GB1585016A - Reinforced plastics article - Google Patents

Description

(54) REINFORCED PLASTICS ARTICLE (71) We SKF NOVA AB, a Swedish Body Corporate, of S-415 50 Göteborg, 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 the following statement: The invention relates to a process of producing a reinforced plastics article and to the article.

Accordingly, in one aspect, the invention provides a process of producing a reinforced plastics article comprising providing a plastics which when cured is hard at room temperature, reinforcing fibres, and reinforcing particles of steel, combining the ingredients together and then curing the plastics, the proportions of the ingredients being such that the plastics form a continuous phase.

The invention includes an article produced by a process according to the immediately preceding paragraph.

In another aspect the invention provides a reinforced plastics article comprising a cured plastics which is hard at room temperature, reinforcing fibres, and reinforcing particles of steel, the plastics forming a continuous phase.

The particles may form in the range of 20 to 80% by weight of the weight of plastics and steel particles.

The steel particles may be in the size range of from 2 to 20 in one dimension and from 20 to 40011 in the other two dimensions.

The article may be a floor or a floor plate.

The accompanying drawing represents the results of some comparative tests. A number of test plates were made up each 150 x 150 x 5mm. Each plate was placed on a rigid base and a ball weighing 500gum was dropped onto each plate from varying heights. The height at which the plate was cracked or started cracking was noted.

Plates were tested consisting of a polyester; of polyester reinforced with a mat of glass fibres 300g/m2; of polyester reinforced with steel particles; in varying weight percentages of plastics plus steel, and of polyester reinforced with a glass fibre mat 300g/m2 and with steel particles in varying weight percentages of plastics plus steel. The steel particles were chips produced by grinding a steel of ball bearing quality, the particles having a size in the range of from 2 to 20 in one dimension and 20 to 400p in the other dimension (where > =10~6m). The surface area of the plate is 0.225m2 and therefore the mat weighed 67.5g.

The results were plotted on a graph of percentage weight of steel in a mixture of steel plus plastics against height in metres.

Point A is the height, 0.1 metres, at which the 500gm ball produced cracks in a plate consisting of polyester. Point B is the height, 0.2 metres, at which the ball produced cracks in a plate consisting of polyester reinforced with glass fibres. Reinforcing the plastics with glass fibres does therefore produce some benefit in impact strength.

Curve C is a best curve plotted on the points shown as circled crosses for polyester plates reinforced with steel particles in varying percentage weights. As can be seen there is a continuing improvement in impact strength although past 50% by weight steel particles plus 50% weight plastics there is little to be gained in adding more steel particles. Below about 10% steel particles plus 90% plastics by weight the strength of the plate is less than that of the plate reinforced with glass fibres only-point B.

From the separate results for glass fibre reinforcement and steel particle reinforcement, one would expect a combination of the two i.e. a plastics plate reinforced with both glass fibres and steel particles to produce a curve somewhat like curve E.

However when plates of polyester -rein forced with glass fibres and varying weight percentages of steel particles were tested, the results shown as crosses on the graph produced a best curve D. This was wholly unexpected. There can be seen to be a considerable improvement over the whole range of weight percent of steel particles although adding more steel particles to the plastics past about 50% produces diminishing increases in drop height of the ball before cracking occured. Past a steel particle content of 80% (that is 80 parts by weight steel to 20 parts by weight plastics) means that no continuous phase of plastics can be obtained so that the plates cannot be formed.

From the test results one can see that a floor produced from a plastics reinforced with a fibrous material such as a glass fibre mat and with particles of a permanently deformable material such as metal will be highly resistant to cracking by objects being dropped on it. The floor can be formed by producing plates of the reinforced plastics material according to the invention and laying them to produce a floor, or by mixing the plastics, fibrous material and particles, spreading the mixture on the ground and then curing the plastics to produce the floor.

The content of the particles in the reinforced plastics according to the invention is preferably large enough for substantially all of the particles each to be in contact with another.

The force resulting from an object dropped on to a test plate for example should then be transmitted through the particles and absorbed as work done in plastically deforming the particles. Particles such as silica sand would be crushed instead of being plastically deformed under impact without absorbing any appreciable energy.

A test plate of plastics reinforced with silica sand would therefore be cracked easier because the plastics itself would be absorbing a great deal of the impact. Particles of steel can absorb a great deal of impact energy by being plastically deformed and are therefore preferred.

The fibrous material used in the tests was a mat of glass fibre, and plastics reinforced with glass fibre are well known. However other fibrous materials may be suitable.

A variety of plastics may be used, thermosetting plastics, polymers and the like.

WHAT WE CLAIM IS: 1. A process of producing a reinforced plastics article comprising providing a plastics which when cured is hard at room temperature, reinforcing fibres, and reinforcing particles of steel, combining the ingredients together and then curing the plastics, the proportions of the ingredients being such that the plastics forms a continuous phase.

2. A process of producing a reinforced plastics article as claimed in claim 1 and substantially as herein described with reference to the accompanying drawing.

3. An article produced by a process as claimed in claim 1 or 2.

4. A reinforced plastics article comprising a cured plastics which is hard at room temperature, reinforcing fibres, and reinforcing particles of steel, the plastics forming a continuous phase.

5. An article as claimed in claim 4 wherein the particles form in the range of 20 to 80% by weight of the weight of plastics and steel particles.

6. An article as claimed in claim 4 wherein the particles are in the size range of from 2 to 20y in one dimension and from 20 to 400cm in the other two dimensions.

7. A plastics reinforced article as claimed in claim 4 and substantially as herein described with reference to the accompanying drawing.

8. A reinforced plastics article as claimed in any one of claims 4 to 7 wherein the article is a floor or a floor plate.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. forced with glass fibres and varying weight percentages of steel particles were tested, the results shown as crosses on the graph produced a best curve D. This was wholly unexpected. There can be seen to be a considerable improvement over the whole range of weight percent of steel particles although adding more steel particles to the plastics past about 50% produces diminishing increases in drop height of the ball before cracking occured. Past a steel particle content of 80% (that is 80 parts by weight steel to 20 parts by weight plastics) means that no continuous phase of plastics can be obtained so that the plates cannot be formed. From the test results one can see that a floor produced from a plastics reinforced with a fibrous material such as a glass fibre mat and with particles of a permanently deformable material such as metal will be highly resistant to cracking by objects being dropped on it. The floor can be formed by producing plates of the reinforced plastics material according to the invention and laying them to produce a floor, or by mixing the plastics, fibrous material and particles, spreading the mixture on the ground and then curing the plastics to produce the floor. The content of the particles in the reinforced plastics according to the invention is preferably large enough for substantially all of the particles each to be in contact with another. The force resulting from an object dropped on to a test plate for example should then be transmitted through the particles and absorbed as work done in plastically deforming the particles. Particles such as silica sand would be crushed instead of being plastically deformed under impact without absorbing any appreciable energy. A test plate of plastics reinforced with silica sand would therefore be cracked easier because the plastics itself would be absorbing a great deal of the impact. Particles of steel can absorb a great deal of impact energy by being plastically deformed and are therefore preferred. The fibrous material used in the tests was a mat of glass fibre, and plastics reinforced with glass fibre are well known. However other fibrous materials may be suitable. A variety of plastics may be used, thermosetting plastics, polymers and the like. WHAT WE CLAIM IS:

1. A process of producing a reinforced plastics article comprising providing a plastics which when cured is hard at room temperature, reinforcing fibres, and reinforcing particles of steel, combining the ingredients together and then curing the plastics, the proportions of the ingredients being such that the plastics forms a continuous phase.

2. A process of producing a reinforced plastics article as claimed in claim 1 and substantially as herein described with reference to the accompanying drawing.

3. An article produced by a process as claimed in claim 1 or 2.

4. A reinforced plastics article comprising a cured plastics which is hard at room temperature, reinforcing fibres, and reinforcing particles of steel, the plastics forming a continuous phase.

5. An article as claimed in claim 4 wherein the particles form in the range of 20 to 80% by weight of the weight of plastics and steel particles.

6. An article as claimed in claim 4 wherein the particles are in the size range of from 2 to 20y in one dimension and from 20 to 400cm in the other two dimensions.

7. A plastics reinforced article as claimed in claim 4 and substantially as herein described with reference to the accompanying drawing.

8. A reinforced plastics article as claimed in any one of claims 4 to 7 wherein the article is a floor or a floor plate.