JP2002155494A - Bulky and soft paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce printing paper that has satisfactory bulkiness and softness even in the case where the face temperature of the paper lowers down on an early drying step in the paper-making process. SOLUTION: In the process of producing the objective bulky and soft paper, a bulking and softening agent that is liquid or melts at <=40 deg.C and has an HLB value of <=6 is contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulky and flexible printing paper.

[0002]

2. Description of the Related Art Comic books and paperbacks have rapidly become widespread, reflecting the recent divergence in printing. Along with this, paper is also required to be lightweight and flexible. Here, the lightening of the paper refers to a reduction in weight while maintaining the thickness of the paper, that is, a higher bulk (lower density). At present, environmental issues are being raised, and light weight of paper is an unavoidable issue for the effective use of paper pulp produced from forest resources. In addition, flexibility is the stiffness of the paper while maintaining the thickness of the paper, that is, the suppleness of the paper that can keep the open state sufficiently without opening naturally when the book is opened. Point to.

[0003] As a method for increasing the bulk of paper, a method using crosslinked pulp (Japanese Patent Application Laid-Open No. 4-185792), a method by mixing with synthetic fibers (Japanese Patent Application Laid-Open No. 3-269199, etc.), inorganic substances between pulp, etc. (Japanese Unexamined Patent Application Publication No. H3-124895, etc.) and a method using expandable particles (Japanese Unexamined Patent Application Publication No. 5-230798, Japanese Unexamined Patent Application Publication No. H11-200282, etc.). However, the use of crosslinked pulp, synthetic fibers and the like makes paper recycling impossible. Also, the method of filling the filling material between the pulp and the method using the expandable particles significantly reduces the paper strength. Also, a method using a surfactant (WO098 / 03730)
JP, JP-A-11-200283, JP-A-11-200284, JP-A-11-200285, JP-A-11-269799,
JP-A No. 11-350380) has also been reported.

On the other hand, it is considered that the flexibility of paper is expressed by many factors such as fiber type, paper density, paper moisture and the like. Household paper products, such as toilet paper and tissue paper, require moderate softness for their applications.Therefore, many softeners have been developed so far, and glycerin, polyethylene glycol, urea, and paraffin emulsification have been developed. It is known that substances, quaternary ammonium salts, and the like have the effect of giving paper flexibility. Further, a softener containing a di-long chain alkyl type quaternary ammonium salt (JP-A-63-165597, JP-A-8-2
96197), a dilonging alkyl type quaternary ammonium salt and glycerin, and a softening agent containing water or an aliphatic alcohol having 4 or less carbon atoms (JP-A-4-100995), lanolin and a lanolin derivative. Softener contained (JP-A-53
-147803), softener containing urethane alcohol or quaternary compound thereof (JP-A-60-139897), softener containing cationic oligomer (JP-A-63-251049), polyamide derivative Softener containing
JP-A-38600), pyrrolidonecarboxylic acid or a salt thereof (JP-A-7-189170) have been reported.

However, even when these bulking agents and softening agents are used in the actual papermaking process, the effects of bulking and softening may not be sufficiently exhibited.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing paper which exhibits sufficient bulkiness and flexibility even when the paper surface temperature is lowered in the papermaking drying step.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by containing a liquid or a bulky softening agent having a melting point of 40 ° C. or less, the drying of papermaking for some reason. It has been found that a paper exhibiting sufficient bulkiness and having excellent flexibility can be obtained even when the paper surface temperature is lowered in the process. In addition, HLB of bulky softener used
It has been found that the value is preferably 6 or less, and the present invention has been completed. More preferably, the bulky softener is an ester of a polyhydric alcohol and a higher unsaturated fatty acid or a higher branched fatty acid. It is preferable to add a bulk softening agent to the raw pulp in a range of 0.1% by weight or more and 5.0% by weight or less, and in order to make the bulky softness without significantly changing the paper quality, 0.2% by weight or more and 2.0% by weight or less. It is more preferable to add them in the range.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.

The bulk softening agent used in the present invention has both a hydrophobic group and a hydrophilic group in the molecule,
Currently well known are surfactants. Examples thereof include higher alcohols and alkylene oxide adducts of higher fatty acids, but are not particularly limited to surfactants as long as they can make paper bulky and flexible. It is also known that some of the aliphatic polyamidoamine compounds have a bulky and softening effect. At present, the bulky softeners that are marketed include Sulsol VL of BASF, Bivolume P Liquid of Bayer, and React-Pake of Sansei Co., Ltd.
(Opacity improver), KB-08T, KB-1 of Kao Corporation
15 and the like. The mechanism of the bulky softness is not clear, and the composition of the drugs marketed as the bulky softening agent is not the same, but in any case, it is fixed to the pulp fiber at the time of paper making and by increasing the bonding distance between the pulp fibers. It is considered that bulkiness and flexibility are exhibited.

[0010] The bulk softening mechanism is thought to be such that the bulk softening agent is melted by the heat of the dryer and covers the fiber surface, so that the fibers themselves are hydrophobized, and hydrogen bonding between fibers is inhibited, and the bulk softening effect is exhibited. ing. However, when the efficiency of the drying process is lowered for some reason and the paper surface temperature does not rise sufficiently, the bulkiness softener does not melt and the coatability is reduced, the fibers are not sufficiently hydrophobized, and hydrogen bonds between fibers are reduced. It is formed and does not show sufficient bulkiness and flexibility. Further, even if the bulk softening agent is melted, if sufficient heat is not applied to the paper, inter-fiber hydrogen bonds are generated before the paper is melted, making it difficult to exhibit a sufficient bulk softening effect. The paper surface temperature in the drying process of a general paper machine is 40 minutes until the temperature of the wet paper web becomes constant (preheating drying period).
The temperature of the wet paper is from 55 ° C to 55 ° C, and the temperature of the wet paper thereafter is about 55 ° C to 80 ° C. In addition, the bulky flexibility generally starts to take effect during the preheating drying period before the inter-fiber bonds of the pulp are formed.

[0011] Then, as a result of examining the relationship between the paper surface temperature, particularly the paper surface temperature during the preheating drying period and the bulkiness and flexibility of the paper,
By using a bulky softener that can be easily melted with a small amount of heat and that is liquid at room temperature or has a melting point of 40 ° C. or less, the fiber surface can be efficiently hydrophobicized,
It has been found that paper with low density and improved flexibility can be effectively produced.

In general, higher saturated fatty acid esters are often solid at room temperature, but higher unsaturated fatty acid esters and higher branched fatty acid esters are mostly liquids. There are many cases.

Specific examples of the ester compound of a polyhydric alcohol and a higher unsaturated fatty acid and / or a higher branched fatty acid which are used as the bulk softener of the present invention include the following compounds.

Ethylene glycol monooleate, ethylene glycol dioleate, ethylene glycol monolinoleate, ethylene glycol dilinoleate, glycerin monooleate, glycerin dioleate, glycerin trioleate, glycerin monolinoleate, glycerin dilinoleate, glycerin Trilinoleate, propylene glycol monooleate, propylene glycol dioleate, propylene glycol monolinoleate, propylene glycol dilinoleate, pentaerythritol monooleate, pentaerythritol dioleate, pentaerythritol trioleate, pentaerythritol tetraoleate, Pentaerythritol monolinolate, pentaerythritol dilinoleate, pentaerythritol Rutoririnoreto, pentaerythritol tetra linoleate, sorbitan dioleate, sorbitan trioleate, sorbitan tetraoleate, sorbitan distearate linoleate, sorbitan tanto Lili methylate, higher unsaturated fatty acid esters such as sorbitan tetra linoleate.

[0015] Ethylene glycol monoisostearate, ethylene glycol diisostearate, glycerin monoisostearate, glycerin diisostearate, glycerin triisostearate, propylene glycol monoisostearate, propylene glycol diisostearate, pentane Erythritol monoisostearate, pentaerythritol diisostearate,
Higher branched fatty acid esters such as pentaerythritol triisostearate, pentaerythritol tetraisostearate, sorbitan diisostearate, sorbitan triisostearate and sorbitan tetraisostearate. And the like, but are not limited to these.

Further, a bulky softening agent having a high HLB value and not having sufficient hydrophobicity cannot impart a desired bulky softening effect because the fiber cannot be hydrophobized. Therefore, in order to impart sufficient hydrophobicity to the fiber, the HLB value needs to be 6 or less. However, if the hydrophobicity is too high, it will be difficult to efficiently disperse in water, and it will not be possible to uniformly adsorb the fibers, and as a result, sufficient bulkiness and flexibility will not be obtained. Therefore, when using a bulky softening agent having high hydrophobicity, it is important to use a surfactant having excellent dispersibility in combination with a surfactant in order to sufficiently disperse the emulsion in water and to form a uniform emulsion. Some bulk softeners have self-emulsifying properties, but when using bulky softeners with high hydrophobicity, the surfactant should be contained in a proportion of 10.0% by weight or less based on the bulk softener. preferable.

Specific examples of the surfactant used for emulsifying the bulky softener of the present invention include the following compounds. That is, anionic surfactants such as Perex OT-P (Kao), Demol EP (Kao), Disper TL (Meisei Chemical), Gohselan L-3266 (Nippon Synthetic Chemical), and Aron T-40 (Toa Gosei Chemical). , Emulgen A-
Nonionic surfactants such as 60 (Kao), Emulmin 50 (Sanyo Chemical), Cation DS (Sanyo Chemical), Cotamine 8
Examples thereof include, but are not limited to, cationic surfactants such as 6W (Kao) and Cotamine D86P (Kao).

Since the bulky softening agent is a factor inhibiting the bonding between pulp fibers, the strength of the paper is generally reduced, and the bulky softness of the paper is exhibited. However, even if the amount of addition is increased beyond a certain level, the effect will level out. That is, it is preferable to add a bulk softener to the raw pulp in an amount of 0.1% by weight or more and 5.0% by weight or less. Further, if the amount is too large, the coefficient of friction of the paper may be extremely changed, which may affect the general paper quality.On the other hand, if the amount is too small, the bulky softening effect may not be sufficiently exhibited depending on the type of the bulky softener. In some cases, it is more preferable to add 0.2% by weight or more and 2.0% by weight or less.

The bulky flexible paper of the present invention is produced from various types of pulp by a usual papermaking process. Raw pulp includes chemical pulp (bleached or unbleached softwood kraft pulp, bleached or unbleached hardwood kraft pulp, etc.), mechanical pulp (ground pulp, thermomechanical pulp, chemithermomechanical pulp, etc.), deinked pulp, etc. They can be used alone or mixed in an arbitrary ratio. PH during papermaking
May be acidic, neutral or alkaline.

The bulky flexible paper of the present invention may contain a filler. As the filler, those commonly used can be used and are not particularly limited.For example, clay, calcined clay, diatomaceous earth, talc, kaolin, calcined kaolin, delamikaolin, heavy calcium carbonate, light calcium carbonate, Magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide, calcium hydroxide, magnesium hydroxide,
Inorganic fillers such as zinc hydroxide, and organic fillers such as urea-formalin resin, polystyrene resin, phenolic resin, and fine hollow particles are used alone or in appropriate combination of two or more kinds.

In order to obtain the paper containing the bulky softening agent of the present invention, the bulky softening agent may be used as it is or an emulsion of the bulky softening agent may be added (so-called internal addition) to a usual paper making process.
The place to be added is not particularly limited as long as it can be uniformly mixed with the pulp slurry.

In producing the bulky flexible paper of the present invention, papermaking such as various nonionic and cationic retention agents, freeness improving agents, paper strength improving agents, internal sizing agents and the like conventionally used. An internal additive is appropriately selected and used as needed.

Examples of the internal additive for papermaking include basic aluminum compounds such as a sulfuric acid band, aluminum chloride, sodium aluminate, basic aluminum chloride and basic polyaluminum hydroxide, and alumina sol which is easily decomposed in water. And polyvalent metal compounds such as ferrous sulfate and ferric sulfate, and silica sol.

Next, examples of various sizing agents include alkyl ketene dimer compounds, alkenyl succinic anhydride compounds, styrene-acrylic compounds, higher fatty acid compounds, petroleum resin sizing agents, and rosin sizing agents.

Other papermaking aids include various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic Various compounds such as a crosslinked polymer particle dispersion and derivatives or modified products thereof can be exemplified.

Further, internal additives for papermaking such as a dye, a fluorescent brightener, a pH adjuster, a defoamer, a pitch control agent and a slime control agent can be appropriately added according to the use. The paper manufacturing method of the present invention may be based on an acidic papermaking method in which the papermaking pH is, for example, about 4.5, or contains an alkaline filler such as calcium carbonate as a main component and has a papermaking pH of about 6. There is no particular limitation as to whether or not the paper is made by so-called neutral papermaking performed in a weak alkaline state of about 9 to about paper obtained by any papermaking method. As the paper machine, a fourdrinier paper machine, a twin wire machine, a Yankee paper machine or the like can be used as appropriate.

The bulky flexible paper of the present invention is suitable as, for example, offset printing paper. In addition, letterpress printing paper,
It can also be used as base paper for information recording paper such as electrophotographic paper, ink jet recording paper, heat-sensitive recording paper, and pressure-sensitive recording paper. In addition, use as a base paper for coated paper is also a preferred embodiment.

[0028]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. As a method of simulating the paper surface temperature in a normal papermaking process, handsheets were dried using two types of dryers and compared. That is, an air blow dryer assuming that the paper surface temperature during the preheating drying period becomes lower than normal (low temperature drying), and an environment assuming that the paper surface temperature during the preheating drying period becomes normal or higher than normal (high temperature drying). The evaluation was performed using a testing machine. Here, the initial paper surface temperature was used as the paper surface temperature during the preheating drying period.・ Low-temperature drying: Blow dryer (initial paper surface temperature 40 ° C, heating temperature
High temperature drying: Environmental tester (initial paper temperature 70 ° C, heating temperature)
105 ℃)

The following items were measured and evaluated for the bulky flexible papers produced in Examples and Comparative Examples. The results are shown in Table 1. -Density: compliant with JIS P 8118-Tensile strength: compliant with JIS P 8113-Clark stiffness: compliant with JIS P 8143-HLB value of bulky softener: Calculated by the following formula. HLB value = 20 × (molecular weight of hydrophilic group portion) / (total molecular weight)

[Example 1] Pentaerythritol dioleate (reagent: Tokyo Chemical Industry, liquid, HL)
(B value = 4.0) 10.0 g as a dispersant, “Rex OT-
0.1 g of P (manufactured by Kao Corporation) is mixed well, added to 1000 g of water, and rotated at 10,000 rpm using an emulsifier.
Stirring was performed for 10 minutes to prepare an emulsified liquid of the bulky softener. LBKP (freeness CSF 350 ml) was used as the pulp content. To this, a stock was prepared by adding the above-mentioned bulky softener emulsion to 1.0% by weight based on pulp.
Then, the paper was made using a round-type hand maker so as to have a basis weight of 60 g / m ^2, and pressed at an effective press pressure of 4.18 kg / cm ² ,
Air dryer (paper temperature 40 ° C) and environmental tester (paper temperature
(70 ° C.) for 1 hour to obtain a bulky flexible paper.

[Example 2] Glycerin trioleate (reagent: Tokyo Chemical Industry Co., Ltd., liquid, HL)
(B value = 2.0) 10.0 g and Emulgen A-60 as a dispersant
A bulky flexible paper was obtained in the same manner as in Example 1 except that an emulsifier for a bulky softener was prepared using 0.2 g (manufactured by Kao Corporation).

Example 3 Glycerin monolinoleate (reagent: Tokyo Chemical Industry, liquid, HLB value = 5.
1) 10.0 g with cationic DS as a dispersant (Sanyo Chemical Co., Ltd.)
The bulky soft paper was obtained in the same manner as in Example 1 except that an emulsifier of a bulky softener was prepared using 0.15 g of the same.

Example 4 The procedure of Example 1 was repeated except that 0.3 g of pentaerythritol diisostearate (self-produced, liquid, HLB value = 4.0) was used as a bulk softener to prepare an emulsifier for the bulk softener. To obtain bulky flexible paper.

[Comparative Example 1] Pentaerythritol distearate (reagent: manufactured by Tokyo Chemical Industry Co., Ltd.)
A bulky flexible paper was obtained in the same manner as in Example 1 except that an emulsifier for a bulky softener was prepared using a melting point of 51 ° C. and an HLB value of 4.0.

Comparative Example 2 Sorbitan monolaurate (reagent: Span # manufactured by Tokyo Chemical Industry Co., Ltd.) was used as a bulk softening agent.
20, a liquid, HLB value = 9.4), and a bulky soft paper was obtained in the same manner as in Example 1 except that an emulsifier for a bulky softener was prepared.

Comparative Example 3 A handsheet was obtained in the same manner as in Example 1 except that the bulk softener was not added.

[0037]

[Table 1] As shown in Table 1, when Examples 1-4 and Comparative Example 1 are compared,
By using a higher unsaturated fatty acid ester or a higher branched fatty acid ester salt which is liquid at room temperature as a bulking softener, compared to a case where a higher saturated fatty acid ester having a high melting point is used, even if the initial paper surface temperature is low, the bulkiness is increased. Paper with reduced Clark stiffness was obtained. That is, in the examples, a sufficient bulk softening effect is exhibited irrespective of the drying temperature (initial paper surface temperature). However, in the comparative example (in the case of using a bulk softening agent having a melting point exceeding 40 ° C.), the bulk softening effect is reduced. It can be seen that a sufficiently high initial paper surface temperature is necessary for the expression. In addition, when Examples 1 to 4 are compared with Comparative Example 2, it can be seen that if the HLB value of the bulk softener is 6 or less, a sufficient bulk softening effect can be obtained.

As described above, by using a liquid or a bulk softening agent having a melting point of 40 ° C. or less and an HLB value of 6 or less, sufficient bulk flexibility is obtained even when the paper surface temperature is lowered in the initial drying step. Can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsutoshi Nakamura 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. (72) Inventor Masafumi Ishida 5-2-1-1, Oji, Kita-ku, Tokyo No. Nippon Paper Industries Co., Ltd. (72) Inventor Yasunori Minamisato 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 4L055 AA03 AC06 AG34 AH50 EA20 EA29 EA32 FA16 FA23 GA08 GA15

Claims (3)

[Claims] 1. A liquid or melting point of 40 ° C. or less and H
A bulky soft paper containing a bulky softener having an LB number of 6 or less. 2. The bulky flexible paper according to claim 1, wherein the bulky softener is an ester compound of a polyhydric alcohol and a higher unsaturated fatty acid and / or a higher branched fatty acid. 3. The bulky flexible paper according to claim 1, wherein the surfactant is contained in an amount of 10.0% by weight or less based on the bulky softener.