JPS61171713A - Production of polymethyl methacrylate molded article - Google Patents

Abstract

PURPOSE:To obtain the titled molded article for surface defect-free artificial marble, etc., by adding two kinds of polymerization initiators different in the half-life temperatures between each other in a composition made up of filler and a syrup consisting of methyl methacrylate polymer and methyl methacrylate monomer to effect polymerization to a specific conversion point followed by compression molding. CONSTITUTION:A composition made up of (1) 70-20pts.wt. of a syrup consisting of, based on the total amount of the syrup, (i) 0-50wt% of methyl methacrylate polymer and (ii) 100-50wt% of methyl methacrylate monomer and (2) 30-80pts. wt. of filler is incorporated with (A) a radical polymerization initiator with a 10hr half-life temperature <=50 deg.C and (B) a second radical polymerization initiator with a 10hr half-life temperature >=70 deg.C to perform polymerization on heating, of part of said monomer by the initiator (A) to adjust the conversion of the system between 30% and 80% by raising the conversion by >=10% to prepare a molding material. This material is them packed in a mold to carry out compression molding and curing mainly by the initiator (B), thus obtaining the objective molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a polymethyl methacrylate (hereinafter abbreviated as PMM)-based composite product containing a filler.

More specifically, methyl methacrylate (hereinafter abbreviated as MMA) based syrup and filler are mixed to form a bulk molding compound (hereinafter abbreviated as BMC) or a sheet molding compound (hereinafter abbreviated as 8MC),
The present invention relates to a method for manufacturing a filler-containing PMMA molded product, which is filled into a mold and hardened by compression molding.

(Prior art) PMMA-based molded products containing fillers have attracted attention in recent years due to their deep appearance, excellent mechanical strength, thermal performance, and weather resistance, and are particularly useful for use in ceiling boards, partition boards, etc. Its use as a decorative board, that is, an artificial marble board, is expanding.

Methods for manufacturing such PMMA molded products can be roughly divided into two. One method is to melt and mix thermoplastic PMMA resin and filler to form a molded product by extrusion molding or injection molding.Since the matrix PMMA resin is thermoplastic, it has excellent heat resistance and chemical resistance. It has the disadvantage of being inferior to The other method is cast molding, in which a slurry containing MMAM syrup and filler is injected into a mold and hardened. Heat resistance and chemical resistance are improved by increasing the degree of polymerization and adding a crosslinking agent. However, the molding time is long, the slurry is sticky, making it difficult to handle and workability is poor, and if the slurry is stored, the filler will settle and solidify, so it must be stirred vigorously each time it is used. No. Furthermore, since MMA has a high polymerization shrinkage rate, surface defects such as sink marks and fibre-purging holes are likely to occur in molded products, which may restrict the shape of the molded product or require special casting equipment. There are drawbacks. When increasing the amount of polymerization initiator or raising the polymerization temperature to shorten molding time, bubbles and cracks occur in the molded product. Increasing the filler loading amount and increasing the polymer concentration in the syrup have been proposed as methods to prevent defects caused by polymerization shrinkage, but these methods are not practical as they increase the slurry viscosity and make injection difficult. isn't it.

(Problems to be Solved by the Invention) In order to improve the handling of slurry, which is a viscous liquid, and to shorten the polymerization time and enable molding even when the slurry viscosity is high, unsaturated polyester resins such as BMC and SM are used.
Compression molding of C is known.

However, in the case of MMAM syrup, it does not have the thickening properties of unsaturated polyester resin, so in order to eliminate stickiness and improve handling, it is necessary to fill it with a large amount of filler or increase the polymer concentration of the syrup. This makes it virtually impossible to mix them, making it difficult to manufacture BMC and SMC.

The present invention manufactures BMC and SMC without the above-mentioned disadvantages, and produces filler-containing PMMA molded products, especially artificial marble boards, which have excellent heat resistance and chemical resistance, and are free from surface defects such as sink marks and fiber shows. The purpose is to provide a method for manufacturing in a short time with good workability.

(Means for Solving the Problems) The present invention provides 0 to 5011 based on the total amount of syrup.
% of methyl methacrylate polymer and 100~5oxi
70 to 20 parts by weight of methyl methacrylate syrup made of methyl methacrylate monomer of ts and 30 parts by weight of filler
~80 parts by weight, a radical polymerization initiator (A) with a 10-hour half-life temperature of 50°C or less and a 10-hour half-life temperature of 70°C
The above radical polymerization initiator (B) is added, and a part of the methyl methacrylate monomer is heated and polymerized by the radical polymerization initiator (A) to increase the polymerization rate of the system by 10 times or more. A filler-containing material that is adjusted to 30 to 80% and is used as a molding material, is compressed by filling the molding material into a mold, and is cured mainly by radical polymerization initiator (B) K. This is a method for manufacturing methyl methacrylate molded products.

The MMAM syrup used in the present invention contains ``cO~50% by weight of MMAM polymer and 1% by weight based on the total amount of syrup.
00 to 50 MM human mass monomer mixture, preferably 10 to 40 MM based on the total amount of syrup
It is a mixture of the A-based polymer and the MMA-based monomer of 90 to 6011 Azaki. If the content of the MMA-based polymer exceeds 50% by weight, the viscosity will be high and it will be difficult to fill with a predetermined amount of filler, which is not preferable. If the content of the reverse KMMA polymer is low, the viscosity of the slurry will be low, and as a result, the filler may settle during partial polymerization and the filler concentration in BMC or SMC may become uneven. Content value is 10
1 [JIL% or more, non-uniformity of filler concentration does not pose a practical problem.

An MMA-based monofish is defined as one in which MMA alone or one in 20 or less parts of MMA is replaced with a polymerizable monomer copolymerizable with MMA. Examples of polymerizable monomers that can be copolymerized with MMA include acrylic acid, methacrylic acid, and carbon number 1.
ester of ~18 monohydric alcohol and acrylic acid,
Ester of 1rlff+ alcohol having 2 to 18 carbon atoms and methacrylic acid.

Olefinic nitriles such as 7crylonitrile and methacrylonitrile, aromatic olefins such as styrene, α-methylstyrene, and tertiary-butylstyrene, vinyl esters such as vinyl acetate and vinyl benzoate, and vinyls such as acryl 7mide and methacrylamide. Monofunctional monomers such as 7mide and ethylene glycol di(meth)acrylate and polyethylene glycol: meth)7 acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanethiol di(meth)7 acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra Polyfunctional monomers such as (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, to name a few. These can be used alone or in combination of 211 or more.

Ru. Among these, polyfunctional monomers are preferably used because they form crosslinking bonds and improve the heat resistance and chemical resistance of the finished product. However, if the crosslinking density becomes too high, the molded product will become brittle, so the amount of polyfunctional monomer added should be MM.
0.01 to 2.0% by weight, preferably 0.01 to 1.81% by weight, more preferably 0.01 to 1.5% by weight, even more preferably 0.01% by weight based on the general control of the A-based syrup. ~
It is 1.2% by weight. The MMA-based polymer is defined as a polymer of the above-mentioned MMA-based monomer, and needs to be dissolved in the above-mentioned MMA-based monomer. Note that the amount of polyfunctional monomers added to the MMA syrup shall be calculated as the amount of all the polyfunctional monomers used in the MMA polymer as well as those in the MMA monomer. Further, the compositions of the MMA monomer and the MMA polymer in the MMA syrup do not necessarily have to be the same. The method for producing the MMA syrup described above is not limited to the percentage, and any method may be used, such as partially polymerizing the MMA monocasing, dissolving the MMA polymer in the MMA monomer, etc. You can take it.

The filler used in the present invention is not particularly limited as long as it does not interfere with the polymerization of the MMA-based polymer, and any filler that is generally used as a filler can be used. Examples of such are aluminum hydroxide, aluminum oxide, calcium carbonate, calcium silicate, calcium sulfate, barium sulfate, magnesium hydroxide, titanium oxide, silica, mica, talc, clay, calcium aluminate, hydroxy 7 Examples include powders such as patite and wood. These may be used alone or in combination of two or more. Is the amount of filler added based on the total amount of MMA syrup and filler? 30 to 80 weight. If the amount added is less than 30 weight tS, the effect of adding the filler, such as improving hardness, heat resistance, flame resistance, and reducing the shrinkage rate, will be small, and if the amount added exceeds SOS, the viscosity will increase. This is not preferable because it becomes impossible to uniformly mix a fixed amount of the filler.

In the present invention, a part of the MMA monomer in the slurry is polymerized to increase the polymerization rate of the system by 10% or more, and the polymerization rate of the system is increased to 30%.
It is necessary to control it within the range of ~80%, preferably 40-75%. In the present invention, the viscosity of the slurry is lowered to make it easier to mix the syrup and filler.
The slurry is naturally sticky, and in order to obtain BMCJPSMC with good handling properties, it is necessary to polymerize a part of the MMA monomer to increase the polymerization rate of the system by 10% or more to increase the viscosity. is required. Therefore, the indigo MMA monomer, which does not reach 10% in 1 part of the system, is only partially polymerized.B
MC and SMC are difficult to handle due to residual stickiness of the slurry. Similarly, if the polymerization rate of the system is less than 30%, BMC and SMC are sticky and difficult to handle. However, if the polymerization rate of the system exceeds 80%, BM
C and SMC have poor fluidity, making it difficult to fill them into molds. Note that the polymerization rate herein refers to a polymerization rate calculated assuming that all the polymers present in the system from the beginning were unpolymerized polymerizable mono-indigo.

In the present invention, the process of polymerizing the MMA-based monomer is divided into two stages. In the process of partially polymerizing the MMA monomer in the slurry, it is required to increase the polymerization rate of the system by 10% or more to bring the polymerization rate of the system to a range of 30 to 80%. It is therefore required that the polymerization and curing be carried out without inconvenience and without the influence of the previous partial polymerization.

The present inventors have conducted intensive studies on a polymerization method that satisfies these two requirements at the same time. 1) Using two types of radical polymerization initiators with different decomposition temperatures, the partial polymerization process is carried out at a relatively low temperature, and compression molding is performed. It has been found that the process can be carried out at a relatively high temperature. That is, MM in the slurry
The step of partially polymerizing the A-based monomer to produce BMC or SMC is carried out using a radical polymerization initiator (A) with a 10-hour half-life temperature of 50 °C or lower, preferably 45 °C or lower, and The SMC compression molding process is mainly carried out using a radical polymerization initiator (B) having a 10-hour half-life temperature of 70°C or higher, preferably 75°C or higher. Partial polymerization is carried out using a radical polymerization initiator with a 10-hour half-life temperature exceeding 50°C, or compression molding curing is carried out.
If you try to use a radical polymerization initiator with a 10-hour half-life temperature of less than 70°C, the radical polymerization initiator for compression molding curing will decompose during the partial polymerization process.
It may become impossible to control the polymerization rate of the system between 30 and 80%. Therefore, the 10-hour half-life temperature T A ('C) of the radical polymerization initiator (A) for the partial polymerization process and the 10-hour half-life temperature TB ('C) of the radical polymerization initiator (B) for the compression molding process. preferably satisfies Tll≧TA+30.Also, the set temperature T p of the partial polymerization step
('C) is TA≦TP≦'l' B -20゜TP
It is necessary to satisfy ≦60. If TP<TA, the partial polymerization process takes a long time and is impractical, and TP
>TB-20 or TP>60, the radical polymerization initiator (B) for the compression molding step is decomposed in the partial polymerization step, making it impossible to control the polymerization rate of the system to 30 to 80%.

Note that the 10-hour half-life temperature of the radical polymerization initiator here refers to the 10-hour half-life temperature of the radical polymerization initiator. When kept at a constant temperature as a 2 mol/l benzene solution, it is the temperature at which the half-life is 10 hours.

As the radical polymerization initiator used in the partial polymerization step and compression molding step described above, those normally used in radical polymerization can be used, but the 10-hour half-life temperature used in the partial polymerization step is 50 (A) below ℃
Examples include di-3-methoxybutyl peroxydicarbonate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di-secondary butyl peroxydicarbonate, di-n-propyl peroxydicarbonate, 2゜4 .4-) Peroxide-based initiators such as limethylpentyl peroxyphenoxy acetate, tert-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, inbutyl peroxide, acetyl cyclohexyl sulfonyl peroxide and 2.2′-7zobisuN,
N-dimethylene imptyramidine dihyde p Coolai F
, 2,2'-7zobis-4-methoxy-2,4-dimethylpaleronitrile and the like can be mentioned. These may be used in combination for 28 or more. The amount of radical polymerization initiator (A) added is 10% of the MMA syrup.
-1:0,002 to 0.4 mIt part, more preferably 0.02 to 0.21 mIt part per 0.011 part. If the amount added is less than 0.002 parts by weight, the partial polymerization process will take a long time, making it impractical, and the polymerization rate of the system will not reach a predetermined value. )
This is undesirable because it may induce decomposition and make it impossible to stop the unit.

The 10-hour half-life temperature used in the compression molding process is 70°C.
Examples of the above radical polymerization initiator (B) include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone ketone peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, .5-Dimethyl-2,5-ditertiary-butyl peroxyhexane, 2,2'-ditertiary-butyl peroxybutane, tertiary-butyl peroxyacetate, ditertiary-glythyl peroxyhexahydroterephthalate, ditertiary-butyl peroxyase peroxide initiators such as benzoyl peroxide and 1°1'-7zobis-1-cyclohexane carportol, 2-carbamoylazoisoptylonitrile, 2,2'-7zobis-2.4.4- ) 7zo-based initiators such as trimethylpentane can be mentioned.

Two or more of these may be used in combination. The amount of radical polymerization initiator (B) added is 100! 0.1 to 1.0 parts per volume, preferably 0.2 to 1.0 parts
It is a 0.6-layer lid. If the amount added is less than 0.1 portion, the polymerization rate will not increase during compression molding, and the heat resistance of the molded product will therefore decrease, which is not preferable. Addition amount is 1.
If it exceeds 0 heavy electric parts, cracks may occur in the molded product during compression molding, which is not preferable.

Methods for controlling the polymerization rate of the system in the partial polymerization process include 1
There is no particular restriction, and any method can be used, such as adjusting the amount of the radical polymerization initiator (A) added or stopping the polymerization by cooling during the polymerization.

Partial polymerization is carried out by heating the slurry to a temperature of 60°C or less, as described above, but if it is spread thinly into a sheet, temperature control is easy, and the ratio of vsim in the system is reduced. It is easy to carry out and is advantageous. Sheet-shaped partially polymerized products can be used together as BMC or as they are as SMC. What is BMC and SMC?
In order to prevent the MMA monomer from escaping, the surface is usually covered with a film or metal foil, but in the present invention, if the slurry is injected into the film or metal foil from the beginning and the slurry is partially mixed, This is advantageous because the step of covering the surface with a film or metal foil can be omitted. BMC and S obtained in this way
The MC may be compression molded directly or may be stored or transported for a while and then molded.

The mold used in the compression molding of the present invention is not particularly limited as long as it does not interfere with the polymerization of the MMA monoplate, but a metal mold with excellent mold strength, pressability, and heat conductivity is recommended. The compression molding temperature is preferably 80 to 140°C. If the compression molding temperature is less than 80° C., molding takes a long time and is not practical. Furthermore, if the compression molding temperature exceeds 140° C., the molded product may become soft and cannot be removed unless the deaf is cooled, resulting in large losses of heat and time, which is economically disadvantageous. Therefore, it is desirable that the 10-hour half-life temperature of the radical 1 initiator (B) does not exceed 130°C.

In addition to the ingredients explained above, uninvented BMC and SMC also contain
It is possible to add polymerization accelerators, chain transfer agents, stabilizers, reinforcing materials, dyes and pigments, modifiers, mold release agents, etc. as necessary.

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited in any way by these Examples.

(Example) Examples 1 to 6 PMMA was dissolved in a mixed solution of MMA and trimethylolpropane trimethacrylate to produce syrup. Siltup 100. ! Diisopropyl peroxydicarbonate (10 hour half-life temperature 40°C) 0.0
3'IL gill, ditertiary butyl peroxyhexahydrothyrephthalate) (10% half-life temperature 83°C
) 0.3 times.

11 parts of stearin #1 was added, and aluminum hydroxide (Hyclite H-30, manufactured by Showa Denko K.K.) was further mixed to form a slurry. This slurry was poured into a casting mold in which two glass plates made of vinylon film facing inward were held at a 4-fi interval, and the entire mold was held between two heating plates, and the heating plates were heated to 55°C. After heating for an appropriate time,
The heating plate was cooled to 5° C. to obtain an easy-to-handle SMC having a system ratio shown in Table 1.

Two sheets of SMC with the vinylon film removed were filled in a 200m square, 50cm deep mold with a mirror-like glossy surface, and pressure molded at 120°C and 80 to 9/al for 10 minutes. did. All of the obtained Yusei had an astronomical stone-like surface with a mirror-like luster, and there were no defects such as poor filling.

In Example 1, the casting mold was placed horizontally and occasionally turned upside down to perform partial polymerization while preventing the filler from settling. In addition, in Example 6, the slurry viscosity was a little high, so the casting mold was opened and the slurry was poured, and the mold was placed at 4°C.
The slurry was compressed to a thickness of m and partially polymerized. Table 1 shows the formulation in each example.

Comparative Example 1 A syrup was prepared by dissolving 6G parts of a mixed solution of 39.9 parts by weight of MMA and 0.1 parts by weight of trimethylpropane trimethacrylate. This syrup 70
Although 30 parts by weight of the same aluminum hydroxide as used in Examples 1 to 6 was added to the parts by weight and mixed, the viscosity was high and uniform mixing could not be achieved.

Comparative Example 2 15 parts by weight of MMA and 85 parts by weight of the same aluminum hydroxide used in Examples 1 to 6 were mixed, but they could not be mixed uniformly. Comparative Example 3 SMC with a system polymerization rate of 65% was obtained by the same operation as in Example 6 except that 80 parts by weight of syrup and 20 parts by weight of filler were used. This was bravely molded by the same operation as in Example 6. Most of the surface of Yuujou had a mirror-like luster, but there were some dull sink marks.

Example 7 Slurry with the same composition as Example 6 (Togane ratio of the system is 50%)
Using the same procedure as in Example 6 except for changing the partial polymerization time, an SMC with a system polymerization rate of 60 was obtained. This SMC was not sticky and was easy to handle. The molded product obtained by pressure molding this in the same manner as in Example 6 had a mirror-like glossy surface, and there were no defects such as poor filling.

Comparative Example 4 Slurry with the same formulation as Example 6 (polymerization rate of the system is 50%)
Using the same procedure as in Example 6 except for changing the partial polymerization time, an SMC with a system polymerization rate of 55- was obtained. When the vinylon film was removed, this SMC was sticky and could not be handled easily. However, the molded product obtained by pressure molding this in the same manner as in Example 6 had a mirror-like glossy surface and had no defects such as poor filling.

Example 8 Slurry with the same formulation as Example 2 (polymerization rate of the system is 10%)
The polymerization rate of the system was increased by 20 times to obtain SMC with a system polymerization rate of 30% using the same procedure as in Example 2 except for changing the partial 1 polymerization time. This SMC had little tackiness even after the vinylon film was peeled off, and was easy to handle. The molded product obtained by pressure molding this in the same manner as in Example 2 had a mirror-like glossy surface and had no defects such as poor filling.

Comparative Example 5 Slurry with the same formulation as Example 2 (polymerization rate of the system is 10%)
Using the same procedure as in Example 2 except for changing the partial polymerization time, the polymerization rate of the system was increased by 15% to obtain SMC with a system polymerization rate of 25%. When the vinylon film was removed, this SMC was sticky and difficult to handle. However, the molded product obtained by pressure molding using the same procedure as in Example 2 had a mirror-like glossy surface and no defects such as poor filling.

Comparative Example 6 SMC with a system polymerization rate of 85% was obtained by using the same slurry as in Example 2 and performing the same operations as in Example 2 except for changing the partial polymerization time. This SMC was molded into a Yugyo by the same operation as in Example 2, but a filling failure occurred due to poor fluidity.

Examples 9 to 11 A syrup was prepared by dissolving 1 part of PMMA201i in a mixed solution of 79.8 parts by weight of MMA and 0.2 parts by weight of ethylene glycol dimethacrylate. To 30 parts by weight of this syrup, 20 parts by weight of calcium carbonate (Whiten B, manufactured by Shiraishi Calcium Co., Ltd.), silica (Glistalite AA
1. Made by Tatsumori Co., Ltd.) 30-layer lid, fluminicum hydroxide (
Hisilite H-30, Showa Denko Co., Ltd.) 2011
1 part and 1 part of stearic acid were added, and the radical polymerization initiator shown in Table 2 was further added and mixed at °C to obtain a slurry. This was heated at the hot plate temperature shown in Table 2 for an appropriate time, and Example 2
The polymerization rate of liberal arts is 55-6596 by the same operation as ~5.
obtained SMC. When this was molded using the same deafness as in Examples 1 to 6 under the same conditions, a molded product with mirror-like luster and no defects was obtained.

Comparative Examples 7 to 11! ! SMC was prepared by the same operations as in Examples 9 to 11 except for using the radical polymerization initiator and hot plate heating temperature shown in 3.
However, in all cases, polymerization did not stop even when the hot plate was cooled, and the polymerization rate of the SMC system reached 90 degrees or more. This was achieved using the same mold and under the same conditions as Examples 1 to 6, but
Because the SMC was stiff, he was unable to attain the form of bravery.

Comparative Example 12 SMC obtained by the same procedure as Comparative Example 11 except that the heating temperature of the hot plate was set to 40 ° C. and partial polymerization was carried out for 4 hours had the same fluidity and stickiness as the slurry before partial polymerization. When the vinylon film was peeled off, the mold could not be filled.

Example 12 1 part of PMMA 9-weight was added to an important part of MMA21-heavy plate, and to this was added 0.009 part by weight of diisopropyl peroxydicarbonate, 0.09 part by weight of ditertiarybutylperoxyhexahydrothyrephthalate, and 0 part of stearic acid. .Triple 1L part and aluminum hydroxide (Hisilite H-3
0, manufactured by Showa Denko Co., Ltd.) 70 Jukanbu were mixed to form a slurry. This was treated in the same manner as in Examples 2 to 5 to obtain an easy-to-handle SMC with a system polymerization rate of 60 inches. The bravery who achieved this SMC by the same operation as in Examples 1 to 6.

It had a mirror-like glossy surface and no defects such as poor filling occurred.

Procedural amendment (voluntary) May 1985 278 1. Indication of the case 1985 Patent Application No. 12310 2. Name of the invention Method for manufacturing polymethyl methacrylate molded products 3. Person making the amendment Relationship to the case Patent Applicant 3-8-2 Nihonbashi, Chuo-ku, Tokyo 4. Date of amendment order (voluntary) 5. Subject of amendment 6. Contents of amendment (1) Page 3, line 4 of the specification (hereinafter referred to as PMMAJ)
The description of "(hereinafter referred to as polymethyl methacrylate PMMA)
Correct it with J.

(2) “(hereinafter referred to as MMA) on page 3, line 6 of the specification
” has been corrected to [(Hereinafter, methyl methacrylate will be corrected to MMAJ.

(3) On page 3, line 8 of the specification, the description “(hereinafter referred to as BMC)” was changed to “(hereinafter referred to as bulk molding compound BMC)”.
Correct as MCJ.

+4) 8A specification page 3, line 9 “(hereinafter referred to as SM
The description of ``C'' has been corrected to ``(Sheet molding compound is hereinafter referred to as SMCJ.

(5) “80chi” on page 10 of the statement @ line 14
The description in ``801i quantity chi'' has been corrected.

(6) On page 19 of the specification, line 7, the statement ``Film was hotta'' is corrected to ``Film was attached.''

(7) The statement of the claims from page 1, line 4 to line 2, line 17 of the specification is amended as follows.

2. Claims (0 to 50% by weight based on the total amount of syrup)
70 to 20 parts by weight of a methyl methacrylate syrup consisting of a methyl methacrylate polymer and a methyl methacrylate monomer in a lo'50i amount, and 30 to 8 parts by weight of a filler.
A radical polymerization initiator (A) with a 10-hour half-life temperature of 50°C or lower and a radical polymerization initiator (B) with a 10-hour half-life temperature of 70°C or higher are added to 0 parts by weight of the radical polymerization initiator (A). ) K Therefore, a part of the methyl methacrylate monomer is heated and polymerized to increase the polymerization rate of the system by 10 or more, and the polymerization rate of the system is adjusted to 30 to 80% to obtain a molding material. A method for producing a filler-containing methyl methacrylate-based finished product, which is characterized in that it is filled indoors, compacted, and cured mainly by a radical polymerization initiator (B) K.

(2) Methyl methacrylate syrup has a content of 0.0% based on its total amount. 2. The method according to claim 1, wherein the syrup contains a polyfunctional monomer of 1 to 2.0% by weight.

(3) Radical polymerization initiators (A) and (B) 1
Claim 1 in which the 0-hour half-life temperature satisfies the following formula!
The method according to item 181.

T1≧T530 (4) Radical polymerization initiator (A) and (B) 1
2. The method according to claim 1, wherein the 0-hour half-life temperature and the temperature at which a portion of the methyl methacrylate monomer is thermally polymerized satisfy the following conditions.

TB-20≧'rp≧TA% 'rp≦60However, TA,
T is 1 of radical polymerization initiators (A) and (B), respectively.
The 0-hour half-life temperature (°C) is the heating temperature at which a part of the methyl methacrylate monomer is heated and polymerized. " stomach

Claims (4)

[Claims] (1) Based on the total amount of syrup, 70 to 20 parts by weight of methyl methacrylate syrup consisting of 0 to 50% by weight of methyl methacrylate polymer and 100 to 50% by weight of methyl methacrylate monomer, and 30 parts by weight of filler. ~80
A radical polymerization initiator (A) with a 10-hour half-life temperature of 50°C or lower and a radical polymerization initiator (B) with a 10-hour half-life temperature of 70°C or higher are added to parts by weight, and the radical polymerization initiator (A) is added. By heating and polymerizing a part of the methyl methacrylate monomer to increase the polymerization rate of the system by 10% or more and adjusting the polymerization rate of the system to 30 to 80%, the molding material is made into a molding material. A method for producing a filler-containing methyl methacrylate molded product, which comprises filling the mold into a mold, compressing it, and curing it mainly with a radical polymerization initiator (B). (2) The method according to claim 1, wherein the syrup contains 0.01 to 2.0% by weight of a polyfunctional monomer based on the total amount of the methyl methacrylate syrup. (3) The method according to claim 1, wherein the 10-hour half-life temperature of the radical polymerization initiators (A) and (B) satisfies the following formula. TB≧TA+30 (4) Claim 1, in which the 10-hour half-life temperature of the radical polymerization initiators (A) and (B) and the temperature at which a portion of the methyl methacrylate monomer is heated and polymerized satisfy the following conditions: Method described. TB-20≧TP≧TA, TP≦60 However, TA and TB are respectively radical polymerization initiators (A),
TP indicates the 10-hour half-life temperature of (B), and the heating temperature when heating and polymerizing a part of the methyl methacrylate monomer.