JPS59109504A - Recovery of vinyl chloride resin for processing into paste - Google Patents

Abstract

PURPOSE:To recover particulate aggregates of PVC in high yields, by adding coarser PVC particles to an aqueous dispersion of PVC for processing into a paste, and mixing the resulting dispersion with an organic liquid which is difficultly soluble in water and neither dissolves nor swells PVC. CONSTITUTION:PVC of an average particle diameter of 10-60mu in an amount of 1-70wt%, based on the total weight of resin, is added to an aqueous dispersion of PVC for paste technique. To the resulting dispersion is added an organic liquid which is difficultly soluble in water and neither dissolves nor swells PVC (e.g., dioctyl phthalate, trioctyl trimellitate, butyl oleate, or liquid paraffin). In this way, it is possible to obtain particulate aggregates of PVC in extremely high yields, and further to facilitate markedly the recovery of the resinous matter contained in the aqueous layer left after separating the particulate polymer.

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, and dipping, and the molded product is obtained by heating and melting and solidifying the plastisol. Therefore, since the flow characteristics of plastisol have an extremely important influence on the formability of paste processing, the reality is that great effort and ingenuity are being put into the formulation, especially in the quality design of the resin. be. In general,
As a method for producing the resin, vinyl chloride or a monosoft mixture mainly composed of vinyl chloride is subjected to emulsion polymerization 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 particle size of 005 to 5 μm is obtained by drying the dispersion, and this aqueous dispersion is soufflé-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 water residual liquid are dried and captured as a solid aggregate as the water evaporates, so in order to ship as a product, a pulverization process is required. It may require
Even with such treatments, it is often not possible to achieve dispersion of the aggregated particles by simple mixing during plastisol production. Furthermore, since conventional resins are fine powders, it only causes a deterioration of the working environment, such as powder scattering during product refilling and during plastisol production by personnel opening bags and mixing. Automatic metering and automatic transportation are difficult due to poor fluidity.As a result of studying the current problems of these vinyl chloride resins for paste processing, the inventor has developed an aqueous dispersion of vinyl chloride resin for paste processing. By adding and mixing an organic liquid that is sparingly soluble in water and does not dissolve or swell the vinyl chloride resin, the vinyl chloride resin is separated from the aqueous phase as a granular aggregate, and then dried to form a powder. The molded product has good fluidity and low scattering properties, has sufficient dispersibility and low viscosity for paste processing when made into plastisol, and has 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 discovered that the vinyl chloride resin with a specific particle size could be recovered from the above vinyl chloride resin. It was confirmed that resin can be obtained with extremely high efficiency by using specific amounts in combination, and furthermore, it is extremely easy to recover the resin contained in the aqueous phase after separating the granular aggregates, and the present invention I was able to complete it.

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 the vinyl chloride resin by separating it from the aqueous phase as an aggregate and drying it, a coarse vinyl chloride resin with an average particle size in the range of 10 to 60 microns is added to the aqueous dispersion of the vinyl chloride resin for paste processing. 〇The method of the present invention relates to a method for recovering vinyl chloride resin for paste processing, characterized in that it does not add in an amount of 1 to 70% by weight, preferably 5 to 60% by weight based on the total resin amount. The basic steps shown below are:
1) A first step of mixing an aqueous resin dispersion and an organic liquid to aggregate the resin via the organic liquid; 2) Separating and removing the aqueous phase from the mixed liquid containing the resin aggregates obtained in the first step. 3) a third step of drying the resin aggregate from which the aqueous phase has been removed; and, if necessary, 4) using the resin in the aqueous phase separated in the second step in the first step. The groove bottom is mixed into the raw materials in the "first" step.

The vinyl chloride resin for paste processing used in the present invention (an aqueous dispersion with an average particle size of 0.05 to 5 μ → and the vinyl chloride resin with an average particle size of 10 to 60 μm (hereinafter sometimes referred to as coarse vinyl chloride resin) , a homopolymer of vinyl chloride resin produced by conventional emulsion polymerization or suspension polymerization, or a vinyl chloride-based homopolymer (usually 70% by weight or more)
Its resin composition is a copolymer of this and an olefinic monomer such as vinyl acetate, vinylidene chloride, ethylene, propylene, butene, acrylonitrile, acrylic acid ester, memethacrylic acid 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, but the total vinyl chloride resin in the aqueous dispersion after addition of the coarse vinyl chloride resin may be used. It is desirable that the content is 10 to 70 wt. If 10% by weight is not added, the amount of waste water will be too large compared to the amount of product, resulting in uneconomical results.70. ji
If it exceeds ij%, the difference between aqueous dispersion and organic liquid? !
, the viscosity of the hardware increases due to heat, making operation difficult. In addition, if the average particle size of the coarse vinyl chloride resin exceeds 60 microns, streaks may occur during thin film coating, the surface of the molded product may become rough, and matteness may occur. This is undesirable because it causes such problems. Moreover, if the diameter 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. If the amount of resin added is less than 1% by weight, the recovery of the resin and the viscosity properties when made into a sol are poor, fr, υ, while if it exceeds 70% by weight, tO(
Improvement of fat recovery efficiency and ease of recovery of resin components from separated water are maintained; however, when the obtained product is made into plastisol and subjected to paste processing, gelation property decreases and molded product machine This results in a disadvantage that the range of applications is limited because the reduction in the optical strength becomes large.

The organic liquid added to the aqueous dispersion of vinyl chloride resin is
#i #ffJ in water and does not dissolve or moisten the resin during separation and recovery in the present invention. Generally, this a#: body has a melting point of 2 (
Those whose boiling point at normal pressure is below IC and above the temperature during separation and recovery of the present invention, preferably above 200C are used.

If an organic liquid whose node point is below the temperature at the time of separation and recovery is used, it will volatilize and additional equipment will be required for this recovery, making it uneconomical.Of course, as a single product, it will not meet the above conditions. Even if it is a mixture, it can be used as long as it meets the above-mentioned requirements1.The reason why the organic liquid is required to be difficult to bathe in water is as follows.

Firstly, this is to reduce the number of shrimps entering the aqueous phase to be separated after mixing with the aqueous dispersion, thereby preventing loss of organic liquid and reducing wastewater treatment costs. In order to aggregate resin particles dispersed in water through an organic liquid,
This is because the organic liquid needs to exist as a liquid phase with an interface between the resin particles and the ice.

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.

Beak 1) Plastic cutting of heptalic acid alkyl esters such as dioctyl phthalate, dinonyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, etc. (2) Trioctyl trimellitate, diethylene IJ
: r -/I/ Aromatic secondary carphones such as dibenzoate (night ester OS plastic R1 131 dioctyl-1 dibate, dibutyl sebacate,
Plastic machining based on aliphatic dibasic acid esters such as dioctyl tetrahydrophthalate +41 points! Phosphorus + IL ester plasticizers such as J ocbuur phosphenite and trichloroethyl phosphate (5) Diethylene glycol cicafurilate, 14
1 ton of fat such as butylene glycol-di-2-ethyl hexa/ni)! Glycol ester plasticizer (6) Polyester plasticizer (1) JJi- such as olein tV butyl, methyl acetyl ricinoleate, 2.2.4-1-dibutyl-1,3-pentanediol diimptile, etc. r fatty acids (11 esters, epoxidized soybean oil, epoxy systems such as epoxidized octyl derinate, chlorinated fatty acid methyls, chlorinated paraffin systems such as chlorinated paraffins, aliphatic dibasic acids such as succinyl chloride, etc.) Ester-based secondary plasticizer (8) Mineral spirit, mineral turpentine, etc., petroleum-based, dodecylbenzene, etc. 4% !jfl Alkylbenzene-based diluent (9) Higher alcohol, liquid paraffin, high grade) 1 ft furkylnisdel, etc. The additive liquid of the liquid i'it A'1 organic liquid is 0.5 to 20 parts, preferably 2 to 15 parts per 100 parts by weight of the resin in the aqueous dispersion.
The selection should be made within the Keio Welfare Ministry. The amount added is 20 M
If the amount exceeds .gll, the desired granular material may not be obtained and a sol-like material may be generated. do. Even if granules are obtained, there is a risk that it will be difficult to remove moisture in the subsequent drying process due to the large amount of liquid contained. In this case, the desired particulate matter is hardly produced.

The mixing of the organic liquid and the aqueous dispersion of resin is carried out at 20-70C.
1, preferably in the range of 20 to 50 CL (near). If the temperature exceeds 7'OC, swelling and absorption of the resin by the organic liquid will be promoted, and coalescence will also occur due to softening of the resin, so there is a risk that the dispersibility of the final product will be significantly impaired.

The method of mixing an organic liquid and an aqueous dispersion of resin is as follows:
Any known method can be used, but since the degree of mixing has a large effect on the efficiency of aggregation of the resin with the organic liquid, it is preferable that the mixing power per unit volume of the mixing device be I KW/M.
(1 kilowatt per cubic meter) or more, and the product with the mixing time should be 4 KW - Hr/)A" or more. For the mixing device, the uniformity and continuity of the mixing, etc. From this point of view, it is preferable to use an I6-speed rotary continuous mixer or a multi-speed continuous mixing tank, but a normal stirring 191 type mixer or static mixer may also be used.

Next, in order to separate the aqueous phase from the resin aggregate assembled via the organic liquid, a known method may be used depending on the shape of the captured resin mixture.However, softening and coalescence of the resin may be prevented. The temperature should be in the range 20 to 70C to maintain the temperature.

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. That is, the temperature of the resin to be dried during the drying process is set to be 70°C or less, preferably f'i, 50°C or less.

In this way, vinyl chloride/L-resin can be obtained at a good yield, but this material has good fluidity and little scattering, and has a specific viscosity when made into glastisol by a conventional method and when made into a molded product. It also has excellent physical properties such as thermal stability.

Next, the present invention will be explained in detail with reference to examples. In addition, the average particle size of vinyl chloride resin is 50% in the weight distribution of resin particles.
The particle size at the point is shown. In addition, the circular efficiency of granular vinyl chloride resin was calculated using the following formula.

In addition, the sedimentation properties, powder properties, sol (produced by mixing 50F fat and 50F di-2-ethylhexyl phthalate, !Z in a sieve machine) properties and film properties are described below. explain.

Sedimentation of the resin in the separated water after passing through the screen After collecting the separated water in a glass container and allowing it to stand, it is considered good if an almost transparent supernatant liquid is produced within 2 to 3 minutes.
Items that do not produce liquid are considered defective.

Angle of repose indicates the ease of fluidity of powder; the smaller the value, the better the fluidity.

It is the apparent density of the bulk specific gravity powder, and the larger the value, the better the handling properties.

After placing the sample on a piece of paper and vibrating it horizontally, the sample was thrown away and the amount of resin deposited on the paper was observed.

The less the better.

Viscosity Brookfield BM viscosity: 4t rotor #4 when measured at 96rpm7 (first day) and 7 at 26C.
The value at a sol temperature of 23C when left for days (after 7 days).

The particle size of the resin particles in the North Fines sol indicates the finer the higher the number (8 is the finest and 0 is the roughest).The thermally stable sol was poured into an aluminum mold and heated to 50°C in a hot air atmosphere at 190C. Changes in color tone after minutes A (small change) to E
Displayed in 5 levels (large change).

The film strength sol was coated to a thickness of 400μ on a glass plate with a thickness of 2 degrees, heated to gel in a 180C hot air atmosphere for 10 minutes, and formed into a film. The tensile strength at break is measured at a speed of 200 min/min.

Example Aqueous dispersion of vinyl chloride resin for paste processing (solid content 50% by weight, average particle size 1.2μ) 3000y-, 45
Aqueous dispersion of coarse vinyl chloride resin (solid molecules j, 1150% by weight) having an average particle size of 4001i' and
2-Ethylhexyl phthalate 61F! -, with an inner diameter of 10 cm and an internal volume of 6, with a large number of stirring leaves of diameter 9 (branches) inside.
．． Place in an 8p cylindrical stainless steel mixer and mix at 1200r
After mixing for 10 minutes at pm, an aqueous dispersion of the 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, resulting in a wetness of 826z. The obtained granules were dried for 12 hours in a hot air circulation dryer S5C, resulting in 603
A resin pellet of 1- was obtained.

Example-2 Aqueous dispersion of vinyl chloride resin for paste processing (solid content 50wt, h, average particle size 1.2μ) 320137
．． Coarse vinyl chloride resin powder 3 having an average particle size of 26μ
00F and di-2-ethylhexyl phthalate 1001
i1' at 11000 rp for 15 min 11707-1 dry resin (Bl (7) M&t was 8315r-T).

Comparative Example-1 Example-1 and the aqueous dispersion of vinyl chloride resin for paste processing used in Example-1 (solid content 60%) using 5400 f- and di-2-ethylhexyl phthalate 61 yen. The experiment was conducted using exactly the same equipment, conditions, and procedures. The weight of the obtained wet n ■ grain autumn product is 402F! -1 dry resin (
C) Noju Mouse was 2855”C.

Comparative Example-2 Aqueous dispersion of vinyl chloride resin for paste processing used in Example-2 (however, the solid content was adjusted to an excellent volume of 15%) 2
6007, coarse vinyl chloride resin powder eoof and G2
Using -ethylhexyl phthalate 959-, an experiment was conducted using the same equipment, conditions, and procedures as in Example-2. The amount of wet silk weight obtained was 1060y-1 dry resin (I
))'s Jfj cabinet was 7851.

Comparison 1 1l-3 Aqueous dispersion of vinyl chloride resin for paste processing used in Example-1 (solid content 60% by weight) 30007.95μ
Coarse vinyl chloride with an average particle size of 5007 and U Sea 2-
Example-1 using ethylhexyl phthalate 64f
exactly the same device.

The experiment was conducted under the following conditions: 11th shift in middle school. The weight of the wet granules obtained is 866y-1 dry resin (the weight of the thorns is 6325'
Met.

Reference Example-1 The aqueous dispersion of vinyl chloride resin for paste processing used in Example-1 was heated to a population temperature of 160 using a spray dryer.
It was dried at a discharge temperature of 56 U and pulverized with a tabletop pulverizer to obtain a dry resin (F). The table shows the recovery efficiency and characteristics of the resins (A) to (F).

Claims (1)

[Claims] By adding and mixing an organic liquid that is sparingly soluble in water and does not cause the vinyl chloride resin to dissolve or swell to an aqueous dispersion of the 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, add vinyl chloride resin having an average particle size of 10 to 60 microns to the aqueous dispersion of the vinyl chloride resin for paste processing in a proportion of 1 in all the resin paper.
A method for collecting vinyl chloride resin for paste processing, characterized in that the amount is added in a range of 70% by weight.