Glass Yarns For Reinforcing Organic and/or Inorganic Materials
The invention relates to glass reinforcement strands whose composition comprises the following constituents in the limits defined below, expressed as percentages by weight: SiO 2 50-65% Al 2 O 3 12-20% CaO 12-17% MgO 6-12% CaO/MgO ≦2, preferably ≧1.3 Li 2 O 0.1-0.8%, preferably ≦0.6% BaO + SrO 0-3% B 2 O 3 0-3% TiO 2 0-3% Na 2 O + K 2 O <2% F 2 0-1% Fe 2 O 3 <1%. These strands are made of a glass offering an excellent compromise between its mechanical properties, represented by the specific Young's modulus, and its melting and fiberizing conditions.
1 . A glass reinforcement strand whose composition comprises the following constituents in the limits defined below, expressed as percentages by weight:
SiO 2
50-65%
Al 2 O 3
12-20%
CaO
12-17%
MgO
6-12%
CaO/MgO
≦2
Li 2 O
0.1-0.8%
BaO + SrO
0-3%
B 2 O 3
0-3%
TiO 2
0-3%
Na 2 O + K 2 O
<2%
F 2
0-1%
Fe 2 O 3
<1%.
2 . The glass strand as claimed in claim 1 , characterized in that the composition has an Al 2 O 3 +MgO+Li 2 O content equal to 23% or higher.
3 . The glass strand as claimed in claim 1 , characterized in that the composition has an SiO 2 +Al 2 O 3 content of greater than 70%.
4 . The glass strand as claimed in claim 1 , characterized in that the composition has an Al 2 O 3 /(Al 2 O 3 +CaO+MgO) weight ratio that ranges from 0.40 to 0.44.
5 . The glass strand as claimed in claim 1 , characterized in that the composition comprises the following constituents:
SiO 2
58-63%
Al 2 O 3
13-18%
CaO
12.5-15%
MgO
7-9%
CaO/MgO
1.5-1.9
Li 2 O
0.1-0.5%
BaO + SrO
0-1%
B 2 O 3
0-2%
TiO 2
0-0.5%
Na 2 O + K 2 O
<0.8%
F 2
0-1%
Fe 2 O 3
<0.5.%.
6 . The glass strand as claimed in claim 1 , characterized in that it contains no B 2 O 3 or F 2 .
7 . An assembly of glass strands, especially in the form of woven fabric, characterized in that it comprises glass strands as defined in claim 1 .
8 . A composite consisting of glass strands and organic and/or inorganic material(s) characterized in that it comprises glass strands as defined by claim 1 .
9 . A glass composition suitable for producing glass reinforcement strands, comprising the following constituents in the limits defined below, expressed as percentages by weight:
SiO 2
50-65%
Al 2 O 3
12-20%
CaO
12-17%
MgO
6-12%
Ca/MgO
≦2
Li 2 O
0.1-0.8%
BaO + SrO
0-3%
B 2 O 3
0-3%
TiO 2
0-3%
Na 2 O + K 2 O
<2%
F 2
0-1%
Fe 2 O 3
<1%.
10 . The composition as claimed in claim 9 , characterized in that it has a forming range (T(log η=3)−T liquidus ) of more than 50° C.