JP2909827B2 - Cellulose-based flame-retardant bulky processed sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cellulosic flame retardant which is particularly preferably used as a wallpaper used in building interior materials such as wall materials and ceiling materials requiring flame retardancy and safety. Provided is a bulky processed sheet.

[Conventional technology and its problems] Conventionally, a widely used interior material for wallpaper and the like having excellent decorativeness and processability is to heat a vinyl chloride resin compound added with a plasticizer, a flame retardant, a foaming agent, and the like. It is manufactured by foaming and embossing.

Since such interior materials are mainly made of vinyl chloride resin, they do not absorb moisture and have no humidity control function, especially when used as wallpaper. The woody portion of the wood is easily damaged and easily deteriorates.

Further, when a fire occurs in a building in which such an interior material is used, there is a problem that a large amount of smoke is generated and a large amount of a halogen-based compound gas is generated. On the other hand, some cellulose-based processed paper is used as wallpaper, but these have almost no bulkiness, and it is difficult to give a high three-dimensional pattern.

[Problems to be Solved by the Invention] An object of the invention is to have excellent flame retardancy, retain moisture absorption, that is, have a humidity adjustment function, maintain strength, and emit smoke during combustion.
An object of the present invention is to provide a building material which is highly safe in terms of generated gas, can be subjected to printing, embossing, and the like, and has a high degree of three-dimensional decorativeness and functionality, and is particularly suitable as a wallpaper.

[Means for Solving the Problems] The present invention achieves the above-mentioned object, and its gist is as follows.

(1) Crosslinked pulp 54 to 60% by weight and composite heat-fusible fiber 18 to
20% by weight and 5 to 10% by weight of polyvinyl alcohol fiber are mixed to make paper, and a flame retardant selected from ammonium polyphosphate or guanidine sulfamate is 15 to 21.
Cellulose-based flame-retardant bulky processed sheet obtained by flame-retardant treatment by weight%.

(2) The first (1), wherein the heat-fusible fiber is a composite of two or more thermoplastic polymer fibers having different melting points.
A bulky processed sheet according to the above item.

(3) Crosslinked pulp 54 to 60% by weight and composite heat fusible fiber 18 to
20% by weight and 5 to 10% by weight of polyvinyl alcohol fiber are mixed to make paper, and a flame retardant selected from ammonium polyphosphate or guanidine sulfamate is 15 to 21.
A method for producing a flame-retardant bulky processed sheet, characterized in that a flame-retardant treatment is carried out at a weight percentage, followed by heating and pressurizing treatment in a wet state, followed by drying and heating and embossing.

(4) The method for producing a bulky processed sheet according to the above (3), wherein embossing is performed at a temperature equal to or lower than the softening point of the high melting point polymer forming the heat-fusible fiber.

The flame retardancy can be imparted to the cellulose-based flame-retardant bulky processed sheet of the present invention by any of the following three methods.

First, a sheet made from crosslinked pulp, heat-fused fibers and a binder is treated with a flame retardant solution and / or a flame retardant dispersion solution.

Second, a flame retardant that is insoluble in water is added and adhered during papermaking.

Thirdly, there is a method in which the bulky pulp itself is made flame-retardant and mixed with the heat-fusible fiber to make paper.

Of course, two or more of the above three methods may be used in combination.

As the flame retardant used in the present invention, in the above-mentioned first method, a water-soluble flame retardant effective mainly for a cellulosic material is used. That is, an ammonium salt, an amine salt, a guanidine salt of an organic or inorganic acid having flame resistance,
Examples of the acid include phosphoric acid, polyphosphoric acid, sulfuric acid, sulfamic acid, imidodisulfonic acid and the like.

These flame retardants are used by dissolving them in water.However, an amount exceeding their solubility can be dispersed in water.In such a case, the material is converted into a slurry, but the material is treated with the uniformly dispersed slurry. Can be attached to make it flame-retardant.

However, since these are water-soluble salts, there are problems such as difficulty in obtaining a product sheet sizing degree and reduction of the flame retardant effect by washing with water, and using water or a solvent other than water to prevent this. The above-mentioned sheet can be treated with a material obtained by dissolving or dispersing an insoluble flame retardant into the above-mentioned material to make it flame-retardant.

Examples of such water-insoluble flame retardants include alkyl phosphates, aryl phosphates, alkyl aryl phosphates, and halogenated phosphates. However, halogenated phosphoric acid esters are effective, but are not preferable in this respect because they contain halogen.

In the above-mentioned second method of flame retardation, it is preferable to use a water-insoluble flame retardant, and a poorly soluble flame retardant can be used. In addition, a soluble or hardly soluble flame retardant itself may be surface-treated or encapsulated to make it insoluble and used for the flame retardant treatment.

As such a flame retardant, highly condensed ammonium polyphosphate, guanidine polyphosphate, co-condensed ammonium phosphate and urea or a condensable compound such as urea phosphate and melamine, dicyandiamide, and the like are effective. Soluble ones are encapsulated as described above and used as insoluble.

Zinc borate, antimony oxide, boric acid, borax,
Aluminum hydroxide and magnesium hydroxide can be used in the same manner, but the amount used must be slightly increased, and is not the most preferred flame retardant.

In the third method of flame retarding, a reactive flame retardant is used. Those which react with cellulose fibers or react with other compounds to entangle with cellulose fibers to make them flame-retardant are used. Examples of such a flame retardant include tetrakisphosphonium salt, N-methyloldimethylphosphonopropionamide (vinyl phosphonate oligomer by Stoffer) and the like.

However, the reactive flame retardant is also applied to the first method, that is, a method of treating a sheet prepared by cross-linking pulp and heat-fusible fibers, and also in this case, a flame retardant having excellent durability. Become.

In some cases, the flame retarding method can be carried out by combining any two or more of the first, second and third methods, and can be used in the preparation of a sheet by using a heat-fusible fiber which has been made flame retardant in advance. Methods that reduce the amount of flame retardant that is used are also useful.

The crosslinked pulp used in the present invention is produced by reacting a pulp crosslinking agent as described later in detail.

The crosslinked pulp in the present invention has a crosslinked structure in which the crosslinking agent reacts with the hydroxyl group in the cellulose to form a crosslinked structure. Unlike ordinary valve fibers, the degree of bonding between the valve fibers by hydrogen bonding is small and the strength is significantly reduced. . For this reason, in the present invention, a separate binder is required.

Examples of the binder include starch, polyvinyl alcohol and the like dissolved in water, polyvinyl alcohol powder dispersed in water, and an adhesive polymer emulsion, latex, i.e., SBR, NBR, natural rubber, and acrylic. And vinyl acetate polymers and copolymers. There are water-dispersible binders such as polymers modified with carboxyl groups, hydroxyl groups, amino groups, epoxy groups, etc., and polyvinyl alcohol-based fibrous binders, and water-dispersible binders are also effective. Can be used, but the strength is insufficient, or part of the used material leaks into drainage,
There are drawbacks such as a large cost required for processing.

For the purpose of the present invention, fibrous binders, particularly hot water-soluble fibers, are preferred. The fibers are mixed with crosslinked pulp and heat-fusible fibers, and heated under a slight pressure in a wet state. The hot-water-soluble fibers function as an adhesive, and a sheet having extremely high strength can be obtained.

Here, the hot-water-soluble fiber hardly dissolves in water at room temperature and maintains its fiber form, but when heated on the dryer surface after papermaking, it starts to dissolve easily, and at that moment equipment such as a touch roll When it is pressurized, it becomes a fibrous binder astride between the main fibers, and then re-solidified by dehydration and drying, and becomes a strong paper layer constituting fiber which cannot be easily separated unless it is in high-temperature water.

A typical fibrous binder is a fibrous binder for PVA. Usually, PVA fiber is cut short and only swells in water at room temperature but does not dissolve, but it dissolves in water at 60-90 ° C or higher and becomes a binder.

Commercially available hot water soluble PVA fiber brands include those having a water dissolution temperature of 60 ° C, 70 ° C, and 80 ° C.

The term "water dissolution temperature" used here means that one end of the aligned fiber bundle is suspended at normal temperature in water at a load of 1/500 g / d and the water temperature is raised at a rate of about 2 ° C per minute. The temperature at which the fiber is melted and cut.

The dissolution temperature in water actually indicates, in the case of papermaking, approximately the temperature at which the wet paper is heated by the dryer and the binder fibers exhibit an adhesive function.

The hot water-soluble fiber does not necessarily need to be completely dissolved by heating in water, nor does it need to have a uniform composition that dissolves at the same temperature. Rather, a composite of different solubility and other physical properties often has a favorable effect on strength and the like.

The greater the proportion of hot water-soluble fibers blended in the sheet of the present invention, the greater the strength, but the resulting sheet becomes hard and unfavorable in texture. On the other hand, when the amount is small, the required strength cannot be obtained. Therefore, the mixing ratio of the hot water-soluble fiber in the raw material mixture is required to be 1% or more by weight and preferably in the range of about 30%.

As a polymer fiber having adhesiveness to pulp, there is a polyvinyl alcohol-based fiber as described above,
The dissolution temperature can be controlled by the degree of polymerization and the degree of crosslinking.

As the heat-fusible fiber in the present invention, the softening point in the thermoplastic fiber is 150 ° C or less, and in some cases, it is melted by heating with a low polymer fiber having a temperature of 100 ° C or less, and the adhesive strength is increased. It is a fiber that can be easily heat-sealed or embossed.

Examples of such heat-fusible fibers include ethylene-vinyl acetate copolymer fibers, polyester fibers, and polyamide fibers.
In particular, a fibrillated polyethylene-based low melting point synthetic pulp developed for papermaking is preferred.

More preferable is a composite heat-fusible fiber in which two or more types of polymer fibers having different melting points are composited.

When embossing the sheet of the present invention, the sheet is embossed at a heating temperature lower than the softening point of the high melting point polymer in the composite heat-fusible fiber.

As a result, the low-melting polymer fibers are melted during the heat processing, and the composite heat-fusible fibers are fixed to each other to perform embossing. The high-melting polymer fibers remain unchanged in shape and contribute to maintaining the strength of the sheet itself, and the parts that are not heated during embossing are kept bulky by bulky pulp. In addition, the bulky cellulose-based sheet of the present invention can be obtained. If the ratio of the composite heat-fusible fiber in the sheet of the present invention is small, the embossing is difficult to be performed, and the strength of the embossed sheet itself decreases. As the mixing ratio increases, the characteristics of the bulky valve are lost.

Therefore, the mixing ratio of the composite heat-fusible fibers is required to be 5% by weight or more by weight and preferably in the range of about 50% by weight. Conversely, the amount of heat-fusible fibers can be increased to control hygroscopicity and texture.

When the melting point of the low melting point polymer in the composite heat-fusible fiber is high, it is necessary to increase the embossing temperature, and the pulp fiber is likely to be deteriorated.
The temperature is preferably 0 ° C or lower and 180 ° C or lower and 80 ° C or higher.

There are many types of composite heat-fusible fibers in which two or more polymers having different melting points are combined, and there are a large number of polymers to be combined and their production methods, which can be used as the target fibers of the present invention.

Specific examples thereof include polypropylene / polyethylene conjugate fiber (trade name: Nissopoly Pro ES fiber), in which the melting points of the low-melting-point components are all 135 ° C. or less.
C. or less, which is particularly desirable for the above purposes of the present invention.

In addition, polyester / low melting point polyester, polyester / low melting point polyethylene, polypropylene / low melting point ethylene-vinyl acetate copolymer, nylon 66 / nylon 6, nylon 6 / polyethylene, polyester / nylon 6 and the like can be used.

As a method for producing a crosslinked pulp according to the present invention, the pulp is defibrated and dispersed in a solvent such as water, and a crosslinker having two or more functional groups that react with cellulose in the molecule is added and reacted. By this reaction, the crosslinked pulp is fixed in a crimped state by the intramolecular or intermolecular crosslinkage of the cellulose, becomes bulky, and has excellent dimensional stability.
However, if the cross-linking points are too close to each other or if the cross-linking density is too high, the valve itself becomes weak to impact, and the fiber becomes short during re-defibration after the cross-linking reaction, making it unusable for practical use. If the crosslinkable functional groups in the molecule of the crosslinker compound are too long, they will not easily become bulky even if used in large amounts.

The chemical structure of the crosslinking agent compound molecule has at least two atoms between the functional groups, and the functional groups include methylol, alkoxymethyl, aldehyde, isocyanate, epoxy, and others that react with the hydroxyl group of cellulose.

Also, a halogen compound such as epichlorohydrin can be used because it can be effectively cross-linked by using an alkali such as caustic soda.

More preferably, it has a cyclic structure between the crosslinkable functional groups. Particularly, a compound having an N-methylol group as a crosslinkable functional group is preferable because it has high reactivity. Also, N-alkoxymethyl compounds alkoxylated for their stabilization and / or control of reactivity are likewise preferred. Specific examples include the following structures.

Further, it can be used as modified by reacting with a compound that reacts with these methylol groups in order to impart various functions.

Alternatively, the desired product can be obtained by crosslinking with a reactive polymer such as a methyl roll of polyacrylamide.

The amount of these crosslinking agents used is preferably 2% by weight or more based on the pulp and is preferably within 50% by weight. Although there is a difference depending on the type of the cross-linking agent, if the amount is too large, the bulkiness increases, but as described above, the fibers are shortened at the time of re-fibrillation and the strength is reduced.

In addition, in the usual method of drying and heating crosslinking reaction and fibrillation by attaching a crosslinking agent using water as a solvent, a method of shortening the fiber easily occurs and reducing the load on the crosslinked pulp during fibrillation is taken. Is preferred.

Even when a non-aqueous solvent or water is contained, the system is treated with a system containing as little amount as possible, dried and defibrated to produce a short fiber. In this case, the mixing amount of water in the treatment liquid is preferably 40% or less, and a method using a fibrillation aid such as a surfactant is also effective.

As a usual method for producing a crosslinked pulp, a solution containing a crosslinking agent and a catalyst, if necessary, an auxiliary agent is brought into contact with the pulp, squeezed so that a predetermined amount of the crosslinking agent adheres, and then dried, heated, A crosslinking reaction is performed. After the completion of the reaction, the product is beaten, if necessary, defibrated, and dried by filtration.

Further, the crosslinked pulp can be made into a sheet or a mat by directly papermaking or accumulating after defibrating in water. By such a method, a very bulky crosslinked pulp can be produced, and the crosslinked pulp can be obtained with a thickness of 8 to 12 times with no load as compared with an untreated crosslinked pulp. 14 times higher bulk can be obtained.

The crosslinked pulp produced by the above method is made or accumulated in a usual manner together with a heat-fusible fiber and a hot water-soluble fiber chop, and heated under a slight pressure in a wet state to obtain a sheet or mat. Although it depends on the pressure at the time of heating, those obtained in this way use uncrosslinked pulp and can easily be made three times or more bulky as compared with those obtained in the same manner, and have excellent texture. It will be.

Also, to improve the performance of the generated sheet or mat,
Alternatively, various additives can be mixed to change. Therefore, the thickness of the sheet is bought depending on the type or amount of the additive. Such additives include heat resistance,
It is an improver such as an improver of weather resistance, water resistance, flexibility, and strength, and the effect of improving performance can be exhibited by adding a known amount of each of the known improvers.

In the present invention, crosslinked pulp may be mixed with ordinary pulp or a variety thereof subjected to various chemical treatments within a range not to impair the object of the present invention, and heat-fusible fiber and hot water-soluble Various kinds of fibers can be used in combination.

The fibrous materials that can be used in combination are not only pulp fibers, but also synthetic fibers such as rayon, vinylon, nylon, polyester, acrylic, aramid, and polyolefin; inorganic fibers such as alumina, ceramics, metal, glass, and carbon; and chops of these. May be used alone or in combination of two or more to give each characteristic.

[Effects] According to the present invention, the pulp-based material has an extremely high flame retardancy and bulkiness, has excellent strength, dimensional stability and texture, and has a humidity adjusting function required for building interior materials, especially wallpaper, and the like. It is possible to easily obtain a sheet that is highly safe with respect to smoke emission and generated gas during combustion. These result in highly embossed and highly decorative wallpapers by printing embossing. It can also be used as a very preferable interior material for vehicles, ships, and the like.

[Example] Example 1, Comparative Example 1 (Production of crosslinked pulp) Softwood pulp was defibrated in the following treatment liquid using a small mixer.

Treatment liquid Dimethylol dihydroxyethylene urea 8 parts by weight Zinc nitrate 2 parts by weight Water 90 parts by weight After defibration, suction filtration was performed with a glass funnel, drying was performed at 100 ° C. for 1 hour, and then curing was performed at 120 ° C. for 30 minutes. After curing, re-defibration was performed, and suction filtration was performed while slightly compressing with a glass funnel to obtain a round sheet sample. This was dried at 100 ° C. for 2 hours without changing its shape to obtain a bulky crosslinked pulp. The weight increase was 14.2% with respect to the raw pulp, and the thickness was measured under no load. As a result, the thickness was 11.2 times as large as that obtained by performing the same treatment without a crosslinking agent.

The crosslinked pulp produced above and polyvinyl alcohol (PVA) defibrated (Kuraray Co., Ltd. VP 105-2), polypropylene / polyethylene composite fiber (Chisso Polypro Fiber E)
A) and insoluble ammonium polyphosphate were mixed and dispersed in water together with a small amount of polyethyleneimine, and paper was made using a standard tappy sheet machine.

Drying was performed by passing the paper through a drum dryer having a surface temperature of 110 ° C. for 3 minutes to produce a flame-retardant bulky processed sheet.
The basis weight (g / M ² ) and thickness of this product were measured, and a tensile test was performed in accordance with JIS P8113 to measure the breaking length.

Further, a columnar copper wire having a width of 2.0 mm and a height of 6.0 mm was arranged on the sheet and hot-pressed at 120 ° C. for 5 minutes to produce an embossed sample, and the breaking length of this sample was measured. The test piece is manufactured by arranging wires so that two vertical lines are drawn in a width of 15 mm. The formulation and measurement results are shown in the table (described below).

In addition, a sheet was prepared in the same manner using pulp not subjected to a cross-linking treatment and measured, and the result is shown in the table as a comparative example.

The flame-retardant bulky sheet was left in a humidity chamber at 25 ° C. and a humidity of 92% (in the presence of a saturated aqueous solution of monoammonium phosphate) to measure the hygroscopicity. The results are shown in the table.

In addition, the flame retardancy test was performed according to JIS-Z-2150 “Flame-proof test of thin materials” (45 ° C Meckel burner method) with a flame contact time of 10
Seconds, the carbonization length was measured. The results are shown in the table.

Example 2 and Comparative Example 2 The crosslinked pulp prepared in Example 1 and the PVA fiber (Kuraray Co., Ltd. VP105-2) polypropylene / polyethylene composite fiber (Chissopolypro fiber EA) were mixed and dispersed in water.
After making paper with tappy type standard sheet and drying with drum dryer,
The obtained sheet was immersed in a 20% aqueous solution of guanidine sulfamate, squeezed with a roll, and dried in the same manner as in Example 1 to obtain a flame-retardant bulky sheet. The weight increase after guanidine sulfamate treatment was 25%.

About this thing, basis weight, thickness, and
The strength, hygroscopicity and flame retardancy were measured, and an embossed sheet was produced in the same manner and the strength was measured. The results are shown in the table.

On the other hand, Comparative Example 2 was prepared in the same manner except that a pulp treated without a crosslinking agent was used. The measurement results are shown in the table.

Examples 3 and 4 The composition of the treatment solution for the crosslinking treatment was dimethylol dihydroxyethylene urea 10 parts by weight, zinc nitrate 2 parts by weight, water 88 parts by weight, and the same treatment as in Example 1 was carried out to obtain a bulky crosslinked pulp. The weight increase was 19.4% with respect to the raw pulp, and the thickness was measured with no load. As a result, the thickness was 13.1 times as large as that obtained by performing the same treatment without a crosslinking agent.

A flame-retardant bulky sheet and an embossed sheet were prepared in the same manner as in Example 1, and the basis weight, thickness, and strength were measured. The results for each formulation are shown in the table.

Example 5 Using tetramethylol acetylene diurea as a crosslinking agent, treatment was carried out in the same manner as in Example 1 with the following composition to obtain a bulky crosslinked pulp.

Tetramethylol acetylene diurea 4 parts by weight Zinc nitrate 1 part by weight Water 95 parts by weight The weight increase of the crosslinked pulp is 7.6% based on the raw pulp, and the thickness was measured with no load. It was 10.2 times as large as that performed.

A flame-retardant bulky sheet and an embossed sheet were prepared in the same manner as in Example 1, and the basis weight, thickness, strength, and flame retardancy were measured. The formulations and results are shown in the table.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // D21H 27/20 D21H 27/20 5/14 B 5/20 BC 5/00 E (58) Field surveyed (Int.Cl. ⁶ , DB name) D21H 11/16-11/22 D21H 13/10-13/26 D21H 15/10 D21H 21/34

Claims (4)

(57) [Claims] A paper is made by mixing 54 to 60% by weight of crosslinked pulp, 18 to 20% by weight of composite heat-fusible fiber and 5 to 10% by weight of polyvinyl alcohol fiber, and is made from ammonium polyphosphate or guanidine sulfamate. Selected flame retardants
Cellulose-based flame-retardant bulky processed sheet obtained by flame-retardant treatment at 15 to 21% by weight. 2. The bulky processed sheet according to claim 1, wherein the heat-fusible fiber is a composite of two or more thermoplastic polymer fibers having different melting points. 3. A papermaking method comprising mixing 54 to 60% by weight of a crosslinked pulp, 18 to 20% by weight of a composite heat-fusible fiber and 5 to 10% by weight of a polyvinyl alcohol fiber, and forming the mixture from ammonium polyphosphate or guanidine sulfamate. Selected flame retardants
A method for producing a flame-retardant bulky processed sheet, comprising: performing a flame-retardant treatment at 15 to 21% by weight; heating and pressurizing in a wet state; drying after the treatment; 4. The method for producing a bulky processed sheet according to claim 3, wherein the embossing is performed at a temperature equal to or lower than the softening point of the high melting point polymer forming the heat fusible fiber.