JPH0559133A - Production of high nitrile resin - Google Patents

Abstract

PURPOSE:To obtain a high nitrile resin excellent in moldability and transparency and reduced in the lowering of impact resistance and in the yellowing of the resin by using a strong acid Al salt as a coagulant for the obtained latex of the high nitrile resin and adjusting the pH of water when the coagulated resin is washed with the water. CONSTITUTION:(A) 100 pts.wt. of a monomer mixture comprising (i) >=50wt.% of an unsaturated nitrile and (ii) the balance of one or more kinds of monomers copolymerizable with the component (i) is subjected to an emulsion-graft- polymerization in the presence of (B) 1-40 pts.wt. of a dienic synthetic rubber and (C) a polymerization initiator, preferably a persulfate polymerization initiator. The obtained polymer latex having a pH of 2-7 is coagulated with a coagulant comprising a strong acid Al salt such as aluminum sulfate and subsequently washed with water having a pH of 4-7 (preferably 5-6) adjusted with a basic substance such as NaOH to obtain the objective resin.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a diene rubber having excellent transparency, impact resistance and processability in a well-balanced manner, and graft copolymerization of unsaturated nitrile and a monomer copolymerizable with unsaturated nitrile. 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 barrier properties against gas and vapor and solvent resistance, and have recently become practically useful 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, a resin latex obtained by emulsion polymerization is added in an appropriate amount with a coagulant such as an inorganic salt to form a paste, which is put into hot water in a strand form to coagulate. Well known is a method of recovering a solid polymer by washing with water, filtering the resulting slurry and drying.

[0003]

However, in the production of the high nitrile resin which is the object of the present invention, the recovered polymer is obtained by using an aluminum salt of a strong acid as a coagulant and washing it normally with water and drying it. When heated and melt-kneaded, there were problems such as a decrease in impact resistance, yellowing of the resin, a decrease in gloss, and burning of the resin in the molding machine.

As a resin having the same problems as described above,
For example, ABS resin and the like are available, and are disclosed in JP-A-58-147414.
In the publication, when a rubber elastic latex whose particle size is enlarged by phosphoric acid is used, there are problems such as deterioration of the surface appearance of the resin. However, when the resin latex is coagulated with an alkaline earth metal salt, It can be improved by adjusting the pH of the system to 4 to 7 during washing with water by using an acid.
No. 05 publication discloses that an ABS resin latex produced using a redox initiator is coagulated with an alkaline earth metal salt, and then, when washed with water, the pH of the washing water is adjusted to 7 or less by using an acid. Methods such as improving the thermal stability (drying process) of the ABS resin powder have been proposed.

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

Further, in JP-A-59-24709 and JP-A-59-24710, there is a problem of insufficient kneading and appearance of the resin surface when an ABS or MBS resin is mixed with another resin. With respect to, a method of improving the coagulated slurry of resin latex by setting the pH to 6 or less is proposed.

However, these methods are also characterized in that the coagulated product is not washed with water. Essentially, the auxiliary raw materials cannot be removed, and the problems caused by them are included. Therefore, the improvement effect is sufficient. I can't say.

The object of the present invention is to solve the above problems and to provide a method for producing a high nitrile resin having good moldability, excellent transparency, reduced impact resistance due to thermoforming, and less yellowing of the resin. To do.

[0009]

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 used an aluminum salt of a strong acid as a coagulant, and usually washed it with water and dried it. In this case, we found out that the auxiliary material emulsifier reacts with the coagulant, the product tends to remain in the resin, and that it causes the above-mentioned drawbacks because it deteriorates and decomposes due to heat during molding processing. It was Even more surprisingly, after coagulation using the above coagulant, the pH of the washing water is adjusted to 4 to 4 with a basic substance.
When the product is washed with water 7 and dried, the product is less likely to remain in the resin, the impact resistance of the resin is hardly reduced due to the thermoforming process, the yellowing of the resin is small, and further in the molding machine. The present invention has been completed by finding out that the resin of Example No. 1 is less burnt, the resin can be easily peeled off from the metal, and the molding machine can be easily cleaned after molding.

That is, in 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 the diene synthetic rubber 1 In a method for producing a high nitrile resin obtained by adding a polymerization initiator and carrying out emulsion graft polymerization in the presence of ˜40 parts by weight, the obtained polymer latex of pH 2 to 7 is used as a strong acid as a coagulant. When the polymer is coagulated using the aluminum salt of 1. and the coagulated polymer is washed with water, the pH of the washing water is adjusted to 4
It is a manufacturing method of the high nitrile system resin characterized by setting to -7.

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

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, acrylic rubber having excellent weather resistance may be used.

In the present invention, the high nitrile polymer is obtained by emulsion graft-polymerizing a large amount of unsaturated nitrile and other monomer components copolymerizable therewith with a preformed diene synthetic rubber. Oxygen is removed by a generally known emulsion polymerization method from about 0 to 100 ° C.
At this temperature, the monomer and other components can be polymerized by batchwise, continuous or divided addition.

When a monomer is polymerized in the presence of rubber, examples of the polymerization initiator used include persulfuric acid, peracetic acid, and peracids such as perphthalic acid, peracid salts such as potassium persulfate, and peroxidation. 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, alkyl 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 kinds. The persulfates are preferable.

The emulsifier used in the present invention is preferably an anionic surfactant, and examples thereof include fatty acid salts, higher alcohol sulfuric acid ester salts, liquid fatty oil sulfuric acid ester salts, aliphatic amine and aliphatic amide sulfates, and aliphatic salts. Alcohol phosphate ester salts, dibasic fatty acid ester sulfonates, aliphatic amide sulfonates,
Examples include formalin-condensed naphthalene sulfonates.

The molecular weight regulator used in the present invention is an alkyl mercaptan, such as n-dodecyl mercaptan, tert-dodecyl mercaptan, n-dodecyl thioacetate, pentaerythritol tetrakis (β-mercaptopropionate), limonene dimercaptan. Etc.

Examples of the strong acid aluminum salt used as the coagulant in the present invention include aluminum sulfate, aluminum chloride and aluminum nitrate.

The basic substance used for adjusting the pH of the washing water in the present invention includes alkali metal hydroxides or oxides, alkaline earth metal hydroxides or oxides, weak acid salts and the like. And a hydroxide of an alkali metal is preferable.

The method for producing a high nitrile resin of the present invention comprises:
Using the above-mentioned raw materials, a resin latex can be obtained by a generally known emulsion polymerization method, and an aluminum salt of a strong acid can be used as a coagulant to coagulate it by a conventionally known salting-out method. For example, latex and aluminum sulfate are continuously introduced into the mixing chamber of the screw pump, and the paste-like material produced by mixing is formed into a strand form, which is put into hot water close to the softening temperature of the resin to solidify the polymer. Can be collected. Alternatively, the latex and aluminum sulfate may be mixed by a mixer such as a static mixer.

The solid content concentration of the latex is preferably 20 to 40% by weight, and one of the coagulants, aluminum sulfate, is used in the form of an aqueous solution. The addition amount to the latex is aluminum sulfate pure content based on the latex solid content. It is preferably 1 to 5% by weight.

The coagulated product obtained in the coagulation step is washed in the water washing step. In this case, the pH of the washing water is adjusted with a basic substance to a range of 4 to 7, preferably a range of 5 to 6 for washing. When the pH is less than 4, the hue of the obtained resin changes to dark brown, the heat discoloration is large, and the resin is burnt during molding. On the other hand, if it exceeds 7, the resin is yellowed to cause a large thermal discoloration, and the impact strength and the transparency are deteriorated.

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 such as extrusion molding, injection molding or blow molding. It is a resin, has a high barrier property against vapor and gas, has excellent solvent resistance, impact resistance, and has excellent transparency, so it is particularly useful as a bottle, film, and other types of liquid / solid packaging container materials. Is.

[0025]

The present invention will be described below with reference to examples. All "parts" and "%" in the examples are by weight.

Example 1 (A) Production of Conjugated Diene Rubber Latex A mixture of the following components was subjected to nitrogen substitution in a stainless steel polymerization reactor to remove oxygen, and stirred at 50 ° C. for 20 minutes.
Polymerization was carried out for a time. Acrylonitrile 30 parts 1,3-butadiene 70 parts Fatty acid soap 2.4 parts Azobisisobutyronitrile 0.3 parts t-dodecyl mercaptan 0.5 parts Water 200 parts Monomer addition rate is 90%, latex solid The concentration is 3
It was 0%.

(B) Production of Graft Polymer The following raw materials were charged in a polymerization reactor, oxygen was removed by nitrogen substitution, 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 Polyvinylpyrrolidone 0.4 parts Potassium persulfate 0.06 parts n-Dodecyl mercaptan 1.3 parts Single quantity The conversion of the body is 90%, the pH of the latex obtained
Was 7, and the solid content concentration was 30%.

An aluminum sulfate aqueous solution having a concentration of 40% was added to the obtained latex in an amount of 3.5% based on the solid content in the latex to form a paste, which was put into warm water at 75 ° C. in a strand form to coagulate. Let P of the coagulum at this time
H was 1.2. Then, the coagulated product was washed with water in a washing tank. At this time, the pH of the wash water was adjusted to 4 with 1% by weight sodium hydroxide. After washing with water, filtration and drying were performed to obtain a resin.

The resin thus obtained was roll-kneaded at 160 ° C. to prepare a sheet.
A transparent press sheet was obtained by pressure molding at 00 kg / cm ² G. The obtained press sheet is ASTM D256
The Izod impact value (Izod) with notch at 23 ° C. and 3.83 kg load was measured in accordance with
Yellowing degree (YI = Yel) according to STM D1925
The low index was measured. Further, as a test corresponding to thermal discoloration at the time of molding, the yellowing degree was measured by changing the normal press sheet molding conditions of 174 ° C. × 4 minutes to 184 ° C. × 10 minutes. The results are shown in [Table 1].

Further, in order to evaluate the thermal stability with respect to burning during molding and the ease of cleaning the molding machine, 30
mmφ extruder temperature 230 ℃, screw rotation speed 45
The resin was run at rpm for 1 hour, and the state of burning of the resin under harsh temperature conditions and the ease of cleaning (ease of removal of the adhered resin from the screw, die, etc.) were evaluated. The results are shown in [Table 2].

Example 2 A resin was produced in the same manner as in Example 1 except that the pH of the washing water was adjusted to 5 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].

Example 3 A resin was produced in the same manner as in Example 1 except that the pH of the washing water was adjusted to 6 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].

Example 4 A resin was produced in the same manner as in Example 1 except that the pH of the washing water was adjusted to 7 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].

Comparative Example 1 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. The pH of the rinsing water at this time 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 2 A resin was produced in the same manner as in Example 1 except that the pH 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].

Example 5 In Example 1, polymerization was carried out by adding phosphoric acid at the initiation of the polymerization of (B) to adjust the system pH to 3.5. The pH of the obtained latex was 4. In the subsequent treatment, a resin was obtained by coagulating, washing with water, filtering and drying in the same manner as in Example 1 except that the pH of the washing water was adjusted to 5. 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].

Example 6 A resin was produced in the same manner as in Example 5, except that the pH of the washing water was adjusted to 6 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].

Comparative Example 3 A resin was produced in the same manner as in Example 5 except that the pH 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].

Comparative Example 4 A resin was produced in the same manner as in Example 6 except that magnesium sulfate was used as the coagulant. 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].

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

EFFECTS OF THE INVENTION The high nitrile resin obtained by the production method of the present invention shows almost no deterioration in impact resistance due to thermoforming process, and the yellowing of the resin due to the heat history during the forming process is small. There is little burning of the resin in the machine, good releasability of the resin from the metal, and easy cleaning after molding.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuichi Fukushima 2-1-1 Tangodori, Minami-ku, Nagoya-shi, Aichi Mitsui Toatsu Chemicals, Inc. (72) Inventor Shuichi Yamaguchi 2 Tango-dori, Minami-ku, Nagoya, Aichi 1-chome Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. 100 parts by weight of a monomer mixture containing at least 50% by weight of an unsaturated nitrile and at least one monomer copolymerizable with the unsaturated nitrile, and 1 to 40 parts by weight of a diene synthetic rubber. In the method for producing a high nitrile resin obtained by emulsion polymerization by adding a polymerization initiator in the presence of, a polymer latex having a pH of 2 to 7 is obtained,
A high nitrile system characterized in that when a strong acid aluminum salt is used as a coagulant to coagulate a polymer and the coagulated polymer is washed with water, the pH of the washing water is adjusted to 4 to 7 with a basic substance. Resin manufacturing method. 2. The method for producing a high nitrile resin according to claim 1, wherein the polymerization initiator is a persulfate polymerization initiator.