JPS6129603B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vinyl chloride resin with an improved particle shape that is excellent in molding processing through suspension polymerization of a vinyl chloride monomer or a vinyl chloride monomer and a monomer mixture copolymerizable therewith. be. Conventionally, when vinyl chloride monomer or vinyl chloride monomer and a monomer mixture copolymerizable therewith are suspended in an aqueous medium in the presence of an oil-soluble polymerization initiator, the suspending agent is , water-soluble polymeric substances such as partially saponified polyvinyl alcohol and cellulose derivatives such as methylcellulose are used. Furthermore, various organic peroxides and azo compounds are used as polymerization initiators. However, the vinyl chloride resin produced by this method has the disadvantage of poor porosity and poor moldability. As a method for improving such drawbacks, for example, a method of using a surfactant in combination with a known dispersant is disclosed in Japanese Patent Publications No. 31-5740, Japanese Patent Publication No. 2996-1972, Japanese Patent Publication No. 25412-1978, and Japanese Patent Publication No. 49-83785. No., Tokukaisho
No. 49-125489, Special Publication No. 49-11259, Japanese Patent Publication No. 11259
50-58157, British Patent No. 1378875, etc., and the method of using a water-soluble initiator in combination with an oil-soluble initiator is described in Japanese Patent Publication No. 45-2189, Japanese Patent Publication No. 46-12473, and Japanese Patent Publication No. 48-7229. , Methods using modified or modified dispersants are described in Japanese Patent Publication Nos. 1972-21892, 1972-25412, 1972-23831, 1972-53275, 1972-115587, Japanese Patent Application Publication No. 52-5886, Tokuko Sho
Methods such as No. 54-27873 and Japanese Unexamined Patent Publication No. 54-24989 have been proposed and have been found to be effective to some extent. However, these known methods are not only insufficiently effective, but also have drawbacks in granulation, wastewater contamination, scale adhesion, etc. during polymerization, and the products have poor thermal stability, sheet transparency, etc. It had some disadvantages. In addition, the resin produced by the above method generally has a smooth surface shape of the resin particles, although it depends on the type of dispersant and polymerization initiator used during polymerization. Compounds containing such additives have poor fluidity, and the resin and compound have problems in pneumatic transportation and in hoppers of molding machines such as extruders. Furthermore, when a stainless steel production reactor is used, the decrease in pH caused by dehydrochlorination causes the stainless steel to corrode, causing pinholes and cracks on the walls of the reactor. For the purpose of preventing this, it is known to add various alkaline compounds such as sodium tripolyphosphate, sodium bicarbonate, sodium pyrophosphate, caustic soda, ammonia, and ammonium salts during polymerization as pH regulators. In such a case, the surface shape of the produced resin tends to be particularly smooth, and the disadvantage is that the powder fluidity of the resin and the fluidity of the compound are poor. In view of the current situation, the present inventors conducted intensive research and found that when vinyl chloride is suspended polymerized in an aqueous medium, a part of the organic peroxide, which is a polymerization initiator, is treated with a specific organic nitrogen-containing compound. By using this method, we can create a vinyl chloride resin with improved particle shape that has excellent processability and does not have any of the above drawbacks even when polymerized without changing the conventional polymerization method or using a known PH regulator. The present invention was completed based on the discovery that the present invention can be obtained. The vinyl chloride resin with improved particle shape according to the present application has a unique unevenness on the resin surface, which can be observed at 10 to 100 times magnification using a scanning electron microscope. Although the reason for this formation is not clear, it is thought that the surface active effect of a specific organic nitrogen-containing compound causes unevenness on the surface of the resulting resin. These resins with improved particle shapes have a fast plasticizer absorption rate, are easy to work with in compounds used for hard and soft formulations, and are easy to use when building a plasticizer.
It has many characteristics such as fewer eyes and excellent thermal stability. The organic peroxide used as a polymerization initiator in the present invention is not particularly limited, and any organic peroxide can be used as long as it is used as a polymerization initiator for suspension polymerization of vinyl chloride in an aqueous medium. The organic peroxides include benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, and tert-butyl peroxide. Examples include pivalate, dimethoxyisopropyl peroxydicarbonate, and acetylcyclohexylsulfonyl peroxide. In addition, as a polymerization initiator, the above-mentioned organic peroxide alone or a combination of two or more kinds of organic peroxides, the above-mentioned organic peroxide and an azo polymerization initiator in combination, and the above-mentioned organic peroxide and a water-soluble polymerization initiator are used. A combination of agents may also be used. Specific organic nitrogen-containing compounds include compounds having an amino group bonded to a benzene ring and heterocyclic compounds having nitrogen as a foreign atom. Compounds having an amino group bonded to a benzene ring are primary, secondary, and tertiary amines having at least one aromatic ring, such as aminobenzene, dimethylaniline, benzalaniline, α-naphthylamine, phenyl- β-naphthylamine, 1-amine-2-methylanthraquinone, aminoresorcinol, amino-4-methylquinoline, aminobenzonitrile, aminobenzophenone, aminopropylbenzene, aminofluorene, N-N'-diphenyl-p-phenylenediamine , N'-phenyl-N-isopropyl-p-phenylenediamine and the like, but are not limited to these. Examples of heterocyclic compounds having nitrogen as a foreign atom include aminopyridine, pyridazine, pyrimidine,
Pyrazine, phthalazine, quinazoline, quinoxaline, 1,2,3-triazine, pyridine, pyrroline, lutidine, pyriindigo, 2-(2-pyridyl)pyrrole, pyridone, paraoxazine, dioxazine dye, 6-ethoxy-2,2,4 -Trimethyl-1,2 dihydroquinoline, 2-mercaptobenzomelimidazole, 2,3-benzopyrrole, dibenzopyrrole, 2-phenylindole, naphthotriazole stilbenesulfonate, 2(2'hydroxy-5methylphenyl)benzotriazole , 2(2-hydroxy-3′,5′-
ditertiarybutyl phenyl)benzotriazole, 2,5-bis(5'-tertiarybutylbenzoxazolyl(2))thiophene, 2H-1,2
-thiazine, 2-mercaptobenzothiazole,
Examples include, but are not limited to, 2,2' dithiobis-benzothiazole, phenothiazine diphenylthiourea, and the like. In addition, when using nitrogen-containing organic compounds,
It is not necessary to use only one type, and two or more types of these may be used in combination. The amount of the specific nitrogen-containing organic compound used to treat the organic peroxide used in the present invention depends on the molecular weight of the compound, but it is 0.2 weight percent or less based on the organic peroxide and 2 ppm or less based on the vinyl chloride monomer. is sufficient. If the amount exceeds 0.2 weight percent, the polymerization reaction is inhibited, which not only reduces productivity but also impairs the thermal stability of the product and the color tone of the sheet. Further, it is not preferable because it causes disadvantages such as coarse particle size and significant scale adhesion. Although the minimum amount used is not particularly limited, in order to fully exhibit the effect, the amount of the specific nitrogen-containing organic compound used is preferably 100 ppm or more based on the organic peroxide. The specific organic nitrogen-containing compound used in the present invention reacts quickly with the organic peroxide at room temperature, so the treatment conditions are not particularly limited. However, if heat generation is significant during treatment, the organic oxide may be cooled to below room temperature. However, it is preferable to react gradually. In the present invention, copolymerizable monomers include α-olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate,
Vinyl ethers such as methyl vinyl ether and cetyl vinyl ether; acrylic acid or methacrylic acid such as acrylic acid and methyl methacrylate; vinyl halides other than vinyl chloride such as vinyl bromide and vinyl fluoride; aromas such as styrene and α-styrene; Examples include group vinyl, maleic acid, fumaric acid and its anhydride, acrylonitrile, vinylidene chloride, and the like. Note that there is a method of coating or adding a compound similar to the specific organic nitrogen-containing compound used in the present invention to the polymerization vessel to prevent scale adhesion to the polymerization wall, stirring blade, etc., as described in Japanese Patent Publication No. 45-30343. No., Special Publication No. 46-47535, Special Publication No. 48-29871, etc., but these methods are aimed at preventing scale adhesion, so the amount applied (or added) to the equipment must be large. The intended effect was not observed. In the case of the present invention, the amount of the specific organic nitrogen-containing compound added is extremely small, 2 ppm or less when converted to vinyl chloride monomer, and it also reacts with organic peroxides, so it is difficult to scale. No effect on preventing adhesion was observed. From the above facts, it can be said that the present invention is different from the invention of the earlier application in terms of the amount added, the purpose of use, and the effect. Next, the present invention will be described in detail with reference to Examples, but these are not intended to limit the scope of the present invention. Each physical property value in the examples was measured according to the following formulation and method. Average degree of polymerization: JIS K-6721 Apparent specific gravity: JIS K-6741 Particle size distribution: JIS Z-8801 Microwave particle shape: Resin at magnification of 100 to 10,000 times using a scanning electron microscope MSM4C-101 manufactured by Hitachi-Kyoto The shape of the particles on the surface was determined, and those with unique unevenness on the resin surface were marked as ○, those with a smooth resin surface without unevenness were marked as ×, and those in between were marked as △. Plasticizer absorption rate: Added 50 parts by weight of plasticizer (DOP) using a planetary mixer, measured at a jacket temperature of 80°C, and expressed as the time (minutes) required until the compound dries up and the stirring torque suddenly decreases. . Rigid blendability test: Put 2.5 kg of resin and 50 gr of lead stearate into a small Henschel mixer (No. 9) and stir and mix at a rotation speed of 3600 rpm. Blending is carried out until the temperature of the compound rises to 130℃, but if the flow of the compound temporarily stops during this process, it is ×, and if the flow of the compound does not stop but is extremely bad, it is △, the fluidity of the compound is If there was almost no change during the entire process and the condition was good, it was judged as ○. Fluidity of soft compound: Using a 400 gr compound whose plasticizer absorption rate has been measured as a sample, a stainless steel funnel (diameter 150φ x inclination angle 60° x
Drop from foot length 700mm x foot diameter 20φ),
○ for items that fall in less than 15 seconds, 16 seconds to 30
Those that required more than a second were judged as ×. Fishery Eye: 100 parts by weight of resin, DOP50
parts by weight, 3 parts by weight of tribasic lead sulfate, 1 part by weight of lead stearate, and an appropriate amount of ultramarine.
Knead at 150°C for 7 minutes to create a roll sheet with a wall thickness of 0.1 mm. The number of transparent particles with a diameter of 100 μ or more existing in this 50 cm ² roll sheet was defined as the fish eye number. Thermal stability: 100 parts by weight of resin and 2 parts by weight of Ba/Zn stabilizer are blended and roll kneaded at 170°C for 3 minutes to create a sheet with a wall thickness of 0.7 mm. This rolled sheet was heated in a gear type oven at 180°C, and the time (minutes) for the sheet to blacken was evaluated. Example 1 500 kg of vinyl chloride monomer, 1000 kg of pure water, 150 g of partially saponified polyvinyl alcohol, and 200 g of methyl cellulose were placed in a stainless steel polymerization vessel with an internal volume of 2.5 m ³ .
Sodium pyrophosphate 50g as gr and PH regulator
The mixture was stirred at 200 rpm using two stages of 400φ three-blade paddle blades and two ring buttfuls, and polymerization was carried out at 58° C. until the polymerization pressure reached 6.0 Kg/cm ² . At this time, the following polymerization initiators were used. 1 200g diisopropyl peroxydicarbonate treated with 300ppm α-aminopyridine
Tertiary-butyl peroxyneodecanate treated with r2 400ppm 2-aminofluorene
230 gr 3 200 gr tert-butyl peroxypivalate treated with 500 ppm of 0-aminopropylbenzene and 150 gr untreated di-2-ethylhexyl peroxydicarbonate 4 2 (2'-hydroxy-3',5'-di tertiary) Butylphenyl)benzotriazole
300gr dimethoxyisopropyl peroxydicarbonate treated with 350ppm 5 N-phenyl-β-naphthylamine 300ppm
100 gr of benzoyl peroxide treated with
and 150 gr of untreated 2,2'-azobis-2,4-dimethylvaleronitrile The results of this polymerization were as shown in Table 1 for the examples. Comparative Example 1 In Comparative Experiment No. 6, 200 gr of diisopropyl peroxydicarbonate as a polymerization initiator was used as it was without being treated with an organic nitrogen-containing compound. Comparative Example Experiment No. 7 did not use an organic peroxide as a polymerization initiator, but instead used an azo initiator 2,2'-azobis-
Only 150g of 2,4-dimethylvaleronitrile was used, and aminopyridine was used as an initiator treatment agent.
500ppm was added. Other polymerization conditions were exactly the same as in Example-1.

[Table] As shown in Table 1, all particles that were polymerized using a polymerization initiator treated with an organic nitrogen-containing compound that reacts with the organic peroxide had a unique uneven surface. However, resins with good plasticizer absorption properties, fluidity of hard and soft compounds, and fixability can be obtained. Furthermore, the particle size distribution, bulk specific gravity, thermal stability, scale adhesion, etc. of the same resin are no different from those using an untreated polymerization initiator. In addition, when only an azo polymerization initiator is used,
Even when mixed with a nitrogen-containing compound, there was no reaction at all, and the resin was not improved at all. Example 2 The organic peroxide used as a polymerization initiator was
Ethylhexyl peroxydicarbonate 200g
r, and the organic compound to be treated is 1-amino-2-
Polymerization was carried out under exactly the same polymerization conditions as in Example 1, except that methylanthraquinone was used and the amount used was changed as shown in Table 2. The polymerization results were as shown in Table 2.

【table】

[Table] As shown in Table 2, when the amount of the treatment agent for the polymerization initiator is 100 ppm or less relative to the polymerization initiator, the surface shape of the particles is slightly improved, but the effect is insufficient. As shown in Comparative Example 2-2, when the amount of the processing agent exceeds 2000 ppm, the polymerization reaction is significantly inhibited, and not only the reaction rate decreases, but also the viscosity becomes rough. This results in disadvantages such as an increase in the amount of scale adhesion due to poor thermal stability. Therefore, the appropriate amount of the organic nitrogen-containing compound used to treat the polymerization initiator is 0.01 to 0.2 weight percent (preferably 0.02 to 0.08 weight percent) based on the organic peroxide used as the polymerization initiator. In addition, considering cases where there is a large amount of polymerization initiator, such as when a polymerization initiator is used in combination, the amount of treatment agent should be 2ppm of the PVC monomer.
The following is appropriate. Example 3 The organic compound treated with the polymerization initiator was 500 ppm of 2-phenylindole, and the polymerization initiator was tertiary butyl peroxypivalate (Experiment No.
14, 17), dimethoxyisopropyl peroxydicarbonate (Experiment No. 15, 18), diisopropyl peroxydicarbonate (Experiment No. 16, 19), and 20g of diisopropyl peroxydicarbonate, and the polymerization temperature was 67°C, respectively. , 58℃ and 53
Polymerization was carried out under exactly the same polymerization conditions as in Example-1, except that the temperature was changed to ℃. The polymerization results were as shown in Table 3.

【table】

[Table] Comparative Example 3 Example except that the polymerization initiator was not treated with 2-phenylindole in advance and was used as it was.
Polymerization was carried out under exactly the same polymerization conditions as in Example 3. The polymerization results were as shown in Comparative Example in Table 3.
As shown in Table 3, the effect of the treatment agent on the polymerization initiator is not significantly affected by the type of organic peroxide used as the polymerization initiator and the polymerization temperature. It may also be an initiator.

Claims (1)

[Claims] 1. As a polymerization initiator in suspension polymerization of a vinyl chloride monomer alone or a mixture of a monomer copolymerizable with vinyl chloride in an aqueous medium containing a suspending agent and a PH adjuster. A particle shape characterized by using an organic peroxide partially treated with an organic nitrogen-containing compound selected from a compound having an amino group bonded to a benzene ring and a heterocyclic compound having nitrogen as a foreign atom. A method for producing vinyl chloride resin with an improved method. 2. The amount of the organic nitrogen-containing compound treated is 0.01 to 0.2 percent by weight based on the amount of polymerization initiator used in polymerization, and the amount is based on the total amount of monomers used.
The manufacturing method according to claim 1, wherein the content is 2 ppm or less. 3. In the method according to claim 1, the amount of the organic nitrogen-containing compound treated is 0.01 to 0.2 percent by weight based on the amount of polymerization initiator used in polymerization,
and a method for producing a vinyl chloride resin with improved particle shape, characterized in that the amount is 2 ppm or less based on the total amount of monomers used. 4. Particles in the method according to claim 1, wherein the organic nitrogen-containing compound is at least one selected from primary, secondary, and tertiary amines having at least one aromatic ring. A method for producing vinyl chloride resin with improved shape. 5. In the method according to claim 1, the nitrogen-containing organic compound is azo, azine, pyridine, urea, oxazine, hydroquinoline hydrazine, benzimidazole, indole, triazole,
A method for producing a vinyl chloride resin with improved particle shape, characterized in that the resin is an organic compound having at least one group selected from thiourea and thiazine.