KR100494832B1 - A manufacturing method of thermoplastic resin with the superior heat resisting property and the easy wastewater treatment - Google Patents

Abstract

The present invention relates to a method for preparing a thermoplastic composition having excellent heat resistance and easy wastewater treatment, and more particularly, in preparing a thermoplastic composition by emulsion polymerization using a monomer mixture comprising α-alkylstyrene and unsaturated nitrile. Minimize the amount of additives used, and use environmentally friendly emulsifiers instead of organic dispersants that are not decomposed by microorganisms in the treatment of the generated wastewater. By minimizing the amount of monomer produced, the copolymer composition of the thermoplastic composition is easy, heat resistance is excellent, and the chemical oxygen demand (COD) and total nitrogen (TN) are significantly lower during the treatment of waste water remaining after the manufacturing process is completed. It is possible to produce a friendly and excellent thermoplastic composition.

Description

A manufacturing method of thermoplastic resin with the superior heat resisting property and the easy wastewater treatment}

The present invention relates to a method for preparing a thermoplastic composition having excellent heat resistance and easy wastewater treatment, and more particularly, in preparing a thermoplastic composition by emulsion polymerization using a monomer mixture comprising α-alkylstyrene and unsaturated nitrile. Minimize the amount of additives used, and use environmentally friendly emulsifiers instead of organic dispersants that are not decomposed by microorganisms in the treatment of the generated wastewater. By minimizing the amount of monomers produced, the thermoplastic composition is easy to form copolymers, has excellent heat resistance, and has low chemical oxygen demand and total nitrogen in the treatment of waste water remaining after the manufacturing process. Can be prepared.

Generally, as a method of producing a radical copolymer containing? -Alkyl styrene and an unsaturated nitrile as a monomer, there are largely an emulsion polymerization method and a bulk polymerization method.

First, the bulk polymerization method is low in manufacturing cost because almost no other additives other than the mixture of the α-alkylstyrene monomer and the unsaturated nitrile monomer, the initiator and the small amount of oil are contained, and the polymer is itself a finished product after the polymerization is completed. The waste water treatment process does not exist because no process is required, but there is a limit in increasing the content of α-alkylstyrene due to the polymerization property, and thus has a disadvantage in that the heat resistance of the produced polymer is lowered.

The method for preparing a radical copolymer by emulsion polymerization of α-alkyl styrene and unsaturated nitrile was developed by Sumitomo Co., Ltd. in 1978. After completion of polymerization, sintering, dehydration and drying are performed. After mixing with ternary copolymer resins of acrylonitrile-butadiene-styrene and other additives, the present invention is applied to automotive interior materials, electric ovens, microwave ovens and the like requiring heat resistance.

However, unlike the bulk polymerization method, since the emulsion polymerization method has a large amount of additives and the prepared polymer is emulsified in a medium of pure water, a later step of recovering the polymer emulsified in the medium is required after the polymerization is completed. Therefore, the problem of treatment of wastewater generated in this process remains a problem to be solved. However, although most of the additives used in the polymerization coexist with the polymers and cause a problem, it is possible to increase the content of α-alkyl styrene much more than the bulk polymerization method. It is characterized by excellent heat resistance and has been used continuously.

According to Japanese Patent Application Laid-Open Nos. 55-78043, 55-7873 and 55-78007, the heat resistance of the copolymer obtained according to the emulsion polymerization method of the radical copolymer using? -Alkylstyrene and unsaturated nitrile as monomers Although it is excellent, the amount of various additives introduced during the polymerization is too high, and the organic waste is not decomposed by the microorganisms in the wastewater generated in the later stage of the emulsion polymerization, and thus there is a problem that the direct wastewater treatment is impossible. However, if the additive causing the above problems is not introduced during the polymerization, the viscosity of the latex is extremely increased during the polymerization, so that the polymerization cannot proceed any further, and the polymerization initial stage is to be solved. The number of particles produced in the present invention was also controlled. In this case, an excessive amount of unreacted monomers remained in the wastewater caused by the loss of raw materials.

Conventionally, in the method for preparing a radical copolymer by the emulsion polymerization method using α-alkyl styrene and unsaturated nitrile as monomers, an organic dispersant is used for maintaining viscosity between polymerizations, latex stability, and proper polymerization. For example,

Here, n is an integer in the range of 5-10.

The organic dispersant has excellent ability as an additive for polymerization, but has a big problem in that it is not decomposed at all by microorganisms in the wastewater treatment process.

That is, in the conventional method, the input amount of the initial emulsifier was excessively increased due to the low polymerization rate of α-alkyl styrene, and when the use of the polymerization additive was excluded, the viscosity during the polymerization was as high as 1000 to Brookfield viscometer. It can go up to 40000 cps and no longer allow the polymerization to proceed. In addition, if the initial amount of the emulsifier is reduced in order to prevent such a viscosity increase, the polymerization rate is delayed, so that many unreacted monomers remain in the latex, resulting in loss of the polymerization raw material.

As described above, the thermoplastic composition prepared by emulsion polymerization using α-alkyl styrene and unsaturated nitrile as monomers is advantageous in increasing the heat resistance of the final molded product, but various additives are added for proper polymerization progress. In addition to the high chemical oxygen demand of the waste water remaining in the process of obtaining the final polymer, it contains an organic dispersant that is not decomposed by microorganisms, making the waste water treatment almost impossible.

Due to the difficulty of the direct wastewater treatment, a storage tank for storing only the wastewater is needed, and the productivity of the polymer is also limited due to the limited capacity of the storage tank.

Therefore, in order to exclude the organic dispersant, which is a problem of wastewater treatment remaining after the emulsion polymerization method, there remains a problem of simultaneously solving two problems, namely, increasing the viscosity between polymerizations and achieving an appropriate polymerization rate.

Accordingly, the inventors of the present invention have made an effort to solve the above problems, and as a result, organic dispersants and other unnecessary additives that are problematic for the wastewater treatment are drastically excluded and applicable additives are also easily reduced by reducing the amount of wastewater treatment. A polymer of the thermoplastic composition obtained by newly introducing and using a biodegradable emulsifier in order to solve the problems between the polymerization caused by the exclusion and reduction of the existing additives, and by adding these emulsifiers separately during the polymerization reaction It was found that the stability of the excellent and can achieve an appropriate polymerization progress rate to produce a thermoplastic composition excellent in heat resistance with excellent polymerization conversion rate was completed the present invention.

Accordingly, an object of the present invention is to provide a method for producing a thermoplastic composition which is easy to treat wastewater, facilitates polymerization, and has excellent heat resistance.

The present invention provides a method for producing a thermoplastic composition by emulsion polymerization using α-alkyl styrene and unsaturated nitrile as monomers, comprising: 1) 60 to 80 wt% of α-alkyl styrene and 20 to 40 wt% of unsaturated nitrile. When the total amount of the monomer mixture is 100 parts by weight, 0.05 to 0.5 parts by weight of the emulsifier (A) and 0.05 to 0.5 parts by weight of the molecular weight modifier in 5 to 25% by weight of the total amount of the monomer mixture in the process of gradually increasing the temperature to 40 to 60 ℃ Forming an initial seed while maintaining the temperature range after adding the part; and 2) adding 0.3 to 1.3 parts by weight of an initiator to the reactant on which the seed was formed, and gradually raising the temperature of the mixture to 70 to 90 ° C. Next, here the remainder of the total amount of the monomer mixture and 1.0 to 3.0 parts by weight of the molecular weight regulator and 0.7 to 2.0 parts by weight of the emulsifier (B) in the above temperature range for a certain time After the rapid injection, and after the continuous injection, the thermoplastic composition having a high heat resistance comprising the step of inserting 0.1 to 0.7 parts by weight of the initiator and 0.3 to 1.0 parts by weight of the emulsifier (B) and maintaining the temperature range for a predetermined time to form a copolymer Characterized in that the manufacturing method.

The present invention will be described in more detail as follows.

The present invention minimizes the amount of additives used in preparing a thermoplastic composition by emulsion polymerization using a monomer mixture including α-alkylstyrene and unsaturated nitrile, and is not decomposed by microorganisms during the treatment of the generated wastewater. Instead of organic dispersants, environmentally friendly emulsifiers are used, and by controlling the method of injecting mixtures and additives of each emulsifier and monomer to minimize the amount of unreacted monomers, the copolymer of the thermoplastic composition is easily formed, and the heat resistance is excellent while the manufacturing process The present invention relates to a method for preparing a thermoplastic composition which is environmentally friendly and has excellent physical properties by significantly reducing the chemical oxygen demand (COD) and the total nitrogen amount (T-N) during the treatment of waste water remaining after the end.

The present invention will be described in detail for each manufacturing step as follows.

First, in preparing the thermoplastic composition by emulsion polymerization using α-alkyl styrene and unsaturated nitrile as monomers, when the total amount of the monomer mixture consisting of α-alkyl styrene and unsaturated nitrile is 100 parts by weight, After adding a part of the monomer mixture, an emulsifier (A) and a molecular weight modifier, the temperature is gradually raised to 40 to 60 ° C., and then an initial seed is formed while maintaining the temperature range.

A monomer mixture consisting of 60 to 80% by weight of the α-alkylstyrene and 20 to 40% by weight of unsaturated nitrile is prepared. When the amount of the α-alkylstyrene is less than 60% by weight, the heat resistance is lowered. The flowability of a molded article becomes low and productivity falls. In this case, the α-alkyl styrene may be used one or a mixture of two or more selected from α-methylstyrene, α-ethylstyrene, methyl-α-methylstyrene, and the like, and the unsaturated nitrile may be acrylonitrile or methacryl. One or a mixture of two or more selected from ronitrile and ethacrylonitrile and the like is used.

In inserting the monomer mixture, first, when the total amount of the monomer mixture is 100 parts by weight in the initial temperature raising process, 5 to 25% by weight of a part thereof is inserted and 0.05 to 0.5 parts by weight of the emulsifier (A) is used. If the amount of (A) is less than 0.05 part by weight, the polymerization rate is lowered. In this case, the emulsifier (A) may be used one or a mixture of two or more selected from fatty acid salts, oleates and alkali metal salts of alkyl sulfonates.

The molecular weight regulator may be used 0.05 to 0.5 parts by weight, n-dodecyl mercaptan, n- amyl mercaptan, t- butyl mercaptan, t- dodecyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan And one or a mixture of two or more selected from n-nonyl mercaptan and the like can be used.

As a second step, after the completion of the first step, an initiator is added, and the temperature of the mixture is gradually raised to 70-90 ° C. while maintaining a certain time in the temperature range, the remaining part of the monomer mixture, the remaining part of the initiator, It is a step of dividing-injecting a molecular weight modifier and an emulsifier (B) to form a copolymer.

The present invention excludes the use of organic dispersants and chelating agents containing nitrogen elements that cause problems in wastewater treatment, and makes wastewater treatment easier by reducing the content of unsaturated nitriles, especially among unreacted monomers remaining in the wastewater without reacting. To lose.

When the mixture having a predetermined amount of seeds is gradually heated up again and the temperature of the mixture reaches 70 to 90 ° C., the remaining monomer mixture 75 to 95 wt% and the molecular weight modifier and the emulsifier (B) which are purchased in the seed forming step are continuously While injecting, the mixture is stirred while maintaining the temperature range for a certain time. Here, the emulsifier (B) is added by dividing, and after the first step is finished, the temperature of the mixture is raised to 70 ~ 90oC and stirred while maintaining the above temperature range for a predetermined time while continuously injecting a portion with a molecular weight regulator to react the reaction. Proceed.

The amount of the emulsifier (B) is 1.0 to 3.0 parts by weight based on 100 parts by weight of the total amount of the total monomer mixture, which is divided into two or more times during the reaction, and then 0.7 to 2.0 parts by weight is added first. After the end of the continuous injection, by adding 0.3 to 1.0 parts by weight to improve the polymerization conversion of α-alkylstyrene and unsaturated nitrile monomer. If the total amount of the emulsifier (B) to be divided and injected as described above is less than 1.0 part by weight, the inter-polymerization emulsification stability is lowered, and if it exceeds 4.0 parts by weight, it may cause an increase in the viscosity between polymerizations. As the emulsifier (B), one or a mixture of two or more selected from rosin acid salts, alkali metal salts of alkyl sulfates and fatty acid salts of alkyl sulfates is used. Unlike conventional organic dispersants, a component having excellent biodegradability by microorganisms is used. It is a feature of the present invention.

The initiator may use an initiator conventionally used in the art, but minimizes the amount of the initiator used in the conventional emulsion polymerization method. That is, the total amount of the initiator is 0.4 to 2.0 parts by weight, and the timing of the injection is 0.3 to 1.3 parts by weight, which is a part of the temperature increase after completion of step 1, and the temperature of the mixture reaches 70 to 90 ° C. after the temperature is raised. Then, after a continuous injection of 75 to 95% by weight of the remainder of the monomer mixture, 1.0 to 3.0 parts by weight of the molecular weight modifier and 0.7 to 2.0 parts by weight of the emulsifier (B), the remainder of the initiator is introduced and the amount used is 0.1 It is-0.7 weight part. Initiators which can be used include potassium persulfate and ammonium persulfate. The molecular weight modifier is used 1.1 to 3.5 parts by weight based on 100 parts by weight of the total amount of the monomer mixture, if the amount is less than 1.1 parts by weight excessively increased, if it exceeds 3.5 parts by weight the molecular weight is too low and the physical properties are lowered . The molecular weight regulator is selected from n-dodecyl mercaptan, n-amyl mercaptan, t-butyl mercaptan, t-dodecyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-nonyl mercaptan and the like. One kind or a mixture of two or more kinds can be used.

Therefore, in the present invention, by reducing the unreacted monomer content of unsaturated nitrile, which is the main culprit in increasing the amount of organic dispersant and total nitrogen, which is a problem of wastewater treatment, and excluding the chelating agent containing nitrogen element, it becomes an index of the ease of wastewater treatment. The chemical oxygen demand and the total nitrogen can be significantly reduced, the final polymer produced by the above method has a molecular weight of 10 to 200,000, the glass transition temperature is shown to be 100 ~ 130 ℃ high heat resistance, and the reaction proceeds It shows excellent physical properties such as low viscosity during the process.

Such polymers are subjected to sintering, dehydration and drying after completion of polymerization, and then mixed with terpolymer copolymer resin and other additives of acrylonitrile-butadiene-styrene and other automotive interior materials or electric ovens requiring heat resistance. It is applied to electric and electronic parts such as microwave oven, etc.

Accordingly, the present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention thereto.

Examples 1-3

Pure water was added at room temperature and 5.0 wt% of a monomer mixture consisting of α-methylstyrene and acrylonitrile and alkylbenzenesulfonate were added while the temperature was raised to 40 to 60 ° C. When the temperature of the mixture exceeded 60 ° C. in the course of raising the temperature, 0.5 parts by weight of potassium persulfate was first introduced as an initiator, and the temperature of the mixture was again raised to 70 to 90 ° C. When the temperature of the mixture reaches 70 to 90 ° C., 95% by weight of the monomer mixture consisting of α-methylstyrene and acrylonitrile, 1.0 part by weight of sodium rotate and t-dode as a molecular weight modifier over 4 hours while maintaining the temperature. 0.2 parts by weight of silmercaptan was continuously injected, and after the end of the continuous injection, 0.5 parts by weight of the remaining sodium rosinate and 0.1 parts by weight of potassium persulfate were added, and further stirred for 5 hours, followed by cooling to obtain a latex of the thermoplastic composition of the present invention. It was.

After filtering a small amount of latex of the obtained thermoplastic composition, the unreacted monomer content was analyzed by gas chromatography to evaluate the polymerization conversion rate and the polymerization progress rate, and the heat resistance of the latex of the obtained thermoplastic composition was determined by the glass transition temperature. (Tg) was measured and evaluated. The chemical oxygen demand was measured by the potassium permanganate titration method, and the total nitrogen was measured by the ultraviolet absorbance method.

The composition and the amount used in the preparation of the thermoplastic composition, the results of the polymer analysis of the latex, and the chemical oxygen demand and total nitrogen of the wastewater are shown in Table 1 below.

Comparative Examples 1 to 4

Pure water was injected at normal temperature, and 5.0 weight% of the monomer mixtures which consist of (alpha) -methylstyrene and acrylonitrile, 0.3 weight part of sodium oleate, and sodium ethylenediamine tetraacetate were added, heating up the temperature to 40-60 degreeC. When the temperature of the mixture exceeded 60 ° C. in the course of raising the temperature, 1.0 parts by weight of potassium persulfate was inserted and the temperature of the mixture was raised again to 70 to 90 ° C. When the temperature of the mixture reaches 70 to 90 ° C., 95% by weight of the monomer mixture consisting of α-methylstyrene and acrylonitrile, 2.5 parts by weight of sodium oleate and t-dodecyl as molecular weight regulators are maintained over 4 hours while maintaining the temperature. 1.0 parts by weight of mercaptan was continuously injected, and after the end of continuous injection, 0.3 parts by weight of the remaining sodium oleate and 0.5 parts by weight of potassium persulfate were added, followed by further stirring for 5 hours, followed by cooling to obtain a latex.

The physical properties of the obtained latex was carried out in the same manner as in Examples 1 to 3, the composition component and the amount used in the preparation of the composition, the results of the polymer analysis of the latex and the chemical oxygen demand and total nitrogen of the waste water are shown in Table 2 Shown in

As shown in Tables 1 and 2, the thermoplastic composition of the present invention does not use an organic dispersant and sodium ethylenediaminetetraacetate, which are used in the past, and alkylbenzenesulfonate as an emulsifier having excellent biodegradability in selecting an emulsifier. Partially injected using rosinate (Examples 1-3). In Examples 1 to 3, the viscosity and the content of unreacted monomers are significantly lower than those of Comparative Examples 1 to 4, and the chemical oxygen demand and total nitrogen content of the waste water remaining after the thermoplastic composition is prepared are low. . In addition, it can be seen that the glass transition temperature is higher than that of the thermoplastic compositions prepared by Comparative Examples 1 to 4, thereby showing excellent heat resistance.

As described above, according to the method for preparing a thermoplastic composition according to the present invention, using a monomer mixture containing an existing α-alkyl styrene and an unsaturated nitrile, it is decomposed by a microorganism used to prepare the thermoplastic composition by emulsion polymerization. Instead of using organic dispersants, a biodegradable, environmentally friendly emulsifier was used, but the method of split injection was applied, and the amount of other additives was minimized to minimize the production of unreacted monomers. In the treatment of waste water remaining after the end of the process, the chemical oxygen demand and the total nitrogen amount are significantly low, thereby reducing the manufacturing cost required for the manufacturing process due to environmentally friendly effects, elimination of organic dispersants and other additives. In addition, it is easy to form a copolymer (latex, seed) of the thermoplastic composition, the copolymer of the prepared thermoplastic composition is low in viscosity during polymerization, the reaction occurs easily, and the heat resistance is superior to that prepared by the conventional method. .

1 is a graph briefly illustrating a polymerization process by introducing an emulsifier into a thermoplastic composition according to the present invention.

Claims (7)

In the method for producing a thermoplastic composition by emulsion polymerization method using an alkyl styrene and an unsaturated nitrile as a monomer, 1) When the total amount of the monomer mixture consisting of 60 to 80% by weight of α-alkylstyrene and 20 to 40% by weight of unsaturated nitrile is 100 parts by weight, the emulsifier (A) is 0.05 to 5 to 25% by weight of the total amount of the monomer mixture. Adding 0.5 to 0.5 parts by weight and 0.05 to 0.5 parts by weight of a molecular weight modifier and then gradually raising the temperature to 40 to 60 ° C. to form an initial seed while maintaining the temperature range; 2) Add 0.3 to 1.3 parts by weight of an initiator to the reactant having the seed formed thereon, and gradually increase the temperature of the mixture to 70 to 90 ° C., and then add the remainder of the total amount of the monomer mixture and 1.0 to 3.0 parts by weight of the molecular weight regulator and the emulsifier. (B) 0.7 to 2.0 parts by weight of continuous injection, while maintaining a predetermined time in the temperature range, 0.1 to 0.7 parts by weight of the initiator and 0.3 to 1.0 parts by weight of the emulsifier (B) to form a copolymer Method for producing a thermoplastic composition excellent heat resistance comprising a. The method of claim 1, wherein the α-alkylstyrene is one or a mixture of two or more selected from α-methylstyrene, α-ethylstyrene, and methyl-α-methylstyrene. . The method of claim 1, wherein the unsaturated nitrile is one or a mixture of two or more selected from acrylonitrile, methacrylonitrile, and ethacrylonitrile. The method according to claim 1, wherein the emulsifier (A) is one or a mixture of two or more selected from alkali metal salts of fatty acid salts, oleate salts and alkyl sulfonates.  The method according to claim 1, wherein the emulsifier (B) is one or a mixture of two or more selected from rosin acid salts, alkali metal salts of alkyl sulfates and fatty acid salts of alkyl sulfates. The method of claim 1, wherein the molecular weight modifier is n-dodecyl mercaptan, n-amyl mercaptan, t-butyl mercaptan, t-dodecyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan and n- A method for producing a thermoplastic composition having excellent heat resistance, characterized in that one or a mixture of two or more selected from nonyl mercaptan. The thermoplastic composition excellent in heat resistance manufactured by the manufacturing method in any one of Claims 1-6 whose molecular weight of a final polymer is 100,000-200,000, and glass transition temperature is 100-130 degreeC.