JPH0248003B2 - PEESUTOKAKOYOENKABINIRUJUSHINOKAISHUHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing granular vinyl chloride resin to be subjected to paste processing. Normally, when paste processing vinyl chloride resin, the vinyl chloride resin (hereinafter referred to as resin) manufactured for paste processing is mixed with plasticizers, stabilizers, pigments, fillers, etc. as necessary. A method is adopted in which the plastisol is mixed with an agent to form a liquid plastisol and then subjected to a molding process. Then, the liquid plastisol is shaped by means such as casting, coating, dipping, etc., and a molded article is obtained by heating and melting and solidifying the plastisol. Therefore, the fluidity properties of plastisol are properties that have an extremely important effect on the formability of paste processing, and the reality is that great effort and ingenuity are put into the formulation, especially in the quality design of the resin. be. Generally, the method for producing resin for this purpose involves emulsion polymerization or suspension polymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride in the presence of a radical-generating polymerization initiator and an emulsifier. A method has been adopted in which an aqueous dispersion of spherical resin having a diameter of 0.05 to 5 μm is obtained and this aqueous dispersion is spray-dried. However, the resin obtained by this method contains all the nonvolatile components in the aqueous resin dispersion, which causes a decrease in properties such as thermal stability, water resistance, and transparency of the molded product. Furthermore, in normal spray drying, the resin particles in the sprayed aqueous dispersion are dried and captured as a solid aggregate as the water evaporates, so a pulverization process is required to ship the product. It may require
Even with such treatments, it is often impossible to achieve dispersion of aggregated particles by simple mixing during plastisol production. Furthermore, since conventional resins are fine powders, they not only cause a deterioration of the working environment, such as powder scattering when products are packed into bags or when opened and mixed during plastisol production, but also cause powder flow. Due to poor performance, automatic weighing and transportation are difficult. As a result of studying the current problems of the vinyl chloride resin for paste processing, the present inventor found that the vinyl chloride resin is difficult to dissolve in water and can be dissolved or swollen in an aqueous dispersion of the vinyl chloride resin for paste processing. By adding and mixing an organic liquid that does not cause oxidation, the vinyl chloride resin is separated from the aqueous phase as a granular aggregate, and then dried, resulting in a powder with good fluidity and little scattering, and is similar to plastisol. We have previously discovered that when this process is carried out, it is possible to recover granular vinyl chloride resin that has sufficient dispersibility and low viscosity to be subjected to paste processing, and which provides molded products with excellent thermal stability, water resistance, and transparency. . However, in order to further improve the efficiency of this method, as a result of further studies, we found that by combining the above vinyl chloride resin with a specific amount of vinyl chloride resin of a specific particle size, a resin can be obtained with extremely high efficiency. confirmed that it is extremely easy to recover the resin contained in the aqueous phase after separating the granular aggregates, and completed the present invention. That is, the present invention makes the vinyl chloride resin granular by adding and mixing an organic liquid that is sparingly soluble in water and does not dissolve or swell the vinyl chloride resin into an aqueous dispersion of the vinyl chloride resin for paste processing. When recovering vinyl chloride resin by separating it from the aqueous phase as an aggregate and drying it, coarse chloride with an average particle size in the range of 10 to 60 microns is added to the aqueous dispersion of vinyl chloride resin for paste processing. The present invention relates to a method for recovering vinyl chloride resin for paste processing, characterized in that vinyl resin is added in an amount of 1 to 70% by weight, preferably 5 to 60% by weight based on the total amount of resin. The method of the present invention consists of the following basic steps: (1) a first step of mixing an aqueous resin dispersion and an organic liquid and aggregating the resin via the organic liquid; A second step of separating and removing the aqueous phase from the mixed liquid containing the resin aggregate obtained in the step, (3) a third step of drying the resin aggregate from which the aqueous phase has been removed, and (4) a further step as necessary. The fourth step consists of mixing the resin in the aqueous phase separated in the second step with the raw material used in the first step. The aqueous dispersion of vinyl chloride resin for paste processing (average particle size: 0.05 to 5 μm) and vinyl chloride resin (hereinafter referred to as coarse vinyl chloride resin) having an average particle size of 10 to 60 μm used in the present invention are:
A vinyl chloride resin homopolymer or vinyl chloride produced by normal emulsion polymerization or suspension polymerization (usually 70% by weight or more), and vinyl acetate,
Its resin composition is a copolymer with an olefinic monomer such as vinylidene chloride, ethylene, propylene, butene, acrylonitrile, acrylic ester, methacrylic ester, or maleic acid. As the coarse vinyl chloride resin, any of an aqueous dispersion after polymerization, a wet cake after dehydration, and a powder resin after drying may be used. It is desirable that the content is between 10 and 70% by weight. 10% by weight
If the amount is less than 70% by weight, the amount of wastewater will be too large compared to the amount of product, which is uneconomical. If it exceeds 70% by weight, the viscosity of the mixture of aqueous dispersion and organic liquid will increase significantly, making it difficult to operate. becomes difficult. Furthermore, if the average particle size of the coarse vinyl chloride resin exceeds 60 microns, it is undesirable because it causes streaks during thin film coating processing, roughening and matting of the surface of the molded product. Moreover, if it is less than 10 microns, the recovery efficiency of granular vinyl chloride resin and the recovery efficiency of the resin component from separated water will decrease. In addition, if the amount of coarse vinyl chloride resin added is less than 1% by weight, the recovery efficiency of the resin and the viscosity characteristics when made into a sol will be poor, while if it exceeds 70% by weight, the recovery efficiency of the resin will be improved and the separation will be poor. Although the ease of recovering the resin component from water is maintained, if the obtained product is made into plastisol and subjected to paste processing, the gelling property and mechanical strength of the molded product will be significantly reduced. The disadvantage is that the scope of use is limited. The organic liquid added to the aqueous dispersion of vinyl chloride resin is one that is sparingly soluble in water and does not dissolve or swell the resin during separation and recovery in the present invention. Generally, this organic liquid is
Those having a melting point of 20° C. or lower and a boiling point at normal pressure higher than the temperature during separation and recovery of the present invention, preferably 200° C. or higher are used. If an organic liquid having a boiling point lower than the temperature at the time of separation and recovery is used, additional equipment is required for recovery because the organic liquid evaporates, which is not economical. Of course, even if it does not meet the above-mentioned conditions as a single product, it may be used as a mixture as long as it satisfies the above-mentioned requirements. There are two reasons why organic liquids are required to be poorly soluble in water. Firstly, this is to reduce the amount entrained in the aqueous phase to be separated after mixing with the aqueous dispersion, thereby preventing loss of organic liquid and reducing wastewater treatment costs.Secondly, To aggregate resin particles dispersed in water via an organic liquid,
This is because the organic liquid needs to exist as a liquid phase with an interface between the resin particles and water.
Furthermore, if the organic liquid used is one that dissolves or swells the resin at the temperature during separation and recovery in the present invention, this is disadvantageous because the resin particles may be deformed or altered in quality. In addition, since most of the organic liquid used in the present invention remains in the product resin, it is necessary to avoid any liquid that would have an adverse effect on the operability and processability during paste processing and the quality of the molded product. In view of the above points, it is most natural and rational to use a liquid compounding agent commonly used in paste processing as an organic liquid. Examples of the organic liquid in the present invention include the following. (1) Phthalic acid alkyl ester plasticizers such as dioctyl phthalate, dinonyl phthalate, butyl lauryl phthalate, and methyl oleyl phthalate (2) Aromatic carboxylic acid ester plasticizers such as trioctyl trimellitate and diethylene glycol dibenzoate (3) ) Aliphatic dibasic acid ester plasticizers such as dioctyl adipate, dibutyl sebacate, and dioctyl tetrahydrophthalate (4) Phosphate ester plasticizers such as trioctyl phosphate and trichloroethyl phosphate (5) Diethylene glycol dicarbonate rate, 1.4
Fatty acid glycol ester plasticizers such as butylene glycol di-2-ethylhexanoate (6) Polyester plasticizers (7) Butyl oleate, methyl acetyl ricinolate 2,2,4-trimethyl-1,3-pentane Fatty acid esters such as diol diisoptylate, epoxidized soybean oil, epoxys such as octyl epoxystearate, chlorinated fatty acid methyl, chlorinated paraffins such as chlorinated paraffin, aliphatic dibasic acids such as dioctyl succinate Ester-based secondary plasticizers (8) Petroleum-based diluents such as mineral spirits and mineral turpentine, and long-chain alkylbenzene-based diluents such as dodecylbenzene (9) Liquid lubricants such as higher alcohols, liquid paraffin, and higher fatty acid alkyl esters Organic The amount of liquid added is 100% of the resin in the aqueous dispersion.
0.5 to 20 parts by weight, preferably 2 to 20 parts by weight
It should be selected within the range of 15 parts by weight. The amount added is
If it exceeds 20 parts by weight, the desired granules may not be obtained and a sol may be formed. Even if granules are obtained, the large content of organic liquid may make it difficult to remove water in the subsequent drying step. If the amount added is less than 0.5 parts by weight,
Very little of the desired granules are obtained. The mixing of the organic liquid and the aqueous dispersion of the resin is
It should be carried out at 70°C, preferably in the range 20-50°C. If the temperature exceeds 70°C, swelling and absorption of the resin by the organic liquid will be promoted, and coalescence will begin to occur due to softening of the resin, so there is a risk that the dispersibility of the final product will be significantly impaired. Any known method can be used to mix the organic liquid and the aqueous dispersion of the resin, but since the degree of mixing has a large effect on the aggregation efficiency of the resin with the organic liquid, it is preferable to mix the amount per unit volume of the mixing device. Mixed power is 1KW/ ^M3 (1 per cubic meter
kilowatts) and the product with the mixing time is
It should be 4KW・Hr/M ³ or more.
From the viewpoint of uniformity and continuity of mixing, it is preferable to use a high-speed rotating continuous mixer or a multi-blade continuous mixing tank as a mixing device, but ordinary stirring tank mixers and static top mixers are also recommended. Can be used. Next, in order to separate the aqueous phase from the assembled resin aggregate via the organic liquid, a known method may be used depending on the shape of the captured resin mixture. however,
The temperature must be in the range of 20-70°C to prevent softening and coalescence of the resin. The resin particles separated in the separation process are then sent to a drying process to remove the organic liquid and attached moisture. In this drying process, widely known drying equipment can be used, but it is necessary to set conditions such that the strength of resin aggregation and coalescence does not impair dispersibility during paste processing. In other words, the temperature of the resin to be dried during the drying process is 70°C or less, preferably 50°C.
Make it as follows. In this way, vinyl chloride resin can be obtained in high yield, and this resin has good fluidity and low scattering, and also has good viscosity characteristics when made into plastisol by conventional methods and thermal stability when made into molded products. It also has excellent physical properties. The method of the invention will now be explained by way of examples. Note that the average particle size of the vinyl chloride resin indicates the particle size at the 50% point in the weight distribution of the resin particles. In addition, the recovery efficiency of granular vinyl chloride resin was calculated using the following formula. Recovery efficiency = Weight of vinyl chloride resin sieved on a wire mesh with a predetermined opening/weight of vinyl chloride resin in the charged vinyl chloride latex x 100 (%) In addition, the sedimentation property and powder property of the resin , sol (resin 50g
and 30 g of di-2-ethylhexyl phthalate in a sieve machine) and the properties of the film will be explained below. Sedimentation property of resin in separated water after passing through a screen After collecting separated water in a glass container and allowing it to stand still,
A case where an almost transparent supernatant liquid is formed within 3 minutes is considered good, and a case where a supernatant liquid is not formed even after 10 minutes is judged poor. Angle of repose Indicates the ease of fluidity of powder; the smaller the value, the better the fluidity. Bulk specific gravity This is the apparent density of the powder, and the larger the value, the better the handling properties. Adhesion After placing the sample on paper and vibrating it horizontally, discard the sample and observe the amount of resin attached to the paper.
The less the better. Viscosity Burtskfield BM type viscometer rotor #4
Values at a sol temperature of 23°C when measured at 6 rpm (on the first day) and when left at 23°C for 7 days (after 7 days). North Finesse This indicates the particle size of the resin particles in the sol, and the larger the number, the finer it is (8 is the finest and 0 is the coarsest). Thermal stability The sol was poured into an aluminum mold and the 190
Changes in color tone after 30 minutes in a hot air atmosphere at ℃ are displayed in 5 levels from A (small change) to E (large change). Film strength The sol was coated on a 2 mm thick glass plate to a thickness of 400μ, heated to gel in a hot air atmosphere at 180°C for 10 minutes, and then formed into a film.JIS K-6301-
75 compliant No. 3 dumbbell, tensile speed 200mm/
Measure the tensile strength at break at min. Example 1 3000 g of an aqueous dispersion of vinyl chloride resin for paste processing (solid content 30% by weight, average particle size 1.2μ),
400g of an aqueous dispersion (solid content 30% by weight) of coarse vinyl chloride resin having an average particle size of 45μ and a
61g of 2-ethylhexyl phthalate was transferred into a container with an inner diameter of 10cm and an internal volume that had numerous stirring blades of 9cm in diameter inside.
Place in a 3.8 cylindrical stainless steel mixer,
After mixing at 1200 rpm for 10 minutes, an aqueous dispersion of a spherical resin composition was obtained. The spherical resin composition was separated from this dispersion using a 60-mesh wire mesh, and the material on the wire mesh was centrifugally dehydrated to obtain 826 g of wet granules. When this was dried in a hot air dryer at 35°C for 12 hours, 603 g of resin (A) was obtained. Example 2 3200 g of an aqueous dispersion of vinyl chloride resin for paste processing (solid content 30% by weight, average particle size 1.2μ),
Coarse vinyl chloride resin powder with average particle size of 26μ
300g and 100g of di-2-ethylhexyl phthalate
Example 1 except that g was mixed at 1000 rpm for 15 minutes.
The experiment was conducted using exactly the same equipment and procedure as in the previous study. The weight of the wet granules obtained was 1170 g, and the weight of the dry resin (B) was 831 g. Comparative Example 1 Using 3400 g of the aqueous dispersion of vinyl chloride resin for paste processing used in Example 1 (solid content 30% by weight) and 61 g of di-2-ethylhexyl phthalate, the same equipment and conditions as in Example 1 were carried out. The experiment was carried out according to the procedure. The weight of the wet granules obtained was 402 g;
The weight of the dry resin (C) was 285 g. Comparative Example 2 Using 2,600 g of the aqueous dispersion of vinyl chloride resin for paste processing used in Example 2 (however, the solid content was adjusted to 15% by weight), 800 g of coarse vinyl chloride resin powder, and 95 g of di-2-ethylhexyl phthalate. The experiment was conducted using exactly the same equipment, conditions, and procedures as in Example 2. The weight of the obtained wet weight is 1060g,
The weight of the dry resin (D) was 785 g. Comparative Example 3 3000 g of the aqueous dispersion of vinyl chloride resin for paste processing used in Example 1 (solid content 30% by weight),
500 g of an aqueous dispersion (solids content 32% by weight) of coarse vinyl chloride resin having an average particle size of 93μ and a
An experiment was conducted using 64 g of 2-ethylhexyl phthalate using the same equipment, conditions, and procedure as in Example 1. The weight of the wet granules obtained was 866 g, and the weight of the dry resin (E) was 632 g. Reference Example 1 The aqueous dispersion of vinyl chloride resin for paste processing used in Example 1 was dried with a spray dryer at an inlet temperature of 160°C and an outlet temperature of 56°C, and pulverized with a tabletop pulverizer to obtain dry resin (F). I got it. The table shows the recovery efficiency and characteristics of resins (A) to (F). 【table】

Claims (1)

[Claims] 1. By adding and mixing an organic liquid that is sparingly soluble in water and does not dissolve or swell the vinyl chloride resin into an aqueous dispersion of a vinyl chloride resin for paste processing, the vinyl chloride resin is formed into a granular aggregate in the aqueous phase. When recovering the vinyl chloride resin by separating it further and drying it, the aqueous dispersion of the vinyl chloride resin for paste processing has an average particle size of 10 to
60 micron vinyl chloride resin from 1 to 100% of the total resin amount
A method for recovering vinyl chloride resin for paste processing, characterized in that the amount is added within a range of 70% by weight.