JP3552407B2 - Method for producing vinyl chloride polymer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention, in the particle size distribution of number-based, relates to three preparation of vinyl chloride polymer latex having a maximum value.
The vinyl chloride-based polymer latex obtained in the present invention gives a polymer having a high packing density when dried, and a plastisol having good fluidity when a plasticizer or the like is added thereto. In particular, according to the present invention, a vinyl chloride polymer latex that can provide a vinyl chloride polymer suitable for a paste can be easily produced.
[0002]
[Prior art]
Plastisols containing plasticizers and the like in a vinyl chloride polymer for pastes are used for various purposes such as flooring and wallpaper production, rust-proof coating (undercoat) for automobiles by coating, dipping, spraying and other processing methods. It has been offered to. In the production of flooring and wallpaper, a method of applying this plastisol on a substrate by a method such as knife coating is widely used, and in order to improve productivity, the viscosity of the plastisol, particularly 10 ² sec ⁻¹ or more, is used. It is desired to lower the viscosity in a so-called high shear rate region. In addition, a spray coating method is frequently used for undercoating of automobiles. In this case, too, a low viscosity in a high shear rate region is required in order to stabilize the spray.
[0003]
[Problems to be solved by the invention]
As one of techniques for improving the fluidity of plastisol, it has been proposed to use a vinyl chloride polymer having a plurality of maximum values in a number-based particle size distribution. For example, Japanese Patent Publication No. 61-8843 discloses that a vinyl chloride polymer latex having two maximum values in particle size distribution is mixed and spray-dried. However, the plastisol obtained by blending a plasticizer with the vinyl chloride polymer obtained by this method has a drawback that the viscosity in the high shear rate region is not sufficiently reduced. JP-A-7-53627 discloses that a vinyl chloride polymer latex having a maximum value of 3 to 6 particles in a particle size distribution is produced by mixing vinyl chloride polymer latexes obtained by different production methods. Is disclosed. Further, JP-A-5-155908 discloses that a plurality of vinyl chloride-based polymer latexes are mixed to form a seed latex having a plurality of maximum values in particle size distribution, and a vinyl chloride-based monomer is added in the presence of the seed latex. It is described that a vinyl chloride polymer latex having a plurality of maximum values is produced by polymerizing a polymer.
[0004]
However, the method of mixing a plurality of latexes employed in these methods has the disadvantage that the operation is complicated and it is difficult to maintain the stability of the latex. Accordingly, the present invention is Ru der which provides cents a method for easily producing a vinyl chloride polymer latex having a three maxima in the particle size distribution of number basis.
[0005]
[Means for Solving the Problems]
According to the present invention, first, a vinyl chloride-based monomer (in the present specification, a vinyl chloride-based monomer means vinyl chloride or a mixture of vinyl chloride and another monomer copolymerizable therewith. The proportion of vinyl chloride in the mixture is usually 80% by weight or more) is subjected to emulsion polymerization or fine suspension polymerization to produce a vinyl chloride polymer latex, which is then used as a seed latex to obtain a vinyl chloride monomer. The emulsion is subjected to emulsion polymerization or fine suspension polymerization to produce a second vinyl chloride-based polymer latex, which is further used as a seed latex to again carry out emulsion polymerization or fine suspension polymerization of the vinyl chloride-based monomer to obtain a number. A vinyl chloride polymer latex having three maximum values in a standard particle size distribution can be produced.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described in detail. In the present invention, a vinyl chloride monomer, that is, a mixture of vinyl chloride or vinyl chloride and another monomer copolymerizable therewith is used as a raw material, and three particles have a particle size distribution. A vinyl chloride polymer having a maximum value is produced. Other copolymerizable monomers include vinyl esters such as vinyl acetate, vinyl propionate and vinyl stearate, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, octyl vinyl ether and lauryl vinyl ether, acrylic acid, methacrylic acid, Examples include unsaturated carboxylic acids such as itaconic acid and alkyl esters thereof, vinylidene chloride, unsaturated nitrile and the like. The mixture to be subjected to polymerization may contain two or more of these.
[0007]
In the present invention, first, in step (I), a vinyl chloride monomer is subjected to emulsion polymerization or fine suspension polymerization by a conventional method to produce a polymer latex having one maximum value in the number-based particle size distribution. I do. Emulsion polymerization may be performed in an aqueous medium containing an emulsifier using a water-soluble polymerization initiator. The fine suspension polymerization may be performed by dispersing a vinyl chloride monomer in the form of fine droplets using a homogenizer in the presence of an emulsifier, and using an oil-soluble polymerization initiator. As the emulsifier, an alkali metal salt or an ammonium salt such as a higher alcohol sulfate, an alkylbenzene sulfonic acid, or a higher fatty acid is used. Also, an anionic surfactant can be used. Two or more of these surfactants can be used in combination, and a nonionic surfactant can be used in combination with them.
[0008]
These emulsifiers are used in an amount of usually 0.1 to 3% by weight, preferably 0.3 to 1% by weight, based on the vinyl chloride monomer.
It is also preferable to use 0.2 to 2% by weight of a higher alcohol having 10 to 18 carbon atoms as an emulsifying aid.
As the polymerization initiator, in the case of emulsion polymerization, for example, water-soluble peroxides such as sodium salt, potassium salt, ammonium salt and hydrogen peroxide of persulfuric acid, or these water-soluble peroxides and water-soluble reducing agents, For example, a water-soluble redox polymerization initiator composed of sodium sulfite, sodium pyrosulfite, sodium bisulfite, ascorbic acid, sodium formaldehyde sulfoxylate, or the like is used. In the case of fine suspension polymerization, an oil-soluble polymerization initiator soluble in monomers such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, lauroyl peroxide, t-butylperoxypivalate, or A redox polymerization initiator comprising a combination of these oil-soluble polymerization initiators and the above-mentioned water-soluble reducing agent is used.
[0009]
These polymerization initiators are preferably used in an amount of about 0.01 to 0.5% by weight, particularly about 0.01 to 0.2% by weight, based on the vinyl chloride-based monomer.
The polymerization reaction system may further include a polymerization degree regulator and other auxiliaries.
As the polymerization degree regulator, a chain transfer agent such as trichloroethylene, carbon tetrachloride, 2-mercaptoethanol, octyl mercaptan, a cross-linking agent such as diallyl phthalate, triallyl isocyanurate, ethylene glycol diacrylate, trimethylolpropane trimethacrylate, and the like. Used.
[0010]
Other auxiliary agents include, for example, water-soluble transition metal salts such as cupric chloride, ferrous sulfate, and nickel nitrate that act as activators for redox polymerization initiators, and monohydrogen phosphate or dihydrogen alkali metal. PH adjusters such as salts, potassium hydrogen phthalate and sodium hydrogen carbonate.
In either case of emulsion polymerization or fine suspension polymerization, the polymerization degree is usually about 40 to 70 ° C, and the polymerization time is usually about 4 to 10 hours.
By this polymerization reaction, the same pattern as the particle size distribution pattern of the vinyl chloride polymer latex having one local maximum in the number-based particle size distribution, that is, the polymer latex produced by ordinary emulsion polymerization or fine suspension polymerization. Of latex. The maximum value is preferably in a particle size range of 0.3 to 0.6 μm, and the particle size distribution is preferably sharp.
[0011]
In the present invention, as step (II), emulsion polymerization or fine suspension polymerization of a vinyl chloride monomer is carried out in the same manner as described above, using the polymer obtained above as a seed, and two particles in the particle size distribution are obtained. To produce a polymer latex having a maximum value of The emulsion polymerization method is preferred because of the control of the reaction and the control of the particle size of the obtained latex.
Usually, the polymer latex obtained above is used as a seed without drying. The amount of the polymer latex to be used is usually 3 to 6% by weight, preferably 3.5 to 5% by weight, based on the total amount of the vinyl chloride monomer and the polymer in the latex. The conditions for the seed polymerization may be the same as those for the polymerization for producing the seed. That is, the polymerization temperature is about 40 to 70 ° C., and the polymerization time is about 3 to 9 hours. The same emulsifier, polymerization initiator and other auxiliaries as those used in the production of the seed can be used.
[0012]
Preferably, as the emulsifier, sodium lauryl sulfate or sodium alkylbenzene sulfonate, which has a small amount of new polymer particles and has an action of suppressing aggregation of the polymer particles, is used. Further, as the polymerization initiator, hydrogen peroxide or other water-soluble peroxide is used. These emulsifiers and polymerization initiators are preferably added continuously to the reaction system during the emulsion polymerization reaction.
[0013]
In the sheet polymerization, a seed enlargement reaction and a new polymer particle formation reaction are caused simultaneously, and a polymer latex having two maximum values in a number-based particle size distribution is generated. That is, the seed polymerization is to provide a latex having one maximum, preferably one maximum, and a sharp particle size distribution if no seed is present. Done. The two maximum values are preferably in the particle size range of 0.2 to 0.5 μm and 0.7 to 1.6 μm.
[0014]
In the present invention, as a step (III), the latex having two maximum values in the particle size distribution obtained above is used as a seed, and emulsion polymerization or fine suspension of a vinyl chloride monomer is performed in the same manner as described above. The polymerization is carried out to produce a polymer latex having three maximum values in the particle size distribution. Also in this case, it is preferable to carry out emulsion polymerization from the viewpoint of easy control of the reaction and control of the particle size of the obtained latex. The seed polymer latex is preferably used as it is without drying. The amount of the polymer latex used is usually 4 to 12% by weight, preferably 6 to 10% by weight, based on the total amount of the vinyl chloride monomer and the polymer in the polymer latex.
[0015]
This seed polymerization can also be performed under the same conditions as the above-mentioned seed polymerization. The polymerization temperature is about 40 to 70 ° C., and the polymerization time is about 3 to 8 hours. The same emulsifier, polymerization initiator and other auxiliaries as those used in the above-mentioned seed polymerization can be used. Also in this seed polymerization, it is necessary to continuously add an emulsifier such as sodium lauryl sulfate and sodium alkylbenzene sulfonate, and a polymerization initiator such as hydrogen peroxide and other water-soluble peroxides to the reaction system during the polymerization reaction. preferable. Also in this seed polymerization, the seed enlargement reaction and the formation reaction of new polymer particles occur simultaneously, and a polymer latex having three maximum values in the number-based particle size distribution is generated. That is, the seed polymerization is also performed so as to provide a latex having one local maximum if no seed is present.
[0016]
The three maximum values of the vinyl chloride polymer latex obtained in the present invention are in the particle size range of 0.1 to 0.4 μm, 0.6 to 1.0 μm, and more than 1.0 μm to 2.0 μm. Is preferred.
Particularly preferred polymer latexes have maxima from 0.1 to 0.4 μm, 0.6 to 1.0 μm and more than 1.0 μm to 2.0 μm, and lie between these three maxima. Of the two minimum values, the weight of the particles smaller than the smaller minimum value of the particle size is 10 to 50% by weight of the entire polymer, and the weight of the particles larger than the minimum value of the larger particle size is the weight of the entire polymer. Latex accounts for 30 to 40% by weight. The latex having such a particle composition exhibits a low viscosity in a high shear rate region, and gives a plastisol with good workability.
[0017]
The vinyl chloride polymer latex having three maximum values produced by the method of the present invention is subjected to a commercialization process such as drying and pulverization by a conventional method to obtain a vinyl chloride polymer of the product. At that time, if necessary, a usual adjusting emulsifier, an antioxidant and other auxiliaries, a modifier, and the like may be added. Further, the vinyl chloride polymer thus obtained is used as a compounding agent such as a plasticizer, an organic solvent, a stabilizer, a filler, an antioxidant, an ultraviolet absorber, an antistatic agent, a colorant, and a release agent. Is appropriately blended and used as a plastisol or organosol.
In the present invention, the particle size distribution of the vinyl chloride polymer is measured using CHDF-1100 manufactured by MATEC APPLIED SCIENCES, which is a capillary type submicron particle size distribution analyzer.
[0018]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless departing from the gist of the invention. In the examples, "%" represents "% by weight" unless otherwise specified.
Example 1
The following steps (I), (II) and (III) were performed to obtain a vinyl chloride polymer latex.
[0019]
Step (I):
90 kg of deionized water at a temperature of 54 ° C., 10 g of potassium persulfate, 50 g of sodium pyrosulfite, and 22 g of sodium lauryl sulfate as an initial emulsifier were charged into a 300-liter polymerization vessel equipped with a stirrer, and stirred for about 20 minutes after deaeration. And dissolved. Next, 60 kg of vinyl chloride was charged into the polymerization can, stirred and emulsified, and the temperature in the can was adjusted to 50 ° C. Fifteen minutes after the completion of the charging of vinyl chloride, a total of 10 g of potassium persulfate was converted into a 0.2% aqueous solution of potassium persulfate while controlling the polymerization reaction rate to be constant. Was added. When the polymerization rate reached about 15%, a 10% aqueous solution of sodium lauryl sulfate was added at a rate of about 80 ml / 10 minutes, and the addition was continued until the total amount of sodium lauryl sulfate reached 360 g. The reaction was stopped when the pressure in the vessel dropped from the saturation pressure of vinyl chloride at 50 ° C. by 1960 hPa (2 kg / cm ² ), and unreacted vinyl chloride was recovered to obtain a vinyl chloride polymer latex. This latex was composed of particles having a sharp particle size distribution having a maximum value of the particle size distribution at a position where the particle size was 0.35 μm, and the stability was good.
[0020]
Step (II):
80 kg of deionized water and 3.0 kg of the vinyl chloride polymer latex prepared in the above step (I) in a solid content of 3.0 kg were charged into a 300 l polymerization vessel equipped with a stirrer. 77.0 kg of vinyl was added and emulsified. After the temperature in the can was raised to 55 ° C., a redox polymerization initiator of hydrogen peroxide-sodium formaldehyde sulfoxylate was continuously added so that the total amount was 0.05% based on vinyl chloride. Further, when the polymerization rate reaches 10% with respect to the total amount of the seed polymer and vinyl chloride, a total of 500 g of sodium lauryl sulfate is added to vinyl chloride at a rate of about 0.08% per hour at 10%. It was added continuously as an aqueous solution.
[0021]
The reaction was stopped when the pressure in the can was lowered by 980 hPa (1 kg / cm ² ) from the saturation pressure of vinyl chloride at 55 ° C., and unreacted vinyl chloride was recovered to obtain a vinyl chloride polymer latex. The particle composition of the vinyl chloride polymer in the latex shows a maximum value at two points of a particle diameter of 0.30 μm and 0.95 μm, and two peaks are independent in a particle diameter distribution curve, that is, a so-called two-peak particle diameter. The distribution was shown. The weight of particles larger than the minimum existing between the local maximums was 78% of the polymer weight, and the weight of particles smaller than the local minimum was 22%.
[0022]
Step (III):
80 kg of deionized water and 8 kg of a solid content of the vinyl chloride polymer latex prepared in the above step (II) were charged into a 300 liter polymerization vessel equipped with a stirrer, and then degassed to obtain 72 kg of vinyl chloride. It was emulsified by addition. After the temperature in the vessel was raised to 55 ° C., a redox polymerization initiator of hydrogen peroxide-sodium formaldehyde sulfoxylate was continuously added so that the total addition amount was 0.05% based on vinyl chloride. Further, when the polymerization rate reaches 15% with respect to the total amount of the seed polymer and vinyl chloride, a total of 500 g of sodium lauryl sulfate is added to a 10% aqueous solution at a rate of about 0.10% per hour to vinyl chloride. Was added continuously.
[0023]
The reaction was stopped when the pressure in the can was lowered by 980 hPa (1 kg / cm ² ) from the saturation pressure of vinyl chloride at 55 ° C., and unreacted vinyl chloride was recovered to obtain a vinyl chloride polymer latex. The particle composition of the vinyl chloride polymer in the latex shows maximum values at three points of particle diameters of 0.13 μm, 0.65 μm and 1.46 μm, and three peaks are independent in the particle diameter distribution curve, so-called Miyama. The particle size distribution is shown. The weight of particles larger than the minimum between 0.65 μm and 1.46 μm is 33% of the total polymer, and the weight of particles smaller than the minimum between 0.13 μm and 0.65 μm is less than the total weight. It was 31% of the polymer.
Example 2
The following steps (I), (II) and (III) were performed to obtain a vinyl chloride polymer latex.
[0024]
Step (I):
75 kg of deionized water, 100 g of lauroyl peroxide, 558 g of sodium lauryl sulfate, and 400 g of lauryl alcohol are added to a 300-liter premixing tank equipped with a stirrer and an emulsifier (Manton-Gaulin high-pressure homogenizer). After degassing, 60 kg of vinyl chloride was added, and the mixture was maintained at 35 ° C. with uniform stirring. Then, while dispersing into fine droplets under the conditions of a primary pressure of 14.8 MPa and a secondary pressure of 5.0 MPa using an emulsifier, a 300-liter capacity polymerization vessel equipped with a stirrer in which the dispersion was previously degassed. Transferred to.
After the transfer of the dispersion was completed, the temperature of the polymerization vessel was raised to 55 ° C., and polymerization was started with stirring. The reaction was stopped when the pressure in the vessel dropped 980 hPa (1 kg / cm ² ) from the saturation pressure of vinyl chloride at 55 ° C., and unreacted vinyl chloride was recovered to obtain a vinyl chloride polymer latex. This latex consisted of a polymer with a sharp particle size distribution having a maximum at 0.48 μm.
[0025]
Step (II):
A method similar to that of step (II) in Example 1 except that the vinyl chloride polymer latex obtained in the above step (I) was used in an amount of 4.0 kg in solid content and the amount of vinyl chloride added was changed to 76 kg. Was performed to obtain a vinyl chloride polymer latex. The particle composition of the vinyl chloride polymer in the latex shows a maximum value at two points of 0.35 μm and 1.19 μm in diameter, and a so-called two-peak particle size distribution in which two peaks are independent in the particle size distribution curve. Indicated. The weight of particles larger than the minimum existing between the two maximums was 70% of the polymer weight, and the weight of particles smaller than the minimum was 30%.
[0026]
Step (III):
80 kg of deionized water and 8 kg of the vinyl chloride-based polymer latex prepared in the above step (II) were charged in a solid content of 8 kg into a 300-liter polymerization can equipped with a stirrer, and then degassed to obtain 72 kg of vinyl chloride. It was emulsified by addition. After the temperature in the vessel was raised to 55 ° C., a redox polymerization initiator of hydrogen peroxide-sodium formaldehyde sulfoxylate was continuously added so that the total addition amount was 0.05% based on vinyl chloride. Further, when the polymerization rate reaches 15% with respect to the total amount of the seed polymer and vinyl chloride, a total of 500 g of sodium lauryl sulfate is added to a 10% aqueous solution at a rate of about 0.10% per hour with respect to vinyl chloride. Was added continuously.
[0027]
The reaction was stopped when the pressure in the can was lowered by 980 hPa (1 kg / cm ² ) from the saturation pressure of vinyl chloride at 55 ° C., and unreacted vinyl chloride was recovered to obtain a vinyl chloride polymer latex. The particle composition of the vinyl chloride polymer in the latex shows so-called three-peak particles in which maximum values are shown at three points of diameters 0.19 μm, 0.71 μm and 1.68 μm, and three peaks are independent in the particle diameter distribution curve. The diameter distribution was shown. The weight of particles larger than the minimum between 0.71 μm and 1.68 μm is 38% of the total polymer, and the weight of particles smaller than the minimum between 0.19 μm and 0.71 μm is the total weight 25% of the coalescence.
[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, a three-peak particle size distribution latex can be easily manufactured without performing the mixing operation of latex.

Claims (6)

In a method for producing a vinyl chloride polymer latex by emulsion polymerization or fine suspension polymerization of a vinyl chloride monomer, the number is obtained by performing the following steps (I), (II) and (III). A method for producing a vinyl chloride polymer latex having three maximum values in a standard particle size distribution.
Step (I): Emulsion polymerization or fine suspension polymerization of a vinyl chloride monomer to produce a vinyl chloride polymer having one maximum value in a number-based particle size distribution.
Step (II): Emulsion polymerization or fine suspension polymerization of a vinyl chloride monomer in the presence of the vinyl chloride polymer obtained in Step (I) to obtain two peaks in the number-based particle size distribution. A vinyl chloride polymer having a specific value is produced.
Step (III): Emulsion polymerization or fine suspension polymerization of a vinyl chloride-based monomer in the presence of the vinyl chloride-based polymer obtained in Step (II) to obtain three maximum particles in a number-based particle size distribution. A vinyl chloride polymer having a specific value is produced. 2. The method according to claim 1, wherein the amount of the vinyl chloride polymer in the step (II) is 3 to 6% by weight based on the total amount of the vinyl chloride polymer and the vinyl chloride monomer. Method. 3. The amount of the vinyl chloride polymer in the step (III) is 4 to 12% by weight based on the total amount of the vinyl chloride polymer and the vinyl chloride monomer. The described method. 4. The method according to claim 1, wherein the three maximum values are in the range of more than 0.1 to 0.4 [mu] m, 0.6 to 1.0 [mu] m and 1.0 [mu] m to 2.0 [mu] m, respectively. The method according to any of the above. Of the two local maxima present between the three local maxima, the weight of particles having a particle size smaller than the smaller local maximum is 10 to 50% by weight of the whole polymer, and the particles larger than the larger local maximum. 5. The method according to claim 1, wherein the weight of the particles having a diameter accounts for 30 to 40% by weight of the total polymer. In a method for producing a vinyl chloride polymer latex by polymerizing a vinyl chloride monomer, the following steps (I ′) and ( II ') And the process ( III '), Producing a vinyl chloride polymer latex having three maximum values in the number-based particle size distribution.
  Step (I ') A vinyl chloride polymer latex having one maximum value in a number-based particle size distribution is produced by subjecting a vinyl chloride monomer to emulsion polymerization or fine suspension polymerization.
  Process ( II ') Emulsion polymerization of a vinyl chloride monomer in the presence of the vinyl chloride polymer latex obtained in step (I') to give a vinyl chloride polymer having two maximum values in the number-based particle size distribution Produce a polymer latex. However, the amount of the vinyl chloride polymer in the total of the vinyl chloride polymer and the vinyl chloride monomer in the vinyl chloride polymer latex used in this step is 3 to 6% by weight.
Process ( III ′) Process ( II ') Emulsion polymerization of a vinyl chloride monomer in the presence of the vinyl chloride polymer latex obtained in (1) to produce a vinyl chloride polymer latex having three maximum values in the number-based particle size distribution. I do. However, the amount of the vinyl chloride polymer in the total of the vinyl chloride polymer and the vinyl chloride monomer in the vinyl chloride polymer latex used in this step is 4 to 12% by weight.