JPH0618969B2 - Methacrylic resin molding material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a methacrylic resin molding material. More specifically, the present invention relates to a methacrylic resin molding material for obtaining a crosslinked molded article and having particularly excellent flow stability during molding.

(Prior Art) Generally, methacrylic resin containing methyl methacrylate as a main component is used in various fields such as lighting covers, automobile parts, signboards, ornaments, and sundries due to its excellent weather resistance and excellent transparency. However, since the methacrylic resin is a linear polymer, it has a drawback that heat resistance, solvent resistance, impact resistance and surface hardness are insufficient. For example, the heat resistance is limited to about 100 ° C., and it is the current situation that the requirements from various fields requiring heat resistance cannot be sufficiently met. For example, it cannot be used as a cover for headlamps as automobile parts, and in the case of tail lamps, the size of the lamp itself is larger than that of conventional products, or the amount of heat generated by increased illuminance is increased and the thickness is reduced due to cost reduction. From the both sides, improvement of heat resistance is required, and it is expected that the application will be expanded to automobiles, motorcycle (motorcycle) meter covers, solar water heater water heater covers, and other parts where the temperature rises significantly in direct sunlight. So
It is expected to develop a methacrylic resin that can withstand even the boiling point of water or higher.

Conventionally, for the purpose of improving the heat resistance of methacrylic resin, a method of copolymerizing methyl methacrylate and α-methylstyrene (US Pat. No. 3,135,723), a method of copolymerizing methyl methacrylate, α-methylstyrene and maleic anhydride ( Japanese Patent Publication No.45-31,953, Japanese Patent Publication No.49-10,156
No.), methylmethacrylate, α-methylstyrene and maleimide (Japanese Patent Publication No. Sho 48-95,490
No.) and many other methods have been proposed.

However, although heat resistance is improved in any of these methods, the polymerization rate is extremely slow, a high polymerization rate cannot be obtained without increasing the polymerization rate, and a polymer can be obtained efficiently in a relatively short time. However, the polymer has a strong tint, transparency, weather resistance, surface hardness, mechanical strength and the like have merits and demerits, industrial production is extremely difficult, and the present situation is that it has not been put to practical use. .

On the other hand, in general, introduction of a crosslinked structure into a linear polymer is considered to improve heat resistance, solvent resistance, etc. However, since the crosslinked polymer has already formed a three-dimensional structure, this crosslinked polymer has It is impossible to mold the coalesce by injection molding, extrusion molding or transfer molding. Further, in the case of molding by the casting polymerization method, voids, foaming and the like are likely to occur, so that not only a complicated shape cannot be molded but also its productivity is low.

Kodama et al., Polymer Chemistry Vol. 27, No. 297, p. 65 et seq. “One way to improve the moldability of cross-linked polymers is to use long distances between functional groups, and there is a considerable amount of monomer. In this state, for example, a method of completing the first stage polymerization (polymerization rate of 90% or more) and then performing the second stage polymerization to complete the polymerization is also possible. " However, there is no description of its specific example,
According to the additional test of the inventor based on the description of Kodama, etc.,
After completion of the first-stage polymerization, the sample was heat-compressed and molded in a mold, but the sample solidified but did not flow and became powdery, showing no moldability at all. Therefore, the molding described in Kodama et al. Means an extremely simple bending process.
It was impossible to apply to the molding with flow for the purpose of the present invention.

The present inventors have previously mentioned that, as shown in Japanese Patent Application No. 59-058,258, which can meet the above-mentioned demands, (A) an alkyl methacrylate monomer and an α, β-containing an alkyl methacrylate as a main component. A mixture of a resin raw material selected from the group consisting of an ethylenically unsaturated monomer mixture and a syrup containing a polymer thereof and (B) a mixture of 2 to 250 parts by weight of a crosslinking agent per 100 parts by weight of the resin raw material is partially added. When the total polymer content is not more than 80% by weight, the content of the polymer is 4 than the polymer content in the mixture.
A methacrylic resin molding material comprising a partially cross-linked gel polymer increased by up to 65% by weight and a method for producing the same have been found. Since the methacrylic resin molding material flows by applying shear stress at room temperature or at an elevated temperature,
The compression molding method, extrusion molding method, transfer molding method, etc. can be used to obtain a product having a complicated shape that cannot be molded by casting polymerization, and the molded product has excellent heat resistance and resistance. It showed various performances such as solvent resistance and impact resistance, and had excellent performances such as transparency and weather resistance which the methacrylic resin originally possessed without deterioration. However, the inventors of the present invention further conducted research on the methacrylic resin molding material, and when the methacrylic resin molding material was put into a fluid state by being applied with pressure, a slight but transient flow Retention is observed, which causes defective appearance such as patterns that were torn and flowed in the molded product when the draw ratio of the material was increased, and the material with high polymerization rate had poor mold transferability. There was found.
Further, the shear stress required to bring it into a fluidized state still needs to be quite high, and there is room for further improvement.

(Problems to be Solved by the Invention) Therefore, the present invention is intended to improve the problems of the methacrylic resin molding material as described above.

That is, an object of the present invention is to provide an improved methacrylic resin molding material. It is another object of the present invention to provide a methacrylic resin molding material for obtaining a cross-linked molded article and having particularly excellent flow stability during molding.

(Means for Solving Problems) The above-mentioned various purposes are (A) 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 a syrup containing the polymer, and (B) 2 to 250 per 100 parts by weight of the resin raw material. A mixture of parts by weight of cross-linking agent was partially polymerized to obtain a total polymer content of 9
Methacryl obtained by crushing a partially crosslinked gel polymer having an average particle size of 5 mm or less in which the content of the polymer is increased by 4 to 75% by weight relative to the content of the polymer in the mixture within a range not exceeding 0% by weight. This is achieved by a resin-based molding material.

Examples of the monomer used as the resin raw material (A) in the present invention include alkyl methacrylate alone or a mixture of alkyl methacrylate and an α, β-ethylenically unsaturated monomer copolymerizable therewith. In the case of such a monomer mixture, alkyl methacrylate is 50
It is preferably at least mol%, and more preferably at least 60 mol%. Examples of alkyl methacrylate include methyl methacrylate, ethyl methacrylate, n
-Propylmethacrylate, isopropylmethacrylate, n-butylmethacrylate, sec-butylmethacrylate, tert-butylmethacrylate, etc., but methylmethacrylate is particularly preferred.

As the copolymerizable monomer, an alkyl methacrylate other than the alkyl methacrylate (eg, methyl methacrylate) used as the main component (for example, the above-mentioned alkyl methacrylate or 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, 3-
Hydroxypropyl acrylate such as hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-chloropropyl acrylate, 2-
Hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, hydroxyalkyl methacrylate such as 2-hydroxy-3-chloropropyl methacrylate, acrylic acid, methacrylic acid, neodymium acrylate, lead acrylate , Acrylates such as boron acrylate, methacrylates such as neodymium methacrylate, lead methacrylate, and boron methacrylate,
Examples include vinyl chloride, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, α-methylstyrene, vinyltoluene, and anhydrous acid.

The syrup containing the polymer of the alkyl methacrylate or the monomer mixture containing alkyl methacrylate as a main component is generally 1 to 20,000 at 25 ° C.
It is a monomer solution having a viscosity of 0 centipoise and containing 3 to 40% by weight, preferably 6 to 20% by weight of a polymer.

The cross-linking agent (B) used in the present invention has at least two (meth) acryloyl groups in the molecule, and the number of carbon atoms existing between the (meth) acryloyl groups is
A monomer having 10 or less, preferably the following formulas (1) to
(3) [Here, n is an integer of 3 to 6, and MA represents a methacryloyl group. ] [Wherein R ₁ is H, CH ₃ , C ₂ H ₅ , CH ₂ OH, and R ₂ is H, CH ₃ , (R ₄ represents a group of H, CH ₃ ), CH ₂ OH group, R ₃ represents a group of H, CH ₃ respectively, and R ₁ , R ₂ and R ₃ are not hydrogen at the same time, and (M) A Represents a methacryloyl group or an acryloyl group. ] [Here, n is 1 or 2, and (M) A represents a mecryloyl group or an acryloyl group. ] Specific examples of these monomers include 1,3-propylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanediol 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 (meth) acrylate.

The amount of the cross-linking agent (B) used is the same as the resin raw material (A).
2 to 250 parts by weight, preferably 4 to 100 parts by weight
~ 150 parts by weight. That is, when the amount is less than 2 parts by weight, the heat resistance of the finally obtained molded product is not improved, while when it exceeds 250 parts by weight, the finally obtained molded product is fragile and cannot be practically used.

The methacrylic resin molding material according to the present invention is polymerized by heating a mixture of the resin raw material (A) and the cross-linking agent (B) in the presence of a polymerization initiator to obtain a mixture of the monomers present in the mixture. It uses a gel-like partial polymer obtained by stopping the reaction at a stage where a part of the polymer has reacted without reacting the whole amount.

In this case, the content of the polymer present in the methacrylic resin molding material, which is a gel-like partial polymer, is (A) an alkyl methacrylate monomer and an α, β-ethylenically unsaturated mono-component having alkyl methacrylate as a main component. 4 to 7 more than the polymer content in the mixture of the resin raw material selected from the group consisting of the monomer mixture and these partial polymers and the crosslinking agent (B).
A value increased by 5% by weight and not exceeding 90% by weight, preferably a value increased by 10 to 75% by weight and not exceeding 90% by weight, most preferably a value increased by 20 to 65% by weight and 90% by weight The range does not exceed%. If the value of the polymer content is less than 4% by weight, the product does not show a gel and is inconvenient to handle, and if the value increased by 75% or the upper limit of 90% is exceeded, it is good at the time of molding. It does not show flow and neither meets the objectives of the present invention.

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

As the polymerization initiator, various ones can be used, but if a low-temperature active polymerization initiator and a high-temperature active polymerization initiator are used in combination, the formation reaction of the gel-like partial polymer acts on the low-temperature active polymer initiator. When the gel-like molding material thus obtained is further heated to be molded into a desired article, it can be carried out by the action of the high temperature active polymerization initiator. However, it is also possible to use only one of the high-temperature activated initiator and the low-temperature activated initiator.

Further, in the case of the molding material of the present invention, the polymerization initiator consumed when the molding material is further heated to be molded into a desired article can be mixed in when crushing the gel molding material. . Therefore, when the mixture of the resin raw material (A) and the cross-linking agent (B) is partially polymerized, only the polymerization initiator that is lost in the polymerization process is mixed, and the obtained gel-like molding material is obtained. When crushing, the crushed molding material is further heated, so that it is possible to improve the storage stability of the molding material by incorporating a polymerization initiator that is consumed in molding the desired article. desirable. In this case, a low temperature active polymerization initiator is mixed when the mixture of the resin raw material (A) and the cross-linking agent (B) is partially polymerized, and a high temperature active polymerization initiator is mixed when the gel-like molding material is crushed. Is more desirable.

As the low temperature active polymerization initiator, for example, a peroxide having a decomposition temperature of 50 ° C. or lower for obtaining a half-life of 10 hours and an azo compound radical polymerization initiator 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 in the polymerization process for obtaining the molding material. Therefore, the decomposition temperature is preferably 26 to 45 ° C., particularly 26 to 45 ° C. 41 ° C. is preferred. The amount of the low-temperature active polymerization initiator used is 0.002 to 1% by weight, preferably 0.0, based on the total amount of the resin raw material (A) and the crosslinking agent (B).
05-0.1% by weight is used.

Examples of such a low temperature active polymerization initiator include (I)
Acetyl cyclohexyl sulfonyl peroxide, isobutyryl peroxide, cumyl peroxy neodecanoate, diisopropyl peroxydicarbonate,
Di-n-propyl peroxydicarbonate, dimyristyl peroxydicarbonate, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), (II) di-
(2-Ethoxyethyl) peroxydicarbonate, di-
(Methoxyisopropyl) peroxydicarbonate,
Di- (2-ethylhexyl) peroxydicarbonate,
(III) Di- (3-methyl-3-methoxybutyl) peroxydicarbonate, t-butylperoxyneodecanoate, 2,2'-azobis (2,4-dimethylvaleronitrile), etc. are available. Of these, compounds belonging to the groups (I) and (II) are preferable, and compounds belonging to the group (I) are particularly preferable.

The high temperature active polymerization initiator has a decomposition temperature of 60 to 220.
A polymerization initiator such as peroxide at 90 ° C. is preferable, and 90 to 170 ° C. for improving the molding cycle and maintaining storage stability,
More preferred is a polymerization initiator having a decomposition temperature of 120 to 160 ° C. The amount of the high-temperature active polymerization initiator used is 0.02 to 2.0% by weight, preferably 0.05 to 2.0% by weight based on the total amount of the resin raw material (A) and the crosslinking agent (B).
2.0% by weight is used.

Examples of such a high temperature active polymerization initiator include (IV)
t-Butylcumyl peroxide, diisopropylbenzene hydroperoxide, di-t-butylperoxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexyne-3 ,
1,1,3,3-tetramethylbutyl hydroperoxide,
2,5-Dimethylhexane-2,5-dihydroperoxide, 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-butylperoxymaleic acid, t-butylperoxylau Rate, t-butylperoxy-3,3,5-trimethylhexanoate, cyclohexanone peroxide, t-
Butyl peroxyisopropyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane,
2,2-bis (t-butylperoxy) octane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4- Bis (t-butylperoxy) valerate,
Di-t-butyldiperoxyisophthalate, methyl ethyl ketone peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t- Butyl peroxy)
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 1-carbonitrile), etc., among which, preferably, compounds belonging to the groups (IV) and (V) And particularly preferably a compound belonging to the group (IV).

As described above, in the methacrylic resin molding material according to the present invention, a mixture of the resin raw material (A) and the crosslinking agent (B) is heated in the presence of the polymerization initiator to polymerize. This polymerization reaction is carried out at a temperature of 10 to 80 ° C, preferably 35 to 65 ° C for 10 to 300 minutes, preferably 20 to 180 minutes. However, when both low-temperature active and high-temperature active polymerization initiators are used in combination, the low-temperature active polymerization initiator is consumed almost entirely, but the high-temperature active polymerization initiator remains as it is without being decomposed at the reaction temperature. Therefore, it is consumed during the molding reaction using the molding material.

According to the present invention, a gelled partial polymer having a desired polymerization rate can be obtained by stopping the polymerization reaction by quenching or the like. Further, according to the present invention, the resin raw material (A) and the crosslinking agent (B) are used. By heat-polymerizing a mixture of the above with the above-mentioned polymerization initiator, by adding a specific amount of a specific regulator, a gel polymer having a desired polymerization rate can be obtained more easily. Such specific regulators include 1,4
(8) -P-menthadiene, 2,6-dimethyl-2,4,6-octatriene, 1,4-P-menthadiene, 1,4-cyclohexadiene, and α-methylstyrene dimer.

Such regulators include the resin raw material (A) and the crosslinking agent (B).
0.0001 to 0.5% by weight, preferably 0.001 to 0.2% by weight, most preferably 0.0
It can be used in the range of 05 to 0.1%. If the amount of the regulator added is less than 0.0001% by weight, the regulating effect of the present invention is not exhibited, and if the amount added exceeds 0.5% by weight, the desired polymerization rate cannot be reached.

According to the method of the present invention, the desired degree of polymerization is the amount of the regulator,
It can be adjusted by selecting the amount of the low temperature active radical polymerization initiator and the polymerization temperature. That is, as the amount of the low temperature active initiator is decreased, the polymerization rate becomes markedly slow at the low polymerization rate. In addition, the larger the amount of the regulator, the slower the polymerization rate at a lower polymerization rate and the longer the time required to reach it, as compared with the case where the regulator is not used. Also, the lower the polymerization temperature, the lower the polymerization rate and the slower the polymerization rate in the same formulation.

According to the method of the present invention, a gelled polymer having a desired polymerization rate can be obtained by stopping the polymerization reaction by rapid cooling during the polymerization or slowing the polymerization rate by decreasing the amount of the polymerization disclosing agent. According to the method (2), a gel-like partial polymer having a desired polymerization rate can be obtained with good reproducibility and a gel-like partial polymer having good storage stability can be obtained by a simpler operation.

The greatest feature of the present invention is that the gel-like partial polymer thus obtained is crushed to obtain an average particle size of 5
mm or less, preferably 2 mm or less. The gel-like partial polymer obtained by partially polymerizing the resin raw material (A) and the cross-linking agent (B) is non-greasy and has a shape-retaining property, and the monomer component is just a polymer component having a network structure. It is configured to be taken into each cavity of.
When the gel-like partial polymer is subjected to a crushing treatment, it is apparent that each unit having the above-mentioned constitution (that is, a monomer component incorporated in a polymer component having a certain network structure) is made finer. Became. Surprisingly, the gel-like partial polymer, which has been crushed in this way and has an average particle size of 5 mm or less, exhibits extremely stable fluidity when pressure is applied, and is easy even with a smaller pressure. It was found that the fluidity and the physical properties of the obtained molded product were not deteriorated by such a crushing treatment. Further, for example, when the molding resin material is extruded through a die when being poured into a molding die or the like, a change in fluidity due to a change in the diameter D and length L of the die, that is, an L / D ratio does not cause crushing treatment. Compared with the case of the gel-like partial polymer, it is much smaller and more improved.

To crush the gel-like partial polymer, the gel-like partial polymer has a relatively low polymer content, for example, if the total polymer content does not exceed 50% by weight, a screw, a calendar roll, etc. It can be carried out by kneading using a kneader. This is because kneading has a crushing effect as is well known. The distribution effect, which is another effect of kneading, does not seem to be directly involved in the present invention. By carrying out the kneading in this way, the average particle diameter can be made 5 mm or less, preferably 2 mm or less, but it is more preferable to knead until the molding material takes a paste form. By thus forming the paste, the fluidity of the molding material at the time of molding becomes better.

Further, a gel-like partial polymer, particularly a gel-like partial polymer having a relatively high polymer content that cannot be kneaded as described above,
It can be easily crushed by using a crusher such as a ball mill or a cutter mill.

If necessary, an additive such as a chain transfer agent, a coloring agent, a filler, or other resin may be added to the raw material mixture before the polymerization in the gelling reaction by partial crosslinking.
For example, as a chain transfer agent, alkyl having 11 to 1 carbon atoms
2 n-alkyl and t-alkyl mercaptans, thioglycolic acid, alkyl thioglycolic acid alkyl esters having 11 to 8 carbon atoms, and the like. Further, as the colorant, any ordinary dye or pigment can be used. Further, as the filler, there are glass fiber, calcium carbonate, methyl oxide, aluminum hydroxide, particulate carbon, carbon fiber, mica flakes, calcium phosphate, barium sulfate, magnesium oxide, tin oxide and the like.

Further, these additives or other resins may be blended in the methacrylic resin molding material at the time of crushing, as long as they are kneaded when the gelled partially crosslinked polymer is crushed. Therefore, various methacrylic resin molding materials can be prepared by changing the compound to be added at the time of kneading from one lot manufactured under the same conditions until the step of partially crosslinking the resin raw material (A) and the crosslinking agent (B). It can be prepared.

The methacrylic resin molding material according to the present invention is 80 to 170 ° C. by a compression molding method, an injection molding method, a transfer molding method, or the like.
Preferably at a temperature of 90-160 ° C. for 1.5-30 minutes,
It is preferably heated for 3 to 20 minutes to be molded into an article having a desired shape.

Next, the present invention will be described in more detail with reference to examples.

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

150 ml of dichloromethane with dissolved 1000 ppm hydroquinone monomethyl ether in a Soxhlet extractor
And put the gel polymer 1 in the cylindrical filter paper for extraction.
After putting 5 g into strips, reflux extraction was carried out for 20 hours in a constant temperature water bath kept at 50 ° C.
It is put in 00 ml of methanol, the polymer content is separated, combined with the polymer content in the filter paper, and dried under reduced pressure at 55 ° C. until a constant weight is obtained, and the weight of the polymer is determined.

Examples 1 to 2 20 parts by weight of neopentyl glycol dimethacrylate were 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 -Mentadiene 0.008% by weight,
PCND 0.005% by weight and PBD 0.3% by weight were mixed and dissolved, and the mixture was made into two glass plates with a plate thickness of 6 mm and an area of 450 x 350 mm, and a vinyl chloride gasket was used so that the interval was 10 mm. Injected into the assembled cell, put the cell into a constant temperature water tank heated to 60 ℃,
After 2 hours and 2.5 hours, it was taken out and the polymer content of the partial polymer was measured and found to be 25, 32%. This partial polymer was fed into an extruder having a screw diameter of 50 mm and L / D = 8 in the form of a 1 cm square die, and when extruded, a paste-like extrudate having a maximum particle diameter of 2 mm was obtained. This fluidity was measured and shown in Table 1 and FIGS. 1 and 2. Also, the length of 250 is preheated to 120 ° C.
mm, width 135 mm, depth 35 mm, into the mold from which the molded product shown in FIG. 4 can be obtained, and 320 g was put into the mold and held at 23 kg / cm ² for 2 minutes, and then the pressure was increased to 76 kg / cm ² for 1 minute. The pressure was maintained, then the pressure was increased to 230 kg / cm ^2, and the pressure was maintained for 15 minutes. The molded product showed a shape similar to that of a mold, and there was no material flowing pattern on the rising portion, and a molded product having a beautiful appearance could be obtained.

Measurement of flowability In a cylinder of a high performance type flow tester, Examples 1-2
The kneaded methacrylic resin molding material obtained in 1. and the unkneaded methacrylic resin molding material obtained in Comparative Examples 1 and 2 which are used as controls, respectively, are filled, and a plunger is set under a temperature condition of 25 ° C. The molding material was discharged from the die by moving it with a constant load. The relationship between the flow time and the moving distance of the plunger at this time was investigated. The results are shown in Table 1 and FIG. Further, the flow rate was calculated from the slope of the relationship diagram between the flow time and the moving distance of the plunger, 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. Further, the same measurement was repeated while changing the diameter D and the length L of the die. The obtained results are shown in Table 2 and FIG.

Examples 3 to 5 PCND 0.004 was added to a highly viscous liquid obtained by adding 20 parts by weight of neopentyl glycol dimethacrylate 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. % By weight, P
BD 0.2% by weight was mixed and dissolved to obtain a mixture with a plate thickness of 6 mm.
After injecting into a cell assembled with two glass plates with a width of 50 x 350 mm using a vinyl chloride gasket so that the interval is 3 mm, and after polymerizing at 55 ° C for 2 hours in a constant temperature water bath The product was taken out, and the polymer content of the partial polymer was measured and found to be 74%. This partial polymer was attached with a mesh of 6 mm using a crusher manufactured by Toho Tekkosho Co., Ltd.
In order to avoid heat generation, the cooling water was passed through and the amount of supply was limited to pulverize. The crushed crosslinked gel polymer was sieved with a JIS standard mesh sieve 31/2 mesh, 4 mesh, 6 mesh, 9 mesh, 16 mesh and a saucer, and was sieved on 6 mesh, 9 mesh and 16 mesh. 180g of crushed partial polymer is 200mm in length and 180 in width
mm into the mold from which the molded product shown in FIG. 3 can be obtained, the mold temperature is 120 ° C., the initial pressure is 45 kg / cm ² for 2 minutes, and the intermediate pressure is 65 kg / cm ² for 1 minute. High pressure 230kg / cm ²
The pressure was held for 15 minutes and the mold was opened to obtain a molded product. The appearance of the molded product was smooth, and the transfer of the triangular structure was sufficient.

Comparative Examples 1 and 2 The partial polymers of the same lot obtained in Example 1 were cut out with a cork borer so that the partial polymers were put in the cylinder of the high-performance flow tester as they were, and the fluidity was measured. First result
The results are shown in the table and FIG. Further, 320 g of the plate-shaped product was put into the same mold as in Example 1 and compression molding was performed under the same conditions as in Example 1 to obtain a molded product. As for the appearance of the molded product, a flow pattern of the material was observed at the rising portion and a crack pattern was observed at the upper plane.

Comparative Example 3 A partial polymer obtained in the same manner as in Example 3 was cut into a plate-like shape having a size of 200 × 180 mm, and molded in the same mold as in Example 3 under the same conditions. The apex of the triangle of the obtained molded product became round, and sufficient transferability was not obtained.

Comparative Example 4 When the crushed partial polymer of 31/2 mesh obtained by the standard mesh sieve in Example 3 was compression-molded under the same conditions as those of Example 3, the corners of the triangle became white, It became fragile.

(Effects of the Invention) As described above, the methacrylic resin molding material of the present invention comprises (A) an alkyl methacrylate monomer, an α, β-ethylenically unsaturated monomer mixture containing alkyl methacrylate as a main component, and the same. A resin raw material selected from the group consisting of syrup containing a polymer and (B) the resin raw material 1
A mixture of 2 to 250 parts by weight of a cross-linking agent per 100 parts by weight is partially polymerized so that the total polymer content does not exceed 90% by weight. 4 to 75% by weight of the partially crosslinked gel polymer is crushed into particles having an average particle size of 5 mm or less. Therefore, compression molding method, injection molding method, transfer molding method, etc. using the molding material. When performing molding by applying a slight shear stress, it shows extremely stable fluidity, it can flow to the desired shape and mold-like molded products can be obtained, and it does not cause a block-shaped flow There is no appearance defect of the molded product and the molding time can be shortened. Further, since the transferability can be improved, a molded product having a complicated shape can be obtained. The resulting molded article is a crosslinked methacrylic resin molded article in which various physical properties such as heat resistance and solvent resistance are improved, and various physical properties such as excellent transparency and weather resistance originally possessed by the methacrylic resin are enjoyed as they are. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the flow time of the partially crosslinked methacrylic resin molding material and the moving distance of the plunger, and FIG. 2 shows the relationship between the shear rate and the viscosity of the partially crosslinked methacrylic resin molding material. It is a diagram, FIG. 3 is a figure which shows a metal mold | die, and FIG. 4 is a figure which shows a metal mold | die.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-51-125491 (JP, A) JP-A-51-125483 (JP, A) JP-A-57-167340 (JP, A)

Claims (5)

[Claims] 1. A resin raw material selected from the group consisting of (A) an alkyl methacrylate monomer, an α, β-ethylenically unsaturated monomer mixture containing alkyl methacrylate as a main component, and a syrup containing the polymer. And (B) a mixture of 2 to 250 parts by weight of a crosslinking agent per 100 parts by weight of the resin raw material is partially polymerized to obtain a total polymer content of 90.
A methacrylic system obtained by crushing a partially cross-linked gel polymer having an average particle size of 5 mm or less in which the content of the polymer is increased by 4 to 75% by weight from the content of the polymer in the mixture within a range not exceeding 5% by weight. Resin molding material. 2. The methacrylic resin molding material according to claim 1, wherein the methacrylic resin molding material has a paste form. 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 the crosslinking agent is 4 per 100 parts by weight of the resin raw material.
The amount of the polymer is about 150 parts by weight and the content of the polymer is 10 to 65% by weight higher than the content of the polymer in the mixture.
The methacrylic resin molding material according to any one of item 3. 5. The methacrylic resin molding material according to any one of claims 1 to 4, wherein the alkyl methacrylate is methyl methacrylate.