JPS6144907A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To obtain the titled polymer which can give a low-viscosity plastisol good in heat stability of a molding, by performing emulsion polymerization or fine suspension polymerization of vinyl chloride or its mixture with a copolymerizable monomer in the presence of a specified emulsifier for polymerization. CONSTITUTION:A mixture of vinyl chloride with 0-30wt% copolymerizable monomer (e.g., ethylene) is added to ion-exchanged water containing 0.1-5wt%, based on the monomer, sulfonate compound of formula I (wherein R is a 6-18C alkyl, n is 0-4, X is formula II or -CH2-CH2, M is an alkali metal or ammonium) as a polymerization emulsifier and a water-soluble polymerization catalyst and polymerized at 30-70 deg.C by an emulsion polymerization process or a fine suspension polymerization process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing vinyl chloride polymers. More specifically, when carrying out emulsion polymerization or fine suspension polymerization of vinyl chloride alone or a mixture of vinyl chloride and other ethylenically unsaturated monomers that can be copolymerized with vinyl chloride, specific emulsifiers are used. The present invention relates to a method for producing a vinyl chloride polymer for paste, which provides a plastisol with low viscosity and good thermal stability for molded products.

``Prior art'' Vinyl chloride polymers for paste are usually produced by emulsion polymerization using a water-soluble polymerization catalyst, or by mechanically dispersing vinyl chloride in water using a so-called oil-soluble catalyst that dissolves in vinyl chloride. It is produced by a fine suspension polymerization method in which the polymer is homogenized and then polymerized. At this time, anionic surfactants such as alkyl alcohol sulfate, alkyl sulfonate, and alkylaryl sulfonate are used as emulsifiers. The vinyl chloride polymer for paste obtained in this way has a high initial viscosity, for example, in a paste dispersion such as plastisol or organosol prepared by blending the polymer with a plasticizer, diluent, stabilizer, etc.
Another major drawback is that the sol viscosity increases over time, and even if the initial viscosity is low, the sol viscosity increases after a few days, making molding difficult. Furthermore, molded articles obtained from the polymer also had the disadvantage of poor thermal stability. ``However, for the purpose of reducing sol viscosity, etc., the above-mentioned anionic surfactants, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene block copolymer, sorbitan ester, etc. are added to the latex after polymerization.
Drying has also been carried out by adding an appropriate amount of seven or more nonionic surfactants such as glycerin alkyl esters. However, satisfactory results have not always been obtained.

On the other hand, alkyl sulfate esters are used as emulsifiers when producing vinyl chloride polymers for pastes in order to improve the state of foam cells of vinyl chloride paste sol, high expansion ratio, processing temperature range, and foaming properties with low plasticizer formulations. Alternatively, a method using an alkali metal salt or ammonium salt of an ethoxylated alkyl 'flt acid ester is recommended! ;/-2/A It is known from the Kuda issue. However, the vinyl chloride polymer for paste produced by this method has a large increase in oral sol viscosity and also has poor thermal stability of molded products. Also,
Polyoxyethylene alkylphenol ether sulfate is used as an emulsifier for the purpose of producing or formulating a vinyl chloride resin composition for paste that provides a sol with good defoaming properties and provides molded products with excellent transparency, hygroscopic whitening properties, and electrical resistance. An invention using an alkali metal salt or ammonium salt was published in JP-A-Sho! ;9-1029Q! It is disclosed in Publication No. J. Similar to the above-mentioned ethoxylated alkyl sulfate, the vinyl chloride resin composition for paste using the emulsifier also has a large oral change in viscosity and poor thermal stability. In order to solve the above-mentioned drawbacks of conventional products, the present inventors have developed a vinyl chloride plastisol that has a significantly low initial viscosity and a small oral change in viscosity, and can improve the thermal stability of molded products. As a result of intensive studies to obtain a system polymer, it was discovered that the object of the present invention could be achieved by emulsion polymerization or fine suspension polymerization of vinyl chloride using a specific emulsifier, and the present invention was completed. .

That is, an object of the present invention is to provide a method for producing a vinyl chloride polymer that can provide a plastisol with a significantly low initial viscosity and a small oral change in viscosity, and can improve the thermal stability of molded articles. .

``Structure of the Invention'' The gist of the present invention is to obtain a vinyl chloride polymer by emulsion polymerization or fine suspension polymerization of vinyl chloride alone or a mixture of vinyl chloride and a monomer copolymerizable therewith. In manufacturing, the general formula [
I] (wherein R is an alkyl group having 6 to 1 g of carbon atoms, n
is an integer of O-da, X is -CH2-9H-OH2- or -C! H2-C!
M represents an alkali metal atom or an ammonium group, respectively. ) A method for producing a vinyl chloride polymer, characterized by using an alkylphenyl ether sulfonate compound represented by:

The present invention will be described in detail.

The method of the present invention comprises vinyl chloride or vinyl chloride and monomers copolymerizable therewith, such as ethylene, propylene, n-
Olefins such as butene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl stearate, unsaturated acids such as acrylic acid, methacrylic acid, itaconic acid or their alcohol esters, methyl vinyl ether, ethyl vinyl ether, octyl vinyl ether, lauryl A mixture of seven or more monomers such as vinyl ether such as vinyl ether, maleic acid, alkaline fumaric acid, anhydride or ester thereof, aromatic vinyl compound, unsaturated nitrile, etc. is subjected to emulsion polymerization or fine suspension polymerization. Monomers that can be copolymerized with vinyl chloride are not limited to those mentioned above, and the proportion of copolymerization with vinyl chloride is 30% by weight or less, preferably 20% by weight or less. Ru.

The method of the present invention is characterized in that an alkylphenyl ether sulfonate compound represented by the general formula CI) is used as an emulsifier during polymerization. R in the formula of the sulfonate compound represented by the general formula [I] is an alkyl group having 6 to 1 carbon atoms;
'ji;'h is preferably a straight chain, and is usually located at a position para to the oxygen atom bonded to the benzene ring.

n is an integer of 0-<2, and is particularly preferably in the range of / to 3. The sulfonate compounds include, for example, alkali metal salts or ammonium salts of alkylphenylucose sulfoethyl ether, alkali metal salts or ammonium salts of alkylphenyl-3-sulfo-2-hydroxypropyl ether, alkylphenylpolyoxyethylene- Examples include alkali metal salts or ammonium salts of course sulfoethyl ether, and alkali metal salts or ammonium salts of alkylphenylpolyoxyethylene-3-sulfo-2-hydroxypropyl ether. The amount of the emulsifier used is desirably in the range of 0.1 to 3% by weight, preferably 0.3 to 3% by weight, particularly 0.3 to 1% by weight, based on the monomers charged. In addition, some of these emulsifiers include general anionic surfactants such as alkyl alcohol sulfate ester salts, alkyl sulfonates, alkylaryl sulfonates, dialkyl sulfosuccinates, polyoxyethylene alkyl ethers, General nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymer, sorbitan ester, and glycerin alkyl ester can be used instead. It is also possible to add only higher fatty acids, higher alcohols, etc. as emulsification aids.

To carry out emulsion polymerization according to the method of the present invention, for example, ion-exchanged water, an emulsifier, and a water-soluble polymerization catalyst are placed in a polymerization container, and after vacuum degassing or nitrogen substitution is repeated as necessary, vinyl chloride or vinyl chloride is added thereto. Polymerizable monomers are added to initiate polymerization. The polymerization temperature is not particularly limited, but is determined by the desired average degree of polymerization; for example, to obtain a high degree of polymerization, a low temperature is used, while to obtain a low degree of polymerization, a high temperature is used. implement. Generally 30~? (It is carried out in a temperature range of 7° C.) The degree of polymerization may be controlled using a degree of polymerization regulator such as halogenated hydrocarbons and mercaptans.

The emulsion polymerization in the method of the present invention may also be carried out in the presence of a latex containing a seed polymer previously produced by an emulsion polymerization method, so-called seeded polymerization. In this polymerization method, for example, demineralized water and vinyl chloride polymer seed latex are charged into a polymerization container, and after repeated vacuum degassing or nitrogen substitution as necessary, vinyl chloride or vinyl chloride and a monomer copolymerizable therewith are prepared. This is carried out by adding a mixture of 1 and 2 and continuously adding a water-soluble polymerization catalyst at an appropriate temperature. The emulsifier represented by the general formula [I] may be present in the polymerization system before the start of polymerization, but since the purpose is to grow the polymer seeds, the emulsifier is continuously added after the polymerization rate reaches approximately i0%. It is preferable to add

To carry out the fine suspension polymerization according to the method of the invention, demineralized water,
An emulsifier and an oil-soluble polymerization catalyst are placed in a polymerization container, and the polymerization system is degassed under reduced pressure or purged with nitrogen gas as necessary. Vinyl chloride or a mixture of vinyl chloride and other monomers is then added and mechanically removed. The monomer such as vinyl chloride is homogenized to be dispersed into the desired fine oil droplets by thorough stirring), and the polymerization is carried out at a predetermined polymerization temperature depending on the desired degree of polymerization. In the fine suspension polymerization method, as in the case of emulsion seeding polymerization, seeding polymerization may be performed in the presence of a seed polymer prepared in advance.

The latex obtained by emulsion polymerization or fine suspension polymerization as described above has excellent stability, so it may be spray-dried as is, or if necessary, sodium alkyl sulfate or sodium alkylaryl sulfonate may be added. , an anionic surfactant such as sodium fatty acid, or a nonionic surfactant such as polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, sorbitan alkyl ester, etc. may be added, followed by spray drying. Of course, the obtained latex may be used as it is without spray drying depending on the purpose.

"Effects of the Invention" The novel emulsifier used in the method of the present invention has the advantage that it has good mechanical dispersion stability and almost no adhesion of the polymer to the can wall when producing vinyl chloride polymers. The obtained vinyl chloride polymer can be used to prepare a sol by a conventionally known method, and the viscosity of the plastisol is initially low and changes little over time. In addition, this plastisol has excellent fluidity due to its low viscosity not only in the low shear rate range but also in the high shear rate range, and this effect is particularly desired in the field of plastisol processing using coating methods. It is a nature. For example, a low sol viscosity in the low shear rate range facilitates handling of the paste sol, e.g. feeding, filtration, deacidification, and a low sol viscosity in the high shear rate range allows for high application speeds, such as for flooring, wall coverings, etc. This is a favorable property for manufacturing. Furthermore, the vinyl chloride polymer produced by the method of the present invention can provide molded articles with good thermal stability. Therefore, in addition to being used as a vinyl chloride polymer for pastes, the polymer can also be used for powder molding such as Engel process, high 2-7" process, Hayashi process, fluidized dip coating, electrostatic powder coating, and rotational molding. Since it has good thermal stability as a vinyl chloride polymer, it can be used as a gelling temperature improver for vinyl chloride resins produced by suspension polymerization.

"Examples" Next, the method of the present invention will be explained in more detail with reference to Examples, but the method of the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Note that "parts" and "ti" described in the examples are based on weight.

The formulation of plastisol used in the test was as follows.

Vinyl chloride polymer 100 parts Dioctyl phthalate 60 parts Oa-Zn stabilizer
Part 3 (MARK 8O-j4t, Adeca Argus Chemical H) Each test method is as follows.

B-type viscosity (centiboise) Measured using a BE-type viscometer (manufactured by Tokyo Keiki Seisakusho) YT6T rotor at the rotational speed of J Orpm at -23°C. However, a formulation other than the above-mentioned formulation without the stabilizer was used.

Thermal stability/? A sheet having a thickness of 100 mm thick was gelled at 795 DEG C. for 5 minutes and was taken out every j minutes, and the total time until it turned dark brown was measured.

Example / Seed emulsion polymerization method Ion-exchanged water ROI with 2θθ volume and heavy metal species equipped with a stirrer
cg, vinyl chloride polymer seed latex with average particle size O, Sμ (emulsifier: p-octylphenyldioxyethylene-3-sulfo-2-hydroxyglobyl ether sodium, catalyst: potassium persulfate-sodium bisulfite system used) After charging 11 kg of polymer seeds as polymer seeds, it was degassed, 7 kg of vinyl chloride monomer was added, and the temperature was raised to 50°C. A redox catalyst of hydrogen oxide-sodium formaldehyde sulfoxylate was added continuously. Furthermore, from the time when the polymerization rate reached 70% of the total amount of polymer seeds and vinyl chloride until the end of polymerization, an emulsifier shown in Table 1 was added to the vinyl chloride monomer every hour at an aqueous solution concentration of about ♂. It was weighted continuously at a ratio of O0θ. The total addition plan for emulsifier is θ, s qb (vs. monomer).

From the saturation pressure of vinyl chloride at a polymerization pressure of 50°C/k
When g/cA drops, polymerization is stopped and unreacted monomers are collected.

The average particle diameter of the latex obtained in each case was θ and rμ, and the stability of the latex was very good. The obtained latex was spray-dried and then pulverized to obtain a salted vinyl polymer.

Plastisol prepared using this polymer was measured for sol viscosity change over time and thermal stability using the above test method. The results are shown in Table 1.

Comparative Example: A cyclized vinyl polymer was produced in the same manner as in Example f11/, using lauryl sulfate as an emulsifier during the production of vinyl chloride polymer seed latex and using sodium dodecyl sulfate as an emulsifier during seeding polymerization. However, the viscosity and thermal stability of the plastisol were investigated in the same manner as in the Examples and are also listed in Table 1.

Examples 3 and 3 Seeding Fine Suspension Polymerization Method In a premixing tank of 12,004 volumes equipped with a stirrer, 100 parts of ion-exchanged water and 9 parts lauroyl peroxide (hereinafter referred to as I, P) were added.
O)≦oog1 Sodium lauryl sulfate aoog, lauryl alcohol-〇OI were added, then the premix tank was degassed, thokg of vinyl chloride monomer was added, and 3jCK was maintained without stirring. After stirring uniformly, the mixture was dispersed to a desired droplet size using a pore-forming machine, and a stirrer, which had been previously degassed, was leaked. The mixture was transferred to a zoot reactor.

After the transfer of the dispersion liquid was completed, the temperature of the reaction tank was raised and polymerization was carried out by a known method. The emulsifying pressure of the emulsifying machine is 2 j Okg.
/cylfr- The average particle size of the seed particles in the obtained latex was 0. It became μμ.

Next, for the purpose of producing a vinyl chloride polymer with an average particle size of 1μ, the seed 1 combined particles were held at 60°C for a period of time to remove the excess amount of LPO, and the LPO contained in the particles was removed. Adjusted the amount of @.

Seed polymerization was performed using the seed polymer prepared as described above.

Add ion-exchanged water to a -200 mL polymerization tank equipped with a stirrer.
Okys Average particle diameter 0.4t with LPO amount adjusted above
μ seed latex is used as a seed polymer, and after adding 60% sodium bicarbonate op, it is degassed and made into a vinyl chloride monomark! After the temperature was raised to SO° C., a 0.1% aqueous solution of sodium bisulfite, which had been dissolved in advance, was continuously added little by little to the polymerization tank to initiate polymerization. After starting the continuous addition of sodium bisulfite, the reaction was maintained at a constant rate. Furthermore, from the time when the polymerization rate differs from io% of the total amount of the seed polymer and vinyl chloride until the end of the polymerization, as an emulsifier, the emulsifier shown in Table 2 is used as an aqueous solution of about r% to the vinyl chloride monomer. It was added continuously at a rate of o, org, per hour. The total amount of emulsifier added was 0.3 molar relative to vinyl chloride.

From the saturation pressure of vinyl chloride at a polymerization pressure of 50°C/k
When the amount of g/cr/l decreased, polymerization was stopped and unreacted monomers were collected. Even if the emulsifier was different, the average particle diameter of the obtained latex was between /, 0 and /, 0, and the stability of the latex was extremely good, and a vinyl chloride polymer was obtained. Plastisol prepared using this polymer was tested for changes in sol viscosity and thermal stability using the above test methods.

The results are shown in Table 2.

Comparative Example Using the seed polymer latex produced in Korg Example 2,
Seed polymerization was carried out in the same manner as in Example using the various emulsifiers listed in Table 1 to produce a vinyl chloride polymer t-at.

The viscosity and thermal stability of plastisols of these polymers were measured and listed in Table S1. Examples and Comparative Examples! In the method of Example 1, when performing 1 batch of sowing,
Example λ except that 5% vinyl acetate monomer (relative to Tanishi monomer) was charged in addition to vinyl chloride monomer as a monomer.
Polymerization was carried out in exactly the same manner. The average particle diameter of the obtained latex was 80 μm, and the stability of the latex was shown in Table 3.

Other than using sodium dodecyl sulfate as an emulsifier,
Comparative Example j was prepared in the same manner as in Example 1.

Claims (4)

[Claims] (1) When producing a vinyl chloride polymer by emulsion polymerization or fine suspension polymerization of vinyl chloride alone or a mixture of vinyl chloride and a monomer copolymerizable with it, general formula [I] is used as an emulsifier for polymerization. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[I] (In the formula, R is an alkyl group with 6 to 18 carbon atoms, n is 0
An integer of ~4, x is ▲a mathematical formula, chemical formula, table, etc.▼or -CH_
A group represented by 2-CH_2-, M represents an alkali metal atom or an ammonium group, respectively. ) A method for producing a vinyl chloride polymer, which comprises using an alkylphenyl ether sulfonate compound represented by: (2) The method for producing a vinyl chloride polymer according to claim 1, wherein a sulfonate compound of an alkylphenyl ether is sequentially added during polymerization. (3) The chloride according to claim 1, wherein the sulfonate compound represented by the general formula [I] is an alkali metal salt or ammonium salt of p-octylphenyldioxyethylene-3-sulfo-2-hydroxypropyl ether. A method for producing a vinyl polymer. (4) The vinyl chloride polymer according to claim 1, wherein the sulfonate compound represented by the general formula [I] is an alkali metal salt or ammonium salt of p-octylphenyldioxyethylene-2-sulfoethyl ether. manufacturing method.