JP2007270400A - Paper softener - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper softener which can give soft and smooth paper without deteriorating the strength of the paper. <P>SOLUTION: This paper softener comprises a specific compound (a) and a modified silicone (b) having a functional group equivalent of 10 to 100 mgKOH/g in a mass ratio of the compound (a) to the siclicone (b) of 85/15 to 99.9/0.1. The modified silicone (b) is one or more kind selected from the group consisting of amino-modified silicones, carboxyl-modified silicones and polyether-modified silicones. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a softening agent for paper. More specifically, the present invention relates to a paper softener that can impart flexibility and paper surface smoothness to paper without reducing paper strength.

  In recent years, in the paper manufacturing industry, the visualization and colorization of printed matter has progressed, and more flexible printing paper is required from the viewpoint of improving printability. On the other hand, in recent years, demands for improving the quality of paper products are increasing from consumers. In particular, printing paper is required to have not only flexibility but also smoothness in terms of the flexibility of paper that does not close naturally when a book is opened and the ease of turning pages. Further, in household paper such as tissue paper and toilet paper, there is a strong demand for imparting softness (flexibility) and smoothness to the paper in order to improve the feeling of use. Many softeners have been developed so far. For example, it is known that polyethylene glycol, urea and the like are effective in improving the flexibility of paper. However, even if these are used in an actual papermaking process, a sufficient flexibility effect cannot be obtained. In addition, a method using a quaternary ammonium salt or the like has been developed in order to enhance the feel of paper products. However, this method is effective in improving flexibility, but is not sufficient in improving the smoothness of the paper surface. Furthermore, there is a problem that paper strength is reduced.

  So far, a method of using a densification chemical consisting of an alkylene oxide adduct of a higher alcohol and a quaternary ammonium salt (for example, Patent Document 1), an esterified product of an alkylene oxide adduct of a polyalkyleneimine and a higher fatty acid It is known to improve flexibility while suppressing a decrease in paper strength of a paper product by using a method (for example, Patent Document 2) that uses the. However, with these methods, it is difficult to improve the smoothness of the paper surface. Moreover, although the method (for example, patent document 3 and 4) etc. which use a silicone type compound can improve the smoothness of paper products, it is difficult to improve a softness | flexibility.

Against this background, there is a demand for a softening agent that improves the flexibility without reducing the paper strength of the paper product and further improves the smoothness of the paper surface.
JP 2001-271292 A JP 2005-82949 A Japanese Patent Laid-Open No. 3-900 Japanese National Patent Publication No. 9-509989

  An object of the present invention is to provide a softener for paper that can obtain a soft and smooth paper without reducing paper strength.

  As a result of intensive studies to solve the above problems, the present inventors have achieved a paper that achieves the above object by combining a specific compound (a) and a specific modified silicone (b) at a specific mass ratio. It has been found that a softening agent can be obtained. The present invention has been completed based on such findings.

  The paper softener of the present invention is a paper softener comprising a specific compound (a) and a modified silicone (b) having a functional group equivalent of 10 to 100 mgKOH / g, wherein the compound (a) is: The following general formula (1):

(A is the residue of a dicarboxylic acid is a ^{C4-12, R 1, R 2, R} 5, and ^{R 6} are each an alkyl group having 1 to 4 carbon atoms, and ^{R 3} and ^{R 4} Are each an alkylene group having 2 to 4 carbon atoms), and the modified silicone (b) is selected from the group consisting of amino-modified silicone, carboxyl-modified silicone, and polyether-modified silicone. And the mass ratio of the compound (a) to the modified silicone (b) is 85/15 to 99.9 / 0.1.

  By using the paper softener of the present invention, it is possible to obtain a paper excellent in flexibility and paper surface smoothness without reducing paper strength.

  The paper softener of the present invention comprises a compound (a) and a modified silicone (b). Hereinafter, each component and the softening agent for paper will be sequentially described.

(Compound (a): component a)
The compound (a) used in the present invention has the following general formula (1):

(A is a residue of a dicarboxylic acid having 4 to 12 carbon atoms, R ¹ , R ² , R ⁵ , and R ⁶ are each an alkyl group having 1 to 4 carbon atoms, and R ³ and R ⁴ Are each an alkylene group having 2 to 4 carbon atoms.)

  In the general formula (1), A is a residue of a dicarboxylic acid having 4 to 12 carbon atoms. Examples of such a dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, Azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. Preferred is a dicarboxylic acid having 6 to 10 carbon atoms. When the number of carbon atoms exceeds 12, the paper softener comprising such a compound (a) imparts flexibility to paper, but the resulting compound (a) has a high melting point and is difficult to handle. There is.

In the general formula (1), R ¹ , R ² , R ⁵ , and R ⁶ having an alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. Etc. A methyl group and an ethyl group are preferable. When the number of carbon atoms exceeds 4, the paper softener obtained from such a compound (a) imparts flexibility to the paper, but the resulting compound (a) has a high melting point and is difficult to handle. There is a case.

In the general formula (1), examples of the alkylene group having 2 to 4 carbon atoms of R ³ and R ⁴ include an ethylene group, a propylene group, and a butylene group. A propylene group is preferred.

  The compound (a) is obtained by reacting a dialkylaminoalkyleneamine with a dicarboxylic acid. This reaction is performed by a normal condensation reaction. The compound (a) can be used as it is, but the handleability is improved by neutralization with an acid. As the acid used in this case, formic acid, acetic acid, glycolic acid, lactic acid, gluconic acid and the like are preferable in consideration of the case where the acid remains on the paper after papermaking. These acids are used in an equivalent amount based on the amine value of the compound (a).

(Modified silicone (b): component b)
The modified silicone (b) used in the present invention is at least one selected from the group consisting of amino-modified silicone, carboxyl-modified silicone, and polyether-modified silicone. Amino-modified silicone is preferred.

  The modified silicone (b) has a functional group equivalent of 10 to 100 mgKOH / g, preferably 40 to 80 mgKOH / g, and is not particularly limited. Commercial products may be used. In this specification, in the case of amino-modified silicone, functional group equivalent means the number of mg of potassium hydroxide equivalent to perchloric acid required to neutralize 1 g of modified silicone. In the case of, this refers to the number of mg of potassium hydroxide required to neutralize 1 g of the modified silicone, and in the case of polyether-modified silicone, it is used to acetylate the hydroxyl groups contained in a 1 g sample of the modified silicone. It refers to the number of mg of potassium hydroxide required to neutralize the acetic acid required. When the functional group equivalent is less than 10 mgKOH / g, the fixability to the pulp is lowered, and the effect of improving the smoothness of the paper surface becomes insufficient. When the functional group equivalent exceeds 100 mgKOH / g, the sticky feeling increases and the effect of improving the smoothness of the paper surface becomes insufficient.

  The modified silicone (b) generally has a molecular weight of 300 to 50,000.

(Softener for paper)
The softener for paper of the present invention comprises the compound (a) (component a) and the modified silicone (component b). Mass ratio (a component) / (b component) of a component and b component is 85 / 15-99.9 / 0.1, Preferably it is 90 / 10-95 / 5. When the mass ratio is less than 85/15, the flexibility improving effect and paper strength may be insufficient. When the mass ratio exceeds 99.9 / 0.1, the effect of improving the smoothness of the paper surface becomes insufficient.

  The use of the softener for paper of the present invention is not particularly limited, but preferred examples of use are given below.

(Usage example of paper softener)
0.03 to 8 parts by mass, preferably 0.1 to 4 parts of the above paper softener (total amount of compound (a) (component a) and modified silicone (component b)) with respect to 100 parts by mass of pulp. Add so that it becomes a mass part. When the amount added is less than 0.03 parts by mass, the resulting paper may have insufficient flexibility. When the amount exceeds 8 parts by mass, the effect of improving the paper flexibility and the paper surface smoothness corresponding to the amount of use cannot be obtained, but rather the cost of the paper is increased, which is economically disadvantageous.

  Examples of the 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, etc.). These can be used alone or in combination.

  In paper manufacture, paper softeners can be utilized in various processes. That is, it can be added to the papermaking system at any stage of the papermaking process (internal addition method), and can also be applied to the surface of the pulp sheet obtained by the papermaking process (external addition method). For example, the internal addition method that is added to the pulp slurry in the mixing chest, machine chest, seed box, etc. in the paper making process, or the size press, gate roll, spray, etc. that are applied to the pulp sheet surface obtained by paper making The addition method is adopted. The softening agent for paper may be used as it is, but it may be used as a dispersion by dispersing it directly in water or using a surfactant generally used as a dispersing agent.

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

  Examples of paper obtained using the paper softener of the present invention include, for example, newsprint paper, printing paper, recording paper, packaging paper, cardboard paper such as paperboard, liners and cores, wallpaper, base paper, backing paper, etc. Paper products, toilet paper, sanitary paper such as 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.

(Synthesis Example 1.1: Preparation of Compound (a))
A 500 ml four-necked flask equipped with a stirrer, condenser, thermometer and nitrogen inlet tube was charged with 161.8 g (0.8 mol) of sebacic acid and 208.3 g (1.6 mol) of diethylaminopropylamine. It is. Next, the temperature was raised to 120 to 130 ° C. with stirring in a nitrogen atmosphere, and the reaction was performed for 15 hours while removing the generated water out of the system to obtain Compound a-1 having a total amine value of 263.

(Synthesis Examples 1.2 to 1.4)
In the same manner as in Synthesis Example 1.1, compounds a-2 to a-4 shown in Table 1 were obtained.

(Comparative Synthesis Example 1.1)
In the same manner as in Synthesis Example 1.1, Compound a′-1 shown in Table 1 was obtained.

(Example 1: Preparation of paper softener and evaluation of paper softener)
1. Preparation of Dispersion of Softener for Paper In a 1 liter beaker, 703.5 g of ion-exchanged water, 73.6 g of compound a-1 and 16.5 g of acetic acid (0. 0 with respect to the amine value of compound a-1). Equivalent to 8 equivalents), and 6.4 g of modified silicone b-1 shown in Table 2 were added, the temperature was raised to 80 ° C., and the mixture was stirred at 5000 rpm for 5 minutes using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). A 10% by mass dispersion of a paper softener was prepared (dispersion I). The paper softener in this dispersion had a mass ratio of compound a-1 to modified silicone of 92/8.

2. Evaluation of Softener for Paper Using the dispersion I obtained above, a handsheet was produced as follows. The obtained handsheet was evaluated for (1) flexibility (bending stiffness), (2) smoothness of the paper surface, and (3) paper strength.

2-1. Preparation 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 amount) was put in a 200 mL capacity beaker, and 0.05 g of the above paper softener dispersion I (paper softener (compound (a) and modified silicone with respect to 100 parts by mass of pulp)) was added. Cation) that was gelatinized by diluting it to 0.1 g (0.1 parts by mass with respect to 100 parts by mass of pulp) and 1% by mass in advance. 1.0 g (1.0 part by mass with respect to 100 parts by mass of pulp) of modified starch (Ace K-100 manufactured by Oji Corn Starch Co., Ltd.) was added. Subsequently, it stirred for 1 minute at 250 rpm with the turbine blade of diameter 4.5cm. After stirring, paper was made with a TAPPI standard sheet machine (manufactured by Yasuda Seiki Co., Ltd.). After paper making, press for 5 minutes at 0.35 MPa using a hydraulic press (manufactured by Yasuda Seiki Co., Ltd.), dry for 2 minutes at 105 ° C. using a drum dryer (manufactured by Yasuda Seiki Co., Ltd.), and basis weight 50 g / m ^2. Three handsheets were manufactured. 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 (1) Evaluation of Flexibility (Bending Stiffness) Using a pure bending tester (KES-FB2, manufactured by Kato Tech Co., Ltd.), the bending stiffness in the longitudinal direction and the lateral direction of the handsheet is measured and averaged. Asked. In addition, it evaluated as follows on the basis of bending rigidity less than 4.41 * 10 < ^-5 > N * m < ² > / m which 7 or more evaluates among 10 women as flexible. The results are shown in Table 3.

(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) Evaluation of paper surface smoothness 10 women were thoroughly soaped with both hands, and a handsheet with a basis weight of 20 g / m ² prepared by the same method as above and the above paper softener were added. A non-handsheet was touched and scored according to the following four criteria:

(Evaluation criteria)
4 points: very smooth compared to handsheets without added softener 3 points: smoother than handsheets without added softener 2 points: handsheet without added softener Slightly smoother than 1 point: Smoothness of handsheet without added softener

  The total score of the obtained points is calculated. When the total score is 35 points or more, the smoothness of the paper surface is very good (◎). When it was good and less than 30 points, the paper surface was evaluated as insufficiently smooth. The results are shown in Table 3.

(3) Evaluation of paper strength The handsheet was cut into 120 × 15 mm, and the tensile strength when the paper was pulled apart was measured with a tensile / compression tester (SV-201-0-SH manufactured by Imada Manufacturing Co., Ltd.). From the obtained tensile strength and basis weight values, the tear length was calculated from the following formula according to JIS P 8113 (referred to as the test tear length). This operation was performed three times to obtain an average value of the test crack step length. On the other hand, the row cut length when using a handsheet produced without adding the paper softener (control example) was defined as the blank row cut length. The test row length was compared with the blank row length and evaluated according to the following criteria. The results are shown in Table 3.

(Evaluation criteria)
Test tear length is 80% or more of blank row break length: Good paper strength (○)
Test tear length is less than 80% of blank row break length: paper strength is insufficient (×)

(Examples 2 to 8)
Among the compounds (a) (a-1 to a-4), modified silicones (b-1 to b-4), and acids (described in Table 3 described in Table 3 with respect to the amine value of compound (a)) 10 mass% dispersions (dispersions II to VIII) of the paper softener were obtained in the same procedure as in Example 1, respectively. These dispersions II to VIII were added in the amounts shown in Table 3, handsheets were produced in the same procedure as in Example 1, and the obtained handsheets were evaluated. The results are shown in Table 3.

(Comparative Example 1)
A handsheet was produced in the same procedure as in Example 1 except that the paper softener dispersion I was not used, and the obtained handsheet was evaluated. The results are shown in Table 4.

(Comparative Examples 2 to 5)
A handsheet was produced in the same procedure as in Example 1 except that a 10% by weight dispersion liquid (dispersions IX to XII) of the paper softener described in Table 4 was used, and evaluation of the obtained handsheet Went. The results are shown in Table 4.

  From the results in Table 3, it can be seen that by using the paper softener dispersions I to VIII of Examples 1 to 8, paper having excellent flexibility, paper surface smoothness, and paper strength can be obtained. .

  On the other hand, from the results of Table 4, when the paper softener of Comparative Example 1 is not used, or when the paper softener dispersions IX to XII of Comparative Examples 2 to 5 are used, the flexibility, The paper surface was inferior in either smoothness or paper strength. That is, in Comparative Example 1, since the paper softener is not used, the flexibility and the smoothness of the paper surface are insufficient. In Comparative Example 2, since the compound a′-1 is not the compound (a) used in the present invention, the flexibility is insufficient. In Comparative Example 3, since the functional group equivalent of the modified silicone is small, the smoothness of the paper surface is insufficient. In Comparative Example 4, since the amount of the compound (a) (component a) is lower than the amount of the modified silicone (component b) (a component / b component is 70/30), the flexibility is insufficient. And in the comparative example 5, since the modified silicone is not used, the smoothness of the paper surface is insufficient.

  ADVANTAGE OF THE INVENTION According to this invention, the softening agent for papers which can provide a softness | flexibility and the smoothness of the paper surface to paper, without reducing paper strength is provided. When this paper softener is used, a soft and smooth paper can be obtained while maintaining a sufficient paper strength. Such paper includes newspaper paper, printing paper, recording paper, wrapping paper, paperboard, liner, corrugated paper such as core, paper products such as wallpaper, base paper and backing paper, sanitary paper such as toilet paper and tissue paper. Widely used for paper in various fields.

Claims (1)

A paper softening agent comprising a compound (a) and a modified silicone (b) having a functional group equivalent of 10 to 100 mgKOH / g,
The compound (a) is represented by the following general formula (1):

(A is a residue of a dicarboxylic acid having 4 to 12 carbon atoms, R ¹ , R ² , R ⁵ , and R ⁶ are each an alkyl group having 1 to 4 carbon atoms, and R ³ and R ⁴ Are each an alkylene group having 2 to 4 carbon atoms).
The modified silicone (b) is at least one selected from the group consisting of amino-modified silicone, carboxyl-modified silicone, and polyether-modified silicone, and the compound (a) and the modified silicone (b) A softener for paper having a mass ratio of 85/15 to 99.9 / 0.1.