SPLITTING OF THICK HARD-FOAM PLATES

Abstract

The present invention relates to a method for cutting rigid foams, especially slabstock P(M)I foams. A method is provided here, by means of which it is possible to cut these rigid foams even in relatively high layer thicknesses of, for example, more than 3 mm, without material loss, which is produced in relevant amounts, for example, in the course of sawing as a result of the sawdust formed.

Claims

1-15. (canceled)

16: A method for planar division of a rigid foam to obtain a film or thin sheet, said method comprising: flexibilizing the rigid foam to obtain a flexibilized foam, cutting the flexibilized foam with a knife, wherein said flexibilizing of the rigid foam prior to cutting is accomplished by storing the rigid foam in water and/or heating or adjusting to a temperature of not less than 15 C. and not more than 1 C. below the foaming temperature of the rigid foam, and wherein the rigid foam is a PE, PP, PVC, PMMA or P(M)I foam.

17: The method according to claim 16, wherein the rigid foam is flexibilized prior to cutting by storing in an oven or by irradiating with IR rays or microwaves.

18: The method according to claim 17, wherein the rigid foam is cut with the knife directly after removal from an oven or a heated press, or wherein the knife is within the oven.

19: The method according to claim 17, wherein the rigid foam is first moved past the IR or microwave radiation sources and subsequently transported to the knife with a maximum distance of 2 m, or wherein the radiation source is directly above the knife.

20: The method according to claim 16, wherein the rigid foam is heated prior to cutting to a temperature above the heat distortion resistance temperature of the rigid foam material.

21: The method according to claim 16, wherein the rigid foam is stored in a water bath for at least 30 min and then divided with the knife within not more than 30 min.

22: The method according to claim 16, wherein the rigid foam slab is moved at right angles to the cutting surface of the knife, and wherein the knife moves only at right angles to the transport direction of the rigid foam slab.

23: The method according to claim 16, wherein the rigid foam is a P(M)I foam having a density between 20 and 320 kg/m.sup.3.

24: The method according to claim 16, wherein a film consisting of the rigid foam having a thickness between 0.05 and 1.0 mm is obtained.

25: The method according to claim 16, wherein a thin sheet consisting of the rigid foam having a thickness between more than 1.0 and a maximum of 30.0 mm is obtained.

26: The method according to claim 16, wherein the knife is a band knife which moves in a circuit at right angles to the cutting direction.

27: The method according to claim 24, wherein the film or the thin sheet is subsequently covered with at least one outer layer.

28: The method according to claim 16, wherein several films or thin sheets are divided off from the rigid foam after the flexibilizing, in one movement with several knives in succession.

29: The method according to claim 16, wherein the film or thin sheet is divided off, and after having been divided, is cut to size in the two other dimensions.

30: The method according to claim 24, wherein the film divided off is subsequently wound onto a roll.

Description

WORKING EXAMPLES

[0038] The examples described below comprise various PMI foams. The inventive effect is surprising for the closed pores of this foam. Accordingly, the results can be transferred in a simple manner to other rigid foams which, as is known by the person skilled in the art, are effectively characterized by exclusively closed pores.

[0039] A band knife system from Fecken and Kirfel having a band knife speed of 120 m/sec and a table advance rate of 20 m/min was used for the division. The system was equipped with a vacuum table, holding rolls and automatic thickness adjustment.

[0040] Rigid PMI foams of the Rohacell IG-F, HERO and RIMA brands, having nominal densities of 71 and 110 kg/m.sup.3, were divided. The division format was 950500 mm.

Example 1: Division after Water Storage

[0041] The slabs to be divided were stored under water for 30 h and then divided at room temperature. The division thicknesses were 1 mm and 2 mm. The slabs were divided without fracture.

Example 2: Division after Heating in an Oven

[0042] The foam slabs to be divided were stored in an air circulation oven at 160 to 190 C. for 2 hours in each case. Thereafter, they were divided. The time delay between removal from the oven and the commencement of the division operation was about 10 sec. The division thicknesses were set between 2 and 15 mm. The slabs were divided without fracture.

Example 3: Division after Heating in a Heated Press

[0043] The heating in a heated press took place at a heating plate temperature between 160 C. and 190 C. for 2 h, the plates of the heated press having been in contact with either side of the foam slab; the plate pressure was adjusted to a maximum of 0.2 bar. The time delay between removal from the heated press and the commencement of the division operation was about 10 sec. The division thicknesses were set between 2 and 15 mm. The slabs were divided without fracture.

Example 4: Division Directing after the Foaming Operation

[0044] For division directly after the foaming operation which was conducted at 230 C., the freshly foamed Rohacell foam slab was divided directly. The time delay between removal from the foaming oven and the commencement of the division operation was about 20 sec, such that the foam block cooled down to a temperature between 215 and 220 C. The slabs were divided without fracture.

Example 5: Division by Heating with IR Radiation during the Division Process

[0045] The plant was supplemented with an IR radiator field. The width of the radiator field was chosen such that it was 20 cm broader than the foam slab to be cut on either side. The length of the radiator field was 100 cm. The IR radiator field was positioned such that it was upstream of the band knife. The slabs were divided at a division thickness of 10 mm with a speed of 1 m/min. The power of the radiator field was chosen such that the slabs could be divided without tears or fracture.