JPS5923972B2 - Patterned molding method for synthetic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a patterned molding method for unsaturated poly9ester resin, and in particular, by passing through the steps of thickening, redifferentiation, recombination, and forming into a sheet of a raw resin compound, It is an object of the present invention to easily produce an unsaturated polyester resin molded article having a characteristic joining pattern and arrangement pattern even in a complicated shape.

Unsaturated polyester resin (hereinafter abbreviated as UP resin) molded products have advantages such as excellent strength, heat resistance, and low-pressure moldability, so they are widely used for interior products such as bathtubs and washbasins, building materials, and automobile parts. It is used.

However, when considering the above-mentioned uses, it is extremely preferable to have a pattern as well as a single color in order to increase the product value. The method of adding patterns to UP resin molded products is to set a woven fabric, non-woven fabric, paper, or glass fiber mat with a preprinted pattern on the top surface and impregnate it with the molding material, and then add a reinforcing rigid material to the back side. A method is known in which a molding material (such as plywood) and a molding material are set and bonded together. However, when using this method, the pattern obtained is the back side pattern, and it is not possible to give the same pattern as the front side to any arbitrary cross section of the inside, so post-processing is not possible and the objects can be limited. Furthermore, since it is a surface pattern, it lacks depth and a natural sense of reality, and in complex shapes such as deep drawing, the pattern may be overlapping, missing, or discontinuous at joints of patterned fabric, paper, etc. Because of these problems, there is also the drawback that the molded shape is limited to a flat shape. In addition, many other molded products and molding methods are known under the name of artificial marble, but most of them are due to incomplete mixing of coloring agents with resin, and the resulting patterns are completely random. Therefore, the pattern boundary line cannot help but become unclear.

One method for eliminating the drawbacks of the conventional patterning method for UP resin molded bodies ("Method for manufacturing patterned molded bodies" according to a patent application dated April 6, 1970) was proposed by a group to which the present inventor belongs. has already been proposed by.

This method involves the following techniques a) to (6), namely (a)
Preparing two or more UP resin compounds, (b
) thickening the resin compound; (c) dividing the thickening compound into fine pieces; (4) filling the finely divided compound into a predetermined mold and molding it under pressure.

It is characterized by including.

According to this method, the disadvantages of the conventional method as described above are eliminated, the pattern is almost the same from the surface to the inside, and the appearance and texture of B1 natural stone is achieved by combining small parts with clear boundaries. It has been confirmed that a UP resin molded article can be obtained. However, the above method does not require a subdivision compound (hereinafter referred to as “
Since the filling of PMC (abbreviated as ``PMC'') into the mold is essentially based on the scattering method, the mold has a large rise angle b.
When there is a vertical portion or a vertical portion, it is difficult to smoothly fill the PMC into the mold.

Therefore, the filling in the rising part b is caused by P during heating and pressure molding.
In many cases, this is due to the melt flow of MC, and in such raised areas, the above-mentioned method of clarifying the pattern boundary (hereinafter referred to as "
The greatest advantage of the PMC method) will be lost. This method provides an improved method of the above-mentioned PMC method.The 1UP resin compound is once thickened and then finely divided.The resulting PMC is then combined into a sheet form under pressure to form a sheet molding compound (hereinafter referred to as "SMC"). ) and placing it in a mold, the above-mentioned PMC
This is based on the knowledge that the operational difficulties of the PMC method can be solved, and that a patterned synthetic resin molded article can be obtained that has a wider range of objects to be molded using the PMC method and has better pattern boundary properties.
Therefore, the patterned molding method of synthetic resin of the present invention is based on the following technique a)? c): B) step of thickening two or more types of UP resin compounds and dividing them into PMC; (b) combining the obtained PMCs under pressure to form SMC. (c) a step of placing the above-mentioned SMC in a predetermined mold and molding it under heat and pressure.

Another patterned molding method of synthetic resin according to the present invention involves laminating a separately prepared B-sheet molding compound containing reinforcing fibers together with the sheet molding compound, and heating both. It is characterized by being integrally molded under pressure.

Hereinafter, the present invention will be described in more detail with reference to the drawings as necessary.

In this manual, "UP resin compound" means
Esterification products of unsaturated dibasic acids or saturated dibasic acids added thereto and glycols, substantially non-crosslinked brepolymers of saturated or unsaturated dibasic acids and unsaturated alcohols, and these U obtained by dissolving an unsaturated polyester selected from a mixture of in a reactive monomer having an ethylenically unsaturated bond such as styrene or methyl methacrylate, and adding a polymerization inhibitor as necessary.
It means a molding material that further contains low-shrinkage additives, colorants, fillers, hardeners, thickeners, etc. as necessary to the P resin, and has thickening and hardening properties by itself.

0 to 40 parts of a thermoplastic polymer such as polystyrene, polymethyl methacrylate, etc. as a low-shrinkage additive to 100 parts by weight of UP resin (hereinafter, the limit unless otherwise specified, "parts" are parts by weight based on the same standard). However, the filler includes 0 to 500 parts of calcium carbonate, talc, silica sand, glass fiber strands (preferably relatively short ones of about 2 to 61 m), etc.
The curing agent contains 0.2 to 3 parts of an organic peroxide such as t-butyl perpenzoate or cumene hydroperoxide; the thickening agent contains 0.1 to 5 parts of MgO, Ca(0H). ，
Alkaline earth metal oxides or hydroxides such as: are used as necessary.

However, when using a crystalline unsaturated polyester, which is an esterification product of a symmetric aliphatic glycol and fumaric acid or a lower alkyl ester of fumaric acid, as the unsaturated polyester in the UP resin, a thickening agent is especially necessary. It is possible to thicken the UP resin compound by crystal growth without addition. In this way, two or more types of UP resin compounds having a color tone and texture according to a predetermined design are prepared, and after each is placed in an appropriate container, the mixture is heated at room temperature to 40°C if a thickener is used. A thickened solid compound can be obtained by aging at a moderate temperature for one to several days, or in the case of using crystalline unsaturated polyester, by lowering the temperature from a heated state to room temperature or a slightly cooled state. .

The thickened compound thus obtained is then
PMC is finely divided into pellets or sticks of a shape and size that conform to a predetermined mosaic shape using any solid fragmentation means such as a crusher, cutter, beletizer, granulator, preforming press, etc. (Fig. 1a)
or b). Here, the term "comminuted" means to be made relatively small compared to the thickening compound, and does not determine its absolute size. however,
In order to give a pattern similar to natural stone, PMC having a diameter of about 1 to 20 Tfm is preferably used. The PMC grains obtained in this way are either heated (maintained for a short time below the curing temperature) to the extent that they do not harden but become sticky, or the PMC grains are made sticky by suppressing thickening before preparing the PMC grains. The SMC2a,
2b (Figure 2, hexagrams a and b). Then the obtained SM
C2 is placed in the mold 3 (Fig. 3) and molded under heat and pressure (
4) to obtain the desired molded body (FIGS. 5a and 5b).

The molded product obtained by this method has all the characteristics of the PMC method, such as a clear boundary pattern and a pattern that is almost the same on the inside of the surface. However, since it is difficult to mix reinforcing fibers with a length exceeding the particle size of PMC, it tends to be weak in terms of strength. In such a case, SMC obtained by preforming the above PMC (hereinafter [P
Separately from the PMC-SMC (referred to as "MC-SMC"), an SMC mixed with reinforcing fibers (referred to as "reinforced SMC") is prepared, and as shown in Figure 6, when placing the PMC-SMC in the mold, the PMC
-This reinforced SMC is placed on top of SMC2 on the opposite side of the product surface.
5 (FIG. 6) and then heating and press-molding it is preferable. When such a laminated structure is adopted, the effects of the present invention are more effectively exhibited.
That is, when manufacturing a single-layer molded product as shown in FIG. 5, molding is possible even with the conventional PMC method, even though there is a problem with the flow of the pattern in the raised ridges.

Furthermore, if the upper mold 4 is brought into contact with the PMC after it is placed on the lower mold 3, and then heated to the molding temperature, the flow of the pattern can be alleviated, although the workability will deteriorate. However, when obtaining a laminated molded product, if the material to be stacked with SMC is a so-called free-flowing PMC, the thickness of each layer will be non-uniform in the molded product obtained through subsequent heating and pressure molding. This is because it is difficult to avoid. In order to obtain a laminated molded product as described above, the molding shrinkage rates during curing of PMC-SMC and reinforced SMC are measured in advance and made to be approximately equal, resulting in a molded product with very little warpage. is obtained.

The production of the reinforced SMC is not different from the usual method, and the reinforcing fibers selected from strand-shaped, roping-shaped, cross-shaped or mat-shaped glass fibers are preferably used, and the fiber length is preferably 3.
Impregnate the UP resin compound into the material more than m, or
Alternatively, the former is dispersed and mixed into the latter to form a sheet, and the viscosity is further thickened in the same manner as in the case of PMC above to form a reinforced SM.
Let it be C.

The reinforcing fiber content in the reinforcing SMC is preferably about 5% by weight or more. Hardened reinforcement S for laminated molded products
The thickness of the MC layer is determined depending on the desired strength of the molded product;
The thickness of the SMC layer after molding is 2?2 to give the product a deep mosaic pattern. If the length is preferably 1 m or less, the color of the reinforcing SMC layer can be seen through the resin-rich part formed at the bonding boundary of PMC grains, and mixes with the surface mosaic pattern. Effects can also be obtained.

As described above, according to the present invention, in addition to the advantages of the PMC method in that it provides clear pattern boundaries and a deep mosaic pattern, it is possible to expand the molding objects of the PMC method, such as a bathtub with a large angle. The effect is that molded bodies and laminated molded bodies having raised ridges can be easily produced.

The present invention will now be described in more detail with reference to Examples.

Example: With the formulation shown below, the linear shrinkage rate during molding is 0 in all cases.
．． Two types of PMC (PMC-A and PMC-B) and reinforced SMC adjusted to 3(f) were prepared.

PMC-A was obtained by thickening a compound having the above composition at room temperature for two days and preforming it into a diameter of 57 m using a granulator.

PMC-B was obtained in the same manner as PMC-A based on a compound obtained by removing the yellow pigment from the composition for PMC-A. In addition, the reinforced SMC uses the above SMC compound at a weight ratio of 201:! ) is impregnated into a chopped strand with a length of about 2.5u and a thickness of 5mm. It was obtained by thickening the sheet at room temperature for 2 days. Based on the above molding base material, first mix PMC-A and PMC-B at a ratio of 1:1,
While heating it to 50°C to give it tackiness, it is pressed into a flat sheet with a rolling roller to a thickness of 3mm. PMC-SMC was obtained.

Next, a molded product as shown in Figure 5 (approximate dimensions: maximum width 5
007! Molds 3 and 4 having a length of 500 m and a height of 50 Tm are prepared, and the above PMC-SMC and then the reinforced SMC are placed on top of the lower mold 3, and the upper mold 4 is brought into contact with the mold to cool the mold. 120℃, pressure 100Kf/Cf! Press molding was performed for 10 minutes at i to obtain a molded body. The obtained molded product had a mosaic pattern characterized by clear boundaries and depth, and almost no flow of the pattern was observed even in the upright part.

In addition, the molded body has a bending strength of 10Kf/71171 and an impact strength (Charpy 1) according to Fig. 5.
It had sufficient strength of 10 Kf-Cm/d.

[Brief explanation of drawings]

Figures 1 to 6 are process explanatory diagrams of an example of the patterned molding method for synthetic resin according to the present invention. ．． Figures 1, 2 and 5 are perspective views, Figures 3, 4} and 6 are sectional views, and A and b in Figures 1, 2 and 5 are respectively This is a case where pellet-like PMC and stick-like PMC are used. DESCRIPTION OF SYMBOLS 1...PMC, 1a...Pellet shape, 1b...Stick shape, 2...PMC-SMCl3,4...Mold, 5...Reinforced SMC.

Claims (1)

[Scope of Claims] 1. A method for molding a synthetic resin with a pattern, the method comprising the following steps (a) to (c). (a) a step of thickening and then subdividing two or more unsaturated polyester resin compounds; (b) a step of combining the obtained subdivided compounds under pressure to form a sheet molding compound; (c) the above-mentioned sheet. A process in which molding compound is placed in a predetermined mold and molded under heat and pressure. 2. A patterned molding method for synthetic resin, characterized by including the following steps (a) to (c). (a) a step of thickening and then subdividing two or more unsaturated polyester resin compounds; (b) a step of combining the obtained subdivided compounds under pressure to form a sheet molding compound; (c) the above-mentioned sheet. The molding compound is placed in a predetermined mold and molded under heat and pressure.At this time, a separately prepared sheet molding compound containing reinforcing fibers is laminated together with this sheet molding compound, and both are laminated under heat and pressure. The process of integrally molding the