FR2773556A1 - GLASS COMPOSITIONS FOR THE MANUFACTURE OF GLAZING - Google Patents

Abstract

The invention concerns a silico-sodocalcic glass composition in particular for producing glazing sheets and comprising the constituents listed below with contents expressed in percentage by weight, defined within the following limits: SiO2 74-80 %; B2O3 0-2 %; MgO 0.3-4 %; CaO 1-10 %; Na2O 11-17 %; K2O 0.3-1.5 %; Al2O3 0.2-2 %; Fe2O3 0.2-2 % where Fe2O3 is total iron for a thickness of 3.5 mm, the global energy transmission TEis less than 46 %, and preferably less than 45 %, the ultraviolet transmission TU.V.ISO is less than 18.5 % and preferably less than 15 %.

Description

GLASS COMPOSITIONS FOR

TO THE MANUFACTURE OF GLAZING

  The invention relates to new glass compositions of the silica type.

  soda-lime more particularly intended for the manufacture of glazing. Although not limited to such applications, the invention will be more

  specially described with reference to automobile glazing.

  Glazing intended for the automotive industry is subject to various requirements, in particular as regards their optical properties; these requirements are governed by regulations, for example when it comes to the light transmission of a windshield or for the sake of user comfort, for example with regard to energy transmission or else

  again for the sake of aesthetics, especially with regard to color.

  In addition, for some time, manufacturers have been moving towards a new requirement concerning the transmission of ultraviolet light. This new trend aims to protect the skin from the sun by avoiding tanning and sunburn. Another aim of this trend is to limit the fading of the fabrics that adorn the interior of

motor vehicles.

  It is known that iron, in its form of ferric ions Fe3 +, that is to say in the form Fe203, makes it possible to obtain absorption in the ultraviolet. It is also known that iron, in its form of ferrous ions Fe2 +, that is to say in the form FeO, makes it possible to obtain absorption in the infrared and therefore

energy absorption.

  It is thus known that the regulation of redox (coefficient of oxido-

  reduction) of a glass composition makes it possible to regulate the absorption in the ultraviolet compared to that in the infrared with regard to the action of iron. -2 - It has moreover already been described, in particular in patent application WO94 / 14716, that cerium oxide CeO2 has an effect on absorption in the ultraviolet. However, the introduction of this oxide leads to a very significant additional cost of the composition due to the cost of the raw materials allowing the introduction of this oxide. It has also already been described, in particular in US Pat. No. 5,478,783 that titanium oxide TiO2 also has an effect on absorption in the ultraviolet. If the cost of introducing TiO2 into a glass matrix is lower than that

  of CeO2, it is still very high.

  It is also known in particular from document WO94 / 14716 to combine the two oxides CeO2 and TiO2, again with the aim of better absorption in the ultraviolet. Such a combination does not of course limit

  the additional cost due to the introduction of these oxides into a glass matrix.

  Furthermore, the manufacturers' desire is always to reduce the

  cost of manufacturing vehicles and therefore that of glazing.

  The inventors have therefore given themselves the task of producing new glass compositions having the required optical properties, in particular in terms of energy transmission and transmission.

  ultraviolet and with reduced manufacturing costs.

  This object is achieved according to the invention by a glass composition of the soda-lime-silica type intended in particular for the production of glazing, comprising the following constituents, according to contents, expressed in percentages by weight, defined by the following limits SiO2 74-80%

B203 0- 2%

  MgO 0.3 - 4% CaO 1 - 10% Na20 11 -17%

K20 0.3-1.5%

A1203 0.2- 2%

  Fe203 0.2- 2% o Fe203 is the total iron

"2773556

  - 3 - And the glass matrix having, for glazing thicknesses of 3.85 mm, an overall energy transmission TE of less than 46%, and preferably less than 45%, more preferably still less than 43% and an ultraviolet transmission Tu.v . Iso less than 18.5%, and preferably less than 15% and more preferably less than 10%. The matrix according to the invention, rich in silica, makes it possible to limit production costs, in particular because of the raw material providing the SiO2 oxide which is inexpensive. On the other hand, the matrices according to the invention have the advantage of having relatively low densities; the price of the glass being usually established by weight, it appears that in terms of glazing, the compositions according to the invention further reduce the price

said glazing.

  Furthermore, the glasses obtained according to the invention have a lower refractive index than standard soda-lime type glasses and have

  thus greater anti-reflection power.

  More preferably, the silica content is greater than or equal to 76%.

  The viscosity of the glasses according to the invention can make it more difficult to merge according to usual methods. However, it is also possible to carry out the merger using techniques such as those described in the request for

French patent FR98 / 00176.

  A1203 oxide is used in very small quantities, as it also contributes to an increase in viscosity and a decrease in

visible transmission.

  The alkaline oxides Na20 and K20 facilitate the melting of the glass and adjust its viscosity at high temperatures. K20 is

  advantageously used with contents of less than 1.5%.

  The alkaline earth oxides introduced into the glasses according to the invention have the overall effect of increasing the viscosity at high temperatures. The CaO content must not exceed 10% to keep the devitrification of the glasses within acceptable limits. That in MgO is advantageously less than 4% for similar reasons and in addition to improve the

  absorption properties in infrared.

  - 4 - BaO which makes it possible to increase the light transmission, can be added in the compositions according to the invention in contents of less than 4%. Indeed, BaO has a much weaker influence than MgO and CaO on the viscosity of the glass. In the context of the invention, the increase in BaO takes place essentially to the detriment of alkaline oxides, of MgO and especially of CaO. Any significant increase in BaO therefore contributes to increasing the viscosity of the glass, in particular at low temperatures. In addition, the introduction of a high percentage of BaO significantly increases the cost of

  the composition and tends to reduce the hydrolytic resistance of the glass.

  When the glasses of the invention contain barium oxide, the percentage of this oxide is preferably between 0.5 and 3.5% by weight. The glass compositions according to the invention can also comprise oxide B203. The B203 content then does not exceed 2% because, beyond this value, the volatilization of boron in the presence of alkaline oxides during the production of the glass can become non-negligible and can lead to corrosion of the refractories in the case conventional fusion techniques. In

  in addition, higher levels of B203 adversely affect the quality of the glass.

  According to a first alternative embodiment, the total iron content is such that Fe 2 O 3> 1%. Such an embodiment is particularly favorable when the desired light transmission is not too high, for example in the case of side glazing or else of roofs for automobiles, or even for example, when the requirements concerning the light transmission are greater by example in the case of windshield or

  rear glasses made with thinner lenses.

  According to another alternative embodiment, the total iron content is such that Fe 2 O 3 <0.6. More particularly according to this latter variant, the glass composition according to the invention further comprises a functional agent absorbing ultraviolet radiation such as CeO2, TiO2, WO3, ... or a combination of two or more of these oxides. Regarding the CeO2 oxide, its weight content can range up to 1.5% and is preferably between 0.3 and 0.8% by weight. The TiO2 content by weight can be between 0.1 and 2% and advantageously does not exceed 1.2%. W03 oxide can

  to be present to it with weight contents of between 0.1 and 1.2%.

  The latter oxide will be preferred to the other two, since the raw materials which make it possible to introduce it into the glass composition according to the invention are more economical. The presence of these functional agents authorizes

  easily ultraviolet transmissions below 10%.

  When the desire is to produce colored glasses, the glass compositions can also comprise one or more coloring agents such as

CoO, Se, Cr203, NiO.

  The glasses according to the invention may also contain up to 1% of other constituents provided by the impurities of the vitrifiable raw materials and / or due to the introduction of cullet into the vitrifiable mixture.

  and / or resulting from the use of refining agent (SO3, Cl, Sb203, As203).

  According to a first alternative embodiment and more particularly for automotive applications such as windshields or front side windows, the overall light transmission factor under illuminant A (TLA) is greater

or equal to 70%.

  According to another alternative embodiment of the invention and more particularly for automotive applications such as rear side windows and rear glasses, the light transmission factor

  overall under illuminant A (TLA) is less than or equal to 55%, or even 35%.

  According to a third alternative embodiment of the invention and more particularly for applications such as roofs for cars, the overall light transmission factor under illuminant A (TA) is lower

or equal to 10%.

  To facilitate the fusion and in particular to make it achievable according to the usual fusion techniques, the matrix advantageously has a temperature, corresponding to a viscosity q, expressed in poise, such as logq = 2, of less than 1550 C and preferably less than 1500 C. More preferably and in particular for the production of the substrate from a glass ribbon obtained according to the "float" technique, the matrix has a temperature corresponding to the viscosity i, expressed in poise, such that logq = 3, 5, Tlogrl = 3.5 and a liquidus temperature Tliq, satisfying the relationship T (logTr = 3.5) - Tliq> 0 C and preferably T (logl = 3.5) - Tliq> 20 C, and preferably again the relation: T (logi = 3.5) - Tijq> 50 C, Other details and advantageous characteristics will emerge below

  of the description of exemplary embodiments according to the invention.

  A series of glasses has been produced from compositions shown in the table below. These compositions were prepared under redox conditions, such that the redox is between 0.12 and 0.28. The optical properties are measured for a light transmission equal to 71%. This table also indicates the values of the following properties - the overall light transmission factor under illuminant A (TLA) between 380 and 780 nm, - the overall energy transmission factor TE integrated between 295 and 2500 nm according to the Parry Moon Masse 2 standard, '- the transmission factor in the integrated ultraviolet between 295 and 380 nm, Tu.v. ISO, according to standard ISO 9050, the dominant wavelength under illuminant C, the density - the refractive index The table also shows the temperatures corresponding to the viscosities l, expressed in poise, such as logl = 2 and logq = 3.5, Tlog2 and

  Tlog3.5 as well as the liquidus temperature Thq.

-7-

TABLE 1

  1i 2 3 4 5 6 7 8 9 SiO2 74 74 74 _ 77.2 78.4 74 74 76.7 80

B203 0 2 0 O 2 2 2 O 0.95 O

  MgO 0.3 4 3.2 4 4 0.3 3.2 2.1 4 CaO 9.9 1.2 10 1 1 9.1 1 3.4 1.7 Na20 11 17 11 11 11 11 17 13, 7 11

  K20 1.5 0.3 0.3 1.5 1.5 0.3 1.5 0.85 0.3

A1203 2 0.2 0.2 2 2 2 2 1 2

  Fe203 1.17 1.1 0.93 1.1 1.11 0.97 1.01 1.09 1.08 FeO 0.212 0.128 0.163 0.152 0.143 0.179 0.119 0.156 0.145 Density 2,481 2,442 2,480 2,395 2,383 2,480 2,432 2,429 2,388 refraction 1.5155 1.5062 1.5201 1.4983 1.4968 1.5179 1.5011 1.5044 1.4972

TLA (%) 71 71 71 _ 71 71 71 71 71 71 71

  TE (%) 43.6 43.2 45.6 44.7 45.4 44.7 42.3 43.2 45.5

  TU.V.ISO (%) 13.6 13.9 14 14.4 15 11.1 17.5 15.6 22.8

  Ud (D65) nm 533 509 530 533 531 538 511 515 517 Tlog2 (C) 1528 1461 1502 1673 1717 1522 1522 1554 1738 Tlog3.5 (C) 1153 _ 1095 1146 1234 1247 1152 1125 1153 1384 c Tlog4 (C) 1074 1021 1069 1141 1155 1073 1042 1067 1173 Tia1070 1010 1145 1160 116 10705 1120 12600 -8 -

TABLE 2

11 12 13 14 15 16

SiO2 74 74 74 74 77.2 74 76.7

B203 2 2 0 0 2 0 0.95

  MgO 4 4 3.2 3.2 4 3.2 2.1 CaO 1, 2 1.2 10 10 1 1 3.4 Na20O 17 17 il 11 11 11 17 13.7

K20 0.3 0.3 0.3 0.3 1.5 1.5 0.85

A1203 0.2 0.2 0.2 0.2 2 2 1

  Fe203 1,353 1,1083 1,193 0.997 1,168 1,219 1,071 FeO 0, 203 0.222 0.178 0.199 0.21 0.219 0.193 Density 2,442 2,442 2,480 2,480 2,395 2,432 2,429 Index of 1.5062 1.5062 1.5201 1.5201 1.4983 1 , 5011 1.5044 refraction

TLA (%) 71 71 71 71 71 71 71 71

  TE (%) 42.2 41.5 45.5 44.7 42.7 41.3 43.4

  TU.V.ISO (%) 17.3 21.8 12.1 15.4 15.9 20.7 17.5

  Tiog2 (C) 1461 1461 1502 1502 1673 1522 1554 Tlog3.5 (C) 1095 1095 1146 1146 1 234 1125 1153 Tlog4 (C) 1021 1021 1069 1069 1141 1042 1067 Tliq 1010 1010 1 1 45 1145 1160 1070 1120

  From the compositions prepared, the inventors further defined other compositions by modifying the matrices.

  These compositions are presented in Table 3 below

TABLE 3

17 18 19 20 21 22 23 24

  SiO2 74.1 75.1 75.7 75.7 76 76.1 77 78

B203O 0 1 0 0 0 0 0

  MgO 4 3.7 2.1 2.1 1.8 0.4 0.4 0.4 CaO 4.4 3.5 3.5 3.5 3.5 3.1 3 2 Na2O 13.5 5, 9 13.9 14.7 14.9 16.5 15.6 17 K2O 1.5 1.5 1.5 1.5 1.5 1.5 1.5 0.5

A1203 1 1 1 1 1 1 1 0.5

  Fe203 1.18 1.12 1.043 1.2 1.15 1.37 1.2 1.3 II FeO 0.208 0.17 0.2 0.2 0.18 0.1760.18 0.18 Density 2.452 2,438 2,436 2,436 2,434 2,434 2,426 2,416 1.5080 index 1.5050 1.5050 1.5040 1.5040 1.5030 1.5010 1.4990 refraction

TLA (%) 71 71 71 71 71 71 71 71 71

  TE (%) 42.9 44.3 43 42.8 43.7 43.4 43.3 42.9

  TU.V.ISO (%) 16.7 18.5 18.2 18.3 18.9 17.1 19.4 19.5

  Tlog2 (C) 1537 1552 1540 1530 1259 1481 1521 1506 Tlog3.5 (C) 1151 1157 1145 1137 1135 1099 1124 1109 Tlog4 (C) 1067 1072 1062 1054 1053 1020 1043 1031 Tliq 1061 1075 1104 1085 1089 1089 1 108 1106 The compositions developed and those redefined from the measured results show that the invention makes it possible to obtain new glass compositions having enhanced optical properties and in particular relatively weak ultraviolet transmission at reduced costs compared to

to known techniques.

Claims (10)

  1. Composition of glass of the soda-lime-silica type intended in particular for the production of glazing, characterized in that it comprises the following constituents according to contents, expressed in percentages by weight, defined by the following limits SiO2 74- 80% B203 0- 2%   MgO 0.3- 4% CaO 1 -10% Na20 11 - 17% K20 0.3-1.5% A1203 0.2 - 2%   Fe203 0.2- 2% o Fe203 is the total iron and in that for a thickness of 3.85 mm, the overall energy transmission TE is less than 46%, and preferably less than 45%, and in that the transmission ultraviolet Tu.v. Iso is less than 18.5% and preferably less than 1 5%.   2. Glass composition according to claim 1, characterized in that   the total iron content is such that Fe203> 1%.   3. Glass composition according to claim 1, characterized in that   the total iron content is such that Fe 2 O 3 <0.6%.   4. Glass composition according to one of the preceding claims,   characterized in that it further comprises at least one functional agent such than CeO2, TiO2, WO3.   5. Glass composition according to one of claims 1 to 4,   characterized in that the overall light transmission factor under   illuminant A (TLA) is greater than or equal to 70%.   6. Glass composition according to one of claims 1 to 4,   characterized in that the overall light transmission factor under   illuminant A (TLA) is less than or equal to 55%, and preferably 35%. l1   7. Glass composition according to one of claims 1 to 4,   characterized in that the overall light transmission factor under   illuminant A (TLA) is less than or equal to 10%.   8. Glass composition according to one of the preceding claims,   characterized in that it further comprises at least one coloring agent such as CoO, Se, Cr203, NiO.   9. Glass composition according to one of the preceding claims,   characterized in that the difference between the temperature corresponding to a viscosity T, expressed in poise, such as logq = 3.5, and the liquidus temperature Tiq, is positive and preferably greater than 20 C and preferably still higher than 50 C.   10. Glass composition according to one of the preceding claims,   characterized in that the temperature corresponding to a viscosity n, expressed in poise, such that logq = 2 is less than 1,550 C, and of preferably less than 1500 C.