CN103269988B

CN103269988B - The manufacture method of glass substrate for plane display device

Info

Publication number: CN103269988B
Application number: CN201280003080.5A
Authority: CN
Inventors: 小山昭浩; 苅谷浩幸
Original assignee: Avanstrate Inc
Current assignee: Avanstrate Inc
Priority date: 2011-09-30
Filing date: 2012-09-26
Publication date: 2016-04-13
Anticipated expiration: 2032-09-26
Also published as: JPWO2013047585A1; JP5555373B2; TW201323355A; KR101476520B1; CN103269988A; TWI477459B; KR20130073910A; WO2013047585A1

Abstract

The invention provides a kind of method that manufacture is suitable for the glass substrate of LTPSTFT, the method uses the glass being suitable for light-weighted composition, can produce the glass substrate of the percent thermal shrinkage of the degree with the spacing deviation that can suppress pixel when not damaging productivity.Disclosed the present invention is the manufacture method of glass substrate for plane display device.The method comprises the following steps: (1) melts step, is less than 8 quality % and this glass substrate has the mode Blend Stocks of the strain point of more than 675 DEG C with the resultant of SrO and BaO in manufactured glass substrate, melts; (2) forming step, goes out glass ribbon by overflow downdraw by the melting glass ware forming melted; And (3) cooling step, with following condition (A), the shaping glass ribbon obtained is cooled, (A) average cooling rate from annealing point to the temperature of (strain point-50 DEG C): 0.5 DEG C/sec ~ be less than 5.5 DEG C/sec.

Description

The manufacture method of glass substrate for plane display device

Technical field

The present invention relates to glass substrate for plane display device.In more detail, the present invention relates to the manufacture method of low-temperature polysilicon film transistor (following, to be recited as LTPSTFT (Low-Temperature-Polycrystalline-SiliconThin-Film-Transis tor)) glass substrate for plane display device.And, the present invention relates to the manufacture method of transparent oxide semiconductor thin film transistor (following, to be recited as TOSTFT (TransparentOxide-SemiconductorThin-Film-Transistor)) glass substrate for plane display device.Say in further detail, the present invention relates to and form LTPS or TOS and the manufacture method of glass substrate that the flat-panel screens that manufactures uses at substrate surface.Say in further detail again, the present invention relates to the manufacture method that manufacture method that above-mentioned flat-panel monitor is the glass substrate for plane display device of liquid-crystal display and above-mentioned flat-panel monitor are the glass substrate for plane display device of organic EL (Electroluminescence, electroluminescent) indicating meter.

Background technology

For reducing the reasons such as power consumption, the indicating meter being equipped on the small machines such as portable unit is expected to apply LTPS in the manufacture of thin film transistor (TFT), but needs to heat-treat with the relatively-high temperature of 400 ~ 600 DEG C in the manufacture of LTPSTFT.On the other hand, in recent years high-precision refinement is more and more required to the indicating meter of small machines.Therefore, expect the spacing deviation (pitchshift) as far as possible suppressing pixel, suppression is carried out to the thermal contraction of glass substrate when causing the manufacture indicating meter of the spacing deviation of pixel and becomes problem.Further, in the glass substrate of TOSTFT, thermal contraction is suppressed to become problem too.

Report is had to point out, the percent thermal shrinkage of glass substrate reduces (Japanese Unexamined Patent Publication 2009-196879 publication: patent documentation 1, it is all recorded in this as especially openly quoting) by the speed of cooling reduced near annealing point when manufacturing glass substrate.And, report is had to point out, the percent thermal shrinkage of glass substrate also reduces (patent documentation 2: Japanese Unexamined Patent Publication 2011-20864 publication, it is all recorded in this as disclosing especially and quotes) by the speed of cooling near annealing point being set to when manufacturing glass substrate below the value that obtains with the form of the function of the annealing point with glass.

Summary of the invention

The problem that invention will solve

But as recorded in patent documentation 1, if excessively reduce the speed of cooling near annealing point in the manufacturing step of glass substrate, then producing apparatus gigantism, productivity is also deteriorated.In the method that patent documentation 2 is recorded, according to the annealing point controlled cooling model speed of glass.But in the method, productivity when fully reducing percent thermal shrinkage is not high.And then the glass composition of use itself is containing relatively many SrO and BaO, and the glass substrate obtained is that density is high and be unsuitable for the light-weighted glass of glass substrate.

Therefore, a kind of manufacture is the object of the present invention is to provide to be suitable for the method for the glass substrate of LTPSTFT, the method uses the glass being suitable for light-weighted composition, can produce the glass substrate having and the degree Hot Shrink of the spacing deviation of pixel can be suppressed to lead when not damaging productivity.And then object of the present invention is also to provide a kind of manufacture to have as the method for TOSTFT with the glass substrate of also suitable percent thermal shrinkage, and the method uses the glass being suitable for light-weighted composition, can manufacture too when not damaging productivity.

The technique means of dealing with problems

The present inventor finds by carrying out research to glass composition, can produce the glass substrate of the LTPSTFT with the following percent thermal shrinkage of regulation, thus complete the present invention when not damaging productivity.And then also find, above-mentioned glass substrate has the following percent thermal shrinkage of the regulation that also can be used as TOSTFT, thus completes the present invention.

The present invention is as described below.

[1] (the 1st mode of the present invention)

A manufacture method for glass substrate for plane display device, the method comprises:

(1) melt step, be in harmonious proportion raw material to make the resultant of SrO and BaO in manufactured glass substrate be less than 8 quality % and this glass substrate has the strain point of more than 675 DEG C, melt;

(2) forming step, goes out glass ribbon by overflow downdraw by the melting glass ware forming melted; And

(3) cooling step, cools the shaping glass ribbon obtained with following condition (A), (A) average cooling rate from annealing point to the temperature of (strain point-50 DEG C): 0.5 ~ be less than 5.5 DEG C/sec.

[2] as the manufacture method of the glass substrate for plane display device of [1], wherein, in melting step (1), Blend Stocks is to make (SiO in manufactured glass substrate ₂+ 2 × Al ₂o ₃)/B ₂o ₃the mol ratio of display more than 9.5.

[3] as the manufacture method of [1] or [2], wherein, for the glass substrate manufactured via cooling step (3), heat up with 10 DEG C/min from normal temperature, keep 1 hour at 550 DEG C, thereafter normal temperature is cooled to 10 DEG C/min, again with 10 DEG C/min of intensifications, keep 1 hour, after being cooled to normal temperature with 10 DEG C/min at 550 DEG C, the percent thermal shrinkage represented by following formula is below 75ppm

Percent thermal shrinkage (ppm)={ length of the glass before the shrinkage/thermal treatment of the glass before and after thermal treatment } × 10 ⁶.

[4] (the 2nd mode of the present invention)

(1) melt step, Blend Stocks is to make having (SiO in manufactured glass substrate ₂+ 2 × Al ₂o ₃)/B ₂o ₃be the mol ratio of more than 9.5, this glass substrate has the strain point of more than 680 DEG C not containing BaO in fact, melt;

(3) cooling step, cool the shaping glass ribbon obtained with following condition (A), (A) lights average cooling rate to the temperature of (strain point-50 DEG C) from being less than annealing: 0.5 ~ be less than 5.5 DEG C/sec.

The effect of invention

According to the present invention, the method producing when not damaging productivity and there is the LTPSTFT flat-panel monitor use of the following percent thermal shrinkage (being such as less than 75ppm) of regulation and the glass substrate of TOSTFT flat-panel monitor can be provided in.

Accompanying drawing explanation

Fig. 1 is the schematic schematic diagram (sectional view) of overflow downdraw shaped device.

Fig. 2 is the schematic schematic diagram (side-looking face) of overflow downdraw shaped device.

Fig. 3 is the figure of the temperature distribution of the specified altitude position representing glass ribbon.

Fig. 4 is the figure of the example of the speed of cooling of the glass ribbon representing embodiment 1 (speed of cooling is the example of 1 DEG C/sec).

Embodiment

The present invention relates to the manufacture method of the glass substrate for plane display devices such as LTPSTFT and TOSTFT.And, the glass substrate produced by manufacture method of the present invention can be used as the glass substrate of liquid-crystal display and OLED display, therefore, the present invention comprises the manufacture method of liquid crystal display glass substrate and the manufacture method of OLED display glass substrate.

The manufacture method of glass substrate for plane display device of the present invention includes following melting step (1), forming step (2) and cooling step (3).Below, be described for the manufacture method of LTPSTFT glass substrate for plane display device, but the manufacture method of TOSTFT glass substrate for plane display device also can similarly be implemented.Further, the manufacture method of liquid crystal display glass substrate and OLED display glass substrate also can similarly be implemented.

(1) step is melted

Melt in step (1), raw material is concocted by the mode meeting prescribed condition with manufactured glass substrate, and heating melts and clarifies, and preparation is available for shaping melting glass.The object of the invention is to manufacture the glass substrate with the following percent thermal shrinkage of regulation, and its object is to, even if with condition (A) to through shaping glass ribbon, the cooling carried out in following cooling step (3) also can produce such glass substrate.For this reason, raw material is concocted by the mode meeting prescribed condition with manufactured glass substrate, heating melts.

In 1st mode of the present invention, Blend Stocks is to make the resultant of SrO and BaO in manufactured glass substrate be less than 8 quality % and this glass substrate has the strain point of more than 675 DEG C.

SrO and BaO is the composition of the devitrification temperature that can reduce glass.Not required composition in glass substrate of the present invention, if but containing, devitrification resistance and meltability can be improved.But if content is too much, then density and thermal expansivity rise.If thermal expansivity rises, then cannot produce the glass substrate of the LTPSTFT flat-panel monitor with the following percent thermal shrinkage (being such as less than 75ppm) of regulation when not damaging productivity.Further, if density rises, then the lightweight of glass substrate cannot also be realized, not good enough for LTPSTFT purposes.Therefore, the resultant of SrO and BaO in manufactured glass substrate and SrO+BaO are set to are less than 8 quality %.SrO+BaO is preferably 0 ~ 7 quality %, be more preferably 0 ~ 5 quality %, and then be preferably the scope of 0 ~ 3 quality %, the more preferably scope of 0 ~ 1 quality %, especially when the density of glass substrate will be reduced, preferably in fact not containing SrO and BaO.

The strain point of manufactured glass substrate is more than 675 DEG C.If the strain point of glass substrate is low, then in heat treatment step (when manufacturing indicating meter), thermal contraction becomes large.The strain point of glass substrate of the present invention is preferably more than 680 DEG C, is more preferably more than 686 DEG C, and then is preferably more than 690 DEG C, more preferably more than 695 DEG C, is further preferably more than 700 DEG C.The strain point of glass substrate suitably can be selected according to the composition of glass substrate, will hereafter carry out describing about the glass composition that strain point can be set to more than 675 DEG C.In the present invention, by the strain point of manufactured glass substrate is set to more than 675 DEG C, the glass substrate that percent thermal shrinkage is little can be obtained.But the percent thermal shrinkage of glass substrate not only depends on strain point, also can change according to the cooling conditions in other characteristic or manufacturing step, especially cooling step.

In 2nd mode of the present invention, Blend Stocks is to make having (SiO in manufactured glass substrate ₂+ 2 × Al ₂o ₃)/B ₂o ₃be the mol ratio of more than 9.5, this glass substrate has the strain point of more than 680 DEG C not containing BaO in fact.

In any one of 1st mode of the present invention and the 2nd mode, manufactured glass substrate is by containing SiO ₂, Al ₂o ₃, B ₂o ₃glass form.In 1st mode of the present invention, preferably with the mol ratio (SiO in glass substrate ₂+ 2 × Al ₂o ₃)/B ₂o ₃be more than 9.5 mode concoct frit.Further, in the 2nd mode of the present invention, with the mol ratio (SiO in glass substrate ₂+ 2 × Al ₂o ₃)/B ₂o ₃be more than 9.5 mode concoct frit.Volatilize due to fractions in manufacturing processed and/or disperse, the composition of the frit thus concocted changes sometimes a little with the composition of the glass substrate manufactured.In the present invention, consider this volatile quantity during blending frit and disperse and the composition needed for glass substrate.In addition, as long as not specified in this specification sheets, then the content of glass ingredient and mol ratio refer to the value in glass or glass substrate.

SiO ₂with the Al of 2 times ₂o ₃resultant i.e. (SiO ₂+ 2 × Al ₂o ₃) relative to B ₂o ₃mol ratio (SiO ₂+ 2 × Al ₂o ₃)/B ₂o ₃become the index of high strain-point and devitrification resistance.If (SiO ₂+ 2 × Al ₂o ₃)/B ₂o ₃being less than 9.5, then fully cannot improving strain point, being difficult to produce when not damaging productivity the glass substrate of the LTPSTFT with the following percent thermal shrinkage (being such as less than 75ppm) of regulation.On the other hand, in order to fully reduce devitrification temperature to guarantee formability, (SiO ₂+ 2 × Al ₂o ₃)/B ₂o ₃be preferably less than 25.0, be more preferably less than 19.0.According to above situation, (SiO ₂+ 2 × Al ₂o ₃)/B ₂o ₃be preferably 9.5 ~ 25.0 scope, be more preferably the scope of 9.5 ~ 19.0, so preferably more than 9.5 ~ 17.0 scope, the more preferably scope of 10.0 ~ 15.5, be further preferably 11.0 ~ 15.0 scope.

For manufactured glass substrate, in the 1st mode of the present invention, preferably in fact not containing BaO.In 2nd mode of the present invention, in fact not containing BaO.Therefore, in this case, during blending frit, do not use compound containing Ba as frit.But in this specification sheets, what is called does not refer to containing BaO in fact and does not make BaO be contained in glass substrate consciously, is not precluded within the situation that in frit or manufacturing step, BaO contains as the impurity be inevitably mixed in glass.

As the composition of glass substrate manufactured in manufacture method of the present invention, the SiO containing 60 ~ 78mol% can be illustrated ₂, 3 ~ 20mol% Al ₂o ₃, 0.1 ~ 15mol% B ₂o ₃glass composition.Or the SiO that can illustrate containing 60 ~ 78mol% ₂, 3 ~ 20mol% Al ₂o ₃, 3 ~ 15mol% B ₂o ₃glass composition.This glass can further containing MgO, the CaO of 0 ~ 20mol% of 0 ~ 15mol%, the SrO of 0 ~ 10mol%, the ZnO of 0 ~ 5mol%, the K of 0 ~ 0.8mol% ₂the Fe of O, 0 ~ 0.1mol% ₂o ₃, other finings etc.Further, preferably in fact not containing SB ₂o ₃and in fact not containing As ₂o ₃.These aspects are general in above-mentioned 1st mode and the 2nd mode.

SiO ₂being the framework ingredient of glass, is therefore required composition.If content tails off, then have and cause the tendency that strain point reduces, thermal expansivity increases.Further, if SiO ₂content is very few, be then difficult to make glass substrate low density.On the other hand, if SiO ₂content is too much, then have melt temperature obviously to uprise and be difficult to the tendency that melts.If SiO ₂content is too much, then also have the tendency that devitrification resistance reduces, so there is the tendency of formability deteriorates.From this viewpoint, SiO ₂content be preferably set to the scope of 60 ~ 78mol%.SiO ₂content be more preferably 62 ~ 75mol%, and then be preferably 63 ~ 72mol%, the more preferably scope of 65 ~ 71mol%.

Al ₂o ₃it is the required composition improving strain point.If content is very few, then strain point reduces.And then, there is Young's modulus also to reduce, tendency that etch-rate also reduces.If Al ₂o ₃content is too much, then have the devitrification temperature of glass to rise and the tendency of formability deteriorates.From this viewpoint, Al ₂o ₃content be preferably the scope of 3 ~ 20mol%.Al ₂o ₃content be more preferably 5 ~ 18mol%, and then be preferably 5 ~ 15mol%, more preferably 7 ~ 14mol%, and then the scope of more preferably 10 ~ 14mol%.

B ₂o ₃reduce the required composition that the melt temperature of glass improves meltability.If B ₂o ₃content is very few, then have and cause the tendency that meltability reduces, devitrification resistance reduces and thermal expansivity increases.Further, if B ₂o ₃content is very few, be then difficult to realize low density.If B ₂o ₃content is too much, then cause the reduction of strain point and Young's modulus.From this viewpoint, B ₂o ₃content is preferably the scope of 0.1 ~ 15mol%, be more preferably the scope of 3 ~ 15mol%, and then be preferably 3 ~ 9.5mol%, more preferably 3 ~ be less than 8.9mol%, further be preferably 4 ~ be less than 8.9mol%, further be preferably 5 ~ 8.5mol%, then the scope of more preferably 6 ~ 8mol%.Further, from the view point of fully preventing devitrification, B ₂o ₃content is preferably the scope of 0.1 ~ 15mol%, is more preferably the scope of 3 ~ 15mol%, and then is preferably 5 ~ 13mol%, more preferably 5 ~ 12mol%, is further preferably 6 ~ is less than the scope of 10mol%.

MgO is the composition improving meltability.Further, it is the composition being difficult to increase density in alkaline-earth metal, if so relatively increase its content, then easily realize low density.It is also nonessential, but can improve meltability by containing.But, if the content of MgO is too much, then because the devitrification temperature of glass sharply rises so formability deteriorates.Especially when devitrification temperature will be reduced, preferably in fact not containing MgO.From this viewpoint, content of MgO is preferably 0 ~ 15mol%, be more preferably 0 ~ 10mol%, and then be preferably 0 ~ 5mol%, more preferably 0 ~ be less than 2mol%, be further preferably 0 ~ 1.5mol%, and then more preferably 0 ~ 1mol%, more preferably 0 ~ 0.5mol% again, so more more preferably 0 ~ be less than 0.2mol%, most preferably be and do not contain in fact.

CaO is to effective composition in the devitrification temperature that sharply can not promote glass improving the meltability of glass.Further, it is the composition being difficult to increase density in alkaline-earth metal, if so relatively increase its content, then easily realize low density.If content is very few, then has and cause meltability to reduce and the tendency causing increased devitrification resistance to reduce that rises due to devitrification temperature due to melt temperature rising.If CaO content is too much, then has and cause the tendency that thermal expansivity increases and density rises.CaO content is preferably 0 ~ 20mol%, is more preferably 3.6 ~ 16mol%, and then is preferably 4 ~ 16mol%, more preferably 6 ~ 16mol%, further be preferably greater than 7 ~ 16mol%, and then more preferably 8 ~ 15mol%, then the scope of more preferably 9 ~ 13mol%.

SrO is the composition that can reduce devitrification temperature.SrO is also nonessential, if but containing, devitrification resistance improves, and then meltability also improves.If SrO content is too much, then density rises.SrO content is preferably 0 ~ 10mol%, is more preferably 0 ~ 5mol%, and then is preferably 0 ~ 3mol%, more preferably 0 ~ 2mol%, further be preferably 0 ~ 1mol%, and then more preferably 0 ~ be less than 0.5mol%, more more preferably 0 ~ be less than the scope of 0.1mol%.When reducing the density of glass, preferably in fact not containing SrO.

BaO is the composition that can reduce devitrification temperature.BaO is also nonessential, if but containing, devitrification resistance improves, and meltability also improves.Further, if BaO content is too much, then density is caused to rise and thermal expansivity increase.BaO content is preferably 0 ~ 10mol%, is more preferably 0 ~ is less than 5mol%, and then is preferably 0 ~ 3mol%, more preferably 0 ~ 2mol%, is further preferably the scope of 0 ~ 1mol%.In addition, from the problem of environmental pressure, preferably in fact not containing BaO.

Li ₂o and Na ₂o is the composition improving meltability, but its thermal expansivity likely melting out from glass substrate and make TFT deterioration in characteristics or increase glass.Li ₂o and Na ₂the content of O is preferably 0 ~ 0.5mol%, is more preferably 0 ~ 0.1mol%, and then is preferably 0 ~ 0.01mol%, further preferably in fact all not containing Li ₂o and Na ₂o.

K ₂o is the basicity of raising glass and promotes clarification composition.Further, it reduces ratio resistance and reduces melting temperature (Tm) and improve the composition of meltability.Though and nonessential, if containing; clarification raising, meltability would also improve.If K ₂o content is too much, then likely melt out from glass substrate and make TFT deterioration in characteristics.Further, thermal expansivity also has the tendency of increase.K ₂o content is preferably 0 ~ 0.8mol%, is more preferably 0.01 ~ 0.5mol%, and then is preferably the scope of 0.1 ~ 0.3mol%.

The glass substrate obtained by manufacture method of the present invention can comprise finings.As finings, SnO ₂suitable.If SnO ₂content very few, then bubble quality variation.If SnO ₂content too much, then easily produce devitrification.SnO ₂content be preferably set to the scope of 0.01 ~ 0.2mol%, be more preferably 0.03 ~ 0.15mol%, and then be preferably the scope of 0.05 ~ 0.12mol%.

Fe ₂o ₃it is the composition of the ratio resistance reducing glass except the effect had as finings.Viscosity in high-temperature area is high and be difficult in the glass melted, preferably containing Fe ₂o ₃to reduce the ratio resistance of glass.But, if Fe ₂o ₃content is too much, then glass coloring, and transmitance reduces.Therefore, Fe ₂o ₃content is the scope of 0 ~ 0.1mol%, is preferably 0 ~ 0.05mol%, is more preferably 0.001 ~ 0.05mol%, and then is preferably 0.005 ~ 0.05mol%, the more preferably scope of 0.005 ~ 0.02mol%.

Consider the problem of environmental pressure, the glass substrate obtained by manufacture method of the present invention is not preferably in fact containing As ₂o ₃.In glass substrate of the present invention, consider the problem of environmental pressure, SB ₂o ₃be preferably 0 ~ 0.5mol%, be more preferably 0 ~ 0.1mol%, most preferably in fact not containing SB ₂o ₃.

In addition, in this specification sheets, so-called " in fact not containing " refers to the material not using the raw material becoming this composition in above-mentioned frit, and is not precluded within the composition that contains with Impure forms in the frit of other composition and melts out being mixed into of composition to glass by manufacturing installation.

If from SiO ₂content in deduct Al ₂o ₃content 1/2 difference (SiO ₂-Al ₂o ₃/ 2) value is too small, though then can improve etch-rate, likely reduces devitrification resistance.If this value is too high, then likely reduce etch-rate.From this viewpoint, (SiO ₂-Al ₂o ₃/ 2) be preferably below 66mol%, be more preferably 50 ~ 66mol%, and then be preferably 56 ~ 64mol%, more preferably 57 ~ 63mol%, be further preferably 58 ~ 62mol%.

If SiO ₂with Al ₂o ₃resultant and SiO ₂+ Al ₂o ₃very few, then there is the tendency that strain point reduces, if too much, then have the tendency that devitrification resistance is deteriorated.Therefore, SiO ₂+ Al ₂o ₃be preferably more than 75mol%, be more preferably 76 ~ 88mol%, and then be preferably 77 ~ 85mol%, more preferably 78 ~ 82mol%.

If B ₂o ₃with P ₂o ₅resultant and B ₂o ₃+ P ₂o ₅very few, then there is the tendency that meltability reduces, if too much, then due to B ₂o ₃+ P ₂o ₅volatilization and cause the heterogeneity apparition of glass, easily produce striped.And then, there is the tendency that strain point reduces.Therefore, B ₂o ₃+ P ₂o ₅be preferably 0.1 ~ 15mol%, be more preferably 3 ~ 15mol%, and then be preferably 3 ~ 9.5mol%, more preferably 4 ~ 9mol%, be further preferably 5 ~ 9mol%, and then more preferably 6 ~ 8mol%.Further, from the view point of fully preventing devitrification, B ₂o ₃+ P ₂o ₅be preferably the scope of 0.1 ~ 15mol%, be more preferably 3 ~ 15mol%, and then be preferably 5 ~ 13mol%, more preferably 5 ~ 12mol%, be further preferably 6 ~ be less than the scope of 10mol%.

Improve meltability while reducing from the view point of preventing strain point, CaO is relative to B ₂o ₃mol ratio CaO/B ₂o ₃be preferably more than 0.5, be more preferably more than 0.9, and then preferably more than 1.2, the scope more preferably more than 1.2 ~ 5, then the scope more preferably more than 1.2 ~ 3, be further preferably the scope of 1.3 ~ 2.5, most preferably be the scope of 1.3 ~ 2.Further, from the view point of fully improving meltability, being preferably 0.5 ~ 5, being more preferably 0.9 ~ 3, and then preferably more than 1 ~ 2.5, more preferably more than 1.2 ~ 2, further preferably more than 1.2 ~ 1.5 scope.

Mol ratio CaO/RO becomes the index of meltability and devitrification resistance.CaO/RO is preferably 0.5 ~ 1, is more preferably 0.7 ~ 1, and then preferably more than 0.85 ~ 1, and more preferably 0.88 ~ 1, be further preferably the scope of 0.90 ~ 1, and then more preferably 0.92 ~ 1, most preferably be 0.95 ~ 1.By being set to above-mentioned scope, devitrification resistance and meltability can be taken into account.And then can low density be realized.

If RO, ZnO and B ₂o ₃resultant and RO+ZnO+B ₂o ₃very few, then there is the tendency that meltability reduces.On the other hand, if too much, then there is the tendency that strain point reduces.Therefore, RO+ZnO+B ₂o ₃be preferably 7 ~ 30%, be more preferably 7 ~ be less than 25mol%, be more preferably 10 ~ 23mol%, and then be preferably 12 ~ 22mol%, more preferably 14 ~ 21mol%, be further preferably the scope of 16 ~ 21mol%.Further, from the view point of fully improving meltability, being preferably 7 ~ 30%, but being more preferably 12 ~ 27%, being more preferably 14 ~ 25mol%, and then be preferably the scope of 17 ~ 23mol%.

RO is relative to SiO ₂with Al ₂o ₃resultant (SiO ₂+ Al ₂o ₃) mol ratio RO/ (SiO ₂+ Al ₂o ₃) become the index of strain point and meltability.From the view point of taking into account high strain-point and meltability, also taking into account the high strain-point of glass and the reduction of ratio resistance, be preferably the scope of 0.07 ~ 0.2, be more preferably 0.08 ~ 0.18, and then be preferably 0.13 ~ 0.18, the more preferably scope of 0.13 ~ 0.16.

Li ₂o, Na ₂o and K ₂the resultant of O and R ₂o be improve glass basicity, easily carry out finings oxidation thus given play to clarification composition.Further, it is the composition reducing ratio resistance and melting temperature (Tm) thus improve meltability.R ₂o is also nonessential, if but containing, improve bubble quality and meltability.But, if R ₂o content is too much, then have the tendency that thermal expansivity increases.R ₂o is preferably 0 ~ 0.8mol%, is more preferably 0.01 ~ 0.5mol%, and then is preferably 0.1 ~ 0.3mol%.

K ₂o and Li ₂o or Na ₂it is large that O compares molecular weight, so be difficult to melt out from glass substrate.Therefore, containing R ₂when O, preferably containing K ₂o.That is, preferred K ₂the mol% content > Li of O ₂the mol% content of O and/or K ₂the mol% content > N of O ₂the mol% content of O.If Li ₂o and Na ₂the ratio of O is large, then melt out from glass substrate and make the possibility of TFT deterioration in characteristics become large.Mol ratio K ₂o/R ₂o is preferably 0.3 ~ 1, is more preferably 0.5 ~ 1, and then is preferably 0.8 ~ 1, the more preferably scope of 0.9 ~ 1.

The resultant of MgO, CaO, SrO and BaO and RO are the compositions improving meltability.If RO content is very few, then meltability is deteriorated.If RO content is too much, then has and cause the tendency that strain point reduces, density rises and Young's modulus reduces.Further, if RO content is too much, then the tendency that thermal expansivity increases also is had.From this viewpoint, RO is preferably the scope of 3 ~ 25mol%, be preferably 4 ~ 16mol%, be more preferably 4 ~ 15mol%, and then be preferably 5 ~ be less than the scope of 14mol%, the more preferably scope of 6 ~ 14mol%, is further preferably the scope of 8 ~ 13mol%, and then the scope of more preferably 9 ~ 12mol%.

The devitrification temperature of glass substrate of the present invention is preferably less than 1270 DEG C, is more preferably less than 1260 DEG C, and then is preferably less than 1250 DEG C, more preferably less than 1200 DEG C.If devitrification temperature is less than 1270 DEG C, then glass tube down-drawing is easily utilized to carry out the shaping of sheet glass.If devitrification temperature is too high, then easily produces devitrification and cannot glass tube down-drawing be applicable to.

The mean thermal expansion coefficients (100 ~ 300 DEG C) of glass substrate of the present invention is preferably less than 55 × 10 ^-7dEG C ^-1, be more preferably 28 × 10 ^-7dEG C ^-1~ be less than 40 × 10 ^-7dEG C ^-1, and then be preferably 30 × 10 ^-7dEG C ^-1~ be less than 39 × 10 ^-7dEG C ^-1, more preferably 32 × 10 ^-7dEG C ^-1~ be less than 38 × 10 ^-7dEG C ^-1, be further preferably 34 × 10 ^-7dEG C ^-1~ be less than 38 × 10 ^-7dEG C ^-1scope.Further, from the view point of reducing percent thermal shrinkage further, preferably 37 × 10 are less than ^-7dEG C ^-1, be more preferably 28 × 10 ^-7dEG C ^-1~ be less than 36 × 10 ^-7dEG C ^-1, and then be preferably 30 × 10 ^-7dEG C ^-1~ be less than 36 × 10 ^-7dEG C ^-1, more preferably 31 × 10 ^-7dEG C ^-1~ 35 × 10 ^-7dEG C ^-1, be further preferably 32 × 10 ^-7dEG C ^-1~ be less than 35 × 10 ^-7dEG C ^-1scope.If thermal expansivity is large, then there is the tendency that percent thermal shrinkage increases.On the other hand, if thermal expansivity is little, then exists and be difficult to obtain mating thus causing the situation that circumferential component is peeled off of the periphery material such as the metal be formed on glass substrate, organic system binding agent and thermal expansivity.By thermal expansivity is set to above-mentioned scope, the thermal stresses produced by thermal expansion difference can be reduced.

The percent thermal shrinkage of glass substrate of the present invention is preferably below 75ppm, is more preferably below 60ppm, and then is preferably below 55ppm, more preferably below 50ppm, further be preferably below 48ppm, and then be more preferably less than 45ppm, more more preferably below 43ppm.If percent thermal shrinkage (amount) is excessive, then causes the larger spacing deviation of pixel and the indicating meter of fine cannot be realized.In order to percent thermal shrinkage (amount) is controlled in specialized range, preferably the strain point of glass substrate is set to more than 675 DEG C.In addition, if make percent thermal shrinkage be 0ppm, then must do one's utmost the speed of cooling reducing cooling step (such as the 2nd cooling step), or thermal contraction is differently set with cooling step described later reduces treatment step.Specifically, reducing treatment step by arranging thermal contraction after cut-out step described later, percent thermal shrinkage (off-line annealing) can be reduced.But, reduce speed of cooling if do one's utmost or thermal contraction is differently set with cooling step and reduce treatment step, then cause productivity to reduce, cost increase.If the productivity of considering and cost, then percent thermal shrinkage is preferably 5 ~ 75ppm, be more preferably 5 ~ 60ppm, and then be preferably 8 ~ 55ppm, more preferably 8 ~ 50ppm, further be preferably 10 ~ 48ppm, and then more preferably 10 ~ be less than 45ppm, more more preferably 15 ~ 43ppm.

In addition, for percent thermal shrinkage, be 10 DEG C/min at enforcement twice warming and cooling rate and represent with following formula after 550 DEG C of maintenances thermal treatment of 1 hour.More specifically, heat up with 10 DEG C/min from normal temperature, keep 1 hour at 550 DEG C, thereafter, be cooled to normal temperature with 10 DEG C/min, again with 10 DEG C/min of intensifications, keep 1 hour at 550 DEG C, be cooled to normal temperature with 10 DEG C/min.

Percent thermal shrinkage (ppm)={ length of the glass before the shrinkage/thermal treatment of the glass before and after thermal treatment } × 10 ⁶

The density of glass substrate of the present invention is preferably 2.6g/cm ³below, 2.5g/cm is more preferably ³below, so be preferably 2.45g/cm ³below, more preferably 2.42g/cm ³below.If density is too high, then the lightweight of glass substrate becomes difficulty, also can not realize the lightweight of indicating meter.

If the Tg step-down of glass, then there is in the heat treatment step when manufacturing indicating meter the tendency easily producing thermal contraction.The Tg of glass substrate of the present invention is preferably more than 720 DEG C, is more preferably more than 730 DEG C, and then is preferably more than 740 DEG C, more preferably more than 750 DEG C.In order to the Tg of glass substrate is set to above-mentioned scope, in the compositing range of glass substrate of the present invention, increase the such as SiO improving Tg ₂and Al ₂o ₃suitable Deng composition.

The temperature (melt temperature) of the display viscosity (100dPas) of glass melting liquid of the present invention is preferably less than 1750 DEG C, be more preferably the scope of 1600 ~ 1750 DEG C, and then be preferably 1620 ~ 1730 DEG C, the more preferably scope of 1650 ~ 1720 DEG C.The easy step-down of strain point of the glass that melt temperature is low.In order to improve strain point, also melt temperature must be improved to a certain extent.But, if melting temperature (Tm) uprises, then the burden melting groove is become large.Further, owing to using the energy in a large number, so cost also uprises.In order to the melting of glass is set to above-mentioned scope, containing falling low viscous such as B in the compositing range of glass substrate of the present invention ₂o ₃, the composition such as RO is suitable.

The ratio resistance (when 1550 DEG C) of melten glass of the present invention is preferably 50 ~ 300 Ω cm, is more preferably 50 ~ 250 Ω cm, and then is preferably 50 ~ 200 Ω cm, the more preferably scope of 100 ~ 200 Ω cm.If ratio resistance is too small, then melt required current value excessive and likely occur the restriction on equipment.If the ratio resistance of melten glass is excessive, then there is electric current not flowing but forming flowing in the heat resisting brick melting groove thus causing melting the possibility of groove melting loss in glass.The ratio resistance of melten glass is mainly by control RO, K ₂o and Fe ₂o ₃content and be adjusted to above-mentioned scope.

The liquid phase viscosity of glass of the present invention is preferably 30, more than 000dPas, is more preferably 40, more than 000dPas, and then is preferably the scope of 50, more than 000dPas.Be difficult to produce devitrification crystal, so easily utilize overflow downdraw formed glass substrate when shaping by being in above-mentioned scope.

The Young's modulus of glass substrate of the present invention is preferably more than 70GPa, is more preferably more than 73GPa, and then is preferably more than 74GPa, more preferably more than 75GPa.If Young's modulus (GPa) is little, then easily make glass breakage due to the flexure because of the glass caused by glass deadweight.For the Young's modulus (GPa) of glass substrate, make by increasing in the compositing range of glass substrate of the present invention the such as Al that the tendency of Young's modulus (GPa) change is stronger ₂o ₃deng content increase the Young's modulus (GPa) of glass substrate.

The ratio Young's modulus (Young's modulus/density) of glass substrate of the present invention is preferably more than 28, is more preferably more than 29, and then is preferably more than 30, and more preferably more than 31.If less than Young's modulus, then easily make glass breakage due to the flexure because of the glass caused by glass deadweight.

(2) forming step

In forming step (2), to be melted and the melting glass ware forming clarified goes out glass ribbon by through heating by overflow downdraw.The method of overflow downdraw itself is known method.Overflow downdraw such as can refer to the publications such as Japanese Unexamined Patent Publication 2009-298665 publication, Japanese Unexamined Patent Publication 2010-215428 publication, Japanese Unexamined Patent Publication 2011-168494 publication, and it is all recorded in this as especially openly quoting.The explanatory view of the device used in overflow downdraw is shown in Fig. 1 and Fig. 2.

Fig. 1 and Fig. 2 represents the schematic formation of the shaped device 40 used in overflow downdraw.Fig. 1 is the sectional view of shaped device 40.Fig. 2 is the side-looking face of shaped device 40.

Shaped device 40 comprises the passage that glass ribbon GR passes through and the space surrounding passage.The space surrounding passage is made up of overflow chamber 20, shaping chamber 30 and cooling chamber 80.

Shaped device 40 is formed primarily of formed body 41, distance member 50, cooling roller 51, temperature adjustment unit 60, lower withdrawing roll 81a ~ 81d, well heater 82a ~ 82h and shut-off device 90.And then shaped device 40 possesses control device (not shown).Overflow chamber 20 is the spaces making the melten glass transported from clarifying plant (not shown) be shaped to glass ribbon GR.By adopting overflow downdraw without the need to the grinding steps of the glass baseplate surface after shaping.

(3) cooling step

In cooling step (3), with following condition (A), glass ribbon shaping in forming step is cooled.

(A) annealing point is to the average cooling rate of the temperature of (strain point-50 DEG C): 0.5 ~ be less than 5.5 DEG C/sec

The glass ribbon one formed extends one side cooling downwards.Be known about the extension of glass ribbon and the usual method of cooling and condition.In method of the present invention, use the online annealing that the glass ribbon formed in overflow shaped device is directly cooled, and then cut off, manufacture sheet glass.

Shaping chamber 30 be configured at overflow chamber 20 below and be used for adjusting the thickness of glass ribbon GR and the space of amount of warpage.In shaping chamber 30, implement a part of the 1st cooling step S41 described later.Specifically, in shaping chamber 30, the upstream region of glass ribbon GR is cooled.The upstream region of so-called glass ribbon GR is the region of temperature higher than the glass ribbon GR of annealing point of the central part C of glass ribbon GR.The central part C of glass ribbon GR is the width center of glass ribbon GR.Temperature province till the temperature that upstream region comprises the central part C of glass ribbon GR reaches near annealing point.After glass ribbon GR is interior by shaping chamber 30, by cooling chamber 80 described later.

Cooling chamber 80 shown in Fig. 1 and 2 be configured at overflow chamber 20 and shaping chamber 30 below and be used for the space of the dependent variable adjusting glass ribbon GR.In overflow chamber 20, implement a part of following 1st cooling step S41, the 2nd cooling step S42 and the 3rd cooling step S43.Specifically, in cooling chamber 80, have passed the annealed point of glass ribbon GR, the strain point in shaping chamber 30, be cooled to the temperature of near room temperature.In addition, the inside of cooling chamber 80 is divided into a plurality of space by heat insulating member 80b.

The cooling step of glass ribbon comprises: the 1st cooling step, and will be formed in overflow shaped device about 1,100 DEG C ~ 1, the glass ribbon cools of 250 DEG C is to exceeding annealing point; 2nd cooling step, till the temperature being cooled to (strain point-50 DEG C) is lighted in self-annealing; And the 3rd cooling step, be cooled to the temperature near (strain point-200 DEG C) from being less than the temperature of (strain point-50 DEG C) till.And then in the present invention, the average cooling rate of glass ribbon central part in the 2nd cooling step is set to 0.5 ~ be less than 5.5 DEG C/sec (condition A).By the average cooling rate of glass ribbon central part in the 2nd cooling step is set to above-mentioned scope, the glass substrate that percent thermal shrinkage reduces can be obtained when not damaging productivity.In addition, in this specification sheets, as long as the speed of cooling of glass ribbon is not recorded especially, then refer to the average cooling rate of the central part of glass ribbon.More specifically, can refer to No. 2012-525566, Japanese Patent Application etc., whole records are wherein in this as especially openly quoting.In addition, in this specification sheets, (strain point-50 DEG C) refers to the temperature of lower than strain point 50 DEG C, and (strain point-200 DEG C) refers to the temperature of lower than strain point 200 DEG C.

Manufacture method of the present invention in the cooling step of shaping glass ribbon, also preferred with following condition (B) and (C) cooled glass band except meeting above-mentioned condition (A).

(B) average cooling rate till the temperature of shaping in forming step (2) glass ribbon reaches annealing point: more than 5.5 DEG C/sec;

(C) average cooling rate till the temperature of glass ribbon reaches annealing point in above-mentioned (B) is faster from the average cooling rate be less than above-mentioned (strain point-50 DEG C) to (strain point-200 DEG C) than the temperature of above-mentioned glass ribbon.

Manufacture method of the present invention in the cooling step of shaping glass ribbon, except meeting above-mentioned condition (A) or (A) ~ (C), also can satisfy condition (D).(D) average cooling rate lighted to (strain point-50 DEG C) than the temperature self-annealing of above-mentioned glass ribbon from the average cooling rate be less than above-mentioned (strain point-50 DEG C) to above-mentioned (strain point-200 DEG C) of the temperature of above-mentioned glass ribbon is fast.

Condition (B) is the cooling conditions in the 1st cooling step till the temperature of glass ribbon reaches annealing point, and the average cooling rate of glass ribbon central part shaping in forming step is set to more than 5.5 DEG C/sec.In 1st cooling step, the average cooling rate of glass ribbon central part is preferably 5.5 DEG C/sec ~ 50.0 DEG C/sec, is more preferably 8.0 DEG C/sec ~ 16.5 DEG C/sec.If the average cooling rate of glass ribbon central part is less than 5.5 DEG C/sec in the 1st cooling step, then productivity reduces.On the other hand, if the average cooling rate of glass ribbon central part is more than 50.0 DEG C/sec in the 1st cooling step, then the temperature being difficult to carry out in order to the width of the glass ribbon suppressing plane strain or warpage to be carried out controls.Further, the 1st edge part speed of cooling in the 1st cooling step S41 is preferably 5.5 DEG C/sec ~ 52.0 DEG C/sec, is more preferably 8.3 DEG C/sec ~ 17.5 DEG C/sec.Further, in the 1st cooling step the average cooling rate of glass ribbon central part preferably faster than the average cooling rate of glass ribbon central part in the 2nd cooling step and the 3rd cooling step.Condition (C) is the average cooling rate in the 1st cooling step till the temperature of glass ribbon reaches annealing point faster than the temperature of glass ribbon from the average cooling rate be less than in the 3rd cooling step above-mentioned (strain point-50 DEG C) to (strain point-200 DEG C).By setting like this, the temperature controlled precision of the width of glass ribbon can be improved.

Condition (A) is the cooling conditions of the glass ribbon in the 2nd cooling step, annealing point to the average cooling rate of the glass ribbon central part of the temperature of (strain point-50 DEG C) is 0.5 ~ be less than 5.5 DEG C/sec, be preferably 1.0 DEG C/sec ~ 5.5 DEG C/sec, be more preferably 1.5 DEG C/sec ~ 5.0 DEG C/sec.If the average cooling rate of glass ribbon central part is less than 0.5 DEG C/sec in the 2nd cooling step, then producing apparatus gigantism and cause productivity to reduce.On the other hand, if more than 5.5 DEG C/sec, then fully percent thermal shrinkage cannot be reduced.Further, the edge part speed of cooling in the 2nd cooling step is preferably 0.3 DEG C/sec ~ 5.3 DEG C/sec, is more preferably 0.8 DEG C/sec ~ 2.8 DEG C/sec.Further, in the 2nd cooling step, the average cooling rate of glass ribbon central part is preferably slower than the average cooling rate of glass ribbon central part in the 1st cooling step.

In the present invention, to the speed of cooling of glass ribbon central part in the 3rd cooling step, there is no particular restriction, is preferably 1.5 DEG C/sec ~ 7.0 DEG C/sec, is more preferably 2.0 DEG C/sec ~ 5.5 DEG C/sec.If the speed of cooling of glass ribbon central part is less than 1.5 DEG C/sec in the 3rd cooling step, productivity reduces.On the other hand, if more than 7.0 DEG C/sec, then there is the possibility that glass ribbon breaks because of glass quenching.Further, in the 3rd cooling step S43, edge part speed of cooling is preferably 1.3 DEG C/sec ~ 6.8 DEG C/sec, is more preferably 1.5 DEG C/sec ~ 5.0 DEG C/sec.

Further, in the 3rd cooling step, the average cooling rate of glass ribbon central part can faster than the average cooling rate of glass ribbon central part in the 2nd cooling step.Condition (D) is the average cooling rate of temperature in the 2nd cooling step that the average cooling rate be less than in the 3rd cooling step above-mentioned (strain point-50 DEG C) to above-mentioned (strain point-200 DEG C) to be lighted faster than the temperature self-annealing of above-mentioned glass ribbon to (strain point-50 DEG C) of glass ribbon.By setting like this, the temperature controlled precision of the width of glass ribbon sometimes can be improved further.But, even if the temperature of glass ribbon lights the average cooling rate in the 2nd cooling step to (strain point-50 DEG C) from the temperature self-annealing that the average cooling rate be less than in the 3rd cooling step above-mentioned (strain point-50 DEG C) to above-mentioned (strain point-200 DEG C) is slower than above-mentioned glass ribbon, as long as meet above-mentioned condition (A) to (C), then also can carry out the temperature control of the width of glass ribbon with required precision.By satisfying condition, (D) can improve its precision further.

That is, in aforesaid way, preferably in three cooling step S41 ~ S43 contained by the cooling step S4 of glass ribbon GR at least in cooling step S41 and S42 with different speed of cooling cooling plate-like glass SG.No matter which one is comparatively fast for the speed of cooling of cooling step S42 and S43.Specifically, the speed of cooling of the 1st cooling step S41 in three cooling step S41 ~ S43 is the fastest, the speed of cooling of the 2nd cooling step S42 and the speed of cooling of the 3rd cooling step S43 no matter which one are very fast or be identical speed, all can improve the temperature controlled precision of temperature control, the especially width of glass ribbon while maintaining higher productivity.

Below, with reference to Fig. 3 and Fig. 4, the temperature treatment of the glass ribbon GR in each cooling step S41 ~ S43 is described in detail.Fig. 3 represents the temperature distribution of the specified altitude position of glass ribbon GR.Fig. 4 represents the speed of cooling of the glass ribbon GR (0.7mm) manufactured in the embodiment 1 of satisfy condition (D).

(3-1) the 1st cooling step

The melten glass at interflow immediately below formed body 41 is cooled to the step of the temperature near annealing point by the 1st cooling step S41.Specifically, in the 1st cooling step, the glass ribbon GR of about 1,100 DEG C ~ 1,250 DEG C is cooled to the temperature (with reference to Fig. 4) near annealing point.Herein, annealing point is viscosity is 10 ¹³temperature during dPas.

In 1st cooling step S41, carry out the temperature treatment of glass ribbon GR based on the 1st temperature distribution TP1 ~ the 4th temperature distribution TP4.1st cooling step comprises: the 1st temperature controlling step, with the temperature of the end of the width of glass ribbon GR lower than the temperature of the middle section CA clamped by end and the temperature of middle section CA becomes uniform mode carries out; And the 2nd temperature controlling step, after carrying out the 1st temperature controlling step, carry out towards the mode of end step-down from central part with the temperature of the width of glass ribbon GR.Herein, the temperature of so-called middle section CA becomes and evenly refers to that the temperature of middle section CA is contained in the temperature province of regulation.The temperature province of so-called regulation is the scope of reference temperature ± 20 DEG C.Reference temperature is the medial temperature of the width of middle section CA.The temperature of the width of so-called glass ribbon GR refers to towards end step-down and form gradient (thermograde) in the temperature of central part C and the temperature of edge part R, L from central part.In addition, herein, so-called thermograde is the value that deducts the temperature gained of edge part R, L from the temperature of central part C divided by the width W (such as 1650mm, with reference to Fig. 3) of glass ribbon GR divided by the value ((temperature of the temperature of central part C-edge part R, L)/(width W/2 of plate glass)) after the value of 2 gained.

The 1st temperature distribution TP1 shown in Fig. 3 realizes by being controlled to cooling roller 51 in die cavity room 30 and temperature adjustment unit 60.Specifically, by edge part R, L of cooling roller 51 cooled glass band GR.For the temperature of edge part R, L of glass ribbon GR, be cooled to the temperature compared with the low specified temperature of the temperature of middle section CA (such as 200 DEG C ~ 250 DEG C).For the 1st temperature distribution TP1, carry out quenching by opposite side edge and suppress glass ribbon GR to shrink on width, thus make the thickness of slab of glass ribbon GR even.

2nd temperature distribution TP2 and the 3rd temperature distribution TP3 realizes by being controlled to temperature adjustment unit 60 in die cavity room 30.Specifically, by edge part R, L of cooling unit 64,65 cooled glass band GR, by the middle section CA of cooling unit 62,63 cooling plate-like glass.By carrying out this cooling, constantly can apply tension force at the central part of glass ribbon GR, the warpage of glass ribbon GR can be suppressed.

In addition, the 4th temperature distribution TP4 is realized by the well heater 82a in controlled cooling model chamber 80.By making the thermograde TG4 in the 4th temperature distribution TP4 be less than thermograde TG3 in the 3rd temperature distribution TP3 of upstream, constantly can apply tension force at the central part of glass ribbon GR, the warpage of glass ribbon GR can be suppressed.

(3-2) the 2nd cooling step

2nd cooling step S42 is the step (with reference to Fig. 4) be cooled to by the glass ribbon GR of the temperature reached near annealing point near strain point-50 DEG C.Herein, strain point is the viscosity of glass is 10 ^14.5the temperature of dPas.

In 2nd cooling step S42, carry out the temperature treatment of glass ribbon GR based on the 5th temperature distribution TP5 and the 6th temperature distribution TP6.2nd cooling step comprises the 3rd temperature controlling step, and the 3rd temperature controlling step is with along with near the strain point of glass, and the mode that the end of the width of above-mentioned plate glass and the thermograde of central part reduce is carried out.

5th temperature distribution TP5 is realized by the well heater 82b in controlled cooling model chamber 80.By making the thermograde TG5 in the 5th temperature distribution TP5 be less than thermograde TG4 in the 4th temperature distribution TP4 of upstream, constantly can apply tension force at the central part of glass ribbon GR, the warpage of glass ribbon GR can be suppressed.

In 6th temperature distribution TP6, the temperature of the width of glass ribbon GR (edge part R, L of width are to the temperature of central part C) evenly.In other words, 6th temperature distribution TP6 is following temperature distribution: on the width of glass ribbon GR, the thermograde of the temperature of edge part R, L periphery and the temperature of central part C periphery is minimum, and the temperature of edge part R, L periphery and the temperature of central part C periphery are same degree.

Herein, what is called evenly refers to that the temperature of edge part R, L periphery and the temperature of central part C periphery are contained in the temperature province of regulation.The temperature province of so-called regulation is the scope of reference temperature ± 5 DEG C.Reference temperature is the medial temperature of the width of glass ribbon GR.

In addition, the 6th temperature distribution TP6 is realized by the well heater 82c in controlled cooling model chamber 80.Further, the 6th temperature distribution TP6 realizes near strain point.Herein, the temperature province of the regulation comprising strain point is referred near so-called strain point.The temperature province of so-called regulation is the region from " (annealing point+strain point)/2 " to " strain point-50 DEG C ".6th temperature distribution TP6 is that more at least (place of flow direction) near strain point realizes.

(3-3) the 3rd cooling step

3rd cooling step S43 is the step (with reference to Fig. 4) the glass ribbon GR of the temperature reached near strain point-50 DEG C being cooled to the temperature near strain point-200 DEG C.

In 3rd cooling step S43, carry out the temperature treatment of glass ribbon GR based on the 7th temperature distribution TP7 ~ the 10th temperature distribution TP10.3rd cooling step comprises the 4th temperature controlling step, and the 4th temperature controlling step is carried out towards the mode of central part step-down from the end of the width of above-mentioned plate glass with the temperature of the width of above-mentioned plate glass.In other words, in 3rd cooling step S43, preferably be less than in the region near strain point of glass in the temperature of above-mentioned central part, to control the temperature of above-mentioned glass ribbon from the above-mentioned both ends (edge part) of above-mentioned glass ribbon towards the mode of above-mentioned central part step-down.

In addition, the 7th temperature distribution TP7 ~ the 10th temperature distribution TP10 is realized by the well heater 82d ~ 82g in controlled cooling model chamber 80.Specifically, realize the 7th temperature distribution TP7 by well heater 82d, realize the 8th temperature distribution TP8 by well heater 82e, realize the 9th temperature distribution TP9 by well heater 82f, realize the 10th temperature distribution TP10 by well heater 82g.The temperature of the central part C of middle section CA is minimum, the temperature of edge part R, L is the highest, and thermograde TG7 ~ 10 increased gradually along the flow direction of glass ribbon GR in the 7th temperature distribution TP7 ~ the 10th temperature distribution TP10, constantly can apply tension force at the central part of glass ribbon GR thus, the warpage of glass ribbon GR can be suppressed.

And, in above-mentioned 1st ~ 3rd cooling step, central part in order to the width at above-mentioned glass ribbon makes tension force work in the conveyance direction of glass ribbon, can carry out temperature control as follows: at least deduct in the temperature province of the temperature (strain point-200 DEG C) of 200 DEG C from the temperature (annealing point+150 DEG C) that glass annealing point adds 150 DEG C to strain point of glass in the temperature of the central part of the width of above-mentioned glass ribbon, the speed of cooling of the central part of the width of above-mentioned glass ribbon is faster than the speed of cooling at the both ends of above-mentioned width.

As mentioned above, in above-mentioned 1st ~ 3rd cooling step preferably: (1) with the temperature of the central part of the width at the above-mentioned glass ribbon both ends that are the width of glass ribbon above-mentioned in region more than glass softening point lower than the temperature of the central part clamped by above-mentioned both ends and the temperature of above-mentioned central part becomes the temperature that uniform mode controls above-mentioned glass ribbon; (2) at the central part of the width of above-mentioned glass ribbon, being be less than glass softening point and be more than or equal in the region of strain point of glass to make the tension force of glass ribbon conveyance direction play a role in the temperature of the above-mentioned central part of above-mentioned glass ribbon, from above-mentioned central part, control the temperature of above-mentioned glass ribbon towards the mode of above-mentioned both ends step-down with the temperature distribution of the width of above-mentioned glass ribbon; And the mode that disappears of the thermograde at (3) above-mentioned both ends and above-mentioned central part of becoming the width of above-mentioned glass ribbon in the temperature province of strain point of glass with the temperature of the above-mentioned central part at above-mentioned glass ribbon controls the temperature of above-mentioned glass ribbon.

Embodiment

Below, the present invention is further described by embodiment.But the present invention is not defined as the intention of embodiment.

Embodiment 1

(making of sample glass)

To become the mode of the glass composition shown in table 1, use common frit and silicon-dioxide, aluminum oxide, boron oxide, salt of wormwood, alkaline magnesium carbonate, calcium carbonate, Strontium carbonate powder, tindioxide and ferric oxide, blending frit batch of material (hereinafter referred to as batch of material).

The continuous fusion device possessing the melting groove of refractory brick and the adjustment tank of platinum alloy is used to be melted with 1560 ~ 1640 DEG C by the batch of material of above-mentioned blending, with 1620 ~ 1670 DEG C of clarifications and with after 1440 ~ 1530 DEG C of stirrings, use the manufacturing installation of the glass substrate shown in Fig. 1 and 2, the width being shaped to glass ribbon GR by overflow downdraw is 1600mm, thickness is the lamellar of 0.7mm, anneal under prescribed conditions, obtain liquid-crystal display (OLED display is used) glass substrate.The annealing conditions of regulation is shown in table 2 ~ 6.In addition, about following each characteristic, made the test glass substrate of 30mm × 40mm × 0.7mm by the glass substrate obtained with the annealing conditions of table 3.

(strain point, annealing point)

Use camber beam determinator (manufacture of Tokyo Industries, Inc) to measure, obtain strain point and annealing point according to camber beam method (ASTMC-598) by calculating.

(percent thermal shrinkage)

Glass substrate is heated up with 10 DEG C/min from normal temperature, keep 1 hour at 550 DEG C, thereafter, normal temperature is cooled to 10 DEG C/min, again with 10 DEG C/min of intensifications, keep 1 hour at 550 DEG C, be cooled to normal temperature with 10 DEG C/min, use the shrinkage of the glass substrate after aforesaid operations, obtain percent thermal shrinkage by following formula.

Percent thermal shrinkage (ppm)

={ length of the glass before the shrinkage/thermal treatment of the glass before and after thermal treatment } × 10 ⁶

In the present embodiment, specifically, the mensuration of shrinkage is carried out by the following method.

(measuring method of devitrification temperature)

Above-mentioned glass substrate is pulverized, by the sieve of 2380 μm, obtains the glass grain residued on the sieve of 1000 μm.This glass grain to be impregnated in ethanol and after carrying out ultrasonic cleaning, in thermostatic bath, to carry out drying.On the platinum boat of width 12mm, length 200mm, degree of depth 10mm, drop into the glass grain of drying in the mode making above-mentioned glass grain 25g become constant thickness.Have 1080 ~ 1320 DEG C thermograde electric furnace in keep this platinum boat 5 hours, thereafter, take out in stove, result from the devitrification of inside glass with the observation by light microscope of 50 times.The top temperature observing devitrification is set to devitrification temperature.

(measuring method of mean thermal expansion coefficients α and Tg in the scope of 100 ~ 300 DEG C)

Use differential dilatometer (ThermoPlus2TMA8310), the temperature in mensuration temperature-rise period and the stroke of glass.Heat-up rate is now 5 DEG C/min.Based on the measurement result of the stroke of said temperature and glass, measure the mean thermal expansion coefficients in the temperature range of 100 ~ 300 DEG C and Tg.

(density)

For the density of glass, by Archimedian method, above-mentioned Young's modulus working sample is measured.

(Young's modulus, than Young's modulus)

For Young's modulus, make the glass of thickness 5mm, measured by ultrasonic pulse method.Calculated by Young's modulus and density than Young's modulus.

(melt temperature, liquid phase viscosity)

Melt temperature is according to using the measurement result of platinum ball pull-type automatic viscosity determinator to calculate viscosity for temperature during 102.5dPas and obtaining.The viscosity that liquid phase viscosity calculates under devitrification temperature according to said determination result obtains.

(ratio resistance)

The 4192ALF impedance analyzer using Hewlett-Packard Corporation to manufacture also utilizes four-terminal method to measure, and calculates the ratio resistance value of 1550 DEG C according to said determination result.

The composition (mol%) of glass, devitrification temperature (DEG C), annealing point (DEG C), strain point (DEG C), mean thermal expansion coefficients (× 10 ^-7dEG C ^-1), density (g/cm ³), Young's modulus (GPa), more as shown in table 1 than Young's modulus, melt temperature (DEG C), liquid phase viscosity (dPas), Tg (DEG C) and ratio resistance (Ω cm).

[table 1]

The average cooling rate (DEG C/sec) of the temperature variation (DEG C) of glass ribbon GR in cooling step S4 and the measured value of time (second) needed for temperature variation and the central part C of glass ribbon GR is represented in table 2 ~ 5.Value when table 2 ~ table 5 represents that the average cooling rate (DEG C/sec) in S42 (annealing point is to the scope of the temperature of strain point-50 DEG C) is respectively 0.9,1.1,2.9 and 5.1.And then, the percent thermal shrinkage of glass substrate manufactured when table 8 represents that the average cooling rate (DEG C/sec) in S42 is respectively 0.9,1.1,2.9 and 5.1.

[table 2]

[table 3]

[table 4]

[table 5]

Embodiment 2

The composition (mol%) of glass, devitrification temperature (DEG C), annealing point (DEG C), strain point (DEG C), mean thermal expansion coefficients (× 10 ^-7dEG C ^-1), density (g/cm ³), Young's modulus (GPa), more as shown in table 1 than Young's modulus, melt temperature (DEG C), liquid phase viscosity (dPas), Tg (DEG C) and ratio resistance (Ω cm).Further, the width of glass ribbon GR is 1600mm, and thickness is 0.7mm.

Table 6 ~ 7 represent the average cooling rate (DEG C/sec) of the temperature variation (DEG C) of glass ribbon GR and the measured value of time (second) needed for temperature variation and the central part C of glass ribbon GR in cooling step S4.Table 6 ~ 7 are the average cooling rate (DEG C/sec) represented in S42 values when being respectively 2.1 and 3.0.And then, the percent thermal shrinkage of glass substrate manufactured when the average cooling rate (DEG C/sec) representing in S42 in table 8 is respectively 2.1 and 3.0.

[table 6]

[table 7]

[table 8]

According to the result shown in table 8, the average cooling rate in the 2nd cooling step is 0.5 ~ when being less than between 5.5 DEG C/sec, the glass substrate that percent thermal shrinkage is below 60ppm can be obtained.

Comparative example

Table 9 represent the temperature variation (DEG C) of glass ribbon GR in cooling step S4 and the time (second) needed for temperature variation measured value, based on measured value interpolation about until the value (interpolate value) of time arrived till annealing point (715 DEG C), strain point-50 DEG C (610 DEG C) and strain point-200 DEG C (460 DEG C) and the speed of cooling (DEG C/sec) of central part C.

In cooling step S4, implement cooling step in the mode that the speed of cooling in the 1st cooling step S41 is maximum value, speed of cooling in the 3rd cooling step S43 is Second Largest Value, speed of cooling in the 2nd cooling step S42 is minimum value.The percent thermal shrinkage of the glass substrate obtained is as shown in table 8 is 86ppm.

[table 9]

Claims

1. a manufacture method for glass substrate for plane display device, the method comprises:

(1) melt step, Blend Stocks, to make the resultant of SrO and BaO in manufactured glass substrate be less than 8 quality % and this glass substrate has the strain point of more than 675 DEG C, melts;

(3) cooling step, with following condition (A), the shaping glass ribbon obtained is cooled, (A) average cooling rate the temperature (strain point-50 DEG C) of 50 DEG C is deducted from annealing point to strain point: 0.5 DEG C/sec ~ be less than 5.5 DEG C/sec

Described cooling step is made up of following steps:

By 1,100 DEG C ~ 1, the glass ribbon cools of 250 DEG C is to the 1st cooling step exceeding annealing point;

Self-annealing is lighted and is cooled to the 2nd cooling step that strain point deducts the temperature (strain point-50 DEG C) of 50 DEG C; And

The 3rd cooling step of the temperature near temperature (strain point-200 DEG C) that strain point deducts 200 DEG C is cooled to from being less than strain point and deducting the temperature of the temperature (strain point-50 DEG C) of 50 DEG C,

In described 1st ~ 3rd cooling step,

(1) with the temperature of the central part of the width at the described glass ribbon both ends that are the width of glass ribbon described in region more than glass softening point lower than the temperature of the central part clamped by described both ends and the temperature of described central part becomes the temperature that uniform mode controls described glass ribbon;

(2) at the central part of the width of described glass ribbon, being be less than glass softening point and be more than or equal in the region of strain point of glass to make the tension force of glass ribbon conveyance direction play a role in the temperature of the described central part of described glass ribbon, from described central part, control the temperature of described glass ribbon towards the mode of described both ends step-down with the temperature distribution of the width of described glass ribbon; And

(3) mode that the described both ends of width of glass ribbon described in the temperature province becoming strain point of glass with the temperature of the described central part at described glass ribbon and the thermograde of described central part disappear controls the temperature of described glass ribbon.

2. the manufacture method of glass substrate for plane display device as claimed in claim 1, wherein, in melting step (1), Blend Stocks is to make (SiO in manufactured glass substrate ₂+ 2 × Al ₂o ₃)/B ₂o ₃the mol ratio of display more than 9.5.

3. the manufacture method of glass substrate for plane display device as claimed in claim 1 or 2, wherein, for the glass substrate manufactured via cooling step (3), with 10 DEG C/min of intensifications from normal temperature, keep 1 hour at 550 DEG C, thereafter normal temperature is cooled to 10 DEG C/min, again with 10 DEG C/min of intensifications, keep 1 hour, after being cooled to normal temperature with 10 DEG C/min at 550 DEG C, the percent thermal shrinkage represented by following formula is below 75ppm

Percent thermal shrinkage={ length of the glass before the shrinkage/thermal treatment of the glass before and after thermal treatment } × 10 ⁶

In above formula, the unit of percent thermal shrinkage is ppm.

4. a manufacture method for glass substrate for plane display device, the method comprises:

(3) cooling step, with following condition (A), the shaping glass ribbon obtained is cooled, (A) from being less than the average cooling rate of annealing and lighting to the temperature (strain point-50 DEG C) that strain point deducts 50 DEG C: 0.5 DEG C/sec ~ be less than 5.5 DEG C/sec

Described cooling step is made up of following steps:

In described 1st ~ 3rd cooling step,

5. the manufacture method as described in claim 1 or 4, wherein, the 1st cooling step comprises:

With the temperature of the end of the width of glass ribbon lower than the temperature of the middle section clamped by end and the temperature of middle section becomes the 1st temperature controlling step that uniform mode is carried out.

6. the manufacture method as described in claim 1 or 4, wherein, the 2nd cooling step comprises:

With the 3rd temperature controlling step that the thermograde of the end of the width of glass ribbon and central part is carried out along with the mode reduced near strain point of glass.

7. the manufacture method as described in claim 1 or 4, wherein, in described 1st ~ 3rd cooling step, central part in order to the width at described glass ribbon makes tension force work in the conveyance direction of glass ribbon, carry out temperature control as follows: at least deduct in the temperature province of the temperature (strain point-200 DEG C) of 200 DEG C from the temperature (annealing point+150 DEG C) that glass annealing point adds 150 DEG C to strain point of glass in the temperature of the central part of the width of described glass ribbon, the speed of cooling of the central part of the width of described glass ribbon is faster than the speed of cooling at the both ends of described width.