JPH0341096B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a premix molding material that provides a cured product with excellent heat resistance and hot water resistance, and is an inexpensive material that can be used in all fields such as artificial marble, extruded buttons, housing equipment, vehicle parts, and electrical parts. This invention relates to premix molding materials that are easy to handle. (Prior Art) Conventionally, molding materials made by kneading thermosetting resins such as unsaturated polyester resins and epoxy resins with fillers and reinforcing short fibers have been known as premixes. Premixes are mainly subjected to press molding and injection molding, and the resulting molded products are used for electrical parts, vehicle parts, and the like. (Problems to be solved by the invention) However, these conventional premixes have a high viscosity during kneading during the manufacturing process, which limits the amount and size of the filler that can be used. Cannot be used in large quantities. In addition, because the adhesion between the resin and the filler and reinforcing short fibers is poor, and the resin itself has poor water resistance, molded products obtained from conventional premixes can be immersed in boiling water for a short period of time. The problem was that the surface was corroded, causing whitening and loss of gloss. Furthermore, this molded product also had a problem with heat resistance, being prone to yellowing when exposed to high temperatures of 180° C. or higher, and contamination was noticeable even in the lighted cigarette test. Therefore, products molded from these conventional premixes have insufficient performance for applications that require heat resistance and hot water resistance, such as bathtubs, kitchen counters, button fabrics, electrical parts, and vehicle parts, and cannot be used. Currently, it is either limited or not used at all. The purpose of the present invention is to improve the current state of the art, and to provide a cured product that has excellent heat resistance, hot water resistance, and high flame retardancy, and is suitable for extrusion molding, press molding, and injection molding. The company provides premix molding materials. (Means and effects for solving the problem) As a result of various studies by the present inventors, a curable composition obtained by kneading a specific amount of a specific filler with a specific monomer was used as a reinforcing short film. The present invention was completed by discovering that premixes impregnated and mixed with fibers can effectively achieve the purpose. That is, in the present invention, 250 to 800 parts by weight of an inorganic filler having an average particle size of 5 microns or less is added to 100 parts by weight of a monomer mixture containing an aliphatic polyfunctional (meth)acrylate and an aromatic vinyl compound as essential components. A curable composition () obtained by kneading parts by weight and a curing agent,
This invention relates to a premix molding material that is impregnated with and mixed with reinforcing short fibers to give a cured product with excellent heat resistance and hot water resistance. The premix molding material of the present invention is a highly viscous, bread-like, non-sticky lump with excellent handling properties, and can be easily heat-molded into a product with a high filler content. Moreover, this product does not require a gel coat and does not change its appearance even when immersed in boiling water for a long time. The aliphatic polyfunctional (meth)acrylates used in the present invention include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, Glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)
Contains acrylate, etc. Aromatic vinyl compounds include styrene, α-
Examples include methylstyrene, p-methylstyrene, and divinylbenzene. The ratio of aliphatic polyfunctional (meth)acrylate and aromatic vinyl compound is 20 to 80% by weight for the former and 80% for the latter.
The ratio may be 20% by weight, but the more preferred is 30-70% by weight for the former and 70-30% by weight for the latter. still,
The monomer mixture in the present invention has the above two types as essential components, and a portion of the monomer mixture includes (meth)acrylic acid and salts thereof, methyl (meth)acrylate, isobutyl (meth)acrylate, Various (meth)acrylate monomers such as pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, unsaturated polyester oligomers, fumaric acid esters, Other monomers and oligomers such as maleimides can also be used.
However, if these other monomers or oligomers are used too much, it may be difficult to obtain a product with a high filler content, or the product may have poor heat resistance and hot water resistance. Furthermore, if the boiling point of other monomers used is low, foaming may occur during molding, resulting in poor appearance of the product. Furthermore, a thermoplastic polymer may be added to the monomer mixture in order to reduce shrinkage during molding and curing, prevent cracks and improve surface smoothness of the product. Examples of thermoplastic polymers include (meth)acrylic polymers such as polymethyl methacrylate, (meth)acrylic-styrene copolymers, polystyrene, polyvinyl acetate, styrene-vinyl acetate copolymers, polyvinyl chloride, polybutadiene, and polyethylene. Conventionally known low-shrinkage polymers such as , polycaprolactam, and saturated polyester can be used alone or in combination. When thermoplastic polymers for low shrinkage are blended in large amounts, they increase the viscosity of the monomer mixture, making it difficult to obtain premix molding materials with high filler content, or causing poor product transparency and heat resistance. Sometimes you only get what you get. Therefore, it is best to use the thermoplastic polymer for low shrinkage in as small a quantity as possible, preferably within a range of 40 parts by weight or less, more preferably from 5 to 30 parts by weight, per 100 parts by weight of the monomer mixture. is desirable. The inorganic filler used in the present invention may have an average particle size of 5 microns or less, and may include calcium carbonate, talc, clay, silica, alumina, quartz, calcium silicate, aluminum hydroxide,
Commonly used hydrates of metal oxides such as magnesium hydroxide and calcium hydroxide can be used. Among these inorganic fillers with an average particle size of 5 microns or less, fill as high as possible,
It is also desirable to have a material that can be safely dispersed even at low viscosity, and hydrates of metal oxides are particularly preferred. Furthermore, hydrates of metal oxides are ideal in terms of flame retardancy. It is preferable to use a silane coupling agent when kneading the monomer mixture and the inorganic filler because it improves the water resistance of the product obtained by curing the resulting premix molding material. Examples of the silane coupling agent include γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, and vinyltriacetoxysilane. The amount of the inorganic filler used is in the range of 250 to 800 parts by weight per 100 parts by weight of the monomer mixture.
If the amount is less than 250 parts by weight, it will not be possible to obtain a premix molding material in the form of fresh bread that provides a cured product with excellent heat resistance, hot water resistance, and flame retardancy. In addition, if the amount exceeds 800 parts by weight, the viscosity of the curable composition () obtained by kneading becomes too high, resulting in insufficient impregnation and mixing into the reinforcing short fibers, resulting in poor hot water resistance and mechanical strength. It cannot be used as a premix molding material that gives an excellent cured product. When kneading the monomer mixture and the inorganic filler,
By blending a curing agent, a curable composition () used for impregnating and mixing reinforcing short fibers in the present invention can be obtained. Examples of the curing agent used in the present invention include organic peroxides commonly used in heat and pressure molding, such as benzoyl peroxide, t-butyl peroxyoctoate, t-butyl peroxybenzoate, and dicumyl peroxide. There are salts of organic amines and polyvalent metals that are accelerators used in combination with these substances. The curing agent is generally used in an amount corresponding to 0.5 to 3.0% based on the weight of the monomer mixture. In addition, in order to obtain the curable composition (2), in addition to inorganic fillers and curing agents with an average particle size of 5 microns or less, various fillers and zinc stearate may be used in amounts that do not impair the effects of the present invention, if necessary. A release agent such as a thixotropic agent, a plasticizer, a flame retardant, a coloring agent, etc. may be added. The premix molding material of the present invention is obtained by impregnating and mixing the curable composition into short reinforcing fibers. For example, it is possible to impregnate and mix reinforcing short fibers after preparing the curable composition (), or to add reinforcing short fibers when kneading the inorganic filler and curing agent into the monomer mixture. Alternatively, kneading and impregnation/mixing may be performed simultaneously to obtain a premix molding material. The former method is preferred from the standpoint of sufficiently kneading the inorganic filler and preventing unnecessary breakage of the reinforcing short fibers. The reinforcing short fibers used in the present invention include organic and inorganic fibers such as glass fibers, carbon fibers, polyamide fibers, and various whiskers, and relatively short fibers of 12 mm or less are used. The amount of reinforcing short fibers to be used is not particularly limited and can be determined as appropriate depending on the intended use of the cured product molded from the obtained premix molding material and the required mechanical strength. )
The proportion ranges from 5 to 50 parts by weight per 100 parts by weight. In order to specifically carry out the present invention, for example, firstly, 80 to 20% by weight of aliphatic polyfunctional (meth)acrylate, preferably 70 to 30% by weight, and 20 to 80% by weight, preferably 30 to 30% by weight of aromatic vinyl compound. Prepare a 70% by weight monomer mixture, and add 250 to 100 parts by weight of this mixture.
A curable composition () is prepared by kneading 800 parts by weight of an inorganic filler with an average particle size of 5 microns or less and a curing agent. At this time, the inorganic filler may be treated with a silane coupling agent in advance, or a silane coupling agent may be added to the monomer mixture in an amount of 0.1 to 2.0% based on the weight of the inorganic filler used. By using the inorganic filler after dissolving or dispersing it, the water resistance of the resulting product can be improved. As a kneading method, for example, a low-speed kneader such as a double-arm kneader, a high-speed stirrer such as a disper, a pigment dispersion machine for manufacturing paints, or a kneading roll may be used, but the curable composition () with a high filler content may be used. To obtain this, a low-speed kneader with strong kneading power is preferable. While continuously kneading the curable composition thus obtained, reinforcing short fibers are added and kneaded for 2 to 5 minutes, so that the reinforcing short fibers are impregnated and mixed with the composition, resulting in the premix molding material of the present invention. is obtained. The premix molding material of the present invention is a moderately sticky, non-tacky lump that is easy to handle, and can be molded and hardened by extrusion molding, press molding, injection molding, transfer molding, etc. Various heating/pressure molding methods can be used, such as
Molded products with excellent surface gloss can be obtained by heating and pressure molding in a mating mold heated to 100 to 160°C or in an extruder. (Effects of the invention) The premix molding material of the present invention can be easily produced using a low-speed kneader such as a kneader, has excellent handling workability and storage stability, and can last for 1 to 6 months depending on the selection of a curing agent. It has a life of .
The molded product obtained by curing this under heat and pressure has the advantages of excellent surface properties such as surface gloss and smoothness, good dimensional accuracy, little distortion, and less cracking. Furthermore, since the premix molding material of the present invention can be highly filled with inorganic fillers, it has a high degree of flame retardancy and a high heat distortion temperature, and can be immersed in boiling water.
Even after being immersed for over 500 hours, there is no change in appearance such as whitening, and the product can be made into a beautiful cured product that gives excellent results in tobacco resistance tests and other contamination tests. It can be used with confidence even in fields where it has been difficult to use due to the lack of. (Example) Examples will be explained in more detail below.
These do not represent all of the invention. Example 1 Trimethylolpropane trimethacrylate 25
A monomer mixture consisting of parts by weight and 75 parts by weight of styrene, 3 parts by weight of zinc stearate, 0.8 parts by weight of t-butyl peroxyoctoate (Perbutyl 0, manufactured by NOF Corporation) as a hardening agent, and silane coupling. 0.5 part by weight of agent [KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.] was mixed, and this mixed solution was charged into a double-arm kneader.
Next, 300 parts by weight of aluminum hydroxide [Hygilite H-320, average particle size 3.5 microns, manufactured by Showa Light Metal Co., Ltd.] was charged into a kneader with stirring to obtain a highly viscous curable composition. Subsequently, 45 parts by weight of glass fiber chops cut to a length of 6 mm were added and kneaded for 5 minutes to obtain a premix molding material of the present invention. This molding material was a non-adhesive lump that was easy to handle. This molding material was cut with a knife, weighed, and 2 kg was placed in a box-shaped mold (bottom 270 x 380 mm, depth 80 mm,
When pressed at a pressure of 60 tons and a press time of 5 minutes, a beautiful molded product was obtained with a milky white translucent surface and excellent surface gloss without cracks or distortion. The physical properties of this molded article are as shown in Table 1, and it was excellent in heat resistance, hot water resistance, and flame resistance. Examples 2 to 4 Premix molding materials of the present invention were prepared in the same manner as in Example 1 using the formulations shown in Table 1. All of the premix molding materials obtained were easy to handle. Next, when these molding materials were press-molded under the same conditions as in Example 1, beautiful molded products without cracks or distortions were obtained, and their physical properties were as shown in Table 1. It had excellent hot water resistance and flame resistance. Comparative Example 1 0.7 mol of maleic anhydride, 0.3 mol of isophthalic acid, 0.3 mol of neopentyl glycol, 0.6 mol of propylene glycol, and hydrogenated bisphenol.
45 parts by weight of unsaturated polyester obtained by condensing 0.15 mol of A was dissolved in 45 parts by weight of styrene, and 0.005 parts by weight of hydroquinone as a stabilizer was added to prepare an unsaturated polyester resin liquid. 10 parts by weight of polystyrene [S-Bright T-2 beads, manufactured by Sumitomo Chemical Industries, Ltd.] was dissolved in this resin liquid, and then 3 parts by weight of zinc stearate as an internal mold release agent and t as a curing agent.
- 0.8 parts by weight of butyl peroxyoctoate, silane coupling agent [KBM-503, Shin-Etsu Chemical Co., Ltd.]
0.5 parts by weight of aluminum hydroxide [Hygilite H-310, average particle size 17 microns, manufactured by Showa Light Metal Co., Ltd.] were sequentially added and kneaded in a kneader in the same manner as in Example 1 to form lumps. A sticky curable composition was obtained. Subsequently, 45 parts by weight of glass fiber chops cut to a length of 6 mm were added and kneaded for 5 minutes to obtain a premix molding material for comparison.
When 2 kg of this premix molding material was press-molded under the same conditions as in Example 1, a beautiful white molded product was obtained, but as shown in Table 1, the physical properties of the product were poor in heat resistance and hot water resistance. It was hot.

【table】

[Claims]

1 Monomer mixture containing an aliphatic polyfunctional (meth)acrylate and an aromatic vinyl compound as essential components 95~
For 100 parts by weight of a polymerizable syrup obtained by dissolving 5 to 50 parts by weight of a thickening thermoplastic polymer in 50 parts by weight, 200 to 800 parts by weight of an inorganic filler with an average particle size of 5 microns or less, and a thickener. A curable composition () obtained by kneading 0.1 to 10 parts by weight and a curing agent,
A fiber-reinforced thermosetting molding material made by impregnating reinforcing fibers. 2. The fiber-reinforced thermosetting molding material according to claim 1, wherein the thickening thermoplastic polymer has two or more carboxyl groups in the molecule, and the thickening agent is a metal oxide or metal hydroxide. . 3. The fiber-reinforced thermosetting molding material according to claim 1, wherein the thickening thermoplastic polymer has two or more hydroxyl groups in the molecule, and the thickening agent is a polyfunctional isocyanate compound. 4. The fiber-reinforced thermosetting molding material according to claim 1, wherein the inorganic filler is a hydrate of a metal oxide.