JP2764650B2 - Polymer scale adhesion inhibitor and method for preventing adhesion of polymer scale - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a polymer scale antiadhesive for polymerizing vinyl chloride monomers or monomer mixtures based on vinyl chloride, and polymer scale adhesion. Prevention methods.

[Conventional technology]

In a method of producing a polymer by polymerizing a monomer in a polymerization vessel, there is a known problem that the polymer adheres as a scale to an inner wall surface of the polymerization vessel.

When the polymer scale adheres to the inner wall of the polymerization vessel, the yield of the polymer decreases, the cooling capacity of the polymerization vessel decreases, and the quality of the product polymer decreases due to the detachment of the attached polymer scale and mixing into the product. And the like, and further, a great deal of labor and time are required for removing the polymer scale. In addition, because the polymer scale contains unreacted monomers, workers may be exposed to it and cause physical disability.

Conventionally, in the polymerization of a monomer having an ethylenic double bond, as a method of preventing the adhesion of polymer scale to the inner wall surface of the polymerization vessel, a suitable substance is used as a polymer scale adhesion inhibitor as an inner wall surface of the polymerization vessel. There is known a method of applying the composition to a surface.

Suitable substances as the polymer scale adhesion inhibitor include, for example, dyes and pigments described in JP-B-45-30835.

[Problems to be solved by the invention]

By the way, recently, from the viewpoint of appearance and mechanical properties, the degree of coloring, fish eye, bulk specific gravity, gelation speed, initial coloring, and heat stability of molded articles of vinyl chloride polymer, particularly transparent sheets and bottles, have been improved. There is an increasing demand from users for quality improvement for various physical properties such as properties. Therefore, development of a polymer scale adhesion inhibitor which does not adversely affect the physical properties of the obtained polymer is desired.

However, when the above dyes and pigments are used as a polymer scale adhesion inhibitor, the following (i) and (i)
As shown in i), it adversely affects various physical properties of the product polymer.

(I) Since the coating film comprising the polymer scale adhesion inhibitor is easily dissolved, the resulting product polymer is colored or the bulk specific gravity is reduced.

(Ii) Since the adhesion of the coating film to the inner wall surface of the polymerization vessel is weak, the coating film peels off during polymerization and partially disappears, and the scale adheres to the coating film. When processed into a molded article, it causes an increase in fish eyes.

[Means for solving the problem]

An object of the present invention is to always effectively prevent adhesion of a polymer scale in polymerization or copolymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride, and the degree of coloring is remarkably small. Another object of the present invention is to provide a polymer scale adhesion preventive agent and a method for preventing polymer scale adhesion, which can provide a high-quality product polymer having very few fish eyes in a molded product.

That is, the present invention provides a vinyl chloride monomer or vinyl chloride containing (A) a naphthoquinone-based natural dye and (B) a polyvinyl alcohol having a saponification degree of 70 mol% or more and less than 95 mol%. The present invention provides a polymer scale adhesion inhibitor for the polymerization of a monomer mixture mainly composed of

Further, the present invention is a method for preventing adhesion of a polymer scale in the polymerization of a vinyl chloride monomer or a monomer mixture containing vinyl chloride as a main component in a polymerization vessel. Provided is a method for preventing adhesion of a polymer scale, comprising a step of performing the polymerization in a polymerization vessel in which a coating film containing both the components (A) and (B) is formed.

(A) Naphthoquinone-based natural dye The naphthoquinone-based natural dye which is the component (A) of the polymer scale adhesion inhibitor of the present invention includes 6-methyl-1,4
- naphthoquinone, 2-methyl-1,4-naphthoquinone, Lawson, juglone, Plumbagin, alkannin, echinochrome chrome A, Supinokuromu A, vitamin K _1, vitamin K _2, naphthazarin, 2,3 divinyl mud carboxymethyl naphthalate The phosphorus, 2-methylnaphthazaline, 2-hydroxynaphthazaline, 2-hydroxy-3-methylnaphthazaline, 2-
Hydroxy-3-ethylnaphthazaline, 2-hydroxy-3-acetylnaphthazaline, 2,7-dimethylnaphthazaline, alkanna, shikonin, acetylshikonin, isobutylshikonin, β, β′-dimethylacrylshikonin, β- Examples include hydroxyisowarel shikonin, teracrylic shikonin, and derivatives thereof. These can be used alone or in combination of two or more, and the combination is appropriately selected.

Among these naphthoquinone-based natural pigments, particularly preferred are shikonins such as shikonin, acetyl shikonin, isobutyl shikonin, β, β′-dimethylacryl shikonin, β-hydroxyisowarrel shikonin, teracrylic shikonin, and naphthazarin, 2 , 3-Dihydroxynaphthazaline, 2-methylnaphthazaline, 2-hydroxynaphthazaline, 2-hydroxy-3-methylnaphthazaline, 2hydroxy-3-ethylnaphthazaline, 2-hydroxy-3-acetyl Naphthazalines such as naphthazarin and 2,7-dimethylnaphthazaline. These shikonins and naphthazalines can be obtained by extracting purple grass roots with an organic solvent.

(B) Polyvinyl Alcohol The polyvinyl alcohol which is the component (B) of the polymer scale adhesion inhibitor of the present invention needs to have a saponification degree of 70 mol% or more and less than 95 mol%, and in particular, a saponification degree of 78 mol%
It is preferable that the content be at least 90 mol% and less than 90 mol%. Also,
The higher the degree of polymerization of polyvinyl alcohol, the better, in order to increase the persistence on the coating film forming surface, the monomer resistance, and the like.

The polymer scale adhesion inhibitor of the present invention contains a solvent, if necessary, in addition to the above components (A) and (B). In addition, in order to enhance the scale prevention effect, the polymer scale adhesion preventive includes various hydrophilic high molecular compounds such as anionic, chaotic and amphoteric, surfactants, amine compounds, phenol group-containing compounds, and quinone compounds. Compounds and the like can also be added.

The polymer scale adhesion inhibitor of the present invention is, for example, formed as a coating film on the inner wall surface of a polymerization vessel to prevent scale adhesion on the inner wall surface of the polymerization vessel. Usually, when the coating film is formed on the inner wall surface of a polymerization vessel, it is used in a solution state, that is, as a coating solution.

Preparation of Coating Solution The coating solution as described above is prepared by adding the components (A) and (B) to an appropriate solvent.

Examples of the solvent used for preparing such a coating solution include water; methanol, ethanol, propanol, butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and 3-methyl- 1
Alcohol solvents such as butanol, 2-methyl-2-butanol and 2-pentanol; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone;
Ester solvents such as methyl formate, ethyl formate, methyl acetate, methyl acetoacetate; ether solvents such as 4-methyldioxolane, ethylene glycol diethyl ether; furans; aprotic solvents such as dimethylformamide, dimethyl sulfoxide, acetonitrile, etc. Is mentioned. These are used singly or as a mixture of two or more solvents.

The total concentration of the components (A) and (B) in the coating solution is not particularly limited as long as the coating amount per unit area described below can be obtained, but is usually 0.001 to 20% by weight, preferably 0.005% by weight.
About 5% by weight. The content ratio of the component (A) to the component (B) in the coating solution is usually 0.1 to 5,000 parts by weight, preferably 1 to 100 parts by weight, per 100 parts by weight of the component (A).
0 parts by weight. If the amount of the component (B) is too large or too small as compared with the component (A), the effect of preventing the adhesion of scale by using the components (A) and (B) in combination may not be obtained.

The pH of the coating solution is not particularly limited. If necessary, a pH adjuster can be added. Its pH
Examples of the modifier include sulfuric acid, phosphoric acid, acetic acid, oxalic acid, lactic acid, p-toluenesulfonic acid, phytic acid, thioglycolic acid, glycolic acid, sodium hydroxide, potassium hydroxide, aqueous ammonia, ethylenediamine, and the like. Used as appropriate.

To form a coating film on the inner wall of the polymerization vessel using the coating solution adjusted as described above, first, apply the coating solution to the inner wall surface of the polymerization vessel, and then, for example, from room temperature to 100 ° C After sufficiently drying in the temperature range up to, and further washing with water as needed. In this case, since a coating film is formed on the inner wall surface of the polymerization vessel, adhesion of the polymer scale to the inner wall surface of the polymerization vessel is prevented.

Further, the coating liquid is preferably applied not only to the inner wall surface of the polymerization vessel but also to other parts where the monomer comes into contact during the polymerization, and it is preferable to form a coating film thereby. For example, stirring blades, stirring shafts, baffles, condensers,
It is better to form a coating film on the header, search coil, bolt, nut and the like by applying the coating liquid. In particular, a coating film should usually be formed on the stirring blade, stirring shaft, and baffle by applying the coating solution. The application of the coating solution to these sites to form a coating film may be performed in the same manner as when forming a coating film on the inner wall of the polymerization vessel.

More preferably, the coating liquid is a part other than the part where the monomer comes into contact during the polymerization, a part where the polymer scale may adhere, for example, an unreacted monomer recovery system device and piping. It is preferable that the coating liquid is applied to an inner surface to form a coating film. More specifically, such portions include inner surfaces of a monomer distillation column, a condenser, a monomer storage tank, a valve, and the like. The formation of the coating film at these sites may be performed in the same manner as the case of forming the coating film on the inner wall of the polymerization vessel.

In this way, when a coating film is formed at a site where the monomer comes into contact during polymerization and at a site where other polymer scale may be attached, adhesion of the polymer scale to those sites is prevented. You.

The method for applying the coating solution to the inner wall surface of the polymerization vessel is not particularly limited. Examples thereof include brush coating, spray coating, and a method in which the polymerization vessel is filled with the coating solution and then withdrawn. Automatic coating methods described in 61001, 55-36288, JP-B-56-501116, JP-B-56-501117, JP-A-59-11303 and the like can also be used.

Further, the method of drying the surface that is wet by the application of the coating liquid is not limited, and for example, the following method can be used. That is, after the application of the coating solution, a method of applying an appropriately heated warm air to the application surface,
Alternatively, a method in which the inner wall surface of the polymerization vessel to be coated with the coating solution and other surfaces are previously heated to, for example, 30 to 80 ° C., and the coating solution is directly applied to the heated surface can be used. After the application surface is dried, the application surface is washed with water as needed.

Thus the coating film obtained by a coating amount per unit area, usually 0.001 g / m ² or more, and particularly preferably 0.05 to 2 g / m ^2.

The above-mentioned coating operation may be performed for every one to several dozen batches of polymerization. Since the formed coating film has high durability and maintains the action of preventing the adhesion of the polymer scale, it is not always necessary to perform the coating for each batch of polymerization. For this reason, the productivity of the product polymer is improved.

Polymerization As described above, a coating film is formed by applying a coating treatment to the inner wall of the polymerization vessel, and preferably to a portion where the monomer comes into contact during polymerization, and then the polymerization is carried out in the polymerization vessel by a conventional method. Do. That is, in addition to the monomer and the polymerization initiator (catalyst), if necessary, a polymerization medium such as water, and a dispersant such as a suspending agent, a solid dispersant, a nonionic, or an anionic emulsifier are charged. The polymerization is carried out by a conventional method.

The monomer to be polymerized by applying the method of the present invention is a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a copolymerizable monomer of vinyl chloride. Examples of monomers copolymerizable with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid, methacrylic acid, and their esters or salts; maleic acid, fumaric acid, and their esters or anhydrides. Stuff;
Styrene, acrylonitrile, vinylidene halide,
Vinyl ether and the like.

Further, the type of polymerization to which the method of the present invention is applied is not particularly limited, but particularly in suspension polymerization, particularly in suspension polymerization of a polymerization system containing partially saponified polyvinyl alcohol and / or completely saponified polyvinyl alcohol as a dispersant. Shows effective scale prevention effect.

Hereinafter, a general polymerization method will be specifically described by taking the case of suspension polymerization as an example.

First, water and a dispersant are charged into a polymerization vessel, and then a polymerization initiator is charged. Next, the inside of the polymerization vessel was evacuated to 0.1 to 760
After reducing the pressure to mmHg, the monomer was charged (at this time, the internal pressure of the polymerization vessel was usually 0.5 to 30 kgf / cm ² · G).
Polymerizes at 0-80 ° C. During the polymerization, if necessary, water,
One or more of a dispersant and a polymer initiator are added. In the polymerization, the difference between the inlet temperature and the outlet temperature of the cooling water flowing into and out of the jacket provided around the polymerization reactor when the internal pressure of the polymerization reactor is reduced to 0 to 7 kg f / cm ^2. When it has disappeared (that is, when the heat generated by the polymerization reaction has disappeared), it is determined to be completed. Water to be charged at the time of polymerization, a dispersant and a polymerization initiator are usually 20 to 500 parts by weight of water, 100 parts by weight of a monomer, and 0.01 parts by weight of a dispersant.
To 30 parts by weight, and 0.01 to 5 parts by weight of a polymerization initiator.

When polymerization is performed by applying the method for preventing adhesion of a polymer scale of the present invention, adhesion of the polymer scale can be prevented regardless of the material such as the inner wall surface of the polymerization vessel. Even when the polymerization is carried out in a steel polymerization vessel, a glass-lined polymerization vessel, or the like, the adhesion of the polymer scale can be prevented.

Those added to the polymerization system can be used without any restrictions. That is, for example, t-butyl peroxy neodecanoate, bis (2-ethylhexyl) peroxy dicarbonate, 3,5,5-trimethylhexanoyl peroxide, α-cumyl peroxy neodecanoate, cumene hydroper Oxide, cyclohexanone peroxide, t-butyl peroxypivalate, bis (2-ethoxyethyl) peroxydicarbonate,
Benzoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, α, α′-azobisisobutyronitrile, α, α′-azobis-2,4-dimethylvaleronitrile , Potassium peroxodisulfate, ammonium peroxodisulfate, polymerization initiators such as p-menthane hydroperoxide; partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, polyacrylic acid, a copolymer of vinyl acetate and maleic anhydride, hydroxypropyl methylcellulose Suspending agents such as cellulose derivatives such as cellulose, natural or synthetic polymer compounds such as gelatin; solid dispersants such as calcium phosphate and hydroxyapatite; sorbitan monolaurate, sorbitan triolate, polyoxyethylene Nonionic emulsifiers such as renalkyl ether; anionic emulsifiers such as sodium alkylbenzenesulfonate such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate; sodium dioctyl sulfosuccinate; fillers such as calcium carbonate and titanium oxide; tribasic lead sulfate Stabilizers such as calcium stearate, dibutyltin dilaurate, dioctyltin methylcaptide; lubricants such as rice wax, stearic acid and cetyl alcohol; plasticizers such as DOP and DBP; t
-In a polymerization system in which mercaptans such as dodecyl mercaptan and a chain transfer agent such as trichloroethylene are present, the method of the present invention can effectively prevent adhesion of polymer scale.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. Experiments marked with * in Table 1 below
No. is a comparative example, and other experiment Nos. Are examples of the present invention.

Example 1 Polymerization was carried out as follows using a stainless steel polymerization vessel equipped with a stirrer and having an internal volume of 1000.

In each experiment, first, the component (A) (natural naphthoquinone dye) and the component (B) (partially saponified polyvinyl alcohol) were dissolved in a solvent so as to have a total concentration as shown in Table 1, and then the pH was measured. Then, each coating solution was adjusted by adding a pH adjuster as needed. Next, this coating solution was applied to the inner wall of the polymerization vessel, the stirring shaft, the stirring blade, and other parts where the monomer was in contact with the polymerization.
After heating and drying for a minute to form a coating film, the film was washed with water.

However, Experiment No. 101 is a comparative example in which no coating liquid was applied, and Experiment Nos. 102 and 103 were comparative examples in which a coating liquid containing only one of the component (A) and the component (B) was applied. Further, Experiments Nos. 108 and 116 were conducted using C.I.
I. This is a comparative example using Acid Black 2 as the component (A), and Experiment No. 117 is a comparative example in which the saponification degree of (B) the partially saponified polyvinyl alcohol is less than 70%.

The types of the components (A) and (B) in the coating solution used in each experiment, the weight ratio (A) / (B) of the components (A) and (B) in the coating solution, and the type of solvent used Table 1 shows the total concentration of (A) + (B) in the coating solution, the type of pH adjuster added, and the pH of the coating solution.

Thereafter, 400 kg of water, 200 kg of vinyl chloride, 250 g of partially saponified polyvinyl alcohol, 25 g of hydroxypropylmethylcellulose and 25 g of diisopropyl peroxydicarbonate were charged into the polymerization vessel in which the coating treatment was performed to form a coating film, and the mixture was stirred. Polymerization was performed at 57 ° C. for 6 hours.

After the polymerization was completed, the amount of polymer scale adhered to the inner wall of the polymerization vessel (the amount of polymer scale adhered) was measured.

Further, the whiteness of the polymer obtained in each experiment No. was measured by the following method.

100 parts by weight of polymer, stabilizer TS-101 (Akishima Chemical Co., Ltd.) 1
Parts by weight and 0.5 parts by weight of C-100J (manufactured by Katsuta Kako Co., Ltd.) and 50 parts by weight of a plasticizer DOP are mixed with a two-roll mill for 1 part.
After kneading at 60 ° C. for 5 minutes, a sheet having a thickness of 1 mm was formed. Next, this sheet was placed in a mold frame of 4 cm × 4 cm × 1.5 cm (thickness), and heated and pressed at 160 ° C. and 65 to 70 kg f / cm ² to prepare a measurement sample. About this measurement sample, JI
The lightness index L in the color difference formula of Hunter described in S Z8730 (1980) was determined, and the larger the L value, the higher the whiteness.

 The L value was determined as follows.

In accordance with the description of JIS Z8722, the stimulus value Y of the XYZ color system is calculated by the standard light C and the stimulus value direct reading method using a photoelectric colorimeter (Z-1001DP colorimeter manufactured by Nippon Denshoku Industries Co., Ltd.). I asked. The geometric conditions of illumination and light reception include:
The condition d described in Section 4.3.1 of JIS Z8722 was adopted.

Next, L was determined by the equation: L = 10Y1 ^{/ 2} described in JIS Z8730 (1980).

Furthermore, the fish eyes when the polymer obtained in each experiment No. was formed into a sheet were measured by the following method.

Using a 6-inch roll, a mixture prepared at a blending ratio of 100 parts by weight of polymer, 50 parts by weight of DOP, 1 part by weight of dibutyltin dilaurate, 1 part by weight of cetyl alcohol, 0.25 part by weight of titanium oxide, and 0.05 part by weight of carbon flux was used. At 7
After kneading for minutes, the sheet was formed into a sheet having a thickness of 0.2 mm, and the number of fish eyes contained per 100 cm ^{2 of the} obtained sheet was examined by a light transmission method.

 Table 1 shows the measurement results.

In each experiment No., a commercially available product shown in Table A below was used as (B) partially saponified polyvinyl alcohol.

Experiment Nos. 101, 108, 116, 104, 105, 109, 110, 112, 113
Was measured using a bulk specific gravity measuring device (manufactured by Kuramochi Kagaku Kikai Seisakusho; Kasa specific gravity measuring device) in accordance with the description in JIS K6721 section 3.3. The results are shown in Table 2.

[Effects of the Invention] According to the present invention, in the polymerization or copolymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride, adhesion of a polymer scale can always be effectively prevented, and the present invention The coating film formed by the polymer scale adhesion inhibitor does not peel off or dissolve in the polymerization system. Therefore, when the present invention is applied, there is no risk that the product polymer will be colored, whereby a high whiteness of L value of 70 or more can be obtained, and fish eyes in the molded product are significantly less, and It is possible to produce a high quality product polymer whose bulk specific gravity is not reduced.

Further, according to the present invention, regardless of the type of the monomer and the polymerization initiator used, the type of polymerization, and the polymerization conditions such as the material of the inner wall of the polymerization vessel, the adhesion of the polymer scale is effectively prevented. can do. In particular, in suspension polymerization,
Prevents polymer scale adhesion even when using a polymerization vessel such as a stainless steel polymerization vessel or a glass-lined polymerization vessel, or when using a polymerization initiator with strong oxidizing power. can do.

Therefore, when polymerization is performed by applying the present invention, it is not necessary to remove the polymer scale for each polymerization, thereby improving the productivity and producing a high quality product polymer. be able to.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Masahiro Usu, 1-figure Towada, Kazu-gun, Kashima-gun, Ibaraki Prefecture Inside the PVC Research Laboratory, Shin-Etsu Chemical Co., Ltd. 1 Shin-Etsu Chemical Co., Ltd. PVC Research Laboratory (56) References JP-A-4-108802 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08F 2/00-2 / 60

Claims (2)

(57) [Claims] 1. A vinyl chloride monomer or a monomer mixture mainly comprising vinyl chloride, comprising (A) a naphthoquinone-based natural dye and (B) polyvinyl alcohol having a saponification degree of 70 mol% or more and less than 95 mol%. Polymer scale adhesion inhibitor for polymerization. 2. A method for preventing adhesion of a polymer scale in polymerization of a vinyl chloride monomer or a monomer mixture mainly composed of vinyl chloride in a polymerization vessel. A polymer scale having a step of performing the polymerization in a polymerization vessel in which a coating film containing A) a naphthoquinone-based natural dye and (B) a polyvinyl alcohol having a saponification degree of 70 mol% or more and less than 95 mol% is formed. How to prevent adhesion.