JPH11172594A - Noncombustible heat-resistant sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide non-combustible and heat-resistant sheets that have excellent incombustibility as well as smoothness and whiteness. SOLUTION: A slurry that mainly contains calcium carbonate whiskers or a combination of thereof with sepiolite as main materials is subjected to paper making. In order to increase the sheet strength, inorganic reinforcing fibers as Glass fibers may be added. Since this sheet is a sheet made of a substantially inorganic material made of calcium carbonate whiskers resistant to the temperature of >=600 deg.C, excellent incombustibility can be attained. In addition, fine and fibrous calcium carbonate whiskers constructs fine-grained homogeneous texture structure and gives excellent surface smoothness and whiteness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-combustible heat-resistant sheet used as a wall covering, a decorative board or various kinds of building materials, a core substrate such as a honeycomb, a gasket, a filter, and the like. More specifically, the present invention relates to a non-combustible heat-resistant sheet which is manufactured in a paper or cardboard shape by a papermaking method, that is, a paper-making method, and has excellent heat resistance as well as non-combustibility.

[0002]

2. Description of the Related Art In recent years, there has been a great interest in sheets having special functions and characteristics called "functional papers" obtained by using a fibrous material other than pulp as a main material and forming it into paper or cardboard. And its research and development are being actively pursued. Non-combustible heat-resistant sheets that have a wide range of applications in fields where fire resistance or heat resistance is required, such as construction materials, are also one of them. Various new materials have been developed as new materials to replace asbestos (asbestos) sheets. It has also been proposed.

[0003] The typical one is mainly used as a heat-resistant filter, and is mainly made of glass fiber [Japanese Patent Publication No. 5-65634, Japanese Patent Publication No. 7-51].
No. 210, etc.]. Further, those using ceramic fibers such as alumina fibers, alumina-silica fibers, boron nitride fibers, and zirconia fibers as main materials are also typical [Japanese Patent Publication No. 2-60759, Japanese Patent Publication No. 6-377.
No. 60, Japanese Patent Publication No. 6-89518, etc.]. Furthermore, FRM
Etc. are mainly used as reinforcing materials, but those using fibrous potassium titanate as a main material [Japanese Patent Publication No. 4-5043]
No. 9], those mainly comprising silicon nitride or silicon carbide whiskers [Japanese Patent Publication No. 4-53994, Japanese Patent Publication No. 8-231]
No. 19] is also known.

[0004] Apart from these, the present applicant has developed and proposed a non-combustible heat-resistant sheet mainly composed of sepiolite, which is a hydrous magnesium silicate clay mineral [Japanese Patent Laid-Open No. 4-100993, etc.].

Further, the present applicant has also developed and proposed a non-combustible heat-resistant sheet mainly composed of a pulverized product of brucite, which is a magnesium hydroxide mineral, in the form of plate-like particles [JP-A-7-268796, etc].

[0006]

As described above, a non-combustible heat-resistant sheet as a functional paper which is substantially made of an inorganic material and has both non-combustibility and heat resistance has heretofore been mainly composed of various inorganic materials. Are being developed.

[0007] Among them, in particular, the non-combustible heat-resistant sheet mainly composed of sepiolite is a fibrous form of sepiolite, which has excellent consolidation properties, so that a high-strength paper sheet can be obtained. Since sepiolite has sintering properties, it has a feature that even when heated strongly due to a fire or the like, its original shape can be favorably maintained without collapsing the sheet. In addition, the non-combustible heat-resistant sheet using brucite composed of plate-like particles as a main material has excellent fire resistance due to its self-extinguishing properties, because the brucite, which is a magnesium hydroxide mineral, has a dehydrating and endothermic effect by thermal decomposition. In addition, by being in the form of plate-like particles, there are features such as obtaining excellent smoothness and whiteness of the sheet surface.

[0008] Although these sepiolites and brucites are all natural products and inexpensive materials, it is difficult to always obtain good quality.
These resources themselves are also limited. Therefore, for the inorganic material used as the main material of the non-combustible heat-resistant sheet,
The search and development of new materials to replace them were required.

In search of such a new material, the present inventors have developed calcium carbonate, which has been developed for use as a plastic reinforcing material (filler) or heat-insulating filler, and has recently been industrially put to practical use. Focusing on CaCO ₃ whiskers (whiskers), as a result of repeated tests and examinations, the use of this as the main material of the non-combustible heat-resistant sheet has not only excellent heat resistance, but also particularly excellent surface smoothness and It was found and confirmed that whiteness was obtained.

Therefore, an object of the present invention is to provide a novel non-combustible heat-resistant sheet having excellent surface smoothness and whiteness as well as flame retardancy.

[0011]

Specifically, a non-combustible heat-resistant sheet according to the present invention uses the above-mentioned calcium carbonate whisker as a main material,
This is made into a sheet by a papermaking method,
A slurry containing calcium carbonate whiskers as a main material and an organic binder added to the slurry.

Here, the whisker of calcium carbonate is
In the gas-liquid reaction for carbonating calcium hydroxide Ca (OH) ₂ , it is obtained by controlling the reaction conditions and growing crystals only in a certain direction. Unlike acicular calcium carbonate (argonite type), and heavy calcium carbonate in the form of irregular spherical particles, it is generally 0.1%.
15 to 40 μm for a short diameter (thickness) of 3 to 1.5 μm
In the form of a fine fiber having a long diameter (length). The calcium carbonate whisker decomposes into calcium oxide CaO at a high temperature, and its decomposition temperature exceeds 600 ° C.

Therefore, the calcium carbonate whisker which is in a fibrous state has a good mutual binding property (entangling property) and a good papermaking property.
The sheet can be formed into a sheet only by using a small amount of the organic binder, and a non-combustible heat-resistant sheet having excellent non-combustibility and heat resistance can be obtained. In addition, since calcium carbonate whiskers are in the form of fine short fibers, a fine-grained and uniform tissue structure is formed by papermaking.
Excellent surface smoothness and whiteness (opacity) can be obtained.

Further, the non-combustible heat-resistant sheet of the present invention may be formed by forming a slurry containing calcium carbonate whiskers and sepiolite as main materials and adding an organic binder. Thereby, the shape retention of the sheet when heated at a high temperature can be favorably secured by the self-sintering property of sepiolite.

Further, the non-combustible heat-resistant sheet of the present invention can be formed so as to further include inorganic reinforcing fibers such as glass fibers. That is, reinforcing fibers are further added to the above slurry, and a slurry containing the reinforcing fibers can be formed. Thereby, a stronger non-combustible heat-resistant sheet can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the non-combustible heat-resistant sheet of the present invention is used to form a slurry containing calcium carbonate whiskers as a main material and containing an organic binder, or a slurry further containing inorganic reinforcing fibers. It is made. Except for using calcium carbonate whiskers as a main material, it is technically basically the same as a conventional non-combustible heat-resistant sheet.

Here, any calcium carbonate whiskers can be used, but those having a relatively large aspect ratio are more preferable. Specifically, those having a minor axis (thickness, average) of about 0.3 to 1.5 μm and a major axis (length, average) of about 15 to 40 μm can be used. However, it is more preferable that the short diameter is 0.5 to 1.0 μm and the long diameter is 20 to 30 μm.
And the aspect ratio is preferably about 20 to 30.

A part of the calcium carbonate whisker can be replaced with another inorganic material as long as its properties are not impaired. And, as such an inorganic material, a colloidal silica that is effective for increasing the sheet strength and also for improving the whiteness, further improving the smoothness of the surface, and enhancing the soft feeling, a synthetic swelling mica or a synthetic smectite, Furthermore, aluminum hydroxide, hydrous calcium borate, sepiolite, brucite and the like used in conventional flame-retardant sheets can be exemplified. However, except for the case of sepiolite, the use ratio of these inorganic materials is generally preferably within 10% by weight so as not to impair the excellent characteristics of calcium carbonate whiskers.

However, in the case of sepiolite, which is a fibrous hydrated magnesium silicate mineral, its shape can be maintained even when the sheet is heated at a high temperature due to its self-sintering property. Therefore, 30 to 70% by weight of the calcium carbonate whisker can be replaced by the sepiolite, that is, the calcium carbonate whisker and the sepiolite can be combined as the main material, whereby
In addition to excellent heat resistance, excellent smoothness and whiteness can be obtained.

In the present invention, an inorganic reinforcing fiber can be further used to increase the strength of the sheet. Examples of the reinforcing fibers include glass fibers, carbon fibers, ceramic fibers such as silica-alumina, and rock wool fibers.
It can be used with a fiber length of the order.

[0021] These inorganic reinforcing fibers can be used basically in an arbitrary ratio, but have relatively high rigidity, so that the calcium carbonate whiskers maintain excellent smoothness of the sheet surface. Is preferably used in a small proportion. That is, specifically, a ratio of 3 to 20 parts by weight which does not exceed 20 parts by weight with respect to 100 parts by weight of the calcium carbonate whisker is preferable. More preferably, it can be used in a proportion of 5 to 15 parts by weight.

Further, in the non-combustible heat-resistant sheet of the present invention mainly comprising calcium carbonate whiskers which are fine fibers, an organic binder (paper) made of a high-molecular organic compound is used to bond them together to form a sheet. Force enhancer) is used. Examples of such a binder include natural products such as starch, denatured products thereof, and induced moving bodies, and more preferable are synthetic high molecular organic compounds, such as polyvinyl alcohol, polyethylene oxide, and the like.
Examples thereof include carboxymethyl cellulose, polyacrylamide, and other acrylic polymers, and urea-formaldehyde resin, melamine-formaldehyde resin, epoxidized polyamide resin, and methylolated polyacrylamide, which are thermosetting resins. These can be used alone or in an appropriate combination.Especially, for polyacrylamide and the like, preferably, the fixing property is enhanced, or the ionicity having the action as a retention agent or a coagulant is combined. That is, it is used as an anionic, cationic or amphoteric modified product (copolymer). As the organic binder, an acrylic or polyester-based synthetic resin emulsion can also be used. However, in general, the above-mentioned water-soluble type binder can be more preferably used.

This organic binder is used in a small proportion, such as the amount of addition, in order to ensure excellent incombustibility.
Specifically, the amount of the organic binder to be added is generally about 100% in terms of calcium carbonate whiskers (and reinforcing fibers).
Not more than 7.0 parts by weight to 0.5 to 7 parts by weight.
It can be used in a proportion of 0 parts by weight, and more preferably in a proportion of 1.0 to 5.0 parts by weight. In addition, since calcium carbonate whiskers are in a fibrous form and have good paper-making properties, sheets can be formed even with such a small amount of organic binder.

Using the calcium carbonate whiskers, the inorganic reinforcing fibers, and the organic binder, the non-combustible heat-resistant sheet of the present invention can be produced by a general paper-making method. That is, the raw materials are uniformly dispersed in water, and the aggregated flocs are formed, and a slurry preparation step of preparing a raw material slurry for papermaking, and the prepared slurry is filtered through a paper net. Papermaking by a paper machine, forming a wet sheet, and
Subsequently, the wet sheet can be manufactured by a step consisting essentially of a drying step of squeezing, dehydrating and then drying. In addition, as a paper machine, short net type, long net type,
Any type, such as a circular net type or a combination type, can be used, and as the netting, a mesh of about 60 to 90 mesh can be generally used. In addition, in the slurry preparation step, an inorganic coagulant such as a sulfuric acid band, or a polymer coagulant is appropriately added separately from the binder in order to form a good coagulated floc of the main material component. Can be. The sheet is generally made to have a thickness of about 0.15 to 1.0 mm or 80 to 200 in basis weight, depending on the specific use or the like.
g.

The non-combustible heat-resistant sheet of the present invention thus produced by papermaking has a composition substantially corresponding to the solid content composition of the slurry, and is substantially composed of inorganic material mainly composed of calcium carbonate whiskers. is there. Therefore, it has excellent incombustibility, and also has excellent surface smoothness and whiteness,
It has good appearance and printability or notation. Therefore, this flame-retardant sheet can be widely used in fields where fire resistance or fire resistance is required, and can be suitably used particularly as a base paper for a wall material or a surface material of a building material. Further, the non-combustible heat-resistant sheet may be further subjected to a water-repellent treatment with a silicone resin or the like, or a strengthening treatment by impregnation with an inorganic composition, whereby the use of the sheet can be further expanded. . Further, the non-combustible heat-resistant sheet may be fired in an oxidizing atmosphere to burn off the organic binder, thereby obtaining a sheet made of a completely inorganic material.

[0026]

[Example 1] Using the following materials, a non-combustible heat-resistant sheet of an example of the present invention was experimentally produced by a TAPPI hand-making apparatus. (Raw ingredients) Calcium carbonate whisker 100 parts by weight Anionic polyacrylamide 1.5 parts by weight Epoxidized polyamide resin 1.0 part by weight Here, the calcium carbonate whisker has a minor axis of about 0.7 μm.
m, a length of about 25 μm “Whiscal” (Maruo Calcium Co., Ltd.).

100 parts by weight of calcium carbonate whiskers were dispersed in about 2000 parts by weight of water, and the mixture was thoroughly stirred and uniformly dispersed. To this, the diluted anionic acrylamide was added and sufficiently stirred, and then the epoxidized polyamide resin was added and further stirred. As a result, a slurry in which the calcium carbonate whiskers were satisfactorily floculated was obtained without particularly using a flocculant.

Then, the slurry is made into a paper using a TAPPI hand-making apparatus using a 90-mesh net (20 × 25 cm), and the obtained wet sheet is dried under pressure at 100 ° C. by a heating press. A non-combustible heat-resistant sheet having a thickness of 0.265 mm (average of 10 sheets, the same applies hereinafter) and a basis weight of 132.4 g / m ² was obtained. In addition, the yield was about 65%.

This non-combustible heat-resistant sheet was excellent in smoothness and whiteness. In addition, when a flame of a gas lighter was applied to this sheet to perform a combustion test, smoke was slightly emitted from the area where the flame was applied, and the sheet slightly browned, but the surrounding area showed no change. I couldn't see it. That is, excellent incombustibility could be confirmed.

Example 2 A non-combustible heat-resistant sheet of another example of the present invention was produced in the same manner as in Example 1 except that reinforcing fibers were further added. (Raw ingredients) 100 parts by weight of calcium carbonate whisker 10 parts by weight of glass fiber 1.6 parts by weight of anionic polyacrylamide 1.1 part by weight of epoxidized polyamide resin 1.1 parts by weight of glass fiber is a papermaking fiber having a diameter of 9 μm and a fiber length of 6 mm. It was used.

The glass fibers were defibrated in advance using a mixer in the above amount, and dispersed in water together with calcium carbonate whiskers to form a uniform dispersion. Then
Anionic polyacrylamide as a binder and an epoxidized polyamide resin were sequentially added thereto to prepare a floc-formed raw material slurry. Then, in the same manner as in Example 1, the slurry was hand-made and hand-pressed to produce a nonflammable heat-resistant sheet.

The resulting non-combustible heat-resistant sheet has a thickness of 0.3
It had a basis weight of 149,2 g / m ² , a tensile strength of 1.34 kgf [tear length 0.60 km], and a tear strength (JIS P 8117) of 128 gf. In addition, the yield was about 67%.

Further, a nonflammability test of this sheet was performed. As in Example 1, excellent nonflammability was confirmed. In addition, the fired portion in the test showed more excellent strength than that of the sheet of Example 1 because of the glass fiber content.

Example 3 A non-combustible heat-resistant sheet of still another example of the present invention was prepared by replacing half the amount of calcium carbonate whiskers in Example 2 with sepiolite. (Raw ingredients) Calcium carbonate whisker 50 parts by weight Sepiolite 50 parts by weight Glass fiber 10 parts by weight Anionic polyacrylamide 1.6 parts by weight Epoxidized polyamide resin 1.1 parts by weight

A non-combustible heat-resistant sheet was prepared in the same manner as in Example 2 except that an equal mixture of calcium carbonate whiskers and sepiolite was used.

The resulting non-combustible heat-resistant sheet has a thickness of 0.3
25 mm, a basis weight of 145,8g / m ^2, also the tensile strength is 1.24Kgf [breaking length 0.57Km], tear strength (JIS P 8117) was 113Gf. In addition, the yield was about 65%.

Further, a nonflammability test of this sheet was conducted. As in Examples 1 and 2, excellent nonflammability was confirmed. Furthermore, when this sheet was heated and baked at 800 ° C., its shape was well maintained.

[0038]

As described above, the non-combustible heat-resistant sheet according to claim 1 comprises calcium carbonate whiskers as a main material and is formed by slurrying a slurry to which an organic binder is added. It is made of wood.

Therefore, according to the non-combustible heat-resistant sheet, since calcium carbonate whiskers which are in a fibrous form and have excellent mutual bonding (entanglement) are used as the non-combustible inorganic main material, organic The binder can be used in a small amount, such as an additive, so that
It can be substantially composed of an inorganic material mainly composed of calcium carbonate whiskers having a heat resistance of 600 ° C. or higher. Therefore, excellent flame retardancy can be obtained. In addition, since calcium carbonate whiskers are in the form of fine fibers, they can form a fine-grained and homogeneous sheet structure, thereby providing excellent smoothness and whiteness, and excellent sheet surface and printability. Can be obtained. That is, according to the non-combustible heat-resistant sheet, excellent non-combustibility and excellent surface smoothness and whiteness can be obtained.

Further, the non-combustible heat-resistant sheet according to claim 2 comprises calcium carbonate whiskers and sepiolite as a main material, and is made of a slurry to which an organic binder is added. It becomes.

Therefore, according to the non-combustible heat-resistant sheet, since sepiolite having sinterability is used as the main material, its shape can be well maintained even when heated under high heat. That is, it is possible to obtain not only excellent heat resistance but also excellent surface smoothness and whiteness.

Further, in the non-combustible heat-resistant sheet according to claim 3, the above-mentioned slurry further contains inorganic reinforcing fibers. Therefore, according to the non-combustible heat-resistant sheet, since inorganic reinforcing fibers are further contained, higher sheet strength can be secured without impairing non-combustibility.

Claims (3)

[Claims] 1. A non-combustible heat-resistant sheet substantially made of an inorganic material, comprising a slurry containing calcium carbonate whiskers as a main material and an organic binder added. 2. A non-combustible heat-resistant sheet substantially composed of an inorganic material, comprising a calcium carbonate whisker and sepiolite as main materials and a slurry to which an organic binder is added. 3. The non-combustible heat-resistant sheet according to claim 1, wherein the slurry further includes an inorganic reinforcing fiber.