JPH0477527A - Production of granular vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain the subject resin having high bulk density and excellent flowability by drying an aqueous latex produced by the emulsion polymerization of vinyl chloride optionally with a comonomer to obtain powder, etc., having specific particle diameter and pressing the powder or a mixture of crushed product of the above powder in the form of flakes. CONSTITUTION:An aqueous latex is produced by the emulsion polymerization or fine suspension polymerization of vinyl chloride or a mixture of vinyl chloride and a copolymerizable comonomer (e.g. vinyl acetate). The latex is dried to obtain particles having an average particle diameter of >=5mum and the particles are mixed with particles having an average particle diameter of <5mum and produced by drying and crushing the above particles. The powdery mixture or a mixture produced by mixing the crushed particles having an average particle diameter of <5mum with particles produced by suspension polymerization and having an average particles diameter of >=5mum is pressed and solidified in the form of flakes to obtain the objective granular vinyl chloride resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a granular vinyl chloride resin that has a large bulk specific gravity, good fluidity, can be automatically measured, and can be used as a base resin.

[Conventional technology]

Vinyl chloride resin for paste (base resin) is generally a chloride resin of 0.1 to 2 μm obtained by polymerization or fine suspension polymerization of vinyl chloride or a mixture of vinyl chloride and copolymerized or possible comonomers. It is manufactured by spray-drying latex containing vinyl resin particles and then pulverizing it.This manufacturing method not only requires high costs for packaging, storage, and transportation, but also because of its low bulk specific gravity. However, the powder fluidity is poor, making it difficult to apply it to automatic weighing machines, etc., which are normally used for vinyl chloride resins produced by suspension polymerization or bulk polymerization.

Furthermore, the base resin was highly dusty and had an adverse effect on the working environment.

In order to improve this drawback, JP-A-52-47853 discloses a method of granulating base resin by heating it in the presence of a binder such as water and an emulsifier. It takes a long time for the base resin to be granulated, making it unsuitable for mass production. Moreover, the bulk specific gravity does not become so large. Rough heating during the granulation period can also cause deterioration of the base resin.

(Problem to be solved by the invention) The present inventors have found that the final product is free from dust, has a low sol viscosity when made into plastisol, has good viscosity stability, and has no lumps or streaks caused by poorly dispersed particles. As a result of intensive studies on the production method of vinyl chloride resin that can be used as a base resin that does not remain in the resin, we have found that vinyl chloride or a mixture of vinyl chloride and a comonomer that can be copolymerized with it is subjected to emulsion polymerization or fine suspension polymerization. Obtained O, 1-2
A base resin with an average particle size of less than 5 μm produced by spray-drying latex containing μm-sized vinyl chloride resin particles and then pulverization is mixed with a resin with an average particle size of 5 μm or more that is not pulverized after spray drying as described above. , or by mixing the above-mentioned base resin with an average particle size of less than 5 μm and a resin for mixing base resin with an average particle size of 5 μm or more obtained by suspension polymerization, so-called blending resin, and compressing it while degassing. Both resins solidify into flakes and have a significantly large bulk specific gravity. By dispersing these solids in a dispersing agent, a plastisol with low viscosity, good viscosity stability, and no poorly dispersed particles can be easily formed. The present invention was completed based on the discovery that the present invention is possible.

That is, the object of the present invention is to provide a method for producing a granular vinyl chloride resin that has a large bulk specific gravity, does not cause dusting, has good fluidity, has excellent handling properties, and can provide low viscosity when made into plastisol. There is something to do.

[Means for Solving the Problems] The gist of the present invention is to provide an aqueous latex obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride or a mixture of vinyl chloride and a comonomer copolymerizable therewith. An average particle size of 5 μm produced by drying
A mixed powder of the above particles and particles with an average particle size of less than 5 μm obtained by drying and pulverizing, or an average obtained by suspension polymerization with particles with an average particle size of less than 5 μm obtained by the above-mentioned pulverization. A granular vinyl chloride resin characterized by preparing a mixed powder with a base resin having a particle size of 5 μm or more and a so-called blending resin, and then compressing the mixed powder to solidify it into flakes. It's in the manufacturing method.

The method of the present invention will be explained in detail.

As the granular vinyl chloride resin produced by the method of the present invention, any resin produced by emulsion polymerization or fine suspension polymerization of a mixture of vinyl chloride and a comonomer copolymerizable therewith can be used. Examples of comonomers that can be copolymerized with vinyl chloride include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate;
Acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic esters such as methyl methacrylate, ethyl methacrylate, maleic esters such as dibutyl maleate, diethyl maleate, dibutyl fumarate, diethyl fumarate, etc. Fulleric acid esters, vinyl ethers such as vinyl methyl ether, vinyl butyl ether, vinyl octyl ether, vinyl cyanides such as acrylonitrile and methacrylate, ethylene, propylene,
Examples include α-olefins such as styrene, and vinyl halides other than beer chloride such as vinylidene chloride and vinyl bromide. % or less. Of course, the comonomers are not limited to those mentioned above.

Vinyl chloride resins having an average particle size of 5 μm or more are obtained by agglomeration obtained by spray drying aqueous latex polymerized by emulsion polymerization or fine suspension polymerization to a conversion rate of 80% or more using a rotary disk or nozzle method. When forming a thin film using the resin particles, the maximum particle diameter is desirably adjusted to 100 μm or less, preferably 70 μm or less, in order to prevent streaks or bumps from occurring.

Normal base resin is spray dried 1110~200μ
After spray drying, the particles are crushed and classified into a fine powder using a hammer mill or an air classification mill. This is used as the vinyl chloride resin having an average particle size of less than 5 μm in the present invention.

Blending resin, which is a vinyl chloride resin having an average particle size of 5 μm or more and is used for mixing base resin, is also applicable. Blending resins are usually produced by a suspension polymerization method, and the suspending agents used at that time include various saponified polyvinyl acetate products, various water-soluble cellulose derivatives, maleic acid copolymers, gelatin, etc. They can be used alone or in combination of two or more. Moreover, these suspending agents and certain surfactants can also be used in combination. A slurry obtained by a suspension polymerization method with a conversion rate of 80% or more is dehydrated and dried to obtain a blending resin for mixing base resins with a diameter of usually 10 to 100 μm.

The method of the present invention begins with the above-mentioned average particle size of 5 μm or more and 5 μm or more.
A mixed powder is prepared by mixing a vinyl chloride resin having a particle size of less than The mixing ratio of each resin is not particularly limited, but the weight ratio of resin with an average particle size of 5 μm or more and resin with an average particle size of less than 5 μm is at least 1:99.
It is desirable to set it in the range of ~99:I, especially in the range of 5:95 to 95:5. Specifically, in the case of granular vinyl chloride resin used in plastisol for rotary screen printing,
The ratio of the former to the latter is in the range of 10:90 to 80:20,
Plastisol for high-speed coating for wallpaper applications should be in the range of 20:80 to 70:30, and plastisol for dip molding should be in the range of 50:50 to 9.
A range of 0:10 is preferred. That is, depending on the use of the granular vinyl chloride resin, it is desirable to determine the blending ratio of particles with different particle sizes when preparing the mixed powder in the manufacturing process.

In order to compress the mixed powder described above in the method of the present invention, the mixed powder is supplied to a compressor that is a set of a filter drum roll that can reduce pressure and a pressure roll that presses the roll, and the pressure is reduced by a vacuum pump. In terms of production efficiency, it is desirable to adsorb the mixed powder in a layer on the surface of the filter drum, which has been made into a filter drum, and then forcibly compress it between both rolls while degassing to solidify it. Of course,
It can be compressed and solidified between rotating rolls without degassing, or
Alternatively, the mixed powder may be pressed and solidified while degassing using a press mold equipped with an air filter. The solidified mixed powder becomes brittle flakes with good handling properties. When producing a plastisol using the above-mentioned hardened flakes, the flakes have an average size in the range of 0.05 to 20 mm, preferably in the range of 0.1 to 10 mm, in order to speed up the dispersion speed in the plasticizer. It is preferable to crush or size the powder.

(Effects of the Invention) According to the method of the present invention, by mixing vinyl chloride resins with different average particle sizes, the resin can be effectively degassed,
The bulk specific gravity also increases significantly.

In addition, even if it is compressed and hardened, it is brittle and can be easily pulverized and sized.

The granular resin obtained by the method of the present invention does not crumble easily when applied with finger pressure, etc., does not form powder, has excellent fluidity, enables automatic weighing, improves the working environment, and has a high bulk specific gravity, so it can be packaged. , transportation and storage costs are reduced. Moreover, the granular resin can be easily dispersed by adding and mixing a plasticizer to form a plastisol with low viscosity and good viscosity stability. Moreover, since particles having different average particle sizes are suitably blended and solidified into one particle, it becomes unnecessary to weigh, blend, and prepare each time before use, which is beneficial because it leads to improved productivity. Therefore, the granular vinyl chloride resin produced by the method of the present invention has high utility value as a base resin.

〔Example〕

Next, the method for producing granular vinyl chloride resin of the present invention will be explained in detail with examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

The evaluation was performed as follows, and the results are summarized in the table.

<Bulk specific gravity and powder fluidity> Bulk specific gravity was measured according to JIS K6721. At this time, a 60g sample was placed in the funnel of the bulk specific gravity measuring device, and the time from when the damper was pulled out to when the sample completely fell from the funnel was measured. The smaller the falling time, the better the powder fluidity.

<Plastisol viscosity> Plastisol with the following formulation was prepared under conditions of temperature 23°C and humidity 50%, and the viscosity at 50 revolutions per minute of the Nα6 spindle was measured using a Brookfield viscometer. .

Vinyl chloride resin 100””DOP
60 polyoxyethylene octyl phenyl ether
1 <Viscosity stability> After leaving the above plastisol for one week, No. 6 was added again.
The viscosity was measured when the spindle rotated at 50 revolutions per minute, and was expressed as a value divided by the initial viscosity value. The smaller the value, the better the stability over time.

Sample A Vinyl chloride resin with an average particle size of less than 5 μm A polymerization reaction was carried out in an aqueous medium at 58°C for 8 hours using sodium lauryl sulfate as the main emulsifier, and then unreacted vinyl chloride monomer was recovered. An aqueous latex having resin particles with an average particle diameter of 0.85 μm was obtained.

Next, the latex was heated at a population temperature of 170°C and an outlet temperature of 52°C.
After spray drying under the conditions of C, the mixture was pulverized in a hammer mill to obtain a finely powdered vinyl chloride resin.

The average particle diameter of the obtained vinyl chloride resin was 4.3 μm.

Sample B Vinyl chloride resin with an average particle size of 5 μm or more 1 Vinyl chloride aqueous latex having resin particles with an average particle size of 0.85 μm used in the production of Sample A was subjected to conditions of an inlet temperature of 170°C and an outlet temperature of 65°C. After spray drying, the mixture was passed through a screen mesh with an opening of 70 μm to obtain a spherical vinyl chloride resin.

The average particle size of the obtained vinyl chloride resin powder was 17.5μ.
It was m.

Sample Cr Vinyl chloride resin with an average particle size of 5 μm or more 1 Suspension polymerization was carried out at 55°C for 10 hours using gelatin as a dispersant in an aqueous medium, and unreacted vinyl chloride monomer was recovered. After dehydrating and drying the slurry-like dispersion, the mesh size was 63.
Passed through a μm screen mesh, with an average particle size of 33
A μm blending resin was obtained.

The average particle diameters of Samples A to C were measured using a Horiba Laser Diffraction 2"LA-500".

Examples 1 to 7 A total of 20 kg of sample A, sample B, and sample C were prepared in the ratios (weight ratios) shown in the table to 100! ! , and the mixture was placed in a drum with a capacity of 100 mL, and the mixture was rotated in a drum tumbler for 20 minutes to prepare a mixed powder. Next, the mixed powder is supplied to a roll compressor equipped with a filter drum roll with a diameter of 160 mm that can be depressurized and a pressure roll with a diameter of 220 mm that presses the roll, and the mixed powder is depressurized by a vacuum pump. The mixed powder was adsorbed in a layer on the surface of the filter drum, compressed between both rolls while degassing, and discharged.

At this time, the degree of vacuum at the outlet of the filter drum roll was set to -500.
mm Hg, gap between both rolls 3 mm, roll rotation speed 3
Degassing and compression treatment were performed at rp-, respectively, to obtain irregularly shaped flaky resin. However, in Example 7, a flaky resin was obtained by performing roll compression treatment without vacuum degassing. Next, the flaky resin was supplied to a vertical sizing machine equipped with a 3 mm φ screen, and the discharged granular resin was used as a sample for evaluation.

Comparative Example 1 Sample A obtained by a normal base resin manufacturing method was subjected to evaluation as it was.

Comparative Example 2 Only Sample A was subjected to the same treatment as in Example 1, and then sized and subjected to evaluation.

Comparative Example 3 A powder prepared by mixing sample A and sample B at a ratio of 70:30 in a drum tumbler for 20 minutes was subjected to evaluation.

As seen in the evaluation results according to the examples, according to the present invention,
By mixing powders with an average particle diameter of less than 5 μm and powders with an average particle diameter of 5 μm or more and performing roll compression treatment, it has a large bulk specific gravity and good fluidity, and when it becomes plastisol, it is a granular form with low viscosity and excellent viscosity stability. It is clear that the resin can be manufactured efficiently.

Patent applicant: Mitsubishi Kasei Vinyl Corporation

Claims (1)

[Claims] 1) An average of powder produced by drying an aqueous latex obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride or a mixture of vinyl chloride and a comonomer copolymerizable therewith. A mixed powder of particles with a particle size of 5 μm or more and particles with an average particle size of less than 5 μm obtained by drying and pulverization, or a suspension with particles with an average particle size of less than 5 μm obtained by the above-mentioned pulverization. A method for producing a granular vinyl chloride resin, which comprises preparing a mixed powder with particles having an average particle diameter of 5 μm or more obtained by polymerization, and then solidifying the mixed powder into flakes by compressing the mixed powder. 2) The method for producing a granular vinyl chloride resin according to claim 1, wherein the compression is performed by pressing while degassing the mixed powder. 3) Mixed powder solidified into flakes by compression, with an average of 0
．． The method for producing a granular vinyl chloride resin according to claim 1 or 2, wherein the resin is pulverized or sized to a size in the range of 1 to 10 mm. 4) Claims 1, 2, or 3, wherein the mixing ratio of particles with an average particle diameter of 5 μm or more and particles with an average particle diameter of less than 5 μm is in the range of 5:95 to 95:5 by weight. A method for producing a granular vinyl chloride resin as described in 1.