JP4533937B2 - Impregnated paper for flooring - Google Patents

Description

  The present invention relates to an impregnated paper for flooring used as a reinforcing material for plywood constituting the flooring.

  Conventionally, for example, as shown in Patent Document 1, a decorative board for flooring or the like is generally configured to include a decorative sheet, an adhesive layer, and a plywood. In particular, veneer plywood is often used as the plywood in composite flooring flooring, but MDF (medium density laminated board) is used as the reinforcing material. However, when MDF is used as a reinforcing material, the cost is not only higher than a floor material composed of a single plywood, but it absorbs moisture and swells, and the floor surface is likely to be wavy. There is a problem of getting worse. Therefore, as a reinforcing material, in addition to MDF, for example, as shown in Patent Document 1, a resin-impregnated paper cured layer (craft paper) having a thickness of about 0.3 mm, a prepreg shown in Patent Document 2, and Patent Document The fibrous sheet which apply | coated the synthetic resin liquid shown by 3 is used. This kraft paper is impregnated with a hardened resin such as phenol, melamine, or DAP (diallyl phthalate) on the base paper to maintain the impact resistance of the flooring and to cover the irregularities formed on the surface of the flooring. , So that no wavy is formed.

  Furthermore, with the recent increase in demand for wood, the price of veneer has soared, making it difficult to obtain plywood. Therefore, in order to reduce the manufacturing cost, relatively inexpensive Chinese-made veneer plywood has been used. However, Chinese-made veneer plywood is soft, has low impact resistance, and has poor surface properties. For this reason, the conventional kraft paper having a thickness of about 0.3 mm cannot secure impact resistance as a flooring material and cannot cover unevenness formed on the surface of the flooring material.

  In addition, when V-cut processing is applied to a flooring material using kraft paper with a thickness of about 0.3 mm as a reinforcing material, the veneer plywood itself can be seen, resulting in a poor appearance of the flooring material. It was. Thus, a method of laminating two kraft papers having a thickness of about 0.3 mm is used, but there is a problem that the peel strength is lowered on the kraft paper laminating surface and the number of processing steps is increased.

  Further, since the conventional kraft paper has a poor impregnation property with a resin or the like, there is also a problem that it is difficult to obtain impact resistance necessary for use as a flooring material. Therefore, there are means such as increasing the freeness of the raw material pulp to improve the impregnation property, lowering the press linear pressure in the paper making process, the calendar linear pressure, etc., but any means weakens the entanglement between the pulp fibers, As a result, the inter-fiber strength is reduced, and the interlaminar strength as the flooring impregnated paper cannot be ensured, and it is difficult to ensure impact resistance.

JP 2007-77726 A JP 2003-314043 A JP 2002-172604 A

  The present invention has been made in view of the above-described circumstances, and the object of the present invention is that the interlaminar strength is high even when a soft veneer plywood is used as the plywood, which has poor surface properties. Another object of the present invention is to provide an impregnated paper for flooring that is impact resistant and that can cover unevenness formed on the surface of the flooring.

The above-mentioned object of the present invention is an impregnated paper for flooring formed by impregnating and applying a resin to an impregnated base paper of multilayer paper having at least two paper layers of a front layer and a back layer, The raw material pulp constituting each layer is blended with 70 to 90% by mass of NBKP and 10 to 30% by mass of mechanical pulp, the resin is a curable resin, and the impregnated base paper is “paper” described in JIS-P8118 (1998). and board - density measured in accordance with the test method "in thickness and density of 0.3 to 0.5 g / cm ^3, wherein the impregnated paper is paper thickness is 550～770Myuemu, also the impregnated paper The interlayer strength measured in accordance with “Test method for adhesive tape / adhesive sheet—tensile strength” described in JIS-Z0237 (2000) is longitudinal: 350 N / 15 mm or more, lateral: 200 N / 15 mm or more. For flooring It is achieved by providing a paper.

In addition, the above-mentioned object of the present invention is that the raw material pulp constituting each layer of the impregnated base paper is “paper and paperboard—pulp freeness test method—Canadian standard freeness test method described in JIS-P8121 (1995). Is achieved effectively by providing an impregnated paper for flooring, characterized by adjusting the freeness measured according to ”to 600-750 cc.

  Further, the above object of the present invention is that the impregnated base paper has a Klem water absorption of 80 to 120 mm measured according to “paper and paperboard—water absorption test method—Klem method” described in JIS-P8141 (2004). In addition, J. of the impregnated base paper. TAPPI No. An impregnated paper for flooring characterized in that the oil absorption measured in accordance with “Paper and paperboard—oil repellency test method—kit method” described in 41 (2000) is 0.5 to 10 seconds. This is achieved more effectively by providing.

  Furthermore, the above object of the present invention is achieved more effectively by providing an impregnated paper for flooring, wherein the resin is a curable resin.

  According to the impregnated paper for flooring according to the present invention, a resin is impregnated and applied to a base paper for multi-layer paper having at least two paper layers, a front layer and a back layer, and described in JIS-Z0237 (2000). Since the interlaminar strength measured in accordance with “Adhesive tape / adhesive sheet test method—tensile strength” of length: 350 N / 15 mm or more and width: 200 N / 15 mm or more, surface properties are poor as a plywood for flooring, Even if soft veneer plywood or the like is used, it has impact resistance and can cover the unevenness of the surface of the flooring.

  Hereinafter, the impregnated paper for multilayer flooring according to the present invention will be described in detail by taking as an example the case where the impregnated base paper is composed of three paper layers of a surface layer, one intermediate layer and a back layer. The impregnated paper for multilayer flooring according to the present invention is not limited to the following embodiments, and it goes without saying that the configuration can be changed as appropriate without departing from the scope of the claims. .

  An impregnated paper for flooring according to the present invention (hereinafter referred to as “the present impregnated paper”) is obtained by impregnating and applying a resin to an impregnated base paper having three paper layers, as described in JIS-Z0237 (2000). The interlayer strength (hereinafter simply referred to as “interlayer strength”) measured in accordance with “Testing method of adhesive tape / adhesive sheet—tensile strength” is set to 350 N / 15 mm or more (vertical) and 200 N / 15 mm or more (horizontal). . When the vertical interlayer strength is less than 350 N / 15 mm and the horizontal interlayer strength is less than 200 N / 15 mm, delamination is likely to occur and impact resistance is reduced, and the impregnated paper cannot be used as a flooring material.

  The raw material pulp of each layer forming the impregnated raw paper includes hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), hardwood sulfite pulp, Wood fiber such as coniferous sulfite pulp as the main raw material, chemically treated pulp, ground pulp obtained by mechanically pulping chemically treated pulp and chips, and chips processed under heating and pressure Mechanically pulped thermomechanical pulp (TMP), chemi-ground pulp mechanically pulped with chemicals added to wood or chips, and semi-chemical pulped with a refiner after cooking the chips until soft Virgin pulp such as pulp can be used. In addition, non-wood fibers such as kenaf, hemp, and straw, which are fiber materials other than wood, can be used. However, non-wood pulp has low pulp strength and the unit price of the pulp itself is high. It is preferable to use mechanical pulp such as kraft pulp and TMP. In addition, although pulp made from waste paper may be blended, there are many fine fibers. For this reason, the drainage of the impregnated base paper deteriorates, the production speed decreases, the appearance of the paper surface after impregnating the impregnating base paper with the resin deteriorates, and the interlayer strength also decreases. Therefore, it is preferable not to mix the waste paper pulp with the raw material pulp that forms the surface layer and the back layer, and it is more preferable not to mix it with the raw material pulp that forms the middle layer.

  Furthermore, the raw material pulp constituting the impregnated base paper of the present impregnated paper is preferably 70 to 100% by mass of the total raw material pulp as NBKP and 0 to 30% by mass of mechanical pulp such as TMP. In addition, when the compounding ratio of mechanical pulps, such as TMP, exceeds 30 mass%, the problem that resin impregnation property will worsen will arise. If the NBKP compounding ratio exceeds 90% by mass, the amount of resin impregnation in the impregnated base paper tends to increase, resulting in increased costs. Therefore, the NBKP compounding ratio is more preferably 70 to 90% by mass.

  Since the impregnated paper is formed by impregnating the impregnated base paper with a resin, it is preferable that the impregnated paper is made using the raw material pulp having the same composition. For example, the waste paper is blended in the raw material pulp of the middle layer. Papermaking may be performed using raw pulp having a different composition from the back layer.

  In addition, the raw material pulp of each layer was measured according to JIS-P8121 (1995) "Paper and paperboard-Pulp freeness test method-Canadian standard freeness test method". "Freeness") is preferably adjusted to 600 to 750 cc. If the freeness of the raw pulp of each layer exceeds 750 cc, the amount of resin impregnated in the impregnated base paper increases, resulting in an increase in the amount of resin used and cost. In addition, the amount of resin impregnation increases and drying takes time. The operability is also reduced. In addition, since the fiber-to-fiber bonding force is also reduced and the interlayer strength is lowered, when such an impregnated base paper is used for flooring, problems such as delamination and reduced impact resistance occur. On the other hand, if the freeness of the raw material pulp of each layer is less than 600 cc, the fiber-to-fiber bond strength increases and the interlayer strength increases, but the resin impregnation property of the impregnated base paper significantly decreases. It becomes difficult to obtain strength, and impact resistance decreases.

  Further, it is preferable to add a wet paper strength enhancer and / or a dry paper strength enhancer to at least one layer of raw pulp of the impregnated base paper. Thereby, while being able to improve the workability at the time of the resin impregnation coating in this impregnation paper, the interlayer intensity | strength of this impregnation paper can be made higher.

  In the case where the wet paper strength enhancer is not blended, the suitability for processing may be lowered, for example, paper breakage may occur when the resin is impregnated with the impregnated base paper. On the other hand, when the dry paper strength enhancer is not blended, the interlaminar strength of the impregnated paper after the resin is impregnated and coated on the impregnated base paper is lowered, making it difficult to use the impregnated paper as a flooring material. Therefore, it is preferable to add the wet paper strength enhancer and the dry paper strength enhancer to the raw pulp of all layers constituting the impregnated paper.

  As such a wet paper strength enhancer, for example, polyamide polyamine / epichlorohydrin type, melamine / formalin type, urea / formalin type resin and the like can be used. As the dry paper strength enhancer, anionic, cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan, or the like can be used. However, the wet paper strength enhancer and the dry paper strength enhancer used for the impregnated paper are not limited to these.

  Further, since the resin impregnation property of the impregnated base paper is reduced by adding the paper strength enhancer, a sizing agent is added to the raw material pulp forming the layer to which the paper strength enhancer is added. In order to impart resin impregnation properties to the impregnated base paper, it is also possible to add chemicals such as a liquid absorbent and a bulking agent in addition to the sizing agent. However, since it is not necessary to add chemicals such as a sizing agent depending on the degree of beating of the raw pulp and the blending ratio of the pulp, it may not be added in this case.

  Moreover, in order to increase the bulk of the impregnated base paper, that is, to increase the paper thickness of the impregnated base paper, thermally foamable particles can be used. The thermally foamable particles that can be used in the impregnated base paper are those in which a low-boiling solvent is enclosed in a fine particle outer shell composed of a thermoplastic synthetic resin mainly composed of an acrylic copolymer. The thermally foamable particles preferably have an average particle diameter of 5 to 15 μm and start to expand upon heating at 75 to 130 ° C.

  Examples of the thermoplastic synthetic resin constituting the outer shell include copolymers such as vinylidene chloride, acrylonitrile, acrylic acid ester, and methacrylic acid ester.

  Examples of the low boiling point solvent enclosed in the outer shell include isobutane, pentane, petroleum ether, hexane, low boiling point halogenated hydrocarbon, and methylsilane.

  Examples of such thermally expandable particles include “Matsumoto Microsphere F-20 Series”, “F-30 Series”, “F-36 Series”, and “F-46” manufactured by Matsumoto Yushi Seiyaku Co., Ltd. "Expancel WU" and "Same DU" sold by Nippon Philite Co., Ltd. can be used, but the thermally foamable resin used for the impregnated base paper is not limited to these.

  Since the heat-expandable particles do not self-fix, it is preferable to use a fixing agent. As this fixing agent, polyacrylamide type paper strength agent, polyamide epichlorohydrin type paper strength agent, polyethyleneimine type paper strength agent, starches such as starch, oxidized starch, carboxymethylated starch, plant gum, polyvinyl alcohol, Various known materials such as carboxymethyl cellulose can be used.

  In addition, about the addition amount of a chemical | medical agent added to the raw material pulp of each layer which comprises an impregnation base paper, a kind, etc. can be adjusted suitably.

By forming the impregnated base paper using the above raw material pulp, the density of the impregnated base paper (before applying the resin) is set to 0.3 to 0.5 g / cm ³ , and the book after the resin is impregnated and applied The paper thickness of the impregnated paper can be 550 to 770 μm.

By adjusting the density of the impregnated base paper, the resin impregnation property of the impregnated base paper can be adjusted. That is, if the density of the impregnated base paper is less than 0.3 g / cm ³ , the resin impregnation property of the impregnated base paper is improved, but since the impregnated base paper is impregnated with more resin than necessary, it takes time to dry and the work Inefficiency and manufacturing costs increase. On the other hand, if the density of the impregnated base paper exceeds 0.5 g / cm ³ , the resin impregnation property decreases, and the amount of resin impregnated and coated on the impregnated base paper decreases, so that the desired interlayer strength of the present invention is obtained. This makes it difficult to use the impregnated paper as a flooring material.

  Further, when the paper thickness of the impregnated paper after coating the resin on the impregnated base paper is less than 550 μm, when using, for example, a soft and poor surface veneer plywood as a plywood, the impact resistance is lowered, Since the unevenness formed on the surface of the flooring material cannot be covered, it is difficult to use the impregnated paper as the flooring material. In addition, the veneer plywood can be seen by applying the V-cut process, which causes a problem that the appearance as a flooring material is deteriorated and the quality is deteriorated. On the other hand, when the paper thickness of the impregnated paper exceeds 770 μm, the suitability of the impregnated paper as a flooring material decreases. Further, in order to make the paper thickness of the impregnated paper larger than 770 μm, it is necessary to increase the paper thickness of the impregnated base paper. However, if the paper thickness is too large for the impregnated base paper, the resin penetrates the impregnated base paper at the time of resin coating. The time until the time is increased, the operability is lowered, and the amount of resin to be used is increased, resulting in an increase in manufacturing cost. Furthermore, delamination is likely to occur, resulting in a problem that impact resistance is reduced. In addition, since the swelling occurs after the resin impregnation, the paper thickness of the impregnated base paper is preferably 400 to 500 μm.

  The impregnated base paper forming this impregnated paper is a Clem water absorbency (longitudinal) measured in accordance with “Paper and paperboard—Water absorption test method—Klem method” described in JIS-P8141 (2004). Water absorption (longitudinal) ") is 80-120 mm. TAPPI No. 41 (2000), the oil absorption measured in accordance with “Paper and paperboard—oil repellency test method—kit method” (hereinafter simply referred to as “oil absorption”) is 0.5 to 10 seconds. is there.

  When the impregnated base paper has a Klem water absorption (longitudinal) of less than 80 mm, the resin impregnation property is lowered and the amount of resin impregnation is reduced. Therefore, even after the resin is impregnated, the desired interlayer of the impregnated paper is obtained. Strength cannot be obtained and it becomes difficult to use as a flooring. On the other hand, if the Krem absorbency (longitudinal) exceeds 120 mm, the impregnating base paper is too high in resin impregnation, and the impregnated base paper is impregnated with more than the necessary amount of resin. At the same time, the manufacturing cost increases.

  Further, if the oil absorption of the impregnated base paper is less than 0.5 seconds, the resin impregnation property becomes too high, and the impregnated base paper is impregnated with more than the required amount of resin. At the same time, the manufacturing cost increases. On the other hand, when the oil absorption of the impregnated base paper exceeds 10 seconds, the resin impregnation property is lowered, the time until the required amount of resin is impregnated becomes long, and the operability is lowered.

  Further, the impregnated base paper constituting the impregnated paper has a strength (hereinafter referred to as “peeling”) according to “Paper and paperboard—Burn strength test method using a Murren high-pressure tester” described in JIS-P8131 (1995). It is preferable that the strength is 0.35 to 0.7 MPa. When the peel strength is less than 0.35 MPa, delamination is likely to occur, and it becomes difficult to use the impregnated paper as a flooring material. On the other hand, if the peel strength exceeds 0.7 MPa, the resin impregnation property is lowered and the operability may be lowered.

  The raw material pulp described above forms an impregnated base paper having three paper layers of a surface layer, a middle layer, and a back layer through a known papermaking process, for example, a wire part, a press part, a dryer part, a size press, a calendar part, and the like. . The paper making method of the impregnated base paper for forming the impregnated paper is not particularly limited, and any of acidic paper making method, neutral paper making method and alkaline paper making method may be used.

  Also, since the paper machine is not particularly limited, for example, various known paper machines such as a long net paper machine, a twin wire paper machine, a circular net paper machine, and a short net combination machine can be used. it can.

  The impregnated base paper formed as described above is impregnated with resin. Examples of the resin include rubber-based latex such as styrene / butadiene copolymer (SBR), acrylonitrile / butadiene copolymer (NBR), methyl methacrylate / butadiene copolymer (MBR), chloroprene polymer (CR), natural rubber latex ( NR), urethane resin-based latex and resin-based latex, and acrylic, vinyl acetate and the like and copolymers thereof, and curable resins such as phenol, melamine, diallyl phthalate (DAP), and epoxy can be used. . Among these, the use of a water-soluble melamine resin is more preferable because it is unlikely to cause sick house syndrome and the environmental load can be reduced. The impregnated paper is formed by impregnating and applying the impregnating liquid using such a resin to all layers constituting the impregnated base paper.

  The impregnation amount of the resin in the impregnated paper is 37 to 71%, preferably 40 to 60%, based on the basis weight of the entire impregnated base paper. If the resin impregnation amount is less than 37%, the desired interlayer strength of the present invention cannot be obtained, and delamination tends to occur, making it difficult to use the impregnated paper as a flooring. On the other hand, when the resin impregnation amount exceeds 71%, since the resin more than necessary is impregnated, it takes time to dry, the work efficiency is deteriorated, and the production cost is increased.

In order to make the impregnation amount of the resin within the above range, the basis weight of the impregnated base paper is preferably 170 to 200 g / m ² .

  As mentioned above, the case where the impregnated base paper is composed of the three layers of the surface layer, the middle layer, and the back layer has been described. However, the present invention is not necessarily limited to such an impregnated paper for flooring. In addition to this, for example, it may be an impregnated base paper composed of two paper layers, a front layer and a back layer, and further, the middle layer of the impregnated base paper is composed of two or more layers. You may comprise four or more paper layers. That is, the floor material impregnated paper having a plurality of intermediate layers may have a structure in which all layers including the intermediate layer are impregnated with the resin.

  In order to confirm the effect of the impregnated paper for flooring according to the present invention, the following various samples were prepared, and a test for evaluating the quality of each sample was performed. In addition, in a present Example, the numerical value which shows a mixing | blending, a density | concentration, etc. is a numerical value of the solid content or the mass reference | standard of an active ingredient. Moreover, since the pulp, chemical | medical agent, etc. which are shown in a present Example are only examples, it cannot be overemphasized that this invention is not restrict | limited by these Examples, and can be selected suitably.

  In order to compare and compare with 26 types of impregnated paper for flooring according to the present invention (referred to as “Example 1” through “Example 26”) and Examples 1 through 26, there are four types of paper. Impregnated paper for flooring (referred to as “Comparative Example 1” to “Comparative Example 4”) was prepared in the configuration shown in Table 1.

[Example 1]
Using the following raw materials, in accordance with the following production method, an impregnated base material for a flooring material having a four-layer structure composed of a surface layer, a back layer, and two middle layers located between both layers was obtained.
<Raw material>
・ Surface and back layers After blending 90% by weight of softwood bleached kraft pulp (NBKP) and 10% by weight of mechanical pulp (TMP), the raw material with Canadian Standard Freeness (CSF) adjusted to 700cc is used as a chemical fixing agent. Aluminum sulfate 0.5 mass% (50 kg / t), wet paper strength enhancer (WS4024 manufactured by Seiko PMC Co., Ltd.) 0.07 mass% (7 kg / t), dry paper strength enhancer (DS4356 manufactured by Seiko PMC Co., Ltd.) ) 0.1% by mass (10 kg / t) and 0.02% by mass (2 kg / t) of a sizing agent (DF6300 manufactured by Seiko PMC Co., Ltd.) to obtain a raw material pulp slurry for the front and back layers. .
・ Intermediate layer After blending 90% by weight of softwood bleached kraft pulp (NBKP) and 10% by weight of mechanical pulp (TMP), 0.5% by weight of aluminum sulfate as a chemical fixing agent is added to the raw material whose CSF is adjusted to 700cc. (50 kg / t), 0.07 mass% (7 kg / t) of wet paper strength enhancer (WS4024 manufactured by Seiko PMC Co., Ltd.), and 0.1 mass% of dry paper strength enhancer (DS4356 manufactured by Seiko PMC Co., Ltd.) (10 kg / t), 0.02% by mass (2 kg / t) of a sizing agent (DF6300 manufactured by Seiko PMC Co., Ltd.) was blended to obtain a pulp slurry for the middle layer.

Using these raw pulp slurries, the paper layers of the surface layer, the two middle layers, and the back layer are made with a circular net paper machine, the surface layer weight is 50 g / m ² , and the middle layer weight is 80 g. / ^{m 2,} 53g / ^{m 2} Paste amount of backing layer, the basis weight of the whole impregnation base paper to obtain a 183 g / ^{m 2} and is 4-ply flooring impregnated base paper (example 1).

  The impregnated base paper thus prepared is impregnated with a resin as shown in Table 1 in the amount of impregnation shown in Table 1 with respect to the basis weight of the entire impregnated base paper to form an impregnated paper.

  Further, impregnated base papers were prepared in the same manner as in Example 1 except for Examples 2 to 26 and Comparative Examples 1 to 4 except the conditions shown in Table 1. In addition, as a heat-expandable particle in a present Example, heat-expandable particle | grains (Matsumoto Yushi Seiyaku Co., Ltd. "Matsumoto microsphere F-46") and fixing agent (Hakuto Co., Ltd. "Hakutron KC100") are mixed beforehand. (Aggregated cationic polymer resin) was used.

  In addition, "CSF (cc)" in Table 1 is measured in accordance with "Paper and paperboard-Pulp freeness test method-Canadian standard freeness test method" described in JIS-P8121 (1995). It is the value.

In addition, “attachment amount (g / m ² )” refers to the delamination of each sample, and the basis weight of each layer was measured according to “paper and paperboard—basis weight measurement method” described in JIS-P8124. Value.

  The delamination was performed according to the following procedure. First, each sample obtained from each sample is immersed in water at room temperature for about 1 hour. Each sample immersed in water is wound around a round bar of about 10 mmΦ starting from a corner, and then the round bar is rolled to squeeze each sample. This operation is repeated starting from all four corners of each sample, and the ironing force is applied to the sample from each direction. Thereby, a part of the layers of each sample is peeled off, and this is used to separate the layers into the surface layer, the middle layer, and the back layer. After delamination, each layer of each sample was sufficiently dried with a hot air dryer or the like and used for the test.

  Table 2 shows the results of quality evaluation for all of these Examples and Comparative Examples. This quality evaluation test was performed under environmental conditions of temperature 23 ± 2 ° C. and humidity 50 ± 2% in accordance with JIS-P8111.

In addition, “basis weight (g / m ² )” in Table 2 is the basis weight of all the layers of each sample, that is, the entire impregnated base paper for flooring, and is described in “Paper and paperboard” described in JIS-P8124 (1998). It is the value measured based on "basis weight measuring method".

  “Paper thickness (μm)” is a value measured according to “Paper and paperboard—Test method of thickness and density” described in JIS-P8118 (1998).

“Density (g / cm ³ )” refers to the basis weight measured in accordance with “Paper and paperboard—basis weight measurement method” described in JIS-P8124 (1998) and JIS-P8118 (1998). It is a value calculated from the paper thickness measured according to “Paper and paperboard—Test method of thickness and density”.

  “Clem water absorption (mm)” is a value of water absorption in the vertical direction measured according to “paper and paperboard—water absorption test method—Klem method” described in JIS-P8141 (2004).

  "Oil absorption (seconds)" TAPPI No. 41 (2000), which is a value measured according to “Paper and paperboard—oil repellency test method—kit method”.

  “Peel strength (MPa)” is the value measured in accordance with the rupture strength test method by “Paper and paperboard-Mullen high pressure type tester” described in JIS-P8131 (1995) as the delamination strength. It is.

  "Interlaminar strength (N / 15mm)" is based on "Adhesive tape / adhesive sheet test method-Tensile strength" described in JIS-Z0237 (2000). It is a value measured by changing to N / 15 mm.

  “Contamination” means a sample of 30 cm × 30 cm visually checked for no contamination in the sample, ◎ if there are only less than 2 mm contamination, △, 4 mm if it can be confirmed up to 2-4 mm Excess impurities were evaluated as x.

“Bending” is an evaluation of interlayer strength. Each sample, which is impregnated paper, was bent at 90 ° and 180 °, and the occurrence of cracks was visually confirmed and evaluated. The evaluation criteria were as follows.
○: No crack occurred.
○ △: Cracks are starting to occur.
Δ: Slightly cracked.
X: Cracking has occurred.

"Cellophane tape" evaluates the surface strength. A cellophane tape with a width of 15 mm and a length of 150 mm is applied to the impregnated paper in the vertical direction, a 5 kg load is applied for 5 minutes, and then the cellophane tape is applied. The peeled surface of the cellophane tape at the time of peeling was observed and evaluated. The evaluation criteria were as follows.
○: The cellophane tape is peeled cleanly.
Δ: The impregnated paper surface is slightly peeled off.
X: The impregnated paper surface and the fibers are peeled off together.

  The “cross grid” is an evaluation of interlayer strength. The evaluation method is to use a grid with a width of 2 mm and a depth of 0.3 mm vertically and horizontally in the flow direction of the surface of the impregnated paper impregnated with the impregnated base paper as each sample, and cut with a 100 mm cutter. Then, a cellophane tape was applied to the surface of the impregnated paper, and then the cellophane tape was forcibly removed. In this case, the evaluation was performed by counting the cells where the layers were not separated. In the table, it is expressed as “the number of remaining wrinkles / 100 wrinkles”.

“Comprehensive evaluation” is a comprehensive evaluation of resin permeability, interlaminar strength (vertical / horizontal), bending, cellophane tape, and grid, and the evaluation criteria are as follows. .
A: Satisfactory.
○: Satisfied.
Δ: Slightly satisfactory
X: Not satisfied.

From Table 2, it can be seen that the floor material impregnated paper according to the present invention has high interlayer strength, impact resistance, and can cover the unevenness formed on the surface of the floor material.

Claims (3)

An impregnated paper for flooring formed by impregnating and applying a resin to a base paper of a multi-layered paper having at least two paper layers of a front layer and a back layer,
70 to 90% by mass of NBKP and 10 to 30% by mass of mechanical pulp are blended in the raw material pulp constituting each layer of the impregnated base paper,
The resin is a curable resin;
The impregnated base paper has a density of 0.3 to 0.5 g / cm ³ measured according to “Paper and paperboard—Test method of thickness and density” described in JIS-P8118 (1998),
The impregnated paper has a paper thickness of 550 to 770 μm,
In addition, the impregnated paper has an interlayer strength measured in accordance with “Adhesive tape / adhesive sheet test method—tensile strength” described in JIS-Z0237 (2000): longitudinal: 350 N / 15 mm or more, lateral: 200 N / 15 mm or more. Impregnated paper for flooring, characterized in that The raw pulp constituting each layer of the impregnated base paper has a freeness measured in accordance with “Paper and paperboard—pulp freeness test method—Canadian standard freeness test method” described in JIS-P8121 (1995). The impregnated paper for flooring according to claim 1, wherein the paper is adjusted to 600 to 750 cc. The impregnated base paper has a Klem water absorption of 80 to 120 mm measured according to “Paper and paperboard—Water absorption test method—Klem method” described in JIS-P8141 (2004),
In addition, J. of the impregnated base paper. TAPPI No. 41. The oil absorption measured in accordance with “Paper and paperboard—oil repellency test method—kit method” described in No. 41 (2000) is 0.5 to 10 seconds. 2. Impregnated paper for flooring according to 2.