Lightweight composite material

Claim 2

A lightweight composite material comprising reinforcing fibers in a thermoplast matrix, the fibers being at least 50 mm in length and being three-dimensionally arranged in the material, and the thermoplast matrix being characterized by the presence of cavities therein.

Claim 3

A lightweight composite material according to claim 1 wherein the reinforcing fibers have a higher softening interval or melting point than the thermoplast matrix.

Claim 4

A lightweight composite material according to claim 1 wherein the proportion of reinforcing fibers is 15 to 90% by weight of the lightweight composite material.

Claim 5

A composite material comprising reinforcing fibers in a thermoplast matrix, the fibers being over 50 mm in length and being three-dimensionally arranged in the thermoplast matrix.

Claim 6

A composite material comprising reinforcing fibers in a thermoplast matrix, the fibers being over 50 mm in length and being three-dimensionally arranged in the thermoplast matrix.

Claim 7

Moulded parts and finished products consisting or containing the lightweight composite material according to claim 1.

Claim 8

Molded parts and finished products comprising the lightweight composite material according to claim 2.

Claim 9

Molded parts and finished products comprising the lightweight composite material according to claim 3.

Claim 10

A process for producing lightweight composite materials comprising reinforcing fibers provided in a thermoplast matrix, the reinforcing fibers being at least 50 mm in length, and the lightweight composite material being characterized by the presence of cavities in the thermoplast matrix, the process comprising: (a) providing a formation of said reinforcing fibers in a three-dimensional arrangement such that empty spaces define at least 30% by volume of the formation; (b) impregnating the formation with thermoplast at a temperature above the glass transition temperature of the thermoplast under pressure conditions sufficient to reduce the thickness of the formation by at least 10%, thereby forming a composite material; and (c) thermally treating the composite material using temperature and pressure conditions which induce expansion of the thickness of the composite material by at least 10%, whereby cavities are formed in the thermoplast matrix during expansion.

Claim 11

A process for producing lightweight composite materials comprising reinforcing fibers provided in a thermoplast matrix, the reinforcing fibers being at least 50 mm in length, and the lightweight composite material being characterized by the presence of cavities in the thermoplast matrix, the process comprising: (a) providing a formation of said reinforcing fibers in a three-dimensional arrangement such that empty spaces define at least 30% by volume of the formation; (b) impregnating the formation with thermoplast at a temperature above the glass transition temperature of the thermoplast under pressure conditions sufficient to reduce the thickness of the formation by at least 10%, thereby forming a composite material; and (c) thermally treating the composite material using temperature and pressure conditions which induce expansion of the thickness of the composite material by at least 10%, whereby cavities are formed in the thermoplast matrix during expansion.

Claim 12

A process as claimed in claim 8 wherein the temperature at which the formation is impregnated with thermoplast is below the melting point of the reinforcing fibers.

Claim 13

A process as claimed in claim 8 wherein the formation of the composite material is carried out in a press.

Claim 14

A process as claimed in claim 10 wherein the thermal treatment is carried out in a press.

Claim 15

A process as claimed in claim 11 wherein the formation of the composite material and the thermal treatment are carried out in successive cycles in a two-cycle press.

Claim 16

The process as claimed in claim 8 further comprising the step of introducing gas into the thermoplast matrix during the thermal treatment.

Claim 17

The process as claimed in claim 8 further comprising providing a gas-releasing substance in the thermoplast which is capable of producing gas in the thermoplast matrix upon thermal treatment.

Claim 18

A process for producing a composite material comprising reinforcing fibers provided in a thermoplast matrix, the reinforcing fibers being at least 50 mm in length, the comprising: (a) providing a formation of reinforcing fibers in a three-dimensional arrangement such that empty spaces define at lease 30% by volume of the formation; and (b) impregnating the formation with thermoplast at a temperature above the glass transition temperature of the thermoplast, under pressure conditions sufficient to reduce the thickness of the formation by at least 10%.

Claim 19

A process for producing a composite material comprising reinforcing fibers provided in a thermoplast matrix, the reinforcing fibers being at least 50 mm in length, the comprising: (a) providing a formation of reinforcing fibers in a three-dimensional arrangement such that empty spaces define at lease 30% by volume of the formation; and (b) impregnating the formation with thermoplast at a temperature above the glass transition temperature of the thermoplast, under pressure conditions sufficient to reduce the thickness of the formation by at least 10%.

Claim 20

A lightweight composite material produced by the process of claim 8.

Claim 21

A lightweight composite material produced by the process of claim 9.

Claim 22

A lightweight composite material produced by the process of claim 13.

Claim 23

A lightweight composite material produced by the process of claim 14.

Claim 24

A composite material produced by the process of claim 25.