JPH0661854B2 - Molding method for edgeless moldings based on mold closure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a rimless molded article based on mold closing for the purpose of molding a brimless rimless molded article partially or wholly.

[0002]

2. Description of the Related Art Conventionally, for molding a molded article having no edge, a molded article including a brim-shaped edge that accompanies mold closing is first obtained, and then a part or all of the edge is cut and removed. As a result, a molded product having a target shape and no edges was obtained.

[0003]

According to the above-mentioned conventional molding method, since unnecessary parts must be removed after molding, not only time and labor are required for post-processing, but also high-efficiency mass production is possible. It is difficult to do so, and the working environment is deteriorated by the dust at the time of cutting, which causes a problem of processing cutting waste, and there are many problems with a decrease in yield.

[0004]

A part of a brim-shaped edge to be removed from a molded product molded by a conventional molding method, or
Place a holder having a size and shape that includes everything (it is used as a copy holder in the mold of the injection molding die) in the lower mold, and place a reinforcing material mat so that it does not substantially overlap the holder. Then, the upper mold is lowered to close the mold, and the inside of the mold is filled with a liquid resin and cured to obtain a cured product. The molding is removed from the cured product to obtain the desired molded product. In the above-mentioned cured product, the retainer and the other fiber-reinforced thermosetting resin (hereinafter referred to as FRP) part are integrated, but the resin part bridging between each other does not contain a reinforcing material, so the FRP part It is significantly more fragile than that of, and it is easy to remove the obturator.
That is, the present invention is a molding method utilizing the fact that there is a great difference in strength between the bridging portion and the FRP portion containing a reinforcing material.

The present invention is an injection reaction molding (usually R-type) using a liquid resin containing SMC method, BMC method and reinforcing material short fibers.
It cannot be applied to a method of moving and molding a gruel containing reinforcing short fibers in a mold, such as the method (abbreviated as RIM). In those molding methods, a cured product obtained by connecting a resin containing short fibers between the retainer and the other portion is obtained, so that it is not easy to remove the retainer from the cured product. Therefore, when a liquid resin containing short fibers is used, it is outside the scope of the present invention.

Any molding method suitable for carrying out the present invention can be used as long as it is a molding method in which a reinforcing material is previously placed in a mold as described above, and a liquid resin containing no reinforcing material is impregnated and cured. A molding method may be used. Examples thereof include a resin transfer molding method (RTM method), an injection reaction molding method (RTM method), and a cold press method. In the molded product obtained by these molding methods, the edge of the molded product that accompanies the mold closing appears like a flange on the outside. The presence of this brim-shaped edge is often unfavorable for the use of the molded product. Moreover, in those molding methods, the operating pressure is 20 kg / cm ²
Since the low pressure is below, and in most cases the resin type is used,
The seam (parting line) of the lower mold and the upper mold is one straight line, or it is practically impossible to select other than a few bends. This too limits the shape of the edges of the molding. As described above, the present invention makes it possible to largely loosen these shape restrictions of the edge of the molded product by using the retainer.

The material of the holder used in the present invention is not particularly limited as long as it can withstand the mold temperature during curing. Therefore, there is also a method in which a desired silt is made beforehand by machining or the like and used, or a molded product containing a reinforcing material mat is molded without the silt, and cut out from there to make the silt.
Although the cut-out pieces can be used as they are as a stand, the thickness of the cut-out pieces can be adjusted to 0. to prevent scratches on the mold by the stand, discharge air in the mold, and smooth the flow of the liquid resin. It is desirable to reduce the size by about 2 mm to 0.5 mm before use. For the latter purpose, it is also effective to dig a groove having a depth of about 0.5 mm to 1 mm on one surface or both surfaces of the holder, or to substantially form the groove as in the second embodiment. After curing, in order to easily remove the obturator from the cured product for reuse, make the surface of the obturator and its surrounding cross section sufficiently smooth and finish with a fluororesin.
Alternatively, it is desirable to apply a release agent. To place the holder on the lower mold, it is sufficient to install it in the correct position on the lower mold, and it may be attached to the lower mold using a double-sided adhesive tape or the like, but there is almost no need for this. As a general rule, place the placement block so that it does not overlap the reinforcement mat. Again, there is no difficulty if the reinforcement mat is cut or preformed carefully. Also, if they overlap in the visible part, cut the mat in place, or use Cellotape (registered trademark) to prevent the mat from overlapping the obsole, Just straddle the edge. In order to remove the hardened material from the cured material after molding, the hardened material can be taken out of the mold and pushed easily or by applying a twisting force to the hardened material. Also in the mold, it may come off when the edge of the holder, that is, the brim portion is lifted or a force is applied to the inside or outside of the mold. As a general rule, the reinforcing material mat and the obturator do not overlap, but when some of the fibers of the mat are frayed and overlapped with the obturator, or for reasons such as securing an air discharge path and a resin path, Most mat layers do not overlap the obturator, and a thin layer of mat may be molded over the obturator. Even in this case, if you prune the interface between the obturator and other parts with a sharp knife, the obturator will come off, and then the fibrous material of the obturator part can be cut, so compared to the conventional method that does not use the obturator. , The present invention is much easier. In this case as well, F
Since the bridging portion of the RP portion has a greater strength difference than the FRP portion, it is included in the present invention. In the claims of the present invention, the word “substantial” in the claims refers to such a case. A flexible film of polyethylene or the like is attached to one or both sides of the end of the retainer by a double-sided adhesive tape so that the end of the retainer and the reinforcement mat will not be overwhelmed by about 3 mm to 15 mm. , The mat can be under or between the films, but this is not a requirement.

Liquid resins suitable for the practice of the present invention are generally radically polymerizable liquid resins such as α, β-unsaturated polyesters, various vinyl esters and urethane (meth) acrylates, epoxy resins, A non-radical curing resin such as a phenol liquid resin may be used. Also, as will be seen in Example 2, RIM that simultaneously feeds various raw materials that can be urethane methacrylate and various materials for curing the urethane methacrylate into the mold to perform radical curing following the ionic reaction. Since molding can be performed, the liquid resin used in the present invention includes a mixture of such raw material stages.
The handling of these resins, the curing agent for curing, the formulation of the resin mixture containing the release agent, the method of supplying to the mold, the curing conditions, etc. are the same as in the case of normal molding without the use of a mold. However, generally known techniques can be applied as they are.

The reinforcing material mat used in the practice of the present invention is no different from that conventionally used in the RTM method, the RIM method and the like. Most preferred is a preformed reinforcement mat, although heat-flexible glass fiber mats are commonly used. The mat may be a woven fabric or a knitted fabric, and a mat made of carbon fiber, vinylon fiber or the like may be used as the reinforcing material. The most common form of mat is a continuous short fiber mat, and some chopped strand mats are also suitable for use. How to choose these is also the conventional R
This can be done with knowledge of the TM method and the like. Further, there is no particular need to consider for implementing the present invention.

In practicing the present invention, there is no particular need to change the material and design of the mold from those of the conventional mold, and it can be used for practicing the present invention without any processing. As the material of the mold, a resin mold that has been widely used in the past is sufficient, but a metal mold such as an electroformed nickel mold and aluminum can also be used.

[0011]

[Function] The mold and the reinforcing mat are made to exist in the mold without being substantially overlapped with each other, and the cured resin obtained by acting the liquid resin on them and the part where the reinforcing mat is present. Since the strength of the bridge part does not include the reinforcing material mat, it is much weaker than other parts. Therefore, the obturator can be easily removed from the molded product.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. All "parts" and "%" are "parts by weight" and "% by weight".

[0013]

[Embodiment 1] The shape shown in FIG. 1 is a square shape having a bottom whose length direction, bottom side and top side are 25 cm and 30 cm respectively, depth direction and bottom side are respectively 20 cm and 25 cm, and height is 20 cm. It is a pot with a rim of 3 cm in width around the upper side that is formed along with the mold closure and projects outward in the shape of a tsuba, and is a molded product that does not include a part of the sloped part including the tsuba. . The lower mold is an electroformed mold and the upper mold is an aluminum mold. The airtightness of the edges where the upper and lower dies meet, that is, the outer side of the rim, is made by surrounding the upper die with silicone rubber. Deaeration in the mold is performed through holes 16 having an inner diameter of 8 mm at the four corners of the upper mold. The liquid resin injection port 15 is at the center of the upper die 12 when viewed from above (FIG. 3). Using this type, R
A molded product was molded by the TM method. That is, two pieces of thermoplastic Uniflo glass mat U-720 (made by Saint-Gobain, France, 450 g / m ² ) are placed in the lower mold, and the mold is closed and at room temperature, a multiflow injection pump 10020 type (manufactured by Keiyo Seisakusho) is placed. Using, Percure A (trademark of NOF CORPORATION, acetylacetone peroxide) 1.0%, concentration 6% cobalt naphthinate, 0.08%, mold release agent Moldbits INT1858 (commercial display American Accelerator Plastic Research Laboratories, Inc. ) 0.6%
Unsaturated polyester Yupika 4001A (trade name: Nippon Yupica) containing 30% of calcium carbonate powder SS-80 (manufactured by Nitto Koki Co., Ltd., average particle size: 2.5 μm), porridge (hereinafter referred to as dope), pressure 3.2 kg. / Cm ² was injected through the nozzle 14. After 1 hour, the mold was opened and a molded product having a wall thickness of 3 mm was obtained. The shape of this molded product was as shown in FIG. 1, but it was a complete molded product with no missing parts.

The shape shown in FIG. 1 was made from this molding using a saw. At this time, the obturator used in the present invention was made from the one containing a part of the edge obtained by cutting. In other words, sanding both surfaces of the excavated sticker to give a thickness of about 1 m
m, and coated with Teflon (registered trademark) to make it especially easy to remove the insert from the cured product after molding. The thickness of the coating after coating was 0.4 mm less than that before sanding. Next, place this holder in the lower mold, place a uniflo glass mat where there is a cut so that it does not overlap with it, clamp the mold in exactly the same way as above, and harden it including the holder in the lower mold. I got a thing. The denshi was slightly covered with the cured product of the dope. When the collar portion of the obturator was placed inside the mold, the obturator was easily removed and the attached dope was easily removed, so the obturator could be reused as it was. Since the hardened material in the mold has no sills,
It was possible to release from the mold very easily, and the desired molded product 8 shown in FIG. 1 was obtained.

[0015]

COMPARATIVE EXAMPLE 1 Comparative example 1 is the same as the case where the above-mentioned part to be the nest is cut out from the molded product with a saw. The cutting took about 40 minutes because it was hard, tough and labor consuming because the molded product contained a reinforcing mat and calcium carbonate powder.
In addition, the saw blade became blunt quickly and could not be used with five blades.
Moreover, dust is generated by sawing and the working environment deteriorates,
Although it is possible to make several pieces shown in Fig. 1, it was recognized that mass production is impossible.

[0016]

Example 2 It has the shape shown in FIG. 1 except that it has no collar at all.
Example of obtaining a molded product having a raised edge with a bowl height of 10 mm.

Similar to the first half of Example 1, it is shown in FIG. 1 (however, a molded product having a notch and a flange around the periphery). Next, at a height of 19 cm, the molded product was sliced into rings, and a brim to be finished on the stand and a rising slope portion with a height of 1 cm were obtained. With respect to this product, the thickness of the back surface of the collar and the sloped part following it were sanded to 0.5 mm to 2.5 mm, and holes having an inner diameter of 8 mm were punched at four corners corresponding to the air vent holes of the upper mold. Moldbits INT1585 was applied as a release agent, and finished as a retainer.

Next, in order to secure an air vent passage, prior to placing this retainer, a thickness of 0.5 mm is placed on the lower mold collar.
A 25 mm × 25 mm plate made of a ball plate was placed in contact with the inner edge of the brim of the mold as shown in FIG. In FIG. 2, 1 is a contour line of the lower mold, 2 is a strip-shaped protrusion having a triangular cross section provided so as to be in contact with the silicone rubber of the upper mold, and 3 is a position corresponding to an air vent hole attached to the upper mold. The mold has nothing attached here. 4 is a place where the flange of the molded product is formed, 5 is the ball plate, which are placed in contact with the inner edge 6 of the lower mold collar, There is a gap of about 5 mm in width. Reference numeral 7 indicates the bottom of the lower mold, but there is a space at the height of the lower mold guard. After placing the ball plate as described above, the holder 9 was placed thereon (FIG. 3). This ball plate has substantially the same function as digging an air passage having a depth of 0.5 mm in a holder having a thickness of 3 mm. Next, the lower mold is chopped strand mat (for Fuji fiber glass 450g / m ² RTM)
Two of them were installed so that their upper ends were directly under the obturator. Close the mold and prepare to inject the liquid resin.
Held in.

FIG. 3 is a sectional view taken along the line AA in FIG. 2 with the upper die and the lower die being combined (intermediate). However, mold heating and heat-retaining additives were omitted. In the figure, 10 is a lower mold, 1
1 is a chop strand mat, 12 is an upper mold, 13 is a rubber strip, and 14 is a nozzle for injecting a liquid resin.

Liquid A and liquid AB were prepared as follows on the assumption that this molding is performed by the RIM method.

Liquid A: 783 parts of toluene diisocyanate (Nippon Polyurethane T-80), 64.8 parts of 2-hydroxyethyl methacrylate, methyl methacrylate (MM
A) 70.1 parts, diethylaniline 0.2 part, a solution of vinyl polysuccinate / MMA = 33/67 70.3 parts, alumina B-103 (Nippon Light Metals, average particle size 8 μ) 163.
3 parts Solution B: benzoyl peroxide solution 8.6 parts (NIPPER NOF CO., LTD. Niper BMT), glycerin dimethacrylate (NOF CORPORATION Blemmer GMR) 112.5 parts, di-n-butyltin dilaurate 0.81 part, MMA 100 parts, Alumina B-103 150 parts, Moldbits INT1858
4.5 copies

Since there is actually no RIM molding machine, A, B
Immediately after mixing the liquid, the pressure is quickly set to 0.8 kg / c using nitrogen pressure.
It was fed into the mold through a nozzle at m ² . After 6 minutes the cure was complete and the mold was opened. The holder was easily removed by simply lifting it up, and the hardened material that adhered to it could be easily removed and reused. By demolding, it was possible to obtain a square pot-shaped molded product having a brim-shaped, steep slope without edges. The edges were easily finished with a sandpaper.

[0023]

[Embodiment 3] In the mold of Embodiment 1, the denseness of the mold is brought into contact with the upper mold silicone rubber and the lower mold belt-shaped projections, and the air in the mold is discharged and the excess liquid resin overflows. It is designed to be done through air vent holes provided at the four corners of the mold. The molded product having a solid edge in Example 2 can also be obtained by using a mold that does not have an air vent hole and is not a dense type made of silicon rubber.

The mold used in this example is the same as that used in Example 1, except that the air vent holes provided at the four corners of the upper mold are closed with cellophane tape (registered trademark) and the silicone rubber is removed from its holding groove. It is a thing. This type is also RTM
, Which is widely used for the reinforcement mat, is designated by reference numeral 2 in FIG.
It is installed beyond the strip-shaped protrusion with a triangular cross section,
When the mold is closed, the reinforcement mat is strongly compressed by the compression part formed between the protrusion and the upper mold.

The procedure of the whole procedure of the third embodiment is the same as that of the second embodiment.
Is the same as. First, the same as in the first half of Example 1 is shown in FIG. 1 (however, a molded product having no notch portion, a flange around the flange, and a reinforcement mat on the outer periphery of the flange was obtained). This molding was sliced in the same manner as in Example 2 to obtain a square collar having a reinforcing mat around it, which was to be processed into a mold. After peeling off the reinforcing mat, the square brim portion was cut so that the width of 3 cm was narrowed to 1 cm from the outer periphery, and finished in the same manner as in Example 2 to prepare a denshi.

In order to place the retainer on the lower mold, the same concept is shown in FIG. However, the ball plate is 16 mm
It was arranged in a square of 25 mm and a thickness of 0.5 mm, and its 16 mm side was in contact with a raised wall having a height of 1 cm around the inside of the obturator. Next, a strip-shaped reinforcing material mat having a width of about 5 cm was prepared, and two mats were placed so as to contact the outer periphery of the holder and cover the strip-shaped projections 2 having a triangular cross section of the lower mold. After closing the mold, molding was carried out in exactly the same manner as in Example 2. After opening the mold, the reinforcing material mat on the outer periphery was removed, and then the debris was removed to form a desired brim without a brim edge. A square pot-shaped molded product having a slope was obtained.

[0027]

According to the present invention, the reinforcement mat is placed on the lower mold,
In the molding method in which the reinforcing resin mat is impregnated with the liquid resin before or after the mold is closed, a molded product having a brim-shaped edge around the mold is obtained as the mold is closed. It is possible to obtain a molded product without Further, conventionally, the brim-shaped edge has been a straight line or one in which it is bent once or twice. It was a constraint from the convenience of matching the lower mold and the upper mold. However, according to the present invention, not only the design of the mold itself does not change, but there is no brim-shaped edge, and the edge of the molded article rises like an SMC press molded article or a thermoplastic resin injection molded article. It is also possible to form a curved line. Furthermore, it is possible to make the curve that is undercut with respect to the rising direction. That is, the present invention is
The degree of freedom in the shape of the edge of the molded product such as the RTM and RIM methods is remarkably increased as compared with the conventional molding by those. This means that the range of application of these molding methods has expanded, and the industrial value of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a perspective view of a molded product lacking a portion including a part of an edge based on a mold closing molded according to the present invention.

FIG. 2 is a plan view in which a ball plate serving as a base of the holder is placed on the lower mold portion.

[FIG. 3] Similarly, the upper die and the lower die are combined (intermediate), and A in FIG.
-A sectional view with a part omitted at the position A.

[Explanation of reference numerals] 1 contour line of lower mold 2 strip-shaped projection having a triangular cross section provided so as to contact the upper mold silicon rubber 3 position corresponding to the air vent hole of the upper mold 4 place where the flange of the molded product is formed 5 Ball plate used as a stand for the holder 6 Inner line of the collar 7 Bottom of the lower mold 8 Molded product 9 Lower mold 10 Lower mold 11 Chop strand mat 12 Upper mold 13 Rubber strip 14 Nozzle 15 Pouring 16 Air vent hole

Claims (3)

[Claims] 1. A molding method in which a reinforcing resin mat is impregnated and cured with a liquid resin and a molded product is obtained using a mold,
A lower part of a mold having a shape including part or all of a brim-shaped edge portion around the upper edge of the molded product is installed in the lower mold, and the lower mold is arranged so that the reinforcement mat does not substantially overlap with the former. Installed inside, then close the mold by fitting the upper mold to the lower mold, impregnate the reinforcing material mat with the liquid resin and cure it, and before or after taking out the molded product from the mold, remove the mold from the molded product. A method for molding a rimless molding based on mold closing, characterized by removing. 2. The retainer includes a collar portion.
A method for molding a rimless molding based on the described mold closure. 3. A method for molding a molded article having no edge based on mold closing, which is obtained by cutting out a molding from a molding molded without using the molding and processing the molding.