Method for producing soft paper and paper softener

Abstract

To provide a method for producing paper having sufficient softness by papermaking from pulp slurry with a softening agent blended in advance.SOLUTION: A method for producing soft paper according to the present invention comprises papermaking a pulp slurry containing a softening agent containing lecithin and pulp.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing soft paper and a paper softener. [Background technology]

[0002] Generally, household paper such as tissue paper, toilet paper, and kitchen paper is required to have an appropriate level of flexibility depending on its use. Similarly, printing paper for magazines, books, and the like is also required to have the flexibility required for its use, that is, a level of pliability that allows the magazine, book, etc. to remain fully open without closing on its own when opened.

[0003] From the viewpoint of the manufacturing process, methods for producing paper with such flexibility can be broadly divided into methods in which a softener is applied to paper produced by making a pulp slurry that does not contain a softener by coating, impregnation, spraying, etc. (hereinafter also referred to as the "external addition method"), and methods in which a pulp slurry to which a softener has already been added is made (hereinafter also referred to as the "internal addition method").

[0004] Paper made by the external addition method has the characteristics of improving the texture and imparting moisture retention (moist feeling), but has the problem that the physical flexibility of the paper is not improved much.In contrast, paper made by the internal addition method has the characteristic of expressing physical flexibility because the softener inhibits the hydrogen bonds between cellulose molecules.

[0005] Known conventional softeners used in this type of internal addition method include those containing an amide compound and a quaternary ammonium compound (JP Patent Publication No. 2004-308095 (Patent Document 1)), those consisting of higher fatty acid esters of alkylene oxide adducts of higher alcohols (JP Patent Publication No. 2002-275792 (Patent Document 2)), and those containing a nonionic surfactant and a quaternary ammonium compound (JP Patent Publication No. 2004-044058 (Patent Document 3)). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-308095 A [Patent Document 2] JP 2002-275792 A [Patent Document 3] JP 2004-044058 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, paper produced by the conventional internal addition method using softeners does not necessarily have sufficient softness.

[0008] The present invention has been made in consideration of the problems associated with the above-mentioned conventional techniques, and aims to provide a paper softener capable of producing paper with good flexibility, and a method for producing paper with good flexibility by papermaking a pulp slurry that has previously been mixed with a softener. [Means for solving the problem]

[0009] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that paper with good flexibility can be obtained by making paper from a pulp slurry that has been pre-blended with a softener containing lecithin, and thus completed the present invention.

[0010] That is, the method for producing soft paper of the present invention is a method characterized by making paper from a pulp slurry containing a softener including lecithin and pulp.

[0011] In the soft paper manufacturing method of the present invention, the softener is represented by the following formulas (1-1) to (1-2):

[0012] [ka]

[0013] [In the above formula (1-1), R 11 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 12 is an aliphatic hydrocarbon group having 8 to 26 carbon atoms or -(AO) m14 -H stands for R 13 represents an alkylene group having 2 to 4 carbon atoms, n11 is an integer of 0 to 3, and in (1-2), R 14 and R 15 are each independently -CH3, -(AO) m15 -H, -(AO) m16 -C(=O)-R 16 or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R 16 represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, and in the formulas (1-1) and (1-2), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m11 to m16 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different. and tertiary amines represented by the following formulae (2-1) to (2-3):

[0014] [ka]

[0015] [In the above formula (2-1), R 21 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 22 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms or an alkyl group having 1 to 3 carbon atoms; R 23 represents an alkyl group having 1 to 3 carbon atoms, R 24 represents an alkyl group having 1 to 3 carbon atoms or a benzyl group, and in the formula (2-2), R 25 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 26 is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, -(AO) m23 -H or an alkyl group having 1 to 3 carbon atoms; R 27 is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) m24m21, m23 and m24 each independently represent a number from 1 to 4; when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different; 28 is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) m25 -H stands for R 29 and R 30 are each independently -CH3, -(AO) m26 -H, -(AO) m27 -C(=O)-R 31 or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R 31 represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, m22 and m25 to m27 each independently represent a number from 1 to 20, when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different, in the formulas (2-2) and (2-3), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, and in the formulas (2-1) to (2-3), X represents a counter ion, p represents the valence of the counter ion X, and is an integer from 1 to 3. and more preferably further contains at least one polyamine selected from the group consisting of polydiallyldimethylammonium salts, polyvinylamines, polyethyleneimines, and epichlorohydrin polycondensates of dimethylamine, polyallylamine, polyallylamine sulfone copolymers, polyamine polyamides, and polyamine-epichlorohydrin copolymers.

[0016] The softener of the present invention is a compound represented by the following formulas (1-1) to (1-2):

[0017] [ka]

[0018] [In the above formula (1-1), R 11 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 12is an aliphatic hydrocarbon group having 8 to 26 carbon atoms or -(AO) m14 -H stands for R 13 represents an alkylene group having 2 to 4 carbon atoms, n11 is an integer of 0 to 3, and in (1-2), R 14 and R 15 are each independently -CH3, -(AO) m15 -H, -(AO) m16 -C(=O)-R 16 or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R 16 represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, and in the formulas (1-1) and (1-2), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m11 to m16 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different. and tertiary amines represented by the following formulae (2-1) to (2-3):

[0019] [ka]

[0020] [In the above formula (2-1), R 21 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 22 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms or an alkyl group having 1 to 3 carbon atoms; R 23 represents an alkyl group having 1 to 3 carbon atoms, R 24 represents an alkyl group having 1 to 3 carbon atoms or a benzyl group, and in the formula (2-2), R 25 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 26 is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, -(AO) m23 -H or an alkyl group having 1 to 3 carbon atoms; R 27 is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) m24 m21, m23 and m24 each independently represent a number from 1 to 4; when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different; 28is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) m25 -H stands for R 29 and R 30 are each independently -CH3, -(AO) m26 -H, -(AO) m27 -C(=O)-R 31 or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R 31 represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, m22 and m25 to m27 each independently represent a number from 1 to 20, when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different, in the formulas (2-2) and (2-3), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, and in the formulas (2-1) to (2-3), X represents a counter ion, p represents the valence of the counter ion X, and is an integer from 1 to 3. and at least one amine-based additive component selected from the group consisting of quaternary ammonium compounds represented by the following formula:

[0021] It is preferable that the softener of the present invention further contains at least one polyamine selected from the group consisting of polydiallyldimethylammonium salts, polyvinylamines, polyethyleneimines, epichlorohydrin polycondensates of dimethylamine, polyallylamine, polyallylamine sulfone copolymers, polyamine polyamides, and polyamine-epichlorohydrin copolymers. Effect of the Invention

[0022] According to the present invention, it is possible to produce paper having good flexibility by making paper from a pulp slurry that has previously been mixed with a softening agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will be described in detail below based on preferred embodiments thereof.

[0024] [Method of manufacturing soft paper] First, the method for producing soft paper of the present invention will be described. The method for producing soft paper of the present invention is a method for making paper from a pulp slurry containing a softener including lecithin and pulp. This makes it possible to obtain paper with good flexibility.

[0025] (pulp) In the present invention, the raw material pulp is not particularly limited, and raw material pulp used in conventional soft paper production can be used, for example, wood pulp obtained from broadleaf trees or coniferous trees, vegetable fibers such as bagasse, kenaf, bamboo pulp, straw pulp, recycled pulp from waste paper, etc. These pulps may be used alone or in combination of two or more kinds.

[0026] In the pulp slurry used in the present invention, the concentration of such pulp (stock solids) is not particularly limited as long as it is a concentration that allows papermaking, and is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass.

[0027] (lecithin) Lecithin may be extracted from living organisms such as plants, animals, and microorganisms, and purified as necessary, or may be synthesized.Among these lecithins, animal-derived lecithin and plant-derived lecithin are preferred, and examples of animal-derived lecithin include lecithin derived from egg yolk and milk, and examples of plant-derived lecithin include soybean, rapeseed, wheat, rice, corn, cottonseed, safflower, linseed, sesame, sunflower seed, etc.In addition, in the present invention, hydrogenated products (hydrogenated lecithin), enzymatic decomposition products (enzymatic decomposition lecithin), fractionated products (fractionated lecithin), etc. of these lecithins can also be used.

[0028] In the pulp slurry used in the present invention, the amount of lecithin is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of pulp (paper stock solids). When the amount of lecithin is within the above range, the lecithin adheres uniformly to the paper, imparting good flexibility to the paper and also imparting good texture.

[0029] (amine-based additives) The softener used in the present invention preferably further contains at least one amine-based additive selected from the group consisting of tertiary amines and quaternary ammonium compounds described below, which improves the flexibility and feel imparted to paper.

[0030] The tertiary amine used in the present invention is represented by the following formulas (1-1) to (1-2):

[0031] [ka]

[0032] It is expressed as follows.

[0033] In the formula (1-1), R 11 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 12 is an aliphatic hydrocarbon group having 8 to 26 carbon atoms or -(AO) m14 -H stands for R 13 represents an alkylene group having 2 to 4 carbon atoms, n11 is an integer of 0 to 3, AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m11, m12, and m14 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different. 11 and R 12 The aliphatic hydrocarbon group of R may be linear or branched, and may be saturated or unsaturated. 13 The alkylene group of R may be linear or branched. 11 The number of carbon atoms in the aliphatic hydrocarbon group is preferably 10 to 22. 12 From the viewpoint of the balance between the water solubility of the tertiary amine and the softening property, the number of carbon atoms in the aliphatic hydrocarbon group is preferably 10 to 22. From the viewpoint of improving the softness and feel imparted to paper, n11 is preferably 0 or 1.

[0034] Such a tertiary amine represented by the formula (1-1) can be synthesized by a known method. For example, a tertiary amine in which m11, m12, and m14=1 in the formula (1-1) can be synthesized by subjecting 1 mole of a primary or secondary aliphatic amine having a predetermined aliphatic hydrocarbon group to an addition reaction of a predetermined number of moles of a predetermined alkylene oxide under catalyst-free conditions. In addition, a tertiary amine in which m11, m12, and m14>1 in the formula (1-1) can be synthesized by subjecting 1 mole of a tertiary amine in which m11, m12, and m14=1 in the formula (1-1) to an addition reaction of a predetermined number of moles of a predetermined alkylene oxide in the presence of an alkali catalyst. The reaction temperature of the addition reaction is not particularly limited, but is preferably 70 to 200°C, more preferably 100 to 160°C. In addition, the reaction time of the addition reaction is not particularly limited, but is preferably 0.1 to 40 hours, more preferably 0.5 to 20 hours. The alkali catalyst includes sodium hydroxide, potassium hydroxide, and the like.

[0035] In addition, in the formula (1-2), R 14 and R 15 are each independently -CH3, -(AO) m15 -H, -(AO) m16 -C(=O)-R 16 or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R 16 represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m13, m15, and m16 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different. 14 and R 15 The aliphatic hydrocarbon group of R may be linear or branched, and may be saturated or unsaturated. 16 The aliphatic hydrocarbon group of R may be linear or branched, and may be saturated or unsaturated. 14 and R 15 The number of carbon atoms in the aliphatic hydrocarbon group is preferably 10 to 22. 16From the viewpoint of improving the flexibility and feel imparted to paper, the number of carbon atoms in the aliphatic hydrocarbon group is preferably 11 to 21. From the viewpoint of improving the flexibility and feel imparted to paper, it is preferable that m13, m15, and m16=1.

[0036] Such a tertiary amine represented by the formula (1-2) can be synthesized by a known method. For example, it can be synthesized by esterifying a predetermined number of moles of a predetermined aliphatic carboxylic acid with respect to 1 mole of a trialkanolamine or a tertiary amine represented by the formula (1-1) under normal pressure or reduced pressure in the presence of an esterification catalyst. The reaction temperature of the esterification reaction is not particularly limited, but is preferably 70 to 250°C, more preferably 100 to 230°C. In addition, the reaction time of the esterification reaction is not particularly limited, but is preferably 0.5 to 40 hours, more preferably 1 to 20 hours. Examples of the esterification catalyst include conventionally known catalysts such as organotin-based polymerization catalysts such as antimony trioxide and dibutyltin oxide; germanium-based catalysts; inorganic titanium-based catalysts; organotitanium-based catalysts; organocobalt-based catalysts; and transesterification catalysts such as zinc acetate and manganese acetate.

[0037] The quaternary ammonium compound used in the present invention is represented by the following formulas (2-1) to (2-3):

[0038] [ka]

[0039] It is expressed as follows.

[0040] In the formula (2-1), R 21 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 22 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms or an alkyl group having 1 to 3 carbon atoms; R 23 represents an alkyl group having 1 to 3 carbon atoms, R 24represents an alkyl group having 1 to 3 carbon atoms or a benzyl group, X represents a counter ion, and p represents the valence of the counter ion X and is an integer of 1 to 3. 21 and R 22 The aliphatic hydrocarbon group of R may be linear or branched, and may be saturated or unsaturated. 22 ~R 24 The alkyl group in R may be linear or branched. 21 and R 22 The number of carbon atoms in the aliphatic hydrocarbon group is preferably 10 to 22. 22 ~R 24 The alkyl group in is preferably a methyl group. Examples of X include halogen ions (fluorine ion, chloride ion, iodine ion, bromide ion, etc.), and organic anions (acetate ion, citrate ion, lactate ion, glycolate, phosphate ion, nitrate ion, sulfonate ion, sulfate ion, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ion and ethyl sulfate ion).

[0041] Specific examples of the quaternary ammonium compound represented by the formula (2-1) include alkyl trimethyl ammonium chloride (having 12 to 16 carbon atoms), alkyl trimethyl ammonium chloride (having 16 to 18 carbon atoms), tallow alkyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, cocoyl dimethyl benzyl ammonium chloride, didecyl dimethyl ammonium chloride, di-co-alkyl dimethyl ammonium chloride, alkyl (having 16 to 18 carbon atoms) dimethyl ammonium chloride, di-hardened tallow alkyl dimethyl ammonium chloride, and dioleyl dimethyl ammonium chloride.

[0042] Such a quaternary ammonium compound represented by the formula (2-1) can be synthesized by a known method. For example, in the formula (2-1), R 24A quaternary ammonium compound having an alkyl group with 1 to 3 carbon atoms can be synthesized by subjecting 1 mole of a quaternizing agent, such as an alkyl halide or a dialkyl sulfate, having an alkyl group with 1 to 3 carbon atoms, to an addition reaction under non-catalytic conditions with 1 mole of a tertiary amine having a specific aliphatic hydrocarbon group. The reaction temperature of the addition reaction is not particularly limited, but is preferably 70 to 150°C, more preferably 80 to 120°C. The reaction time of the addition reaction is not particularly limited, but is preferably 1 to 12 hours, more preferably 1 to 6 hours. Commercially available quaternary ammonium compounds represented by the formula (2-1) (for example, "Cortamin series" manufactured by Kao Corporation, "Lipocard series" manufactured by Lion Corporation, and "Nissan Cation series" manufactured by NOF Corporation) may also be used.

[0043] In addition, in the formula (2-1), R 24 A quaternary ammonium compound having a benzyl group can be synthesized by subjecting 1 mole of benzyl chloride to an addition reaction under catalyst-free conditions with 1 mole of a tertiary amine having a specific aliphatic hydrocarbon group. The reaction temperature of the addition reaction is not particularly limited, but is preferably 70 to 150°C, and more preferably 80 to 120°C. The reaction time of the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0044] In addition, in the formula (2-2), R 25 represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms, R 26 is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, -(AO) m23 -H or an alkyl group having 1 to 3 carbon atoms; R 27 is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) m24 R represents -H, AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m21, m23, and m24 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different, X represents a counter ion, and p represents the valence of the counter ion X and is an integer from 1 to 3. 25 and R 26The aliphatic hydrocarbon group of R may be linear or branched, and may be saturated or unsaturated. 26 and R 27 The alkyl group in R may be linear or branched. 25 and R 26 The number of carbon atoms in the aliphatic hydrocarbon group is preferably 10 to 22. Examples of X include halogen ions (fluorine ion, chloride ion, iodine ion, bromide ion, etc.), and organic anions (acetate ion, citrate ion, lactate ion, glycolate, phosphate ion, nitrate ion, sulfonate ion, sulfate ion, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ion and ethyl sulfate ion).

[0045] Such a quaternary ammonium compound represented by the formula (2-2) can be synthesized by a known method. For example, in the formula (2-2), R 27 A quaternary ammonium compound in which the alkyl group has 1 to 3 carbon atoms can be synthesized by subjecting 1 mole of a quaternizing agent, such as an alkyl halide or a dialkyl sulfate, in which the alkyl group has 1 to 3 carbon atoms, to an addition reaction under catalyst-free conditions with 1 mole of the tertiary amine represented by the above formula (1-1). The reaction temperature of the addition reaction is not particularly limited, but is preferably 70 to 150°C, and more preferably 80 to 120°C. The reaction time of the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0046] In addition, in the formula (2-2), R 27 The quaternary ammonium compound having a benzyl group can be synthesized by subjecting 1 mole of benzyl chloride to an addition reaction under catalyst-free conditions with 1 mole of the tertiary amine represented by the formula (1-1). The reaction temperature for the addition reaction is not particularly limited, but is preferably 70 to 150° C., and more preferably 80 to 120° C. The reaction time for the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0047] Furthermore, in the formula (2-2), R27 - (AO) m24 The synthesis method of the quaternary ammonium compound of -H differs depending on the value of m24. When m24=1, a quaternization reaction is carried out on a specific tertiary amine with a specific alkylene oxide, and when m24>1, a specific aliphatic hydrocarbon group R is added to a specific tertiary amine. 25 Specifically, a quaternary ammonium compound having m24=1 is prepared by placing 1 mole of a tertiary amine represented by the above formula (1-1) and the same mass of distilled water in a pressure-resistant reaction vessel, and reacting with the counter ion X p- The compound can be synthesized by mixing molar equivalents of any acid capable of producing the above, neutralizing the mixture, replacing the atmosphere in a reaction vessel with nitrogen, and then adding 1 mole of a given alkylene oxide to the mixture. The reaction temperature for the addition reaction is not particularly limited, but is preferably 70 to 120°C, and more preferably 80 to 100°C. The reaction time for the addition reaction is not particularly limited, but is preferably 0.1 to 40 hours, and more preferably 0.5 to 20 hours. The quaternary ammonium compound having m24>1 can be synthesized by mixing 1 mole of a tertiary amine represented by the above formula (1-1) with a given aliphatic hydrocarbon group R 25 The reaction temperature of the addition reaction is not particularly limited, but is preferably 70 to 150° C., and more preferably 80 to 120° C. The reaction time of the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0048] In addition, in the formula (2-3), R 28 is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) m25 -H stands for R 29 and R 30 are each independently -CH3, -(AO) m26 -H, -(AO) m27 -C(=O)-R 31 or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R 31represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m22 and m25 to m27 each independently represent a number from 1 to 20, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different, X represents a counter ion, p represents the valence of the counter ion X and is an integer from 1 to 3. 29 ~R 31 The aliphatic hydrocarbon group of R may be linear or branched, and may be saturated or unsaturated. 28 The alkyl group in R may be linear or branched. 29 and R 30 The number of carbon atoms in the aliphatic hydrocarbon group is preferably 10 to 22. Examples of X include halogen ions (fluorine ion, chloride ion, iodine ion, bromide ion, etc.), and organic anions (acetate ion, citrate ion, lactate ion, glycolate, phosphate ion, nitrate ion, sulfonate ion, sulfate ion, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ion and ethyl sulfate ion).

[0049] Such a quaternary ammonium compound represented by the formula (2-3) can be synthesized by a known method. For example, in the formula (2-3), R 28 A quaternary ammonium compound in which the alkyl group has 1 to 3 carbon atoms can be synthesized by subjecting 1 mole of a quaternizing agent, such as an alkyl halide or a dialkyl sulfate, in which the alkyl group has 1 to 3 carbon atoms, to an addition reaction under catalyst-free conditions with 1 mole of the tertiary amine represented by the above formula (1-2). The reaction temperature of the addition reaction is not particularly limited, but is preferably 70 to 150°C, and more preferably 80 to 120°C. The reaction time of the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0050] In addition, in the formula (2-3), R 28The quaternary ammonium compound having a benzyl group can be synthesized by subjecting 1 mole of benzyl chloride to an addition reaction under catalyst-free conditions with 1 mole of the tertiary amine represented by the formula (1-2). The reaction temperature for the addition reaction is not particularly limited, but is preferably 70 to 150° C., and more preferably 80 to 120° C. The reaction time for the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0051] Furthermore, in the formula (2-3), R 28 - (AO) m25 The quaternary ammonium compound of -H is prepared by placing 1 mole of the tertiary amine represented by the formula (1-2) and the same mass of distilled water in a pressure-resistant reaction vessel, and adding a counter ion X p- The compound can be synthesized by mixing molar equivalents of any acid capable of producing the above, neutralizing the mixture, replacing the atmosphere in a reaction vessel with nitrogen, and then adding 1 mole of a specific alkylene oxide to the mixture. The reaction temperature for the addition reaction is not particularly limited, but is preferably 70 to 120° C., and more preferably 80 to 100° C. The reaction time for the addition reaction is not particularly limited, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours.

[0052] In the pulp slurry used in the present invention, the amount of such an amine-based additive component is preferably 1 to 400 parts by mass, more preferably 10 to 200 parts by mass, per 100 parts by mass of pulp (paper stock solids). When the amount of the amine-based additive component is within the above range, the flexibility and texture imparted to the paper are improved, and foaming is less likely to occur during papermaking, improving productivity. On the other hand, when the amount of the amine-based additive component is less than the lower limit, the flexibility and texture imparted to the paper may not be sufficiently improved, while when the amount exceeds the upper limit, foaming occurs during papermaking, tending to reduce productivity.

[0053] (Polyamine) The softener used in the present invention preferably further contains a polyamine, which will be described later, in addition to lecithin and the amine-based additive component, thereby further improving the softness and feel imparted to paper.

[0054] The polyamine used in the present invention is an aliphatic hydrocarbon having three or more primary amino groups bonded thereto, and may be linear, branched, cyclic, or a mixture thereof.

[0055] Examples of such polyamines include polydiallyldimethylammonium salts, polyvinylamines, polyethyleneimines, and epichlorohydrin polycondensates of dimethylamine, polyallylamine, polyallylamine sulfone copolymers, polyamine polyamides, and polyamine-epichlorohydrin copolymers. Among these polyamines, polydiallyldimethylammonium salts, polyvinylamines, polyethyleneimines, and epichlorohydrin polycondensates of dimethylamine are preferred from the viewpoint of improving the flexibility and texture imparted to paper.

[0056] The polydiallyldimethylammonium salt contains a structure represented by the following formula (3-1) and / or a structure represented by the following formula (3-2).

[0057] [ka]

[0058] In the formulas (3-1) and (3-2), n31 and n32 are each independently an integer that gives a weight average molecular weight of the polydiallyldimethylammonium salt of 1000 to 1000000, X represents a counter ion, and p represents the valence of the counter ion X and is an integer of 1 to 3. Examples of X include halogen ions (fluorine ions, chloride ions, iodine ions, bromide ions, etc.) and organic anions (acetate ions, citrate ions, lactate ions, glycolate ions, phosphate ions, nitrate ions, sulfonate ions, sulfate ions, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ions and ethyl sulfate ions).

[0059] The polydiallyldimethylammonium salt used in the present invention may contain either one of the structure represented by the formula (3-1) and the structure represented by the formula (3-2), or may contain both.

[0060] Such polydiallyldimethylammonium salts can be synthesized by known methods, for example, by polymerizing diallyldimethylammonium chloride in the presence of a polymerization initiator such as 2,2'-azobis(2-methylpropionamidine) dihydrochloride (for example, "V-50" manufactured by Wako Pure Chemical Industries, Ltd.).

[0061] The polyvinylamine contains a structure represented by the following formula (3-3).

[0062] [ka]

[0063] In the formula (3-3), n33 is an integer that gives a weight average molecular weight of polyvinylamine of 1000 to 1000000, X represents a counter ion, and p represents the valence of the counter ion X and is an integer of 1 to 3. Examples of X include halogen ions (fluorine ion, chloride ion, iodine ion, bromide ion, etc.) and organic anions (acetate ion, citrate ion, lactate ion, glycolate, phosphate ion, nitrate ion, sulfonate ion, sulfate ion, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ion and ethyl sulfate ion).

[0064] Such polyvinylamine can be synthesized by a known method, for example, by polymerizing N-vinylformamide in the presence of a polymerization initiator or a chain transfer catalyst, followed by a hydrolysis reaction.

[0065] Furthermore, the polyethyleneimine contains a linear structure represented by the following formula (3-4) or a branched structure represented by the following formula (3-5).

[0066] [ka]

[0067] In the formula (3-4), n34 is an integer that gives a weight average molecular weight of polyethyleneimine of 1000 to 1000000, X represents a counter ion, and p represents the valence of the counter ion X and is an integer of 1 to 3. Examples of X include halogen ions (fluorine ion, chloride ion, iodine ion, bromide ion, etc.) and organic anions (acetate ion, citrate ion, lactate ion, glycolate, phosphate ion, nitrate ion, sulfonate ion, sulfate ion, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ion and ethyl sulfate ion).

[0068] Such polyethyleneimine can be synthesized by a known method, for example, by ring-opening polymerization of ethyleneimine in the presence of an acid catalyst.

[0069] The epichlorohydrin polycondensate of dimethylamine contains a structure represented by the following formula (3-6).

[0070] [ka]

[0071] In the formula (3-6), n35 is an integer that gives a weight-average molecular weight of 1000 to 1000000 of the epichlorohydrin polycondensate of dimethylamine, X represents a counter ion, and p represents the valence of the counter ion X and is an integer of 1 to 3. Examples of X include halogen ions (fluorine ion, chloride ion, iodine ion, bromide ion, etc.) and organic anions (acetate ion, citrate ion, lactate ion, glycolate, phosphate ion, nitrate ion, sulfonate ion, sulfate ion, alkyl sulfate ester ions having 1 to 3 carbon atoms, such as methyl sulfate ion and ethyl sulfate ion).

[0072] Such an epichlorohydrin polycondensate of dimethylamine can be synthesized by a known method, for example, by dropping epichlorohydrin into dimethylamine to cause a polycondensation reaction between dimethylamine and epichlorohydrin.

[0073] The weight average molecular weight of such polyamines is not particularly limited, but from the viewpoint of improving the flexibility and feel imparted to paper, it is preferably 1,000 to 1,000,000, and more preferably 1,000 to 200,000.

[0074] In the pulp slurry used in the present invention, the amount of such polyamine is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, per 100 parts by mass of pulp (paper stock solids). When the amount of polyamine is within the above range, the flexibility and texture imparted to the paper are further improved. On the other hand, when the amount of polyamine is less than the lower limit, the flexibility and texture imparted to the paper may not be sufficiently improved, and on the other hand, when the amount of polyamine is more than the upper limit, the emulsification and dispersion of lecithin is easily hindered, and the flexibility and texture imparted to the paper may not be sufficiently improved.

[0075] (Production method of flexible paper) The method for producing soft paper of the present invention is a method for producing soft paper by preparing a pulp slurry containing lecithin, and, if necessary, the amine-based additive component and, if necessary, the polyamine, and a softener, and making paper from the pulp slurry containing the softener.

[0076] In the method for producing soft paper of the present invention, a softener may be added, for example, in a process for beating pulp fibers using a beating device (beater) or the like (beating process), a process for loosening waste paper using a pulper or the like (defibration process), or a process for mixing various chemicals into the pulp slurry (preparation process), but from the viewpoint of easily improving the flexibility and texture imparted to the paper, it is preferable to prepare a pulp slurry containing various chemicals other than the softener as necessary, and then add the softener before papermaking.

[0077] Examples of the various chemicals include coagulants, sizing agents, paper strength agents, dryer release agents, pitch control agents, slime control agents, retention aids, defoamers, fillers, pigments, dyes, dispersants, and pH adjusters.

[0078] As a method for adding each component of the softener, the original liquid may be added directly to the pulp slurry, but from the viewpoint of the dispersibility of each component in the pulp slurry, it is preferable to disperse each component in water in advance and add this dispersion to the pulp slurry. Also, the dispersion of each component of the softener may be added independently to the pulp slurry, or a dispersion containing all the components of the softener may be prepared in advance and this softener dispersion may be added to the pulp slurry.

[0079] Furthermore, when dispersing each component of the softener in water, lecithin may be dispersed using various anionic, cationic, nonionic or amphoteric surfactants, fatty acid esters such as glycerides and polyglycerol fatty acid esters, alkaline compounds such as triethanolamine and sodium hydroxide, and solvents such as ethanol, but in the present invention, since the amine-based additive component acts as a dispersant for lecithin, it is preferable to disperse lecithin in water using the amine-based additive component. On the other hand, the amine-based additive component and the polyamine can be uniformly dispersed in water without using a dispersant.

[0080] Next, the paper softener of the present invention will be described. The paper softener of the present invention contains lecithin and the amine-based additive component. In the softener containing lecithin and the amine-based additive component, the amine-based additive component acts as a dispersant for lecithin, improving the flexibility and feel imparted to paper.

[0081] The paper softener of the present invention preferably further contains the polyamine, which further improves the softness and feel imparted to paper. EXAMPLES

[0082] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The tertiary amines, quaternary ammonium compounds, and polyamines used in the examples and comparative examples are shown below.

[0083] [Tertiary amine] <Tertiary amine represented by the following formula (1-1)>

[0084] [ka]

[0085] m11=1 and R 12 Tertiary monoamine (n11 = 0) of EO-H (m14 = 1): used in Examples A1, A2, C1 to C4 and Comparative Examples 2 and 9 A predetermined number of moles of a predetermined alkylene oxide are subjected to an addition reaction at 120° C. under catalyst-free conditions to 1 mole of a primary aliphatic monoamine having an aliphatic hydrocarbon group shown in R11 in Table 1, and a compound represented by the formula (1-1) in which m11=1 and R 12 synthesized a tertiary monoamine (n11=0) of EO-H (m14=1).

[0086] m11=2+1 and R 12 (EO)2(PO)1-H (m14=2+1) or m11=4 tertiary monoamine (n11=0): used in Examples A3 and A4 First, a predetermined number of moles of a predetermined alkylene oxide is subjected to an addition reaction at 120° C. under catalyst-free conditions to 1 mole of a primary aliphatic monoamine having an aliphatic hydrocarbon group shown by R11 in Table 1 or a secondary aliphatic monoamine having an aliphatic hydrocarbon group shown by R11 and R12 in Table 1, to obtain a compound represented by the formula (1-1) in which m11=1 and R 12 synthesized EO-H (m14 = 1) or tertiary monoamine (n11 = 0) with m11 = 1. Next, this tertiary monoamine (m11 = 1 and R 12is added to 1 mole of EO-H (m14=1) or m11=1, n11=0) in the presence of sodium hydroxide as an alkali catalyst at 120°C, and 12 synthesized (EO)2(PO)1-H (m14 = 2 + 1) or tertiary monoamines (n11 = 0) with m11 = 4.

[0087] m11 and m12 = 1 and R 12 Tertiary diamine (n11 = 1) of EO-H (m14 = 1): used in Example A5 A predetermined number of moles of a predetermined alkylene oxide are subjected to an addition reaction at 120° C. under catalyst-free conditions to 1 mole of a primary aliphatic diamine having an aliphatic hydrocarbon group shown in R11 in Table 1, and a compound represented by the formula (1-1) in which m11 and m12=1 and R 12 synthesized a tertiary diamine (n11 = 1) of EO-H (m14 = 1).

[0088] <Tertiary amine represented by the following formula (1-2)>

[0089] [ka]

[0090] m13=1 and R 14 and R 15 is EO-H(m15=1) or EO-C(=O)-C 17 H 33 Tertiary monoamine (m16=1): Examples A6 to A8, C5 to C8, Comparative Examples 3 and 10 A predetermined number of moles of a predetermined aliphatic carboxylic acid is esterified with respect to 1 mole of triethanolamine in the presence of n-tetrabutoxytitanium as an esterification catalyst at 160°C, and the above-mentioned formula (1-2) is obtained in which m13=1 and R 14 and R 15 is EO-H(m15=1) or EO-C(=O)-C 17 H 33 A tertiary monoamine (m16=1) was synthesized.

[0091] m13=2 and R 15 (EO)2-C(=O)-C 17 H 33 Tertiary monoamine (m16=2): used in Example A9 First, a predetermined number of moles of a predetermined alkylene oxide are added to 1 mole of a primary aliphatic monoamine having an aliphatic hydrocarbon group shown in R14 in Table 2 under catalyst-free conditions at 120°C to obtain a compound represented by the formula (1-1) in which m11=1 and R 12 synthesized a tertiary monoamine (n11 = 0) of EO-H (m14 = 1). Next, this tertiary monoamine (m11 = 1 and R 12 A predetermined number of moles of a predetermined alkylene oxide are added to 1 mole of EO-H (m14=1, n11=0) in the presence of sodium hydroxide as an alkali catalyst at 120°C to obtain a compound represented by the formula (1-1), in which m11=2 and R 12 synthesized a tertiary monoamine (n11 = 0) of (EO)2-H (m14 = 2). Then, this tertiary monoamine (m11 = 2 and R 12 A predetermined number of moles of a predetermined aliphatic carboxylic acid are esterified at 160° C. in the presence of n-tetrabutoxytitanium as an esterification catalyst with 1 mole of (EO)2-H (m14=2, n11=0), and the compound represented by the formula (1-2) above, m13=2 and R 15 (EO)2-C(=O)-C 17 H 33 A tertiary monoamine (m16=2) was synthesized.

[0092] [Quaternary ammonium compounds] <Quaternary ammonium compound represented by the following formula (2-1)>

[0093] [ka]

[0094] ·R 21 and R 22 C 18 H 35 , R 23 and R 24Quaternary ammonium compound with CH3, X is Cl, and p=1: used in Example B1 "Lipocard 2O-75I" manufactured by Lion Specialty Chemicals Co., Ltd.

[0095] ·R 21 and R 22 C 12 H 25 , R 23 and R 24 Quaternary ammonium compound having CH3, X being Cl, and p=1: used in Examples B2, C9 to C12, D1 to D4, and Comparative Examples 4, 5, and 11 "Lipocard 2C-75" manufactured by Lion Specialty Chemicals Co., Ltd.

[0096] ·R 21 C 18 H 35 , R 22 , R 23 and R 24 Quaternary ammonium compound with CH3, X is Cl, and p=1: used in Example B3 "Lipocard T-28" manufactured by Lion Specialty Chemicals Co., Ltd.

[0097] ·R 21 C 16 H 33 , R 22 and R 23 CH3, R 24 Quaternary ammonium compound with CH2-C6H5, X is Cl, and p=1: used in Example B4 A predetermined number of moles of benzyl chloride are subjected to an addition reaction at 100° C. under catalyst-free conditions to 1 mole of a tertiary aliphatic monoamine having an aliphatic hydrocarbon group shown in R21 to R23 in Table 3, to obtain a compound represented by the formula (2-1) R 24 synthesized a quaternary ammonium compound of the formula CH2-C6H5.

[0098] <Quaternary ammonium compound represented by the following formula (2-2)>

[0099] [ka]

[0100] ·R 27 Quaternary ammonium compound having CH3 and m21=1: used in Examples B5, B6, C13 to C16, and Comparative Examples 6 and 12 First, a predetermined number of moles of a predetermined alkylene oxide was added to 1 mole of a secondary aliphatic monoamine having an aliphatic hydrocarbon group shown in R25 and R26 in Table 4 under catalyst-free conditions at 120°C to synthesize a tertiary monoamine (n11=0) in the above formula (1-1). Next, a predetermined number of moles of dimethyl sulfate was added to 1 mole of this tertiary monoamine (m11=1, n11=0) under catalyst-free conditions at 100°C to synthesize R 27 synthesized a quaternary ammonium compound with CH3, m21=1.

[0101] ·R 27 is CH2-C6H5, m21=1 and R 26 Quaternary ammonium compound with EO-H (m23=1): used in Example B7 First, a predetermined number of moles of a predetermined alkylene oxide are subjected to an addition reaction at 120° C. under catalyst-free conditions to 1 mole of a primary aliphatic monoamine having an aliphatic hydrocarbon group shown in R25 in Table 4, to obtain a compound represented by the formula (1-1) in which m11=1 and R 12 synthesized a tertiary monoamine (n11 = 0) of EO-H (m14 = 1). Next, this tertiary monoamine (m11 = 1 and R 12 A predetermined number of moles of benzyl chloride are added to 1 mole of EO-H (m14=1, n11=0) under catalyst-free conditions at 100°C to obtain R 27 is CH2-C6H5, m21=1 and R 26 synthesized a quaternary ammonium compound of EO-H (m23=1).

[0102] ·R 27 is CH2-C6H5, m21=2+1 and R 26 Quaternary ammonium compound with the formula (EO)2(PO)1-H (m23=2+1): used in Example B8 First, a predetermined number of moles of a predetermined alkylene oxide are subjected to an addition reaction at 120° C. under catalyst-free conditions to 1 mole of a primary aliphatic monoamine having an aliphatic hydrocarbon group shown in R25 in Table 4, to obtain a compound represented by the formula (1-1) in which m11=1 and R 12 synthesized a tertiary monoamine (n11 = 0) of EO-H (m14 = 1). Next, this tertiary monoamine (m11 = 1 and R 12 A predetermined number of moles of a predetermined alkylene oxide is subjected to an addition reaction at 120° C. in the presence of sodium hydroxide as an alkali catalyst to 1 mole of EO-H (m14=1, n11=0), and in the above formula (1-1), m11=2+1 and R 12 synthesized a tertiary monoamine (n11 = 0) of (EO)2(PO)1-H (m14 = 2 + 1). Then, this tertiary monoamine (m11 = 2 + 1 and R 12 A predetermined number of moles of benzyl chloride are added to 1 mole of (EO)2(PO)1-H (m14=2+1, n11=0) at 100° C. under a catalyst-free condition to obtain R 27 is CH2-C6H5, m21=2+1 and R 26 synthesized a quaternary ammonium compound of the formula (EO)2(PO)1-H (m23=2+1).

[0103] ·R 27 Quaternary ammonium compound with EO-H (m24=1) and m21=4: used in Example B9 First, a predetermined number of moles of a predetermined alkylene oxide was added to 1 mole of a secondary aliphatic monoamine having an aliphatic hydrocarbon group shown in R25 and R26 in Table 4 under catalyst-free conditions at 120°C to synthesize a tertiary monoamine (n11=0) in the above formula (1-1) where m11=1. Next, a predetermined number of moles of a predetermined alkylene oxide was added to 1 mole of this tertiary monoamine (m11=1, n11=0) in the presence of sodium hydroxide as an alkali catalyst at 120°C to synthesize a tertiary monoamine (n11=0) in the above formula (1-1) where m11=4. Then, 1 mole of this tertiary monoamine (m11=4, n11=0) and the same mass of distilled water were charged into a pressure-resistant reaction vessel, and 0.97 moles of acetic acid were mixed therein to neutralize the mixture. The atmosphere in the reaction vessel was replaced with nitrogen, and then 1 mole of a given alkylene oxide was added and reacted at 90° C. to obtain the product represented by R 27 synthesized a quaternary ammonium compound with EO-H (m24 = 1) and m21 = 4.

[0104] <Quaternary ammonium compound represented by the following formula (2-3)>

[0105] [ka]

[0106] ·R 28 is CH2-C6H5, m22=1 and R 29 and R 30 is EO-H(m26=1) or EO-C(=O)-C 17 H 33 Quaternary ammonium compound (m27=1): used in Examples B10, B11, C17 to C20, and Comparative Examples 7 and 13 A predetermined number of moles of a predetermined aliphatic carboxylic acid is esterified with respect to 1 mole of triethanolamine in the presence of n-tetrabutoxytitanium as an esterification catalyst at 160°C, and the above-mentioned formula (1-2) is obtained in which m13=1 and R 14 and R 15 is EO-H(m15=1) or EO-C(=O)-C 17 H 33(m16=1) was synthesized. Next, this tertiary monoamine (m13=1 and R 14 and R 15 is EO-H(m15=1) or EO-C(=O)-C 17 H 33 (m16=1)) is subjected to an addition reaction with a predetermined number of moles of benzyl chloride under catalyst-free conditions at 100° C. to obtain R 28 is CH2-C6H5, m22=1 and R 29 and R 30 is EO-H(m26=1) or EO-C(=O)-C 17 H 33 A quaternary ammonium compound with m27=1 was synthesized.

[0107] ·R 28 is CH2-C6H5, m22=2 and R 30 EO-C(=O)-C 17 H 33 Quaternary ammonium compound (m27=2): used in Example B12 First, a predetermined number of moles of a predetermined alkylene oxide are subjected to an addition reaction at 120° C. under catalyst-free conditions to 1 mole of a primary aliphatic monoamine having an aliphatic hydrocarbon group shown in R29 in Table 5, to obtain a compound represented by the formula (1-1) in which m11=1 and R 12 synthesized a tertiary monoamine (n11 = 0) of EO-H (m14 = 1). Next, this tertiary monoamine (m11 = 1 and R 12 A predetermined number of moles of a predetermined alkylene oxide are added to 1 mole of EO-H (m14=1, n11=0) in the presence of sodium hydroxide as an alkali catalyst at 120°C to obtain a compound represented by the formula (1-1), in which m11=2 and R 12 synthesized a tertiary monoamine (n11 = 0) of (EO)2-H (m14 = 2). Next, this tertiary monoamine (m11 = 2 and R 12 A predetermined number of moles of a predetermined aliphatic carboxylic acid are esterified at 160° C. in the presence of n-tetrabutoxytitanium as an esterification catalyst with 1 mole of (EO)2-H (m14=2, n11=0), and the compound represented by the formula (1-2) above, m13=2 and R 15 (EO)2-C(=O)-C17 H 33 (m16=2) was synthesized. Then, this tertiary monoamine (m13=2 and R 15 (EO)2-C(=O)-C 17 H 33 (m16=2)) is subjected to an addition reaction with a predetermined number of moles of benzyl chloride at 100° C. under catalyst-free conditions to obtain R 28 is CH2-C6H5, m22=2 and R 30 (EO)2-C(=O)-C 17 H 33 A quaternary ammonium compound with m27=2 was synthesized.

[0108] ·R 28 is EO-H(m25=1), m22=1 and R 29 and R 30 EO-C(=O)-C 17 H 33 Quaternary ammonium compound with m27=1: used in Example B13 A predetermined number of moles of a predetermined aliphatic carboxylic acid is esterified with respect to 1 mole of triethanolamine in the presence of n-tetrabutoxytitanium as an esterification catalyst at 160°C, and the above-mentioned formula (1-2) is obtained in which m13=1 and R 14 and R 15 EO-C(=O)-C 17 H 33 (m16=1) was synthesized. Next, this tertiary monoamine (m13=1 and R 14 and R 15 EO-C(=O)-C 17 H 33 1 mole of (m16=1) and the same mass of distilled water were charged into a pressure-resistant reaction vessel, 0.97 moles of acetic acid were mixed and neutralized, and the inside of the reaction vessel was replaced with nitrogen. Then, 1 mole of a given alkylene oxide was added and reacted at 90° C. to obtain R 28 is EO-H(m25=1), m22=1 and R 29 and R 30 EO-C(=O)-C 17 H 33 A quaternary ammonium compound with m27=1 was synthesized.

[0109] [Polyamine] Polydiallyldimethylammonium salt (formula (3-1) below): used in Examples C9, C13, C17 and Comparative Examples 8 to 13 "PAS-H-10L" manufactured by Nittobo Medical Co., Ltd., weight average molecular weight: 200,000, in the following formula (3-1), X is Cl, p = 1.

[0110] [ka]

[0111] Polyvinylamine (formula (3-3) below): used in Examples C10, C14, and C18 "PVAM-0570B" manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 100,000, in the following formula (3-3), X is Cl, p=1.

[0112] [ka]

[0113] Polyethyleneimine (formula (3-5) below): used in Examples C11, C15, and C19 "Epomin SP-200" manufactured by Nippon Shokubai Co., Ltd., weight average molecular weight: 10,000.

[0114] [ka]

[0115] Epichlorohydrin polycondensate of dimethylamine (following formula (3-6)): used in Examples C12, C16, and C20 Obtained by dropping epichlorohydrin into dimethylamine to carry out a polycondensation reaction. Weight average molecular weight: 50,000. In the following formula (3-6), X is Cl and p=1.

[0116] [ka]

[0117] (Example A1) Hardwood bleached kraft pulp (LBKP) was beaten using a beater to a Canadian standard freeness of 550 to 600 ml to prepare a pulp slurry with a stock solids content (pulp) of 1% by mass. While stirring this pulp slurry using a chemical stirrer, 0.7 parts by mass of soybean lecithin and the R 11 , R 12 , R 13 A softener consisting of 0.3 parts by mass of a tertiary amine having AO, m11, m12 and n11 was added to prepare a paper stock. The paper stock was mixed with a paper sheet machine (manufactured by Kumagai Riki Kogyo Co., Ltd.) to prepare a paper stock having a basis weight of 40 g / m 2 The paper was then pressed at a pressure of 700 kPa for 5 minutes using an air sheet press (Kumagaya Riki Kogyo Co., Ltd.), and then dried at 105° C. for 5 minutes using a test Yankee dryer (Kumagaya Riki Kogyo Co., Ltd.) to obtain a test paper.

[0118] (Examples A2 to A5) As the tertiary amine, R 11 , R 12 , R 13 A test paper was prepared in the same manner as in Example A1, except that 0.3 parts by mass of a tertiary amine having AO, m11, m12 and n11 was used.

[0119] (Examples A6 to A9) As the tertiary amine, R 14 , R 15 , R 16 A test paper was prepared in the same manner as in Example A1, except that 0.3 parts by mass of a tertiary amine having AO and m13 was used.

[0120] (Examples B1 to B4) Instead of the tertiary amine, R 21 , R 22, R 23 , R 24 A test paper was prepared in the same manner as in Example A1, except that 0.3 parts by mass of a quaternary ammonium compound having X, p and p was used.

[0121] (Examples B5 to B9) Instead of the tertiary amine, R 25 , R 26 , R 27 A test paper was prepared in the same manner as in Example A1, except that 0.3 parts by mass of a quaternary ammonium compound having AO, m21, X and p was used.

[0122] (Examples B10 to B13) Instead of the tertiary amine, R 28 , R 29 , R 30 , R 31 A test paper was prepared in the same manner as in Example A1, except that 0.3 parts by mass of a quaternary ammonium compound having AO, m22, X and p was used.

[0123] (Examples C1 to C4) As a softening agent, soybean lecithin and the above-mentioned formula (1-1) represented by R 11 C 18 H 35 , R 12 A test paper was prepared in the same manner as in Example A2, except that a softener consisting of a tertiary amine in which EO-H, AO is EO, m11 = 1 and n11 = 0 and a polydiallyldimethylammonium salt, a polyvinylamine, a polyethyleneimine or an epichlorohydrin polycondensate of dimethylamine was used.

[0124] (Examples C5 to C8) As a tertiary amine, the amount shown in Table 6 is represented by the formula (1-2), and R 14 EO-H, R 15 EO-C(=O)-C 17 H 33 , R 16 C 17 H 33Test papers were prepared in the same manner as in Examples C1 to C4, except that EO and a tertiary amine in which m13=1 were used as AO.

[0125] (Examples C9 to C12) Instead of the tertiary amine, the amount shown in Table 7 is 21 and R 22 C 12 H 25 , R 23 and R 24 Test papers were prepared in the same manner as in Examples C1 to C4, except that a quaternary ammonium compound in which X was CH3, X was Cl, and p=1 was used.

[0126] (Examples C13 to C16) Instead of the tertiary amine, the amount shown in Table 7 is 25 and R 26 C 18 H 35 , R 27 Test papers were prepared in the same manner as in Examples C1 to C4, except that a quaternary ammonium compound in which: CH3, AO was EO, m21=1, X was CH3SO4, and p=1 was used.

[0127] (Examples C17 to C20) Instead of the tertiary amine, the amount shown in Table 7 is 28 CH2-C6H5, R 29 and R 30 EO-C(=O)-C 17 H 33 , R 31 C 17 H 33 Test papers were prepared in the same manner as in Examples C1 to C4, except that a quaternary ammonium compound in which AO was EO, m22=1, X was Cl, and p=1 was used.

[0128] (Examples D1 to D4) Test papers were prepared in the same manner as in Example B2, except that the amounts of soybean lecithin and quaternary ammonium compound were changed to those shown in Table 8.

[0129] Comparative Example 1 A test paper was prepared in the same manner as in Example A1, except that no softener was added.

[0130] Comparative Example 2 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (1-1) and R 11 C 18 H 35 , R 12 A test paper was prepared in the same manner as in Example A2, except that a softener consisting of only a tertiary amine in which EO-H, AO, EO, m11=1 and n11=0 was used.

[0131] Comparative Example 3 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (1-2) and R 14 EO-H, R 15 EO-C(=O)-C 17 H 33 , R 16 C 17 H 33 A test paper was prepared in the same manner as in Example A6, except that a softener consisting only of EO and a tertiary amine having m13=1 was used as AO.

[0132] (Comparative Examples 4 to 5) As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (2-1) and R 21 and R 22 C 12 H 25 , R 23 and R 24 A test paper was prepared in the same manner as in Example B2, except that a softener consisting of a quaternary ammonium compound in which X is CH3, X is Cl, and p=1 was used.

[0133] Comparative Example 6 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (2-2) and R 25 and R 26 C 18 H 35 , R 27A test paper was prepared in the same manner as in Example B6, except that a softener consisting of a quaternary ammonium compound in which: CH3, AO is EO, m21=1, X is CH3SO4, and p=1 was used.

[0134] Comparative Example 7 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (2-3) and R 28 CH2-C6H5, R 29 and R 30 EO-C(=O)-C 17 H 33 , R 31 C 17 H 33 A test paper was prepared in the same manner as in Example B10, except that a softener consisting of a quaternary ammonium compound in which AO is EO, m22=1, X is Cl, and p=1 was used.

[0135] Comparative Example 8 Test papers were prepared in the same manner as in Example C1, except that soybean lecithin and tertiary amine were not added, and a softener consisting only of polydiallyldimethylammonium salt in the amount shown in Table 9 was used as the softener.

[0136] Comparative Example 9 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (1-1) and R 11 C 18 H 35 , R 12 A test paper was prepared in the same manner as in Example C1, except that a softener consisting of a tertiary amine having EO-H, AO being EO, m11=1 and n11=0 and polydiallyldimethylammonium salt was used.

[0137] Comparative Example 10 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (1-2) and R 14 EO-H, R 15 EO-C(=O)-C 17 H 33 , R 16 C 17 H 33A test paper was prepared in the same manner as in Example C5, except that a softener consisting of a tertiary amine having EO and m13=1 and a polydiallyldimethylammonium salt was used as AO.

[0138] Comparative Example 11 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (2-1) and R 21 and R 22 C 12 H 25 , R 23 and R 24 A test paper was prepared in the same manner as in Example C9, except that a softener consisting of a quaternary ammonium compound in which X is CH3, X is Cl, and p=1, and a polydiallyldimethylammonium salt was used.

[0139] Comparative Example 12 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (2-2) and R 25 and R 26 C 18 H 35 , R 27 A test paper was prepared in the same manner as in Example C13, except that a softener consisting of a quaternary ammonium compound in which m21=1, X=CH3SO4 and p=1 and polydiallyldimethylammonium salt was used.

[0140] Comparative Example 13 As a softener, soybean lecithin was not added, and the amount of the softener represented by the formula (2-3) and R 28 CH2-C6H5, R 29 and R 30 EO-C(=O)-C 17 H 33 , R 31 C 17 H 33 A test paper was prepared in the same manner as in Example C17, except that a softener consisting of a quaternary ammonium compound in which AO is EO, m22=1, X is Cl, and p=1, and a polydiallyldimethylammonium salt was used.

[0141] <Flexibility> In accordance with JAPAN TAPPI Paper and Pulp Test Method No. 34 (2000) "Paper - Softness Test Method", the resistance force [gf] generated when the test paper was pressed was measured using a handle-o-meter. The test paper was cut to a size of 100 mm x 100 mm, and measurements were taken with an effective bending stroke of 12 mm and a test paper receiving plate clearance of 10 mm. The results are shown in Tables 1 to 9. A smaller measured value indicates better flexibility.

[0142] <Texture> Five test papers were held in one hand, and a sensory evaluation of softness was performed, and rated according to the following five-level scale. Ten people performed the evaluation, and the average value was calculated. The results are shown in Tables 1 to 9.

[0143] (Evaluation Criteria) 5: Very soft. 4: Soft. 3: Slightly soft. 2: Same as no fabric softener. 1: Hard.

[0144] <density> According to JIS P 8118:2014, the density (mass per unit volume) was calculated from the measured values ​​of the thickness and mass of one sheet of paper. The results are shown in Tables 1 to 9.

[0145] [Table 1]

[0146] [Table 2]

[0147] [Table 3]

[0148] [Table 4]

[0149] [Table 5]

[0150] [Table 6]

[0151] [Table 7]

[0152] [Table 8]

[0153] [Table 9]

[0154] As shown in Tables 1 to 7, it was found that low-density soft paper with excellent flexibility and feel was obtained when a softener containing lecithin and a tertiary amine represented by the formulas (1-1) to (1-2) was blended with a pulp slurry and paper was made (Examples A1 to A9), when a softener containing lecithin and a quaternary ammonium compound represented by the formulas (2-1) to (2-3) was blended with a pulp slurry and paper was made (Examples B1 to B13), when a softener containing lecithin, a tertiary amine represented by the formulas (1-1) to (1-2) and the polyamine was blended with a pulp slurry and paper was made (Examples C1 to C8), and when a softener containing lecithin, a quaternary ammonium compound represented by the formulas (2-1) to (2-3) and the polyamine was blended with a pulp slurry and paper was made (Examples C9 to C20).

[0155] On the other hand, as shown in Table 9, when no softener was added (Comparative Example 1), when a softener containing no lecithin and only the tertiary amines represented by the formulas (1-1) to (1-2) was added (Comparative Examples 2 to 3), when a softener containing no lecithin and only the quaternary ammonium compounds represented by the formulas (2-1) to (2-3) was added (Comparative Examples 4 to 7), when a softener containing no lecithin and only the polyamines was added (Comparative Example 8), and when a softener containing no lecithin and only the polyamines was added (Comparative Example 9) were added. First, it was found that when a softener containing only the tertiary amine represented by the formulas (1-1) to (1-2) and the polyamine was blended (Comparative Examples 9 to 10), and when a softener containing only the quaternary ammonium compound represented by the formulas (2-1) to (2-3) and the polyamine without lecithin was blended (Comparative Examples 11 to 13), the flexibility and feel were inferior and the density was high compared to Examples A1 to A9, Examples B1 to B13, and Examples C1 to C20.

[0156] In addition, as shown in Tables 1 to 7, it was found that by blending the polyamine with a softener containing lecithin and a tertiary amine represented by the formulas (1-1) to (1-2) or a quaternary ammonium compound represented by the formulas (2-1) to (2-3), the softness and feel were improved and the density was reduced (Examples C1 to C20).

[0157] On the other hand, as shown in Table 9, even when the polyamine was blended with a softener that did not contain lecithin and contained only the tertiary amine represented by the formulas (1-1) to (1-2) or the quaternary ammonium compound represented by the formulas (2-1) to (2-3), the flexibility and feel were not improved, and the density did not change (Comparative Examples 9 to 13). [Industrial Applicability]

[0158] As described above, according to the present invention, it is possible to obtain paper with good flexibility. Paper with good flexibility is excellent in ease of turning, texture, feel, and ease of delamination, so the method for producing flexible paper of the present invention is particularly useful as a method for producing household paper such as tissue paper, toilet paper, and kitchen paper. It can also be used to produce newsprint, coated paper, recording paper such as inkjet recording paper and thermal recording paper, packaging paper, paperboard, liner, corrugated paper, wallpaper, sliding door paper, etc.

Claims

1. A method for producing soft paper, comprising making paper from a pulp slurry containing pulp and a softener including lecithin.

2. The softener is represented by the following formulas (1-1) to (1-2): 【Chemistry 1】 [In the above formula (1-1), R １１ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R １２ is an aliphatic hydrocarbon group having 8 to 26 carbon atoms or -(AO) ｍ１４ represents —H, R １３ represents an alkylene group having 2 to 4 carbon atoms, n11 is an integer of 0 to 3, and in (1-2), R １４ and R １５ Each independently represents -CH ３ , -(AO) ｍ１５ -H, -(AO) ｍ１６ -C(=O)-R １６ or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R １６ represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, and in the formulas (1-1) and (1-2), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m11 to m16 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different. and tertiary amines represented by the following formulae (2-1) to (2-3): 【Chemistry 2】 [In the above formula (2-1), R ２１ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R ２２ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms or an alkyl group having 1 to 3 carbon atoms; R ２３ represents an alkyl group having 1 to 3 carbon atoms; R ２４ represents an alkyl group having 1 to 3 carbon atoms or a benzyl group, and in the formula (2-2), R ２５ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R ２６ is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, -(AO) ｍ２３ represents —H or an alkyl group having 1 to 3 carbon atoms; R ２７ is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) ｍ２４ m21, m23 and m24 each independently represent a number from 1 to 4; when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different; ２８ is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) ｍ２５ represents —H, R ２９ and R ３０ Each independently represents -CH ３ , -(AO) ｍ２６ -H, -(AO) ｍ２７ -C(=O)-R ３１ or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R ３１ represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, m22 and m25 to m27 each independently represent a number from 1 to 20, when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different, in formulas (2-2) and (2-3), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, and in formulas (2-1) to (2-3), X represents a counter ion, p represents the valence of the counter ion X, and is an integer from 1 to 3.

2. The method for producing soft paper according to claim 1, further comprising at least one amine-based additive selected from the group consisting of quaternary ammonium compounds represented by the formula:

3. The method for producing soft paper according to claim 2, characterized in that the softener further contains at least one polyamine selected from the group consisting of polydiallyldimethylammonium salt, polyvinylamine, polyethyleneimine, and epichlorohydrin polycondensates of dimethylamine, polyallylamine, polyallylamine sulfone copolymer, polyamine polyamide, and polyamine-epichlorohydrin copolymer.

4. Lecithin and The following formulas (1-1) to (1-2): 【Chemistry 3】 [In the above formula (1-1), R １１ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R １２ is an aliphatic hydrocarbon group having 8 to 26 carbon atoms or -(AO) ｍ１４ represents —H, R １３ represents an alkylene group having 2 to 4 carbon atoms, n11 is an integer of 0 to 3, and in (1-2), R １４ and R １５ Each independently represents -CH ３ , -(AO) ｍ１５ -H, -(AO) ｍ１６ -C(=O)-R １６ or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R １６ represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, and in the formulas (1-1) and (1-2), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, m11 to m16 each independently represent a number from 1 to 4, and when there are multiple AOs in a molecule, the multiple AOs may be the same or different. and tertiary amines represented by the following formulae (2-1) to (2-3): 【Chemistry 4】 [In the above formula (2-1), R ２１ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R ２２ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms or an alkyl group having 1 to 3 carbon atoms; R ２３ represents an alkyl group having 1 to 3 carbon atoms; R ２４ represents an alkyl group having 1 to 3 carbon atoms or a benzyl group, and in the formula (2-2), R ２５ represents an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R ２６ is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, -(AO) ｍ２３ represents —H or an alkyl group having 1 to 3 carbon atoms; R ２７ is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) ｍ２４ m21, m23 and m24 each independently represent a number from 1 to 4; when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different; ２８ is an alkyl group having 1 to 3 carbon atoms, a benzyl group, or -(AO) ｍ２５ represents —H, R ２９ and R ３０ Each independently represents -CH ３ , -(AO) ｍ２６ -H, -(AO) ｍ２７ -C(=O)-R ３１ or an aliphatic hydrocarbon group having 8 to 26 carbon atoms; R ３１ represents an aliphatic hydrocarbon group having 11 to 25 carbon atoms, m22 and m25 to m27 each independently represent a number from 1 to 20, when a plurality of AOs are present in a molecule, the plurality of AOs may be the same or different, in formulas (2-2) and (2-3), AO represents an alkyleneoxy group having 2 to 4 carbon atoms, and in formulas (2-1) to (2-3), X represents a counter ion, p represents the valence of the counter ion X, and is an integer from 1 to 3. At least one amine-based additive component selected from the group consisting of quaternary ammonium compounds represented by the formula: A paper softener comprising:

5. The paper softener according to claim 4, further comprising at least one polyamine selected from the group consisting of polydiallyldimethylammonium salts, polyvinylamines, polyethyleneimines, and epichlorohydrin polycondensates of dimethylamine, polyallylamine, polyallylamine sulfone copolymers, polyamine polyamides, and polyamine-epichlorohydrin copolymers.

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