JP2003292347A - Inorganic fiber layered body, method for manufacturing the same, and binder for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic fiber layered body bonded with a water glass-based binder, whose thermal durability, water resistance, flexibility, and durability are remarkably improved, and a method for manufacturing the same. <P>SOLUTION: The inorganic fiber layered body is characterized by being bonded with the water glass-based binder, where inorganic fibers inside the inorganic fiber layered body are bonded around their intersecting points with the water glass-based binder, and a film of the water glass-based binder is formed on the surface of the inorganic fiber layered body. The inorganic fiber layered body is manufactured by dipping a layered inorganic fiber in a water glass-based binder with a solid concentration of 1-15 wt.% and then drying it. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inorganic fiber laminate in which inorganic fibers are bound with a water glass binder, a method for producing the same, and a binder for the inorganic fiber laminate.

[0002]

2. Description of the Related Art In the case of forming a felt-like, board-like or any other molded article laminate from inorganic fibers such as glass fibers and ceramic fibers, the aspect ratio (length / thickness) should be as small as possible. Use larger mineral fibers. The reason is that, when the inorganic fibers are melted and stretched to form, the inorganic fibers have a circular cross-sectional shape and a smooth surface, and it is difficult to entangle the fibers. An organic binder is used to bond such inorganic fibers to each other or, in the case of forming it into a cloth, to seal it. On the other hand, even when inorganic short fibers are bonded to each other, the present situation is to use an organic binder regardless of the aspect ratio (length / thickness) of the fibers.

(Problems of Prior Art) However, the inorganic fiber laminate using such an organic binder has the following problems. When heat resistance is required, the heat resistance temperature of the organic binder, which is significantly lower than the heat resistance temperature of the inorganic fiber, is the safe use temperature of the inorganic fiber laminate. Specifically, when an inorganic fiber laminate is formed from glass wool, JIS states that the glass wool itself has a heat resistance of 600 ° C, but the safe use temperature is 300 ° C in accordance with the heat resistance of phenol resin. It was Further, even if the inorganic fiber laminate is used as a core material for vacuum heat insulation, it cannot be used because the degree of vacuum is lowered by the gas generated from the organic binder. In addition, cheap water-soluble phenolic resins are generally widely used as organic binders, but unreacted phenol and formalin resins are not used in the process of manufacturing inorganic fiber laminates because they are made from carboxylic acid and formalin as raw materials. Will be released into the atmosphere and wastewater, but a large-scale removal device was required to remove it. In particular, waste water that has been used to clean devices such as wire mesh in a line increases the increase in BOD and COD, and when using an explosive tank for purifying waste water, it has to be diluted with a large amount of water. In addition, since the heat insulating material for home electric appliances such as a microwave oven has a high temperature of 300 ° C., the organic binder is thermally decomposed to generate free formalin. In addition, since the unreacted phenol-free formalin is considered to be one of the causes of the thickness syndrome in the heat insulating material for general housing, a binder that is safe for the human body other than phenol is required. Moreover, since the organic binder was sprayed and applied to the laminated inorganic fibers, it was not possible to evenly attach the fibers one by one to the entire laminate. As a result, the inorganic fiber laminate has a problem in handleability because delamination occurs, or fibers or particularly imperfect fibers (shots) are released from the surface or cross section to cause tingling. In particular, when the inorganic fiber laminate is used as a heat insulating material or a sound absorbing material, free fibers are a problem, and it is necessary to treat the fibers so as not to scatter on the surface or cross section. For this reason, inorganic fiber-based sheets such as glass cloth and glass mat, metal-based sheets such as aluminum foil and aluminum foil lining, and organic and organic composite materials such as polyethylene film and aluminum-deposited resin-based film. A material or the like is attached to the cross section or the surface with an organic adhesive, the laminate is put in a bag, or the laminate is directly coated with a resin such as chloroprene. Since the adhesives and the like are also organic materials, it is necessary to set the safety temperature in accordance with an organic material that is significantly lower than the heat resistant temperature of the inorganic fiber. Alternatively, there is a possibility that a gas that may adversely affect the human body may be generated by thermal decomposition.

For the above reasons, water glass binders have been investigated as binders for inorganic fibers in place of water-soluble phenolic resins. However, when this water glass binder was attached to the inorganic fiber laminate, there were the following problems. That is, the water glass-based binder originally has a problem in water resistance such as being water-soluble and not resistant to moisture. Also, in order not to reduce the adhesive strength of water glass,
Conventionally, as a result of being adhered at a high concentration, in the drying process, the solid component of the water glass-based binder, by the time it migrates to the surface side of the inorganic fiber laminate together with moisture, inside the laminated inorganic fibers. The water glass binder shrinks and hardens. As a result, since the solid components of the water glass forming component and the inorganic fibers are fixed over a wide range with the internal stress left, the inorganic fiber laminate is inflexible and brittle, and can withstand slight deformation. could not. Furthermore, since the solid component of the water-glass-based binder, which is combined with the inorganic fibers in a wide range inside the inorganic fiber laminate, is strongly alkaline, it deteriorates the inorganic fibers, and there is a problem in durability of the inorganic fiber laminate. It was

[0005]

Therefore, in the present invention, the above-mentioned problems are solved, and an inorganic fiber laminated body bonded by a water glass-based binder having remarkably improved heat resistance, water resistance, flexibility and durability is obtained. It is an object to provide a manufacturing method thereof.

[0006]

[Means for Solving the Problems] In order to solve the above problems,
The method for producing an inorganic fiber laminate according to the present invention, as set forth in claim 1, wherein the laminated inorganic fibers have a solid content concentration of 1 to 15
It is characterized in that it is immersed in a wt% water glass based binder and then dried. The method for producing an inorganic fiber laminate according to claim 2 is the method for producing an inorganic fiber laminate according to claim 1, wherein the component of the water glass-based binder is M.
₂ O · nSiO ₂ (n = 2 to 30, M is an alkali metal,
Na, K, Li alone or in a mixed system thereof). The method for producing an inorganic fiber laminate according to claim 3 is the method for producing an inorganic fiber laminate according to claim 1 or 2, wherein the drying is air drying, hot air drying or high frequency heat drying, or these. It is characterized in that it is performed in combination. The method for producing an inorganic fiber laminate according to claim 4 is the method for producing an inorganic fiber laminate according to claim 3, wherein the drying is performed at a humidity of 65.
% Or less, and air drying or hot air drying at 0.2 m / sec or more is characterized. Further, in the inorganic fiber laminate according to claim 5, the inorganic fibers on the inner side of the inorganic fiber laminate are bound by a water glass-based binder mainly at the intersections of the inorganic fibers, and the surface of the inorganic fiber laminate is A coating film of the water glass-based binder is formed on. Further, the inorganic fiber laminate according to claim 6 is the inorganic fiber laminate according to claim 5, wherein a coating film of the water glass-based binder is also formed on the back surface of the inorganic fiber laminate. Characterize. In addition, claim 7
The inorganic fiber laminate according to claim 5 is the inorganic fiber laminate according to claim 5 or 6, characterized in that the coating film contains needle crystals. The inorganic fiber laminate according to claim 8 is the inorganic fiber laminate according to any one of claims 5 to 7, wherein the component of the water glass-based binder is M ₂ O · nSiO ₂ (n = 2 to 30, M is an alkali metal, Na, K, Li alone or in a mixed system thereof)
Is characterized in that. Further, the inorganic fiber laminate according to claim 9 is the inorganic fiber laminate according to any one of claims 5 to 8, wherein the inorganic fiber has a diameter of 7 μm.
It is characterized in that it is an ultrafine fiber of m or less. Further, the inorganic fiber laminate according to claim 10 is the inorganic fiber laminate according to any one of claims 5 to 9, wherein the inorganic fiber laminate is a vacuum heat insulating core material or a filter medium. Is characterized by. Further, the binder for an inorganic fiber laminate according to claim 11 is a water glass-based binder for binding the inorganic fibers of the inorganic fiber laminate, and the solid content concentration of the water glass-based binder. Is 1 to 15% by weight.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The inorganic fiber laminate of the present invention is produced by immersing laminated inorganic fibers in a water glass-based binder to adhere them, and then drying to bond the inorganic fibers together. As the inorganic fiber, glass fiber, rock wool, ceramic fiber or the like can be used. The fiber diameter needs to be 7 μm or less. This is because if it exceeds 7 μm, the voids per unit volume formed between the inorganic fibers become wide, the vacuum heat insulating property becomes low, and the collection efficiency as a filter medium for filters becomes poor. As a component of the water glass-based binder, M ₂ O · nSiO ₂ (n = 2 to 30, M
Is an alkali metal, such as Na, K, Li alone or a mixture thereof, which is obtained by filtering the alkali content of M ₂ O · nSiO ₂ with a permeation membrane, or the alkali content of M ₂ O · nSiO ₂ with an acid. Examples thereof include hydrated ones and one in which one of M in M ₂ O · nSiO ₂ is replaced with an alkaline earth metal.
The water glass binder has a solid content of 1 to 15% by weight.
And This is because if it is less than 1% by weight, the bonding between the inorganic fibers is weak and it is difficult to maintain the shape of the laminated body of the inorganic fibers. On the other hand, if it exceeds 15% by weight, a large amount of water glass-based solid component remains inside in the inorganic fiber laminate obtained by drying, so that the inorganic fiber is easily deteriorated by the solid component showing strong alkali. . In addition, the inorganic fibers are fixed at points other than the intersections of the inorganic fibers, and the obtained inorganic fiber laminate loses flexibility. Further, in order to dry the glass fiber to which the water glass binder is attached, either air drying, hot air drying, or heat drying using an electric furnace, a gas furnace or a high frequency heating furnace can be used. In the case of heat drying, water glass is foamed when dried at a high temperature of 130 ° C. or higher, so it is preferable to dry at less than 130 ° C. Further, during the above-mentioned drying, if dried rapidly, needle-like crystals such as sodium sesquicarbonate (Na ₂ CO ₃ NaHCO ₃ 2H ₂ O) will be generated on the surface of the inorganic fiber laminate. However, the surface of the resulting inorganic fiber laminate is lacking in smoothness.Therefore, when drying the inorganic fibers to which the water glass-based binder is attached, moisture is slowly absorbed from the surface side of the inorganic fiber laminate. Alternatively, it may be possible to gradually evaporate. For example, in the case of air drying or hot air drying, it is preferable that the air velocity is 0.2 m / sec or more in an atmosphere having a humidity of 65% or less, and more preferably,
It is preferable to dry at an air velocity of 1.0 m / sec in an atmosphere having a humidity of 40% or less.

[0008]

EXAMPLES Next, examples of the present invention will be described. Example 1 In this example, a water glass stock solution containing 9.3% by weight of sodium oxide and 28.4% by weight of silicon dioxide as a water glass binder (the molar ratio n of silicon dioxide and sodium oxide was 3.2). (N = the number of moles of silicon dioxide / the number of moles of sodium oxide). The solid content concentration was adjusted to 3.6% by weight, and the one having good heat resistance and water resistance was used. A layer of short glass fibers having a diameter of 2 μm as an inorganic fiber was cut into 12 mm × 190 mm × 250 mm square, and the weight per unit area was 760 g / m ² , soaked in a water glass binder and then taken out, punching metal A glass short fiber laminate was produced by sandwiching it between the plates together with a spacer having a thickness of 5.5 mm, pressing and dehydrating with a Schacoman, taking out, and heating and drying for 25 minutes in a high-frequency heating furnace with an output of 600 W. The upper limit of the heating temperature during drying was set to 125 ° C., and when the temperature was exceeded, the output of the microwave oven was reduced to 200 W, and when the temperature dropped to 120 ° C., the output was switched to 600 W to control the temperature. . Further, in this embodiment, the drying is performed by the high frequency heating furnace, but it may be dried by air drying or a combination of air drying and the high frequency heating furnace.

Observation of the front, middle and back surfaces of the obtained short glass fiber laminate by an electron microscope revealed that a water glass binder film was formed on the surface of the short glass fiber laminate from FIG. 1 and the glass from FIG. On the inner side of the short fiber laminate, it was found that the glass short fibers were bonded to each other with a water glass binder centering on their intersections. This is because the solid component of the water-glass binder solidifies at the intersections of the short glass fibers or the narrow gaps between the short glass fibers on the inner side in the process of drying and bonds the short glass fibers to each other, and the rest is glass together with water. It is considered that this is because the short fiber laminate moved to the surface side and solidified to form a film. As shown in FIG. 3, on the back surface of the short glass fiber laminate of the present example, water glass was immersed and dehydrated, and the short glass fiber laminate was placed directly on the glass plate, so that evaporation of moisture was observed on the back surface. Since it did not occur, it was found that the coating by the solid component of the water glass binder was not formed.

With this structure, the inside of the short glass fiber laminate has a relatively low sodium content, so that it has excellent water resistance and excellent durability with little deterioration of short glass fibers. Further, since the ratio of the portions where the glass short fibers are bonded to each other except the narrow gaps between the intersections of the glass short fibers or the narrow gaps between the glass short fibers is low, the elasticity of the glass short fibers is maintained even after solidification, which is excellent. It has flexibility. Further, since a coating film was formed on the surface side of the glass short fiber laminate by the solid component of the water glass binder, the surface strength of the glass short fiber laminate was high.
Regarding heat resistance, no change was observed even after heating at 650 ° C. for 30 minutes, and excellent heat resistance was obtained.

(Embodiment 2) Next, a filter material for a filter made of an inorganic fiber laminate which is another embodiment of the present invention will be described. In this example, the filter medium for filter was produced by air-drying instead of the high-frequency heating furnace of Example 1. That is, glass short fibers having a diameter of 2 μm are laminated as the inorganic fibers, and 12 mm × 190 mm × 250 mm
Cut into squares, weigh 190 g / m ² per unit area, soak in water glass binder, take out, sandwich with 5.5 mm thick spacer between punching metal plates, and dehydrate under pressure with Shakoman. Removed from the temperature 2
Under a condition of 0 ° C. and a humidity of 40% or less, the front surface and the back surface were hung and arranged so that an airflow of 0.7 m / s was parallel to each other, and dried until the weight became constant to produce a filter medium. In this embodiment, the drying is performed by air drying, but the drying may be performed by heat drying using a high frequency heating furnace or the like, or a combination of air drying and heat drying, as in the first embodiment.

Enlarged photographs of the front, middle and back surfaces of the obtained filter medium with an electron microscope are shown in FIGS. 4 to 6.
From FIGS. 4 and 6, it was found that a coating film made of the solid component of the water glass binder was formed on the front surface and the back surface of the filter medium. Furthermore, needle-shaped sodium sesquicarbonate (Na ₂ CO ₃ NaHCO ₃ 2H) is used on both the front and back surfaces.
It was found that crystals of ₂ O) were formed. Also,
From FIG. 5, it was found that the glass short fibers were bonded to each other on the inner side of the filter medium with the solid component of the water glass binder centering on the intersections thereof.

With this structure, the inside of the filter medium has a relatively small amount of sodium, so that it has excellent water resistance.
It has excellent durability with little deterioration of short glass fibers. Further, since the ratio of the portions where the glass short fibers are bonded to each other except the narrow gaps between the intersections of the glass short fibers or the narrow gaps between the glass short fibers is low, the elasticity of the glass short fibers is maintained even after solidification, which is excellent. It has flexibility. Further, since the coating film was formed on the front and back sides of the filter medium by the solid component of the water glass binder, the surface strength of the short glass fiber laminate was high. Also,
With respect to heat resistance, no change was observed even after heating at 650 ° C. for 30 minutes, and excellent heat resistance was obtained. Furthermore,
In the filter medium of this example, the coating on the front and back surfaces is sodium sesquicarbonate (Na ₂ CO ₃ · NaHCO _3).
It was found that the surface area can be increased and the dust collection effect was very excellent because it was formed so as to include needle-like crystals of (2H ₂ O).

(Embodiment 3) Next, a vacuum heat insulating core material made of an inorganic fiber laminate which is another embodiment of the present invention will be described. In this example, 1.1 wt% sodium oxide and 23.5 wt% silicon dioxide were used as the water glass binder.
The water glass stock solution (the molar ratio n of silicon dioxide and sodium oxide was 22) was diluted with water to a solid content concentration of 3.6% by weight. Diameter 5 as inorganic fiber
Using glass short fibers of μm, the glass short fibers are laminated and cut into 12 mm × 190 mm × 250 mm square, the weight per unit area is 760 g / m ^2, and the glass short fibers are immersed in a water glass binder and then taken out, It is sandwiched between punching metal plates together with a spacer having a thickness of 5.5 mm, pressurized and dehydrated with Schacoman, taken out, and heated by a high-frequency heater for 15 minutes, and further, the temperature is 20 ° C, the humidity is 40% or less, and the speed is 0.
Under a 7 m wind speed atmosphere, the core material for vacuum insulation was prepared by suspending it in parallel with the air flow and drying it until the weight became constant.

This vacuum heat insulating core material also has the same structure as that of the second embodiment. Since the inner side has a relatively small amount of sodium, it is excellent in water resistance and excellent in short glass fiber deterioration. It became durable. Also,
Since the ratio of the portions where the glass short fibers are bonded to each other except the intersections of the glass short fibers or the narrow gaps between the glass short fibers is low, the elasticity of the glass short fibers is maintained even after solidification, and the excellent flexibility is obtained. Has become. In addition, since the coating is formed on the surface side of the vacuum heat insulating core material by the solid component of the water glass binder, the surface strength of the glass short fiber laminate is high. Regarding heat resistance,
No change was observed even after heating at 650 ° C. for 30 minutes, and excellent water resistance was obtained. Moreover, this core material for vacuum heat insulation had good strength and feel, and was extremely excellent in workability. In this example, the fiber diameter of the glass short fibers was 3 μm.
However, if the fiber diameter is made thin, for example, 1 μm, the voids between the glass short fibers can be further increased to improve the heat insulating property. In addition, the glass short fibers of the present example used a felt in which the direction of the fibers generally manufactured was laminated in the horizontal direction, so that the fiber directions are random in advance, for example, by forming a floc-shaped fiber bundle. By using the laminated felt, it is possible to improve the compression (deformation) resistance especially under vacuum.

Although glass short fibers are used as the inorganic fibers in each of the above-mentioned embodiments, the present invention is not limited to this, and ceramic fibers, rock wool or the like may be used.

[0017]

As described above, according to the production method of the present invention, the water-glass binder of the present invention has a very low solid component concentration of 1 to 15% by weight for binding the laminated inorganic fibers. By using, it is possible to obtain an inorganic fiber laminate having excellent heat resistance, water resistance, durability, flexibility and surface strength, and having an extremely smooth surface and good handleability. Further, according to the inorganic fiber laminate of the present invention, it has excellent heat resistance, and even if it is used as a home electric appliance such as an electronic jar or a refrigerator, a packing material, an asbestos sponge substitute or a construction material, the organic binder is used. Since it is not used, it can be used as a heat insulating material with excellent safety.
Further, it can be used as a filter material such as a filter having a high collection efficiency by utilizing submicron needle-like crystals formed on the surface of the inorganic fiber laminate. Furthermore, since it has excellent surface strength and air permeability, it does not impair its function as a heat insulating material even in a high vacuum state.

[Brief description of drawings]

FIG. 1 is a micrograph (× 400) of the surface of an inorganic fiber laminate which is an example of the present invention.

FIG. 2 is a photomicrograph (400 ×) of the inside of an inorganic fiber laminate which is an example of the present invention.

FIG. 3 is a photomicrograph (400 times) of the back surface of the inorganic fiber laminate which is an example of the present invention.

FIG. 4 is a photomicrograph (400 times) of the surface of the inorganic fiber laminate which is one example of the present invention.

FIG. 5 is a photomicrograph (400 times) of the inner side of the inorganic fiber laminate which is an example of the present invention.

FIG. 6 is a photomicrograph (400 times) of the back surface of the inorganic fiber laminate which is an example of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeyuki Horisaki             1-36-8 Matsubara Setagaya-ku, Tokyo Co., Ltd.             Within Japan Insultec F-term (reference) 4F100 AA00B AA40A AA40B AA40K                       BA02 DG01B EJ82B GB56                       JB07 JJ03 JK12 JK17 YY00B                 4G060 BA05 BC00 BC03 BC04 BD15                       CA01 CA21

Claims (11)

[Claims] 1. The laminated inorganic fibers have a solid content concentration of 1 to 1.
A method for producing an inorganic fiber laminate, which comprises immersing in a 15 wt% water glass-based binder and then drying. 2. The component of the water glass-based binder is M ₂ O.
NSiO ₂ (n = 2 to 30, M is an alkali metal, N
a, K, Li alone or in a mixed system thereof), The method for producing an inorganic fiber laminate according to claim 1, wherein 3. The method for producing an inorganic fiber laminate according to claim 1, wherein the drying is performed by air drying, hot air drying, high frequency heating drying, or a combination thereof. 4. The method for producing an inorganic fiber laminate according to claim 3, wherein the drying is air drying at 0.2 m / sec or more or hot air drying in an atmosphere having a humidity of 65% or less. 5. The inorganic fiber on the inner side of the inorganic fiber laminate is bound mainly by an intersection of the inorganic fibers with a water glass based binder, and the surface of the inorganic fiber laminate is coated with the water glass based binder. An inorganic fiber laminated body characterized by being formed. 6. The inorganic fiber laminate according to claim 5, wherein the back surface of the inorganic fiber laminate is also coated with the water glass binder. 7. The inorganic fiber laminate according to claim 5, wherein the coating contains needle crystals. 8. The component of the water glass-based binder is M ₂ O.
NSiO ₂ (n = 2 to 30, M is an alkali metal, N
a, K, Li alone or in a mixed system thereof), The inorganic fiber laminate according to any one of claims 5 to 7. 9. The inorganic fiber laminate according to claim 5, wherein the inorganic fiber is an ultrafine fiber having a diameter of 7 μm or less. 10. The inorganic fiber laminate according to claim 5, wherein the inorganic fiber laminate is a vacuum heat insulating core material or a filter media. 11. A water glass binder for binding inorganic fibers of an inorganic fiber laminate, wherein the water glass binder has a solid content concentration of 1 to 15% by weight. Binder for inorganic fiber laminates.