Ion exchange strengthening of soda-lime-silica glass

Claim 2

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 2 to 4.5 percent by weight ZrO 2 and 0 to 4.5 percent by weight Al 2 O 3 ; the CaO content being restricted to 6 to 8.5 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 3

The glass of claim 1 wherein the Al 2 O 3 concentration is zero.

Claim 4

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 0 to 4.5 percent by weight ZrO 2 and 2.5 to 4.5 percent by weight Al 2 O 3 ; the CaO content being restricted to 6 to 8.5 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 5

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 0 to 4.5 percent by weight ZrO 2 and 2.5 to 4.5 percent by weight Al 2 O 3 ; the CaO content being restricted to 6 to 8.5 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 6

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, 0 to 5 percent by weight MgO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 2 to 4.5 percent by weight ZrO 2 and 0 to 4.5 percent by weight Al 2 O 3 up to a total of 4.5 weight percent Al 2 O 3 and ZrO 2 ; the CaO content being restricted to 4 to 8.5 weight percent and the total CaO and MgO content being restricted to 6 to 13 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 7

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, 0 to 5 percent by weight MgO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 2 to 4.5 percent by weight ZrO 2 and 0 to 4.5 percent by weight Al 2 O 3 up to a total of 4.5 weight percent Al 2 O 3 and ZrO 2 ; the CaO content being restricted to 4 to 8.5 weight percent and the total CaO and MgO content being restricted to 6 to 13 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 8

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, 0 to 5 percent by weight MgO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 0 to 4.5 percent by weight ZrO 2 and 2.5 to 4.5 percent by weight Al 2 O 3 up to a total of 4.5 weight percent Al 2 O 3 and ZrO 2 ; the CaO content being restricted to 4 to 8.5 weight percent and the total CaO and MgO content being restricted to 6 to 13 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 9

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, 0 to 5 percent by weight MgO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 0 to 4.5 percent by weight ZrO 2 and 2.5 to 4.5 percent by weight Al 2 O 3 up to a total of 4.5 weight percent Al 2 O 3 and ZrO 2 ; the CaO content being restricted to 4 to 8.5 weight percent and the total CaO and MgO content being restricted to 6 to 13 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 10

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, 0 to 5 percent by weight MgO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 3 to 4.5 percent by weight ZrO 2 and/or Al 2 O 3 ; the CaO content being restricted to 4 to 8.5 weight percent and the total CaO and MgO content being restricted to 6 to 13 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.

Claim 11

In a glass composition of the conventional soda-lime-silica flat glass type which consists of SiO 2 as the major constituent, 12 to 16 percent by weight Na 2 O, 0 to 2 percent by weight K 2 O, but no more than 17 percent by weight total of Na 2 O and K 2 O, a substantial inclusion of CaO, 0 to 5 percent by weight MgO, optionally a relatively small amount of Al 2 O 3 , and 0 to 2 percent by weight total of SO 3 and colorants, essentially free of Li 2 O, and exhibiting a melting temperature less than about 2850° F. and a working range greater than about 90° F., the improvement comprising: enhanced ion exchange strengthening below the strain point by virtue of an elevated annealing point above 1030° F. by the inclusion of 3 to 4.5 percent by weight ZrO 2 and/or Al 2 O 3 ; the CaO content being restricted to 4 to 8.5 weight percent and the total CaO and MgO content being restricted to 6 to 13 percent by weight to avoid reducing the working range; whereby the SiO 2 remainder is 67 to 74 percent by weight.