PAPER TREATMENT AGENT AND PAPER USING SAME, AND METHOD FOR IMPROVING PAPER TEXTURE

Description

Technical Field

[0001] The present invention relates to a paper treatment agent and paper using same, and a method for improving paper texture.

Background Art

[0002] Paper products such as toilet paper and tissue are required to have a soft and moist texture, and paper products treated with paper treatment agents containing a moisturizing component, such as moisturizing tissue with a soft touch, are widely used throughout the year. Such paper, including this moisturizing tissue, is coated with a paper treatment agent that contains a polyhydric alcohol such as glycerin for providing flexibility. This flexibility is brought about by the reduction in hydrogen bonds in between the pulps due to an increase in the moisture content of the coated paper. This is problematic because reduced paper strength in high-humidity environments causes the paper to tear while low-humidity environments cause the paper to have deteriorated texture. Therefore, there is a need for paper products such as moisture-retaining tissues that are less dependent on the humidity environment.

[0003]  Further, of the papers that are treated with paper treatment agents containing moisturizing ingredients, moisturizing tissues are often used for blowing the nose, and a product having a favorable texture for reducing the burden on the skin such as the one exhibiting reduced surface friction has been required. It is also desired for papers, intended to provide moisture-retaining properties, to have textures that commercially match the user's taste.

[0004] Heretofore, various measures have been taken to solve technical problems for imparting softness less dependent on the humidity environment and improving the texture. For example, PTL 1 proposes a fiber web product which is produced by making fiber webs contain a hydrous gel composition. However, there have been issues in gel compositions because uniform treatment of the gel composition in a state of gel prior to the coating to papers involves complex processes, and gel compositions are difficult to transport. PTL 2 takes advantage of the water absorbency of hydrophilic polymers for improving the moisty feeling. However, hydrophilic polymers require time and effort to uniformly disperse themselves, and therefore make the processes of producing paper treatment agent complex. Further, hydrophilic polymers cause significant thickening. For this reason, the additive amount of hydrophilic polymers had to be limited, which prevented sufficient effects from being achieved. PTL 3 employs an oil substance and a water-soluble wax for imparting softness or reducing friction. However, a water-soluble wax is problematic because it exhibits high viscosity, which in turn impairs the fluidity or uniform coating property of the paper treatment agent, and therefore worsens the operability.

[0005] PTLs 4 and 5 each contains glycerin, and branched alcohol or sucrose fatty acid ester for improving the softness and skin feel in low-humidity environments. Although these bases have the advantage of being easily formulated in moisturizers and can contribute to maintaining softness in low-humidity environments, they were not effective enough.

[0006] PTLs 6 to 9 describe sulfonates for use as surfactants that are blended into paper treatment agents.

Citation List

Patent Literature

[0007] 

PTL1: JP-A-2003-199685

PTL2: JP-A-2009-263837

PTL3: JP-A-H10-226986

PTL 4: JP-A-2007-107173

PTL 5: JP-A-2016-074999

PTL 6: JP-A-2019-099938

PTL 7: JP-A-2019-157307

PTL 8: JP-A-2008-073118

PTL 9: JP-A-2010-265562

Summary of Invention

Technical Problem

[0008] Although PTLs 6 to 8 each describes a sulfonate as optional component or as a component that is optionally selected from multiple types of surfactants in working examples, no discussion has ever been specifically made about the content of the sulfonate, and each reference specifically discloses a high amount of sulfonate, which makes it difficult to impart a unique texture termed herein as coreless softness to papers, no longer makes it possible to keep the fluidity in a state of paper treatment agent, and unintentionally raises an issue that it becomes hard.

[0009] PTL 9 describes sulfonate as a component that is optionally selected from surfactants. However, since the specifically disclosed product to which the sulfonate is added contains no water, such product raises problems of insufficient results, difficulty in bringing out unique texture, and texture deterioration under a low-humidity environment.

[0010] The present invention has been made in view of the above circumstances and it is an object of the present invention to provide a paper treatment agent that: can impart, to paper provided with moisture retention properties, a specific texture that matches a user's taste; brings about little change in moisture content in the paper between when the paper is in a high-humidity environment and when the paper is in a low-humidity environment; and can suppress moisture evaporation from paper even in a low-humidity environment as well as paper using such paper treatment agent, and a method for improving the texture of paper.

Solution to Problem

[0011] The inventor of the present invention diligently conducted studies for solving the above-mentioned objects and has found out that a paper treatment agent containing not only polyhydric alcohol but also sulfonate in a specific range of content as well as water imparts a unique, slimy, silk-like feel to paper. More surprisingly, the inventor has also found out that the agent imparts a coreless softness to paper and brings about little change in moisture content in the paper between when the paper is in a high-humidity environment and when the paper is in a low-humidity environment; and can suppress moisture evaporation from paper even in a low-humidity environment, and as a result of which has completed the invention. The term "unique, slimy, silk-like feel" as used herein refers to a slimy feel as if touching gel.

[0012] That is, the paper treatment agent according to the present invention is characterized by containing (A) polyhydric alcohol, (B) sulfonate, and (C) water, wherein the (B) sulfonate is contained therein in an amount from 0.05% by mass to less than 8.0% by mass relative to the total amount excluding water. The paper according to the present invention is characterized by a paper treated with the paper treatment agent.

[0013] The method for improving paper texture according to the present invention is characterized by comprising treating a paper with the paper treatment agent.

[0014] The paper treatment agent according to the present invention contains not only (A) polyhydric alcohol but also (B) sulfonate in a specific range of content as well as (C) water, where, in particular, the specific range of (B) sulfonate is uniquely combined with water (C) to thereby imparts a unique, slimy, silk-like feel and coreless softness to paper, brings about little change in moisture content in the paper between when the paper is in a high-humidity environment and when the paper is in a low-humidity environment, and can suppress moisture evaporation from paper even in a low-humidity environment.

[0015] Further, the paper treatment agent contains not only (A) polyhydric alcohol but also (B) sulfonate in a specific range of content as well as (C) water, where, in particular, the specific range of the sulfonate (B) is uniquely combined with (C) water to suitably keep the water content in the paper treatment agent of the present invention on the coated paper by which the swelling of pulps is suppressed compared to the one of the conventional paper treatment agent, which therefore allows papers to have and exhibit coreless softness.

[0016] This softness impartation is brought not only by the breakage of hydrogen bonds between pulps due to its water content but also by suitably making the paper less resilient by suppressing the swelling of paper. For this reason, a paper treated by the paper treatment agent of the present invention is less dependent on the humidity environment. Since this softness is less dependent on water content, the paper treated with the paper treatment agent of the present invention feels soft but does not lose its paper strength and, for example, is less prone to tearing.

[0017] The paper treatment agent according to the present invention can suppress moisture evaporation from paper even in a low-humidity environment. For this reason, the paper treatment agent is less likely to cause deterioration in texture in a low-humidity environment.

Advantageous Effects of Invention

[0018] The present invention allows impartation of a unique, slimy, silk-like feel and coreless softness to paper having moisture-retaining properties; brings about little change in moisture content in the paper between when the paper is in a high-humidity environment and when the paper is in a low-humidity environment; and can suppress moisture evaporation from paper even in a low-humidity environment. These advantageous effects are significant that is far beyond the scope of effects that a person skilled in the art could have predicted from the features of the present invention.

Description of Embodiments

[0019] The present invention will be described in greater detail below.

[0020] The term "texture" as described herein in the present invention particularly encompasses a unique, slimy, silk-like feel and a coreless softness which has a less resilient feel with little fluffiness, reduces the burden to skin and reminds a user of gentleness to skin.

(Paper treatment agent)

[0021] The paper treatment agent of the present invention essentially comprises (A) polyhydric alcohol, (B) sulfonate, and (C) water.

(A) Polyhydric alcohol

[0022] In the paper treatment agent of the present invention, the polyhydric alcohol as the component (A) is a moisturizing agent that improves the moisture absorbency and moisture-retaining property of paper and imparts a moisty feeling and softness to the paper.

[0023] Examples of the polyhydric alcohol as the component (A) include, but are not particularly limited to, glycerin, diglycerin, triglycerin, polyglycerin, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, polypropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,2-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polyoxyethylene glycerin ether, isoprene glycol, pentaerythritol, and trimethylolpropane.

[0024] The component may be a sugar alcohol or a sugar. Examples of the sugar alcohol include sorbitol, inositol, glucosyltrehalose, xylitol, erythritol, mannitol, lactitol, fructose, oligosaccharide alcohols, maltitol, reduced palatinose, reduced starch syrup, and reduced starch hydrolysates. Examples of the sugar include fructose, glucose, lactose, xylose, psicose, malt suger, starch syrup, oligosaccharides, maltose, trehalose, lactose, palatinite, sucrose, isomerized sugar, isomaltooligosaccharides, fructooligosaccharides, galactooligosaccharides, xylooligosaccharides, lactofructose oligosaccharides, soybean oligosaccharides, raffinose, stevia, licorice, saccharin, aspartame, acesulfame K, and sucralose.

[0025] They may be used alone, or two or more of them may be used in combination.

[0026] Of these, preferred are glycerin, 1,3-butanediol, 1,2-propanediol and sorbitol, among which glycerin is more preferred.

[0027] The content of the polyhydric alcohol (A) is not particularly limited but may be, for example, more than or equal to 1% by mass relative to the total amount of the paper treatment agent excluding water. It is preferred in terms of improving the texture due to moisture absorbency of the polyhydric alcohol (A) on the coated paper that the content be more than or equal to 50% by mass, more preferably more than or equal to 70% by mass, even more preferably more than or equal to 80% by mass, particularly preferably more than or equal to 85% by mass, and most preferably more than or equal to 90% by mass relative to the total amount of the paper treatment agent excluding water. Further, it is preferred in terms of improving the texture specific to the present invention that the content be less than or equal to 99.5% by mass, more preferably less than or equal to 98% by mass relative to the total amount thereof excluding water.

(B) Sulfonate

[0028] The paper treatment agent of the present invention contains not only (A) polyhydric alcohol but also (B) sulfonate in a specific range of content as well as (C) water to impart a unique, slimy, silk-like feel and coreless softness to paper, bring about little change in moisture content in the paper between when the paper is in a high-humidity environment and when the paper is in a low-humidity environment, and suppress moisture evaporation from paper even in a low-humidity environment.

[0029] The sulfonate (B) contains at least one sulfonate structure (-SO₃X) and preferably contains hydrophobic and hydrophilic groups in which the hydrophilic group has a sulfonate structure (-SO₃X) to thereby exhibit interfacial activity. The hydrophobic group preferably contains an alkyl group.

[0030] The alkyl group in the sulfonate may, for example, contain, 4 to 30 carbon atoms (C4 to C30), which is not particularly limited. It is preferred in terms of the unique, slimy, silk-like feel and coreless softness, particularly in respect of improving the unique, slimy, silk-like feel that the number of carbon atoms in the alkyl group be 8 or more, more preferably 10 or more, even more preferably 14 or more, particularly preferably 16 or more. It is preferred in terms of making it more likely to be solubilized in the polyhydric alcohol and to more effectively exhibit the effects of the present invention that the number of carbon atoms in the alkyl group be 26 or less, more preferably 24 or less, even more preferably 22 or less, particularly preferably 18 or less. The term "number of carbon atoms" in the alkyl group as used herein is an integer. Also, such an alkyl group may be of a type that is unsaturated or saturated, and the group may be of a type that is linear or branched.

[0031] The sulfonate of the component (B) used in the present invention is not particularly limited, but examples thereof include an alkyl sulfonate, alkyl benzene sulfonate, alkylnaphthalene sulfonate, sulfosuccinate ester salt, sulfo fatty acid ester salt, α-olefin sulfonate, alkyloylalkyltaurine salt, and sodium methyl cocoyl taurate. They may be used alone, or two or more of them may be used in combination.

[0032] Of these, in respect of exhibiting advantageous effects of the present invention, preferred are an alkyl sulfonate, alkyl benzene sulfonate, sulfosuccinate ester salt, and sulfo fatty acid ester salt, among which an alkyl sulfonate, alkyl benzene sulfonate, and sulfosuccinate ester salt are more preferred.

[0033] Examples of the countercation for the sulfonate anion in the sulfonate (B) include, but are not particularly limited to, an alkali metal ion such as sodium ion and potassium ion.

[0034] Although the content of the sulfonate (B) relative to the total amount of the paper treatment agent excluding water is from 0.05% by mass to less than 8.0% by mass, it is preferred in respect of the unique, slimy, silk-like feel and improving coreless softness that the content relative to the total amount thereof excluding water be more than or equal to 0.1% by mass, more preferably more than or equal to 0.2% by mass, even more preferably more than or equal to 0.4% by mass, still more preferably more than or equal to 0.7% by mass, further preferably more than or equal to 1.5% by mass, and particularly preferably more than or equal to 2.0% by mass. It is also preferred in respect of enhancing the flowability of the paper treatment agent that the content be less than or equal to 7.9% by mass, more preferably less than or equal to 6.0% by mass, and even more preferably less than or equal to 5.0% by mass relative to the total amount of the paper treatment agent excluding water.

[0035] In the paper treatment agent of the present invention, it is preferred in respect of the unique, slimy, silk-like feel and improving the coreless softness that the mass ratio of the sulfonate (B) to the polyhydric alcohol (A) (Component (B)/Component (A)) be 0.001 or more, more preferably 0.007 or more, even more preferably 0.015 or more, and particularly preferably 0.02 or more. It is also is preferred in respect of the flowability of the paper treatment agent that the ratio be 0.085 or less, more preferably 0.07 or less, and even more preferably 0.053 or less.

(C) Water

[0036] In the paper treatment agent of the present invention, the component (C) or water is an essential component for exhibiting advantageous effects of the present invention in combined use with the component (B) or sulfonate.

[0037] Examples of the component (C), namely water, include, but are not particularly limited to an ion-exchanged water, tap water, and sterilized water.

[0038] Examples of the contents of water (C) include, but are not particularly limited to, 0.1 to 90% by mass relative to the total amount of the paper treatment agent. It is preferred in view of the stability and viscosity of the paper treatment agent that the content be more than or equal to 1% by mass, more preferably more than or equal to 5% by mass, and even more preferably more than or equal to 8% by mass. It is preferred in respect of production efficiency and ease of viscosity adjustment depending on the types of coating devices that the content be less than or equal to 80% by mass, more preferably less than or equal to 50% by mass, and even more preferably less than or equal to 30% by mass.

(D) Further component

[0039] The paper treatment agent of the present invention may contain further component(s) (D) as an ingredient(s) other than those described above within the range that does not impair the advantageous effects of the present invention. Examples of such further component include, but are not particularly limited to, for example, an oil component, a surfactant (a nonionic surfactant, anionic surfactant except for the component (B), a cationic surfactant, amphoteric surfactant), a moisturizing ingredient other than the component (A)), a thickener, a fungicide, a preservative, an antifoam agent, a perfume, a colorant, a pH adjuster, an extract, an antioxidant agent, an anti-inflammatory drug, an inorganic mineral, an inorganic salt, and a water-soluble polymer. They may be used alone, or two or more of them may be used in combination.

(Oil component)

[0040] The oil component mainly improves the texture, such as the oily and moist feeling and the surface feel (smoothness) of treated paper. Examples of the oil component include hydrocarbons, lipids, esters, fatty acids, higher alcohols, silicone oils, waxes, and steroids. They may be used alone, or two or more of them may be used in combination.

[0041] Examples of the hydrocarbons include a liquid paraffin, paraffin, solid paraffin, light isoparaffin, light liquid isoparaffin, liquid isoparaffin, ceresin, microcrystalline wax, petroleum jelly, squalane, polyethylene wax, polypropylene wax, hydrogenated polyisobutene, ethylene-α-olefin-cooligomer, and ethylene propylene polymer.

[0042] Examples of the lipids include, for example, an avocado oil, almond oil, flaxseed oil, olive oil, cacao oil, perilla oil, camellia oil, castor oil, sesame oil, wheat germ oil, rice germ oil, rice bran oil, sasanqua oil, safflower oil, soybean oil, evening primrose oil, camellia oil, corn oil, rapeseed oil, prunus armeniaca kernel oil, palm kernel oil, coconut oil, palm oil, beef fat, pork fat, horse fat, sheep fat, shea fat, cacao fat, turtle oil, mink oil, egg yolk oil, purcellin oil, castor oil, sunflower oil, jojoba oil, grape seed oil, macadamia nut oil, cotton seed oil, meadowfoam oil, coconut oil, peanut oil, cod liver oil, rose hip oil, hardened oil of beef fat, extremely hardened oil of beef fat, hardened castor oil, and extremely hardened palm oil.

[0043] Examples of the esters include, for example, a stearic acid alkyl ester, palmitic acid alkyl ester, myristic acid alkyl ester, lauric acid alkyl ester, behenic acid alkyl ester, oleic acid alkyl ester, isostearic acid alkyl ester, 12-hydroxystearic acid alkyl ester, undecylenic acid alkyl ester, lanolin fatty acid alkyl ester, erucic acid alkyl ester, coconut oil fatty acid alkyl ester, stearoyloxystearic acid alkyl ester, isononanoic acid alkyl ester, dimethyloctanoic acid alkyl ester, octanoic acid alkyl ester, lactic acid alkyl ester, ethylhexanoic acid alkyl ester, neopentanoic acid alkyl ester, malic acid alkyl ester, phthalic acid alkyl ester, citric acid alkyl ester, malonic acid alkyl ester, adipic acid alkyl ester, ethylene glycol fatty acid ester, propanediol fatty acid ester, butanediol fatty acid ester, trimethylolpropane fatty acid ester, pentaerythritol fatty acid ester, polyglycerin fatty acid ester, trehalose fatty acid ester, and pentylene glycol fatty acid ester.

[0044] Examples of the fatty acids include, for example, stearic acid, palmitic acid, myristic acid, lauric acid, behenic acid, oleic acid, isostearic acid, 12-hydroxystearic acid, undecylenic acid, lanolin fatty acid, erucic acid, and stearoyloxystearic acid.

[0045] Examples of the higher alcohols include, for example, lauryl alcohol, cetyl alcohol, cetostearyl alcohol, stearyl alcohol, oleyl alcohol, behenyl alcohol, lanolin alcohol, hexyldecanol, myristyl alcohol, aralkyl alcohol, phytosterol, isostearyl alcohol, and octyldodecanol.

[0046] Examples of the silicone oils include, for example, an amino-modified silicone oil, epoxy-modified silicone oil, carboxy-modified silicone oil, polyether-modified oil, polyglycerin-modified silicone oil, dimethylpolysiloxane, dimethylsilicone, polyether-modified silicone, methylphenylsilicone, alkyl-modified silicone, higher fatty acid-modified silicone, methylhydrogen silicone, fluorine-modified silicone, epoxy-modified silicone, carboxy-modified silicone, carbinol-modified silicone, amino-modified silicone, methylpolysiloxane, methylphenylpolysiloxane, silicone resin, dimethicone, methylhydrogenpolysiloxane, methylcyclopolysiloxane, octamethyltrisiloxane, tetramethylhexasiloxane and highly polymerized methylpolysiloxane.

[0047] Examples of the waxes include, for example, a Japan wax, beeswax, sumac wax, lacquer wax, sugarcane wax, palm wax, montan wax, carnauba wax, candelilla wax, rice bran wax, lanolin, spermaceti, reduced lanolin, liquid lanolin, hard lanolin, ceresin and ozokerite. Examples of the steroids include, for example, a cholesterol, dihydrocholesterol and cholesterol fatty acid ester.

(Surfactant)

[0048] Of the surfactants, examples of the nonionic surfactant include, but are not particularly limited to a sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene hardened castor oil, polyoxyethylene castor oil, polyoxyethylene hardened castor oil fatty acid ester, castor oil fatty acid ester, hardened castor oil fatty acid ester, ethylene glycol fatty acid ester, sucrose fatty acid ester, glycerin fatty acid ester, diglycerine fatty acid ester, polyglyceryl fatty acid ester, organic acid monoglyceride, polyethyleneglycol monoethanol fatty acid amide, propylene glycol fatty acid ester, polyoxyethylene lanolin alcohol ether, polyoxyethylene alkyl ether, lauric acid alkanolamide, polyoxyethylene glycerin fatty acid ester, polyoxyethylene hardened castor oil pyroglutamic acid fatty diester, pyroglutamic acid fatty glyceryl, polyoxyethylene glyceryl pyroglutamic acid fatty diester, and polyether modified silicone.

[0049] Examples of the anionic surfactant except for the component (B) include, but are not particularly limited to, a sulfate, a phosphate and a carboxylate. Examples of the sulfate include, but are not particularly limited to, for example, an alkyl sulfate, alkylsulfate ester salt, alkyl ether sulfate, alkylamide sulfate, and polyoxyethylenealkyl ether sulfate. Examples of the phosphate include, but are not particularly limited to, for example, a phosphate ester salt, alkyl ether phosphate, alkylamide phosphate, perfluoroalkyl-phosphoric acid ester, polyoxyethylene alkyl ether phosphate, and alkyl phosphate. Examples of the carboxylate include, but are not particularly limited to a fatty acid salt, N-acyl amino acid salt (such as N-acyl-L-glutamate and N-acyl-L-arginine ethyl-DL-pyrrolidone carboxylate), alkyl ether carboxylate, and polyoxyethylene alkyl ether acetate.

[0050] Examples of the cationic surfactant include, but are not particularly limited to, a mono-alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, alkylpyridinium salt, N,N-dialkyloyloxyethyl-N-methyl, N-hydroxyethyl ammonium salt, alkylamine salt, and stearyldimethylbenzylammonium salt.

[0051] Examples of the amphoteric surfactant include, but are not particularly limited to, an alkylbetaine, fatty acid amide propyl betaine, lauryl hydroxysulfobetaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, lecitin, hydrogenated lecitin, alkyloxyhydroxypropyl arginine hydrochloride, lauryl hydroxysultaine, lauriminodipropionate, undecyl hydroxyethyl imidazolinium betaine sodium, disodium lauriminodiacetate, lauryl dimethyl amino acetic acid betaine, N-[3-alkyloxy-2-hydroxypropyl]-L-arginine hydrochloride, alkyl hydroxy sulfobetaine, alkyldimethy amine oxide, sodium alkylamino dipropionate, dihydroxyalkyl methylglycine, and sodium lauryl diaminoethylglycinate.

[0052] Examples of the moisturizing ingredient other than the component (A) include, but are not particularly limited to, amino acids and alkalis/acids having hygroscopic property or salts thereof. Examples of the amino acids include, for example, glycine, valine, leucine, isoleucine, serine, threonine, phenylalanine, arginine, lysine, aspartic acid, glutamic acid, cystine, cysteine, methionine, tryptophan. Examples of the alkalis/acids having hygroscopic property or salts thereof include trimethylglycine, betain, pyrophosphoric acid, sodium pyrophosphate, chondroitin sulfate, potassium pyrophosphate, hyaluronic acid, sodium hyaluronate, sodium metaphosphate, potassium polyphosphate, sodium pyrrolidone carboxylate, sodium lactate, sodium chloride, calcium chloride, sodium alginate, and sodium polyacrylate. They may be used alone, or two or more of them may be used in combination.

[0053] It is preferred that the content of the component (D) be less than or equal to 90% by mass, more preferably less than or equal to 70% by mass, even more preferably less than or equal to 50% by mass, and particularly preferably less than or equal to 30% by mass relative to the total amount of the paper treatment agent excluding water.

[0054] The paper treatment agent of the present invention may be produced by uniformly mixing the respective ingredients in accordance with the conventional method. For example, the respective ingredients may be stirred and mixed at a temperature by which the ingredients are dissolved to obtain the paper treatment agent.

[0055] The paper treatment agent of the present invention may be in a state in which the components (A), (B), and (C) are uniformly mixed, or in which the components (A), (B), (C), and (D) are uniformly mixed if the component (D) is further blended, and the state may be, for example, in a molten state, a solubilized state, an emulsified state, or a dispersed state.

[0056] The paper treatment agent of the present invention contains the components (A), (B), and (C), and thus has a low viscosity before being applied to paper, and after being applied to paper, its moisture is appropriately retained on the coated paper, thereby exerting the advantageous effects of the present invention. As explained above, the paper treatment agent of the present invention exhibits low viscosity, and therefore allows easy transportation and favorable handling, and the amount of treatment agent attached to the treatment paper can be easily controlled, thus resulting in good operability. Uniform application of paper treatment agent to paper, pertaining to the texture of the paper, will become favorable as well.

[0057] It is preferred that the paper treatment agent of the present invention have a viscosity, as measured at 60 rpm and 40°C using a B-type viscometer, of less than 2000 mPa·s, more preferably less than 500 mPa·s.

[0058] Furthermore, the paper treatment agent of the present invention maintains a uniform state over time and is highly stable. In other words, the paper treatment agent has good stability over time, and can maintain an appropriate viscosity over time.

[0059] As a preferred example of the paper treatment agent of the present invention, there may be listed: a paper treatment agent that contains 50 to 98% by mass of the component (A) and 0.7 to 7.9% by mass of an alkyl sulfonate having an alkyl group having 12 to 26 carbon atoms as the component (B) relative to the total amount of the paper treatment agent excluding water, the agent further containing 5 to 50% by mass of the component (C) relative to the total amount of the paper treatment agent; a paper treatment agent that contains 50 to 98% by mass of the component (A) and 0.7 to 7.9% by mass of an alkyl benzene sulfonate having an alkyl group having 12 to 26 carbon atoms as the component (B) relative to the total amount of the paper treatment agent excluding water, the agent further containing 5 to 50% by mass of the component (C) relative to the total amount of the paper treatment agent; and a paper treatment agent that contains 50 to 98% by mass of the component (A) and 0.7 to 7.9% by mass of a sulfosuccinate ester salt having an alkyl group having 12 to 26 carbon atoms as the component (B) relative to the total amount of the paper treatment agent excluding water, the agent further containing 5 to 50% by mass of the component (C) relative to the total amount of the paper treatment agent.

(Paper)

[0060] The paper of the present invention is directed to a paper treated with the paper treatment agent as explained above. The treatment of paper using the paper treatment agent of the present invention allows paper to have a unique, slimy, silk-like feel and coreless softness, brings about little change in moisture content in the paper between when the paper is in a high-humidity environment and when the paper is in a low-humidity environment, and can suppress moisture evaporation from paper even in a low-humidity environment.

[0061] Examples of the paper include a tissue paper, toilet paper, facial tissue, pocket tissue, paper handkerchief, and paper towel.

[0062] The basis weight of the paper is not particularly limited but preferably 1 to 50 g/m², more preferably 5 to 20 g/m². The ply number (the number of base paper layers) is not particularly limited but preferably 1 to 5, and more preferably 2 to 3.

[0063] Examples of the method for treating paper with a paper treatment agent include, but are not particularly limited to, a method of applying paper treatment agent onto paper. Examples of the method of applying the agent onto paper include, but are not particularly limited to, transcription and spraying. Examples of the system for applying the agent onto paper using these methods include a flexographic printing system, a gravure printing system, a spray system, and a rotor dampening system. In the flexographic printing system, a flexographic printing machine that is one of the letterpress printing machines is used to transfer a paper treatment agent onto paper using a roller equipped with a machine plate made of rubber or synthetic resin whose surface has been engraved. In the gravure printing system, a gravure printing machine that is one of the intaglio printing machines is used to transfer a paper treatment agent onto paper using a roller equipped with a cylinder made of metal whose surface has been subjected to plate-making. In the spray system, a paper treatment agent is sprayed onto paper in the form of a mist from a nozzle by compressed air. In the rotor dampening system, a paper treatment agent is sprayed onto paper in the form of a mist using a disk rotating at a high speed.

[0064] The amount of paper treatment agent to be coated onto paper is not particularly limited but the amount in terms of weight of the paper treatment agent excluding water is preferably 1 to 7 g/m², more preferably 1.5 to 6 g/m².

(Method for Improving Paper Texture)

[0065] The method for improving paper texture according to the present invention is directed to a method of treating paper with the paper treatment agent as explained above. Specific embodiments for treating paper with the paper treatment agent are as explained above. The treatment of paper with the paper treatment agent of the present invention allows the paper to have a unique, slimy, silk-like feel and a coreless softness which has a less resilient feel with little fluffiness, reduces burden to skin and reminds a user of gentleness to skin, thus improving the texture.

Examples

[0066] The present invention is described in greater detail hereunder with reference to working examples. However, the invention shall not be limited to the following working examples.

(1) Preparation of Paper Treatment Agent

[0067] The following processes were used to prepare the paper treatment agent.

[0068] The respective ingredients of the additive amounts as shown in Tables 1 to 5 were put into a beaker, and the ingredients were mixed and stirred at a temperature by which the ingredients were dissolved to prepare the paper treatment agent. The amounts of each ingredient shown in Tables 1 to 5 indicate the effective amounts excluding water if the actual amount includes water. The amount of water in the actual amount is included in the amount of added water as indicated in the Tables.

(2) Preparation of Coated Paper

[0069] The paper treatment agent obtained by the above method was uniformly applied to both sides of dry tissue (ply number 2, basis weight 12 to 14 g/m²) so that the mass of the paper treatment agent excluding water was 25% by mass ±3% relative to the mass of the base paper, and then air-dried for 3 hours.

(3) Evaluation

[0070] The following evaluations were performed on the paper treatment agents and the coated papers of the working and comparative examples which were prepared in the manner as shown above.

[Unique, slimy, silk-like feel (Sensory evaluation)]

[0071] The coated papers prepared by the process shown in (2) were evaluated for sensory evaluation by 10 experienced panel members on a scale of 1 to 3 based on the following evaluation scores, and their average scores were used to evaluate the unique, slimy, and silk-like feel using the following criteria.

Evaluation Score:

[0072] 

Score 3: Unique, slimy, silk-like feel was felt

Score 2: Unique, slimy, silk-like feel was slightly felt

Score 1: Unique, slimy, silk-like feel was not felt

Evaluation Criteria:

[0073] 

⊚⁺: Average score of 10 panel members was 2.5 or more

⊚: Average score of 10 panel members was from 2.0 to less than 2.5

○: Average score of 10 panel members was from 1.5 to less than 2.0

×: Average score of 10 panel members was less than 1.5

[Coreless Softness (sensory evaluation)]

[0074] The coated papers prepared by the process shown in (2) were evaluated for sensory evaluation by 10 experienced panel members on a scale of 1 to 3 based on the following evaluation scores, and their average scores were used to evaluate the coreless softness using the following criteria.

Evaluation score:

[0075] 

Score 3: Coreless softness was felt

Score 2: Coreless softness was slightly felt

Score 1: Coreless softness was not felt

Evaluation Criteria:

[0076] 

⊚⁺: Average score of 10 panel members was 2.5 or more

⊚: Average score of 10 panel members was from 2.0 to less than 2.5

○: Average score of 10 panel members was from 1.5 to less than 2.0

×: Average score of 10 panel members was less than 1.5

[Coreless Softness (T₀/T_m value)]

[0077] KES-G5 Handy Compression Tester (manufactured by KATO TECH CO.,LTD.) was used as a test device to subject two coated papers (in one set) to measurement of the thickness (mm) T₀ at a load of 0.5 gf/cm² and the thickness (mm) T_m at a load of 50 gf/cm².

[0078] The lower the value of T₀/T_m or the ratio of T₀ to T_m, the smaller the difference in thickness between when no load is applied and when a load is applied, which indicates that the coated paper has a less resilient feel with little fluffiness. This value of T₀/T_m, indicating less resilient feel, correlates with the coreless softness in the sensory evaluation explained above; i.e., the lower the value T₀/T_m becomes, the more coreless softness it is felt. Accordingly, this coreless softness was determined based on the value T₀/T_m using the following criteria.

Evaluation Criteria:

[0079] 

⊚⁺: The value T₀/T_m was 1.8 or less

⊚: The value T₀/T_m was from 1.8 to less than 2.0

○: The value T₀/T_m was from 2.0 to less than 2.2

×: The value T₀/T_m was 2.2 or more

[Humidity Environment Dependency]

[0080] For the coated papers prepared in accordance with the above-explained procedure in (2), the masses of the papers after being left to stand for 24 hours in environments of 40% RH and 70% RH at 25°C were respectively measured, and the bone-dry masses of the papers after being left to stand for 1.5 hours at 80°C were also measured, and based on these values, the proportions of water, relative to the bone-dry masses of the papers, at 40% RH and 70% RH at 25°C were respectively calculated.

[0081] Based on these values, differences in contents of water, relative to the respective bone-dry masses of the paper, between those at 40% RH at 25°C and those at 70% RH at 25°C were calculated to evaluate their humidity environment dependency using the following criteria.

Evaluation Criteria

[0082] 

⊚⁺: The difference between the content of water in paper at 40% RH and that of 70% RH relative to the bone-dry masse of the paper was less than 7.0%

⊚: The difference between the content of water in paper at 40% RH and that of 70% RH relative to the bone-dry masse of the paper was from 7.0% to less than 8.0%

○: The difference between the content of water in paper at 40% RH and that of 70% RH relative to the bone-dry mass of the paper was from 8.0% to less than 9.0%

×: The difference between the content of water in paper at 40% RH and that of 70% RH relative to the bone-dry mass of the paper was 9.0% or more

[Water Content under Low-humidity environment]

[0083] For the coated papers prepared in accordance with the above-explained procedure in (2), each mass of the papers after being left to stand for 24 hours in an environment of 25% RH at 25°C, and the bone-dry mass of the paper after being left to stand for 1.5 hours at 80°C were measured, and based on the difference between these values, each content of water at 25% RH at 25°C relative to the bone-dry mass of the paper was calculated, and this value was determined as the water content at 25% RH to evaluate the water content at low-humidity environment using the following criteria.

Evaluation Criteria:

[0084] 

⊚⁺: Water content at 25% RH was 5.1% or more

⊚: Water content at 25% RH was from 4.7% to less than 5.1

○: Water content at 25% RH was from 4.5% to less than 4.7

×: Water content at 25% RH was less than 4.5%

[Viscosity of Paper Treatment Agent]

[0085] The B-type viscometer was used to measure the viscosity at 60 rpm and 40°C of the paper treatment agent, prepared by the process of (1) as shown above, and the viscosity was evaluated using the following criteria.

Evaluation Criteria:

[0086] 

⊚: The paper treatment agent had a viscosity of less than 500 mPa·s

○: The paper treatment agent had a viscosity from 500 mPa·s to less than 2000 mPa·s

×: The paper treatment agent had viscosity of 2000 mPa·s or more, or was unmeasurable (could not maintain a uniform state)

[Stability of Paper Treatment Agent]

[0087] The states of paper treatment agents prepared by the process of (1) as shown above were checked at the time immediately after the paper treatment agent was prepared and at the time after the agent was left to stand at room temperature for one month, and their states were evaluated, considering if the state is suitable for actual use, using the following criteria.

Evaluation Criteria:

[0088] 

⊚: The agent maintained a uniform state for one month after the agent was prepared

○: The agent maintained a uniform state for one month after the agent was prepared but the state was slightly changed

×: The agent was non-uniform immediately after the agent was prepared, or the agent could not maintain a uniform state for one month

[0089] The formulations of each of the working and comparative examples and the evaluation results for each item are shown in Tables 1 to 5. In Tables 1 to 5, the formulation amount of each component is shown in parts by mass.

[0090] According to the evaluations in each item shown in Tables 1 to 5, in the evaluations of the unique, slimy, silk-like feel (sensory evaluation), coreless softness (sensory evaluation), coreless softness (T₀/T_m value), humidity environment dependency, and water contents in low-humidity environment, ○, ⊚ and ⊚⁺ indicate results that are good in solving the problem of the invention and better in this sequence in ascending order. Further, if one or more of these evaluations were marked ×, it was determined that the invention did not solve the problem.

[0091] In the tables, the "C" for the sulfonate (B) denotes the number of alkyl groups.

[Table 1]

		Working example
		1	2	3	4	5	6	7	8	9	10
(A) Polyhydric alcohol		1	99.95	92.1	70	80	90	99.9	99.3	98	95
	Sorbitol
(B) Sulfonate	Alkyl sulfonate (C8)
	Alkyl sulfonate (C10)
	Alkyl sulfonate (C14)
	Alkyl sulfonate (C18)	0.7	0.05	7.9	2	2	2	0.1	0.7	2	5
	Alkyl sulfonate (C24)
	Alkyl sulfonate (C26)
	Alkyl benzene sulfonate (C8)
	Alkyl benzene sulfonate (C10)
	Alkyl benzene sulfonate (C14)
	Alkyl benzene sulfonate (C18)
	Alkyl benzene sulfonate (C24)
	Alkyl benzene sulfonate (C26)
	Sulfosuccinate ester salt (C8)
	Sulfosuccinate ester salt (C10)
	Sulfosuccinate ester salt (C 14)
	Sulfosuccinate ester salt (C18)
	Sulfosuccinate ester salt (C24)
	Sulfosuccinate ester salt (C26)
	Sulfo fatty acid ester salt (C18)
	α-olefin sulfonate (C18)
(D) Further component	Liquid paraffin	90			8	5	2
	Nonionic surfactant	8.3			20	13	6
	Alkyl sulfate (C18)
	Alkyl carboxylate (C18)
Total Amount of (A), (B) and (D)		100	100	100	100	100	100	100	100	100	100
Content (% by mass) of sulfonate (B) relative to the total amount of (A), (B) and (D)		0.7	0.05	7.9	2	2	2	0.1	0.7	2	5
Content (% by mass) of polyhydric alcohol (A) relative to the total amount of (A), (B) and (D)		1	99.95	92.1	70	80	90	99.9	99.3	98	95
Mass ratio of sulfonate (B) to polyhydric alcohol (A)		0.70	0.001	0.086	0.029	0.025	0.022	0.001	0.007	0.020	0.053
Content of added water (C)		10	10	10	10	10	10	10	10	10	10
Content (% by mass) of water (C) relative to the total amount of paper treatment agent		9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1
Evaluation	Unique, slimy, silk-like feel (Sensory evaluation)	⊚	○	⊚+	⊚+	⊚+	⊚+	⊚	⊚	⊚+	⊚+
	Coreless softness (Sensory evaluation)	○	○	○	○	⊚	⊚+	○	⊚	⊚+	⊚
	Coreless softness (T0/Tm value)	○	○	○	○	⊚	⊚+	○	⊚	⊚+	⊚
	Humidity environment dependency (Water content difference of coated paper between 40% RH and 70% RH)	⊚	○	⊚	⊚	⊚	⊚	○	○	⊚	⊚
	Water Content under Low-humidity environment (Water content in coated paper at 25% RH)	○	⊚	⊚+	⊚	⊚+	⊚+	⊚	⊚	⊚+	⊚+
	Viscosity of paper treatment agent	○	⊚	○	○	⊚	⊚	⊚	⊚	⊚	⊚
	Stability of paper treatment agent	○	⊚	○	○	⊚	⊚	⊚	⊚	⊚	⊚

[Table 2]

		Working example
		11	12	13	14	15	16	17	18	19	20
(A) Polyhydric alcohol	Glycerin	98	98	98	98	98	98	98	98	98	98
	Sorbitol
(B) Sulfonate	Alkyl sulfonate (C8)	2
	Alkyl sulfonate (C10)		2
	Alkyl sulfonate (C14)			2
	Alkyl sulfonate (C18)
	Alkyl sulfonate (C24)				2
	Alkyl sulfonate (C26)					2
	Alkyl benzene sulfonate (C8)						2
	Alkyl benzene sulfonate (C10)							2
	Alkyl benzene sulfonate (C14)								2
	Alkyl benzene sulfonate (C18}									2
	Alkyl benzene sulfonate (C24)										2
	Alkyl benzene sulfonate (C26)
	Sulfosuccinate ester salt (C8)
	Sulfosuccinate ester salt (C10)
	Sulfosuccinate ester salt (C14)
	Sulfosuccinate ester salt (C18)
	Sulfosuccinate ester salt (C24)
	Sulfosuccinate ester salt (C26)
	Sulfo fatty acid ester salt (C18)
	α-olefin sulfonate (C18)
(D) Further component	Liquid paraffin
	Nonionic surfactant
	Alkyl sulfate (C18)
	Alkyl carboxylate (C18)
Total Amount of (A), (B) and (D)		100	100	100	100	100	100	100	100	100	100
Content (% by mass) of sulfonate (B) relative to the total amount of (A), (B) and (D)		2	2	2	2	2	2	2	2	2	2
Content (% by mass) of polyhydric alcohol (A) relative to the total amount of (A), (B) and (D)		98	98	98	98	98	98	98	98	98	98
Mass ratio of sulfonate (B) to polyhydric alcohol (A)		0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020
Content of added water (C)		10	10	10	10	10	10	10	10	10	10
Content (% by mass) of water (C) relative to the total amount of paper treatment agent		9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1
Evaluation	Unique, slimy, silk-like feel (Sensory evaluation)	○	○	⊚	⊚+	⊚+	○	○	⊚	⊚+	⊚+
	Coreless softness (Sensory evaluation)	○	⊚	⊚+	⊚	○	○	⊚	⊚+	⊚+	⊚
	Coreless softness (T0/Tm value)	○	⊚	⊚+	⊚	○	○	⊚	⊚+	⊚+	⊚
	Humidity environment dependency (Water content difference of coated paper between 40% RH and 70% RH)	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚
	Water Content under Low-humidity environment (Water content in coated paper at 25% RH)	⊚	⊚+	⊚+	⊚+	⊚+	⊚	⊚+	⊚+	⊚+	⊚+
	Viscosity of paper treatment agent	⊚	⊚	⊚	○	○	⊚	⊚	⊚	⊚	○
	Stability of paper treatment agent	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚

[Table 3]

		Working example
		21	22	23	24	25	26	27	28	29
(A) Polyhydric alcohol alcohol	Glycerin	98	98	98	98	98	98	98	98	98
	Sorbitol
(B) Sulfonate	Alkyl sulfonate (C8)
	Alkyl sulfonate (C10)
	Alkyl sulfonate (C14)
	Alkyl sulfonate (C18)
	Alkyl sulfonate (C24)
	Alkyl sulfonate (C26)
	Alkyl benzene sulfonate (C8)
	Alkyl benzene sulfonate (C10)
	Alkyl benzene sulfonate (C14)
	Alkyl benzene sulfonate (C18)
	Alkyl benzene sulfonate (C24)
	Alkyl benzene sulfonate (C26)	2
	Sulfosuccinate ester salt (C8)		2
	Sulfosuccinate ester salt (C10)			2
	Sulfosuccinate ester salt (C14)				2
	Sulfosuccinate ester salt (C18)					2
	Sulfosuccinate ester salt (C24)						2
	Sulfosuccinate ester salt (C26)							2
	Sulfo fatty acid ester salt (C18)								2
	α-olefin sulfonate (C18)									2
(D) Further component	Liquid paraffin
	Nonionic surfactant
	Alkyl sulfate (C18)
	Alkyl carboxylate (C18)
Total Amount of (A), (B) and (D)		100	100	100	100	100	100	100	100	100
Content (% by mass) of sulfonate (B) relative to the total amount of (A), (B) and (D)		2	2	2	2	2	2	2	2	2
Content (% by mass) of polyhydric alcohol (A) relative to the total amount of (A), (B) and (D)		98	98	98	98	98	98	98	98	98
Mass ratio of sulfonate (B) to polyhydric alcohol (A)		0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020
Content of added water (C)		10	10	10	10	10	10	10	10	11
Content (% by mass) of water (C) relative to the total amount of paper treatment agent		9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.1	9.9
Evaluation	Unique, slimy, silk-like feel (Sensory evaluation)	⊚+	○	○	⊚	⊚+	⊚+	⊚+	○	○
	Coreless softness (Sensory evaluation)	○	○	⊚	⊚+	⊚+	⊚	○	○	○
	Coreless softness (T0/Tm value)	○	○	⊚	⊚+	⊚+	⊚	○	○	○
	Humidity environment dependency (Water content difference of coated paper between 40% RH and 70% RH)	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚	○
	Water Content under Low-humidity environment (Water content in coated paper at 25% RH)	⊚+	⊚	⊚+	⊚+	⊚+	⊚+	⊚+	⊚	○
	Viscosity of paper treatment agent	○	⊚	⊚	⊚	⊚	○	○	⊚	⊚
	Stability of paper treatment agent	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚	⊚

[Table 4]

		Working example
		30	31	32	33	34	35
(A) Polyhydric alcohol	Glycerin		98	98	98	98	98
	Sorbitol	98
(B) Sulfonate	Alkyl sulfonate (C8)
	Alkyl sulfonate (C10)
	Alkyl sulfonate (C14)
	Alkyl sulfonate (C18)	2	2	2	2	2	2
	Alkyl sulfonate (C24)
	Alkyl sulfonate (C26)
	Alkyl benzene sulfonate (C8)
	Alkyl benzene sulfonate (C10)
	Alkyl benzene sulfonate (C14)
	Alkyl benzene sulfonate (C18)
	Alkyl benzene sulfonate (C24)
	Alkyl benzene sulfonate (C26)
	Sulfosuccinate ester salt (C8)
	Sulfosuccinate ester salt (C10)
	Sulfosuccinate ester salt (C14)
	Sulfosuccinate ester salt (C18)
	Sulfosuccinate ester salt (C24)
	Sulfosuccinate ester salt (C26)
	Sulfo fatty acid ester salt (C18)
	α-olefin sulfonate (C18)
(D) Further component	Liquid paraffin
	Nonionic surfactant
	Alkyl sulfate (C18)
	Alkyl carboxylate (C18)
Total Amount of (A), (B) and (D)		100	100	100	100	100	100
Content (% by mass) of sulfonate (B) relative to the total amount of (A), (B) and (D)		2	2	2	2	2	2
Content (% by mass) of polyhydric alcohol (A) relative to the total amount of (A), (B) and (D)		98	98	98	98	98	98
Mass ratio of sulfonate (B) to polyhydric alcohol (A)		0.020	0.020	0.020	0.020	0.020	0.020
Content of added water (C)		10	1.0	5.3	8.7	43	100
Content (% by mass) of water (C) relative to the total amount of paper treatment agent		9.1	1	3	8	30	50
Evaluation	Unique, slimy, silk-like feel (Sensory evaluation)	○	⊚+	⊚+	⊚+	⊚+	⊚+
	Coreless softness (Sensory evaluation)	○	⊚+	⊚+	⊚+	⊚+	⊚+
	Coreless softness (T0/Tm value)	○	⊚+	⊚+	⊚+	⊚+	⊚+
	Humidity environment dependency (Water content difference of coated paper between 40% RH and 70% RH)	⊚	⊚	⊚	⊚	⊚	⊚
	Water Content under Low-humidity environment (Water content in coated paper at 25% RH)	○	⊚+	⊚+	⊚+	⊚+	⊚+
	Viscosity of paper treatment agent	○	○	○	⊚	⊚	⊚
	Stability of paper treatment agent	⊚	○	⊚	⊚	⊚	⊚

[Table 5]

		Comparative example
		1	2	3	4	5	6	7	8	9
(A) Polyhydric alcohol	Glycerin	100	92			98	98	98	92.1	94
	Sorbitol
(B) Pulfonate	Alkyl sulfonate (C8)
	Alkyl sulfonate (C10)
	Alkyl sulfonate (C14)
	Alkyl sulfonate (C18)		8					2	7.9	3
	Alkyl sulfonate (C24)
	Alkyl sulfonate (C26)
	Alkyl benzene sulfonate (C8)
	Alkyl benzene sulfonate (C10)
	Alkyl benzene sulfonate (C14)				40
	Alkyl benzene sulfonate (C18)
	Alkyl benzene sulfonate (C24)
	Alkyl benzene sulfonate (C26)
	Sulfosuccinate ester salt (C8)			40
	Sulfosuccinate ester salt (C10)
	Sulfosuccinate ester salt (C14)
	Sulfosuccinate ester salt (C18)
	Sulfosuccinate ester salt (C24)
	Sulfosuccinate ester salt (C26)
	Sulfo fatty acid ester salt (C18)
	α-olefin sulfonate (C18)
(D) Further component	Liquid paraffin
	Nonionic surfactant									3
	Alkyl sulfate (C18)						2
	Alkyl carboxylate (C18)					2
Total Amount of (A), (B) and (D)		100	100	40	40	100	100	100	100	100
Content (% by mass) of sulfonate (B) relative to the total amount of (A), (B) and (D)		0	8	100	100	0	0	2	7.9	3
Content (% by mass) of polyhydric alcohol (A) relative to the total amount of (A), (B) and (D)		100	92	0	0	98	98	98	92.1	94
Mass ratio of sulfonate (B) to polyhydric alcohol (A)		0	0.087	-	-	0	0	0.020	0.086	0.032
Content of added water (C)		10	10	60	60	10	10	0	0	0
Content (% by mass) of water (C) relative to the total amount of paper treatment agent		9.1	9.1	60	60	9.1	9.1	0	0	0
Evaluation	Unique, slimy, silk-like feel (Sensory evaluation)	×	⊚+	○	○	×	×	×	×	×
	Coreless softness (Sensory evaluation)	×	×	×	×	×	×	×	×	×
	Coreless softness (T0/Tm value)	×	×	×	×	×	×	×	×	×
	Humidity environment dependency (Water content difference of coated paper between 40% RH and 70% RH)	×	⊚	⊚	⊚	×	×	○	○	○
	Water Content under Low-humidity environment (Water content in coated paper at 25% RH)	×	⊚+	×	×	×	×	×	×	×
	Viscosity of paper treatment agent	⊚	×	×	×	⊚	⊚	×	×	×
	Stability of paper treatment agent	⊚+	○	○	○	⊚	⊚	×	×	×

[0092]  The working examples 1 to 35 in Tables 1 to 35 used paper treatment agents each containing (A) polyhydric alcohol, (B) sulfonate, and (C) water, wherein the content of (B) sulfonate is from 0.05% by mass to less than 8.0% by mass with respect to the total amount excluding water. These paper treatment agents each had a unique, slimy, silk-like feel and coreless softness, was less dependent on humidity environment, and suppressed moisture evaporation from paper in a low-humidity environment. Further, the paper treatment agent had low viscosity and favorable stability over time. The coated papers having low T₀/T_m values and less resilient feel with little fluffiness showed coreless softness which was good in sensory evaluation, and it was therefore demonstrated that the value of T₀/T_m correlates with the coreless softness in the sensory evaluation.

[0093] Comparative example 1 contained the components (A) and (C) but the component (B) was not contained therein, comparative example 2 contained the component (B) but the amount was excessive, comparative examples 3 and 4 each contained the components (B) and (C) but the component (A) was not contained therein, comparative examples 5 and 6 each contained an alternative anionic surfactant instead of the component (B), comparative examples 7 to 9 each contained the components (A) and (B) but the component (C) was not contained therein. These comparative examples did not result in advantageous effects similar to those of the working examples.

Claims

1. A paper treatment agent comprising:

(A) polyhydric alcohol;

(B) sulfonate; and

(C) water,
wherein the sulfonate (B) is contained in an amount from 0.05% by mass to less than 8.0% by mass relative to the total amount excluding water.

2. The paper treatment agent according to claim 1, wherein the sulfonate (B) contains an alkyl group having 4 to 30 carbon atoms.

3. A paper treated with the paper treatment agent according to claim 1 or 2.

4. A method for improving paper texture, wherein the method comprises treating a paper with the paper treatment agent according to claim 1 or 2.