GB1578366A - Porous elastic material - Google Patents

Description

(54) IMPROVEMENTS IN O R RELATING TO A POROUS ELASTIC MATERIAL (71) We, AKTIEBOLAGET WILHELM BEC KER, a Swedish Company, of Fack, S-102 70 Stockholm, Sweden, 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 following statement The present invention is related to an open cell foam material and more particularly to a compressed plate which comprises a body of a porous, open cell foamed plastics material and which is intended to be used for example for sound insulation and filling of cavities.

It has been previously proposed to use foam-plastic materials in the form of sheets or strips in the sealing of joints or filling of cavities, for instance between two outside panels in a building element. In order to enable the foam-plastic material to fulfil its function in a satisfactory way, the foamplastic sheet or strip has to be inserted into the cavity in a compressed condition, so that the material can expand after insertion to a certain degree and thus completely fill the cavity or space available and at the same time press against the walls forming and limiting the cavity with a certain force. This insertion is difficult to achieve because the foam-plastic material immediately resumes its original volume after compression when the compressing force ceases due to its inherent elasticity.

In order to obviate this difficulty it has previously been suggested, for instance in Swedish patent specification 382,609, to impregnate the foam-plastic material with a binder which delays the return of the elastic material to its original volume and to facilitate the packing of the material whilst in a compressed condition. This procedure has the advantage that the material can be compressed during the manufacture and that a certain time period is available after the removal of the package at another work place for inserting the material in a space or cavity. The material then can expand so that the space or cavity is completely filled. The disadvantage of this procedure is that during the manufacture the material has to be enveloped in a special package which has to be so designed that it can withstand the tendency of the material to expand and also the package has to be removed before the insertion of the material in the intended space or cavity.

The main object of the present invention is to provide a compressed member of material which is so designed that it is maintained in the compressed condition without outer means, so that the above described disadvantage is reduced or obviated. According to one aspect of the invention there is provided a compressed expandable member comprising a body of a foamed material having open cells substantially the whole body of foamed material being impregnated with a substance having a predetermined softening temperature with the range of 70"C-200"C so that the body of foamed material is maintained in the compressed condition as long as the temperature does not exceed a limit value which depends upon the softening temperature of the impregnating substance.

According to another aspect of this invention there is provided a method of forming a compressed member comprising the steps of impregnating a body of a foamed material having open cells with an impregnating substance which has a predetermned softening temperature within the range of 70"C-200"C, and which is above said softening temperature during the impregnating step, and cooling said member in a compressed condition to produce a compressed expandable member that will remain in the compressed condition as long as the temperature does not exceed a limit value which depends on the softening temperature of the impregnating substance.

It will be appreciated that the invention is based upon the concept that the open cell foam material of the member should be compressed and impregnated to such an extent with a suitable substance that the inherent elastic expansion is completely prevented, until a temperature increase occurs so that the impregnating substance is softened and the material can then expand.

One advantage of utilising a member in accordance with the invention is that the moment for the expansion of the member can be determined by the supply of heat to cause the temperature to be elevated to a predetermined limit value. A further advantage of the invention is that the temperature necessary for the expansion of the member can be varied within wide limits by the choice of impregnating substance giving opportunities for adapting or adjusting the member for different applications.

The material of the member is orginally flexible and is able to be compressed to a volume which is substantially smaller than its original volume. The member also has such a structure that the impregnating substance can penetate into and impregnate substantially the whole volume of the body. The body of the member may be provided with a nonporous surface layer on one or both sides and possibly also with one or two self-adhesive surfaces which are covered with a removable paper or foil.

A large number of substances can be used for the impregnation. It is important that the impregnating substance can be introduced into and distributed substantially uniformly over the whole body and that the substance is capable of maintaining the body in the compressed condition at temperatures normal during transport and storing of material for buildings and constructions. Further, the impregnation substance should have a softening temperature to which the elastic material can be heated without harm. Particularly suitable impregnating substances or compositions are thermo-plastics which are available in a large number having different properties and softening temperatures.

Preferably the substance used for impregnating comprises a mixture of two or more thermo-plastics having different softening temperatures. This will give the advantage that the softening temperature of the impregnating substance, which temperature determines the temperature at which the elastic material can expand, can be varied between wide limits by variation of the ratio between the quantities of the two or more thermo-plastics having different softening temperatures which form the substance used for impregnating. Of course, the substance used for impregnating can also contain additional materials for different purposes.

Any plastics material can be used which has the properties to soften at a certain temperature, although plastics materials which are termed bituminous plastics are preferred. In order that the invention may be more readily understood and so that further features thereof may be appreciated the invention will now be described by way of example.

In preparing one embodiment of the invention an impregnating substance in the form of a mixture of two different bituminous plastics was used. One bituminous plastics material had a softening temperature of 85"C and the other had a softening temperature of about 200"C. The first mentioned bituminous plastics material formed 97% and the last mentioned bituminous plastic formed 3 % of the impregnating substance. A block or member of foamed plastics material having open cells or pores was impregnated with the impregnating substance at an elevated temperature in excess of 100"C, that is to say a temperature at which the impregnating substance is liquid or substantially liquid.

While at the elevated temperature the block is compressed and then cooled while in the compressed state. With the above described impregnating process an expansion of the resultant block of elastic material was obtained at an elevation of the temperature of the block to about 100"C.

It is important that during the impregnation the impregnating substance penetrates into the whole elastic body or block and that a sufficient quantity of the impregnating substance is supplied so that the impregnation really provides means for maintaining of the elastic body or block in the compressed condition for an unlimited period of time, if the temperature is not increased to the value at which expansion occurs determined by the softening temperature of the impregnating substance. The quantity of the impregnating substance which has to be supplied depends upon many properties, for instance the rigidity and volume weight of the foamplastic. However, when impregnating a foamplastic sheet having a thickness of 7 mm. with the above mentioned impregnating substance a quantity of 1 kg. of the impregnating substance per square metre of the sheet proved to be sufficient.

As indicated above, the impregnating substance can consist of a single bituminous plastics material and this should have a softening temperature in the range of 70 200"C so that there is no risk of an unintentional expansion of the member due to an accidental increase of the temperature to the softening point of the impregnating substance. If the impregnating substance consists of a mixture of two bituminous plastics or corresponding substances, one should have a softening temperature in the range of 70 100 C and the other a softening temperature in the range of 150-200"C. Due to the fact that the two bituminous plastics forming the impregnating substance have softening temperatures at each end of the actual range of 70 200"C the softening temperature of the impregnating substance, which is normally the temperature at which the impregnated elastic body can expand due to the inherent elastic forces, can be chosen over the whole range or interval by variation only of the quantity ratio between the two bituminous plastics materials.

A member may be according to the inven tion primarily intended to be used in manufacturing processes in which heat is supplied during one or more of the manufacturing steps so that the member then expands to a predetermined thickness. For instance, one application is in doors or elements manufactured of metal. In manufacturing such products the metal surfaces are required to be washed before the final treatment which frequently is a painting procedure. During this wash washing liquid may penetrate into the door or the element and is absorbed by an elastic body inserted in the door or element, if this body is in an expanded condition.

However, if the body is a member in accordance with this invention in a compressed condition, the body does not absorb any liquid. When the body later is caused to expand, the expansion of the body facilitates the expelling of liquid from the washed door or element. As the washing procedure normally takes place at a temperature of not more than 70"C, it is necessary that the softening temperature of the impregnating substance is higher than 70"C. Preferably, the softening temperature should be at 100"C or slightly above, because any remaining water has boiled off at this temperature.

As mentioned above, the compressed member in accordance with this invention can be used for sound insulation and/or filling up of cavities and can, if desired, be shaped as an elongated strip and be used as a sealing strip.

WHAT WE CLAIM IS: 1. A compressed expandable member comprising a body of a foamed material having open cells, substantially the whole body of foamed material being impregnated with a substance having a predetermined softening temperature within the range of 70 C-200 C so that the body of foamed material is maintained in the compressed condition as long as the temperature does not exceed a limit value which depends upon the softening temperature of the impregnating substance.

2. A member according to claim 1 in which the foamed material is a foam-plastic material and the impregnating substance contains at least one thermo-plastics material having a softening temperature of 70"C or above.

3. A member according to any one of the preceding claims wherein the body of foamed material is impregnated with a substance containing a mixture of two different thermoplastics having different softening temperatures.

4. A member according to claim 3, wherein one of said plastics has a softening temperature in the range of 70-100 C and the other of said bituminous plastics has a softening temperature in the range of 150-200 C.

5. A compressed member substantially as herein described by way of example.

6. A method of forming a compressed member comprising the steps of impregnating a body of a foamed material having open cells with an impregnating substance which has a predetermined softening temperature within the range of 70"C-200"C, and which is above said softening temperature during the impregnating step, and cooling said member in a compressed condition to produce a compressed expandable member that will remain in the compressed condition as long as the temperature does not exceed a limit value which depends on the softening temperature of the impregnating substance.

7. A method according to claim 6 wherein the body is a foam plastic material.

8. A method according to claim 6 or 7 wherein the impregnating substance contains at least one thermo-plastics material having a softening temperature of 70"C or above.

9. A method according to any one of claims 6 to 8 wherein the impregnating substance contains a mixture of two thermoplastics materials having different softening temperatures.

10. A method according to claim 9 wherein one of said plastics materials has a softening temperature in the range of 70 100"C and the other has a softening temperature in the range of 150-200 C.

11. A method of forming a compressed member substantially as herein described by way of example.

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

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. tion primarily intended to be used in manufacturing processes in which heat is supplied during one or more of the manufacturing steps so that the member then expands to a predetermined thickness. For instance, one application is in doors or elements manufactured of metal. In manufacturing such products the metal surfaces are required to be washed before the final treatment which frequently is a painting procedure. During this wash washing liquid may penetrate into the door or the element and is absorbed by an elastic body inserted in the door or element, if this body is in an expanded condition. However, if the body is a member in accordance with this invention in a compressed condition, the body does not absorb any liquid. When the body later is caused to expand, the expansion of the body facilitates the expelling of liquid from the washed door or element. As the washing procedure normally takes place at a temperature of not more than 70"C, it is necessary that the softening temperature of the impregnating substance is higher than 70"C. Preferably, the softening temperature should be at 100"C or slightly above, because any remaining water has boiled off at this temperature. As mentioned above, the compressed member in accordance with this invention can be used for sound insulation and/or filling up of cavities and can, if desired, be shaped as an elongated strip and be used as a sealing strip. WHAT WE CLAIM IS:

1. A compressed expandable member comprising a body of a foamed material having open cells, substantially the whole body of foamed material being impregnated with a substance having a predetermined softening temperature within the range of 70 C-200 C so that the body of foamed material is maintained in the compressed condition as long as the temperature does not exceed a limit value which depends upon the softening temperature of the impregnating substance.

2. A member according to claim 1 in which the foamed material is a foam-plastic material and the impregnating substance contains at least one thermo-plastics material having a softening temperature of 70"C or above.

3. A member according to any one of the preceding claims wherein the body of foamed material is impregnated with a substance containing a mixture of two different thermoplastics having different softening temperatures.

4. A member according to claim 3, wherein one of said plastics has a softening temperature in the range of 70-100 C and the other of said bituminous plastics has a softening temperature in the range of 150-200 C.

5. A compressed member substantially as herein described by way of example.

6. A method of forming a compressed member comprising the steps of impregnating a body of a foamed material having open cells with an impregnating substance which has a predetermined softening temperature within the range of 70"C-200"C, and which is above said softening temperature during the impregnating step, and cooling said member in a compressed condition to produce a compressed expandable member that will remain in the compressed condition as long as the temperature does not exceed a limit value which depends on the softening temperature of the impregnating substance.

7. A method according to claim 6 wherein the body is a foam plastic material.

8. A method according to claim 6 or 7 wherein the impregnating substance contains at least one thermo-plastics material having a softening temperature of 70"C or above.

9. A method according to any one of claims 6 to 8 wherein the impregnating substance contains a mixture of two thermoplastics materials having different softening temperatures.

10. A method according to claim 9 wherein one of said plastics materials has a softening temperature in the range of 70 100"C and the other has a softening temperature in the range of 150-200 C.

11. A method of forming a compressed member substantially as herein described by way of example.