JPH01240501A - Dispersion stabilizer for suspension polymerization of vinyl compound - Google Patents

Abstract

PURPOSE:To obtain the subject stabilizer capable of producing vinyl chloride polymer particles simultaneously having plasticizer absorptibity and a remarkably high packing specific gravity, by blending two kinds of polyvinyl alcohol- based polymer with each specified polymerization degree and saponification degree. CONSTITUTION:A dispersion stabilizer obtained by blending (A) a polyvinyl alcohol-based polymer (e.g., polymer obtained by polymerizing a vinyl ester in the presence of a chain-transfer agent such as n-octyl aldehyde and subsequent ly saponifying the resultant product) with >=6C alkyl group at the terminal, <=500 polymerization degree and >=98mol% saponification degree with (B) another polyvinyl alcohol-based polymer with >=500 polymerization degree and 70-90% saponification degree in a weight ratio of A/B=30/70-70/30, preferably 40/60-60/40.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dispersion stabilizer for suspension polymerization of vinyl compounds, especially vinyl chloride.

(B) Conventional technology When producing vinyl chloride resin industrially, vinyl chloride monomers are dispersed in an aqueous medium in the presence of a dispersion stabilizer, and polymerization is carried out using an oil-soluble catalyst. Suspension polymerization methods are widely practiced. In general, the factors that control the quality of the resin include the polymerization rate, water-motsumer ratio, polymerization temperature, type and amount of catalyst, type of polymerization tank, stirring speed, and type and amount of dispersion stabilizer, among others. It is known that the type of dispersion stabilizer has a very large effect.

The performance required of a dispersion stabilizer for suspension polymerization of vinyl chloride monomers is (i) to exhibit high dispersion power even when used in a small amount, and to make the particle size distribution of the resulting vinyl chloride polymer particles as sharp as possible; (11) To increase the absorption rate of the plasticizer and facilitate processability, and to facilitate the removal of vinyl chloride monomer remaining in the polymer particles; (iii) It has the function of making each polymer particle as uniform and porous as possible in order to prevent the formation of fish eyes, etc., and (iii) It has the function of creating polymer particles with a high filling specific gravity.

Conventionally, cellulose derivatives such as methyl cellulose and carboxymethyl cellulose, partially saponified polyvinyl alcohol, and the like have been used alone or in combination as dispersion stabilizers for @turbidity polymerization of vinyl compounds. However, these methods have drawbacks such as low ability to make vinyl chloride polymer particles porous, slow plasticizer absorption rate, and difficulty in removing residual vinyl chloride monomers.

It is also known to use a polyvinyl alcohol (hereinafter abbreviated as PVA) polymer having an alkyl group at the end as a dispersion stabilizer for suspension polymerization of a vinyl compound.

For example, in JP-A-51-18779, the number of carbon atoms at the end is 8.
P having the above alkyl group and a polymerization degree of 300-1500
It has been disclosed that VA alone is used in an amount of 0.2% based on vinyl chloride monomer, and JP-A-54-259
No. 90 discloses that PVA having an alkyl group having 4 or more carbon atoms at the end and having a saponification degree of 60 to 90 mol% is used alone or together with general polyvinyl alcohol in an amount of 0.1% based on the vinyl chloride monomer. Furthermore, JP-A-59-166505 discloses the use of PVA having an alkyl group at the terminal and having a degree of polymerization of less than 150 alone at 0.05% based on the vinyl chloride monomer.゛However, although it is recognized that the porosity of the vinyl chloride resin obtained by these methods tends to increase, it has the disadvantage that it is difficult to obtain a material with a large filled specific gravity.Especially in recent years, there has been a demand for a vinyl chloride resin with a large filled specific gravity. In reality, it was not at a level that could be used satisfactorily.

(C) Solving the Problem - Ginco-1st Stage ~ As a result of intensive research to solve the above problems, the inventor has found (A)
It has an alkyl group with 6 or more carbon atoms at the end, and the degree of polymerization is 50.
0 or less and a saponification degree of more than 98 mol%, and (B) a PVA-based polymer with a saponification degree of 500 or more and a saponification degree of 70 to 70%.
90 mol% PVA polymer! It lil ratio (A
)/(B) is used in combination at a ratio of 30770 to 7G/3G, surprisingly, the above (i)(ii)(
We have completed the present invention by discovering that all of the requirements of (iii) are satisfied, and in particular, the filling specific gravity of (iii) is significantly improved.

The (A) PVA-based polymer having an alkyl group having 6 or more carbon atoms at the terminal of the present invention is obtained by polymerizing a vinyl ester in the presence of a chain transfer agent described below and saponifying the obtained polyvinyl ester. be able to.

As the chain transfer agent, an aldehyde or mercaptan having an alkyl group having 6 or more carbon atoms is used.

Examples of aldehydes include n-octylaldehyde, 2-ethyl-hexylaldehyde, n-capricaldehyde,
Examples include n-decylaldehyde, n-undecylaldehyde, laurylaldehyde, n-tridecylaldehyde, cetylaldehyde, valmitylaldehyde, and stearylaldehyde.

Examples of mercaptans include n-dodecylmercaptan, n-octylmercaptan, n-octadecylmercaptan, n-decylmercaptan, stearylmercaptan, and the like.

Although there is no particular upper limit to the number of carbon atoms, it is appropriate to select the number of carbon atoms from a range of 40 or less from the viewpoint of ease of manual work. These chain transfer agents may be used alone or in combination with
It is also possible to use more than one species in combination. The chain transfer agent obtains P
It is used to the extent that the average polymerization degree of VA is 500 or less.

The average degree of polymerization of the PVA-based polymer (A) having an alkyl group having 6 or more carbon atoms at the terminal used in the present invention needs to be 500 or less, preferably 200 or less.

If the degree of polymerization exceeds 500, a vinyl chloride resin with high plasticizer absorption cannot be obtained.

Further, it is necessary that the degree of saponification of the PVA-based polymer (A) having an alkyl group having 6 or more carbon atoms at the end used in the present invention is greater than 98 mol%. If the degree of saponification is 98 mol% or less, it may be difficult to obtain a vinyl chloride resin with a high filling specific gravity.

In addition, the above-mentioned P having an alkyl group at the end used in the present invention
The alkyl group of VA needs to have 6 or more carbon atoms. When the number of carbon atoms is less than 6, the above-mentioned remarkable effects cannot be obtained.

In the present invention, (A) a PVA-based polymer having an alkyl group having 6 or more carbon atoms at the terminal as described above and (3) a polymerization degree of 5
00 or more, preferably 1000 or more, and the degree of saponification is 7a~
90 mol%, preferably 75 to 85 mol% of the PVA-based polymer at a polymerization ratio of 30/70 to 7G/3G.

It is an essential requirement that they be used in combination, preferably in a ratio of 40/60 to 6074G.

The degree of polymerization of the PVA-based polymer (B) used here is 5
It is necessary that the saponification degree is 00 or more, and the saponification degree is 70 to 9.
It is necessary that it be 0 mol%. When the degree of polymerization of the PVA-based polymer (3) is less than 500, the particle size distribution of the vinyl chloride resin is likely to be wide, and coarse particles are likely to be formed.

In addition, if the degree of saponification of the PVA-based jIf aggregate (B) is less than 70 mol%, it is easy to form a vinyl chloride resin that becomes fish eyes, and if it is 90 mol% or more, the particle size distribution is wide. Prone.

When (A)/(B) is smaller than 30/70, the plasticizer absorption tends to be low, and when it is larger than 70/30, the filled specific gravity does not increase.

A polyvinyl polymer having an alkyl group of 6 or more, a degree of polymerization of 500 or less and a degree of saponification of more than 98 mol%, and one or more types of (B) a degree of polymerization of 500 or more and a degree of saponification of 70 Up to 90 mol % of polyvinyl alcohol-based polymers can be mixed and used in the same blending ratio as above.

When using the dispersion stabilizer obtained by the above method to perform suspension polymerization of vinyl chloride alone or a mixture containing vinyl chloride as a main component and a monomer that can be copolymerized with it, the dispersion stabilizer is usually added to the aqueous medium. The process is carried out in the presence of an oil-soluble catalyst by adding and dispersing a vinyl chloride monomer or a mixture of monomers copolymerizable with the vinyl chloride monomer. The dispersion stabilizer may be added as a powder or as an aqueous solution.

The dispersion stabilizer is 0.0% for a vinyl chloride monomer or a mixture of vinyl chloride monomers and monomers that can copolymerize with vinyl chloride monomers.
01-0.2% by weight, preferably 0.03-0.07
% by weight used.

Further, the catalyst used in suspension polymerization may be any oil-soluble catalyst, such as benzoyl peroxide, lauroyl peroxide, diisopropyl peroxydicarbonate, 2.2'-azoisobutyronitrile, 2.2 '-Azobis-2°4-dimethylvaleronitrile or mixtures thereof are used.

The polymerization temperature is selected from a range of about 30 to 100°C.

One or more nonionic surfactants and/or anionic surfactants can also be used in combination as a dispersion aid during polymerization.

Furthermore, the dispersion stabilizer of the present invention enables stable polymerization even when the stirring blade of the polymerization tank is a high-speed stirring type such as a blue margin type, and all of the above (i), (ii), and (iii) are possible. One of the characteristics is that it is possible to obtain a vinyl chloride resin that satisfies the following requirements.

Furthermore, even if the temperature of the water at the time of charging the vinyl chloride compound monomer into the polymerization tank is 30 to 80° C., there is no problem with the stability of polymerization and the performance of the vinyl chloride compound resin obtained.

Although the explanation has been given mainly regarding the polymerization of vinyl chloride, the dispersion stabilizer of the present invention is not necessarily limited to the polymerization of vinyl chloride, and can be used with vinylidene chloride, alkyl vinyl ethers, vinyl acetate, acrylic acid, and esters thereof. , methacrylic acid and its esters, maleic acid and its anhydrides, itaconic acid, styrene, vinyl chloride, acrylonitrile, isoprene, isobutene, alpha-olefins such as butanoene, and ethylene. It is also used for suspension polymerization of vinyl compounds containing

(D) Saku no I-N7L-μLV□Deku1□NanajiL
□4 Book 1 - The present invention specifies (A) the degree of polymerization and degree of saponification of a PVA-based polymer having an alkyl group having 6 or more carbon atoms at the terminal, and (B) the degree of polymerization is 500 or more and the degree of saponification is 70.
By specifying the blending ratio of ~90 mol% of PVA-based polymer, it was possible to obtain vinyl chloride polymer particles that simultaneously satisfy plasticizer absorption and extremely high filling specific gravity, which were previously thought to be contradictory. It has extremely high industrial value.

(E) Examples The present invention will be explained in more detail with reference to Examples below, but the dispersion stabilizer of the present invention is not limited only to these Examples. In the examples, parts and percentages are based on weight.

9 Husband "Ji-Kichi" Tragedy 1 J Ributsumi 30 Glass lined autoclave with deionized water 1
50 parts, various dispersion stabilizers in the amounts shown in [Table-1] to [Table-6], and 0.2 part of di-2-ethylhexyl peroxydicarbonate were charged, and the inside of the autoclave was heated to 50 parts.
After removing oxygen by degassing until the mass was reduced to 11 g mm, 100 parts of vinyl chloride monomer was added, and the mixture was stirred at 750 rpIi using a blue margin type stirring blade at 54°C.
Polymerization was carried out by raising the temperature to .

At the start of polymerization, the pressure inside the autoclave was 8.0 kg/C.
-G, but 4.0 kg/cm 8 hours after the start of polymerization
At this point, the polymerization was stopped, the unreacted vinyl chloride monomer was purged, and the contents were taken out and dehydrated and dried.

The polymerization yield of vinyl chloride resin is 90%, and the average type of synthetic leather is 1
・It was 00.

(E)-2: For vinyl chloride - properties *N value method (1) Particle size distribution: Measured by dry sieve analysis using a wire mesh based on Tyler mesh (42 to 200 mesh).

(2) Average particle size 2 It was determined by plotting the weight composition divided into two parts by the above method on a Rosin-Rammler diagram.

(3) Filling specific gravity: JIS K 6721-1959
Measured by.

(4) Uniformity of particle porosity: 100 parts of vinyl chloride resin,
50 parts of dioctyl phthalate, 1 part of dibutyltin maleate
part, cetyl alcohol 1 part, titanium white 0.25ffi,
A mixture of 1 part of carbon black Q was kneaded with a roll at 150°C for a predetermined time to form a sheet with a wall thickness of 0.2 mm, and light was transmitted through this to determine the number of fish eyes contained in the sheet per 100 cm. The faster the fish eyes disappeared, the more uniform the particle porosity was.

(5) Using a planetary mixer connected to a plasticizer-absorbing niblastograph, add 100 parts of vinyl chloride resin and 50 parts of dioctyl phthalate in a container kept at 80°C, and add the The kneading torque is recorded and expressed as the kneading time at the point where the kneading torque decreased.

(6) Residual vinyl chloride monomer: A certain amount of vinyl chloride resin was dissolved in tetrahydrofuran, and the vinyl chloride monomer content in the vinyl chloride resin was determined by gas chromatography.

(E)-3: Extravagant vinyl 1 performance steering wheel 1” [Example 1
~4], [Comparative Example 1] Using the dispersion stabilizer shown in Table 1, (A) For the purpose of investigating the influence of the number of carbon atoms in the alkyl group of the PVA polymer having an alkyl group at the terminal (E) Suspension polymerization of vinyl chloride was carried out by the method shown in -1. The results are shown in Table-1.

[Examples 5 to 7], [Comparative Examples 2 to 4] Using the dispersion stabilizer shown in Table 2, for the purpose of investigating the influence of the degree of saponification of (A) PVA-based polymer pentapolymer having an alkyl group at the terminal. Suspension polymerization of vinyl chloride was carried out by the method shown in (E)-1. The results are shown in Table-2.

[Examples 8 to 1G), [Comparative Example 5] Using the dispersion stabilizer shown in Table 3, for the purpose of investigating the influence of the degree of polymerization of (A) PVA-based polymer having an alkyl group at the terminal, (Elf Suspension polymerization of vinyl chloride was carried out by the method shown below.The results are shown in Table 3.

[Examples 11 to 13), [Comparative Examples 6 to 7] Using the dispersion stabilizer shown in Table 4, (E)-I was used for the purpose of investigating the influence of the saponification degree of (B) PVA-based polymer. Suspension polymerization of vinyl chloride was carried out using the method shown below.

The results are shown in Table-4.

[Examples 14 to 17), [Comparative Example 8] Using the dispersion stabilizer shown in Table-5, the method shown in (E)-1 was carried out for the purpose of investigating the influence of the degree of polymerization of the (B) PVA-based polymer. Suspension polymerization of vinyl chloride was carried out. The results are shown in Table-5.

[Examples 18 to 20), (Comparative Examples 9 to +4) Using the dispersion stabilizer shown in Table 6, a combination of (A) PVA polymer having an alkyl group at the terminal and (B) PVA polymer In order to investigate the effect of ratio, suspension polymerization of vinyl chloride was carried out using the method shown in Elf. The results are shown in Table 6.

Margin below

Claims (16)

[Claims] (1) (A) A polyvinyl alcohol polymer having an alkyl group having 6 or more carbon atoms at the terminal, a degree of polymerization of 500 or less and a degree of saponification of greater than 98 mol%, and (B) a degree of polymerization of 500 or less.
In the above, the polyvinyl alcohol polymer with a saponification degree of 70 to 90 mol% is used in a weight ratio of (A)/(B) of 30/70 to
A dispersion stabilizer for suspension polymerization of vinyl compounds, characterized by being mixed in a ratio of 70/30. (2) The dispersion stabilizer according to claim (1), wherein (A) the polyvinyl alcohol polymer having an alkyl group having 6 or more carbon atoms at the terminal has a degree of polymerization of 200 or less. (3) (A) A polyvinyl alcohol polymer having an alkyl group having 6 or more carbon atoms at the terminal, a degree of polymerization of 500 or less, and a degree of saponification of more than 98 mol% is converted into a vinyl ester in the presence of a chain transfer agent. Claim (1) is obtained by polymerizing polyvinyl ester and saponifying the obtained polyvinyl ester.
) Dispersion stabilizer described in . (4) Chain transfer agent is n-octylaldehyde, 2-ethyl-hexylaldehyde, n-caprinaldehyde, n
-decylaldehyde, n-undecylaldehyde, n-
Aldehydes having 6 or more carbon atoms such as lauryl aldehyde, n-tridecyl aldehyde, cetyl aldehyde, palmityl aldehyde, stearyl aldehyde, or n-dodecyl mercaptan, n-octyl mercaptan, n-octadecyl mercaptan, n-decyl mercaptan, stearyl mercaptan, etc. The dispersion stabilizer according to claim 3, which is a mercaptan having 6 or more carbon atoms. (5) Claim (3) wherein the vinyl ester is vinyl acetate.
Or the dispersion stabilizer described in (4). (6) The dispersion stabilizer according to claim (1), wherein the polyvinyl alcohol polymer (B) has a degree of polymerization of 1000 or more and a degree of saponification of 75 to 85 mol%. (7) Vinyl compounds include vinylidene chloride, alkyl vinyl ether, vinyl acetate, acrylic acid and its esters, methacrylic acid and its esters, maleic acid and its anhydride, itaconic acid, styrene, vinyl chloride, acrylonitrile, isoprene, and isobutene. The dispersion stabilizer according to claim 1, which contains one or more components from the group consisting of α-olefins such as , butadiene, and ethylene. (8) Claim (7) wherein the vinyl compound is vinyl chloride.
The dispersion stabilizer described in. (9) The dispersion stabilizer according to claim (1), wherein (A)/(B) is 40/60 to 60/40. (10) One or more polyvinyl alcohol-based polymers (A) having an alkyl group having 6 or more carbon atoms at the terminal and having a degree of polymerization of 500 or less and a saponification degree of more than 98 mol%; The dispersion stabilizer according to claim 1, wherein two or more types of (B) polyvinyl alcohol polymers having a degree of polymerization of 500 or more and a degree of saponification of 70 to 90 mol% are mixed. (11) The dispersion stabilizer according to (1), wherein one or more nonionic surfactants and/or anionic surfactants are used together as a dispersion aid during polymerization. (12) The dispersion stabilizer according to claim (1), wherein the amount of the dispersion stabilizer used is 0.01 to 0.2% by weight based on the vinyl compound. (13) The dispersion stabilizer according to claim (12), wherein the amount of the dispersion stabilizer used is 0.03 to 0.07% by weight based on the vinyl compound. (14) The dispersion stabilizer according to claim (1), wherein the stirring blade of the polymerization tank is of a blue margin type. (15) The dispersion stabilizer according to item (1), wherein the temperature of the water when charging the vinyl compound into the polymerization tank is 30 to 60°C. (16) Examples 1 to 2 of the suspension polymerization method of vinyl compounds
The dispersion stabilizer according to claim 1, which is the dispersion stabilizer according to claim 0.