JP2001106709A - Production of vinyl chloride-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a vinyl chloride-based resin by graft-copolymerizing vinyl chloride to an acrylic polymer obtained by an emulsion polymerization, by which the vinyl chloride-based resin can be obtained in a state scarcely generating particles without deteriorating the quality of the vinyl chloride-based resin and without generating the particles such as SS in waste fluids. SOLUTION: This method for producing a vinyl chloride-based resin comprises graft-copolymerizing vinyl chloride to an acrylic polymer. Therein, a reducing agent is added to the acrylic polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a vinyl chloride resin.

[0002]

2. Description of the Related Art Conventionally, vinyl chloride resins have been widely used as materials having excellent properties such as mechanical strength, weather resistance and chemical resistance. However, since the impact resistance is inferior, various proposals have been made on a method for improving the impact resistance. For example, Japanese Patent Application Laid-Open No. 60-258513 discloses a method for producing a vinyl chloride resin having excellent impact resistance and weather resistance by graft copolymerizing vinyl chloride to a crosslinked acrylic copolymer. It has been disclosed.

However, in the polymerization method in which vinyl chloride is graft-copolymerized onto the acrylic copolymer, the polymerization form in the above polymerization mode is lower than that in the ordinary polymerization method of vinyl chloride resin. Since suspension polymerization is performed in the presence of a polymerization initiator or an emulsifier, a large amount of a dispersant and an antifoaming agent are required.Furthermore, since polymerization is performed in the presence of an acrylic copolymer, graft copolymerization is required. The waste liquid from which the polymer has been removed later contains a large amount of suspending substances, soluble substances, and the like, and has remarkable white turbidity. This suspending substance (S
S) is subjected to flocking treatment each time and becomes industrial waste. In addition, in the above-mentioned polymerization mode, the particle size tends to vary.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, the present invention relates to a method of graft copolymerizing vinyl chloride by suspension polymerization on an acrylic polymer obtained by emulsion polymerization. It is an object of the present invention to provide a method for producing a vinyl chloride resin which does not lower the quality of the resin and generates less fine particles such as SS in waste liquid with less generation of fine particles.

[0005]

As a cause of the generation of the suspended substance (SS) which deteriorates the turbidity of the polymerization waste liquid of the above-mentioned vinyl chloride resin, the water-soluble start-up remaining in the acrylic copolymer is considered. The reaction between the dispersant and the dispersant added during the graft polymerization is considered.

[0006] Therefore, when vinyl chloride is polymerized on the acrylic copolymer, the initiator remaining in the acrylic polymer is decomposed before the graft copolymerization, and then the acrylic polymer is reacted with vinyl chloride. The present inventors have found that the use of copolymerization significantly reduces the amount of suspended substances in the waste liquid and has no adverse effects such as slowing down the polymerization reaction and deteriorating various physical properties of the product.

The production method according to claim 1 (Invention 1) is a method for producing a vinyl chloride resin by graft copolymerizing an acrylic polymer with vinyl chloride or a vinyl monomer containing vinyl chloride as a main component. The acrylic copolymer is characterized in that a reducing agent is added.

[0008] The production method according to claim 2 (invention 2) is characterized in that, in the invention 1, the graft copolymerization is carried out at 60 to 80 ° C.

The manufacturing method according to the third aspect is the invention 1 or 2
Wherein the content of the acrylic polymer in the vinyl chloride resin is 1 to 30% by weight.

The acrylic polymer used in the present invention is a polymer obtained by polymerizing an acrylic monomer containing an alkyl (meth) acrylate as a main component. ) In addition to the acrylate, other monomers copolymerizable with the alkyl (meth) acrylate and a polyfunctional monomer may be contained.

The alkyl (meth) acrylate is not particularly restricted but includes, for example, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate and isobutyl (meth) acrylate. Acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate , N-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, Include allyl (meth) acrylate, these may be used alone, or two or more kinds may be used in combination.

The other monomer copolymerizable with the alkyl (meth) acrylate is not particularly restricted but includes, for example, 2-hydroxyethyl (meth) acrylate,
Polar group-containing vinyl monomers such as hydroxypropyl (meth) acrylate and 2-acryloyloxyethyl phthalic acid; aromatic vinyl monomers such as styrene, α-methylstyrene and vinyl toluene; unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile And vinyl esters such as vinyl acetate vinyl propionate. These may be used alone or in combination of two or more.

The proportion of the alkyl (meth) acrylate in the acrylic monomer is preferably at least 75% by weight. If it is less than 75% by weight, sufficient impact resistance cannot be obtained.

The polyfunctional monomer is used for crosslinking the acrylic polymer to prevent coalescence of the acrylic polymer particles and to improve the impact resistance of the obtained vinyl chloride resin.

The polyfunctional monomer is not particularly restricted but includes, for example, ethylene glycol di (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, 1,6-
Hexanediol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate,
Multifunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate and dipentaerythritol hexa (meth) acrylate; And a divinyl compound such as divinylbenzene and butadiene. These may be used alone or two or more of them may be used in combination.

The ratio of the polyfunctional monomer in the acrylic polymer is 100
It is preferably 0.1 to 10 parts by weight based on part by weight. 0.
If the amount is less than 1 part by weight, the cross-linking density is low, so that the impact strength of the molded article is reduced. More preferably, it is 0.2 to 8 parts by weight.

The acrylic polymer is obtained by, for example, emulsion-polymerizing an acrylic monomer having the above-mentioned alkyl (meth) acrylate as a main component in the presence of an emulsifying dispersant and a polymerization initiator.

The emulsifying and dispersing agent is not particularly limited.
For example, anionic surfactants, nonionic surfactants, partially saponified polyvinyl alcohol, cellulose dispersants, gelatin and the like are listed. In particular, commercially available anionic surfactants include polyoxyethylene nonyl phenyl ether Sulfate and the like.

The polymerization initiator is not particularly limited.
For example, water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate, and hydrogen peroxide, organic peroxides such as benzoyl peroxide and lauroyl peroxide, and azo polymerization initiators such as azobisisobutyronitrile. Is mentioned.

In the above emulsion polymerization, if necessary,
A pH adjuster, an antioxidant and the like may be added.

The method of the emulsion polymerization is not particularly limited, and examples thereof include a batch polymerization method, a monomer dropping method, and an emulsion dropping method. In the batch polymerization method, for example, pure water, an emulsifying dispersant, a polymerization initiator, and a mixed monomer composed of the acrylic monomer and the polyfunctional monomer are collectively added into a jacketed polymerization reactor,
After sufficient emulsification by stirring under a nitrogen stream, the temperature in the reactor is increased by a jacket to start the polymerization reaction.

In the monomer dropping method, for example, pure water, an emulsifying dispersant, and a polymerization initiator are charged into a jacketed polymerization reactor, and the inside of the reactor is heated under a nitrogen stream pressure. A polymerization reaction is started by dropping a predetermined amount of the mixed monomer comprising the above-mentioned polyfunctional monomer.

In the emulsion dropping method, for example, a mixed monomer composed of the acrylic monomer and the polyfunctional monomer, an emulsifying dispersant and pure water are stirred to prepare an emulsifying monomer in advance, and then a polymerization reactor with a jacket is prepared. Pure water and a polymerization initiator are put into the reactor, and the temperature of the reactor is raised under a nitrogen gas flow and a pressurized condition.

In the present invention, the reducing agent added to the acrylic polymer is not particularly limited, and examples thereof include oxides such as sodium sulfite, sodium hydrogen sulfite, and sulfur dioxide; and ferrous chloride and stannous chloride. Examples thereof include salts of metals having a low valence, and sodium bisulfite is preferable. The amount of the reducing agent added is 10 to 100 parts by weight of the initiator added during the polymerization of the acrylic polymer.
To 200 parts by weight, more preferably 50 to 10 parts by weight.
0 parts by weight.

The method of adding the reducing agent is not particularly limited, and may be, for example, at the end of the polymerization reaction of the acrylic polymer, immediately before the graft reaction of vinyl chloride onto the acrylic polymer. Considering this, it is preferable to add a reducing agent after the polymerization is completed and before cooling. Further, in order to efficiently decompose the remaining polymerization initiator, it is preferable to heat at a temperature close to the polymerization temperature for about one hour. That is,
It is most preferable to add a reducing agent after the completion of the polymerization reaction of the acrylic polymer and carry out the treatment for 1 hour as it is.
Considering the decomposition temperature of a general polymerization initiator, it is preferable to perform the treatment at a temperature of 80 ° C. or more for 1 hour or more.

The proportion of the acrylic polymer in the vinyl chloride resin is preferably 1 to 30% by weight.
If the amount is less than 1 part by weight, the effect of improving impact resistance is low, and if it exceeds 30 parts by weight, mechanical strength such as tensile strength and bending strength decreases. More preferably, it is 4 to 20% by weight.

The vinyl chloride resin of the present invention can be obtained by graft copolymerizing vinyl chloride with the above acrylic polymer by suspension polymerization.

The above suspension polymerization is carried out in the presence of a dispersant and an oil-soluble polymerization initiator. The dispersant is added to improve the dispersion stability of the acrylic polymer and efficiently perform graft copolymerization.Examples include methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol, and partial ken. Polyvinyl alcohol, gelatin, polyvinyl pyrrolidone, starch, maleic anhydride-styrene copolymer, and the like. These may be used alone or in combination of two or more.

As the above-mentioned polymerization initiator, an oil-soluble initiator generally used for suspension polymerization of vinyl chloride is preferably used. As such a polymerization initiator, for example, di-2
-Ethylhexylperoxydicarbonate, diethoxyethylperoxydicarbonate, α-cumylperoxyneodecanate, t-butylperoxyneodecanate, t-butylperoxypivalate, t-butylperoxy-3 , 5,5-trimethylhexanoe
Acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, lauroyl peroxide,
2,2′-azobisisobutyronitrile and the like,
These may be used alone or in combination of two or more.

In the present invention, the above acrylic copolymer obtained by the emulsion polymerization method may be graft-copolymerized in an emulsified state as it is. It is industrially advantageous to carry out graft copolymerization. The flocculant is not particularly limited, and examples thereof include sodium chloride, calcium chloride, potassium chloride, magnesium chloride, and aluminum chloride.

As a specific method for producing the vinyl chloride resin of the present invention, for example, water, the acrylic polymer, the dispersant, and the oil-soluble polymerization initiator are charged into a pressure-resistant reaction vessel equipped with a stirrer and a jacket. Further, if necessary, a coagulant, a polymerization degree regulator and the like are added. After that, the air in the reactor was discharged by a vacuum pump, vinyl chloride was added with stirring, and other vinyl monomers were added as necessary.The graft copolymerization was started by raising the temperature in the reactor with a jacket. Can be The above graft copolymerization reaction is an exothermic reaction, and the temperature in the reactor is adjusted by a jacket as necessary. After completion of the reaction, unreacted vinyl chloride is removed out of the system to form a slurry, which is then dehydrated and dried to obtain a vinyl chloride resin.

[0032]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

(Example 1) [Production of acrylic polymer] In a reactor equipped with a stirrer and a reflux condenser, a predetermined amount of n-butyl acrylate, pure water, an emulsifying dispersant (Hytenol) shown in Table 1 were added. N-08,
Daiichi Kogyo Co., Ltd.), ammonium persulfate ("APS" in the table)
) And trimethylolpropane triacrylate (denoted as “TMPTA” in the table), and after the atmosphere in the reactor was replaced with nitrogen, the temperature was raised to 65 ° C., and the mixture was reacted while stirring for 5 hours. 30% by weight of an acrylic polymer latex (shown as "acrylic latex" in the table) was obtained. After the completion of the reaction, 0.05 parts of sodium sulfite (50% by weight based on the amount of the charged initiator) was added, and the mixture was stirred at 65 ° C. for 1 hour and then cooled.

[Production of Vinyl Chloride Resin] In a pressure-resistant reaction vessel equipped with a stirrer and a jacket, predetermined amounts of charged water, calcium chloride, partially saponified polyvinyl alcohol (Kurarepovar L-8, 3 by Kuraray Co., Ltd.
% Aqueous solution (shown as "PVA aqueous solution" in the table), hydroxypropyl methylcellulose (Metroze 60SH)
5, a 3% by weight aqueous solution (produced by Shin-Etsu Chemical Co., Ltd.) (labeled as "cellulose" in the table) is added, and the above-mentioned acrylic polymer latex and t-butyl peroxy neodecanoate (hereinafter referred to as "BPOND") are added. After that, the air in the polymerization reactor was removed by a vacuum pump, a predetermined amount of vinyl chloride shown in Table 1 was added, and the mixture was stirred for 30 minutes to be uniformly mixed.
At ℃, the polymerization was started. After the start of polymerization, the internal pressure of the polymerization vessel is 7 kg
/ Cm 2, the polymerization was stopped, and an unfoaming agent (Toray Silicone SH5510, manufactured by Toray Industries, Inc.) was added under pressure to remove unreacted vinyl chloride. Then, the resulting slurry polymer was centrifuged. By dehydration, it was separated into a polymerization waste liquid and a cake-like polymer. The cake-like polymer was further dried to obtain a vinyl chloride resin.

Example 2 A vinyl chloride resin was obtained in the same manner as in Example 1 except that the amount of sodium sulfite was changed to 0.1 part in the polymerization of the acrylic polymer.

Example 3 A vinyl chloride resin was obtained in the same manner as in Example 1 except that the temperature during the addition of sodium sulfite was changed to 90 ° C. in the polymerization of the acrylic copolymer.

Example 4 A vinyl chloride resin was obtained in the same manner as in Example 1 except that the holding time when adding sodium sulfite was changed to 3 hours in the polymerization of the acrylic copolymer.

(Example 5) The polymerization temperature at the time of grafting was 80
A vinyl chloride-based resin was obtained in the same manner as in Example 1 except that the initiator was changed to t-butylperoxy-2-ethylhexananoate (indicated as "BPOEH" in the table).

(Example 6) The polymerization temperature during grafting was 64
° C, the content of the acrylic copolymer to 20%, the initiator to 3,5,5-trimethylhexananoyl peroxide (“TMHPO” in the table), and the amount of calcium chloride to 1
A vinyl chloride resin was obtained in the same manner as in Example 1 except that the amount was changed to 17 parts by weight.

Comparative Example 1 A vinyl chloride resin was obtained in the same manner as in Example 1 except that the reduction treatment of sodium sulfite and the like was not performed in the polymerization of the acrylic copolymer.

Comparative Example 2 A vinyl chloride resin was obtained in the same manner as in Example 1 except that the temperature at the time of adding sodium sulfite was changed to 40 ° C. in the polymerization of the acrylic copolymer.

(Comparative Example 3) A vinyl chloride resin was obtained in the same manner as in Example 1 except that in the polymerization of the acrylic copolymer, the holding time when sodium sulfite was added was changed to 0.1 hour.

Comparative Example 4 A vinyl chloride resin was obtained in the same manner as in Example 5 except that the reduction treatment of sodium sulfite and the like was not performed in the polymerization of the acrylic copolymer.

Comparative Example 5 A vinyl chloride resin was obtained in the same manner as in Example 6, except that the reduction treatment of sodium sulfite and the like was not performed in the polymerization of the acrylic copolymer.

[Evaluation] The above Examples 1 to 6 and Comparative Examples 1 to
The following physical properties of the vinyl chloride resin obtained in 5 were evaluated. Table 2 shows the results. (Bulk specific gravity) It measured based on JISK6721. (Particle size distribution) According to JIS Z8801, # 60,
Each of the sieves # 100 and # 200 was sieved, and the sieve pass amount (% by weight) was measured. (Polymerization degree) The viscosity-average polymerization degree was measured in accordance with JIS K 6721, and defined as the polymerization degree. (PH of Polymerization Waste Liquid) According to JIS Z 8802, the pH value of the polymerization waste liquid after the filtration was measured. (COD value of polymerization waste liquid) The COD value of the polymerization waste liquid after the filtration was measured in accordance with JIS K0102. (SS in polymerization waste liquid) The SS value of the polymerization waste liquid after centrifugation was measured by the method listed in Appendix 8 of the Notification of Environment Agency No. 59 (Environmental Standard for Water Pollution).

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

According to the method for producing a vinyl chloride resin of the present invention, when a vinyl chloride resin is produced by graft copolymerizing vinyl chloride with an acrylic polymer, a reducing agent is added to the acrylic copolymer. Therefore, it is possible to obtain a vinyl chloride resin having a low SS value of the polymerization waste liquid and little generation of fine particles.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomokazu Moriya 4560 Kaiseicho, Shinnanyo-shi, Yamaguchi Prefecture Tokuyama Sekisui Industry Co., Ltd. F-term (reference) 4J011 AA05 AA10 AB02 BA04 DA03 JA01 PA06 PA09 PA69 PB40 PC02 PC07 4J026 AA45 AC31 BA10 CA05 CA06 DA04 DA07 DB03 DB08 DB12 DB15 DB32 GA02 GA06

Claims (3)

[Claims] When a vinyl chloride resin is produced by graft copolymerizing vinyl chloride or a vinyl monomer containing vinyl chloride as a main component with an acrylic polymer, a reducing agent is added to the acrylic polymer. A method for producing a vinyl chloride resin. 2. The method for producing a vinyl chloride resin according to claim 1, wherein the graft copolymerization is performed at 60 to 80 ° C. 3. The method for producing a vinyl chloride resin according to claim 1, wherein the content of the acrylic polymer in the vinyl chloride resin is 1 to 30% by weight.