JP2006307403A - Softening agent for paper and method for producing paper by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a softening agent for paper, capable of imparting excellent flexibility and sizing ability to the paper. <P>SOLUTION: The softening agent for the paper comprises a condensate of an amidoamine compound with urea. The condensate is obtained by reacting two kinds of amidoamine compounds having different rates of amidation with the urea in an amount of 0.1-1 mol eq. based on 1 mol amino group of the amidoamine compounds. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a paper softener and a method for producing paper using the same. More specifically, the present invention relates to a paper softening agent capable of imparting excellent flexibility and size to paper and a method for producing paper using the same.

  With the progress of visualization and colorization of printed matter, there is a demand for a printing paper having higher flexibility from the viewpoint of improving printability. In addition, more flexible printing paper is required from the viewpoint of easy turning of pages of printed materials such as books.

  As a paper softener, in the field of sanitary paper such as tissue paper, a paper softener containing lanolin and derivatives thereof (for example, Patent Document 1), a di-long chain alkyl type quaternary ammonium salt has been used. A paper softener contained therein (for example, Patent Document 2) is known.

  However, when these softening agents for paper are used for printing paper, there is a problem that the size property is not sufficiently exhibited. For example, in the papermaking of printing paper, sizing is usually obtained by adding an emulsion of a sizing agent such as rosin, alkenyl succinic anhydride, alkyl ketene dimer, etc. Inhibits the effect.

  Furthermore, amino ammonium salts (for example, Patent Document 3), ester compounds of polyhydric alcohols and higher unsaturated fatty acids (for example, Patent Document 4) and the like have been proposed as softening agents for printing paper. Although some degree of flexibility can be obtained, the size is not sufficient.

  When sufficient size characteristics cannot be obtained on a printing paper, there arises a problem that a beautiful finish of printed matter cannot be obtained. Furthermore, in the paper manufacturing process, problems such as wrinkles and penetration of the coating liquid may occur in the coating of starch aqueous solution, filler dispersion, sizing agent emulsion, and the like.

Therefore, a paper softener capable of providing paper excellent in flexibility and size, particularly printing paper, is demanded.
JP-A-53-147803 JP 63-165597 A JP 2001-355197 A JP 2002-155494 A

  An object of the present invention is to provide a paper softener capable of imparting excellent flexibility and size properties to paper. Another object of the present invention is to provide a method for efficiently producing paper using the paper softener.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have obtained a condensation obtained by reacting two kinds of amidoamine compounds having a specific molar ratio and different amidation rates with urea at a specific ratio. It was found that a paper having good flexibility and sufficient size can be obtained by using the product. Furthermore, a paper manufacturing method has been obtained using this paper softener. The present invention has been completed based on such findings.

The paper softener of the present invention comprises a condensate of an amidoamine compound and urea, and the condensate has a molar ratio of the amidoamine compound (a) to the amidoamine compound (b) of 30:70 to 90:10. The amidoamine compound is obtained by reacting 0.1 to 1 molar equivalent of urea with respect to 1 mol of the amino group of the amidoamine compound, and the amidoamine compound (a) is represented by the following formula (1):
R ¹ NH— (R ² —NH) _m —R ³ (1)
(R ¹ and R ³ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 1 to 4 carbon atoms, and m is 2 to 4). A polyamine compound (1) and a carboxylic acid having 10 to 24 carbon atoms and containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms with respect to 1 mol of an amino group of the polyamine compound (1) , And the amide amine compound (b) is obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.6 to 0.85 molar equivalent, and the following formula (2):
_{^{R 4 NH- (R 5 -NH)}} n -R 6 (2)
(R ⁴ and R ⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ⁵ is an alkylene group having 1 to 4 carbon atoms, and n is 2 to 4) A polyamine compound (2) and a carboxylic acid having 10 to 24 carbon atoms and containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms with respect to 1 mol of the amino group of the polyamine compound (2) , And obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.2 to 0.45 molar equivalent.

The paper softener of the present invention also comprises a condensate of an amidoamine compound and urea and an alkyl ketene dimer composed of a saturated or unsaturated carboxylic acid having 12 to 24 carbon atoms, and the condensate and the alkyl ketene dimer. An amidoamine compound having a mass ratio of 50:50 to 99: 1, and wherein the condensate is a molar ratio of the amidoamine compound (a) to the amidoamine compound (b) of 30:70 to 90:10; It is obtained by reacting 0.1 to 1 molar equivalent of urea with respect to 1 mol of amino group, and the amidoamine compound (a) is represented by the following formula (1):
R ¹ NH— (R ² —NH) _m —R ³ (1)
(R ¹ and R ³ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 1 to 4 carbon atoms, and m is 2 to 4). A polyamine compound (1) and a carboxylic acid having 10 to 24 carbon atoms and containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms with respect to 1 mol of an amino group of the polyamine compound (1) The amide amine compound (b) is obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.6 to 0.85 molar equivalent.
_{^{R 4 NH- (R 5 -NH)}} n -R 6 (2)
(R ⁴ and R ⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ⁵ is an alkylene group having 1 to 4 carbon atoms, and n is 2 to 4) A polyamine compound (2) and a carboxylic acid having 10 to 24 carbon atoms and containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms with respect to 1 mol of the amino group of the polyamine compound (2) , And obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.2 to 0.45 molar equivalent.

  The paper manufacturing method of the present invention includes a step of adding the paper softener to 100 parts by mass of the pulp so that the amount of the condensate is 0.03 to 8 parts by mass.

  The paper softener of the present invention comprises a condensate obtained by reacting two kinds of amidoamine compounds having different amidation ratios in a specific molar ratio with urea at a specific ratio. The paper softener of the present invention can impart excellent flexibility and size to paper. Therefore, by using this paper softener, paper having excellent flexibility and size can be obtained.

  The paper softener of the present invention comprises a condensate of an amidoamine compound and urea. Or the softener for paper of this invention consists of the condensate and alkyl ketene dimer of the said amidoamine compound and urea. Hereinafter, each component, a paper softener, and a paper manufacturing method using the same will be described.

(Condensate)
The condensate can be obtained by reacting two kinds of amidoamine compounds having different amidation rates with urea at a specific ratio. In the present invention, one of the features is that two types of amidoamine compounds (a) and (b) having different amidation rates are used in a specific molar ratio.

(1) Amidoamine compound In the amideamine compound as a raw material of the condensate, as described above, two types of amideamine compounds having different amidation rates, that is, the amideamine compound (a) having a relatively high amidation rate and the amideamine An amidoamine compound (b) having a lower amidation rate than the compound (a) is used. In this specification, an amidation rate means the molar equivalent of the carboxyl group of carboxylic acid with respect to 1 mol of amino groups of the polyamine compound used for manufacture of an amidoamine compound. Therefore, this amidation rate can be adjusted, for example, by the ratio of the polyamine compound and the carboxylic acid. Hereinafter, the amidoamine compounds (a) and (b) will be described first, and then the ratio of the amidoamine compounds (a) and (b) will be described.

(1-1) Amidoamine compound (a)
The polyamine compound (1) used for the production of the amidoamine compound (a) has the following general formula (1):
R ¹ NH— (R ² —NH) _m —R ³ (1)
(R ¹ and R ³ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 1 to 4 carbon atoms, and m is 2 to 4). .

In the general formula (1), examples of the alkyl group having 1 to 3 carbon atoms of R ¹ and R ³ include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

In the general formula (1), examples of the alkylene group having 1 to 4 carbon atoms of R ² include a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, and a butylene group.

  The carboxylic acid used for the production of the amidoamine compound (a) is a carboxylic acid having 10 to 24 carbon atoms containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms. Carbon number of the carboxylic acid is preferably 12-18. When the number of carbon atoms is less than 10, the resulting softening agent for paper has insufficient flexibility and size improvement effects. When the number of carbon atoms exceeds 24, the paper softener using such an amidoamine compound has the effect of imparting flexibility and size to the paper, but the melting point of the resulting amidoamine compound is increased, and the paper softener It may be difficult to handle the agent. When the content of the saturated carboxylic acid is less than 35% by mass, the effect of improving the size of the obtained paper softener becomes insufficient.

  Examples of the carboxylic acid having 10 to 24 carbon atoms include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, tetracosanoic acid and the like; palmitoleic acid, oleic acid, linoleic acid, Examples thereof include unsaturated carboxylic acids such as linolenic acid and erucic acid.

  In the amidoamine compound (a), the carboxyl group of the carboxylic acid is 0.6 to 0.85 with respect to 1 mol of the amino group of the amine compound (1). It is obtained by reacting at a molar equivalent, preferably 0.6 to 0.75 molar equivalent. When the amount is less than 0.6 molar equivalent, the effect of improving the flexibility and size of the obtained paper softener is insufficient. When it exceeds 0.85 molar equivalent, the effect of improving the flexibility of the obtained paper softener becomes insufficient. The reaction for obtaining the amidoamine compound (a) is performed, for example, by charging the polyamine compound (1) and the carboxylic acid in a reactor, and heating the mixture with stirring in a nitrogen atmosphere to remove generated water. While holding for several hours.

(1-2) Amidoamine compound (b)
The polyamine compound (2) used for the production of the amidoamine compound (b) has the following general formula (2):
_{^{R 4 NH- (R 5 -NH)}} n -R 6 (2)
(R ⁴ and R ⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ⁵ is an alkylene group having 1 to 4 carbon atoms, and n is 2 to 4) .

In the general formula (2), for the alkyl group having 1 to 3 carbon atoms of R ⁴ and R ⁶ , the same alkyl group as R ¹ and R ^{3 in} the formula (1) can be used. For the alkylene group having 1 to 4 carbon atoms in R ⁵ , the same alkylene group as R ^{2 in the} above formula (1) can be used.

  The carboxylic acid used for the production of the amidoamine compound (b) is a carboxylic acid having 10 to 24 carbon atoms containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms. Carbon number of the carboxylic acid is preferably 12-18. When the number of carbon atoms is less than 10, the resulting softening agent for paper has insufficient flexibility and size improvement effects. When the number of carbon atoms exceeds 24, the paper softener using such an amidoamine compound has the effect of imparting flexibility and size to the paper, but the melting point of the resulting amidoamine compound is increased, and the paper softener It may be difficult to handle the agent. When the content of the saturated carboxylic acid is less than 35% by mass, the effect of improving the size of the obtained paper softener becomes insufficient. Examples of the carboxylic acid having 10 to 24 carbon atoms include carboxylic acids used in the amidoamine compound (a).

  In the amidoamine compound (b), the carboxyl group of the carboxylic acid is 0.2 to 0.45 with respect to 1 mol of the amino group of the polyamine compound (2). It is obtained by reacting at a molar equivalent, preferably 0.25 to 0.4 molar equivalent. When the amount is less than 0.2 molar equivalent, the effect of improving the flexibility and size of the obtained paper softener is insufficient. When it exceeds 0.45 molar equivalent, the effect of improving the flexibility of the obtained paper softener becomes insufficient. The reaction for obtaining the amidoamine compound (b) can be performed, for example, by the same method as the amidoamine compound (a).

  The amidoamine compound has a molar ratio of the amidoamine compound (a) to the amidoamine compound (b) of 30:70 to 90:10, preferably 35:65 to 70:30. When the molar ratio is out of the range of 30:70 to 90:10, the effect of improving the flexibility of the obtained paper softener becomes insufficient.

(2) Urea Commercially available products can be used as appropriate for urea, which is a raw material for the condensate.

(3) Condensation reaction (Preparation of condensate)
The condensate is obtained by reacting the amidoamine compound with 0.1 to 1 molar equivalent, preferably 0.3 to 0.7 molar equivalent, of urea with respect to 1 mol of the amino group of the amidoamine compound. When urea is less than 0.1 molar equivalent, the effect of improving the size of the resulting paper softener is insufficient. When the urea exceeds 1 molar equivalent, the effect of improving the flexibility and size according to the amount used is I can't get it. This condensate is prepared by a normal condensation reaction.

  The condensate is preferably made into a salt by reacting an unreacted amine moiety with an inorganic acid or an organic acid in order to facilitate the preparation of a paper softener dispersion. Examples of the inorganic acid include hydrochloric acid, sulfuric acid, carbonic acid, nitric acid, phosphoric acid and the like. Organic acids include formic acid, acetic acid, propionic acid, octylic acid, butyric acid, oxalic acid, malonic acid, itaconic acid, adipic acid, succinic acid, sebacic acid, citric acid, hydroxybenzoic acid, malic acid, hydroxymalonic acid, lactic acid , Gluconic acid, salicylic acid, hydroxyvaleric acid, aspartic acid, glutamic acid, taurine, sulfamic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and the like. Of these, organic acids are preferable, and formic acid, acetic acid, and propionic acid are particularly preferable. You may perform this reaction by an acid, when preparing a paper softening agent.

(Alkyl ketene dimer)
Alkyl ketene dimers are used to impart additional sizing (water resistance) to the paper. The alkyl ketene dimer can be obtained, for example, by converting a carboxylic acid to a carboxylic acid chloride by a phosphorus method or a phosgene method, and then dehydrochlorinating with a tertiary amine as a catalyst.

  Examples of the carboxylic acid used as the raw material for the alkyl ketene dimer include saturated or unsaturated carboxylic acids having 12 to 24 carbon atoms, preferably 14 to 18 carbon atoms. When the number of carbon atoms of the carboxylic acid is less than 12, it may not be possible to expect a further improvement in size, and when it exceeds 24, handling of the resulting paper softener may be difficult.

  Examples of the saturated carboxylic acid include lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, and tetracosanoic acid. Examples of the unsaturated carboxylic acid include palmitoleic acid, oleic acid, erucic acid and the like. These carboxylic acids may be used alone or in combination of two or more.

(Softener for paper)
The paper softener of the present invention comprises the condensate. Or it consists of the said condensate and alkyl ketene dimer.

  When the paper softener of the present invention comprises a condensate and an alkyl ketene dimer, the mass ratio of the condensate to the alkyl ketene dimer is 50:50 to 99: 1, preferably 70:30 to 95: 5. is there.

  The paper softener of the present invention is preferably used as a dispersion liquid dispersed in a solvent such as water. The dispersion is prepared using an emulsifier such as a high-pressure homogenizer after mixing with additives such as a dispersant and protective colloid.

(Paper manufacturing method)
The paper manufacturing method of the present invention is characterized in that the paper softener is used in paper manufacture. The softener for paper is added so that the amount of the condensate is 0.03 to 8 parts by mass, preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the pulp. When the amount of the condensate is less than 0.03 parts by mass, sufficient flexibility and size cannot be imparted to the paper. When the amount of the condensate exceeds 8 parts by mass, the effect of improving the flexibility and the sizing property corresponding to the amount used cannot be obtained, but rather the cost of the paper is increased, which is economically disadvantageous.

  Examples of the above pulp (raw pulp) include chemical pulp (exposed or unexposed kraft pulp of softwood or hardwood), mechanical pulp (such as ground pulp, thermomechanical pulp, chemithermomechanical pulp), deinked pulp (newspaper, magazine) Used paper). These can be used alone or in combination.

  The paper softener of the present invention can be used in various processes in the production of paper. That is, it can be added to the papermaking system at any stage of the papermaking process (internal addition method), and further applied to the surface of the pulp sheet obtained by the papermaking process (external addition method). For example, an internal addition method that is added to the pulp slurry in the mixing chest, machine chest, seed box, etc. in the papermaking process, or a size press, gate roll, spray, etc. that is applied to the pulp sheet surface obtained by papermaking The addition method is adopted.

  In particular, the internal addition method is preferably employed. For example, paper is obtained by adding the paper additive to a mixture containing pulp and water (for example, pulp slurry) and making paper by a usual method.

  In the paper manufacturing method of the present invention, paper machines such as a long net paper machine, a twin wire machine, and a Yankee machine, which are generally used for paper making, can be used.

  Examples of the paper manufactured by the paper manufacturing method of the present invention include newsprint paper, printing paper, recording paper, packaging paper, paperboard, liner, corrugated paper such as a core, wallpaper, base paper, backing paper, and the like. Examples include sanitary paper such as paper products, toilet paper, and tissue paper. In particular, printing paper is suitable.

  The present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Hereinafter, the amidoamine compound (a) is referred to as amidoamine compound a, and the amidoamine compound (b) is referred to as amidoamine compound b.

(Synthesis Example 1.1: Synthesis of Amidoamine Compound a)
In a 500 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube, 51.5 g (0.5 mol) of a polyamine compound (diethylenetriamine) shown in Table 1 and 287.5 g of stearic acid (1 Moles), the temperature was raised to 180 to 190 ° C. with stirring in a nitrogen atmosphere, and the reaction was carried out for 3 hours while removing the generated water from the system. The amidoamine compound a-1 having a total amine value of 89.9 Got.

(Synthesis Examples 1.2 to 1.5)
Amidoamine compounds a-2 to a-5 were obtained in the same manner as in Synthesis Example 1.1 except that the polyamine compounds and carboxylic acids shown in Table 1 were used in the proportions shown in Table 1.

(Synthesis Example 1.6: Synthesis of Amidoamine Compound b)
In the same manner as in Synthesis Example 1.1 except that 73.0 g (0.5 mol) of polyamine compound (triethylenetetramine) and 258.8 g (0.9 mol) of stearic acid shown in Table 1 were used, Amidoamine compound b-1 having an amine value of 197.4 was obtained.

(Synthesis Examples 1.7 to 1.10)
Amidoamine compounds b-2 to b-5 were obtained in the same manner as in Synthesis Example 1.1 except that the polyamine compounds and carboxylic acids shown in Table 1 were used in the proportions shown in Table 1.

(Comparative Synthesis Examples 1.1 to 1.4)
Amidoamine compounds c-1 to c-4 were obtained in the same manner as in Synthesis Example 1.1, except that the polyamine compounds and carboxylic acids shown in Table 1 were used in the proportions shown in Table 1.

  Various amidoamine compounds as shown in Table 1 were obtained. Among these, the amidoamine compounds of Comparative Synthesis Examples 1.1 to 1.4 do not satisfy any of the conditions of the amidoamine compounds a and b which are raw materials of the condensate used in the present invention. That is, the amidoamine compound c-1 of Comparative Synthesis Example 1 has a small number of carbon atoms in the carboxylic acid. Amidoamine compound c-2 of Comparative Synthesis Example 2 has a high ratio of carboxyl group to amino group in the amidoamine compound. The amidoamine compound c-3 of Comparative Synthesis Example 3 does not contain a saturated carboxylic acid in the carboxylic acid. And the amidoamine compound c-4 of the comparative synthesis example 4 has a low ratio of the carboxyl group with respect to the amino group in an amidoamine compound.

(Synthesis Example 2.1: Synthesis of condensate)
In a 500 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet, 202.8 g (0.33 mol) of the amidoamine compound a-1 obtained in the above synthesis example, and the amidoamine compound 112.6 g (0.18 mol) of b-1 was charged and heated to 110 to 120 ° C. with stirring in a nitrogen atmosphere. The amine value of this mixed amidoamine compound was 127.6. Subsequently, 25.8 g (0.43 mol) of urea was further added, and the mixture was stirred at 160 ° C. to 170 ° C. in a nitrogen atmosphere, and reacted for 1 hour while removing ammonia out of the system. The total amine value was 22.3. The condensate A-1 was obtained. The results are shown in Table 2.

(Synthesis Examples 2.2 to 2.5)
Condensates A-2 to A-5 were obtained in the same manner as in Synthesis Example 2.1 except that amidoamine compounds a and b and urea described in Table 2 were used. The results are shown in Table 2.

(Comparative Synthesis Examples 2.1 to 2.7)
Condensates A-6 to A-12 were obtained in the same manner as in Synthesis Example 2.1 except that the amidoamine compounds and urea listed in Table 2 were used. The results are shown in Table 2.

  Various condensates as shown in Table 2 were obtained. Among these, the condensates of Comparative Synthesis Examples 2.1 to 2.7 do not satisfy the conditions of the condensate used in the present invention. That is, the condensates of Comparative Synthesis Examples 2.1 to 2.4 do not contain any of the amidoamine compounds a and b. In the condensates of Comparative Synthesis Examples 2.5 and 2.6, the ratio (molar ratio) of amidoamine compounds a and b is not appropriate. In the condensate of Comparative Synthesis Example 2.7, the ratio of urea to the amino group of the amidoamine compound is small.

(Example 1: Preparation of paper softener dispersion and evaluation thereof)
1. Preparation of dispersion liquid for paper softener In a 1 L beaker, 628.2 g of ion-exchange water, 70 g of condensate A-1 (component A) obtained in Synthesis Example 2.1, and 1.8 g of acetic acid (condensate) Equivalent to 1.05 molar equivalents relative to the amine value), and the temperature was raised to 80 ° C. Subsequently, it processed for 5 minutes at 5000 rpm using a homomixer (made by Tokushu Kika Kogyo Co., Ltd.), and also 2 at 40 MPa using a pressure emulsifier (made by Manton Gorin, APV GAULIN, INC.). The paper softening agent dispersion was prepared (referred to as Dispersion I). This dispersion I contains 10% by mass of the condensate.

2. Evaluation of paper softener Using the paper softener dispersion I obtained above, a handsheet was produced as follows, and the flexibility (bending stiffness and capacity) and size of the handsheet obtained Sexuality was evaluated.

2-1. Manufacture of handsheets LBKP (hardwood bleached pulp) having a freeness of 400 mL was disaggregated using a disaggregator (manufactured by Kumagaya Riken Co., Ltd.) to prepare a pulp slurry containing 1% by mass of pulp. 100 g of this pulp slurry (1 g of pulp) is put in a 200 mL capacity beaker, 0.05 g of the above-mentioned paper softener dispersion I (condensate amount is 0.5 parts by mass with respect to 100 parts by mass of pulp) and cationized Add 1.0 g of paste (1.0 part by mass of cationized starch to 100 parts by mass of pulp) obtained by diluting starch (ACE K-10, manufactured by Oji Cornstarch Co., Ltd.) with water to 1% by mass, The mixture was stirred for 1 minute at 250 rpm with a turbine blade having a diameter of 4.5 cm. Then, after making paper with a TAPPI standard sheet machine (manufactured by Yasuda Seiki Co., Ltd.) and using a hydraulic press machine (manufactured by Yasuda Seiki Co., Ltd.) for 5 minutes at 0.35 MPa, a drum dryer (manufactured by Yasuda Seiki Co., Ltd.) ) Was dried at 105 ° C. for 2 minutes to produce a handsheet having a basis weight of about 50 g / m ² . The handsheet was further stored for 17 hours in a constant temperature and humidity chamber at a temperature of 23 ° C. and a humidity of 50% to adjust the humidity.

2-2. Evaluation The flexibility (bending stiffness and capacity) and size of the obtained handsheet were evaluated by the following methods. The results are shown in Table 3.

(1) Flexibility evaluation 1 (bending stiffness)
Using a pure bending tester (KES-FB2, manufactured by Kato Tech Co., Ltd.), the bending stiffness in the vertical direction and the horizontal direction of the handsheet was measured to obtain an average value. The average value obtained was evaluated according to the following criteria.

(Evaluation criteria)
Flexural rigidity is less than 4.41 × 10 ⁻⁵ N · m ² / m: Good flexibility (◯)
Flexural rigidity is 4.41 × 10 ⁻⁵ N · m ² / m or more: Insufficient flexibility (×)

(2) Flexibility evaluation 2 (capacity)
The basis weight of the handsheet was measured according to JIS P8124. Further, the thickness was measured using a JIS paper pressure measuring device MEI-10 (manufactured by Citizen Watch Co., Ltd.). The sheet capacity was obtained from the following equation using the obtained basis weight and thickness measurement values, and evaluated according to the following criteria.
Sheet capacity (cm ³ / g) = thickness (μm) / basis weight (g / m ² )

(Evaluation criteria)
When the sheet capacity is 1.60 cm ³ / g or more: Good flexibility (◯)
When the sheet capacity is less than 1.60 cm ³ / g: flexibility is insufficient (×)

(3) Evaluation of sizing properties In accordance with JIS P8122, the degree of sizing of the handsheets was measured, and the sizing properties were evaluated as follows. If it is ◎ or ○, there is no practical problem.

(Evaluation criteria)
Sizing degree is 30 seconds or more: Size is very good (◎)
Sizing degree is 20 seconds or more and less than 30 seconds: Good sizing (○)
Size is less than 20 seconds: Insufficient size (×)

(Example 2)
A dispersion II was obtained in the same manner as in Example 1 except that the condensate A-2 was used. A handsheet was produced and evaluated in the same manner as in Example 1 except that the dispersion II was used so as to have the addition amount shown in Table 3. The results are also shown in Table 3.

(Example 3)
In a 1 L beaker, 612.3 g of ion-exchanged water, 61.0 g of condensate A-3 (component A) obtained in Synthesis Example 2.3, alkyl ketene dimer (component B) using stearic acid as a starting fatty acid 7. 0 g, 17.5 g of a 10% by weight cationic starch (HI-CAT260, manufactured by Roquette Italy SpA) previously treated with sodium persulfate, and 2.2 g of acetic acid (1. 1 with respect to the amine value of the condensate). Equivalent to 05 molar equivalents) and heated to 80 ° C. Subsequently, it processed for 5 minutes at 5000 rpm using a homomixer (made by Tokushu Kika Kogyo Co., Ltd.), and also 2 at 40 MPa using a pressure emulsifier (made by Manton Gorin, APV GAULIN, INC.). The paper softening agent dispersion liquid was prepared by carrying out the round treatment (referred to as dispersion liquid III). This dispersion III contains about 10% by mass of the condensate and the alkyl ketene dimer in total. A handsheet was produced and evaluated in the same manner as Example 1 using Dispersion III. The results are also shown in Table 3.

(Examples 4 and 5)
Dispersions IV and V were obtained in the same manner as in Example 3, except that the condensate (component A), alkyl ketene dimer (component B), and acid described in Table 3 were used. A handsheet was produced and evaluated in the same manner as Example 3 using each dispersion. The results are also shown in Table 3.

(Comparative Examples 1-8)
As shown in Table 3, using a condensate (component A), an alkyl ketene dimer (component B), and an acid, paper softener dispersions VI to XIII were prepared. When no alkyl ketene dimer was included, the same method as in Example 1 was used, and when an alkyl ketene dimer was included, the same method as in Example 3 was used. A handsheet was produced and evaluated in the same manner as in Example 1 using each dispersion. The results are also shown in Table 3.

  From the results of Table 3, it can be seen that when the paper softener dispersions I to V of Examples are used, paper (handsheet) having excellent flexibility and sizing properties can be obtained. In particular, it can be seen that when the paper softener dispersions III to V containing the condensate of Examples 3 to 5 and the alkyl ketene dimer are used, paper having more excellent size properties can be obtained.

  In contrast, the paper softener dispersions VI to XIII of Comparative Examples do not contain a condensate or the condensate does not satisfy the conditions of the present application. It was inadequate in any respect. That is, since the dispersion VI of Comparative Example 1 does not contain a condensate, the flexibility of the paper was insufficient. In the dispersion VII of Comparative Example 2, in the condensate A-6, the amidoamine compound a is not used, and instead the amidoamine compound c-1 having a small carboxylic acid carbon number is used. Insufficient flexibility and size. In the dispersion VIII of Comparative Example 3, in the condensate A-7, the amidoamine compound a is not used, and instead, the amidoamine compound c-2 in which the molar ratio of the carboxylic acid to the polyamine compound is not appropriate is used. For this reason, the flexibility of the resulting paper was insufficient. In the dispersion IX of Comparative Example 4, in the condensate A-8, the amidoamine compound b is not used, and instead the amidoamine compound c-3 not containing a saturated carboxylic acid is used. The size was insufficient. In the dispersion X of Comparative Example 5, in the condensate A-9, the amidoamine compound b is not used, and instead, the amidoamine compound c-4 in which the molar ratio of the carboxylic acid to the polyamine compound is not appropriate is used. For this reason, the flexibility and size of the obtained paper were insufficient. In the dispersion XI of Comparative Example 6, since the ratio of the amidoamine compounds a and b in the condensate A-10 was not appropriate, the flexibility of the obtained paper was insufficient. In the dispersion XII of Comparative Example 7, in the condensate A-11, since the ratio (molar ratio) between the amidoamine compounds a and b was not appropriate, the flexibility of the obtained paper was insufficient. In the dispersion XIII of Comparative Example 8, in the condensate A-12, since the ratio of urea to the amino group of the amidoamine compound was small, the resulting paper had insufficient size properties.

  ADVANTAGE OF THE INVENTION According to this invention, the softener for paper which can provide the softness | flexibility and size property which were excellent in paper is provided. When this softening agent for paper is used, paper having excellent flexibility and size, particularly printing paper can be obtained. The obtained paper is widely used as paper in various fields such as bookbinding paper, newsprint paper, printing / information paper, cardboard base paper, and paperboard.

Claims (3)

A paper softener comprising a condensate of an amidoamine compound and urea,
The condensate has a molar ratio of the amidoamine compound (a) and the amidoamine compound (b) of 30:70 to 90:10, and 0.1 to 0.1 mol of the amino group of the amidoamine compound. Obtained by reacting with 1 molar equivalent of urea,
The amidoamine compound (a) is represented by the following formula (1):
R ¹ NH— (R ² —NH) _m —R ³ (1)
(R ¹ and R ³ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 1 to 4 carbon atoms, and m is 2 to 4). A polyamine compound (1);
A carboxylic acid having 10 to 24 carbon atoms containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms,
The polyamine compound (1) is obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.6 to 0.85 mole equivalent to 1 mole of the amino group, and the amidoamine compound (b) However, the following formula (2):
_{^{R 4 NH- (R 5 -NH)}} n -R 6 (2)
(R ⁴ and R ⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ⁵ is an alkylene group having 1 to 4 carbon atoms, and n is 2 to 4) A polyamine compound (2);
A carboxylic acid having 10 to 24 carbon atoms containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms,
It is obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.2 to 0.45 molar equivalent to 1 mol of the amino group of the polyamine compound (2).
Softener for paper. A paper softener comprising a condensate of an amidoamine compound and urea and an alkyl ketene dimer comprising a saturated or unsaturated carboxylic acid having 12 to 24 carbon atoms,
The mass ratio of the condensate to the alkyl ketene dimer is 50:50 to 99: 1;
The condensate has a molar ratio of the amidoamine compound (a) and the amidoamine compound (b) of 30:70 to 90:10, and 0.1 to 0.1 mol of the amino group of the amidoamine compound. Obtained by reacting with 1 molar equivalent of urea,
The amidoamine compound (a) is represented by the following formula (1):
R ¹ NH— (R ² —NH) _m —R ³ (1)
(R ¹ and R ³ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 1 to 4 carbon atoms, and m is 2 to 4). A polyamine compound (1);
A carboxylic acid having 10 to 24 carbon atoms containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms,
The polyamine compound (1) is obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.6 to 0.85 mole equivalent to 1 mole of the amino group, and the amidoamine compound (b) However, the following formula (2):
_{^{R 4 NH- (R 5 -NH)}} n -R 6 (2)
(R ⁴ and R ⁶ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ⁵ is an alkylene group having 1 to 4 carbon atoms, and n is 2 to 4) A polyamine compound (2);
A carboxylic acid having 10 to 24 carbon atoms containing 35% by mass or more of a saturated carboxylic acid having 10 to 24 carbon atoms,
It is obtained by reacting at a ratio such that the carboxyl group of the carboxylic acid is 0.2 to 0.45 molar equivalent to 1 mol of the amino group of the polyamine compound (2).
Softener for paper.   The paper manufacturing method including the process of adding the softening agent for paper of Claim 1 or 2 with respect to 100 mass parts of pulp so that the quantity of the said condensate may be 0.03-8 mass parts. .