JP5334375B2 - Thermosetting resin composition, fiber reinforced molding material and molded body - Google Patents

Description

  The present invention relates to a thermosetting resin composition particularly useful as a binder for a fibrous base material, a fiber-reinforced molding material obtained using the same, and a molded body obtained by molding and curing the fiber-reinforced molding material It is about.

Conventionally, a molded body made of a fiber reinforced molding material called FRP has excellent mechanical strength and durability, as is well known. For example, a bathtub, a water tank, a septic tank, an exterior / interior In addition to housing-related parts for automobile panels, they are used as vehicle-related parts, advertising boards, leisure boats, bobbins and the like .

  And as such fiber reinforced molding material, a fiber base which is a reinforcing fiber is obtained by adding an inorganic filler and additives such as a curing accelerator and a release agent to a thermosetting resin and mixing them. A composite material that is impregnated or coated (hereinafter simply referred to as “impregnation”) and semi-cured by aging as necessary is used, and this composite material is heated and pressed. Thus, a molded article having excellent characteristics as described above is manufactured. Typical examples of such fiber-reinforced molding materials include sheet molding compound (SMC), bulk molding compound (BMC), prepreg, premix, and the like depending on the material form at the time of molding.

  More specifically, taking the above SMC as an example, SMC is a fiber reinforced molding material having a sheet-like form, and usually an inorganic filler is added to a thermosetting resin, and further if necessary. Then, an additive such as a curing accelerator (thickening agent) and a release agent is added and mixed by stirring to prepare a pasty thermosetting resin composition (hereinafter simply referred to as “paste” in this paragraph). Then, after applying this paste on a releasable carrier film with an SMC manufacturing apparatus, a fibrous base material is spread on the applied paste, and further, the paste is further applied thereon. The carrier film is laminated so that the fibrous base material is sandwiched from above and below to form a sheet having a three-layer structure, and is then passed through a plurality of rollers and pressed to paste the fibrous base material. Impregnation with Performing thickness adjustment, without the sheet of predetermined thickness, further, typically by performing aging treatment, it is being produced. And as described above, the SMC manufactured in this way is utilized as a material for housing-related parts, vehicle-related parts, etc., taking advantage of the properties of thermosetting molding materials reinforced with fibers. .

  However, fiber reinforced molding materials such as SMC are likely to be accompanied by anisotropy due to the fibrous base material, which reduces the dimensional accuracy due to warpage deformation in a molded body obtained by heating and pressing the fiber reinforced molding material. In addition, there are inherent problems such as a decrease in aesthetics due to lack of surface smoothness.

  Under such circumstances, in Japanese Patent Laid-Open No. 2001-261976 (Patent Document 1), specific plate-like boehmite or plate-like alumina is effective as a filler in order to suppress anisotropy that causes warpage and distortion. It has been made clear that there is. Japanese Patent Application Laid-Open No. 59-36143 (Patent Document 2) clarifies that no warpage is imparted by using mica powder as a reinforcing material. Although any document has improved warping resistance, it is still difficult to say that the effect of suppressing anisotropy when a fibrous base material is used as an essential component, and there is room for improvement. It was what had.

  Further, among the fiber reinforced molding materials as described above, in particular, in SMC, since it is also used for manufacturing a molded body by deep drawing, it is desirable that there is no anisotropy. There is a strong demand for a material having low-pressure moldability (property that can be molded at a low pressure), which is advantageous for suppressing property.

JP 2001-261976 A JP 59-36143 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is a heat that can be advantageously used for the production of a fiber-reinforced molding material having excellent low-pressure moldability. It is to provide a curable resin composition, and to provide a fiber-reinforced molding material that is excellent in low-pressure moldability and can impart warpage resistance and surface smoothness to a molded body, and further warpage resistance. Another object of the present invention is to provide a molded article having improved surface smoothness.

  And, as a result of intensive studies on the thermosetting resin composition used in the production of the fiber-reinforced molding material, the inventor of the present invention includes kaolin clay having a specific densely packed bulk density as an inorganic filler. The present inventors have found that the problems as described above can be solved eagerly and have completed the present invention.

That is, the present invention is a thermosetting resin composition used as a binder for a fibrous base material, containing the thermosetting resin in a proportion of 35 to 70% by mass, and having a tightly packed bulk density of 0.1. A thermosetting resin composition containing 71 to 1.15 g / cm ³ of kaolin clay in a proportion of 30 to 65% by mass and having a thixotropic index of 2.0 or more and 4.0 or less . Is the gist of this.

In one preferred embodiment of the thermosetting resin composition according to the present invention, the kaolin clay is a flat or flaky kaolin clay .

  Furthermore, in another preferred embodiment of the thermosetting resin composition according to the present invention, a thermosetting phenol resin is employed as the thermosetting resin.

  The gist of the present invention is also a fiber-reinforced molding material characterized by containing the thermosetting resin composition as described above and a fibrous base material as essential components.

  In one preferred embodiment of the fiber reinforced molding material according to the present invention, the fiber reinforced molding material is in a sheet form, that is, a sheet molding compound (SMC).

  In addition, the gist of the present invention is a molded body obtained by molding and curing the fiber-reinforced molding material.

Thus, in the thermosetting resin composition according to the present invention, kaolin clay having a densely packed bulk density of 0.71 to 1.15 g / cm ³ is contained as an inorganic filler. The composition exhibits a high viscosity and remarkable thixotropy, and the fluidity when an external pressure is applied is effectively enhanced.

  For this reason, in the fiber reinforced molding material according to the present invention containing such a thermosetting resin composition and a fibrous base material, the fluidity at the time of molding can be effectively enhanced, and the pressure is lower than before. It is possible to mold with a low pressure moldability.

  Therefore, in a molded body obtained by molding and curing such a fiber reinforced molding material, it is difficult to be accompanied by anisotropy due to the fibrous base material, has excellent warpage resistance, and good dimensional accuracy can be realized. In addition, the surface smoothness is advantageously improved, and the aesthetics can be improved.

  In particular, when a thermosetting phenol resin is used as the thermosetting resin, excellent flame retardancy is imparted to the obtained molded body.

  In addition, when the fiber-reinforced molding material according to the present invention is formed into a sheet shape, as described above, since it is excellent in low-pressure moldability, deep drawing can be easily performed.

  By the way, the thermosetting resin composition according to the present invention is a composition having a thermosetting resin and kaolin clay having a specific close-packed bulk density as essential components, and is used in combination with a fibrous base material or as necessary. It is advantageously used as a binder for other inorganic fillers.

  Here, as the thermosetting resin, although thermosetting phenol resin and unsaturated polyester resin are generally used, other thermosetting resins, for example, at least epoxy resin, melamine resin, guanamine resin, etc. One kind can be used alone or in combination within a quantitative range that does not impair the curability of the thermosetting phenol resin or unsaturated polyester resin. Among these, the thermosetting phenol resin is particularly preferably used because it is advantageous in terms of flame retardancy. Examples of such thermosetting phenol resins include resol type phenol resins, Examples thereof include benzyl ether type phenol resins, novolac type phenol resins, modified or modified phenol resins thereof, and mixtures thereof. Among such thermosetting phenol resins, in particular, a resol type phenol resin can be suitably employed from the viewpoints of coatability and curing characteristics.

  And in this thermosetting resin composition, this thermosetting resin is generally contained in the ratio of 35-70 mass%, and preferably 40-40 mass% from the point of a flame retardance. It is.

On the other hand, kaolin clay contained in the thermosetting resin composition according to the present invention is produced from raw materials such as clay (kaolinite, halloysite) and wax stone (pyrophyllite), which are mainly produced from aluminum silicate. a kaolin clay and pyrophyllite clays are, close-packed bulk density, in particular, those in the range of 0.71 ~1.15g / cm ^3, preferably 0.71 ~1.10g / cm ^3, More preferably, those in the range of 0.71 to 1.00 g / cm ³ are used. This is because if the densely packed bulk density is decreased , the flame retardancy of the molded product may be decreased. Conversely, if the densely packed bulk density exceeds 1.15 g / cm ³ , the thixotropy for the composition is obtained. Even if it is used as a binder for a fibrous base material, it does not give low-pressure formability to the fiber reinforced molding material, and a molded product obtained by molding and curing the fiber reinforced molding material. This is because it is impossible to improve the surface smoothness and warpage resistance. The above-mentioned densely packed bulk density is literally a bulk density when densely packed. In the present invention, the condition of tapping speed: 1 time / second, tapping time: 10 minutes, total number of tapping: 600 times The mass (bulk density) of kaolin clay per unit area is obtained by close packing.

  Further, in the present invention, among kaolin clay having such densely packed bulk density, in particular, kaolin clay having a shape as shown in the scanning electron microscope (SEM) photograph of FIG. 1 or FIG. Is a flat or flaky kaolin clay having an average particle diameter of about 5 μm, and by using such a kaolin clay, as described later, In addition, the viscosity of the thermosetting resin composition is increased and the thixotropy is further advantageously enhanced, thereby imparting extensibility to the composition and effective impregnation of the fibrous base material by external pressure. It is possible to prevent excessive lateral flow at a position not subject to external pressure. In addition, the composition has a thixotropic index that is effective in improving the pressure fluidity of the fiber-reinforced molding material, so that it can be molded at a lower pressure than in the past, and the desired molded article can be obtained. The occurrence of warp or the like can be advantageously prevented. In addition, the kaolin clay of this shape can be obtained commercially, For example, the kaolin clay (product name: FY86) marketed from Fujilite Industry Co., Ltd. can be illustrated.

  And the kaolin clay which has the above-mentioned close-packed bulk density is generally 30-65 mass% in the thermosetting resin composition, Preferably it is desirable to contain in the ratio of 40-60 mass%. The reason for this is that when the content of kaolin clay is less than the above range, effects such as low-pressure moldability, surface smoothness, warpage resistance, etc., even if used as a binder for a fibrous base material, are used. This is because it may not be able to be expressed advantageously, and when it exceeds the above range, the viscosity of the thermosetting resin composition becomes too high and the content of the thermosetting resin is relatively high. This is because the function as a binder may not be achieved.

  The thermosetting resin composition according to the present invention includes, in addition to the above thermosetting resin and kaolin clay having a specific close-packed bulk density, a quantitative range that does not hinder the effects of the present invention, if necessary. In addition, other inorganic fillers other than the above kaolin clay, various conventional additives such as a curing accelerator (thickening agent), a release agent, and a silane coupling agent can be blended. Here, examples of the inorganic filler include aluminum hydroxide, calcium carbonate, talc, microballoon, silica sand, calcium silicate and the like, and one or more of these may be used as necessary. Can be formulated. Examples of the curing accelerator include hydroxides and oxides of alkaline earth metals such as magnesium hydroxide, calcium hydroxide, and magnesium oxide. Examples of the mold release agent include zinc stearate and calcium stearate. Examples include stearic acid-based metal salts.

Thus, in preparing the thermosetting resin composition according to the present invention, the same technique as in the past can be employed. For example, using a known mixing apparatus such as MTI / Universal Mixer manufactured by Tsukishima Kikai Co., Ltd., the thermosetting resin as an essential component and the densely packed bulk density are 0.71 to 1.15 g / cm. ^{3. A} paste-like thermosetting resin composition according to the present invention is prepared by adding kaolin clay, ³ and, if necessary, other various additives simultaneously or in any order, and stirring and mixing. . In preparing the thermosetting resin composition, it is possible to add a solvent such as water, alcohol, or acetone as necessary.

In the thermosetting resin composition obtained as described above, a kaolin clay having a closely packed bulk density of 0.71 to 1.15 g / cm ³ is used, and therefore, 1.15 g / cm. Compared to a thermosetting resin composition using kaolin clay having a densely packed bulk density exceeding ³ , the viscosity becomes extremely high, and thixotropic property is imparted, and the thixotropic index is advantageously improved. It becomes. Note that in this case, thixotropic index is: for "stirring speed n viscosity at _1": the ratio of "agitation rotational speed viscosity at n _2" (where, n _1> n ₂₎ are those represented by In the present invention, the viscosity was calculated by measuring the viscosity (A) at 10 rpm and the viscosity (B) at 100 rpm at 25 ° C. using a commercially available viscometer (for example, a programmable digital viscometer manufactured by Brookfield, USA). Let the ratio (A / B) be a thixotropic index.

  In the thermosetting resin composition according to the present invention, it is desirable that the thixotropic index is 2.0 or more in order to obtain effective low-pressure moldability. In addition, the upper limit of the thixotropic index is preferably 4.0 or less, more preferably 3.5 or less in consideration of deterioration of the impregnation property to the fibrous base material due to the rapid increase in viscosity of the paste. It is desirable. Thus, when the thixotropic index is 2.0 or more, the fluidity when external pressure is applied is effectively enhanced, and when used as a binder for a fibrous base material, fiber reinforced molding Excellent low pressure formability can be imparted to the material.

  Thus, the thermosetting resin composition according to the present invention is advantageously used for the production of a fiber-reinforced molding material as a binder for a fibrous base material. Hereinafter, such a thermosetting resin composition and The fiber reinforced molding material according to the present invention that is configured to include a fibrous base material will be specifically described. Here, as a fiber-reinforced molding material, a sheet molding compound (SMC) having a sheet-like form is taken up as a representative and will be described in detail.

  That is, the fiber-reinforced molding material according to the present invention contains a paste-like thermosetting resin composition (hereinafter referred to as a paste) as described above and a fibrous base material as essential components. As the above, those containing at least a thermosetting resin as described above and kaolin clay having a specific close-packed bulk density are used.

On the other hand, the fibrous base material is not particularly limited as long as it has a reinforcing function mainly composed of fibrous materials, depending on the characteristics required for the fiber reinforced molding material and the application field thereof. Thus, an arbitrary shape and material are appropriately selected and used. Examples of the shape of the fibrous base material include various fibers having shapes such as filament, roving, strand, chopped strand, paper, mat, and cloth. The material for the fibrous base material, e.g., glass fibers, carbon textiles, A aramid fibers, phenol fibers, polyamide fibers, polyester fibers, alumina fibers, other metal fibers, whiskers, milled fibers, linter, hemp Examples thereof include fibers and wood chips. These fibrous base materials may be used alone or in combination of two or more. Of these, glass fibers are most preferably used in SMC from the viewpoints of cost, strength, availability, and the like.

  In addition, when using the said glass fiber as a fiber base material, it is desirable to use a silane coupling agent together, and this improves the affinity of the thermosetting resin contained in the paste and the glass fiber. As a result, the adhesion between the thermosetting resin and the glass fiber can be effectively improved. Examples of such silane coupling agents include aminosilanes such as N-β (aminoethyl) -γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane, and epoxy silanes such as γ-glycidoxypropyltrimethoxysilane. Are preferably used. Moreover, although this silane coupling agent will generally be used in the ratio which becomes the range of 0.01-5 mass parts with respect to 100 mass parts of glass fiber, the effect by addition of a silane coupling agent From the standpoints of the development and cost, it is desirable to use it in a proportion that is preferably in the range of 0.05 to 3.0 parts by mass. Usually, it is added and mixed in advance in the paste as described above.

  And the fiber reinforced molding material according to this invention can be produced by impregnating the said fiber base material with the said paste by the method similar to the past. At this time, the mixing ratio of the fibrous base material in the fiber reinforced molding material (SMC) is particularly a ratio of 3 to 60% by mass, preferably 5 to 40% by mass, and more preferably 8 to 35% by mass. It is contained at a ratio of. This is because if the blending ratio is less than 3% by mass, the reinforcing effect by the fibrous base material cannot be sufficiently exerted, and there is a possibility of causing insufficient strength. This is because it tends to be difficult to impregnate the base material with the paste.

  More specifically, the fiber-reinforced molding material according to the present invention can be typically produced as follows. That is, a known SMC apparatus is used, and the above-mentioned paste is applied at a predetermined thickness on one surface of a carrier film made of polyethylene, polypropylene, or the like disposed above and below. Next, the fibrous base material is spread on the paste applied to the lower carrier film, and the upper carrier film is further superimposed thereon, so that the fibrous base material is sandwiched between the upper and lower pastes. . The fiber base is impregnated with a carrier film and paste in the vertical direction by simultaneously impregnating the fibrous base material with the paste by pressurizing it by passing it between a plurality of rolls, etc. A sheet having a three-layer structure in which a material and a carrier film are sequentially laminated is manufactured, and then semi-cured by being subjected to aging treatment (thickening treatment) as necessary, and the fiber-reinforced molding material according to the present invention As a result, the SMC is manufactured. Here, when the aging treatment is performed, the conditions can be appropriately set in consideration of the moldability of SMC. For example, the heat treatment is performed at a temperature of 50 to 70 ° C. for several hours to several days. Is done.

  The SMC produced in this way is obtained by impregnating a fibrous base material with the paste as described above, and the fluidity of the material during molding is effectively enhanced. Therefore, it has a low-pressure moldability that can be molded at a lower pressure than in the past. For this reason, the expression of anisotropy can be advantageously suppressed, warpage or unevenness can be advantageously prevented from occurring in the target molded article, and deep drawing can be performed very easily. It is possible. Moreover, since it has excellent fluidity, it is advantageously prevented that the fibrous base material is localized without flowing during pressure molding, in other words, only the paste flows, It is advantageously prevented from being rolled, and the fibrous base material spreads and spreads to every corner of the molded body. Therefore, it can be advantageously prevented that the strength of the molded body is partially weakened, and high strength can be ensured in every corner of the molded body.

  Moreover, when manufacturing the target SMC molded body 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 body shape is determined. Prepare a mold that can be separated into upper and lower parts, put a required amount of SMC with the carrier film peeled into this mold, heat and pressurize, then open the mold and take out the desired molded body Then, the intended SMC molded body is manufactured by a normal press molding method or the like. At this time, the molding pressure and molding temperature can be appropriately set depending on the size, shape, etc. of the target molded body. For example, when a building material panel is produced as an SMC molded body, generally, 1 MPa or more, Although a molding pressure of 80 MPa or less and a molding temperature of 30 ° C. or higher and 240 ° C. or lower can be adopted, in the present invention, as described above, the fluidity of SMC is effectively enhanced, Even with a conventional molding pressure of about 1/4 to 1/2, molding can be advantageously performed.

  Thus, in the molded body according to the present invention, since kaolin clay having a specific close-packed bulk density is used as the inorganic filler, as described above, the paste obtained as an intermediate has thixotropic properties. Thus, the fluidity of SMC, which is the material of the molded body, is effectively enhanced, and excellent low-pressure moldability is realized. In a molded product obtained by molding and curing such SMC, deep drawing can be easily performed, and the fibrous base material as a reinforcing material is uniformly dispersed throughout the molded product. As a result, the strength is further improved as compared with the conventional one.

  Moreover, since the fluidity of SMC can be effectively increased and excellent low-pressure formability can be realized, it is difficult to be accompanied by anisotropy due to the fibrous base material, and has excellent warpage resistance and good dimensional accuracy. In addition, the surface smoothness can be advantageously improved, and the aesthetics can be improved. Therefore, according to this invention, the large molded object without an external appearance defect can be manufactured advantageously.

  Thus, the molded body according to the present invention has excellent mechanical strength and durability. For example, housing-related parts such as bathtubs, water tanks, septic tanks, exterior / interior panels, vehicle-related parts, It can be advantageously used as an advertising board, leisure boat, bobbin or the like. Above all, when a thermosetting phenol resin is used as the thermosetting resin, it gives excellent flame resistance to the molded product, so that vehicle-related parts and housing-related parts where flame resistance is important As a result, it will be used particularly advantageously. Needless to say, when the molded body according to the present invention is used, it may be subjected to a surface treatment such as a coating treatment, if necessary.

The specific configuration of the present invention has been described in detail by taking the SMC having a sheet form as an example. However, this is merely an example, and the present invention is not limited to the above description. not to undergo limitations, in addition to the above SMC, bulk molding compound (BMC), a prepreg, those various forms of the premix or the like, and to obtain Ri target Do of the present invention.

  Some examples of the present invention will be shown below to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say. In addition to the following examples, the present invention includes various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the specific description described above. It should be understood that improvements and the like can be added.

  In this example, the measurement of densely packed bulk density of kaolin clay, the measurement of paste viscosity and thixotropic index, the evaluation of flame retardancy, the evaluation of surface smoothness, the measurement of warpage, and the low pressure formability of SMC Evaluation of was performed by the following method.

(1) Measurement of densely packed bulk density First, the mass (α) of a stainless bulk density measuring cup (inner diameter: 50.40 mm, height: 50.15 mm) having a volume of 100 cm ³ was measured. Next, a cap is attached to the opening of the measuring cup, and after the kaolin clay is gently put into the top of the cap using a spoon, etc., a cap cover for preventing the kaolin clay from scattering is attached, A measurement sample was prepared. Then, using the powder tester (TYPE: RT-E) manufactured by Hosokawa Micron Co., Ltd., the measurement sample is set in this tapping holder, and tapping is performed 600 times in total for 10 minutes at a speed of 1 time / second. Went. Then, take out the measurement sample from the tapping holder, gently remove the cap and cap cover, and then scrape the excess kaolin clay that has risen from the opening of the measurement container with a blade. Mass (β) was measured. Then, in the following calculation formula, the mass (β−α) obtained by subtracting the measurement cup mass (α) from the mass (β) of the measurement cup containing kaolin clay, that is, the mass of the kaolin clay, By dividing by the volume of 100 cm ³ , the densely packed bulk density was calculated, and this measurement was repeated four times to obtain the densely packed bulk density (average value).
Close packed bulk density [g / cm ³ ] = (β−α) / 100

(2) Measurement of Paste Viscosity and Thixotropic Index Paste viscosity was measured at a temperature of 25 ± 1.0 ° C. in a hot water circulating thermostat after collecting about 10 g of paste in an aluminum cylindrical container. Then, using a programmable digital viscometer (model: DV-II +, manufactured by Brookfield, USA), the rotation speed was 10 rp
It was determined by measuring the viscosity (A) at m. On the other hand, the thixotropic index was measured by measuring the viscosity (viscosity B) at a rotational speed of 100 rpm using a paste adjusted to a temperature of 25 ± 1.0 ° C. as described above. The ratio (A / B) of the viscosity (A) at the rotation speed of 10 rpm was calculated.

(3) Flame Retardancy Evaluation Flame retardant evaluation was performed by cutting out a test piece (length: 100 mm, width: 100 mm, thickness: 2.2 mm) from the produced plate-shaped molded body, Using a meter device, a combustion test based on the “Architectural Test Methods for Fireproof and Fireproof Performance” edited by Japan Building Research Institute was conducted in a test time of 10 minutes, and the maximum heat generation rate was measured. This test was performed twice, and the average value of the maximum heat generation rate was determined to be acceptable when it did not exceed 30 MJ / m ² , while the average value exceeding 30 MJ / m ² was rejected.

(4) Evaluation of surface smoothness Evaluation of surface smoothness was performed by visually observing the uneven state (the presence or absence of unevenness and the degree thereof) of the surface of the molded body and the sharpness of the fluorescent lamp reflected on the surface of the molded body. In addition, the judgment criteria are: ◎: no unevenness, no problem with reflection of fluorescent light, ○: no unevenness, reflection of fluorescent light is slightly inferior to ◎, △: some unevenness, poor reflection of fluorescent light, X: There was unevenness and the reflection of the fluorescent lamp was extremely poor.

(5) Measurement of warpage The evaluation of warpage resistance was performed on (i) a molded body after 24 hours from molding and (ii) a molded body after heat treatment (aging). Specifically, in the above (i), a specimen immediately after molding (vertical: 270 mm, horizontal: 210 mm, thickness: 2.2 mm) is subjected to 24 under an environment of temperature: 25 ° C. and relative humidity: 30 to 40%. After standing for a period of time, the amount of warpage was determined by measuring the maximum amount of displacement (mm) from the surface of the surface plate observed by placing it on the surface plate for warpage measurement. On the other hand, in the above (ii), the specimen immediately after molding (length: 270 mm, width: 210 mm, thickness: 2.2 mm) is subjected to heat treatment (150 ° C. × 20 hours), and then naturally cooled to room temperature. The amount of warpage was determined by measuring the maximum amount of displacement (mm) from the surface of the surface plate observed by placing this on the surface plate for warpage measurement. This measurement was repeated 5 times, and the average value was calculated. The obtained average value was taken as the warpage amount (mm) of the molded body.

(6) Evaluation of low-pressure formability of SMC After cutting out a test piece (length: 5 cm, width: 5 cm) from the produced SMC (thickness: about 2 mm), this was cut into two mirror-finished stainless steel plates (length: 470 mm, width: 290 mm, thickness: 1.5 mm), and subjected to heat and pressure molding at a temperature of 150 ° C. and a molding pressure of 2.94 MPa for 3 minutes, thereby obtaining a substantially circular shaped body. . And the passing diameter of the obtained molded object was measured at four places at intervals of 45 ° in the circumferential direction. This measurement was repeated twice to calculate an average value, and the obtained average value was defined as the fluidity ( cm 2 ) of SMC. It can be determined that the greater the fluidity value, the higher the fluidity and the better the low-pressure formability. Further, the flowability of SMC was measured in the same manner as described above at a molding pressure of 5.88 MPa or 11.8 MPa.

Example 1
40 parts by mass of a resol type phenolic resin (trade name: AKP-012, manufactured by Asahi Organic Materials Co., Ltd.), 35 parts by mass of kaolin clay having a close packed bulk density of 0.81 g / cm ³ , and a curing accelerator ( 0.6 parts by weight of calcium hydroxide as a thickener), 1 part by weight of zinc stearate as a release agent, and 0.1 of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent. The mass part was stirred and mixed with a hand mixer for about 10 minutes to prepare an SMC paste as a thermosetting resin composition. And when the viscosity and thixotropic index of the paste thus obtained were measured, the viscosity was 38600 mPa · s / 25 ° C. and the thixotropic index was 2.1, respectively.

  Next, using the SMC manufacturing apparatus, the SMC paste obtained above was applied to a 40 μm-thick polypropylene carrier film, and this was roving cut to a length of about 2.54 cm (about 1 inch). The glass fiber is spread, and the carrier film coated with the paste is overlapped, so that the glass fiber is sandwiched between the pastes to form a sheet with a three-layer structure, and a plurality of rollers provided above and below. In between, the glass fiber was impregnated with the paste and the thickness of the sheet was adjusted. At this time, as shown in Table 1 below, the glass fiber was used at a ratio of 25 parts by mass with respect to about 75 parts by mass of the paste. Thereafter, the obtained sheet was subjected to aging treatment at a temperature of 50 ° C. for 70 hours to obtain an SMC having an average thickness of about 2 mm.

  Then, about 220 g of the obtained SMC was cut out, and this was cut into a cavity of a mold with a chrome plating surface finish mounted on a pressure press machine preheated to 150 ° C. (length: 270 mm, width: 210 mm, depth) : 2.2 mm), the mold was immediately set and subjected to heat and pressure molding at a molding pressure of 5.88 MPa for 5 minutes to produce a molded body having a thickness of 2.2 mm. The molded body thus obtained was used for the evaluation of flame retardancy, the evaluation of surface smoothness and the measurement of warpage as described above, and the results obtained are also shown in Table 1 below.

(Examples 2 and 3 and Comparative Examples 1 and 2)
A paste for SMC, which is a thermosetting resin composition, was prepared in the same manner as in Example 1 except that kaolin clay having a different densely packed bulk density was used instead of kaolin clay in Example 1, and the viscosity and The thixotropic index was measured and the obtained results are shown in Table 1 below. Moreover, SMC was produced using the obtained paste similarly to the said Example 1, and the molded object was produced using this SMC continuously. And about the obtained molded object, the above flame retardant evaluation, surface smoothness evaluation, and the amount of curvature were measured, and the obtained result was combined with following Table 1, and was shown. Moreover, about the kaolin clay used in the comparative example 1, the SEM photograph of a different magnification was imaged and it showed in FIG. 3 (5000 times) and FIG. 4 (10000 times).

Example 4
A thermosetting resin composition was used in the same manner as in Example 1 except that kaolin clay having a different densely packed bulk density was used instead of kaolin clay in Example 1 and the blending ratio of phenol resin and kaolin clay was changed. A paste for SMC was prepared, and the viscosity and thixotropic index of this paste were measured. The results obtained are shown in Table 1 below. Moreover, SMC was produced using the obtained paste similarly to the said Example 1, and the molded object was produced using this SMC continuously. And about the obtained molded object, the above flame retardant evaluation, surface smoothness evaluation, and the amount of curvature were measured, and the obtained result was combined with following Table 1, and was shown. Moreover, about the kaolin clay used in Example 4, the SEM photograph of a different magnification was imaged and it showed in FIG. 1 (5000 times) and FIG. 2 (10000 times).

As is clear from the results in Table 1, the viscosity and thixotropic index of the paste (thermosetting resin composition) greatly change in the vicinity of the densely packed bulk density of kaolin clay: 1.20 g / cm ^3. It can be seen that the pastes according to Examples 1 to 4 have larger viscosities and thixotropic indices than the pastes according to Comparative Examples 1 and 2. In addition, it is recognized that the molded bodies according to Examples 1 to 4 have an extremely small amount of warpage and excellent warpage resistance as compared with Comparative Examples 1 and 2, and also have good surface smoothness (◎ or ○). ). Moreover, it is recognized that the molded body which concerns on Examples 1-4 does not have any trouble also about a flame retardance.

(Examples 5 and 6 and Comparative Examples 3 and 4)
An SMC was produced in the same manner as in Example 1 except that kaolin clay having a different densely packed bulk density was used instead of kaolin clay in Example 1 and the blending ratio of phenol resin and kaolin clay was changed. The obtained SMC was used to evaluate the low-pressure formability as described above, and the results obtained are shown in Table 2 below.

As is apparent from the results in Table 2, in Examples 5 and 6 using kaolin clay having close packed bulk densities of 1.15 and 0.71 g / cm ³ , respectively, the molding pressure: 2 Even in the case of .94 MPa, the flowability of SMC exceeds 10 cm , whereas in Comparative Example 3 and Comparative Example 4 using kaolin clay with a densely packed bulk density exceeding 1.20 g / cm ³ , For the first time, the flowability of SMC exceeds 10 cm at molding pressures of 5.88 MPa and 11.8 MPa. From these results, it is recognized that the SMCs according to Example 5 and Example 6 can be molded even at a molding pressure lower than that of Comparative Example 3 and Comparative Example 4 , and are excellent in low-pressure moldability. . In particular, when Example 5 and Example 6 are compared with Comparative Example 4, the SMC according to Example 5 and Example 6 can reduce the molding pressure to about 1/2 to 1/4. is there.

Moreover, when the obtained substantially circular shaped molded product was visually observed, in the molded products according to Comparative Example 3 and Comparative Example 4 , the glass fiber was localized in the central portion, and there was not much glass fiber in the outer peripheral portion. In contrast, in the molded bodies according to Example 5 and Example 6, the glass fibers were well dispersed up to the outer peripheral portion.

It is a SEM photograph of kaolin clay used in Example 4, and shows a magnification of 5000 times. It is a SEM photograph of kaolin clay used in Example 4, and shows a magnification of 10,000 times. It is a SEM photograph of the kaolin clay used in the comparative example 1, Comprising: The magnification of 5000 times is shown. It is a SEM photograph of kaolin clay used in Comparative Example 1 and shows an enlargement magnification of 10,000 times.

Claims (6)

A thermosetting resin composition used as a binder for a fibrous base material, containing a thermosetting resin in a proportion of 35 to 70% by mass, and a densely packed bulk density of 0.71 to 1.15 g / A thermosetting resin composition comprising cm ³ kaolin clay in a proportion of 30 to 65% by mass and having a thixotropic index of 2.0 or more and 4.0 or less .
The thermosetting resin composition according to claim 1, wherein the kaolin clay is a flat or flaky kaolin clay .   The thermosetting resin composition according to claim 1, wherein the thermosetting resin is a thermosetting phenol resin.   A fiber-reinforced molding material comprising the thermosetting resin composition according to any one of claims 1 to 3 and a fibrous base material as essential components.   The fiber-reinforced molding material according to claim 4, which is in a sheet form.   A molded article obtained by molding and curing the fiber-reinforced molding material according to claim 4 or 5.

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