WO1998042759A1 - Vinyl chloride resin powder and process for preparing the same - Google Patents

Abstract

A vinyl chloride resin powder having a K value of 63 to 74, a bulk density D (g/ml) satisfying, in relation with the K value, the formula (I): 8.5≤KD≤11, a volume specific resistance of not less than 8 x 1013 Φ.cm and a number of fish-eyes of less than 5; and a process for preparing the vinyl chloride resin powder by using as a suspending agent either (1) a combination of hydroxypropylmethylcellulose (a) with a terminally ionic polyvinyl alcohol (b) having a degree of saponification of 61 to 70 mol % and an average degree of polymerization of 150 to 350, or (2) a combination of the component (a), the component (b), and a partially saponified polyvinyl alcohol (c) having a degree of saponification of 70 to 99 mol % and an average degree of polymerization of 2800 to 5000. The vinyl chloride resin powder can provide a molding that is porous and excellent in plasticizer absorption, has a high bulk density, a good productivity in molding, and a high volume specific resistance, and is reduced in fish-eyes, that is, has a good appearance.

Description

 Specification

Vinyl chloride resin powder and method for producing the same

Technical field

 The present invention relates to a vinyl chloride resin powder and a method for producing the same. More specifically, the present invention is porous, excellent in plasticizer absorption, high in bulk density, has good processing productivity, has a large volume resistivity value, and has a good appearance with few fish eyes. The present invention relates to a general-purpose vinyl chloride resin powder for giving a molded article, and a method for efficiently producing the same. Background art

 General-purpose vinyl chloride resin powders are widely used in many fields as hard products and soft products because they can be mass-produced and are inexpensive.

 As a method for producing this general-purpose vinyl chloride resin powder, for example, in the presence of a suspending agent such as a cellulose derivative, polyvinyl alcohol, or gelatin, vinyl chloride alone or mainly containing vinyl chloride can be copolymerized with the same. A method of performing suspension polymerization with an unsaturated monomer is known.

 However, among the vinyl chloride resin powders obtained by the conventional suspension polymerization method, those having excellent porosity have disadvantages such as low bulk density, non-uniform particle size and existence of fine particles. On the other hand, those with a high bulk density have the disadvantage of poor porosity. Regarding the bulk density, a resin powder having a high bulk density is preferable from the viewpoints of high-speed processing accompanying cost reduction and energy saving, improvement in workability during processing, and improvement in productivity in molding processing. When the porosity is poor, the plasticizer absorbs poorly, and as a result, the work efficiency is inevitably reduced, for example, when processing agricultural films, and the appearance of the molded product is poor due to the increase in fish eyes And other problems arise.

Conventionally, the butyl chloride resin powder with less fisheye has a volume resistivity value of Tended to be small. In wire coating applications, it has a high bulk density due to high productivity in extrusion processing, has few fish eyes to exhibit an excellent appearance, and has a high volume resistivity due to the requirement of excellent insulation. It has been desired to have a vinyl chloride resin powder.

 Until now, various attempts have been made to produce a vinyl chloride resin powder having excellent porosity and a vinyl chloride resin powder having a high bulk density. For example, as a suspending agent, (1) a degree of conversion of 65 to A combination of a polyvinyl alcohol having a degree of polymerization of 80 to 100 mol% and an average degree of polymerization of from 300 to 250 and a cellulose derivative (Japanese Patent Application Laid-Open No. 54-46884); Combination of polyvinyl alcohol having a degree of hydrolysis of 60 mol% or more and a water-soluble cellulose ether (Japanese Patent Application Laid-Open No. 61-151209) (3) The degree of genification is 20 to 55 mol%, and the average A method using a combination of polyvinyl alcohol having a degree of polymerization of 150 to 600 and hydroxypropylmethylcellulose (Japanese Patent Application Laid-Open No. Sho 63-156809) is disclosed.

 However, all of these methods have an improving effect on either one of the plasticizer absorbency and the bulk density, but the effects of simultaneously improving both are not always satisfactory.

 Japanese Patent Application Laid-Open No. 432,208 discloses that, when a vinyl chloride polymer is subjected to suspension polymerization, first, as a dispersion stabilizer, a degree of genification of 65 to 75 mol%, an average degree of polymerization of The polymerization is carried out in the presence of a partially-genated polyvinyl alcohol having a molecular weight of 75 to 85 and hydroxypropylmethyl cellulose, and the polymerization conversion is between 5 and 60% by weight. There has been proposed a method for producing a vinyl chloride-based polymer in which a partially-genated polyvinyl alcohol having an average degree of polymerization of 150 to 270 mol% is added. However, in this method, a force capable of obtaining a high bulk density vinyl chloride resin powder can provide a molded product having many fish eyes, a high bulk density, and a small number of fish eyes. There is a problem that it is not possible to obtain a well-balanced vinyl chloride resin powder.

Further, Japanese Patent Application Laid-Open No. Sho 60-42407 discloses that when polymerizing in the presence of a primary suspending agent such as polyvinyl alcohol having a saponification degree of 70 to 99 mol%, Degree 7 By adding at least one kind of polyvinyl ester of less than 0 mol% before or during the polymerization, a porous vinyl chloride resin powder having a high bulk density and a high volume resistivity can be obtained. It has been disclosed. Even with this method, even with this method, there is still much fishery, and further improvement in bulk density is desired.

 As described above, according to the conventional technology, it is difficult to produce a vinyl chloride resin powder which is excellent in the balance of porosity, bulk density and volume resistivity, and which gives a molded article with a small fish eye and a good appearance. The reality is that it is difficult. Disclosure of the invention

 It is an object of the present invention to provide a porous material having excellent plasticizer absorbability, a high bulk density, good heat productivity, a high volume specific resistance value, and a good appearance with few fish eyes. An object of the present invention is to provide a vinyl chloride resin powder which gives a molded article.

 Another object of the present invention is to provide a method for efficiently producing the above-mentioned vinyl chloride resin powder having excellent performance.

 The present inventors have conducted intensive studies to achieve the above object, and as a result, the κ value is in a specific range, and the bulk density D (g / ml) of the powder and the K value are in a specific relationship. As a result, it was found that a vinyl chloride resin powder having a volume resistivity value equal to or higher than a certain value and having a smaller number of fish eyes than a specific value could be suitable for the purpose.

 Also, as a suspending agent, a combination of a polyvinyl alcohol having a terminal ionic group having a specific degree of genification and an average degree of polymerization and hydroxypropyl methylcellulose is used. Specified methods for adding these suspending agents by using in combination with polyvinyl alcohol containing a terminal ionic group and hydroxypropyl methyl cellulose having an average degree of polymerization and polyvinyl alcohol having a specific degree of genification and an average degree of polymerization. By doing so, it has been found that the vinyl chloride resin powder having the excellent performance described above can be efficiently obtained.

 The present invention has been completed based on such findings.

 That is, the present invention

(1) A vinyl chloride resin powder having a K value of 63 to 74, and a bulk density D (g / ml) and the above K value and force formula [1]

8.5≤K ^D ≤11… [1]

A vinyl chloride resin powder characterized by satisfying the following relationship, and having a volume resistivity value of at least 8 × 10 ¹³ Ωcm and less than five fishes:

 (2) In an aqueous medium, in the presence of a suspending agent, vinyl chloride alone or vinyl chloride as a main component, and a mixture thereof with a copolymerizable unsaturated monomer is subjected to suspension polymerization to form a vinyl chloride resin. In the production of powder, as a suspending agent, (a) hydroxypropyl methylcellulose and (b) a terminal ionic group having a saponification degree of 61 to 70 mol% and an average polymerization degree of 150 to 350 It is characterized by using a combination with the contained polyvinyl alcohol, the K value is 63 to 74, the bulk density D (gZml) of the powder, the above K value and the formula

 [1]

8.5≤K ^D ≤11… [1]

And a volume resistivity value of at least 8 XI 0 ¹³ Ω'cm and less than five fishes (hereinafter referred to as the production method [1]) ,

 (3) The method according to item (2), wherein (a) 0.01 to 0.5 part by weight of hydroxypropylmethylcellulose and (b) 0.001 to 0.5 part by weight of polyvinyl alcohol having a terminal ionic group are used per 100 parts by weight of the monomer. A method for producing a vinyl chloride resin powder,

(4) In an aqueous medium, in the presence of (a) hydroxypropyl methylcellulose and (b) polyvinyl alcohol having a terminal ionic group having a degree of saponification of 61 to 70 mol% and an average degree of polymerization of 150 to 350, vinyl chloride Initiate suspension polymerization of a mixture of vinyl chloride alone or with a copolymerizable unsaturated monomer, and when the polymerization rate is 5% by weight or more, (c) the degree of Mol%, partially added saponified polyvinyl alcohol with an average degree of polymerization of 2800 to 5000.Start adding, and continue continuously so that the polymerization rate progresses at least 10% by weight and the polymerization rate at the end of addition does not exceed 70% by weight. The K value is from 63 to 74, and the bulk density D (g / ml) of the powder and the K value are represented by the formula [1]

8.5≤K ^D ≤11… [1] A vinyl chloride resin powder having a volume resistivity value of at least 8 × 10 ¹³ Ω'cm and less than 5 fishes (hereinafter referred to as a production method [2]);

as well as

 (5) With respect to 100 parts by weight of the monomer, (a) 0.01 to 0.5 part by weight of hydroxypropylmethylcellulose, (b) 0.001 to 0.5 part by weight of a terminal ionic group-containing polyvinyl alcohol, and (c) partially-genated polyvinyl alcohol The method for producing a vinyl chloride resin powder according to item (4), wherein 0.001 to 0.5 part by weight is used,

Is provided. BEST MODE FOR CARRYING OUT THE INVENTION

 The vinyl chloride resin powder of the present invention needs to have the following properties. First, the K value must be in the range of 63 to 74. This K value has a correlation with the average degree of polymerization. When the K value is in the range of 63 to 74, the average degree of polymerization is about 900 to 1600. If the K value is less than 63, there is a problem in terms of strength, such as deterioration of wear resistance and a decrease in tensile strength, and if it exceeds 74, the bulk density is reduced and workability is deteriorated. Fishiness increases as the sex worsens.

 Next, the bulk density D (g / ml) of the vinyl chloride resin powder and this K value are expressed by the following equation [1]

8.5≤K ^D ≤11… [1]

Is necessary to satisfy the relationship, preferably, the value of K ^D of 8.7 or more and 10.5 or less. Porosity when the value of K ^D of departing from the scope of formula [1], bulk density, specific volume without the vinyl chloride resin powder having excellent balance of the resistance value is obtained, is achieved which have not been object of the present invention.

 The K value is a value measured by the following method in accordance with DIN 53726, which shows the relationship with the average polymerization degree obtained from the specific viscosity of the solution in JIS K 6721.

That is, a test solution is prepared by dissolving 0.5 g of a vinyl chloride resin powder sample in 100 ml of cyclohexanone. Next, use an Ubbelohde viscometer and set the temperature to 25 ± 0. At 05 ° C, the drop seconds of the test solution and the drop seconds of the cyclohexanone used for preparing the test solution are measured, and the K value is calculated according to the following formula.

K = k10 ³

 Test liquid drop seconds (s)

 Where Z (relative viscosity)

 Sanon fall seconds (s)

C (test solution concentration): gZl 0 Oml cyclohexanone

 The bulk density D (g / ml) is a value measured by the following method in accordance with ISO 601977.

 That is, a funnel with a shape specified by ISO 60 1977 and a cover at the bottom is placed on the measuring cylinder 20 to 30 mm with an inner diameter of 45 ± 5 mm and a capacity of 100 ± 0.5 ml. After thoroughly stirring 10 to 120 ml of the vinyl chloride resin powder sample 1 in the above funnel, remove the bottom cover immediately and drop the sample into the measuring cylinder. The sample raised from the cylinder is scraped off with a thin flat member to make a horizontal surface. Next, accurately weigh the sample in the cylinder to 0.1 g, measure the internal volume of the cylinder, and determine the bulk density by the following formula.

 Bulk density D (g / ml) = m / V

 m: Weight of sample in cylinder (g)

 V: Internal volume per cylinder (ml)

Measure twice and take the average value.

The vinyl chloride resin powder of the present invention has a volume resistivity value of 8 × 10 ¹³ Ωcm or more, preferably 1 110 ¹⁴ Ωcm or more, and has a fish eye count of 5 The number is less than 3, preferably 3 or less. This makes it possible to provide a molded article having excellent electrical insulation and a beautiful appearance.

The volume resistivity is a value measured as follows. That is, a mixture prepared by adding 50 parts by weight of octyl phthalate and 3 parts by weight of a lead-based stabilizer to 100 parts by weight of a vinyl chloride resin powder was mixed with a 6-inch roll for kneading. Knead at 50 ° C for 5 minutes and press the resulting sheet further at 100 ° C for 6 minutes to obtain a thickness of 1.0 ± 0.15 Hidden, 120 X X 120 X Hidden Make a square test piece larger than that. After maintaining this test piece in a constant temperature and humidity room at 23 ° C and 50% for 30 minutes or more, measure the volume resistivity value in accordance with JISK6723.

The number of fish eyes is a value measured as follows. That is, an S compound prepared by adding 100 parts by weight of vinyl chloride resin powder, 60 parts by weight of dioctyl phosphate, 2 parts by weight of a barium-zinc composite stabilizer, and 3.5 parts by weight of a deep blue pigment was added. , were kneaded for 7 minutes at 1 4 0 ° C by kneading a 6-inch roll, to create width 1 0 0 mm, the sheet having a thickness of 0. 5 mm, the transparent particles children per 5 0 cm ² of this sheet And this is defined as the number of fish eyes. The less fisheye, the more beautiful the formed film.

 The vinyl chloride resin powder of the present invention having such excellent properties can be produced extremely efficiently by the production method of the present invention described below.

 Next, a method for producing the vinyl chloride resin powder of the present invention will be described.

In the method of the present invention, a vinyl chloride resin powder is produced by suspension polymerization in an aqueous medium. In this case, vinyl chloride alone or a mixture of vinyl chloride with an unsaturated monomer copolymerizable therewith is used as a raw material monomer. Here, unsaturated monomers copolymerizable with vinyl chloride include, for example, acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, gay cinnamate, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride. Unsaturated monocarboxylic acids, such as unsaturated dicarboxylic acids and their anhydrides; monoalkyl esters of fumaric acid and monoalkyl esters of itaconic acid; monoalkyl esters of unsaturated dicarboxylic acids; methyl, ethyl and propyl acrylate or methacrylate Unsaturated carboxylic acid esters such as butyl, octyl, cyclohexyl, and benzyl esters; unsaturated dicarboxylic acids such as dimethyl, maleic acid and fumaric acid, dimethyl, dimethyl, dipropyl, dibutyl, octyl, zinclohexyl, and dibenzyl esters Acid diesters; Binirue one ether such as ruby two Rue one ether, E chill vinyl ether, propyl vinyl ether; Orefin of ethylene, propylene, butene one 1, etc. pentene one 1; Steel Aromatic monovinyl compounds such as lene and α-methylstyrene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; unsaturated amide compounds such as acrylamide and methacrylonamide; vinyl acetate, vinyl propionate, and cabron Vinyl carboxylate esters such as vinyl acrylate and vinyl acrylate; and vinylidene chloride. These copolymerizable monomers may be used alone or in combination of two or more.

 When a mixture of vinyl chloride and the above copolymerizable unsaturated monomer is used as a raw material monomer, the content of vinyl chloride in the monomer mixture should be 50% by weight or more. Preferably, it is 75% by weight or more.

 In the production method of the present invention, there are two embodiments. In the production method [1], a combination of (a) hydroxypropylmethylcellulose and (b) polyvinyl alcohol having a terminal ionic group is used as a suspending agent. In the production method [2], a combination of (a) hydroxypropylmethylcellulose, (b) polyvinyl alcohol having a terminal ionic group, and (c) partially-genated polyvinyl alcohol is used as a suspending agent.

 The hydroxypropyl methylcellulose as the component (a) in the production methods [1] and [2] is obtained by substituting a part of the hydroxyl groups of the cellulose with a hydroxypropoxy group and a methoxy group. Is not particularly limited, and in the present invention, those obtained by a known method can be used. The degree of substitution of the hydroxypropoxy group and the methoxy group is not particularly limited. However, from the viewpoint that a vinyl chloride resin powder having excellent plasticizer absorption and a high bulk density can be obtained, the hydroxypropoxy group and the Those having a substitution degree of 5 to 15 mol% and a methoxy group substitution degree of 15 to 35 mol% are preferred. Further, a 2% by weight aqueous solution having a viscosity at a temperature of 20 ° C. in the range of 10 to 550 centimeters is excellent in terms of suspension properties and the performance of the obtained vinyl chloride resin powder. It is suitable.

In the production methods [1] and [2] of the present invention, the hydroxypropyl methylcellulose may be used alone or in combination of two or more, and the amount of the hydroxypropyl methylcellulose used is not particularly limited. No, it is selected according to the situation, but usually, It is selected in the range of 0.01 to 0.5 part by weight per 100 parts by weight of the raw material monomer. If the amount is less than 0.01 part by weight, the polymerization system may be unstable.If the amount exceeds 0.5 part by weight, the particle size of the obtained polymer becomes too small, resulting in poor handling. Is not preferred. Considering the stability of the polymerization system and the particle size of the obtained polymer, the preferred amount of the hydroxypropyl methylcellulose is 0.02 to 0.1 part by weight per 100 parts by weight of the raw material monomer. Range.

 On the other hand, in the production methods [1] and [2], the terminal ionic group-containing polyvinyl alcohol of the component (b) has an ionic group at the terminal of the partially-genated polyvinyl alcohol. Has a degree of genification of 61 to 70 mol%, preferably 62 to 68 mol%, and an average degree of polymerization of 150 to 350, preferably 170 to 270 mol%. Are used. If the degree of saponification or the average degree of polymerization deviates from the above range, it is difficult to obtain a vinyl chloride resin powder having an excellent balance between plasticizer absorption and bulk density, and the object of the present invention cannot be achieved. The ionic group is not particularly limited, but preferably includes, for example, an amino group, an ammonium group, a carboxyl group, a sulfonate group and the like.

 Such a polyvinyl alcohol having a terminal ionic group can be easily produced according to a known method, for example, a method described in International Publication No. 91 / 155,018.

In the production methods [1] and [2] of the present invention, the terminal ionic group-containing polyvinyl alcohol may be used alone, or two or more kinds may be used in combination. The amount used is not particularly limited and may be appropriately selected depending on the circumstances.In general, the amount is selected from 0.001 to 0.5 part by weight per 100 parts by weight of the raw material monomer. It is. If the amount is less than 0.001 part by weight, the effect of improving fisheye may not be sufficiently exerted.If the amount exceeds 0.5 part by weight, the bulk density of the obtained polymer becomes small, and It is not preferable because the property becomes worse. Considering the effect of improving fish eye and the bulk density of the polymer, the preferred amount of the terminal ionic group-containing polyvinyl alcohol is 0.01 to 0 parts by weight per 100 parts by weight of the raw material monomer. It is in the range of 1 part by weight. Further, the partially-genated polyvinyl alcohol of the component (c) in the production method [2] is a suspending agent added during the polymerization as described later, and in the present invention, the saponification degree is 70%. Those having an average degree of polymerization in the range of 280 to 50,000 are used. If the degree of genification or the average degree of polymerization is out of the above range, it is difficult to obtain a vinyl chloride resin powder having an excellent balance between plasticizer absorbency and bulk density, and the object of the present invention cannot be achieved.

 In the production method [2] of the present invention, one of these partially-genated polyvinyl alcohols may be used, or two or more of them may be used in combination. The amount used is appropriately selected depending on the situation, but is usually selected in the range of 0.001 to 0.5 part by weight per 100 parts by weight of the raw material monomer. If the amount is less than 0.001 part by weight, the bulk density may be low. If the amount exceeds 0.5 part by weight, the effect of improving fish fish is not sufficiently exhibited, which is not preferable. From the viewpoints of the bulk density of the polymer and the effect of improving fishiness, the preferred use amount of this partially-genated polyvinyl alcohol is 0.01 to 0.1 part by weight per 100 parts by weight of the raw material monomer. Range. In the production method [1] of the present invention, as long as the object of the present invention is not impaired, it is possible to use other conventionally known suspending agents together with the components (a) and (b) as desired. In addition, in the production method [2] of the present invention, if necessary, together with the component (a), the component (b) and the component (c), as long as the object of the present invention is not impaired. Other suspending agents may be used. Other suspending agents that may optionally be used include, for example, polyvinyl methyl ether, polyethylene glycol, starch, sodium alginate, gelatin, carboxylated cellulose, vinyl maleate monoacetate copolymer and salts thereof, and methyl. Examples include vinyl ether-maleic anhydride copolymers and salts thereof, fatty acid esters of polyethylene glycol, and anionic, nonionic, and cationic surfactants. These can be added at an appropriate time before or during the polymerization.

ルペルォキシド、 ジサクシニックァシッ ドペルォキシ ドなどの有機過酸化物、 さらには 2 , 2 '—ァゾビスィソプチロニトリル、 2 , 2 ' ーァゾビス一 2—メチルブチロニトリル、 2， 2 'ーァゾビスジメチルバレロニト リルなどのァゾ化合物などを挙げることができる。 これらの触媒の 1種又は 2種 以上を組み合わせて使用することができ、 その使用量は、 原料単量体の種類と量 及び仕込方式などによって適宜選ばれるが、 通常原料単量体 1 0 0重量部当たり、 0. 0 0 1〜5. 0重量部の範囲で選択することができる。 In the suspension polymerization in the production methods [1] and [2] of the present invention, an oil-soluble radical initiator is used as a catalyst. The oil-soluble radical initiator is not particularly limited, and is conventionally used when producing a vinyl chloride polymer by a suspension polymerization method. Any one can be selected from those that are used. Examples of the oil-soluble radical initiator include dibenzoylperoxides, diacyl peroxides such as di-3,5,5-trimethylhexanoylperoxide and dilauroylbeloxide; diisopropylperoxide; Peroxydicarbonates such as oxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexylperoxydicarbonate; t-butyl peroxybivalate, t-butyl Peroxyesters such as ate; or

Organic peroxides such as ruperoxide and disuccinic acid peroxide, and 2,2'-azobisisobutyronitrile, 2,2'-azobis-1-2-methylbutyronitrile, 2,2'-azo An azo compound such as bisdimethylvaleronitrile can be mentioned. One or a combination of two or more of these catalysts can be used, and the amount used is appropriately selected depending on the type and amount of the raw material monomers, the charging method, and the like. It can be selected in the range of 0.001 to 5.0 parts by weight per part by weight.

Next, a preferred embodiment of the production method [1] of the present invention will be described. The suspension polymerization method in the production method [1] of the present invention is not particularly limited, and a method conventionally used for producing a vinyl chloride polymer by suspension polymerization can be used. For example, suspension polymerization can be suitably performed as follows. First, in an aqueous medium, predetermined amounts of the above-mentioned (a) component hydroxypropylmethylcellulose, (b) component-end-containing polyvinyl alcohol having an ionic group, and an oil-soluble radical initiator as a suspending agent are added in predetermined amounts. After charging, a predetermined amount of vinyl chloride as a raw material or a predetermined ratio of a mixture of vinyl chloride and a copolymerizable unsaturated monomer is charged, and the temperature is usually in the range of 30 to 80 ° C with stirring. The polymerization is carried out. At this time, the charged amount of each material and the reaction conditions were adjusted so that the K value of the obtained polymer was in the range of 63 (average degree of polymerization of about 900) to 74 (average degree of polymerization of about 160). Etc. are appropriately selected. The average degree of polymerization can be measured by the specific viscosity specified in JISK6721 (however, cyclohexanone is used as a solvent). The measurement of the K value is as described above. In this reaction, there is no particular limitation on the order of charging the suspending agent, the oil-soluble radical initiator and the raw material monomers.

In addition, it is advantageous to select the stirring conditions such that the net required power for stirring per unit volume is 0.6 to ³ kW / m ³ . The required net stirring power per unit volume is the value obtained by dividing the stirring power excluding the rotational driving load of the transmission or reduction gear and the stirrer itself from the total stirring power by the internal volume. It can be calculated by [2].

P NP

 P

 V-V [2]

: Power required for stirring per unit volume (kWZm ³ )

 P: stirring power (kW)

V: liquid volume (m ³ )

 NP: Number of power, fixed value of stirring blade, empirical value is used.

 For example, Fadora: 1.5,

 Max blended wing · Full zone wing: 2.5,

 Loop wing · Anchor wing: 1.0

P: Liquid density (kg / m ³ )

 n: Number of rotations (1 / sec)

 d: stirring blade diameter (m)

: Gravity conversion coefficient [(kg'm) // (kg'sec ² )]

 As another method of obtaining the net stirring power required per unit volume, there is a method using an ammeter of a motor of a stirrer of a polymerization reactor. The stirrer is turned in advance when the polymerization vessel is empty, the rotational drive load of the transmission or reduction gear and the stirrer itself is known with an ammeter, and the effective voltage is subtracted from the ammeter reading during the polymerization reaction. Multiplied by and dividing by the liquid volume.

 Next, a preferred embodiment of the production method [2] of the present invention will be described.

one First, in an aqueous medium, the above-mentioned hydroxypropyl methylcellulose (a) as a suspending agent, polyvinyl alcohol having a terminal ionic group as a component (b) as a suspending agent, and an oil-soluble radical initiator were respectively added. After charging a predetermined amount, charge a predetermined amount of the raw material vinyl chloride or a mixture of vinyl chloride in a predetermined ratio and a copolymerizable unsaturated monomer, and stir, usually in the range of 30 to 80 ° C. The polymerization is started at a temperature of. There are no particular restrictions on the order in which the above-mentioned suspending agent, oil-soluble radical initiator and raw material monomer are charged.

 In the production method [2] of the present invention, after the polymerization is started in this way, when the polymerization rate (polymerization conversion rate) is 5% by weight or more, the partially-polyvinylated polyvinyl chloride of the component (c) is used. It is necessary to start the addition of the alcohol and continuously add the alcohol during a period in which the polymerization rate progresses at least 10% by weight, and so that the polymerization rate at the end of the addition does not exceed 70% by weight. When the addition of the partially-genated polyvinyl alcohol of the component (c) is started at a point in time when the conversion is less than 5% by weight, the molded article obtained by using the obtained polymer has many fish eyes, and at the end of the addition. When the degree of polymerization exceeds 70% by weight, the effect of increasing the bulk density of the polymer is not sufficiently exhibited. In order to reduce the fishiness of the molded article by the obtained polymer and to increase the bulk density of the polymer, the partially gamma-modified polyvinyl alcohol of the component (c) is used. %, And it is particularly advantageous to add it so that the conversion at the end of the addition does not exceed 60% by weight. In addition, when the addition of the partially-genated polyvinyl alcohol is completed when the rate of increase in the degree of polymerization is less than 10% by weight, or when it is added all at once, the molded product has many fish eyes, which is not preferable.

 As a method for adding the component (c), it is recommended to press-fit the solution with a high-pressure metering pump in the form of an aqueous solution of preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight. In this reaction, the charged amount of each material and the K value of the obtained polymer were in a range of 63 (average degree of polymerization of about 900) to 74 (average degree of polymerization of about 160). Reaction conditions and the like are appropriately selected.

In the production methods [1] and [2] of the present invention, the monomer polymerization conversion per hour is leveled and the load of reaction heat removal is made uniform as long as the object of the present invention is not impaired. For the purpose of, for example, causing polymerization, a polymerization inhibitor or a polymerization retarder can be appropriately added during the polymerization reaction, if desired. The polymerization inhibitor and the polymerization retarder are not particularly limited, and may be appropriately selected from those conventionally used in the production of vinyl chloride polymers. Examples of polymerization inhibitors include phenolic compounds such as hydroquinone and Pt-butylcatechol, and hydrochlorides such as N, N-getylhydroxylamine, N-dinitrosulfonylhydroxylamine ammonium salt (cuperone). Xylamine compounds; organic thio compounds such as dithiobenzoyl disulfide and tetraethyl thiuram disulfide. These may be used alone or in combination of two or more.

 On the other hand, examples of the polymerization retarder include cycloalkene compounds having 5 to 8 carbon atoms such as cyclopentene, cyclohexene, and cyclopentene, and these may be used alone or in combination of two or more. May be used.

 If desired, known additives such as a chain transfer agent, a cross-linking agent, and a scale inhibitor can be added to the polymerization system.

The polymerization pressure is usually in the range of 3 to 15 kgZcm ² G, preferably 4 to 12 kgZcm ² G, and the polymerization time is determined by the type of the raw material monomer, the type and amount of the catalyst, the polymerization temperature, the polymerization pressure, Although it depends on various conditions such as the desired K value (desired degree of polymerization) of the obtained polymer and cannot be unconditionally determined, it is usually about 2 to 20 hours.

 Thus, vinyl chloride polymer particles having an average particle size of about 50 to 250 / m are produced. After completion of the reaction, the unreacted monomer is recovered according to a conventional method, and then the polymer is taken out and dried to obtain a desired vinyl chloride resin powder.

 The vinyl chloride resin powder thus obtained has a K value in the range of 63 to 74, and has a bulk density D (g / ml) of the powder, the above K value, and the formula [1] ]

8. 5≤K ^D ≤1 1… [1]

A satisfies the relationship, in volume resistivity 8 ¹ 0 1 ³ Ω · cm or more, the number of Fi Sshuai by the measurement method is less than 5.

The vinyl chloride resin powder is porous and excellent in plasticizer absorption, and has a high bulk density. In addition to good processing productivity, a molded product having a large volume resistivity value, excellent electrical insulation properties, and good appearance with little fishery can be provided.

 Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

 The physical properties of the obtained vinyl chloride resin powder were measured according to the following procedures.

(1) κ value

 It was measured according to the method described in the text of the specification. ―

(2) Average degree of polymerization

 The measurement was performed according to JIS K 6721. However, cyclohexanone was used as a solvent.

 (3) Bulk density

 The measurement was performed according to the method described in the specification text.

 (4) Plasticizer absorption time

 400 g of vinyl chloride resin powder is placed in a mixer tester [Toyo Seiki Labo Plastomill, Planetary Mixer P-600], preheated (5 minutes) with stirring at 100 rpm, and heated to 88 ° C. To this, 200 g of a polyester plasticizer [SP-105 manufactured by Sanken Kako Co., Ltd.] was added, and the time when the torque decreased from the time of addition and reached a steady value was taken as the absorption time. The shorter the time, the better the plasticizer absorption.

 (5) Volume resistivity

 The measurement was performed according to the method described in the specification text.

 (6) Fitsshui

 It was measured according to the method described in the text of the specification.

Production Example 1

Production of polyvinyl alcohol containing terminal ionic group

A reaction vessel was charged with 1400 parts by weight of vinyl acetate, 0.12 parts by weight of 3-mercaptopropionic acid, and 350 parts by weight of methanol, and the inside of the vessel was purged with nitrogen, and then heated to raise the liquid temperature to 60 ° C. When the liquid temperature reached 60 ° C, 5 parts by weight of methanol containing 0.60 parts by weight of 2,2'-azobisisobutyronitrile was added. Next Then, 25 parts by weight of methanol containing 2.54 parts by weight of 3-mercaptopropionic acid was uniformly added dropwise over 4 hours. After the completion of the dropwise addition, the reaction was carried out at 60 ° C. for 4 hours, and then the reaction solution was cooled.

 Next, an operation of distilling off residual vinyl acetate in the reaction-completed solution together with methanol under reduced pressure while adding methanol was performed to obtain a methanol solution of polyvinyl acetate (concentration). About 70% by weight).

Next, the polyvinyl acetate in the methanol solution was subjected to a genification treatment with sodium hydroxide to obtain a polyvinyl alcohol having a degree of genification of 65 mol%. This polyvinyl alcohol has an average degree of polymerization of 250, and a nuclear magnetic resonance analysis (NMR) shows the presence of one COON a group at one end, and Na 0 〇C-CH ₂ It was confirmed that the compound had a group represented by CH ₂ —S—. Production Example 2

By the same operation as in Production Example 1, a polyvinylidene having a group represented by Na〇〇C—CH ₂ CH ₂ —S— at one end of the molecule, having a degree of genification of 40 mol% and an average degree of polymerization of 250 was obtained. Nyl alcohol was produced.

Example 1

In a stainless steel lined polymerization reactor equipped with a stirrer and jacket with an internal volume of 2000 liters, 1000 kg of deionized water, 400 g of 1,1,3,3-tetramethylbutylhydroxyneodecanoate and suspension The amount of hydroxypropyl methylcellulose [abbreviated name: HPMC, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: Methrose 60 SH50] as the agent shown in Table 1 and the polyvinyl alcohol containing a terminal ionizable group obtained in Production Example 1 After the coal was charged, the polymerization vessel was degassed, 800 kg of vinyl chloride monomer was charged, the temperature was raised to 57 ° C, and the polymerization pressure was 8.5 kg / cm ² G. Net stirring power required per unit volume 1.7 kW / Polymerization was started at m ³ . The polymerization was carried out while maintaining the temperature at 57 ° C., and the polymerization was terminated when the polymerization pressure dropped to Ί kgZcra ² G.

 After completion of the reaction, the unreacted monomer was recovered, and then the polymer was dehydrated and dried. Table 1 shows the evaluation results of the obtained vinyl chloride resin powder.

Example 2 A vinyl chloride resin powder was produced in the same manner as in Example 1, except that the amount of the terminal ionic group-containing polyvinyl alcohol was changed as shown in Table 1. Table 1 shows the evaluation results of the resin powder.

Example 3

In Example 1, the temperature was raised to 51.5 ° C, and the polymerization was carried out while maintaining the temperature at 51.5 ° C. When the polymerization pressure dropped to 5.9 kgZcm ² G, the polymerization was terminated. Other than the above, the procedure was the same as in Example 1. Table 1 shows the evaluation results of the obtained vinyl chloride resin powder.

Example 4

 Example 3 was carried out in the same manner as in Example 3, except that the amount of the terminal ionic group-containing PVA was changed as shown in Table 1. Table 1 shows the evaluation results of the obtained vinyl chloride resin powder.

Example 5

に降下した時点で重合を終了した以外は、 実 施例 4と同様に実施した。 得られた塩化ビニル樹脂粉体の評価結果を第 1表に示 す。 In Example 4, the temperature was raised to 49.5 ° C, and the polymerization was carried out while maintaining the temperature at 49.5 ° C.

The procedure was performed in the same manner as in Example 4 except that the polymerization was terminated when the temperature dropped to. Table 1 shows the evaluation results of the obtained vinyl chloride resin powder.

Table 1

Table 1

 Example 1 Example 2 Example j 3 Example 4 Example 5

HPMC ² ) (% by weight) "0 04 0 04 0 0 ^ 0 04

 M ^^ ll 1 Production example 1 Production example 1 Partial o n ^ 0 035

 PVA Genification degree (mol%) Lily Li% J Li KJ Ri Average polymerization degree L 9 Π V 9 0 9 n 0 Π \ J Terminal ionic group Yes Yes Yes Yes Yes

K value 66 66 71 71 73 Rating Plasticizer absorption time (min) 7.5 5.8 8.0 7.0 7.5 Bulk density (g / ml) 0.534 0.523 0.516 0.512 0.505 Volume resistivity (Ω · αη) 2.5x 10 ¹⁴ 2.3 10 ¹⁴ 2.9x 10 ¹⁴ 2.2x 10 ¹⁴ 2.0X 10 ¹⁴ value Fittings (pieces) 2 1 2 0 1

K ^D 9.37 8.95 9.02 8.87 8.73

[note]

 1)% by weight based on vinyl chloride monomer

 2) HPMC: Hydroxypropyl methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: METROSE 60 SH50J, degree of substitution of methoxy group 28 to 30 mol%, degree of substitution of hydroxypropoxy group 7 to 7 12 mol%

Comparative Examples 1 and 2

 In Example 1, except that the polyvinyl alcohol having a terminal ionic group obtained in Production Example 2 was used in an amount shown in Table 2 in place of the polyvinyl alcohol having a terminal ionic group obtained in Production Example 1. Was carried out in the same manner as in Example 1 to produce a vinyl chloride resin powder. Table 2 shows the evaluation results of each vinyl chloride resin powder. Comparative Examples 3 and 4

 In Example 1, in place of the polyvinyl alcohol having a terminal ionic group obtained in Production Example 1, partially saponified polyvinyl alcohol PVA-1 having no terminal ionizable group of the kind and amount shown in Table 2 Except for using PVA-2 and PVA-2, the same procedure as in Example 1 was carried out to produce a vinyl chloride resin powder. Table 2 shows the evaluation results of each vinyl chloride resin powder.

Comparative Example 5

 Example 1 was repeated except that in place of the terminal ionic group-containing polyvinyl alcohol obtained in Production Example 1, SMS (sorbitan monostearate, nonionic surfactant) was used in the amounts shown in Table 2. This was carried out in the same manner as in Example 1 to produce a vinyl chloride resin powder. Table 2 shows the evaluation results of the resin powder.

Comparative Example 6

 In Example 1, the terminal ionic group-containing polyvinyl alcohol obtained in Production Example 1 and the partially saponified polyvinyl alcohol PVA-3 obtained in Production Example 1 were used without using hydroquinylpropylmethylcellulose as a suspending agent, as shown in Table 2. The procedure was performed in the same manner as in Example 1 except that the amounts shown in Table 1 were used to produce a vinyl chloride resin powder. Table 2 shows the evaluation results.

Comparative Example 7 Comparative Example 2 was carried out in the same manner as in Comparative Example 2, except that the polymerization temperature was changed to 51.5 ° C and the end pressure was changed to 5.9 kgZcm ² G. Table 2 shows the evaluation results of the obtained vinyl chloride resin powder.

Comparative Example 8

Comparative Example 6 was carried out in the same manner as in Comparative Example 6, except that the polymerization temperature was changed to 51.5 ° C and the end pressure was changed to 5.9 kgZcm ² G. Table 2 shows the evaluation results of the obtained vinyl chloride resin powder. ― Comparative Example 9

Comparative Example 6 was carried out in the same manner as in Comparative Example 6, except that the polymerization temperature was changed to 49.5 ° C and the end pressure was changed to 5.4 kgZcm ² G. Table 2 shows the evaluation results of the obtained vinyl chloride resin powder.

Table 2 1

Table 2 1

Table 2

 Comparative Example δ Totogi Giari / Comparative Example 8 Comparative Example 9

R η r Ρ λ iV / 2)

 iΓ Pashi (Parablet 1) 0 04

Production Example 1 Restriction Example 1 PVA-3 ⁶⁾ Production Example 1 n | JJ No (weight) 0.065 0.05 0.065 0.05 0.065 0.05 m PVA Saponification degree (mol%) 80 65 An 80 65 80 65 υ Average polymerization Degree 2400 250 Δ9 0J 2400 250 2400 250 Terminal ionic group Yes Yes No Yes te Yes

SMS ³ ) (% by weight) ^Π

 K value 66 7 I 1 丄 71 73 π Plasticizer absorption time (min) 11.0 Ό.

Bulk density (g / ml) 0.495 n 08 0.489 0.485 Volume resistivity (Ω · ι) 3. lxlO ¹³ 2. lxlO ¹⁴ 3. Ox 10 ¹³ 3.2x 10 ^13- valent fish-ai (pieces) 40 30 70 75

K ^D 7.96 8.71 8.04 8

>-

[note]

 1)% by weight based on vinyl chloride monomer

 2) HPMC: hydroxypropyl methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., trade name "Metroz 60 SH50", degree of methoxy group substitution 28 to 30 mol%, degree of hydroxypropoxy group substitution 7 to 12 mol%

 3) SMS: Sorbitan monostearate (nonionic surfactant)

 4) PVA-1: partially genated polyvinyl alcohol (prototype)

 5) PVA-2: Partially saponified polyvinyl alcohol (prototype)

 6) PVA-3: Partially saponified polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsenol KH-20"

Example 6

In a stainless steel-lined polymerization reactor with a stirrer and jacket with an internal volume of 2000 liters, 1000 kg of deionized water, 400 g of 1,1,3,3-tetramethylbutylhydroxyoxynedecanoet and a suspension were placed. The amount of the hydroquinyl propyl methylcellulose [abbreviated as HPMC, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: METROSE 60 SH50] as the agent shown in Table 3 and the polyvinyl alcohol containing a terminal ionic group obtained in Production Example 1 After charged calls, degassed polymerization vessel was charged with vinyl chloride monomer 800 kg, the temperature was raised to 57 ° C, polymerization pressure 8.5kgZcm ² G, at net agitation power 1.7KWZm ³ per unit volume The polymerization was started. The polymerization was carried out while maintaining the temperature at 57 ° C. When the conversion was 10% by weight, 160 g of partially added polyvinyl alcohol (PVA-1) shown in Table 3 was converted to a 5% by weight aqueous solution. The polymerization was continuously added until the polymerization rate reached 35% by weight, and the polymerization was terminated when the polymerization pressure dropped to Ί kgZcm ² G.

 After completion of the reaction, the unreacted monomer was recovered, and then the polymer was dehydrated and dried. Table 3 shows the evaluation results of the obtained vinyl chloride resin powder.

Example 7

In Example 6, except that the post-addition partially saponified polyvinyl alcohol (PVA-1) was continuously added until the polymerization rate reached 20% by weight until it reached 60% by weight. The procedure was performed in the same manner as in Example 6, to produce a vinyl chloride resin powder. Table 3 shows the evaluation results of this resin powder.

Example 8

Example 6 was carried out in the same manner as in Example 6, except that the polymerization temperature was changed to 51.5 ° C and the end pressure was changed to 5.9 kgZcm ² G. Table 3 shows the evaluation results of the obtained vinyl chloride resin powder.

Example 9

Example 7 was carried out in the same manner as in Example 6, except that the polymerization temperature was changed to 49.5 ° C and the end pressure was changed to 5.4 kgZcm ² G. Table 3 shows the evaluation results of the obtained vinyl chloride resin powder.

Table 3

[note]

 1)% by weight based on vinyl chloride monomer

2) HPMC: hydroxypropyl methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., trade name “METROSE 60 SH50”, methoxy group substitution degree 28-30 mol%, hydroxy Propoxy group substitution degree 7 to 12 mol%

 3) PVA-1: Partially genated polyvinyl alcohol, manufactured by Kuraray Co., Ltd., product name "PVA635", without terminal ionic group

Comparative Example 10

 Example 6 A vinyl chloride resin powder was produced in the same manner as in Example 6, except that the post-added partially saponified polyvinyl alcohol (PVA-1) was added not during the polymerization but before the polymerization. did. Table 4 shows the evaluation results of the resin powder.

Comparative Example 11

 A vinyl chloride resin was prepared in the same manner as in Example 6, except that the partially added partially-purified polyvinyl alcohol (PVA-1) was added in a short period of time at a polymerization rate of 25 to 30% by weight. A powder was produced. Table 4 shows the evaluation results of this resin powder.

Comparative Example 12

 In the same manner as in Example 6, except that the post-added partially saponified polyvinyl alcohol (PVA-2) shown in Table 4 was used in place of the post-added partially genated polyvinyl alcohol (PVA-1) And a vinyl chloride resin powder was produced. Table 4 shows the evaluation results of this resin powder.

Comparative Example 13

 In Example 6, polymerization was carried out using 0.02 parts by weight of partially genated polyvinyl alcohol (PVA-3) shown in Table 4 instead of 0.05 parts by weight of the terminal ionic group-containing polyvinyl alcohol obtained in Production Example 1. A vinyl chloride resin powder was produced in the same manner as in Example 6, except that the partially added polyvinyl alcohol (PVA-2) was added at a polymerization rate of 30 to 60% by weight. Table 4 shows the evaluation results of this resin powder.

Comparative Example 14

Comparative Example 10 was carried out in the same manner as in Comparative Example 10, except that the polymerization temperature was changed to 51.5 ° C and the end pressure was changed to 5.9 kgZcm ² G. Table 4 shows the evaluation results of the obtained vinyl chloride resin powder. Comparative Example 15

Comparative Example 10 was carried out in the same manner as in Comparative Example 10 except that the polymerization temperature was changed to 49.5 ° C and the end pressure was changed to 5.4 kgZcm ² G. Table 4 shows the evaluation results of the obtained vinyl chloride resin powder.

Table 4

Table 4

 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Comparative Example 14 Comparative Example 15

HPMC ² ) (% by weight) "0.04 0.04 0.04 0.04 0.04 0.04 Before polymerization Type Production example 1 PVA-1 ³⁾ Production example 1 Production example 1 PVA-3 ⁵ ) Production example 1 PVA-1 ³⁾ Production Example 1 PVA-1 ³ Addition amount (% by weight) "0.05 0.02 0.05 0.05 0.02 0.05 0.02 0.05 0.02 Partial degree of transformation (mol%) 65 93 65 65 72 65 93 65 93 Suspended PVA Average degree of polymerization 250 3500 250 250 800 250 3500 250 3500 Turbidity Terminal ionic group Yes No Yes Yes No No No Yes No No Type PVA-1 ³⁾ PVA-2 ^4> PVA-2 ⁴⁾

 Post-addition amount (% by weight) ') 0.02 0.02 0.02

 Partial genification degree (mol%) 93 80 80

 PVA Average degree of polymerization 3500 2400 2400

 Addition period

 [Polymerization rate (% by weight)] 25-30 10-35 30-60

K value 66 66 66 66 71 73 Evaluation Plasticizer absorption time (min) 15.0 13.5 6.0 18.5 16.0 17.0 Bulk density (gZml) 0.561 0.549 0.551 0.555 0.541 0.535 Volume resistivity (Ω · αη) 9.3 10 ¹³ 9.2x 10 ¹³ 7.5 ^{10 13 4.9 10 13 9. Ox 10} '3 9.3 10' 3 -valent Fuitsushuai (number) 70 40 15 150 7.5 80

K ^D 10. 49 9.97 10.06 10.23 10. 04 9. 93

[note]

 1)% by weight based on vinyl chloride monomer

 2) HPMC: Hydroxypropyl methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., trade name “Metrose 60 SH50J, substitution degree of methoxy group 28-30 mol%, substitution degree of hydroxypropoxy group 7-12 mol%

 3) PVA-1: Partially genated polyvinyl alcohol, manufactured by Kuraray Co., Ltd., product name “PVA635J, without terminal ionic group”

 4) PVA-2: Partially genated polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsenol KH20", without terminal ionic group

 5) PVA-3: partially genated polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsenol KP08J, no terminal ionic group, industrial applicability"

 The vinyl chloride resin powder of the present invention is porous, excellent in plasticizer absorption, high in bulk density, has good processing productivity, has a large volume resistivity value, and has little fish eyes. A molded article having a good appearance can be provided.

 According to the method of the present invention, the vinyl chloride resin powder having the above excellent performance can be produced extremely efficiently.

Claims

The scope of the claims 1. A vinyl chloride resin powder having a K value of 63 to 74, wherein the bulk density D (g / ml) of the powder, the K value and the power formula [1] 8.5≤K ^D ≤11… [1] And a volume resistivity value of 8 × 10 ¹³ Ω'cm or more and less than five fishes.  2. In an aqueous medium, in the presence of a suspending agent, vinyl chloride alone or vinyl chloride as a main component, and a mixture thereof with a copolymerizable unsaturated monomer is subjected to suspension polymerization to produce vinyl chloride resin powder. In preparing the body, as a suspending agent, (a) hydroxypropyl methylcellulose, (b) a terminal degree of 6:!-70 mol% and an average degree of polymerization of 150-350 It is characterized by using a combination with a group-containing polyvinyl alcohol. The K value is 63 to 74, the bulk density D (g / ml) of the powder, the K value and the force equation [1] ^8.5≤ Ό ≤ 11 ... [1] A vinyl chloride resin powder having a volume resistivity value of at least 8 × 10 ¹³ Ω · cm and less than five fishes.  3. The method according to claim 2, wherein (a) 0.01 to 0.5 part by weight of hydroxypropyl methylcellulose and (b) 0.001 to 0.5 part by weight of polyvinyl alcohol having a terminal ionic group are used per 100 parts by weight of the monomer. Production method of vinyl chloride resin powder. 4. In an aqueous medium, vinyl chloride alone or in the presence of (a) hydroxypropyl methylcellulose and (b) polyvinyl alcohol containing a terminallyionic group having a degree of conversion of 61 to 70 mol% and an average degree of polymerization of 150 to 350. Suspension polymerization of a mixture of vinyl chloride as a main component and a copolymerizable unsaturated monomer is started, and when the polymerization rate is 5% by weight or more, (c) a degree of genification of 70 to 99 mol %, Average degree of polymerization 2800 to 5000 Partially genated polyvinyl alcohol is added and continuously added over a period in which the conversion is at least 10% by weight and at the end of the addition not exceeding 70% by weight. It has a K value of 63 to 74 and a bulk density D (g / ml) and the above K value are expressed by the formula [1] 8.5≤K ^D ≤11… [1] And a volume resistivity value of 8 × 10 ¹³ Ω'cm or more and less than 5 fishes. 5. For 100 parts by weight of monomer, (a) 0.01-0.5 parts by weight of hydroxypropylmethylcellulose, (b) 0.001-0.5 parts by weight of polyvinyl alcohol containing terminal ionic group, and (c) partially genated polyvinyl. The method for producing a vinyl chloride resin powder according to claim 4, wherein 0.001 to 0.5 parts by weight of alcohol is used.