JPS60135223A - Sandwich molding method - Google Patents

Abstract

PURPOSE:To obtain a sandwich molded product provided with an outer layer having a uniform thickness and a molded product to which random patterning is applied, by limiting the injection rate of a sandwich molding apparatus and the thickness of a molding space. CONSTITUTION:The injection rate Q of a sandwich molding apparatus is set to 503cc/sec while the gap thinkness of a molding space 12 is set to 0.6mm. or more and molding materials 30, 31 are injected into the molding space 12. As the injection of the molding material 30, 31 advances, a second mold 11 is allowed to approach to the side of a first mold 10 along the direction shown by the arrow 33 by a drive means 32. By this mechanism, the thickness H of the molding space 12 becomes narrow and the first mold 10 is contacted with the second mold 11 to confine a molded product in an air-tight state. As mentioned above, by selecting the injection rate Q of the sandwich molding apparatus and the thickness of the molding space 12, a uniform sandwich molded product having an outer layer, of which the thickness is 50mum or more, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a sandwich molding method for producing a molded product by injection molding an inner layer and an outer layer formed around the outer periphery of the inner layer.

BACKGROUND ART In the prior art, as shown in No. 11NK, a first molding material 1 forming an outer layer and a second molding material 2 forming an inner layer are passed from a through hole 3 through a gate 4 into molds 5 and 6. It is injected into the molding space and is filled and molded. The outer layer molding material 1 is made of a weather-resistant acrylic resin, and the inner layer molding material 2 is a strong and relatively inexpensive vinyl resin. Given.

On the other hand, the colors of the outer layer molding material 1 and the inner layer molding material 2 are made different, and the injection volume of the inner layer molding material 2 is increased to cause the inner layer to pierce through the outer layer, so that the colors form a pattern and form a pattern on the molded product. Aesthetically treated.

In such prior art, the injected outer layer forming material 1
The velocity of the inner layer molding material 2 in the mold flow path decreases as the distance from the gate 4 increases, and therefore the thickness of the outer layer 1 near the gate 4 is thin and increases as the distance from the gate 4 increases. For this reason, the weather resistance of the molded product near the gate 4 was poor. Therefore, in order to make the thickness of the outer layer 1 uniform, the thickness of the outer layer 1 is increased radially to maintain the weather resistance of the molded product. For this reason, an increase in the cost of molded products due to an increase in the amount of outer layer molding material 1 used has become a problem. Furthermore, when applying colored patterns to molded products, only changing the injection volume of the molding material can only give a certain pattern, and random coloring makes it impossible to obtain unique products with patterns.

Object The object of the present invention is to provide a sandwich molding method for obtaining a sandwich molded product whose outer layer has a uniform thickness and a molded product with a random pattern.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention. In order to perform sand inch molding, a first mold 10 and a second mold 11 are provided, and a molding space 1 is formed by these molds 10 and 11.
2 is defined. The molding space 12 is selected depending on the form of the molded product. A gate 13 communicating with the molding space 12 is formed in the $1 mold 10, and the molding space 12 of the gate 13
One end on the opposite side communicates with the blowhole 15 of the nozzle 14 .

A nozzle flow path 16 is formed in the nozzle 14 and is connected to the blowhole 15 , and the nozzle flow path 16 is arranged in a straight line with the front r gate 13 . A first molding material supply channel 17 communicating with the channel 16 is formed in the nozzle 14 in its thickness direction. Nozzle touch surface 1 of first molding material supply channel 17
8 is provided with a plasticizing means 19 for plasticizing and supplying an outer layer molding material, such as an acrylic resin. Nozzle 14 is fixed to cylinder 21 by screw 20.

The internal space 22 of the cylinder 21 is connected to the flow path 16 of the nozzle 14.
, and a right cylindrical surface 24 extending in a straight line from the large diameter end of the conical surface 23 .

A rod-shaped screw 25 is disposed in this internal space 22 so as to be movable in its axial direction (left-right direction in FIG. 2(1)). The screw 25 is composed of a screw portion 26 and a tip portion 27, and the tip portion 27 is configured to be able to be inserted snugly into the nozzle channel 16. As shown in FIG. 2(2), when the tip 27 of the screw 25 is inserted into the nozzle flow path 16, the free end 28 of the tip 27 extends to the vicinity of the blowhole 15. At this time, the screw 26 has an outer circumferential surface that can substantially exactly contact the conical surface 23. The screw portion 26 is configured with an external thread force, and in this way, injection molding of the so-called one-piece in-line type is possible.

For sandwich molding & plasticization method 1
The acrylic resin 30 as the outer layer molding material from 9 is made to flow into the nozzle flow path 16 from the nozzle touch surface 18 via the first molding material supply flow path 17 in a plasticized state. At this time, the screw 25 is moved backward to the right in FIG.

Next, the screw 25 is driven to rotate around its axis, and the inner layer molding material, for example, the vinyl resin 31, in a plasticized state, flows into the internal space 22 of the cylinder 21, thus forming the nozzle flow path 16 and the nozzle flow path 16 side of the cylinder 21. Gt in the internal space 22 of the acrylic resin 30 as the outer layer molding material; in the plasticized state, and in the acrylic resin 30! Next, on the right side of FIG. 2(1), vinyl resin 31 as an inner layer molding material is prepared while being kept under pressure.

Thereupon, the molds 10 and 11 provided in series with the blowhole 15 of the nozzle 14 are opened, and the completed molded product is taken out and the molds 10 and 11 are closed.

Next, tighten the screw 25 using a hydraulic ram, etc. @Figure 2 (1)
The outer layer molding material 30 and the inner layer molding material 31 are moved to the left side.
are sequentially injected into the molding space 12 of the mold 10.11.

Generally, in order for a molded product obtained by sandwich molding to maintain weather resistance, the wall thickness R of the outer layer 3O is required to be at least 50 μm or more, and therefore, a uniform thickness of 50 μm is applied to the outer circumference of the inner layer 31. In order to form the outer layer 30 having a wall thickness of Hmm, the results of an experiment conducted by the present inventor will be described below.0 When molding a flat molded product, the injection rate Q cm3/sec of the sandwich molding machine is: The wall thickness of the molded product is Hcm
The velocity Vcm/sec at a position where the molding material is a circular plate with a radius rcm centered on the axis of the gate 13 can be expressed as V-Q/2yrrH-(1). Therefore, when the thickness J' (H) of the disc-shaped molded product is 0.2 cm, the radius r is 10 cm, and the velocity V in the mold flow path at a position 1 cm away from the gate 13 is 100 cm/sec, the above-mentioned From the first equation, Q=2πrHV =2πXlX0, 2X100 (2).

At this injection rate Q, the mold flow path velocity V at a position 10 cm away from the gate 13 is 10 cm/sec from the first equation.
becomes. Therefore, as can be seen from FIG. 3, the thickness Rmm of the outer layer 30 changes from 0.1 to 0.34 in accordance with the change in the velocity V in the mold flow path, and therefore the thickness of the outer layer 30 becomes unbalanced.

Therefore, when the velocity V in the mold flow path at a position 1 cm away from the gate 13 is 400 mm/sec, Q=503 cc/sec is obtained from the first equation. At this injection rate Q, the velocity V in the mold flow path at a distance of 10 cm from the gate 13 by the first part is 40 cm/see. The thickness of the outer layer changes from o-0o5 to 0.19 mm depending on the variation of the velocity V in the mold flow path from the roughness shown in FIG. Therefore, considering the value A obtained by dividing the change in the outer layer 30 per unit speed dust, that is, the thinness of the outer layer 3o by the difference in mold flow path velocity, in the above example, A = 0.34-0.1. /1000-1.00=0.
00027 (3), whereas in this example A=0.19-0.05/4000-400=0
．． 000039 (4) It can be seen that the uniformity of one wall thickness is improved.

On the other hand, according to the experimental results of the present inventor, when the thickness of the molding space 12 formed by the molds 1o and 11 is 0.6 mm or less, the injection rate Q of the sandwich molding apparatus is 500 cc.
/sec or more, it was not possible to obtain an outer layer 3o having a uniform thickness of 50 μm or more. As a result, 0
．． The sandwich molding method according to the present invention can be suitably carried out for molded articles having a thickness of 6 mm or more. The injection rate Q't of the sandwich molding machine was
: 503 cc/sec, and the wall thickness of the molding space 12 is 0 * 6 mm or more, and the molding material is 30.3
1 is injected into the molding space 12. Molding material 30.31
As the injection progresses, the second mold 11 is moved by the driving means 32.
As a result, it approaches the first mold 10 side in the direction of arrow 33.

As a result, the thickness H of the molding space 12 becomes smaller, and as shown in FIG. 2(2), the first mold 10 and the second mold 1
1 come into contact with each other and the molded product is airtightly confined. In this way, the injection rate Q and molding space 1 of the sandwich molding machine are
By selecting the thickness K as shown in FIG. 2 (2), it is possible to obtain a uniform sandwich molded product whose outer layer has a wall thickness of 50 μm or more, as shown in FIG. 2 (2).

By making the thickness of the outer layer uniform in this way, when sandwich molding molded products that require weather resistance, such as exterior building materials and automobile parts, the outer layer is made of a material with excellent weather resistance, such as acrylic resin, and is relatively An inexpensive material having durability and impact resistance, such as polyvinyl chloride, can be used. Such molded products are weather resistant and have excellent strength, and their production costs are low, so they can be suitably used, for example, in parts for rain gutters.

FIG. 4 is a sectional view of another embodiment of the invention. -4th
The figure is similar in construction to that of FIG. 2, and corresponding parts are given the same reference numerals. What should be noted is that the molded product is not a sandwich molded product, the wall thickness d is 0°6 mm or less, and the inner layer 31 and outer layer 30 are injection molded using different colored materials, and are randomly placed on the substrate 50. Try to draw a color pattern,
That's what happened.

According to the experimental results of the present inventor, when the thickness d of sandwich molding is 0.6 mm or more, in order to pattern the substrate 50, the injection volume of the outer layer material is increased so that the inner layer 31 covers the outer layer 30. A pattern is created on the substrate by a method of making it break through, so-called marble molding. When a flower pot or a vase is decorated with a pattern using this marble molding, the area near the gate 13 of the molded product becomes the color of the outer layer 30, as shown in FIG. The area near the edge becomes the color of the inner layer 31, making it impossible to apply a random color pattern on the substrate 50.

Therefore, the thickness d of the molding space 12 between the substrate 50 as an object loaded in the molds 10 and 11 and the mold 10 is set to 0.6.
If injection molding is performed with a thickness of less than 1 mm, the inner layer 31 and outer layer 30 will not form a sandwich shape as shown in FIG. 5(2), and therefore a completely random color pattern can be formed on the substrate. In this way, the wall thickness d of the molded product
By setting the thickness to 0.6 mm or less, flower pots, vases, etc. can be easily decorated with patterns, which greatly improves productivity.

Effects As described above, according to the present invention, by regulating the injection rate of the sandwich molding device and the thickness of the molding space, a molded product having a uniform outer layer can be obtained, so when a relatively inexpensive material is used as the outer layer. By reducing the thickness of the outer layer material, it is possible to reduce the cost of the molding material and improve productivity.

[Brief Description of the Drawings] Fig. 1 is a cross-sectional view showing the prior art, Fig. 2 is a cross-sectional view showing the operating state of an embodiment of the present invention, and Fig. 3 is a cross-sectional view showing the operating state of an embodiment of the present invention. FIG. 4 is a sectional view showing another embodiment of the present invention, and FIG. 5 is a perspective view of a sandwich molded product obtained by the embodiment of FIG. 4. 1.14... Nozzle, 2.30... Outer layer, 3.31
...Inner layer, 5,6,10.11...Mold, 12...
・Molding Space Agent Patent Attorney Kei Nishi Part 1 (1) Figure 5 Procedures Amendment Book May 17, 1980 1. Indication of Case Patent Application 1982-248133 2. Name of Invention Sand Inch Molding Method 3 , Relationship to the case of the person making the amendment Applicant Address Name (583) Matsushita Electric Works Co., Ltd. Representative 4, Agent Address Shinkosan Building Kokusai EX, 1-13-38 Nishihonmachi, Nishi-ku, Osaka 0525-5985 IM 'l'AP'
l' J International FAX GIl&Gl (06)538-0
2476, Drawing 7 subject to correction, Contents of correction (1) Figure 1 will be corrected as shown in the attached sheet. (21 Figure 2 (2) is corrected as shown in the attached sheet. Emino 1)

Claims (1)

[Claims] - In a sandwich molding method in which a first molding material forming an inner layer and a second molding material forming an outer layer are injected into a molding space formed by a pair of molds to cover the outer periphery of the inner layer with an outer layer, The injection rate of molding material is 500 cc
/sec or more and the thickness of the molding space is 0.
A sand inch forming method characterized in that the thickness is 6 mm or more.