JPH0153882B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a vinyl chloride paste resin (hereinafter referred to as paste resin) in which a water-soluble cationic polymer flocculant is added to a vinyl chloride resin latex to increase the solid content concentration, and then the vinyl chloride resin is separated.
It pertains to the manufacturing method. In recent years, in the production of paste resin, with the rise in the price of crude oil, various methods have been considered to remove water from the latex to increase the solid content concentration to prevent an increase in energy costs during drying. Conventionally, paste resins have been produced using emulsion polymerization or microsuspension polymerization, with an average particle size of approximately
From the viewpoint of quality, a method of producing latex of 3 μm or less and spray drying the latex has been widely used. However, according to this method,
Unless the solid concentration in the latex is as high as possible,
Costs will rise. In addition, for a stable latex, if the solid content concentration is not maintained at 45% or less, a large amount of aggregates will easily occur during polymerization, or a large amount of auxiliary agents such as emulsifiers will be required, resulting in quality problems. There's a problem. Therefore, conventionally, the particle concentration in latex was
The method used is to concentrate it to about 60% and then dry it by spray drying. On the other hand, it is easily possible to increase the particle concentration and reduce the drying energy cost by agglomerating the latex and then subjecting it to filtration or centrifugal dehydration. However, if latex is simply agglomerated, a large amount of water will be included in the agglomerate, which not only makes it impossible to dehydrate by filtration or centrifugation, but also makes it highly adhesive and non-flowable, making it difficult to handle industrially. It is not desirable because it masters. Paste resin requires the removal of water in latex and then dispersion of polyvinyl chloride in a plasticizer to give plastisol, but it is simply agglomerated with polyvalent metals or conventionally known flocculants. Otherwise, the plastisol will not form or the viscosity of the plastisol will become extremely high, greatly impairing its commercial value as a paste resin. In other words, conventional aggregation methods have been based on methods such as deactivating the effect of emulsifiers in latex, linking particles with polymer chains, or removing particle surface charges. In the drop flocculation method, once the particles are dried, they do not redisperse in the plasticizer. The well-known theory of agglomeration is
As stated in Smolnchowski's theory of rapid agglomeration, while each particle of the latex is undergoing Brownian motion, the particles collide with each other and agglomeration occurs, which reduces the total number of particles and causes aggregation. It is completed and finally becomes one big lump. In such agglomeration, water is included in the aggregates, and even after dehydration, the water content remains high.Furthermore, the particles adhere to each other, so even if an attempt is made to disperse the particles after dehydration and drying, it is difficult to disperse them. Therefore, this method is inappropriate as a method for producing paste resin. The present inventor previously filed a patent application No. 10687/1987 for a latex agglomeration method in which a water-soluble cationic polymer compound is added to latex, but in subsequent research, a structural formula not described in the earlier application was developed. It has been found that the water-soluble cationic polymer compound also has a good flocculating effect on vinyl chloride resin latex. As a result of exploring the phenomenon of agglomeration occurring without adhesion of particles in latex, the present inventor found that by adding a specific water-soluble cationic polymer compound to latex, particles can be agglomerated without adhesion. The present invention was achieved based on the discovery that water can be easily separated. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a paste resin in which particles in a latex are aggregated without coagulating and the solids are separated from free water. Therefore, the gist of the present invention is to add a water-soluble cationic polymer compound represented by the following general formula [] or [] to a vinyl chloride resin latex or a vinyl chloride copolymer latex, and then separate the solid content. A method for producing a vinyl chloride-based resin is provided. General formula [] General formula [] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, Z is -(CH ₂ ) _n - group,

[Formula] The group, -( _CH2 ) _n -O-( _CH2 ) _o- , X and Y are halogen atoms, which may be the same or different. m and n are integers of 1 to 6, and may be the same or different. l represents an integer of 2 or more. ) The present invention will be explained in detail below. Vinyl chloride resin latex or vinyl chloride copolymer latex (hereinafter sometimes simply referred to as latex) is produced by emulsion polymerization (vinyl chloride or vinyl chloride and a comonomer copolymerizable with vinyl chloride) without any particular limitation. (copolymerization) or microsuspension polymerization (copolymerization). Specific examples include polyvinyl chloride latex (emulsion) and vinyl chloride-vinyl acetate copolymer latex. General formulas [] and [] used in the method of the present invention
The water-soluble cationic polymer compound can be produced by various synthetic methods. Compounds represented by the general formulas [] and [] have a structure in which the alkyl groups R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms or C _1-3 alkyl groups, i.e. methyl, ethyl, propyl A group is preferred, and a methyl group is particularly preferred. X and Y may be chloro or bromine atoms, and both may be the same. Z is preferably an alkylene group having 1 to 3 carbon atoms, specifically a methylene group, an ethylene group, or a propylene group. The value of l may be any integer greater than or equal to 10, but it is preferably in the range of 10 to 1,500, preferably in the range of 50 to 1,000. The larger the value of l, the greater the aggregation effect. m
As the number of and n increases, the charge density in the polymer chain decreases, so the value of m+n and the number of l should be selected appropriately, taking into account the charge of the latex particles used. In the compound represented by the general formula [], R ₃ and R ₄ in the structural formula are preferably hydrogen atoms. The surface charge density of these compounds is positively charged particles with a surface charge density of 10 microcoulombs/cm ² or more.
Particles of 0.01 μm to 10 μm are desirable. A water-soluble cationic polymer compound (hereinafter referred to as a flocculant) collides with the negatively charged latex particles in the latex and the positive charges in the flocculant, causing the latex particles to flocculate, but the flocculated particles repel each other. As a result, the dispersibility is good, and the latex as a whole has excellent fluidity without becoming tofu-like.
It becomes a dispersion liquid with good water separation property. The flocculant may be used after being dissolved in water or other medium, if necessary. Therefore, the amount of coagulant added is 0.001 to 5% by weight, preferably 0.01% by weight, based on the weight of particles in the latex.
By adding in a range of 2% by weight, various agglomerated particles can be obtained. As the amount added is increased little by little, the viscosity of the latex gradually increases, and as the amount is further added, the viscosity decreases. When this process is observed using an optical microscope, the latex particles interact with each other as ionic polymers and aggregate in the initial stage, and exist as large aggregated particles. When the amount added is small, the aggregates with a small particle size are the main body, and as the amount added increases, the aggregate particle size increases, and when further addition is made, the aggregate particle size is divided into 10 to 100μ. The size of the aggregated particles changes to approximately uniform, especially about 20 to 50μ. The diameter of the aggregated particles can be adjusted to a desired size by adjusting the amount of the flocculant added. According to the method of the present invention, when a flocculant is added to latex and left to stand after stirring, water and latex particle aggregates are easily separated, water can be removed by decantation, and water can be dehydrated using a centrifuge. Dehydration can be carried out to a solid content concentration of about 72% using a filter press, and to a solid content concentration of about 78% using a filter press. Therefore, according to the method of the present invention, approximately 22-35%
Since it is only necessary to evaporate a certain amount of water, the energy cost associated with conventional drying is significantly reduced, making it possible to significantly reduce manufacturing costs. Further, the dehydrated cake obtained by the present invention suddenly loses fluidity when the moisture content falls below a certain value. Until then, it exhibits clay-like flow properties despite relatively high particle concentrations. Dehydrated cakes can also be granulated by utilizing these properties. Granulated paste resin has a small bulk density and generates a lot of dust, which can easily cause problems when handling, but because it is in a granular form, it creates less dust and maintains the working environment. Not only can equipment costs be reduced, but the bulk density is approximately 0.5g/ml, which is about twice that of conventional paste resins, and has the advantage of reducing transportation costs and warehouse storage costs to about half of conventional paste resins. Furthermore, since the granulated paste resin can be transported by pneumatic transport or the like, bulk transport and further automatic measurement is possible in this case. Therefore, it is possible to streamline the work and improve the work environment to a greater extent than with conventional powder handling. The method of the present invention will be explained in detail below using Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. In addition, "parts" in the examples represent "parts by weight." Example 1 0.6 parts of sodium lauryl sulfate, 0.03 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, and 0.07 parts of sodium sulfite were added to 100 parts of vinyl chloride monomer using a 300°C pressure-resistant container, and the vinyl chloride monomer was heated at 60°C. Emulsion polymerization was carried out until the saturated vapor pressure of the mixture decreased by 2 kg/cm to obtain a vinyl chloride resin latex with an average particle size of 0.8 μm. The particle solids content in this latex was 38%. Separately, use a 5-necked flask in a nitrogen stream at room temperature. 1 mole of dibromobutane and dibromobutane were added dropwise into dimethylformamide (DMF)/water = 4/1 mixed solvent 1 over 2 hours, then water from 2 was added and left for one week. This polymer compound is a compound in which Z is a butylene group and X and Y are each a bromine atom in the general formula []. The number average molecular weight of the compound was determined by osmotic pressure method to be 82,000, and the value of 1 was approximately 250. The thus obtained aqueous solution was added in an amount of 1.03 to 100 kg of the above-mentioned latex, slowly stirred at 40°C, and then dehydrated using a p660 super decanter manufactured by Tomoe Kogyo. A dehydrated cake with a moisture content of 37% was reduced to 26-29% using a circular mesh with a diameter of 1.1 mm using a twin-screw horizontal extrusion granulator EXD-60 manufactured by Fuji Paudal Co., Ltd. and extrusion granulation. This sample was dried for 1.5 hours using hot air at 50°C in a fluidized fluid dryer to obtain a dry resin with a moisture content of 0.1% or less. The bulk density of the obtained resin was 0.54 g/cc, compared to 0.25 g/cc ± 0.05 of normal paste resin.
It had a very large value compared to the value of g/cc. For 100 parts of this resin, 60 parts of dioctyl phthalate (DOP), 0.6 parts of nonionic surfactant,
A plastisol was prepared by adding 3 parts of a Ca-Zn heat stabilizer and 3 parts of epoxidized soybean oil, and subjected to type B viscosity measurement and oven heat stability test, and the results are shown in Table 1. In the oven thermal stability test, the film was left in a closed container with hot air circulation at 195°C for 10 minutes, and then the film was taken out and continued at the same temperature until it turned black. Example 2 3 In a nitrogen atmosphere, 377 g of diallyldimethylammonium chloride and 705 g of dimethyl sulfoxide were added to 1 g of ammonium persulfate in an autoclave, and the mixture was polymerized at 30° C. for 50 hours without stirring. Add 700g of methanol to the obtained solid,
After dissolving, reprecipitate with a large amount of acetone and add 1N-NaCl.
When the intrinsic viscosity of the solution was measured, it was 0.71. This compound has R ₁ in the general formula []
and a compound in which R ₂ is a methyl group, R ₃ and R ₄ are hydrogen atoms, and X is a chlorine atom. The degree of polymerization l calculated from the intrinsic viscosity is about 490, and the molecular weight is about 79,000. After adding 200 g of this methanol solution to the latex 30 used in Example 1, it was dehydrated using a Super Decanter P660 manufactured by Tomoe Kogyo Co., Ltd., and the solid content in the drained liquid was 0.1% or less. The moisture content in the dehydrated cake was 31%. The obtained dehydrated solid content was heated to 50℃ using a shelf dryer.
to obtain a dry resin. The same test as in Example 1 was conducted on the dried resin. Comparative Example 1 3 g of aluminum sulfate was added to 1000 ml of the PVC latex used in Example 1 to coagulate it. When the whole solidified and became impossible to dehydrate, it was dried at 50°C in a shelf dryer to obtain a dry resin. Comparative Example 2 1000ml of PVC latex used in Example 1,
When flocculating using 2 g of a common cationic flocculant (modified polyacrylamide type), the entire mixture became cream-like and no water was released, making it difficult to dehydrate using paper. Comparative Example 3 The latex used in Example 1 was directly dried using a mini spray dryer manufactured by Yamato Kagaku. The hot air temperature is 120℃ on the inlet side and 50℃ on the outlet side.
I went to ℃. (Conventional method performed without any treatment) Of course, latex cannot be dehydrated by centrifugation or filtration if it is left as is.

【table】

Claims (1)

[Claims] 1. A water-soluble cationic polymer compound represented by the following general formula [] or [] is added to a vinyl chloride resin latex or a vinyl chloride copolymer latex, and then the solid content is separated. A method for producing a vinyl chloride paste resin. General formula [] General formula [] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, Z is -(CH ₂ ) _n - group,
[Formula] or -(CH ₂ ) _n -O-(CH ₂ ) _o - group, X and Y are halogen atoms, which may be the same or different. m and n are integers of 1 to 6, and may be the same or different. l represents an integer of 10 or more. )