JPH07100908A - Production of marblelike molded product - Google Patents

Abstract

PURPOSE:To simply and inexpensively produce a deep-draw product having marblelike appearance. CONSTITUTION:20-200 pts.wt. of an inorg. filler and a polymerization initiator are kneaded with 100 pts.wt. of an acrylic resin syrup and the resulting kneaded mixture is polymerized to prepare a thermoplastic resin with a wt. average mol.wt. of 200000-1500000. This resin is molded into a thermoplastic resin plate with a thickness of 1-15mm and this plate is subjected to vacuum and/or pressure forming to produce a molded product having marblelike appearance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molded article having a marble-like appearance by vacuum and / or pressure forming.

[0002]

2. Description of the Related Art Conventionally, acrylic resin moldings containing a large amount of inorganic filler have been mainly produced by casting, and kitchen countertops with a marble-like appearance,
It is used for wash-basins and desk panels. For example, Japanese Patent Application Laid-Open No. 4-345812 discloses a method for producing a shaped article by casting a mixture of an acrylic syrup and an inorganic filler. However, the method of cast molding into the shape of a molded product according to these uses has low productivity, and cracks are likely to occur during cast molding, resulting in poor yield.

[0003]

When an acrylic resin plate mixed with an inorganic filler is subjected to vacuum and / or pressure forming to make a molded product other than a flat plate, the amount and size of the inorganic filler, the molecular weight of the acrylic resin, There are restrictions on plate thickness. For example, when a large amount of an inorganic filler is added, the rigidity of the resin plate increases, and even if the resin plate is heated above the softening point of the matrix resin, sufficient extensibility is not exhibited, and vacuum and / or pressure forming becomes difficult. On the other hand, when the amount of the inorganic filler is too small, there arises a problem that the filler is settled during the polymerization and a problem that the marble-like appearance of the resin plate is impaired.
Also, it is possible to reduce the molecular weight of the polymer so that the rigidity of the resin plate does not increase too much even if it is highly filled, but vacuum and / or air pressure molding of a highly filled resin plate using a low molecular weight polymer as a matrix Then, there arises a problem that the thickness distribution of the molded product becomes large and the extensibility is small. On the contrary, the highly filled resin plate in which a high molecular weight polymer having a weight average molecular weight of more than 1,500,000 is matrixed has high rigidity and a high softening point as described above, and causes depolymerization of the polymer during preheating. Furthermore, as the plate thickness increases, a larger force is required for stretching during heating, which makes vacuum and / or pressure air molding difficult.

[0004] The present invention is intended to improve the present problems, and provides a method for producing a deep-drawn molded product having a marble-like appearance.

As a result of various studies by the present inventors, a casting plate having a specific plate thickness prepared by compounding a specific amount of an inorganic filler and controlling the molecular weight of the matrix resin to fall within a specific range and polymerizing the mixture. The present invention has been completed by finding that by using it, it is possible to produce a deep-drawing molded product by thermoforming and having a marble-like appearance.

[0006]

According to the present invention, an inorganic filler 20 is added to 100 parts by weight of an acrylic syrup consisting of a (meth) acrylic polymer and a (meth) acrylic monomer.
~ 200 parts by weight and a curing agent are mixed to polymerize a mixture to give a weight average molecular weight of 200,000 to 1,500,000 and a thickness of 1
TECHNICAL FIELD The present invention relates to a method for producing a molded product having a marble-like appearance by forming a flat thermoplastic resin plate having a thickness of up to 15 mm, and vacuum and / or pressure forming the obtained resin plate in a state of being heated to a softening point or higher. .

The molded product retains a marble-like appearance without sedimentation of the inorganic filler, and has a relatively small wall thickness distribution after vacuum and / or pressure molding. It also has excellent mechanical strength and resistance to surface contamination.

The acrylic syrup used in the present invention is, for example, methyl (meth) acrylate or ethyl (meth).
1 of alkyl (meth) acrylate monomers such as acrylate, butyl (meth) acrylate, propyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate Or a mixture of two or more kinds and a polyalkyl (meth) acrylate obtained by using one or more kinds of the above-mentioned monomers as a raw material. In addition, a part of the monomers is ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta. It may be replaced with one or more of polyfunctional (meth) acrylate monomers such as erythritol tetra (meth) acrylate.

The proportion of the monofunctional and polyfunctional (meth) acrylate monomers and the (meth) acrylate polymer in the acrylic syrup is 90 to 50% by weight for the former and 1 for the latter.
0 to 50% by weight, preferably 80 to 70% by weight for the former and 20 to 30% by weight for the latter. Moreover, the polyfunctional (meth) acrylate monomer is 0% of the whole acrylic syrup.
-5% by weight, more preferably 0-3% by weight. However, when a large amount of polyfunctional monomer is used, the softening temperature of the resin plate rises, and the stretchability at the time of heating also decreases, so it is not suitable for a deep-drawn molded product.

The inorganic filler used in the present invention may have an average particle size of 100 μm or less. Examples thereof include metal oxides such as calcium carbonate, talc, clay, silica, alumina, quartz and calcium silicate. A commonly used one such as a hydrate can be used. Among such inorganic fillers having an average particle diameter of 100 μm or less, those which are filled as high as possible and are dispersed with good stability even at low viscosity are desirable, and hydrates of metal oxides are particularly desirable.

When a silane coupling agent is used when kneading the acrylic syrup and the inorganic filler, the resin plate obtained by polymerizing the obtained molding material is improved in water resistance, stain resistance and mechanical strength. Examples of the silane coupling agent include γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, and vinyltriacetoxysilane.

The amount of the inorganic filler used is 20 to 200 parts by weight based on 100 parts by weight of the acrylic syrup. If the amount is less than 20 parts by weight, sedimentation of the inorganic filler easily occurs, and a beautiful marble-like appearance cannot be obtained. If the amount exceeds 200 parts by weight, the viscosity of the mixture of the acrylic syrup and the inorganic filler becomes too high and the workability is deteriorated, and the rigidity of the obtained resin plate is too high to allow thermoforming. Furthermore, the transparency of the resin plate is also reduced, and the texture of marble is lost.

Examples of the polymerization initiator used in the present invention include organic peroxides generally used in medium-temperature molding such as benzoyl peroxide and methyl ethyl ketone peroxide, and organic amines which are accelerators used in combination with them. There are salts of polyvalent metals. The polymerization initiator is usually used in an amount of 0.5 to 3% based on the weight of the acrylic syrup.

In the production of a resin plate obtained by mixing an acrylic syrup and an inorganic filler and polymerizing the mixture, the molecular weight of the polymer component produced by polymerizing the monomer component by adding the chain transfer agent to the resin blend. Can be controlled. Examples of the chain transfer agent used include mercaptos such as α-methylstyrene dimer, thiocresol, octyl β-mercaptopropionate and octyl thioglycolate.
A polymer having a weight average molecular weight of 200,000 to 1,500,000 can be obtained by adding these in an amount of 0 to 1% by weight based on the weight of the acrylic syrup and using the above-mentioned polymerization initiator.

The resulting polymer has a weight average molecular weight of 20.
If it is less than 10,000, the thickness distribution of the molded product becomes large when the obtained resin plate is heat-molded, and if it is a deep-drawn molded product, it will be broken at the high-stretched portion and cannot be molded. On the other hand, in the case of a polymer having a weight average molecular weight of more than 1,500,000, the resin plate has a high rigidity, is hard to be softened even when heated, and has a low extensibility. Therefore, the weight average molecular weight of the produced polymer is 200,000 to 150.
It should be in the range of 10,000, and more preferably 500,000 to 1
It is desired to be, 000,000.

Further, in obtaining the polymerized resin plate, other than the inorganic filler, the polymerization initiator, the silane coupling agent, and the chain transfer agent, if necessary, various fillers in an amount within the range that does not impair the effect of the present invention, A modifier, a plasticizer, a defoaming agent, a coloring agent and the like may be added.

Further, the polymerized resin plate has a thickness of 1 to 15 m.
Create so that it falls within the range of m. If the thickness is less than 1 mm, the corner portion of the molded product may become thin and may be broken by being stretched in vacuum and / or pressure molding. On the other hand, if the thickness exceeds 15 mm, the tensile stress of the resin plate during vacuum and / or pressure forming becomes large, and it becomes impossible to sufficiently mold with vacuum or pressure of about 3 kgf / cm ² .

In order to specifically carry out the present invention, for example, 10 to 50 parts by weight of poly (meth) acrylate, a monofunctional (meth) acrylate monomer and a polyfunctional (meth) acrylate are used.
It is sufficient to add 20 to 200 parts by weight of an inorganic filler having an average particle size of 100 μm or less and 0.5 to 3.0 parts by weight of a polymerization initiator to 100 parts by weight of an acrylic syrup consisting of 90 to 50 parts by weight of an acrylate monomer. Knead and disperse. At this time, as the inorganic filler, one previously treated with a silane coupling agent may be used, or a silane coupling agent corresponding to 0.1 to 2.0% by weight based on the weight of the inorganic filler used may be used as the syrup. By using the inorganic filler after being dissolved or dispersed in, the water resistance, stain resistance and mechanical strength of the obtained molded article can be improved. Furthermore, in order to control the molecular weight of the polymer component produced after the polymerization, a chain transfer agent may be added in an amount of 0 to 1% by weight based on 100 parts by weight of the acrylic syrup.
As a kneading method, for example, a low-speed kneader such as a double-arm kneader, a high-speed agitator such as a disper, a pigment disperser for producing a paint, or a kneading roll may be used, and the inorganic filler added to the monomer mixture during kneading In addition to the agent, various fillers, thixotropic agents, plasticizers, defoamers, coloring agents and the like may be added if necessary. The viscosity of the resin mixture before polymerization obtained by kneading varies depending on the amount of the poly (meth) acrylate component and the amount of the filler, but can be adjusted to a range of several poises to several thousand poises at 30 ° C. Next, the obtained resin composition is poured into a flat plate mold made of two flat plates such as stainless steel and glass and a spacer and heated to polymerize the (meth) acrylate monomer. When a thick cast plate is polymerized, it is polymerized in a medium having a high heat removal efficiency such as a water bath, if necessary.

The thickness thus obtained is 1 to 15 mm
The resin plate of above is heated by the heater above the softening point of the resin plate, usually 1
It is heated to 20 to 240 ° C., and the resin plate in the softened state is vacuum and / or pressure formed by a conventionally known method. The temperature of the mold at this time may be room temperature, but a molded product having a smaller wall thickness distribution and excellent surface properties by heating to near the glass transition point of the resin plate, usually 90 to 110 ° C., and molding there. Can be obtained.

[0020]

EXAMPLES Examples will be described in more detail below, but these are not representative of all of the present invention.

Example 1 Polymethylmethacrylate (SUMIPEX B-LG-6, manufactured by Sumitomo Chemical Co., Ltd., hereinafter PM)
Also described as MA. ) 30 parts by weight was dissolved in 70 parts by weight of methyl methacrylate to obtain 100 parts by weight of acrylic syrup. 100 parts by weight of the obtained acrylic syrup was added to a polymerization initiator benzoyl peroxide paste (Nyper B
O, 2.0 parts by weight of NOF CORPORATION, 0.5 parts by weight of triphenylphosphine accelerator, defoaming agent (BYK A51)
5, 0.1 parts by weight of Big Chemie Japan Co., Ltd. and 50 parts by weight of aluminum hydroxide (Hijilite HS-320, Showa Denko KK) were added and kneaded with a high-speed stirrer to blend the resin. I got a thing.

The resin composition thus obtained was poured into a mold prepared by sandwiching a spacer having a thickness of 3 mm between two glass plates and heated at 60 ° C. for 100 minutes to prepare a resin plate. The molecular weight of the matrix resin component of the obtained resin plate was 1.1 million on the weight average and 850,000 on the number average, excluding polymethyl methacrylate that was present in advance. The obtained resin plate is preheated at 200 ° C. for 5 minutes, a mold for vacuum or compressed air molding with an exhaust port is maintained at 90 ° C., and a compressed air of 3 kgf / cm ² is applied from above to mold.
After holding for 1 minute, a molded product was obtained. The shape of the mold is 8c deep
m, minimum radius of corner is 5R, average area expansion rate is 10
A box type of 0% (2 times) was used. The obtained molded product was completely imprinted to the corners, and there was little partial variation in wall thickness. Furthermore, the stain resistance of the molded product,
The heat resistance also showed excellent performance as shown in Table 1.

Example 2 A resin plate was produced in the same manner as in Example 1, except that the amount of aluminum hydroxide added was changed to 100 parts by weight in the same resin composition as in Example 1.
The molecular weight of the matrix resin component of the obtained resin plate was 1,100,000 on the weight average and 850,000 on the number average excluding polymethyl methacrylate which was present in advance. The obtained resin plate was molded by the same apparatus and method as in Example 1 to obtain a molded product. The obtained molded product was completely imprinted to the corners, and the local variation in wall thickness was small. Further, the stain resistance and heat resistance of the molded product also showed excellent performance as shown in Table 1.

Example 3 A resin plate having a thickness of 10 mm was obtained by the same resin formulation and resin plate manufacturing method as in Example 1.
The molecular weight of the matrix resin component of the obtained resin plate, except for polymethylmethacrylate that was previously present,
The weight average was 1.1 million and the number average was 850,000. The obtained resin plate was preheated at 200 ° C. for 15 minutes, molded by the same apparatus and method as in Example 1, and held for 5 minutes to obtain a molded product. The obtained molded product was completely imprinted to the corners, and the local variation in wall thickness was small. Furthermore,
The stain resistance and heat resistance of the molded product also showed excellent performance as shown in Table 1.

Example 4 A resin plate was obtained by polymerization in the same manner as in Example 1 except that the amount of acrylic syrup shown in Table 1 was used. The molecular weight of the matrix resin component of the obtained resin plate was 1.4 million on a weight average and 950,000 on a number average except for polymethylmethacrylate which was present in advance. The obtained resin plate was molded by the same apparatus and method as in Example 1 to obtain a molded product. The obtained molded product was completely imprinted to the corners, and the local variation in wall thickness was small. Further, the stain resistance and heat resistance of the molded product also showed excellent performance as shown in Table 1.

Example 5 0.1 part by weight of octyl thioglycolate as a chain transfer agent was added to 100 parts by weight of acrylic syrup in the same resin composition as in Example 1,
After manufacturing a resin plate in the same manner as in Example 1, 120 ° C.
After-curing for 120 minutes. The molecular weight of the matrix resin component of the obtained resin plate was 50 on a weight average basis excluding the preexisting polymethylmethacrylate.
The number average was 220,000. The obtained resin plate was molded by the same apparatus and method as in Example 1 to obtain a molded product. The obtained molded product was completely imprinted to the corners, and the local variation in wall thickness was small. Further, the stain resistance and heat resistance of the molded product also showed excellent performance as shown in Table 1.

Comparative Example 1 100 parts by weight of polymethylmethacrylate (SUMIPEX B-LG-6, PMMA beads, manufactured by Sumitomo Chemical Co., Ltd.) were melted in a double-arm kneader heated to 200 ° C., and water was further added. 50 parts by weight of aluminum oxide (Hijilite HS-320, average particle size 3.5 μm, manufactured by Showa Denko KK) was added and kneaded. After kneading for 10 minutes, the mixture was rapidly fed to a flat plate mold heated to 90 ° C. and compression-molded. The molecular weight of the polymethylmethacrylate used was 70,000 on a weight average and 39,000 on a number average. The obtained resin plate having a thickness of 3 mm is preheated at 180 ° C. for 5 minutes,
When pressure molding was carried out by the same apparatus and method as in Example 1,
Since the corners of the molded product were thin and had holes during molding, perfect molding was not possible.

Comparative Example 2 A resin plate was manufactured in the same manner as in Example 1, except that the addition amount of aluminum hydroxide was changed to 250 parts by weight in the same resin composition as in Example 1.
The molecular weight of the matrix resin component of the obtained resin plate was 1,100,000 on a weight average and 850,000 on a number average except for polymethylmethacrylate which was present in advance. When the obtained resin plate having a thickness of 3 mm was molded by the same apparatus and method as in Example 1, the resin plate was broken during shaping and could not be molded.

(Comparative Example 3) The same resin composition as in Example 1 was poured into a mold made by sandwiching a spacer having a thickness of 20 mm between two glass plates and polymerized in a water bath at 60 ° C for 100 minutes. A resin plate was obtained. The weight average molecular weight of the matrix resin component of the obtained resin plate was 1.1 million, and the number average molecular weight was 850,000. The resin plate thus obtained was preheated at 200 ° C. for 15 minutes, and pressure molding was attempted by the same apparatus and method as in Example 1. The resin plate was slightly stretched and could not be completely shaped. . Further, pre-heating was attempted with the same resin plate at 220 ° C. for 15 minutes at a pneumatic pressure of 4 kgf / cm ² , but this was also slightly stretched but could not be completely shaped.

Comparative Example 4 A resin plate was obtained by polymerizing in the same manner as in Example 1 except that the amount of acrylic syrup shown in Table 1 was used. The weight average molecular weight of the matrix resin component of the obtained resin plate was 2.2 million, and the number average molecular weight was 1.2 million. When the obtained resin plate was molded by the same apparatus and method as in Example 1, the resin plate broke during shaping and could not be molded.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

The present invention has a beautiful marble-like appearance,
A deep-drawing molded product having excellent water resistance, heat resistance, and stain resistance can be manufactured extremely simply and inexpensively. Therefore, the molded product obtained by the method of the present invention can be used in many fields such as bathtubs and kitchen counters.

Claims (1)

[Claims] 1. A (meth) acrylic polymer and (meth)
A composition in which 20 to 200 parts by weight of an inorganic filler and a polymerization initiator are mixed with 100 parts by weight of an acrylic syrup made of an acrylic monomer is polymerized to have a weight average molecular weight of 200,000 to 1,500,000 and a plate thickness of 1 A method for producing a marble-like molded product, which comprises molding a thermoplastic resin plate having a thickness of up to 15 mm, and heating the obtained resin plate to a softening point or higher for vacuum and / or pressure molding.