Patent Application
20080032107
A strengthening material was produced consisting of three layers which were mutually connected according to the Rachel technique (for instance with a maliwatt machine from the Karl Mayer company), wherein use was made of a knitted net (weight 8 g/m2) of fine-textured polyester filament of 167 dtex.
The used middle layer, or thickness-providing layer, is a flat knit composed of a glass filament of glass yarn 136 tex. The middle layer or thickness-providing layer has a thickness of about 4 mm and a weight of about 900 g/m2.
Adhered on both sides to this middle layer or thickness-providing layer was a glass mat (strengthening layer), consisting of cut glass fibres of 50 mm length and a thickness of 25 tex, and a weight of 500 g/m2.
The total weight of the strengthening material expressed in weight/m2 is 500+900+500+8=1908 g/m2. The total thickness of the obtained strengthening material was about 5 mm.
In similar manner as described in comparative example 1, a strengthening material was produced consisting of three layers, the middle layer or thickness-providing layer (900 g/m2) of which consisted of a knit of glass filament and glass yarn, and the two outer layers or strengthening layers (450 g/m2) consisted of a glass mat.
The total weight of the strengthening material expressed in weight/m2 is 300+900+300+8=1508 g/m2. The total thickness of the obtained strengthening material was about 4.5 mm.
A strengthening material according to the present invention was produced consisting of three layers mutually connected according to the Rachel technique (for instance with a maliwatt machine from the Karl Mayer company), wherein use was made of a knitted net (weight 8 g/m2) of fine-textured polyester filament of 167 dtex.
This strengthening material can be designated as a “sandwich” construction, such as for instance a honeycomb, wherein the middle layer serves as spacer or thickness-providing layer between the two outer layers, the main function of which is to provide strength or reinforcement.
The used middle layer or thickness-providing layer is a flat knit composed of a glass filament, glass yarn 136 tex, and a polyethylene filament (PE), 33 tex monofilament, in a ratio of 136 glass to 33 PE. The middle layer or thickness-providing layer has a thickness of about 4 mm and a weight of about 280 g/m2.
Adhered on both sides to this middle layer or thickness-providing layer was a glass mat (strengthening layer), consisting of cut glass fibres of 50 mm length and a thickness of 25 tex, and a weight of 500 g/m2.
The obtained strengthening material is deformable and permits stretch of more than 75%. The total weight of the strengthening material expressed in weight/m2 is 500+280+500+8=1288 g/m2. The total thickness of the obtained strengthening material is about 4.8 mm.
In similar manner as described in example 1, a strengthening material was produced consisting of three layers, the middle layer or thickness-providing layer of which consisted of a knit of glass filament, glass yarn 136 tex, and a polyethylene filament (PE), 33 tex monofilament, in a ratio of 136 glass to 33 PE.
The middle layer or thickness-providing layer has a thickness of about 4 mm and a weight of about 280 g/m2. The two outer layers or strengthening layers (450 g/m2) consisted of a glass mat. The total weight of the strengthening material expressed in weight/m2 is 450+280+450+8=1188 g/m2. The total thickness of the obtained strengthening material was about 4.7 mm.
In similar manner as described in example 1, strengthening materials 3a to 3k according to table 1 were produced consisting of three layers, the middle layer or thickness-providing layer of which consisted of a knit of glass filament, glass yarn 136 tex, and a polyethylene filament (PE), 36 tex monofilament. All strengthening materials had a glass polyethylene (PE) ratio of 1 thread glass to 3 or 4 monofilaments polytheylene and a total thickness varying in the range of 4 to 5 mm. The weights of the thickness providing layers and the strengthening layers are depicted in Table 1.
The thickness under a determined pressure of the strengthening material according to example 1 and comparative example 1 were compared, and it was found that strengthening material according to the present invention displayed about 7% less compression at the same pressure. The strengthening materials were compared under different pressures (vacuum) and the results hereof are shown in table 2.
Table 2 shows that the strengthening material according to the present invention provides a weight-saving of 620 g/m2, and in addition provides less compression under pressure, which will result in a thicker composite and a better resin transport.
Improved resistance to compression as compared to similar strengthening materials comprising a thickness providing layer of only a glass knit of the same weight were obtained using the strengthening materials 3a to 3k according to example 3.
A composite, in this case a helmet, was manufactured using the so-called “vacuum technique closed mould system”. In summary, a first film was placed in a mould and the strengthening material according to example 2 and a polyester resin were placed thereon. A second film was then placed on the strengthening material according to example 2 and, after the edges of the first film and the second film were closed, a vacuum was created between the mould and the first foil and between the first and the second film.
Under the influence of the vacuum the strengthening material was modelled as according to the shape of the mould and the resin was simultaneously pressed to the outer ends of the strengthening material. After impregnating the resin in the strengthening material, i.e. through the thickness-providing layer and into the strengthening layers, and after curing of the resin, a modelled composite was obtained in the form of a helmet.
This method was repeated wherein use was made of the strengthening material according to comparative example 2 instead of the strengthening material of example 2.
The time required for a full impregnation of both strengthening materials was measured, and this is shown in table 3.
Table 3 shows that the strengthening material according to the present invention provides at least three advantages: 1) a shorter production time, 2) a stronger composite (900 g/m2 against 600 g/m2 strengthening material) with a lower weight (1188 g/m2 against 1508 g/m2), and 3) a saving of raw materials and hence a cheaper product.
Reduced impregnation times as compared to strengthening materials comprising a thickness providing layer of a glass knit of the same weight were obtained using the strengthening materials 3a to 3k according to example 3.
A composite was manufactured using the so-called “injection technique closed mould system”. In summary, the strengthening material according to example 2 was placed in a closed mould, in this case a mould for a helmet, with a cavity of 3 mm. After the mould had been closed, polyester resin was injected under pressure. After impregnation of the resin through the thickness-providing layer and into the strengthening layers, a composite in the form of a helmet was obtained after curing.
This method was repeated wherein use was made of the strengthening material according to comparative example 2 instead of the strengthening material of example 2.
The time required for a full impregnation of both strengthening materials was measured, and this time is shown in table 3.
Table 4 shows that the strengthening material according to the present invention provides at least three advantages: 1) a shorter production time, 2) a stronger composite (900 g/m2 against 600 g/m2 strengthening material) with a lower weight (1188 g/m2 against 1508 g/m2), and 3) a saving of raw materials and hence a cheaper product.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1025846 | Mar 2004 | NL | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/03369 | 3/29/2005 | WO | 00 | 5/25/2007 |
