JP2003253589A - Paper-bulking agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper-bulking agent having an enough bulkiness- improving effect, without deteriorating dry paper strength. <P>SOLUTION: This paper-bulking agent contains (A) a water-soluble urethane resin which is obtained by reacting isocyanate groups of a urethane prepolymer with active hydrogen compounds for introducing hydrophilic groups and (B) a salt of sulfosuccinate diester, wherein the urethane prepolymer is a reaction product of a polyisocyanate with a hydrophobic compound having reactivity with the isocyanate group and contains the free isocyanate groups. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulking agent for paper which improves bulkiness of paper for use in books and the like.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for papers excellent in printability and volume feeling, mainly for book applications and the like. Since these printability and volume feeling are related to the bulkiness of paper, various bulking agents for improving bulkiness have been proposed.

For example, Japanese Patent Application Laid-Open No. 11-200284 discloses a compound comprising a specific fatty acid and a polyoxyalkylene adduct of a fatty acid ester, and also Japanese Patent Application Laid-Open No. 1-200284.
JP-A 1-269799 discloses a compound comprising a specific cationic compound, an amine, an acid salt of an amine and an amphoteric compound.

However, with the conventional bulking agent, even if stable bulkiness is obtained, there is a problem that the dry paper strength is lowered, and a sufficient solution to this has not yet been obtained. .

The present invention has been made in view of the above, and an object of the present invention is to provide a bulking agent for paper which has an excellent effect of improving bulkiness and does not cause a problem of reduction in dry paper strength. .

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the use of a urethane resin as a main component improves the bulkiness without causing a decrease in dry paper strength. The present invention has been completed and the present invention has been completed.

That is, the bulking agent for paper of the present invention is (A)
A water-soluble product obtained by reacting an isocyanate group of a urethane prepolymer containing a free isocyanate group, which is a reaction product of a polyisocyanate and a hydrophobic compound having reactivity with an isocyanate group, with an active hydrogen compound for introducing a hydrophilic group. -Containing urethane resin and (B) sulfosuccinic acid diester salt (Claim 1).

As the hydrophobic compound having reactivity with an isocyanate group in the component (A), a polyol component having an average number of functional groups of 2 or more can be used (claim 2).

As the active hydrogen compound for introducing the hydrophilic group in the component (A), a compound having a salt-forming carboxylic acid group or sulfonic acid group can be used (claim 3). An alkylene oxide polymer can also be used as the active hydrogen compound (claim 4).

The water-soluble urethane resin as the component (A) is
It is obtained by reacting the free isocyanate group of the urethane prepolymer with an active hydrogen compound for introducing a hydrophilic group, and then blocking the remaining free isocyanate group with a blocking agent that regenerates the isocyanate group by heat treatment. It is possible (Claim 5).

Alternatively, this water-soluble urethane resin is obtained by reacting a free isocyanate group of a urethane prepolymer with an active hydrogen compound for introducing a hydrophilic group, and then crosslinking the remaining free isocyanate group with water to polymerize it. It is also possible (claim 6).

As the sulfosuccinic acid diester salt in the component (B), a sulfosuccinic acid ester sodium salt of a linear alcohol having 14 to 30 carbon atoms can be used (claim 7).

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The urethane prepolymer constituting the component (A) used in the present invention is obtained by reacting a hydrophobic compound having reactivity with an isocyanate group with a polyisocyanate compound in an excessive NCO / OH equivalent ratio. Manufactured.

As the hydrophobic compound having reactivity with an isocyanate group, a divalent or higher polyol having a molecular weight of 1,000 to 20,000 is used. Further, castor oil polyol, polybutadiene polyol, fluorine polyol, polythioether polyol and the like are also used.

First, as the polyol component having an ether bond, a divalent or higher polyether polyol having a molecular weight of 1,000 to 20,000 is preferably used. The polyether polyol is obtained by polyadding an alkylene oxide with a polyhydric alcohol as a starting material in the presence of a basic catalyst. Examples of the dihydric alcohol component include glycols having 2 to 4 carbon atoms. Examples of the trihydric alcohol component include triols such as glycerin, hexanetriol, trimethylolethane, and trimethylolpropane, and alkanolamines such as triethanolamine, triisopropanolamine, and tributanolamine. Moreover, pentaerythritol is mentioned as an example of a tetrahydric alcohol component. Further, examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide and the like.

Further, alkylene oxide adducts of polyvalent amines such as alkylene oxide adducts of ethylenediamine are also used.

Further, a modified polyorganosiloxane having an average number of functional groups of 2 or more is also used. The modified polyorganosiloxane is classified into a molecule both-ends modified type and a side chain modified type in which two or more side chains are modified in the molecule.
Both can be used. More specifically, as a functional _{group, - (CH 2) pOH,} - (OCH 2 CH 2) q
OH and _{- (CH 2) p (OCH} 2 (CH 3) CH 2) q
Carbinols with OH, etc. and, _- (CH 2) pNH
An amino compound having (CH ₂ ) rNH ₂ and the like (where p is an integer of 1 to 5, q is an integer of 1 to 10 and r is 1 to
Each of which represents an integer of 5), which has reactivity with the organic polyisocyanate compound. Further, a compound having a total of two or more functional groups at both the molecular end and the side chain is also used. The average molecular weight of these modified polyorganosiloxanes is preferably in the range of 800 to 8000.

Further, as the polyol component having an ester bond, a polyester polyol obtained from a dibasic acid component and a dihydric alcohol component is also used. Examples of the dibasic acid component constituting the polyester polyol component include saturated or unsaturated oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. Included are saturated aliphatic dibasic acids and aromatic dibasic acids. Examples of the dihydric alcohol component constituting the polyester polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and 1,4-
Butanediol, 1,5-pentanediol, 1,6-
Aliphatic glycols such as hexanediol, 3-methyl-1,5-pentadiol and the like and alicyclic glycols such as cyclohexanediol and the like can be mentioned. A polyester polyol is obtained by subjecting these dibasic acid component and dihydric alcohol component to a condensation reaction.

The isocyanate compound used in the present invention is not particularly limited, and those conventionally used in the field of urethane industry are used. Examples thereof include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymeric. Examples thereof include organic polyisocyanate compounds such as MDI, hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and isophorone diisocyanate (IPDI). When yellowing is required,
Aliphatic isocyanates such as HMDI, alicyclic isocyanates such as IPDI, and alicyclic isocyanates such as XDI and TMXDI are preferably used.

In the synthesis of the above urethane prepolymer, a chain extender component may be used if necessary. The chain extender component is a low molecular weight polyol component having two or more active hydrogen groups, and examples thereof include dihydric alcohol components such as ethylene glycol, diethylene glycol, butanediol and propylene glycol, and trimethylolpropane, glycerin and penta. Examples thereof include polyhydric alcohols such as erythritol or oxyalkylene derivatives. In addition, as the chain extender component having an aromatic ring or an alicyclic ring, bisfer A, bisphenol B,
Hydrogenated bisphenol A, dibromobisphenol A,
Examples thereof include cyclohexanediol, cyclohexanedimethanol, hydroquinone, hydroquinone dihydroxyethyl ether, bis (2-hydroxyethyl) terephthalate, and bis (4-hydroxyphenyl) sulfone.

The above polyol component and the organic polyisocyanate are mixed at an arbitrary ratio such that the molar ratio of NCO group / active hydrogen group is 1.0 or more, and the mixture is mixed with a known method in a proportion of 30 to 13 by a known method.
By reacting at 0 ° C for 30 minutes to 50 hours, a urethane prepolymer having at least 0.5% by weight or more, preferably 1 to 8% by weight of a free isocyanate group can be obtained.

In the present invention, since the component (B) is anionic, the water-soluble urethane resin as the component (A) needs to be anionic or nonionic.

Therefore, as an active hydrogen compound for introducing a hydrophilic group that reacts with an isocyanate group, first,
A compound having a salt-forming carboxylic acid group or sulfonic acid group is used. For example, glycolic acid, malic acid,
Hydroxy acids such as glycine, aminobenzoic acid, alanine, dimethylolpropionic acid, and dimethylolbutanoic acid, aminocarboxylic acids, aminosulfonic acids such as 2-aminoethanesulfonic acid (tauric acid), and 2-hydroxyethanesulfonic acid Examples thereof include hydroxysulfonic acids. In addition, examples of salt-forming agents corresponding thereto include monovalent metal hydroxides such as sodium hydroxide and potassium hydroxide, and tertiary amine compounds such as ammonia, trimethylamine, and triethylamine.

When a nonionic hydrophilic group is introduced into the urethane prepolymer, a polyhydric alcohol is used as a starting material of a basic catalyst as an active hydrogen compound for reacting with an isocyanate group to introduce a hydrophilic group. It is also possible to use a polyether polyol obtained by polyadding alkylene oxide in the presence. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide and the like. These alkylene oxide polyadducts were introduced into the prepolymer so that the ethylene oxide content in the prepolymer was 35
% Or more.

There are two types of methods for treating the remaining isocyanate groups (unreacted isocyanate groups). That is, (a) a method of blocking unreacted isocyanate groups with a blocking agent, and (b) a method of water-crosslinking or amine-crosslinking the unreacted isocyanate groups during emulsification.

Regarding the above method (a), the blocking agent for blocking the unreacted isocyanate group is
Known compounds can be used, but specifically, (1) bisulfite, (2) lactam type such as ε-caprolactam,
(3) Acetone oxime, methyl ethyl ketoxime,
Oxime type such as cyclohexanone oxime, (4) dimethyl malonate, active methylene type such as ethyl acetoacetate, (5) imidazole, 2-methylimidazole, 2
-Ethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole and other imidazole compounds, (6) phenol, cresol,
Examples thereof include phenolic compounds such as para-hydroxybenzoic acid, para-hydroxybenzoic acid ester, salicylic acid, and salicylic acid ester.

With regard to the method (b), when the remaining isocyanate groups (unreacted isocyanate groups) are water-crosslinked, the urethane prepolymer is water-dispersed while the free isocyanate groups remain, and the isocyanate groups are replaced with water molecules. Can be crosslinked to obtain a high molecular weight.
At the time of water-crosslinking, a free isocyanate group can be amine-crosslinked by using a polyamine-based crosslinking agent such as hydrazine, ethylenediamine, diethylenetriethylene and dipropylenetriamine together.

The synthesis of the urethane prepolymer is a non-solvent system, but depending on the viscosity of the urethane prepolymer,
A solvent which is inactive with isocyanate and can dissolve the urethane prepolymer may be used. Examples of such solvents are dioxane, methyl ethyl ketone, dimethylformamide, tetrahydrofuran, N-methyl-2.
-Pyrrolidone, toluene, propylene glycol monomethyl ether acetate and the like. A solution or emulsion of an antioxidant or a light stabilizer may be used in combination with the urethane prepolymer aqueous solution.

Examples of antioxidants include solutions or emulsions of hindered phenol-based or semicarbazide-based antioxidants. Examples of light stabilizers include
Hindered amine (HALS) type, benzophenone type,
Examples thereof include solutions or emulsions of light stabilizers such as benzotriazole.

Next, the sulfosuccinic acid diester salt (B) which is another essential component constituting the bulking agent is preferably a sodium salt of a sulfosuccinic acid ester of a linear alcohol having 14 to 30 carbon atoms. For example,
Sulfosuccinic acid dimyristyl ester, sulfosuccinic acid dipentadecyl ester, sulfosuccinic acid dicetyl ester, sulfosuccinic acid diheptadecyl ester, sulfosuccinic acid distearyl ester, sulfosuccinic acid dioleyl ester, sulfosuccinic acid dinonadecyl ester,
Examples thereof include sulfosuccinic acid dieicosyl ester, sulfosuccinic acid diceryl ester, sulfosuccinic acid dimelylyl ester, sulfosuccinic acid dibenzyl ester, and sulfosuccinic acid dicinnamyl ester. Of these, esterified products of alcohols having 16 to 20 carbon atoms and sodium sulfosuccinate are preferable because they can be produced at low cost.

The weight ratio of the components (A) and (B) is 98/2 to 2/98, preferably 95.
/ 5 to 5/95. If either component is less than 2% by weight, a sufficient bulking effect cannot be obtained.

Although the reason why the bulkiness effect is greatly improved by blending both is not clear, it is generally known that the bulkiness effect is exhibited by hydrophobizing the pulp surface in the slurry during papermaking. Therefore, it is considered that by blending both the component (A) and the component (B), the pulp surface can be more effectively hydrophobized by the synergistic effect of the both.

The bulking agent produced as described above can be applied by a method such as coating to a web after paper making like a sizing agent, but it is added to a papermaking stock together with other additives such as a filler. However, it is suitable for being added to the paper which is produced through a wire section, a press section, a dryer section, etc. by a conventional method. In that case, the amount of the bulking agent for paper added is preferably 0.05 to 5.0 weight based on the weight of fiber in the stock. Since the bulking agent of the present invention has a high bulking effect, it is possible to reduce the amount of the chemical agent added as compared with the conventional bulking agent, and thus it is possible to minimize the decrease in dry paper strength.

The bulking agent for paper of the present invention can be applied not only to pulp such as mechanical pulp and chemical pulp but also to pulp including waste paper pulp as a raw material for pulp, and rosin and alkyl ketene at the time of papermaking. In addition to sizing agents such as dimer, alkenyl succinic anhydride, starch and gelatin, it is also possible to add paper strength improvers, fillers, drainage improvers and the like.

[0035]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

1. (A) Synthesis of Water-Soluble Urethane Resin (Synthesis Example 1) Ethylene Oxide / Propylene Oxide Polyaddition Product Starting from Glycerin (Average Molecular Weight:
10,000, PO content: 50%) 450 parts by weight (hereinafter referred to as "parts") of 22.3 parts of hexamethylene diisocyanate were added and reacted at 100 ° C for 2 hours to obtain 1.2 parts by weight of free isocyanate groups. A urethane prepolymer having a% was obtained. Then 30% sodium bisulfite aqueous solution 4
After adding 7 parts and stirring at 45 ° C. for 60 minutes, the mixture was diluted with water to prepare a semitransparent viscous anionic blocked urethane resin aqueous solution (1) having a resin content of 15%.

(Synthesis Example 2) With respect to 100 parts of 1,6-hexylene carbonate (molecular weight: 1000, bifunctional),
50 parts of MDI was added and reacted at 70 ° C. for 90 minutes.
At this time, the free isocyanate group content was 5.6%. Furthermore, 100 of PEG2000 monomethoxy compound
Parts were added and reacted at 70 ° C. for 2 hours. Inner temperature is 40 ° C
And diluted with water to obtain a 25% pure water-soluble urethane resin aqueous solution (2).

(Synthesis Example 3) Polytetramethylene ether glycol (molecular weight: 1000, bifunctional, hereinafter PTM
(Abbreviated as G)) For 200 copies, TDI-80 is 10
4.4 parts was added, and the mixture was reacted at 70 ° C. for 30 minutes. At this time, the free isocyanate group content was 11%. The system was cooled to 60 ° C. and dimethylolpropionic acid was added to 40.
Two parts were added and the reaction was carried out at 65 ° C. for 60 minutes. At this time, the free isocyanate group content was 2.5%. Furthermore, 19 parts of butyl paraoxybenzoate was added, and the mixture was added at 65 ° C for 30 minutes.
Let react for minutes. After confirming the disappearance of free isocyanate groups, the mixture was diluted with water to obtain a water-soluble urethane resin aqueous solution (3) having a pure content of 25%.

(Synthesis Example 4) Ethylene oxide / propylene oxide polyaddition product starting from glycerin (average molecular weight: 10,000, PO content: 60%) 1
50.4 parts of HMDI was added to 00 parts, and the temperature was 70 ° C.
And reacted for 60 minutes. At this time, the free isocyanate group content was 1.2%. Butyl benzoate 2
0 part was added and reacted at 70 ° C. for 30 minutes. At this time, the free isocyanate group content was 0.8%. After cooling the internal temperature to 40 ° C, add 35% taurine Na aqueous solution to 84%.
Parts were added and the reaction was carried out at 40 ° C. for 10 minutes. Further, it was diluted with water to obtain a water-soluble urethane resin aqueous solution (4) having a pure content of 25%.

(Synthesis Example 5) PTMG (average molecular weight: 10)
(00, bifunctional) 200 parts, TDI-80 10
4.4 parts was added, and the mixture was reacted at 70 ° C. for 30 minutes. At this time, the free isocyanate group content was 11%. The system was cooled to 60 ° C. and dimethylolpropionic acid was added to 40.
Two parts were added, and the mixture was reacted at 65 ° C for 60 minutes. At this time, the free isocyanate group content was 2.5%. Further, 39.4 parts of butyl paraoxybenzoate was added to give 65
The reaction was carried out at 30 ° C. for 30 minutes. After confirming the disappearance of free isocyanate groups, the mixture was diluted with water to obtain a water-soluble urethane resin aqueous solution (5) having a pure content of 25%.

(Synthesis Example 6) Side chain hydroxyl group-modified silicone oil (dimethylsiloxane base, average molecular weight: 230)
0, OH group value: 73, average number of functional groups 3) To 200 parts of xylylene diisocyanate at room temperature, 49.0 parts of xylylene diisocyanate was added and reacted for 70 minutes at an internal temperature of 95 ° C to obtain 4.4% of free isocyanate groups. A urethane prepolymer containing was obtained. To 200 parts of this urethane prepolymer, at a system temperature of 40 ° C., 72 parts of a 30% sodium bisulfite aqueous solution was added, reacted for 40 minutes and then diluted with water to obtain a water-soluble urethane resin aqueous solution having a solid content of 25% ( 6) was obtained.

(Synthesis Example 7) 100 parts of polyester polyol (2EO adduct of bisphenol A / polycondensation product of adipic acid, average molecular weight: 1000), 6.7 parts of trimethylolpropane, 1,4-cyclohexanedimethanol 21. 6 parts, N-methyldiethanolamine 20.8
Part and 115.1 parts of HMDI were reacted at 65 ° C. for 120 minutes. The free isocyanate group content at this time was 6.0.
%Met. Next, the temperature of the system is set to 40 ° C., 22.1 parts of diethyl sulfate is added, a quaternization reaction is performed at 55 ° C. for 30 minutes, diluted with water, and free isocyanate groups are water-crosslinked,
Aqueous aqueous urethane resin solution with solid content of 25% (7)
Got

(Comparative Synthesis Example 1) 100 PEG1000
Parts, 3.3 parts of trimethylolpropane, 20.8 parts of N-methyldiethanolamine, and 58.8 parts of hexamethylene diisocyanate were reacted at 65 ° C. for 120 minutes. The free isocyanate group content at this time was 2.0%. Next, the system temperature was set to 50 ° C., and diethyl sulfate 22.1
Parts were added and a quaternization reaction was carried out at 55 ° C. for 30 minutes. Three
The mixture was cooled to 5 ° C. and diluted with water to obtain a water-soluble urethane resin aqueous solution (1) having a pure content of 25%.

2. (B) Synthesis of sulfosuccinic acid diester salt (Synthesis Example 1) 8.5 parts of maleic anhydride was added to 35 parts of myristyl alcohol and reacted at 190 ° C. for 2 hours to obtain maleic acid dimyristyl ester. Then, to this maleic acid dimyristyl ester, 8.2 parts of anhydrous sodium bisulfite and 1.5 parts of anhydrous sodium sulfite,
24 parts of water was added and reacted at 85 ° C. for 4 hours to obtain a sodium salt (I) of dimyristyl sulfosuccinate.

(Synthesis Example 2) Oleyl alcohol 44.5
8.5 parts maleic anhydride was added to 190 parts, and the temperature was 190 ° C.
And reacted for 2 hours to obtain maleic acid distearate.
Subsequently, to this maleic acid distearate, 8.2 parts of anhydrous sodium bisulfite and 1.5 parts of anhydrous sodium sulfite were added.
Parts and 24 parts of water were added and reacted at 85 ° C. for 4 hours to obtain a sodium salt (II) of sulfosuccinic acid distearate.

(Synthesis Example 3) To 72 parts of melysyl alcohol, 8.5 parts of maleic anhydride was added, and the mixture was heated at 190 ° C. for 2 hours.
The reaction was carried out for a time to obtain maleic acid dimelisyl ester.
Subsequently, 8.2 parts of anhydrous sodium bisulfite and 1.2 parts of anhydrous sodium sulfite were added to the maleic acid dimelicyl ester.
5 parts of water and 24 parts of water were added, and the mixture was reacted at 85 ° C. for 4 hours to obtain a sodium salt of sulfosuccinic acid dimericyl ester (II
I) got.

(Comparative Synthesis Example 1) (C13 alcohol ester) To 33 parts of tridecyl alcohol, 8.5 parts of maleic anhydride was added and reacted at 190 ° C. for 2 hours to obtain maleic acid diacetylate. Subsequently, to this maleic acid diacetylate, 8.2 parts of anhydrous sodium bisulfite, 1.5 parts of anhydrous sodium sulfite and 24 parts of water were added, and the mixture was reacted at 85 ° C. for 4 hours to give di-tridecyl sulfosuccinate. The sodium salt (a) was obtained.

[Examples and Comparative Examples] Using the urethane resin aqueous solutions and sulfosuccinic acid diester salts obtained in the above Synthesis Examples and Comparative Synthesis Examples, JIS P 8 was prepared as follows.
A papermaking test was conducted according to 209-1961.

LBKP (Hardwood Sulfate Pulp) 135.
After tearing 3 g into about 3 cm square and immersing in 1668.7 g of water overnight, defibrating for 3 hours with a standard disintegrator, pulp concentration 7.5%, freeness 427 (ml) (Canadian standard freeness, 20 ° C, 0.3%) pulp slurry.

400 g of this pulp slurry was adjusted to pH 4.5 with aluminum sulfate in advance and then adjusted to a solid content of 2% in advance, and the amounts of the aqueous solutions of Examples and Comparative Examples shown in Tables 1 to 3 (in the table, pulp was used). An amount corresponding to the amount of pure content (% by weight based on dry weight) is added, and 3.0 g of an aqueous solution of a commercially available rosin-based sizing agent adjusted to a solid content of 2% is added, and further 594 g of water is added to the pulp. The concentration was set to 3% and used as a stock.

32 g of the thus-prepared stock was collected, paper-made by a sheet machine, and then pressed by a press machine (3.5
(kg / m ² × 5 minutes), and finally dried with a mirror drier at 100 ° C. for 3 minutes to produce a test paper having a basis weight of 60 g / m ² . The obtained sheet is 20 ° C x 65% R
The humidity was controlled overnight under H condition, and the bulkiness and dry paper strength were measured.

The bulk density (g / cm ³ ) was determined by the following formula after measuring the basis weight (g / m ² ) and thickness (mm) of the humidity-conditioned sheet. The bulk density indicates that the lower the absolute value, the higher the bulk.

[0053]

[Formula 1]

The dry paper strength (tear length) was measured by measuring the basis weight (g / m ² ) of the conditioned sheet and then measuring the sheet length 11
(Cm) × 1.5 (cm) width, cut into pieces and mounted on an Autograph standard tensile tester with a chuck distance of 5 cm,
Tensile strength (kgf) was measured and the breaking length (k
m) was calculated.

[0055]

[Formula 2]

As a comparative example, a stock was prepared in the same manner as above except that a bulking agent was not used, and a papermaking paper was also determined for bulk density and breaking length in the same manner as above (Comparative Example 1). .

Further, commercially available (1) fatty acid polyamidoamine (Comparative Example 4) and (2) pentaerythritol stearic acid esterified product (Comparative Example 5) were adjusted to an aqueous solution having a solid content of 2%, and the mixture was prepared in advance. 7.5% pulp slurry 40 adjusted to pH 4.5 with aluminum sulfate
An aqueous solution in which an amount corresponding to the amount shown in Table 3 was added to 0 g and a commercially available rosin-based sizing agent was adjusted to a solid content of 2% 3.0
g, and then 591 g of water to obtain a pulp concentration of 3
% And stock. Using this, papermaking was performed in the same manner as above, and the bulk density and the breaking length were determined.

The results are shown in the table.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

According to the bulking agent for paper of the present invention, the decrease in dry strength of paper, which has been a problem with conventional bulking agents, can be suppressed. Further, since the bulking effect is further improved as compared with the existing bulking agent, the amount of pulp used in papermaking can be further reduced, and further cost reduction can be achieved.

Continued front page    F-term (reference) 4J002 CK031 CK041 CK051 EV186                       GD00                 4J034 BA07 BA08 CA04 CA22 CB04                       CC01 CC03 CD08 DA01 DB04                       DB05 DB07 DF01 DF16 DF20                       DF21 DF22 DG03 DG04 DG05                       DG23 HA01 HC03 HC12 HC17                       HC22 HC46 HC52 HC61 HC63                       HC64 HC67 HC71 HC73 HD04                       HD07 HD12 HD13 HD15 QB15                       QB17 RA09                 4L055 AA03 AC06 AG34 AG36 AG85                       AH50 BD10 EA30 FA16

Claims (7)

[Claims] 1. An active hydrogen for introducing a hydrophilic group into an isocyanate group of a urethane prepolymer containing a free isocyanate group which is a reaction product of (A) a polyisocyanate and a hydrophobic compound having reactivity with the isocyanate group. A bulking agent for paper, comprising a water-soluble urethane resin obtained by reacting with a compound, and (B) a sulfosuccinic acid diester salt. 2. The hydrophobic compound having reactivity with an isocyanate group in the component (A) has an average number of functional groups of 2
The bulking agent for paper according to claim 1, which comprises at least one polyol component. 3. The active hydrogen compound for introducing a hydrophilic group in the component (A) is a compound having a salt-forming carboxylic acid group or sulfonic acid group, according to claim 1 or 2. The bulking agent for paper described. 4. The bulking agent for paper according to claim 1, wherein the active hydrogen compound for introducing a hydrophilic group in the component (A) is an alkylene oxide polymer. 5. The water-soluble urethane resin as the component (A),
It is obtained by reacting the free isocyanate group of the urethane prepolymer with an active hydrogen compound for introducing a hydrophilic group, and then blocking the remaining free isocyanate group with a blocking agent that regenerates the isocyanate group by heat treatment. The bulking agent for paper according to any one of claims 1 to 4, which is characterized in that: 6. The water-soluble urethane resin as the component (A),
The urethane prepolymer is obtained by reacting a free isocyanate group with an active hydrogen compound for introducing a hydrophilic group, and then crosslinking the remaining free isocyanate group with water to polymerize it. The bulking agent for paper according to any one of 1 to 4. 7. The sulfosuccinic acid diester salt of the component (B) is a sulfosuccinic acid ester sodium salt of a linear alcohol having 14 to 30 carbon atoms, according to any one of claims 1 to 6. The bulking agent for paper according to item 1.