JPH0146530B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses a thermosetting acrylic syrup that has excellent weather resistance, moldability, low smoke generation, and colorability.
SMC (Sheet Molding Compound) and BMC
(Bulk Molding Compound) manufacturing method.

(Prior art and its issues) Due to its features such as light weight, high strength, good design, and corrosion resistance, fiber reinforced plastics (FRP) are used for fishing boats,
It is widely used in various applications such as boats, yachts, septic tanks, water tanks, bathtubs, corrugated plates, corrosion-resistant equipment, industrial parts, automobiles, and electrical parts. Among FRP,
Molding materials that can be compression molded such as SMC, compression molded such as BMC, injection molded, or transfer molded are easy to mold in one piece, have excellent design, are fast molding, and can achieve stable dimensional accuracy and quality. On the other hand, it can also contribute to improving the molding work environment, which has become harsher in recent years, so conventional hand-lay-up molding materials and It has replaced spray-up molding materials.

There is a big difference in form between SMC and BMC, whether it is sheet-like or bulk-like, but other than that, there are generally differences in the length of the fiber reinforcement and the amount of filler, but the basic content is Includes unsaturated polyester resin (), thickeners such as MgO or Mg(OH) ₂ (), organic peroxides (), fiber reinforcement (), fillers () and optionally low shrinkage agents. It is a sheet or bulk molding material made by wrapping a compound consisting of a thermoplastic polymer, a mold release agent, a coloring agent, etc. in a polyethylene film, etc., and aging it to remove stickiness and improve moldability.

However, conventional SMC and BMC molded products
The weather resistance, especially the gloss of the molded product, decreases due to outdoor exposure, resulting in chalking (chalking), and the glass fiber reinforcement material becomes exposed, which significantly impairs the appearance. This is due to the fact that the unsaturated polyester resin that is the matrix of SMC and BMC does not necessarily have good weather resistance, and the thickeners MgO and Mg added to improve moldability.
It is also thought that (OH) ₂ and the like are strongly alkaline and water-absorbing, so they accelerate the deterioration of unsaturated polyester resins. In order to improve this drawback, it is possible to use acrylic resin, which is a typical weather-resistant resin. However, standard methyl methacrylate polymer derived from methyl methacrylate is a thermoplastic resin, and although it can be applied to stampable sheets, which have been attracting attention in recent years, it is not suitable as a matrix for SMC or BMC. .

Acrylic syrup, which is usually obtained by dissolving methyl methacrylate polymer in methyl methacrylate, is thermosetting by copolymerizing crosslinking monomers such as ethylene glycol di(meth)acrylate and trimethylolpropane trimethacrylate into the polymer. However, the diluent monomer methyl methacrylate has a low boiling point of 100°C, easily foams, and cannot be made into SMC or BMC because it cannot be thickened with MgO or the like.

The present inventors have conducted extensive research to improve these drawbacks, and as a result, have come up with the manufacturing method of the present invention.

That is, the present invention relates to a cross-linked acrylic syrup () which is at least partially copolymerized with a vinyl monomer having a hydroxyl group, one type of compound selected from organic polyisocyanate, aluminum alcoholate or aluminum acetylacetonate (), polymerized Sheet-like or A method for producing bulk molding materials.

In order to produce the cross-linked acrylic syrup used in the present invention, some modifications may be made to the production of conventional cross-linked acrylic syrup.
The simplest method is to copolymerize a vinyl monomer having a hydroxyl group when producing the acrylic polymer as the main component by vinyl polymerization.

As is already known, crosslinked acrylic syrup can be obtained by partially polymerizing an acrylic monomer (a) such as methyl methacrylate and optionally another vinyl monomer (b) such as styrene; Alternatively, a partial or complete polymer of acrylic monomer (a) alone or a mixture of acrylic monomer (a) and other vinyl monomer (b) may be used as a liquid acrylic monomer alone or with a liquid acrylic monomer and another liquid vinyl monomer. In the so-called acrylic syrup obtained by diluting with a mixture of
A crosslinking agent (c) having two or more unsaturated bonds capable of vinyl polymerization is copolymerized or coexisting as is.

The cross-linked acrylic syrup (2) used in the present invention has a hydroxyl group added to the acrylic polymer contained therein. For example, a vinyl monomer (d) having a hydroxyl group can be copolymerized when producing the cross-linked acrylic syrup. Manufactured by.

Specific examples of the acrylic monomer (a) include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, acrylic amide, cyclohexyl acrylate, methyl methacrylate, Examples include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, and glycidyl methacrylate, with methyl methacrylate being particularly preferred.

Examples of other vinyl monomers (b) include styrene, vinyltoluene, α-methylstyrene, chlorostyrene, and vinyl acetate.
Naturally, in order to produce acrylic syrup, it is necessary to select liquid monomers, such as methyl methacrylate and styrene, for at least some of the monomers (a) and (b).

Examples of the crosslinking agent (c) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neobentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythrittetra(meth)acrylate. acrylate, divinylbenzene, diallyl phthalate, diallyl isophthalate, triallyl cyanurate, triallyl isocyanurate, unsaturated polyester resin, vinyl ester resin, adduct of 2-hydroxyethyl (meth)acrylate and polyisocyanate,
Examples include adducts of 2-hydroxypropyl (meth)acrylate and polyisocyanate.

In addition, examples of the vinyl monomer (d) having a characteristic hydroxyl group in the present invention include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, allyl Alcohol, ethylene glycol monoallyl ether, propylene glycol monoallyl ether, trimethylolpropane diallyl ether,
Examples include pentaerythritol triallyl ether.

In addition, examples of the monomer (e) that can be used in combination with this monomer include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid,
Fumaric acid monoalkyl esters such as monomethyl fumarate and monoethyl, monomethyl maleate,
Examples thereof include maleic acid monoalkyl esters such as monoethyl, itaconic acid monoalkyl esters such as monomethyl itaconate and monoethyl, and citraconic acid monoalkyl esters such as monomethyl citraconate and monoethyl.

In the crosslinked acrylic syrup of the present invention,
The total weight of the acrylic monomer (a), the hydroxyl group-containing monomer (d), and the carboxyl group-containing monomer (e) should account for at least 50% of the syrup. (e)
do not necessarily need to coexist.

In addition, the amount of crosslinking agent (c) is 1 to 50% by weight of the syrup.
is appropriate.

The content of partial or complete polymer (solid content) in the syrup used in the present invention is not particularly limited, but from the viewpoint of workability, the viscosity (at 25°C)
The content is preferably 0.5 to 100 poise.

When the hydroxyl group-containing monomer (d) is used for the subsequent compound preparation, it is preferable to use an acrylic syrup having a hydroxy value of 5 to 100.

Examples of the polyisocyanate compound () to be added to the hydroxyl group-containing acrylic syrup () include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and adducts thereof that leave free NCO groups. On the other hand, examples of aluminum alcoholate or its acetylacetonate include aluminum isopropoxide or its acetylacetonate, aluminum butoxide or its acetylacetonate, and all of these are resistant to reaction with hydroxyl groups.
When used in an amount of 0.5 to 3 equivalents, SMC or BMC that is not sticky and has excellent flow characteristics during molding can be obtained.

As a polymerization initiator () as a curing agent,
organic peroxides, such as benzoyl peroxide,
lauroyl peroxide, methyl ethyl ketone peroxide, tertiary butyl perbenzoate, tertiary butyl peroctoate, kyumene hydroperoxide, or azo initiators such as 2,2'-azobisisobutyronitrile, 2-phenylazo- 2,4-dimethyl-4-
Methoxyvaleronitrile is used. Such a polymerization initiator () is generally used for syrup,
Add 0.5 to 3% by weight.

In addition, as a fiber reinforcing agent (), glass fiber (chopped strand, chopped roving,
Any type of material used for SMC and BMC such as unidirectional roving, chopped strand mat, etc.), boron fiber, carbon fiber, polyamide fiber (nylon fiber, aramid fiber), vinylon fiber, polyester fiber, natural Fiber (Jisal hemp)
etc. In the case of SMC, the fiber reinforcing material is generally mixed in an amount of about 20 to 70% by weight, preferably 25 to 35% by weight, based on the compound, and in the case of BMC, it is generally mixed in an amount of 10 to 50% by weight, preferably 10% by weight, based on the compound. Add approximately 30% by weight.

Other fillers may be used as necessary, such as calcium carbonate, hydrated alumina, clay, talc,
Milled fiber, silica sand powder, porcelain powder, etc., release agents such as zinc stearate, aluminum stearate, calcium stearate, barium stearate, stearic acid, stearic acid amide, alkyl phosphate, silicone oil, etc., colorants, etc. For example, inorganic pigments, organic pigments,
A dye or the like may be added.

For SMC, for example, acrylic syrup (), one compound selected from organic polyisocyanate, aluminum alcoholate, or aluminum acetylacetonate (), a polymerization initiator (), and other additives () as necessary are uniformly added to the SMC according to a conventional method. or by spreading the homogeneous mixture into a sheet and using this sheet to impregnate the fiber reinforcement ().
Either make a sheet-like compound by sandwiching it, or mix (), (), (), () and () as necessary and spread it into a sheet-like compound to make a sheet-like compound. The compound is sandwiched with a release film such as polyethylene or polyester, and is usually heated at 15 to 50℃ for 12 hours.
Made by aging for ~72 hours. In this case, it is not always necessary to sand-chip with the release film after making the sheet-like compound; instead, the sheet-like fiber reinforcement material () is placed on top of the release film, and then the acrylic syrup is applied on top of it. Alternatively, a method may be used in which the material is impregnated with a mixture of the above and then wrapped with a releasable film. In addition, the special public interest public
As described in Publication No. 14108, a plurality of unidirectional glass rovings are pulled out in a line and a compound of acrylic syrup is wrapped around them to continuously form a sheet-like compound, which is then sandwiched with a release film. You can also create an SMC using the following method.

BMC is easily manufactured by uniformly mixing acrylic syrup () and other ingredients () to () and then wrapping the mixture in a releasable film. In this case, it is appropriate that the fiber reinforcing material () be in the form of short fibers.

The SMC and BMC thus obtained are compression molded,
Usually 100 by injection molding, transfer molding, etc.
It can be molded into various molded products at a mold temperature of ~170℃.

According to the manufacturing method of the present invention, foaming is less likely to occur during manufacturing compared to conventional glass fiber reinforced acrylic resins, and the resulting SMC or BMC has fast curing properties.

Furthermore, molded products made from SMC or BMC manufactured by the present invention have features that are far superior in weather resistance, low smoke emission, colorability, gloss, etc., than SMC or BMC molded products made using ordinary unsaturated polyester resins. Chairs, benches, tables, tanks, automobile exterior parts, electrical parts, pleasure boats, roofing materials, play equipment, wall materials, traffic signs, advertising boards, electrical parts (lighting equipment) that are particularly susceptible to outdoor exposure. It is used in a wide range of applications, including railway car parts, displays, etc.

In addition, when molding the SMC or BMC of the present invention, for example, when compression molding, the method of charging the mold is devised, and the SMC or BMC of the present invention is charged on the outer surface, and the normal one is placed on the center or lower part. By charging SMC and BMC using unsaturated polyester resin, it is possible to reduce the amount of expensive acrylic SMC and BMC used and to obtain molded products with excellent weather resistance.

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that "parts" are based on weight.

Example 1 3200 g of methyl methacrylate, 400 g of 2-hydroxyethyl methacrylate, 400 g of ethylene glycol dimethacrylate, 16 g of n-dodecylmercaptan, and 2,2'-azobis were placed in a reaction vessel equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube. 0.4g of isobutyronitrile was charged, reacted at 100℃, and when the viscosity reached 23 poise (25℃), hydroquinone
500 ppm was added, and the mixture was quickly cooled to room temperature to stop polymerization.

100 parts of the obtained thermosetting acrylic syrup, 5 parts of hexamethylene diisocyanate, 0.2 parts of tin octoate (28%), 1 part of tertiary-butyl bar octoate, 1 part of tertiary-butyl perbenzoate, Polyton Blue-J-831W (Coloring agent manufactured by Dainippon Ink Chemical Industries), 4 parts of zinc stearate, 250 parts of calcium carbonate, and 50 parts of 6mm chop roving were kneaded in a kneader, the resulting compound was wrapped in polyethylene film, and kept at room temperature. After leaving it for 24 hours, a less sticky BMC was obtained.
This BMC was molded at a mold temperature of 150° C. and a pressure of 80 kg/cm ² for 7 minutes to obtain a flat plate with a thickness of 5 mm. The bending strength of this molded plate according to JIS: K6911 is 13.5
Kg/mm ² , tensile strength was 5.2 Kg/mm ² , flame resistance was self-extinguishing, and almost no smoke was generated.

In addition, when we conducted a 500-hour accelerated weather resistance test using a Sunshine Inducycle Weather-Ometer, there was almost no discoloration or yoking.
Moreover, it exhibited almost the same gloss as when molded.
This molded board is suitable for benches, chairs, etc. left outdoors.
Ideal for roofing materials, etc.

On the other hand, a BMC molded plate obtained in the same manner except for using unsaturated polyester resin exhibits self-extinguishing properties, but generates a lot of black soot during combustion, and white yoking occurs in accelerated weathering tests. However, it had lost its luster.

Example 2 2400 g of methyl methacrylate, 800 g of styrene, 400 g of 2-hydroxyethyl methacrylate, 400 g of ethylene glycol dimethacrylate, and 16 g of n-dodecyl mercaptan were charged into the same reactor as in Example 1, and polymerized at 100°C to obtain a viscosity (25 ℃)
Polymerization was continued until 5 poise was obtained. Immediately, 100 ppm of hydroquinone was added, and the mixture was quickly cooled to below 15°C to inhibit polymerization.

Mix 100 parts of the obtained syrup, 3 parts of acetylacetonate of aluminum isopropoxide, 1 part of tertiary butyl bar octoate, 0.8 part of tertiary butyl perpivalate, and 0.2 part of Zeretsu UN (mold release agent manufactured by Dupont). Then, spread it on a polyethylene film and evenly sprinkle 43 parts of 50 mm C glass chops and rovings (refractive index η _D ²⁵ = 1.519), and cover it with another polyethylene film so that the thickness is about 2 mm. Impregnation and defoaming were carried out using a suitable defoaming roller. This sheet-like material is heated at 25℃.
After leaving it for 10 hours, a less sticky SMC was obtained.
This SMC was suitably cut, stacked, and pressed at a mold temperature of 120° C. and a pressure of 30 kg/cm ² for 10 minutes to obtain a transparent flat plate with a thickness of 3 mm.

When we measured the bending strength and tensile strength of this flat plate in accordance with JIS: K-6919, the strength was 19.6.
The values of Kg/mm ² and 11.4Kg/mm ² were obtained. Also, test time
An accelerated weathering test was carried out in the same manner as in Example 1, except that the test was carried out for 1000 hours. There was almost no yellowing or exposure of the glass fibers, and the total light transmittance measured by a haze meter was the same before and after the weathering test. 87% and 85 respectively.
% and showed excellent weather resistance. This molded board is ideal as a building material for daylighting, a material for solar water heaters, and a material for greenhouses.

On the other hand, when a molded plate obtained in the same manner except for using an unsaturated polyester resin was subjected to a weather resistance test, it was found to be significantly discolored, the glass fibers were exposed and whitened, and the total light transmittance was It showed 85% and 65% before and after the weather resistance test, respectively.

Comparative Example 1 3600 g of methyl methacrylate and ethylene glycol dimethacrylate were placed in the same reactor as in Example 1.
400g, n-dodecyl mercaptan 16g, 2,
Prepare 0.4g of 2'-azoisobutyronitrile, 100
The reaction was carried out at °C, and when the viscosity reached 25 poise (25 °C), 500 ppm of hydroquinone was added, and the polymerization was immediately cooled to room temperature to stop the polymerization.

100 parts of the obtained thermosetting acrylic syrup, 1 part of tertiary-butyl peroctoate, 1 part of tertiary-butyl perbenzoate, 5 parts of Polyton Blue J-831W, 4 parts of zinc stearate, 250 parts of calcium carbonate, 6 mm tip. droving 50
The mixture was kneaded using a kneader, and the resulting compound was wrapped in polyethylene film to create a BMC.
This BMC remained extremely sticky, and when the film was removed during molding, the compound adhered to the film, making it extremely difficult to handle. this
BMC was molded at a mold temperature of 150° C. for 7 minutes at a pressure of 80 kg/cm ² to obtain a flat plate with a thickness of 5 mm.

However, blisters and uneven coloring were observed on the surface of the molded product, and many air bubbles remained inside the product. Also, the cracks in the measured strength were large.

Claims (1)

[Claims] 1. A crosslinked acrylic syrup () obtained by at least partially copolymerizing a vinyl monomer having a hydroxyl group, one compound selected from the group consisting of an organic polyisocyanate, an aluminum alcoholate, and an acetylacetonate of an aluminum alcoholate (), polymerization A sheet-shaped or A method for producing bulk molding materials.