CS214020B1 - Laminated glass made body and method of its manufacture - Google Patents

Abstract

1509644 Glass laminated sheet JENAER GLASWERK SCHOTT & GEN VEB 23 April 1976 [12 May 1975] 16564/76 Heading C1M A laminate of glass and/or glass ceramics comprises a thick core with a high thermal coefficient of expansion completely enveloped by and adhered to a thinner layer with a lower expansion coefficient there being a transition zone between the layers having a variation of the expansion coefficient per unit length perpendicular to the surface of the laminate of not more than 5 Î 10<SP>-7</SP>‹C<SP>-1</SP>/Ám. The laminate may be made by fusing the laminae together and holding at the lamination temperature with optional post treatment at below the softening point of the layer which softens at the higher temperature.

Description

The invention also relates to a laminated body of glass which consists of a thicker core part and a fused, adjacent thinner layer having a lower thermal expansion and completely enclosing the core part.

The invention also relates to a process for the manufacture of said body.

It is known that the mechanical strength of glass bodies can be increased by sheathing glass with lower thermal expansion.

Already in 1891, Otto Schott, in the then German Reich Patent No. 61,573, protected the method of manufacturing multilayer glass articles 8 by a tension-stretched inner layer and a pressure-stretched casing layer, and defined the relationships between the expansion coefficients and the thickness of the glass layers. to obtain relatively small thicknesses by lower thermal expansion, which should not exceed one fifth to one tenth of the total thickness, if the thermal expansion of the core layer exceeds by half the thermal expansion of the shell layer;

These findings were then further expanded in the sense that in such laminated glasses the core layer exhibits a softening temperature slightly lower than the softening temperature of the skin layers. · Since 1968, Corning Glass Works has been serving in the United States. to the increasing extent of patent applications for multilayer bodies, as shown, for example, in DE-OS Nos. 1,926,824 and 2,142,600; DE-OS Nos. 1,926,824. the expansion of the layers, the relative thicknesses of the layers, and their viscosity ratios at their forming temperature, and suitable base glasses are mentioned, for example, when using glasses of at least 15 · 10 ¹ К. Thermal expansions of 60 to 110 · 10 * are given for the core part? к “ ¹ _and pr ₀ sheath part between 30 to 80 · 10 *? K * \ The total thickness ratio between the pressure and tensile stressed layers should be between 1:10 and 1: 30 · Finally, a viscosity ratio of 1: 1 to 6: 1 should be maintained at the forming temperature between the core and the shell layer ·

DE-OS 6 · 2 142 600, on the other hand, has a viscosity ratio of 1: 1 to 1: 6 at the layer-forming temperature in order to prevent surface deformation.

However, all laminated bodies produced in this way have two significant drawbacks. Firstly, these multilayer glass bodies exhibit unforeseen fracture phenomena and, secondly, they exude excessively thick surface layers from the core glass. However, according to DE-OS No. 2 032 255, the latter deficiency can be remedied if. stresses occurring in multilayer glass bodies and derived from the difference in thermal expansion of the individual layers overlap the stress profile with a lower degree of efficiency and greater depth, generated additionally by thermal curing. claims and yet has the disadvantage that such stresses can only cope with surface layers to a certain extent, while surface layers with a larger core glass thickness are peeling ·

The purpose of the invention is to prevent unforeseen fracture phenomena on multilayer glass articles without creating a profile of high pressure stress 8 with a lower depth and lower pressure stress.

214 020 with greater depth i) and allow further increase in the thickness of the pressure-stretched skin layers.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multilayer glass body as well as a method for its production in which the bonding between layers of different thermal expansion is designed to prevent unforeseen fractures and to increase the thickness of the surface layers.

The object of the present invention is to provide a laminated body of glass according to the invention which has a layer of lower thermal expansion between the edge layer of lower thermal expansion and the core portion 8 in which the temperature of the individual components of the glass is reduced. extensibility below 5 · 10 ¹ К ·,

The object is also solved by a process for the production of a body according to the invention, which consists in maintaining the laminated body of glass, after joining its layers together, for a short time at their forming temperature.

The laminated glass bodies according to the invention exhibit greater mechanical strength and better fracture properties compared to comparable glass bodies produced so far.

The invention will now be explained in more detail with reference to several examples thereof.

The refraction of the laminated body of glass is caused essentially either by the cracking of the pressure-stretched surface layer and the associated uncovering of the fractured endangered, tensile stressed core layer, or by fracture phenomena due to the additional propagation of cracks already occurring or arising in the glass surface. Thus, both the pressure-stressed surface layer and the fracture phenomenon sputtering are demonstrably due to a high stress gradient when moving from the lower thermal expansion layer to the higher thermal expansion layer, or vice versa.

In the case of spalling of the surface layer, a high stress gradient leads to a shear stress in the transition zone between the two layers, which exceeds the shear strength of the laminate body material. In the case of fracture phenomena, on the other hand, the high shear stress that occurs in the transition zone between the two layers results in an instantaneous fracture if the widening crack reaches said transition zone.

However, if the shear stress reaches a certain value, which is a critical shear stress, the crack extending up to the transition zone will no longer expand due to the shear stress »With this critical shear stress on the other hand in each Also, at this critical shear stress and at lower shear stresses, fracture phenomena do not occur, nor does the surface layer spill onto the body.

In the case of a layered body whose edge layers are up to 1 mm thick and where the overall ratio of the edge layers to the core layer is below 1: 3> the shear stress in the transition zone of the two interconnected layers increases substantially with increasing temperature expansion difference between the two layers , with increasing difference between the release temperature of the layer with the lowest release temperature and between the operating temperature of the laminate, as well as the increasing thickness of the thinner edge layer.

Thus, for the same, differently small volume components of the transition zone, with the same difference between the release temperature of the lower release temperature layer and the operating temperature of the laminate, as well as the same thickness of the thinner boundary layer. this volumetric

214 020 Component · If the shear stress on the volumetric component of the transition zone is greater than the critical shear stress, fracture phenomena or flaking occurs on the laminate »

By scattering the glass components in the transition zone This is propagated with proper heat treatment from one layer to the next. · As the transition zone extends, the greatest shear stress on these bulk components decreases if the difference between the release temperature of the layer 8 is the smallest release temperature and the operating temperature of the laminate , the thickness of the thinner edge layer, as 1 difference in thermal expansion of the layers remains constant ·

Considering that, due to the characteristic scattering feature, the change in glass components and hence the change in thermal expansion between adjacent transition zones at all its locations is not the same, it is decisive for determining the shear stress achievable to the greatest extent on a differential small volume component Only the bulk component on which the greatest difference in thermal expansion per unit length occurs, as long as the thickness of the thinner edge layer and the difference between the release temperature of the layer 8 by the lowest release temperature and the operating temperature of the laminate remains constant.

Considering that the difference between the release temperature of the layer with the lowest release temperature and the operating temperature of the laminate remains constant during the assembly of certain two glasses, the greatest possible shear stress at the small volume component of the transition zone is determined by the thinner edge thickness and the greatest change in temperature length of Transition Band Units · Thus, for each given thickness of the thinner marginal layer, an accurate value for changing the thermal expansion per micrometer in the transition zone of two co-layers is obtained, resulting in a critical shear stress. the maximum permissible change in thermal expansion per micrometer in the transition zone must be reduced with increasing thickness of the thinner edge layer. · For a laminated body of glass which consists of a thicker core part with a high thermal expansion and adjacent thinner layers of lower thermal expansion therebetween, completely enclosing the core portion, and having a core portion thickness to total thickness of the pressure-stretched adjacent layers of between 3: 1 and 30: 1, and just so, occurs between At the thickness of the outer adjacent layer 30, the core layer and the layer adjacent to at least the difference in thermal expansion 5 · 10 * ^ allow the greatest change in thermal expansion per micrometer in the transition zone 5 · 10 * · K · without exceeding the critical shear stress in the transition zone.

The glass used to produce these laminates for the individual layers must have a range of 10 to 10? The viscosity to be between 1: 5 and 5: 1 in the relationship between the core part and the adjacent thinner layers so as to guarantee the mechanical stability of the laminate in its manufacture ·

Such layered bodies, which at a thickness of the outer adjacent layer of 30 µm exhibit the greatest -1-1 change in thermal expansion per micrometer in the transition zone of more than 5 · 10 * K · yue, show fracture phenomena and a correspondingly large change in thermal expansion per micrometer also flaking of surface layers ·

All laminate bodies on which, on the other hand, the thickness of the outer adjacent layer is greater than 30 µm, shall exhibit the greatest variation in thermal expansion per micrometer in the transition zone214 020 · 10 " ⁷ K" ¹ / µm ¹ , layer, coordinated. with the thickness of the outer adjacent layer, in any case not less than the critical shear in the meei transition zone with different thermal expansions. in the transition zone on the micromeer, it is achieved both by treatment at the formation temperature of the laminated body and by heat treatment ·

Treatment of the laminated body immediately after its formation from the monolayer to its forming temperature is substantially continued for 0.2 to 2 min. For laminated bodies with smaller absolute thicknesses, the shorter processing times and the laminated body are reduced. in the forest with. with greater thicknesses. selects .processing times.

Said thermal treatment, on the other hand, means heating the laminate for heat treatment, the heat treatment of the laminated body. at temperatures below the layers soften! at a higher temperature, and finally a gradual cooling of the layered operating temperature ·

For heat treatment of the laminate body mu! occur at a temperature below the layer temperature. mákinouuí pří. at a higher temperature so as to prevent deformation of the layered body. the processing is determined essentially according to

The heat treatment generally takes the bodies to the temperature mRmu!

to His body temperature. aces softening

Shape temperature and wall thickness of laminated body.

at temperatures from 600 to 900 ° C for processing times from 30 to 300 min.

By processing the laminate at its core temperature, as well as its thermal treatment, the change in thermal expansion per unit length decreases as it moves from the thermal expansion layer to the higher thermal expansion layer, or vice versa, with increasing temperature and thermal time. This reduction in temperature expansion is made possible by the dispersion of the glass components on the basis of their concentration between the individual layers. In principle, all glass components are readily dispersible if there is an appropriate concentration difference of the single-glass components in the two glasses.

This dispersion of all glass components in appreciable sizes occurs in each case when the laminate is processed at the layer forming temperature.

At temperature. however, only the scattering of alkaline and alkaline glass components has been attracted to the heat treatment of the laminated body, and at the given times, the glass constituents are of an expandable size.

Considering, however, that in particular the alkaline and soil-forming components of conventional glasses (e.g., reduce the thermal expansion of these glasses), it is also possible to disperse below the temperature by changing the thermal expansion per micrometer in the transition zone between two together. Accordingly, each individual component has its own scattering coefficient at the respective processing temperature for each layer. Thus, for each individual component, it is possible to derive the following:

a.) If the scattering coefficient for a single component at a certain temperature in a thinner edge layer is larger than in a thicker core layer, it increases or decreases due to the greater thickness of the edge layer over the overall thickness of the edge layer. , far-reaching leveling of concentration in the thinner edge layer.

b) If the scattering coefficient for any component at the processing temperature in the thinner edge layer is less than in the thicker core layer, this leveling of the core layer concentration cannot be expected due to its greater thickness at the indicated processing times.

If the scattering for the single component in the boundary layer is greater than in the core layer, the difference in thermal expansion between the layers of the layered body cannot increase or decrease with sufficient scattering. Considering that due to the higher thermal expansion of the core layer required for the laminated bodies, the core layer generally contains a higher proportion of alkali oxides, thereby increasing their proportion in the entire boundary layer due to the higher scattering coefficients for the alkali components in the boundary layer. by extensively balancing the concentration in the boundary layers, thereby reducing the thermal expansion difference between the boundary layer and the boundary layer. Core layer.

Accordingly, at least the coefficient of dispersion for the alkaline components of the thicker core layer at all processing temperatures may be equal to or greater than the respective scattering factors for the alkaline components of the thinner edge layer.

The following examples are given below:

Example 1

In accordance with the method of the present invention, in the droplet dispenser, the separate edge and core glass melt streams in the following composition were combined by means of a fire-resistant circular nozzle into a glass skein of several layers:

core glass edge glass silicon dioxide sio ₂ 71.8% 74.6% boric oxide ^B 3 ° 3 3.8% 13.6% alumina. A1 ₂ O ₃ 4.8% 3.2% magnesium oxide MgO 2.3% -% calcium oxide CaO 4.6% 0.8% natron At ₂ 0 9.2% 6,1% potassium oxide . KgO 2.8% 1.2% thermal expansion 75. 10 ' ⁷ ' K ¹ 47. 10 ⁷ K ¹

Returned with acid ENEN skein simply engage ЫШ ^- guaranteeing extended ^PTY lm povinovaného odsWpnováinC concentration gradient in the layer of tension for 35 seconds in the nozzle and dispenser výpuutí temperature forming laminated tělesa'1.320 ° C.

For pouuití technological process and blow molding they are then produced from the glass gob borrowed multilayer cups ratio zi mm edge and core glass from 1: 4 to U6, and a middle 'thickness ST ^E N ^1.8 mm. Tests with the boundary of the Via micro-probes reveal the greatest change in thermal expansion in the stress transient layer 4.1. 10 ”* K“ ^x . ^ umi-.

The achieved graduation of the concentration guaranteed 2.7 times increased mechanical strength (tested according to the steel ball drop method) compared to comparable products from the above-mentioned edge glass, with fracture properties comparable to non-tensile glass, with a number of fragments of between 10 and 15.

214 020

Reducing the dwell time of the layered skein at a layer forming temperature below 0.2 min · resulted in a change in the thermal expansion in the transition zone of greater than 6 »10 'K' for products made by the compression and blowing technique. yum.

Such products showed, without exception, a sharp fracture with a large number of fragments (more than 50).

Example 2

For the production of the three-layer body, separate batches for core and edge glass in the following weight composition were melted and formed into glass panes:

Core glass peripheral silicon dioxide S10 ₂ 59.0% 77.0 alumina Al ₂ ° ₃ 18.0% 4,5 boric oxide ^B 3 ° 3 2.0% 11.5 natron At ₂ 0 12.5% 3.5 potassium oxide KgO 4.0% 3.5 calcium oxide CaO 2.0% - magnesium oxide HgO 2.5% -

* 7 1

The thermal expansion of the core glass was 90.8 · 10 "* K" ^x , the edge expansion coefficient of —7 —1 glass 43> 0 · 10 * К · After the sheets were assembled together, a three-layer cup with a bottom diameter of 60 mm and a total height of 30 mm.

The core glass layer had a thickness of 1.2 mm. The overall thickness of the body edge layers was 0> 06 mm. This results in a total thickness to core ratio of 15: 1 ·

After shaping, the object exhibited a transition voltage strand in which the test could determine the greatest change in thermal expansion 7.1

10 ' ⁷ K ¹ . yum ¹ .

Example 3

The multilayer cups produced according to Example 1, with the greatest variation in temperature expansion in the —7 -1 -1 layer and a voltage transfer of 4.1 · 10 * K · yum, were additionally heat treated for 200 min after the measurements were made. at 700 ° C ·

Scattering events in the stress transition layer caused a further reduction in the change in thermal expansion to 3.4. 10 “^. ^ звГ \

Mechanical strength tests, ie the detection of impact by the steel ball drop method, the treated cups also yielded an increase in strength to 2.4-fold with additional refractive properties of glass articles after additional heat treatment compared to comparable edge glass products · Fragments per cup decreased to 6 to 9.

In the case of a thermally treated laminated body which has been thermally treated after shaping for a further 150 min. at a temperature of 740 ° C, the scattering processes between the core and the casing glass reduced the greatest change in thermal expansion in the transition zone to 3.8 · 10 · ·

While the heat-treated laminated bodies exhibited a number of fracture phenomena and, in some articles, the surface layers popped, such phenomena did not occur after the described heat treatment.

Claims (10)

1 »A laminated body of glass consisting of a thicker core layer and an adjacent thinner layer having a lower thermal expansion and surrounding the core part completely, indicated by a shade having an edge layer and lower thermal expansion and a core part and a higher temperature expansion layer , in which ae there is a scale of concentration of the individual components of the glass reducing the thermal expansion below 5 · 10 “? 2. A laminated glass théeo according to Run 1, characterized in that as the transition from the layer and the higher thermal expansion to the lower thermal expansion layer, the sky is inverted. It gives the greatest thermal expansion per unit length, reduced and increasing thickness of the adjacent thinner edge layer. 3. A laminated body according to claim 1, characterized in that, at the reaction temperature, the difference in the coefficients of thermal expansion is at least 5 · 10 &quot; yun "\ 4 »The laminated body of ecla according to claim 1, characterized in that the immersion is not thrust-stretched The core parts and the pressure-stretched edge layers are greater than 3: 1 · 5. A layered ecla body according to claim 1, characterized in that the draft thickness of the tensioned core portion to the thickness of the pressure-tensioned edge layer is not less than 30: 1. 6. A method for producing a laminated body from ecl according to claim 1, characterized in that ae the laminated bodies, after joining their layers together, maintain at a short time their formation temperature. 7. The method according to claim 6, characterized in that the laminated body is heat treated at a temperature below the invariant temperature of the layer at a higher temperature. β. 6. The method according to claim 6, characterized in that the laminated body is kept briefly at its formation temperature for a short time after joining its layers together, and also heat-treated at a temperature below the inverting temperature of the layer at a higher temperature. The method according to claim 6, characterized in that the ее layered body keeps the formation temperature of the individual layers immediately thereafter still for 0.2 to 2 nin. Process according to claim 7, characterized in that the heat treatments are carried out at temperatures of from 600 to 900 ° C and for a treatment period of from 30 to 300 nln.