JPH0558387B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a method for improving the adhesion of an unsaturated polyester resin surface and a sheet used for implementing the method, and more particularly, to a method for improving the adhesiveness of an unsaturated polyester resin surface, and more specifically, to a method for improving the adhesiveness of an unsaturated polyester resin surface. The aim is to improve the adhesion of the bonding surfaces of each part to the unsaturated polyester resin used. (Prior art) Unsaturated polyester resin used in FRP etc. becomes a smooth surface when cured as is, resulting in poor adhesion, and sufficient adhesive strength cannot be obtained no matter what kind of adhesive is applied to the joint. do not have. Therefore, in order to improve this adhesive property, conventionally,
For places where strong adhesion is required, such as the joints between parts or the joints of pipes, we use a sandblasting method, in which sand is sprayed with strong jet pressure, or mechanical methods, such as polishing with a rotary file, to form a shaved surface. This method is mainly adopted. However, with these methods, for example, sandblasting, there is a serious drawback that dust containing resin powder is dissipated when sand is blasted, harming the health of workers, and the equipment is complicated and large. At the same time, there was a problem in that the processing required a considerable amount of time and labor, and productivity did not improve. In addition, file polishing also tends to cause variations in polishing, making process control difficult, and, like the sandblasting method, has the disadvantages of using resin powder that poses hygiene problems and low productivity. (Problem to be solved by the invention) Therefore, as a result of extensive research, the present inventor discovered that a new active interface was created by combining polyester resin and cloth, and this problem of resin dust was solved. The present invention has been completed by creating a method that does not generate any problems and is simple to work with. (Means for Solving the Problems and Effects) In the present invention, first, when molding an unsaturated polyester resin, the intended joint portion is positioned on the mold surface or the like in advance before molding. Then, a sheet 1 in which a cloth body 2 having adhesive properties with the unsaturated polyester resin and a membrane body 3 for stopping impregnation of the unsaturated polyester resin are integrated is laid at the positioned location. The cloth body 2 is made by bundling fibers and has unevenness formed on the surface when viewed microscopically.Generally, as shown in Fig. 1, the warp and weft, which are bundles of thin fibers, are alternately made. This refers to woven fabrics, but non-woven fabrics may be used if necessary. The fabric needs to have adhesion to the unsaturated polyester resin, but the adhesion does not necessarily need to be strong, and should be strong enough to tear one side of the interface when peeled off later. It refers to power. The membrane body 3 forms a membrane in order to stop the impregnation of the unsaturated polyester resin into the fibers at that position, and is integrated with the cloth body 2, for example, by attaching a synthetic resin film to the cloth body. Heat-seal and integrate. Then, liquid unsaturated polyester resin is poured onto the laid sheet 1, cast, and left to stand for a certain period of time or slightly heated to advance the curing reaction and allow the liquid resin to solidify. Wait (see Figure 2A). In this process, the liquid resin leaches into the fiber threads of the cloth body 2 and is fully absorbed, but when it hits the integrated membrane 3, the leaching is stopped there as described above. In other words, if the impregnation of the resin exceeds the cloth body, the membrane body 3 may become submerged in the resin, making it difficult to peel off after curing. to work. Further, the integration of the cloth body 2 works to prevent the occurrence of wrinkles, although there is a risk of wrinkles occurring if the peeling is soft. After the curing reaction progresses and the liquid resin is solidified, it is demolded (see FIG. 2B), and the sheet 1 is peeled off by hand from the surface of the solidified unsaturated polyester resin. Thereupon, the unsaturated polyester resin and the sheet 1 adhered thereto are separated, and a new interface is exposed (see FIG. 3C). The new interface is activated in three ways to improve adhesion. The first reason is that when viewed microscopically, the fabric body 2 has unevenness formed on its surface. The unevenness is formed on the resin surface forming the female mold, and the engagement of the unevenness increases the adhesive strength of the bonding surface. improves. The second reason is due to the reactivity of the unsaturated polyester resin.The curing reaction of the unsaturated polyester resin is caused by the unsaturated alkyd resin causing a radical polymerization reaction with a polymerizable monomer, and proceeding with a decomposition reaction, a growth reaction, etc. However, if both have unsaturated bonds, the grown monoradicals or polyradicals add to the unsaturated bonds, and further monomers are attached to form cross chains and harden. In the generation of this cross chain, not all functional groups have reacted even after curing has been completed, and a considerable number of functional groups remain unreacted. Therefore, when the fabric to which this unsaturated polyester resin is adhered is peeled off, the infiltrated resin is separated from the interface, and the monomer containing unreacted functional groups is exposed on the surface, which is then used for the adhesion process. When it enters, it gives rise to strong adhesion forces that create targeted cross-chain bonds. The third and final activation is due to an increase in the adhesion area due to the raised protrusions, and since the fabric is selected to maintain adhesive strength with the unsaturated polyester resin, after the resin hardens. The two are in an adhesive state, and the cloth body is peeled from this adhesive state, so
The surface is not just uneven, but also has delicate raised protrusions in the direction of tearing, which can significantly increase the bonding area. (Results) The present invention is as described above, and since it is only necessary to peel off the cloth body after curing before adhesion work, it is possible to perform work such as sand jetting or sanding, unlike the conventional sandblasting method or mechanical method. Since there is no dust, there is no need to dissipate dust containing resin powder, which is a hygiene problem, and the health of workers can be protected. Furthermore, since the process involves simply peeling off the sheet, the processing time is short and requires almost no effort, resulting in a marked improvement in productivity. Then, the treated surface is significantly activated by the formation of an uneven surface by the cloth, the exposure of unreacted functional groups by peeling, the induction of raised projections, etc., and the adhesion can be greatly improved. Furthermore, the sheet 1 used in the process is also carved with irregularities on its surface, and the impregnation of the unsaturated polyester resin into the fibers can be stopped at that position, which makes the work more reliable and improves adhesive strength. It is essential. (Example) When molding a septic tank using FRP, the joint portion between the body and side portions was positioned on the mold in advance before molding. Then, in that position, a sheet was laid in which a cloth body made of plain-woven polyester fibers having a thickness of 150 denier and a membrane body made of a polyester film having a thickness of 12 μm were integrated by heat welding. After that, the viscosity is 3.2P and the thixotropy is placed in the mold.
A resin solution prepared by mixing the unsaturated polyester (3.3) and its curing agent (methyl ethyl ketone peroxide) was poured into a mold while mixing glass fibers, and left for 24 hours to harden. The edges of the sheet were then separated by hand to expose the active interface at the joint. The results of an adhesion test at the interface were as follows.

[Table] As a result, it was revealed that the interface produced by the method of the present invention has a strong adhesive force that causes the destruction of the base material, and it is inferred that the adhesion is due to chemical bonding rather than simply physical adhesion. Of course,
It was confirmed that it has superior adhesive strength to any other adhesive.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Figure 1 is a partially enlarged front view of a sheet, Figure 2 is a schematic side view showing the method of the present invention, and A shows a part of the sheet cast into a mold. An enlarged longitudinal sectional side view, a partially enlarged longitudinal sectional side view in a state where B is removed from the mold, and a partially enlarged longitudinal sectional side view in which C is a state in which the sheet is peeled off. 1...sheet, 2...cloth body, 3...membrane body.

Claims (1)

[Scope of Claims] 1. In the molding process of unsaturated polyester resin, the parts that need to be joined after molding are positioned in advance on the mold surface, etc., and the unsaturated polyester resin and adhesive properties are applied to the positioned parts. A sheet that integrates a cloth body and a membrane body that stops resin impregnation is laid, then an unsaturated polyester resin is poured into the mold and cured, and then the sheet is peeled from the surface of the solidified resin, A method for improving adhesion on the surface of an unsaturated polyester resin, characterized by exposing an interface rich in activity by the peeling action of the sheet. 2. A sheet 1 in which a cloth body 2 having adhesive properties with unsaturated polyester resin and a membrane body 3 for stopping impregnation of the resin are integrated.