JPS61188402A - Production of particulate vinyl chloride resin for paste - Google Patents

Abstract

PURPOSE:To obtain the title resin excellent in blooming resistance, etc., by forming a PVC resin emulsion by using a maleic acid copolymer salt as an emulsifier and preparing PVC resin agglomerates by adding a difficultly water- soluble organic liquid to the emulsion. CONSTITUTION:Vinyl chloride or a mixture thereof with a copolymerizable vinyl compound (e.g., vinyl acetate) is polymerized in an aqueous medium in the presence of a water-soluble polymerization catalyst or a redox polymerization catalyst consisting of a water-soluble reducing agent and an organic hydroperoxide by using a maleic acid copolymer salt as an emulsifier. To the obtained vinyl chloride resin emulsion a difficultly water-soluble organic liquid which does not dissolve or swell the vinyl chloride resin (e.g., dioctyl phthalate is added and mixed to prepare vinyl chloride resin agglomerates, which are separated, dehydrated and dried to obtain the purpose particulate vinyl chloride resin for paste.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to a plume phenomenon that occurs on the surface of a molded product due to an emulsifier contained in a vinyl chloride resin for paste processing.
Alternatively, the present invention relates to a method for producing a granular vinyl chloride resin for paste processing, which is intended to prevent molded products from whitening, low transparency, etc. due to moisture absorption.

(Prior art) Vinyl chloride resin for paste is usually produced through emulsion polymerization, seeded emulsion polymerization or fine suspension polymerization process, spray drying process and, depending on the case, a crushing process combined with this process. It has an average particle size of 12 to 2 micrometers, and is a collection of primary particles that are close to true spheres and has a secondary particle size of several tens of micrometers, and is usually processed in powder form. . When processing it, first, vinyl chloride and vinyl resin powder are mixed and dispersed in a plasticizing agent along with heat stabilizers, fillers, a-materials, and other mixtures, which is called a paste sol. A resin composition is obtained. This glue-like composition is then poured into cedar molding.

-5゜These paste-sols are processed into final molded products by molding methods such as slush molding, single rotation molding, spread coat molding such as knife coat coating, and screen coating molding. Depending on the processing method and the type and amount of components other than the resin in the paste sol, the emulsifier and trace amounts of water contained in the resin may remain as air bubbles in the paste sol, causing pinholes in the molded product. The product easily absorbs all of the water (which may result in whitening or poor transparency, or residual emulsifier may precipitate).
In order to improve these drawbacks, it is conceivable to reduce the total amount of emulsifier used, but this results in the generation of lumps and a decrease in mechanical stability, resulting in a significant loss of productivity. Therefore, in order to obtain a vinyl chloride resin with good water resistance and less precipitation, a compatible and highly dispersible emulsifier is desired.

Furthermore, when producing vinyl chloride resin industrially, the selection of a catalyst is also important in order to obtain a latex with high mechanical stability.

(Problem that the invention attempts to solve) The inventor has achieved thermal stability, water resistance, plume resistance.

A method for producing a vinyl chloride resin for granular paste that provides a molded article from a paste sol with good transparency and a stable polymerization reaction was developed (as a result of intensive research, the present invention was discovered).

(Means for Solving the Problems) That is, the present invention provides vinyl chloride or a mixture of vinyl chloride and a vinyl compound copolymerizable with vinyl chloride under a water-soluble polymerization catalyst or under a water-based reducing agent and an organic hydroperoxide. Polymerization is carried out in an aqueous medium using a maleic acid copolymer salt as an emulsifier under a redox polymerization catalyst of For pastes, characterized in that an aggregate of vinyl chloride resin is prepared by adding and mixing an organic liquid that does not contain the organic liquid, and then the aggregate is dehydrated and the granular vinyl chloride resin is recovered by drying. This invention relates to a method for producing vinyl chloride resin.

The vinyl compound copolymerizable with vinyl chloride in the present invention includes vinyl acetate and vinyl globionate.

Vinyl esters such as vinyl myristate, vinyl oleate, vinyl benzoate; acrylic acid, methacrylic acid, maleic acid, fumaric acid. Unsaturated carboxylic acids such as cinnamic acid or their anhydrides; esters of acrylic acid such as methyl, ethyl, butyl, octyl, and benzyl; esters of methacrylic acid such as methyl, ethyl, butyl, octyl, and benzyl; maleic acid esters; Unsaturated carboxylic acid esters such as fumaric acid esters and cinnamic acid esters: methyl vinyl ether, ethyl vinyl ether, phthyl vinyl ether, octyl vinyl nial, myristyl-
Vinyl ether II such as vinyl ether; z Monoolefins such as tyrene, propylene, phthene, and pentene; ordinary vinyl that can be radically copolymerized with vinyl chloride, such as vinylidene chloride, styrene and its derivatives, acrylonitrile, methacrylonitrile, etc. It refers to one or more compounds, and can be used in a mixture with vinyl chloride, usually in an amount of up to 50%.

The water bath polymerization catalyst in the present invention is a persulfate such as ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, etc. The amount of this catalyst used is o, oos, etc. ~3% by weight O Water-soluble reducing agent is ethylenediaminetetraacetic acid.

A complex compound of its sodium or potassium salt, ethylenediaminetetraacetic acid, or its sodium or potassium salt and six heavy metals such as iron, copper, and chromium.

Sulfinic acids, their sodium or potassium salts,
l-Ascorbic acid, its sodium, potassium or calcium salts, ferrous birophosphate.

Reducing agents used as common radical redox polymerization catalyst components that are soluble in water, such as ferrous sulfate, ferrous ammonium sulfate, sodium sulfite, sodium bisulfite, sodium formaldehyde sulfoxylate, and reducing sugars. The amount of reducing agent used is usually 100,001 to 5% by weight relative to the monomer; if it is outside this range, the polymerization reaction may not proceed smoothly. It is not possible to add the reducing agent at the initial stage of polymerization.

The organic hydroperoxide in the present invention includes:
For example, tertiary amyl hydroperoxide,
Tertiary-butyl hydroperoxide, isopropyl hydroperoxide, cumene hydroperoxide, paracymene hydroperoxide, tertiary-butylinopropylbenzene hydroperoxide.

Diisoglobilbenzene hydroperoxide.

Examples include paramenthane hydroperoxide and decalin hydroperoxide. ◇ Two or more of these may be used as a combined component. ◇ The amount of organic hydroperoxide used is usually 0.00% relative to the monomer.
1 to 5 weight.

The maleic acid copolymer salt in the present invention includes maleic acid or maleic anhydride and styrene.

Ethylene, 7o pyrene, vinegar [Examples include mono- or diammonium salts, sodium salts, and potassium salts of copolymers such as vinyl, methyl vinyl ether, butadiene, etc.0 Maleic acid or maleic anhydride in the copolymer The copolymerization ratio is 10^90 mol, preferably 30 to 60 mol. The amount of the maleic acid copolymer salt to be used is preferably 105 to 15% by weight based on the monomer from the viewpoint of stability of the polymerization reaction. a, 05
If it is less than 15% by weight, a large amount of lumps will be generated.
When the amount is more than 10%, the polymerization reaction rate is significantly delayed and degassing properties are often poor. In addition, 0.
When it is less than 5% by weight, the viscosity properties of the paste sol are particularly good.

In addition, when a maleic acid copolymer that is not a salt is used as an emulsifier, a large amount of lumps may be generated, or sometimes only lumps may be obtained, and an emulsion may not be obtained. When an anionic surfactant is used as an emulsifier, the degassing operation after the completion of the polymerization reaction is extremely difficult due to intense bubbling.

In the production of the resin in the present invention, the entire amount of vinyl chloride or a mixture of vinyl chloride and a vinyl compound copolymerizable with vinyl chloride, an emulsifier, water, a polymerization catalyst, and if necessary a PH regulator, a chain transfer agent, seeds, etc. is reacted in advance. It is carried out by emulsion polymerization method or seeded emulsion polymerization method in which the polymerization reaction is carried out under normal conditions by placing the polymer in a container or by continuously adding it.

The weight ratio of monomer/water is Q, 85 or less, especially α30~(
L is preferably set to 70. If this ratio exceeds a, 85, a large amount of lumps may be generated in the polymerization system. On the other hand, the lower limit is 0, which is determined as appropriate depending on the required productivity.
'i6 or more is preferable. p! ! is usually prepared using ammonia, sodium hydroxide, sodium bicarbonate,
It is made with ammonium carbonate, etc. If the maleic acid copolymer salt is continuously added during the polymerization, the resulting vinyl chloride resin paste sol will have a low viscosity (preferably 0). 35-5 from the point of
The temperature is 5°C, preferably 40-50°C.

The organic liquid used to recover the granular vinyl chloride resin from the vinyl chloride resin emulsion thus prepared is generally one that is difficult to dissolve in water and does not dissolve or swell the resin tube. The liquid to be used has a melting point of 20° C. or lower and a boiling point at normal pressure higher than the temperature at the time of resin recovery of the present invention, preferably 200° C. or higher. When an organic liquid having a boiling point lower than the temperature at the time of resin recovery is used, additional equipment is required for recovery of the resin that evaporates, which is not economical. Of course, as a single product, even if it does not meet the above conditions, it is fine as long as it meets the above requirements as a mixture. ◎The first reason is to reduce the amount entrained in the separated pot water phase after mixing with the emulsion, prevent loss of organic liquid, and reduce the effort of wastewater treatment. The second reason is that in order to disperse resin particles in water and aggregate them via an organic liquid, it is necessary for the organic liquid to exist as a liquid phase with an interface between the resin particles and the water. It's sinking. Furthermore, if the organic liquid is one that dissolves or swells the resin, the resin particles may be deformed or altered, which is disadvantageous. Therefore, substances that have a negative effect on processability and quality of molded products must be avoided.

In view of the above points, it is most rational to use a liquid compounding agent used in ordinary paste processing as the organic liquid.

Examples of the organic liquid in the present invention include the following +11 to (
9) can be mentioned.

+11 Heptatalic acid alkyl ester plasticizers such as dioctyl phthalate, dinonyl phthalate, butyl lauryl phthalate, and methyl oleyl phthalate (2) Aromatic carbonic acid ester plasticizers such as trioctyl trimellitate and diethylene glycol dibenzoate (3) Aliphatic dibasic acid ester plasticizers such as dioctyl adipate, dibutyl sebacate, and dioctyl tetrahydroctate (4) Phosphate ester plasticizers such as trioctyl phosphate and trichloroethyl phosphate (5) Diethylene glycol cicafrey) , 1.
Fatty acid glycol ester plasticizers such as 4-phthylene gelicol-di-2-ethylhexanoate (6) Polyester plasticizers (7) Butyl oleate, methyl acetyl ricinolate, 2.2.4- ) dimethyl-1 , 3-penta/diol diisobutyrate and other fatty acid ester secondary plasticizers, epoxidized soybean oil, epoxy octyl stearate and other epoxy secondary plasticizers, chlorinated fatty acid methyl, chlorinated paraffin such as chlorinated paraffin. secondary plasticizer, Kono・
Aliphatic dibasic acid ester secondary plasticizers such as dioctyl phosphate (8) Petroleum-based diluents such as mineral spirit and mineral turpentine, long-chain alkylbenzene diluents such as dodecylbenzene (9) Higher alcohols, liquid paraffin, The amount of the liquid lubricant organic liquid such as higher fatty acid alkyl ester is usually Q, 5 to 30 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight of the resin in the emulsion.
It is 15 parts by weight. If it is less than 15 parts by weight, the resin cannot be sufficiently aggregated through the organic liquid, and if it exceeds 3031[jt part, sol-like aggregates are likely to be formed (even if granular aggregates are formed, the organic Due to the large liquid content, it may be difficult to remove residual liquid in the subsequent drying process, which may lead to a decrease in productivity.The organic liquid may be added to the emulsion all at once, or it may be added in portions or continuously. May be added.

As a device for mixing the emulsion and the organic liquid, a batch type stirring tank type, mixer, container rotating type mixer, etc. are suitable.

The organic liquid and emulsion are mixed at i! below 70°C.
degree, and the organic liquid used is resin t-I! It is carried out at a temperature that does not cause decomposition or swelling, but it should preferably be carried out at a temperature below 50°C because the higher the temperature, the faster the rate of swelling of the resin by the organic liquid increases.If it exceeds 70°C, the absorption of the organic liquid into the resin will be accelerated. Moreover, there is a risk that the resin will soften and coalesce, making the final product no longer suitable for processing.

Next, when dehydrating the aggregated resin particles via the organic liquid, a known method is employed depending on the shape of the captured resin. However, the temperature must be kept at 70° C. or lower to prevent softening and coalescence of the resin.

The resin particles separated in the dehydration process are then sent to a drying process to remove adhering moisture. Although a normal drying device can be used in this drying step, it is necessary to set conditions such that the strength of resin aggregation and coalescence does not impair dispersibility during processing. That is, the temperature of the resin to be dried during the drying step is set to be 70°C or less, preferably 50°C or less.

In addition, when the resin from the vinyl chloride resin emulsion obtained by the above polymerization method is recovered by a normal drying method such as spray drying, coagulation using a coagulant, dehydration drying, direct filtration dehydration drying, etc. Since it is difficult to sufficiently remove the emulsifier used during polymerization and coagulants etc. are mixed in, it is difficult to obtain resin molded products with excellent thermal stability, transparency, water resistance, etc. as in the present invention. -0 (Effect of the invention) According to the present invention, the polymerization reaction is stable, and the recovery efficiency when recovering granular resin is extremely high, which is true for dehydration operations! 2. When using the filtration method, there is less foaming of p-filtered water (very easy to operate). Also, since the obtained resin is granular, there is less scattering of powder during paste sol production (and fluidity is lower). is excellent.

Furthermore, when made into a paste sol, the dispersibility is good, and the molded products have excellent thermal stability, transparency, water resistance, and plume resistance.

(Example) The present invention will be explained below with reference to examples. ◇Example 1 5.5 liters of deionized water, average particle size Q, 51 micron, minimum particle size & [132 micron, maximum particle size Q, 55 micron vinyl chloride resin 3
Emulsion containing 0% by weight o, 5lcp, z-ascorbic acid 900IIIg, ferrous ion ethylenediamine-sodium acetate complex salt 30d, sodium pyrophosphate 6? to adjust the pH to 7, replace with nitrogen, and degas under reduced pressure (
After repeated deoxidation, 3kyk vinyl chloride was added.
The contents were heated from the jacket while stirring, and the temperature was continuously adjusted to 50°C.

On the other hand, cumene hydroperoxide 400W), monopotassium salt of methyl vinyl ether-maleic anhydride equimolar copolymer 1? , water 400) were mixed with a high-speed stirrer,
A cumene hydroperoxide emulsion was prepared separately. Also, monopotassium salt of methyl vinyl ether-leic anhydride equimolar copolymer 14? , water 400? An aqueous solution of was prepared separately.

Next, a separately prepared cumene hydroperoxide emulsion f: 25c was passed through a one-lunger metering pump.
was introduced into the reactor at a rate of c/h.

Start of introduction of cumene hydroperoxide emulsion 1
After a period of time, a separately prepared monopotassium methyl vinyl ether-maleic anhydride copolymer aqueous solution was introduced into the reaction system at a rate of 5 occ for 7 hours using a Granger type fixed-lid pump.

(The polymerization reaction was carried out for 16 hours, and the polymerization conversion rate was about 90.
%, unreacted monomers were removed.

The vinyl chloride resin emulsion thus obtained was passed through a screen covered with a wire mesh with openings of 74 microns.
Add water to the passed emulsion to reduce the solids content to 303
It was adjusted to 1t%. Next, this emulsion 11000
? was placed in a seed-type mixing device with a diameter of 20 scratches and an internal volume of 12), and stirring was started at 1 liter and 100 rpm. At the same time, di-2-ethylhexyl phthalate was added at a rate of 5?5 minutes from the bottom of the mixing device. was injected for 60 minutes at a rate of . After the injection was completed, the stirring operation was continued for an additional 60 minutes at 110 Q rpm, and an aqueous dispersion of granular resin was obtained. When this dispersion was vacuum-filtered using a door cloth with an aeration rate of 80 ec/sec・1" to separate the granular resin, 5100J
A wet granular product of ' was obtained. This was dried at 30° C. for 15 hours in a hot air circulation dryer to obtain a granular vinyl chloride resin (A) of 35705'.

Example 2 The redox polymerization catalyst emulsion used in Example 1, ie! - Ammonium persulfate 50% as a substitute for ascorbic acid, sodium ethylenediaminetetraacetic acid complex salt of ferrous ion and cumene hydroperoxide emulsion.
0119'! The emulsifier used in Example 2, i.e. 5580.9 was prepared in the same manner as in Example 2, except that styrene-maleic anhydride equimolar copolymer diammonium salt isgy was used instead of the monopotassium salt of methyl vinyl ether-maleic anhydride equimolar copolymer. Granular vinyl chloride resin (C)' was obtained.

Comparative Example 1 A vinyl chloride resin emulsion obtained by the same polymerization method as in Example 2 was heated to a population temperature of 170°C using a spray dryer.
The mixture was dried at an outlet temperature of 50° C. and pulverized using a tabletop pulverizer to obtain a finely powdered vinyl chloride resin (D).

Comparative Example 2 525090 granular chloride was prepared in the same manner as in Example 2 except that sodium lauryl sulfate 509 was used instead of the emulsifier used in Example 2, that is, the monopotassium salt of methyl vinyl ether-maleic anhydride equimolar copolymer. A vinyl resin (E) was obtained.

(Evaluation of vinyl chloride resin properties) Recovery efficiency, powder properties (angle of repose, bulk ratio X) and sol (resin 5
0#, di-2-ethylhexyl phthalate 30,9
．． Ba/Zn-based stabilizer 11t - Mixed and cleaved with one limestone machine) Properties (nosfine resistance, thermal stability, transparency, water resistance, bloom) were evaluated as follows. The results are shown in the table.

The angle of repose indicates the ease of fluidity of powder; the smaller the value, the better the fluidity.

It is the apparent density of bulk specific gravity powder, and the larger the value, the better the twist handling property.

This indicates the viscosity of the resin particles in the North Fineness sol, and the number is thicker and finer than the trout (8 is the finest and 0 is the roughest).The thermostable sol is poured into an aluminum mold and placed in a hot air atmosphere at 190℃. Change in color tone after 30 minutes t-A (small change) ~
0 Transparency displayed in 5 stages of 2 (large change) 0 Transparency of the 0.511 thickness of the sol heated at 190°C for 10 minutes to form a sheet, the light transmittance (@ was measured using an integrating sphere spectroscopy FT and a positioning needle) did.

The same sheet used for measuring water resistance and transparency was placed in water at 23°C for 2 hours.
The light transmittance (S) was measured for the sheet that had been immersed for 4 hours. After the same sheet used for the plume transparency measurement was left for 3 months, it was visually observed whether powdery substances had formed on the surface.

Claims (1)

[Claims] Vinyl chloride or a mixture of vinyl chloride and a vinyl compound that can be copolymerized with vinyl chloride is mixed with a maleic acid copolymer salt as an emulsifier under a water-soluble polymerization catalyst or under a redox polymerization catalyst consisting of a water-soluble reducing agent and an organic hydroperoxide. By adding and mixing an organic liquid that is sparingly soluble in water and does not dissolve or swell the vinyl chloride resin into the resulting vinyl chloride resin emulsion, the vinyl chloride resin is polymerized in an aqueous medium. 1. A method for producing a granular vinyl chloride resin for paste, which comprises preparing an aggregate, then dehydrating and drying the aggregate to recover granular vinyl chloride resin.