JPH10158332A - Production of acryl syrup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an acryl syrup excellent in transparency and weather resistance and suitable for molding, etc., by mixing monomers, etc., consisting essentially of a methacrylate in a biaxial kneader under specific conditions. SOLUTION: (A) A monomer consisting essentially of a methacrylate is mixed with (B) a methacrylate-based polymer in a biaxial kneader such as a continuous biaxial kneader at >=50 deg.C to provide the objective acryl syrup. Furthermore, polymer content of the acryl syrup is preferably in the range of 20-80wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing acrylic syrup. More particularly, the present invention relates to a production method capable of efficiently and inexpensively producing acrylic syrup suitable for molding.

[0002]

2. Description of the Related Art Conventionally, acrylic syrups mainly composed of methyl methacrylate have been used as resin raw materials for lighting fixtures, signboards, automotive parts, decorative articles, miscellaneous goods, various building materials, etc. due to their excellent transparency and weather resistance. Used as a raw material for adhesives. As a method of producing an acrylic syrup, conventionally, for example, a method of pre-polymerizing methacrylic esters or adding a methacrylic ester polymer to methacrylic esters and mixing and dissolving the polymer by stirring. Has been taken.

[0003]

However, in the above-mentioned conventional method for producing acrylic syrup, there is a problem that a pre-polymerization step is required or a long time is required for dissolving the methacrylate polymer. Yes, especially when the polymer content in the acrylic syrup increases, the viscosity increases, making not only difficult handling, but also difficult to manufacture because syrup production or transport requires a great deal of power. Met. Accordingly, an object of the present invention is to provide a method for producing an acrylic syrup, and in particular, to provide a method for efficiently and inexpensively producing an acrylic syrup suitable for molding.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, a methyl methacrylate monomer and a methyl methacrylate polymer were mixed in a twin-screw kneader. Acrylic syrup can be produced by mixing the syrups, and especially high-viscosity acrylic syrups in which the polymer content in the acrylic syrup exceeds 40% can be efficiently and inexpensively produced. And completed the present invention.

That is, the gist of the present invention is as follows.
In producing an acrylic syrup, a monomer (A) mainly composed of methacrylic acid ester and a methacrylic acid ester-based polymer (B) are mixed and kneaded in a biaxial kneader under a temperature condition of 50 ° C. or more. This is a method for producing an acrylic syrup.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The monomer (A) mainly composed of methacrylic ester used in the present invention refers to methacrylic ester alone or another unsaturated monomer mainly composed of methacrylic ester and copolymerizable therewith. A monomer mixture of
Methacrylic acid ester is 60% by weight or more, preferably 8% by weight.
It is desirably 0% by weight or more.

[0008] Methacrylic acid esters include those having 5 carbon atoms.
Methacrylates of about 18 to about 18 are preferably used, and specifically, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, and the like. No. Of these, methyl methacrylate is particularly preferably used.

The other unsaturated monomer copolymerizable with the methacrylic acid ester is not particularly limited. For example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, acrylic acid Acrylic esters such as 2-ethylhexyl, cyclohexyl acrylate, and lauryl acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; unsaturated monomers such as acrylonitrile, methacrylonitrile, acrylamide, vinyl acetate, and vinyl chloride A polyfunctional unsaturated monomer such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and trimethylolpropane trimethacrylate. These monomers are used alone or in combination of two or more.

The methacrylic acid ester polymer (B) used in the present invention is not particularly limited as long as it is a methacrylic acid ester polymer soluble in the above-mentioned monomer mainly composed of methacrylic acid ester. You can,
For example, those obtained by polymerizing a monomer mainly composed of the methacrylic acid ester, or those obtained by copolymerizing one or more of these monomers with another polymerizable monomer are preferable. Can be. As the methacrylate polymer, for example, a polymer obtained by polymerizing the above-mentioned monomer mainly composed of methacrylate by emulsion polymerization, suspension polymerization, bulk polymerization, or the like is used. The methacrylate polymer obtained by such a polymerization method is preferably in the form of particles from the viewpoint of miscibility with the monomer, and the particle diameter is supplied to a biaxial kneader described later. The size is not particularly limited as long as it is possible, but usually 5
mm or less, more preferably about 0.1 to 2 mm.
As the particle shape of the methacrylic acid ester-based polymer, a pellet shape, a pulverized powder shape, a bead shape, and the like are usually used, and a bead shape is particularly preferable from the viewpoint of the time required for dissolution, ease of handling, and the like. The weight average molecular weight of the methacrylate polymer is not particularly limited as long as it can be dissolved in the monomer, but is usually in the range of 50,000 to 600,000, preferably in the range of 50,000 to 300,000, more preferably 1 to 300,000.
The range is from 0 to 200,000.

In the method of the present invention, the mixing ratio of the monomer (A) mainly composed of methacrylic acid ester and the methacrylic acid ester-based polymer (B) is first determined when the acrylic syrup having a low viscosity is obtained. After adjusting the high-viscosity acrylic syrup by the method described above, the method of the present invention can be further continued to obtain a desired acrylic polymer having a low polymer content, so that the polymer content of the acrylic syrup is not particularly limited. Is preferably 20 to 80% by weight, more preferably 40 to 60% by weight, so that an acrylic syrup having a desired viscosity can be produced in one step.

In the method of the present invention, when producing an acrylic syrup, the above-mentioned monomer (A) mainly composed of methacrylic acid ester and methacrylic ester polymer (B) are mixed in a twin-screw kneader. 50 ° C. or higher, preferably 6
It is necessary to mix under a temperature condition of 0 to 100 ° C, more preferably 70 to 90 ° C. When the mixing temperature in the twin-screw kneader is less than 50 ° C., it takes a long time to mix and dissolve the methacrylic acid ester-based polymer. Residence time 1
The dissolution in 0 minutes or less, more preferably in about 1 to 5 minutes, tends to be incomplete, which is not preferable.

The twin-screw kneader used in the method of the present invention is not particularly limited as long as it is a twin-screw kneader, and a batch-type twin-screw kneader, a continuous twin-screw kneader, or the like is usually used. The use of a single-screw kneader is inferior to a twin-screw kneader in terms of productivity, dispersibility, and the like, and is not preferable because the effects of the present invention are not exhibited.

As a batch type twin-screw kneader, for example, two mixing blades such as a Z type, an H type, a finish tail type, and a dispersion type placed in parallel in a trough rotate in opposite directions to each other, A double-armed kneader for shearing, compressing, stretching and kneading the mixture; kneading the double-armed kneader with a mechanical pressure cover, and pressing the pressure cover by air pressure, hydraulic pressure, etc. A pressure kneader in which a strong shearing force is generated between the kneaded material and the trough wall surface or between the kneaded materials by compressing to strengthen the kneading; the raw material is put into a closed mixing chamber and incorporated in the mixing chamber. An internal mixer or the like in which two rotors rotate in opposite directions to each other and apply a strong shearing force between the chamber wall surface and the rotor or between the rotors to knead them.

Further, as a continuous twin-screw kneader, raw materials are continuously fed into a kneading section by a feed screw section arranged in a raw material supply section, and are fed to a kneading section in which a rotor or a kneading disk is arranged. And a kneaded material is continuously discharged, and a twin screw kneader, a continuous kneader, or the like is preferably employed. These continuous twin-screw kneaders are preferably those in which the degree of kneading can be freely adjusted by changing the combination of screws, rotors, kneading disks, etc., and also in terms of kneading properties and the like. It is preferable that the L / D of the portion corresponding to the kneading section is about 4 to 50. In the continuous twin-screw kneader, the two-shaft meshing may be any of a non-meshing type or a meshing type, and the biaxial rotation direction may be either a co-rotating type or a different-direction rotating type. In the method of the present invention, a continuous twin-screw kneader is preferably used among the twin-screw kneaders from the viewpoint of productivity and the like.

In the method of the present invention, the monomer (A) mainly composed of methacrylate and the methacrylate polymer (B) are supplied to the twin-screw kneader,
Mixing and kneading are performed at a temperature of not less than ℃. For this reason, the twin-screw kneader adjusts the amount of the raw material to be supplied, so that the heat generated by shearing or the like can be reduced.
Although a temperature of 0 ° C. or more can be maintained, a kneaded material is provided with a temperature control portion such as a jacket portion, using an electric heating heater, steam, hot or cooling water, a temperature control oil, or the like. Preferably, it can be adjusted to a temperature.

In the method of the present invention, in addition to the monomer (A) mainly composed of methacrylic acid ester and the methacrylic ester polymer (B), an inorganic filler and an organic filler may be added depending on the use. Thereby, it is possible to easily develop a shearing force and improve the kneading effect. Examples of the inorganic filler include inorganic fine powders such as silica, talc, calcium carbonate, and aluminum hydroxide, and examples of the organic filler include silicon fine powder, partially crushed polymer, and crosslinked resin powder. Can be As the crushed partially crosslinked polymer, a crushed acrylic partially crosslinked gel polymer can be preferably employed. A crushed product of an acrylic partially crosslinked gel polymer is disclosed in JP-A-62-1705.
As described in Japanese Patent Application Laid-Open Publication No. H07-27, (A) alkyl methacrylate monomer, α, β-
A resin material selected from the group consisting of an ethylenically unsaturated monomer mixture and a syrup containing the polymer, and (B) a mixture comprising 2 to 250 parts by weight of a crosslinking agent per 100 parts by weight of the resin material Partially crosslinked gel polymer in which the polymer content is increased by 4 to 75% by weight from the total polymer content in the mixture so that the total polymer content does not exceed 90% by weight by polymerization. Having a mean particle size of 5 mm or less.

In the method of the present invention, a curing agent can be added without interfering with the object of the present invention. Usually, a method of obtaining an acrylic syrup under the above-mentioned conditions and then cooling the mixture immediately after mixing the curing agent. And a method of mixing a curing agent during the cooling process of the syrup, or a method of mixing the curing agent after cooling. As the curing agent, those having a critical temperature of 70 ° C. or higher can be preferably used. Further, in the method of the present invention, as long as the object of the present invention is not hindered,
An ultraviolet absorber, a light stabilizer, an antioxidant, a coloring agent, a release agent, a polymerization regulator, a defoaming agent, and the like can be mixed during or after kneading.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. In addition, an Example shows embodiment of this invention, and is not limited to these examples. The pressure spreadability was tested by the following method. (Measurement of spreadability under pressure) 30 semi-solid acrylic syrups
g in a press machine heated to a hot platen temperature of 50 ° C., and a total of 3 tons in the state of upper hot platen / 50 μm thick nylon film / semi-solid acrylic syrup / 50 μm thick nylon film / lower hot platen Pressurize with a load for 60 seconds to measure the spread area of the semi-solid acrylic syrup with an area meter [Hayashi Denko Co., Ltd.
Manufactured by AAM-8 automatic area meter]. In addition, the presence or absence of undissolved polymer particles in the film obtained after the pressure spreading was visually observed.

(Example 1) A continuous twin-screw kneader with a feed rate of 19 kg / hour of methyl methacrylate from a liquid mixing tank by a metering pump [S2 type KR manufactured by Kurimoto Iron Works Co., Ltd.]
C kneader, caliber 50φ, L / D = 13, rotation speed 100
rpm, power 3.7 kW], followed by a degree of polymerization of 13
00, methacrylic resin beads having an average particle diameter of 0.3 mm (weight average molecular weight 110,000) were supplied from a powder quantitative feeder at a feed rate of 20 kg / hour. While heating these raw materials at a heating medium temperature of 85 ° C using a jacket attached to a continuous twin-screw kneader, a methacrylic resin was dissolved in methyl methacrylate, and an outlet syrup temperature of 75 ° C,
A mochi-like acrylic syrup having a polymer content of 51.3% by weight was obtained at room temperature (23 ° C.). The average residence time required for dissolving the raw materials in the continuous twin-screw kneader was 2 minutes. The pressure spreadability of the obtained acrylic syrup was 5
60 cm ² , and no residual resin beads were dissolved.

(Example 2) A mixture of 70 parts by weight of methyl methacrylate and 30 parts by weight of neopentyl glycol dimethacrylate was poured into a liquid mixing tank by a metering pump.
The feed rate of kg / hour was supplied to the same continuous twin-screw kneader as in Example 1, and then the same methacrylic resin beads as in Example 1 were supplied from the powder quantitative feeder at a feed rate of 16 kg / hour. While heating these materials at a heating medium temperature of 90 ° C. using a jacket attached to a continuous twin-screw kneader, a methacrylic resin bead was dissolved in a mixture such as methyl methacrylate, and the outlet syrup temperature was 80 ° C. An acrylic syrup having a polymer content of 28.6% by weight was obtained. While cooling this syrup in a continuous twin-screw kneader, 0.15 parts of t-butyl peroxyisobutyrate was supplied, and 25 ° C.
Thus, a 200 poise liquid acrylic syrup for casting was obtained. The average residence time required for dissolving the raw materials in the continuous twin-screw kneader was 2 minutes, and the residence time required for cooling was 2 minutes.

(Example 3) A liquid obtained by mixing 57 parts by weight of methyl methacrylate and 43 parts by weight of neopentyl glycol dimethacrylate from a liquid mixing tank was added to a liquid by a metering pump.
The feed rate of kg / hour was supplied to the same continuous twin-screw kneader as in Example 1, and the same methacrylic resin beads as in Example 1 were fed from the powder quantitative feeder at a feed rate of 36 kg / hour. While heating these raw materials at a heating medium temperature of 95 ° C. using a jacket attached to a continuous twin-screw kneader, a methacrylic resin bead was dissolved in the above mixed solution, and the outlet syrup temperature was 85 ° C. and the polymer was contained. An acrylic syrup having a ratio of 70.6% by weight was obtained. While cooling this syrup in a continuous twin-screw kneader, 3.5 parts of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane was supplied, and a rubber-like syrup was obtained at room temperature (23 ° C.). An acrylic syrup for heat-press molding was obtained. The average residence time required for dissolving the raw materials was 2 minutes, and the residence time required for cooling was 2 minutes. The pressure spreadability of the obtained acrylic syrup was 1
It was 05 cm ² , and no dissolved residue of the resin beads was observed.

(Comparative Example 1) The same operation as in Example 1 was performed except that the temperature of the heating medium was changed to 45 ° C. The obtained kneaded material is
The resin beads were not completely dissolved.

Comparative Example 2 Methyl methyl methacrylate 7
0 g and neopentyl glycol dimethacrylate 30 g
Of the same methacrylic resin beads as in Example 1
0 g was added, and the mixture was stirred and mixed at 70 ° C. in a closed vessel equipped with a stirrer. However, even after 30 minutes, the methacrylic resin beads remained as a lump.

[0025]

As described above, the present invention is a method for producing acrylic syrup at a temperature of 50 ° C. or more using a twin-screw kneader, so that acrylic syrup can be produced simply and efficiently. In particular, even a high-viscosity acrylic syrup having a polymer content of more than 40% in the syrup can be efficiently produced, so that it is suitable as a method for producing an acrylic syrup for molding.

Claims (3)

[Claims] In producing an acrylic syrup, a monomer (A) mainly composed of methacrylic acid ester and a methacrylic acid ester-based polymer (B) are mixed in a twin-screw kneader for 5 minutes.
A method for producing acrylic syrup, comprising mixing at a temperature of 0 ° C. or higher. 2. An acrylic syrup having a polymer content of 20
2. The method according to claim 1, wherein the amount is in the range of about 80% by weight. 3. The method according to claim 1, wherein the twin-screw kneader is a continuous twin-screw kneader.