JPH0859711A - Production of vinyl chloride-based polymer - Google Patents

Abstract

PURPOSE: To provide a method for producing a vinyl chloride-based polymer for pastes by which the amount of an emulsifying agent used is minimized to afford an aqueous dispersion having a high polymer concentration as much as possible by a seeding microsuspension (co)polymerization method. CONSTITUTION: This method for producing a vinyl chloride-based polymer is to use an oil-soluble polymerization initiator and carry out the microsuspension (co)polymerization of vinyl chloride alone or the vinyl chloride and further a monomer copolymerizable therewith (hereinafter referred to as a vinyl chloride-based monomer) in the presence of a straight-chain aliphatic higher alcohol in an amount of 1.0-6.0 pts.wt. based on 100 pts.wt. monomer(s) in an aqueous medium containing an anionic emulsifying agent in the method for producing the vinyl chloride-based polymer by performing the seeding microsuspension (co)polymerization of the vinyl chloride-based monomer(s) in the presence of a seed polymer.

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a vinyl chloride polymer. More specifically, it relates to a method for producing a vinyl chloride polymer for paste by seeding fine suspension polymerization. Conventionally, vinyl chloride-based polymers for pastes are generally prepared by emulsion-polymerizing vinyl chloride-based monomers using a water-soluble polymerization initiator, or by vinyl chloride-based monomers being preliminarily machined. It is manufactured by a fine suspension polymerization method in which it is uniformly homogenized, dispersed in an aqueous medium, homogenized, and then suspension polymerized. Further, there is a so-called seeding polymerization method using a seed polymer in the above-mentioned polymerization method, that is, a seeding fine suspension polymerization method and a seeding emulsion polymerization method. The seeded fine suspension polymerization method is a fine suspension polymerization in which vinyl chloride monomer, water, emulsifier, oil-soluble polymerization initiator and other polymerization aids are homogenized under high shear and then polymerized under stirring. An aqueous dispersion of a so-called seed polymer containing an oil-soluble polymerization initiator is produced by a legal method, and subsequently, a vinyl chloride-based monomer is added to the aqueous dispersion,
In this method, water and an emulsifier are added and the mixture is polymerized with stirring to produce an aqueous dispersion of fine vinyl chloride polymer particles. JP-B-45-28790 discloses that an aqueous dispersion of a seed polymer is produced by a fine suspension polymerization method using an anionic emulsifier, and subsequently 100 parts by weight of an anionic emulsifier as a monomer by continuous polymerization. A method of obtaining a latex having a polymer concentration of about 55% by a fine suspension polymerization method at a temperature of 52 ° C. by using 1.2 parts by weight is described. In JP-A-5-271313, an aqueous dispersion of a seed polymer is produced using an anionic emulsifier or a nonionic emulsifier, and subsequently a polymer concentration of 40 is obtained by a so-called seed emulsion polymerization method using a water-soluble polymerization initiator. A method is described for obtaining an aqueous dispersion of the order of%. In order to form a vinyl chloride resin for paste from the latex, it is necessary to spray-dry the latex first. Therefore, it is desirable that the latex has a high concentration. However, when the latex has a high concentration, the vinyl chloride polymer particles are likely to associate with each other, that is, become unstable. Therefore, in order to prevent this, a large amount of emulsifier is used. However, if a large amount of an emulsifier is mixed in the vinyl chloride polymer, the water whitening resistance of the vinyl chloride resin paste is lowered, which is not preferable.
Then, the polymerization method which suppresses the usage-amount of an emulsifier as much as possible and manufactures an aqueous dispersion liquid whose polymer concentration is as high as possible is provided. In the present invention, vinyl chloride alone or vinyl chloride and a monomer copolymerizable therewith (hereinafter referred to as vinyl chloride-based monomer) are added in the presence of a seed polymer. In the method for producing a vinyl chloride-based polymer in which seeding fine suspension polymerization is carried out, the seed polymer comprises a vinyl chloride-based monomer as the monomer 1
1.0 to 0.003 parts by weight of linear aliphatic higher alcohol
Production of a vinyl chloride polymer characterized by being a polymer obtained by finely suspension polymerizing in an aqueous medium containing an anionic emulsifier using an oil-soluble polymerization initiator in the presence of 6.0 parts by weight. Is the way. In the present invention, the vinyl chloride-based monomer is vinyl chloride alone or a monomer mixture of vinyl chloride and a monomer copolymerizable therewith. Other monomers besides vinyl chloride include olefins such as ethylene, propylene and α-butene, vinyl acetates such as vinyl acetate, vinyl propionate, vinyl laurate and vinyl stearate, acrylic acid, methacrylic acid and Unsaturated acids and their esters such as itaconic acid, vinyl ethers such as methyl vinyl ether, octyl vinyl ether and lauryl vinyl ether,
Maleic acid, fumaric acid, their anhydrides or their esters, aromatic vinyls, unsaturated nitriles and the like can be mentioned. The seeded fine suspension polymerization method used in the present invention is
A seed polymer containing a polymerization initiator obtained by a fine suspension polymerization method in advance is a method for finely suspension polymerizing a further monomer using this seed polymer, which is itself a method. It need not be more specific and may be a well-known one. As a fine suspension polymerization method for obtaining a seed polymer, a well-known fine suspension polymerization method is used. That is, it is a method in which a vinyl chloride-based monomer is homogenized with an aqueous medium containing an oil-soluble polymerization initiator and an anionic emulsifier in advance using a homogenizer and then polymerized. In the present invention, in particular, a linear aliphatic higher alcohol is present at this time. The linear aliphatic higher alcohol is a linear aliphatic higher alcohol having 10 to 18 carbon atoms, and specifically, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, cetyl alcohol, Stearyl alcohol is exemplified. The amount is 1.0 to 6.0 parts by weight per 100 parts by weight of the monomer. If this amount is too small, the latex is likely to agglomerate during the seeding fine suspension polymerization, and if too large, no effect can be expected for the amount. As the oil-soluble polymerization initiator used in the fine suspension polymerization method for obtaining a seed polymer, among those usually used for the polymerization of vinyl chloride-based monomers, its 10-hour half-life temperature is 30.
Those of ˜55 ° C. are suitable. In addition, if the 10-hour half-life temperature is too low, the seed polymer is easily decomposed and the activity is lost during the seeding fine suspension polymerization. Examples of the oil-soluble polymerization initiator include di-2-
Ethylhexyl peroxydicarbonate (10 hour half-life temperature 45 ° C), 2,4-dichlorobenzoyl peroxide (54 ° C), di-1-methylheptyl peroxydicarbonate (44 ° C), t-butyl peroxyheptanoate (50 ° C.), t-butyl peroxyneohexanoate (54 ° C.) and the like, and these are used alone or in combination of two or more kinds. The amount of the vinyl chloride-based monomer is 10
It is 0.1 to 1 part by weight per 0 part by weight. If this amount is too small, the polymerization during seeding fine suspension polymerization will be delayed, and if it is too large, it will be difficult to control the polymerization of fine suspension polymerization itself to obtain a seed polymer. The anionic emulsifier used in the fine suspension polymerization method for obtaining a seed polymer may be a well-known one, for example, alkali metal salts and ammonium salts of higher alcohol sulfuric acid esters, alkali metal salts and ammonium salts of alkylbenzene sulfonic acid, etc. And one or more of these are used. The amount of the emulsifier used is 100% of the monomer.
0.3 to 2.0 parts by weight, especially 0.5 to
1.5 parts by weight is preferred. The water forming the aqueous medium is not in a very specific amount, but is about 50 to 300 per 100 parts by weight of the monomer.
Parts by weight. In addition to the above, a particle size adjusting agent such as sodium sulfate and sodium bicarbonate, a chain transfer agent, or a polymerization inhibitor can be used as a polymerization aid forming an aqueous medium. In the fine suspension polymerization, the temperature is from 20 ° C to 5 ° C.
0 ° C. Although this temperature depends on the kind of the oil-soluble polymerization initiator to be used, if it is too high, the activity at the time of the next seeded fine suspension polymerization is lowered, which is not preferable. The seeded fine suspension polymerization is a method in which a vinyl chloride-based monomer to be newly polymerized, an anionic emulsifier and, if necessary, water are added to an aqueous medium containing the above-mentioned seed polymer and the mixture is polymerized under stirring. is there. These quantitative ratios include, finally, that is, 5 to 20 parts by weight of the seed polymer per 100 parts by weight of the vinyl chloride-based monomer, including those involved in the aqueous medium containing the above-mentioned seed polymer, anionic property. Emulsifier 0.3-1.
50 to 85 parts by weight of the aqueous medium containing 0 parts by weight. If the amount of the seed polymer is insufficient, the polymerization rate becomes low, and conversely, if the amount is too large, the proportion of seeded fine suspension polymerization becomes low, and in any case, the productivity becomes low. The type of anionic emulsifier in the seeded fine suspension polymerization is the same as described above. If this amount is too small, the emulsified state of the aqueous medium will be unstable, and if it is too large, the water-whitening resistance will deteriorate, among other properties of the paste processed product made of the obtained polymer. Therefore, the vinyl chloride-based monomer 10
The anionic emulsifier per 0 parts by weight is preferably 0.
5 to 1.0 parts by weight. If the amount of water forming the aqueous medium in the seeded fine suspension polymerization is too small, the concentration of the monomer or polymer may be too high and may cause aggregation during the polymerization. Is not achieved. In the seeded fine suspension polymerization, the temperature is from 30 ° C to
It is 65 ° C. The lower this temperature, the higher the degree of polymerization of the polymer obtained, but the lower the polymerization rate and the lower the productivity. If this temperature is too high, only a polymer having a low degree of polymerization can be obtained. After the seeding fine suspension polymerization is completed, a well-known method, that is, an aqueous medium containing the polymer taken out is spray-dried, and the obtained granular material is kneaded with a plasticizer to form a paste sol. According to the present invention, an aqueous medium containing a high concentration of vinyl chloride polymer particles can be obtained with a small amount of anionic emulsifier. As a result, the product obtained by paste processing also has good resistance to water whitening. In addition, since a stable high-concentration aqueous medium can be obtained, when the unreacted monomer is recovered after the completion of the polymerization, it can be performed under high temperature conditions with good efficiency, and the thermal energy for drying the aqueous medium is small. There is also an advantage. EXAMPLES Examples will be given below to specifically explain the present invention, but the present invention is not limited thereto. The evaluation items in the examples are as follows. -Polymerization stability: The obtained fine particle suspension of the polymer is filtered through a 60-mesh wire net to obtain agglomerates on the wire net, and the deposits on the inner wall of the polymerization tank are scraped together to measure the weight, and then charged. It was expressed as the weight of the aggregate relative to 100 parts by weight of the monomer. -Polymer particle size: Measured using a laser scattering particle size distribution measuring device. Solid concentration in aqueous medium: 2 g of the liquid was heated at 105 ° C. for 2 hours, evaporated to dryness, and the calculated concentration (%) was calculated from the weight ratio. Emulsion stability of aqueous medium: 5 Kg of the aqueous medium containing the polymer was placed in a 5 L flask (inner diameter 158 mm) equipped with a stirrer having a stirring blade length of 85 mm, and the mixture was stirred at 70 ° C. at 275 rpm, and the liquid surface started from the start of stirring. The time (minutes) until it stopped flowing was measured. Water resistance whitening test: spray drying an aqueous medium containing a polymer,
To 100 parts by weight of the obtained polymer powder, 55 parts by weight of 2-ethylhexyl phthalate and 2 parts by weight of a stabilizer were added, and the mixture was kneaded with a raikai machine to obtain a paste sol. 3 times the paste sol
After hand-drawing on a glass plate with a 00μ coater,
It was melted by heating at 220 ° C. for 5 minutes. Immerse the sheet in deionized water at room temperature for 4 hours and change the haze value of the sheet to JI.
It was measured according to S K7105-1981. The higher alcohols used in the examples are C ₁₂ : lauryl alcohol, C ₁₄ : myristyl alcohol, C ₁₆ : cetyl alcohol, and C ₁₈ : stearyl alcohol. The amount is expressed in parts by weight per 100 parts by weight of the vinyl chloride-based monomer. In both the fine suspension polymerization and the seeding fine suspension polymerization, the polymerization tank is made of 100 liter glass lining, and the inner wall surface is coated with 0.15 g / m ^{2 of} 1-naphthol sulfide compound as a scale adhesion preventing agent. What was done was used. Reference Examples 1 to 5 (Production of Seed Polymer) 225 parts by weight of deionized water, 0.6 part by weight of sodium dodecylbenzenesulfonate, a higher alcohol of the kind and amount shown in Table 1, in a tank equipped with a stirrer. After 0.2 parts by weight of di-2-ethylhexylperoxydicarbonate was charged and degassed, 100 parts by weight of vinyl chloride monomer was charged and the mixture was homogenized by a two-stage pressure high-pressure pump. Next, this dispersion was transferred to a degassed polymerization tank and heated to 39 ° C. to start polymerization. After about 8 hours, the pressure dropped by 0.5 Kg / cm ² , so the polymerization was terminated and the unreacted monomers were removed and the contents were taken out. Examples 1 to 3 An aqueous medium containing 11 parts by weight of the seed polymer shown in Table 2,
Deionized water and 0.36 parts by weight of sodium dodecylbenzenesulfonate were added to deionize water to an amount of 80 parts by weight including the amount of water in the aqueous medium containing the seed polymer, and then 100 parts by weight of vinyl chloride monomer was polymerized. The mixture was charged into a tank and the temperature was raised to 49 ° C. to start polymerization. After about 10 hours, the pressure is 0.5
Since the amount was decreased by kg / cm ² , the polymerization was terminated and unreacted monomers were removed and the contents were taken out. The results of seeding fine suspension polymerization and the evaluation results of the paste sol are shown in Table 2. Example 4 Aqueous medium containing 9 parts by weight of the seed polymer shown in Table 2, deionized water of 77 parts by weight combined with the amount of water in the aqueous medium containing the seed polymer, sodium lauryl sulfate 0 .6
After charging 5 parts by weight and degassing, vinyl chloride monomer 100
Part by weight was placed in a polymerization tank and the temperature was raised to 55 ° C. to start polymerization. After about 10 hours, the pressure dropped by 0.5 kg / cm ² , so the polymerization was terminated and unreacted monomers were removed and the contents were taken out. The results of seeding fine suspension polymerization and the evaluation results of the paste sol are shown in Table 2. Example 5 An aqueous medium containing 11 parts by weight of the seed polymer shown in Table 2.
Example 4 was performed in the same manner as in Example 4 except that deionized water was used in an amount of 60 parts by weight combined with the amount of water in the aqueous medium containing the seed polymer. Table 2 shows the evaluation results. Comparative Example 1 The procedure of Example 1 was repeated, except that the seed polymer shown in Table 2 was used. When the polymerization tank was opened after completion of the polymerization, the contents were aggregated. Comparative Example 2 The procedure of Example 4 was repeated, except that the seed polymer shown in Table 2 was 12 parts by weight and the sodium lauryl sulfate was 1.3 parts by weight. The results of seeding fine suspension polymerization and the evaluation results of the paste sol are shown in Table 2. [Table 1] [Table 2]

Claims (1)

Claims: 1. Fine suspension polymerization in which vinyl chloride alone or vinyl chloride and a monomer copolymerizable therewith (hereinafter referred to as vinyl chloride monomer) are seeded in the presence of a seed polymer. In the method for producing a vinyl chloride-based polymer, the seed polymer is present in the presence of 1.0 to 6.0 parts by weight of a linear aliphatic higher alcohol per 100 parts by weight of the vinyl chloride-based monomer. A method for producing a vinyl chloride-based polymer, which is a polymer obtained by finely suspension polymerizing in an aqueous medium containing an anionic emulsifier using an oil-soluble polymerization initiator. 2. The method according to claim 1, wherein the oil-soluble polymerization initiator has a 10-hour half-life temperature of 30 to 55 ° C. 3. In the seeded fine suspension polymerization, 5 to 20 parts of the seed polymer is added to 100 parts by weight of vinyl chloride-based monomer.
The manufacturing method according to claim 1, characterized in that a weight part is used. 4. In the seeded fine suspension polymerization, 0.3 anionic emulsifier per 100 parts by weight of vinyl chloride monomer.
50-85 parts by weight of an aqueous medium containing 1.0 part by weight to 1.0 part by weight is used, and the production method according to claim 1 is characterized.