GB2123741A - Manufacturing moulded sheet material - Google Patents

Abstract

Manufacturing a moulded sheet material is effected by charging a desired amount of synthetic resin powder (3) into a treatment container (2). The powder is spattered by agitation blades (4) so that the spattered power is forced to be adhered to and is fused on a predetermined shaped moulding mould surface (11) heated to the melting point or higher of the synthetic resin powder and is formed thereon in a fused and moulded coat of a predetermined thickness, and then the coat is solidified by cooling. <IMAGE>

Description

SPECIFICATION Manufacturing moulded sheet material This invention relates to manufacturing moulded sheet material such as is used for interior decoration for example in a vehicle such as a motorcar.

It has been usual hitherto that moulded sheet material such as is used as interior decoration, for example as an instrument panel, a door panel and so on in a vehicle such as a motorcar, or in any other constructional object, has a complicated curved surface and/or a desired pattern such as seams, specifically formed wrinkles or the like. In a conventional manufacturing process thereof for producing such material, plastics sol is charged into a mould having a predetermined curved shape and/or a pattern. Alternatively, slush moulding is effected, where plastics powder is coated on a predetermined shaped moulding mould surface by electrodeposition coating and the coated surface is then fused by heating so that a plastics sheet is formed thereon.The first of these two processes is defective in that air is liable to be confined to the contact surface between the charged liquid and the mould, and pinholes are liable to be created in the moulded sheet due to air included in the liquid.

The second process is defective in that, because the powder is coated after being charged with electricity, the flow rate and the flow amount of the powder from a gun are limited, resulting in lowering of the coating efficiency. Furthermore, especially when a comparatively large-sized and complicated moulded product is to be manufactured, the problem is encountered that it is difficult to coat on every sideward and rearward part of the curved mould surface, and therefore it is inevitable that a multiple head gun apparatus has to be provided wherein a large number of guns are disposed at various necessary angles in relation to the mould surface.

According to the present invention there is provided a process for manufacturing a moulded sheet material, wherein a desired amount of synthetic resin powder is charged into a treatment container, and the powder is spattered by an agitation blade means and the spattered powder is forced to be adhered to and is fused on a predetermined shaped moulding mould surface heated to the melting point or higher of the synthetic resin powder and is formed thereon into a fused and moulded coat of a predetermined thickness, and then the coat is solidifed by cooling.

The invention also provides apparatus for manufacturing a moulded sheet material comprising a treatment container for containing# a charged layer of synthetic resin powder, an agitator in the container having an agitation blade means for spattering a charged layer of synthetic resin powder, and a metallic mould closing the container; the metallic mould being provided with a moulding mould surface directed for facing the charged powder layer, this moulded surface being so arranged as to be heated or cooled at will. By this method and apparatus moulded sheet material of good quality can be formed uniformly and accurately according to a predetermined shaped surface of a mould, and at a high efficiency.

The synthetic resin powder charged in the treatment container is so spattered violently and thereby the spattered powder is impinged and fused on the whole area of the heated moulding mould surface, that a good quality of moulded sheet material which is formed accurately according to the shape of the predetermined shaped moulding mould surface, and which is free from air and pinholes can be produced in a short time, and productivity is enhanced.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made by way of example, to the accompanying drawings, in which Figures 1, 2 and 3 are somewhat schematic side views of three forms of apparatus for manufacturing moulded sheet material.

Referring to Figure 1, numeral 1 denotes a machine base. A treatment container 2 which has a predetermined depth and is open at its upper surface is fixedly provided on the machine base 1.

In use a lower space 3 of the container 2 is charged with synthetic resin powder which comprises a large number of fine particles a in the range of 30 to 200 p in particle diameter. A rotary agitator 4 is mounted for rotation about a horizontal axis in this lower space 3 wherein there is the charged layer of synthetic resin powder.

In more detail, a rotary shaft 4a of the agitator 4 extends horizontally with both end portions supported by bearings on mutually opposite side walls of the treatment container 2. An agitation blade arrangement comprises a number of agitation groups each comprising radially extending agitation blades 4b, these agitation groups being disposed on the shaft 4a at predetermined intervals along the axial direction thereof. There is at least one agitator 4, but usually there are several provided side by side, that is, in parallel one with another. Numeral 5 denotes an agitation motor.

A bottom wall of the treatment container 2 is composed of an air-permeable wall 6 such as an air filter or the like having innumerable fine holes and being made of for example, glass or fabric Below the wall 6 there is an air chamber 7 so arranged that compressed air may be introduced thereinto through an air supply opening 8 in the side wall of the chamber 7 and to which there is connected an air supply pipe 9. The synthetic resin layer may be brought into a floating condition by the supplied air passing through the bottom wall 6. Numeral 7a denotes a mesh window for air discharge.

The upper surface of the treatment container 2 is provided with a metallic mould 10 covering, that is, closing, the container 2. The metallic mould 10 is provided with a downwardly directed moulding mould surface 11 having a predetermined complicated curved moulding shape and additionally, as occasion demands, a wrinkle pattern or the like formed thereon. There is provided at the rear surface of the moulding mould surface 1 1 a temperature adjusting jacket 12 into which a heating medium and a cooling medium may be introduced alternatively for effecting heating and cooling, alternately, of the whole area of the surface 1 The jacket 12 is selectively connected through two communication openings 1 2a, 1 2a to a circuit 13 for heating medium and a circuit 14 for cooling medium.

The circuit 13 for heating medium comprises a tank 15 for heating medium such as oil or water, a pump 16, a heater 17, a three-way valve 18 upstream of the jacket 12 and a three-way valve 1 9 downstream of the jacket 12, the circuit 13 being connected through the communication openings 1 2a, 1 2a to the jacket 12 for circulation supply of heating medium. The circuit 14 for cooling medium comprises a tank 20 for cooling medium such as oil or water, a pump 21, a cooler 22, the three-way valve 19 and an additional three-way valve 23, the circuit 14 also being connected through the communication openings 1 2a, 1 2a to the jacket 12 for circulation supply of cooling medium.

A line connecting between the cooler 22 and the three-way valve 23 can serve for heightening the cooling or heating efficiency. Namely, when the metallic mould 10 is to be changed from heating to cooling, if the hot medium in the mould jacket 12 is returned to the tank 20 for cooling medium, the efficiency becomes bad. Accordingly the line between the cooler 22 and the valve 23 is used in this case for returning the hot medium to the tank 1 5 for heating medium, and immediately thereafter the circuit is changed over to the cooling cycle. This is similarly applicable to the case that the circuit is changed over from cooling to heating.

The metallic mould 10 is so arranged that, by turning of an opening and closing mechanism 24 attached to the side surface thereof, the mould 10 can be turned over to such an open position thereof that the moulding mould surface 1 1 thereof is directly upwards, as shown by chain dot lines, so that after the completion of the moulding operation, the moulding mould surface 11 of the mould 10 may be directed upwards and thereby removal of the product A is facilitated. It is preferable that an air-tight sealing member 25 such as a packing is provided on the periphery of the moulding mould surface 1 1 of the metallic mould 10.

Manufacture is carried out as follows:~ /with the metallic mould 10 in open position a desired amount of synthetic resin powder a is charged into the treatment container 2. The metallic mould 10 is turned to its closed position (to close the treatment container 2) by operation of the opening and closing mechanism 24, and then the air chamber 7 at the bottom of the treatment container 2 is supplied with air. Air is caused to flow into the bottom of the container 2 through the bottom wall 6 so as to bring the charged layer of synthetic resin into a flowing and floating condition. At the same time the jacket 12 of the metallic mould 10 is supplied with heating medium heated to a temperature above the melting point of the synthetic resin powder a, and thereby the moulding mould surface 1 1 is heated to a predetermined temperature.Under this condition, the agitator 4 is rotated so that the large number of blade 4b groups are rotated violently at a high speed, and the floating synthetic resin powder layer is driven by the blades 4b to spatter continuously upwards. By this operation, the fine particles of the synthetic resin powder a are forced to impinge strongly against the surface of the heated moulding mould surface 11, which is directed downwardly, and which is located over the floating resin powder, and are fused on the surface 1 1 by the heat thereof. As a result, there is obtained a fused and firmly deposited layer of the synthetic resin powder without air confined between the fixed powder and the moulding mould surface 1 1. Similarly, in sequence, fine particles of the synthetic resin powder are forced to be acumulated on and are fused to the heated fused resin layer.If upward spattering of the resin powder by the agitator is continued for 30-120 seconds, there is produced a sheet of fused and moulded resin coat of about 0.5-2 mms in thickness.

If the rotation of the agitator is reversed in the midst of the operation and accordingly the rotation of the agitation blades are reversed, the direction of the spattered resin powder toward the mould surface 1 1 is varied, and a uniform and accurate iayer-forming in conformity with the curved shape of the mould surface can be ensured. It is preferable that regular rotation and reverse rotation of the agitator are repeated 2-3 times. It is further preferable that the uniform coating property is further improved by arranging that one of two agitators, for instance, disposed in parallel one with another is rotated in regular direction while the other is rotated in the reverse direction so as to create a turbulent flow of powder.Also, if the agitator 4 is so arranged that the same may be shifted left or right to a predetermined position in the axial direction of the shaft, or if it is so arranged that the shaft 4a thereof may be inclined in relation to the mold surface 11, uniform adhesion of the synthetic resin powder to the moulding mould surface can be further enhanced.

When the thickness of the fused resin layer reaches a desired one, the rotation of the agitator and the supply of the air are stopped, and the fused resin layer is kept at a predetermined temperature in order to ensure a uniform sheetforming treatment. Thereafter, the supply of heating medium into the jacket 12 is stopped, and the three-way valves are suitably changed-over to the cooling circuit side, whereby cooling medium is supplied into the jacket 12 to cool the moulding mould surface 1 1 for solidifying the resin layer, and thus the moulded sheet material product A of the predetermined thickness is produced.

Thereafter, the opening and closing mechanism 24 is operated, and thereby the metallic mould 10 is turned over so that the moulding mould surface 11 is opened, and accordingly the moulded product A is turned to be directed upwards. As a result, the product A can be easily taken out.

If the metallic mould 10 isturnable by operation of opening and closing mechanism 24 provided on each side of the treatment container 2 as shown in Figure 2, such a manufacturing procedure becomes possible that while one of two metallic moulds 10, 10 is positioned on the upper surface of the container 2 to close the container 2, and the moulding mould surface 11 thereof is heated to form thereon a fused moulded sheet, the other mould 10 will be in open position and a fused moulded sheet previously formed thereon can solidfy by cooling and then can be taken out, and thereafter this procedure can be repeated alternately. This is advantageous in that the products A can be manufactured continuously and at a high efficiency.As a modified example of this apparatus, there can be considered such an arrangement that, as shown in Figure 3, there is provided a rotary frame 26 on the side of the treatment container 2, and two of the metallic moulds 10, 10 are provided on the rotary frame 26 so as to be at rotational symmetrical positions with respect to one another. In this case either one of the two metallic moulds 10, 10 may be moved to its operative position alternately by turning in one direction and in the other direction of the rotary frame 26. In this example, the treatment container 2 is so arranged as to be able to be retreated outwards from the rotation loci of these metallic moulds 10, 10 so that the container 2 does not stand in the way of the rotation of these metallic moulds 10, 10.To this end, the machine base 1 having the container 2 fixedly mounted thereon is movable upwards and downwards through an elevating mechanism 29 on a movable table 28 movable forwards and rearwards by a ram 27, so that when the rotary frame 26 is to be turned, the container 2 is first lowered slightly by the elevating mechanism 29 and is then retreated together with the movable table 28 to the outside of the rotation loci of the moulds 10.

Specific Example Vinyl chloride resin powder in a range of about 30-200 p in particle diameter, and, for example 150 p in average particle diameter, either alone or in a powder composition composed of 100 parts of the resin powder, 70-80 parts of a plasticizer, 1-5 parts of a stabilizer, 1-5 parts of a pigment and 1-2 parts of an additive is used as the raw material.The metallic mould is previously heated to a temperature of 2300 C, and the powder raw material is brought into a floating condition by the air and in this floating condition is agitated and is spattered on the mould surface for 60 seconds by such a manner that the agitator is repeatedly turned in regular direction and in the reverse direction alternately at a rotation speed of 1200 r.p.m. so that a uniformly fused layer of the powder is formed. Thereafter, the alternative turning of the agitator is stopped and the supply of the air is also stopped, and the metallic mould is kept at a temperature of 2300C for 120 seconds, whereby the fused resin layer is so matured on the mould surface as to be smooth in surface and uniform in thickness.

Thereafter, the metallic mould is cooled, and the temperature thereof is lowered to 800C in 120 seconds, whereby the fused resin sheet is solidified and the manufacturing thereof is completed. There is obtained a predetermined form of mould sheet material which has a uniform thickness of about 1.2 mms and is composed solely or chiefly of vinyl chloride and has at its surface a wrinkle pattern.

In a case where the vinyl chloride skin material 'is used as the raw material for manufacturing an interior decoration member for a vehicle such as a motorcar, there is carried out such a process, for instance, that a core sheet member of ABS resin prepared separately by a conventional process is set in one of two moulds facing one another, and present product is set in the other mould, and urethane form liquid is charged between the two and is cured, and thereby there is produced an interior decoration member having at its surface the present material layer.

Claims (10)

1. A process for manufacturing a moulded sheet material, wherein a desired amount of synthetic resin powder is charged into a treatment container, and the powder is spattered by an agitation blade means and the spattered powder is forced to be adhered to and is fused on a predetermined shaped moulding mould surface heated to the melting point or higher of the synthetic resin powder and is formed thereon into a fused and moulded coat of a predetermined thickness, and then the coat is solidified by cooling.

2. A process as claimed in claim 1, wherein the charged synthetic resin powder is kept in a floating condition.

3. A process for manufacturing a moulded sheet material, substantially as hereinbefore described with reference to any of the foregoing Examples and as illustrated in the accompanying drawings.

4. Apparatus for manufacturing a moulded sheet material comprising a treatment container for containing a charged layer of synthetic resin powder, an agitator in the container having an agitation blade means for spattering a charged layer of synthetic resin powder, and a metallic mould closing the container; the metallic mould being provided with a moulding mould surface directed for facing the charged powder layer, this mould surface being so arranged as to be heated or cooled at will.

5. Apparatus as claimed in claim 4, wherein the treatment container has in its lower portion a space for containing said charged layer of synthetic resin powder; wherein said agitation blade means is for spattering upwards said charged layer; wherein said moulding surface is downwardly directed; and wherein the metallic mould is so constructed as to be turned over to an open position in which the moulding mould surface there of is directed upwards.

6. Apparatus as claimed in claim 4 or 5, wherein the agitator comprising a rotary shaft and agitation blades disposed thereon at predetermined intervals along the axial direction of the shaft, the shaft extending horizontally in the treatment container.

7. Apparatus as claimed in claim 3, 4, 5 or 6, wherein the agitator is movable in its axial direction.

8. Apparatus as claimed in any one of claims 3 to 7, wherein the agitator is tiltable in relation to the moulding mould surface.

9. Apparatus as claimed in claim 4 or any one of claims 5 to 8 as appendant to claim 4, wherein the metallic mould is one of two provided one each side of the treatment container, these metallic moulds being so arranged that they can be turned over alternately.

10. Apparatus as claimed in claim 4 or any one of claims 5 to 8 as appendant to claim 4, wherein a rotary frame is provided on the side of the treatment container, and wherein the metallic mould is one of two so provided on the rotary frame as to be at rotational symmetrical positions with respect to one another, and the treatment container being so arranged as to be retreatable outwards from the rotation loci of these two metallic moulds.

1 Apparatus for manufacturing a moulded sheet material, substantially as hereinbefore described with reference to any of the foregoing Examples and as illustrated in the accompanying drawings.