JPH04361693A - Water-repelling treatment for paper - Google Patents

Abstract

PURPOSE:To accomplish the title treatment by reaction of a two or more isocyanate groups-contg. compound with the hydroxyl groups present in a paper to form urethane link(s) and by reaction of a specific compound with the remaining isocyanate group(s). CONSTITUTION:A compound having two or more isocyanate groups such as p-phenylene diisocyanate is reacted with the hydroxyl groups present in a paper to effect formation of at least one urethane link, and a water-repellent compound with relatively low molecular weight having at least one hydroxyl group (e.g. 2,2,2-trifluorethanol) is then reacted with the remaining isocyanate group(s) to effect urethane link formation, thus accomplishing the objective water- repelling treatment for the paper.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for making paper made from natural wood used in industry water repellent.

0002

[Prior Art] As a conventional chemical treatment method for paper made from natural wood, a silane coupling agent (for example, JP-A-02-16134 and JP-A-02-55206) is used.
carboxylic acids (e.g., JP-A-53-7
5126), but there is no example of reacting isocyanate with paper.

[0003]Also, a method of surface modification by reacting fine particles of alumina, ferrite, silica, carbon black, etc. with a compound containing an isocyanate group to bind a polymer compound is known; There are no examples of this being applied to paper that has been used.

0004

[Problem to be solved by the invention] Among conventional chemical treatment methods for paper made from natural wood, for example, in the case of silane coupling treatment, there are not many types of silane coupling agents, and it is difficult to achieve the intended function. There are drawbacks such as the inability to freely select the compounds to be used, and the fact that silane coupling agents are very expensive. In the case of physical treatment, there are drawbacks such as insufficient adhesion to the substrate, resulting in peeling of the treated film and poor durability.

[0005] In view of the above state of the art, the present invention seeks to provide a method for chemically treating paper made from natural wood to impart water repellency to the paper.

[0006]

[Means for Solving the Problems] The present inventors have intensively investigated a chemical treatment method for imparting water repellency to paper made from natural wood (hereinafter simply referred to as paper), and have found that the molecular weight of We have invented a chemical treatment method in which several thousand relatively low-molecular-weight compounds are reacted with hydroxyl groups present in paper via isocyanate to chemically bond them to impart the desired water-repellent function.

Specifically, the present invention provides (1) reacting hydroxyl groups present in paper with a compound having at least two isocyanate groups to form at least one urethane bond; A method for treating paper with water repellency, which comprises reacting a compound having a water repellency function with a relatively small molecular weight and having at least one hydroxyl group with the remaining isocyanate groups to form a urethane bond. .

(2) A paper characterized by reacting hydroxyl groups existing in the paper with at least one isocyanate group and a compound having a relatively small molecular weight group having a water-repellent function to form a urethane bond. Water repellent treatment method. It is.

[0009]

[Operation] Paper usually has hydroxyl groups on its fiber surface. In the chemical water repellency treatment method of the present invention, it is possible to directly treat the fiber by utilizing the hydroxyl groups present on the surface of the fiber, but if the surface is contaminated with oil etc. Preferably, the treatment of the invention is carried out.

[0010] As the low-molecular compound having a molecular weight of several tens to several thousand, various compounds that provide the desired function can be used. Specifically, for example, in the case of water repellency, fluorine compounds,
For example, in the case of hydrophilicity, compounds such as polyhydric alcohols may be used. If these compounds contain an isocyanate group, they can react directly with the hydroxyl groups of paper, and if they have a group that has a water-repellent function but do not contain an isocyanate group, they are first reacted with a polyisocyanate compound. Chemical water repellency treatment is possible by reacting the two and then reacting them.

The present invention will be explained in more detail below. Examples of low molecular weight compounds with a molecular weight of several tens to several thousand for imparting water repellency include saturated hydrocarbons, aromatic hydrocarbons, perfluoroalkyl groups, or fluorine in which hydrogen atoms are partially substituted with fluorine atoms as water repellent groups. A compound having a hydrocarbon-containing hydrocarbon in the molecule and at least one isocyanate group, or at least one hydroxyl group, amino group, or carboxyl group in the molecule is applicable,
Among these, the compound having an isocyanate group can be directly reacted with the hydroxyl group of the paper fibers to form a chemical bond, thereby achieving the desired chemical treatment.

[0012] In addition, for a compound that does not contain an isocyanate group and has only a carboxyl group, hydroxyl group, or amino group other than a water-repellent group, first, a hydroxyl group of paper fibers and a compound that has two or more isocyanate groups in the molecule are combined. The desired chemical water repellency treatment can be achieved by reacting to form a chemical bond, and then reacting the remaining isocyanate group with a carboxyl group, hydroxyl group, or amino group to form a chemical bond.

[0013] Specific examples will be explained below, but they are not intended to limit the chemical water repellency treatment method of the present invention.

Examples of compounds having at least one isocyanate group in the molecule and a saturated hydrocarbon group as a water-repellent group include n-propyl isocyanate, isopropyl isocyanate, and ethyl isocyanate.

Those having at least one isocyanate group in the molecule and having an aromatic hydrocarbon as a water-repellent group include phenyl isocyanate, α-naphthyl isocyanate, benzyl isocyanate, benzenesulfonyl isocyanate, and isocyanate. m-tolyl, isocyanic acid-
Examples include p-tolyl and p-toluenesulfonyl isocyanate.

Compounds having at least one isocyanate group in the molecule and a fluorine-containing hydrocarbon group in which hydrogen atoms are partially substituted with fluorine atoms as water-repellent groups include:
Examples include α,α,α-trifluoro-o-tolyl isocyanate, α,α,α-trifluoro-m-tolyl isocyanate, and 2-fluorophenyl isocyanate.

These low-molecular compounds containing at least one water-repellent group and at least one isocyanate group in their molecules can achieve the desired chemical water-repellent treatment by reacting with hydroxyl groups present on the surface of paper fibers.

Examples of substances having at least one hydroxyl group in the molecule and a saturated hydrocarbon group as a water-repellent group include lower alcohols such as methanol and ethanol, or higher alcohols having a long chain saturated hydrocarbon group such as stearyl alcohol. Alcohol is an example.

Those containing at least one hydroxyl group, amino group or carboxyl group in the molecule and having a fluorine-containing hydrocarbon group in which hydrogen atoms are partially substituted with fluorine atoms as a water-repellent group include 2,2 , 2-trifluoroethanol, hexafluoroisopropanol, 3-
Examples include aminobenzotrifluoride, pentafluoroaniline, trifluoroacetic acid, pentafluorobenzenecarboxylic acid, perfluoro-n-octanoic acid, perfluorohexyl-2-ethanol, and the like.

These compounds containing a water repellent group and at least one hydroxyl group, amino group or carboxyl group in the molecule are prepared by first reacting the hydroxyl group on the surface of paper fibers with a compound having two or more isocyanate groups in the molecule. After chemical bonding, the remaining isocyanate group is reacted with the hydroxyl group, amino group, or carboxyl group of the compound containing a water-repellent group to form a chemical bond, thereby achieving the desired chemical water-repellent treatment.

Examples of compounds containing two or more isocyanate groups in the molecule include paraphenylene diisocyanate, 2-chloro-1,4 phenyl diisocyanate, 2,
4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate,
Hexamethylene diisocyanate, diphenylmethane
4,4'-diisocyanate, 1,3-xylylene-4
, 6-diisocyanate, diphenyl sulfide-4
, 4'-diisocyanate, 1,4-naphthalene diisocyanate, polymeric methylene diisocyanate,
Triphenylmethane triisocyanate, 1,3,6-
Examples include hexamethylene triisocyanate, tris(isocyanate phenyl) thiophosphate, and the like.

The chemical water repellency treatment method of the present invention is characterized by reacting the hydroxyl groups on the surface of paper fibers with an isocyanate-containing compound in an organic solvent to form a chemical bond. Examples of organic solvents include N-methyl-2-pyrrolidone, benzonitrile, nitrobenzene, acetophenone, o-dichlorobenzene, N,N'-
Examples include dimethylaniline and anisole.

The temperature at which this reaction is carried out varies depending on the solvent used and the type of isocyanate, but the temperature ranges from room temperature to 2.
It can be carried out in the range of 00°C, preferably 80 to 16
Performed at 0°C.

The concentration of isocyanate used in this reaction varies depending on the solvent used and the amount of hydroxyl groups on the paper fiber surface, but it can be carried out in the range of about 0.01 to about 100 mol/l, but if it is too thin, The reaction takes a long time, and if it is too concentrated, the amount of isocyanate that does not participate in the reaction will increase, so it is desirable to select it appropriately, preferably from 0.1 to 1.
A range of 0 mol/l is preferable.

The amount of isocyanate used in the reaction depends on the amount of hydroxyl groups on the paper fiber surface and the amount of free water, but it is desirable to use a sufficiently excess amount of isocyanate. In addition, the time required for this reaction depends on temperature, concentration,
It is preferable to carry out the reaction over several tens of minutes to several hours until the reaction between the isocyanate and the hydroxyl groups on the surface of the paper fibers is completed, although it varies depending on the solvent used and the intensity of stirring.

[0026]

[Examples] The present invention will be explained in more detail with reference to Examples below.

(Example 1) Well-dried general analytical filter paper (20 x 20 x 0.5 mm) was placed in a 500 ml separable flask.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 4.1 g (30 mmol) of 4-fluorophenyl isocyanate to this and heat to 80°C.
The mixture was stirred for an hour to react with the paper pieces. Then put the piece of paper in N,
Soxhlet extraction with N'-dimethylformamide, washing, and drying at 80°C under a reduced pressure of about 1 mmHg in a vacuum dryer.
It was dried for 4 hours.

(Example 2) Well-dried general analytical filter paper (20 x 20 x 0.5 mm) was placed in a 500 ml separable flask.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. To this, 5.6 g (30 mmol) of isocyanate-α,α,α-trifluoro-m-tolyl was added,
The mixture was heated to 80° C. and stirred for 4 hours to react with the paper pieces. Thereafter, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried at 80 DEG C. for 24 hours under a reduced pressure of about 1 mmHg in a vacuum dryer.

(Example 3) Well-dried general analytical filter paper (20 x 20 x 0.5 mm) was placed in a 500 ml separable flask.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. 2 for this
, 2,2-trifluoroethanol 6.0g (60mm
ol), heated to 60°C, and stirred for 4 hours to react. Thereafter, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried in a vacuum dryer at about 1 mmH.
The mixture was dried at 80° C. for 24 hours under a reduced pressure of 100 g.

(Example 4) A well-dried general analytical filter paper (20 x 20 x 0.5 mm) was placed in a 500 ml separable flask.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. 1 for this
, 10.0 g (60 mmol) of 1,1,3,3,3-hexafluoro-2-propanol was added thereto, heated to 60° C., and stirred for 4 hours to react. Then put that piece of paper in N,N
' - Soxhlet extraction with dimethylformamide, washing, and drying at 80°C under a reduced pressure of about 1 mmHg in a vacuum dryer for 24 hours.
Dry for an hour.

(Example 5) Well-dried general analytical filter paper (20 x 20 x 0.5 mm) was placed in a 500 ml separable flask.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. 3 to this
- 9.7 g (60 mmo) of aminobenzotrifluoride
1) was added, heated to 60°C, and stirred for 4 hours to react. Thereafter, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried in a vacuum dryer at approximately 1 mmHg.
The mixture was dried at 80° C. for 24 hours under reduced pressure.

(Example 6) Well-dried general analytical filter paper (20×20×0.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. 2 to this
, 3,4,5,6-pentafluoroaniline at 11.0
g (60 mmol) was added thereto, heated to 60° C., and stirred for 4 hours to react. Thereafter, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried at 80 DEG C. for 24 hours under a reduced pressure of about 1 mmHg in a vacuum dryer.

(Example 7) A well-dried general analytical filter paper (20×20×0.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. Add 6.8g (60mmol) of trifluoroacetic acid to this and 60℃
and stirred for 4 hours to react. Thereafter, the paper strips were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried in a vacuum dryer under a reduced pressure of about 1 mmHg for 80 minutes.
It was dried at ℃ for 24 hours.

(Example 8) Well-dried general analytical filter paper (20 x 20 x 0.5 mm) was placed in a 500 ml separable flask.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. To this, 12.7 g (60 mmol) of pentafluorobenzoic acid was added, heated to 60° C., and stirred for 4 hours to react. Thereafter, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried at 80 DEG C. for 24 hours under a reduced pressure of about 1 mmHg in a vacuum dryer.

(Example 9) Well-dried general analytical filter paper (20×20×0.
Add 10 pieces of 5) and add 300m of N-methyl-2-pyrrolidone.
Added l. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
and stirred for 4 hours to react with the paper pieces. To this was added 24.8 g (60 g) of pentadecafluoro-n-octanoic acid.
mmol), heated to 60° C., and stirred for 4 hours to react. After that, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried in a vacuum dryer for about 1 m
It was dried at 80° C. for 24 hours under reduced pressure of mHg.

(Example 10) Well-dried general analytical filter paper (20 x 20 x 0
．． Add 10 pieces of 5) and add 300 N-methyl-2-pyrrolidone.
ml was added. Add 7.5 g (30 mmol) of diphenylmethane-4,4'-diisocyanate to this, and
℃ and stirred for 4 hours to react with the paper pieces. To this, add 21.8 g of perfluorohexyl-2-ethanol (
60 mmol) was added, heated to 60° C., and stirred for 4 hours to react. Thereafter, the paper pieces were washed by Soxhlet extraction with N,N'-dimethylformamide, and dried at 80 DEG C. for 24 hours under a reduced pressure of about 1 mmHg in a vacuum dryer.

[0037]

Effects of the Invention: Paper pieces chemically treated by the treatment method of the present invention exhibited water repellency, confirming the effectiveness of the present invention.

Claims (2)

[Claims] Claim 1: At least 2 hydroxyl groups present in the paper
Reacting a compound having more than 1 isocyanate group,
A compound that forms at least one urethane bond, leaves at least one isocyanate group, has a relatively small molecular weight, has a water repellent function, and has at least one hydroxyl group is added to the remaining isocyanate group. A method for treating paper to make it water repellent, which is characterized by causing a reaction to form a urethane bond. Claim 2: At least one hydroxyl group exists in the paper.
1. A method for treating paper to make it water repellent, which comprises reacting a compound having a group having a water repellent function with a relatively small molecular weight with a compound having a group having a water repellent function and having a relatively small molecular weight to form a urethane bond.