DD145524A5 - METHOD AND DEVICE FOR HEAT TREATMENT OF GLASS - Google Patents

Description

<&. Berlin, 1. 2. 1980

3 1 5 © % ί "M- AP C 03 Β / 215 022 • 55" 994/24/32

Lead Verfa and _{Vorrichtunf? Ii} for heat treating .__ Gla_s

Area of application of the invention

The invention relates to the heat treatment of glass, in particular the heat-hardening of flat glass or curved glass panes, for example of glass individually as a windshield for motor vehicles or as part of a laminated safety glass windshield for motor vehicles, as rear windows or side windows for motor vehicles or for the construction of windshield assemblies for plug and train locomotives.

Cha r t _ale: erijg ti k_ ά ^ he be ka η η t eh _u tee is before the η Lo sun gen

In DS-PS 125 942 a method for the heat treatment of glass articles is described. Each glass article is heated to a temperature above its lower cooling point er-ν / ϋΐΓΏΐ, followed by a rapid cooling of the glass articles in sequence in a homogenous gas fluidized bed of powdered material! Material. This homogeneous powder-based gas fluidized bed is in a motionless, uniformly expanded state of homogeneous fluidization by controlling the distribution of the fluidizing gas * in the homogeneous fluidized bed, adjusting to a gas flow velocity through the homogeneous fluidized bed between that velocity corresponding to the initial fluidization and that corresponding to the maximum velocity Expansion of the homogeneous fluidized bed *

This condition of fluidization of the fluidized bed is such as to cause the movement of the powder-based homogeneous fluidized bed on the hot submerged surfaces of the glass when the glass in the fluidized bed is cooled zvv but has any overtravel tension,

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which are induced in the surface of the hot glass when the entrance kanta first grazes the fluidized bed are not of such a serious nature that they could endanger the glass. Therefore, the Verfakren on a high efficiency.

The degree of cure of a glass sheet immersed in such a fluidized bed depends on the rate of heat transfer between the homogeneous fluidized bed and the hot one. Glass disc, which is immersed in the fluidized bed, and the rapid transport of 'Teilkienien away ata near the glass pane with the same rapid tracking of colder particles from the mass of the fluidized bed in the Uäh the glass pane.

The movement of the particles in the vicinity of the glass surfaces is faster than the movement of the particles in the main mass of the fluidized bed _β This is due to the rapid movement of the homogeneous fluidized bed, which is due to the hot immersed surface of the glass due to the heating of the homogeneous fluidized bed is caused by the glass, and this phenomenon continues as the glass cools in the fluidized bed.

The movement of the homogenous fluidized bed at the glass surfaces is more likely to be enhanced if a selected homogeneous particulate material is used which has latent gas evolution characteristics such that rapid evolution of gas from the homogeneous fluidized bed occurs when heating the surface of the glass surfaces is

It has now been found that there are three factors that prevail in controlling the heat curing of glass in a homogeneous gas fluidized bed and that in the

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Specifically, control the degree of hardening of a hot glass sheet when it comes in contact with a homogeneous gas fluidized bed.

These factors are the following:

"The gas evolution characteristics of homogeneous and off

single particle existing fluidized bed. *.

2. The heat capacity per unit volume of the homogeneous fluidized bed in the state of minimum fluidization. The derivation is made from the specific heat of the material of the homogeneous fluidized bed, measured at 50 C, and from the density of the relevant powdered material of the homogeneous fluidised bed, measured at the minimum fluidization of the material. «

3. The "flow characteristic" of the homogeneous fluidized bed as defined below, which corresponds to the sum of four specific statements attributed to the fluidized bed by the assessment of four characteristics of the flowable powdered material. The expression "flowability" is the same Meaning when used here.

These four characteristics of a flowable homogeneous fluidized bed and the nature and manner of assigning specific statements are set forth in the article "Evaluation of the Flow Properties of Solids" by Ralph L. Carr, Jr., Chemical Engineering, Vol. 72, ITr ₀ 2, January 18, 1965, and can be stated as follows:

100 (P - A)

where: P = gross density of packed conditions A = bulk density under aerated conditions

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ft f fcfä ^ ^ 2, S & hüt ^ viukel ^ This is the angle in degrees between the horizontal and the inclination of a Haufeas of the powdery material, the free falling from a point above the horizontal, until a constant angle is measured.

3 · ^ Pälg ^ HJjJJ ^ GJR-L ^ ^η spatula is horizontal, the lowest hawks a mass of the dry powdered material inserted and vertically upward and out of the material fine A! Average value of the angle in degrees between the side of the material heap and Horizontal on the spatula corresponds to the spade angle.

This distribution is described in the above-mentioned article as the numerical value obtained by: ## EQU1 ## the width of the screen opening (ie particle size) through which 60 % of the homogeneous and particulate material passes is divided by the width of the screen aperture through which just 10 % of the homogeneous and particulate material passes.

All values for the particle size distribution referred to herein were measured in a known manner by a method using a Coulter payer to give the particle diameters corresponding to the cumulative mass percentages obtained of 40 % and 90 % according to the present invention. To determine widths of Sieböffnimgen pass through the 60 % and just 10 % of the homogeneous material.

Me numerical values for compressibility, the Schiitt ™ angle and the spatula angle were calculated using a

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Hosakawa powder tester measured. This powder tester is specifically designed to determine the "flowability" of powders, as defined above.

The flow characteristic of a particulate powder is fundamentally related to factors such as the average particle size, particle size distribution and shape of the particles, sometimes referred to as the sharp edge of the particles, ie whether they are rounded or solid The value of the flow characteristic increases with the increase in the average particle size, with a narrowing of the particle size distribution and with a decrease in sharp-edgedness.

The heat capacity per unit volume with minimal fluidization is dependent on the specific heat of the material and the density of the fluidized bed with minimal fluidization, the density increasing with a narrowing of the particle size distribution,

A high level of 'cure stress' is produced in the glass when it is rapidly cooled in a fluidized bed having optimum flow properties. Some materials that provide the required cure voltages can be obtained commercially. Other commercially available materials may be modified to provide the required cure voltages by sieving the material to achieve a change in its average particle size and particle size distribution.

However, there is a problem because there is a limit to what the degree of annealing stress induced in glass is due to the change in the flow property of the

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Commercially available materials can be controlled. Materials having the required flow property can not be obtained commercially. Obtaining a large amount of a material having the required flow property may involve sifting through a large amount of powdery material. In addition, when a single material is used, the only way of modifying the heat capacity of the fluidized bed is in the narrowing of the particle size distribution, so that there is no possibility of modifying the heat capacity irrespective of the change in the flow characteristic caused by the narrowing of the particle size distribution "

It has now been found that a powdery material having optimum gas-evolving properties, optimum heat capacity and flowability for generating the required hardening stresses in a glass article can be obtained through the use of a mixture of the powdery materials, with each individual powdered material being the optimum one Properties of the mixture contributes. By selecting the powdered materials and the respective proportions according to which the mixtures are made, the homogenous gas fluidized bed can be made "to size" to provide, within a wide range, any required hardening stresses *

Object of the invention

The aim of the invention is to carry out the heat treatment of glass in such a way that the associated operating costs are reduced and the use of little cost expenditure and easily available materials is possible.

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the invention

The invention has for its object to provide a method and apparatus for heat treatment of glass, in which the glass is heated to a predetermined temperature and brought into contact with a homogeneous gas fluidized bed, so that in the glass by a suitable mixture and by selection he achieved the higher hardening stresses selected in the proportions of the mixture in the state of fluidization.

According to the invention, this object is achieved by using a homogeneous powdery material consisting of a mixture of a series of selected homogeneous powders, wherein at least one of the powdery materials, when heated by the hot glass, has gas-generating properties, and the respective powdery materials are mixed with each other in selected predetermined proportions, whereby a heat capacity and flow characteristic is imparted to the mixture of the gas fluidized bed of the powdery materials, so that a required heat treatment of the glass is achieved.

Advantageously, the materials are mixed together in selected predetermined proportions such that the necessary hardening stresses are produced in the glass when the glass in the homogeneous gas fluid layer cools from a temperature above its lower cooling point.

The present invention further relates to the selection of a pulverulent material for gas evolution, which is able to develop in the range of 4 % to 37 % of its own weight of gas, when a heating to a constant mass at 800 ⁰ C has occurred, as well Mixing the

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oil · »><^ y Si0 esa fei _ o

powdery materials in predetermined proportions, whereby the. Mixture is given a heat capacity per unit volume with a minimum solids in the range of 1.02 to 1 »75 MJ / ra K and a flow property in the range of 60 to 86 *

According to a further feature of the invention, in which a sheet of liatron-KaXk silica glass is thermally cured in a thickness of 2 UHn to 2.3 mm, the glass sheet is heated to a temperature of 610 ⁰ C to 680 ⁰ C, u & d the Mixture is maintained in a motionless, uniformly expanded state of homogeneous fluidization; such that the homogeneous powdery material has the property of inducing an average tensile stress in the glass sheet in the range of 35 to 57 MPa.

In the manufacture of a windshield, the character may be characterized by mixing the homogeneous powdered materials in predetermined proportions to give the mixture a flow property in the range of 71 to 83 and a heat capacity per Yolumen unit at the minimum fluidization in the range of 1 _S Q9 MJ / πΑί is awarded to 1.38 HJ / iÄ.

Preferably, the gas evolution material / alumina is oxide. Advantageously, the α-alumina is present in a mixture with the α-alumina. In a further embodiment, the mixture to 7 weight _e is -% to 86 weight '% of ~' / "- alumina _β

Another possibility for realizing the present invention is characterized in that a hot glass cube is rapidly cooled in a gas fluidized bed mixture consisting of an alkaline gas powder and at least one powdered metal oxide, the heat capacity of the ceramics

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powdered metal oxide per unit volume at a distillization of 1.76 MJ / m ³ K corresponds to 2.01 HJ / iA, and the powdered! Materials are mixed in predetermined proportions, thereby imparting to the mixture a heat capacity per unit volume at a minimum fluidization in the range of 1.2.7 MJ / m ³ K to 1.76 MJ / iA and a flow property in the range of 71 to 82 \\ rd.

The powdered metal oxide may preferably be sphaloid iron oxide (--Fe ₂ O.). The mixture is advantageously to 30 wt .- $ bis.70 wt .-%. composed of the spheroidal iron oxide. Furthermore, the mixture in a further embodiment of the invention to 70 Gev; .-% to 30 wt. SS of ^ -Aluminiumoxid as Gaseentwicklurgßmaterial. Another possibility in the context of this aspect of the present process is that the mixture contains from 23 % to 35% by weight of the spheroidal iron oxide and from 45% to 56% by volume of c <L alumina, with the remainder corresponding to the / - alumina as the gas evolution material.

The powdery metal oxide is preferably the zirconium (ZrOp, SiO ₂ ). The mixture settles

suitably to 10 wt .-% to 70 wt .-% of aluminum monohydrate (AIpO ^ ₀ IHoO) as the Gasentv icklungsmaterlal and to 90 wt .-% to 30 Be. ~% of zirconium together «

In another embodiment of the invention, the powdery gas evolution material corresponds to an aluminosilicate. Advantageously, the aluminosilicate% is equal to the zeolite, thereby v ^ ground Gevi 8 ~ to 10 wt -.% Zeolite with 90 wt,% to 92 ~ & ev} mixed .-% ^ alumina to form the mixture.

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According to a further variant of the invention, the pulverulent gas developing material is aluminum monohydrate

Further, according to the present invention, the mixture may be made of silicon carbide (SiC) mixed with a porous gas evolution material. In one embodiment, the gas evolution powder corresponds to the aluminum monohydrate (Al ₂ Q ₀ → IH ₂ O), and the mixture consists of 17% by weight of the aluminum monohydrate in a mixture with 83% by weight of silicon carbide.

Another possibility of implementing the present method provides for the use of aluminum trihydrate O - .. 3H ₂ O) as a gas evolution powder.

The mixture can according to the invention of two. Gaseentwicklungspiilvern exist ^ from the aluminum trihydrate (Al ₂ O .3HgO) and from <x> aluminum oxide in equal proportions.

Another aADere possibility of implementing the present method is to use as a powdered gas developing material sodium bicarbonate (NaHCOo). The mixture preferably consists of 10% by weight, of sodium bicarbonate and 90% by weight of c * _ aluminum oxide.

The present invention also includes the apparatus for heat treating glass, comprising a container for the homogeneous gas fluidized bed, gas connections to the gas supply container for maintaining the state of fluidization of the powdery material and means for positioning the hot glass in your container. It is characterized in that in the container a homogeneous G-ascot layer of a mixture of

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selected powdery! Materials, at least one of which powder has gas-generating properties when heated by the hot glass, the powdered materials in selected predetermined proportions are mixed together, whereby the mixture of the gas fluidized bed, a heat capacity and a flow behavior are imparted that required Heat treatment of the glass is achieved.

Execution sbe ispiel

The invention will be explained in more detail below with reference to execution examples. In the accompanying drawing show:

Pig, 1: schematically a vertical plane through the ullage. for heat curing of. Glass;

Pig. FIG. 2: a graph of the mean tensile stress as a function of the proportions of the mixture of pulverulent materials which characterize the gas fluidized bed. FIG. Dor Curve display-shows the course of the change in the voltage as a puncture of the change in the respective proportions au;

Fig. 3: a graphical graph similar to the Pig. Figure 2 illustrates the variation in mean tensile stress variation as a function of changes in proportions in another powdered mixture;

Pig. 4s is a graphical graph similar to Pig. 3> wherein the course of the change of the surface compressive stress in 2.3 mm glass is reproduced as a puncture of the change in the composition of the gas vortex layer;

Fig. 5t is a graph of graphs similar to Fig. 3> showing the mean pull-up stress induced in a glass of Giner thickness of 6 mm;

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Fig. 6 is a graph similar to Fig. 4, illustrating the variation of the surface compressive stress in a 6 mm glass;

Fig. 7 is a graphical graph similar to Fig. 3 for a 12 mm glass;

Fig. 8 is a graphical graph similar to Fig. 4 for a 12 mm glass;

Figures 9, 10 and 11 are graphs showing the course of change in the mean tensile stress as a function of the composition of the mixture of powdery materials, taking into account three other possibilities for realizing the method according to the invention.

Referring to Fig. 1 of the drawings, it is a perpendicular hardening furnace 1 _{S of} the side walls 2 and a cover 3 has. The side walls 2 and the cover 3 are made of ordinary refractory material, and the lower part of the furnace 1 has an opening 4 ₅ which manifests itself by an elongated shape in a base plate 5 on which the furnace 1 is located. A slidable closure is provided (not shown) to close the opening 4 in a known manner. A glass plate 6, which is to bend and then thermally harden, is suspended in the furnace 1 by pliers 7, which engage the upper edge of the glass plate 6. The pliers 7 hang on a pliers rod 8, which depends on a known hoist (not shown). The pliers rod 8 moves on vertical guides 9 which extend in a downward direction through the furnace 1 to guide the lowering and the lifting of the pliers rod 8.

A pair of bending tools 10 ^ 11 are located immediately below the opening 4 of the furnace 1 in a heated chamber 12 which is maintained at a temperature such that the bending

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tools 10; _11: the same as temperature have to be bent hot glass. The chamber 12 is heated by hot gases supplied through openings 12a. When the bending tools 10; 11 are open, they are on each side of the path of the glass plate 6. The bending tool 10. represents a solid male, which is attached to a pressure piston and has a curved end face, which defines the curvature on the hot glass plate 6 to is transferred. The bending tool 11 corresponds to an annular die, which is held by struts 14, attached to a support plate 15, which is located on a pressure piston 16. The curvature of Werkzeugrahxnens 11 corresponds to the curvature of the end face of the male 10th

The slide rails 9 extend downwardly on each side of the bending tools 10; 11 into a container with a fluidized bed 17 of powdery refractory materials in which the hot crumb rate glass plate 6 must be rapidly cooled, the glass sheet 6 being lowered downwardly into the fluidized bed 17 in the direction of flow.

The container with the fluidized bed 17 consists of an open-topped rectangular tank 18 located on a ¹ : platform that can be raised and lowered by a disc-shaped device. When the platform 19 is in its upper position, the upper edge of the tank 18 is just below the bending tools 10; 11th

A high pressure drop microporous membrane 20 extends across the bottom surface of the tank 18.

The edges of the membrane 20 are fixedly attached between a flange 21 on the container and a chute 22 on an air chamber 23 forming the bottom of the container. The splashing 21; 22 and the edges of the membrane 20 are interconnected

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a screw 24 connected. A gas inlet feed line is connected to the air comb he 23, and fluidized air is the Gasiolaßzuleitung 25 fed under a regulated high pressure. At the membrane 20 there is a high pressure drop of at least 60 % of the plenum pressure, whereby a uniform distribution of the fluidizing air in the powdery material at a gas flow rate through the pulp-shaped material between that speed corresponding to the minimum fluidization of the particles, just in the In the direction of upwardly flowing air are suspended, Ufid that speed is conditioned according to the maximum expansion of the powdery particles, wherein there is a dense fluidization. The expanded fluidized bed 17 is in a substantially bubble-free motionless state of homogeneous fluidization with a horizontal resting surface through which the glass sheet 6 enters the fluidized bed 17.

The membrane 20 may be made of a steel plate providing a uniform distribution of holes and a series of layers of strong microporous paper on the plate. For example, 15 sheets of paper can be used. The membrane 20 is completed on the uppermost layer of the paper layers with a wire mesh; For example, a wire mesh made of stainless steel can be used »

A basket for receiving broken glass may be provided near the diaphragm 20 and must be arranged constructively so as not to interfere with the uniform flow of fluidizing gas upwardly from the diaphragm 20.

The guide rails 9 extend in the direction down to au 'a position below the bending tools 10; 11 and end iia area of the top of the container »A solid

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Frame 27 is located in the tank 18 and has at its lower end an upwardly bent foot 28 in which the lower edge of a glass sheet 6 is received, which dips into the fluidized bed 17 when the pliers rod 8 via the bending tools 10; 11 is lowered by the lifting system.

To introduce eiiie glass plate 6 in the system, the scissor-shaped platform 19 is lowered and mounted at the bottom of the pliers rod 8 at the lower part of the guide rails to be curved and to be cured glass plate 6 on the pliers.

The lifting equipment then pulls the hinged glass plate 6 up into the oven 1, which is maintained at a certain temperature, for example 850 C, so that the glass plate 6 is rapidly heated to a temperature near its lower cooling point, for example in the range of 610 C to 680 ⁰ C ", When the glass plate 6 has reached the required temperature uniformly, the shutter which closes the opening 4 is opened, and the hot glass plate 6 is by the lifting system in the position between the open bending tools 10; 11 lowered «The pressure piston 13; 16 are put into action and the bending tools 10j 11 compressed UBi the glass plate 6 to give the desired curvature. When the required curvature is made on the glass sheet 6, for example, to enable the glass sheet 6 to be used as part of a laminated glass safety glass for a motor vehicle, the bending work eyes 10; 11 open, and the hot curved. Glass pane 6 is rapidly herabgese.nkt into the fluidized bed 17 in the tank 18, which has been brought into the position for rapid cooling of the glass sheet 6, VMR by raising the scissors-like working table 19 & e _s while the glass plate was heated in the furnace 1 6 "The Fluidized bed 1? is by a water cooling jacket at a temperature between 30 ⁰ C and 150 ⁰ C.

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held firmly attached to the flat longer side walls of the tank 18 *

The fluidized bed 17 corresponds to a homogeneous Gaswirbelßehieht of powdery materials. It is a mixture of a series of powdered materials in predetermined proportions, at least one of which has gas evolution properties and is capable of evolving gas when contacting the fluidized bed 17 with the hot gas 6.

A suitable powdered gas evolution material is capable of developing gas in the range of 4 % to 37 % of its own weight when heated to a mass consistency at 800 ° C. "Suitable materials are: Aluminum oxide (/ "- AIpOo), which is porous and contains water adsorbed in its pores, aluminosilicates containing porous bind and water adsorbed in their pores, alumina hydrates such as the aluminum trihydrate (AloO-,. 3HpO) containing chemically bound cryogenic water and aluminum monohydrate (AlgO 3) which contains water of crystallization and is porous even if water is adsorbed in the pores; and materials which evolve gases other than water, for example, "tetrathihydrogen carbonate (KaHCO -,).

In order to produce the required hardening stresses in the glass 6, the individual components of the powdered mixture must be mixed in predetermined proportions with each other so as to give the mixture a minimum fluidization heat capacity in the range of 1.02 to 1.76 MJ / mK To provide flow behavior in the range from GO to 86 «

Other components of the mixture, which are found in the mixture together with the gac development powder, are those powdery materials which are inert in the sense of

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Essentially no gas is generated when heated from these materials. Examples include: ^, - alumina ( ⁰ C-AIpO-,); Zirconium (ZrO ₂ → SiO ₂ ); silicon carbide; and spheroidal iron oxide (ο (_ ~ Έβ _ο 0 ~) _Λ

C-.

These powdery materials are in a dense and non-porous form, and are selected to have a flowability and heat capacity different from that of the gas-developing powder, so that depending on the proportion of the dense non-porous material used, these materials will act to modify the flowability and heat capacity of the powder mixture to such an extent as to cause a desired degree of hardening stress in the glass 6.

It is believed that, when a hot glass sheet 6 in a Gaowirbelscliicht such a mixture of powdered materials is rapidly cooled, rapid development and expansion of the gas from the Gasentwicklungspulvsx ¹ by heating the powder in the cows of the glass surfaces, the local movement of the powder mixture is reinforced on the glass surfaces in a manner similar to the boiling of a liquid. As a result, there are observed moving layers of gas and. Glide powder over the glass surfaces when the glass sheet 6 is rapidly cooled in the fluidized bed 17.

By mixing the individual constituents of the mixture in predetermined proportions, there is an optimum transfer of heat away from the glass surfaces in the direction of the main mass of the fluidized bed -17. This produces the required stresses in the glass 6. In addition, a continuous dissipation of heat to the more remote parts of the fluidized bed 17 can be observed, this heat being dissipated from the glass 6 by the movement of the homogeneous fluidized bed 17 in the immediate vicinity Glass pane 6 is removed »

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fe "

-1 Q

™ IO ™

The water jacket 29 cools the more remote parts of the fluidized bed 17 »so that they act in the sense of a heat sink. The vigorous movement of the powdered material on the glass surfaces continues until the glass 6 cools below its lower point. This assures that the mid-surface temperature gradients initially induced in the glass β when it is in the fluidized bed 17 are maintained as the glass 6 cools above its lower cooling point. The required hardening stresses are subsequently developed during the continuous cooling of the glass 6, while it is still in the immersed state in the fluidized bed 17.

The lower edge of the hot glass sheet β is uniformly rapidly cooled as it enters the horizontal resting surface of the expanded sirbe layer 17. In essence, the same tensile stresses are caused in different areas of the surface of the edge of the glass sheet 6, so that there is a very small occurrence of fractures. During the lowering of the lower edge of the glass sheet 6 in the fluidized bed 17, each part of the lower edge is always in contact with the homogeneous fluidized bed 17, which has a motionless uniformly expanded state of homogeneous fluidization. This uniform treatment of the lower edge of the glass sheet 6 largely prevents breakage of the glass 6 and the resulting problems, regardless of the flowing movement of the powdery material which can be caused on the hot glass surfaces by gas evolution from the gas evolution of the mixture an elimination of broken glass in the fluidized bed.

This, together with the prevention of glass pane loss due to a change in the shape of the glass.

"W

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slices and / or a reduction in the surface quality of a commercially viable yield of tempered glass.

Some examples of the practice of the present invention with selected blends of powdered materials are given below. In each of these examples, the numerical value of the product from the sub-

3

density in g / cm and the average particle size in / around each constituent of the mixture less than 220 "This is a criterion which has been useful in the evaluation of whether a particular individual powder for fluidization is at rest uniformly expanded state of homogeneous fluidization is suitable when operating with air at ambient conditions of normal temperature and pressure. A mixture of the bleached powdered materials is then capable of being placed in a quiescent uniformly expanded state of a homogeneous fluidized bed 17.

BeisDie_l_J_

The fluidized bed 17 was composed of a mixture of alumina as the powdery gas evolution material and of cis -alumina.

Dao alumina used was a microporous material having pores with diameters in the range of 2.7 to 4? 9 and with a free pore space of 20 % to 40 %. The pores contain adsorbed water which is released as gas when the material is heated.

The '^' alumina used had the following characteristics:

20

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Mean particle size 119 / do

size distribution 2.34

fluidity ...... 90,25

Water content (mass loss at 800 ^° C.). 4.3 %

Heat capacity per unit volume

at minimum fluidization 1.09 MJ / iA

The latex alumina was present in a dense and non-porous form with the following properties.

Average particle size 30 / um

Particle size distribution 1.22

Flow property 70

Heat capacity per VoXtimeneinheit

at minimum fluidization 1.3 MJ / iA

The experiments were carried out with mixtures of / '- alumina and ⁰ ^ - - alumina, wherein the respective mixtures were prepared in predetermined proportions »glass plates 6 of Katron-lime-silica glass with a thickness of 2.3 mm were cut and the edges of the The cut glass plates 6 were processed by being rounded off using a fine diamond grit grinding wheel. Each glass plate 6 was heated in the oven 1 to 660 C before it was bent and rapidly cooled in the swirl mixture 17. The fluidized bed was in a stationary uniformly expanded state of homogeneous fluidization,

Table 1 contains the properties of the various mixtures of these materials in the range of 30% to 90% by weight for cc -alumina and. from 70% by weight to 10 % by weight

for T ^ '^ uminiuraoxid and also gives the middle Zug-. voltage, which was caused in deia glass panes 6 during rapid cooling. For comparison purposes, the mean is

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WZ cZ

- 21 '

Tensile stress caused when the <? T alumina and the? -? - Aluininiuinoxxd used alone are also indicated.

Table. 1 ; Results

Wt .-% in the mixture

⁰ ^ -alumina ΐΓ- alumina

Flow characteristic of the mixture

Heat capacity per volume at minimum fluidization (MJ / m ^ K)

Ivlittlere tension

100% 90.25

1.09 41

30 % 50 % 30 % 70 % 50 % 74 81.5 75 1.24 1.16 1.20 49 43 49

90 % 10%

72,25

1.28 47

100 % O %

70

1 * 3

32

 Pig. Figure 2 illustrates the course of the change in the mean tensile stress as a function of the composition of the mixture.

The TiAluminum oxide alone has a flow characteristic which is too high to produce a maximum cure stress in the glass sheets 6, particularly because of its large average particle size and the fact that the particles have a relatively smooth porin with no edges , The addition of a certain amount of oC-alumina, which has a lower flowability to the / alumina, because of the smaller average particle size of the ⁰ ^ - alumina and the sharpness of its one-particle, lowers the flowability of the mixture, the flowability of the mixture decreases as the proportion of cc -aluminum oxide in the mixture is increased, and there is a measurable increase in the average produced

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r- tiV> - 22 ~

Tension. A maximum mean tensile stress of 49 MPa is reached when the fluidity has been adjusted to the optimum value of 74. Then, the mixture contains about 70 Ge * s. ~% <? C alumina and about 30 wt. ~% 'Ί- alumina.

The "sC-alumina has a higher heat capacity than the ^ alumina, and if the proportion of" o (, - is aluminum miniumoxid enlarged in 'the mix, there is a growing increase in heat capacity of the mixture, resulting in an increase contributes to the tension that is achieved «,

Further addition of 47C-alumina in a proportion of over 70% by weight slightly increases the heat capacity and maintains a reasonable flow property, but lowers the average tensile stress obtained because the proportion of the gas decomposition component, the T- alumina , has been reduced to a low level.

The fluidized bed 17 was composed in this example of a mixture of / '' - Aluminiuisoxid as the gas evolution powder and. '^ - alumina together,

The T ^ -alumina used was a microporous material with pore diameters Xm ranging from 2.7 to 4.9 nm and having a free pore space of 20 % to 40%. "The pores contain adsorbed water which is released as gas when the material is heated.

The T-Almsl biotin oxide used had the following characteristics:

S ίΙ Φ P - 23 -

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Average particle size 64 / um

Particle size distribution ............. 1.88

Flow property 84

Water content (mass loss at 800 ^° C.). 4 %

Heat capacity per unit volume

at minimum fluidization 1.06 MJ / iA

The C-alumina used was that used in Example 1.

The experiments were carried out with mixtures of α-alumina and oC-alumina, which in predetermined proportions of 100 % ^ -aluminum oxide and 9% oC-alumina to 0 % f-Alxaai.n. ± xm.oy: ± d. and 100 % o6.aluminum oxide were mixed.

Table 2 contains the heat capacity per unit volume at the minimum fluidization and the flowability of the mixtures used:

Table 2: Results

Geraisch in Gew. ~? 5 heat capacity flow

in MJ / ra ^ K property

Alumina - 'alumina

100 O 1.05 .84

86 14 1.09 82.75

61 39 1.15 79

40 60 1.20 * 76

22 78 1.25. 73 »25

7 93 1,29 '·. 71

0 100 1 _s 30 70

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The glass plates 6 of soda-lime-silica glass having a thickness of 2.3 ram were trimmed and the edges of the cut glass plates 6 were machined by being rounded using a fine diamond grit grinding wheel Pliers 7 hung and heated in the oven 1, before bending and rapid cooling were made. The results are shown in FIGS. 3 and 4. The abscissa of each graph corresponds to the composition of the mixture in% by weight, in each of the pigs. 3 and 4, four curves are shown corresponding to the mean tensile stress (Fig. 3) and the surface compressive stress (Pig. 4) caused in the glass sheets 6 having the thickness of 2.3 mm. These glass sheets 6 are heated to a temperature of 610 ⁰ C, 63Ο ⁰ C, 65Ο ⁰ C or 670 ⁰ C. and then rapidly cooled in the fluidized bed 17. The fluidized bed 1.7 was held in a quiescent uniformly expanded state of homogeneous fluidization and in the temperature range between 60 ⁰ C and 80 ⁰ C.

The ivD.rven show that it was preferable to use the oC-alumina at about 7 wt.% To about 86 wt.% In a mixture with T-alumina. When the ionic proportions of o - alumina in the mixture are increased, take the mean tensile stress; and the surface compressive stress induced in the glass 6 in the thermal deterring process, up to a maximum reached when the amount of C 10 aliminium oxide is about 70% to 80% by weight of the mixture. In general, the highest stresses are produced when the amount of α-alumina present constitutes 55% by weight to 85% by weight of the mixture. A higher amount of α-alumina in the mixture causes a decrease in the voltages reached.

By appropriate selection of the proportions of α-alumina and CL alumina, the mixture had gas

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 ψ

winding properties, a heat capacity per unit volume with a minimum fluidization at 50 ⁰ C and a fluidity, whereby constantly high values of the average tensile stress and the surface compressive stress in the glass sheets β were produced with a thickness of 2.3 mm.

For example, when the glass 6 is heated to 670 C and then rapidly cooled, a required average tensile stress in the range of 42 MPa to 49 MPa and a corresponding surface compressive stress in the range of 83 MPa to 103 MPa in the glass 6 can be produced. This is achieved by the selection of the predetermined proportions of / alumina and oC "alumina in the mixture in the range of 7 wt .-% to 86 wt .-% for ^ alumina and 93 weight -% to 14 weight _e -% for c £ alumina.

Glass plates 6 of IJatron-lime-silica glass having a thickness of 6 mm were processed and the PCante was processed. Subsequently, the glass plates 6 were heated and rapidly cooled in a fluidized bed 17 in a quiescent uniformly expanded state of homogeneous fluidization. The fluidized bed 17 was composed of a mixture of the same powdered. ^un and γ-aluminum-III cid-I / Iaterialien together as described in Example 2. »Fig. 5 and 6 correspond to graphical graphs similar to Figs. 3 and 4« These figures reproduce the results were obtained for glass plates 6, which were heated to temperatures of 610 ⁰ C, 630 ⁰ C, 65Ο C and 670 C and then cooled rapidly.

The results show that the required hardening stresses can be produced in the glass 6, by doing functions of the proportion of the γ 1 χ 1 χ ΐύ Α Α χΑ χΑ und und und und und und ui ui in in in in in in in the mixture to have. Maximum voltages

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are achieved when the mixture to about 65 wt .-% to 95 t .-% of oC-alumina existed. For example, if that

Heated glass 6 to 670 ⁰ C and then in a Wirbelgemiscli from 22 wt. "-% ψ-Ά1υΐη ± η1υχαοχίά ^un & was cooled ^from 78 Aluminiuraozid rapidly, the mean tensile stress were in the glass 6 at 91 MPa and the Oberflächendruckspanntxng at 216 MPa ,

This 6-mni high-strength glass is used in the manufacture of windshields for aircraft and railway locomotives.

Similar results were obtained when it came to the hardening of gypsum plates of liatron-lime-silica glass with a thickness of 10 mm. Such glass sheets 6 are used in the manufacture of aircraft windscreens. These may consist aum example of two glass panes, of which the one from gehäi'tetem of glass having a thickness of 10 mm and the other outer pane of tempered glass having a thickness of 3 mm, "The two glass sheets 6 one another by plastic interlayers known type connected.

Be_i_sj3iel__4

Glass plates 6 made of ITatron lime-gravel! Acid glass with a thickness of 12 mm were cut to size and the edges were machined. Subsequently, they were heated and rapidly cooled in a fluidized bed of a mixture of ^^ alumina and <X- alumina in predetermined proportions in the same manner as described in Example 3.

The results were obtained for everyone glass plates 6 _s were heated to 610 ⁰ G ₅₆₃₀ ⁰ C, 650 ⁰ C and 670 ⁰ C. It was from a number of Mensenanteilen the two components

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^ -Alumina * and <Χ-alumina. The results are illustrated by the curves of Pig, 7 and 8.

Maximum values of stress were measured when the vortex mixture was composed of about 65% to 85% by weight of oC-alumina. When a glass plate is heated for 6 to 670 C and then in a fluidized bed 17 of a mixture to 22 weight _e ~% of "^ alumina and weight to the 78th ~% of" X. alumina was rapidly cooled, the average tensile stress was in the Glass at 124 MPa and the surface compressive stress at 261 LiPa.

Figs. 7 and 8 show how an extensive range of values for the curing stresses in the glass 6 can be obtained on demand. This is done by selecting the proportions of the constituents of the powdery mixture which have proven to be suitable for the particular temperature to which the glass 6 is heated prior to rapid cooling.

The results given in Pig. 3 to 8 have in common that higher hardening stresses are achieved when the proportion of rye in the mixture in the mixture is increased with the higher heat capacity (oC-alumina) to such a value from which a further increase in the above amount reduces the proportion of the gas evolution component (T alumina) to an insufficient level.

The range of proportions of the gas evolution material and the other component or the other components of the mixture to ensure eino .Fließeigenschaft the mixture in the range of 60 to 80 _s, the thus IDt ₅ arranged that the movement of the existing pulverförmi-gen

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Materials on the glass surfaces for the cooling of the glass 6 at such a speed favorable effect, at which the required values of / voltage in the glass 6 are reached.

The cooling of the glass 6 happens due to the rapid movement of the powdery! Materials near the glass surface *. In the process, Ji gives this movement essentially by the evolution of water vapor from the ^ -alumina as a constituent of the mixture.

A higher level of cC- alumina increases the rate of heat removal from the glass 6 and also modifies the plating behavior of the mixture.

The fluidized bed 17 in this example was composed of a mixture of γ- alumina as the gas evolution component with a content of sph ^; 3xoidal iron oxide (cC-PegO ^) and one kind or two kinds of OC- alumina together.

The "T" alumina exhibited the following characteristics:

Mean particle size. ", 84 / um

Particle size distribution .................. 1 »94

Flow property 87, 25

Water content (weight loss at 800 ^° C.) 6 %

Heat capacity per Yolumsneinheit at

a minimum fluidity "1.063 MJ / iA

The spheroidal iron oxide had the following characteristics:

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Mean particle size 41 / um

Particle size distribution ... »1,69

Flowing property 76, 5

Y / heat capacity per volume

at a minimum fluidization 2.01 MJ / m%

The first CC alumina used was that used in Example 1. The second CJC niuraoxide had the following properties:

Mean particle size, 24 / um

Particle size distribution 1.25

Flow characteristic 66

Y / heat capacity per unit volume

3 with a minimum fluidization 1.192 MJ / ra K

Glass plates 6 made of soda-lime-silica glass with a thickness of 2.3 mm were 660 G ^T ext: IRMT and in Wirbe rapidly cooled mixtures of the above materials. The fluidized materials were in a motionless uniformly expanded state of a homogeneous fluidization.

The characteristics of the mixtures and the average tensile stresses induced in the glass sheets 6 corresponded to the information given in Table 3.

Table 3σ results

'/ Wiluminiuraoxid Sphäroi dale s egg se monoxide CC -Alum in iümoxid (1) ®' ~ -Aluffliniumoxid (2)

Gew _o -% amount in your mixture

30 %

50 % 50 %

30 70

(4)

20 % 35 % 45 %

(5)

1 D - / 0

OD O /

36% 20 %

ζ Hf

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- 23

Weight % ? proportion ⁽ iLj in that mixture (D (2) 78 (4) (5) Flow behavior of the mixture: 82 79 1,726 74 73.5 Heat capacity of the silicic acid per volumetric hot "at a minimum fluidization (MJ / nPK) 1,347 1.54 50 1.502 1.44 Mean tensile stress (MPa) 45 49 57 53.0

Pig «9 illustrates the course of the change in the mean tensile stress depends on the composition of the mixtures (1), (2) and (3) ans f -alumina and o ^ -Fe ^ O., In Table 3 * The average tensile stresses on Reason of use of f-alumina alone and cC-FepO- alone was 41 MPa baw. 32 IiPa.

As in Example 1, the T ^ Aluniiniumoxii used in the present example has. has a plucking property high enough to achieve a maximum set stress in the glass sheets 6. The spha'oidal iron oxide has a lower flow property than the /-alumina, in particular because of its smaller particle size. The addition of increasing amounts of the spheroidal iron oxide to the aluminum oxide in the mixtures (1), (2) and (3) in Table 3 has a gradual effect of reducing the pouring behavior of the mixture by the continued reduction of the average particle size of the mixture, as the Meiigenantell is increased to sphäroidalcm iron oxide in the Gemiscii «% hen the Fließyennögen the mixture aUHiEsnt, it kOBimt to eiiier gradual increase in induced in the glass sheets average tensile stress." A

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 ft i ''

maximum mean tensile stress of 50 MPa is achieved when the mixture contains about 70 % spheroidal iron oxide and 30 % T * alumina.

The flow behavior of the spheroidal iron oxide is not as low as that of the oC ~ alumina used in Example 1 because it has a larger average particle size and the particles are smoothly rounded when compared to the sharp-edged particles of the OC aluminum oxide. Therefore, the spheroidal iron oxide is not as effective in lowering the flowability of the mixture as the OC-alumina in Example 1 does.

The mixture (3) of the present example includes 70 wt .-% to 30 wt spheroidal · Si se η oxide and -% at • 7'-Alimini umo:.: - ID, wherein, in the glass 6, the maximum average tensile stress of 50 MPa, a flow behavior of 78 to,. This is higher than the optimum rheology of 74% of the mixture of 70% by weight aluminum oxide and 30% by weight of alumina, producing a high average tensile stress according to Example 1.

However, the maximum mean tensile stress induced in the glass 6 by the mixture (3) in the present example is approximately equal to the maximum mean tensile stress generated by the mixture in Example 1 '. Although the fluidity of the mixture (3) is a little higher than the optimum flow characteristic at which the maximum stress is produced, this is because the spheroidal iron oxide used in the device (3) has a much higher heat capacity than the of the c £ -aluminum oxides used in Example 1

Because WtH adopted by the flow property of the mixture (3) ¹ qcj slightly too high to ± SE n _s is the anochließond

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Mixture (4) set. This contains a proportion of the OC-alumina used in Example 1. As a result of this addition, the flowability of the mixture was brought to an optimum value of 74, and the mixture caused a further increase in the mean tensile stress to 57 MPa, and this resulted in a reduction in the heat capacity.

Mixture (4) has the same optimum flowability property as 74, as in the mixture in Example 1, consisting of 30% by weight of T ^ "alumina and 70% by weight of cc- alumina" with a maximum mean tensile stress of 49 The fact that the mixture (4) causes a higher mean tensile stress of 57 MPa is attributed to the higher heat capacity of the mixture (4), ie, 1.502 MJ / W-K compared to 1.24 MJ / nrK of the mixture in Example 1..

The further lowering of the fluidity due to the addition of a proportion of a second & C aluminum oxide to the mixture (5) has led to a reduction in the heat capacity of the mixture compared to the mixture (4) _? with at the same time a slight reduction of the mean tension

The fluidized bed 17 was composed of a mixture of aluminum carbohydrate (Al ₂ O tHgO) as the gas evolution powder and zircon (ZrOp * SiO 2) sasammen.

The aluminum monohydrate: was present in the form of boehmite, which is a porous material containing 15 % by weight of chemically bound water of crystallization and 13% by weight of water in its pores. During the rapid cooling of the glass 6, the adsorbed water is released and crystallizes in the main

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to develop gas, resulting in increased movement of the powdery material near the glass surfaces.

The aluminum monohydrate used had the following characteristics:

Mean particle size »51 / um

Teileiiengrößenverteilung. 1.70

Flow characteristic. 78.

Water content (mass loss at 800 ^° C.). 28.4 %

Heat capacity per unit volume

at a minimum fluidization 1.18 MJ / πΑί

The zircon, which is an inert nonporous zirconium ortho-silicate with a higher. Heat capacity than the CC alumina, has the following characteristics:

Mean particle size. "34 / um

Particle size distribution: 1.73

Flow property ...... "" 67

Heat capacity per volura unit

at a minimum fluidization of 1, 76 MJ / nrK

Glass plates 6 having a thickness of 2.3 t have been now to 66o C ⁰ erwäi ^ and rapidly cooled in mixtures of aluminum monohydrate, and zirconium as specified in Table 4 below. Table 4 shows the properties of the mixtures and the average tensile stresses in the glass sheets.

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Table 4 «Results

Weight % proportion 50 % in the mixture 10 % 0 % aluminummonohydrate 100 % 70% 50 % 20 % 90 % 100% zircon 0% 30% 74 QA Ο * öU / o 71 67 Flow behavior of the Ge 78 75.5 1.41 73 1.70 1.76 Heat capacity of the mixture per unit volume at minimum fluidisation (MJ / m-%) 1 * 005 1,277 44 1.62 39 23 Mean tensile stress (MPa) 37 42 46.5

Pig. 10 illustrates the course of the change in the mean tensile stress as a function of the composition of the mixture.

The Aluininlurrjnonohydrat has good gas-generating properties and has a lower flowability than the 7-alumina in Examples 1 and 5. However, the flow characteristic of Aluslniummonohydrates is higher than the optimum flowability, in which a maximum average tensile stress is caused, and the heat capacity is relatively low. The zirconium has a lower flow characteristic and a higher heat capacity than the aluminum _{carbohydrate,} and when the amount of zirconium in the mixture is increased, there is a gradual increase in the mean tensile stress in the glass 6, 1, both gradually Reduction of the flow characteristic as well as by the increase of the heat capacity of the mixture.

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Daa zircon has a high heat capacity, which contributes significantly to the increase of the average tensile stress in the glass sheets 6 in the same manner as in the spheroidal iron oxide in Example 5. Because the zircon has a lower flow property than the spheroidal iron oxide in Example 5, it has a greater effect on reducing the fluidity of the mixture and thus makes a greater contribution to the increase in the mean tensile stress in the glass 6. This is done by reducing the Value of the flow characteristic of the mixture.

The maximum mean tensile stress of 46.5 MPa is achieved when the mixture contains about 20% by weight of aluminum monohydrate and 80% by volume of zirconium, the mixture having an optimum flowability of 73% *.

Further addition of zirconium above about 30 % by volume increases the heat capacity of the mixture, but results in a decrease in mean tensile stress due to a substantial reduction in fluidity below the optimum value and due to the reduction in the proportion of aluminum monohydrate the gas-generating component to a less effective level.

Beispiel_7

The fluidized bed 17 consisted of a mixture of t-alumina, with equal proportions of each of the four TiAl minium oxides, designated A ₅ B, C and D, as shown in Table 5. In this table, the properties of the four l? ^v aluminas wi edergegebcn _s

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! Table 5 '· Properties

f-Klxmln iumoxi de B C D A 61 57 72 Mean particle size (yum) 70 1.67 1.66 1.65 Teilcjiengrößenverteilung 1.47 88 85 86 flow property 88.5 7 7 7 Water content (mass % in % at 800 ⁰ G) 7 1.16 1.12 1.12 Heat capacity per voltsaen unit in a Zäindest- fluidization (MJ / iA) 1.16

The C-alumina had the following characteristics:

Mean particle size ».. 22 / um

Particle size distribution ................. 1.69

Flow property .......... 63

Heat capacity per volume unit

at a minimum fluidization 1.24 MJ / ra K

The glass sheets 6 from the Hatron-lime-silica glass having a thickness of 2 _S 3 mm were heated to 660 G and rapidly abgekülilt in gas ™ vüirbelgemischeii consisting of the above powdery materials. These layers of gas vortices were in a quiescent uniformly expanded state of homogeneous fluidization «

The properties of the mixtures and the mean tensile stresses induced in the glass panes 6 corresponded to the data in Table 6 below *

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36 -

* .4 .4

Table 6: Properties

Weight % proportion 20 % in the mixture Mixture of the four * $ - aluminas 100 % 40 % 80 % 10 % \ J / Q cc - aluminas 0 % 60% 67 90% 100 % Flow characteristic of the mixture 87 70 1.22 65 63 Heat capacity of the mixture per unit volume at a minimum fluidization (KJ / iÄ) 1.14 1.20 35 1.23 1.24 Mean tensile stress (MPa) 39 40 31 25

Fig. 11 -ve shows the course of the change in the mean tensile stress as a function of the composition of the mixture.

The foregoing examples have shown how higher voltages can be caused by mixing a gas evolution powder with an inert material, rather than using the gas evolution powder alone. However, it may be considered desirable to obtain lower stress values; than this can be the case with the use of the powdered gas-generating material alone «

In this example, this is achieved by the use of an oC-alumina having a small average particle size and a relatively large particle size distribution. This results in a significantly lower flowability compared to the c <-Aluminiiimo: xidene used in the previous examples

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The resulting maximum mean tensile stress was 40 MPa. In this case, a mixture was used which constituted 40% by weight of 'T' aluminum oxide and 60% by weight of OC aluminum oxide and had a flow property of 70. The maximum mean tensile stress of 40 MPa is only marginally above the mean tensile stress of 39 MPa, which is obtained when the T ~ alumina alone is used.

Further incremental addition of oc-alumina to the blends rapidly reduces the flowability of the blends to such low levels that the average tensile stresses obtained in the glass sheets 6 are less than the values provided by the use of alumina alone.

The fluidized layer 17 was composed of a mixture Together, which weight to 9 -..% Of zeolite, which is a porous crystalline aluminosilicate, wherein the Y / ater is adsorbed in the pores present, and 91 parts by weight / 5 from ° £ - Aluffiinium to st.

The zeolite had the following characteristics:

Average particle size 24 / um

Particle size distribution * «......., 4

Flow property 51

Water content (weight loss at 800 ^° C) ... 20 %

Heat capacity per unit volume

in a Miiadestfluicüsation ... '^ ........ 0.8 MJ / m ^ K

The. .oc-Alumina had the following properties:

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ftt ^ Vis * da &> __ -yg _

..; Mt * ''

Mean particle size .. 37 / um

Particle size distribution 1.682

Flow property 70

Heat capacity per unit volume

at a minimum fluidization 1, .4 MJ / m K

The heat capacity of the mixture per unit volume was at a minimum fluidization of 1.34 MJ / nAi and the fluidity of the mixture was 60.

A glass plate 6 with the thickness of 2.3 mm was heated to 660 ⁰ G and Irbe in the v /! Mixture rapidly cooled. In this case, an average tensile stress of 41 MPa was caused in the glass sheet 6. By changing the selected proportions of the einseinen components of the mixture could be on the glass sheet 6, an average tensile stress within the range of 25 MPa to 41 MPa caused.

Example 9

The mixture of the powdery constituents for the production of the fluidized bed 17 consisted of 20 % by weight of polyimide oxide and 40% by weight of each of the two cis-aluminum nitrate oxides which were readily available and instead of a single more sparing α-alumina.

The properties of the f'-alumina can be given as follows

Mean particle size. ,, 57 / um

Particle size distribution ............ * .... 1.66

Flow characteristic. 85 /

Water content (Iviarässverlust at 800 ⁰ G) ... 7 %

Heat capacity per unit volume

at a minimum fluidization 1.18 MJ / m ^ K

0%

fei

Ho

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Me properties of the two <X-Aluminium02d.de A and B can be seen from Table 7 as follows.

The fluidity of the mixture was 73.5 and the heat capacity of the mixture per unit volume at a minimum fluidization was 12.5 MJ / nrK.

A glass plate 6 having a thickness of 2.3 mm was heated to 660 ⁰ C and the V / Irbe! Mixture rapidly cooled. In this case, an average tensile stress of 48 MPa was produced in the glass 6. By varying the selected relative proportions of the components of the mixture, a selected average tensile stress in the range of 34 MPa to 48 MPa in the glass sheet 6 could be produced.

Table.7 * Properties

oC ~ alumina A B Average particle size (/ um) particle flow property of heat capacity per unit volume at ej _f ner Mindestfluidisation '(LiJZm- ⁵ K) 38 24 1.19 1.25 75 66 1.14 1.19

At s-iii el 10

The versatility of the process of the present invention is further illustrated by the preparation of a "tailor-made" blend by blending together multiple gas evolution ingredients and several inert ingredients, all of which are available and are relatively inexpensive materials. With these ingredients becomes a mixture

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has seiche gas evolution properties, optimum flow characteristics and heat capacity. Thus, the required tensile stresses in the glass 6 are achieved in the rapid cooling of the glass 6 in each mixture when the mixture is in a quiescent uniformly expanded state of homogeneous fluidization.

In this example, the mixture contained each of the four Ύ-aluminas designated A, B, C and D 'in an amount of 5% by weight. The properties of these ingredients are given in Table 8 below:

Table 8: Properties

Mean Particle Size (/ um) Particle Size Distribution Flow Property

Water content (mass loss in % at 800 ^° C.)

Heat capacity per unit volume for a single dilution (LiJ / m ^ K)

7-alumina

A B C D

70 61 57 72 1.47 1.67 1.66 1.65 88.5 88 85 86

7th

1.16 1.16 1.12 1.12

This total amount of 20 Ge \ v .-% T alumina was 26.6 wt -.% Each of the three oC ~ aluminas E, F and G are mixed, whose properties are further indicated below in Table 9.

Hi

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Table 9 ί Properties

cc-alumina P G e 30 24 Mean particle size 33 1.22 1.25 TeilchengrößenverteilTäsig 1.19 70 66 flow property 75 1.3 1.19 Heat capacity per unit volume at minimum / fluidization (MJAr ⁵ K) 1.38

The flowability of the mixture was 74, and the heat capacity of the mixture Pa ^-1 O volume unit at the minimum fluidization was 1.26 MJ / m K.

A glass plate 6 having a thickness of 2.3 mm was heated to 660 C and rapidly cooled in the fluidized mixture. The mean tensile stress caused thereby in the glass pane 6 was 49 MPa. By ¥ the selected proportions of the T ^ -Aluminiuraoxide, which are involved in the mixture to 20 wt .-% hange, or by changing the proportions of the cc-aluminas, never weight of the mixture to 80 - are involved%. or by changing the relative proportions of total 7Si-aluminas to total ^ -aluminum oxides in the mixture, a selected average tensile stress in the range of 32 to 49 MPa could be produced in the glass 6.

 Example 11

The homogenous fluidized bed 17 set to 17 wt .-% of the Aluminiuinnionohydrat of Example 6 in a mixture with 83 Gevi, -% of silicon carbide having the following characteristics to-

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& 'Φ Ü; ä - 42 -

Mean particle size 40 / um

Particle size distribution .1,32

 Flow characteristic ··. 72.75

Heat capacity per unit volume

with a minimum flow ♦ .. _t 1.21 MJ / nrK

The flowability of the mixture was 75, and the heat capacity of the mixture per unit volume at a minimum fluidization was 1.02 MJ / iA.

A glass plate 6 having a thickness of 2.3 mm was heated to 66 ° C. and rapidly cooled in the fluidized mixture. The average tensile stress induced in the glass sheet 6 corresponded to 51 MFa:. These materials provided the ability to produce a selected average tensile stress in a wide range of 32 MPa to 51 MPa in the glass sheet 6. For the purpose of this, the individual components of the mixture were selected in predetermined proportions in order to apply the vortex mixture to achieve the required tensile stress in the custom glass,

"Example 12

In a Zweikoinponentengemisch both powdered materials about GascntvJicklungseigenschaften can have .. A mixture was blended in equal proportions in -.% From ~ F ~ Alumina and aluminum trihydrate (AIpO- ,. 3HPO) is (~ aluminum trihydroxide) stated "A proportion of the crystal water dee aluminum trihydrate released upon heating, and in addition to the effect of the released from the pores of the 7 ^ -Aluminiurnoxi.des water. ^v

The properties of the 7-alumina can be stated as follows:

έί

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Mean particle size, ", 60 / um

Participation size distribution is 1.9

Flow property ..... "" 84

Water content (mass loss at 800 ^° C.). 8 %

Heat capacity per unit volume

at a minimum fluidization ......... 1.05 MJ / nrK

The characteristics of aluminum trihydrate can be stated as follows: ·

Mean particle size ",. 86 / um

Particle size distribution 1.42

Flow characteristic .... 86

Water content (mass loss at 800 ^° C.). 34 %

Heat capacity per voltaic unit

at a minimum fluidization of 1.56 MJ / m ^ K

The flow characteristic of the mixture was 85-25, and the heat capacity of the mixture per unit volume at a minimum fluidization was 1.31 MA

A glass plate 6 having a thickness of 2.3 mm was rapidly cooled to 660 ° C and rapidly cooled in the fluidized mixture. In this case, an average tensile stress of 47 MPa was caused in the glass pane 6. By means of a suitable selection of the relative mengon parts of the two gas evolution materials, a selected mean tensile stress in the range of 42 KBa to .47 MPa could be achieved in Eq.

Beisj3iel_J_3.

Gas developer powders that develop gases other than water vapor upon heating can be used, for example, the urhydric carbonate (HaHCOo) _. releasing the both carbon dioxide and water, a mixture of 10 wt ~ _e / 5 Hatriumhydrogen! carboxylic at a part on of 0.6 Ge \ v. ~% colloidal.

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Silica for the purpose of improving the flowability of the sodium hydrogencarbonate and 90% by weight oC-alumina of the grade A according to Example 9 was used.

The characteristics of the mixture of the sodium bicarbonate and the colloidal silica can be stated as follows:

Mean particle size · 70 , im

Particle size distribution 1.98

Flow property 75

H ₂ 0 / C0 ₂ content (mass loss at 800 ⁰ G) 37% <

Heat capacity per unit volume -

at ejkier I'.lindestfluidisation 1, 41 MJ / m K

The fluidity of the vortex mixture was 75 > and its heat capacity per unit volume at the minimum fluidization was 1.38 l,! J / m ³ K.

Sine glass plate, 6 with a thickness of 2.3 mm, was heated to 660 C and then rapidly cooled in the vortex mixture. The mean tensile stress in glass 6 was 53 »5 IiPa. By appropriate selection of the relative proportions of the components of the mixture, a selected average tensile stress in the range of 34 MPa to about 55 MPa could be produced in the glass 6.

In many of the above examples, an indication of the stresses induced in the glass, when rapidly cooled in the homogeneous fluidized bed, was given by the stresses induced in a sheet of glass of liatron-lime-silica glass 2.3 mm thick, provided that Heating to 660 C was performed and the glass 6 was then cooled rapidly. In the same manner as described in Examples 2, 3 and 4, different tensions can be achieved by heating the temperature

 1.2. 1930

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.- "to" 0 $. * Φ fiä 4i »- /J.φ -

which the glass 6 is heated, is changed. In this case, 6 correspondingly higher voltages are then produced in thicker glass.

The examples all illustrate the manner in which the selection of a proportion of a powdered gas evolution material capable of developing gases corresponding to 4% by weight to 47% by weight of its own weight when heating at 800 ° C a mass constancy is to take place and then the mixing of the gas evolution material in predetermined proportions with other powdered gas evolution materials or with other inert materials has to be done. The mixture may be "custom-made" in the manner to obtain a desired flow property in the range of 60 to 86 and a heat capacity per unit volume at the minimum fluidization in the range of 1.02 to 1.75 HJ / mK , As a result, it is ensured that the glass sheet 6, which has been rapidly cooled in the mixture, undergoes the required heat curing. This is indicated by the mean tensile stress in the above examples. According to the usual conditions in thermoset glass, the ratio of the surface compressive stress to the mean tensile stress is 2: 1, and the surface compressive stress caused in the glass is about twice the indicated average tensile stress.

When applying the inventive method, the Härtungobedingungen can be readily reproduced, and there is a Mb "possibility ₅ to make use of the property for grouting powdered materials extended use and mixtures of cheaper and more readily available materials in powder form instead of sparse available and expensive individual components of the Mixture to use, thereby reducing the operating costs are reduced.

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Further, by proper selection of the powdered materials and the proportions in which they are mixed, it is possible to produce selected higher curing stresses in the glass than the stresses which could be achieved by any constituents of the almonds "when used alone become.

Some of the above-described powdery materials were commercially available with a suitable average particle size, particle size distribution, flowability and heat capacity.

If these properties of the required materials, for example, in the case of α-alumina, are not present in the commercially available materials, sieving must be conducted to obtain classified powdered materials having the required properties for blending with other ingredients to obtain a mixture which, in the state of fluidization, would produce the required curing stresses in the glass.

It has been found that the swirl mixtures in Examples 1 to 4 and 13 are particularly suitable for heat curing glass sheets for laminated safety glass for making windshields for motor vehicles. The flowability of such mixtures corresponds to 71 to 83, their gas content as mass loss when heating to mass constancy at 800 C 4 % to 37 % and their heat capacity per unit volume at the minimum fluidization of 1.09 to 1.3B MJ / iÄ.

By selecting the proportions of ingredients of the mixture, it is possible to develop lower stresses in the glass than those produced by the gas evolution additive alone. This relationship is explained in more detail in Example 7.

Claims (24)

1.2. 1930 AP C 03 B / 215 022 ff lift 55 994/24/32 Experiences withjjr A method of heat treating glass in which the glass is heated to a predetermined temperature and contacted with a homogeneous layer of gas scrubbing, characterized in that a powdered material is used which is composed of a mixture of a series of selected powdered material in that at least one of the powdered materials has gas evolution properties when heated by the hot glass, and the materials are mixed in selected predetermined proportions to impart a heat capacity and flow characteristic to the homogeneous gas vortex mixture such that a desired heat treatment of the glass is achieved; 2. The method according to item 1, characterized in that the powdered Materialisn be mixed in selected predetermined proportions such that the required hardening stresses in the glass pane (6) are caused when in the homogeneous gas fluidized bed (17) from a temperature above the is cooled to the lower cooling point of the glass (6). 3. The method according to item 2, characterized in that is selected as the powdered Gasevvieklungsmaterial such that is able to develop gas to 4% to 37 % of its own weight, if it is heated to a mass constancy at 800 G , and the powdery! Materials are mixed in predetermined proportions with each other, wherein the mixture is given a heat capacity per unit volume at a minimum fluidization of 1.02 to 1.7.5 MJ / rA and a flow property of 60 to So * 4o Method according to point 3 for heat-curing a glass plate made of Ilatron lime Kießelsärureeilas with a thickness of 2 mm O" - '.. ί · Τ RIM RiUK'. * ,! 7 · ί Κ ' 1. 2. 1930 AP C 03 B / 215 ^ 1 S © 8f 19 55 994/24/32 - 48 -. 2.5 mm, the glass plate is heated to a temperature of 610 ⁰ C to 680 ⁰ C and held the mixture in a resting uniformly expanded state of the homogeneous fluidization, characterized in that the powdery materials are composed so that in Glass plate (6) an average tensile stress of 35 MPa to 57 MPa is generated. 5. The method according to item 3 or 4, characterized in that the powdery materials are mixed in predetermined proportions with each other, whereby the mixture has a flowability of 71 to 83 and a heat capacity per unit volume at a Mindestfluidisation of, 1.09 to 1.38 MJ / iA is awarded. 6. Process according to any one of items 1 to 5, characterized in that the pulverulent gas evolution material is - alumina » 7. The method according to item 6, characterized in that the "^ alumina is present in a mixture with the ^ -Aluminiumoxid. 8. The method according to item 6, characterized in that the mixture is from 7% by weight to from 86% by weight of aluminum oxide and from 93% by weight to 14% by weight; composed of oC- alumina. 9. Method according to item 3 or 4 », characterized in that a hot glass pane (6) in a gas vortex mixture (17) is rapidly cooled off from a homogeneous pulverulent gas evolution material and at least one pulverulent metal oxide, its heat capacity per unit volume at a mind fluidization 1.76 MJZm constitutes ³ K to 2.01 Γ, Ιο / ηΑί, and wherein the powdered materials in predetermined ivie ngenan te ilen among themselves, mixed ¹ er w to to the mixture a Wärmekanazität per unit volume in the 1. 2. 1980 & C 03 B / 215 022 9 ί-% fh ^ ^g P ^ ^{0 s 55} 994/24/32 Minimum fluidization of 1.27 MJ / m ³ K to 1.76 MJ / m ³ K and a flowability of 71 Ms 82 to give. 10, the method according to item 9, characterized in that the powdered metal oxide is spheroidal iron oxide ( ⁰ C-FepOO. 11. ^ experience according to item 10, characterized in that the mixture to 30 wt .-% to 70 wt .-% composed of spheroidal iron oxide * 12. The method according to item 11, characterized in that the mixture is composed of 70% by weight to 30% by weight of T- alumina as the gas evolution material, 1.3 · method according to item 11, characterized in that the mixture to 28 wt .-% to 35 wt .-% of spheroidal iron oxide and below 45 wt. "- zusaramensetzt% to 56% of Gevi ~ cc-alumina, the Remainder corresponds to the ^ alumina as the 'Gasentwicklungsmateriai. 14 «method according to Punlit 9, characterized in that the powdered metal oxide zirconium (ZrOg.SiOg) is. 15. The method according to item 14, characterized in that. the mixture to 10 wt -.% to 70% of GevK- Aluminiummonohydrat- (AIPO ^ 1HPO.) weight as the gas evolution material and 90 wt .-% to 30 _a .-% composed of zirconium.. 16. The method according to any one of items 1 to 4, characterized in that the gas evolution material is an aluminosilicate. 17. The method according to item 16, characterized in that the aluminosilicate equal to. Zeolite and the zeolite to form the mixture to 8 wt - . % To 10 wt .-% with ⁰ V 1. 2. 1380 AP C 03 B / 215 022 2ί5 ^ 9P ^5Λ 55 994/24/32 % is mixed - wt miiiiurnoxid 90 "wt .-% to 92.. 18. A process according to any one of items 1 to 4, characterized in that the gas evolution material is aluminum monohydrate (Al ₂ O- ^ IH ₂ O). 19. A method according to any one of items 1 to 4, characterized in that the mixture of silicon carbide (SiC) and a powdered! Gas development material ". 20. A method according to item 19, characterized in that it is "Alurainiurnmonohydrat (Al ₂ O IHgO) in the gas evolution material and the mixture to 17 wt .-% of Äünlniummonohydrat and 83 Gevi.-fo of 'silicon carbide , composed. A method according to any one of items 1 to 4, characterized in that the powdery gas evolution material corresponds to the aluminum trihydrate (Al ₂ O -., 3H ₂ O). 22. Method according to any one of items 1 to 4 »characterized in that the mixture of two powdered! Gssentwicklungnmoteriälien composed of Aluminiumtriir / clrat (AloO ^ .3HpO) and? ^ Alumina in equal proportions. The method according to any one of items 1 to 5 is characterized in that the sodium hydrogen carbonate (UaHC0.0) is used as the gas evolution material, 24. The method according to item 23 *, characterized in that 10 Gevn-5S H & triumhydrogenkarbonat and 90 Ge.YK-fo ^ -Aluniiniuir.oxid mixed with each other to form the mixture. '& 1. 2. 1980 AP G 03 3/215 022 .9 51 55 994/24/32 Apparatus for carrying out the method according to item 1, comprising a container for the homogeneous gas vane layer, gas connections to the gas supply container for maintaining the state of homogeneous fluidization, and means for positioning the hot glass in the container, characterized that in the container a gas fluidized bed (17) of selected powdered materials is present, at least one of which when heated by the hot glass plate (6) gas evolution properties, wherein the mixture of the powdery materials in selected predetermined I.iengenanteilen with each other to award the for the , Heat treatment of the glass plate (6) required heat capacity and flow characteristic is provided.