JP3395230B2 - Method for producing paste PVC resin - Google Patents

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 paste vinyl chloride resin. More specifically, in the production of paste PVC resin in the seed micro suspension polymerization method, by adding a water-soluble polymerization initiator and conducting polymerization, production of paste PVC resin which gives a vinyl chloride foam having a uniform cell structure. It is about the method.

[0002]

2. Description of the Related Art A paste vinyl chloride resin (hereinafter abbreviated as paste vinyl chloride) is usually processed into a paste vinyl chloride sol by kneading it with a compounding agent such as a plasticizer, a diluent, a stabilizer, and the like. Various molded products can be obtained depending on the processing method. Among them, manufacturing a wall covering material by a method of coating paste vinyl chloride sol is currently one of the main uses of paste vinyl chloride.

A vinyl chloride wall covering material using paste vinyl chloride is manufactured, for example, as follows. First, the paste vinyl chloride sol is prepared by kneading the paste vinyl chloride with an appropriate amount of a plasticizer, a filler, a stabilizer, a foaming agent, a pigment, and if necessary, a diluent and the like. Next, the paste vinyl chloride sol is coated on a substrate such as flame-retardant paper or release paper, and then heated under a temperature condition that does not cause decomposition of the foaming agent to form a semi-gel state sheet. A predetermined color / pattern is printed on the thus obtained semi-gel-like sheet by a means such as direct printing or transfer, and heated in an oven at a predetermined temperature for a predetermined time to form a foam. Further, the surface of the foam is reheated with a far infrared heater or the like and embossed with an embossing roll to obtain a product.

The quality of the finished product is greatly affected by the cell structure of the foam before the step of embossing with an embossing roll. For example, the cells are large and rough, or uneven, especially a substrate such as flame-retardant paper. If the area is uneven and rough, the cells may be crushed after embossing, causing the product to be worn out, and the product with the desired thickness may not be obtained, or the embossing roll pattern may not fit into the product cleanly. It was

A conventionally known method for producing a paste vinyl chloride used for processing is to produce a vinyl chloride monomer and a vinyl chloride monomer which can be copolymerized with a vinyl chloride monomer alone or with a vinyl chloride monomer. Emulsion polymerization method in which the mixture is polymerized with deionized water, a surfactant, and a water-soluble polymerization initiator under gentle stirring, a seed emulsion polymerization method in which particles obtained by the emulsion polymerization method are used as seeds, and emulsion polymerization is performed. A vinyl monomer alone or a mixture of vinyl chloride and vinyl chloride monomer copolymerizable with vinyl chloride monomer is deionized water, a surfactant, and an emulsification aid such as a higher alcohol, if necessary, After mixing and dispersing the oil-soluble polymerization initiator with a homogenizer or the like,
There are a microsuspension polymerization method in which polymerization is performed under gentle stirring, and a seed microsuspension polymerization method in which polymerization is performed using a seed containing an oil-soluble polymerization initiator obtained by the microsuspension polymerization method.

When a foam is produced by using the paste PVC thus obtained, it is not possible to obtain a foam having a uniform cell structure from the paste PVC obtained by the conventional seed microsuspension polymerization method. It was difficult.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies on a method for producing paste PVC that gives a dense and uniform structure of foam cells in the seed microsuspension polymerization method, and as a result, a water-soluble polymerization initiator was found. The present invention has been achieved by the finding that paste vinyl chloride that sufficiently satisfies the above requirements can be obtained by adding and polymerizing the above.

[0008]

[Means for Solving the Problems] That is, according to the present invention, a vinyl chloride monomer alone or a mixture of a vinyl monomer and a vinyl chloride monomer copolymerizable with the vinyl chloride monomer is prepared by oil-soluble polymerization. Seed containing an initiator, in the presence of a surfactant,
The present invention relates to a method for producing paste vinyl chloride, which comprises adding a water-soluble polymerization initiator to carry out polymerization when producing paste vinyl chloride by an seed medium suspension polymerization method in an aqueous medium.

The present invention will be described in detail below.

Examples of the water-soluble polymerization initiator used in the present invention include sodium persulfate, potassium persulfate, ammonium persulfate and hydrogen peroxide. The polymerization temperature is
When the temperature is lower than the 10-hour half-life temperature of the water-soluble polymerization initiator, for example, potassium persulfate and sodium thiosulfate,
A combination of ammonium persulfate and ascorbic acid, hydrogen peroxide and a reducing agent such as ammonia may be used as a so-called redox type initiator.

The water-soluble polymerization initiator may be added all at once before the start of the polymerization, continuously during the polymerization, or at the final stage of the polymerization, but it is necessary to obtain a paste vinyl chloride resin which gives a uniform cell. It is preferable to charge all of them together before the start of polymerization. The amount of the water-soluble polymerization initiator used is 10 to 1000 ppm, preferably 50 to 500 ppm, based on 100 parts by weight of the monomer.

Specific examples of the surfactant to be used in the present invention include alkyl sulfate salts such as sodium lauryl sulfate, myristyl sulfate, and alkyl aryl sulfonates such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate. , Sodium dioctyl sulfosuccinate, sulfosuccinic acid ester salts such as sodium dihexyl sulfosuccinate, fatty acid salts such as ammonium laurate, potassium stearate, polyoxyethylene alkyl sulfate ester salts, anion surface active agents such as polyoxyethylene alkyl aryl sulfate ester salts Agents, sorbitan esters such as sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene alkyl phenyl Ethers, may be used those known conventionally such as nonionic surface active agents such as polyoxyethylene alkyl esters.

Further, as an emulsifying auxiliary agent used as necessary, higher alcohols such as cetyl alcohol and lauryl alcohol, higher fatty acids or esters thereof such as lauric acid, palmitic acid and stearic acid, aromatic hydrocarbons, higher hydrocarbons, etc. Examples thereof include aliphatic hydrocarbons and halogenated hydrocarbons such as chlorinated paraffin.

The vinyl compound copolymerizable with vinyl chloride in the present invention includes vinyl esters such as vinyl acetate, vinyl propionate, vinyl myristate, vinyl oleate and vinyl benzoate, acrylic acid, methacrylic acid and maleic acid. Acids, fumaric acid, unsaturated carboxylic acids such as cinnamic acid or anhydrides thereof, esters of acrylic acid methyl, ethyl, butyl, octyl, benzyl, etc., esters of methyl methacrylate, ethyl, butyl, octyl, benzyl, etc., Unsaturated carboxylic acid esters such as maleic acid ester, fumaric acid ester and cinnamic acid ester, vinyl ethers such as vinyl methyl ether, vinyl amyl ether and vinyl phenyl ether, ethylene, propylene,
It is one or more of ordinary vinyl compounds that can be radically copolymerized with vinyl chloride, such as monoolefins such as butenepentene, vinylidene chloride, styrene and its derivatives, acrylonitrile, methacrylonitrile and the like.

The production method used in the present invention contains vinyl chloride monomer alone or a mixture of vinyl chloride and vinyl chloride monomer copolymerizable with vinyl chloride, and an oil-soluble polymerization initiator. It is a seed microsuspension polymerization method in which a water-soluble polymerization initiator is added when a seed and a surfactant are polymerized in an aqueous medium at 30 to 80 ° C.

[0016]

Embodiments will be described in more detail below with reference to embodiments.

The seeds used in each of the following examples were manufactured as follows.

Preparation of seed containing oil-soluble polymerization initiator Deionized water 360 kg, vinyl chloride monomer 300 kg, lauroyl peroxide 5.7 kg in 1 m ³ autoclave
And 30 kg of a 15 wt% sodium dodecylbenzenesulfonate aqueous solution were charged, and this polymerization solution was circulated for 3 hours using a homogenizer, and after homogenization treatment, the temperature was changed to 45 ° C.
To proceed with the polymerization. After the pressure has dropped, the unreacted vinyl chloride monomer is recovered, particles with a solids content of 35% by weight have an average particle size of 0.55 μm and 2% by weight of polymer based lauroyl peroxide. A latex containing (hereinafter abbreviated as seed 1) was obtained.

Example 1 350 ml of deionized water, 400 kg of vinyl chloride monomer, 2 kg of 20 wt% sodium dodecylbenzenesulfonate as a surfactant, 47 kg of seed 1 and 4 wt% potassium persulfate in a 1 m ³ autoclave. 2 l of an aqueous solution was charged and the temperature of this reaction mixture was raised to 64 ° C to initiate polymerization. From the start of polymerization to the end of polymerization, 0.7 parts by weight of 20% by weight sodium dodecylbenzenesulfonate was continuously added to the vinyl chloride monomer. When the polymerization pressure drops 6 kg / cm ² from the saturated vapor pressure of vinyl chloride at 64 ° C, the polymerization is stopped,
Unreacted vinyl chloride monomer was recovered to obtain a vinyl chloride polymer latex. The obtained latex was spray-dried with a spray dryer at a hot air inlet temperature of 190 ° C. and an outlet temperature of 63 ° C., and then pulverized to obtain paste vinyl chloride.

[Example 2] A paste vinyl chloride was obtained in the same manner as in Example 1 except that 2 l of a 4 wt% potassium persulfate aqueous solution was continuously added from the start of the polymerization until the end of the polymerization.

Example 3 In a 1 m ³ autoclave, 350 l of deionized water, 400 kg of vinyl chloride monomer, 2 kg of 20 wt% sodium dodecylbenzene sulfonate as a surfactant, 47 kg of seed 1 and 0.1 wt% sulfuric acid. Copper aqueous solution 1 kg, 4 wt% potassium persulfate aqueous solution 2 l
The temperature of the reaction mixture was raised to 48 ° C., and 30 kg of a 0.1 wt% ascorbic acid aqueous solution was continuously added during the entire polymerization time. Furthermore, 0.7 to the vinyl chloride monomer from the start of polymerization to the end of polymerization
Parts by weight of 20% by weight sodium dodecylbenzene sulfonate were added continuously. When the polymerization pressure dropped 2 kg / cm ² from the saturated vinyl chloride vapor pressure at 48 ° C., the polymerization was stopped and unreacted vinyl chloride monomer was recovered to obtain a vinyl chloride polymer latex. The latex thus obtained was heated with a spray dryer at a hot air inlet temperature of 158 ° C. and an outlet temperature of 5
After spray drying at 5 ° C., the product was pulverized to obtain paste vinyl chloride.

[Comparative Example 1] A paste vinyl chloride was obtained in the same manner as in Example 1 except that 2 l of a 4 wt% potassium persulfate aqueous solution was not charged.

[Comparative Example 2] A paste vinyl chloride was obtained in the same manner as in Example 3 except that 2 l of a 4 wt% potassium persulfate aqueous solution was not charged.

The paste vinyl chlorides obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were foamed according to the following composition and processing conditions.
Embossed by embossing.

Table 1 shows the results of polymerization prescriptions, foaming ratios, thickness reduction rates after embossing, and cell structures of Examples 1 to 3 and Comparative Examples 1 and 2.

(Compounding) Paste PVC 100 parts DOP 40 parts Calcium carbonate 50 parts Stabilizer 3 parts Foaming agent 6 parts Pigment (TiO ₂ ) 15 parts Diluent 5 parts (processing conditions) -foaming Paste salt prepared by the above composition A sol having a thickness of 0.25 mm was coated on flame-retardant paper and heated in an oven heated to 140 ° C. for 40 seconds to prepare a semi-gel sheet. After cooling this sheet to room temperature, 2
It was heated for 60 seconds in an oven heated to 10 ° C. to obtain a foam.

The expansion ratio and cell structure of the obtained foam were determined by the following methods. (1) Expansion ratio The thickness of the semi-gel sheet and the thickness of the foam were measured and calculated from the following formula. Foaming ratio = foam thickness (mm) / semi-gel sheet thickness (mm) (2) Cell structure The cross section of the foam was observed and evaluated. ○: Foam cells are small and uniform △: Foam cells are large but uniform ×: Foam cells are large and rough (especially in the vicinity of the substrate) ・ Embossing the obtained foam with a far infrared heater The surface of the body was heated to 150 ° C. and embossed with an embossing roll.

The thickness reduction rate of the foamed product after embossing and the embossing amount were determined by the following methods.

(1) Thickness reduction rate The foam and the thickness after embossing were measured and calculated by the following equation. Thickness reduction rate (%) = foam thickness (mm) -thickness after embossing (mm) / foam thickness (mm) x 100 (2) Embossed sheet The embossed sheet was observed and evaluated. ○: All embossing roll patterns are reproduced △: Fine pattern of embossing rolls is not clear ×: The entire pattern of embossing rolls is not clear

[0030]

[Table 1]

[0031]

Industrial Applicability According to the present invention, a paste vinyl chloride having a dense and uniform cell structure of a foam can be obtained.

Claims (2)

(57) [Claims] 1. A seed or a surfactant containing an oil-soluble polymerization initiator, which comprises a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and a vinyl chloride monomer copolymerizable with the vinyl chloride monomer. In the presence of the above, when producing a paste vinyl chloride resin in an aqueous medium by a seed microsuspension polymerization method, a water-soluble polymerization initiator is added to carry out polymerization, and a method for producing a paste vinyl chloride resin. 2. The amount of the water-soluble initiator added is 10 to 1 with respect to the vinyl chloride monomer alone or the mixture of the vinyl chloride monomer and the vinyl chloride monomer copolymerizable with the vinyl chloride monomer.
The method according to claim 1, which is 000 ppm.