Specification

Technical Field

[0001 ] The present invention relates to a glass polygonal tube, a method for manufacturing the same, and a container, and more particularly relates to a glass polygonal tube suitable for employment as a large container employed for the thermal processing of large substrates for solar cells or organic ELs or the like, and to a method for manufacturing the same and a container.

Prior Art [0002] Conventional large-size containers are principally constituted from quartz glass or the like, and the production thereof is based on the employment of large bore tubes formed by heating a quartz glass tube as it is fed through a lathe (for example, Patent Document 1 ). An additional method in use is based on filling a tubular-shaped mold with quartz crystal particles and heating the mold from the inner-surface side to manufacture a tube with a large bore. Another method commonly employed for square-shaped large containers comprises heating large quartz glass plate members with a flame burner and using a quartz glass welding rod to weld the end surfaces of the quartz glass plates (for example, Patent Document 2). [0003] However, the increase in the size of solar cell and organic El substrates has been more rapid in recent years, and a further increase in the size of the large containers used for the thermal processing is required. Unfortunately, there are limits to both the equipment and the technologies available for forming quartz glass tubes with a large bore, and the manufacture thereof has proved

problematic.

[0004] In addition, apart from the drop in outer diameter and wall thickness tolerance associated with a larger bore, there are inherent problems in current methods for increasing bore size based on the flame processing of a tube or packing and melting a powder in a mold in that, for tubes of outer diameter not less than 500 mm, the outer diameter tolerance is of the order of ±50 mm, the wall thickness tolerance is of the order of ±5 mm, and the length tolerance is of the order of ±30 mm. Poor dimensional tolerance leads to a drop in sealing

characteristics and, accordingly, because the gas that is used in processes for solar cells or organic EL cells is an especially toxic gas, the use of conventional tubes is problematic from the standpoint of the sealing characteristics at the end portions thereof. In addition, the wall thickness tolerance and dimensional tolerance of large containers is becoming increasingly severe.

[0005] Furthermore, accompanying recent advancements in low-temperature processing, the use of other glasses other than quartz glass including, for example, high silica glass, Pyrex (registered trademark), vycor, tempax, neoceram, neorex and fayalite has been considered.

Prior Art Documents

[0006] Japanese Laid-Open Patent Application No. H4-26522

Japanese Published Utility Model No. H7-14194

Disclosure of the Invention

Problems to be Solved by the Invention

[0007] It is an object of the present invention to provide a glass polygonal tube of excellent dimensional precision for which increase in size is possible, a method of manufacturing a glass polygonal tube that affords the simple manufacture of this glass polygonal tube, and a container of excellent dimensional precision for which increase in size is possible.

Means for Solving the Problems

[0008] As a result of extensive research carried out by the inventor etc. of the present invention to establish a method of manufacturing a large container for solving the problems described above, it was discovered that a large container could be simply manufactured by bonding at least four heat-resistant glass plates using a slurry-like adhesive having SiO ₂ fire particles as a principal component. [0009] That is to say, the method of manufacturing a glass polygonal tube of the present invention constitutes a method of manufacturing a glass polygonal tube formed by bonding at least four heat-resistant glass plates using a slurry-like adhesive having SiO ₂ fine particles as a principal component characterized by comprising:

(A) a step for joining heat-resistant glass plates using a slurry-like adhesive having SiO ₂ fine particles as a principal component to form a joined body; and

(B) a step for heating the aforementioned joined body to at least 100°C to bond the aforementioned heat-resistant glass plates. The number of the aforementioned heat-resistant glass plates is preferably not less than ten.

[0010] The viscosity of the aforementioned slurry-like adhesive as measured by a B-type viscometer under conditions of 30rpm and 23 °C is preferably not less than 3000mPa-s.

[001 1 ] The joining of the aforementioned step (A) is ideally performed at room temperature.

[0012] Quartz glass is ideally employed as the aforementioned heat-resistant glass plate. When quartz glass is employed as the aforementioned heat-resistant glass plate, the heating of step (B) is preferably performed at a temperature of not less than 500 °C. [0013] The glass polygonal tube of the present invention is characterized in being formed by bonding at least four heat-resistant glass plates using a slurry-like adhesive having SiO ₂ fine particles as a principal component. The number of the aforementioned heat-resistant glass plates is preferably not less than ten.

[0014] According to the present invention, a large-bore glass polygonal tube can be obtained in which the outer diameter of the aforementioned glass polygonal tube is not less than 500 mm, the wall thickness of the aforementioned glass polygonal tube is not less than 10 mm, and the length of the aforementioned glass polygonal tube is not less than 1000 mm. In addition, according to the present invention, in the aforementioned large-bore glass polygonal tube the dimensional tolerance of the outer diameter of the aforementioned glass polygonal tube is within ±5 mm, the dimensional tolerance of the wall thickness of the

aforementioned glass polygonal tube is within ±2 mm, and the dimensional tolerance of the length of the aforementioned glass polygonal tube is within ±10 mm.

[0015] The glass polygonal tube of the present invention is ideally

manufactured by the method of manufacturing the glass polygonal tube of the present invention as described above.

[0016] The container of the present invention is characterized in being manufactured by employing the glass polygonal tube of the present invention described above.

Effects of the Invention

[0017] A significant effect of the present invention resides in the provision of a glass polygonal tube and a container of excellent dimensional precision for which an increase in size is possible. An additional significant effect of the present invention resides in the provision of a method of manufacturing a glass polygonal tube that affords the simple manufacture of a glass polygonal tube that exhibits excellent dimensional precision even when manufactured in a large size.

Brief Description of the Drawings [0018]

FIG. 1 is a perspective explanatory diagram of one embodiment of the glass polygonal tube of the present invention;

FIG. 2 is a perspective explanatory view showing a state at a midpoint in the manufacture of the glass polygonal tube of FIG. 1 ; FIG. 3 is a perspective explanatory view of another embodiment of the glass polygonal tube of the present invention; FIG. 4 is a perspective explanatory view showing a state at a midpoint in the manufacture of the glass polygonal tube of FIG. 3; and

FIG. 5 is an expanded view of the main portion of the inner-surface side of the glass polygonal tube of FIG. 4. Best Means for Carrying out the Invention

[0019] While embodiments of the present invention will be hereinafter described with reference to FIGS. 1 to 5, this description is obviously provided for illustrative purposes only, and the present invention should not be construed as being limited thereto. [0020] FIG. 1 is a perspective explanatory diagram of one embodiment of the glass polygonal tube of the present invention, and FIG. 2 is a perspective explanatory view showing a state at a midpoint in the manufacture of the glass polygonal tube of FIG. 1 . The symbol 10 in FIG. 1 denotes a first glass polygonal tube. The polygonal tube 10 is formed by bonding at least four (fourteen in FIG. 1 ) heat-resistant glass plates 12 into a polygonal tube-shape (14-corner tube shape in FIG. 1 ) using a slurry-like adhesive 14 having SiO ₂ fine particles as a principal component. FIG. 2 shows a glass polygonal tube intermediate body denoted by the symbol 10a in a state in which, at a manufacturing midpoint, six heat-resistant glass plates 12 have been bonded in an arch shape using a slurry-like adhesive 14 having SiO ₂ fine particles as a principal component. The polygonal tube 10 shown in FIG. 1 is formed from the state of the glass polygonal tube intermediate body 10a by further bonding the eight remaining heat-resistant glass plates 12 using a slurry-like adhesive having SiO ₂ fine particles as a principal component.

[0021 ] While a range of well-known heat-resistant glasses are able to be used as the aforementioned heat-resistant glass plates and there are no particular limitations thereto, glasses that have a coefficient of thermal expansion in the temperature range 20 °C to 700 °C of 1 x10 ^~7 to 1 x10 ^~5 (°K ^~1 ) are preferred and, more specifically, doped or non-doped silicate glasses containing not less than 85% by mass SiO ₂ are desirable. Examples of such silicate glasses include, for example, highly heat-resistant glasses such as high silica glass, Pyrex (registered trademark), vycor, tempax, neoceram, neorex, fayalite and quartz glass of which quartz glass is most preferred.

[0022] There are no particular limitations to the shape of the aforementioned heat-resistant glass plates provided they are plate-like in shape, and this shape may be selected as appropriate to match the shape of the target glass polygonal tube. More specifically, glass plates of a rectangular or an arch shape are preferably employed.

While FIG. 1 shows an example in which the number of employed heat-resistant glass plates is fourteen, provided the number of heat-resistant glass plates employed in the glass polygonal tube of the present invention is at least four, this number may be selected as appropriate to match the shape of the target glass polygonal tube. From the standpoint of producing a large bore polygonal tube, the employment of not less than ten heat-resistant glass plates is preferred.

[0023] There are no particular limitations to the method of manufacturing the aforementioned heat-resistant glass plates, and the heat-resistant glass plates may be acquired by well-known methods including, for example, a method based on slicing a block-shaped ingot and molding performed under a high-temperature heat.

[0024] As the SiO ₂ fine particles of the slurry-like adhesive of which the aforementioned SiO ₂ fine particles serve as a principal component, non-crystalline SiO ₂ fine particles are preferred and, more specifically, fine particles of high silicic acid or quartz glass are most preferred.

[0025] The particle diameter of the aforementioned SiO ₂ fine particles is preferably not more than 500 μιη, and more preferably not more than 100 μιη, and the dissolution thereof in a solvent in which the particle diameter is controlled to establish a very close-packed particle distribution is particularly preferred. The fine particles of the high silicic acid or quartz glass may be prepared by pulverizing a glass material and ensuring the particle size is uniform. The slurry may be a mixture obtained as a blend of the fine particles of the high silicic acid and quartz glass, or it may be produced from each of these individually. In addition, from the standpoint of achieving the preferred very close packing, the particles must be dissolved in a solvent together with very fine particles.

[0026] There are no particular limitations to the solvent employed in the adhesive provided it allows for the production of a slurry-like adhesive in which SiO ₂ fine particles are dissolved and, for example, the solvent may be selected from pure water or alcohol, or another high-purity chemical product (for example, Si alkoxide) and so on. For example, when fine particles of high silicic acid or quartz glass are dissolved in pure water, the adhesive is formed as slurry that has a turbid viscosity. While there are no particular limitations to the viscosity of the adhesive, a viscosity that is too low precludes industrial application because, until the adhesive dries following application, the adhesive is fluid. In addition, a viscosity that is too large renders the handling of the adhesive difficult. Accordingly, the viscosity of the adhesive as measured by a B-type viscometer under conditions of 30rpm and 23 °C is preferably not less than 3000 mPa-s and more preferably of the order of between 4000 and 15000 mPa-s.

[0027] The solid component of the slurry-like adhesive is preferably not less than 65% by mass, more preferably not less than 80% by mass, and even more preferably not less than 83% by mass. As the slurry-like adhesive of which the aforementioned SiO ₂ fine particles serve as a principal component, a water-based slurry containing non-crystalline SiO ₂ particles as described in, for example, Japanese Patent Publication No. 2008- 51 1527 is ideally employed.

[0028] FIG. 3 is a perspective explanatory view of another embodiment of a glass polygonal tube of the present invention, FIG. 4 is a perspective explanatory view showing a state at a midpoint in the manufacture of the glass polygonal tube of FIG. 3, and FIG. 5 is an expanded view of the main portion of the inner-surface side of FIG. 4. The symbol 1 1 in FIG. 3 denotes a second glass polygonal tube. The glass polygonal tube 1 1 is formed by bonding 4 heat-resistant glass plates 12 into a polygon shape (square shape) using a slurry-like adhesive 14 having SiO ₂ . . fine particles as a principal component. FIGS. 4 and 5, in which the symbol 1 1 a denotes a glass polygonal tube intermediate at a manufacturing midpoint, show a state in which two heat-resistant glass plates 12 are bonded in an L-shape using a slurry-like adhesive 14 having SiO ₂ fine particles as a principal component. The glass polygonal tube 1 1 shown in FIG. 3 is formed from the state of the glass polygonal tube intermediate 1 1 a by additionally bonding the remaining two heat- resistant glass plates 12 using a slurry-like adhesive having SiO ₂ fine particles as a principal component.

[0029] The method of manufacturing the glass polygonal tube of the present invention is characterized by comprising: (A) a step for joining heat-resistant glass plates using a slurry-like adhesive having SiO ₂ fine particles as a principal component to form a joined body; and (B) a step for heating the aforementioned joined body to at least 100°C to bond the aforementioned heat-resistant glass plates. [0030] In step (A) described above, a joined body of a shape the same as in the completed state shown in FIGS. 1 and 3 is formed, and this joined body is subjected to a heat treatment in step (B) to afford the final adhesion of the heat- resistant glass plates and the manufacture of a glass polygonal tube in the completed state. [0031 ] In addition, following the joining of two or more heat-resistant glass plates which is a lesser amount than the completed amount of heat-resistant glass plates to form the joined body in the aforementioned step (A), these heat-resistant glass plates are bonded in step (B), and then this cycle of step (A) and step (B) may be repeated to produce the final target polygonal tube. For example, the manufacture of a glass polygonal tube in the completed state may comprise, in the step (A) noted above, forming an incomplete state arch-shaped or L-shaped joined body as shown in FIGS. 2 and 4, subjecting this joined body to a heat treatment in step (B) step to bond the incomplete state heat-resistant glass plates, forming a combined body of a joined body and a bonded body of a shape the same as the incomplete state obtained following the further bonding of a heat-resistant glass plate to the incomplete state arch-shaped or L-shaped bonded body, and then further subjecting this combined body to a heat treatment in step (B) to bond the heat-resistant glass plates in the final joined state.

[0032] While there are no particular limitations to the method of joining of step (A) described above, since an adhesive in which the glass particles are dissolved in a state approaching very close-packing possesses stickiness, the bonding may be based on coating an adhesive such as this on the end surfaces of the glass. In addition, the glass plates may be fixed at 90 °, and the adhesive may be caused to flow into the gaps within the end faces. More particularly, when fine particles are dissolved within an adhesive, because there is a risk that a bias in the particle distribution will be produced due to gravity if the adhesive is let stand, the adhesive is preferably retained in a state of adequate agitation rather than being let stand. In addition, while there are no particular limitations to the end surfaces of the plates to be bonded, an undulating surface to which the adhesive takes to readily is preferred. Incidentally, a sufficient bonding effect is able to be exhibited even on a smooth surface as long as the adhesive is not repelled.

[0033] While the adhesive used in the formation of the joined body of step (A) described above must cause the solvent to evaporate, it is sufficient for the location of bonding to be heated to room temperature or to a temperature of the order of 100°C. This method for heating may comprise blowing a hot wind forcibly onto the bonding portion, or may comprise heating based on the use of an industrial drier or the like. Depending on need, the location of bonding may be dried using a flame.

[0034] The temperature of the heating of step (B) described above is not less than 100°C and, while this may be selected as appropriate according to either the type of fine particle dissolved in the adhesive or the type of glass plate, the temperature at which the glass fine particles fuse due to heating is ideal.

From the standpoint of bonding quartz glass plates with an adhesive of which the SiO ₂ component is quartz glass, the temperature of heating is preferably not less than 500 °C, and is more preferably a temperature of not less than 1000°C and not more than 1400°C. In addition, for high silica glass, Pyrex (registered trademark), vycor, tempax, neoceram, neorex, and fayalite, the glass material is heated to not - - less than 200 °C, and is preferably heated to between not less than 400 °C and not more than 500 °C.

While the heating time is selected as appropriate in response to the temperature of heating, the heating time is ideally between 1 and 10 hrs. [0035] By the employment in the present invention of an adhesive having SiO ₂ as a principal component, elongation and contraction attributable to thermal expansion is able to be minimized. In addition, by the preparation and bonding of at least four glass plates in the present invention, a glass polygonal tube of very high dimensional precision and low tolerance is able to be produced. For example, in a large bore polygonal tube having an outer diameter not less than 500 mm, a wall thickness not less than 10 mm and a length not less than 1000 mm, a large bore polygonal tube of excellent dimensional precision having an outer diameter dimensional tolerance within ±5 mm, wall thickness dimensional tolerance within ±2 mm, and length dimensional tolerance within ±10 mm is able to be produced. Working Examples

[0036] While the present invention will be hereinafter specifically described with reference to the working examples thereof, it should be noted that these working examples serve as illustrative examples only, and the present invention should in no way be construed as being limited thereto. [0037] Test Example 1

A quartz glass fine powder was modified to prepare fine particles of not more than 1 μιη, medium particles of between 5 and 10 μιη, and large particles of a size 50 to 100 μιη which were blended in a proportion to afford close packing, and then dissolved in pure water. The moisture content thereof was of the order of approximately 10%, and the viscosity of the adhesive as measured using a B-type viscometer at a rotation rate condition of 30rpm and at room temperature (23 °C) was 6500 Mpa-sec.

Two quartz glass square rods of width 10 mm x length 40 mm x t10 mm were joined using this adhesive, and then heated for 1 hr at 1200 °C to bond the quartz - - glass square rods to produce a long, narrow square rod of width 10 mm x length 80 mm x t10 mm.

[0038] Using the thus-bonded quartz glass square rod as a sample, a 3-point bending test was carried out thereon in accordance with the JAS primary-grade laminated veneer lumber test using the method described below, and the resistance load (N) was measured. The sample was loaded on two support rods having support points a distance of 30 mm apart and was disposed linearly across the span thereof with the top surface of the sample as the upper surface, and then a load was applied at a load speed of 0.5 mm/min to the effective length (width of the sample) of the loaded rod, and the load resistance was measured at room temperature. Table 1 shows the results thereof.

[0039] Test Example 2

Using an adhesive the same as that used in Test Example 1 , two quartz glass square rods of width 10 mm x length 40 mm x t10 mm were joined at room temperature and then heated for 1 hr at 600 °C to produce a sample of the same size as Working Example 1 . A 3-point bending test was carried out on this sample using the same method employed for Test Example 1 . Table 1 shows the results thereof.

[0040] Test Example 3 Ethanol was added to the adhesive of Test Example 1 and, following

measurement using a B-type viscometer at a rotation rate condition of 30rpm at room temperature (23 °C) which indicated an adhesive viscosity of 4500 mPa-sec, quartz glass and neocerum (width 10 mm x length 40 mm x t10 mm) were joined using the adhesive, and the joined surface was rapidly dried using an industrial drier to produce a joined body. The thus-produced joined body was heated for 1 hr at 600 °C to bond the quartz glass and neocerum so as to produce a sample. A 3- point bending test was carried out on this sample using the same method employed for Test Example 1 . Table 1 shows the results thereof. - -

[0041 ] Test Example 4

Using an adhesive the same as that used in Test Example 1 , two quartz glass square rods of width 25 mm x length 40 mm x t25 mm were joined at room temperature and then heated for 1 hr at 1200 °C to produce a sample of width 25 mm x length 80 mm x t25 mm. A 3-point bending test was carried out on this sample using the same method employed for Test Example 1 . Table 1 shows the results thereof.

[0042] Comparative Example 1

Although two quartz glass square rods (width 25 mm x length 40 mm and t25 mm) were attached by means of pressure and fused by melting the end surfaces thereof with a burner using an oxyhydrogen flame, because the end surfaces were not able to be sufficiently heated the fusion was inadequate, cracking occurred in the fused surfaces. Efforts to produce a sample were repeated until finally, on the 10 ^th attempt, a sample was successfully produced. A 3-point bending test was carried out on the thus-produced sample using the same method employed for Test Example 1 . However, because the fused surfaces were unable to be firmly fused, it simply fell apart at the bonded surfaces when the 3-point bending test was carried out. Table 1 shows the results thereof.

[0043] Comparative Example 2 Although two sheets of Pyrex (registered trademark) (40 mm x 200 mm x t25 mm) were attached by means of pressure and fused by melting the end surfaces thereof with a burner using a propane/oxgyen flame, the Pyrex (registered trademark) cracked while this procedure was being carried out, and the fusion could not be completed. Although a number of attempts to produce a sample were made, unfortunately a sample was unable to be produced.

[0044] Working Example 1

Thirty-six rectangular-shaped quartz glass plates of width 50 mm, length 1500 mm and wall thickness 20 mm were prepared, two quartz glass plates were joined at room temperature using an adhesive identical to the one used in Test Example 1 - - at an angle of 10° at a position along the length 1500 mm to form a joined body, and this joined body was then heated for 1 hr at 1200 °C to bond the quartz glass plates to produce a glass polygonal tube intermediate. The bonding of the quartz glass plates was repeated for this glass polygonal tube intermediate using the same method to produce a polygonal tube comprising a total of thirty-six bonded quartz glass plates of outer diameter 60 mm, length 1500 mm and wall thickness 20 mm. Notably, as a measure for increasing the mechanical strength, the adhesive was built up not only on the end surfaces of the quartz glass but also on the inner-surface side of the polygonal tube. The dimensional tolerances of this polygonal tube allow for the manufacture of a polygonal tube with very high precision of length ±10 mm, outer diameter ±10 mm and wall thickness ±2 mm.

Using a method for fusing a sample of the same wall thickness as the thus- produced polygonal tube, a sample of width 20 mm x length 80 mm x 20 mm was produced, and a 3-point bending test was carried out thereof using a method the same as that employed in Test Example 1 . Table 1 shows the results thereof.

[0045] Working Example 2

Four quartz glass plates (width 700 mm, length 700 mm, wall thickness 10 mm) were prepared and, employing an adhesive the same as that employed for Working Example 1 , the four quartz glass plates were bonded using the method described below to produce a glass polygonal tube. As shown in FIG. 5, the glass plates were fixed together at an angle of 90 ° to allow the adhesive to flow into the gaps between the end surfaces thereof, the adhesive was dried at room temperature to produce a joined body, and then this joined body was heated for 1 hr at 1200°C to bond the quartz glass plates and produce a glass polygonal tube intermediate. Quartz glass plates were further bonded to this glass polygonal tube intermediate using the same method, and a total of four quartz glass plates were bonded to produce a square tube. The dimensions of the thus-produced square tube were 700 mm ±10 mm and wall thickness 10 ±2 mm.

Using the thus-produced square tube as the sample, a 3-point bending test was carried out thereon using a method identical to the method employed for Test

Example 1 . Table 1 shows the results thereof. - -

[0046] Comparative Example 3

Despite attempts to blow up a quartz glass tube of outer diameter 300 mm and a certain wall thickness to produce a tube of outer diameter 600 mm and wall thickness 20 mm, the formation of a tube of wall thickness 20 mm proved impossible, and only a tube of wall thickness 4 mm was able to be produced.

[0047] Comparative Example 4

A quartz crystal powder was packed into a metal mold of outer diameter 700 mm, and this was melted from the center portion in a reduced-pressure atmosphere. The thus-produced quartz glass tube had an outer diameter of 600 mm ±50 mm, wall thickness of 20 mm ±6 mm and length of 1500 mm ±50 mm, and was unable to be used because of its poor dimensional precision. While ten tubes were produced by melting in this way, improvement in the dimensional precision was not recognized.

[0048] Table 1

Explanation of Symbols

10, 1 1 : Glass polygonal tube,

10a, 1 1 a: Glass polygonal tube intermediate,

12: Heat-resistant glass plate,

14: Adhesive.