JPH0819177B2 - Method for producing granular vinyl chloride resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention provides granules having a large bulk specific gravity, less powdering, good powder flowability, and extremely easy handling as a paste resin. The present invention relates to a method for producing vinyl chloride resin.

"Prior art" Vinyl chloride resin for paste is generally 2μ obtained by emulsion polymerization or fine suspension polymerization of vinyl chloride monomer.
It is produced by a method of spray-drying a latex containing vinyl chloride resin particles described below and then pulverizing strongly agglomerated coarse particles. The vinyl chloride resin obtained by the production method is a fine powder, has a low bulk specific gravity, has a bad packaging environment due to powdering, and has a high packaging cost and transportation cost, which is economically disadvantageous. Furthermore, the vinyl chloride resin is significantly inferior in powder fluidity to a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method, and it is difficult to apply an automatic weighing machine or the like. There was a limit to improvement in work.

In order to improve the above-mentioned drawbacks, a method of granulating a paste vinyl chloride resin is disclosed in JP-A-52-47853, but in this method, once the paste vinyl chloride resin is dried in a separate step. The method of granulation is adopted, and there is a work or economic disadvantage. Further, a method of adding a coagulant to a vinyl chloride resin latex, dehydrating with a decanter after coagulating vinyl chloride resin particles, and drying a putty-like wet cake is disclosed in JP-A-59-155403. However, with this method, the wet cake adheres to the inside of the casing of the decanter, and industrially continuous stable operation is difficult.

“Problems to be Solved by the Invention” In view of such circumstances, the present inventors have little dusting,
As a result of diligent study on a method for producing a vinyl chloride resin which has good powder fluidity and is easy to handle, the vinyl chloride resin latex was destroyed without spray-drying the vinyl chloride resin latex to aggregate the vinyl chloride resin particles. It was found that granular vinyl chloride resin, which can be industrially stable and can be used as a paste resin, can be efficiently obtained by post-pressurizing with a belt press or the like to dehydrate and then drying at a relatively low temperature. The invention was completed.

That is, an object of the present invention is to provide a method for producing a granular vinyl chloride resin, which has a large bulk specific gravity, a small amount of powdering, a good fluidity, and is easy to handle.

"Means for Solving Problems" Accordingly, the gist of the present invention is to provide a method for producing a granular vinyl chloride resin from a vinyl chloride resin latex produced by emulsion polymerization or fine suspension polymerization, wherein: A) Step of coagulating and destroying vinyl chloride resin latex by using coagulant (B) 50% water content of the destroyed vinyl chloride resin latex by filter press type dehydrator, belt press type dehydrator or tube press type dehydrator The method for producing a granular vinyl chloride resin comprises the steps of dehydrating and (C) drying the dehydrated vinyl chloride resin at a temperature of less than 80 ° C.

 The present invention will be described in detail below.

As the vinyl chloride resin latex used in the present invention, those produced by vinyl chloride or a mixture of vinyl chloride and a comonomer copolymerizable therewith by a fine suspension polymerization method or an emulsion polymerization method are used. Thus, as a comonomer copolymerizable with vinyl chloride, for example, vinyl acetate,
Vinyl esters such as vinyl propionate and vinyl laurate, acrylic acid esters such as methyl acrylate, ethyl acrylate and butyl acrylate, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, maleates such as dibutyl maleate and diethyl maleate. Fumarate esters such as acid esters, dibutyl fumarate and diethyl fumarate, vinyl ethers such as vinyl methyl ether, vinyl butyl ether and vinyl octyl ether, vinyl cyanides such as acrylonitrile and methacrylonitrile, ethylene, propylene and styrene Α-olefins such as vinylidene chloride, vinyl halides other than vinyl chloride such as vinyl bromide, and the like. These comonomers account for 30% by weight in the constituent components of the vinyl chloride resin. The amount used below is preferably 20% by weight or less.

Of course, the comonomers are not limited to those mentioned above.

Although the solid content concentration of the vinyl chloride resin latex varies depending on the ratio of the polymerizable monomer and water, the additives, and the degree of polymerization, it is desirable that the higher it is in consideration of the separation of water after the cohesive failure of latex, the size of the apparatus, etc. It is desirable to use one in the range of 30% by weight or more based on the total latex.

In the step (A) of the method of the present invention, as the aggregating agent, known aggregating agents such as polyvalent metal salts such as alum, magnesium sulfate and calcium acetate, polymer aggregating agents such as alginic acid, polyamine and polyacrylamide are applied. It
Among them, alkaline earth metal salts excluding halides, which can destroy the emulsifier system of latex over many types, are most preferable. This alkaline earth metal salt has the effect that the reaction product with the emulsifier acts as a heat stabilizer.

For example, as a method of destroying the vinyl chloride resin latex by using a coagulant, under mechanical agitation, agitation by a jet pump, agitation by an air ring, or the like,
There are a method of adding an aggregating agent to the vinyl chloride resin latex and a method of supplying the resin latex and the aggregating agent at a constant ratio to a twin-screw extruder type mixer.

The most preferred embodiment of the present invention is a method of feeding the concentrated resin latex and the aggregating agent to a twin-screw extruder type mixer. According to this method, since the vinyl chloride resin particles having a strong water-containing aggregate structure due to aggregation can be destroyed by the shearing force of the twin screw, it is possible to obtain an aggregate that is uniform and does not enclose water. .

Further, in the case of the method of adding the aggregating agent to the resin latex having a solid content of 40 to 50% under the simple stirring described above,
Not only does the vinyl chloride resin particles become agglomerates having a low fluidity to make stirring difficult, but it is difficult to obtain a uniform agglomerate, which easily causes turbidity of the superfluid during dehydration in the next step (B). Conversely, if the resin latex is diluted to a solid content of 15 to 20% and then mixed with an aggregating agent, uniform agglomeration can be obtained while maintaining fluidity even after aggregating, which is a preferred embodiment, but it is diluted with water before dehydration. Therefore, it is disadvantageous in terms of operation and economy. In this case, it is appropriate to add a flocculant with a solid content concentration of around 30%.

By such agglomeration operation, vinyl chloride resin particles having a size of 2 μm or less can be collected with a cloth having an opening of about 150 μm.

To recover the vinyl chloride resin particles from the destroyed vinyl chloride resin latex in the step (B) of the present invention, a filter press type dehydrator, a belt press type dehydrator or a tube press type dehydrator is used. It is preferable to employ a belt press type dehydrator or a tube press type dehydrator because it can be continuously operated and a large pressure can be applied.

For example, to collect vinyl chloride resin particles with a belt press type dehydrator or a tube press type dehydrator,
Continuously supplying a broken vinyl resin latex chloride in belt or tube, when surface pressure 1 kg / cm ² or more belt press, the linear pressure 1 kg / cm ² or more pressure, and if surface pressure of the tube press A pressure of 40 kg / cm ² or more is applied to dehydrate water to 50% or less, preferably 40% or less. In order to make the recovered vinyl chloride resin particles into granules, it is necessary to adjust the water content to the above value, and it is possible to easily dehydrate the water content to the above water content by applying pressure.

Aggregates of vinyl chloride resin particles that have been dehydrated to a water content of 50% or less are obtained in a sheet form, so if necessary, crushed into granules, or crushed ones further known as screw type, pressure type, etc. It can be granulated by supplying it to a granulator.

In the step (C) of the method of the present invention, the dehydrated vinyl chloride resin is dried by a known method such as a shelf dryer, a fluid dryer, a rotary kiln or the like, which is used for a vinyl chloride resin produced by a suspension polymerization method. A dryer can be used. In particular, a rotary kiln is preferable because the drying efficiency is low and the dehydrated vinyl chloride resin particle aggregates do not collapse into fine powder. As the drying conditions in the method of the present invention, a temperature of less than 80 ° C, preferably 10 to 70 ° C, especially 30 to 60 ° C is selected.

Vinyl chloride resin, when made into plastisol,
Since the viscosity of plastisol is governed by thermal history, it is necessary to shorten the heating time in the case of high temperature drying. When the vinyl chloride resin is made into a granular form as in the method of the present invention, the surface area per unit weight becomes small, and it becomes difficult to dry it in a short time. Therefore, the method of the present invention requires drying at a relatively low temperature, and it is important to reduce the heat history of the vinyl chloride resin. If the drying temperature is higher than 80 ° C, the resulting vinyl chloride resin may have an extremely high viscosity when it is made into blastisol, or it may not be possible to form a fluid plastisol. , The drying time becomes longer and the drying efficiency becomes worse,
This results in poor productivity.

The granular vinyl chloride resin obtained by the method of the present invention was obtained as a vinyl chloride resin for paste, for applications such as flooring materials, wall materials, interior materials for automobiles, and by suspension polymerization method and bulk polymerization method. It is used as a fluidity improver for vinyl chloride resins.

"Effect of the Invention" According to the method of the present invention, unlike the spray drying method in which all the water of the vinyl chloride resin latex is evaporated by heat energy, most of the water is mechanically separated and removed, so the drying energy is reduced. It is economically advantageous and industrially advantageous. And, the granular vinyl chloride resin obtained by the method of the present invention has a large bulk specific gravity, has less powder standing, and has excellent powder fluidity, so that it is possible to employ an automatic weighing machine, and a packaging workshop, Environmental hygiene at each location such as shipping and unpacking workshops will be improved, and it will also help to reduce various costs such as packaging and transportation due to a significant bulk ratio.

Further, since the granular vinyl chloride resin obtained by the method of the present invention forms a gradual agglomerate, the agglomerate is easily broken by mixing it with a plasticizer and slightly stirring it to give a low viscosity. Plastisol is prepared (prepared).

"Examples" Next, the method of the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

The physical properties of vinyl chloride resins produced by the methods described in Examples and Comparative Examples were tested as follows, and the results are summarized in the table.

<Bulk specific gravity and powder fluidity> Bulk specific gravity: Based on JIS K 6721.

Powder flowability: 60 g of a sample (vinyl chloride resin) was placed in the funnel of the bulk specific gravity measuring device, and the time from when the damper was pulled out until the sample all dropped from the funnel was measured.

The smaller the dropping time, the better the powder fluidity.

<Plastisol viscosity> A plastisol having the following formulation was prepared under the conditions of an air temperature of 23 ° C and a humidity of 50%, and the viscosity of the No. 6 spindle at 50 revolutions per minute was measured using a Brookfield viscometer. .

Vinyl chloride resin 100 parts by weight DOP (di-2-ethylhexyl phthalate) 60 Polyoxyethylene octylphenol ether 1
<Pulsation test in plastisol> Based on JIS-K-5400 crushing test (B) judgment method.

Example 1 Fine suspension polymerization was carried out in a water medium using a higher fatty acid ammonium salt as a main emulsifier to obtain an average particle size of 0.9μ and a solid content of 40%.
A vinyl chloride resin latex with a water content of 60% was obtained. After passing the latex through a 235 mesh (63μ) screen, the latex and a 10% aqueous solution of calcium acetate were fed to a twin screw extruder at a ratio of 4 aqueous calcium acetate solution to 100 latex using a metering pump.

The creamy aggregate having a water content of 62% coming out of the twin-screw extruder was supplied to a tube press (manufactured by Ashizawa Iron Works Co., Ltd.) and dehydrated under pressure at a pressure of 100 kg / cm ² for 2 minutes. The liquor was clear. The dehydrated aggregate cake had a water content of 24%. This agglomerate cake is crushed and sieved to 0.5-2mm
Particles were obtained. The particles were placed in a rotary dryer equipped with a heat transfer tube and dried under reduced pressure at 30 ° C. for 2 hours to obtain a granular vinyl chloride resin.

Example 2 Fine suspension polymerization was carried out in a water medium using a higher fatty acid ammonium salt as a main emulsifier to obtain an average particle size of 0.9μ and a solid content of 40%.
A vinyl chloride resin latex with a water content of 60% was obtained. After the above latex was passed through a 235 mesh (63μ) screen, the latex and a 10% aqueous solution of calcium acetate were fed to a twin-screw extruder at a ratio of 4 aqueous calcium acetate solution to 100 latex using a metering pump.

The cream-like agglomerate with a water content of 62% that came out of the twin-screw extruder was fed to a belt press type dehydrator to obtain a surface pressure of 5 kg / cm ² ,
It was dehydrated at a linear pressure of 60 kg / cm. The liquor was clear. The water content of the dehydrated cake was 35%. The agglomerate cake was crushed and sieved to give particles of 0.5-2 mm. The particles are put into a rotary dryer equipped with a heat transfer tube and decompressed.
It was dried at 30 ° C. for 2 hours to obtain a granular vinyl chloride resin.

Examples 3 to 6 In Example 1, the drying conditions in the rotary dryer were 40 ° C. for 1 hour (Example 3), 50 ° C. for 30 minutes (Example 4), and 60 ° C. for 30 minutes (Example 5). And 30 at 70 ° C
A granular vinyl chloride resin was obtained in the same manner as in Example 1 except that the time was changed (Example 6).

Comparative Example 1 The procedure of Example 1 was repeated, except that the rotary dryer was dried at 80 ° C. for 30 minutes.

Comparative Example 2 The vinyl chloride resin latex of Example 1 was spray dried with a spray dryer equipped with a rotary disk type sprayer under conditions of an inlet temperature of 170 ° C. and an outlet temperature of 52 ° C., pulverized with a pulverizer, and then finely divided. A powdered vinyl chloride resin was obtained.

Comparative Example 3 In Example 1, DOP was used instead of calcium acetate.
Was fed to a twin-screw extruder at a ratio of DOP3 to 100 of latex, and the same procedure as in Example 1 was performed. Aggregates coming out of the twin-screw extruder are cloudy liquids with insufficient aggregation, and the liquid was supplied to a tube press for dehydration, but most of the resin particles escaped to the filtrate side, and the aggregate cake It was not obtained, and the physical property test could not be performed.

Claims (1)

[Claims] 1. A method for producing a granular vinyl chloride resin from a vinyl chloride resin latex produced by emulsion polymerization or fine suspension polymerization, comprising: (A) a step of cohesively breaking a vinyl chloride resin latex using a coagulant. B) A step of dehydrating the destroyed vinyl chloride resin latex with a filter press type dehydrator, a belt press type dehydrator or a tube press type dehydrator to a water content of 50% or less, and (C) dehydrating the vinyl chloride resin. A method for producing a granular vinyl chloride resin, which comprises a step of drying at a temperature of less than ° C.