.5kg, and partially saponified polyvinyl alcohol with a saponification degree of 80 mol% 1.5k9 were charged and reacted at 57°C.
After the polymerization rate of the monomer exceeds 20% and particle formation is completed, a copolymer of methyl vinyl ether and maleic anhydride (1:1 molar ratio) having a specific viscosity of 0.4 at 25°C from a 1% solution of methyl ethyl ketone is added. 500 ppm of vinyl chloride was added in the form of an aqueous solution, and the reaction was continued until the pressure reached 5 kg/d.

After the reaction was completed, unreacted monomers were collected, and the polymer slurry was discharged, dehydrated and dried to obtain a product, and its volume resistivity and other physical properties were measured using the methods described above. The results are shown in Table 1.

Comparative Example 1 An experiment was conducted in the same manner as in Example 1, except that the copolymer of methyl vinyl ether and maleic anhydride was not added.

The results are shown in Table 1.

Comparative Example 2 An experiment was carried out in the same manner as in Example 1 except that the copolymer of methyl vinyl ether and maleic anhydride was added before polymerization.

The results are shown in Table 1.

In this comparative example, the PVC particles obtained are large and problematic.

That is, according to the method of the present invention, PVC with a high volume resistivity can be obtained without adversely affecting other physical properties.

Example 2 3000 ml of deionized water was added to a stainless steel polymerization tank with an internal volume of 7 d.
k9, vinyl chloride 2000k9, t-butyl peroxypivalate 0.6kg, hydroxypropyl methylcellulose 0.5k9, hydroxyethylcellulose 1.5
K9 was charged and the reaction was continued for 5rc until the pressure reached 5k9/CIL.

After the reaction was completed and unreacted monomers were collected, a copolymer of methyl vinyl ether and maleic anhydride (1%) having a specific viscosity of 1.4 at 25° C.
:1 molar ratio) in the form of an aqueous solution per raw material vinyl chloride.
ppm. and stirred for 5 minutes. The polymer slurry was then discharged, dehydrated and dried to obtain a product, and its volume resistivity and other physical properties were measured using the methods described above. The results are shown in Table 2.

Comparative Example 3 An experiment was conducted in the same manner as in Example 2, except that the copolymer of methyl vinyl ether and maleic anhydride was not added.

The results are shown in Table 2. Comparative Example 4 An experiment was carried out in the same manner as in Example 2, except that the amount of the copolymer of methyl vinyl ether and maleic anhydride was increased to 10,000 ppm.

The results are shown in Table 2.

As seen in this comparative example, the effect of improving the volume resistivity is not much different from that when a small amount is added, but the light transmittance is deteriorated.

Example 3 In Example 2, partially saponified polyvinyl alcohol (saponification degree 75 mol%) was used instead of hydroxyethyl cellulose.
The reaction was carried out at 56°C using 1.5k9.

After the reaction was completed and unreacted monomers were collected, a copolymer of methyl vinyl ether and maleic anhydride (11 molar ratio) with a specific viscosity of 1.5 in a 1% solution of methyl ethyl ketone was prepared.
was added in the amount shown in Table 3, and a product was obtained in the same manner as in Example 2. A PVC composition was prepared by blending the vinyl chloride polymer thus obtained with a PVCl compound having an average degree of polymerization of 1100, 50 parts of dioctyl phthalate, 3 parts of tribasic lead sulfate, 1 part of dibasic stearic acid, and 15 parts of calcium carbonate. Tsukutsuta. Table 3 shows the volume resistivity values measured by the method described above. That is, the volume resistivity is improved by adding the copolymer of methyl vinyl ether and maleic anhydride.

Claims (1)

[Claims] 1. When vinyl chloride is made into a vinyl chloride polymer by aqueous suspension polymerization, a copolymer of alkyl vinyl ether and maleic anhydride is added at a concentration of 10 to 50% of the raw material monomer.
1. A method for producing a vinyl chloride polymer composition having a high specific volume resistivity, which comprises adding 0.00 ppm after the start of polymerization and before a dehydration step of a polymerization suspension.