JPS6335166B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a method for producing a vinyl chloride resin for paste, and more specifically, when used as a plastisol or an organosol, it provides a paste sol with low sol viscosity and good defoaming properties, and further improves transparency, hygroscopic whitening property, and electrical resistance. The present invention relates to a method for producing a vinyl chloride resin for paste that yields excellent molded products. Generally, plasticizer is added to vinyl chloride resin for paste.
When a paste sol is made by adding stabilizers, etc. and stirring and mixing these ingredients, if the paste sol is used while containing air bubbles, the transparency and surface texture will be deteriorated, which will impair the product value and also reduce the mechanical properties. It is usual to degas under reduced pressure during or after kneading. However, such operations are a waste of labor and time and have very poor work efficiency. Furthermore, when the paste sol obtained by the above method is molded by slush molding, coating method, dip molding, rotary molding, etc., if the sol viscosity is high, uniform molding may not be possible, or heat gelation may occur. The transparency of the molded product obtained by gelling is poor, so it cannot be used in fields where transparency is required, or even if the transparency is good immediately after heating and gelling, if it is left for a long time, moisture in the atmosphere may be removed. There have been problems such as the molded product becomes cloudy due to moisture absorption, which significantly impairs its commercial value, and the molded product has poor electrical resistance, making it unsuitable for applications such as electrical parts. The present invention eliminates these conventional drawbacks, and provides a paste sol that has a low sol viscosity and can be defoamed in a short time with a low degree of vacuum, and the molded product has excellent transparency and can be used for a long time. The present invention relates to a method for producing a vinyl chloride resin for paste that does not cause hygroscopic whitening even when left to stand and provides a vinyl chloride paste that has excellent electrical resistance. Vinyl chloride resin for paste is usually produced by emulsion polymerization using a water-soluble catalyst, but during polymerization, fatty acids, higher alcohol sulfuric esters, alkylbenzene sulfonic acids, dialkyl sulfosuccinic acids, α-olefin alkyl sulfonic acids, and polyoxyethylene are used. Anionic surfactants such as alkali metal salts such as alkyl ethers or ammonium salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene, polyoxypropylene block copolymers, sorbitan esters, and glycerin alkyl esters are used as emulsifiers. ing. The vinyl chloride polymer latex obtained by such a method is dried and manufactured by spray drying or the like. However, conventional manufacturing methods using such general emulsifiers have low sol viscosity, good defoaming properties of paste sol, excellent transparency of molded products, no whitening due to moisture absorption, and excellent electrical resistance. It is difficult to obtain a paste resin that provides such quality. As a result of intensive research on the above points, the inventor found that the viscosity of the paste sol is low, the defoaming property is good, the transparency of the molded product is excellent, and it does not whiten due to moisture absorption.
They discovered a method for producing paste resin that provides excellent electrical resistance. That is, in the present invention, when producing a vinyl chloride resin for paste, the monomer
Micro-suspension polymerization is carried out using 0.1 to 2.0 parts by weight of an alkali metal salt or ammonium salt of polyoxyethylene alkyl phenol ether sulfate represented by the following general formula () as an emulsifier per 100 parts by weight. The content is a method for producing a vinyl chloride resin for paste, which has a low viscosity as a paste sol, has good defoaming properties, and has excellent transparency, hygroscopic whitening properties, and electrical resistance of molded products. (However, M represents one type selected from alkali metals or ammonium groups, and R has 8 to 8 carbon atoms.
18 linear aliphatic hydrocarbon groups, preferably located in the para position. n represents an integer from 1 to 6. ) The alkali metal salts or ammonium salts of polyoxyethylene alkylphenol ether sulfates used in the present invention include fatty acids, higher alcohol sulfates, alkylbenzene sulfonic acids, dialkyl sulfosuccinic acids, α-olefin alkyl sulfonic acids, and polyoxyethylene alkyl ethers. It can be used as an emulsifier for the polymerization of vinyl chloride without any adverse effects, just like general anionic emulsifiers such as alkali metal salts or ammonium salts. That is, the paste sol prepared using the paste resin obtained by the present invention has a low sol viscosity;
Not only does it have good defoaming properties, and the molded products obtained by heating and gelling the paste sol have excellent transparency, water absorption and whitening properties, and electrical resistance, but they also eliminate deposits during polymerization using the emulsifiers mentioned above. It was found that this method also has the advantage that almost no aggregates (agglomerates in the polymerization solution and scale adhering to the walls of the polymerization vessel and the propeller) are generated. Specific examples of the emulsifier according to the present invention include monooxyethylene octyl phenol ether sulfate, monooxyethylene dodecyl phenol ether sulfate, monooxyethylene hexadecyl phenol ether sulfate, dioxyethylene octyl phenol ether sulfate, and dioxyethylene octyl phenol ether sulfate. Oxyethylene dodecyl phenol ether sulfate, dioxyethylene hexadecyl phenol ether sulfate,
Trioxyethylene octyl phenol ether sulfate, trioxyethylene dodecyl phenol ether sulfate, trioxyethylene hexadecyl phenol ether sulfate, tetraoxyethylene octyl phenol ether sulfate, tetraoxyethylene dodecyl phenol ether sulfate, tetraoxyethylene hexa Examples include alkali metal salts or ammonium salts such as decylphenol ether sulfate. The amount of emulsifier used in the present invention is preferably in the range of 0.1 to 2.0 parts by weight to monomer. The polymerization method employed in carrying out the present invention is as follows:
This is a polymerization method using a homogenization treatment using an oil-soluble catalyst (polymerization method using a microsuspension method, hereinafter referred to as microsuspension polymerization method). The present invention is not limited to the homopolymerization of vinyl chloride, but can also be applied to the production of copolymer resins by copolymerizing with vinyl acetate, vinyl propionate, acrylonitrile, etc., but a microsuspension polymerization method using vinyl chloride alone is effective. It is. In addition, during polymerization, general anionic emulsifiers such as alkali metal salts or ammonium salts such as fatty acids, higher alcohol sulfuric esters, alkylbenzenesulfonic acids, dialkylsulfosuccinic acids, α-olefin alkylsulfonic acids, and polyoxyethylene alkyl ethers, Alternatively, nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene block copolymer, sorbitan ester, and glycerin alkyl ester can be used in combination or dispersed within the range that does not impair the purpose of the present invention. Palmitic acid as a sex stabilizing agent,
Higher fatty acids such as stearic acid, higher alcohols such as dodecyl alcohol and stearyl alcohol, metal salts such as sodium sulfate and dibasic sodium phosphate, and hydrocarbons such as alkylbenzene and dodecane may be used in combination with the emulsifier of the present invention. You can also do it. EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. Example 1 [Polymerization by micro-suspension polymerization method (=polymerization method using macro-suspension method)] In a 300 stainless steel autoclave, 130 kg of ion-exchanged water, 100 kg of vinyl chloride monomer, α,
0.05 parts by weight of α′-azobisisobutyloberonitrile to monomer and 1.5 parts by weight of the emulsifier shown in Table 1 as an emulsifier to monomer were charged, and this polymerization solution was circulated using a homogenizer for 90 minutes to homogenize it. The temperature was raised to 50℃ to proceed with polymerization, and the polymerization pressure was 1 from the saturated vapor pressure of vinyl chloride at 50℃.
When the amount of Kg/cm ² decreased, polymerization was stopped and unreacted monomers were collected. The scale in the latex, the pellets, and the scale adhering to the walls of the polymerization vessel were collected, dried, and weighed. The obtained latex was spray-dried under the same conditions and then ground to obtain a vinyl chloride paste resin. Comparative example 1 (emulsion polymerization method) In a 300 glass lined autoclave,
After adding 130 kg of ion-exchanged water and 5 kg of uniform vinyl chloride seed polymer latex with a unit particle size of 0.4 μ as a polymer, remove oxygen, add 100 kg of vinyl chloride monomer, raise the temperature to 50°C, and reduce the total weight to 0.05 kg. of potassium persulfate (based on vinyl chloride monomer) was added continuously throughout the entire polymerization time. Furthermore, from the time the polymerization rate reached 10% to the end of polymerization, a total of 0.6 parts by weight of emulsifier was added to the vinyl chloride monomer at a rate of 0.025 parts by weight per hour.
It was added continuously for hours. When the polymerization pressure dropped by 1 kg/cm ² from the saturated vapor pressure of vinyl chloride at 50° C., the polymerization was stopped and unreacted monomers were recovered. In addition, aggregates in the polymerization solution, pellets, and scale adhering to the walls of the polymerization vessel were collected, dried, and weighed. A vinyl chloride paste resin was obtained from the obtained latex in the same manner as in Example 1. Sol viscosity and defoaming properties of the paste sols prepared using the resins obtained in Example 1 and Comparative Example 1, and transparency, water absorption whitening properties, and volume resistivity of the film obtained by heating and gelling the paste sol The percentage and amount of polymerized deposits were as shown in Table 1.

【table】

[Table] The composition of the paste sol used in each test shown in Table 1 is as follows. Paste resin 100 parts (by weight) DOP 70 parts (〃 ) Stabilizer 3 parts (〃 ) The methods for each test are as follows. (1) Sol viscosity Measured the paste sol with a BM type viscometer at 30±1℃ (2) Defoaming property 300 c.c. .Place the graduated cylinder in a decompression desiccator and reduce the pressure with a vacuum pump. When the paste sol bubbles in the graduated cylinder disappear, measure the degree of decompression in the desiccator with a mercury manometer and calculate the foamed volume. Find the foaming ratio by dividing by the volume of the paste sol before foaming. That is, the higher the degree of vacuum in the desiccator and the lower the foaming ratio, the better the defoaming performance. (3) Transparency The paste sol with the above composition was degassed and kneaded using a vacuum pump for 20 minutes, then poured onto a glass plate, coated with a 1 mm thick coating using a doctor knife, and gelled for 10 minutes in a hot air dryer at 170℃. to become The transparency of the obtained film is visually evaluated. (4) Water absorption whitening property The film used for transparency evaluation was taken into a size of 4 cm x 4 cm and immersed in distilled water kept at a temperature of 23°C ± 2°C, while comparing the transparency with the film that was not soaked. Observe the whitening state of the soaked film, measure the time from the start of soaking until whitening, and measure the water absorption rate after 24 hours. The water absorption rate is determined from the ratio of the original weight of the film to the weight increase before and after water absorption. That is, the longer the time until water absorption and whitening occurs and the lower the water absorption rate, the better the water absorption and whitening property. (5) Volume resistivity The film used for transparency evaluation was 120mm x 120mm.
Measure the size according to JIS-K6723 volume resistivity test for soft vinyl chloride compounds. That is, the larger the specific volume resistivity, the better the electrical resistance. From Table 1, the sol viscosity of the paste sol produced by the micro-suspension polymerization method using the sodium polyoxyethylene dodecyl phenol ether sulfate of the present invention as an emulsifier is the lowest, the defoaming property is good, the transparency of the film is It can be seen that the water absorption whitening property and specific volume resistivity are excellent, and the amount of scale during polymerization is small. Especially regarding sol viscosity,
The emulsion polymerization method used in the comparative example was too expensive and could not be used for molding by slushing, coating, or the like.

Claims (1)

[Claims] 1. When producing a vinyl chloride resin for paste, the general formula () is added as an emulsifier to 100 parts by weight of vinyl chloride monomer. (However, M represents one selected from alkali metals or ammonium groups, and R has 8 carbon atoms.
A vinyl chloride resin for paste, characterized by micro-suspension polymerization using 0.1 to 2.0 parts by weight of a compound represented by ~18 linear aliphatic hydrocarbon groups, n represents an integer of 1 to 6. manufacturing method.