GB1577657A - Method of producing rolls of foamed plastics materials - Google Patents

Description

(54) A METHOD OF PRODUCING ROLLS OF FOAMED PLASTICS MATERIALS (71) We, KWIKSTIK PRODUCTS LIMITED, a British Company, of Waterside, Chesham, Buckinghamshlre, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method of producing rolls of foamed plastics materials.

Foamed plastics material in strip form, such as is used for example for sealing purposes, is commonly sold in rolls which are formed by making a plurality of cuts through a long roll in planes at right angles to its axis. However, with low density materials, the instability of the materials limits the diameter of the roll which can be successfully cut without producing an unacceptable amount of waste material.

In accordance with the present invention a method of producing rolls of foamed plastics material by dividing a long roll of the material by cutting transversely through the long roll includes the step of cooling the long roll substantially below ambient temperature, thereby increasing its hardness to a degree at which it does not appreciably deform under the pressure of a cutting tool, before subjecting the long roll to the cutting operation.

On cutting long rolls of thermoplastics materials, for example polyvinyl chloride, which may have a hardness of as low as 5 in the Shore "00" scale, the material is frozen to raise its hardness to the value of at least 50 and preferably 80 or more. Due to the heat insulating properties of foamed materials, it is necessary to "soak" a roll to be cut within a refrigerating room or cabinet for an extended period. In practice it has been found that soaking times of between 12 and 16 hours at a temperature of the order of - 25 C produce very satisfactory results in suitably hardening rolls of diameters up to 40.6 cm of materials having a hardness value of between 10 and 40 at ambient temperature.

For a clearer understanding of the invention, there will now be described a method of producing rolls of foamed polyvinyl chloride in strip form having one surface coated with a pressure sensitive adhesive and the opposite surface of the strip attached to a backing paper.

In this method, a 1 metre wide sheet of backing paper is fed through a weir at which a coating of foamable polyvinyl chloride composition is spread evenly over one surface of the paper. The thus coated paper is then conveyed through an oven to cause foaming of the polyvinyl chloride and then cooled. After cooling the laminate of paper and foamed polyvinyl chloride is fed through a coating machine in which the exposed surface of the foamed material is coated with a pressure sensitive adhesive and then wound into 20 metre long rolls on a fibre core mounted on a mandrel.

The 20 metre long roll thus produced is then placed in a refrigerating room or cabinet having an inside temperature of the order of --25"C and left to "soak" for 12 hours until it is completely frozen throughout. The frozen roll can then be removed from the room or cabinet and mounted on the mandrel of a lathe type slitting machine on which it is rotated 600r.p.m. while a slitting knife or blade makes successive cuts through the roll at right angles to its axis to divide the roll into a plurality of flat rolls having a thickness equal to the required thickness of the strips. By the method described above clean cuts through the long roll can be achieved without the formation of ragged or scolloped edges, paper chips, or tears, at acceptable production rates.

The method described is applicable to thermoplastic foamed materials including polyethylene, polypropylene and ethylene vinyl acetates to thermosetting foamed materials such as, for example, polyurethane and to natural and synthetic foamed rubbers.

While the method has been described with reference to the production of ahesively coated, paper backed materials, it is equally useful in producing strips in which the adhesive coating is omitted with or without a backing paper.

WHAT WE CLAIM IS: 1. A method of producing rolls of foamed plastics material by dividing a long roll of the material by cutting transversely through the long roll wherein, prior to the cutting operation, the long roll is cooled to a temperature substantially below ambient to thereby increase the hardness of the material to a degree at which it does not appreciably deform under the pressure of the cutting tool.

2. A method according to claim 1 wherein the hardness of the material is increased to a value of at least 50 in the shore "00" scale.

3. A method according to claim 2 wherein the value is at least 80.

4. A method according to any of claims 1-3 wherein the shore "00" scale hardness of the material prior to cooling is between 10 and 40, and the roll is cooled for a period of between 12 and 16 hours at a temperature of substantially --25"C.

5. A method according to any of the preceding claims wherein the material is polyvinyl chloride having a coating of pressure sensitive adhesive on one surface and a paper backing on the other surface.

6. A method of producing rolls of foamed plastics material substantially as herein before described.

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

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. vinyl acetates to thermosetting foamed materials such as, for example, polyurethane and to natural and synthetic foamed rubbers. While the method has been described with reference to the production of ahesively coated, paper backed materials, it is equally useful in producing strips in which the adhesive coating is omitted with or without a backing paper. WHAT WE CLAIM IS:

1. A method of producing rolls of foamed plastics material by dividing a long roll of the material by cutting transversely through the long roll wherein, prior to the cutting operation, the long roll is cooled to a temperature substantially below ambient to thereby increase the hardness of the material to a degree at which it does not appreciably deform under the pressure of the cutting tool.

2. A method according to claim 1 wherein the hardness of the material is increased to a value of at least 50 in the shore "00" scale.

3. A method according to claim 2 wherein the value is at least 80.

4. A method according to any of claims 1-3 wherein the shore "00" scale hardness of the material prior to cooling is between 10 and 40, and the roll is cooled for a period of between 12 and 16 hours at a temperature of substantially --25"C.

5. A method according to any of the preceding claims wherein the material is polyvinyl chloride having a coating of pressure sensitive adhesive on one surface and a paper backing on the other surface.

6. A method of producing rolls of foamed plastics material substantially as herein before described.