JPH0912823A - Synthetic resin molding material and production of molding from the same - Google Patents

Abstract

PURPOSE: To provide a synthetic resin molding material which is one called a premix being capable of being subjected to a a heat compression molding process higher in productivity than the casting process and prepared by an easy operation within a short time and can give a molding in which the gloss and transparency of the resin particles in the premix are retained and to produce a molding therefrom. CONSTITUTION: This synthetic resin molding material is obtained by mixing 100 pts.wt. mixture comprising 10-60wt.% acrylic syrup based on methyl methacrylate, 0-85wt.% inorganic filler and 1-85wt.% inorganic-filler-filled resin particles having a degree of swelling in methyl methacrylate of below 2.5 and being insoluble in methyl methacrylate with 0.1-5.0 pts.wt. polymerization initiator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin molding material used for producing an acrylic resin molded article, and a method for producing a molded article using the synthetic resin molding material.

[0002]

2. Description of the Related Art Acrylic resin moldings containing inorganic fillers are characterized by a deep appearance and a high-grade feel. For example, as artificial marble, a kitchen top plate, various countertops, It is used in many applications such as vanities, bathrooms, flooring and wall materials.

A method for producing an acrylic resin molded article for use in artificial marble or the like is as follows: an acrylic syrup containing methyl methacrylate as a main component, aluminum hydroxide as a filler, and a polymerization initiator. A casting method in which a molding material composed of the mixed composition is poured into a mold prepared in advance and then heat-polymerized (Japanese Patent Publication No. 50-22586),
A method in which a molding material composed of a mixed composition of acrylic syrup, aluminum hydroxide as a filler, and polymethylmethacrylate resin powder is heated and melted to be shaped and cooled (JP-A-1-14138). Is common.

Further, in recent years, an acrylic resin which is formed by compression molding a molding material made of a mixed composition of an unsaturated monomer containing methyl methacrylate as a main component, an inorganic filler and resin particles. A method for producing a resin molded product has been proposed (JP-A-5-32720).

[0005]

The method for producing an acrylic resin molded product by the above-mentioned casting method is such that after the acrylic syrup is obtained by dissolving the polymer in an unsaturated monomer mainly composed of methyl methacrylate. In this method, a predetermined additive is added to the acrylic syrup to prepare a slurry, and then the slurry is polymerized and cured in a state of being along a mold.

The molding material used here has a low boiling point of the unsaturated monomer in the acrylic syrup, so that the unsaturated monomer is liable to volatilize during the polymerization and curing of the slurry, and the molding product thus obtained is obtained. Vacancies occur in the.

For this reason, the polymerization at the time of polymerization and curing of the slurry is carried out at a low temperature of 60 to 80 ° C., which is lower than the boiling point of the monomer, to prevent volatilization of the monomer at the time of polymerization and curing of the slurry. , It is necessary to prevent the formation of voids in the molded product. Therefore, in the method for producing an acrylic resin molded product by the cast method, the rate of polymerization and curing of the slurry is slow, and it takes a long time to manufacture the molded product, resulting in poor productivity.

On the other hand, in a method for producing a resin molded product in which a thermosetting resin is shaped by compression molding, a preform prepared in a putty form by mixing a liquid thermosetting resin with predetermined additives. It is a method of heat compression molding a molding material called mix. Generally, in the case of a molded product with a wall thickness of 1 mm, it can be molded in less than 1 minute, and it has higher productivity and is more economical than the casting method. Moreover, it can be molded into molded products of various shapes.

The above-mentioned Japanese Patent Laid-Open No. 5-32 utilizing this method.
In the method for producing an acrylic resin molded product described in Japanese Patent No. 720, an unsaturated monomer containing methyl methacrylate as a main component, an inorganic filler, and a degree of swelling with respect to methyl methacrylate of 3 to 15 times. The method comprises preparing a premix composed of a mixed composition with resin particles and subjecting the mixture to heat compression molding.

However, in this method for producing a resin molded product, in the premix which is a synthetic resin molding material,
Since resin particles having a large degree of swelling with respect to methyl methacrylate of 3 to 15 times are used, it takes a long time to swell the resin particles sufficiently and uniformly, so that it is necessary to prepare a premix. Not only is it time-consuming, but it also has drawbacks such as a decrease in gloss and transparency of the resulting molded article.

Therefore, the object of the present invention is that it can be subjected to a heat compression molding method which is more productive as compared with the casting method, the preparation operation is easy, and it can be prepared in a short time. To provide a synthetic resin molding material, which is a molding material called a premix having, and which can obtain a molded article in which the gloss and transparency of the resin particles mixed in the premix do not decrease. Another object of the present invention is to provide a method for producing a molded product from the synthetic resin molding material.

[0012]

DISCLOSURE OF THE INVENTION The inventors of the present invention have prepared a molding material called a premix with a resin particle containing an inorganic filler which has a degree of swelling with respect to methyl methacrylate of less than 3 and is insoluble in methyl methacrylate. By using, as a result of confirming that it is possible to easily prepare a premix in a short time, and yet it is possible to produce a heat compression molded product without lowering the gloss or transparency of the resin particles,
The present invention has been completed.

The above object can be achieved by the synthetic resin molding material of the present invention having the following constitution, and a method for producing a molded product from the synthetic resin molding material. That is, the present invention
Acrylic syrup (a) containing methyl methacrylate as a main component, 10 to 60% by weight, and inorganic filler (b) 0 to 8
5% by weight, and the degree of swelling with methyl methacrylate is 2.
The amount of the polymerization initiator (d) is 0.1 to 5 parts by weight with respect to 100 parts by weight of the mixture with the inorganic filler-containing resin particles (c) 1 to 85% by weight which is 5 or less and is insoluble in methyl methacrylate.
It is made of a synthetic resin molding material containing 5.0 parts by weight.

The present invention further comprises 10 to 60% by weight of an acrylic syrup (a) containing methyl methacrylate as a main component,
Inorganic filler (b) 0 to 85% by weight, and inorganic filler-containing resin particles (c) 1 to 85% by weight having a degree of swelling with respect to methyl methacrylate of 2.5 or less and being insoluble in methyl methacrylate. From 100% by weight of the mixture of 100 parts by weight of the mixture, a synthetic resin molding material containing 0.1 to 5.0 parts by weight of a polymerization initiator (d) is polymerized and cured while being shaped under pressure. Become.

In the synthetic resin molding material of the present invention having the above-mentioned constitution, and the method for producing a molded article by the synthetic resin molding material, the inorganic substance in the inorganic filler (b) and / or the inorganic filler-containing resin particles (c) is used. Aluminum hydroxide is suitable as the filler.

As in the case of compression molding of unsaturated polyester resins, in the compression molding of acrylic resins using acrylic unsaturated monomers, the preparation of the premix as a molding material is the most important matter. There is one. The premix using this acrylic unsaturated monomer cannot be easily thickened like the premix of unsaturated polyester resin, and various ideas for preparing a highly viscous premix. Is proposed.

For example, a syrup made of a crosslinked acrylic resin in which a vinyl monomer having a carboxyl group is partially copolymerized, an alkaline earth metal oxide such as MgO or Mg (OH) ₂ or a hydroxide is added. A method of obtaining a premix added as a thickener (Japanese Patent Publication No. 64-11652),
A method of obtaining a thickened premix by adding a polyisocyanate compound and an aluminum alcoholate to a syrup made of an acrylic resin partially copolymerized with a vinyl monomer having a hydroxyl group (Japanese Patent Publication No. 46530/1989). JP-A-5-124844. A polyisocyanate is added as a filler to an acrylic syrup containing a polymethylmethacrylate copolymer having a hydroxyl group to obtain a thickened premix.
(JP-A-2-160648), a method of obtaining a thickened premix by adding a polymethylmethacrylate resin powder to an acrylic syrup (JP-A-2-160648).
Etc.

However, in the above method, uniform stirring is difficult when preparing a high-viscosity premix,
Since it is difficult to control the temperature of the premix, abnormal polymerization is likely to occur, and it is difficult to control the quality such as the polymerization rate and the degree of polymerization. or,
When an acrylic premix filled with a high concentration of inorganic powder is prepared, there is a drawback that the transparency of the obtained molded article is lowered.

On the other hand, according to the synthetic resin molding material of the present invention, a highly viscous acrylic premix can be prepared easily and in a short time, and the inorganic powder is filled in a high concentration. Also, the transparency of the obtained molded product does not decrease.

According to the synthetic resin molding material of the present invention,
Even if a premix in a state close to powder is prepared by reducing the amount of the acrylic syrup (a) and increasing the blending amount of the inorganic filler (b) and the inorganic filler-containing resin particles (c), Uniform mixing and stirring of the premix can be easily performed. Furthermore, according to the method for producing a molded article of the present invention, a high quality acrylic resin molded article can be obtained.

In the synthetic resin molding material of the present invention having the above-mentioned constitution and the method for producing a molded article by the synthetic resin molding material, as the acrylic syrup (a) containing methyl methacrylate as a main component, a methyl methacrylate unit amount is used. For the body, syrup in which polymethylmethacrylate or a copolymer of methylmethacrylate and α, β-unsaturated compound such as vinyl acetate, styrene, methylacrylate, ethylmethacrylate, butylmethacrylate, cyclohexylmethacrylate is dissolved is used. It

The acrylic syrup (a) may contain a cross-linking agent in a proportion of 15% by weight or less of the composition components of the acrylic syrup (a). As the cross-linking agent at this time, for example, ethylene glycol dimethacrylate, 1,
3-Propylene glycol dimethacrylate, divinylbenzene, triallyl cyanurate, neopentyl glycol dimethacrylate, etc. can be used.

As the inorganic filler in the inorganic filler (b) and the inorganic filler-containing resin particles (c), calcium carbonate, magnesium hydroxide, aluminum hydroxide, silica, glass or the like can be used. However, aluminum hydroxide is most suitable. The surface of the inorganic filler may be treated with, for example, a silane coupling agent, a titanate coupling agent, stearic acid or the like.

The resin particles (c) containing an inorganic filler have a degree of swelling with respect to methyl methacrylate of 2.5 or less,
Moreover, the resin particles are insoluble in methyl methacrylate. The degree of swelling of the inorganic filler-containing resin particles (c) with respect to methyl methacrylate is the bulk volume when the inorganic filler-containing resin particles (c) are swollen by immersing the inorganic filler-containing resin particles (c) in a methyl methacrylate monomer at 25 ° C. for 5 hours. And the bulk volume of the inorganic filler-containing resin particles (c) before swelling.

The inorganic filler-containing resin particles (c) may be completely insoluble in methyl methacrylate, but in order to improve the physical properties and the like of the resulting acrylic resin molded product, the degree of swelling with respect to methyl methacrylate is 0. It is preferably 0.5 or more.

The resin particles (c) containing an inorganic filler have a degree of swelling with respect to methyl methacrylate of 2.5 or less,
Moreover, any one may be used as long as it is insoluble in methyl methacrylate, but since the affinity at the interface of the resin particles in the obtained acrylic resin molded article becomes high, methyl methacrylate resin particles are particularly preferable.

When the degree of swelling of the above-mentioned inorganic filler-containing resin particles (c) with respect to methyl methacrylate exceeds 2.5, (1) surface characteristics such as gloss of a molded product obtained from a synthetic resin molding material, molded product The transparency of (2)
Acrylic syrup (a) containing methyl methacrylate as a main component, inorganic filler (b), inorganic filler-containing resin particles (c), and polymerization initiator (d) are mixed and stirred to make a synthetic resin. It takes a lot of time and energy to prepare the molding material, and further, (3) the design characteristics of the acrylic resin molded product expressed by the inorganic filler-containing resin particles (c) are deteriorated. It causes harm.

The inorganic filler-containing resin particles (c) are excellent in surface gloss and transparency in order to further enhance the design characteristics of the acrylic resin molded product expressed by the inorganic filler-containing resin particles (c). It is preferable to use resin particles obtained by crushing acrylic resin-based artificial marble or polyester resin-based artificial marble.

In particular, the resin particles obtained by crushing an acrylic resin-based artificial marble have a swelling degree with respect to methyl methacrylate of 1.2 to 2.5, and are used as the inorganic filler-containing resin particles (c). The resin molded product obtained as described above is a molded product having a high-grade appearance and a transparent appearance, which expresses the designability of the inorganic filler-containing resin particles (c) as it is. Among them, an acrylic resin-based artificial marble obtained by the method described in Japanese Patent Publication No. 50-22586, which is an inorganic filler made of aluminum hydroxide 20-
Inorganic filler-containing resin particles (c) obtained by pulverizing those containing 85% by weight are suitable.

The particle size of the inorganic filler-containing resin particles (c) may be not more than the thickness of the obtained molded product, but from the viewpoint of the design characteristics of the obtained molded product, it should be at most half the thickness of the molded product. Preferably there is.

The synthetic resin molding material of the present invention comprises the acrylic syrup (a) containing methyl methacrylate as a main component in an amount of 10 to 60% by weight and the inorganic filler (b) in an amount of 0 to 8.
5% by weight, and the degree of swelling with methyl methacrylate is 2.
10 or less of 5 or less and 1 to 85% by weight of the inorganic filler-containing resin particles (c) insoluble in methyl methacrylate.
The amount of the acrylic syrup (a) containing methyl methacrylate as a main component is preferably 10 to 10% by weight, and a polymerization initiator is added thereto.
60% by weight and 0 to 85% by weight of the inorganic filler (b),
1 to 5 to 75% by weight of resin particles (c) containing an inorganic filler
The total amount of the inorganic filler (b) and the inorganic filler in the resin particles (c) containing the inorganic filler is 100% by weight of the above three components. It is less than 85% by weight of the total.

As the polymerization initiator (d), a polymerization initiator usually used for the polymerization of acrylic monomers can be used as it is, for example, di-3-methoxybutylperoxydicarbonate, diisopropylperoxy. Dicarbonate, dicyclohexyl peroxydicarbonate,
Di-secondary butyl peroxydicarbonate, di-normal propyl peroxydicarbonate, 2,4,4
-Trimethylpentyl peroxyphenoxyacetate, isobutyl peroxide, methyl ethyl ketone peroxide, lauroyl peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone ketone peroxide, dicumyl peroxide, tertiary butyl peroxyacetate, etc. Oxide-based polymerization initiator, azobisisobutyronitrile, 1,1'-azobis-1-cyclohexanecarbonitrile, 2-carbamoylazoisobutyronitrile, 2,2'-azobis-2,4,4 An azo polymerization initiator such as trimethylpentane may be used alone or in combination of two or more.

In preparing the synthetic resin molding material of the present invention, the acrylic syrup (a) containing methyl methacrylate as a main component, the inorganic filler (b), and the inorganic filler-containing resin particles (c). In addition to the polymerization initiator (d), if necessary, a reinforcing material, a release agent, a pigment, a stabilizer,
It goes without saying that a polymerization regulator, an organic filler, etc. may be added.

When preparing the synthetic resin molding material of the present invention, the inorganic filler (b), the inorganic filler-containing resin particles (c), and the polymerization to the acrylic syrup (a) containing methyl methacrylate as the main component are prepared. The order of addition and mixing of the initiator (d) and the like is not particularly specified, but a specified amount of the inorganic filler (b) and the inorganic filler-containing resin particles (c) are added to the acrylic syrup (a) containing methyl methacrylate as a main component. It is preferable to prepare a synthetic resin molding material having a viscosity of 10,000 to 1,000,000 poise by adding the polymerization initiator (d) and the polymerization initiator (d).

The synthetic resin molding material of the present invention having the above constitution is called a premix having a sufficiently high viscosity, and can be applied to compression molding, injection molding, transfer molding and the like.

For compression molding, for example, a pressure of 10 to 500 kg
/ Cm ² , preferably 50 to 150 kg / cm ² , heating temperature 80 to 120 ° C., preferably 90 to 110 ° C., compression molding time 2 to 10 minutes, preferably 3 to 7 minutes.

[0037]

EXAMPLES The specific constitution of the synthetic resin molding material of the present invention and the method for producing a molded product from the synthetic resin molding material will be described below based on examples.

Example 1 Acrylic syrup [manufactured by Mitsubishi Rayon Co., Ltd.] 27.1
Acrylic syrup (a) containing methyl methacrylate as a main component, to which 0.4 part by weight of acrylic ester ED [trade name of Mitsubishi Rayon Co., Ltd.] was added as a cross-linking agent.
¹ ) 27.5 parts by weight, aluminum hydroxide [Japan Light Metal
62.5 parts by weight of an inorganic filler (b ¹ ) made of Co., Ltd.], and an inorganic filler made of particles obtained by crushing Corian [M-Arcie-Dupont (registered trademark)] which is an artificial marble. 10.0 parts by weight of contained resin particles (c ¹ ) and lauroyl peroxide (d ¹ ) as a polymerization initiator
Add 1.5 parts by weight to a kneader set at room temperature and
By mixing and stirring for 0 minutes, a freshly-molded dough-shaped synthetic resin molding material having a viscosity of 100,000 poise, which is an example product of the present invention, was obtained.

Resin particles (c ¹ ) containing the above inorganic filler
The resin constituting the is polymethylmethacrylate,
Inorganic filler is 65% by weight of the total resin particles (c ^1), degree of swelling methacrylate inorganic filler-containing resin particle (c ¹⁾ is 1.6, the particle size of about 1mm
˜100 μm, with an average particle size of 300 μm. Also, the viscosity of synthetic resin molding materials is
It is a numerical value measured by RGA-700 viscometer manufactured by Co., Ltd.

Example 2 The synthetic resin molding material (premix) of Example 1 was used as a 300 ton press using a 700.times.400 mm square flat plate molding die having a chrome-plated surface [Kawasaki Yuko Co., Ltd.].
Manufacturing], mold temperature 100 ° C, compression molding pressure 80k
It was subjected to compression molding at g / cm ^{2 for} 3 minutes to form a plate-like body made of acrylic resin artificial marble with a thickness of 2 mm.

The artificial marble composed of the obtained plate-like body includes
A clear stone tone was revealed by the inorganic filler-containing resin particles (c ¹ ), and the surface of the mold was faithfully transferred, resulting in a molded product having a good appearance and transparency.

Example 3 The synthetic resin molding material (premix) of Example 1 was used as a 200 ton injection molding machine using a metal mold for automobile headlamp reflecting mirror having a chrome-plated surface [Japan Steel Works, Ltd.].
Manufacturing pressure], injection pressure 60 kg / cm ² , mold clamping pressure 100
Ton, a vacuum degree of 650 mmHg, and a molding time of 3 minutes were subjected to injection molding to mold an automobile headlamp reflecting mirror made of an acrylic resin artificial marble having a thickness of 3 mm.

The automobile headlamp reflector made of the obtained acrylic resin artificial marble shows a clear stone tone due to the resin particles (c ¹ ) containing the inorganic filler, and the surface of the mold is faithful. It has been transferred to a molded product with a high gloss and transparency.

Example 4 The synthetic resin molding material (premix) of Example 1 was used in an office equipment molding die having a chrome-plated surface.
Ton transfer molding machine [Toho Press Mfg. Co., Ltd.]
Manufacturing pressure], injection pressure 30 kg / cm ² , mold clamping pressure 100
Then, it was subjected to transfer molding with a molding time of 3 minutes, and an office machine made of acrylic resin artificial marble having a thickness of 5 mm was molded.

In the office equipment made of the obtained acrylic resin artificial marble, a clear stone tone was revealed by the resin particles (c ¹ ) containing the inorganic filler, and the surface of the mold was faithfully transferred. The resulting molded product has a high gloss and transparency.

Example 5 Acrylic syrup [manufactured by Mitsubishi Rayon Co., Ltd.] 22.6
Acrylic ester ED [Mitsubishi Rayon
Co., Ltd .: trade name] Acrylic syrup (a ² ) 2 containing 0.4 parts by weight of methyl methacrylate as a main component
3.0 parts by weight, aluminum hydroxide [Nippon Light Metals Co., Ltd.
43.0 parts by weight of an inorganic filler (b ¹ ) composed of an inorganic filler, and a resin particle containing an inorganic filler composed of particles obtained by pulverizing an artificial marble of Corian [registered trademark] of AMC-DuPont Co., Ltd.]. Examples of the present invention were prepared by mixing 34.0 parts by weight of (c ¹ ) and 1.5 parts by weight of the polymerization initiator lauroyl peroxide (d ¹ ) in a Henschel mixer set at room temperature for 10 minutes and stirring. Thus, a powdery synthetic resin molding material having no stickiness and good handleability was obtained.

Example 6 The synthetic resin molding material (premix) of Example 5 was used in a box molding die having a chrome-plated surface.
Using a ton press (manufactured by Toho Press Mfg. Co., Ltd.), mold temperature 100 ° C, compression molding pressure 100 kg / cm
² , compression molding time 3 minutes, the thickness of 3mm
A box made of acrylic resin-based artificial marble was molded.

In the box made of the obtained acrylic resin-based artificial marble, a clear stone tone was revealed by the resin particles (c ¹ ) containing the inorganic filler, and the surface of the mold was faithfully transferred. The molded product had a good appearance, a high gloss, and a transparent feeling.

Comparative Example 1 Instead of the inorganic filler-containing resin particles (c ¹ ) of Example 1, a mixed solution of styrene and divinylbenzene was suspension polymerized to obtain an average particle size of 32 μm and a swelling degree to methyl methacrylate of 7 Example 1 using all the corresponding components of Example 1 except using the crosslinkable polystyrene particles of
A synthetic resin molding material for comparison was obtained in the same manner as described in 1.

This synthetic resin molding material (premix)
Was subjected to compression molding by the same method as in Example 2, and the obtained molded product had no clear decorative effect due to the crosslinkable polystyrene particles, and had a clear decorative effect due to the crosslinkable polystyrene particles. I couldn't get anything.

Comparative Example 2 In place of the inorganic filler-containing resin particles (c ¹ ) of Example 1, trially produced crushed particles of acrylic resin-based artificial marble (swelling degree to methyl methacrylate 9.7) were used. A synthetic resin molding material for comparison was obtained in the same manner as in Example 1, except that all the corresponding components of Example 1 were used.

This synthetic resin molding material (premix)
Was subjected to compression molding by the same method as in Example 2, and the obtained molded product had streaky stains generated by the crushed particles of the acrylic resin-based artificial marble rubbing against the mold, and the appearance No good molded product was obtained.

[0053]

Industrial Applicability According to the synthetic resin molding material of the present invention, it can be subjected to heat compression molding which is more productive than the casting method, the preparation operation is easy, and the preparation time is short. A synthetic resin molding material which is a molding material called a premix having properties such as capable of producing a molded article in which the gloss and transparency of the resin particles mixed in the premix are not deteriorated. become.

According to the method for producing a molded article of the present invention,
Resin particles containing an inorganic filler compounded in a molding material (c)
It is possible to produce with high efficiency a high quality molded product in which a clear stone tone is revealed and the gloss and transparency of the inorganic filler-containing resin particles (c) are not deteriorated.

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[Procedure amendment]

[Submission date] July 27, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012]

The present inventors have SUMMARY OF THE INVENTION, in the molding material called premix, a less than 3 degree of swelling of methyl methacrylate, yet insoluble inorganic filler-containing resin particles in methyl methacrylate By using, as a result of confirming that it is possible to easily prepare a premix in a short time, and yet it is possible to produce a heat compression molded product without lowering the gloss or transparency of the resin particles,
The present invention has been completed.

Claims (4)

[Claims] 1. An acrylic syrup (a) containing methyl methacrylate as a main component in an amount of 10 to 60% by weight, an inorganic filler (b) in an amount of 0 to 85% by weight, and a degree of swelling with respect to methyl methacrylate of 2.5 or less. And resin particles (c) 1-8 containing an inorganic filler that are insoluble in methyl methacrylate
A synthetic resin molding material comprising 0.1 to 5.0 parts by weight of a polymerization initiator (d) in 100 parts by weight of a mixture with 5% by weight. 2. The synthetic resin molding material according to claim 1, wherein the inorganic filler in the inorganic filler (b) and / or the inorganic filler-containing resin particles (c) is aluminum hydroxide. 3. The synthetic resin molding material according to claim 1 or 2, wherein the inorganic filler-containing resin particles (c) contain 20 to 80% by weight of aluminum hydroxide. 4. A method for producing a molded article, which comprises polymerizing and curing the synthetic resin molding material according to claim 1, 2 or 3 while shaping it under pressure.