JP2909826B2 - Cellulose-based bulky processed sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to building materials such as wall materials and ceiling materials, vehicles, furniture,
The present invention provides a cellulose-based bulky molding mat and sheet excellent in decorativeness and functionality used for decorative articles, filter media, absorbent materials, and the like, and further provides an embossed mat and sheet.

[Prior art and its problems] As bulky mats and sheets mainly composed of pulp, non-woven fabrics obtained by laminating conventionally defibrated pulp and bonding them with a binder, or on one or both sides thereof, There is a sheet to which a long fiber such as rayon is added, or a sheet in which a hot-melt fiber or powder is mixed with a pulp fiber and heat-fused to form a sheet.

These have high bulkiness, but since pulp fibers are used as they are, they lose their bulkiness when they come into contact with water and have poor restorability even when they are dried again.

As an embossed mat or sheet, a sheet produced by heating and embossing a vinyl chloride resin compound to which a foaming agent has been added is used for wallpaper, but there is no cellulose-based sheet. The sheet is mainly made of vinyl chloride resin, has no hygroscopic property, and when used as a building material, does not have a humidity control function and has dew condensation. The occurrence of large amounts of odor is a problem in fire safety measures.

It is known that pulp fibers are made to react with a crosslinking agent to make them bulky.However, if the bulkiness of the valve is increased in such a way, the fibers can be shortened during defibration after crosslinking and the hydroxyl groups can be reduced by the crosslinking reaction. Therefore, the crosslinked pulp is not practical as it is because the strength is significantly reduced.

[Problems to be Solved by the Invention] An object of the present invention is to maintain hygroscopicity, not to lose bulkiness even when in contact with water, to maintain sufficient strength, and to have excellent dimensional stability in which embossing can be performed. It is an object of the present invention to provide mats and sheets, and even embossed mats and sheets that are highly decorative.

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

That is, the bulky processed sheet of the present invention is a sheet obtained by arranging crosslinked pulp, heat-fusible fibers, and a binder, and mixing and papermaking. This is an embossed sheet obtained by subjecting the sheet to heating embossing.

The crosslinked pulp used is one produced by reacting a pulp with a crosslinking agent.

The crosslinking pulse in the present invention can be obtained by mere papermaking because the degree of bonding or entanglement between the pulp fibers due to hydrogen bonding differs from ordinary pulp fibers because the crosslinking agent reacts with the hydroxyl groups in the cellulose to form a crosslinked structure. The strength of the resulting sheet is significantly reduced. For this, a binder is required.

As the binder, starch, those obtained by dissolving polyvinyl alcohol and the like in water, those obtained by dispersing polyvinyl alcohol powder in water and an emulsion latex of an adhesive polymer, i.e., SBR type, NBR type, natural rubber type, acrylic type, Water-dispersible binders such as polymers modified with a carboxyl group, a hydroxyl group, an amino group, an epoxy group or the like, and polyvinyl alcohol-based fibrous binders.

As the fibrous binder, hot water-soluble fibers are particularly preferred. Hot-water soluble fiber is almost insoluble in water at room temperature and retains its fiber form.However, when heated on the dryer surface after papermaking, it starts to dissolve easily, and at that moment, it is pressurized by equipment such as a touch roll. If it does, it becomes a fibrous binder that straddles between the main fibers, resolidifies by subsequent dehydration and drying, and becomes a strong paper layer constituent fiber that does not easily separate unless it is in high-temperature water. What is a fibrous binder for PVA. Normally, PVA fiber is cut short and only swells in water at room temperature and 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 generally indicates a temperature at which the binder fiber exhibits an adhesive function when the wet paper is heated by a dryer in the case of papermaking.

By mixing with the crosslinked pulp and the heat-fusible fiber and heating it under a slight pressure in a wet state, the hot water-soluble fiber acts as an adhesive, and a sheet with extremely high strength can be obtained.

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 completely dissolves at a constant temperature. Rather, those in which some of the compounds having different solubility and other physical properties are compounded often have a favorable effect on the strength and the like.

In the sheet of the present invention, as the ratio of the hot water-soluble fiber increases, the strength increases, but the obtained sheet becomes hard and is not preferable in terms of texture. If the amount is small, the required strength cannot be obtained. Accordingly, the mixing ratio of the hot water-soluble fiber is required to be 1% or more by weight relative to the raw material mixture, and is preferably in the range of about 30%.

As a polymer fiber having a softening point in water of 50 ° C. or more and having an adhesive property to pulp, there is a polyvinyl alcohol-based fiber as described above, and the dissolution temperature can be controlled by the degree of polymerization and the degree of crosslinking.

The heat-fusible fiber in the present invention is a thermoplastic fiber having a softening point of 150 ° C. or lower, and in some cases, a low-polymer fiber of 100 ° C. or lower, which is melted by heating to increase the adhesive strength and thermocompression bonding. A fiber that can be easily heat-sealed or embossed.

Specific examples thereof include ethylene-vinyl acetate copolymer fibers, polyester fibers, and polyamide fibers, and particularly preferred are fibrillated polyethylene-based low-melting synthetic pulp developed for papermaking.

More preferred are composite heat-fusible fibers composited with two or more polymers having different melting points.

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

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 are not heated at the time of embossing. You can get a sheet. If the ratio of the composite heat-fusible fiber in the sheet of the present invention is small, it is difficult to emboss the sheet, and the strength of the embossed sheet itself decreases. As the mixing ratio increases, the characteristics of the bulky pulp 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 the hygroscopicity and the wind.

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 0 ° C or lower, preferably 180 ° C or lower and 80 ° C or higher.

There are many 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 methods for producing the fibers, and these can be used as the target fibers of the present invention.

The first example is a polypropylene / polyethylene conjugate fiber (trade name: Nisso-Polypro ES fiber). The melting point of each of the low-melting-point components is 135 ° C. or less.
C. or less, which is particularly desirable for such purposes.

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.

The crosslinked pulp according to the present invention is produced by fibrillating and dispersing pulp in a solvent such as water, and adding and reacting a crosslinking agent having two or more functional groups that react with cellulose in the molecule.
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 cross-linked pulp itself becomes weak against impact, and becomes short during refibrillation after the cross-linking reaction, making it unusable for practical use. If the distance between the crosslinkable functional groups is too long, it is difficult to become bulky even if used in large amounts.

The chemical structure of the crosslinking agent has at least two atoms between the functional groups, and includes methylol, alkoxymethyl,
It has aldehydes, isocyanates, epoxies, vinyl and others that react with hydroxyl groups of cellulose.

By using an alkali such as caustic soda of a halogen compound such as epichlorohydrin, the compound can be effectively crosslinked and used.

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. The same applies to the alkoxylated N-alkoxymethyl compounds for stabilizing and / or controlling the reactivity.
Specific examples include the following structures.

Further, in order to impart various functions, the cross-linking agent according to the present invention can be used as modified by reacting with a compound that reacts with these methylol groups.

Alternatively, the desired product can be obtained by crosslinking with a reactive polymer such as methylolated 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 attaching a crosslinking agent to pulp using water as a solvent, drying and heating crosslinking reaction, and defibrating, a method of shortening the fiber easily occurs and reducing the load on the crosslinked pulp during defibration. It is preferable to take

The crosslinked pulp according to the present invention obtained as described above is treated with a system containing a nonaqueous solvent or water and containing as little as possible, and dried and defibrated to prevent short fibers. I can do it. 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, a catalyst, and, 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 and 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 chops of the heat-fusible fiber and the hot-water-soluble fiber (binder), and heated under a slight pressure in a wet state to obtain a sheet or mat. . Depending 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 way, and at the same time, have an excellent texture It will be.

The mixture of crosslinked pulp, heat fusible fibers and binder according to the present invention can also be mixed with various additives to improve or modify the performance of the resulting sheet or mat. In that case, the thickness of the sheet changes depending on the type or amount of the additive. Such additives include improvers such as heat resistance, weather resistance, water resistance, flame resistance, flexibility, and strength, and the effect of improving performance can be exhibited by using known additives.

The crosslinked pulp according to the present invention may be a mixture of ordinary pulp or a mixture thereof subjected to various chemical treatments, or a mixture of heat-fusible fibers and hot-water-soluble fibers. Can be used.

Not only pulp fibers, but also synthetic fibers such as rayon, vinylon, nylon, polyester, acrylic, aramid, polyolefin, alumina, ceramics, metal,
Inorganic fibers such as glass and carbon, and one or more of these chops can be mixed and made into paper to give each characteristic.

[Effects] According to the present invention, it is possible to obtain a processed sheet having extremely high bulkiness mainly composed of pulp and excellent in strength, dimensional stability, texture, etc., and in various fields utilizing the characteristics of cellulose. Can be used. Further, by applying printing and embossing to the sheet, it is possible to make the sheet extremely excellent in decorativeness, and it is possible to use the sheet more highly.

[Examples] Examples 1 and 2, Comparative Examples 1 and 2 (Production of crosslinked pulp) Softwood pulp was defibrated in the following treatment solution using a small experimental mixer.

Treatment liquid composition Dimethylol dihydroxyethylene urea 5 parts by weight Zinc nitrate 1 part by weight Water 94 parts by weight After defibration, suction filtration was carried out using a glass funnel, drying was performed at 100 ° C. for 1 hour, and heating reaction was performed at 120 ° C. for 20 minutes.

Thereafter, re-defibration was performed, and suction filtration was performed while slightly compressing using 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 of this product was 9.5% with respect to the raw pulp, and the thickness was measured with no load. As a result, it was 10.5 times that obtained by performing the same treatment without using a crosslinking agent.

(Manufacture of bulky processed sheet) Crosslinked pulp and polyvinyl alcohol (PVA) fiber obtained by carrying out as described above (Kuraray Co., Ltd. VP 105-2)
And polypropylene / polyethylene composite fiber (Chisso Corporation, Chisso Polypro Fiber EA) were mixed and dispersed in water, and paper was made with a tappy type standard sheet machine.

Drying of the obtained undried paper was performed by passing the paper through a drum dryer having a surface temperature of 110 ° C for 3 minutes to obtain a bulky processed sheet. Subsequently, the product was weighed (g / M ² ) and its thickness was measured, and a tensile test was performed in accordance with JIS P8113 to measure the breaking length.

Further, a column-shaped copper wire having a width of 2.0 mm and a height of 6.0 mm was placed on the sheet and hot-pressed at 120 ° C. for 5 minutes to obtain a test piece sample of the embossed sheet. went.

The test piece is manufactured by arranging wires so that two vertical lines are formed in a width of 15 mm.

 The formulation and measurement results are shown in (described below).

In addition, a sheet and a test piece which had been subjected to hot pressing from the sheet in the same manner using pulp not subjected to a crosslinking treatment and measured were shown in the table as comparative examples.

About the above bulky sheet, 25 ° C, humidity 92% (phosphoric acid-
(In the presence of a saturated aqueous solution of ammonium) in a constant-humidity bath and the hygroscopicity was measured. The results are shown in the table (described below).

Examples 3, 4, and 5 The same treatment as in Example 1 was carried out except that the composition of the treatment solution for the crosslinking treatment was changed to 8 parts by weight of dimethylol dihydroxyethylene urea, 2 parts by weight of zinc nitrate and 90 parts by weight of water. Pulp was obtained. 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.

A 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 formulations and results are shown in the table.

Example 6 A bulky crosslinked pulp was obtained by treating in the same manner as in Example 1 except that tetramethylolacetylene diurea was used as a crosslinking agent and the following composition was used.

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 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 formulations and results are shown in the table.

As is clear from the table, the fibers of the examples obtained using the crosslinked pulp, PVA fibers and EA fibers and the sheets of the examples obtained using the EA fibers were uncrosslinked in place of the crosslinked pulp. It has a thickness (bulk) that is three to four times that of the sheets of the comparative examples obtained using pulp, and the breaking length is only a fraction of that. On the other hand, the hygroscopicity of the product of the present invention is
It is slightly inferior to the comparative example, and has sufficient hygroscopicity, for example, for wallpaper.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI D21H 5/14 B 5/20 BC

Claims (4)

(57) [Claims] (1) 65 to 75% by weight of crosslinked pulp and heat-fusible fiber (5)
~ 20% by weight and hot water soluble fiber as a binder 5 ~ 20
A bulky workable sheet made by mixing paper by weight. 2. The bulkiness according to claim 1, wherein a composite heat-fusible fiber obtained by composite melt-spinning two or more kinds of thermoplastic polymers having different melting points is used as the heat-fusible fiber. Processed sheet. 3. A paper made by mixing a crosslinked pulp, a heat-fusible fiber and a binder, followed by heating and pressurizing in a wet state.
A method for producing a bulky processed sheet, comprising drying after the treatment and heating and embossing. 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.