JP2971935B2 - Dispersing aid for suspension polymerization of vinyl compounds - Google Patents

Description

Description: The present invention relates to a dispersing aid for suspension polymerization of vinyl compounds, in particular vinyl chloride.

B. Conventional technology A polyvinyl ester having a saponification degree of 70 mol% or less (hereinafter, referred to as a
It is known that PVAc) is useful as a dispersing aid for suspension polymerization of vinyl compounds.

However, since a PVAc polymer having a saponification degree of 70 mol% or less is insoluble in water, a method of charging it as a powder into a polymerization tank or charging it as a methanol solution or a water-methanol solution is used.

However, in the preparation of powder, sufficient performance as a dispersing agent cannot be obtained, and when a solution containing methanol is used, there is a serious problem in terms of environmental pollution.

C. Problems to be Solved by the Invention The object of the present invention is to eliminate the above-mentioned problems at all,
An object of the present invention is to provide a dispersing aid for suspension polymerization of a vinyl compound comprising an aqueous dispersion containing 70 mol% or less of a PVAc polymer as a dispersoid.

D. Means for Solving the Problems In view of such circumstances, the present inventors have studied excellent dispersion aids for suspension polymerization of vinyl compounds, and found that an amino group or an ammonium group Having a carboxyl group or a sulfonic acid group of 0.1 to 10 mol%, and a saponification degree of 70
An aqueous dispersion containing a mole percent or less of a PVAc polymer as a dispersoid was found, and the present invention was completed.

The PVAc-based polymer used in the present invention has an amino group, an ammonium group, a carboxyl group, or a sulfonic acid group in a side chain of 0.1 to 10 mol%, preferably 0.2 to 5 mol%,
It is a PVAc polymer having a saponification degree of 70 mol% or less. The degree of polymerization of the PVAc polymer is not particularly limited, but is preferably 100 or more, and more preferably 200 to 4000.

The PVAc-based polymer having an amino group, an ammonium group, a carboxyl group or a sulfonic acid group in the side chain used in the present invention can be used without limitation to the production method as long as it is a PVAc-based polymer having these functional groups in the side chain. can do.

Examples of the monomer containing an amino group or an ammonium group include monomers represented by the following general formulas (I) to (V).

[Where n is 0 to 3, m is 1 to 10, R ¹ , R ² , R ⁶ , R ⁷ and R ⁸ are hydrogen atoms or methyl groups, and R ³ and R ⁴ are lower alkyl groups (including substituents) X is a negative group which forms a salt with ammonium nitrogen, A is an amine or ammonium nitrogen atom, and a nitrogen atom of the amide group in formula (I) or (II
I) groups each linking to an oxygen atom in the formula; Examples of the monomer having a carboxyl group include monomers such as crotonic acid, maleic acid, fumaric acid, itaconic acid, and (meth) acrylic acid, and salts thereof.

Examples of the thiol having a sulfonic acid group include those represented by the following general formula.

(Where n = 1 to 4, R _{9 to} R ₁₇ are a methyl group or a hydrogen atom, M is a hydrogen atom, an alkali metal or an ammonium ion, respectively.) The amino group, ammonium group, carboxyl group or carboxyl group of the PVAc polymer The sulfonic acid group content is preferably in the range of 0.1 to 10 mol%, and more preferably in the range of 0.2 to 5 mol%.

Examples of the PVAc-based polymer used in the present method include vinyl acetate, vinyl propionate, and vinyl formate, but vinyl acetate is preferred from the viewpoint of economy.

In some cases, propylene, styrene, alkyl vinyl ether, alkyl acrylate (alkyl group having 1 to 10 carbon atoms), alkyl (meth) acrylate (alkyl group has 1 to 10 carbon atoms) and the like are less than 10 mol%. Those containing may also be used.

The solid concentration of the aqueous dispersion containing the PVAc polymer of the present invention as a dispersoid is not particularly limited, but is preferably 70% by weight or less, more preferably 1 to 6% by weight or 30 to 30% by weight.
60% by weight.

The particle size of the dispersoid is not particularly limited, but is preferably
It is 10 μm or less, more preferably 0.01 to 1 μm, and still more preferably 0.01 to 0.1 μm. From the viewpoint of long-term storage stability of the aqueous dispersion, the smaller the particle size, the better.

The greatest feature of the aqueous dispersion using the PVAc-based polymer of the present invention as a dispersoid is that the PVAc-based polymer itself has a self-emulsifying property, and is not less than one month without using a dispersant or an emulsifier. An aqueous dispersion having good long-term storage stability is obtained.

An aqueous dispersion containing the PVAc-based polymer of the present invention as a dispersoid,
Various additives can be freely added as long as the stability and use thereof are not adversely affected. For example, as additives, conventionally known polyvinyl alcohol (hereinafter abbreviated as PVA) polymers, cellulose derivatives,
A method of adding 5% by weight or less, preferably 1% by weight or less of an anionic, cationic or nonionic surfactant, a preservative or a small amount of alcohol to the PVAc-based polymer of the present invention, or NaOH, Na ₂ CO 3 ₃ , a method in which an alkali such as NaHCO ₃ or CH ₃ COONa is added to the PVAc polymer of the present invention in an amount of 1% by weight or less is also preferably used.

The aqueous dispersion using the PVAc polymer of the present invention as a dispersoid is 0%.
Good storage stability at に お け る 50 ° C., no change in properties even after storage for more than one month.

The method for producing the aqueous dispersion using the PVAc polymer of the present invention as a dispersoid is not particularly limited.For example, a method of charging a PVAc polymer powder into water under stirring, followed by stirring, and further heating And the like. When the concentration of the aqueous dispersion is high, the viscosity of the aqueous dispersion increases, so that the aqueous dispersion can be obtained using a kneader such as a kneader.

The aqueous dispersion of the present invention is particularly useful as a dispersing aid for suspension polymerization of a vinyl compound. That is, the aqueous dispersion of the present invention can provide a performance as a dispersing aid that exceeds the conventional unmodified PVAc-based polymer.

The dispersing agent comprising the aqueous dispersion of the present invention is used in combination with a PVA-based polymer or a cellulose-based derivative which is used as a dispersant for suspension polymerization of a vinyl-based compound. The same formulation as the unmodified PVAc polymer is applied.

When the aqueous dispersion of the present invention is used as an auxiliary and suspension polymerization of a vinyl compound, particularly vinyl chloride, is performed, the obtained vinyl compound, particularly vinyl chloride, has a plasticizer-absorbing property and a demonomerizing property. Good, high filling specific gravity and sharp particle size distribution can be obtained.

E. Examples Hereinafter, the present invention will be described in more detail with reference to Examples, but the aqueous dispersion of the present invention is not limited to these Examples. In the following examples, “%” means “% by weight” unless otherwise specified.

Examples 1 to 7 and Comparative Examples 1 to 2 The PVAc-based polymers shown in Table 1 were put into water, and the mixture was stirred with a peller at room temperature for 1 hour to obtain an aqueous dispersion of the PVAc-based polymer as a dispersoid. After obtaining the dispersion, the properties of the aqueous dispersion were observed. Table 1 shows the results.

Examples 8-13 and Comparative Examples 3-4 Deionized water 1 in 150 glass-lined autoclave
50 parts, various dispersion stabilizers shown in Table 2 and 0.2 parts of di-2-ethylhexylperoxydicarbonate were charged, and the inside of the autoclave was degassed to 50 mmHg to remove oxygen. The temperature was raised to 57 ° C. while stirring at a rotation speed of 580 rpm to carry out polymerization.

At the start of the polymerization, the pressure in the autoclave was 8.0 kg / cm ² G, but after 7 hours from the start of the polymerization, the pressure reached 3.5 kg / cm ² G. At this point, the polymerization was stopped and the unreacted vinyl chloride monomer was released. Was purged, and the contents were taken out and dehydrated and dried.

The polymerization yield of vinyl chloride resin is 87% and the average degree of polymerization is 10
It was 50.

 Table 3 shows the performance of the obtained vinyl chloride resin.

(1) Particle size distribution: measured by dry sieve analysis using a metal mesh based on Tyler mesh.

(2) Filling specific gravity: Measured according to JIS K 6721-1959.

(3) Uniformity of particle porosity: 100 parts of vinyl chloride resin, DOP
50 parts, dibutyltin maleate 1 part, cetyl alcohol 1
Part, a mixture of 0.25 part of titanium white and 0.1 part of carbon black are kneaded with a roll at 150 ° C. for a predetermined time to prepare a sheet having a thickness of 0.2 mm, which transmits light and is contained in the sheet per 100 cm ^2. I counted the number of fish eyes. The disappearance of the fish eye within a short time indicates that the uniformity of the particle porosity is better.

(4) Absorbency of plasticizer: 100 parts of vinyl chloride resin and 50 parts of dioctyl phthalate were charged into a container kept at 80 ° C. using a planetary mixer connected to a plastograph.
The kneading torque for each time is recorded while stirring, and the kneading time at the point where the kneading torque is reduced is indicated.

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

F. Effects of the Invention As is clear from the above Examples, the dispersing aid for suspension polymerization of a vinyl compound comprising the aqueous dispersion of the present invention has good standing stability, and is environmentally friendly because it is aqueous. When the vinyl compound is suspension-polymerized by using the dispersing agent of the present invention in combination with a conventionally known PVA polymer, the particle size distribution has almost the same particle size distribution with good reproducibility, and the particle size distribution is sharp. so,
Each of the particles is extremely high in industrial value such as vinyl chloride resin particles which are porous and excellent in uniformity, have a large specific gravity of filling, and have no adhesion of scale or the like.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-134003 (JP, A) JP-A-3-140303 (JP, A) JP-A-3-290403 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C08F 2 / 18,2 / 20

Claims (1)

(57) [Claims] An aqueous dispersion containing a polyvinyl ester polymer having an amino group, an ammonium group, a carboxyl group or a sulfonic acid group in a side chain of 0.1 to 10 mol% and a saponification degree of 70 mol% or less as a dispersoid. Aid for suspension polymerization of vinyl compounds.