JP5595656B2 - 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 that it becomes worse and a problem with dimensional stability. 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 hard 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 unevenness formed on the surface of the flooring. , So that no wavy is formed. In addition, since the impregnation rate of the impregnation liquid is high and a large amount of chemical liquid is required, it is uneconomical and the impact resistance is ensured by relying on the thermosetting resin of the impregnation liquid. There is also a limit to the properties, and there is still a problem in impact resistance.

  Furthermore, with the recent increase in demand for wood, the price of veneer has soared, making it difficult to obtain veneer 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, 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. It is necessary to absorb a large amount, and the cost is becoming uneconomical.

  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. Therefore, a method of laminating two sheets of kraft paper with a thickness of about 0.3 mm is used, but there is a problem that the peel strength is reduced on the laminating surface of the kraft paper and the processing steps are increased. In order to improve the peel strength of these bonded surfaces, it is necessary to increase the amount of impregnation liquid.

  In addition, since the conventional kraft paper has poor impregnation with resin, the impregnation liquid has a low penetration rate, which causes problems in terms of production efficiency and excessively increases the amount of impregnation liquid impregnated. It was. For this reason, it was difficult to obtain the impact resistance required for use as a flooring. Therefore, there are means such as increasing the freeness of the raw material pulp to improve the impregnation property, lowering the press linear pressure and calender linear pressure in the paper making process, but only that means any means of entanglement between the pulp fibers. As a result, the strength between fibers decreases, the interlaminar strength as an impregnated paper for flooring cannot be ensured, and it is difficult to ensure impact resistance.

JP 2007-77726 A JP 2003-314043 A JP 2002-172604 A JP 2006-46053 A JP 2000-302900 A

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an impregnated paper for flooring that is excellent in impact resistance and dimensional stability even if the amount of impregnation liquid is reduced. It is to provide.

The object of the present invention is to impregnate an impregnating liquid mainly composed of a thermosetting resin and a thermoplastic resin into a paper base material composed of a base paper of a multilayer paper having at least two paper layers, a surface layer and a back layer. Alternatively, it is an impregnated paper for flooring formed by coating, and the paper base material has a disaggregation freeness measured according to JIS-P8121 (1995) of 600 to 700 cc, and conforms to JIS-P8118 (1998). analogously basis weight as measured is 200 to 600 g / ^{m 2,} and JIS-P8118 density measured according to the (1998) is 0.65~1.0g / cm ^3, wherein the impregnation solution, the heat A melamine resin is included as a curable resin, and at least an acrylic resin and a styrene-butadiene (SBR) resin are included as the thermoplastic resin, and a resin impregnation rate with respect to the paper base material 7-30%, and the impregnation liquid has a mixing ratio of the melamine resin: the acrylic resin: the SBR resin of 0.5-5.0: 72-79: 16-27, and JIS-A5905 The water absorption thickness expansion coefficient measured according to JIS is 7-20%, and the impregnated paper for flooring has an impact resistance measured according to JIS-K5600-5-3 (1999) of 0.3- This is achieved by providing an impregnated paper for flooring characterized in that it is 0.7 mm.

  According to the impregnated paper for flooring according to the present invention, the paper base material is impregnated or coated with an impregnating liquid mainly composed of a thermoplastic resin so that the impact resistance is 0.3 to 0.7 mm. Therefore, the impregnation liquid is not excessively impregnated as in the conventional impregnated paper, and even with a low impregnation amount, the impact resistance and the dimensional stability are excellent, and further, the economy is excellent.

  Hereinafter, the impregnated paper for flooring according to the present invention will be described in detail. The impregnated paper for flooring according to the present invention is not limited to the following embodiment, and it is needless to say that the configuration can be changed as appropriate without departing from the scope of the claims.

  The impregnated paper for flooring according to the present invention (hereinafter referred to as “the present impregnated paper”) is formed by impregnating or coating an impregnating liquid containing a thermoplastic resin as a main component on a paper base material. And the impact resistance test value (henceforth "impact resistance") measured by this according to the "DuPont impact test" of JIS-K5600-5-3 (1999) of this impregnation paper is used. 0.3 to 0.7 mm, more preferably 0.4 to 0.6 mm. If the impact resistance is less than 0.3 mm, the impact cannot be absorbed, and the impregnated paper tends to break, so that it becomes difficult to use the impregnated paper for flooring. On the other hand, if the impact resistance exceeds 0.7 mm, the amount of dents becomes large, which causes a problem that the surface strength as a flooring cannot be maintained.

  As thermoplastic resins, rubber-based latexes such as SBR (styrene / butadiene copolymer), NBR (acrylonitrile / butadiene copolymer), MBR (methyl methacrylate / butadiene copolymer), CR (chloroprene polymer), NR ( Natural rubber latex), urethane resin-based latex, and resin-based latex include acrylic, vinyl acetate, and the like, copolymers thereof, acrylic resins, urethane resins, PVA, and the like. Among these, in order to satisfy both desired impact resistance and water absorption thickness expansion coefficient, it is preferable to use a combination of two types of acrylic resin and SBR. As described above, when two kinds of chemicals, acrylic resin and SBR, are combined, the impregnating liquid as in this impregnated paper has a low impregnation amount as will be described later, and the impact resistance, dimensional stability, etc. necessary for the flooring are reduced. Quality could be ensured.

  Further, the impregnating liquid containing the thermoplastic resin as a main component contains a water-soluble melamine resin that is a thermosetting resin, and the thermoplastic resin is a water-soluble acrylic resin and a styrene-butadiene (SBR) resin. By doing so, the impregnation ratio of the impregnating liquid to the paper base material can be reduced to 7 to 30% and a low impregnation amount.

  As the thermosetting resin, a hard resin such as phenol, melamine, DAP (diallyl phthalate), or epoxy resin can be used. However, since phenol and DAP resins are solvent-based resins, melamine resins are water-soluble resins. Therefore, melamine resins are particularly preferable from the viewpoint of workability of impregnation coating. Moreover, although the reason is not certain, it is considered that the compatibility with the water-soluble acrylic resin is better than that of phenol and DAP, and it is cured uniformly. By combining with the above thermoplastic resin, the impregnation liquid improves the permeability of the paper base material to the paper layer, so that even if the impregnation amount is low, the impregnation liquid is formed on the surface with the desired impact resistance. It is excellent in the covering property of the unevenness and can maintain the cushioning property and the dimensional stability.

  Moreover, it is preferable that Tg (glass transition temperature) of acrylic resin and SBR resin which are thermoplastic resins is -15-15 degreeC, More preferably, it is -5-5 degreeC. When Tg is less than −15 ° C., the mechanical stability is poor, and a film is formed / attached on a roll or the like during production, which is unfavorable during actual production. On the other hand, if the Tg is 15 ° C. or higher, the resin is hard, so that the impact resistance cannot be made within a desired range, and it becomes difficult to use the impregnated paper as a flooring.

  Further, the resin impregnation rate of the impregnating liquid in the impregnated paper is preferably 7 to 30%, more preferably 15 to 25% with respect to the basis weight of all layers of the paper substrate. Thus, if the resin impregnation rate is less than 7%, the desired interlaminar strength of the impregnated paper cannot be obtained and delamination tends to occur. Therefore, the impregnated paper can be used as a flooring. It becomes difficult. On the other hand, if the resin impregnation rate exceeds 30%, the impact resistance is lowered, and the impregnated paper cannot be used as a flooring material. In addition, since more than the necessary amount of resin is impregnated, drying takes time, work efficiency is deteriorated, and production costs are increased.

  Further, in the above impregnating liquid, the mixing ratio of the thermosetting resin and the thermoplastic resin is preferably melamine resin: acrylic resin: SBR = 0.5 to 5.0: 72 to 79:16 to 27, and 1: It is more preferable that it is 74:25. When the ratio of the melamine resin is less than 0.5%, thermosetting after impregnation is insufficient, and it becomes difficult to satisfy the desired dimensional stability. On the other hand, if the ratio of the melamine resin exceeds 1.0%, thermosetting is accelerated, so that it is difficult to sufficiently impregnate the impregnating liquid up to the inside of the paper layer of the paper base material. It becomes difficult to satisfy the interlayer strength.

  Further, if the acrylic resin ratio is less than 72%, it becomes difficult to satisfy the interlayer strength after impregnating the paper base material with the impregnating liquid, while if the acrylic resin ratio exceeds 79%, The balance with the curable resin makes it difficult to satisfy the dimensional stability.

  Further, if the SBR ratio is less than 16%, the fluidity and viscosity of the impregnating liquid are lowered, and the impregnation liquid tends to be excessively impregnated inside the paper layer of the paper base material. It becomes difficult to use this impregnated paper as a flooring material. On the other hand, if the SBR mixing ratio exceeds 27%, the fluidity and viscosity of the impregnating liquid tend to increase, and the impregnation of the impregnating liquid into the paper layer of the paper base tends to deteriorate. Therefore, it becomes difficult to use the impregnated paper as a flooring material.

  The impregnated paper using the impregnating liquid in which the thermosetting resin and the thermoplastic resin have the above mixing ratio is the water absorption thickness measured in accordance with “Water absorption thickness expansion coefficient” described in JIS-A5905 (2003). The expansion coefficient (hereinafter simply referred to as “water absorption thickness expansion coefficient”) is preferably 7 to 20%. When the water absorption thickness expansion coefficient is less than 7%, it is considered that the impregnating liquid is excessively impregnated in the paper base material, and thus the above-described impact resistance desired by the present invention cannot be satisfied. If the water absorption thickness expansion coefficient exceeds 20%, it absorbs water and expands, making it difficult to use as an impregnated paper for flooring.

  In addition, the impregnation liquid, as long as the above-described thermosetting resin and thermoplastic resin are included, in addition, within a range that does not affect the effect of the present invention, for example, a lubricant, a sizing agent, a filler dispersant, pH adjuster, thickener, fluidity improver, antifoaming agent, antifoaming agent, mold release agent, penetrating agent, coloring dye, coloring pigment, UV absorber, antioxidant, preservative, antibacterial agent, water resistance Known additives such as an agent and a fluorescent quencher may be added alone or in admixture of two or more.

Hereinafter, the paper base material used for this impregnation paper is explained in full detail. This paper base material is a multi-layer paper having at least two paper layers, a front layer and a back layer, and the freeness after disaggregation measured in accordance with JIS-P8121 (1995) (hereinafter referred to as “disaggregation freeness”). Is 600 to 700 cc, the rice basis weight measured according to JIS-P8118 (1998) is 200 to 600 g / m ² , and the density is 0.65 to 1.0 g / cm ³ .

  The raw material pulp of each layer constituting the paper base material used in the impregnated paper includes hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), and softwood unbleached kraft pulp ( NUKP), hardwood sulfite pulp, softwood sulfite pulp and other wood fibers as main raw materials, chemically treated pulp, chemically treated pulp and ground pulp mechanically pulped into chips, and warming Thermomechanical pulp (TMP) in which chips are mechanically pulped under pressure, Chemi-ground pulp mechanically pulped with chemicals added to wood or chips, and refiner after cooking chips until soft For example, virgin pulp such as semi-chemical pulp obtained by pulping or the like can be used. In addition, non-wood fibers such as kenaf, hemp, straw, etc., which are fiber materials other than wood, can be used, but non-wood pulp is weak in pulp strength, and the unit price of the pulp itself is high, so the cost is also high, It is preferable to use kraft pulp such as NBKP and mechanical pulp such as TMP. Although pulp made from waste paper may be blended, there is a problem that there are a lot of fine fibers, so the drainage of the paper base material deteriorates, the production speed decreases, and the paper base material is impregnated with the impregnation liquid. The appearance of the later paper surface deteriorates and the interlayer strength also decreases. Therefore, it is preferable not to mix the waste paper pulp with the raw material pulp forming the surface layer and the back layer. In addition, when forming a paper base material with three or more paper layers of a surface layer, an at least 1 layer of middle layers, and a back layer, it is preferable not to mix | blend waste paper pulp also with the raw material pulp which forms a middle layer.

  Furthermore, it is preferable to use NBKP for 0 to 20% by mass of the entire raw pulp (raw pulp of all layers) constituting each layer of the paper base material used for the impregnated paper, and more preferably 5 to 15% by mass. preferable. When the blending ratio of NBKP exceeds 20% by mass, the texture is deteriorated, and after impregnating with the resin, a fluttering pattern tends to appear during press working. That is, the impregnation of the impregnating liquid becomes non-uniform, and there is a problem that it may be difficult to ensure the interlayer strength necessary for the impregnated paper. Moreover, 80-100 mass% is preferable, and, as for the compounding rate of LBKP, More preferably, it is 85-95 mass%.

  Since the present impregnated paper is formed by impregnating or applying the above impregnating liquid to the paper base material, each layer of the paper base material is preferably made using a raw material pulp having the same composition. When the substrate is formed from three or more paper layers, paper may be made using raw pulps having different formulations from the surface layer, middle layer, and back layer, such as mixing old paper in the middle layer raw material pulp.

  Moreover, the paper base material used for this impregnated paper is prepared so that the disaggregation freeness may be 600 to 700 cc, more preferably 620 to 670 cc. When the disaggregation freeness is less than 600 cc, the resin impregnation property of the paper base material is deteriorated. In addition, when the disaggregation freeness exceeds 700 cc, in addition to the formation being deteriorated, the resin impregnation is hindered, and the impregnation liquid does not uniformly impregnate the paper base material, resulting in a decrease in interlayer strength. Will occur.

Furthermore, the paper base material used for the impregnated paper has a density of 0.65 to 1.0 g / cm ³ , more preferably 0.7 to 0.9 g / cm ³ . When the density of the paper base material used for the impregnated paper is less than 0.65 g / cm ³ , the impregnation liquid is excessively impregnated, and it is difficult to obtain a desired resin impregnation property. On the other hand, if the density of the paper base material used for the impregnated paper exceeds 1.0 g / cm ³ , the impregnation liquid becomes difficult to impregnate, and similarly, it becomes difficult to obtain a desired resin impregnation property.

  Further, it is preferable to add a wet paper strength enhancer and a dry paper strength enhancer to the raw pulp of at least one layer (or all layers) of the paper substrate. Thereby, the processability when impregnating or applying the impregnating liquid to the paper base material can be improved, and the interlayer strength of the impregnated paper can be further increased.

  In the case where the wet paper strength enhancer is not blended, the processing suitability may be lowered, for example, paper breakage may occur when the impregnation liquid is impregnated or applied to the paper base material. On the other hand, when the dry paper strength enhancer is not blended, the interlaminar strength of the impregnated paper after impregnating or applying the impregnating liquid to the paper base material is lowered, making it difficult to use the impregnated paper as a flooring. 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 paper base material.

  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. Moreover, as a dry paper strength enhancer, anionic or cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan and the like can be used. However, the wet paper strength enhancer and the dry paper strength enhancer used for the paper substrate are not limited to these.

  Moreover, since the resin impregnation property of a paper base material will fall by adding said paper strength enhancer, a sizing agent is added to the raw material pulp which forms the layer which adds a paper strength enhancer. In addition to the sizing agent, chemicals such as a liquid absorbent and a bulking agent can be added in order to impart resin impregnation to the paper substrate. 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, about the addition amount, kind, etc. of the chemical | medical agent added to the raw material pulp of each layer which comprises a paper base material, it can adjust suitably.

  The raw material pulp described above is a paper used for the impregnated paper having at least two paper layers, a front 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, etc. A substrate is formed. The paper base paper making method used for the impregnated paper is not particularly limited, and may be any of acidic paper making method, neutral paper making method and alkaline paper making method. 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 paper basis of the paper base used for the impregnated paper (total basis weight of all layers of the paper base) is 200 to 600 g / m ² , more preferably 210 to 510 g / m ² , and still more preferably 215 to 510 g / m ² . a m ^2. As a result, the impregnation rate of the impregnating liquid is set within the desired range of the present application, and the impregnated paper can be used as a flooring material. If the paper base of the paper base is less than 200 g / m ² , the impact resistance will be low, so that the impregnated paper formed using such a paper base is difficult to use as a flooring. Become. On the other hand, if the paper basis of the paper substrate exceeds 600 g / m ² , the resin impregnation property is deteriorated, and similarly, it is difficult to use as a flooring material.

  Moreover, the resin impregnation property of the paper base material used for this impregnation paper is 0.5 to 3.0 seconds, More preferably, it is 0.7 to 1.2 seconds. In the impregnating liquid, the paper base is more easily impregnated with the solvent (water) than the resin in the impregnating liquid. For this reason, if the resin impregnation property of the paper base material is less than 0.5 seconds, the apparent resin impregnation rate immediately after impregnation increases, but when dried, the solvent evaporates, and the resin impregnation rate decreases. Thus, it becomes difficult to obtain a desired resin impregnation rate of the impregnated paper, and such impregnated paper cannot be used as a flooring material. On the other hand, if the resin impregnation property of the paper base material exceeds 3.0 seconds, the paper base material cannot be sufficiently impregnated with the resin, so that it becomes difficult to use the paper base material as well. In addition, the resin impregnation property in this specification refers to measuring the time until the impregnating liquid permeates the surface opposite to the surface in contact with the impregnating liquid after a piece of paper (paper base material) is floated on the impregnating liquid. Say the value.

As described above, the paper base material used for the impregnated paper is composed of two or more layers, a disaggregation freeness of 600 to 700 cc, a rice floor of 200 to 600 g / m ² , and a density of 0.00. The object of the present invention can be achieved only by setting the concentration to 65 to 1.0 g / cm ³ . That is, it is possible to provide a paper base material used for the present impregnated paper, which is excellent in impact resistance and dimensional stability, and can cover the unevenness formed on the surface of the flooring. In addition, in this specification, dimensional stability is measured based on the "water absorption thickness expansion coefficient" prescribed | regulated to JIS-A5905 (2003) fiber board, and when immersed in normal temperature water for 24 hours, The water absorption thickness expansion coefficient.

  The impregnated paper formed as described above can have an interlaminar strength of 0.8 to 2.0 MPa, more preferably 0.8 to 1.2 MPa, measured according to the JAS plywood plane tensile test. . When the interlaminar strength is less than 0.8 MPa, the paper base material is destroyed when the impregnated paper is used as a flooring material, so that it cannot be used as a flooring material. On the other hand, when the interlayer strength exceeds 2.0 MPa, it is difficult to satisfy the above-described impact resistance because the impregnation liquid is excessively impregnated.

  In addition, the method of impregnating or applying the above-mentioned impregnation liquid to the paper substrate includes a dipping squeeze type impregnating machine, a dipping scraping type impregnating machine, a bar coater, a blade coater, an air knife coater, a rod blade coater, a gate roll coater, and Various known methods such as a roll coater such as a size press, a bill blade coater, a bellbapa coater, and a calender roll coater can be used. It is more preferable because it can be impregnated.

As described above, it is an impregnating liquid containing a thermosetting resin (particularly melamine resin) and a thermoplastic resin (particularly acrylic resin and SBR resin) and containing thermoplastic resin as a main component. Further, melamine resin: acrylic resin : The impregnating liquid in which the mixing ratio of the SBR resin is 0.5 to 5.0: 72 to 79:16 to 27 has at least two paper layers of a front layer and a back layer, and a disaggregation freeness is 600 to 700 cc. By impregnating or coating a paper base having a rice basis weight of 200 to 600 g / m ² and a density of 0.65 to 1.0 g / cm ³ to form the impregnated paper, impact resistance The impregnation ratio of the impregnating liquid with respect to the paper substrate can be set to 7 to 30%, and the water absorption thickness expansion coefficient can be set to 7 to 20%. Can be achieved efficiently. That is, it is possible to obtain and provide an impregnated paper for flooring that is excellent in cushioning properties, impact resistance, and dimensional stability, and that can cover the unevenness formed on the surface of the flooring.

  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.

21 types of impregnated paper for flooring according to the present invention (referred to as “Example 1” to “Example 21” . However, “Examples 2, 4 to 6, 12, 14” are referred to as “Reference Example 2”. 4 to 6, 12, 14 " ) and three types of impregnated paper for flooring (referred to as" Comparative Example 1 ") for comparison with these Examples 1 to 21. To “Comparative Example 3”) as shown in Tables 1 and 2.

[Example 1]
Using the following raw materials, in accordance with the following production method, a four-layer paper base material composed of a surface layer, a back layer, and two middle layers located between both layers is created, and this paper base material is used for flooring Impregnated paper was obtained.
<Raw material>
-Surface layer, middle layer and back layer As shown in Table 1, after blending 10% by mass of softwood bleached kraft pulp (NBKP) and 90% by mass of hardwood bleached kraft pulp (LBKP), it is described in JIS-P8121 (1995). Of paper and paperboard-Pulp freeness test method-Canadian standard freeness test method "Disaggregation freeness (raw material adjusted so that" Freeness (cc) "in Table 1 is 645 cc) In addition, 0.7% by mass of aluminum sulfate as a fixing agent (sulfuric acid band), 0.3% by mass of WS4024 manufactured by Seiko PMC Co., Ltd. as a wet paper strength enhancer, and manufactured by Seiko PMC Co., Ltd. as a dry paper strength enhancer DS4356 of 0.8% by mass and 0.02% by mass of a sizing agent (DF6300 manufactured by Seiko PMC Co., Ltd.) were blended, and the raw pulp slurry for the surface layer, middle layer and back layer was blended. Using these raw pulp slurries, the surface layer, the middle layer of the two layers, and the back layer of the paper layer were made with a circular paper machine, and the amount of the surface layer applied was 57 g / m ² . A four-layer paper base having a total weight of 226 g / m ² , a back layer weight of 57 g / m ² and a basis weight of the entire impregnated base paper of 340 g / m ² was obtained.
<Impregnating liquid>
As shown in Table 2, a melamine resin (manufactured by DIC Corporation, J-101) was used as a thermosetting resin so that the mixing ratio of melamine resin: acrylic resin: SBR resin was 1:74:25. 1 mass%), 74 mass% of acrylic resin (manufactured by Seiko PMC Co., XP-8806) and 25 mass% of SBR (manufactured by Nippon Zeon Co., Ltd., LX-430) are blended as thermoplastic resins. To prepare an impregnating solution. The glass transition temperature (Tg) of the resin was 0 ° C.
<Preparation of impregnated paper>
An impregnated paper (Example 1) is prepared by impregnating and applying the above-mentioned impregnation liquid to the paper base material at a ratio of 20% with respect to the paper base material using a dipping squeeze type impregnation machine.

  Further, Examples 2 to 21 and Comparative Examples 1 to 3 were produced by impregnating a paper base material and a coating solution in the same manner as in Example 1 except for the conditions shown in Tables 1 and 2. In addition, as an impregnation liquid in a present Example, "Phenol" of the column of the thermosetting resin in Table 2 is J325 by DIC Corporation, "DAP" is diallyl phthalate, Daiso by Daiso Corporation A dap was used. In Table 2, “urethane” in the column of thermoplastic resin is urethane resin acrylic, Aqualinker SU710 manufactured by Konishi Co., Ltd. is used, and “PVA” is polyvinyl alcohol. The company Gohsenol N300 was used.

  “Freeness (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). The disaggregation freeness value.

  Table 1 shows the results of quality evaluation of the paper base materials of all the examples, and Table 2 shows the results of quality evaluation of the impregnated paper prepared by impregnating all examples and comparative examples with the impregnation liquid. It was as shown. This quality evaluation test was performed under environmental conditions of temperature 23 ± 2 ° C. and humidity 50 ± 2% in accordance with JIS-P8111.

In Table 1, “US basis weight (g / m ² )” is the basis weight of the entire paper substrate used for each sample, that is, the impregnated paper for flooring that is each sample, and is JIS-P8124 ( 1998) described in “Paper and paperboard—basis weight measurement method”.

  “Paper thickness (μm)” in Table 1 is a value measured according to “Paper and paperboard—Test method of thickness and density” described in JIS-P8118 (1998).

“Density (g / cm ³ )” in Table 1 is a value calculated from basis weight and paper thickness.

  “Clem water absorption (10 minutes) (mm)” in Table 1 is for evaluating liquid absorbency, and the evaluation method is a value measured according to JIS-P8141.

  “Oil absorption (seconds)” in Table 1 is an evaluation of liquid absorption time. TAPPI No. Measured in accordance with “Paper—Water Absorption Test Method—Part 2: Dropping Method” described in 32-1. TAPPI No. 41 (2000) and measured using the kit 6 solution described in “Paper and paperboard—oil repellency test method—kit method”.

  “Peel strength (Mpa)” in Table 1 is an evaluation of interlaminar strength. According to “Paper and paperboard-Muren high-pressure type tester based on burst strength test method” described in JIS-P8131 (1995). It is a measured value.

  The “resin impregnation rate (%)” in Table 2 is an evaluation of the resin permeability of the paper substrate. A paper piece is placed on the resin impregnating solution, and the resin impregnating solution penetrates to the opposite surface. The value (seconds) measured until the time.

  “Resin impregnation (seconds)” in Table 2 indicates the time until the impregnating liquid permeates the surface opposite to the surface in contact with the impregnating liquid after the paper base material as a sample floats on the impregnating liquid. Say the measured value.

  “Impact resistance” in Table 2 is an evaluation of the amount of dents, and the amount of dents measured in accordance with the DuPont falling ball impact dent test specified in “Paint General Test Method” described in JIS-5600 ( mm). The measurement conditions were a drop weight of 710 g, a drop height of 30 cm, and a ball radius of 6.35 mm.

“Water absorption thickness expansion rate (%)” in Table 2 is an evaluation of dimensional stability in the Z-axis direction during water absorption. The evaluation method is a method prescribed in JIS-A5905 (2003) fiberboard, and the following (several numbers) are obtained from the paper thickness of the paper base before and after water absorption when immersed in normal temperature water for 24 hours. 1) (Equation 1)
Water absorption thickness expansion rate (%) = (paper thickness after water absorption−paper thickness before water absorption) / paper thickness before water absorption × 100
Furthermore, the “interlayer strength” in Table 2 is the maximum load (Mpa) at the time of peeling or breaking measured according to the JAS plywood plane tensile test.

From Table 2 of this example, the floor material impregnated paper according to the present invention is excellent in cushioning properties, impact resistance, and dimensional stability, and can cover unevenness formed on the surface of the floor material. I understand that I can do it.

Claims (1)

It is formed by impregnating or applying an impregnating solution mainly composed of a thermosetting resin and a thermoplastic resin to a paper base material composed of a base paper of a multi-layered paper having at least two paper layers, a front layer and a back layer. Impregnated paper for flooring,
The paper substrate, macerated freeness were measured in accordance with JIS-P8121 (1995) is 600～700Cc, basis weight was measured according to JIS-P8118 (1998) is 200 to 600 g / ^{m 2,} and The density measured according to JIS-P8118 (1998) is 0.65 to 1.0 g / cm ³ ,
The impregnation liquid contains a melamine resin as the thermosetting resin, and includes at least an acrylic resin and a styrene-butadiene (SBR) resin as the thermoplastic resin, and has a resin impregnation rate of 7 to 30 with respect to the paper base material. And the impregnating liquid has a mixing ratio of the melamine resin: the acrylic resin: the SBR resin of 0.5 to 5.0: 72 to 79:16 to 27, according to JIS-A5905. The measured water absorption thickness expansion coefficient is 7 to 20%,
The floor material impregnated paper is characterized in that the impact resistance measured according to JIS-K5600-5-3 (1999) is 0.3 to 0.7 mm.