Patent Application
20070017625
The present invention relates to a glass wool molded product used as thermal insulator, which product is formed by needle punching a layered body of short glass fibers (glass wool). Also, the present invention relates to an improved method of molding the product.
Glass wool molded products to be used as thermal insulators are generally prepared by producing fine and short glass fibers (glass wool) from molten glass by means of a centrifugal method or a blowing method, collecting them to form the product having a predetermined thickness, using phenol resin or melamine resin as binder, and drying them by heat. However, organic binders can easily be gasified to a large extent at high temperature in vacuum. Additionally, molded product is poorly capable of retaining their shapes, and not sufficiently thermally insulating and heat resistant. Still additionally, broken fibers are produced, and can give rise to a problem of adversely stimulating human bodies.
In view of the above identified problems of glass wool molded products formed by using short glass fibers (glass wools), there have been proposed thermal insulators of long glass fibers (continuous glass fibers) formed integrally by needle punching without using any binder (Japanese Utility Model Publication No. Hei 6-38674, Japanese Patent Laid-Open No. Hei 7-96563). However, with the techniques disclosed in the above patent documents, long glass fibers can be easily broken by the needle punching. Since fibers are broken, the binding force of fibers due to interlace is reduced. Additionally, broken fibers can easily fly out, and become scattered during the process to raise the consumption rate of glass fibers and adversely stimulate human bodies. Furthermore, since the interlace of fibers is reduced, the density of the product increases, to by turn raise the thermal conductivity and to reduce the heat resistance of the product. Since the binding force of fibers is reduced, the tensile strength of the product is lowered to make the product less handleable when manufacturing, transporting and otherwise using. Moreover, since the binding force of fibers is reduced, the smoothness and the hardness of the surface of the glass wool molded product become insufficient. Finally, since fibers are broken, the cost of manufacturing the product increases.
In view of the above identified problems of the prior art, it is the object of the present invention to provide a glass wool molding that shows satisfactory characteristics in use in terms of compression strength, tensile strength, thermal insulation, compression resiliency, surface hardness, surface smoothness and so on, decreases a dust of glass powder, and does not generate gas from the binder, although it is formed integrally by needle punching. Also, a method of forming the same is provided.
In an aspect of the present invention, the above object is achieved by providing a glass wool molded product comprising a layered body of glass wool, characterized in that
the layered body does not contain any binder,
the layered body is needle punched in a direction orthogonal to a longitudinal direction of the wools thereof, so that the layered body is integrally formed,
the wools have an average diameter of 3 to 7 μm, and
each of the wools has a length between 10 and 200 mm.
Preferably, the molded product has a multilayer structure in the direction orthogonal to the longitudinal direction of the wools, and the average diameter of the wools of a first layer and that of the wools of a second layer differ from each other.
Preferably, the molded product has a multilayer structure in the direction orthogonal to the longitudinal direction of the wools, and a density of a first layer and that of a second layer differ from each other.
Preferably, the molded product is a hexahedron, and a hardened layer of an inorganic type adhesive agent is formed on at least one of surfaces of the molded product.
Preferably, a density of the molded product is between 70 kg/m3 and 110 kg/m3.
The above described molded product can be formed by supplying a layered body of glass wools having an average diameter of 3 to 7 μm and a wool length between 10 and 200 mm, said layered body including no binder, and needle punching the layered body in a direction orthogonal to a longitudinal direction of the wools, to molding the molded product. When the molded product has a hardened layer of adhesive agent, such molded product is formed by subsequently applying an inorganic type adhesive agent to at least one of surfaces of the molded product, and heat-setting the applied inorganic type adhesive agent.
According to the present invention, the average diameter of the glass wools (short glass fibers) is not less than 3 μm. When glass fibers or glass wools having a small diameter are formed from molten glass, the obtained glass fibers tend to be short. Since the average diameter of the glass fibers or wools is 3 μm or more, the fibers or wools are not too short, so that the fibers or wools can be sufficiently interlaced one another by needle punching, so as to obtain the molded product showing a sufficiently high degree of strength in use. Additionally, since the fibers or wools are not too short, it can be prevented from the fibers or wools from being directed to the reciprocating direction of the needle in the needle punching. Thus, it is possible to obtain the molded product showing a low thermal conductivity.
According to the present invention, the average diameter is 7 μm or less. Therefore, the glass fibers or wools are highly resilient, and prevented from being broken during needle punching. Broken fibers decrease the interlace of fibers. Such situation can be prevented according to the present invention, so as to provide the molded product having a sufficient operating strength. Additionally, it is possible to prevent a dust of glass from arising due to broken glass fibers. Since the interlace is prevent from being decreased, the molded product shows a low thermal conductivity.
Additionally, in order to make the average diameter of the glass fiber or wool less than 3 μm, a flow of fire flames having remarkably high temperature is necessary, so as to remarkably increase the fuel cost. Since the present invention does not use glass fibers having such small diameter, the fuel cost can be prevented from increasing.
According to the present invention, the length of the fibers or wools is 10 mm or more. Thus, the fibers or wools are sufficiently interlaced with one another, to provide the molded product with an improved shape-retaining effect and a strength that is satisfactorily high for handling. Additionally, since the fibers or wools are sufficiently interlaced with one another, the molded product shows a low thermal conductivity. If the fiber length is too small, an amount of dust of glass fibers is increased. The present invention prevents the amount of the dust from being increased.
According to the invention, the length is 200 mm or less. Since the short glass fibers (glass wools) are not too long, the number of fibers (glass wools) per unit volume is not decreased. In other words, sufficient glass fibers or wools are included in molded product. Therefore, the molded product shows a uniform density distribution of glass fibers (wools), so as to show a low thermal conductivity.
Since the fibers or wools of the present invention have the average diameter and the length as described above, the short glass fibers or glass wools are highly resilient, and the dust generating ratio is low. According to the prior molded product, the dust generating ratio is 0.9 to 1.7 wt % in the repetitive compression test. According to the present invention, the ratio is reduced to 1/1.5 to 1/3 in value.
Still additionally, no binder is used for the molded product in the present invention. Therefore, unlike known glass wool molded products, the molded product does not give rise to any adverse effect of gasification of a binder, even if it is used in a hot and/or vacuum atmosphere.
Preferably, the molded product has a multilayer structure in a direction orthogonal to the longitudinal direction of the wools, and the average diameter of the fibers or wools of the first layer and that of the second layer differ from each other. Due to the layer formed by fibers or wools having larger diameter, the surface of the molded product is smooth and hard, so that the molded product is highly handleable. The layer formed by fibers or wools having smaller diameter shows a low thermal conductivity. Thus, according to the present invention, it is possible to provide the molded product showing a low thermal conductivity and having the smooth and hard surface.
Preferably, the molded product has a multilayer structure in a direction orthogonal to the longitudinal direction of the fibers (wools) thereof, and the density of the first layer and that of the second layer differ from each other. The molded product shows the lowest thermal conductivity when the density is about 90 kg/m3. On the other hand, the higher is the density, the harder is the molded product, so as to improve handleable and to show an excellent surface smoothness.
With the above described constructions, it is possible to provide the molded product having an excellent thermal conductivity and, at the same time, good surface characteristics (including a level of surface hardness good for handling and a favorable level of surface smoothness).
Preferably, a hardened layer of an inorganic type adhesive agent is formed on at least one of the surfaces of the molded product. Thus, the present invention provides the molded product having not only good thermal conductivity but also good surface smoothness and hardness. In addition, since the inorganic type adhesive agent is used, the molded product can withstand an operating environment where it is exposed to high temperature above 400° C.
Preferably, the density of the molded product is between 70 kg/m3 and 110 kg/m3. As described above, the molded product shows the lowest thermal conductivity when the density is about 90 kg/m3. Therefore, when the density is found within the above range, it is possible to provide the molded product showing a low thermal conductivity.
The above described molded product can be easily manufactured only by adding a needle puncher to a known glass fiber forming unit.
As shown in
As schematically illustrated in
The short glass fibers (glass wools) 1 are continuously collected on a fiber-collecting belt 7 to form a layered body 2. The layered body 2 is then fed to a needle puncher 9. The needle puncher 9 has a large number of needles 10. Each of the needles 10 is driven to move or reciprocate within a span equal to or longer than a thickness D of the layered body 2. The short glass fibers (glass wools) 1 are interlaced or interwound one another by the reciprocation of the needles 10, to form the glass wool molded product 4. A shape of the glass wool molded product 4 is retained without any binder.
A weight per unit area of the layered body 2 is, for example, 1.08 kg/m2, but the present invention is by no means limited thereto.
For example, ten (10) needles are driven into the layered body 2 per 1 cm2 for the purpose of the present invention. A processing speed (a moving speed of the belt 7) is, for example, 5 m/min. It is possible to prepare the glass wool molded product having a density of 90 kg/m3 under these conditions.
Subsequently, the molded product is cut to a desired length by means of a cutter Z.
As shown in
A number of needles 10 driven or inserted into the layered body 2 per unit area by the needle puncher 9 is between 5 and 40 needles per cm2, preferably between 5 and 20 needles per cm2. When the number of needles 10 exceeds 40 per cm2, a thermal conductivity of the molded product 40 becomes too high, although a density of the molded product 4 is raised. When the number of needles 10 is less than 5 per cm2, the fibers or wools are poorly interlaced one another, so as to decrease a tensile strength of the molded product 4, and so as not to obtain a commercially feasible molded product 4. Additionally, the density of the molded product 4 becomes too small, while a thermal conductivity of the molded product 4 becomes too high.
The average diameter of the short glass fibers (glass wools) 1 is between 3 μm and 7 μm, and the length of each short glass fiber (glass wools) 1 is between 10 mm and 200 mm.
When the average diameter falls below 3 μm, the lengths of the short glass fibers (glass wools) 1 inevitably become small at the time of fiber forming, using a flow of fire flames 5. Thus, the fibers or wools 1 poorly interlaced one another by the needle punching, so that it is impossible to obtain a sufficient shape-retaining effect for the molded product 4. Additionally, the glass fibers or wools are directed in Y-direction by the needle punching, so as to consequently raise the thermal conductivity and to decrease an insulating effect of the molded product 4.
On the other hand, when the average diameter exceeds 7 μm, the short glass fibers (glass wools) 1 lose their resiliency. Thus, many of the fibers (wools) 1 will be broken during the needle punching. Also, the fibers (wools) 1 will poorly interlaced one another, so that it is impossible to obtain the molded product 4 that shows the required shape-retaining effect. Additionally a large amount of dust of broken glass fibers will be produced.
When the length of each short glass fiber (glass wools) 1 is less than 10 mm, the fibers or wools will poorly interlaced one another, so that it is impossible to obtain the molded product 4 that shows a commercially feasible shape-retaining effect. On the other hand, the length exceeds 200 mm, a number of short glass fibers (glass wools) per unit volume is reduced, to by turn reduce the quantity of short glass fibers (glass wools) per unit volume. Thus, the density distribution of glass fibers or wools will become not uniform, and the thermal conductivity will rise up high in the molding product 4.
Normally, a dust generating ratio of ordinary short glass fibers in a repetitive compression test is between 0.9 and 1.7 wt %. On the other hand, the dust generating ratio of “excellent” short glass fibers (glass wools) is 1/1.5 to 1/3 of the above cited level. Short glass fibers (glass wools) having the average diameter between 3 and 7 μm and the lengths between 10 and 200 mm exactly show the dust generating ratio of such excellent short glass fibers (glass wools), and hence fall in the category of “excellent” short glass fibers (glass wools).
In
As seen from
On the other hand, the molded product of short glass fibers (glass wools) having the average diameter of 8.5 μm as represented by the curve A shows a very high thermal conductivity.
In
As seen from
The second embodiment of the molded product of short glass fibers (glass wools) according to the present invention has a multilayer structure where layers are laid one on the other in the Y-direction that is orthogonal to the longitudinal direction X of the fibers or wools. The average diameter of the fibers or wools of the first layer differs from that of the second layer. However, the present invention is by no means limited to two-layered multilayer structure. Additionally, the average diameter of the first layer may be same with that of the third layer.
The molded product of the second embodiment illustrated in
Alternatively, the molded product of the second embodiment may be manufactured by the method illustrated in
As illustrated in
According to the third embodiment of the present invention, the glass wool molded product has a multilayer structure where layers are laid one on the other in the Y-direction that is orthogonal to the longitudinal direction X of the short glass fibers (glass wools), where the density of the first layer is different from that of the second layer. However, the number of layers is by no means limited to two. The density of the first layer and that of the third layer may be equal to each other.
While the density of the layered body is differentiated by needle punching in the method of
Still alternatively, the molded product of the third embodiment may be manufactured by the method described below.
The molded product 4A having a three-layered structure illustrated in
A glass wool molded product normally is a hexahedron. A hardened layer may be formed by means of an inorganic adhesive agent on at least one of surfaces of the molded product.
The adhesive agents that can be used for the purpose of the present invention include inorganic type adhesive agents such as aluminum phosphate, aluminum sulfamate and aluminum sulfate. The molded product according to the invention can be provided with heat resistance of withstanding high temperature above 400° C. by using such an inorganic type adhesive agent.
For the purpose of the present invention, such adhesive agent is applied at a rate of 5 to 60 g/m2, preferably 5 to 30 g/m2.
When the rate is more than 60 g/m2, the manufacturing cost of the molded product will rise, and the thermal conductivity of the molded product will become too high. When the rate is less than 5 g/m2, the objective of improving the smoothness and the hardness of the surface is not achieved sufficiently.
The adhesive agent is applied to the layered body and set after the needle punching. In the method illustrated in
A sprayer, a roll coater or some other appropriate known means may be used for applying the above described adhesive agent.
An appropriate known means such as a hot roller or a hot plate may be used as the drying/setting apparatus. Preferably, such means can contact with the surface of the molded product 4 to press and/or heat the surface, because the surface of the molded product is hardened and smoothed.
The heating temperature for heating the adhesive agent is between 200° C. and 550° C., preferably between 250° C. and 500° C. When the temperature is lower than 200° C., the adhesive agent will be hardened imperfectly, and a rigid hardened layer will not be formed. Additionally, problems such as the one that the adhesive agent adheres to the hot roller or the hot plate being used for heating will arise. On the other hand, when the temperature is higher than 550° C., strength of adhesion will be reduced, and problems such as the one that the fibers and the adhesive agent become fragile.
Preferably, the above described molded product 4 has a density between 70 and 110 kg/m3.
As illustrated in
As described above, according to the present invention, it is possible to form a glass wool molded product by supplying a layered body of short glass fibers (glass wools) showing an average diameter between 3 μm and 7 μm, a length between 10 mm and 200 mm and not containing any binder, and then by needle punching the layered body in a direction orthogonal to a longitudinal direction of the fibers or wools. If the molded product has a hardened layer of an inorganic adhesive agent on at least one of surfaces thereof, an inorganic type adhesive agent is applied to at least one of the surfaces, and then the applied adhesive agent is heated and set. With such a method, it is possible to use a known glass fiber forming unit 8 with a wide scope of free choice to form the glass wool molded product.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-311355 | Sep 2003 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP04/12869 | 8/30/2004 | WO | 3/3/2006 |
