JP3080717B2 - Method for producing high nitrile resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graft copolymer of an unsaturated nitrile and a monomer copolymerizable with an unsaturated nitrile, which is excellent in transparency and has a good balance of impact resistance and processability. The present invention relates to a method for producing a high nitrile resin obtained by polymerization.

[0002]

2. Description of the Related Art Nitrile resins are thermoplastic resins having excellent gas and vapor barrier properties and excellent solvent resistance. Recently, nitrile resins have a practical value as packaging materials in the fields of foods, agricultural drugs, cosmetics, and the like. It recognized. As a general method for producing such a resin, an appropriate amount of a coagulant such as an inorganic salt is added to a resin latex obtained by emulsion polymerization to form a paste, which is then coagulated by placing it in a strand of hot water. It is well known that the solid polymer is recovered by washing with water, filtering the resulting slurry and drying.

[0003]

However, in the production of the high nitrile resin which is the subject of the present invention, when the resin is usually washed with water using an inexpensive aluminum sulfate which is easily available as a coagulant and dried, When the recovered polymer is heated and melt-kneaded, there are problems such as a reduction in impact resistance, a yellowing of the resin, a decrease in gloss, and a burning of the resin in a molding machine.

On the other hand, when an alkaline earth metal salt such as magnesium sulfate is used as a coagulant, the initial coloring of the obtained resin can be suppressed to a lower level than when aluminum sulfate is used. There is a problem that the yellowing degree of the resin due to the heat history is large.

[0005] As a resin having the same problems as above,
For example, there is ABS resin and the like.
In the publication, when a rubber elastic latex having an enlarged particle diameter due to phosphoric acid is used, there are problems such as deterioration of the surface appearance of the resin, but during coagulation of the resin latex using an alkaline earth metal salt, or It can be improved by adjusting the pH of the system during washing with water to 4 to 7 using an acid.
No. 05 discloses that after the ABS resin latex produced using a redox initiator is coagulated with an alkaline earth metal salt, the pH of the washing water is reduced to 7 or less using an acid when washing with water. Methods have been proposed for improving the thermal stability (drying step) of the ABS resin powder.

However, these methods are for the case where a specific rubber and a specific polymerization initiator are used, and there are many restrictions, and the effect on the resin in the present invention is not sufficient. I can not say.

Further, JP-A-59-24709 and JP-A-59-24710 disclose problems of insufficient kneading and appearance of resin surface when ABS or MBS resin is mixed with another resin. With respect to the above, there has been proposed a method of improving the pH of a coagulation slurry of a resin latex by making the pH 6 or less.

[0008] However, these methods are also characterized in that the coagulated material is not washed with water, and essentially cannot remove auxiliary materials and the like, which involves the occurrence of problems. I can't say.

An object of the present invention is to provide a method for producing a high nitrile resin, which solves the above-mentioned problems, has good moldability, is excellent in transparency, has a reduced impact resistance due to thermoforming, and has little yellowing of the resin. Is to do.

[0010]

Means for Solving the Problems In the operation of recovering a polymer from a thermoplastic resin latex obtained by emulsion graft polymerization, the present inventors have used aluminum sulfate as a coagulant and usually washed and dried. The emulsifier and coagulant, which are auxiliary materials, react with each other, and the product easily remains in the resin, and is degraded and decomposed by heat during molding processing. After coagulation using a coagulant, the pH of the washing water is adjusted to 4 to 7 with a basic substance, washed with water, and dried.
The above-mentioned product is less likely to remain in the resin, and the impact resistance of the resin due to thermoforming is hardly reduced, the yellowing of the resin is small, and the burning of the resin in the molding machine is small, It has been found that the metal has good releasability from metal and that it is easy to clean the molding machine after molding.

Further, the present inventors have conducted intensive studies, and as a result,
After coagulation using a mixture of aluminum sulfate and magnesium sulfate as a coagulant, the pH of the wash water is adjusted to 4 to 7 with a basic substance, washed with water, and dried. The pH of the washing water is adjusted to 4 to 7 using aluminum sulfate, whereby the transparency of the resin is further improved as compared with the case of washing and drying, and the pH of the washing water is adjusted to 4 to 7 using magnesium sulfate as a coagulant. In the case of washing with water and drying at 7, heat discoloration (yellowing) presumed to be caused by the nitrile group occurs, but it was found that this was suppressed, and the present invention was completed.

That is, according to the present invention, 100 parts by weight of a monomer mixture containing at least 50% by weight of an unsaturated nitrile and comprising at least one monomer copolymerizable with the unsaturated nitrile is added to a diene synthetic rubber 1 In the process for producing a high nitrile resin obtained by emulsion graft polymerization with the addition of a polymerization initiator in the presence of ４０40 parts by weight, the obtained polymer latex having a pH of 2 to 7 is converted into sulfuric acid as a coagulant. When a polymer is coagulated using a mixture of aluminum and magnesium sulfate, and the coagulated polymer is washed with water, the pH of the washing water is adjusted.
Is 4 to 7 depending on a basic substance.

Hereinafter, the present invention will be described in more detail. Examples of the unsaturated nitrile used in the present invention include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like, and preferably acrylonitrile and methacrylonitrile.

The monomer copolymerizable with the unsaturated nitrile is a monomer composed of one or more of unsaturated carboxylic acid ester, aromatic vinyl compound, vinyl ether, vinyl ester, α-olefin and the like. is there.

Examples of the diene-based synthetic rubber used in the present invention include polymers or copolymers of diene-based monomers such as 1.3-butadiene, isoprene and chloroprene.
In addition to the diene-based synthetic rubber, an acrylic rubber having excellent weather resistance may be used.

In the present invention, the high nitrile polymer is obtained by emulsion graft polymerization of a large proportion of unsaturated nitrile and another monomer component copolymerizable with the same to a previously formed diene synthetic rubber. It is obtained at about 0 to 100 ° C. by removing oxygen by a generally known emulsion polymerization method.
At the above temperature, the monomer and other components can be polymerized by batchwise, continuous or split addition.

When the monomer is polymerized in the presence of the rubber, examples of the polymerization initiator used include peracids such as persulfuric acid, peracetic acid and perphthalic acid, persalts such as potassium persulfate, and peroxides. Hydrogen, benzoyl peroxide, chlorobenzoyl peroxide, bromobenzoyl peroxide, naphthyl peroxide, acetyl peroxide, benzoylacetyl peroxide, lauryl peroxide, succinyl peroxide, di-t-butyl peroxide, dicumyl peroxide, hydro Cumyl peroxide, t-butyl peroxide,
Examples thereof include peroxides such as sodium peroxide and barium peroxide, hydroperoxides such as t-butyl hydroperoxide, and azo compounds such as azobisisobutyronitrile. These may be used alone or as a mixture of two or more. Can be used with

The emulsifier used in the present invention is preferably an anionic surfactant. Examples thereof include fatty acid salts, sulfate salts of higher alcohols, sulfate salts of liquid fatty oils, sulfate salts of aliphatic amines and aliphatic amides, and aliphatic salts. Alcohol phosphate esters, sulfonates of dibasic fatty acid esters, aliphatic amide sulfonates,
Naphthalene sulfonates of formalin condensation and the like can be mentioned.

Examples of the molecular weight regulator used in the present invention include alkyl mercaptans, for example, n-dodecyl mercaptan, tert-dodecyl mercaptan, n-dodecyl thiol acetate, pentaerythritol tetrakis (β-mercaptopropionate), limonene dimercaptan And the like.

Examples of the basic substance used for adjusting the pH of the washing water in the present invention include hydroxides or oxides of alkali metals, hydroxides or oxides of alkaline earth metals, and salts of weak acids. And preferably an alkali metal hydroxide.

The method for producing a high nitrile resin according to the present invention comprises:
A resin latex is obtained from the above-mentioned raw materials by a generally known emulsion polymerization method, and a mixture of aluminum sulfate and magnesium sulfate (hereinafter referred to as "coagulant mixture") is used as a coagulant. Can be coagulated by the salting-out method. For example, a method in which the latex and the coagulant mixture are continuously introduced into a mixing chamber of a screw pump, and a paste formed by mixing is formed into a strand, and is put in hot water close to the softening temperature of the resin to coagulate. The polymer can be recovered. Alternatively, the latex and the coagulant mixture may be mixed by a mixer such as a static mixer.

The solid content of the latex is preferably 20 to 40% by weight, and a mixture of aluminum sulfate and magnesium sulfate, which are coagulants, is used in the form of an aqueous solution.
The amount added to the latex is 2 to 2 as the pure content of the mixture of aluminum sulfate and magnesium sulfate based on the solid content of the latex.
It is preferably 5% by weight, and more preferably contains at least 1% by weight of aluminum sulfate. Thus, the ratio of aluminum sulfate of the coagulant mixing <br/> compound in is 20% or more.
When the ratio of aluminum sulfate of the coagulant mixture is less than 20%, since likely to occur thermal discoloration of a resin similar to the case of using only magnesium sulfate (yellowing) is not preferred.

The coagulated product obtained in the above coagulation step is washed with water in a water washing step. In this case, the pH of the washing water is adjusted to a range of 4 to 7, preferably 5 to 6 with a basic substance, and the washing is performed. When the pH value is less than 4, the hue of the obtained resin changes to brown, the thermal discoloration is large, and the resin is burned at the time of molding. On the other hand, if it exceeds 7, the resin yellows and the thermal discoloration is large, and the impact strength and transparency are low.
To lower, both undesirable. Thereafter, the polymer is filtered and dried to obtain a polymer.

The high-nitrile resin produced by the method of the present invention is a thermoplastic resin which can be easily thermoformed by a conventional molding method using a known thermoplastic resin material, for example, extrusion molding, injection molding, blow molding and the like. It is a resin that has high barrier properties against vapors and gases, excellent solvent resistance, impact resistance, and excellent transparency, so it is particularly useful as a container material for bottles, films, and other types of liquids and solids. It is.

[0025]

The present invention will be described below with reference to examples. “Parts” and “%” in the examples are all based on weight.

Example 1 (A) Production of conjugated diene rubber latex A mixture comprising the following components was subjected to nitrogen replacement in a polymerization reactor made of stainless steel to remove oxygen, and stirred at 50 ° C. for 20 minutes.
Polymerization was carried out for hours. Acrylonitrile 30 parts 1,3-butadiene 70 parts Fatty acid soap 2.4 parts Azobisisobutyronitrile 0.3 parts t-dodecylmercaptan 0.5 parts Water 200 parts The monomer addition rate is 90%, and the solid content of the latex is 90%. The partial concentration is 3
It was 0%.

(B) Production of graft polymer The following materials were charged into a polymerization reactor, oxygen was removed by purging with nitrogen, and polymerization was carried out at 60 ° C for 4 hours with stirring. Water 210 parts Acrylonitrile 70 parts Methyl acrylate 30 parts Latex of the above (A) 33 parts Sodium dioctyl sulfosuccinate 1.0 part Polyvinyl pyrrolidone 0.4 parts Potassium persulfate 0.06 parts n-dodecyl mercaptan 1.3 parts Single amount The conversion of the body is 90% and the pH of the latex obtained is
The value was 7, and the solid concentration was 30%.

An aqueous solution of a mixture of aluminum sulfate and magnesium sulfate as a coagulant was added to the obtained latex.
3.5% of the solid content in the latex was added to the total content of the latex to form a paste, which was put into warm water at 75 ° C in the form of a strand and solidified. Of these, aluminum sulfate was 1.0
% And magnesium sulfate were 2.5%. The pH value of the coagulated product at this time was 1.5. Next, the coagulated product was washed with water in a washing tank. At this time, the pH value of the washing water was adjusted to 6 with 1% by weight of sodium hydroxide. After washing with water, filtration and drying were performed to obtain a resin.

The obtained resin is roll-kneaded at 160 ° C. to form a sheet.
Pressing was performed at 00 kg / cm ² G to obtain a transparent press sheet. The obtained press sheet is subjected to ASTM D256
The notched Izod impact value (Izod) at 23 ° C. and a 3.83 kg load was measured in accordance with
Yellowing degree (YI = Yellow) according to STM D1925
wnest Index), AST as transparency
The haze was measured according to MD1003. Further, as a test corresponding to thermal discoloration during molding, the yellowing degree was measured at 184 ° C. × 10 minutes from 174 ° C. × 4 minutes which is a normal press sheet molding condition. The results are shown in [Table 1].

Further, in order to evaluate the thermal stability relating to burning during molding and the ease of cleaning of the molding machine, 30 m
230 ° C, screw rotation speed 45r with mφ extruder
The resin was allowed to flow at pm for 1 hour to evaluate the state of burning of the resin under severe temperature conditions and the ease of cleaning (easiness of removing the adhered resin from screws, dies and the like). The results are shown in [Table 2].

Example 2 In Example 1, the amount of the coagulant added was 2.0 parts by weight of aluminum sulfate in a pure content relative to the solid content in the latex.
%, Except that magnesium sulfate was 1.5%.
A resin was produced in the same manner as in Example 1. Various evaluation tests were performed on the obtained resin in the same manner as in Example 1. The results are shown in [Table 1] and [Table 2].

Comparative Example 1 The procedure of Example 1 was repeated, except that only aluminum sulfate was used as a coagulant, and the amount of addition was 3.5% as a pure content with respect to the solid content in the latex. Resin was produced in the same manner as in Example 1. Various evaluation tests were performed on the obtained resin in the same manner as in Example 1. The results are shown in [Table 1] and [Table 2].

Comparative Example 2 The procedure of Example 1 was repeated, except that only magnesium sulfate was used as a coagulant, and the amount of addition was 3.5% of the solid content in the latex. Resin was produced in the same manner as in Example 1. Various evaluation tests were performed on the obtained resin in the same manner as in Example 1. The results are shown in [Table 1] and [Table 2].

Comparative Example 3 A resin was produced in the same manner as in Example 1, except that the pH of the washing water was not adjusted in the washing step. At this time, the pH value of the washing water was 2. Various evaluation tests were performed on the obtained resin in the same manner as in Example 1. The results are shown in [Table 1] and [Table 2].

Comparative Example 4 A resin was produced in the same manner as in Example 2 except that the pH value of the washing water was adjusted to 8 in the washing step. Various evaluation tests were performed on the obtained resin in the same manner as in Example 1. The results are shown in [Table 1] and [Table 2].

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

The high nitrile-based resin obtained by the production method of the present invention has a higher impact resistance by thermoforming compared to the case where each is used alone by using aluminum sulfate and magnesium sulfate together as a coagulant. Almost no decrease, excellent transparency, little yellowing of resin due to heat history during molding, little burning of resin in molding machine, good releasability of resin from metal, good after molding This has an excellent effect that the cleaning is easy.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Asai 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Examiner at Mitsui Toatsu Chemicals Co., Ltd. Takaaki Harada (56) References JP-A-4-149216 (JP) JP-A-4-146909 (JP, A) JP-A-3-163118 (JP, A) JP-A-1-297402 (JP, A) JP-A-60-217224 (JP, A) JP-A-60-217224 58-147414 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 279/02 C08F 6/22

Claims (2)

(57) [Claims] 1. 100 parts by weight of a monomer mixture containing at least 50% by weight of an unsaturated nitrile and comprising at least one monomer copolymerizable with the unsaturated nitrile, is mixed with 1 to 40 parts by weight of a diene synthetic rubber. In the method for producing a high nitrile resin obtained by emulsion graft polymerization in the presence of
When a mixture of aluminum sulfate and magnesium sulfate is used as a coagulant in a polymer latex of H2 to 7 to coagulate the polymer, and when the coagulated polymer is washed with water, the pH of the washing water is adjusted to 4 with a basic substance. To 7. A method for producing a high nitrile resin. 2. The process for producing a high nitrile resin according to claim 1, wherein the coagulant is a mixture of aluminum sulfate and magnesium sulfate containing at least 1% by weight of aluminum sulfate based on the solid content of the polymer latex.