JPH11279211A - Production of vinyl chloride-based polymer latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy method by which a stable vinyl chloride-based polymer latex having small amount of aggregate is obtained in a micro suspension polymerization and a seeded micro suspension polymerization. SOLUTION: This method for producing a vinyl chloride-based polymer latex by a micro suspension polymerization or a seeded micro suspension polymerization of vinyl chloride or a mixture of the vinyl chloride with an unsaturated monomer copolymerizable therewith is characterized by adding 50-1,000 wt.ppm naphthenic hydrocarbon or an aromatic hydrocarbon based on the amount of the charged monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride polymer latex, and more particularly, to a method for producing a vinyl chloride polymer latex capable of obtaining a stable latex having a small amount of aggregates.

[0002]

2. Description of the Related Art In order to obtain a latex for processing latex or a resin for processing paste, fine suspension polymerization or seeding fine suspension polymerization of a vinyl chloride monomer is performed. In fine suspension polymerization, water is used as a dispersion medium, and monomer, anionic or /
And a method of emulsifying with a homogenizer or the like together with an emulsifier of a nonionic surfactant, an oil-soluble polymerization initiator and the like, and dispersing the monomer into fine droplets for polymerization. The polymerization reaction product has a primary particle diameter continuously spread to 0.1 to 5.0 μm, and spherical polymer particles having a mountain-shaped particle size distribution having a peak at a position of about 1.2 μm are dispersed in an aqueous medium. Latex which is dispersed in Seeding fine suspension polymerization is a method in which a latex polymer obtained by fine suspension polymerization is used as a seed to coat and polymerize a monomer. In seeded fine suspension polymerization,
In the process of microsuspension polymerization when the seed polymer is formed, excess polymer adsorbed on the polymer by polymerizing in the presence of an excess of polymerization initiator in excess of the amount required for polymerization of various polymers In many cases, coating polymerization of a monomer is performed with a polymerization initiator.
However, in order to increase the reaction rate of the coating polymerization, it is often performed to add a solution of an oil-soluble polymerization initiator before the start of the seeding fine suspension polymerization or during the reaction. The reaction product of the seeded fine suspension polymerization is such that spherical polymer particles having a primary particle size in a range of 0.1 to 10 μm and a particle size distribution with a mode particle size around 1.3 μm are water. Latex dispersed in a medium. However, the vinyl chloride-based polymer latex obtained by the fine suspension polymerization and the seeded fine suspension polymerization cannot be said to be a truly stable latex, and aggregates (coagulum) generated during the polymerization reaction are mixed. If agglomerates are mixed in the latex, operation troubles due to clogging of transfer pipes, decrease in yield, increase in maintenance burden on filter, increase in labor and cost of manufacturing latex such as disposal of aggregates by filtration Not only in terms of quality, but also in terms of quality, small agglomerated particles that have passed through the filter cause problems such as streaking and granular projections on the surface of the processed product during latex coating or paste coating. For this reason, there has been a demand for the development of a fine suspension polymerization method and a seeded fine suspension polymerization method capable of obtaining a stable vinyl chloride-based polymer latex with less generation of aggregates.

[0003]

SUMMARY OF THE INVENTION Under the above circumstances, the present invention aims to provide a stable vinyl chloride system which is free from agglomerates in fine suspension polymerization and seeded fine suspension polymerization by a simple method. The purpose of the present invention is to provide a method for obtaining a polymer latex.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the stability of the vinyl chloride polymer latex differs depending on the type of the solvent of the oil-soluble polymerization initiator. With particular attention to this, the present invention has been completed. Thus, according to the present invention, in producing a vinyl chloride polymer latex by fine suspension polymerization or seeding fine suspension polymerization of vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith, Naphthenic hydrocarbon or aromatic hydrocarbon is charged per monomer 50 to 50
There is provided a method for producing a vinyl chloride polymer latex, characterized by adding 1000 ppm by weight.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The process of the present invention is applied to the polymerization of vinyl chloride and the copolymerization of vinyl chloride and an unsaturated monomer copolymerizable therewith. Is preferably at least 50% by weight.
It is more preferable that the content be not less than% by weight. In the method of the present invention, examples of the ethylenically unsaturated monomer copolymerizable with vinyl chloride include olefinic compounds such as ethylene and propylene; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid and methacrylic acid; Unsaturated monocarboxylic acids; methyl acrylate, ethyl acrylate,
Unsaturated monocarboxylic acid esters such as n-butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, and N, N-dimethylaminoethyl methacrylate; and unsaturated monocarboxylic acid esters such as acrylamide and methacrylamide Amides; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid; esters and anhydrides thereof; N-substituted maleimides; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether ;
Further, vinylidene compounds such as vinylidene chloride can be exemplified.

[0006] The emulsifier used in the method of the present invention includes:
For example, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfates such as sodium lauryl sulfate and sodium tetradecyl sulfate;
Sulfosuccinates such as sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate; fatty acid salts such as sodium laurate and potassium potassium semi-hardened tallow; ethoxy such as sodium salt of polyoxyethylene lauryl ether sulfate and sodium salt of polyoxyethylene nonylphenyl ether sulfate Sulfate salt; alkane sulfonate; alkyl ether phosphate sodium salt; and nonionic surfactants such as polyoxyethylene nonyl phenyl ether and polyoxyethylene sorbitan lauryl ester. The emulsifier may be added only at the initial stage, or may be additionally added in accordance with the progress of polymerization in order to enlarge the particle size.The amount used is 0.1 to 100 parts by weight of the monomer. 5
Part by weight is preferred, and 0.1 to 3 parts by weight is more preferred.

Examples of the oil-soluble polymerization initiator include diacyl peroxides such as acetyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide. Benzoyl hydroperoxide, cumene hydroperoxide, p
Hydroperoxides such as cymene hydroperoxide, diisopropylbenzene hydroperoxide and p-menthane hydroperoxide; peroxyesters such as t-butylperoxypivalate; diisopropylperoxydicarbonate, diethylhexylperoxydicarbonate and the like Peroxydicarbonate; organic peroxides such as sulfonyl peroxides such as acetylcyclohexylsulfonyl peroxide; redox polymerization initiators obtained by combining these organic peroxides with reducing agents such as Rongalite; 2,2′- Azobisisobutyronitrile, 2,
2'-azobis (2-methylbutyronitrile), 2,
2'-azobis (2,4-dimethylvaleronitrile),
Azo compounds such as 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) can be mentioned. The amount used is from 0.01 to 0.1 per 100 parts by weight of the monomer.
3 parts by weight. However, when it is polymerized as a seed for seeding fine suspension polymerization, it also contains an initiator for coating polymerization.
1 to 2.0 parts by weight may be used.

In the present invention, at least one of a naphthenic hydrocarbon and an aromatic hydrocarbon is used as a polymerization additive. Examples of the naphthenic hydrocarbon include cyclopentane, cyclohexane, cyclooctane, cyclodecane and the like, and cyclohexane is preferred. Examples of the aromatic hydrocarbon include benzene, toluene, xylene, cumene and the like, with toluene being preferred. The method of adding the naphthenic hydrocarbon or the aromatic hydrocarbon is not limited, but it is preferable to use it as a solvent or a dispersion medium for the oil-soluble polymerization initiator. Conventionally, petroleum aliphatic hydrocarbons having 8 to 18 carbon atoms and plasticizers for vinyl chloride resins have been used as solvents or dispersion media for oil-soluble polymerization initiators. However, when these conventional organic liquids are used as a solvent or a dispersion medium of the polymerization initiator of the fine suspension polymerization of the vinyl chloride monomer or the seeded fine suspension polymerization, the use of the organic liquid according to the present invention is reduced. Aggregation of the primary particles of the polymer is likely to occur in the course of the polymerization reaction, and aggregation (coagulum) is often generated. Therefore, it is recommended to use the naphthenic hydrocarbon or the aromatic hydrocarbon according to the present invention as a solvent or a dispersion medium instead of these solvents. In that case, the concentration is preferably 30 to 400% by weight, more preferably 50 to 400% by weight.
200% by weight. The amount of the naphthenic hydrocarbon or aromatic hydrocarbon to be used with respect to the monomer is required to be 50 to 1000 ppm by weight, preferably 100 to 500 ppm.
Ppm by weight. When the amount is less than 50 ppm by weight, the effect of reducing aggregates is not exhibited. When the amount is more than 1000 ppm, the amount volatilized in the air after the polymerization reaction is increased, and environmental pollution and
This causes problems such as deterioration of the color tone of the molded product. The storage of the polymerization initiator solution or dispersion suppresses decomposition, so that it is -30 to -10.
Perform at a temperature of ° C.

The naphthenic hydrocarbon or the aromatic hydrocarbon may be simply charged into the polymerization vessel separately from the oil-soluble polymerization initiator.

In the fine suspension polymerization, first, water, vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith, a solution of a naphthenic hydrocarbon or an aromatic hydrocarbon as an oil-soluble polymerization initiator. Additives such as emulsifiers and, if necessary, emulsifying aids such as higher alcohols are added and preliminarily mixed, and homogenized by a homogenizer to adjust the particle size of oil droplets. As the homogenizer, for example, a colloid mill, a vibration stirrer, a two-stage high-pressure pump, or the like can be used. The homogenized solution is sent to a polymerization vessel, and the temperature inside the polymerization vessel is raised to a predetermined reaction temperature by heating the jacket while gently stirring to start a polymerization reaction, and thereafter, a predetermined conversion, usually 85 to 95%, is achieved. The polymerization is carried out until reaching. The polymerization temperature is usually 30 to 80C. The solid concentration of the obtained polymer latex is preferably 30 to 65% by weight.

In the seeded fine suspension polymerization, water is added to a polymerization vessel, a polymer latex obtained by the fine suspension polymerization containing a seed polymer, and an oil-soluble polymerization initiator remaining in the seed polymer is insufficient if the polymerization is insufficient. A polymerization initiator, such as a naphthenic hydrocarbon or aromatic hydrocarbon solution, is charged and deaerated in the polymerization vessel or, if necessary, replaced with an inert gas such as nitrogen, to thereby prepare an emulsifier and vinyl chloride or vinyl chloride or vinyl chloride. And a mixture of monomers that can be copolymerized, and the temperature in the polymerization vessel is increased by heating the jacket while gently stirring to initiate polymerization. The polymerization temperature is usually 30 to 80C. Examples of the emulsifier include those similar to the emulsifier used in the emulsion polymerization. In the case of seeded fine suspension polymerization, it is not necessary to newly add a polymerization initiator. The solid concentration of the obtained polymer latex is preferably 30 to 65% by weight.

The polymerization vessel used in the method of the present invention is not particularly limited, and the capacity is suitably from 10 to 100 m ³ . The jacket can be a conventional type of jacket or Japanese Patent Publication 3-42.
No. 49, an internal jacket system with an improved heat transfer coefficient may be used. In order to shorten the reaction time, a reflux condenser may be provided to increase the heat removal ability. In the method of the present invention, known additives such as a chain transfer agent, a crosslinking agent, and a scale inhibitor can be appropriately used depending on polymerization conditions.

Next, embodiments of the present invention will be described. (1) When producing vinyl chloride polymer latex by subjecting vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith to fine suspension polymerization or seeding fine suspension polymerization, naphthenic hydrocarbons Alternatively, a process for producing a vinyl chloride polymer latex, comprising adding an aromatic hydrocarbon in an amount of 50 to 1000 ppm by weight per charged monomer. (2) The method for producing a vinyl chloride polymer latex according to the above (1), wherein a naphthenic hydrocarbon or an aromatic hydrocarbon is used in an amount of 100 to 500 ppm by weight per charged monomer. (3) The above (1) wherein a naphthenic hydrocarbon or an aromatic hydrocarbon is used as a solvent or a dispersion medium for the polymerization initiator.
Or the method for producing a vinyl chloride polymer latex according to (2). (4) The method for producing a vinyl chloride polymer latex according to the above (1) to (3), wherein the naphthenic hydrocarbon is cyclohexane. (5) The above (1) to wherein the aromatic hydrocarbon is toluene.
(4) The method for producing a vinyl chloride polymer latex according to (4).

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Unless indicated otherwise, parts and percentages are by weight. In Examples and Comparative Examples, evaluation of the vinyl chloride polymer latex was performed by the following method. (1) Central Particle Size The cumulative particle size distribution is measured using a laser scattering particle size distribution measuring device [Mastersizer MS-20, manufactured by Malvern Co., Ltd.], and the particle size is determined as the particle size corresponding to a cumulative value of 50% by weight. (2) Aggregate amount The obtained latex was filtered through a 60-mesh wire mesh,
Agglomerates on the wire net were obtained, and deposits on the inner wall of the polymerization vessel were scraped off, and the weight after drying was measured. (3) Sol viscosity A vinyl chloride polymer latex produced through a polymerization reaction is filtered through a 60-mesh wire gauze and then spray-dried to obtain 100 parts by weight of a resin powder and 60 parts by weight of a plasticizer di-2-ethylhexyl phthalate. Of the sol in a constant temperature and humidity room at a temperature of 25 ° C. and a relative humidity of 55% to prepare a plastisol, and after standing for 4 hours, measure the viscosity of the sol with a Brookfield viscometer [Tokimec Co., Ltd. ), BL type],
Measure at 6 rpm using rotor 4.

EXAMPLE 1 30 kg of deionized water and a higher alcohol having 12 to 18 carbon atoms were placed in a pressure-resistant reactor having an inner volume of 100 liters and equipped with a stirrer.
5 gr, a 70% toluene solution of di-2-ethylhexyl peroxydicarbonate as a polymerization initiator 13
Gr (toluene 4 gr) was charged and degassed, and then sodium laurin sulfate 350 gr and vinyl chloride monomer 35 K
g was stirred for 30 minutes, and then homogenized with a two-stage pressurized high-pressure pump. Next, this dispersion is degassed to an internal volume of 10%.
Transfer to 0 liter glass lining polymerization tank, 49 ℃
And the polymerization was carried out at this temperature. After about 14.0 hours, the polymerization was terminated at a polymerization conversion of 85% at a pressure of 1.0 kg / cm ² , and the unreacted monomers were recovered and the contents were taken out. Table 1 shows the results.

Example 2 The procedure of Example 1 was repeated except that a cyclohexane solution having the same concentration was used instead of the toluene solution as the polymerization initiator.
The results are shown in Table 1. Example 3 Example 1 was repeated except that instead of a toluene solution of di-2-ethylhexylperoxydicarbonate as a polymerization initiator, 17.6 g of lauroyl peroxide was separately added together with 30 g of cyclohexane, and polymerization was carried out at 52 ° C. The same was done. The results are shown in Table 1.

Example 4 30 kg of deionized water, 175 gr of sodium dodecylbenzenesulfonate and 385 higher alcohols having 12 to 18 carbon atoms were placed in a pressure-resistant reactor having an internal volume of 100 liters and equipped with a stirrer.
gr, lauroyl peroxide 29 as a polymerization initiator
After stirring 0 g with 35 kg of vinyl chloride for 30 minutes, the liquid homogenized by a two-stage pressurized high-pressure pump was transferred to the same polymerization tank as in Example 1 and polymerized at 48 ° C. The polymerization was terminated at a polymerization conversion of 85%, and a latex containing 27% of polymer particles having a center particle diameter of 0.55 μm was obtained. 10 kg of the obtained latex was charged into the same polymerization tank as in Example 1 and then 30 kg of deionized water, and a 3,5,5-trimethylhexinoyl peroxide 70% strength toluene solution 15
g, and slowly stirred for 30 minutes, and further added 200 g of sodium dodecylbenzenesulfonate,
After degassing, 36 kg of vinyl chloride was charged, and the content was heated at 62 ° C. to perform seeded fine suspension polymerization. The reaction was completed at a polymerization rate of 87%. The results are shown in Table 1.

Comparative Example 1 Shellsol 71 [Shell Chemical Co., Ltd.] was used instead of toluene.
And petroleum aliphatic hydrocarbons] as the solvent for the polymerization initiator. The results are shown in Table 1. Comparative Example 2 The procedure of Example 1 was repeated except that the polymerization initiator was dissolved in 4 g of di-2-ethylhexyl phthalate (DOP) instead of 4 g of toluene. The results are shown in Table 1.

Comparative Example 3 The procedure of Example 1 was repeated except that 6.2 g of a 72.6% toluene solution of di-2-ethylhexyl dicarbonate was used as a polymerization initiator. Table 1 shows the results. Comparative Example 4 6.2 gr of a cyclohexane solution having a concentration of 72.6% of di-2-ethylhexyl dicarbonate was used as a polymerization initiator.
Was carried out in the same manner as in Example 1 except that Table 1 shows the results.

[0020]

[Table 1]

From the comparison between Examples 1 to 3 and Comparative Examples 1 and 2, the use of aromatic hydrocarbons and naphthenic hydrocarbons as the solvent for the oil-soluble polymerization initiator is more effective than the use of aliphatic hydrocarbons and plasticizers. It can be seen that the amount of aggregate formed is small. Example 4 also shows that the effect of suppressing the aggregates is the same even when the aromatic hydrocarbon is simply used, not as a solvent for the polymerization initiator. Example 4 also confirmed the effects of the present invention in seeded fine suspension polymerization.

[0022]

According to the method of the present invention, there is provided a simple method for obtaining a stable vinyl chloride polymer latex with less generation of aggregates in fine suspension polymerization and seeded fine suspension polymerization.

Claims (1)

[Claims] 1. A method for producing a vinyl chloride-based polymer latex by subjecting vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith to fine suspension polymerization or seeding fine suspension polymerization to produce a naphthene-based polymer latex. 50 to 1000 weight p per monomer charged with hydrocarbon or aromatic hydrocarbon
A method for producing a vinyl chloride polymer latex, which comprises adding pm.