JPH0342359B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to paperboard constituting gypsum board, and particularly to noncombustible gypsum board paperboard forming the surface of fire-resistant gypsum board. In recent years, building materials are particularly required to have fire resistance, and gypsum board is generally widely used as a fire-resistant interior material for buildings. Gypsum board is usually obtained by pouring a calcined gypsum slurry between two sheets of paperboard, forming it into a plate shape, curing, and drying it. It is made of a plaster core and paperboard glued together. However, gypsum boards made in this way had the disadvantage that in the event of a fire, the gypsum core itself was non-combustible, but the surface paperboard was combustible. In addition, in recent years, attempts have been made to make gypsum board, like other interior materials, smokeless in the event of a fire and to prevent the generation of toxic gases such as carbon monoxide. In order to solve these problems, for example, as described in Japanese Patent Publication No. 50-8457, non-combustible asbestos-mixed paper made by mixing asbestos fibers into pulp was used as paperboard for gypsum boards. Fire-resistant gypsum board has recently been widely used. However, according to the results of asbestos-related health damage surveys of workers involved in a wide range of asbestos-related activities in various countries, it has become a social problem that lung cancer or mesothelioma frequently occurs in workers exposed to asbestos dust. There is. As a result, there is a strong demand for the introduction of substitutes for various asbestos products. Furthermore, when painting plasterboard using the above-mentioned non-combustible asbestos-mixed paper, the coating of the paint was often uneven. For example, with roller coating, in which the paint is applied by passing it between rollers, color unevenness is more likely to occur than with conventional plasterboard using plain paperboard, and it is difficult to obtain plasterboard with a desirable appearance. Ta. The present inventors have found that they can overcome the disadvantages of paperboard for gypsum board using asbestos (namely, the risk of harming health and the inability to obtain a good paint surface), and also have sufficient fire resistance. We have conducted intensive research on paperboard for plasterboard. As a result, they discovered that the above problems could be solved by using wollastonite as a nonflammable inorganic material and making the surface layer of cellulose fibers, thereby completing the present invention. That is, the first aspect of the present invention is a paperboard for gypsum board having a total basis weight of 200 to 380 gr/ ^m2 consisting of a surface layer, a middle layer, and a back layer, in which the surface layer and the back layer each have a basis weight of 30 to 57 gr/m2. ^m2 and 40~76gr/ ^m2 ,
Consisting of cellulose fibers with no wollastonite mixed therein, the middle layer having a basis weight of 130 to 247gr/m ² and consisting of cellulose fibers mixed with wollastonite in an amount of 25 to 55% of the total basis weight. A non-combustible paperboard for gypsum board. The wollastonite-mixed gypsum board paperboard of the present invention consists of three layers conveniently separated by those skilled in the art: a surface layer, a middle layer, and a back layer. However, when forming a gypsum board, the layer that comes into direct contact with the gypsum is the back layer, and the layer that forms the outer surface of the gypsum board is the surface layer. The surface layer is made of cellulose fibers and is not mixed with wollastonite. The middle layer consists of 38.5 to 84.6 parts by weight of wollastonite and 61.5 to 15.4 parts by weight of cellulose fibers. The back layer is made of cellulose fibers that do not contain a sizing agent and is not mixed with wollastonite. The basis weight of the entire paperboard, ie, the basis weight of the paperboard consisting of the front layer, middle layer and back layer, is 200 g/m ² or more, and desirably 380 g/m ² or less considering economic efficiency. Also, within this overall basis weight of 200 to 380 g/ ^m2 , the basis weight of the surface layer should be 30 to 57 g/m2, and the basis weight of the middle layer should be 30 to 57 g/ ^m2 .
It is preferable that the basis weight of the backing layer is 130 to 247 g/m ² and the basis weight of the back layer is 40 to 76 g/m ² . Furthermore, depending on the basis weight of each type (in the case of the present invention, the basis weight is approximately proportional to the thickness of the layer), one or more of the desired layers of the top layer, the middle layer and the back layer may be plied together. layers, typically 4 in total
It can be a laminated paperboard consisting of ~8 layers. The overall thickness of the paperboard is generally 0.3 to 0.6 mm. Examples of the shape of the wollastonite used in the present invention include fibrous, long columnar, plate-like, and granular shapes, with fibrous shapes being particularly desirable. In addition, the mixing ratio of wollastonite is 25% to 55% of the total basis weight considering fire resistance and economic efficiency.
% range is desirable. In the surface layer, 100 parts of cellulose fiber (parts by weight,
(The same applies hereinafter), 0.1 to 2 parts of a sizing agent can be added (when applied by a calender in the papermaking process, a surface sizing agent of 0.1 to 2 g/m ² can be applied). Abrasion resistance can be imparted to the paperboard by the addition of sizing agents. In addition, in the middle layer, for example, 1 to 10 parts of anionic synthetic rubber latex, 0.05 to 1 part of cationic polyelectrolyte, and 0.1 to 2 parts of rosin sizing agent per 100 parts of total of wollastonite and cellulose fibers.
parts, and 2 to 10 parts of sulfuric acid can be added.
These additives have the effect of improving the fire resistance, strength, etc. of paperboard. The above-mentioned anionic synthetic rubber latex is mainly used as a binder for wollastonite. Specific examples thereof include styrene-butadiene rubber latex (SBR), acrylonitrile-butadiene copolymer synthetic rubber latex (NBR), and isoprene rubber latex. Further, the above-mentioned cationic polyelectrolyte is mainly used for promoting the coagulation and fixation of anionic synthetic rubber latex or wollastonite, or for the purpose of improving the yield of cellulose fibers. 3rd grade kachikon

[Formula] Mannitz reaction-generated polymer (tertiary cationic polymer), 4
class cation

〔Effect of the invention〕

As is clear from Table 1, there is no difference in adhesiveness and bending strength between the gypsum boards using the paperboards of Examples 1, 2 and Comparative Example 1, especially when wollastonite is mixed in the backing layer 3. (Example 2), there was no difference in these physical properties, and all were good. As is clear from Table 2, although the surface layer 1 is made of cellulose fibers, the gypsum boards using the paperboard of Examples 1 and 2 have a higher fire resistance than the gypsum board using asbestos of Comparative Example 1. There were no differences and the results were good. As a result, the gypsum board using the paperboard for gypsum board of the present invention had sufficient nonflammability. Table 3 showing the results of the coating test using roller coating
A significant difference was observed between Examples 1 and 2 and Comparative Example 3. That is, a gypsum board using the paperboard for gypsum board of the present invention could be coated uniformly, and the resulting coated surface was good with no unevenness. In particular, even in the case of the gypsum board using the paperboard of Example 2, which had poor surface smoothness, the coating was uniform and the painted surface was good with no unevenness.

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Claims (1)

[Claims] 1. The total basis weight consisting of the surface layer, middle layer, and back layer is 200 to 200.
In 380gr/ ^m2 plasterboard paperboard, the surface and back layers have basis weights of 30~57gr/ ^m2 and 40~, respectively.
It is 76gr/ ^m2 and is made of cellulose fiber with no wollastonite mixed in, and the middle layer has a basis weight of
A noncombustible gypsum board paperboard having a weight of 130 to 247 gr/m ² and comprising cellulose fiber mixed with wollastonite in an amount of 25 to 55% of the total basis weight. 2 Total basis weight consisting of surface layer, middle layer and back layer is 200~
In 380gr/ ^m2 plasterboard paperboard, the surface layer is
Its basis weight is 30 to 57gr/m ² and is made of cellulose fibers without wollastonite mixed therein, and the middle layer and back layer are each made of cellulose fibers mixed with wollastonite and have a basis weight of 130 to 247gr/m ² and 40
~76gr/ ^m2 , and the total amount of wollastonite contained in the middle layer and back layer is 25 to 55% of the total basis weight, and the amount of wollastonite contained in the back layer is 25% to 55% of the total basis weight. A noncombustible gypsum board paperboard characterized by having a basis weight of 75% or less.