JPS61205A - Production of vinyl chloride resin for paste technique - Google Patents

Abstract

PURPOSE:To produce a vinyl chloride resin for paste technique which can form a molding having good water resistance, blooming resistance, transparency, etc., by polymerizing vinyl chloride in an aqueous medium by using a specified emulsifier. CONSTITUTION:A maleic acid copolymer salt (e.g., diammonium salt of a copolymer comprising equimolar amounts of methyl vinyl ether and maleic anhydride) is used as an emulsifier in polymerizing 0.85pt.wt. or below, per pt.wt. aqueous medium, vinyl chloride (optionally, together with a nearly equimolar amount of vinyl acetate or the like) at about 35-55 deg.C in an aqueous medium (preferably, of a pH >=6) by using 0.05-1.5wt%, based on the monomer, said emulsifier in the presence of a catalyst, i.e. a water-soluble polymerization catalyst or a redox polymerization catalyst comprising a water-soluble reductant and an organic hydroperoxide.

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 vinyl chloride resin for paste processing, with the aim of preventing whitening of molded products, reduction in transparency, etc. due to water absorption.

(Conventional technology) PVC resin for paste is usually emulsion polymerized.

It is produced through a seeded emulsion polymerization or fine suspension polymerization process, a spray drying process, and in some cases a pulverization process combined with this process, and primary particles with an average particle size of 0.2 to 2 microns, which are close to perfect spheres, are secondary to a number of secondary particles. It is aggregated into particles with a diameter of 10 microns, and is usually processed in powder form. In its processing, a resin composition called Punstisol is obtained by first mixing and dispersing AI vinyl resin powder in a plasticizer together with a heat stabilizer, filler, pigment, and other compounding agents. This paste-like composition is then cast.

It is processed into a final molded product by a molding method such as slush molding, single rotation molding, spread coat molding such as knife coat or roll coat, or screen coating molding.

Depending on the processing method of these zolastisols and the types and amounts of components other than resin in the plastisol, the emulsifier and trace amounts of water contained in the resin may remain as air bubbles in the plastisol, resulting in pinholes in the molded product. Or, the molded product easily absorbs water and becomes white, or its transparency deteriorates. Also, residual emulsifier may precipitate.

In order to improve these drawbacks, it is conceivable to reduce the amount of emulsifier used, but this results in the generation of lumps and a decrease in mechanical stability, which significantly impairs 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 developed a product that has defoaming properties, water resistance, and bloom resistance.

In order to develop a method for producing a vinyl chloride resin for paste that provides a molded product made of zola stisol with good transparency, has a stable polymerization reaction, and generates a small amount of lumps, the present invention was discovered as a result of intensive research. .

(Means for Solving the Problems) That is, the present invention provides vinyl chloride or a mixture of vinyl compounds copolymerizable with vinyl chloride under a force polymerization catalyst or from a water-soluble reducing agent and an organic hydride tetraperoxide. When polymerizing in an aqueous medium under a redox polymerization catalyst, a maleic acid copolymer salt is used as an emulsifier at a ratio of 0.
The present invention relates to a method for producing a vinyl chloride resin for paste, characterized in that the amount of vinyl chloride resin used is 0.05 to 1.5% by weight, and the weight ratio of monomer/water is 0.85 or less.

The vinyl compounds copolymerizable with vinyl chloride in the present invention include vinyl acetate and vinyl propionate.

Vinyl esters such as vinyl myristate, vinyl oleate, vinyl benzoate; acrylic acid, methacrylic acid,
Unsaturated carboxylic acid or its anhydride such as maleic acid, fumaric acid, cinnamic acid; methyl, ethyl, butyl acrylic acid,
Esters such as octyl and benzyl, esters of methacrylic acid such as methyl, ethyl, butyl, octyl, and benzyl, unsaturated carboxylic acid esters such as maleic acid ester, fumaric acid ester, and cinnamic acid ester: Methyl.

Vinyl ethers such as ethyl, zotyl, octyl, myristyl vinyl ether: ethylene.

Monoolefins such as propylene, butene, butene, etc.:
Vinylidene chloride, styrene and its derivatives.

One or more ordinary vinyl compounds, such as acrylonitrile and methacrylonitrile, which can be radically copolymerized with vinyl chloride, and usually contain 50%
It can be used up to the weight limit.

The water-soluble polymerization catalyst in the present invention includes persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, hydrogen peroxide, etc., and the amount of this catalyst used is 0.005 to 0.05 per monomer. The water-soluble reducing agent at 3% by weight is ethylenediaminetetraacetic acid.

its sodium or potassium salt, ethylenediaminetetraacetic acid or a complex compound of its sodium or potassium salt with heavy metals such as iron, copper, chromium, sulfinic acid, its sodium or potassium salt, t-ascorbic acid,
Its sodium, potassium or calcium salts, ferrous pyrophosphate.

Reducing agents used as common radical redox polymerization catalyst components that are soluble in water, such as ferrous sulfate, ferrous ammonium sulfate, thorium sulfite, sodium bisulfite, sodium formaldehyde sulfoxylate, and reducing m-classes. This is at least one kind of thing. The amount of the reducing agent used is usually 0.00001 to 5% by weight based on the monomer, and if it is out of this range, a smooth polymerization reaction cannot be carried out. The reducing agent is added at the initial stage of polymerization.

As the organic hydroperoxide in the present invention,
For example, tertiary amyl hydroperoxide, monooxide, tertiary butyl hydroperoxide, isopropyl hydroperoxide, cumene hydroperoxide, paracymene hydroperoxide, tertiary butyl isopropylbenzene hydroperoxide.

Diisopropylbenzene hydroperoxide.

Examples include paramenthane hydrogen, monooxide, and decalin hydroperoxide. Two or more of these can also be used as combined components. The amount of organic hydroperoxide used is usually 0,001 to the monomer.
~5% by weight.

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

All examples include monoal or diammonium salts, sodium salts, and potassium salts of co-electronic substances such as ethylene, propylene, vinyl acetate, methyl vinyl ether, and butadiene. The copolymerization ratio of maleic acid or maleic anhydride in the copolymer is 10 to 90 mol, preferably 30 to 60 mol. The amount of this maleic acid copolymer salt to be used should be 0 to 10% of the monomer from the viewpoint of stability of the polymerization reaction.
．． It is necessary to set the weight ratio to 0.05 to 1.5. 0.0
If it is less than 5% by weight, a large amount of lumps will occur, and 1
．． If the amount of 5 weight cracks is too large, the polymerization reaction rate will be significantly delayed and the degassing properties will be poor. In addition, when the weight is less than 0.05%, the viscosity characteristics of the plastisol are particularly good.

Incidentally, copolymerization of maleic acid without salt as an emulsifier (K1-1 is used in large quantities) may result in formation of lumps, or sometimes only lumps may be obtained and latex may not be obtained. Furthermore, 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 regulator, a chain transfer agent, seeds, etc., is prepared 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 it in a reactor or by continuously adding it.

However, it is necessary that the weight ratio of monomer/water be 0.85 or less, preferably 0.30 to 0.70. If this ratio exceeds 0.85, a large amount of lumps will be generated in the polymerization system. On the other hand, the lower limit is determined as appropriate depending on the required productivity. In addition, in order to prevent the generation of a large amount of lumps, it is preferable that - of the polymerization system is 6 or more. P)I is usually prepared using ammonia, hydroxide, sodium bicarbonate, ammonium carbonate, etc. Further, when the maleic acid copolymer salt is continuously added during the polymerization, the resulting plastisol of vinyl chloride resin has a low viscosity and is suitable. In addition, the polymerization temperature was set at 35°C from the viewpoint of polymerization stability.
-55°C, preferably 40-50°C.

As a method for recovering vinyl chloride resin from the vinyl chloride resin emulsion prepared according to the present invention, a conventional drying method for paste vinyl chloride resin can be employed.

Examples of the drying method include a multi-MW rotating disk type and a single-disk type rotating disk type.

Examples include spray drying using a nozzle method, centrifugal dehydration drying of vinyl chloride resin after coagulating and breaking the emulsion with an inorganic salt or alcohol, and direct filtration dehydration of vinyl chloride resin emulsion. In some cases, a known method of pulverizing vinyl chloride resin for paste, such as a hammer mill or bottle mill type, is then combined.

(Example) The present invention will be explained below with reference to examples.

Example 1 5.5 liters of deionized water, an average particle size of 0.51 S, a minimum particle size of 032 μm, a maximum particle size of 0.55 micron vinyl chloride resin 30
9, t-ascorbic acid 90079, ferrous ion sodium ethylenediaminetetraacetic acid complex salt 30μ, and sodium pyrophosphate 6g were added to the emulsion containing 0.5% by weight to adjust the pH to 7, and the mixture was repeatedly purged with nitrogen and degassed under reduced pressure. After deoxidizing, 9'fI: was added to vinyl chloride 3, and the contents were heated in a jacket while stirring, and the temperature was continuously adjusted to 50°C.

Separately, cumene hydroperoxide emulsion was separately prepared by mixing 1 g of monopotassium salt of cumene hydroperoxide 4oo1n9° methyl vinyl ether-maleic anhydride equimolar copolymer and 400 g of water using a high-speed stirrer. In addition, monopotassium salt of methyl vinyl ether-maleic anhydride equimolar copolymer 14,9. 400g water
An aqueous solution of was prepared separately.

Next, a separately prepared cumene hydroperoxide emulsion of 25Q1 was added through a metering pump with a plunger.
was introduced into the reactor at a rate of between 1.4 and 1.4 mm. One hour after the start of introduction of the cumene hydroperoxide emulsion, a separately prepared aqueous monopotassium solution of methyl vinyl ether-anhydroleic acid copolymer was introduced into the reaction system at a rate of 30 CC, 4 using a metering pump with a plunger.

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

Next, the obtained vinyl chloride resin emulsion was spray dried to remove the vinyl chloride resin. The air flow temperature of the dryer is 170°C at the inlet and outlet, respectively.

The temperature was 50°C. The obtained vinyl chloride resin was pulverized with a hammer mill and subjected to trial driving.

Example 2 5 ammonium persulfate was added to the redox polymerization catalyst emulsion used in Example 1, i.e., t-ascorbic acid, ethylenediaminetetraacetic acid sodium complex salt of ferrous ion, and cumene hydroperoxide emulsion A.
A vinyl chloride resin was prepared in the same manner as in Example 1, except that 0 omg was added at the start of the polymerization reaction.

Examples: 3, 4, Comparative Example 1 A vinyl chloride resin was prepared in the same manner as in Example 2, except that the amount of emulsifier was changed to the amount shown in the table.

Example 5.6 A vinyl chloride resin was prepared in the same manner as in Example 2, except that the emulsifier shown in the table was used.

Comparative Example 2 A vinyl chloride resin was prepared in the same manner as in Example 2, except that 30 g of sodium lauryl sulfate was used instead of monopotassium methyl vinyl ether-maleic anhydride copolymer.

Comparative Example 3 Vinyl chloride 3 to 9. Methyl vinyl ether-maleic anhydride equimolar copolymer monopotassium salt (30 g) dissolved in 5.51 g of water and dilauroylno! - When the same experiment as in Example 1 was conducted except that a finely suspended mixture of 45 g of oxide was reacted at 50°C for 16 hours, a large amount of lumps was generated and a stable vinyl chloride resin emulsion could not be obtained. There wasn't.

Comparative Examples 4 and 5 A vinyl chloride resin was prepared in the same manner as in Example 2, except that the emulsifier shown in the table was used.

Comparative Example 6 The amount of water initially added to the reactor was 41, and the amount of vinyl chloride monomer was 4.5! When a vinyl chloride resin was prepared in the same manner as in Example 1 except that Example 1 was changed, a large amount of lumps were generated and a stable vinyl chloride resin emulsion could not be obtained.

Next, 300 g of vinyl chloride resin powder obtained on each side (excluding Comparative Examples 2 and 6) and 18 g of diisooctyl phthalate were added.
0 g was mixed for 10 minutes using an Ishikawa-type rice sieve machine, and the resulting zolastisol was degassed under reduced pressure and then aged at 25° C. for 1 hour. Various properties of this zolastisol were measured as follows.

(1) Type B accuracy A Tokyo Keiki BM type viscometer (type 2 BM≠4) was used.

Low rotation speed: 6 rpm.

(2) Savers Viscosity Castor Movers Extrusion Viscometer Model A-10
0 used.

Nozzle: 500mm long, 1.56mm diameter.

Pressure crab 95 psi (3) Defoaming property Foam volume when Sol 209 was collected and defoamed under reduced pressure.

(4) Add 6 g of Ba/Zn stabilizer to the sol prepared in Section 2 of “Transparency”
10 at 190℃ with a thickness of 0.5wn.
The sheet was heated for 30 minutes and measured using an integrating sphere spectrophotometer.

(5) Water Resistance The same sheet used for measuring transparency was immersed in water at 23°C, and then the haze value was measured.

(6) After leaving the same sheet used for plume transparency measurement for one month, it was visually observed to see if powdery matter had formed on the surface.

These properties are shown in the table along with the mechanical stability and degassing properties of the latex.

As is clear from the table, the vinyl chloride resin obtained according to the present invention has good latex stability and degassing properties, and the plastisol obtained from this resin has better viscosity characteristics and defoaming properties than those of the comparative example. It has excellent transparency, water resistance, and bloom resistance.

Claims (1)

[Claims] When polymerizing vinyl chloride or a mixture of vinyl chloride and a vinyl compound copolymerizable with vinyl chloride in an aqueous medium under a water-soluble polymerization catalyst or under a redox polymerization catalyst consisting of a water-soluble reducing agent and an organic hydroperoxide, an emulsifier is used. The ratio of maleic acid copolymer salt to monomer is 0.05 to 1.
5% by weight, and the monomer/water weight ratio is 0.85.
A method for producing a vinyl chloride resin for paste, characterized by the following: