JPS6054825A - Manufacture of laminated injection molding - Google Patents

Abstract

PURPOSE:To manufacture laminated molding such as steering wheel of automobile, which is lighter in weight, and the like by realizing extremely thin skin thickness around an insert by a method wherein the insert heated up to 5-100 deg.C in advance is placed in a mold and then injection molding is done. CONSTITUTION:Skin layer forming resin, the quantity of which is not enough for filling-out a mold cavity, is injected and core formation resin containing foaming agent is successively injected before the inner surface of the injected skin formation resin solidifies in order to manufacture molded parts containing a part of the insert or the whole insert within the laminated injection foam. In this case, because the insert is heated up to 5-100 deg.C in advance, the remarkable lowering of viscosity of the resin of the surface of the insert due to the lowering of temperature is prevented from occurring, resulting in allowing the skin formation resin to flow in all the corners of the molded part and reducing the thickness of skin around the insert.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a laminated injection molded article (inner part 6) consisting of a core layer and a skin layer of a long article containing an insert, such as a steering wheel for an automobile.

The present invention provides a JE4 injection molded product with a lighter weight, since the thickness of the skin layer around the insert can be made extremely thin.

Conventionally, in the case of laminated injection molding of long objects such as automobile steering wheels (2), in the case of molding using inserts, a skin is formed on the peripheral area of the insert, which affects the product performance and value of the molded product (2). The weight of the skin layer resin around this insert was the second major obstacle to reducing the weight of laminated injection molded products.

In particular, when the insert is large (as in the case of an automobile steering wheel), the wall thickness of the molded product is thin and the volume compressed by the foam is small. The basis weight is not much different from the case where the core part is not made of foam.The present invention compensates for these drawbacks and provides a lighter laminated injection molded product.

The present invention is a method for manufacturing a laminated injection molded product, which is characterized in that the thickness of the skin layer around the insert is reduced by preheating the insert to 5 to 100 uC to form a lighter laminated structure. .

In other words, in the case of laminated injection molding with an insert, the mold space is filled (the second step is to inject an insufficient skin layer forming resin, and before the inner surface of the skin layer forming resin hardens, it is necessary to fill the mold space with a blowing agent). A laminated injection molded product is obtained by successively injecting the core layer forming resin, but the skin layer is formed on the mold cavity surface and the insert surface.
If the temperature of the insert surface is low, the resin will solidify quickly, so the skin layer around the insert will become thicker. To do this, the insert surface is heated to allow the skin layer-forming resin to flow on the insert surface to the end of the C''-molded product without greatly reducing the viscosity due to a drop in the resin temperature (2). This reduces the

The insert used in the present invention C2 may be solid or may be a C-shaped hollow body to reduce weight.

Further, the material may be metal, metal, synthetic resin, or synthetic resin reinforced with fibers, etc., and is not limited in any way.

Further, the mold may be of any shape, size, and material and is not limited in any way.

You can heat the insert by placing it in hot water, heating it in the oven (heating it with two people, etc.), or use any method you like.
Inserts (= There are no restrictions as long as they do not cause problems such as deformation or molding defects.) 1. The heating temperature of the insert depends on the shape and size of the molded product, the shape, size, material of the insert, and the type of material used. However, it is desirable that the heating temperature be as high as possible without causing problems such as molded product C two-component type and poor molding.

Furthermore, if the surface temperature is below 5°C, the skin layer around the insert cannot be made thinner, and there is no effect. If the heating temperature is 100°C or higher, the cooling time of the foam becomes very long (=long), and the production efficiency deteriorates significantly.The heating temperature is preferably 40°C or higher and 90°C or lower. I can decide.

In addition, the method of the present invention can be used not only with general-purpose polyolefin resins and polyvinyl chloride, but also with thermoplastic resins without any hindrance, and there are no restrictions whatsoever. It's not a thing.

Next, typical examples of the present invention will be explained.

An injection molding machine for forming laminated products with a mold clamping force of 200 tons, which has two cylinder units that meet at the nozzle. Filling the space (= means injecting an insufficient amount of polyvinyl chloride skin layer forming resin, and before the inner surface of the skin layer forming resin hardens, a polyvinyl chloride core layer containing a blowing agent is added. The molding resin was then injected.This produced a handle whose skin layer was polyvinyl chloride and the core layer was foamed polyvinyl chloride.The insert was a hollow iron body with a diameter of 14 (mm
), a ring part made of a pipe with an inner thickness of 2 (IIm),
The ring part (consists of a connected U-shaped iron arm part. The iron core was tested at a surface temperature in the range of 0°C to 140°C. It was heated in an oven for 21 hours at each set temperature. The molding was performed immediately after taking it out of the oven.The gate was a two-point gate, and the shape was a bottle point gate with a diameter of 3 mm.The mold temperature was 40°C.

In this example, the materials used were mixed using a super mixer and then mixed into pellets using a gunnery mixer.

Skin layer forming resin molding part Polyvinyl chloride cP=ttoo)to.

DOP 80 Epoxidized soybean oil 5 Ba-Zn stabilizer 5 Core layer forming resin polyvinyl chloride (P = 1400) 10QDOP
50 Epoxidized soybean oil 10 Ba-Zn stabilizer 5 ADCA (foaming agent) 3 The dimensions of the bundle of this example (=obtained accordingly) are as follows.

Diameter of the handle: 380 (11 Irn) Diameter of the outer grip: 28 (illm) Diameter of the core material (iron): 14 (++++, q) The relationship between the surface temperature of the insert, the average thickness of the skin layer around the insert, and the specific gravity of the molded product. It is shown in Table 1.

In the case of handle molding, considering productivity, the surface temperature should be 4.
It was good at temperatures above 0°C and below 90°C, but especially at -70°C.
Around ℃ was appropriate. At temperatures above 100℃, the cooling time is 2
Even if it was set to 0 minutes, after the molded product was removed from the mold (= it expanded, dimensional changes occurred, and a good product could not be obtained.
At temperatures below ℃, the fluidity of the resin was poor and good products could not be obtained.

As described above, the manufacturing method according to the present invention can easily reduce the weight of laminated injection molded products.Table 1

Claims (1)

[Claims] Insufficient skin layer forming resin to fill the mold space is injected into the mold, and a core layer containing a foaming agent is formed before the inner surface of the skin layer forming resin is assimilated. Inside of a laminated injection foam in which resin is continuously injected 6 = In a method for producing a molded product that incorporates part or all of an insert, a laminated product characterized in that the insert is heated to a temperature of 5 to 100°C before use. Method of manufacturing injection molded products.