JPH0617022B2 - Vehicle interior material manufacturing method - Google Patents

Description

The present invention relates to a door trim, a quarter trim, a door trim of an automobile or the like.
The present invention relates to a method for manufacturing an interior material such as a package tray.

(Prior Art) The above-mentioned interior material is generally one in which a skin material is adhered to the surface of a base material made of a resin containing a filler. Conventionally, interior materials have been manufactured through the following steps.

(1) Stirring step (see FIG. 5 (a)) As a base material, a thermoplastic resin (polyolefin resin or EVA (ethylene vinyl copolymer) resin)
In addition, fillers such as wood powder, calcium carbonate (hereinafter referred to as "tancal"), and talc have been used. This step is a step in which these are put into the high-speed stirrer 20 and granulated.

The stirring is performed prior to the kneading / extruding step, which is the next step, because the dispersibility of the filler is an important point in the molding of the resin containing the filler.

(2) Kneading and extruding step (see (a) in the figure) Next, the raw materials are put into the kneading and extruding machine 21. Here, the raw material is heated to about 200 ° C. and extruded while being stirred in a molten state by the screw shaft 22.

(3) Pelletizing step This is a step of pelletizing 23 the raw material that has undergone the kneading and extruding step.

(4) Stamping molding process The stamping molding machine used in this process is the extruder 2.
4 are installed side by side, and the above pellets are first charged into the extruder 24. The extruder has a single screw conveyor 25 inside, and pellets are
The mixture is heated to about 200 to 230 ° C., melt-kneaded, and extruded into the molding dies 26 and 27, where it is cold-molded together with the skin material 28 to obtain a product having desired properties.

(Problems to be Solved by the Invention) As described above, in the conventional manufacturing method, the base material is once pelletized 23 and then charged into the extruder 24 for molding. Pelletization 23 is an essential step because even if the blended molten resin raw material is directly fed into the extruder 24 of the molding apparatus, the conventional single-screw screw conveyor 25 has a low raw material kneading ability. , Because it cannot even be extruded. Even if it can be extruded even a little, the dispersion of the filler is poor, and the amount of protrusion varies (surging), resulting in deterioration of product quality.

Further, since the pelletizing step is performed, the base material is subjected to the heat history twice in the kneading / extruding step and the stamping molding step. For this reason, when wood powder or the like is used as the filler, it may be burned, and the gas generated at that time may decompose other resin fillers.

As described above, since the extruder of the conventional molding machine has a remarkably low kneading ability, the pelletizing step is inevitable, but the pelletizing step is performed by the extruder 2 of the molding machine.
This is a process that is only necessary for passing No. 4 and is not inherently related to the manufacturing process of the interior material. That is, in the conventional case, the work process is wasted.

In view of the above problems, it is an object of the present invention to provide a manufacturing method capable of omitting the pelletizing step and improving the efficiency of work steps without deteriorating the product quality.

(Means for Solving the Problems) In order to achieve the above object, in the production method of the present invention, after stirring the thermoplastic resin and the inorganic or organic filler, a double-row screw conveyor The raw material for the base material is passed through in an agitated and molten state by directly charging it into an extruder provided and heating it here, and then cold forming.

(Function) The thermoplastic resin as the base material and the inorganic or organic filler are first physically stirred at a predetermined mixing ratio. Then, it is put into the extruder as it is, and here, it is stirred at the same time as heating. That is, in the extruder, the agitating force is higher than in the past by the screw conveyors provided in a plurality of rows, so that the above raw materials are well agitated even in a molten state. After that, it is formed into a desired shape in a cold forming step.

(Example) Hereinafter, the Example which actualized the method of this invention is demonstrated in detail according to drawing.

The raw materials of the base material used in this example are polypropylene resin as a thermoplastic resin, and wood powder and tankar as a filler. And these are 50-90 by weight ratio.
%, The latter is mixed at a ratio of 10 to 30%. First, these raw materials are introduced into the drive blender 2 having the stirring blade 1 inside through the corresponding hoppers 3 and 4, and are mixed and dispersed therein.

After this, unlike the conventional case, the pellets are directly fed into the hopper 6 of the extruder 5 without undergoing the pelletizing step.

The extruder 5 includes a cylinder 7 and built-in screw shafts 8a, 8
Mainly b and. The screw shafts 8a and 8b are supported in two rows in parallel in the axial direction of the cylinder 7 so that they can be slowly rotated in the same direction. Further, a heater (not shown) is attached to the cylinder 7 of the extruder 5. further,
Deaeration holes 9 and 10 penetrate through a plurality of positions of the cylinder 7. An intake device (not shown) is connected to each of the degassing holes 9 and 10, and plays a role of removing water (steam) and bubbles in the base material.

The set temperature of the heater is about 180 to 220 ° C in this example. This is about 20 to 30 ° C. lower than the set temperature for general extrusion of polypropylene resin. this is,
This is because the kneading ability is enhanced by the double row of the screw shafts 8a and 8b, so that the kneading can be sufficiently performed without increasing the plastic state of the raw material.

In this way, the base material S fed into the extruder 5 is heated by the heater to be in a molten state. In this case, when the screw shaft is uniaxial as in the conventional case, since the base material has a low specific gravity (0.2 to 0.5 g / cm ³ ), stirring is almost difficult. , Screw shaft 8 as in this example
If the stirring ability is enhanced by using a and 8b as the two axes, the base material S can be moved in the axial direction by receiving a sufficient stirring force. In addition, water and gas in the raw material are removed by suction from the degassing holes 9 and 10 at this time. The agitated base material raw material S is mounted on the tip of the extruder 5 and is extruded by a required amount from the charging arm 13 extended so as to expand and contract toward the molding dies 11 and 12.

The skin material 14 is set in advance in the molding dies 11 and 12 before the introduction of the base material. In consideration of the adhesiveness to the base material S, the surface material 14 is preferably made of polypropylene, polyethylene, or the like whose back side is similar to the resin material in the base material. Further, it may be a non-woven fabric such as polyester.

After setting the skin material 14, when the base material S is put into the molding dies 11 and 12 and the mold is clamped, the raw material S is rolled in the mold and formed into a predetermined shape, and at the same time, melted and bonded to the skin material 14. Then, when the base material S is cooled and solidified after a lapse of a predetermined time, the interior material having a desired shape is taken out.

The product thus taken out is sufficiently degassed when the base material is extruded, so that foaming is suppressed,
The strength of the product is secured. Further, unlike the conventional case, the heat history is only once at the time of extrusion, so that the thermal deterioration of the base material is suppressed and the deterioration of the product quality can be prevented.

(Effects of the Invention) The effects of the present invention are as follows.

Since the screw conveyor is double-rowed to enhance the stirring ability of the base material, the raw material can be extruded even in a molten state, and thus the pelletizing step can be omitted. Therefore, the number of steps can be reduced and work efficiency can be improved.

Since the number of heat history of the base material can be reduced,
It suppresses the thermal deterioration of raw materials and contributes to the high quality of products.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used in the method of this example, FIGS. 2 to 4 are cross-sectional views showing a molding process, respectively, and FIG. 5 (a).
3A to 3C are explanatory views showing the conventional method. 5 ... Extruder 8a, 8b ... Screw shaft 11, 12 ... Mold S ... Base material

Claims (1)

[Claims] 1. A thermoplastic resin and an inorganic or organic filler are stirred, and then directly charged into an extruder equipped with a double-row screw conveyor, and heated here to stir and melt the base material. A method for producing an interior material for a vehicle, which comprises allowing the material to pass through and then cold forming.