JPH06107733A - Vinyl chloride-based copolymer and its production - Google Patents

Abstract

PURPOSE:To obtain the subject copolymer good in heat resistance and thermal stability without causing colored fish eye by polymerizing vinyl chloride in an aqueous medium to a specific conversion rate, adding an N-substituted maleimide dissolved in vinyl chloride thereto and polymerizing the monomers. CONSTITUTION:Vinyl chloride is radically copolymerized with an N-substituted maleimide expressed by the formula [X is 1-30C (substituted)aliphatic or aromaric group; R and R' are H, F, Cl, Br, cyano or <=3C alkyl] in an aqueous medium. In the process, the vinyl chloride monomer is initially polymerized in the presence of a partially saponified polyvinyl alcohol having 70-95% saponification degree and 700-3000 polymerization degree and a partially saponified polyvinyl alcohol having 35-55mol.% saponification degree and 300-600 polymerization degree until the polymerization conversion efficiency attains 30-60wt.%. The compound, expressed by the formula and dissolved in vinyl chloride is then added into the polymerization system and copolymerized to afford the objective vinyl chloride-based copolymer, having >=0.2ml/g porosity and composed of 50-99wt.% vinyl chloride unit and 1-50wt.% N-substituted maleimide unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate, a sheet, a film, a shaped product, a pipe, a blow molded product and the like, and a vinyl chloride copolymer excellent in heat distortion resistance and heat stability and a method for producing the same. Is.

[0002]

2. Description of the Related Art As one of the methods for improving the heat distortion resistance of polyvinyl chloride, for example, a method of copolymerizing vinyl chloride and N-arylmaleimide as disclosed in JP-B-41-9551, or Japanese Patent Publication No.44-124
A method of copolymerizing vinyl chloride and N-substituted maleimide as disclosed in Japanese Patent No. 33 has been proposed.

However, since the resin obtained by this method contains particles having poor porosity, the thermal stability during processing is extremely poor, and thermal decomposition of the resin, remarkable coloring, or deterioration of mechanical properties are observed. Not suitable for practical use.

As a method for improving the processing heat stability of this vinyl chloride-N-substituted maleimide copolymer, for example, the bulk specific gravity and the average particle size as described in JP-A-63-145351 are used. Limiting methods have been proposed.
By these methods, it is possible to enhance the processing fluidity and thermal stability of the resin composition.

However, a resin composition having a bulk specific gravity of 0.3 or more and an average particle size of 60 to 200 μm as described in JP-A-63-145351 cannot be said to have sufficient thermal stability. Moreover, this method does not provide a fundamental solution to the particles with poor porosity that cause red-colored fish eyes.

[0006]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and its object is to obtain heat resistance,
It is intended to provide a heat-resistant vinyl chloride-based copolymer having excellent heat stability and a method for producing the same.

[0007]

That is, the present invention has a porosity of 0.2 ml / g or more and a vinyl chloride unit of 50 to 99.
When radical-copolymerizing a copolymer composed of 1% to 50% by weight of N-substituted maleimide unit and vinyl chloride and an N-substituted maleimide in an aqueous medium, first, a vinyl chloride monomer having a polymerization conversion ratio of 30 is used. The present invention relates to a method for producing a vinyl chloride-based copolymer, which comprises polymerizing until reaching 60% by weight, and then adding an N-substituted maleimide dissolved in vinyl chloride into the polymerization system for copolymerization. .

The present invention will be described in more detail below.

The N-substituted maleimide used in the present invention has the following general formula (1):

[0010]

[Chemical 3]

(In the formula, X is a substituted or unsubstituted chain or cyclic aliphatic group or aromatic group having 1 to 30 carbon atoms, R and R ′ may be the same or different, and hydrogen, An atom of fluorine, chlorine or bromine, a cyano group or an alkyl group having 3 or less carbon atoms), and specific examples include N- (o, m, p) -methylphenylmaleimide N -(O, m, p) -methoxyphenylmaleimide N- (o, m, p) -chlorophenylmaleimide N-phenylmaleimide N-methylmaleimide N-n-propylmaleimide N-isopropylmaleimide N-n-butylmaleimide N- sec-Butyl maleimide N-tert-butyl maleimide N-octyl maleimide N-cyclohexyl maleimide N-2-methyl-cyclohexyl Reimido N-4- methyl - and cyclohexyl maleimide N- triphenylmethyl maleimide.

The N-substituted maleimide unit in the copolymer is 1
˜50 wt%, preferably 5-45 wt%. When the content of the N-substituted maleimide in the copolymer is less than 1% by weight, the heat resistance is not improved so much, and when it exceeds 50% by weight, the heat resistance is improved but the fluidity during processing is lowered. Considering satisfying both heat resistance and processability 5-4
5% by weight is particularly preferred.

Next, the porosity of this copolymer will be described. According to the knowledge of the present inventors, this copolymer is
It is known that when a large amount of non-porous particles are contained and this resin is processed, a large amount of red-colored fish eyes are generated. As a result of intensive studies by the present inventors to solve this problem, the porosity of the copolymer was 0.2 ml.
It has been found that it is necessary to make the amount above 0.3 / g, preferably above 0.3 ml / g. When the porosity is less than 0.2 ml / g, a large amount of red-colored fish eyes are generated, but when the porosity is 0.2 ml / g or more, the red-colored fish eyes decrease, and particularly when it is 0.3 ml / g or more, the red-colored fish eyes are colored. Not only does it eliminate fish eyes, but it also has powder properties that are excellent in gelling properties.

By adding a stabilizer to the copolymer of the present invention, a resin composition having excellent thermal stability can be obtained.
Examples of the stabilizer include dibutyltin laurate, dibutyltin dilaurate, dibutyltin malate, dibutyltin dimaleate, dibutyltin stearate, dibutyltin distearate, dibutyltin mercaptide, dibutyltin lauryl mercaptide, dibutyltin-S, S-bis. -(Isooctyl-mercaptoacetate), dibutyltin bis-isooctylthioglycolate, dioctyltin maleate polymer, dibutyltin mercaptopropionate and other organotin stabilizers; tribasic lead sulfate, dibasic lead phthalate , Lead-based stabilizers such as dibasic lead phosphite; metal salts such as stearic acid or lauric acid such as calcium, barium, zinc, cadmium, lead; antimony-based stabilizers such as antimony mercaptocarboxylic acid salts or ester salts; Diethyl phosphite, dib Ruhosufaito, phosphite stabilizers such as tricresyl phosphite; Barium -
Examples thereof include complex stabilizers such as zinc, calcium-zinc, and cadmium-barium-zinc, and epoxidized compounds. These stabilizers may be used alone or in combination of two or more. The amount of stabilizer is 1 to 1 with respect to 100 parts by weight of the resin.
It is 0 part by weight, preferably 1 to 5 parts by weight.

Further, a lubricant may be added to the copolymer of the present invention for the purpose of preventing burning of the resin during processing, prevention of sticking during processing, and the like. Examples of the lubricant include paraffin wax and polyethylene wax. Hydrocarbon waxes such as; stearic acid, oleic acid, montanic acid, and other higher fatty acids; calcium stearate, magnesium stearate, and other metal soaps; stearamide, oleylamide, and other fatty acid amides; butyl stearate, methyl hydroxy stearate Fatty acid esters such as rate; higher alcohols such as lauryl alcohol and stearyl alcohol; partial esters of fatty acids and polyhydric alcohols such as stearic acid monoglyceride and oleic acid monoglyceride. These lubricants may be used alone or in combination of two or more. The amount of lubricant is 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the resin.

In addition, ethylene-ethyl acrylate copolymer, polybutadiene-styrene-methyl methacrylate graft copolymer (MBS), polybutadiene-styrene-methyl methacrylate-acrylonitrile graft copolymer may be added to the copolymer of the present invention as required. Polymer (MB
Processing aids such as AS), or antistatic agents, antioxidants, flame retardants, colorants, fillers, ultraviolet absorbers, modifiers, etc. may be added.

Next, a method for producing the above copolymer will be described. When this copolymer is produced by the conventional method, a large amount of non-porous particles are generated, and the generation tendency is due to the N in the copolymer.
-It becomes remarkable as the amount of substituted maleimide increases. or,
The porosity of the particles is less than 0.2. As a result of diligent studies by the present inventors, it was found that these non-porous particles were already formed in the initial stage of polymerization. That is, this copolymer has a problem that N-substituted maleimide is present at the initial stage of the polymerization, and the polymerization conversion rate at which particles are formed is 30 to 30%.
Polymerize up to 60% by weight with vinyl chloride alone, then
It is important to add N-substituted maleimide and polymerize. Hereinafter, the method for producing this copolymer will be specifically described.

In carrying out the present invention, a suspension polymerization method or an emulsion polymerization method generally used can be applied as it is.

Among them, the suspension polymerization method is specifically carried out by the following method. First, deionized water, a dispersion stabilizer, and a polymerization initiator are put in a jacketed pressure resistant polymerization vessel equipped with a stirrer, and the pressure is reduced. Then, vinyl chloride is injected under pressure and heated with stirring to start polymerization.

Next, when the conversion of polymerization reaches 30 to 60% by weight or more, a predetermined amount of N-substituted maleimide dissolved in vinyl chloride is added to the polymerization system in a preliminary dissolution tank. The addition method may be batch addition, divided addition, or continuous addition. However, in the case of divided or continuous addition, the addition of the N-substituted maleimide is preferably completed until the polymerization conversion rate reaches 80% by weight.

Polymerization temperature is usually 20 to 90 ° C., polymerization time is 1
~ 40 hours. After the polymerization is completed, the unreacted monomer is recovered, and the slurry is taken out and dehydrated and dried to obtain a heat-resistant vinyl chloride copolymer having a porosity of 0.2 ml / g or more.

Next, the dispersion stabilizer of this copolymer will be described. In order to obtain the above-mentioned copolymer, it is necessary to increase the porosity of the polyvinyl chloride homopolymer (hereinafter abbreviated as PVC) formed at the initial stage of the polymerization. The following two types of partially saponified polyvinyl alcohol are preferably used as the dispersion stabilizer used.

(I) Partially saponified polyvinyl alcohol having a saponification degree of 70 to 95 mol% and a polymerization degree of 700 to 3000. (ii) Saponification degree of 35 to 55 mol% and a polymerization degree of 300 to 6
No. 00 partially saponified polyvinyl alcohol The degree of saponification of the partially saponified polyvinyl alcohol of the component (i) exceeds 95 mol%, or the degree of polymerization is 3000.
When it exceeds, the porosity of PVC formed in the initial stage of the polymerization is reduced and the porosity of the resulting copolymer is also reduced. or,
When the saponification degree is less than 70 mol% or the polymerization degree is less than 700, the suspension system becomes unstable and the obtained particles become coarse. Therefore, the saponification degree is 70 to 95 mol% and the polymerization degree is 700 to 3
000 is preferable. Further, the amount of component (i) used is preferably 0.01 to 0.2 parts by weight with respect to 100 parts by weight of the total charged vinyl chloride.

When the degree of saponification of the partially saponified polyvinyl alcohol of the component (ii) exceeds 55 mol% or the degree of polymerization exceeds 600, the porosity of PVC formed in the initial stage of the polymerization is decreased, and the resulting copolymer is obtained. Porosity also decreases. If the saponification degree is less than 35 mol% or the polymerization degree is less than 300, the suspension system becomes unstable and the obtained particles become coarse. Therefore, the saponification degree is from 35 to 55 mol% and the polymerization degree is from 300 to 700. Is preferred. The amount of the component (ii) used is 0.001 with respect to 100 parts by weight of the total charged vinyl chloride.
˜0.2 parts by weight is preferred.

In addition, a dispersion stabilizer such as a methyl cellulose derivative or sodium polyacrylate may be used in combination with the partially saponified polyvinyl alcohol of the components (i) and (ii).

As the polymerization initiator, for example, peroxides such as diisopropyl peroxydicarbonate, tert-butyl peroxyneodecanate and benzoyl peroxide, 2,2′-azobisisobutyronitrile, 2 , 2'-azobis-2,4-dimethylvaleronitrile and other azo compounds are used.
Combinations of more than one species can be used.

At the time of the above-mentioned polymerization, another monomer copolymerizable with vinyl chloride or a polymer which is graft-polymerizable with vinyl chloride may be added if necessary and polymerized.

For example, the monomers include vinyl esters such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl laurate, vinyl stearate; olefins such as ethylene, propylene, isobutylene; isobutyl vinyl ether, phenyl vinyl ether. , Alkyl or aryl vinyl ethers such as octyl vinyl ether; halogenated olefins such as vinylidene chloride, vinyl fluoride, allyl chloride, vinyl bromide; ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2 -Acrylic acid and methacrylic acid esters such as ethylhexyl methacrylate, stearyl methacrylate; acrylic acid, methacrylic acid, crotonic acid, acrylonitrile,
Examples thereof include acrylic derivatives such as maleic anhydride and itaconic anhydride.

As a polymer which can be graft-copolymerized with vinyl chloride, an ethylene-vinyl acetate copolymer (EV
A), ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, polybutadiene-styrene-methyl methacrylate copolymer (MBS), polybutadiene-acrylonitrile- (α-methyl) styrene copolymer (ABS), polybutyl Examples thereof include acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer, crosslinked acrylic rubber and the like.

[0030]

The present invention will be further described with reference to the following examples, which should not be construed as limiting the present invention.

Example 1 Pure water was placed in a stainless steel autoclave having an internal volume of 10 liters.
0 l, saponification degree 80 mol%, 3.0 g of partially saponified polyvinyl alcohol having a polymerization degree of 1800, 2.0 g of partially saponified polyvinyl alcohol having a saponification degree of 40 mol% and a polymerization degree of 400, 2,2′-azobis-2 , 4-dimethylvaleronitrile (4.0 g) was added and the pressure was reduced, and then 1.4 kg of vinyl chloride monomer was charged. Then, the internal volume 3l
N-cyclohexylmaleimide (hereinafter,
After charging 252.0 g of N-CHMI), the pressure was reduced and 400.0 g of vinyl chloride monomer was charged.
The inside of this preliminary dissolution tank was heated to 30 ° C. while stirring.

Next, the above 10 l autoclave was heated to 55 ° C. to start the polymerization, and when the conversion of polymerization reached 50%, the N-CHMI solution in the preliminary dissolution tank was added to continue the polymerization. After the polymerization was completed, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

Example 2 Example 3 was repeated except that N-phenylmaleimide (hereinafter abbreviated as N-PhMI) was used as the N-substituted maleimide.

After the polymerization was completed, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

Example 3 The procedure of Example 1 was repeated, except that the N-CHMI solution was added at a polymerization conversion rate of 30%.

After completion of the polymerization, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

Example 4 Example 4 was repeated except that the N-CHMI solution was dividedly added at a polymerization conversion rate of 30%. Split addition is NC
HMI (5.3 g) and vinyl chloride monomer (8.3 g) were added once to the polymerization system at 10-minute intervals over 48 times.

After the polymerization was completed, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

Comparative Example 1 Pure water was placed in a stainless steel autoclave having an internal volume of 10 l.
0 l, saponification degree 80 mol%, 3.0 g of partially saponified polyvinyl alcohol having a polymerization degree of 1800, 2.0 g of partially saponified polyvinyl alcohol having a saponification degree of 40 mol% and a polymerization degree of 400, 2,2′-azobis-2 After charging 4.0 g of 4-dimethylvaleronitrile and 252.0 g of N-CHMI, 1.8 kg of vinyl chloride monomer was charged under reduced pressure. Then, the mixture was heated to 55 ° C. with stirring to carry out polymerization.

After the polymerization was completed, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

Comparative Example 2 The procedure of Comparative Example 1 was repeated except that N-PhMI was used as the N-substituted maleimide.

After the polymerization was completed, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

Comparative Example 3 The procedure of Example 1 was repeated, except that the N-CHMI solution was added at a polymerization conversion rate of 20%.

After the polymerization was completed, unreacted vinyl chloride monomer was recovered, and the slurry was taken out from the autoclave and dehydrated and dried. As a result, a polymer was obtained at a polymerization conversion rate of about 85%.

The vinyl chloride copolymers obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated and measured as follows, and the results are shown in Table 1.

(1) Heat-resistant deformation temperature: 3.0 parts by weight of dibutyltin maleate-based stabilizer and 100 parts by weight of dibutyltin laurate-based stabilizer per 100 parts by weight of polymer.
5 parts by weight, 0.5 parts by weight of a phosphite chelator, 0.5 parts by weight of a fatty acid ester lubricant, and 0.5 parts by weight of a higher alcohol lubricant were added. This compounded composition was kneaded with the two rolls having a surface temperature of 170 ° C. for 5 minutes after the composition was wrapped around the roll, and the obtained roll sheet was further subjected to 185 ° C.
Samples for evaluation were produced by press molding for 10 minutes.

For the evaluation, the temperature at the time when needle insertion into the sample was measured using a Vicat softening temperature measuring device described in JIS K-6740.

(2) Thermal stability of roll sheet A composition prepared in the same manner as in (1) above was used for the surface temperature 17
After kneading with two rolls at 0 ° C., the composition was wound around the roll, and kneading was continued for 5 minutes, and after 10 minutes, the colorability of the sheet was visually evaluated. ○ No coloration △ Some coloration × Coloring

(3) Evaluation of Red-Colored Fish Eyes 2.5 parts by weight of dibutyltin malate stabilizer and 0.5 parts of polyethylene wax lubricant per 100 parts by weight of polymer.
Parts by weight, 0.5 parts by weight of a higher alcohol lubricant,
The product was molded with a C-type channel mold at 160 ° C. and a φ50 mm extruder, and the reddish fish eyes of the product were visually evaluated according to the following criteria. ○ No red-colored fish eyes △ Some red-colored fish eyes × Many red-colored fish eyes

(4) Porosity measurement The porosity of the polymer was measured by the mercury porosimetry method.

[0051]

[Table 1]

[0052]

As is apparent from the above description, according to the present invention, vinyl chloride having a porosity of 0.2 ml / g or more is used.
An N-substituted maleimide copolymer is obtained, and in processing the resin, by adding a stabilizer and a lubricant, generation of red-colored fisheyes is improved, and as a result, heat resistance,
It is possible to obtain a resin composition having excellent thermal stability. The molded product is preferably used for applications such as plates, sheets, films, odd-shaped products and pipes.

Claims (3)

[Claims] 1. A vinyl chloride-based co-polymer having a porosity of 0.2 ml / g or more and comprising 50 to 99% by weight of vinyl chloride units and 1 to 50% by weight of an N-substituted maleimide unit represented by the following general formula (1). Coalescing. [Chemical 1] (In the formula, X is a substituted or unsubstituted chain or cyclic aliphatic group or aromatic group having 1 to 30 carbon atoms, R and R ′ may be the same or different, and hydrogen, fluorine, chlorine Alternatively, it is a bromine atom, a cyano group or an alkyl group having 3 or less carbon atoms.) 2. When radically copolymerizing vinyl chloride and an N-substituted maleimide represented by the following general formula (1) in an aqueous medium, first, a vinyl chloride monomer having a polymerization conversion ratio of 30 is used.
A method for producing a vinyl chloride-based copolymer, which comprises polymerizing until it reaches 60% by weight, and then adding an N-substituted maleimide dissolved in vinyl chloride into the polymerization system for copolymerization. [Chemical 2] 3. A partially saponified polyvinyl alcohol having (i) a saponification degree of 70 to 95 mol% and a polymerization degree of 700 to 3000, and (ii) a saponification degree of 35 to 55 mol% and a polymerization degree of 300.
The method for producing a vinyl chloride-based copolymer according to claim 2, wherein the polymerization is carried out in the presence of ˜600 partially saponified polyvinyl alcohol.