JPH11279208A - Production of vinyl chloride-based polymer latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for uniformly charging a subsidiary raw material into a polymer system, capable of providing stable latex property and polymer quality and excellent in productivity. SOLUTION: This method for producing a vinyl chloride-based polymer latex comprises adding an oil-soluble subsidiary raw material from piping connecting to a monomer charging piping, adding a water-soluble subsidiary material from a water charging piping and preliminarily mixing the subsidiary raw material with a monomer or/and water in the monomer and/or water-charging piping from a connecting part to a polymerizer and charging the mixture, when vinyl chloride or a mixture of vinyl chloride with an unsaturated monomer capable of copolymerizing with vinyl chloride is charged into the polymerizer together with a subsidiary raw material necessary for polymerization reaction and subjected to emulsion polymerization or fine suspension polymerization in water medium to produce vinyl chloride-based polymer latex.

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 having excellent productivity.
The present invention relates to a method for producing a vinyl chloride polymer latex having stable properties and quality.

[0002]

2. Description of the Related Art Emulsion polymerization (including seeded emulsion polymerization) and fine suspension polymerization (including seeded fine suspension polymerization) of vinyl chloride are carried out to obtain latex for latex processing and resin for paste processing. Will be Emulsion polymerization uses water as a dispersion medium, an anionic or nonionic surfactant emulsifier, a water-soluble polymerization initiator, and the like, while performing relatively slow stirring in a pressure-resistant polymerization vessel with a cooling jacket, while using an emulsifier. By the action, the vinyl chloride monomer is emulsified into fine droplets, and the polymerization proceeds in the surfactant micelle layer surrounding the monomer, and the particle size is reduced to 0.1.
It is intended to obtain a latex of microspherical polymer particles having a particle size distribution having a sharp peak in the range of 0.5 to 0.5 μm. In order to obtain a latex of particles having a larger particle size than the emulsion polymerization method, the emulsion-polymerized latex is used as a seed, and the amount of the emulsifier is 20 to 60% of the theoretical amount required to cover the entire surface area of the polymer particles. Seed emulsion polymerization in which coating polymerization for thickening only seed particles while preventing the generation of new microparticles is carried out by keeping the polymerization at a low temperature. In this case, the particle size distribution usually has a sharp main peak in the range of 0.9 to 1.5 μm enlarged by coating polymerization and a sharp secondary peak in the range of 0.1 to 0.3 μm by-produced. Is formed. As another method for obtaining a latex or paste resin, water is used as a dispersion medium, and a mixture of a monomer, a surfactant, and an oil-soluble polymerization initiator is dispersed into fine droplets using a homogenizer or the like. Fine suspension polymerization, which is followed by polymerization, and seeded fine suspension polymerization, in which a suspension of the polymer obtained by the fine suspension polymerization is used as seed particles to further carry out coating polymerization, are also performed. The particle size distribution of latex particles by fine suspension polymerization is 0.1 ~
It spreads continuously to 5.0 μm, and has a mountain-shaped distribution with the vertex at a position of about 1.2 μm. Latex particles by seeding microsuspension polymerization spread continuously from 0.1 to 10 μm,
A particle size distribution having a mode particle size at a position of about 1.3 μm is taken.

[0003] Conventionally, the vinyl chloride polymer latex obtained by the above emulsion polymerization or fine suspension polymerization cannot be said to be a truly stable latex. Aggregates (coagulum) were usually mixed. If aggregates are mixed in latex, operation troubles due to clogging of transfer piping, lowering of yield,
Not only does the burden of maintenance of the filtration filter increase, the problem of latex production such as the disposal of agglomerates separated by filtration and the cost increase occur, but also in terms of quality, small agglomerated particles that have passed through the filtration filter become latex coating and paste. During the coating process, there was a problem that streaks and granular projections were generated on the surface of the processed product. Vinyl chloride polymers are
In order to have mechanical strength suitable for the use of the molded product,
Also, in order to have melting characteristics that match the processing conditions,
An appropriate degree of polymerization is set. Therefore, a chain transfer agent is added during the polymerization reaction to lower the degree of polymerization of the polymer, or a crosslinking agent is added to increase the degree of polymerization.

However, since these oil-soluble or water-soluble secondary materials such as an emulsifier, a polymerization initiator, a chain transfer agent and a cross-linking agent are added together, the polymerization initiator, the chain transfer agent, A small amount of a cross-linking agent or the like was unevenly distributed in the polymerization vessel, and the effect of each auxiliary material was not uniform among the particles. The non-uniform dispersion of the components in the polymerization system has adversely affected the stability of the latex, such as generation of aggregates. In addition, a long operation time caused by sequentially and individually charging the components necessary for the reaction into the polymerization vessel has been a problem from the viewpoint of productivity. Therefore, there has been a demand for the development of a simple method capable of uniformly charging the auxiliary material into the polymerization system.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a vinyl chloride-based polymer having excellent productivity, in which auxiliary materials can be uniformly charged into a polymerization system by a simple method. The purpose of the present invention is to provide a method for producing latex.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, when charging the monomer or / and water in which the auxiliary material is dissolved, the auxiliary line was added to the charging line. It has been found that the above objects can be achieved by introducing materials, and the present invention has been completed based on this finding. Thus, according to the present invention, vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith is charged into a polymerization vessel together with auxiliary materials necessary for the polymerization reaction and emulsion polymerization or fine suspension is carried out in an aqueous medium. When producing a vinyl chloride polymer latex by turbid polymerization, an oil-soluble auxiliary material is added from a pipe connected to a monomer charging pipe,
The water-soluble secondary material is added from a pipe connected to a water supply pipe, and the monomer or / and / or the monomer from the connection to the polymerization reactor is added.
And a method for producing a vinyl chloride-based polymer latex, wherein the auxiliary material is preliminarily mixed with a monomer and / or water in a supply pipe for water and water.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention is applied to the polymerization of vinyl chloride and the copolymerization of an unsaturated monomer copolymerizable with vinyl chloride, wherein the amount of vinyl chloride in the monomer mixture is 50%.
It is preferably at least 75% by weight, more preferably at least 75% 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;
Unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid;
Methyl acrylate, ethyl acrylate, acrylic acid-n
-Butyl, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid-
Unsaturated monocarboxylic acid esters such as N, N-dimethylaminoethyl; unsaturated amides such as acrylamide and methacrylamide; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid; And its anhydrides; N-substituted maleimides; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; and vinylidene compounds such as vinylidene chloride.

In the present invention, examples of auxiliary materials necessary for the polymerization reaction include an emulsifier, an emulsifier, a polymerization initiator, a chain transfer agent, and a crosslinking agent. The form in which these are added as components of the polymerization reaction is liquid. Therefore, the solid auxiliary material needs to be dissolved in a solvent or water. In the present invention, regarding the auxiliary materials necessary for these polymerization reactions,
At least one type, whether oil-soluble or water-soluble, is added from a pipe connected to a monomer or / and water supply pipe. Emulsifier is a water-soluble secondary material,
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.
In the fine suspension polymerization, an oil-soluble polar substance such as a higher alcohol having 12 to 20 carbon atoms, a higher fatty acid, or sorbitan tristearate is used as an emulsifying aid together with the above emulsifier in an amount of 0.5 to 3 per 100 parts by weight of the monomer. Often used in parts by weight.

Among the polymerization initiators, water-soluble ones include:
Examples thereof include water-soluble peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, and hydrogen peroxide, and water-soluble azo compounds such as 2,2'-azobis (2-methylpropionamidine) dihydrochloride. . In addition to these water-soluble initiators, oil-soluble hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide;
A redox-based initiator combined with a water-soluble reducing agent can be treated as a member of the water-soluble initiator. These water-soluble initiators can be used alone or in combination of two or more. Examples of the water-soluble reducing agent include hydrosulfite, sodium acid sulfite,
Water-soluble materials such as sodium sulfite, sodium ethylenediaminetetraacetate, sodium sulfinate, sodium l-ascorbate, ferrous pyrophosphate, ferrous sulfate, ferrous ammonium sulfate, and sodium formaldehyde sulfoxylate are preferably used. Is done. As the oil-soluble polymerization initiator, for example, acetyl peroxide, 3,
Diacyl peroxides such as 5,5-trimethylhexanoyl peroxide, lauroyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide; benzoyl hydroperoxide;
Cumene hydroperoxide, p-cymene hydroperoxide, diisopropylbenzene hydroperoxide, p
Hydroperoxides such as menthane hydroperoxide; peroxyesters such as t-butylperoxybivalate; peroxydicarbonates such as diisopropylperoxydicarbonate and diethylhexylperoxydicarbonate; acetylcyclohexylsulfonyl peroxide and the like. Organic peroxides such as sulfonyl peroxide; redox polymerization initiators combining these organic peroxides with reducing agents such as Rongalite; 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-
Dimethylvaleronitrile), 2,2'-azobis (4-
Azo compounds such as methoxy-2,4-dimethylvaleronitrile). The amount of the polymerization initiator to be used is generally 0.01 to 0.1 part by weight based on 100 parts by weight of the monomer.
3 parts by weight, preferably 0.02 to 0.2 parts by weight. However, when polymerized as a seed for sowing fine suspension polymerization, an oil-soluble polymerization initiator is used in an amount of 0.1 to 2 to provide a part or all of the initiator for the subsequent coating polymerization reaction.
0 parts by weight are often used. Examples of the chain transfer agent include oil-soluble agents such as octyl thioglycolate, carbon tetrachloride, methylene chloride, 2-mercaptoethanol, n-butylmercaptan, and isopropylbenzene. Examples of the crosslinking agent include oil-soluble crosslinking agents such as diallyl phthalate, diallyl maleate, diallyl adipate, diallyl ether, triallyl cyanurate, ethylene glycol divinyl ether, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

In the present invention, when the auxiliary materials required for the above-mentioned polymerization reaction are charged into a polymerization vessel, at least one type of the auxiliary materials, whether oil-soluble or water-soluble, is charged with monomers and / or water. Occasionally, a method is used in which the auxiliary material is preliminarily mixed with the monomer and / or water in a pipe connected to the monomer and / or water and added to the polymerization vessel in a pipe connected to the charging pipe. In the present invention, which sub-material is subjected to the above premixing is not limited. It is also preferable to select a secondary material that is used in a relatively large amount, such as an emulsifier or an emulsifier, but the amount used is preferably 0.1 to 100 parts by weight of the monomer.
It is more preferable to select one that is used in a small amount of less than 5 parts by weight in view of the effect of preventing ubiquity. When the auxiliary material to be subjected to the pre-mixing is oil-soluble, it is added from a pipe connected to the monomer charging pipe, and the oil-soluble sub-material is added in the monomer charging pipe from the connection portion to the polymerization vessel. The monomer is preliminarily mixed and charged into the polymerization vessel. The addition of the oil-soluble auxiliary material is started 5 to 15% after the start of the monomer charging time zone, and the oil-soluble auxiliary material is added at the time 85 to 95% after the start of the monomer charging time. It is preferable to set the instrumentation so that the addition of the auxiliary material is completed. Also,
When adding a water-soluble secondary material from a pipe connected to a water charging pipe, the water-soluble secondary material is preliminarily mixed with water in the water charging pipe from the connection portion to the polymerization vessel. Allow to be charged to the polymerization vessel. In this case, the addition of the water-soluble auxiliary material is started at a time when 5 to 15% has elapsed from the start of the water charging time zone, and the water-soluble auxiliary material is added at a time when 85 to 95% has elapsed from the start of the water charging time zone. It is preferable to set so that the addition of the auxiliary material is completed.

[0011] The piping volume of the pre-mixing section of the auxiliary material necessary for the polymerization reaction is set so that the residence time of the added auxiliary material is 10 to 10.
Preferably, the range is 600 seconds. Further, it is preferable to install a static mixer in each of the premix sections. According to the method of the present invention, the inside of the system can be made more uniform only by stirring the inside of the polymerization vessel for one hour before the polymerization reaction starts. Conventionally, a procedure has been adopted in which auxiliary materials such as a polymerization initiator, a reducing agent, a chain transfer agent, and a cross-linking agent are separately charged into a polymerization vessel from a pipe or a manhole, and the inside of the polymerization vessel is stirred after the completion of the charging of all components. However, it is not easy to uniformly mix the inside of the system after the batch charging. This is presumably because the emulsifier protects the monomer, oil-soluble auxiliary material, and the like as emulsified droplets, so that uniform dispersion cannot be achieved without stirring for a long time. According to the present invention, with simple equipment modification, auxiliary materials can be easily and uniformly charged into the polymerization vessel, thereby enabling a stable polymerization reaction, and generating less agglomerates in the produced latex, particle size, and average particle size. The quality such as the degree of polymerization and the degree of crosslinking is also stable. Further, since the oil-soluble sub-material and the water-soluble sub-material are charged at the same time as the water, shortening the charging operation time also has an effect of improving polymerization productivity.

The embodiments of the present invention will be described below. (1) Vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith is charged into a polymerization vessel together with auxiliary materials necessary for the polymerization reaction, and is subjected to emulsion polymerization or fine suspension polymerization in an aqueous medium. In producing the vinyl chloride polymer latex, the oil-soluble sub-material is added from a pipe connected to a monomer charging pipe, and the water-soluble sub-material is added from a pipe connected to a water charging pipe. A vinyl chloride-based polymer latex characterized in that auxiliary materials are premixed and charged with the monomer and / or water in a pipe for charging monomer or / and water from the connection portion to the polymerization vessel. Production method. (2) Addition of auxiliary materials necessary for the polymerization reaction is started at the time when 5 to 15% has elapsed from the start of the charging time zone of the monomer and / or water. The method for producing a vinyl chloride polymer latex according to the above (1), wherein the addition is completed at a time when 85 to 95% has elapsed from the start. (3) The method for producing a vinyl chloride polymer latex according to the above (1) or (2), wherein the pipe volume of the section for premixing is in a range where the residence time of the auxiliary material is 10 to 600 seconds. (4) The method for producing a vinyl chloride polymer latex according to any one of the above (1) to (3), wherein a static mixer is provided in a section for premixing. (5) The method for producing a vinyl chloride polymer latex according to any one of the above (1) to (4), wherein the auxiliary material is a polymerization initiator. (6) The method for producing a vinyl chloride polymer latex according to any one of the above (1) to (5), wherein the auxiliary material is a chain transfer agent. (7) The method for producing a vinyl chloride polymer latex according to any one of the above (1) to (6), wherein the auxiliary material is a crosslinking agent.

[0013]

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 MS20, manufactured by Malvern Co., Ltd.], and 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) Average degree of polymerization 0.20 gr of the vinyl chloride resin powder obtained by drying is accurately weighed and placed in a 50 ml volumetric flask, 40 ml of nitrobenzene is added, and the mixture is placed in an air bath at a temperature of 100 ° C.
Let stand for more than an hour to dissolve. Next, the measuring flask is immersed in a thermostat adjusted to a temperature of 30 ° C., and after 1 hour, nitrobenzene is added to the measuring flask with a female pipette to a mark of 50 ml. Then, using an Ubbelohde viscometer, JI
The average degree of polymerization is determined from the specific viscosity of the solution according to SK6921. (4) Sol viscosity The vinyl chloride-based polymer latex produced through the polymerization reaction was filtered through a 60-mesh wire gauze and then spray-dried, and 100 parts by weight of a resin powder and 60 parts by weight of a plasticizer di-2-ethylhexyl phthalate were obtained. Of the sol in a constant temperature / humidity chamber 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 by using a Brookfield viscometer [Tokimec Co., Ltd. ), BL type],
Measure at 6 rpm using rotor 4.

Example 1 Seeding of Vinyl Chloride In conducting fine suspension polymerization, as a seed-containing latex, 0.5 parts by weight of sodium dodecylbenzenesulfonate and 0.67 parts by weight of stearyl alcohol were used per 100 parts by weight of vinyl chloride. Latex 1 containing polymer particles having a central particle size of 0.55 μm and having a solid content concentration of 27% by weight obtained by performing fine suspension polymerization at a reaction temperature of 48 ° C. using 0.5 parts by weight of lauroyl peroxide.
0 Kg was collected and put into a glass-lined polymerization vessel having an inner volume of 100 liter with stirring blades, and further 30 K of deionized water.
g and sodium dodecylbenzenesulfonate 200 g
r was added and degassed in vacuo. Next, when 36 kg of the vinyl chloride monomer is charged into the polymerization vessel, 70 gr of octyl thioglycolate as a chain transfer agent is charged by a high-pressure metering pump from the charging valve immediately adjacent to the polymerization vessel to the vinyl chloride charging pipe as a premixing time of 20 g. Injected into a position that is secured for seconds. The octyl thioglycolate was added continuously over the 10-90% time period from the beginning of the vinyl chloride charging time while mixing with the vinyl chloride in the charging pipe. Then, while rotating the stirring blade at 100 rpm, the content was heated to 64 ° C. to initiate polymerization. At the time of 8.5 HR after the start of polymerization, the polymerization rate was 87%, and when the polymerization pressure was 1.5 kg / cm ² lower than the pressure at the start of polymerization, the polymerization was terminated, stirring was stopped, and the content was raised to 70 ° C. The monomer was recovered. Thereafter, the contents were taken out and spray-dried under predetermined conditions. The results are shown in Table 1.

Example 2 A pressure-resistant reactor with an internal volume of 100 liters equipped with a stirrer was charged with 30 kg of deionized water, 350 gr of sodium lauryl sulfate and 385 gr of a higher alcohol having 12 to 18 carbon atoms to degas. Next, when 35 kg of the vinyl chloride monomer is charged into the polymerization vessel, 13 gr of a 70% concentration of di-2-ethylhexylperoxydicarbonate in a toluene solution as a polymerization initiator is supplied to a vinyl chloride charging pipe by a high-pressure metering pump. At a position where a premixing time of 20 seconds is secured from the charging valve immediately adjacent to the polymerization reactor, and at the same time, 64 g of the cross-linking agent diallyl phthalate is used as a premixing time from the charging valve immediately adjacent to the polymerization reactor to the vinyl chloride charging pipe by a high-pressure metering pump. Each was injected into a position secured for 20 seconds.
Both the polymerization initiator and the diallyl phthalate were added continuously while mixing with vinyl chloride in the charging pipe over a time period of 8 to 92% from the beginning of the vinyl chloride charging time. Thereafter, the mixture was stirred for 30 minutes and 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-lined polymerization vessel, 47 ° C
And the suspension polymerization was performed at this temperature. About 15
After a lapse of time, the polymerization was terminated at a point of time when the pressure decreased by 1.0 kg / cm ² at a conversion rate of 82%, the unreacted monomer was recovered, and the content was taken out and spray dried. Table 1 shows the results.

Comparative Example 1 Chain transfer agent Octyl thioglycolate 70 gr
Was carried out in the same manner as in Example 1 except that after the charging of vinyl chloride was completed, the mixture was directly added to the polymerization reactor by a high-pressure metering pump. The results are shown in Table 1. Comparative Example 2 The procedure of Example 2 was repeated, except that 64 gr of diallyl phthalate was directly added to the polymerization reactor by a high-pressure metering pump after the completion of the charging of vinyl chloride. The results are shown in Table 1.

[0018]

[Table 1]

When Example 1 and Comparative Example 1 are compared, a vinyl chloride-based polymer which contains polymer particles having a center average particle diameter of 1.3 μm and a concentration of about 47% and can give a plastisol having substantially the same viscosity is obtained. Although a latex was obtained, Example 1 was a stable latex with a smaller amount of aggregates generated. In Example 1, the average degree of polymerization was 700, which was reasonable in view of the amount of octyl thioglycolate used.
On the other hand, in Comparative Example 1, in a place slightly higher than 750,
The result showed that the chain transfer agent was not working effectively. Also,
Comparing Example 2 with Comparative Example 2, a vinyl chloride polymer latex containing polymer particles having a center average diameter of 1.1 μm and having a concentration of about 47% and capable of giving a plastisol having the same viscosity was obtained. However, Example 2 was a more stable latex with a smaller amount of aggregates generated. The average degree of polymerization was 3500, which was appropriate in view of the amount of diallyl phthalate used in Example 2, whereas the comparative example 2 was a slightly lower value of 3200, indicating that the crosslinking agent did not work effectively. Indicated.

[0020]

According to the method of the present invention, the auxiliary materials can be easily and uniformly charged in the polymerization vessel, whereby the polymerization reaction can be performed with good productivity and stable latex properties and stable polymer quality can be obtained. Can be realized.

Claims (1)

[Claims] 1. A vinyl chloride or a mixture of vinyl chloride and an unsaturated monomer copolymerizable therewith is charged into a polymerization vessel together with auxiliary materials necessary for the polymerization reaction, and emulsion polymerization or fine suspension polymerization is carried out in an aqueous medium. When producing a vinyl chloride polymer latex, the oil-soluble sub-material is added from the pipe connected to the monomer charging pipe, and the water-soluble sub-material is added from the pipe connected to the water charging pipe. A vinyl chloride-based polymer characterized in that the auxiliary material is premixed with the monomer and / or water and charged in the monomer or / and water charging pipe from the connection portion to the polymerization vessel. Latex manufacturing method.