JPS61272219A - Production of rubber-modified thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain a resin having improved surface appearance and various physical properties, by separating an aqueous phase from a mixed phase consisting of a specific graft rubber polymer latex, thermoplastic resin and a specific amount of a specified organic chemical, and treating the residual organic phase by thermal means. CONSTITUTION:An aqueous phase is separated from a two-phase mixture obtained by mixing (A) a latex of a graft rubber polymer prepared by graft polymerizing a vinyl based monomer with a rubber latex, with (B) a thermoplastic resin and (C) an organic solvent, capable of dissolving the resin (B), and having 5-50wt% solubility in water in an amount of 0.2-6 times based on the total polymer and the organic chemical and water are separated from the residual organic phase by thermal means to afford the aimed resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of industrial application] The present invention relates to the production of rubber-modified thermoplastic resins. When producing a rubber-modified thermoplastic resin by combining and mixing thermoplastic resins, after mixing the latex of the rubber polymer, the organic drug, and the thermoplastic resin, the aqueous phase and the organic solvent are sequentially separated from the mixture. The present invention relates to a method for producing a rubber-modified thermoplastic resin characterized by:

[Conventional technology]

In general, most of the rubber-modified thermoplastic resins represented by ABS resin are made by mixing a thermoplastic resin with a polymer obtained by graft polymerizing a vinyl monomer to rubber latex.
It is kneaded. The manufacturing process usually includes an emulsion graft polymerization process, a coagulation process, a dehydration drying process, a blending process, and a melt extrusion process. In the emulsion graft polymerization process, acrylic monomer, vinyl cyan monomer, etc. are added to diene rubber latex, vinyl rubber latex, natural rubber latex, silicone rubber latex, etc.
Vinyl aromatic system.

This is a process for producing graft polymer latex by emulsion graft polymerization of monomers and the like. The coagulation step is a step in which a coagulant such as a polyvalent salt or an acid is added to the graft polymer latex to break the emulsified state and coagulate on the polymer to form a powder. The dehydration drying process is a process in which the aqueous phase is separated from a mixture of powder, dipolymer, and water by means such as centrifugal dehydration, and then the powder is dried by means such as fluidized drying to obtain dry powder. be. The blending process is a process of blending the dry powder with other thermoplastic resins and additives such as stabilizers, lubricants, and plasticizers.The melt extrusion process involves melting and kneading the blended raw materials using a device such as a screw extruder. This process involves extruding it into a strand and shaping it into a pellet.

The first manufacturing and quality problems brought about by the rubber-modified thermoplastic resin manufacturing process comprised of the above steps are that a large amount of heat is used.

This is due to the large amount of hot air used in the drying process. The second problem is that the kraft rubber particles are completely fixed in the coagulation process, and it takes a lot of effort to completely disperse the kraft rubber particles in the thermoplastic resin during the melting and cross-crossing operations after blending. This means that it requires the power of Furthermore, in the worst case, it becomes industrially impossible to uniformly disperse the graft rubber particles in the thermoplastic resin.

Several proposals have been made to improve the conventional manufacturing methods that lead to a decline in industrial competitiveness as described above, some of which have been implemented industrially. One of these is a t-V with dehydration function, commonly called a dehydration extruder, which aims to reduce the amount of heat used in the drying process.
It utilizes a single screw extruder. This type of proposed method involves blending the wet graft rubber powder with other thermoplastic resins and additives after coagulation and dehydration, or supplying the wet graft rubber powder alone to the dehydration extruder. The graft rubber latex and the coagulant, if necessary, and other thermoplastic resins and additives are also supplied simultaneously to the dehydration extrusion process.

This hot method does not require a drying process that uses a large amount of hot air, so it can be expected to be very effective in terms of reducing the amount of heat used. In the former method, the graft rubber particles are completely fixed together, so the latter method is equivalent to the conventional technology from the viewpoint of particle dispersion.In the latter method, the latex and coagulant are first mixed in the processing equipment. After that, dehydration is carried out at a temperature of about 100° C. or lower, at which point the grafted rubber particles are usually in a state of being fixed to each other. Then, as the temperature rises, the thermoplastic resin and the thermoplastic resin melt together and are subjected to crosstalk operation, so the former method differs only in the state of the supplied raw material, and from the viewpoint of particle dispersion, the former method is different from the former method. Similarly, it does not leave the realm of old technology.

Another method is to mix kraft rubber latex, a coagulant, and a monomer to create a two-phase a@
A method of separating the aqueous phase and polymerizing the monomers contained in the growth phase, and polymerizing the monomers without completely separating the aqueous phase of the two-phase mixture t″1, and then separating the aqueous phase. A method has been proposed in which the rubber particles are separated and the polymer is dried.These methods do not involve a process in which the rubber particles completely stick to each other, and are different from the method using the dehydrating extruder described above. It is very distinctive in terms of particle dispersion.However,
In the former method, it is necessary to polymerize a highly viscous mixture consisting of a mochi-like Natsu9 graft polymer and a monomer without causing a runaway reaction, and there are difficulties in terms of equipment and operation, so it is not necessarily a superior method. It's hard to say. Moreover, in rubber-modified thermoplastic resins, the content of the rubber component has a great effect on the basic physical properties of the resin, so polymerization is completely completed at a low polymerization rate with large polymerization rate fluctuations, as is done in ordinary bulk polymerization methods. However, the method of devolatilizing the remaining monomer cannot be used,
Because it is necessary to allow the reaction to proceed until a high polymerization rate is reached, which reduces fluctuations in the polymerization force, the reactant becomes a highly viscous mixture compared to general bulk polymerization systems, making it extremely difficult to handle. Become. In addition, the latter method is a method in which all monomers are polymerized by suspension polymerization, and although the viscosity of the system is small and the heat of reaction can be easily removed, it is the same as the former method, which requires dehydration and drying steps. It is difficult to say that this method is the same.

In order to overcome this current situation, we have previously proposed a method for producing a rubber-modified thermoplastic resin using all organic agents and coagulating agents. This method was a method of producing a rubber-modified thermoplastic resin by sequentially removing water and an organic agent from a combination of a latex of a grafted rubber polymer, a thermoplastic resin, a coagulating agent, and an organic agent. Resins produced using this method, like resins produced using traditional methods, contain latex-derived emulsifiers,
It contains emulsion polymerization aids such as emulsion stabilizers, which cause overall deterioration of the product's color, thermal stability, and moldability.

Therefore, we focused our efforts on developing a method that could remove most of the emulsion polymerization aid into the aqueous phase, and as a result, we discovered an efficient method for producing F12 rubber-modified thermoplastic resin with excellent white skin and transparency. .

[Problems to be solved by the present invention]

Many proposals have been made regarding the manufacturing method of rubber-modified thermoplastic resins as described above, but uniform dispersion of rubber particles and reduction of the amount of heat used are essential for the development of the basic physical properties of the resins. At present, it has not yet been possible to provide a high-quality and competitive method for producing the resin, which simultaneously solves the problems and contains almost no emulsion polymerization auxiliary agent as an impurity. Therefore, the present invention enables uniform dispersion of grafted rubber particles in a thermoplastic resin, and provides an entire process for producing high-quality rubber-modified thermoplastic resins in an energy-saving process and containing almost no emulsion polymerization aid. This is what we are trying to provide.

[Ninth way to solve the problem]

The present invention provides a graft polymer latex obtained by graft polymerizing a vinyl monomer onto rubber latex, a thermoplastic resin, and a thermoplastic resin that is 12 times or more and 6 times or less, on a weight basis, relative to the total polymer. has the ability to dissolve;
and the solubility in water is 5% by weight or more at 25°C.
It is characterized by first separating an aqueous phase from a two-phase mixture formed by mixing an organic drug in an amount of 0% by weight or less, and then separating the organic drug and remaining water from the remaining organic phase mixture by thermal means. The present invention relates to a method for producing a rubber-modified thermoplastic resin.

The present invention will be explained in more detail. The rubber latex that can be used in the present invention includes all those conventionally used as raw materials for rubber-modified thermoplastic resins, such as polybutadiene, polyisoprene, latex of diene rubber such as 13BR, and ethylene-propylene. rubber, olefin rubber latex such as ethylene-vinyl acetate rubber,
Examples include latex of acrylic rubber such as polymethyl methacrylate and polybutyl methacrylate, latex of silicone rubber such as polydimethylsiloxane, etc. These can be used alone or in combination of two or more.

In the present invention, there are no particular restrictions on the type of rubber, and if the rubber-modified thermoplastic resin to be produced is a latex of a polymer that has rubber elasticity in the temperature range, latexes other than those listed above may be used. Needless to say, it can be used even if It is extremely difficult to uniformly disperse the rubber particles contained in the rubber latex into the thermoplastic resin, and even if it were possible, the compatibility between the rubber and the thermoplastic resin would be poor. Due to unfavorable reasons, satisfactory physical properties cannot be achieved. Therefore, graft polymerization is carried out as a means to improve compatibility, enable dispersion of rubber particles, and develop excellent physical properties. The monomer conveniently used in this graft polymerization is a vinyl monomer because the polymerization method is emulsion or radical polymerization, and from the viewpoint of compatibility with the thermoplastic resin to be blended, adhesiveness, etc. Generally, the optimal one is selected from among the following.

This situation does not change in the present invention. Therefore, vinyl monomers that can be graft polymerized to rubber that can be used in the present invention include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, which have been used in the past, and vinyl monomers such as styrene and alpha-methylstyrene. Aromatic monomers, methacrylates such as methyl methacrylate and phenyl methacrylate, methyl chloroacrylate, 2-
These include halogenated vinyl monomers such as chloroethyl methacrylate and other radically polymerizable monomers.

In the present invention, a thermoplastic resin and an organic drug are mixed with a latex of a graft rubber polymer obtained by emulsion graft polymerization.

This operation is unique to the present invention, and usable thermoplastic resins include all those soluble in the organic chemicals described below. These include acrylonitrile-styrene copolymer, acrylonitrile-alphamethylstyrene copolymer, acrylonitrile-alphamethylstyrene-N-7-maleimide copolymer, polystyrene, polymethyl methacrylate, polyvinyl chloride, polycarbonate, and polyethylene terephthalate. This is a typical example.

The organic drug that can be used in the present invention has a solubility in water at 25° C. of 5% by weight or more and 50% by weight or less. Tsumashi, 5 or more S in 100 grams of saturated aqueous solution at 25℃
An organic agent containing an amount of at or less than 100% by weight, and which is capable of dissolving the thermoplastic resin, and is 12 to 6 times the weight of the entire polymer, preferably 12
It is used in a range of up to double meals. Examples of single agents that meet these conditions include methyl ethyl ketone, methyl acetate, ethyl acetate, diethyl cellosolve, ethyl cellosolve acetate, furfural, trioxane, methyl formate, ethyl formate, propylene oxide, 2-pentanol, and 2-butanol. , inbutanol, n-butanol, acrylonitrile, etc.;
The above-mentioned mixed drug and certain organic drugs whose solubility in water at 25°C is 5% by weight or more, such as acetone, methanol, ethanol, n-propertool, imbutanol, GiW1, acetic acid, propionic acid, dioxane. , tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylsulfoxide, ethyl cellosolve, phenol, etc., and an organic drug whose solubility in water at 25°C is 5% by weight or less. , ) Cyanide, xylene, benzene, chloroform, methylene chloride, dimethyl ether, isopropyl ether, tetrachloroethane, ethylbenzene, styrene, methyl methacrylate, etc. are mixed, and the organic agent is contained in the aqueous phase produced in the present invention by 5 weight or more. For example, if you mix 60 parts of water, 15 parts of isopropyl ether, and 25 parts of ethanol by weight,
The mixture is separated into an aqueous phase consisting of 86% by weight of water, 11% by weight of Improvil ether, and 3% by weight of ethanol, and an organic phase containing some water. In this case, in the present invention, the solubility of 60 parts of a mixed drug composed of 15 parts of isopropyl ether and 25 parts of hyethanol in water is 14% by weight.

In the present invention, it is necessary to use such an organic agent in an amount of 0.2 times or more and 6 times or less based on the weight of the total polymer, and if it is used less than 0.2 times, The effect referred to in the present invention cannot be achieved, and on the contrary, if the drug is used more than six times as often, a large amount of thermal energy is required to recover the drug, which results in the loss of industrial advantages.

In the present invention, when the latex of the graft polymer as described above, a thermoplastic resin, and an organic drug are mixed, the mixture is soluble in the graft polymer, the thermoplastic resin, a single drug, and a trace to a small amount of the organic drug. It is separated into an organic phase consisting of polymerization aids and the like, and an aqueous phase consisting of water, organic drugs, most emulsion polymerization aids, etc. From this two-phase compound, the aqueous phase and the organic phase are first separated by conventional means such as total decantation, centrifugal dehydration, and compressed dehydration, and then the organic phase is heated to form an organic drug containing T:rL. If it is separated by a normal devolatilization method, it is possible to uniformly disperse the graft rubber polymer in the thermoplastic resin and obtain a rubber-modified thermoplastic resin containing almost no emulsion polymerization aid. can.

The reason why the graft rubber particles can be uniformly dispersed in the thermoplastic resin according to the present invention is that the graft rubber particles are constantly dispersed without going through the conventional process of completely fixing them.
Or, it is falsely thought that the final product is reached in a soft agglomerated state. In addition, most of the emulsion polymerization aids, including emulsifier 1, migrate to the aqueous phase because an appropriate amount of the organic drug is dissolved in the aqueous phase, and the ability of the aqueous phase to dissolve the emulsion polymerization aid increases. It can be considered as a friend. Furthermore, in the present invention, there is no need to use a dryer, which conventionally caused a large amount of heat loss.
Since it can be manufactured using conventional devolatilization equipment such as a vented extruder, it also makes a significant contribution to the rubber modified thermoplastic resin industry in terms of cost.

Hereinafter, the method of the present invention and the effects brought about by it will be specifically explained using examples. The numbers in the examples are by weight.

〔Example〕

Example 1 Acrylonitrile and styrene were graft-polymerized to a polybutadiene latex having α of 36 μm and an average particle size tV according to Table 1 to obtain a graft rubber polymer latex.

Table 1 Polybutadiene latex 114.3 parts (Polybutadiene aa #) Acrylonitrile 15 I Styrene
45 l Sodium laurin α
51 Sodium hydroxide α011 Rongarit α2I Ferrous sulfate
α0021KDTA-disodium salt
(L1/F tertiary-butyl hydroperoxide cL3I lauryl mercaptan
ll5I deionized water 1251
Polymerization source degree 70℃ Polymerization time
240 minutes - 1,000, an acrylonitrile-styrene copolymer which is a thermoplastic resin was produced based on Table 2. Table 2 Acrylonitrile 25 parts Styrene 75 1 Azobisisobutyronitrile α3N lauryl mercaptan
15N Poval (degree of polymerization 900) α
071 Wednesday 2
50 g Polymerization temperature 75
C. Polymerization time: 240 minutes After completion of the polymerization, the obtained acrylonitrile-styrene copolymer suspension was centrifugally dehydrated and dried at 80.degree. C. to obtain a powder of the copolymer.

Next, 500 parts of the latex of the graft polymer, 150 parts of the powder of the copolymer, and 400 parts of methyl ethyl ketone were added.
0.3 parts of Irganox 1076 (manufactured by Ciba Geigy) (anti-aging agent) and 1 part of Armide HT (manufactured by Lion Armor) (molding aid). Separate into phases. Therefore, this organic phase was treated with a twin-screw extruder to remove the lO aqueous phase, and the polymer was shaped into pellets using a vented extruder while devolatilizing the methyl ethyl ketone contained in the organic phase. did. The surface of the obtained NT pellets is smooth and is called bubbly.
The presence of non-uniform parts and holes were not observed. This is 230
Various test pieces were made by injection molding at .degree. C., and various physical properties g1 were measured.The results shown in Table 3 were obtained. These results show that the rubber-modified thermoplastic resin produced in this example is superior.

Table 3 This test method is the same in Example 2 and Reference Examples.

Example 2 Using the same chemicals as in Example 1, a latex of glazed rubber polymer was produced according to the formulation shown in Table 4.

Table 4 Polybutadiene latex 22 parts 6 parts (Polybutadiene 80〃) Acrylonitrile
5 parts styrene
15 1 Sodium laurate α
4 〃Sodium dispersion (LO1#
Rongalit α15 Ferrous sulfate α0011KDTA-2 sodium salt α05 N tertiary
Butyl peroxide α11 lauryl mercaptan α1 Deionized water
50 〃Polymerization temperature 7
0°C Polymerization time: 280 minutes 50 parts of this graft rubber latex, 85 parts of the acrylonitrile-styrene copolymer used in Example 1, and 80 parts of a mixed agent consisting of 80% by weight of toluene and 20% by weight of incubanol were mixed. The mixed liquid was separated into two phases as in Example 1, so Irganox 1076 α
After adding 1 part and 5 parts of Aramide HT α, it was treated in the same manner as in Example 1 and shaped into a pellet. The surface of the obtained pellet was smooth and no lumps were observed.
There wasn't. The pellets were injection molded at t-230 DEG C. to make various test pieces, and various physical properties were measured in the same manner as in Example 1, and the results shown in Table 5 were obtained. Kon
These results show that the rubber-modified thermoplastic resin produced in this example is superior.

Table 5 Example 3 (Methyl methacrylate and methyl acrylate were graft-polymerized to 8BR rubber latex having an average particle diameter tV of 114 μm according to Table 6 to obtain a kraft rubber polymer latex.

Table 6 SDR rubber latex 100 parts CBBR
Rubber 50 l) Methyl methacrylate 45 Nac]Nor powder methyl
5N potassium rosinate 11
Rongarit α2 Ferrous sulfate [LOO3#KDTA-2 sodium tX CLII cumene hydroperoxide α4 Octyl mercaptan α2 Deionized water 15
Polymethyl methacrylate, a thermoplastic resin, was prepared according to the recipe in Table 7.

Table 7 Methyl methacrylate 100 parts Azobisisobutyronitrile cL51 Lauryl mercaptan α5I Poval (1 degree 900)
l1071 water
200 #Polymerization temperature
80℃ 1 hour
After 180 minutes of polymerization, the obtained suspension of polymethyl methacrylate was centrifugally dehydrated and dried at 80°C to obtain a powder of the polymer.

Next, when 90 parts of the latex of the graft polymer, 70 parts of polymethyl methacrylate powder, and 100 parts of gold were mixed, the mixed solution separated into an aqueous phase and a rice cake-like organic phase. Therefore, the following apparatus used in Example 1 was used to perform aqueous phase separation, devolatilization of ethyl acetate, and pelletization. The surface of the pellets obtained at this time was smooth and no lumps were observed. Furthermore, this pellet t-220℃
Various test pieces were made by injection molding, and various physical property values were measured, and the results shown in Table 8 were obtained. These results show that the rubber-modified thermoplastic resin produced in this example is excellent.

Table 8 Reference Example 1 The latex of the graft polymer produced in Example 1 was coagulated with sulfuric acid by a conventional method, and the obtained wet polymer powder was washed, dehydrated,
Dry the graft polymer to obtain a dry powder. This graft polymer, the acrylonitrile-styrene copolymer produced in Example 1, and the following additives used in Example 1 were mixed in the same proportions as in Example 1, and pelletized using a screw extruder. Processed nine. The composition of the pellets obtained at this time was the same as that of the pellets obtained in Example 1, but the surface morphology had many lumps and was of no commercial value.

Furthermore, the obtained pellets were injection molded and the same tests as in Example 1 were conducted, and the results shown in Table 9 were obtained.

Table 9 [Effects of the Invention] The method of the present invention facilitates the dispersion of graft rubber particles and makes it possible to produce a resin with excellent white discoloration and transparency. Ninth, it is possible to convert a grafted rubber polymer into a rubber-modified thermoplastic casting compound without drying it using a large amount of hot air. This means that a resin with excellent surface appearance and various physical properties and a high T5 field value can be produced at low cost.

Claims (1)

[Claims] A latex of a graft rubber polymer obtained by graft polymerizing a vinyl monomer to rubber latex, a thermoplastic resin, and a thermoplastic resin in an amount of 0.2 times or more and 6 times or less, based on the weight of the total polymer, are dissolved. and has a solubility in water of 5% by weight or more and 50% by weight at 25°C.
A method for producing a rubber-modified thermoplastic resin, which comprises separating an aqueous phase from a two-phase mixture formed by mixing the following organic agents, and separating the organic agent and water from the remaining organic phase by thermal means. .