JPS5925735B2 - Manufacturing method of heat treated glass plate - Google Patents

Description

[Detailed Description of the Invention] The present invention manufactures heat-treated glass that does not cause cracks to propagate even when a glass plate cracks, has sufficient wind pressure resistance, and does not crack due to heat, and is ideal for use in windows of high-rise buildings. It is about the method.

For example, in high-rise buildings, extra-thick glass plates of about 10 to 20 mm are used to improve the wind pressure resistance of window glass plates.

The main problem with using such extra-thick glass plates is that the weight increases significantly, and if thick heat-absorbing glass or colored coated glass plates are used, there is a particular risk of thermal cracking. It has the disadvantage of being highly sensitive.

Although it is possible to use air-cooled tempered glass sheets to reduce weight and prevent heat cracking, air-cooled tempered glass sheets break into many small pieces when broken, so air-cooled tempered glass sheets are not used in high-rise buildings. It is undesirable to use glass panels because there is a risk that glass fragments may fall from the windows of high-rise buildings when they break.

There is also a chemically strengthened glass sheet that has a high surface compressive stress and a low fragment number density as a type of tempered glass sheet, but this chemically strengthened glass sheet has a significant decrease in strength when scratched and is difficult to process during the strengthening treatment process. It is not suitable for practical use because it requires a long time.

First, the applicant has discovered that, unlike conventional tempered glass plates, even when a crack occurs in the glass plate, the crack does not propagate by itself.
A heat-treated glass that has sufficient wind pressure strength and does not crack under heat and is suitable for use in window glasses or spandrels of high-rise buildings, that is, a heat-treated glass plate with a thickness of 5 to 10 mm,
The central tensile stress σt of the heat-treated glass plate is 85 kg/
i to 200ky/d, and the ratio σC/σt of the surface compressive stress σC and the central tensile stress σt is 1.5
We proposed a heat-treated glass plate with a cross-sectional stress distribution in the range of ~3.0.

The present invention was obtained as a result of repeated research aimed at providing an industrial manufacturing method for such a heat-treated glass plate, and its gist is that a glass plate with a thickness of 5 mm or more and less than 10 mm is heated in a heating furnace. After heating the glass plate to 600°C to 660°C through the heating furnace, the glass plate is taken out from the heating furnace and cooled with air.The cooling capacity of the air cooling is gradually increased over time, and the central tensile stress σt of the cooled glass plate is 85-200k
More preferably, the surface compressive pressure is 250 g/ffl, and the ratio σC/σt of the surface compressive stress σC and the central tensile stress σt is in the range of 1.5 to 3.0.
The present invention relates to a method for producing a heat-treated glass plate, which is characterized by controlling the heat-treated glass plate so that the heat-treated glass plate has a weight of 350 kg/cyrt.

A conventional tempered glass plate made of soda-lime glass is heated to a softening temperature range of 600°C to 700°C and then immediately quenched and strengthened by blowing air on both sides of the glass plate. /ffl~150
A surface compressive stress of 0 Y/d and a tensile stress of approximately 1/2 of the surface compressive stress are generated at the center in the cross-sectional direction, and the cross-sectional stress distribution is as shown in FIG.

When this tempered glass plate breaks, the cracks generated in the glass plate propagate by themselves, and the fracture density is uniquely determined by the magnitude of the central tensile stress, for example, 40 to 2.
00 pieces 15cfrL will break into small pieces.

Also, the semi-strengthened glass plate has a surface compressive stress of 300 to 600 kg/ffl, a central tensile stress σt of 250 to 400 kg/crit, and a ratio σ/σt of less than 1.5,
The cross-sectional stress distribution is as shown in Figure 2.When this semi-strengthened glass plate is broken, it does not break with small pieces, but the cracks that occur in the glass plate at the time of breakage propagate on their own, causing the glass plate to break. It reaches the end.

In addition, chemically strengthened glass plates have a weight of 1000 kg/ffl to 30
00 kg/ffl surface compressive stress and 10-60 kg/ffl
d, and its cross-sectional stress distribution is the third
As shown in the figure, if this chemically strengthened glass sheet breaks, unlike air-cooled tempered glass sheets, cracks will not propagate by themselves, but it has poor scratch resistance and cannot be considered a strengthened glass sheet in practical terms. .

On the other hand, the heat-treated glass plate produced according to the present invention has a central tensile stress controlled as low as 85 to 200 to 97d, and a ratio σC/σt of the surface compressive stress σc to the central tensile stress σt. The surface compressive stress is controlled within the range of 1.5 to 3.0, and the surface compressive stress is also 127 to 600.
kg/i range, more preferably 250 to 350 kg/i
i is suppressed to a low level and the cross-sectional stress distribution is as shown in FIG. 4, so when a crack occurs in this heat-treated glass plate, the fracture line does not propagate by itself and it does not break into small pieces.

Moreover, this heat-treated glass plate has a thickness of 57n7IL or more10
m7n and 127ky/i to 600 kg
/crrt, preferably 250 to 350 kg/i, so the wind pressure strength is more than twice as strong as a raw board of the same thickness, which is sufficient for practical use, and it does not suffer from thermal cracking. .

For example, the plate thickness is 6 yen and the central tensile stress σt is 250 kg/
ffl, surface compressive stress σc is 500 kg/i (a c/
In the heat-treated glass plate of σt-2), if the central tensile stress is too high and the glass plate cracks, the crack propagates on its own and the fragments become finer, resulting in a fracture pattern as shown in Figure 5. This is undesirable as there is a high risk of debris falling from the window.

Also, the plate thickness is 8 mm and the central tensile stress σt is 300 kg, /=
, the surface compressive stress σc is 580 kg/ff1 (i.e. σC/
The glass plate with σt=1.93) is the same as the above example, and the sixth
It will look like the figure.

On the other hand, the fracture patterns of the glass plates manufactured according to the present invention, for example, the heat-treated glass plates of the samples of Examples 1 to 5, are as shown in Figs. 7 to 11, respectively. This prevents many lines of breakage from entering the glass plate from one end to the other, and prevents broken pieces of the glass plate from falling from the window.

In addition, the surface compressive stress required to prevent thermal cracking and wind pressure fracture is 127 kg/ff1 or more, particularly preferably 250 k.
g/cr? Since it has a higher surface compressive stress than L,
There is little risk of thermal cracking, and it also has sufficient wind pressure resistance.

In addition, when a glass plate breaks, the self-propagation of the crack is suppressed so that the fracture line (crack) does not extend from one side of the glass to the other, so there is a risk of broken pieces of the glass plate falling from the window. Although it is preferable to have a small number of broken lines (cracks) extending from one side of the glass plate to the other, there is actually no danger of broken pieces falling from the window into the ground, so this type of breakage of about one line is not recommended. The presence of lines (cracks) is acceptable as a fracture pattern in the heat treated glass produced according to the present invention.

Next, a specific example of the method for manufacturing a heat-treated glass plate of the present invention will be described.

FIG. 12 shows a specific example of the apparatus used for manufacturing the heat-treated glass plate of the present invention. In the figure, 1 is a glass plate, 2 is a roller berth, and 3 is a glass plate conveyor. The roll, 4 is a heating device for the glass plate, and 5 is a cooling outlet provided opposite to the glass plate.

The glass plate 1 to be heat-treated is heated to a temperature sufficient to heat-treat the glass plate, for example, 600 to 660°C, while being horizontally conveyed or slid horizontally in a roller berth 2 by a conveyor roll 3. .

The glass plate 1 taken out from the roller berth 1 is
The glass plate is moved between the vertically opposed cooling ports 5 and cooled by blowing air so that the cooling capacity gradually increases over time. After the temperature of the glass plate has decreased to 100 to 300°C, it is taken out from the cooling ports 5 and placed at a predetermined level. A heat-treated glass plate product having a stress value and stress distribution is obtained.

In the present invention, when cooling a heated glass plate while gradually increasing the cooling capacity, the cooling capacity K ('C/sec) is changed over time into the range shown by the following formulas (a), (b), and (c). It is preferable to increase the amount gradually.

0.1 t-1,6≦≦0.6t (0≦t≦16,7
, K2O)... (a) 0.1t-1,6≦≦10 (16,7≦t≦41
) ......(b) 2.5≦≦10 (
t≧41) --(c) (unit, K: °C
/second, t:second) The above range is the area P surrounded by diagonal lines in FIG. 13, that is, K=0.6 t (0≦t≦16.7)
(t≧16.7) and =0.11-1.6 (15≦t
≦41), 2.5 (t≧41), and 0 (including the area on each line).

However, it is preferable to gradually increase the cooling capacity K within this region P with time.

In particular, in the case of glass plates with a thickness of 5 mm or more and 5.5 mm or less, the cooling capacity K ('C/sec) is calculated as shown below (d) over time.
, (e), (f) It is preferable to gradually increase the amount within the range shown by formulas.

0.32 t-1,7≦≦0.6t (0≦t≦16.
7, K≦0)・・・・・・(d) 0.32 t-1,7≦≦10 (16,7≦t≦
30) −・・・・・・(e) 7.9≦≦10
(0≧30) ・・・・・・(f) (unit,
K: °C/second, t: second) This range is the area X surrounded by diagonal lines in Fig. 14, that is, K
=0.6 t (0≦t≦16.7) and K-1O(t
≧167) and = 0.321-1.7 (5≦t≦30
), K=7.9 (t≧30), and the area surrounded by each line of =O (including on each line).

However, the area on the line K=0 is excluded).

In addition, in the case of a glass plate with a thickness of 5.5 mm or more and 7.5 mm or less, the cooling capacity K (°C/sec) is expressed over time by the following formulas (g), (h), and (i). It is particularly preferable to gradually increase the amount within a certain range.

0.2t-2≦≦0.321-1.7 (5≦t≦3
0, K2O)... (g) 0.321-1.7≦≦7.9 (30≦t≦37)
・・・・・・(h) 5.4≦≦7.9
(t≧37) ・・・・・・(i) (Unit, K
:°C/sec, t:sec) This range is the area Y surrounded by diagonal lines in FIG.
9 (t≧30) and K=0.21-2 (10≦t≦3
7) It is indicated by a region surrounded by each line of t = 5.4 (t≧37) and =O (including on each line, except for K=0 on the line).

In addition, in the case of a glass plate with a plate thickness of 7.5 mvt or more and less than 10\mm, the cooling capacity K ('C/sec) is expressed by the following formulas (1), (m), and (n) over time. Particularly preferred is a gradual increase within this range.

0.1t-1,6≦≦0.2l-2 (10≦t≦37
, K2O)... (A) 0.11-1.6≦≦5.4 (37≦t≦41)
・・・・・・(E) 2.5≦≦5.4 (
t≧41)...(n) This range is the area Z surrounded by diagonal lines in FIG. 14, that is, K=0.2 t-2(1
0≦t≦37), K-5,4 (t≧37), and K=0
．． 11-1.6 (15≦t≦41) and K=2.5 (
t≧41) and is surrounded by each line of =0 (including on each line).

However, K=0. ) on the line, excluding)
Heating the glass plate to 0°C, cooling with gradually increasing cooling capacity,
More preferably, it is important to gradually increase the cooling capacity within the range shown by the above formulas (a), (b), and (c), and to combine these conditions.

'The method for manufacturing the heat-treated glass plate of the present invention described above utilizes a roller berth, but it is not limited to this method; the glass plate is heated while being conveyed horizontally using a gas berth, and the glass plate is heated through the outlet of the gas berth. Immediately after heating, the heated glass plate is heat-treated, or the glass plate is suspended from a hanger and heated in a heating furnace while being transported, and the heated glass plate is heat-treated immediately after it comes out of the outlet of the heating furnace. can also be produced in the same way.

Example A soda-lime glass plate was heat-treated using the above-mentioned apparatus under the conditions shown in Table 1, and the central tensile stress σt, surface compressive stress σC1σC/σt, and allowable load indicating wind pressure resistance of the heat-treated glass plate were determined. (Destruction probability 1/l OOO or less)
The results of the thermal cracking test (temperature difference between the central part and the peripheral part of the glass plate until thermal cracking) are also shown in Table 1.

In addition, the fracture patterns when the destructive test specified in JISR3206 6-5 was conducted on the heat-treated glass plates of Examples 1 to 5 and the heat-treated glass plates of Comparative Examples 1 and 2 were shown in Nos. 5 to 1.
It is shown in Figure 1.

By the method of the present invention, the central tensile stress σt is 85 to 200.
kg/cyit, and the ratio of the surface compressive stress σC to the central tensile stress σC/σt is 1.5 to 3.0.
The reason why a heat-treated glass plate having a temperature within the range of .

Normally, when a glass plate is strengthened under constant cooling conditions, the temperature distribution in the cross-sectional direction of the glass plate reaches a steady state after passing through a certain transition state.

The temperature distribution at this time can be represented by a quadratic curve M represented by a parabola.

When the softened glass plate solidifies in this state, residual stress corresponding to the temperature distribution is generated and strengthened.

(See FIG. 15) The method of the present invention focuses on controlling the temperature distribution when the softened glass plate is solidified.

In other words, the temperature distribution in the cross section of the glass plate is uniquely determined by the cooling conditions once the plate thickness is determined, so by controlling these cooling conditions, the temperature distribution when the glass plate solidifies can be determined from the quadratic curve M as shown in Figure 16. This is to control the reinforcing stress generated by providing a temperature distribution as shown by curve N.

It has been found that such a temperature distribution can be obtained by maintaining the transition state at the initial stage of cooling until the glass plate is solidified, that is, by gradually increasing the cooling.

Outside the range of the conditions of the heat treatment method of the glass plate of the present invention described above, that is, the S direction shown in FIG. This is not desirable because
In the T direction shown in the figure, the cooling capacity is insufficient, so the surface compressive stress required for wind pressure strength is σC≧125kg/Cr? This is not preferable because L cannot be obtained.

As described above, according to the present invention, the wind pressure strength is sufficient for practical use, there is no thermal cracking, and furthermore, even if a crack enters the glass plate, the crack does not propagate by itself and does not break into small pieces. Heat treated glass can be provided.

Even if this glass plate breaks, there is little risk that some or all of the pieces will fall off the window frame, and it is useful as a glass plate for construction of buildings, houses, etc.

In particular, the heat-treated glass sheet produced by the method of the present invention is ideal for use as a window glass sheet for medium-to-high-rise buildings, which requires a glass sheet that is free from the risk of falling glass fragments.

The heat-treated glass sheet manufactured by the present invention is particularly suitable for glass sheets such as heat-absorbing glass sheets, colored coated glass sheets, and heat-reflecting glass sheets used for windows or spandrels that have a high risk of thermal cracking. It is.

In addition, the glass plate manufactured according to the present invention has improved wind pressure strength and thermal cracking strength, and also prevents self-propagation of cracks. The window glass plate can be replaced with a 6 mm thick heat-treated glass plate manufactured according to the present invention, and the weight of the glass plate can be reduced.

The surface compressive stress of the glass plates in the above Examples and Comparative Examples was measured using a Toshiba air-cooled tempered glass surface stress meter FSM-30, and the central tensile stress was measured as follows.

・Measurement of central tensile stress Hold the glass plate sample 11 horizontally as shown in Figure 18,
Linearly polarized light A, which has been passed through a polarizer 13, a lens 14, and an aperture 15 using a He-Ne laser 12 as a light source, is incident perpendicularly to the end face.

Let y and Z be the directions parallel and perpendicular to the surface of the glass plate 11, respectively, and let X be the incident direction.

The direction of vibration of the incident light is set at an angle of 45° with respect to each axis in the y-z plane.

The linearly polarized light A incident from the end surface of the glass plate 11 produces a phase difference due to the principal stress difference in the y-'-z plane inherent in the glass, and forms an angle of 45° with the y-z axis as shown in FIG. The polarization changes as follows: ellipse with axis → circle → ellipse → straight line (perpendicular to the incident light) → ellipse → circle → ellipse → straight line, and with a phase difference of 360°, the vibration direction returns to the same linear polarization as the original incident light.

This polarized light is scattered within the glass and is perpendicular to the optical axis.
When observed from a direction of 45° with respect to the y and z axes in the '-'-z plane, it appears as dots for each wavelength as shown in B of FIG. 20 or as shown in FIG.

Since the scattering of the float glass plate is very small, the scattered light to be observed is weak.

To this end, a night vision device with a built-in micro-channel image intensifier is used to project a dot pattern of scattered light onto a monitor television 17 through a high-sensitivity television camera 16.

In combination with the position analyzer 18, the length can be read in real time.

Since one dot corresponds to a phase difference of 360° (one wavelength), by measuring this actual length, the principal stress difference can be determined using the photoelastic constant.

From the principal stress difference Δσ found here, the central tensile stress σy is determined by the following formula.

Principal stress difference △σ σy: Component of stress in the plane direction, i.e. central tensile stress σZ: Component of stress in the thickness direction (σ2ki0) λ: Laser light wavelength (632,8m μmHe-Ne laser) lλ: 360° Optical path difference (b) corresponding to phase difference C: Photoelastic constant 2.63 mμ/CrrL/kg/d (float plate) Note that the central tensile stress σt manufactured by the present invention is 85
~200kg/cr? L, surface compressive stress σc is 127~
600 kg/i, more preferably 250-350 kg
/cr? The above stress values of the heat-treated glass plate L are the first
As shown in Fig. 8, it shows the average of the measured values at 5 points i, 4 points P on the periphery and 1 point Q in the center of the heat-treated glass plate, and is taken as an average value.

[Brief explanation of drawings]

1 to 3 are stress distribution diagrams of a cross section in the thickness direction of a conventional tempered glass plate, FIG. 4 is a stress distribution diagram of a cross section in the thickness direction of a heat treated glass plate manufactured according to the present invention, and FIG. , 6 is a diagram of a crushing pattern of a glass plate according to a comparative example, Figures 7 to 11 are diagrams of a crushing pattern of a heat-treated glass plate manufactured according to the present invention, and Figure 12 is a specific example of an apparatus for carrying out the present invention. Schematic diagrams related to examples, Figures 13 and 14 are cooling capacity characteristic diagrams of the method of the present invention, Figures 15 and 17 are explanatory diagrams for explaining the concept of the method of the present invention, and Figure 18 is a diagram showing the central tension of the glass plate. A schematic diagram of an apparatus for measuring stress; Figures 19 to 21 are explanatory diagrams showing the principle of measuring the central tensile stress of a glass plate;
FIG. 2 is an explanatory diagram showing stress measurement points. 1: Glass plate to be heat treated, 2: Roller hearth, 3:
Conveyance roll, 4: Glass plate heating device, 5: Cooling outlet.

Claims (1)

[Claims] 1. After passing a glass plate with a thickness of 5 mm or more and less than 10 mm through a heating furnace and heating it to 600°C to 660°C, the glass plate is taken out of the heating furnace and air-cooled. The cooling capacity is gradually increased over time, and the central tensile stress σt of this cooled glass plate is in the range of 85 to 200 kg/i, and the ratio of the surface compressive stress σC and the central tensile stress σt is σC/
A method for manufacturing a heat-treated glass plate, characterized in that σt is controlled to be in the range of 1.5 to 3.0. 2 Cooling capacity K (°C/sec) as shown below (a) over time. The method for producing a heat-treated glass plate according to claim 1, wherein the amount is gradually increased within the range shown by formulas (b) and (C). 0.1t-1,6≦≦0.6t (0≦t≦16.7,
K2O) B... (a) 0.1t-1,6≦≦10 (16,7≦t≦41
)・・・・・・(b) 2.5≦≦10 (t≧
41) ......(C) (Unit, K:
'C/sec, t: seconds) 3 In the case of a glass plate with a thickness of 5 u or more and 5.5 mm or less, the cooling capacity K ('C/sec) is calculated as shown in (d) below over time.
. 3. The method for manufacturing a heat-treated glass plate according to claim 2, wherein the amount is gradually increased within the range shown by formulas (e) and (f). 0.321-1.7≦≦0.6 t (0≦t≦16
．． 7, K2O)... (d) 0.321-1.7≦≦10 (16,7≦t≦30)
-(e) 7.9≦≦10 (t≧30)
......(f) (unit, K: 'C/sec, t:
(seconds) 4 For glass plates with a thickness of 5.5 mm or more and 7.5 mm or less, the cooling capacity K (°C/second) is calculated as shown below (g) over time. The method for producing a heat-treated glass plate according to claim 2, wherein the amount is gradually increased within the range shown by formulas (h) and (t). 0.21-2≦≦0.32t-1,7 (5≦t≦30
, K2O) (g) 0.32t = 1.7≦≦7.9 (30≦t≦3.7
) ・・・・・・(h) 5.4≦≦7.9
(t≧37) ・・・・・・(i) (unit,
K:'C/sec, t:sec) 5 In the case of a glass plate with a thickness of 7.5 mm or more and less than 1011t11L, the cooling capacity K ('C/sec) is calculated as follows (1), ( C), the second claim characterized in that the amount is gradually increased within the range shown by formula (n).
A method for producing a heat-treated glass plate as described in Section 1. 0.1 t-1, 6≦≦0.2t-2 (10≦t≦3
7, K2O)... (1) 0.11-1.6≦≦5.4 (37≦t≦41)
・・・・・・(c) 2.5≦≦5.4 (t
≧41) ・・・・・・(n) (Unit, K: 'C
/ second, t: second)