JP2007261117A - Sheet molding compound and molded product using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet molding compound (SMC) capable of favorably giving a strong SMC molded product in an SMC using an organic filler as a filler, and a molded product using the same. <P>SOLUTION: The SMC comprises at least a liquid phenolic resin, a glass fiber, a spherical hardened phenolic resin particle. The SMC molded product is obtained by molding the SMC. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet molding compound and a molded article using the same, and more particularly to an improvement of a sheet molding compound in which a molded article obtained by press molding the sheet molding is useful as a building material panel.

  Conventionally, as a sheet molding compound (hereinafter abbreviated as SMC), a thermosetting resin and an inorganic filler (inorganic filler), and if necessary, a paste in which a thickener, a curing agent, etc. are mixed ( Hereinafter, a molding material that has been semi-cured by impregnating a glass fiber with a glass fiber (hereinafter abbreviated as an SMC paste) to form a sheet and, if necessary, an aging treatment has been used. And the target molded product is manufactured from this SMC by performing the pressure molding which heats it with a metal mold | die. In addition, such molded products can be used as bathroom equipment, water storage tanks, septic tanks, septic tanks, outer wall materials, roofing materials, flooring materials, etc. using their excellent durability, water resistance, mechanical strength, flame resistance, and other characteristics. In particular, in a molded product such as a building material panel, in order to impart high flame retardancy and high designability, SMC has excellent fluidity during molding, It has been demanded.

  Moreover, as a thermosetting resin which is a main component of such SMC, an unsaturated polyester resin has been generally used. However, JP-A-3-189110 (Patent Document 1) and JP-A-2004-182964 are known. As disclosed in Japanese Patent Publication (Patent Document 2) and the like, it has been studied to use a phenol resin for the purpose of imparting higher flame retardancy. The use of the resol type phenolic resins shown has been preferred.

  By the way, conventionally, various inorganic fillers or organic fillers have been added for the purpose of improving various functions in a resin molded product or reducing the polymer content in the molded product. For example, to improve rubber elasticity, wear resistance, dimensional stability, coefficient of thermal expansion, electrical properties, heat resistance, chemical resistance, etc., calcium carbonate (limestone), glass, talc, silica, mica, metal Inorganic fillers such as powder and metal oxides are used, and organic fillers such as wood powder, pulp, paper, and woven fabric have been used to improve the mechanical strength of molded articles. .

  And also in the field of SMC, for example, in JP-A-2003-292648 (Patent Document 3), etc., together with unsaturated polyester resin, polymerizable monomer, low shrinkage agent, curing agent and thickener, An SMC obtained by impregnating a fiber base material with an unsaturated polyester resin composition containing an unsaturated polyester resin powder as a filler has been clarified, and Japanese Patent Application Laid-Open No. 2001-213882 (Patent Document 4). Etc., in SMC in which an unsaturated polyester resin composition containing an unsaturated polyester resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a thickener and a filler is impregnated into a fiber substrate, Examples of the filler include wood powder, polyethylene, polypropylene, polyvinyl chloride, acrylic resin, polyester resin and other thermoplastic resin powder, unsaturated It has been clarified that thermosetting resin powders such as reester resin, epoxy resin, phenol resin, melamine resin and urea resin, or organic powder such as used plastic bottles and credit cards are collected and pulverized. ing.

  However, thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, acrylic resin, and polyester resin as described above are highly flammable. Therefore, in SMC using such a resin as an organic filler, It had the problem that the flame retardance of the molded article obtained by shape | molding it fell.

  Under such circumstances, as a result of intensive studies by the present inventors, organic powder such as wood powder, thermoplastic resin powder, thermosetting resin powder or used PET bottles and credit cards, etc., organic powder such as pulverized products, etc. When used as a filler, these crushed fillers increase the viscosity of the SMC paste in which they are blended, so that the impregnation of such SMC paste into the glass fibers becomes poor. It has been clarified that a molded article using a simple SMC causes a problem that the strength of the molded article obtained from the SMC is lowered. In particular, when a natural organic filler such as wood flour is used as the filler, the water absorption of the phenol resin deprives the water of the phenol resin, thereby increasing the viscosity of the paste for SMC. The strength of the molded product obtained was further reduced. Furthermore, natural organic fillers such as wood powder are flammable, and molded articles obtained by molding SMC using such fillers are not suitable for use as building materials or vehicle interior materials. It was inherent.

Japanese Patent Laid-Open No. 3-189110 JP 2004-182964 A JP 2003-292648 A JP 2001-213882 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is that in SMC using an organic filler as a filler, a high-strength SMC molded product is used. An object of the present invention is to provide an SMC that can be advantageously provided and a molded article using the SMC.

  And as a result of intensive investigations to solve such problems, the present inventors have suppressed the viscosity of the SMC paste sufficiently low when spherical cured phenol resin particles are used as the organic filler. It was found that a molded article having a high strength can be obtained in a molded article obtained by molding SMC obtained by impregnating glass paste with such a paste.

  That is, the present invention has been completed based on such knowledge, and is characterized by containing at least a liquid phenol resin, glass fibers, and spherical cured phenol resin particles in order to solve the above-described problems. SMC is the gist of this.

  In addition, according to one of the desirable aspects of the SMC according to the present invention, the SMC further contains an inorganic filler.

  In addition, according to another desirable aspect of the SMC according to the present invention, the spherical cured phenol resin particles are used in a ratio of 10 to 70% by mass, and according to another desirable aspect, As the spherical cured phenol resin particles, those having an average particle diameter of 1 nm to 100 μm are advantageously used.

  In addition, in the present invention, a molded product obtained by press-molding SMC as described above, and a molded product in which the molded product is a building material panel are also targeted.

  Therefore, according to the SMC according to the present invention, by using the spherical cured phenol resin particles as a filler, the viscosity of the paste for SMC can be suppressed low, and the impregnation of the paste into the glass fiber becomes good, Therefore, the strength of the molded product obtained by molding such SMC is advantageously improved.

  By the way, the sheet molding compound (SMC) according to the present invention contains at least a liquid phenolic resin, glass fiber, and spherical cured phenolic resin particles. Any of them can be adopted. In the present invention, according to the method for producing a liquid phenol resin as disclosed in Japanese Patent Application Laid-Open No. 2002-338784, etc., the applicant of the present invention converts a phenol and an aldehyde into a reaction catalyst such as a base, an acid, Produced by reacting in the presence of a divalent metal salt and a combination thereof at a temperature from 40 ° C. to reflux temperature for 0.5 to 24 hours, and then neutralizing and concentrating as necessary. The liquid phenol resin to be used is preferably used. Examples of such a liquid phenolic resin include a resol resin obtained by conducting a base catalyzed reaction, an acid catalyzed reaction or a novolak type resole resin obtained by carrying out a base catalyzed reaction after the reaction, and a divalent metal salt catalyzed reaction. Benzyl ether type resole resins and mixtures thereof obtained by carrying out can be mentioned. Among them, resole resins and novolak type resole resins excellent in acid curability and thermosetting can be preferably used.

  Here, as the phenols used as the raw material of the liquid phenol resin, in addition to phenol, for example, alkylphenols such as cresol, xylenol, and p-tert-butylphenol, such as resorcinol, catechol, bisphenol F, bisphenol A, and the like And monohydric phenols and mixtures thereof. On the other hand, examples of the aldehyde used as the other raw material of the liquid phenol resin include formalin, paraformaldehyde, trioxane, polyoxymethylene, glyoxal, and furfural. It goes without saying that these raw materials are not limited to those exemplified, and can be used alone or in combination of two or more.

  In addition, there is no restriction | limiting in particular as a mixture ratio of such phenols and aldehydes, Generally 0.8-3.0 mol of aldehydes are mix | blended with respect to 1 mol of phenols. Will be.

  Of the reaction catalysts used in the reaction of such phenols with aldehydes, examples of the base catalyst include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, Examples of the acid catalyst include barium hydroxide, calcium hydroxide, magnesium oxide, and ammonia. Examples of the acid catalyst include hydrochloric acid, sulfuric acid, oxalic acid, p-toluenesulfonic acid, and the like. Examples of the valent metal salt catalyst include zinc acetate, lead acetate, and zinc borate.

  And in this invention, said liquid phenol resin will be mixed with glass fiber and a spherical hardening phenol resin particle, and the target SMC will be comprised, but there, this liquid phenol The resin is preferably used in the range of 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less in terms of resin solid content with respect to the total amount of SMC. If the amount is less than the above range, the strength of the obtained molded product may not be sufficient, and if it is more than the above range, other materials that can be contained in SMC, such as a spherical cured phenol resin, for example. This is because the effects of the blending of the particles may not be fully exhibited.

  Moreover, in SMC according to this invention, glass fiber is contained similarly to the past with said liquid phenol resin. In this case, as the glass fiber, any of the same conventional ones can be adopted, and examples thereof include E-glass, C-glass, T-glass, AR-glass, D-glass, etc. From the viewpoint of cost and the like, E-glass is preferably used. Moreover, generally, as a glass fiber used for SMC, a fiber treated with about 0.01% by mass to 0.2% by mass of a silane coupling agent with respect to the mass of the glass fiber is often used. Also in the present invention, glass fibers treated with such a silane coupling agent may be used.

  In addition, as a fiber diameter of this glass fiber, about 3-30 micrometers is generally preferable, More preferably, the thing of 6-15 micrometers is used. Further, the fiber length of the glass fiber is preferably 0.1 to 100 mm, more preferably 3 to 30 mm. When the fiber diameter of the glass fiber is smaller than the above range and the fiber length is shorter than the above range, the reinforcing effect by the glass fiber cannot be sufficiently exhibited, and as a result, such SMC is molded. There is a risk that the SMC molded product obtained in this manner does not have sufficient bending strength. On the other hand, when the fiber diameter of the glass fiber is larger than the above range and the fiber length is longer than the above range, the flowability of SMC using such glass fiber is lowered, and the moldability may be deteriorated. There is.

  Further, such glass fibers are preferably contained in the range of 3% by mass or more and 40% by mass or less, more preferably 8% by mass or more and 30% by mass or less, with respect to the total amount of SMC. . If the glass fiber content is less than this range, the strength of the molded product obtained by molding such SMC may not be sufficient. On the other hand, if it exceeds the above range, the moldability deteriorates. There is a fear.

  Further, in the SMC according to the present invention, in addition to the above-described liquid phenolic resin and glass fiber, spherical cured phenolic resin particles are further contained and configured. Thus, the viscosity of the paste for SMC can be advantageously reduced by blending and containing such spherical cured phenol resin particles as an organic filler in SMC. In other words, the fluidity of the SMC paste can be advantageously ensured, and therefore the wettability of the SMC paste to the glass fiber is improved, and the glass fiber is more effectively impregnated. Thus, it is possible to advantageously obtain an SMC in which the SMC paste and glass fiber are well blended. And, in the SMC molded product obtained by molding such SMC, it is possible to obtain the SMC molded product with further improved strength compared to the SMC molded product using the conventional filler. It is.

  Here, as the spherical cured phenol resin particles, those having an average particle diameter of preferably 1 nm to 100 μm, more preferably 1 μm to 80 μm are used. By using particles having an average particle diameter in such a range, the impregnation of the glass fiber with the SMC paste containing the spherical cured phenol resin becomes even better, as described above, The strength of the SMC molded product obtained by molding SMC can be further advantageously improved.

  As such spherical cured phenolic resin particles, any conventionally known particles can be used. In the present invention, the applicant of the present invention clearly disclosed in JP-A-3-7714. A first step of reacting a phenol with an aldehyde in the presence of an alkylbenzene sulfonic acid having an alkyl group having 10 or more carbon atoms and a protective colloid to form thermosetting resin particles; Adopting a production method of cured phenol resin particles characterized by including a second step of curing or curing the resin particles by continuing or separating into one step, spherical cured phenol resin particles and the like obtained thereby, It will be used suitably.

  In addition, as phenols used as a raw material of the above-described spherical cured phenol resin particles, various known ones conventionally used in the production of phenol resin particles can be mentioned. In addition to phenol, for example, m-Substituted phenols such as m-cresol, m-butylphenol, 3,5-xylenol, m-nitrophenol, m-aminophenol, m-propenylphenol, m-phenylphenol, m-chlorophenol, m-bromophenol For example, polyphenols such as resorcinol, catechol, pyrogallol, phloroglucinol, and cashew shell oil; Functional feno Kind and, for example, cresol residue, resorcinol residue, catechol residue, phenolic residue purified bisphenol A residue and the like, and may be mixtures thereof and the like.

  Further, for example, o-cresol, p-cresol, 2,5-xylenol, p-tert-butylphenol, p-nonylphenol, p-phenylphenol, p-cumylphenol, 2,5-diaminophenol, 2,4- Bifunctional phenols such as xylenol and 2,6-xylenol and monofunctional phenols can also be used together with polyfunctional phenols as long as they do not inhibit the formation of spherical cured phenol resin particles. .

  On the other hand, the aldehydes that are the other reaction raw materials of the spherical cured phenol resin particles are not particularly limited, and are generally formalin, paraformaldehyde, trioxane, tetraoxane, acetal from the viewpoint of reactivity and raw material price. For example, formaldehyde feed materials such as glyoxal, and mixtures thereof can be suitably used. In addition, acetaldehyde, butyraldehyde, benzaldehyde, hydroxybenzaldehyde, acrolein, furfural and the like can be used as necessary.

  In producing such spherical cured phenol resin particles, generally, aldehydes: 1.0 mol or more, more preferably aldehydes: 1.1 to 1. It will be used in a quantitative range of 3 moles.

  Further, in the production of spherical cured phenol resin particles that can be suitably employed in the present invention, examples of the alkylbenzene sulfonic acid having 10 or more carbon atoms used as a reaction catalyst for phenols and the like include, for example, decyl benzene sulfonic acid, dodecyl Examples thereof include benzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, and mixtures thereof. Among these, dodecylbenzene is used from the viewpoint of economy, availability, catalytic function, and the like. Sulfonic acid is particularly preferably used.

  Further, the protective colloid used in the production of the spherical cured phenol resin particles suitable for the present invention is not particularly limited, and various conventionally known protective colloids can be used. Water-soluble polymer compounds such as gum arabic, gucci rubber, hydroxyalkyl guar rubber, partially hydrolyzed polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose and the like can be exemplified, and among them, gum arabic is particularly preferably used.

  And, if the spherical cured phenol resin particles obtained as described above are used as the spherical cured phenol resin particles in the present invention, such spherical cured phenol resin particles are compared with conventional fillers, Good affinity with liquid phenolic resin, and improves coating power on the surface of liquid phenolic resin filler (spherical cured phenolic resin particles). Therefore, liquid phenolic resin and spherical cured phenolic resin particles are mixed well. Thus, a uniform SMC paste can be obtained, and therefore, the SMC obtained by impregnating glass fiber with such an SMC paste has a further improved strength of the molded product obtained by molding it. It will be an improved advantage.

  In the present invention, the spherical cured phenol resin particles as described above constitute the target SMC together with the liquid phenol resin and the glass fiber. The particles are blended in a proportion of preferably 10 to 70 mass%, more preferably 30 to 50 mass%, based on the total amount of SMC. If the amount is less than this range, the effect obtained by blending the spherical cured phenol resin particles may not be sufficiently exhibited. If the amount is more than the above range, the other components in SMC are relatively blended. There is a risk that the amount decreases, for example, the blending amount of the liquid phenol resin decreases, and the strength of the resulting molded product decreases.

  Further, the SMC according to the present invention may further contain an inorganic filler (excluding glass fiber) in addition to the liquid phenol resin, glass fiber and spherical cured phenol resin particles as described above, if necessary. Good. As such inorganic fillers, conventionally known ones can be used, for example, aluminum hydroxide, kaolin clay, calcium carbonate, silica sand, mica, talc, zinc borate, calcium silicate hydrate. Products, magnesium hydroxide, calcium hydroxide, dosonite, calcium aluminate, and the like. These may be used alone or in combination of two or more. Furthermore, among these, kaolin clay, aluminum hydroxide, calcium carbonate, silica sand, and zinc borate are preferable because flame retardancy can be particularly greatly improved by combining with a silane coupling agent described later. In particular, kaolin clay and aluminum hydroxide are more preferably used from the viewpoint of moldability and fluidity. More preferably, the aluminum hydroxide and kaolin clay and the mixing ratio thereof (aluminum hydroxide: kaolin clay) are used within a mass ratio of 1: 5 to 5: 1. Is desirable.

  And by making the SMC contain the inorganic filler as described above, the flame retardancy of a molded product obtained by molding such SMC can be advantageously improved. It will be possible.

  In the present invention, the inorganic filler is preferably used in a proportion of 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 70% by mass or less based on the total amount of SMC. It becomes. If the amount is less than the above range, the effect of improving the flame retardancy due to the inorganic filler may not be sufficiently exerted, and if the amount is more than the above range, the viscosity of the SMC paste increases. However, the impregnation of the SMC paste into the glass fiber becomes poor, so that the strength of the molded product obtained by molding such SMC may be insufficient.

  When the inorganic filler as described above is blended together with the spherical cured phenol resin particles as the organic filler as the filler to be included in the SMC, preferably, the inorganic filler: the spherical cured phenol resin particles (organic Filler) = 99: 1 to 0: 100, more preferably 90:10 to 0: 100. If this ratio is not satisfied, there is a possibility that the effect of reducing the viscosity of the paste for SMC and the effect of coating force on glass fibers due to the blending of the spherical cured phenol resin particles cannot be fully exhibited. Moreover, the blending amount of the total filler (inorganic + organic) contained in the SMC is preferably in the range of 10 to 90% by mass, more preferably 20 to 80% by mass with respect to the total amount of SMC. If the amount is less than this range, the effects of the organic and inorganic fillers as described above may not be sufficiently exerted. If the amount is more than this range, the blending amount of other components in the SMC is relatively high. May decrease, or the viscosity of the SMC paste may be increased by the inorganic filler, which may cause the above-described problems.

  Furthermore, in addition to the inorganic filler as described above, the SMC according to the present invention further includes additives similar to the conventional ones, for example, an ultraviolet absorber, an internal release agent, a thickener, etc. More preferably, a silane coupling agent or the like disclosed in Japanese Patent Application Laid-Open No. 2004-182964 is appropriately blended in a ratio within a known blending range. The silane coupling agent may be mixed directly with the SMC paste or previously mixed with a liquid phenolic resin.

  By the way, the SMC according to the present invention is obtained by mixing the liquid phenolic resin, spherical cured phenolic resin particles, and components such as an inorganic filler and a silane coupling agent as necessary, and the obtained paste for SMC. In the production of such an SMC paste, known mixers conventionally used in the production of SMC paste (for example, MTI • Made by Tsukishima Kikai Co., Ltd.) are obtained. Mixing can be performed using a universal mixer: EM200B).

  In the present invention, when preparing the SMC paste as described above, if necessary, a solvent such as water, alcohol, acetone or the like conventionally added in the preparation of the SMC paste is added. Even if these solvents are present in the obtained SMC, there is no problem.

  In the present invention, the SMC paste obtained as described above is impregnated into the glass fiber as described above, whereby the intended SMC is obtained. Then, when impregnating the glass fiber with the SMC paste, it can be performed by a conventional method using a known SMC manufacturing apparatus used conventionally. In addition, the thickness of SMC in this invention becomes like this. Preferably it is 0.5 mm or more and 20 mm or less, More preferably, it is 0.5 mm or more and 10 mm or less. Exceeding this range tends to cause a problem that it is difficult to produce SMC using a known SMC manufacturing apparatus that is usually used.

  Here, if a typical production example is given, the above-mentioned SMC paste has a substantially uniform thickness in the range of about 0.3 mm or more and 10 mm or less on the carrier film arranged above and below. The glass fiber cut into a predetermined size is spread on the paste applied to the lower carrier film, the glass fiber is sandwiched between the upper and lower carrier film pastes, and then the whole is impregnated roll The glass fiber is impregnated with the SMC paste by passing through, and then an aging treatment is performed as necessary. Here, as the carrier film, a polyethylene film, a polypropylene film, or the like is generally used. The aging treatment is one of pretreatments before molding. When such aging treatment is performed, it is preferable to perform heat treatment at 20 to 90 ° C. for about 1 hour to 20 days.

Moreover, when manufacturing the target SMC molded product using the SMC according to the present invention as described above, it is possible to adopt the same method as the conventional one. For example, first, the target molded product shape is determined. Prepare a mold that can be separated into upper and lower parts, inject the required amount of SMC into the mold, heat and pressurize, then open the mold and take out the desired molded product. . The molding temperature, molding pressure, and the like can be appropriately selected according to the shape of the target molded product. For example, in the production of a building material panel, the molding pressure is 1 × 10 ⁶ Pa or more. 80 × 10 ⁶ Pa or less is preferable, and the molding temperature is preferably 30 ° C. or higher and 240 ° C. or lower.

  Furthermore, if necessary, the SMC molded product obtained as described above may be subjected to a surface treatment such as painting. For example, when a building material panel is produced as a molded product, a weather-resistant coating film or the like may be treated on the surface.

  As described above, in the SMC according to the present invention, since the spherical cured phenol resin particles are used as the organic filler contained therein, in such an SMC paste, Compared with the SMC paste, the viscosity can be kept sufficiently low, in other words, the fluidity can be sufficiently secured, so that the wettability of the SMC paste with the glass fiber is improved. SMCs in which glass fibers are well impregnated with SMC paste can be advantageously formed, and in molded products obtained by molding such SMCs, the strength of conventional SMCs Compared to the above, it is further improved.

  Moreover, in the SMC according to the present invention as described above, since it has excellent fluidity at the time of molding, as a building material panel or the like that is particularly required to have high flame retardancy and high designability, It can be advantageously used.

  Hereinafter, some examples of the present invention will be shown and the present invention will be more specifically clarified, but the present invention is not limited by the description of such examples. It goes without saying. In addition to the following examples, the present invention can be subjected to various changes, corrections, improvements and the like based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Should be understood.

  First, the liquid phenol resin, spherical cured phenol resin particles, cured phenol resin pulverized product, and wood powder used in the examples and comparative examples of the present invention were prepared as follows.

(1) Liquid phenolic resin In a three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, 752 parts by mass of phenol, 868 parts by mass of 47% formalin, and 75 parts by mass of a 20% aqueous potassium hydroxide solution were charged. The resolation reaction was performed at 85 ° C. for 4 hours. Thereafter, the system was cooled to 40 ° C., neutralized with a 50% p-toluenesulfonic acid aqueous solution, 22.6 parts by mass of 50% urea water was added, and the water content was 20 masses under reduced pressure and heating. % To obtain 1343 parts by mass of a liquid phenolic resin.

(2) Spherical cured phenol resin particles In a 5 L flask equipped with a reflux condenser, a thermometer, and a stirrer, 1500 parts by mass of phenol (P) and 572 parts by mass of 92% paraformaldehyde (F) [F / P ( Mol) ratio = 1.1], 150 parts by weight of 20% aqueous solution of gum arabic, 150 parts by weight of 10% aqueous solution of dodecylbenzenesulfonic acid and 1821 parts by weight of diluted water (water in reaction system / P = 1.41). After charging and heating and stirring at a rate of about 1 ° C./min to the reflux temperature, the reaction was carried out while maintaining the same temperature, and after 45 minutes when resin particles were produced, the produced phenolic resin In order to prevent the composite of the particles, the reaction temperature was slightly lowered and the reaction was continued for another 4 hours to cure the phenol resin particles. Next, neutralization with NaOH, cooling, filtration, washing (washing with hot water-methanol washing) and drying with a vacuum drier were performed to confirm that there was no formaldehyde odor. %, Yellowish brown spherical cured phenol resin particles having an average particle diameter of 33.4 μm were obtained at a yield of 115% based on the raw material phenol.

(3) Hardened phenol resin pulverized product 1000 parts by mass of phenol and 8.0 parts by mass of oxalic acid were charged in a reactor equipped with a heat exchanger, a thermometer, and a stirrer. Then, after raising the temperature of the mixture to 90 ± 2 ° C., maintaining 650 parts by mass of 37% formaldehyde aqueous solution kept in the holding tank while maintaining the same temperature and controlling the degree of vacuum to 440 Torr. The mixture was added to the mixed solution over 3 hours, and after the addition, the mixture was kept under the same conditions for 3 hours to perform an aldehyde contact reaction. Subsequently, after heating the obtained reaction liquid to 150 ° C. under normal pressure, the liquid temperature is increased to 230 ° C. while maintaining the degree of vacuum at 60 Torr to remove residual moisture and free monomer. As a result, a novolac type phenol resin having a melting point of 85 ° C. and a free monomer amount of 0.2% by mass was obtained. 1000 parts by mass of the novolak type phenolic resin and 100 parts by mass of hexamethylenetetramine were mixed and ground, and then heated at 120 ° C. for 60 minutes and further at 160 ° C. for 60 minutes. The obtained cured phenol resin was coarsely pulverized with a hammer mill and then finely pulverized using a pulverizer. The acetone extraction rate of the obtained cured phenol resin pulverized product was 7% by mass, and the average particle size was 40 μm.

(4) Wood flour Sawdust generated during sawing was pulverized with a roll mill and sieved with a 200-mesh sieve to obtain wood powder having an average particle size of 40 μm.

Example 1
30 parts by mass of the liquid phenol resin obtained as described above, as a thickener, 0.3 part by mass of calcium hydroxide, as an internal mold release agent, 1 part by mass of zinc stearate, as an organic filler, 45 parts by mass of the spherical cured phenol resin particles obtained as described above and 0.1 part by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed with a hand mixer for about 10 minutes. Stirring to obtain a paste for SMC. Here, with respect to this SMC paste, the paste viscosity at a temperature of 25 ° C. was measured using a programmable digital viscometer (model DV-II +) manufactured by Brookfield, USA. The obtained results are also shown in Table 1 below.

  Next, a polypropylene film having a thickness of 40 μm is used as a carrier film, and 25 parts by mass of glass fiber is dispersed with respect to 75 parts by mass of the SMC paste using an SMC manufacturing apparatus, and sandwiched between the pastes. Then, an aging treatment was performed at 50 ° C. for 50 hours to produce an SMC having an average thickness of 1 mm, and further, this SMC was molded to obtain a desired molded product. A sample for a three-point bending test was cut out from the flat plate portion of the SMC molded product thus obtained, and JIS-K-6911- using a universal testing machine (PCM-500 type universal tensile compression testing machine manufactured by Minebea Co., Ltd.). According to 2001, bending strength was measured by three-point bending. The obtained results are also shown in Table 1 below.

-Example 2-
Instead of the organic filler of Example 1 (45 parts by mass of spherical cured phenol resin particles), 25 parts by mass of spherical cured phenol resin particles were used as the organic filler, and 20 parts by mass of kaolin clay as the inorganic filler. Except for the above, an SMC was produced in the same manner as in Example 1, and a molded product was obtained by molding the SMC. The paste viscosity and bending strength were evaluated by the same method as in Example 1 above. The obtained results are shown in Table 1 below.

-Comparative Example 1-
A SMC is produced in the same manner as in Example 1 except that 45 parts by mass of kaolin clay is used as an inorganic filler instead of the organic filler of Example 1, and a molded product is obtained by molding the SMC. Got. The paste viscosity and bending strength were evaluated by the same method as in Example 1 above. The obtained results are shown in Table 1 below.

-Comparative Example 2-
A SMC was produced in the same manner as in Example 1 except that 45 parts by mass of wood flour was used as the organic filler in place of the organic filler in Example 1, and a molded product was obtained by molding the SMC. Got. The paste viscosity and bending strength were evaluated by the same method as in Example 1 above. The obtained results are shown in Table 1 below.

-Comparative Example 3-
In place of the organic filler of Example 1, an SMC was prepared in the same manner as in Example 1 except that 45 parts by mass of the pulverized cured phenol resin was used as the organic filler, and the SMC was molded. A molded product was obtained. The paste viscosity and bending strength were evaluated by the same method as in Example 1 above. The obtained results are shown in Table 1 below.

  As is clear from the results of Table 1 above, Examples 1 and 2 which are SMCs according to the present invention can both keep the viscosity of the SMC paste low and sufficiently ensure the fluidity of the SMC paste. From the point of view, the glass fiber is well impregnated with such SMC paste. Therefore, in the molded product obtained by molding such SMC, the bending strength is higher than that of the comparative example. Met.

On the other hand, when only an inorganic filler is used as a filler, or when a conventional organic filler such as wood powder or cured phenol resin powder is used, the viscosity of the SMC paste is either Since such SMC is poor in impregnation into glass fiber, the molded product obtained by molding it has a lower bending strength than the examples according to the present invention. there were.

Claims (6)

  A sheet molding compound comprising at least a liquid phenolic resin, glass fibers, and spherical cured phenolic resin particles.   The sheet molding compound according to claim 1, further comprising an inorganic filler.   The sheet molding compound according to claim 1 or 2, wherein the spherical cured phenol resin particles are used in a proportion of 10 to 70 mass%.   The sheet molding compound according to any one of claims 1 to 3, wherein an average particle diameter of the spherical cured phenol resin particles is 1 nm to 100 µm.   A molded product obtained by press-molding the sheet molding compound according to any one of claims 1 to 4. The molded article according to claim 5, wherein the molded article is a building material panel.