JPS62246903A - Dispersion stabilizer for suspension polymerization - Google Patents

Abstract

PURPOSE:To obtain the titled dispersion stabilizer which can give vinyl chloride polymer particles which are porous and have a large specific gravity of packing and a large particle diameter, by mixing a fluorinated group-terminated PVA polymer of a specified degree of saponification and a specified degree of polymerization with, optionally, another PVA polymer. CONSTITUTION:A polyvinyl ester polymer (a) obtained by polymerizing a vinyl ester (e.g., vinyl acetate) at 10-90 deg.C in the presence of a radical polymerization initiator with the aid of a fluorinated thiol (e.g., a compound of the formula) is subjected to methanolysis at 20-60 deg.C in the presence of 0.001-0.2mol, per mol of the vinyl ester units of component (a), of a catalyst (b) (e.g., NaOH) to obtain a fluorinated group-terminated PVA polymer (A) of a degree of saponification >=60mol% and a degree of polymerization <2,000. Component A is mixed with a PVA polymer of a degree of saponification of 60-99mol% and a degree of polymerization of 100-3,500 at a weight ratio (A/B) of 50-95/50-5.

Description

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

When producing vinyl chloride-based resins industrially, a suspension polymerization method is widely used, in which vinyl chloride hexamer is dispersed in an aqueous medium in the presence of a dispersion stabilizer, and polymerization is carried out using an oil-soluble catalyst. ing. In general, factors governing the quality of the resin include the polymerization rate, water-motsumer ratio, polymerization temperature, type and weight of catalyst, type of polymerization tank, stirring speed, type and amount of dispersion stabilizer, etc. Among these, it is known that the type of dispersion stabilizer has a very large influence.

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 small amounts, and to sharpen the particle size distribution of the resulting vinyl chloride polymer particles as much as possible; (u) In order to increase the absorption rate of the plasticizer to facilitate processability and to facilitate the removal of vinyl chloride monomer remaining in the polymer particles, fish eyes in the molded product etc. It has the function of making each polymer particle as uniform and porous as possible in order to prevent the formation of (i) It has the function of creating polymer particles with a high filling specific gravity.

B. Prior Art Conventionally, dispersion stabilizers for suspension polymerization of vinyl compounds include cellulose derivatives such as methylcellulose and carboxymethylcellulose, partially gephlated polyvinyl alcohol, and the like, either alone or in combination.

Problems to be Solved by the C0 Invention However, these have the drawbacks of low ability to make vinyl chloride polymer particles porous, slow plasticizer absorption rate, and difficulty in removing residual vinyl chloride polymer particles. .

Means for solving the D0 problem The present invention In view of the current situation, we investigated a better dispersion stabilizer for suspension polymerization and found that (a) it has a fluorine-containing group at the end and has a high degree of saponification. is 60 mol or more and the degree of polymerization is less than 2000 (hereinafter polyvinyl alcohol may be abbreviated as PVA)-based polymer, or (b) saponification degree of 60 to 99 mol%,
By using a mixture with a polyvinyl alcohol polymer having a degree of polymerization of 100 to 3500 as a dispersion stabilizer,
The suspension polymer particles of vinyl chloride threads have a sharp particle size distribution, are porous, and have a large packing specific gravity, and this suspension polymerized vinyl chloride polymer absorbs plasticizers. It has the following advantages: high speed, easy removal of vinyl chloride monomer remaining in polymer particles, less scattering of powder during handling in addition to roughness, and good penetration into molding machines, etc. ``We have discovered that it has excellent performance and have completed the present invention.

(a) PVA having a fluorine-containing group at the terminal used in the present invention
The polymer has a volatile fluorine-containing group, preferably a carbon group, at the end.
PVA polymer having fluorine-containing groups such as e2 or more fluorinated alkyl groups or fluorinated alkyl ether groups, preferably 4 or more, with a saponification degree of 60 mol% or more, preferably 60 to 99 mol%, and 1, preferably 65-99
mol%, and the degree of polymerization is less than 2000, preferably 1000
Refers to PVA-based polymers of less than

The PVA-based polymer having a fluorine-containing group at the end of the present invention exhibits excellent suspension polymerization and dispersion stability by itself;
b) Saponification degree 60-99 mol%, polymerization degree 100-35
A PVA polymer that does not have a fluorine-containing group at the terminal of LIO can be used in combination. In particular, PVA polymers having a relatively low degree of polymerization of less than 1,000, preferably 500 or less, more preferably 150 or less, and a terminal fluorine-containing group and a saponification degree of 65 to 99 mol%, and a polymerization degree of 300 or more are preferred. ] 7 or more, preferably 1000 or more, and a saponification degree of 65 to 95 mol% and a PVA polymer that does not have a fluorine-containing group at the end is used in combination as a dispersion stabilizer to improve stability during polymerization. It is suitable to obtain uniform polyvinyl chloride particles with good and more porous and large particle size distribution. Of course, fluorine-containing PVA can also be used in combination.

The PVA polymer having a fluorine-containing group at the end of the present invention can be used without any limitation in its manufacturing method as long as it is a PVA polymer having a fluorine-containing group at the end. For example, PVA with a fluorine-containing group at the end is produced by polymerizing a vinyl ester in the coexistence of a compound having an active group such as an alcohol, an aldehyde, or a thiol having a fluorine-containing group as a chain transfer agent, and then saponifying the vinyl ester unit.
It can be produced by a method of obtaining a polymer based on a polymer, a method of introducing a group having a fluorine-containing group at the end of a polymer based on a polymer through a chemical reaction, and the like. However, as a more economical and more efficient method of introducing fluorine-containing groups at the terminals and obtaining PVA-based polymers having fluorine-containing groups at the terminals that exhibit excellent dispersion stability, there is a chain transfer method that has fluorine-containing groups. Preferred is a method in which vinyl esters such as vinyl acetate are polymerized in the presence of a thiol having a fluorine-containing group (hereinafter sometimes referred to as fluorine-containing thiol), and then saponified.

Various fluorine-containing thiols can be used, but
The general formula nr-s (2) and 1 (a represented by f-X-8R) can be used. Bf is a group containing a fluorine atom, preferably having 2 or more carbon atoms, more preferably 4 or more carbon atoms,
It represents a fluorine-containing group such as fluorinated alkyl or fluorinated alkyl ether, and X is a group that connects a group containing a fluorine atom with 8H, and includes an alkyl chain, an alkyl ether chain, an alkyl chain having an amide bond, an alkylthioether chain, etc. vinegar. +0112% n as an alkyl chain! i ~
5. As an alkyl ether chain, +CH2+h10+C
H2+nm=1-5, n=1-5, and the amide bond is preferably 100NH-t-OH2+n, n=1-5.

1(f-X-8kl) Specifically, H(-CF2-3..01d20(011□-)18
11. ii+CB'2-+-4(Jl, U(-OH
2-) 3811-H + CF2 C) 120 (OR,)
38H1u (cp2-q cH,o (Cn2)38
R1F C0F2)3CH20(0H2)3S)l,
F (CF2)5C112(J (0R2)38n
, F (ah, )7(Eu2O(CkL, )38H
, F (0F2), 0H20 (0H2) 38H1F (
OF, )60H20H28H% F (0F2)70
H2 (H28fl, FCCF2)80ki2Ck1
28H,F(CF2)g C11CH28u,F(C
F2)10CIi2C)12811-F(CF2
)6(0112)4SH1F(CF2)8CL(2CH
2N+0H2)381i-F(OF2)880fi2C
R28M, glance OH3 ni' (OF 2 )1o8 C112CH2SR-upper゛<clI"2)8C11zCHz8 (0H2)3
SR1F (CrF2)8-8CM, 1OH200R
2C) 128R-F (CkI゛2)8SCii,,C
H2S(M,,C■-,Skl,FCOF2)JCON
H(H,0H2SR,FCOF2),C0N)lciL
2C1f28H1F (0F2-)I C0NIIOH
, OH, 48H, etc. In addition, as shown in B1-8H, 02F58u-04Fg8R1Also, fluorine-substituted aromatic or ring hydrocarbons can be used as if, but aliphatic compounds such as alkyl fluoride and alkyl fluoride ether can be used. Fluorine-substituted compounds have better performance and are preferred.

The criterion for selection from among these fluorine-containing thiol groups is to improve the dispersion stability of the PVA polymer having a fluorine-containing group at the end of the present invention. F(OF2) than H(0F2)n-,
It is preferable that n is 2, and n needs to be 2 or more. Further, the upper limit of n is approximately 20, although there is no particular limit. Preferably n is 4 to 18, more preferably 6 to 18. Moreover, it is more preferable that the set be straight-shaped than branched.

When polymerizing vinyl esters such as vinyl acetate in the presence of a fluorine-containing thiol, the amount and method of addition of the fluorine-containing thiol to the polymerization system are appropriately selected. The fluorine-containing thiol is used as a chain transfer agent, and the amount and method of addition of the fluorine-containing thiol to the polymerization system are determined based on the considerations that affect the degree of polymerization and the distribution of the degree of polymerization of the resulting polymer, and the required PVA system. In order to efficiently introduce a fluorine-containing group at one end and obtain a PVA-based polymer with excellent performance, it is determined as appropriate from the viewpoint of dispersion stability of the polymer, depending on the reaction rate of vinyl ester in the polymerization system. It is preferable to add thiol so that the thiol group in the reaction system does not change much compared to the vinyl ester. By doing so, the efficiency of introducing the terminal fluorine-containing group is improved, and the degree of polymerization distribution is also narrowed, so that a dispersion stabilizer with excellent performance can be used, which is preferable. Show the degree of distribution! It is desirable that the ratio Pw/FN of the weight average degree of polymerization (Pw) to the number average degree of polymerization (PN) does not exceed 4.0.

The polymerization method of the present invention is a commonly known method such as bulk polymerization,
Any method such as solution polymerization, suspension polymerization, or emulsion polymerization may be employed, but solution polymerization using methanol, toluene, etc. is most preferred from an industrial perspective. The polymerization process can be produced using any of the batch, semi-batch, and continuous methods. The initiator used in the polymerization of the present invention is generally a known radical polymerization initiator.

For example, 2.2'-7zobisisobutyronitrile, 2
．． Examples include 2-azobis(4-methoxy-2,4-dimethylvaleronitrile)benzoyl peroxide, diisopropyl peroxydicarbonate, potassium persulfate, and the like. The polymerization temperature can be appropriately set depending on the initiator used, but is preferably 10 to 90°C.

In order to obtain a polyvinyl alcohol polymer by saponifying a polyvinyl ester polymer having a fluorine-containing group at the end, generally known methods such as alkali saponification and acid saponification can be employed, but industrially, methanol solvent is used. N
Methanol decomposition using aOH or CH30N a as a catalyst is most advantageous. Although there is no particular restriction on the degree of saponification, it is preferable to carry out the saponification at a temperature of 20 to 60°C from the viewpoint of preventing coloring of the obtained polyvinyl alcohol polymer. In addition, the amount of NaOH or CH3ONa used as a catalyst is usually in the range of 0.001 to 0.2 mol per 1 mol of vinyl ester units to prevent coloring of the polyvinyl alcohol polymer and to lower the base of sodium acetate. This is preferable from the point of view of keeping things in check. If there is a copolymer unit that consumes alkali, such as an acid, it is necessary to carry out saponification in addition to the amount within the above range.

The PVA polymer used in combination with the PVA polymer having a fluorine-containing group at the end of the present invention is other than the PVA polymer having a fluorine-containing group at the end, and has a saponification degree of 60 to 99 mol% and a polymerization degree of 60 to 99 mol%. Any polyvinyl alcohol-based monomer having a molecular weight of 100 to 3,500 can be used without any restrictions in its manufacturing method. (This PVA-based polymer is sometimes referred to as a combined PVA-based polymer.) The combined PVA-based polymer can be produced by a conventional method of polymerizing and saponifying a vinyl ester such as vinyl acetate. In addition to the vinyl alcohol units and vinyl acetate units contained in ordinary PVA, the PVA-based polymer may also contain a small proportion of a secondary component. The fourth component may contain an ionic group such as an anion or a cation, or may contain a nonionic group.

The proportion of the PVA polymer used in combination can be arbitrarily selected as long as it does not impede the effect of the PVA polymer having a fluorine-containing group at the end, but it is more preferably equal weight or less. The preferred usage ratio is (a)/(b)=50
150 to 9515 (weight ratio). For example, ζ is P with a relatively high degree of polymerization of 500 or more, preferably 1ooo or more.
By using VA in an equal M amount or less, the stability of polymerization is improved and it is preferable to use polyvinyl chloride which has excellent porosity. In this case, one having a relatively high degree of saponification can be used. However, PVA with fluorine at the end
The degree of polymerization is low, for example, 500 or less, preferably 300
Hereinafter, it is more preferable to use a PvA of 150 or less, and when a combined PVA polymer is mixed therein, the combined PV
The degree of polymerization of the A-based polymer is 2,000 or less, especially 1,000 or less, and it may be preferable to use it in an equal weight or more proportion. For example, the usage ratio is (a) / (mouth 1 = 5
0150 to 20/80 (weight ratio).

The degree of polymerization of the PVA-based polymer of the present invention is determined by acetylating the PVA-based polymer to form polyvinyl acetate (PVAc).
It was calculated from the measurement of the intrinsic viscosity in an acetone solution using Nakataka's formula (Akio Nakataka: Kobunshi Kagaku 6.451 (1949)). In addition, the value of the ratio PW/PN between the weight average degree of polymerization (Pw) and the number average degree of polymerization (PN) is determined by gel permeation chromatography (UP( 3) Up to tears 1
It can be determined by multiplying 1 by 1 and 1.The degree of saponification means the degree of saponification of the vinyl ester component, and if other components are copolymerized, those components are not included.Saponification The degree can be analyzed by conventionally known chemical analysis methods, nuclear magnetic resonance analysis methods, etc.

The PVA-based polymer of the present invention needs to be water-soluble PVa that can be dissolved or dispersed in water.

Those without water solubility are not preferred because of poor dispersion stability performance.

When the PVA-based polymer of the present invention is used as a dispersion stabilizer to carry out suspension polymerization of a mixture of vinyl chloride alone or a monomer copolymerizable with vinyl chloride, the dispersion is usually stabilized in an aqueous medium. A mixture of vinyl chloride and a monomer copolymerizable therewith is dispersed in the presence of an oil-soluble catalyst. The dispersion stabilizer remains as a powder,
Alternatively, it can be added to an aqueous medium as an aqueous solution. Other dispersion stabilizers, such as conventionally used cellulose derivatives, may be used as long as the effects of the present invention are not impaired.

The dispersion stabilizer is 0.0% based on vinyl chloride monomer or a mixture containing it as a main ingredient and a monomer that can be copolymerized with it.
05 to 0.05 to IMflk%, preferably 0.01 to 0.5 IMflk% is used.

Further, the catalyst used in suspension polymerization may be any oil-soluble catalyst, such as benzoyl peroxide, lauroyl peroxide, diisopropylene! Liver oxydicarbonate, 2,2-azoisobutyronitrile, 2,2'-7zobis-2'4-dimethylvaleronitrile or mixtures thereof are used.

The polymerization temperature is selected from a range of about 30 to 70'C.

A conventionally known dispersion stabilizer can also be appropriately used as an auxiliary agent during polymerization.

As the monomer copolymerizable with vinyl chloride, vinylidene halide, vinyl ether, vinyl acetate, acrylic acid, methacrylic acid and their esters, maleic acid and its anhydride, itaconic acid, styrene, etc. are used.

Although the above description has mainly focused on the polymerization of vinyl chloride, the dispersion stabilizer of the present invention is not necessarily limited to the polymerization of vinyl chloride, but can also be used for the suspension polymerization of vinyl compounds such as styrene and methacrylate.゛As a dispersion stabilizer for suspension polymerization, the present invention preferably has a fluorine-containing group such as a fluorinated alkyl group or a fluorinated alkyl ether group having 2 or more carbon atoms and more preferably 4 or more carbon atoms at the terminal, and has a saponification degree of 60 mol. % or more and a degree of polymerization of less than 2000. This has the ability to make vinyl chloride polymer particles more porous than ordinary PVA polymers that do not have fluorine-containing groups at their terminals. It has excellent properties such as a very high plasticizer absorption rate and easy removal of residual vinyl chloride, and its large particle size and sharp distribution prevents powder from scattering during handling. This shows that the suspension polymer has excellent properties such as low penetration and good penetration into molding machines, etc., and is excellent as a dispersion stabilizer for suspension polymerization.

On the other hand, P with a non-fluorinated hydrocarbon group at the end
VA polymers are known as excellent dispersion stabilizers for suspension polymerization, but in the present invention, PV polymers having a fluorine-containing group at the end
The A-based polymer also has excellent dispersion stability and has the advantage that the amount used can be reduced.

In addition, a fluorine-containing group is introduced into the side button by copolymerization.
Although PVA-based polymers also exhibit excellent surface activity, when used as a dispersion stabilizer for suspension polymerization.

The specific PVA-based polymer having a fluorine-containing group at the end of the present invention may exhibit remarkable effects, but its effects are unsatisfactory.

The PVA polymer having a fluorine-containing group at the end of the present invention exhibits excellent performance alone, but has a relatively low degree of polymerization.
For example, PVA having a polymerization degree of 500 or less, preferably 300 or less, more preferably 150 or less, and having a fluorine-containing group at the end.
By using PVA with a relatively high degree of polymerization, for example, 500 or more, in the system polymer, stability during polymerization is improved, and polychloride with large particle size and sharp distribution with excellent porosity can be achieved. It has the feature that it can be changed to vinyl.

Conventionally known PVA for dispersion stabilizers for suspension polymerization cannot exhibit excellent dispersion stability unless it is PVA with a relatively low degree of saponification, for example, so-called partially saponified PVA with a content of 88 mol% or less. Another major feature of PVA having fluorine-containing groups is that it has a relatively high degree of saponification, for example 90 mol% or more, and exhibits excellent performance.

The present invention will be explained in more detail with reference to Examples below, but the dispersion stabilizer for suspension polymerization of the present invention is not limited to these Examples. In the examples, parts indicate parts by weight.

960 parts of vinyl acetate (hereinafter abbreviated as VAc), 240 parts of methanol and F (CF2)70)I20H,S
Put 1.7 parts of F8 (hereinafter abbreviated as F8) into a reaction vessel, and after thoroughly purging the inside with nitrogen, raise the external temperature to 65°C, and when the internal temperature reaches 60°C, add 2.2'-7 10 parts of methanol containing 0.18 parts of bisisobutyronitrile was added. Meta containing FS26.3 immediately / /l
/ / V A c mixed solution (V A c / (V
60 parts of A c + )tanol) 80% a degree) were added uniformly over 5 hours. Polymerization rate after 5 hours (47%)
Met. After 5 hours, the container was cooled and the remaining VAc was expelled from the system together with methanol under reduced pressure while adding methanol, resulting in PVAc dissolved in methanol! i (concentration 70%) was obtained. Take a part of this methanol solution - PVACl 1 degree 50%, (Na(JH)/
Add a methanol solution of NaOR so that (V A C) = 0.009 (mole ratio), and saponify at 40 ° C. Polyvinyl alcohol (hereinafter abbreviated as PVA) with saponification of 1 ton and 91 mol % Degree of polymerization of PVA After refining the PVh and reacetylating it, the polar viscosity ([η]) of l' V A c in acetone is calculated using the Nakataka formula (Akio Nakataka; 凪 Molecular Chemistry 6.45).
1 (1949)), the degree of polymerization was 101.

The above PVA was washed under reflux with methyl acetate containing 9% water, purified by Soxhlet extraction with methanol for 48 hours, dissolved in heavy water, and subjected to nuclear magnetic resonance analysis (hereinafter referred to as N
(abbreviated as MR).

From this, the presence of CF3 group was confirmed, and elemental analysis confirmed the presence of F, and F (CF2
)7C1j2cH2-8-group fluorine-containing PV
It was confirmed that it was A. Next, gel permeation chromatography (hereinafter abbreviated as GPC) measurement of PVAc obtained by acetylating the purified PVA described above [Apparatus: Toyo Soda Kogyo Co., Ltd. tlLU-802B, Column: (H! [6X2 , solvent: tetrahydrofuran, temperature: 23±1'C], PW/PN =
A result of 2.02 was obtained.

The following 2 White Examples 1 to 13 and Comparative Examples 1 and 2 Suspension polymerization of vinyl chloride was carried out using PVA having a fluorine-containing group at the end, which was found according to the method described above, alone or in combination with PVA. 40 parts of deionized water, 0.75 parts of a 2% by weight aqueous solution of a dispersion stabilizer, and 0.009 parts of a 50-barrel toluene solution of diisopropyl peroxydicarbonate were charged into an autoclave carried out in the following manner. After degassing the inside of the autoclave to remove oxygen until 50 fins remained, 30 parts of vinyl chloride monomer was charged, and the temperature was raised to 57° C. with stirring to carry out polymerization.

At the start of polymerization, the pressure inside the autoclave was 8.5kli/
cm G, but 6.5 k 10 hours after the start of polymerization.
Since it became ti/cxG, the polymerization was stopped at this point,
Unreacted vinyl chloride salt was purged, and the contents were taken out and dehydrated and dried.

The physical properties and usage amount of the dispersion stabilizer are shown in Table 1, and the performance of the obtained vinyl chloride resin is shown in Table 2. The polymerization yield of the vinyl chloride resin was 85%, and the average degree of polymerization was 1000. The dispersion stabilizer for suspension polymerization using PVA having a fluorine-containing group at the end of the present invention alone or in combination with ordinary PVA It can be seen that a vinyl chloride resin with excellent performance was obtained and is excellent.

Margin below (1) Particle size distribution: Measured by dry sieve analysis using a wire mesh based on Tyler mesh.

(2) Filling specific gravity: , 1TIS K6721-195
9.

(3) Uniformity of particle porosity: 100 parts of vinyl chloride resin,
50 parts of dioctyl phthalate, 1 part of diptyltin maleite
A mixture of 1 part of cetyl alcohol, 0.25 part of titanium white, and 0.1 part of carbon black was kneaded with a roll at 150°C for a predetermined time (3 minutes, 5 minutes, 7 minutes) to form a wall thickness of 0.2 m. A sheet of 1,001 sheets was prepared, and the number of Fuitsunyu Eyes contained in the 1001 sheet was counted by transmitting light. This shows that the faster the fish eyes disappear, the more uniform the particle porosity is.

(4) Using a gufnetary mixer connected to a plasticizer-absorbing niblastograph, put 100 parts of vinyl chloride resin and 50 parts of dioctyl phthalate into a container kept at 80°C, and add the mixture at each hour while stirring. Record the mixing torque and display the kneading time at the point where the kneading torque decreased.

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

Claims (4)

[Claims] (1) (a) A polyvinyl alcohol polymer having a fluorine-containing group at the terminal and having a saponification degree of 60 mol% or more and a polymerization degree of less than 2000, or (b) a saponification degree of 60 to 99 mol. %, degree of polymerization is 10
A dispersion stabilizer for suspension polymerization of a vinyl compound, characterized in that it is made of a mixture with a polyvinyl alcohol polymer having a molecular weight of 0 to 3,500. (2) (a) Stable dispersion for suspension polymerization according to claim 1, wherein the polyvinyl alcohol polymer having a fluorine-containing group at the terminal has a saponification degree of 65 to 99 mol% and a polymerization degree of less than 1000. agent. (3) (a) The terminal fluorine-containing group of the polyvinyl alcohol-based polymer having a fluorine-containing group at the terminal is a fluorinated alkyl group or a fluorinated alkyl ether group having 2 or more carbon atoms. Dispersion stabilizer for suspension polymerization. (4) The dispersion stabilizer for suspension polymerization according to claim 1, wherein the vinyl compound is vinyl chloride.