JPH05155910A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To diminish scale deposition on the inside of a polymerization vessel without impairing the capacity for cooling the whole polymerization equipment and without causing impaired polymer qualities such as, in particular, initial discoloration, reduced heat stability, emission of an offensive odor due to an increase in the amount of an initiator residue or decomposition product, and an increase in extractable content. CONSTITUTION:Vinyl chloride monomer or a vinyl monomer mixture consisting mainly of the same is suspension-polymerized in an aqueous medium using an liposoluble polymerization initiator. The initiator is a combination of 3- hydroxy-1,1-dimethylbutyl peroxyneoheptanoate with a compound which has neither a benzene ring nor an alkoxy group in the molecular structure and has a 10-hr half-life temp. of 30-50 deg.C in benzene at a concentration of 0.1mol/l.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride polymer, and more particularly to a method for producing a vinyl chloride polymer capable of obtaining a high quality vinyl chloride polymer with high productivity. is there.

[0002]

2. Description of the Related Art Vinyl chloride polymers are usually produced by suspension polymerization of a vinyl chloride monomer or a mixture of vinyl monomers mainly containing vinyl chloride monomer in an aqueous medium using an oil-soluble polymerization initiator. To be done. At this time, the oil-soluble polymerization initiator used, depending on the type, the exothermic pattern of the polymerization reaction, the polymerization time, the productivity, the scale adhesion at the time of polymerization, the initial colorability of the polymer, thermal stability, odor , Has a great influence on quality characteristics such as extraction resistance.

On the other hand, in recent years, the polymerization time has been shortened for the purpose of improving the productivity of vinyl chloride polymers. To increase the amount of polymerization initiator added for this purpose,
In addition to restrictions due to insufficient cooling capacity of the overall polymerization equipment, effects on polymer quality, especially initial colorability and deterioration of thermal stability,
There was a problem that an offensive odor was generated due to an increase in the residue of the polymerization initiator or a decomposition product, an increase in the extraction component, etc., and the amount of scale attached in the polymerization vessel was increased.

[0004]

SUMMARY OF THE INVENTION Accordingly, the object of the present invention is to limit the cooling capacity of the polymerization apparatus in general and to affect the quality of the polymer, especially the initial colorability and the deterioration of thermal stability.
PROBLEM TO BE SOLVED: To provide a method for producing a vinyl chloride-based polymer, which does not encounter disadvantages such as generation of offensive odor due to increase of polymerization initiator residue or decomposition product, increase of extraction component, etc., and further can suppress scale adhesion amount in a polymerization vessel. There is

[0005]

That is, the method for producing a vinyl chloride polymer according to the present invention is a method for producing an oil-soluble polymer of a vinyl chloride monomer or a mixture of vinyl monomers mainly containing the vinyl chloride monomer in an aqueous medium. When the suspension polymerization is carried out using an initiator, the temperature of the 10-hour half-life of (A) benzene in (A) benzene as a polymerization initiator is 30 to 50 ° C., and a benzene ring or an alkoxy group is contained in the structure. Compounds without (B)
It is characterized by being used in combination with 3-hydroxy-1,1-dimethylbutylperoxyneoheptanoate.

The present invention will be described in more detail below. The oil-soluble polymerization initiator as the component A used in the method of the present invention has a 10-hour half-life temperature of 30 to 50 ° C. in 0.1 mol / L in benzene and has a benzene ring or an alkoxy group in its structure. Not a compound.

[0007] Here, if the temperature of the 10-hour half-life is less than 30 ° C, the sustained activity is decreased, and if it is 50 ° C or more, a large amount of a polymerization initiator is required. The quality characteristics such as sex are deteriorated. In addition, in the case of a compound having a benzene ring in this structure, UV was obtained by an extraction test.
Since the absorption peak appears, its application to the fields of medical treatment and food is limited, and the adhesion of scale becomes extremely large in the compound having an alkoxy group.

The oil-soluble polymerization initiator as the component A is
More specifically, it is composed of one or a combination of two or more selected from the diacyl, perester or percarbonate compounds represented by the following general formula.

1) Diacyl compound:

[Chemical 1] (Here, R ¹ and R ² are respectively a substituted or unsubstituted n-alkyl group having 1 to 15 carbon atoms, a sec-alkyl group, tert.
-Alkyl group or cyclic alkyl group) This compound includes isobutyryl peroxide (0.1% in benzene).
Temperature for 10-hour half-life in mol / L [the same applies below]: 33
℃) is illustrated.

2) Perester compound:

[Chemical 2] (Here, R ³ and R ⁴ are respectively a substituted or unsubstituted n-alkyl group having 1 to 20 carbon atoms, sec-alkyl group, tert
-Alkyl group or cyclic alkyl group) to this compound t-hexyl peroxy neodecanoate (45
℃), t-butyl peroxyneodecanoate (46
℃), t-hexyl peroxy neohexanoate (49
° C) 2,4,4-trimethylpentylperoxy-2
-Neodecanoate (36 ° C), 1-cyclohexyl-1
-Methylethyl peroxy neodecanoate (41 ° C) and the like are exemplified.

3) Percarbonate compound:

[Chemical 3] (Wherein R ¹ and R ² are the same as above) This compound contains diisopropyl peroxydicarbonate (41 ° C.),
Di-n-propyl peroxydicarbonate (41 ° C),
Di-myristyl peroxydicarbonate (41 ° C), di-2-ethylhexyl peroxydicarbonate (43
℃) etc. are illustrated.

Among these, particularly the perester type t-
Hexylperoxy neodecanoate, t-butylperoxy neodecanoate, t-hexylperoxy neohexanoate, 2,4,4-trimethylpentylperoxy-2-neodecanoate, 1-cyclohexyl-
1-Methylethyl peroxy neodecanoate and the like are preferable.

On the other hand, the oil-soluble polymerization initiator as the component B has 3-hydroxy-
1,1-dimethylbutyl peroxy heptanoate _{[CH 3 -CH (OH) -CH} 2 -C (CH 3) 2 -OO-CO-tC 6 H 13] is used.

The blending ratios and the amounts of these two components A and B are slightly different depending on the reaction conditions, but generally, the weight ratio of A / B is preferably 9/1 to 1/9. Initial adhesion and thermal stability are not improved, and if B is more than this, scale adhesion cannot be suppressed.

Further, the total amount thereof is preferably 0.06 to 0.5% by weight of the vinyl monomer in the production of vinyl chloride homopolymer having an average degree of polymerization of 1,000. These both polymerization initiators also have a polymerization temperature of 35 to 60 ° C. and a polymerization time of 2 to
Optimal results are obtained when used under reaction conditions of 6 hours.

The addition of both of these polymerization initiators to the polymerization system is
It may be diluted with a solvent or dispersed in water to form an emulsion or suspension, and then carried out together with water and / or a suspending agent or after these are charged, and a reactor after charging a vinyl chloride monomer. You may make it press-fit inside.

As the vinyl chloride-based monomer used in the method of the present invention, in addition to vinyl chloride alone, a mixture of vinyl chloride-based vinyl monomer mainly having vinyl chloride (usually 50% vinyl chloride is used). As a comonomer copolymerized with vinyl chloride, ethylene,
Α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene Acrylic acid, acrylic acid such as methyl acrylate and ethyl acrylate, or ester thereof; methacrylic acid such as methacrylic acid and methyl methacrylate or ester thereof; maleic acid or ester thereof; vinyl ester such as vinyl acetate and vinyl propionate; Lauryl vinyl ether,
Examples thereof include vinyl ethers such as isobutyl vinyl ether; maleic anhydride; acrylonitrile; styrene; vinylidene chloride; and other monomers copolymerizable with vinyl chloride. These can be used alone or in combination of two or more.

The suspension polymerization in an aqueous medium according to the present invention using these monomers is carried out by using a dispersion aid usually used in the polymerization of vinyl chloride-based monomers such as methyl cellulose, hydroxyethyl cellulose, Water-soluble cellulose ethers such as hydroxypropyl cellulose and hydroxypropylmethyl cellulose; water-soluble or oil-soluble partially saponified polyvinyl alcohol; acrylic acid polymers;
Water-soluble polymers such as gelatin; sorbitan monolaurate, sorbitan trioleate, glycerin tristearate, oil-soluble emulsifiers such as ethylene oxide propylene oxide block copolymers; polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, sodium laurate, etc. These water-soluble emulsifiers and the like may be used alone or in combination of two or more.

Other conditions for this polymerization, the method of charging the aqueous medium, the vinyl chloride type monomer, the dispersion aid, etc. to the polymerization vessel, the charging ratio, etc. may be the same as in the conventional case. Further, this polymerization system is filled with a polymerization regulator, a chain transfer agent, a pH regulator, a gelation improving agent, an antistatic agent, a cross-linking agent, a stabilizer, and a filler, which are appropriately used for vinyl chloride-based polymerization. It is also optional to add agents, antioxidants, buffers, scale inhibitors and the like.

[0020]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Example 1, Comparative Examples 1 and 2 890 kg of deionized water and 350 g of partially saponified polyvinyl alcohol were placed in a stainless steel polymerization vessel having an internal volume of 2.1 m ^3.
And were added as an aqueous solution. After degassing the inside of the vessel to 50 mmHg, 700 kg of vinyl chloride monomer was charged, and while stirring, the type and amount of the polymerization initiator shown in Table 1 was further injected with a pump, and at the same time the temperature was raised to start the polymerization. Started.

The polymerization reaction was carried out while maintaining the polymerization temperature at 55 ° C., the polymerization was stopped when the internal pressure of the polymerization vessel dropped to 6.0 kg / cm ² G, and the unreacted monomer was recovered to obtain the resulting polymer. After the combined product was taken out as a slurry from the outside of the container, the state of scale adhesion inside the container was observed, and the polymer was dehydrated and dried and subjected to the test by the following method, and the results are also shown in Table 1. In addition,
In Comparative Example 2, since the jacket temperature reached the cooling water temperature of 25 ° C. 2 hours after the initiation of the polymerization, the temperature inside the vessel increased by 3 ° C.

Adhesion of scale in polymerization vessel: Evaluation was made according to the following criteria. ◎ ・ ・ ・ No scale is attached and the metallic mirror surface has gloss. ○: There is some cloudiness on the metal mirror surface. △ ‥ ‥ ‥‥ There is a film scale on the entire metal surface.

Measurement of bulk specific gravity: The obtained polymer was measured according to JIS K-6721.・ Measurement of particle size distribution: JIS Z-88 for the obtained polymer
Sift using ^# 60, ^# 100, ^# 200 sieves according to 01,
The amount of passage was measured and expressed in% by weight.

Measurement of the amount of fish eyes: 100 parts by weight of the obtained polymer, 50 parts by weight of DOP, barium stearate
0.1 parts by weight, cadmium stearate 0.1 parts by weight, cetanol 0.8 parts by weight, tin stabilizer 2.0 parts by weight, titanium dioxide 0.5 parts by weight and carbon black 0.1 parts by weight,
Mix and knead with a 6-inch roll at 140 ℃ for 5 minutes to obtain a thickness of 0.3
The sheet was separated as a sheet having a size of 100 mm ² , and the number was shown by the number of white transparent particles in 100 cm ^{2 of} this sheet.

Extraction test: Dilute 15 g of the obtained polymer into an extraction bottle with 300 ml of distilled water. Place the extraction bottle in the sterilizer and leave it at 125 ° C for 60 minutes. After cooling, the extraction bottle is removed and the supernatant is measured for UV absorption and potassium permanganate consumption. At this time, a sample containing only distilled water containing the polymer is used as a standard.

(UV absorption) Absorbance was measured at wavelengths of 220 nm and 241 nm and the difference from the reference value was 0.08 at 220 nm and 0.05 at 241 nm.
If it is more than the above, it is marked with x. (Consumption amount of potassium permanganate) After adding potassium permanganate, titration is performed with sodium thiosulfate. Difference from standard value is 1.00cc
In the above, it is set to x.

Initial colorability: 100 parts by weight of the obtained polymer, 1 part by weight of tin laurylate, 0.5 of a cadmium stabilizer.
1 part by weight and 50 parts by weight of diocrytyl phthalate were mixed and kneaded with a two-roll mill at 160 ° C. for 5 minutes, and then formed into a sheet having a thickness of 0.8 mm. Next, this sheet was cut and stacked, put in a 4 cm × 4 cm × 1.5 cm (thickness) mold, and heated and pressed at 160 ° C. and 65 to 70 kgf / cm ² to prepare a sample. This was visually observed and evaluated according to the following criteria. ⊚ Same as Comparative Example 4. B: Stronger yellowness than Comparative Example 4.

The abbreviations for the polymerization initiators in the table mean the following. BPD: t-butylperoxy neodecanoate (46 ° C) CPD: α-cumylperoxy neodecanoate (36 ° C) HDPH: 3-hydroxy-1,1-dimethylbutylperoxy neoheptanoate (41) ℃)

[0029]

[Table 1]

Examples 2 to 4 and Comparative Examples 3 to 6 A stainless steel polymerization vessel having an internal volume of 2.1 m ³ was charged with 930 kg of deionized water and 760 g of partially saponified polyvinyl alcohol.
And were added as an aqueous solution. After degassing the inside of the vessel to 50 mmHg, charge 630 kg of vinyl chloride monomer, and while stirring, press the type and amount of the polymerization initiator shown in Table 2 with a pump and at the same time raise the temperature to start the polymerization. Started.

The polymerization reaction is carried out while maintaining the polymerization temperature at 51 ° C., the polymerization is stopped when the internal pressure reaches 6.0 kg / cm ² G, the unreacted monomer is recovered, and the obtained polymer is slurried. The sample was taken out of the container, dehydrated and dried, and subjected to the subsequent tests. The results are also shown in Table 2. In Comparative Example 3, the jacket temperature reached the cooling water temperature of 26 ° C. 3 hours and 30 minutes after the initiation of the polymerization, so that the temperature inside the vessel rose by 1.5 ° C.

The abbreviations for the polymerization initiators in the table mean the following, respectively. BPD: t-butylperoxy neodecanoate (46 ° C.) TPPD: 2,4,4-trimethylpentylperoxy-2
-Neodecanoate (36 ° C) CPD: α-cumylperoxy neodecanoate (36 ° C) DEPD: Di- (2-ethoxyethyl) peroxydicarbonate (43 ° C) HDPH: 3-hydroxy-1,1-dimethyl Butyl peroxy neoheptanoate (41 ℃)

[0033]

[Table 2]

Examples 5, 6 and Comparative Example 7 1030 kg of deionized water and 700 g of partially saponified polyvinyl alcohol were placed in a stainless steel polymerization vessel having an internal volume of 2.1 m ^3.
And were added as an aqueous solution. After degassing the inside of the vessel to 50 mmHg, charge 570 kg of vinyl chloride monomer, and while stirring, press the type and amount of the polymerization initiator shown in Table 3 with a pump and at the same time start heating to start the polymerization. Started.

The polymerization reaction was carried out while maintaining the polymerization temperature at 39 ° C., and the polymerization was stopped when the internal pressure reached 4.5 kg / cm ² G,
Unreacted monomers were recovered, the obtained polymer was taken out of the vessel in a slurry form, dehydrated and dried, and subjected to the subsequent tests. The results are also shown in Table 3.

The abbreviations for the polymerization initiators in the table mean the following. IBP: isobutyryl peroxide (33 ° C) BPD: t-butylperoxyneodecanoate (46 ° C) HDPH: 3-hydroxy-1,1-dimethylbutylperoxyneoheptanoate (41 ° C)

[0037]

[Table 3]

[0038]

EFFECTS OF THE INVENTION According to the method of the present invention, there are restrictions due to lack of cooling capacity of the whole polymerization apparatus, influence on polymer quality, especially initial colorability, deterioration of thermal stability, polymerization initiator residue or decomposition formation. Occurrence of unpleasant odor due to increase in substances, increase in extraction components, etc. are not encountered, and further, the amount of scale attached in the polymerization vessel can be suppressed, so that a high-quality vinyl chloride polymer can be obtained with high productivity, The industrial effect is extremely large.

Claims (2)

[Claims] 1. When suspension polymerization of a vinyl chloride monomer or a mixture of vinyl-based monomers mainly containing vinyl chloride monomer with an oil-soluble polymerization initiator in an aqueous medium, the polymerization initiator (A ) A compound having a benzene ring or an alkoxy group in its structure at a temperature of 30 to 50 ° C for a 10-hour half-life at 0.1 mol / L in benzene and (B) 3-hydroxy-
A method for producing a vinyl chloride polymer, which is used in combination with 1,1-dimethylbutylperoxyneoheptanoate. 2. The (A) compound as the polymerization initiator,
The method for producing a vinyl chloride polymer according to claim 1, which is one kind or a combination of two or more kinds selected from diacyl, perester or percarbonate compounds.