JPS5984922A - Method for coagulating thermoplastic resin latex - Google Patents

Abstract

PURPOSE:To facilitate the waste water treatment and coagulate a thermoplastic resin latex in coagulating the latex with an aqueous solution of an inorganic salt, by adding an aqueous solution of a high polymer flocculant in a specific proportion to the latex and/or the aqueous solution of the inorganic salt to reduce the moisture content of the resultant crumb. CONSTITUTION:An aqueous solution of an inorganic salt is added to a thermoplastic resin latex, e.g. ABS resin or impact-resistant styrene resin, prepared by the emulsion polymerization method to coagulate the latex. In the process, 5- 500wt.ppm based on the solid of the latex high polymer flocculant, e.g. strongly anionic polyacrylamide, as an aqueous solution in 0.1-5wt% concentration is added to the latex and/or aqueous solution of the inorganic salt to coagulate the latex.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coagulating a thermoplastic resin polymer latex produced by an emulsion polymerization method.

Rubber elastic bodies, such as polybutadiene, styrene-butadiene copolymer, polyisoprene, ethylene-propylene-nonconjugated diene copolymer, polystyrene, a-methylstyrene, and aromatic vinyl monomers such as vinyltoluene;
And, if necessary, a monomer copolymerizable with the aromatic vinyl monomer, such as acrylonitrile, methacrylate, acrylic acid, or an alkyl ester of methacrylic acid, may be graft copolymerized. graft copolymers, i.e. so-called ABS resins, MB'
S resin and high impact polystyrene are generally manufactured by emulsion polymerization method in many cases due to quality problems.

The emulsion polymerization method has the advantages of a fast polymerization rate, easy stirring and heat removal, and excellent quality of the resulting resin. It was not easy to remove the resin solids from the emulsified dispersion in water.

That is, conventionally, inorganic salts such as MgSO4, NazSO+, MgC1z, NaC! are added to the latex. 1
, a method of adding an electrolyte such as Oa 012 to destroy the emulsified state and coagulating the solid content of the thermoplastic resin latex, so-called salting out, has been carried out. There were problems such as the crumb having a high moisture content and being difficult to dry, and fine particles remaining in the supernatant liquid making it difficult to treat wastewater.

The present inventors have arrived at the present invention as a result of extensive research aimed at solving the problems of the prior art described above and developing a method for coagulating latex that has a low moisture content and is easy to treat wastewater. be.

The above-mentioned object of the present invention is to provide a method for coagulating the latex by adding an aqueous solution of inorganic salts to a thermoplastic resin latex, in which the polymer flocculant is added to 5-so based on the solid content of the latex.

weight - and 0.7 to 5 of the above polymer flocculant
This can be achieved by a method characterized in that it is added to the latex and/or the inorganic salt aqueous solution as a wt % aqueous solution.

As the thermoplastic resin latex to which the method of the present invention is applied, in addition to the already explained ABS resin, MBS resin, impact-resistant styrene resin, styrene-acrylonitrile copolymer (As resin), and polymer flocculant. Examples include polyacrylamide-based, alginic acid-based, methacrylic acid-based, etc., but there are no particular limitations, but anionic, particularly strong anionic polyacrylic amide is preferred.

Note that anionic polyacrylic amide is obtained by partially hydrolyzing polyacrylic Q amide with a base such as NaOH or KOH, and in particular, one having a hydrolysis rate of λθ or higher is referred to as strongly anionic.

In addition, nonionic polyacrylic amide and cationic polymer flocculants [for example, dimethylamine ethyl methacrylate polymer (OH3) 2804] are particularly effective.

The polymer flocculant has a concentration of 0. /~5 wt/w/w added as an aqueous solution. Adding it in powder form is not preferable because the latex will not coagulate uniformly. Further, a concentration of less than 0.7 tbc is not particularly disadvantageous, but it is not preferable because the amount of the aqueous solution to be added increases. If the concentration of the polymer flocculant aqueous solution exceeds triple dust, it will be difficult to dissolve the flocculant, and the viscosity of the solution will become high, making it difficult to handle, which is unsuitable.

It is most effective to add and mix the required amount of the above polymer flocculant aqueous solution to the thermoplastic resin latex, and then mix the inorganic salt aqueous solution and the above latex. It is often added to both the latex and the inorganic salt aqueous solution in advance, and then the latex and the above-mentioned inorganic salt aqueous solution are mixed together, or it is also effective to add it after salting out the latex with the inorganic salt aqueous solution. .

It is appropriate to add the polymer flocculant so that the solid content of the polymer flocculant is 5 to SOO weight based on the solid content of the thermoplastic resin latex, but especially 10 to 10θ
Heavy weight is preferred.

Note that if the added amount is less than - by weight, the effect will be small and Sθ0
If the weight exceeds the weight, the polymer flocculant will remain in the obtained thermoplastic resin, which is not preferable.

When coagulating the thermoplastic resin latex by the method of the present invention, it may be done at room temperature, but at a temperature of go℃ or higher%Fcqo℃
It is preferable to solidify at a higher temperature.

According to the method of the present invention, the average particle diameter (Dp
, to) are large, the water content is low, and the amount of fine particles contained in the supernatant liquid is reduced, making wastewater treatment easier. Furthermore, since it has the ability to solidify at high temperatures, there is no need to cool down the graph latex after polymerization.

The method of the present invention will be explained in more detail below based on Examples and Comparative Examples.

In addition, in the following examples and comparative examples, Dp! rO(s
o% particle diameter (unit: mm) is Rosj, n-Ramm1
It was determined by the formula er.

Example / Graft latex obtained by graft copolymerizing styrene and acrylonitrile to 47-bolybutadiene latex by emulsion polymerization method (pH / 0. Solid content: 0 weight) Concentration: 3% by weight Magnesium sulfate (MgSO4) aqueous solution / 9. Pour into a coagulation tank with a capacity of Ωot containing a mixture of slag and a polymer flocculant θ / 6 volumes of aqueous solution by weight, temperature 95 ° C, rotation speed / 30.
Stir for 70 minutes at rpm.

The resulting slurry-like solidified material was washed with water, dehydrated using a centrifuge, and then dried.

The following polymer flocculants were used.

Experimental Example 7 Weakly anionic polyacrylic ψamide, Diafloc ■, product name AP-33! ; Experimental example λ Strong anionic polyacrylamide, same A
P-7/3 Experimental Example 3 Strong cationic polydimethylaminomethyl methacrylate, Diafloc■, trade name KP-Ωo/G 4-N Experimental Example 1I Mixture of equal amounts of AP-, 3, 3 and KP20/G The results are shown in Table 1.

Comparative Example/ Graft latex was coagulated without using a polymer flocculant and under the same conditions as in Example/. The results are shown in Table 1.

Example: o, i weight% of AP-JJ5 as polymer flocculant aqueous solution
We investigated the addition method using an aqueous solution.

The results are shown in Table 1.

Example AP-3 Kraft latex was coagulated in the same manner as in Example/Experimental Example/, except that the entire amount of the AP-333 aqueous solution was added to the Kraft latex in advance.

Example AP-, 3J! The graph latex was coagulated in the same manner as in Example/(Experimental Example/) except that the r aqueous solution was mixed in advance with the magnesium sulfate aqueous solution.

Example graph latex M? An experiment was conducted in the same manner as in Example/(Experimental Example/) except that after salting out and coagulating with SO4 aqueous iK, an aqueous AP-33 solution was added.

Example 3 Grafting was carried out in the same manner as in Example λ and Experimental Example/, except that the addition amount of AP-33 on the left was changed from 3 weight P to SOO weight p''! with respect to graph-dramatic solid content. The latex was allowed to solidify.

The results are shown in Table 3.

Comparative Example λ Polymer coagulant AP-, 333 powder was directly added to the graph latex in an amount of SO weight relative to the solid content of the graph latex, and the kraft latex was coagulated in the same manner as in Example a1 Experimental Example 1. . Fine particles with a mesh size of 0 or less were Otsu, g-heavy dust, and DpSO/wI+.

EXAMPLE 500 wt. 4 AP based on Kegraf latex solids content
The graph latex was coagulated in the same manner as in Example 2 and Experimental Example 3, except that -333 was added to the graph latex after salting out at goC or 90C. Dp
! i0 was 0.6g in both cases.

Table 1 Table 2 Table 3 *) Moisture content is the water content after dehydration using a centrifuge. The measurement conditions were drying at 103° C. for 2 hours and expressed as a percentage reduction.

Claims (7)

[Claims] (1) In a method of adding an aqueous inorganic salt solution to a thermoplastic resin latex to coagulate the latex, the polymer flocculant is added to t- based on the solid content of the latex.
The amount of the polymer flocculant is 0.5 oo, and the amount is 0.
7~Left Weight As an aqueous solution, the above latex and /''!
, bamboo, is added to the above-mentioned inorganic salt aqueous solution. (2) The method according to claim 1, wherein the polymer flocculant is anionic polyacryloamide. (3) The method according to claim 1, wherein the polymer flocculant is strongly anionic polyac IJ O amide. (4) The method according to claim 1, 2, or 3, wherein the aqueous polymer flocculant solution is added to the thermoplastic resin latex in advance, and then the inorganic salts are added. (5) The method according to claim 1, 2 or 3, characterized in that 70 to 700 weight of polymer flocculant is added based on the solid content of the thermoplastic resin latex. . (6) The method described in paragraph Φ, in which the thermoplastic resin latex is treated with an aqueous inorganic salt solution. (7) When adding the polymer flocculant aqueous solution, add g of thermoplastic resin latex and/or inorganic salt aqueous solution.
Characterized by maintaining temperature above o℃