JPH0449842B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [] OBJECTS OF THE INVENTION The present invention relates to a novel method for producing thermoplastic polymers in which the production process is streamlined and productivity is significantly improved. More specifically, the present invention relates to a novel manufacturing method of polymerizing crumbs made of latex and monomers under crumb conditions.

1. Field of Industrial Use In thermoplastic resins, various types of polymer blends (alloys) with a good balance of physical properties have been commercialized by mixing two or more resins each having advantages and disadvantages.

Many of these resins are graft polymers, in which one resin is grafted with a part of the other resin component, in order to improve the compatibility between the resin components to be mixed.
A so-called interpenetrating polymer, in which one resin component and a part of the other resin component are intertwined with each other, is used.

An example is ABS resin. ABS resin is
By graft polymerizing acrylonitrile and styrene to a diene rubber component, the compatibility between the rubber and the acrylonitrile-styrene copolymer is improved, and the impact resistance of the acrylonitrile-styrene copolymer is significantly improved. The present technology is a particularly effective invention in these fields.

2. Prior Art Conventionally, methods for producing graft polymers or interpenetrating polymers include emulsion polymerization, solution polymerization, bulk polymerization, suspension polymerization, and bulk-suspension polymerization that combines these polymerization methods. Legal, emulsion-suspension polymerization method,
Emulsion-bulk polymerization methods are known.

3 Problems to be Solved by the Invention Among conventional techniques, solution polymerization methods using organic solvents have problems such as recovery of the solvent and removal of polymerization heat. Emulsion polymerization and suspension polymerization, in which polymerization is carried out in an aqueous phase system containing an emulsifier or a suspending agent, have problems in that they require a large amount of cost to recover the polymer and are not capable of continuous polymerization. Moreover, the bulk polymerization method has problems such as the viscosity of the reaction system becoming high, making it difficult to obtain a polymer with a high content of backbone polymer, and also making it difficult to remove the heat of polymerization.

Furthermore, when performing continuous polymerization using these methods, the grafting rate and degree of interpenetration vary greatly depending on the residence time of the polymer serving as the backbone polymer in the reaction system. In order to obtain a good balance of physical properties, an optimal grafting ratio and degree of interpenetration are required. Therefore, continuous polymerization is performed by narrowing the residence time distribution of the polymer that will become the backbone polymer in the reaction system like a piston flow. There is a need to.

Conventional continuous polymerization methods require multi-stage reaction vessels and have drawbacks such as extremely low productivity of continuous polymerization and significant scale deposition on the reaction vessels due to long-term operation.

[] Structure of the Invention As a result of intensive research to solve various problems in conventional polymerization methods and continuous polymerization, the present inventors have developed a method of coagulating a mixture of a polymer latex and a monomer to form crumbs. The inventors have discovered a method for producing thermoplastic polymers in which the production process is significantly streamlined and productivity is significantly improved compared to conventional polymerization methods by polymerizing the thermoplastic polymers in a crumb state. Further, according to the method of the present invention, continuous polymerization is possible with a narrow residence time distribution due to piston flow and no scale deposition.

Further, the present invention will be explained in detail below.

The polymer latex used in the present invention may be a polymer in a latex state, and there are no restrictions on the composition of the polymer or the method for producing it.

For example, the polymers include polybutadiene,
Styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene copolymer, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polybutyl acrylate, butyl acrylate -Acrylonitrile copolymer and the like. A polymer latex obtained by emulsion polymerization may be used, or a latex obtained from a polymer obtained by other polymerization methods may be used.

Although there is no particular restriction on the solid content concentration of the polymer latex, a higher solid content concentration is preferable from the viewpoint of productivity since it is possible to lower the moisture content of the crumb.

If a polymer latex with a very low solid content concentration is used, water may separate from the crumb during crumb formation, but in that case, such water may be removed before use.

Further, the monomer is not particularly limited as long as it is a radically polymerizable monomer. Examples of radical polymer monomers include aromatic vinyls such as styrene, unsaturated nitriles such as acrylonitrile, unsaturated carboxylic acid alkyl esters such as methyl methacrylate, vinyl halides such as vinyl chloride, maleimide, methylmaleimide, and phenylmaleimide. Examples include maleimide monomers such as, and one kind or two or more kinds thereof can be used. Moreover, at this time, if necessary, the same monomer as the backbone polymer can be used.

Furthermore, there is no particular restriction on the mixing ratio of the polymer latex (solid content) with the radically polymerizable monomer.
It can be selected as appropriate based on the properties of the final polymer. The mixing ratio depends on the swelling ability of the polymer latex with respect to the radically polymerizable monomer, but it may be within a range in which the monomer is not separated from the crumb by mixing.

Generally, it can be used in a range of polymer latex (solid content)/monomer = 10/90 to 95/5 (weight ratio). At this time, a portion of the solvent may be used to enhance the swelling ability.

Examples of the method for coagulating the mixture of the polymer latex and the radically polymerizable monomer include adding a coagulant or freezing and coagulating the mixture.

The coagulant may be any compound that has the ability to coagulate latex, such as aluminum sulfate, magnesium sulfate, calcium chloride, hydrochloric acid,
Examples include acetic acid and sulfuric acid. It is preferable to use solid coagulants in the form of an aqueous solution. However, since it is desirable to keep the water content in the crumb as low as possible, it is preferable to use an aqueous solution with a high coagulant concentration.

There is no particular restriction on the method of initiating polymerization in crumb state. Although thermal polymerization can be carried out without using a polymerization initiator, it is preferable to use a radical polymerization initiator because the polymerization temperature can be lowered. The polymerization initiator used is appropriately selected depending on the polymerization temperature, the type or amount of the monomer used, the ease with which the graft reaction can be carried out, and the like.

As a polymerization initiator, t-butyl peroxypivalate, lauroyl peroxide, benzoyl peroxide, α・α′-azobisisobutyronitrile, t-butyl peroxylaurate, t
-butyl peroxybenzoate, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, etc., and one or more types can be used. It is also possible to conduct polymerization by dividing the reaction temperature into two or more stages by using two or more types of initiators having different decomposition temperatures.

Further, there is no restriction on the timing of addition of the polymerization initiator, and it may be added to the monomer in advance, or may be added at the time of coagulation.

A mixture containing a polymer latex, a radically polymerizable monomer, and optionally a coagulant and a polymerization initiator can be coagulated and crumb-formed using a known mixer, kneader, or the like.

The production method of the present invention can be called solid polymerization, and polymerization is carried out in a crumb state without using a liquid such as a solvent or water as a medium.

As the equipment for polymerizing under crumb conditions, any equipment may be used as long as it is equipped with a device that can heat the crumb.

Batch polymerization is also possible, but from the viewpoint of handling the polymer after polymerization and productivity, it is necessary to have equipment that can heat and cool the crumb, and a screw that can control the residence time of the reactants. Continuous production in a cylindrical reactor is preferred.

In addition, during polymerization, known polymerization degree regulators,
Antioxidants, ultraviolet absorbers, colorants, lubricants, plasticizers, fillers, etc. can be added.

Moreover, the polymer obtained according to the present invention can also be mixed with other resins.

The present invention will be explained in more detail below using Examples.

Example 1 (parts by weight) Γ Polybutadiene latex (solid content concentration 50
%, gel 85% average particle size 0.3μ) 50 Γ Styrene 35 Γ Acrylonitrile 15 Γ t-Butyl peroxypivalate (initiator)
0.2 Γ n-octadecyl-3-(4'-hydroxy-
3′・5′77-tert-butylphenyl) propionate (antioxidant) 0.2 Γ t-dodecyl mercaptan (polymerization degree regulator)
0.2 Place the above substances in a beaker equipped with a stirrer,
After stirring for 5 minutes, a salting agent solution consisting of 0.5 parts by weight of aluminum sulfate and 5 parts by weight of water was added while stirring, and the stirring was stopped when the mixture became crumb-like. The beaker containing the crumbs was immersed in warm water at 65°C and left for 60 minutes to complete polymerization.

The obtained polymer had a water content of 33%, a monomer conversion rate (*1) of 98%, and a grafting rate (*2) of 48%. Table 1 shows the physical properties of the composition comprising the obtained polymer and other styrene resins.

Example 2 Crumb prepared in the same manner as in Example 1 was introduced into a reactor equipped with a jacket and screw as shown in Figure 1, and the mixture was heated so that the average residence time was 30 minutes and the jacket temperature was 65°C. control to 40
Polymerization was carried out continuously for hours.

The water content, monomer conversion rate, and grafting rate of the polymer continuously extruded from the reactor outlet were as follows.

After start of operation Moisture content Conversion rate Grafting rate 3rd hour 33% 98% 51% 10th hour 33% 98% 50% 40th hour 33% 98% 51% There was no difference in the physical properties of the polymers, and all showed excellent physical properties. Table 1 shows the physical properties of the composition comprising the obtained polymer and other styrene resins.

Example 3 t-dodecyl mercaptan in Example-1
Polymerization was carried out in the same manner as in Example-1 except that 0.2 part by weight was changed to 0.4 part by weight.

The obtained polymer had a water content of 33%, a monomer conversion rate of 98%, and a grafting rate of 35%. Table 1 shows the physical properties of the composition comprising the obtained polymer and other styrene resins.

Example 4 (parts by weight) Γ Styrene-butadiene copolymer latex (styrene/butadiene = 20/80, solid content concentration 35
%, average particle size 0.15μ, gel 90%) 70 Γ Styrene 15 Γ Methyl methacrylate 15 Γ Lauryl peroxide (initiator) 0.2 Γ n-octadetel-3-(4'-hydroxy-
0.1 3′,5′-di-tert-butylphenyl) propionate (antioxidant) 0.1 Place the above substances in a beaker equipped with a stirrer,
After stirring for 5 minutes, a salting agent solution consisting of 1.0 parts by weight of magnesium sulfate and 5 parts by weight of water was added while stirring, and the stirring was stopped when the mixture became crumb-like. The prepared crumb was introduced into a reactor as shown in Figure 1, and the average residence time was 30 minutes and the jacket temperature was 75.
Polymerization was carried out continuously for 40 hours while controlling the temperature to be at ℃.

The water content, monomer conversion rate, and grafting rate of the polymer continuously extruded from the reactor outlet were as follows.

After start of operation Moisture content Conversion rate Grafting rate 3rd hour 57% 99% 34% 10th hour 57% 99% 34% 40th hour 57% 99% 33% Consisting of the obtained polymer and other styrenic resins Table 1 shows the physical properties of the composition.

[] Effects of the Invention As mentioned above, the present invention eliminates the need for the solvent recovery step and the salt folding step, which were problems in conventional polymerization methods, and also makes it possible to easily produce polymers with a high rubber content. can.

Furthermore, continuous polymerization is also easy.

[Brief explanation of drawings]

Figure 1 shows an example of a reactor used for continuous polymerization of the thermoplastic polymer of the present invention. 1 is a crumb inlet, 2 is a crumb, 3 is a jacket, 4 is a screw, 5 is a jacket heat medium inlet, 6 is a jacket heat medium outlet, and 7 is a polymer outlet.

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Claims (1)

[Scope of Claims] 1. A method for producing a thermoplastic polymer, which comprises coagulating a mixture of a polymer latex and a radically polymerizable monomer to form a crumb, and then polymerizing the mixture in a crumb state. 2. The method for producing a thermoplastic polymer according to claim 1, wherein the polymer latex and the radically polymerizable monomer are coagulated using a coagulant. 3. The method for producing a thermoplastic polymer according to claim 1 or 2, which is polymerized using a radical polymerization initiator. 4. The thermoplastic according to claim 1, 2 or 3, wherein the weight ratio of the solid content of the polymer latex to the radically polymerizable monomer is in the range of 10:90 to 95:5. Method for producing polymers. 5. The method for producing a thermoplastic polymer according to claim 1, 2, 3, or 4, wherein the polymer latex is a diene polymer latex. 6. Claims 1 and 2, in which the radically polymerizable monomer is one or more monomers selected from the group consisting of aromatic vinyl, unsaturated nitriles, and unsaturated carboxylic acid alkyl esters. Section, 3rd
5. A method for producing a thermoplastic polymer according to item 4, item 5, or item 5.