JP3508171B2 - Method for producing vinyl chloride resin - Google Patents

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has a high packing density of dry particles, and by mixing this with a plasticizer and the like, it has good fluidity suitable for the production of flooring materials, wallpaper, etc. by a paste processing method. The present invention relates to a method for producing a vinyl chloride resin, which is capable of giving a plastisol and is particularly suitable for a paste.

[0002]

2. Description of the Related Art A vinyl chloride resin for paste is applied in a form of plastisol (hereinafter sometimes abbreviated as "sol") in which it is mixed with a compounding agent such as a plasticizer, coating (immersion), dipping (dipping), Alternatively, molding and processing are performed by spray coating or other processing methods. Among them, in the field of manufacturing flooring materials, wallpaper, etc., a method of coating sol on a substrate by a method such as knife coating and processing is widely used, and in order to improve its production speed, plastisol It is desired to lower the viscosity, particularly to lower the viscosity in the so-called "high shear rate region" of 10 ² sec ^-1 or more. In addition, a spray coating method is often used for the undercoat of the body for automobile rust prevention, etc., but in order to stabilize the spray at this time, lower viscosity in the high shear rate region is required. Has been.

Up to now, in order to improve the fluidity of plastisol, a graph of particle size distribution (hereinafter referred to as "particles") containing two groups of particles, that is, the relationship between the particle size and the number frequency thereof is shown. Japanese Patent Publication No. Sho 61-8843 discloses a method of spray-drying a vinyl chloride polymer latex having a maximum number frequency of 2 points in the "diameter distribution"). However, the plastisol obtained by mixing the vinyl chloride resin obtained by this method with, for example, 40 parts by weight of a plasticizer with respect to 100 parts by weight of the resin does not have a sufficiently low viscosity in the high shear rate region. Therefore, it has been desired to further reduce the viscosity in order to improve the processing speed.

[0004]

PROBLEM TO BE SOLVED BY THE INVENTION A process for producing a vinyl chloride resin which has a high packing density of dry particles and can give a plastisol having a low viscosity even in a high shear rate region in a processing method such as coating and spraying. This is the subject of the present invention.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies on a method for producing a vinyl chloride resin capable of giving a plastisol having a low viscosity in a high shear rate region and being easily processed. By spray-drying a vinyl chloride polymer latex exhibiting a diameter distribution, a vinyl chloride resin having a high density of dry particles (aggregation packing density) can be obtained.
The inventors have found that a plastisol having a low viscosity can be prepared, and completed the present invention.

That is, the gist of the present invention is to use a vinyl chloride polymer latex (hereinafter referred to as "polydispersed particle size distribution latex") having a maximum number frequency of 3 to 6 in the particle size distribution as a two-fluid nozzle. Using the dry air flow at the device outlet
A method for producing a vinyl chloride resin, which comprises spray-drying at a temperature of 50 to 70 ° C. The present invention will be described in detail below. The “maximum value” referred to in the present specification is a graph of the particle size distribution represented by the relationship between the particle size and the number frequency thereof, that is, what is indicated by the number frequency on the “particle size distribution”.

The particle size distribution is preferably measured by a method in which an effective number of at least two digits is obtained for the particle size, and also in the graph of the particle size distribution in which the number frequency is plotted against the particle size. It is desirable that the particle size is engraved on a logarithmic scale with the horizontal axis as the accuracy so as to give an effective number of two digits or more. Examples of the measuring method satisfying such conditions include a laser diffraction method and a photo-centrifugal sedimentation method.

The polydisperse particle size distribution latex used in the method of the present invention is prepared, for example, by the following method. Water-soluble polymerization of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a comonomer copolymerizable therewith (hereinafter collectively referred to as "vinyl chloride monomer") in an aqueous medium in the presence of an emulsifier. Polymerization using an initiator (emulsion polymerization method) or homogenization of vinyl chloride monomer with a homogenizer in the presence of an emulsifier to finely disperse the oil-soluble polymerization initiator A vinyl chloride polymer latex showing a particle size distribution having a single maximum value is produced by a polymerization method (fine suspension polymerization method). By changing the polymerization conditions, several kinds of vinyl chloride polymerized latexes having different particle diameters that give maximum values are prepared, and these latexes are mixed to prepare a polydisperse particle size distribution latex. The vinyl chloride polymer latex showing a particle size distribution having a single maximum value produced above is further subjected to emulsion polymerization of a vinyl chloride monomer using a seed polymer, which has two maximum values by so-called seed polymerization. A vinyl chloride polymer latex having a particle size distribution is produced, and one or more kinds of latexes having mutually different particle sizes giving a maximum value are mixed to prepare a polydisperse particle size distribution latex.

Comonomers which can be copolymerized with vinyl chloride monomers include vinyl esters such as vinyl acetate, vinyl propionate and vinyl stearate, monounsaturated acids such as acrylic acid, methacrylic acid and itaconic acid. Alkyl ester of monounsaturated acid, methyl vinyl ether,
Vinyl ether such as ethyl vinyl ether, octyl vinyl ether, lauryl vinyl ether, maleic acid,
Examples thereof include diunsaturated acids such as fumaric acid, alkyl esters of these divalent unsaturated acids, vinylidene halides such as vinylidene chloride and unsaturated nitriles, and one or more mixtures thereof.

As the polymerization initiator, in the case of emulsion polymerization,
For example, persulfates (sodium salts, potassium salts, ammonium salts, etc.), water-soluble peroxides such as hydrogen peroxide, or water-soluble peroxides thereof and water-soluble reducing agents (eg sodium sulfite, sodium pyrosulfite, sulfite). Water-soluble redox initiator consisting of sodium hydrogen, ascorbic acid, sodium formaldehyde sulfoxylate, etc., and in the case of fine suspension polymerization, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile,
Examples thereof include monomer-soluble (oil-soluble) initiators such as lauroyl peroxide and t-butylperoxypivalate, or redox initiators composed of a combination of these oil-soluble initiators and the above water-soluble reducing agent.

As the emulsifier, for example, higher alcohol sulfate ester salt (alkali metal salt, ammonium salt), alkylbenzene sulfonate (alkali metal salt, ammonium salt), higher fatty acid salt (alkali metal salt, ammonium salt), etc. Anionic surfactants of These surfactants may be used alone or in combination of two or more. Moreover, you may use together a nonionic surfactant.

Further, in the production of latex, a polymerization degree adjusting agent and other auxiliaries may be used. As the polymerization degree adjusting agent, for example, trichloroethylene, carbon tetrachloride,
Examples thereof include chain transfer agents such as 2-mercaptoethanol and octyl mercaptan, and crosslinking agents such as diallyl phthalate, triallyl isocyanurate, ethylene glycol diacrylate and trimethylolpropane trimethacrylate.

In addition to the above, other auxiliaries include, for example, water-soluble transition metal salts such as cupric chloride, ferrous sulfate and nickel (II) nitrate which act as activators of redox initiators, or Alternatively, a pH adjusting agent such as an alkali metal dihydrogen phosphate, potassium hydrogen phthalate, or sodium hydrogen carbonate can be used. The polydisperse particle size distribution latex gives a maximum value with a number frequency of 3 to 6 points in the particle size distribution, but the maximum value score is 3 to 4 points, especially 3 points.
The point is preferable in terms of workability in preparing the polydisperse particle size distribution latex. Further, with respect to a latex having a maximum value of 7 points or more, generally, the packing efficiency of dry particles does not improve to the extent that the complexity of the preparation increases, and therefore it is not suitable for industrial implementation.

The particle size that gives the maximum value of the polydisperse particle size distribution latex is not particularly limited, but it is preferably in the range of 0.05 to 10 μm from the viewpoint of stability of the latex. In the particle size distribution showing a plurality of maximum values, it is preferable that the respective maximums in the distribution curve are independent of each other because the viscosity in the high shear rate region tends to be lower. It should be noted that the term "independent maximums in the distribution curve" means that the minimum value existing between two adjacent maximum values in the particle size distribution is 2% or less in number frequency (absolute value), preferably 0.5
% Or less.

In the case of a polydisperse particle size distribution latex having three maximum values, that is, a so-called three-peak particle size distribution latex, the particle size giving the maximum value is preferably in the range of 0.05 to 3 μm, and the maximum value is further increased. The three particle sizes given are 0.
It is preferable that the center values of 1 μm, 0.4 μm, and 1.3 μm are within ± 20%, because the packing efficiency of particles tends to be high during spray drying.

The polydisperse particle size distribution latex preferably has a solid concentration of 30 to 70% by weight. The solid content concentration is the same as before the preparation of the polydisperse particle size distribution latex, even if the solid content concentration of each of the above-mentioned and latexes is adjusted by, for example, a method such as ultrafiltration. The solid content concentration may be adjusted to be high. By increasing the solid content concentration, the amount of water evaporated during spray drying can be reduced, energy can be saved, and the porosity of the dry particles can be reduced to obtain particles with a higher packing density.

In the spray drying of the present invention, a usual spray drying apparatus used for producing a vinyl chloride resin for paste can be used. Examples of the spraying method include a rotating disk type, a pressure nozzle type, a two-fluid nozzle type, and the like. Among them, spray drying using a two-fluid nozzle is a vinyl chloride resin obtained. Is preferable because the plastisol prepared from the above tends to have a low viscosity in the high shear rate region.

The temperature at the time of spray drying is usually such that the temperature of the drying air stream at the inlet of the drying device is 100 to 200 ° C and the temperature of the outlet is 45 to 80 ° C. In particular, it is preferable to adjust the latex supply rate so that the temperature of the drying air stream at the outlet of the drying device is in the range of 50 to 70 ° C. When spray drying with a two-fluid nozzle is performed under the above conditions, the vinyl chloride resin obtained and 40 parts by weight of di-2-ethylhexyl phthalate (DOP) as a plasticizer are mixed with 100 parts by weight of this resin. The plastisol prepared as described above has a tendency to exhibit good fluidity, with a seabass outflow rate (measuring method described later) being an index of viscosity in a high shear rate region being usually about 100 to 180 g per 100 seconds. Become.

[0019]

EXAMPLES Specific embodiments of the present invention will be described below in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.
"Parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively, unless otherwise specified.

<Example 1 (Production of Vinyl Chloride Resin A)> (1) Production of Vinyl Chloride Polymer Latex 1 A polymerization can having a volume of 300 liters equipped with a stirrer and a temperature of 54
90 kg of deionized water at 0 ° C., 10 g of potassium persulfate, 50 g of sodium pyrosulfite and 18 g of sodium lauryl sulfate as an initial emulsifier were charged and dissolved by stirring for about 20 minutes. Then, 60 kg of vinyl chloride monomer was charged into the polymerization vessel, and the temperature inside the vessel was adjusted to 50 ° C. After 15 minutes from the completion of the charging of the vinyl chloride monomer, a 0.2% potassium persulfate aqueous solution previously dissolved was added while controlling the polymerization reaction rate to be constant, and the polymerization rate was about 15%
When the temperature reached 1, the separately dissolved 10% aqueous sodium lauryl sulfate solution was added at a rate of about 80 ml / 10 minutes, and the addition was continued until the total amount of sodium lauryl sulfate added reached 360 g. When the pressure inside the can dropped to 1960 hPa (2 kg / cm ² ) from the saturation pressure of the vinyl chloride monomer at 50 ° C., the reaction was stopped and the unreacted vinyl chloride monomer was recovered to give a vinyl chloride polymer latex. Obtained.

The latex contained sharp monodisperse particles having a particle size of 0.43 μm, which gave the maximum value in the particle size distribution, and had good stability. The particle size distribution of the vinyl chloride polymer particles in the latex was measured using a laser diffraction particle size distribution measuring device (LA-700, manufactured by Horiba, Ltd.). The measurement error is usually 10% or less of the measured value. Further, the instrument was calibrated with polystyrene particles having a standard particle diameter, and the latex was also confirmed with a transmission electron microscope photograph.

(2) Production of vinyl chloride polymer latex 2 Same as "(1) Production of vinyl chloride polymer latex 1" except that the amount of sodium lauryl sulfate used as an initial emulsifier was changed to 8 g. Polymerization was carried out by the above method to obtain a latex containing sharp monodisperse particles having a particle size distribution maximum and a particle size of 1.25 μm.

(3) Production of vinyl chloride polymer latex 3 Same as "(1) Production of vinyl chloride polymer latex 1" except that the amount of sodium lauryl sulfate used as an initial emulsifier was changed to 40 g. Polymerize by the method of
A latex containing sharp monodisperse particles having a particle diameter of 0.11 μm and having a maximum particle size distribution was obtained.

(4) Preparation of polydisperse particle size distribution latex and spray drying Vinyl chloride polymer latex 1, 1 obtained by the above method
2 and 3 were mixed at a ratio of 3/4/3 as a solid content weight to prepare a triple mountain particle size distribution latex (solid content concentration of latex after mixing was 38% by weight). Polyoxyethylene nonyl phenyl ether (average degree of polymerization of ethylene oxide unit: 10) was added to this latex as an adjusting emulsifier at 1% with respect to the solid content, and the mixture was mixed uniformly and dried by a drying device equipped with a two-fluid nozzle. ,
The inlet temperature and the outlet temperature of the device for the dry air flow are set to 18
Spray-drying was performed while maintaining the temperature at 0 ° C. and 65 ° C. to obtain vinyl chloride resin A.

<Example 2 (Production of vinyl chloride resin B)>
The Mitsuyama particle size distribution latex prepared in Example 1 was concentrated to a solid content concentration of 50% using an ultrafiltration device. This latex was spray-dried under the same conditions as in Example 1 above to obtain vinyl chloride resin B.

Example 3 (Production of Vinyl Chloride Resin C) (1) Preparation of Vinyl Chloride Polymer Latex 4 80 kg of deionized water was prepared in Example 1 in a 300 liter capacity polymerization can equipped with a stirrer. A vinyl chloride polymer latex 1 was used as a seed polymer and 4.8 kg of a solid content was charged, followed by deaeration and addition of 75.2 kg of vinyl chloride. After the temperature inside the can was raised to 55 ° C., a redox initiator of hydrogen peroxide-sodium formaldehyde sulfoxylate in a total amount of 0.05% (to vinyl chloride monomer) was continuously added. Further, when the polymerization rate reaches 10% with respect to the total amount of the seed polymer particles and the vinyl chloride monomer, a total amount of 500 g of sodium lauryl sulfate as an emulsifier is 0.08% per hour with respect to the vinyl chloride monomer. Was continuously added as a 10% aqueous solution.

The reaction is stopped when the internal pressure of the can decreases from the saturation pressure of the vinyl chloride monomer at 55 ° C. to 980 hPa (1 kg / cm ² ), and the unreacted vinyl chloride monomer is recovered to recover the vinyl chloride-based heavy polymer. A combined latex 4 was obtained. The vinyl chloride polymer particles in the latex show two maximum values in the particle size distribution, that is, particle diameters of 0.41 μm and 1.30 μm, and in the distribution curve, the two maximums show independent so-called two-peak distribution. It was

(2) Preparation of polydisperse particle size distribution latex and spray drying Vinyl chloride polymer latex 4 obtained by the above method and vinyl chloride polymer latex 3 obtained in Example 1
Was mixed at a ratio of 7/3 as a solid content weight to prepare a triple mountain particle size distribution latex (solid content of latex after mixing was 55% by weight). This latex was used as an emulsifying agent for polyoxyethylene nonylphenyl ether (the average degree of polymerization of ethylene oxide units was 1
0) was added to the solid content in an amount of 1% and mixed uniformly, and a drying device equipped with a two-fluid nozzle was used to adjust the inlet temperature and the outlet temperature of the drying air flow device to 180 ° C. and 65 ° C.
Spray-drying was carried out while maintaining the above to obtain a vinyl chloride resin C.

<Comparative Examples 1 to 3> Vinyl chloride polymer latices 1, 2 and 4 were used, each containing 1% of polyoxyethylene nonylphenyl ether (the average degree of polymerization of ethylene oxide units was 10% based on the solid content in the latices). )
Was added and spray-dried in the same manner as in Example 1 to prepare vinyl chloride resins D, E and F.

<Evaluation Method of Vinyl Chloride Resin> The porosity of the vinyl chloride resin produced as described above was measured, and 40 parts by weight and 50 parts by weight were added to 100 parts by weight of the vinyl chloride resin. Plasticizer (DO
P) was mixed with P) to prepare plastisols, and the B-type viscosities of these plastisols and the outflow amount of seaverses (indicated as “S-type flow” in the table) were measured as follows, and shown in Table 1.

Porosity: Porosimeter (Carlo
-Using Erba, Series 200), vinyl chloride resin 1g, from normal pressure to 196MPa (2000kg / c
Volume of mercury (cc) injected during pressurization to m ² · G)
Expressed as It was determined that the smaller the porosity, the higher the particle packing efficiency. B-type viscosity: The plastisol prepared above was treated at 23 ° C.
After aging for 2 hours in a room of 50% RH, the viscosity was measured in the same room using a B8H type viscometer (# 7 rotor) manufactured by Tokimec Co. at a rotation speed of 50 rpm.

Seaverse outflow rate (S-type flow): The above sol was aged in a room at 23 ° C. and 50% RH for 3 hours, and then, a seaber type viscometer (Burrel-Severs).
Rheometer Model A-120) with a nozzle diameter of 0.323 mm, a nozzle length of 5 cm, and a pressure of 620 kPa (90 psi) (shear rate of about 500-
The sol outflow rate for 5 seconds at 5000 sec ^-1 ) was measured and
It was converted to the outflow rate per 00 seconds. The greater the outflow,
It means that the fluidity in the high shear rate region is good and the viscosity is low.

From the results shown in Table 1, the vinyl chloride resins (A, B and C) obtained by the method of the present invention have a smaller porosity than the resins (D, E and F) of the comparative examples, and It is recognized that the plastisol based on the above has a low viscosity and a large amount of seabass outflow.

[0034]

[Table 1]

[0035]

INDUSTRIAL APPLICABILITY The vinyl chloride resin obtained by the method of the present invention has a small porosity (porosity) and a large apparent specific gravity. Therefore, the volume per weight is small, which is advantageous in terms of transportation cost and stock space. Is. Further, the vinyl chloride resin obtained by the method of the present invention easily becomes a plastisol by mixing with a plasticizer, and the plastisol obtained has a low viscosity, especially in a high shear rate region, and is applied at a high speed. It becomes possible to work. The sol having such characteristics is suitably used as a raw material for building materials such as ceiling materials, wallpaper and floor materials, and as a paint for automobile undercoats, sealants and the like.

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Claims (8)

(57) [Claims] 1. A vinyl chloride polymer having a maximum number frequency of 3 to 6 points in a particle size distribution graph (hereinafter referred to as “particle size distribution”) represented by the relationship between particle size and its number frequency. Latex (hereinafter "polydisperse particle size distribution latex")
Is dried at the device outlet using a two-fluid nozzle.
A method for producing a vinyl chloride-based resin, which comprises spray-drying so that an airflow temperature is 50 to 70 ° C. 2. The method for producing a vinyl chloride resin according to claim 1, wherein the polydisperse particle size distribution latex is prepared by mixing two or more vinyl chloride polymer latexes. 3. The vinyl chloride resin according to claim 2, wherein at least one kind of the vinyl chloride polymer latex to be mixed is produced by seeding polymerization and has a maximum value of 2 points in its particle size distribution. Manufacturing method. 4. In the particle size distribution of the polydisperse particle size distribution latex, the particle size at which the number frequency has a maximum value is 0.05 to 1
The method for producing a vinyl chloride-based resin according to claim 1, 2, or 3, which is in the range of 0 μm. 5. The particle size distribution of a polydisperse particle size distribution latex having a maximum number frequency of 3 points (hereinafter referred to as “three peak particle size distribution latex”).
5. The method for producing a vinyl chloride resin according to any one of 4 above. 6. In the particle size distribution of the Sanyama particle size distribution latex, the particle size at which the number frequency has a maximum value is 0.05 to 3 μm.
The method for producing a vinyl chloride resin according to claim 5, which is in the range of m. 7. In the particle size distribution of the Sanyama particle size distribution latex, the particle size at which the number frequency has a maximum value is 0.
The method for producing a vinyl chloride resin according to claim 5 or 6, wherein each has a center value of 1 µm, 0.4 µm, and 1.3 µm and is within ± 20%. 8. The method for producing a vinyl chloride resin according to any one of claims 1 to 7, wherein the polydisperse particle size distribution latex has a solid content concentration of 30 to 70% by weight.