GB2050922A

GB2050922A - Process for producing continuous webs or separate blocks of plastics foam material

Info

Publication number: GB2050922A
Application number: GB7920960A
Authority: GB
Original assignee: PLA MA Ltd
Current assignee: PLA MA Ltd
Priority date: 1977-12-01
Filing date: 1979-06-15
Publication date: 1981-01-14
Also published as: NL7904739A; FR2459123A1; DE2924459A1; LU81434A1; AT362139B; CH641719A5; ATA423579A

Abstract

Process for producing continuous webs or separate blocks of plastics foam material (5) in a moulding channel (8), wherein the moulding channel (8) with a material supply (1) and necessary control equipment and accessories (6, 7) are mounted in a closed chamber (4) in which the pressure is reduced e.g. by one or more suction ventilators (2). <IMAGE>

Description

SPECIFICATION Process for producing continuous webs or separate blocks of plastics foam material The present invention relates to a process for continuous webs or separate blocks of plastic foam material in a moulding channel.

Many different processes are known for such production and the main features of these processes are that the production is carried out in an "opentopped" mould and that the channel-shaped mould is lined in the base and on the sides with synchronously moving webs of for instance paper, the complete production being carried out on a conveyor having controllable speed.

It has, however, been found that a remarkably more advantageous result may be obtained if this production is carried out inside a closed chamber so that the internal pressure of this chamber can be reduced. Previously the chemical composition has been given the opportunity to expand at atmospheric pressure, but it has been found that a production of the same quality, i.e. in accordance with the same formula or recipe, from, for instance polyurethane plastic foam, by controlled and certain reduced pressure (partial vacuum), products are obtained having substantially lower weight per volume and consequently leading to important saving of material.

According to the invention the moulding channel with a material supply and necessary control equipment and accessories is built into a closed chamber wherein the internal pressure may be reduced. The chamber comprising the moulding channel and accessories may be kept at a reduced pressure by means of one or more suction ventilators built into the wall of the chamber.

A further advantage is that in order to obtain the necessary foaming it is no longer required to use Freon 11 as a driving means as in all previously known processes for the production of foam plastic material. This is of great importance to prevent air pollution in the working areas.

As an example it has been found in practice that the same recipes for polyurethane plastic foam at a pressure of 760 mm Hg will give approx. 23.5 Kg/3 volume weight, whereas at a pressure of 630 mm Hg it will give approx. 20.0 kg/m3 volume weight.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing which shows a plantforthe production of continuous plastic foam webs in a channel-shaped mould, wherein the complete production unit is built into a chamber 4 having sealed outlets (at the right hand side of the Figure). In this chamber there is located a mixing chamber 1 for the chemical composition which is to expand orfoam, one or more suction ventilators 2, extending from the chamber or space 4, and a plastic foam block 5 is formed in said chamber 4 by foaming on a moulding conveyor or moulding band 8. Furthermore there is provided a control roller 7 for moulding paper and one supply roller 6 for moulding paper. The outlet end of the conveyor is designated 9.

It should be noted that the process according to the present invention is not limited to the production of continuous webs or blocks but may also be used for the forming of separate blocks and details in moulds by arranging the expanding chemical compositions in a cabinet or chamber which is provided with a suitable partial vacuum in the same way as described above.

Furthermore it should be understood that the process may also be used for ail expandable materials even inorganic. It has been shown during tests that by the production of the same quality under atmospheric pressure and under a pressure in accordance with the invention as exemplified, a product may be obtained having a weight per volume about 12 - 15% lower than by normal pressure.

1. Process for producing continuous webs or separate blocks of plastics foam material in a moulding channel, the moulding channel with a material supply and necessary control equipment and accessories are mounted in a closed chamber in which the pressure may be reduced.

2. Process according to claim 1, wherein the chamber comprising the moulding channel is maintained at an underpressure by means of one or more vacuum ventilators built into the chamber wall.

3. Process according to claim 1 or 2, wherein the foam web is produced as a continuous web.

4. Process for producing a plastics foam web on block substantially as described with reference to the accompanying drawing.

5. A plastics foam web or block when produced by a process as claimed in any one of claims 1 to 4.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Process for producing continuous webs or separate blocks of plastics foam material The present invention relates to a process for continuous webs or separate blocks of plastic foam material in a moulding channel. Many different processes are known for such production and the main features of these processes are that the production is carried out in an "opentopped" mould and that the channel-shaped mould is lined in the base and on the sides with synchronously moving webs of for instance paper, the complete production being carried out on a conveyor having controllable speed. It has, however, been found that a remarkably more advantageous result may be obtained if this production is carried out inside a closed chamber so that the internal pressure of this chamber can be reduced. Previously the chemical composition has been given the opportunity to expand at atmospheric pressure, but it has been found that a production of the same quality, i.e. in accordance with the same formula or recipe, from, for instance polyurethane plastic foam, by controlled and certain reduced pressure (partial vacuum), products are obtained having substantially lower weight per volume and consequently leading to important saving of material. According to the invention the moulding channel with a material supply and necessary control equipment and accessories is built into a closed chamber wherein the internal pressure may be reduced. The chamber comprising the moulding channel and accessories may be kept at a reduced pressure by means of one or more suction ventilators built into the wall of the chamber. A further advantage is that in order to obtain the necessary foaming it is no longer required to use Freon 11 as a driving means as in all previously known processes for the production of foam plastic material. This is of great importance to prevent air pollution in the working areas. As an example it has been found in practice that the same recipes for polyurethane plastic foam at a pressure of 760 mm Hg will give approx. 23.5 Kg/3 volume weight, whereas at a pressure of 630 mm Hg it will give approx. 20.0 kg/m3 volume weight. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing which shows a plantforthe production of continuous plastic foam webs in a channel-shaped mould, wherein the complete production unit is built into a chamber 4 having sealed outlets (at the right hand side of the Figure). In this chamber there is located a mixing chamber 1 for the chemical composition which is to expand orfoam, one or more suction ventilators 2, extending from the chamber or space 4, and a plastic foam block 5 is formed in said chamber 4 by foaming on a moulding conveyor or moulding band 8. Furthermore there is provided a control roller 7 for moulding paper and one supply roller 6 for moulding paper. The outlet end of the conveyor is designated 9. It should be noted that the process according to the present invention is not limited to the production of continuous webs or blocks but may also be used for the forming of separate blocks and details in moulds by arranging the expanding chemical compositions in a cabinet or chamber which is provided with a suitable partial vacuum in the same way as described above. Furthermore it should be understood that the process may also be used for ail expandable materials even inorganic. It has been shown during tests that by the production of the same quality under atmospheric pressure and under a pressure in accordance with the invention as exemplified, a product may be obtained having a weight per volume about 12 - 15% lower than by normal pressure. CLAIMS