Glass fiber structure designed to reinforce bonded abrasive articles
The invention relates to a structure based on glass fiber coated with a resin composition designed to reinforce bonded abrasive articles, the resin composition including the following constituents in the proportions indicated, expressed in percentage by weight of solid matter: 75 to 98% of a mixture of at least one novolac having a glass transition temperature lower than or equal to 60° C. and at least one novolac having a glass transition temperature above 60° C., 0.5 to 10% of at least one wax, 0 to 3.5% of at least one plasticizing agent.
1. A glass fiber structure coated with a resin composition, wherein the resin composition comprises the following constituents in the proportions indicated, expressed in percentage by weight of solid matter but the resin composition does not comprise a crosslinking agent:
75 to 98% of a mixture of a least one first novolac having a glass transition temperature lower than or equal to 60° C. and at least one second novolac having a glass transition temperature above 60° C.,
0.5 to 10% of at least one wax,
0 to 3.5% of at least one plasticizing agent.
2. The structure as claimed in claim 1 , wherein the first novolac represents 50 to 80% by weight of the mixture of novolacs.
3. The structure as claimed in claim 1 , wherein the first novolac has a glass transition temperature above 40° C.
4. The structure as claimed in claim 1 , wherein the second novolac has a glass transition temperature above or equal to 80° C.
5. The structure as claimed in claim 1 , wherein the first novolac and the second novolac are obtained by a process comprising reacting phenol and formaldehyde in a formaldehyde/phenol molar ratio that varies from 0.75 to 0.85.
6. The structure as claimed in claim 1 , wherein the wax is at least one paraffin wax, at least one ethylenebisamide wax, or a mixture thereof.
7. The structure as claimed in claim 1 , wherein the wax content does not exceed 5% by weight of solid matter of the resin composition.
8. The structure as claimed in claim 1 , wherein the plasticizing agent is alkylphosphate, phthalate, triethanolamine, oil, polyhydric alcohol or a mixture thereof.
9. The structure as claimed in claim 1 , wherein the plasticizing agent content does not exceed 1% by weight of solid matter of the resin composition.
10. The structure as claimed in claim 1 , wherein said structure comprises continuous glass yarns.
11. The structure as claimed in claim 10 , wherein the yarns have a diameter of from 9 to 24 μm.
12. The structure as claimed in claim 10 , wherein the yarns have a count, or linear mass, of between 34 and 4800 tex.
13. The structure as claimed in one of claims 1 , wherein said structure is in the form of a fabric having a grammage varying from 100 to 1000 g/m 2 .
14. A bonded abrasive article comprising abrasive particles bonded with a binder, wherein said article comprises a reinforcing structure as claimed in claim 1 .
15. The article as claimed in claim 14 , further comprising an abrasive grinding wheel.
16. The structure of claim 6 , wherein the wax is a paraffin wax, wherein the paraffin wax is polyethylene or polypropylene.
17. The structure of claim 6 , wherein the wax is an ethylenebisamide wax, wherein the ethylenebisamide wax is N,N′-ethylenebis(steramide).
18. The structure as claimed in claim 1 , wherein the continuous glass yarns are in the form of a web, a mat, a mesh, fabric, or a mat of cut strands.