JPH03153712A - Fine suspension polymerization - Google Patents

Abstract

PURPOSE:To improve the storage stability by performing fine suspension polymerization in the presence of a specified high-molecular weight substance added in the production of a vinyl chloride polymer. CONSTITUTION:100 pts.wt. vinyl chloride or monomer mixture thereof with at most 30wt.% comonomer copolymerizable therewith (e.g. acrylonitrile), 0.01-2wt.% oil-soluble polymerization initiator (e.g. azobisisobutyronitrile), 0.1-3 pts.wt. emulsifier (e.g. ammonium salt of a higher alcohol sulfate) and 0.01-1 pt.wt. high-molecular weight substance soluble in vinyl chloride (e.g. partially saponified polyvinyl acetate) are added to water, and the obtained mixture is homogenized under high shearing force, subjected to fine suspension polymerization, and spray-dried to obtain a vinyl chloride polymer.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention provides a microsuspension polymerization method for obtaining a vinyl chloride polymer that can exhibit good storage stability (less viscosity change) when formed into a plastisol. Pertains to.

1 Jubei technology] Vinyl chloride polymers that can be used to form plastisols (for paste) are usually produced by emulsion polymerization using a water-soluble polymerization initiator, or by using a so-called oil-soluble polymerization initiator that dissolves in vinyl chloride monomers. It is produced by a fine suspension polymerization method in which vinyl chloride or a mixture copolymerizable with vinyl chloride is mechanically finely dispersed (homogenized) in an aqueous medium using a polymerization initiator and then polymerized. There is. Among these, vinyl chloride polymers produced by the latter micro-suspension polymerization method are often used in the field of molding, such as vinyl gloves, dolls, horizontal food molds, etc., because they have good melting and melting properties. .

However, although the vinyl chloride polymer produced by the fine suspension polymerization method has good meltability as mentioned above, when it is mixed with a plasticizer and made into plastisol, the sol Because of poor storage stability, the sol viscosity increases over time, leading to problems such as a decrease in handling properties and, furthermore, a failure to function as a sol.

This tendency is the same even when a solvent is used as a dispersion medium.

[Problems to be Solved by the Invention] The present inventor has conducted extensive studies on a method for producing a vinyl chloride polymer with good storage stability in the form of plastisol or organosol (hereinafter simply referred to as plastisol). However, during the production of vinyl chloride polymers, a compound that dissolves in vinyl chloride monomers and thickens the vinyl chloride monomers is added to perform fine suspension polymerization, thereby producing vinyl chloride polymers. The inventors have discovered that it is possible to obtain a polymer whose viscosity changes less over time without impairing properties such as the meltability of the polymer, and has thus arrived at the present invention.

That is, an object of the present invention is to provide a method for fine suspension polymerization of vinyl chloride monomers, which makes it possible to obtain a polymer that becomes a plastisol with good storage stability.

[Means for Solving the Problems 1] However, the gist of the present invention is that vinyl chloride containing an oil-soluble polymerization initiator or vinyl chloride and a comonomer copolymerizable therewith are prepared in an aqueous medium containing an emulsifier. A fine suspension polymerization method characterized in that a high molecular weight substance soluble in vinyl chloride is added to the polymerization system before homogenization treatment, and a fine suspension polymerization method for fine suspension polymerization of a mixture of The present invention relates to a method for seeding and polymerizing vinyl chloride using a vinyl chloride polymer obtained as a seed.

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

The il@ body used in the fine suspension polymerization method of the present invention is vinyl chloride or a copolymerizable copolymerizable with vinyl chloride and vinyl chloride.
It is a mixture with mer. ) For example,
Unsaturated nitriles such as acrylonitrile, methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, acrylic acid 2
- Esters of acrylic acid and methacrylic acid such as hydroxypropyl, 2-hydroxypropyl methacrylate, itaconate esters such as methyl itaconate, methyl itaconate, diisopropyl itafluorate, nooctyl itafluorate, vinyl such as vinyl acetate esters,
Vinylidene chloride, aromatic vinyl compounds, etc. may be used, and one or more of these comonomers may be used.The content of these comonomers is 30% by weight of the vinyl chloride polymer.
Below, it is particularly desirable that the content be in the range of 10% by weight or less.

The oil-soluble polymerization initiator is soluble in monomers such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, lauroyl peroxide, t-butyl peroxyvivalate, that is, it is oil-soluble. It is necessary. In addition, these polymerization initiators include sodium sulfite,
A redox polymerization initiator may be used in combination with a reducing agent such as ammonium sulfite, sodium hydrogen sulfite, ascorbic acid, or sodium formaldehyde sulfoxylate.Of course, the polymerization initiator is limited to those mentioned above as long as it is oil-soluble. The amount of oil-soluble polymerization initiator used is
Depending on the content of active oxygen, 0.01 to 2 of the monomer
% by weight, preferably in the range of 0.03% to 1% by weight.

When producing a vinyl chloride polymer in which the polymerization initiator remains, which will be used as a seed for the seeding polymerization described later, it is generally 0.
It is sufficient to set it within the range of 5% to 1%.

The emulsifier used in the polymerization is one of the known emulsifiers, such as higher alcohol sulfate alkali metal salts (ammonium salts), alkylbenzenesulfonic acid alkali metal salts (ammonium salts), and higher fatty acid alkali metal salts (ammonium salts). , or a combination of two or more types.

The amount of emulsifier used is 0.1 to 3 per 100 parts by weight of monomer.
A range of parts by weight, preferably 0.3^-1 parts by weight, is suitable.

Symptom #I During cloudy polymerization, the high molecular weight substance added to the polymerization system is not particularly limited as long as it is soluble in vinyl chloride.The high molecular weight substance is generally dissolved in vinyl chloride and its viscosity increases. It has the property of increasing 14: Physically, for example, partially saponified polyvinyl acetate, polyacrylic acid ester, polymers such as polyesters called polymer plasticizers, higher alcohols having 12 or more carbon atoms, and higher fatty acids having 15 or more carbon atoms. Examples include high molecular weight substances such as high molecular compounds, and at least one of these is used. In particular, partially saponified polyvinyl acetate is preferred, and the amount of the high molecular weight substance used is 0.01 to 1 part by weight, preferably 0.02 to 0.1 part by weight, per 100 parts by weight of the monomer.
A range of 3 parts by weight is common. If the amount used is less than this range, it is difficult to expect a sufficient effect, whereas if it is used in a large amount beyond this range, no increase in the effect will be observed, and on the contrary, the effect on the reaction such as the occurrence of abnormal reactions, etc. There is a concern that the surface of the vinyl chloride polymer may be blown out (bleed, plume, etc.).

To carry out the fine suspension polymerization method of the present invention, a high molecular weight substance, that is, a substance that acts to thicken vinyl chloride, is added to the polymerization system at any time before the start of the homogenization process. , at or before the time of charging vinyl chloride, ■ At the same time or before or after the addition of emulsifiers, polymerization initiators, and other polymerization aids, ■ Dissolved in advance in a solvent to be mixed with vinyl chloride, or ■There are methods such as dissolving vinyl chloride itself and charging it, but in any case, it is sufficient that the addition is completed before homogenization treatment using high-speed shearing force.After that, fine suspension polymerization itself This is carried out using known methods. The fine suspension polymerization latex thus produced is directly spray-dried to separate the vinyl chloride polymer.

In addition, a latex of a vinyl chloride polymer produced so that an oil-soluble polymerization initiator remains in the polymer particles is prepared by adding vinyl chloride or vinyl chloride to the polymer in an aqueous medium containing an emulsifier as a seed polymer. It can be added to a mixture with a copolymerizable comonomer to carry out a second stage polymerization reaction, so-called seeding polymerization. The seeded polymerization may be a normal emulsion polymerization method.

As the emulsifier, the one employed in the -th stage polymerization reaction can be used as is. The vinyl chloride polymer is separated from the latex after the two-stage polymerization by a method such as spray drying. This polymer also exhibits the same effect of improving storage stability as the vinyl chloride polymer produced by the above-mentioned fine suspension polymerization method.

The reason why the storage stability of the vinyl chloride polymer produced by the fine suspension polymerization method of the present invention is improved is not necessarily clear, but it is clear that the high molecular weight substance soluble in vinyl chloride is When homogenizing by increasing the viscosity of the polymer and applying high-speed shearing force, the droplet size of vinyl chloride becomes larger than that during conventional homogenization, and as a result, the average large particle size of the polymer also increases. (This is thought to be due to a decrease in the total surface area of the particles and a decrease in the contact area of the polymer with the plasticizer when mixed with a plasticizer.Also, among the high molecular weight substances that have a thickening effect, partially saponified polyacetic acid The reason why vinyl is particularly preferable is presumed to be that it does not have a polymerization inhibiting effect, has good compatibility with the vinyl chloride polymer to be produced, and does not cause problems such as bleeding.

When preparing plastisol from the vinyl chloride resin produced by the method of the present invention, plasticizers, stabilizers, antioxidants, ultraviolet absorbers, fillers, antistatic agents, colorants, mold release agents, etc. are usually used in the preparation of plastisol. homogeneously mixed with the additives used.

As a plasticizer, for example, 7tal@:) n-butyl, 7
Talling di-n-octyl, 2-ethylhexyl heptatalate (DOP), diisooctyl heptatalate, noisononyl heptatalate, diisodecyl heptalate, octyldecyl heptalate, butylbenzyl heptalate, di-2 isophthalate - Heptatal acid plasticizers such as ethylhexyl or heptatal acid esters of higher alcohols having about 11 to 13 carbon atoms, di-n-octyl-n-decyl trinoliftate, tri-2-ethylhexyl trimellitate, trimellitic acid Trinolift R plasticizers such as triisodecyl, tri-octyl trinolitate, 7-dipic acid, 2-ethyl hequinyl, 7-dipine 111! Fatty acid ester plasticizers such as no-1-decyl, diisodecyl adipate, di-2-ethylhexyl azelaate, diptyl sebacate, di-2-ethylhexyl sebacate, tributyl phosphate, tri-2-ethylhexyl phosphate, and 2-ethyl phosphate. Examples include phosphate ester plasticizers such as ethylhexyldiphenyl and tricrenol phosphate, epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, epoxidized tall oil fatty acid-2-ethylhexyl, and liquid epoxy resin. These can be used alone or in combination of two or more. The amount used is 100 weight 31g of vinyl chloride resin.
A range of 30.200 parts by weight is preferred.

The stabilizer is known as a stabilizer for vinyl chloride polymers.
Lead-based, barium-zinc-based, calcium-zinc-based, magnesium-zinc-based, calcium-barium-based, cadmium-barium-based, barium-zinc-tin-based, cadmium-
Barium-zinc based, organotin based, and other stabilizers can be used.

The amount of these stabilizers to be used is 0.1 to 5 parts by weight, preferably 0.15·\23 parts by weight, per 100 parts by weight of the vinyl chloride polymer. If the content is too low, thermal stability will be insufficient, and even if more than the appropriate amount is used,
It is not economical because the effect cannot be increased commensurate with the amount added.

[Effects of the Invention] The method of the present invention simply adds a high molecular weight substance to vinyl chloride before homogenization, and the particle size of the vinyl chloride polymer produced by the conventional fine suspension polymerization method is far greater than that of the vinyl chloride polymer. This polymer or the vinyl chloride polymer obtained by two-stage polymerization using this polymer as a seed has a small change in viscosity over time in a plastisol or organosol state, and can be stored easily. It has extremely good stability and meltability, and has physical properties equivalent to r-copolymers obtained by conventional fine suspension polymerization.

[Example 1] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by the following Examples unless the gist thereof is exceeded.

Note that "part J" and "% J" described in the examples are based on weight.

Furthermore, the evaluation of the vinyl chloride polymer is as follows.

■ The plastisol obtained by mixing and solizing 100 parts of Lennon and 60 parts of DOP to be evaluated for viscosity stability in a Hobart mixer was mixed with B8H type viscosity liver (Brookfield V manufactured by Tokyo Keiki Co., Ltd.).
The viscosity is measured at 50 rpm using an iscometer (designated as Elso (init)).

This sol was stored in a constant temperature chamber at 40°C, and the viscosity was measured again in the same manner after 3 days (referred to as B6.(3D)).
it)) is used as an index of viscosity stability as AI (^giB Index).

■ 100 parts of renon, 60 parts of DOP, stabilizer (Ca
-3 parts of Zn) were stirred and mixed in a Chemi-Starte, and the resulting sol was degassed and aged in vacuum, then put in a predetermined amount into a glass tube with a diameter of 20 rings, and this was placed in an oil bath at 100°C. While heating, the viscosity is measured using a B8R type viscometer (using #7 spindle) manufactured by Tokyo Keiki Co., Ltd. The viscosity and heating time are graphed, and the time when the viscosity reaches 1*600 poise is defined as the del temperature, which is a measure of the deltability.

-Large particle size The average particle size of the vinyl chloride polymer produced in the latex state was determined using a Shimadzu Corporation %V particle size distribution measuring device! fs
Measurement was performed using A-CP3.

Example 1 In a pre-mixing tank with a volume of 20,012 and equipped with an agitator, 150 ml of lauroyl peroxide (LOP) was added to 80 ml of deionized water.
0 g, sodium lauryl sulfate 400 g, lauryl alcohol 200 g, and partially saponified polyvinyl acetate soluble in vinyl chloride monomer (Gosefheimer L7514 manufactured by Nippon Gosei Kagaku Co., Ltd., degree of polymerization 650, degree of saponification 30%) 12
Then, the preliminarily mixed tank was degassed, 60 kg of vinyl chloride monomer was added, and the temperature was maintained at 35° C. with stirring.

After stirring uniformly, a container 2 equipped with a stirrer was degassed in advance using an emulsifier (homogenizer) while separating the microorganisms.
0 (I Transferred to I2 reaction tank.

After the transfer of the dispersion liquid was completed, the temperature of the reaction tank was raised to 55''C, and polymerization was carried out by a known method.The average particle size of the polymer particles in the obtained latex was 1.8μ.

The latex obtained by the polymerization reaction was filtered through a 20-mesh wire mesh, and after adding 0.5 pbr of a nonionic surfactant for 7g and 4g, a small spray-dried 1% (Ni
It was dried using a PRODUCTION-M 1nor type (manufactured by RO Corporation). This dried renon was further processed in a hammer mill to obtain a vinyl chloride polymer. This polymer was used as a renon to be evaluated.

Example 2 Polymerization degree 5 (1 (1), saponification degree 25
% partially saponified polyvinyl acetate was used and azobis-2,4-trimethylvaleronitrile was used as the initiator, but the same procedure as in Example 1 was carried out. l! A turbid polymerization reaction was carried out. The average particle size of the vinyl chloride polymer in the latex was 2.1 microns.

Example 3 A fine-molecular suspension polymerization reaction was carried out in the same manner as in Example 1 above, except that 120 g of ste7lyl alcohol was used as the high molecular weight substance. The average particle size of the vinyl chloride polymer in the latex was 1.4 microns.

Comparative Example 1 1 except that partially saponified polyvinyl acetate was not added.
1. A polymerization reaction was carried out in the same manner as in Example 1. The average particle size of the vinyl chloride polymer in the latex was 0.7μ.

Comparative Example 2 Similar to Comparative Example 1, a fine suspension polymerization reaction was carried out in the same manner as in Example 2, except that the high molecular weight substance in Example 2 was not used. The average particle size of polyvinyl chloride in the produced latex was 0.8 microns.

Example 4 100 kg of ion-exchanged water, 600 g of lauroyl peroxide,
Partially saponified polyvinyl acetate soluble in 400 g of sodium lauryl sulfate, 200 g of lauryl alcohol, and vinyl chloride monomer (Gosefaimer L manufactured by Nippon Gosei Kagaku Co., Ltd.)
7514, degree of polymerization 650, degree of saponification 30%) was added, and then preliminary; the polymerization tank was degassed and vinyl chloride monomer 60% was added.
kg was added and maintained at 35° C. with stirring. After stirring uniformly, use an emulsifier (homogenizer) to disperse into fine droplets.
After the transfer of the 9 dispersion liquid to the 0 t reaction tank was completed, the temperature of the reaction tank was raised and polymerization was carried out by a known method. The average particle size of the seed polymer particles in the obtained latex was 2.0 μm, and the solid content concentration was 19%.

The second stage polymerization was carried out as follows using the seed polymer prepared as described above.

80 g of deionized water was added to a 200 Q polymerization tank equipped with a stirrer.
kg, N child claw combined latex 5 kg (solid content equivalent),
After charging 200 g of 0.05% cupric chloride aqueous solution and 20 g of sodium hydrogen carbonate, deaeration was performed to obtain 20 g of vinyl chloride monomer.
After the temperature was raised to 50° C., a 0.5% aqueous solution of sodium pyrosulfite, which had been dissolved in advance, was continuously added little by little to the polymerization tank to initiate polymerization. After starting addition of the sodium pyrosulfite aqueous solution, the amount added was adjusted so that the reaction occurred at a constant reaction rate.

When polymerization started and the reaction rate was about 7-8%, a total of 14
Addition of a vinyl chloride monoelectric material at a rate of 8 kg/br was started. Furthermore, from when the polymerization rate reached 10% until the end of polymerization, an approximately 8% aqueous solution (total of 5 g) of dodecylbenzene and sodium sulfonate, which had been prepared separately as an emulsifier, was continuously added at a ratio of If/I + r. added. When the pressure in the polymerization tank dropped from the saturation pressure of vinyl chloride at 50'C to 1.5 by 117 cm2, the polymerization was stopped and unreacted monomers were recovered. The average particle size of the vinyl chloride polymer in the latex was 2.9μ, and the stability of the latex was good. Moreover, the reaction yield was 80%.

Comparative Example 3 A polymerization reaction was attempted in the same manner as in Example 4 except that the seed polymer was prepared without adding a high molecular weight substance. The average particle size of the 0-seed polymer was 0.7μ, The average particle size of the latex obtained by seed polymerization using this was 1.2μ.

The vinyl chloride polymers obtained from the above-mentioned Examples and Comparative Examples were evaluated, and the results are summarized in Table 1.

As seen in these Examples and Comparative Examples, the vinyl chloride polymer produced by the method of the present invention by adding a high molecular weight substance soluble in vinyl chloride monomer during fine dispersion has a The storage stability in the plastisol state can be improved without impairing the plasticity.

Claims (2)

[Claims] (1) In a method of fine suspension polymerization of vinyl chloride containing an oil-soluble polymerization initiator or a mixture of vinyl chloride and a comonomer copolymerizable therewith in an aqueous medium containing an emulsifier, the A fine suspension polymerization method characterized by adding a high molecular weight substance that dissolves in vinyl chloride to the polymerization system. (2) When performing fine suspension polymerization of vinyl chloride containing an oil-soluble polymerization initiator or a mixture copolymerizable with vinyl chloride in an aqueous medium containing an emulsifier, the vinyl chloride is A vinyl chloride polymer produced by adding a soluble high molecular weight substance and in which the oil-soluble polymerization initiator remains is used as a seed, and can be copolymerized with vinyl chloride or vinyl chloride in an aqueous medium containing an emulsifier. A method for polymerizing vinyl chloride, which comprises polymerizing a mixture with a comonomer.