JP2005179583A - Resin composition for frp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for FRP, getting good mold releasability at a high-temperature part as well as a low-temperature part even if the molded article has temperature nonuniformity in a press molding of the composition, and easily releasable from the mold to improve the molding cycle and reduce the production cost. <P>SOLUTION: The resin composition for FRP contains zinc stearate in combination with stearic acid as internal mold release agents. The resin composition for FRP contains 2-6 pts. wt. of zinc stearate and 0.5-1.5 pts. wt. of stearic acid as internal mold release agents based on 100 pts. wt. of the resin component. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resin composition for FRP, and more particularly to a technique for improving demoldability in a resin composition for FRP.

  Conventionally, FRP (fiber reinforced plastic) has been widely used as a composite material in various fields, for example, in the field of architecture, the field of conveyance, the field of electricity, the field of aerospace, and the like. As a method for producing this FRP, various methods have been developed, and a press molding method, a hand lay-up method, a spray-up method, and the like are known.

  Among these, as molding materials used for the press molding method, there are SMC (sheet molding compound) and BMC (bulk molding compound).

  The FRP resin composition used for the production of press-molded products is prepared by blending resin components, low shrinkage agents, fillers, internal mold release agents, thickeners, curing agents, colorants, etc. The formed material is placed on a molding die (usually referred to as “charge”), the mold is tightened and molded, and after molding, the mold is opened and the molded product is removed.

Conventionally, only zinc stearate has been used as an internal mold release agent to be blended in the FRP resin composition. (For example, see Patent Document 1)
Zinc stearate used as an internal mold release agent for the resin composition for FRP reacts (acts) effectively mainly in a high temperature range (about 110 ° C.).

However, the temperature of the molded product after molding varies depending on the location due to the difference in thickness (or temperature control piping or the like). That is, when the thickness of the molded product is thick, the temperature is high, and when it is thin, the temperature is low. Therefore, the burr part is thin, so the temperature of the molded product is low and the effect of the internal mold release agent cannot be obtained sufficiently. In addition, there is a problem that if the next molding is performed with burrs remaining, molding defects (wax defects) may occur.
Japanese Patent Laid-Open No. 2003-21470

  The present invention has been invented in view of the above-described conventional problems. In molding a press-molded product, even if there is a variation in the molded product temperature after molding, either the high-temperature region part or the low-temperature region part Therefore, it is an object of the present invention to provide a resin composition for FRP in which good mold release properties are obtained, mold release is easy, molding cycles can be improved, and production costs can be reduced.

  In order to solve the above-mentioned problems, the resin composition for FRP according to the present invention is characterized in that zinc stearate and stearic acid are used in combination as an internal mold release agent. Here, it is preferable to contain 2 to 6 parts by weight of zinc stearate and 0.5 to 1.5 parts by weight of stearic acid as an internal release agent with respect to 100 parts by weight of the resin component.

  By adopting such a configuration, when press molding is performed using the FRP resin composition of the present invention, even if the molded product temperature varies due to differences in thickness, temperature control piping, etc., the meat Zinc stearate acts effectively as an internal mold release agent in areas where the temperature of the molded product after molding is high (around 110 ° C), such as where the thickness is thick, and molding is performed where the thickness is thin. In the part of the low temperature region (100 ° C. or less) where the temperature of the molded product is low, stearic acid effectively acts as an internal mold release agent, and as a result, good release in both the high temperature region and the low temperature region. Therefore, the mold can be easily removed, the molding cycle is stabilized, the molding cycle is improved, and the production cost can be reduced.

  According to the present invention, in the molding of a press-molded product, even if there is a variation in the temperature of the molded product after molding, good releasability is obtained in both the high-temperature region and the low-temperature region. The mold is easy, the molding cycle is stable, the molding cycle is improved, and the production cost can be reduced.

  The present invention will be described below.

  First, a molding material (excluding reinforcing fibers, commonly referred to as a compound for FRP called a compound) is blended. That is, the resin composition for FRP of the present invention is prepared by blending a resin component, a low shrinkage agent, a filler, an internal release agent, a thickener, a curing agent, a colorant and the like.

  As the resin, unsaturated polyester resin, vinyl ester, acrylic resin or the like is used. Examples of the filler include calcium carbonate, aluminum hydroxide, barium sulfate, clay, talc, silica, glass beads, alumina, mica and the like. Among these, one kind or a mixture of two or more kinds is used. As the mold release agent (internal mold release agent), zinc stearate and stearic acid are used in combination. Other pigments, thickeners and the like are added and mixed by stirring to obtain a compound.

  Regarding blending, among the internal mold release agents, the zinc stearate is preferably 100 parts by weight of the resin component, the internal mold release agent is 2-6 parts by weight of zinc stearate, and the stearic acid is 0. It mix | blends in 5 to 1.5 weight part. In the case of normal addition blending, it is preferable that zinc stearate / stearic acid = 4/1.

Here, when the addition ratio of stearic acid is excessively increased or the blending specification of only stearic acid is used, the boiling resistance is lowered. (That is, in the case of the ratio specification of zinc stearate / stearic acid = 4/1, it is ΔE / 3.0 or less (90 ° C. × 750 h), and the addition ratio of stearic acid is increased too much or the mixing specification of only stearic acid is used. In this case, ΔE / 3.0 or more (90 ° C. × 750 h).)
Next, as a reinforcing fiber to be combined with the above compound, glass fiber is representative, but there are organic fibers such as carbon fiber, aramid fiber, and other vinylon fibers, which are used alone or in combination. The form of the reinforcing fiber to be used is chopped strand, and the fiber length is adjusted to 1 inch and the content rate is about 20%.

  After compounding reinforcing fibers in the compound, a thickened material for press molding is thickened by allowing it to stand for a certain period of time in a storage room called a so-called thermal chamber at a certain temperature (for example, 35 ° C to 45 ° C) And

  The FRP press-molded product is molded by press molding using the above-described molding material by a press molding apparatus to which a mold is attached. The press molding conditions are as follows.

That is, the mold core mold (male mold) temperature is 90 ° C to 160 ° C, more preferably 120 ° C to 150 ° C, and the mold mold mold (female mold) temperature is 90 ° C to 160 ° C, more preferably 100 ° C. In the range of ˜140 ° C., the pressurizing pressure is in the range of 30 to 150 kgf / cm ² , more preferably in the range of 50 to 120 kgf / cm ² . The pressurization time is appropriately set in the range of about 3 to 15 minutes.

  After molding, the mold is removed to form an FRP press-molded product.

  As described above, an FRP press-molded product is molded using the FRP resin composition. Here, the FRP resin composition according to the present invention includes zinc stearate and stearic acid as internal release agents. Therefore, even if the molded product temperature varies due to differences in thickness, temperature control piping, etc., the molded product temperature after molding is high (about In the portion of around 110 ° C., zinc stearate effectively acts as an internal mold release agent to obtain good release properties, and the molded product temperature after molding is low, such as where the wall thickness is thin. In the region (100 ° C. or lower), stearic acid acts effectively as an internal mold release agent, and good mold release properties can be obtained. Thereby, the mold release property of the FRP press-molded product from the mold is improved, and the molding cycle is stabilized. By stabilizing the molding cycle in this way, the molding cycle is improved and the production cost can be reduced.

  Examples will be described below.

(Example)
Glass fibers were blended into the resin compounds having the blends shown in Table 1 below, and allowed to thicken in a storage at 40 ° C. in an environment of 40 ° C. to obtain a molding material for press molding.

Using this molding material, the mold core mold (male) temperature is 145 ° C., the mold cavity mold (female mold) temperature is 130 ° C., the pressurization pressure is 70 kgf / cm ² , and the pressurization time is 8 minutes. Perform press molding under molding conditions. After molding, the mold was removed to form an FRP press molded product (bathtub).

(Comparative example)
Glass fibers were blended into the resin compounds having the blends shown in Table 2 below, and the mixture was allowed to thicken in a storage at 40 ° C. in an environment of 40 ° C. to obtain a molding material for press molding.

  Using this molding material, press molding is performed under the same molding conditions as in the examples. After molding, the mold was removed to form an FRP press molded product (bathtub).

  In the examples, the demolding was performed smoothly, but in the comparative examples, the demoldability was poor and burrs remained in the mold.

Claims (2)

  A resin composition for FRP, wherein zinc stearate and stearic acid are used in combination as an internal mold release agent.   2. The resin component according to claim 1, comprising 2 to 6 parts by weight of zinc stearate and 0.5 to 1.5 parts by weight of stearic acid as an internal mold release agent. A resin composition for FRP.