Title:
Spacer for double-glazing units, and double-glazing unit
Kind Code:
A1


Abstract:
A spacer for a double-glazing unit, and a double-glazing unit, which make it possible to improve the durability performance of the double-glazing unit and moreover are capable of housing a granular desiccant in the spacer. The double-glazing unit 10 is comprised of a pair of glass plates 11 and 12 each of thickness 3.0 mm that face one another with a predetermined gap therebetween, a spacer 13 that is inserted between the glass plates 11 and 12 at a peripheral portion thereof so as to fix the predetermined gap between the glass plates 11 and 12 at, for example, 14.5 mm, and a secondary sealant 16 that is filled between the glass plates 11 and 12 on the outside of the spacer 13 and seals the spacer 13 from the exterior. The spacer 13 is comprised of an elongated thin-walled hollow body 13b that is interposed via a primary sealant 15 between the pair of glass plates 11 and 12 in the double-glazing unit 10 and houses a desiccant 13a. The hollow body 13b has, at a side thereof facing onto the hollow layer 14 formed inside the double-glazing unit 10, an overlapping portion 13d where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates 11 and 12.



Inventors:
Kato, Hidemi (Itami-shi, JP)
Hizume, Koji (Minooshi-shi, JP)
Application Number:
11/436346
Publication Date:
09/14/2006
Filing Date:
05/18/2006
Assignee:
Nippon Sheet Glass Company, Limited (Tokyo, JP)
Primary Class:
International Classes:
E04C2/54; C03C27/06; E06B3/663
View Patent Images:
Related US Applications:



Primary Examiner:
KWIECINSKI, RYAN D
Attorney, Agent or Firm:
COZEN O'CONNOR (NEW YORK, NY, US)
Claims:
1. A spacer for a double-glazing unit joined via joining portions between a pair of glass plates in the double-glazing unit, characterized by comprising an elongated thin-walled hollow body housing a desiccant, wherein said hollow body has, at a side thereof facing onto a hollow layer formed inside the double-glazing unit, an overlapping portion where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates.

2. A spacer for a double-glazing unit as claimed in claim 1, characterized in that said hollow body has a substantially rectangular cross-sectional shape.

3. A spacer for a double-glazing unit as claimed in claim 2, characterized in that the cross-sectional shape of said hollow body projects out at a side thereof opposite said overlapping portion.

4. A spacer for a double-glazing unit as claimed in claim 3, characterized in that the side opposite said overlapping portion in the cross-sectional shape of said hollow body projects out toward an outer periphery of the double-glazing unit.

5. A spacer for a double-glazing unit as claimed in claim 1, characterized in that a gap at said overlapping portion is not more than 0.6 mm.

6. A spacer for a double-glazing unit as claimed in claim 1, characterized in that a length of said overlapping portion in a thickness direction of the double-glazing unit is not more than a value obtained by subtracting 2.0 mm from an inside dimension of said hollow body in the thickness direction of the double-glazing unit.

7. A spacer for a double-glazing unit as claimed in claim 1, characterized in that said hollow body contains aluminum or an alloy having aluminum as a principal component thereof.

8. A spacer for a double-glazing unit as claimed in claim 7, characterized in that said hollow body has a thickness of at least 2 mm.

9. A double-glazing unit characterized by having therein a spacer for a double-glazing unit as claimed in claim 1.

10. A double-glazing unit as claimed in claim 9, characterized by having a sealing portion that is filled between the pair of glass plates on an outer periphery side of the double-glazing unit relative to the spacer, and seals the spacer from an exterior.

Description:

RELATED APPLICATIONS

This is a continuation of International Application No. PCT/JP2004/017634, filed on Nov. 19, 2004, which claims priority from Japanese application no. 2003-389633 filed Nov. 19, 2003.

TECHNICAL FIELD

The present invention relates to a spacer for double-glazing units, and a double-glazing unit, and in particular to a spacer for double-glazing units, and a double-glazing unit, that can be used in the construction field in residential and non-residential buildings and so on, and the transport field in automobiles and other vehicles, ships, aircraft and so on.

BACKGROUND ART

Hitherto, as shown in FIG. 4, a double-glazing unit 40 has a substantially rectangular spacer 44 having an approximately rectangular cross-sectional shape joined via a joining material 43 between a pair of glass plates 41 and 42 in the double-glazing unit 40. The spacer 44 does not have a free end, and thus cannot open and close.

Moreover, as shown in FIG. 5, another double-glazing unit 50 is comprised mainly of a pair of glass plates 51 and 52 each of thickness 5 mm that face one another with a predetermined gap therebetween, a spacer 54 that is inserted between the glass plates 51 and 52 at a peripheral portion thereof so as to fix the predetermined gap between the glass plates 51 and 52 at, for example, 6 mm, and a curable resin sealant 55 that is filled in between the glass plates 51 and 52 on the outside of the spacer 54 and seals the spacer 54 from the exterior. The spacer 54 has a stainless steel rigid separating member 56 having a substantially U-shaped cross section that is joined via a joining material 57 between the pair of glass plates 51 and 52 in the double-glazing unit 50. The rigid separating member 56 has housed therein a moisture-permeable resin layer 53 as a desiccant (see, for example, Japanese Laid-open Patent Publication (Kokai) No. H11-107644, Japanese Laid-open Patent Publication (Kokai) No. H04-250285).

However, with the double-glazing unit 40, deformation of the pair of glass plates 41 and 42 occurs through changes in internal pressure accompanying changes in the temperature of a hollow layer 45 formed inside the double-glazing unit 40, and yet deformation of the spacer 44 hardly occurs. There is thus a problem of the joining material 43 joining between the spacer 44 and each of the pair of glass plates 41 and 42 undergoing expansion and contraction, whereby the joining material 43 becomes thinner or breaks, and hence the resistance of the double-glazing unit 40 to penetration of moisture into the hollow layer 45 is markedly reduced, bringing about a drop in the durability performance of the double-glazing unit 40.

Moreover, with the other double-glazing unit 50, thinning or breakage of the joining material 57 can be suppressed through the first spacer 54 deforming, but a special adhesive desiccant must be housed in the spacer 54, it not being possible to house an ordinary granular desiccant in the spacer 54.

The present invention has been devised in view of the problems described above. It is an object of the present invention to provide a spacer for a spacer for double-glazing units, and a double-glazing unit, which make it possible to improve the durability performance of the double-glazing unit and moreover are capable of housing a granular desiccant in the spacer.

DISCLOSURE OF THE INVENTION

To attain the above object, in an aspect of the present invention, there is provided a spacer for a double-glazing unit joined via joining portions between a pair of glass plates in the double-glazing unit, the spacer comprising an elongated thin-walled hollow body housing a desiccant, wherein the hollow body has, at a side thereof facing onto a hollow layer formed inside the double-glazing unit, an overlapping portion where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates.

In the present invention, the hollow body has a substantially rectangular cross-sectional shape.

In the present invention, the cross-sectional shape of the hollow body projects out at a side thereof opposite the overlapping portion.

In the present invention, the side opposite the overlapping portion in the cross-sectional shape of the hollow body projects out toward an outer periphery of the double-glazing unit.

In the present invention, a gap at the overlapping portion is not more than 0.6 mm.

In the present invention, a length of the overlapping portion in a thickness direction of the double-glazing unit is not more than a value obtained by subtracting 2.0 mm from an inside dimension of the hollow body in the thickness direction of the double-glazing unit.

In the present invention, the hollow body contains aluminum or an alloy having aluminum as a principal component thereof.

In the present invention, the hollow body has a thickness of at least 2 mm.

Moreover, in the present invention, there is provided a double-glazing unit having therein a spacer for a double-glazing unit according to the present invention.

In the present invention, the double-glazing unit has a sealing portion that is filled between the pair of glass plates on the outer periphery side of the double-glazing unit relative to the spacer, and seals the spacer from the exterior.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a double-glazing unit body having therein a spacer for a double-glazing unit according to an embodiment of the present invention;

FIGS. 2A and 2B are fragmentary sectional views of the double-glazing unit 10 shown in FIG. 1; specifically:

FIG. 2A is a fragmentary sectional view of an outer peripheral portion of the double-glazing unit 10; and

FIG. 2B is an enlarged fragmentary sectional view of the outer peripheral portion of the double-glazing unit 10;

FIG. 3 is a graph showing the relationship between a primary sealant strain ratio and a double-glazing unit lifetime ratio;

FIG. 4 is a sectional view of a conventional double-glazing unit; and

FIG. 5 is a sectional view of another conventional double-glazing unit.

BEST MODE FOR CARRYING OUT THE INVENTION

The present inventors carried out assiduous studies to attain the above object, and as a result discovered that in the case of a spacer for a double-glazing unit interposed via joining portions between a pair of glass plates in a double-glazing unit, if the spacer is comprised of an elongated thin-walled hollow body housing a desiccant, and the hollow body has, at a side thereof facing onto a hollow layer formed inside the double-glazing unit, an overlapping portion where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates, then even in the case that deformation of the pair of glass plates occurs through changes in internal pressure accompanying changes in the temperature of the hollow layer, because the spacer is flexible in the thickness direction of the double-glazing unit, deformation of the joining portions sealing in the hollow layer hardly occurs, and hence dropping of the resistance of the double-glazing unit to penetration of moisture into the hollow layer can be prevented for a long time period, and thus the durability performance of the double-glazing unit can be improved; moreover, a granular desiccant can be housed in the spacer.

Moreover, the present inventors discovered that if the gap at the overlapping portion is not more than 0.6 mm, then even in the case that a desiccant having a very small grain size is used, the desiccant can be reliably housed without falling out from the hollow body, and furthermore that if the length of the overlapping portion in the thickness direction of the double-glazing unit is not more than a value obtained by subtracting 2.0 mm from the inside dimension of the hollow body in the thickness direction of the double-glazing unit, then the spacer can be sufficiently flexed in the thickness direction of the double-glazing unit.

The present invention was accomplished based on the above findings.

An embodiment of the present invention will now be described with reference to the drawings.

FIG. 1 is a perspective view of a double-glazing unit body having therein a spacer for a double-glazing unit according to an embodiment of the present invention.

In FIG. 1, the double-glazing unit body 1 is comprised of a double-glazing unit 10, and a double-glazing unit holder 20 fitted in at an outer peripheral portion of the double-glazing unit 10. The double-glazing unit 10 is held in a sash 30 by the double-glazing unit holder 20.

FIGS. 2A and 2B are fragmentary sectional views of the double-glazing unit 10 shown in FIG. 1; FIG. 2A is a fragmentary sectional view of the outer peripheral portion of the double-glazing unit 10, and FIG. 2B is an enlarged fragmentary sectional view of the outer peripheral portion of the double-glazing unit 10.

As shown in FIG. 2A, the double-glazing unit 10 is comprised of a pair of glass plates 11 and 12 each of thickness 3.0 mm that face one another with a predetermined gap therebetween, a spacer 13 that is inserted between the glass plates 11 and 12 at a peripheral portion thereof so as to fix the predetermined gap between the glass plates 11 and 12 at, for example, 14.5 mm, and a secondary sealant 16 (sealing portion) that is filled between the glass plates 11 and 12 on the outside of the spacer 13 (on the outer periphery side of the double-glazing unit 10) and seals the spacer 13 from the exterior. A hollow layer 14 formed inside the double-glazing unit 10 is filled with dry air.

The spacer 13 is comprised of an elongated thin-walled hollow body 13b that is interposed via a primary sealant 15 (joining portions) between the pair of glass plates 11 and 12 in the double-glazing unit 10 and houses a desiccant 13a. The hollow body 13b has, at a side thereof facing onto the hollow layer 14 formed inside the double-glazing unit 10, an overlapping portion 13d where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates 11 and 12. Moreover, as shown in FIG. 2B, a gap D at the overlapping portion 13d is not more than 0.6 mm, and a length A of the overlapping portion 13d in a thickness direction of the double-glazing unit 10 (hereinafter merely referred to as the “length A of the overlapping portion 13d”) is not more than a value obtained by subtracting 2.0 mm from an inside dimension E of the hollow body in the thickness direction of the double-glazing unit. The inside dimension E of the hollow body in the thickness direction of the double-glazing unit 10 is, for example, 10 mm.

The elongated thin-walled hollow body 13b is made of aluminum, has a thickness of 0.35 mm, and has material constants of a Young's modulus of 7.0×105 kgf/cm2, and a Poisson ratio of 0.3.

To make it difficult for moisture to permeate through the primary sealant 15 in particular, the primary sealant 15 is, for example, made of butyl rubber, has material constants of, for example, a Young's modulus of 5.0 kgf/cm2 and a Poisson ratio of 0.4, and has a thickness of, for example, 0.25 mm. Moreover, the length of contact at the interface between the primary sealant 15 and each of the glass plates 11 and 12 is 5.0 mm.

The secondary sealant 16 is made, for example, of a highly adhesive silicone or polysulfide sealant, and has material constants of, for example, a Young's modulus of 20 kgf/cm2 and a Poisson ratio of 0.4. Moreover, the length of contact at the interface between the secondary sealant 16 and each of the glass plates 11 and 12 is 5.0 mm. As a result, dropping of the resistance to penetration of moisture into the hollow layer 14 can be prevented for a yet longer time period.

Here, as described earlier, expansion and contraction of the primary sealant 15 affects the durability performance of the double-glazing unit 10, and hence the durability performance, i.e. lifetime, of the double-glazing unit 10 can be evaluated using a strain ratio for the primary sealant 15.

First, the number of repeated actions until the primary sealant breaks, i.e. the lifetime of the primary sealant under repeated dynamic stress actions, is given by the maximum integer i for which equation (1) is satisfied. In equation (1), σC represents a value representing the strength of the primary sealant, σL represents a value representing the stress acting on the primary sealant, and n represents a constant characteristic of the material.
i<(σC/σL)n+1 (1)

Next, let us compare the lifetime for two primary sealants having different stresses acting thereon. That is, taking σL1 to be a value representing the stress acting on the primary sealant in a conventional double-glazing unit as shown in FIG. 4, and taking σL2 to be a value representing the stress acting on the primary sealant in the double-glazing unit of the present invention, the ratio R of the lifetime for the primary sealant in the double-glazing unit of the present invention relative to the primary sealant in the conventional double-glazing unit is given by the following equation.
R=(β)−(n+1) (2)

(wherein β=σL2/σL1)

By using above equation (2), the increase in the lifetime of the primary sealant in the double-glazing unit of the present invention relative to the lifetime of the primary sealant in the conventional double-glazing unit can be estimated. For example, setting the material-characteristic constant n for the primary sealant in equation (2) to be 2, 7 or 16, the results of plotting the double-glazing unit lifetime ratio against the primary sealant strain ratio (β) are as shown in FIG. 3.

FIG. 3 is a graph showing the relationship between the primary sealant strain ratio and the double-glazing unit lifetime ratio.

In FIG. 3, the primary sealant strain ratio is shown on the axis of abscissas, and the double-glazing unit lifetime ratio is shown on the axis of ordinates. In FIG. 3, “⋄” shows the relationship between the primary sealant strain ratio and the double-glazing unit lifetime ratio for the case that n=2, “□” for the case that n=7, and “◯” for the case that n=16.

Out of these graphs, in the case, for example, that n=2, if the primary sealant strain ratio is 0.8, then the lifetime of the double-glazing unit is approximately two times, and if the primary sealant strain ratio is 0.6, then the lifetime of the double-glazing unit is approximately 4.5 times.

From the above results, it can be seen that by reducing the primary sealant strain ratio to 0.8 or below, the lifetime of the double-glazing unit can be improved by at least two times.

According to the present embodiment, the elongated thin-walled hollow body 13b having the desiccant 13a housed therein has, at a side thereof facing onto the hollow layer 14 formed inside the double-glazing unit 10, an overlapping portion 13d where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates 11 and 12. As a result, even in the case that deformation of the pair of glass plates 11 and 12 occurs through changes in internal pressure accompanying changes in the temperature of the hollow layer 14 formed inside the double-glazing unit 10, because the spacer 13 is flexible in the thickness direction of the double-glazing unit 10, deformation of the primary sealant 15 sealing in the hollow layer 14 hardly occurs, and hence dropping of the resistance of the double-glazing unit 10 to penetration of moisture into the hollow layer 14 can be prevented for a long time period, and thus the durability performance of the double-glazing unit 10 can be improved; moreover, a granular desiccant 13a can be housed in the spacer 13.

According to the present embodiment, the gap D at the overlapping portion 13d is not more than 0.6 mm. As a result, even in the case of using a desiccant 13a having a very small grain size, the desiccant 13a can be reliably housed without falling out from the hollow body 13b.

According to the present embodiment, the length A of the overlapping portion 13d is not more than a value obtained by subtracting 2.0 mm from the inside dimension E of the hollow body in the thickness direction of the double-glazing unit. As a result, the spacer 13 can be sufficiently flexed in the thickness direction of the double-glazing unit 10.

According to the present embodiment, the double-glazing unit 10 has therein a secondary sealant 16 that is filled between the pair of glass plates 11 and 12 on the outer periphery side of the double-glazing unit 10 relative to the spacer 13 and seals the spacer 13 from the exterior. As a result, dropping of the resistance to penetration of moisture into the hollow layer 14 can be prevented for a yet longer time period.

EXAMPLES

Examples of the present invention will now be described.

As Example 1, an aluminum spacer having an overlapping portion with a gap D of 0.0 mm and a length A of 2.0 mm, having an inside dimension E of the hollow body in the thickness direction of the double-glazing unit of 10 mm, and having a desiccant housed therein was first sandwiched between a pair of glass plates each of dimensions 1000 mm×1000 mm, the spacer was bonded to each of the glass plates with a butyl rubber primary sealant, and then a secondary sealant sealing the spacer from the exterior was filled in between the pair of glass plates on the outer periphery side of the double-glazing unit relative to the spacer, thus preparing a double-glazing unit. Next, as Example 2, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a gap D of 0.3 mm was used instead of the spacer having an overlapping portion with a gap D of 0.0 mm, and furthermore as Example 3, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a gap D of 0.6 mm was used.

On the other hand, as Comparative Example 1, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a gap D of 0.8 mm was used.

Next, for each of Examples 1 to 3 and Comparative Example 1, two-dimensional non-linear structural analysis taking into consideration changes in the volume of the air layer, and a cycle test were carried out, thus evaluating the durability. Here, in the cycle test, the air pressure was set to 101.3 kPa, the maximum temperature was set to 50° C. and the minimum temperature to −50° C., the time period over which the sample to be tested is kept at each of these temperatures was made to be 0.5 hours, and the time period over which the ambient temperature was changed from the maximum temperature to the minimum temperature and from the minimum temperature to the maximum temperature was made to be 3 hours; the cycle with the ambient temperature starting from the maximum temperature, passing through the minimum temperature, and then again reaching the maximum temperature was carried out 300 times.

The evaluation of the durability was carried out through overall evaluation of: primary sealant strain evaluation using two-dimensional non-linear structural analysis in which the strain was calculated for the tip on the air layer side of the primary sealant for each of the Examples and the Comparative Example, taking the strain for the tip on the air layer side of the primary sealant in the case of using the conventional spacer as standard; and a desiccant check of checking whether or not the desiccant was still housed in the spacer after the above cycle test.

The evaluation results are shown in Table 1. In Table 1, “pass” is represented by “◯”, and “fail” by “X>”; likewise hereinafter.

TABLE 1
PrimaryRatio relative
Gap D atLength A ofsealantto strain for
overlappingoverlappingstrainconventionalDesiccant
portion (mm)portion (mm)(%)spacer (%)checkJudgment
Example 10.02.05.349
Example 20.32.05.349
Example 30.62.05.450
Comparative0.82.05.450XX
Example 1

From the results in Table 1, it can be seen that because the elongated thin-walled hollow body housing the desiccant has, at a side thereof facing onto the hollow layer formed inside the double-glazing unit, an overlapping portion where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates, even in the case that deformation of the pair of glass plates occurs through changes in the internal pressure accompanying changes in the temperature of the hollow layer formed inside the double-glazing unit, because the spacer is flexible in the thickness direction of the double-glazing unit, deformation of the primary sealant sealing in the hollow layer hardly occurs, and hence dropping of the resistance of the double-glazing unit to penetration of moisture into the hollow layer can be prevented for a long time period, and thus the durability performance of the double-glazing unit can be improved; moreover, the granular desiccant can be housed in the spacer.

Moreover, it can be seen that if the gap D at the overlapping portion is not more than 0.6 mm, then even in the case of using a desiccant having a very small grain size, the desiccant can be reliably housed without falling out from the hollow body.

Next, for the double-glazing unit of Example 1, spacers having different lengths A of the overlapping portion were used, and durability tests were carried out on the resulting double-glazing units.

Specifically, as Example 4, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a length A of 0.0 mm was used instead of the spacer having an overlapping portion with a length of 2.0 mm; the overlapping portion had a gap D of 0.0 mm. Moreover, as Example 5, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a length A of 1.0 mm was used, as Example 6, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a length A of 4.0 mm was used, and as Example 7, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a length A of 8.0 mm was used.

On the other hand, as Comparative Example 2, a double-glazing unit was prepared having the same construction as in Example 1 except that a spacer having an overlapping portion with a length A of 10 mm was used, this being the same as the inside dimension E of the hollow body in the thickness direction of the double-glazing unit.

Next, for Examples 4 to 7 and Comparative Example 2, the durability was evaluated as for Example 1. The results are shown in Table 2.

TABLE 2
PrimaryRatio relative
Gap D atLength A ofsealantto strain for
overlappingoverlappingstrainconventionalDesiccant
portion (mm)portion (mm)(%)spacer (%)checkJudgment
Example 40.00.05.046
Example 50.01.05.248
Example 50.04.05.450
Example 60.08.05.854
Comparative0.010.09.285X
Example 2

From the results in Table 2, it can be seen that if the length A of the overlapping portion is not more than 8.0 mm, then the spacer can be sufficiently flexed in the thickness direction of the double-glazing unit.

In the above embodiment of the present invention, the double-glazing unit 10 may be constructed using laminated glass, or three or more glass plates, and moreover may be constructed such that all or some of the glass plates in the double-glazing unit 10 have a function of absorbing heat rays, absorbing ultraviolet rays, reflecting heat rays (possibly as a thermal barrier) or the like, or are wired, tempered or the like.

Moreover, in this embodiment, a pair of glass plates 11 and 12 are used for the double-glazing unit 10; the pair of glass plates 11 and 12 may be any of evacuated glass (e.g. Spacia (registered trademark)), functional glass on which a heat ray-reflecting film has been formed by vapor deposition (e.g. Refshine (registered trademark)), security glass having a resin film sandwiched therein (e.g. Secuo (registered trademark)), tempered glass for which the surface compressive stress has been increased through heat treatment (e.g. Pyroclear (registered trademark)), or the like.

In this embodiment, the hollow layer 14 formed inside the double-glazing unit 10 is filled with dry air; however, there is no limitation thereto, but rather the hollow layer 14 may be filled with an inert gas such as Ar.

In this embodiment, the elongated thin-walled hollow body 13b may have a substantially rectangular cross-sectional shape. As a result, the joint strength at the primary sealant 15 can be improved. Moreover, the cross-sectional shape of the hollow body 13b may project out at a side thereof opposite the overlapping portion 13d. As a result, the hollow body 13b can be reliably flexed. Furthermore, the side opposite the overlapping portion 13d in the cross-sectional shape of the hollow body 13b may project out toward the outer periphery of the double-glazing unit 10. As a result, space for housing the desiccant 13a can be reliably secured.

In this embodiment, the spacer 13 is made of aluminum; however, there is no limitation thereto, but rather the spacer 13 may be made of an alloy having aluminum as a principal component thereof. As a result, the gap between the pair of glass plates 11 and 12 can be kept approximately constant.

In this embodiment, the primary sealant 15 is made of butyl rubber; however, there is no limitation thereto, but rather the primary sealant 15 may be made of any material that makes it difficult for moisture to permeate therethrough. Moreover, the primary sealant 15 has a thickness of 0.25 mm, but there is no limitation to this value. Furthermore, the length of contact at the interface between the primary sealant 15 and each of the glass plates 11 and 12 is 5.0 mm, but there is no limitation to this value.

In this embodiment, the secondary sealant 16 is made of a highly adhesive silicone or polysulfide sealant, but there is no limitation thereto. Moreover, the length of contact at the interface between the secondary sealant 16 and each of the glass plates 11 and 12 is 5.0 mm, but there is no limitation to this value.

INDUSTRIAL APPLICABILITY

According to the spacer for a double-glazing unit of the present invention, the elongated thin-walled hollow body housing the desiccant has, at a side thereof facing onto the hollow layer formed inside the double-glazing unit, an overlapping portion where overlap occurs in a direction perpendicular to mutually facing surfaces of the pair of glass plates. As a result, even in the case that deformation of the pair of glass plates occurs through changes in internal pressure accompanying changes in the temperature of the hollow layer formed inside the double-glazing unit, because the spacer is flexible in the thickness direction of the double-glazing unit, deformation of the joining portions sealing in the hollow layer hardly occurs, and hence dropping of the resistance of the double-glazing unit to penetration of moisture into the hollow layer can be prevented for a long time period, and thus the durability performance of the double-glazing unit can be improved; moreover, a granular desiccant can be housed in the spacer.

According to a preferred form of the spacer for a double-glazing unit of the present invention, the hollow body has a substantially rectangular cross-sectional shape. As a result, the joint strength at the joining portions can be improved.

According to a preferred form of the spacer for a double-glazing unit of the present invention, the cross-sectional shape of the hollow body projects out at a side opposite the overlapping portion. As a result, the hollow body can be reliably flexed.

According to a more preferred form of the spacer for a double-glazing unit of the present invention, the side opposite the overlapping portion in the cross-sectional shape of the hollow body projects out toward the outer periphery of the double-glazing unit. As a result, space for housing the desiccant can be reliably secured.

According to a preferred form of the spacer for a double-glazing unit of the present invention, the gap D at the overlapping portion is not more than 0.6 mm. As a result, even in the case of using a desiccant having a very small grain size, the desiccant can be reliably housed without falling out from the hollow body.

According to a preferred form of the spacer for a double-glazing unit of the present invention, the length A of the overlapping portion in the thickness direction of the double-glazing unit is not more than a value obtained by subtracting 2.0 mm from the inside dimension E of the hollow body in the thickness direction of the double-glazing unit. As a result, the spacer can be sufficiently flexed in the thickness direction of the double-glazing unit.

According to a preferred form of the spacer for a double-glazing unit of the present invention, the hollow body contains aluminum or an alloy having aluminum as a principal component thereof. As a result, the gap between the pair of glass plates can be kept approximately constant.

According to a more preferred form of the spacer for a double-glazing unit of the present invention, the hollow body has a thickness of at least 2 mm. As a result, the spacer can be sufficiently flexed in the thickness direction of the double-glazing unit.

According to the double-glazing unit of the present invention, the spacer thereof is flexible in the thickness direction of the double-glazing unit, whereby deformation of the joining portions sealing in the hollow layer hardly occurs. As a result, dropping of the resistance to penetration of moisture into the hollow layer can be prevented for a long time period.

According to a preferred form of the double-glazing unit of the present invention, the double-glazing unit has therein a sealing portion that is filled between the pair of glass plates on the outer periphery side of the double-glazing unit relative to the spacer, and seals the spacer from the exterior. As a result, dropping of the resistance to penetration of moisture into the hollow layer can be prevented for a yet longer time period.