JP2006257627A - Wallpaper-backing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide wallpaper-backing paper giving wallpaper which comprises a decorative layer such as a vinylic resin layer, olefinic resin layer, woven fabric layer, paper layer or inorganic layer, and backing paper for holding the decorative layer, is hardly curled, even when coated with a paste on adhesion, and does form openings after adhered. <P>SOLUTION: This wallpaper-backing paper is characterized by containing pulp, as a pulp component preferably in an amount of ≥50 wt%, treated by bringing bubbles formed cavitation into contact with a pulp suspension. The wallpaper-backing paper has improved dimensional stability required for the wallpaper-backing paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a backing paper for wallpaper.

  The wallpaper is used for a long period of time on a wall in an ordinary residence, hotel, hospital, etc. to beautify the room. The wallpaper includes vinyl wallpaper, olefin wallpaper, textile wallpaper, paper wallpaper, inorganic wallpaper, etc. These wallpapers hold a decorative layer such as vinyl layer, olefin layer, textile layer, paper layer, inorganic layer, and the decorative layer. It is made of backing paper.

  These wallpapers are pasted with starch or vinyl acetate resin water-based glue at the time of construction, but the backing paper absorbs moisture in the glue in the gluing process, so the wallpaper becomes soft or the backing paper stretches due to increased moisture. There are things to do. Due to these problems, the wallpaper is curled, causing problems such as difficulty in sticking to the wall and the tendency for wrinkles to occur after sticking. Further, when the glue dries, the backing paper contracts, so that there is a gap (opening) in the joint portion between the adjacently bonded wallpapers, and there is a problem that the designability after construction is impaired.

  As a method for improving the dimensional stability of backing paper, synthetic papers such as backing paper (Patent Documents 1, 2, and 3), polyolefins, polyesters, polyamides, etc. blended with inorganic fibers such as glass fibers that are less stretched by moisture Lined paper (Patent Documents 4, 5, and 6) containing fibers is disclosed.

  Although these non-cellulosic fibers are effective in improving the dimensional stability of the backing paper, they are weak in self-adhesion, so if the amount is increased, wet press parts, dryer parts, size press rolls, canvas, calendar rolls, etc. There is a problem in operability that the fibers fall off or that the synthetic fibers are soiled by melting with drying heat. For this reason, it is desirable to reduce the blending ratio of non-cellulose fibers as much as possible in order to perform more stable operation.

  Under such circumstances, a method for improving the dimensional stability of backing paper for wallpaper other than the blending of non-cellulose fibers is desired.

Japanese Examined Patent Publication No. 7-122236 JP-A-8-1000039 Japanese Patent Publication No. 8-26631 JP-A-5-59696 JP-A-5-59698 JP-A-5-59699

  Accordingly, an object of the present invention is to provide a backing paper for wallpaper that not only makes it difficult for the wallpaper to curl even when glue is applied during construction, but also does not cause opening after application.

  As a result of intensive studies on the above problems, the present inventors have generated air bubbles by cavitation in the pulp suspension, and by using the pulp that has been treated by contacting it with the pulp suspension, the operability during papermaking The present inventors have found that the dimensional stability can be improved without lowering the thickness and have achieved the present invention. That is, the present invention is a wallpaper backing paper for providing a decorative layer on one side to make a wallpaper, wherein the backing paper generates bubbles by cavitation, and is treated by bringing it into contact with a pulp suspension. It is characterized by containing.

  In addition, the backing paper for wallpaper of the present invention is preferably coated on at least one side with a coating liquid containing a water-soluble polymer and / or a water-dispersible polymer.

  Moreover, in this invention, in order to provide higher dimensional stability, it is also possible to contain 5-20 weight% of thermoplastic synthetic fibers or glass fibers.

  The wallpaper backing paper of the present invention desirably has a dimensional change of 1.3% or less after being immersed in water for 1 hour. Specifically, a strip-shaped test piece of wallpaper backing paper was conditioned at 23 ° C and 50% R / H atmosphere, and the length of the test piece in the horizontal direction of papermaking was immersed in water for 1 hour. Using the length measured immediately after removal, the dimensional change (water elongation) obtained by the following formula is 1.3% or less.

  Water elongation (%) = {(length after 1 hour immersion in water) − (length before water immersion)} / (length before water immersion) × 100

  The wallpaper backing paper of the present invention has no operational problems during papermaking. Moreover, since the wallpaper using the backing paper for wallpaper according to the present invention is less likely to cause an opening, the appearance after construction is good.

  The wallpaper-backed paper of the present invention is characterized by using a pulp which has been treated by bringing bubbles generated by cavitation in the pulp suspension into contact with the pulp suspension (hereinafter referred to as cavitation treatment). Normally, pulp is beaten using a mechanical force with a refiner or the like, but internal beating of the pulp fiber is promoted by beating using a mechanical force. In contrast, cavitation-treated pulp is selectively loaded on the pulp fiber surface, which suppresses the progress of fiber cutting (damage) and internal fibrillation caused by beating by mechanical force. There is a feature that. Although the detailed reason is unknown, it is considered that such a characteristic of the pulp is a cause of suppressing the dimensional stability due to moisture change.

  In the present invention, the pulp to be subjected to cavitation treatment is made from conifers, hardwoods, non-wood fibers, or the like. More specifically, chemical pulp such as kraft pulp, mechanical pulp such as crushed wood pulp, thermomechanical pulp, chemithermomechanical pulp, or recycled pulp produced from a sheet-like substance made of waste paper or fiber. . Examples of used paper include newspapers, flyers, magazines for coated paper, magazines for coated paper, thermal recording paper, pressure-sensitive recording paper, imitation paper, colored fine paper, electrophotographic transfer paper, computer output paper, or these Applicable to mixed waste paper.

  Since cavitation occurs when a liquid is accelerated and the local pressure is lower than the vapor pressure of the liquid, flow rate and pressure are particularly important. From this, the basic dimensionless number representing the cavitation state, the cavitation number σ, is defined as follows (edited by Yoji Kato, new edition of cavitation basics and recent advances, Tsuji Shoten, 1999).

（p_∞：一般流の圧力、U_∞：一般流の流速、p_v：流体の蒸気圧、ρ：流体の密度）
ここで、キャビテーション数が大きいということは、その流れ場がキャビテーションを発生し難い状態にあるということを示す。特にキャビテーション噴流のようなノズルあるいはオリフィス管を通してキャビテーションを発生させる場合は、ノズル上流側圧力p₁、ノズル下流側圧力p₂、試料水の飽和蒸気圧p_vから、キャビテーション数σは下記式（２）のように書きかえることができ、キャビテーション噴流では、p₁、p_2、p_v間の圧力差が大きく、p₁≫p₂≫p_vとなることから、キャビテーション数σはさらに以下のように近似することができる（H. Soyama, J. Soc. Mat. Sci. Japan, 47(4)， 381 1998）。

(P _∞: pressure general flow, U _∞: flow rate of the general flow, p _v: fluid vapor pressure, [rho: the density of the fluid)
Here, a large number of cavitations indicates that the flow field is in a state where cavitation is difficult to occur. In particular, when cavitation is generated through a nozzle or orifice pipe such as a cavitation jet, the cavitation number σ is calculated from the following equation (2) from the nozzle upstream pressure p ₁ , the nozzle downstream pressure p ₂ , and the saturated vapor pressure p _v of the sample water. In the cavitation jet, the pressure difference between p ₁ , p _{2 and} p _v is large, and p ₁ >> p ₂ >> p _v , so the cavitation number σ is further (H. Soyama, J. Soc. Mat. Sci. Japan, 47 (4), 381 1998).

本発明におけるキャビテーションの条件は、上述したキャビテーション数σが0.001以上0.5以下であることが望ましく、0.003以上0.2以下であることが好ましく、0.01以上0.1以下であることが特に好ましい。キャビテーション数σが0.001未満である場合、キャビテーション気泡が崩壊する時の周囲との圧力差が低いため効果が小さくなり、0.5より大である場合は、流れの圧力差が低くキャビテーションが発生し難くなる。

The cavitation condition in the present invention is preferably such that the above-mentioned cavitation number σ is 0.001 or more and 0.5 or less, preferably 0.003 or more and 0.2 or less, and particularly preferably 0.01 or more and 0.1 or less. When the cavitation number σ is less than 0.001, the effect is small because the pressure difference with the surroundings when the cavitation bubbles collapse is low, and when it is greater than 0.5, the flow pressure difference is low and cavitation is difficult to occur. .

  In addition, when the injection liquid is injected through the nozzle or the orifice tube to generate cavitation, the pressure of the injection liquid (upstream pressure) is desirably 0.01 MPa or more and 30 MPa or less, and 0.7 MPa or more and 15 MPa or less. It is particularly preferable that the pressure is 2 MPa or more and 10 MPa or less. When the upstream pressure is less than 0.01 MPa, it is difficult to produce a pressure difference from the downstream pressure, and the effect is small. On the other hand, when the pressure is higher than 30 MPa, a special pump and a pressure vessel are required, and energy consumption increases, which is disadvantageous in terms of cost.

  Further, the jet velocity of the jet liquid is desirably in the range of 1 m / second to 200 m / second, and preferably in the range of 20 m / second to 100 m / second. When the jet velocity is less than 1 m / second, the effect is weak because the pressure drop is low and cavitation hardly occurs. On the other hand, when it is higher than 200 m / sec, a high pressure is required and a special device is required, which is disadvantageous in terms of cost.

  Examples of cavitation generating means that can be used in the present invention include a method using a liquid jet, a method using an ultrasonic transducer, a method using an ultrasonic transducer and a horn-shaped amplifier, and a method using laser irradiation. Although not limited thereto, a method using a liquid jet is preferable because the generation efficiency of cavitation bubbles is high and a cavitation bubble cloud having a stronger collapse impact force is formed. Further, the cavitation treatment can be performed in an arbitrary container such as a tank or in a pipe, but is not limited thereto. Further, although it is possible to perform the processing by one pass, the peeling effect can be further increased by circulating the required number of times. Furthermore, it can process in parallel or permutation using a plurality of cavitation generators.

  In the method of generating cavitation by a liquid jet that can be used in the present invention, distilled water, tap water, industrial water, reused water recovered in the papermaking process, pulp squeezed water, white water, pulp Suspension, alcohol, and the like can be sprayed, but are not limited thereto. Preferably, it is possible to circulate the entire amount to be treated by injecting the pulp suspension itself, which is preferable.

  The pulp concentration in the cavitation treatment in the present invention is preferably 5% by weight or less, more preferably 4% by weight or less, and still more preferably in the range of 0.1 to 3% by weight. It is preferable from the viewpoint of generation efficiency. When the solid concentration of the liquid to be ejected is 5 wt% or more and 20 wt% or less, the effect can be obtained by setting the concentration of the jet liquid to 4 wt% or less.

  The cavitation treatment of the present invention can be applied to any place in the pulping process and the conditioning process, but it is preferable to apply it at the stage where the fibrous material is defibrated to become a pulp. Moreover, you may combine the beating process by the conventional beating machine by mechanical force, and the beating process by the cavitation of this invention.

  The wallpaper backing paper of the present invention must use cavitation-treated pulp. However, pulp that has been beaten by a general beating machine such as a disc-type, conical-type, or drum-type refiner must be used in combination. You can also. However, in that case, it is desirable that 50% by weight or more of the total pulp components are cavitation-treated pulp. If the cavitation-treated pulp is less than 50% by weight, sufficient dimensional stability may not be obtained.

  The backing paper for wallpaper of the present invention can be blended with non-cellulosic fibers such as glass fibers and / or synthetic fibers. In that case, the blending ratio of non-cellulosic fibers is preferably 20% by weight or less. Preferably it is 15 weight% or less. As the blending ratio of non-cellulosic fibers increases, it becomes impossible to solve the problem of operability at the time of papermaking when a large amount of non-cellulosic fibers, which is the object of the present invention, is used. According to the experience of the present inventors, the problem of operability is small if it is about 15% by weight. For example, even a wallpaper-backed paper containing up to about 15% by weight of synthetic fiber can be blended with a cavitation-treated pulp to obtain higher dimensional stability without impairing operability.

  Examples of such non-cellulosic fibers include polyolefin resin fibers such as polyethylene and polypropylene, polyester resin fibers such as polyethylene terephthalate, polyamide resin fibers such as nylon, acrylic resin fibers such as polyacrylonitrile, and polyurethane resins. Thermoplastic synthetic fibers such as fibers and halogen-containing resin fibers such as polyvinyl chloride can be used. In addition, synthetic fibers obtained by copolymerizing the above thermoplastic synthetic resins, or composite fibers containing two or more different thermoplastic synthetic resins having a core-sheath structure, a sea-island structure, etc. in a single fiber are also used. be able to. These synthetic fibers may be used alone or as a mixture of a plurality of types.

  A sizing agent can be internally and / or externally added to the wallpaper backing paper of the present invention in the same manner as ordinary paper. In the case of acidic papermaking, the sizing agent may be rosin sizing agent, rosin emulsion sizing agent, alpha carboxymethyl saturated fatty acid, or the like. On the other hand, in the case of neutral papermaking, rosin sizing agents for neutral papermaking, alkyl ketene dimers, alkenyl succinic anhydrides, and cationic polymer sizing agents can be used. The addition amount of the sizing agent is not particularly limited, but it is preferably 10 seconds or more in terms of Steecht sizing. In addition, a surface sizing agent such as rosin or synthetic resin can also be used for external addition such as a size press.

  The wallpaper backing paper of the present invention is preferably applied to at least the surface on which the decorative layer is provided with a coating liquid mainly composed of a water-soluble polymer and / or a water-dispersible polymer in order to increase the surface strength. . For example, in the case of vinyl wallpaper, a vinyl chloride paste is applied to the surface of the wallpaper backing paper, and after the vinyl chloride paste is cured, it is subjected to a printing process so that the vinyl chloride layer becomes a decorative layer. At this time, if the surface strength of the backing paper for wallpaper is low, the fibers on the paper surface fluff during the application of the decorative layer, and the fluffed portion becomes a protrusion on the wallpaper surface after curing, causing printing failure.

  As the water-soluble polymer used in the present invention, various modified starches such as oxidized starch and enzyme-modified starch, polyvinyl alcohol, polyacrylamide, carboxymethylcellulose, casein and the like can be used as appropriate. As the water dispersible polymer, styrene / butadiene copolymer latex, methyl methacrylate / butadiene copolymer latex, acrylic emulsion, vinyl acetate emulsion and the like can be used as appropriate. At this time, the water-soluble polymer and / or the water-dispersed polymer may be used alone, but may be used by mixing with various pigments such as clay, kaolin, calcium carbonate, titanium dioxide, and silica.

The coating amount of the water-soluble polymer and / or water-dispersible polymer is preferably 0.2 to 10 g / m ² in terms of solid content. When the coating amount is less than 0.2 g / m ^2, fuzzing increases, and when it is 10 g / m ² or more, the backing paper surface is completely covered with a polymer, so that an anchor effect is produced between the decorative layer and the backing paper layer. Decreases.

  Further, fixing agents, dry paper strength agents, wet paper strength agents, fillers, yield improvers, dyes, pigments, and the like can be used as internal additives as long as the quality is not affected. Furthermore, surface paper strength agents, dyes, pigments and the like can be used as external chemicals to be applied or impregnated with a size press or the like.

The basis weight of the wallpaper backing paper of the present invention is preferably 40 g / m ² or more and 120 g / m ² or less. If the basis weight is less than 40 g / m ² , the strength is low and paper breakage is likely to occur during processing. On the other hand, if the basis weight exceeds 120 g / m ² , it becomes too hard when processed into wallpaper, which makes construction difficult and problematic.

  The wallpaper backing paper of the present invention is produced by a known paper machine, but the paper making conditions are not particularly specified. As the paper machine, a long net paper machine, a twin wire paper machine, a circular net paper machine, or the like is used.

  The wallpaper of the present invention can be obtained by providing a decorative layer on the backing paper for wallpaper of the present invention thus produced. For example, wallpaper products such as vinyl wallpaper provided with a vinyl layer as a decorative layer, olefin wallpaper provided with an olefin layer, woven wallpaper provided with a fabric layer, paper wallpaper provided with a paper layer, inorganic wallpaper provided with an inorganic layer, etc. It is done. In any case, after providing a layer serving as a decorative layer, printing is performed as necessary, or foaming or embossing is performed to form a decorative layer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited by this. The following methods were used for the preparation method of the pulp used in each Example and Comparative Example and the evaluation method for the backing paper for wallpaper obtained in the Examples and Comparative Examples.

<Pulp slurry 1: Beating of pulp by cavitation>
Using a cavitation jet cleaning device (nozzle diameter 1.5 mm) as shown in FIG. 1, a pulp suspension having a hardwood bleached kraft pulp (LBKP) concentration of 1.1% by weight as a jet suspension and a pulp suspension in a container. The pulp was beaten by cavitation so that the Canadian standard freeness (CSF) was 450 ml. The pressure of the jet liquid was 7 MPa (jet flow rate 70 m / sec), and the pressure in the jetted container was 0.3 MPa.

<Pulp slurry 2: Beating with a double disc refiner>
Using a double disc refiner (DDR), hardwood bleached kraft pulp (LBKP) was beaten so that the Canadian standard freeness (CSF) was 450 ml.

<Evaluation method>
-Water elongation: The humidity of the test piece was adjusted at 23 ° C. and 50% R / H atmosphere, and the length of the test piece in the horizontal direction of the papermaking was measured. Thereafter, it was immersed in pure water for 1 hour and then taken out and immediately measured in the lateral direction of the papermaking. The water elongation was calculated by the following formula.
Water elongation (%) = {(length after 1 hour immersion in water) − (length before water immersion)} / (length before water immersion) × 100
-Workability: A paste made of vinyl chloride, plasticizer (phthalate ester), calcium carbonate, titanium dioxide, mineral spirit, etc. is applied to the surface of the backing paper at a coating thickness of 250μm and heated at 180 ° C for 2 minutes to gel. Made it. The resulting vinyl wallpaper was cut into two sheets of 1m length and 95cm width, and starch-based Yayoi Chemical A paste was applied to the backing paper side, and two sheets of veneer board (width 2m, length 1m) were applied. Paste the wallpaper so that both ends overlap, cut the overlapping part with a cutter so that there is no joint, leave it in an atmosphere of 23 ° C, 50% R / H for 7 days, and dry it completely. The presence or absence of openings was observed.

[Example 1]
After adding a sulfuric acid band so that pH becomes 4.5 to the pulp slurry 1, 0.15 wt% of alpha carboxymethyl saturated fatty acid salt (trade name: NPS-S, manufactured by Seiko PMC Co., Ltd.) was added as a sizing agent. A paper stock was prepared by adding 0.2% by weight of polyamide / epichlorohydrin resin (trade name: WS-547, manufactured by Seiko PMC Co., Ltd.) as a wet paper strength agent. Paper is made from the obtained stock using a long paper machine, and 1.5% by weight of polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) is applied by a size press during the process, and the basis weight is 65 g / m. ^Two wallpaper backing papers were produced. The resulting paper backing paper was evaluated for water elongation and workability, and the results are shown in Table 1.

[Example 2]
A wallpaper backing paper was produced in the same manner as in Example 1 except that Pulp Slurry 1 and Pulp Slurry 2 were used at a solids weight ratio of 60/40. The resulting paper backing paper was evaluated for water elongation and workability, and the results are shown in Table 1.

[Comparative Example 1]
A wallpaper backing paper was produced in the same manner as in Example 1 except that the pulp slurry 2 was used. The resulting paper backing paper was evaluated for water elongation and workability, and the results are shown in Table 1.

  As shown in Table 1, the wallpaper-backed paper made of pulp beaten by cavitation has improved water elongation, and is good with no openings or the like during construction.

[Example 3]
In a pulp slurry in which pulp slurry 1 and core-sheath fiber (trade name: N-701S, core: polyester fiber, sheath: polyethylene, fiber length 5 mm, manufactured by Kuraray Co., Ltd.) are blended at a solid content weight ratio of 85/15 After adding a sulfuric acid band so that the pH is 4.5, 0.15% by weight of alpha carboxymethyl saturated fatty acid salt (trade name: NPS-S, manufactured by Seiko PMC Co., Ltd.) is added as a sizing agent, and a wet paper strength agent is added. As a base material, polyamide / epichlorohydrin resin (trade name: WS-547, manufactured by Seiko PMC Co., Ltd.) was added at 0.2 wt%. Paper is made from the resulting stock using a long paper machine, and 1.5% by weight of polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) is applied by a size press during the process, and the basis weight is 65 g / m ^2. Manufactured paper backing paper. The resulting paper backing paper was evaluated for water elongation and workability, and the results are shown in Table 2.

[Comparative Example 2]
A wallpaper backing paper was produced in the same manner as in Example 3 except that the pulp slurry 2 was used instead of the pulp slurry 1. The resulting paper backing paper was evaluated for water elongation and workability, and the results are shown in Table 2.

[Comparative Example 3]
A wallpaper backing paper was produced in the same manner as in Example 3 except that the solid content weight ratio of the pulp slurry 2 and the core-sheath fiber was 80/20. The resulting paper backing paper was evaluated for water elongation and workability, and the results are shown in Table 2.

  As shown in Table 2, Example 3 using pulp pulverized by cavitation in wallpaper backing paper made of synthetic paper with synthetic fiber has higher dimensional stability than Comparative Example 2 using pulp pulverized by DDR. Obtained. On the other hand, compared with Example 3 and Comparative Example 2, Comparative Example 3 in which the blending amount of the synthetic fiber was increased was good in quality, but the paper machine dryer was partially soiled compared with Example 3 and Comparative Example 2. It was. As described above, by using pulp pulverized by cavitation even in mixed paper with synthetic fiber, it becomes possible to reduce the blending amount of synthetic fiber that causes troubles when making wallpaper backing paper.

It is the schematic of the cavitation jet type washing | cleaning apparatus used in the Example.

Explanation of symbols

1: Sample tank 2: Nozzle 3: Cavitation jet cell 4: Plunger pump 5: Upstream pressure control valve 6: Downstream pressure control valve 7: Upstream pressure gauge 8: Downstream pressure gauge 9: Water supply valve 10: Circulation valve 11: Drain valve 12: Temperature sensor 13: Mixer

Claims (7)

A backing paper for wallpaper characterized in that it contains pulp which is produced by generating bubbles by cavitation in the pulp suspension and contacting it with the pulp suspension. The backing paper for wallpaper according to claim 1, wherein a coating liquid containing a water-soluble polymer and / or a water-dispersible polymer is applied on at least one side. 3. The wallpaper backing paper according to claim 1, wherein a dimensional change after immersion in water for 1 hour is 1.3% or less. The backing paper for wallpaper according to any one of claims 1 to 3, wherein the blending ratio of the thermoplastic synthetic fiber is 5 to 20% by weight. The backing paper for wallpaper according to any one of claims 1 to 3, wherein the glass fiber content is 5 to 20% by weight. The backing paper for wallpaper according to any one of claims 1 to 5, wherein the basis weight is 40 g / m ² or more and 120 g / m ² or less. A wallpaper comprising a decorative layer on the surface of the backing paper for wallpaper according to any one of claims 1 to 6.

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