JPS621705A - Methacrylic resin molding material - Google Patents

Abstract

PURPOSE:A molding material providing a molded article useful as automobile parts, having improved fluidity stability during molding, good heat resistance, solvent resistance, impact resistance and surface hardness, obtained by crosslinking partially a mixture containing a specific resin raw material and a crosslinking agent. CONSTITUTION:A mixture consisting of (A) a resin raw material selected from syrup containing an alkyl methacrylate monomer (e.g., methyl methacrylate, etc.), an alpha,beta-ethylenic unsaturated monomer mixture comprising an alkyl methacrylate as a main component and its polymer and (B) 2-250pts.wt. based on 100pts.wt. resin raw material of a crosslinking agent (e.g., 1,3-propylene glycol dimethacrylate, etc.) is partially polymerized to give a molding material having <=90wt% total polymer content wherein a partially crosslinked gelatinous polymer having a polymer ratio 4-75wt% higher than that of the mixture is ground into <=5mm average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a methacrylic resin molding material. More specifically, the present invention relates to a methacrylic resin molding material that is used to obtain crosslinked molded products and has particularly excellent flow stability during molding.

(Prior art) In general, methacrylic resins whose main component is methyl methacrylate are used in various fields such as lighting covers, automobile parts, signboards, decorative items, and miscellaneous goods due to their excellent weather resistance and outstanding transparency. However, since the methacrylic resin is a linear polymer, it often suffers from insufficient heat resistance, solvent resistance, impact resistance, and surface hardness. For example, the limit for heat resistance is about 100'C,
At present, it is not possible to fully meet the demands of various fields that require heat resistance. For example, it cannot be used as a cover for a headlamp as an automobile part, and in the case of a tail lamp, the lamp itself is larger than conventional products, or the amount of heat generated due to increased illuminance increases and costs are reduced. Improved heat resistance is required in order to achieve thinner walls, and applications are also expanding to parts whose temperature rises significantly under direct sunlight, such as meter covers for automobiles and two-wheeled vehicles (motorcycles), and covers for water heaters that use solar thermal energy. Therefore, the development of a methacrylic resin that can sufficiently withstand temperatures above the boiling point of water is expected.

Conventionally, in order to improve the heat resistance of methacrylic resins, methods have been developed in which methyl methacrylate and α-methylstyrene are copolymerized (U.S. Pat. No. 3,135,723), and methyl methacrylate, α-methylstyrene, and maleic anhydride are copolymerized. Polymerization method (Japanese Patent Publication No. 45-31,953,
A number of methods have been proposed, including a method of copolymerizing methyl methacrylate, α-methylstyrene and maleimide (Japanese Patent Publication No. 48-95,490M).

However, although these methods improve heat resistance, the polymerization rate is extremely slow, the polymerization rate does not increase and a high polymerization rate cannot be obtained, and the polymer cannot be obtained efficiently in a relatively short time. However, it has both advantages and disadvantages, such as the strong discoloration of the polymer and reduced transparency, weather resistance, surface hardness, mechanical strength, etc., making industrial production extremely difficult, and it has not yet been put into practical use. .

On the other hand, it is generally possible to improve heat resistance, solvent resistance, etc. by introducing crosslinked channels into linear polymers, but since crosslinked polymers already have a three-dimensional structure, It is not possible to mold polymers by injection molding, extrusion or transfer molding. Furthermore, when molding is performed by the cast polymerization method, voids, foaming, etc. are likely to occur, so that not only complex shapes cannot be molded, but the productivity is also low.

Kodama et al. wrote in Kobunshi Kagaku Vol. 27, No. 291, p. 65 et al., ``One way to improve the formability of cross-linked polymers is to use ones with long distances between functional groups, and to increase the presence of monomers to a considerable extent. For example, it is also possible to perform molding after the first stage polymerization has been completed (polymerization rate of 90% or more), and then perform the second stage polymerization to complete the polymerization. , there is no description of a specific example, and furthermore, according to the inventor's follow-up test based on the description by Kodama et al., when the sample was heated and compression molded in a mold after completing the first stage polymerization, the sample solidified but did not flow. It becomes powdery,
It showed no moldability at all. Therefore, the forming described by Kodama et al. means a very simple bending process, and it has been impossible to apply this method to forming involving flow, which is the object of the present invention.

As shown in Japanese Patent Application No. 59-057,258, the present inventors previously proposed (
A> A resin raw material selected from the group consisting of an alkyl methacrylate monomer, a mixture of α, β-ethylenically unsaturated monomers containing alkyl methacrylate as a main component, and syrup containing a polymer thereof, and (B) the resin. By partially polymerizing a mixture consisting of 2 to 250 parts by weight of a crosslinking agent per 100 parts by weight of the raw material, the content of the polymer in the mixture is reduced so that the total polymer content does not exceed 80% by weight. We have discovered a methacrylic resin molding material made of a partially crosslinked gel polymer whose content is increased by 4 to 65 M% and a method for producing the same. Since the methacrylic resin molding material flows by applying shear stress at room temperature or elevated temperature, it can be molded using compression molding, extrusion, transfer molding, or other molding methods to prevent molding from casting polymerization. Products with complex shapes can be obtained, and the molded products exhibit excellent properties such as heat resistance, solvent resistance, and impact resistance, and are superior to methacrylic resins in terms of transparency and weather resistance. It was possible to combine the excellent properties originally possessed by this product without any deterioration. However, when the present inventors conducted a rough research on the methacrylic resin molding material, it was found that when pressure was applied to the methacrylic resin molding material and it became fluid, the flow temporarily stopped, albeit slightly. As a result, when the stretching ratio of the material is increased, the appearance of molded products such as torn and flowed patterns is observed, and materials with a high polymerization rate have poor mold transferability. It has been found. Furthermore, the shear stress required to achieve a fluid state still needs to be quite high, and there is still room for improvement.

(Problems to be Solved by the Invention) Therefore, the present invention aims to improve the above-mentioned problems of methacrylic resin molding materials.

That is, an object of the present invention is to provide an improved methacrylic resin molding material. Another object of the present invention is to provide a methacrylic resin molding material that can be used to obtain a crosslinked molded product and has particularly excellent flow stability during molding.

(Means for solving the problems) The above-mentioned examples include (A) an alkyl methacrylate monomer;
A resin raw material selected from the group consisting of an α,β-ethylenically unsaturated monomer mixture containing alkyl methacrylate as a main component and syrup containing a polymer thereof, and (B) 2 to 250 parts by weight per 100 parts by weight of the resin raw material. The mixture consisting of the crosslinking agent in the heavy weight part is partially polymerized to have a total polymer content of 9.
A partially crosslinked gel-like polymer with a polymer content increased by 4 to 75% by weight over the polymer content of the mixture amount within a range not exceeding 0% by weight is crushed to an average particle size of 5 mm or less. This is achieved using a methacrylic resin molding material.

The monomers used as the resin raw material (A>) in the present invention include alkyl methacrylate alone or alkyl methacrylate and a mixture of α,β-ethylenically inert saturated monomers that can be copolymerized with the alkyl methacrylate. In the case of a monomer mixture, the alkyl methacrylate is 50
It is desirable that the content be less than mol %, and preferably 60 mol % or more. Alkyl methacrylates include methyl methacrylate, ethyl methacrylate, n
-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, 5eC-butyl methacrylate, tert-butyl methacrylate, etc., and methyl methacrylate is particularly preferred.

Copolymerizable monomers include alkyl methacrylates other than the alkyl methacrylate (e.g. methyl methacrylate) used as the main component (e.g. the above-mentioned alkyl methacrylates, 2-ethylhexyl methacrylate,
lauryl methacrylate, cyclohexyl methacrylate, etc.), methyl acrylate, ethyl acrylate, n
-propyl acrylate, isopropyl acrylate,
Alkyl acrylates such as n-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
Hydroxyalkyl acrylates such as 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-talolopropyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2
-Hydroxyalkyl methacrylates such as hydroxy-3-chloropropyl methacrylate, acrylates 1 such as acrylic acid, methacrylic acid, neodymium acrylate, lead acrylate, boron acrylate, neodymium methacrylate, lead methacrylate, boron methacrylate, etc. methacrylate, vinyl chloride, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, α-methylstyrene, vinyltoluene, acid anhydride, etc.

In addition, the syrup containing the polymer of the alkyl methacrylate or the monomer mixture containing the alkyl methacrylate as a main component generally has a temperature of 1 to 20.00 at 25°C.
The monomer solution has a viscosity of 0 centivoice and contains 3 to 40% by weight of polymer, preferably 6 to 20% by weight.

The crosslinking agent (B) used in the present invention is a monomer having at least two (meth)acryloyl groups in the molecule, and the number of atoms between the (meth)7acryloyl groups is 10 or less. % formula (1) [Here, n is an integer of 3 to 6, and MA represents a methacryloyl group. ] [Here, R1 is H, CH3, C2R5, CH20H, and R2 is H, CH3.

CH20COC=CH2 (R4 represents a group of H or CH3), R3 represents a group of H or CH3, respectively, R+, R2 and R3 are not hydrogen at the same time, (M>A is a methacryloyl group or an acryloyl group) Represents Ko(H)A, C-+CH2CH20SF-(14)...
- (3) [where n is 1 or 2, and (M)A represents a methlyloyl group or an acryloyl group. Specific examples of these monomers include 1,3-propylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanethiol dimethacrylate, 1,3-butylene glycol dimethacrylate, Dimethylolethane dimethacrylate, 1.1
-dimethylolpropane dimethacrylate, 2,2. −
Dimethylolpropane dimethacrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane dimethacrylate, ethylene glycol di(meth)acrylate and diethylene glycol di( Meta>acrylate, etc. can be mentioned.

The amount of these crosslinking agents (B) used is determined based on the resin raw material ('A
>100 parts by weight, from 2 to 250 parts by weight, preferably from 4 to 150 parts by weight. That is, if it is less than 2 parts by weight, no improvement in the heat resistance of the final molded product is observed,
On the other hand, if it exceeds 250 parts by weight, the final molded product will be brittle and cannot be put into practical use.

The methacrylic resin molding material according to the present invention is produced by polymerizing a mixture of the resin raw material (A) and a crosslinking agent (B) in the presence of a polymerization initiator, and then polymerizing the monomers present in the mixture. A gel-like partial polymer is used, which is obtained by stopping the reaction when only a portion of the polymer has reacted without the entire polymer reacting.

In this case, the content of the polymer present in the methacrylic resin molding material, which is a gel-like partial polymer, is (A>alkyl methacrylate at-form, α, β-ethylenically inert saturated form containing alkyl methacrylate as the main component). 4 to 7 higher than the polymer content in the mixture of the monomer mixture and the resin raw material selected from the group consisting of partial polymers thereof and (B) the crosslinking agent.
5% by weight and not more than 90% by weight, preferably 10-75% by weight and not more than 90% by weight, most preferably 20-65% by weight and 90% by weight. The range does not exceed %. If the above polymer content value is less than 4% by weight, the product will not have a gel-like appearance and will be inconvenient to handle, and if it increases by 75% or exceeds the upper limit of 90%, it will not be good during molding. Both of these do not meet the purpose of the present invention.

The polymer content in the partial polymer can be determined by an extraction method.

Various types of polymerization initiators can be used, but if a low-temperature active polymerization initiator and a high-temperature active polymerization initiator are used together, the formation reaction of the gel-like partial polymer can be controlled by the action of the low-temperature active polymer initiator. The gel-like molding material thus obtained is then roughly heated and molded into a desired article by the action of the high temperature active polymerization initiator. However, it is also possible to use only one polymerization initiator, either a high temperature active initiator or a low temperature active initiator.

In the case of the molding material of the present invention, the polymerization initiator consumed when the molding material is roughly heated and molded into a desired article can be mixed in when the gel-like molding material is crushed. It is. Therefore, when partially polymerizing a mixture of resin raw material (A> and crosslinking agent (B)), only the amount of polymerization initiator that will be lost during the polymerization process is mixed, and the resulting gel-like molding material is The storage stability of the molding material can be improved by mixing in a polymerization initiator that is consumed when the crushed molding material is roughly heated and molded into the desired article. Therefore, it is desirable.

In this case, a low temperature active polymerization initiator is mixed when partially polymerizing the mixture of the resin raw material (A> and the crosslinking agent (B)), and a high temperature active polymerization initiator is mixed when crushing the gel molding material. It is more desirable.

As the low-temperature active polymerization initiator, peroxide and azo compound radical polymerization initiators having a decomposition temperature of 50° C. or lower to obtain a half-life of 10 hours, for example, are preferable.

In order to improve the storage stability of this molding material, it is preferable that the low-temperature active polymerization initiator disappears as much as possible during the polymerization process to obtain the molding material, so the decomposition temperature is set at 26 to 4
5°C is preferred, particularly 26-41°C. Also,
The amount of the low-temperature active polymerization initiator used is 0.002 to 1% by weight based on the total amount of the resin raw material (A) and the crosslinking agent (B).
, preferably 0.005 to 0.1% by weight.

Examples of such low-temperature active polymerization initiators include (I)
Acetyl cyclohexyl sulfonyl peroxide, isobutyryl peroxide, cumyl peroxy neodecanoate, diisopropyl peroxy dicarbonate,
Di-n-propyl peroxydicarbonate, cimilistyl peroxydicarbonate, 2,2゛-azobis(
4-methoxy-2,4-dimethylvaleronitrile), (
II) di(2-ethoxyethyl)peroxydicarbonate, di(methoxyisopropyl)peroxydicarbonate, di(2-ethylhexyloxydicarbonate, (III) di(3-methyl-3-
methoxybutyl) peroxydicarbonate, t-butyl peroxyneodecanoate, 2,2°-azobis(
Among these, compounds belonging to groups (I) and (II) are preferred, and compounds belonging to group (I>) are particularly preferred.

As a high temperature active polymerization initiator, the decomposition temperature is 60 to 220
A polymerization initiator such as peroxide at a temperature of 90 to 170 °C is preferred, and in order to improve the molding cycle and maintain storage stability,
Most preferably, it is a polymerization initiator having a decomposition temperature of 120 to 160°C. Further, the amount of the high temperature active polymerization initiator used is 0 with respect to the total amount of the resin raw material (A> and the crosslinking agent (B)).

02-2.0% by weight, preferably 0.05-2.

0% by weight used.

Examples of such high temperature active polymerization initiators include (IV
) t-butylcumyl peroxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,
5-dimethyl-2,5-di(1-butylperoxy)hexyne-3,1,1,3,3-tetramethylbutylhydroperoxide, 2,5-dimethylhexane-
2,5-cybidrobar oxide, cumene hydroperoxide, t-butyl hydroperoxide,
1,1,2.2-tetraphenyl-1,2-ethanediol, (V) 1,1-bis(t-butylperoxy)-3.3.5-trimethylcyclohexane, 1,
1-bis(t-butylperoxy)cyclohexane, t
-Butyl peroxymaleic acid, t-butyl peroxylaurate, t-butyl peroxy- 3.
3. 5-trimethylhexanoate, cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,2-bis(t-butylperoxy)octane , t-butylperoxyacetate, 2,2-bis(t-butylperoxy)butane,
t-butyl peroxybenzoate, n-butyl-4,
4-bis(t-butylperoxy)valerate, di-t
-butylshiba-oxyisophthalate, methyl ethyl ketone peroxide, α, α' -bis(t-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy) ) Hexane, (VI) t-butyl hydroperoxide, m-toluoyl peroxide, benzoyl peroxide, t-butyl peroxyisobutyrate, 2,3-dimethyl-2,3-diphenylbutane, octanoyl peroxide , decanol peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide, succinic acid peroxide, acetyl peroxide, 1,1°-
Azobis (cyclohexane gocarbonitrile), etc., and among these, (ff) and (V) are preferred.
A compound belonging to the group of (1) is particularly preferable.
It is a compound belonging to the group v).

As mentioned above, the methacrylic resin molding material according to the present invention is produced by heating a mixture of the resin raw material (A> and the crosslinking agent (B>) in the presence of the polymerization initiator to polymerize it. ~80'C1 Preferably, the polymerization is carried out at a temperature of 35 to 65°C for 10 to 300 minutes, preferably 20 to 180 minutes.When using both low-temperature-active and high-temperature-active polymerization initiators together, low-temperature-active polymerization Although almost all of the initiator is consumed, the high-temperature active polymerization initiator does not decompose at the reaction temperature and remains as it is, so it is consumed during the molding reaction using the molding material.

According to the present invention, a glue-like partial polymer with a desired polymerization rate can be obtained by stopping the polymerization reaction by first quenching, etc. However, according to the present invention, the resin raw material (A>
When heating and polymerizing a mixture of and crosslinking agent (B) in the presence of the polymerization initiator, a gel polymer with a desired polymerization rate can be obtained more easily by adding a specific amount of a specific regulator. be able to. Such specific preparations include 1
, 4(8)-P-menthadene, 2,6-cymethyl-
These include 2,4,6-octatriene, 1,4-P-menthadene, 1,4-cyclohexadiene, and α-methylstyrene dimer.

Such a regulator is the resin raw material (A>) and the crosslinking agent (B).
O-0001-0.5% by weight, preferably 0.001-0.2% by weight, most preferably 0.0% by weight, based on the total amount of
It can be used in a range of 0.05 to 0.1%. When the amount of the regulator added is less than 0.0001% by weight, the regulating effect of the present invention is not exhibited, and when the amount added exceeds 0.5% by weight, the desired polymerization rate cannot be achieved.

According to the method of the invention, the desired polymerization rate is determined by the amount of the regulator,
It can be adjusted by selecting the amount of low-temperature active radical polymerization initiator and the polymerization temperature.

That is, as the amount of the low-temperature active initiator is reduced, the polymerization rate becomes significantly slower at low polymerization rates. Furthermore, the larger the amount of the regulator is used, the slower the polymerization rate will be at a lower polymerization rate than when no regulator is used, and the time taken to reach that point will also be longer. Furthermore, the lower the polymerization temperature, the lower the polymerization rate and the slower the polymerization rate with the same formulation composition.

According to the method of the present invention, a gel-like polymer with a desired polymerization rate can be obtained by stopping the polymerization reaction by rapid cooling during polymerization or slowing down the polymerization rate by reducing the amount of polymerization initiator. According to method 2, it is possible to obtain a gel-like partial polymer with a desired polymerization rate with good reproducibility through simpler operations, and it is also possible to obtain a gel-like partial polymer with good storage stability.

However, the greatest feature of the present invention is that the gel-like partial polymer thus obtained is crushed to produce particles with an average particle size of 5.
The point is that the thickness should be less than mm, preferably less than 2 mm. The gel-like partial polymer obtained by partially polymerizing the resin raw material (A>) and the crosslinking agent (8) is not sticky and has shape retention properties, and the monomer portion is exactly the same as the network-structured polymer portion. It has a structure that seems to be incorporated into each cavity.

When the gel-like partial polymer is subjected to a crushing treatment, each unit forming the above-mentioned structure (i.e., the monomer portion incorporated into a certain network-grooved polymer portion) is made smaller. became clear. Surprisingly, the gel-like partial polymer, which has been crushed to an average particle size of 5 mm or less, exhibits extremely stable fluidity when pressure is applied, and can be easily melted under even smaller pressures. It has been found that such crushing treatment does not reduce the flowability and the consistency of the resulting molded product in any way. For example, when extruding the molding resin material through a die when injecting it into a mold, etc., changes in fluidity due to changes in the ratio of the diameter of the die to the length L, that is, the L/D ratio, may occur without crushing. Compared to the case of a gel-like partial polymer, it is considerably smaller and more improved.

To crush the gel-like partial polymer, if the polymer content of the gel-like partial polymer is relatively low, for example, the total polymer content does not exceed 50% by weight, screws, calender rolls, etc. may be used to crush the gel-like partial polymer. This can be done by mixing using a kneader. This is because crosstalk has a crushing effect as is well known. Note that the distribution effect, which is another effect of kneading, does not appear to be directly involved in the present invention. By performing the mixing in this way, the average particle size can be made to be 5 mm or less, preferably 2 mm or less, but it is more desirable to knead until the molding material becomes paste-like. By forming the molding material into a paste form in this manner, the fluidity of the molding material during molding becomes better.

In addition, gel-like partial polymers, especially gel-like partial polymers with a relatively high polymer content that cannot cause crosstalk as described above,
It can be easily crushed and crushed by using a crusher such as a ball mill or a cutter mill.

In addition, additives such as a chain transfer agent, a coloring agent, a filler, or other resins or other resins may be added to the raw material mixture before polymerization in the gel-forming reaction by partial crosslinking, if necessary.

For example, as a chain transfer agent, an alkyl having 11 to 1 carbon atoms may be used.
Examples include n-alkyl and t-furkyl mercaptans of 2, thioglycolic acid, and thioglycolic acid alkyl esters in which the alkyl group has 11 to 8 carbon atoms. Further, as the colorant, any ordinary dye or pigment can be used. Roughly,
Examples of the filler include glass fiber, calcium carbonate, methyl oxide, aluminum hydroxide, particulate carbon, carbon fiber, mica flakes, calcium phosphate, barium 5A acid, magnesium oxide, and tin oxide.

Further, these additives or other resins can be blended into the methacrylic resin molding material at the time of crushing, as long as they are kneaded when crushing the gel-like partially crosslinked polymerization agent. Therefore, the resin raw material (A>) and the crosslinking agent (
Various methacrylic resin molding materials can be prepared from 10 pieces produced under the same conditions up to the stage of partial crosslinking of B) by changing the formulation added during kneading.

The methacrylic resin molding material according to the present invention is prepared by compression molding, injection molding, transfer molding, etc. at a temperature of 80 to 170°C, preferably 90 to 160'C for 1.5 to 30 minutes.
It is preferably heated for 3 to 20 minutes to form an article having the desired shape.

Next, the present invention will be explained in detail with reference to Examples.

In the Examples, the polymer content of the partial polymer was measured by the following method.

1. Add hydroquinone methyl ether to a Soxhlet extractor. OOppm added dissolved dichloromethane 15
0ml, and put the gel polymer 15q in the form of strips into an extraction thimble filter, and perform far-flow extraction for 20 hours in a constant temperature water bath kept at 50°C. The stream is poured into 1,200 rm1 of methanol, the polymer fraction is separated, combined with the polymer fraction in the filter paper, and dried under reduced pressure at 55° C. to a constant weight to determine the weight of the polymer.

Examples 1 to 2 20 parts by weight of neopentyl glycol dimethacrylate was added to 80 parts by weight of methyl methacrylate syrup containing 8% of polymethyl methacrylate having a viscosity average degree of polymerization of about 12,000, and -1,4(8) - p-menthagene 0.0
08% by weight, PCNDO, 'OO5% by weight, PBDo,
A mixture of 3% by weight was mixed and dissolved at 450x with a plate thickness of 6mm.
The cell was injected into a cell made of two 350mm wide glass plates with a 10mm gap between them using a vinyl chloride gasket, and the cell was placed in a constant temperature water bath heated to 60°C. After 2 hours and 2.5 hours had elapsed, it was taken out and the polymer content of the partial polymer was measured at 25.3.
It was 2%. This partial polymer was
When the mixture was fed into 1 cm square dice and extruded into an extruder with L/D=8, a paste-like extrudate with a maximum particle diameter of 2 mm was obtained.

The fluidity was measured and shown in Table 1 and Figures 1 and 2. Also, vertical 2501 heated to 120'C in advance
111+1. 320Q was placed in a mold to obtain the molded product shown in Fig. 4 with a width of 135 mm and a depth of 35 mm.
After holding the pressure at 3 k (J/ci), the pressure was increased to 76 kMd and held for 1 minute, then the pressure was increased to 230 ko/crA, and after holding for 15 minutes, the mold was opened to obtain a molded product. The molded product had a shape similar to that of the mold, had no material flow pattern in the rising portion, and had a beautiful appearance.

Measurement of fluidity Examples 1 to 2 were placed in the cylinder of an advanced flow tester.
The mixed wire methacrylic resin molding material obtained in 1 and the unkneaded methacrylic resin molding materials obtained in Comparative Examples 1 and 2, respectively, were filled, and the plunger was heated at a temperature of 25°C. The molding material was discharged from the die by moving with a constant load. We investigated the relationship between flow time and plunger travel distance at this time. The results are shown in Table 1 and Figure 1. The flow rate was roughly determined from the slope of the relationship diagram between the flow time and the plunger travel distance, and the viscosity at the load was calculated from this. The viscosity was calculated in the same manner by changing the pressure applied to the plunger. Similar measurements were repeated by roughly changing the diameter and length L of the dice. The results obtained are shown in Table 2 and FIG.

Examples 3 to 5 20 parts by weight of neopentyl glycol dimethacrylate was added to 80 parts by weight of methyl methacrylate syrup containing 8% polymethyl methacrylate with a viscosity average degree of polymerization of about 12.000 to form a highly viscous liquid containing PCNDo, 004. Weight%, P
BDo, 2% by weight was kneaded and dissolved into a plate with a thickness of 6 mm.
With two glass plates measuring 450 x 350 mm,
It was injected into a cell assembled using a vinyl chloride gasket with a spacing of 3 mm, polymerized in a thermostatic water bath at 55°C for 2 hours, then taken out, and the polymer content of the partial polymer was measured. 74 %Met. This partial polymer was crushed into a mesh of 5m using a crusher made by Horai Iron Works Co., Ltd.
m, and pulverization was carried out by passing cooling water and limiting the supply amount in order to avoid heat generation. The pulverized crosslinked gel polymer was
S standard mesh F33% mesh, 4 mesh, 6 mesh,
9 meshes, 16 meshes, and sieve with a receiver, and the sieved crushed partial polymer 180C] on 6 meshes, 9 meshes, and 16 meshes was placed in a 200 m vertical column.
The molded product shown in FIG.
Pressure was held for 2 minutes at 65 kL'cffl, then held at high pressure 230 kg/c, j for 15 minutes, and the mold was opened to obtain a molded product. The appearance of the molded product was smooth and the triangular structure was sufficiently transferred.

Comparative Examples 1 to 2 The same lot of partial polymer obtained in Example 1 was cut into a cylinder of a Koka-type flow tester using a cork polar, and its fluidity was measured. Results first
It is shown in the table and Figure 2. In addition, 320 (J) was placed in the same mold as in Example 1 in a plate shape, and compression molding was performed under the same conditions as in Example 1 to obtain a molded product. A flow pattern and a fissured pattern were observed on the upper plane.

Comparative Example 3 The partial polymer obtained in the same manner as in Example 3 was cut into a size of 200 x 180 mm in the form of a plate, and molded in the same mold as in Example 3 under the same conditions. The triangular apex of the molded product became rounded, and sufficient transferability could not be obtained.

Comparative Example 4 When the crushed partial polymer of 3% mesh obtained using the standard wire sieve in Example 3 was compression molded in the same mold and under the same conditions as in Example 3, the vicinity of the apex of the triangle turned white and became brittle. It became a thing.

(Effects of the Invention) As described above, the methacrylic resin molding material of the present invention comprises (A>alkyl methacrylate monomer, a mixture of α, β-ethylenically unsaturated monomers containing alkyl methacrylate as a main component, and A resin raw material selected from the group consisting of syrup containing a polymer and (B) the resin raw material 10
By partially polymerizing a mixture consisting of 2 to 250 parts by weight of a crosslinking agent per 0 parts by weight, the polymer content in the mixture is reduced so that the total polymer content does not exceed 90% by weight. Since it is made by crushing a partially cross-linked polymer with an average particle size of 5 mm or less, the molding material can be used for compression molding, injection molding,
When molding is performed using transfer molding methods, etc., it exhibits extremely stable fluidity with only a slight shear stress applied, and can flow into the desired shape to obtain a molded product that matches the mold. There are no defects in the appearance of the molded product.
Molding time can also be shortened. Furthermore, since the transferability can be improved, molded products having complicated shapes can be obtained. The resulting molded product is a crosslinked methacrylic resin molded product that has improved physical properties such as heat resistance and solvent resistance, and also enjoys the original properties of methacrylic resin such as transparency and weather resistance. It is.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between flow time and plunger travel distance of a partially cross-linked methacrylic resin molding material, and Figure 2 is a diagram showing the relationship between shear rate and viscosity of a partially cross-linked methacrylic resin molding material. FIG. 3 is a diagram showing a mold, and FIG. 4 is a diagram showing a mold. It's me (sec) Figure 2

Claims (5)

[Claims] (1) (A) A resin raw material selected from the group consisting of an alkyl methacrylate monomer, an α,β-ethylenically unsaturated monomer mixture containing alkyl methacrylate as a main component, and syrup containing the polymer; B) A mixture consisting of 2 to 250 parts by weight of a crosslinking agent per 100 parts by weight of the resin raw material is partially polymerized so that the total polymer content is 90% by weight.
A methacrylic resin molding obtained by crushing a partially crosslinked gel-like polymer whose polymer content is 4 to 75% by weight higher than the polymer content in the mixture within a range not exceeding the average particle size of 5 mm or less. material. (2) The methacrylic resin molding material according to claim 1, wherein the methacrylic resin molding material is in the form of a paste. (3) The methacrylic resin molding material according to claim 1 or 2, wherein the alkyl group of the alkyl methacrylate has 1 to 4 carbon atoms. (4) The amount of crosslinking agent per 100 parts by weight of resin raw material is 4 to 15
0 parts by weight, and the content of the polymer is increased by 10 to 65% by weight compared to the polymer content in the mixture. Claims 1 to 3 The methacrylic resin molding material according to any one of the above. (5) The methacrylic resin molding material according to any one of claims 1 to 4, wherein the alkyl methacrylate is methyl methacrylate.