JPH11107191A - Impregnated paper with high water resistance and rigidity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject impregnated paper high in dimensional stability, durable even under severe waterproof conditions, and alternative to metallic aluminum used in drink and food cans, by impregnating a sheet of paper with a specific impregnant bearing a combination of both organic and inorganic material characteristics. SOLUTION: This impregnated paper is obtained by impregnating a sheet of paper with an impregnant (described below) which is prepared by reaction of a dicarboxylic acid anhydride of formula II (R4 is a 1-8C alkyl or the like) with the hydroxyl group of a cellulose carboxylic acid diester of formula I (R1 is OH or any of various ester groups described below; R2 and R3 are each a 2-4C lower alkyl ester group, nitric ester group or the like; the overall ester group substitution degree is 2.0-2.7; (n)>=10) to introduce reactive carboxyl group into the above diester followed by reaction of a silane coupling agent of formula III (R5 to R7 are each a 1-4C alkyl; R8 is glycidyl or the like), and then carrying out hydrolysis-condensation of the alkoxysilyl group site to obtain the above aimed impregnant of formula IV ((m) is >=1; R9 is a compound portion having such a structure that the epoxy groups are subjected to ring opening polymerization).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper impregnated with an organic-inorganic composite material, and more particularly to an impregnated paper having excellent water resistance and rigidity.

[0002]

2. Description of the Related Art Polyolefin resins, aromatic polyester resins, and the like, which are consumed in a large amount in daily life, are materials derived from petroleum, which is a finite resource, and have a problem of increasing garbage year by year. Similarly, aluminum beverages and food cans, which are consumed in large quantities, require water resistance and rigidity that can withstand the heat treatment process of sterilization, so aluminum is mainly used. There is a concern about the cost of recycling and environmental pollution due to throwing away at resorts.

[0003] Under such circumstances, attention has been paid to material systems with low environmental and resource loads. Paper is a natural renewable resource due to the active reforestation business, and a wide range of recycling is possible. In recent years, waste paper has been actively reused in the papermaking industry, and even if it is combined with other combustible waste, it can be converted into energy by thermal recycling. I have.

[0004] However, the structure of paper is a structure in which cellulose molecules are hydrogen-bonded, and is inherently weak to water and poor in rigidity.
This is because the constituent fibers of the paper are connected by hydrogen bonds, and the hydrogen bonds are easily broken by water. Also, paper is easy to burn. In the field of building materials, paper is typically used as wallpaper, but is required to have water resistance, flame retardancy, and weather resistance. In recent years, the generation of harmful substances due to the burning of wallpaper has become a problem, but this is due to additional components contained in adhesives and paper.

As a method for improving the drawbacks of these papers,
Conventionally, when water repellency is improved, it is often bonded to plastic or aluminum, but this is not an essential improvement in water resistance of paper. As a method of imparting and improving water resistance by coating or impregnating the paper itself, there is a method of coating an epoxy resin, a melanin resin, a urethane resin, or adding an aridylin compound or ethylene urea as a crosslinking agent. In many cases, the rigidity is insufficient. Furthermore, these impregnated papers or coated papers may have materials that are not suitable for waste paper recycling treatment, that is, materials that cannot be alkali-hydrolyzed, or have contents that adversely affect recycled paper.

[0006] In the application of various resin systems, or the improvement of the physical properties of paper by internal addition or impregnation methods, in terms of water resistance, if the paper is put in, for example, boiling water, it often causes peeling at the interface with the paper. . This is considered to be mainly due to the low affinity between cellulose, which is a component of paper, and various resins.

What is considered to have the highest affinity for paper is, of course, the component cellulose. (As an internal additive used as a paper strength enhancer, a drug with a strong affinity for cellulose molecules, a component of paper, is used. Among them, cellulose derivatives such as carboxymethylcellulose and hydroxymethylcellulose are used. ). Cellulose is an environment-friendly natural renewable resource as described above. Since cellulose is a material that responds to recent oil and environmental pollution problems, cellulose-based resins, that is, cellulose derivatives, are used in paper. Is considered most appropriate in terms of affinity with

In addition, a silane-based inorganic material containing an alkoxy group which is abundant in resources and has a low environmental load as an impregnating agent for imparting strength to paper forms a strong siloxane bond capable of alkaline hydrolysis. Attention is drawn from doing. As a conventional concrete method, there is a method of impregnating paper with a mixture of a urethane resin solution and silica-based fine particles having a particle size of 0.02 to 10 μm to improve water resistance. Interaction is mainly hydrogen bonds between hydrogen atoms and oxygen atoms and cannot be said to be a strong bond. Cellulose and silica, which are the components of paper, have different dimensional stability due to different behavior against external factors such as water and heat. Often low.

[0009] Therefore, by the organic-inorganic hybridization by complexing various cellulose derivatives with organoalkoxysilane, the characteristics of inorganic substances (high heat resistance, high flame retardancy, high elastic modulus, high strength, high corrosion resistance, high weather resistance, High solvent resistance, high density) and organic characteristics (high flexibility, high moldability, low density)
Recently, research and development of composite materials having both of these have been performed in various fields.

Hitherto, many organic / inorganic composite materials have been studied among synthetic polymers, for example, a composite material having a urea bond with polyarylene ether ketone and an isocyanate-containing silane coupling agent, Contact lens materials have been made by polymerizing, copolymerizing vinyl acetate and vinyl triethoxy silane, and epoxy silane and methacryloxy silane, as well as alkoxy titanium and methacrylate, and curing.

There have been few reports on the complexation of various cellulose derivatives with metal alkoxides. Among them, the sol-gel method by mixing (blend) is common, and the main interaction is the hydroxyl group of the cellulose derivative. It is a material system that is considered to be a hydrogen bond of a siloxane bond with some functional groups of a silanol group and a cellulose molecule directly reacting with the organic carbon of the organosilane as in the present invention. There is almost no clear example of a material system in which a functional group and a functional group of a cellulose derivative are combined by a covalent bond in which the functional group has reacted, and a material system based on copolymerization of radically polymerizable silicon and cellulose acetate has been reported.

[0012]

Under these circumstances, impregnation for imparting water resistance and strength, which are drawbacks of paper, which has been increasing in demand in recent years due to a small load on resources and the environment, has been proposed. As an agent, an agent using an alkoxysilane, which also has a low resource and environmental load, has been reported.
The interaction with the cellulose molecule, which is a component of the paper, is weak due to only hydrogen bonding and lacks dimensional stability. In addition, since it is a mixture (blend) rather than a composite, brittleness, which is a drawback of inorganic materials, occurs. However, few reports have been made on hybrid materials with cellulose derivatives for the purpose of improving physical properties such as water resistance and strength of paper.

An object of the present invention is to provide a composite material having the characteristics of an organic / inorganic material by forming a derivative of a cellulose molecule, which is a component of paper, and an organosilane through a covalent bond between organic functional groups. To improve the water resistance, hardness and rigidity, flame retardancy, heat resistance, weather resistance, solvent resistance, and because the main component of the impregnating agent is a cellulose derivative, the affinity with paper increases. An object of the present invention is to provide an impregnated paper which has excellent dimensional stability and can withstand severe water-resistant conditions.

[0014]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, have added or graft-polymerized a functional group of a cellulose derivative and a functional group of an organosilane to form a novel composite. Having arrived at the invention of a functional cellulose derivative, by using it as an impregnating agent for paper, it had both inorganic and organic characteristics, that is, water resistance,
A functional paper excellent in rigidity, flame retardancy, heat resistance, dimensional stability, etc. could be provided. In addition, since the stem polymer of the impregnating agent is a cellulose derivative, from the enhancement of affinity with paper,
It is thought to have unprecedented water resistance.

That is, a first invention of the present invention is to react a hydroxyl group of a cellulose carboxylic acid diester represented by the general formula [Chemical Formula 1] with a dicarboxylic anhydride represented by the general formula [Chemical Formula 2], Introducing a reactive carboxyl group,
Using the diesterified cellulose dibasic acid ester represented by the general formula [Chemical Formula 3], the functional group (in -R ₈ ) of the silane coupling agent as shown by the general formula [Chemical Formula 4] is polymerized or 2 Under a reaction condition of copolymerization of more than one kind, the functionalized cellulose derivative is reacted with a carboxyl group of a cellulose derivative, and a silane coupler represented by the general formula [Formula 5] is added or graft-polymerized. This is an impregnated paper having excellent water resistance and rigidity using an impregnating agent having a siloxane network structure represented by the general formula [Chemical Formula 6] due to hydrolysis-condensation of the site.

According to a second aspect of the present invention, in the first aspect,
Adding a polyfunctional reagent that reacts with the functional group -R ₈ in the general formula [Formula 4] added, or graft polymerization reaction system, silane coupler represented by the general formula [Formula 7] is added, or by graft polymerizing A functional cellulose derivative is included, the site of the alkoxysilyl group is hydrolyzed and condensed, and an impregnated paper excellent in water resistance and rigidity using an impregnating agent having a siloxane network structure represented by the general formula [Formula 8] is used. is there.

According to a third aspect, in the first and second aspects, the siloxane network structure is formed by hydrolysis-condensation of an alkoxysilyl group, and p-toluenesulfonic acid dihydrate is used as a catalyst. It is an impregnated paper which is excellent in water resistance and rigidity of a silane coupler grafted cellulose derivative using a Japanese product.

That is, the main feature of the silane coupler graft polymerized cellulose derivative according to the present invention is that, after impregnation on paper, an alkoxy group ([Chem. 5]; -OR ₄ , -OR ₅ ,- OR ₆ )
It cures to form a strong, flame-retardant, heat-resistant siloxane network, and the graft-polymerized cellulose derivative imparts flexibility, a characteristic of organic materials, and reduces brittleness, which is a disadvantage of siloxane bonds. Supplements.
Further, since the impregnating agent according to the present invention has cellulose molecules as a component of paper in the basic skeleton, the affinity with paper is increased and the dimensional stability is improved. further,
Since it has a siloxane three-dimensional structure, it has excellent weather resistance and solvent resistance.

These facts indicate that when a PET film or the like is coated with a wire bar, if it is simply an alkoxysilane, the coating film condensed by hydrolysis cannot be formed in a dispersed state. It is also evident from the fact that the coating film obtained by similarly condensing the silane coupler graft-polymerized cellulose derivative by hydrolysis can be uniformly formed and is insoluble in a solvent.

The impregnated paper according to the present invention, which is excellent in water resistance and rigidity corresponding to the environment, is constituted by a material system having a small load on resources and environment, and has improved and improved the defects of the physical properties of the paper. Things. That is, a cellulose derivative, which is considered to have the highest affinity for paper, is used as a trunk polymer, a silane coupling agent is grafted to the polymer through an organic covalent bond, and after impregnating the paper, hydrolysis of an alkoxysilane group with an acid is performed. It is an impregnated paper having a siloxane three-dimensional structure by condensation. As a result, it has the properties of both inorganic and organic substances, greatly improves the water resistance, which has been considered a drawback of paper, and improves the hardness and rigidity, as well as the flame retardancy, heat resistance, weather resistance, and solvent resistance. Is to be granted.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The raw material of cellulose as a trunk polymer of the present invention may be cellulose of higher plants, ie, LBKP (conifer pulp) or NBKP (hardwood pulp), or cotton linter derived from cotton.

The cellulose derivative of [Chemical Formula 1] is synthesized by a known method. [Chemical Formula 2] Since the reaction with dicarboxylic anhydride has a strong tendency to react with the hydroxyl group at the 6th position in the cellulose skeleton, It is considered that the carboxylic acid ester can be easily manipulated. The reason is that dicarboxylic acid-esterified cellulose is synthesized by hydrolyzing tricarboxylic acid-esterified cellulose.
This is because the position returns to the hydroxyl group. Nitro (nitrate ester)
In the case of cellulose, the degree of substitution is often controlled by the nitric acid mixed acid composition ratio and the reaction time, and the sixth position is not necessarily a hydroxyl group, but is a nitrate ester group, and the second and third positions are hydroxyl groups. Is included in the whole structure,
Since the hydroxyl group at the 3rd or 3rd position is much lower in reactivity than the hydroxyl group at the 6th position, it is considered that it does not react with the dicarboxylic anhydride as described above. Therefore, as shown in claim 1, only the hydroxyl group at the sixth position is shown. Also,
As an advantage of nitrocellulose, since it is soluble in various solvents, the silane coupler graft polymerized cellulose derivative of the present invention has an effect of improving the solvent solubility. Introduction of a carboxyl group by reaction with a dicarboxylic anhydride has the purpose of providing a functional group having high steric reactivity. In this case, (R ₄ ) of [Formula 2] in the first invention
In the malonic acid monoesterified compound having n = 1, there is a tendency that steric reactivity is insufficient and a reaction does not easily occur. Desirably, the monoester of malonic acid having n = 2 or more or aromatic dicarboxylic acid monoester Is suitable. The degree of substitution of various ester groups is determined in consideration of reactivity and physical properties of impregnated paper.
S. = 2.0 or more and 2.7 or less is considered desirable.

In the silane coupling agent of the formula (4), -R ₈
The site is a reactive functional group, an epoxy cyclohexyl group, an aliphatic group containing an epoxy group such as a glycidyl group,
Alternatively, it is desirably an aromatic group. The reaction between the diesterified cellulose dibasic ester of [Chemical Formula 3] and the silane coupling agent of [Chemical Formula 4] is a homogeneous reaction system using a solvent, and the polymerization method is a known method suitable for each functional group. Examples include condensation with acids and bases, ring-opening polycondensation, ionic polymerization, and the like. It is preferable that the conditions be such that the alkoxy group is not hydrolyzed and condensed to form a siloxane network.

As the polyfunctional reagent of the present invention, a reagent which reacts with a functional group (-R _{8 of} [Chemical Formula 4]) of a silane coupling agent is preferable, and a bifunctional reagent which does not gel is desirable. Specifically, an aziridine compound, an epoxide compound such as epichlorohydrin or diglycidyl ether, a diisocyanate such as toluylene diisocyanate, or an asymmetric bifunctional reagent having two functional groups having different reactivities may be used.

The conditions under which the alkoxy group of the silane coupling agent, which is the main component of the impregnating liquid according to the present invention, is hydrolyzed to form a siloxane bond by condensation by heat treatment are generally those of the sol-gel method. From the knowledge, condensation starts under conditions of pH = 4 or less or pH = 10 or more using an acid or an alkali. Specifically, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid and the like can be used as the acid. As the alkali, ammonia or hydroxyamine that can be removed by volatilization after the treatment can be used. In the impregnating liquid of the present invention,
This catalyst has a feature of using p-toluenesulfonic acid dihydrate. Since the catalyst is an organic Brönsted acid, the solvent of the impregnating solution can be unified with an organic solvent. In addition, the hydrolysis of the alkoxy group of the impregnating agent is affected by the moisture in the air, but the main component is the two molecules of crystal water coordinated to p-toluenesulfonic acid. It is considered that hydrolysis occurs, and the stability of the coating liquid is considered to be good. Further, since the solvent of the impregnating liquid can be unified with only the organic solvent, the solid content ratio (NV) can be increased.

Further, the cellulose derivative to which the silane coupling agent, which is the impregnating agent according to the present invention, is grafted is solid and has a characteristic as a silane coupling agent. All are liquids, and the impregnating agent has the advantage of easy handling. In addition, the grafted cellulose derivative is used at a temperature of 100 ° C to 1 ° C.
Even if left for about 1 hour in an environment at 20 ° C., it does not easily condense and is stable. However, about one month under high temperature and humidity,
If left as it is, condensation occurs and gelation occurs, but it is considered that there is no inferiority to the stability of a normal silane coupling agent.

In the method for producing an impregnated paper according to the present invention, a silane coupler graft polymerized cellulose derivative is dissolved in an organic solvent to prepare an impregnating liquid. Here, the organic solvent used is not particularly limited as long as it dissolves the silane coupler graft-polymerized cellulose derivative, but a solvent having a very high volatility (low boiling point) in consideration of the stability of the coating liquid as the impregnating liquid. Is not preferred. Further, it is desirable to use one that is less harmful to the human body. Specifically, ethers such as tetrahydrofuran and dioxane, alcohols such as ethanol and propanol, ketones such as acetone and methyl ethyl ketone, aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate Or a mixture thereof.

The paper used in the present invention includes Japanese paper, imitation paper, nonwoven fabric, high quality paper, art paper, coated paper, pure white roll paper, vertiment paper, kraft paper, or jute liner, kraft liner, coated paper for cardboard. Liners and the like.

Next, as a method of applying the impregnating agent according to the present invention, a usual low coating method, doctor blade coating method, knife edge coating method, curtain coating method, gravure coating method, bar coating method, reverse coating method, etc. Law,
Impregnation coating can be performed using any of the kiss coat method and the like. The application speed and drying conditions are not particularly limited, but it is preferable to perform the application within a range that does not adversely affect the paper and the impregnating liquid of the support.

The effective impregnating amount of the impregnating agent according to the present invention on the paper substrate is usually 1 to 25 g / m ² , and the standard is 2 g / m 2.
/ M ² (based on dry weight) with a very low impregnation amount of about 0.6%, corresponding to an impregnation ratio in paper (% by weight of dry impregnating agent with respect to the base paper), and excellent water resistance, hardness and rigidity of the paper And so on. Of course, the water resistance, hardness and rigidity are further improved by increasing the impregnation amount. And, by increasing the content of the siloxane network in the paper, flame retardancy and heat resistance are also provided. The amount of impregnation or coating was determined by placing the base paper and the impregnated paper in an electric dryer at 120 ° C. for 2 hours to make them completely dry, and subtracting the weight of the base paper having the same area from the impregnated paper.

[0031]

Next, the present invention will be described more specifically based on examples.

<Example 1> (Examples 1 and 2 are examples of production of a composite of nitrocellulose monophthalate and an epoxycyclohexyl group-containing silane coupling agent) First, an impregnation stock solution for impregnating base paper is prepared. . 10 g (β
Mol concentration of -1,4 glucose units; about 25 mmol
l) Nitrocellulose monophthalic ester (Asahi Kasei Kogyo Co., Ltd., trade name; CELNOVA BTK-1 / 8) is dissolved in acetonitrile (100 ml), and 6.16 g of 2 corresponding to an equimolar equivalent of the carboxylic acid equivalent of the cellulose derivative is obtained. -(3,4-Epoxycyclohexyl) ethyltrimethoxysilane (trade name; S530, manufactured by Chisso Corporation)
And SnCl ₂ was used as a catalyst for ring-opening and crosslinking of epoxy groups.
A solution prepared by dissolving (stannous chloride) in methanol at a concentration of 0.0003 mol / g was added to the cellulose derivative in an amount of 0.0005 mol, and the mixture was reacted at about 80 ° C. for 30 minutes while stirring with a stirrer. One of the silane coupler grafted cellulose derivatives according to the invention was produced.

This silane coupler grafted cellulose derivative was added to ethyl acetate in a solid content ratio (NV) = 10 w
t%, and a curing agent (manufactured by Toyo Ink Mfg. Co., Ltd., 50 wt% containing p-toluenesulfonic acid dihydrate)
An isopropanol solution) was added and stirred, and a non-clay surface of coated ivory having a basis weight of 320 g / m ² manufactured by Nippon Paper Industries Co., Ltd. was dried at ² g / m ^{2 with} a wire bar using a wire bar.
² and dried at 120 ° C. for 1 minute to obtain an impregnated paper of Example 1.

Example 2 Grafting 2- (3,3
4-Epoxycyclohexyl) ethyltrimethoxysilane (trade name; S530) The silane according to the present invention in the same manner as in Example 1 except that the amount of addition was twice as much as the carboxylic acid equivalent of the cellulose derivative. One of the coupler-grafted cellulose derivatives was prepared, and the resulting silane coupler-grafted cellulose derivative was added to ethyl acetate in a solid content ratio (N.V.) = 1 as in Example 1.
0 wt%, and a curing agent (powder containing Toyo Ink Manufacturing Co., Ltd., p-toluenesulfonic acid dihydrate 50 w
t% isopropanol solution) and stirred to give a coat ivory (basis weight: 320 g, manufactured by Nippon Paper Industries Co., Ltd.).
/ M ² ) Non-clay surface has a wire bar with a dry weight of 2 g
/ M ² and dried at 120 ° C. for 1 minute to obtain an impregnated paper of Example 2.

The addition amount of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (trade name: S530) to be grafted was increased to 3 times the carboxylic acid equivalent of the cellulose derivative. In the same manner as in Example 1, one of the silane coupler-grafted cellulose derivatives according to the present invention was produced.

Since the gelation occurred when the amount of the silane coupling agent to be grafted was increased, it is considered that the cellulose derivatives were cross-linked by the silane coupling agent. From this, it was found that the use of the impregnating agent by complexing the silane coupling agent in the present reaction system had a limit of twice the mol of the carboxylic acid equivalent of the cellulose derivative.

<Comparative Example 1> The base paper used in Examples 1 and 2 in which the impregnating liquid according to the present invention was not applied was used as Comparative Example 1.

<Comparative Example 2> 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (trade name: S530) which is a raw material of the impregnating agent according to the present invention was used as a catalyst for ring-opening polymerization of epoxy group by using SnCl _2. (Stannous chloride)
Was dissolved in methanol at a concentration of 0.0003 mol / g to 0.0005 mol of the silane coupling agent.
number average molecular weight Mn =
A polymer of about 15,000 (in terms of polystyrene) is dissolved in ethyl acetate at a solid content ratio (N.V.) of 10 wt%, and a curing agent (p-toluenesulfonic acid dihydrate, manufactured by Toyo Ink Mfg. Co., Ltd.) A 50% by weight isopropanol solution containing a sump) was added and stirred, and a non-clay surface of coated ivory (basis weight: 320 g / m ² ) manufactured by Nippon Paper Industries Co., Ltd. was dried to 2 g / m ² with a wire bar using a wire bar. And dried at 120 ° C. for 1 minute to obtain an impregnated paper of Comparative Example 2.

Example 3 (Examples 3 and 4 are examples of production of a composite of nitrocellulose monophthalate and a glycidyl group-containing silane coupling agent) First, an impregnation stock solution for impregnating base paper is prepared. In a 300 ml three-necked flask, 10 g (mol concentration of β-1,4 glucose unit; about 25 mmol) of nitrocellulose monophthalate (Asahi Kasei Kogyo Co., Ltd., trade name; Cellnova BTK-1 / 8) is dissolved in 100 ml of acetonitrile. Then, 11.8 g of 3-glycidoxypropyltrimethoxysilane (manufactured by Chisso Corporation, trade name: S510) corresponding to twice the mol of the carboxylic acid equivalent of the cellulose derivative was charged, and used as a catalyst for ring-opening and crosslinking of epoxy groups. Boron trifluoride methanol complex (BF ₃
2CH ₃ OH) to the cellulose derivative at 0.000
5 mol amount, and while stirring with a stirrer, about 80
The reaction was carried out at 30 ° C. for 30 minutes to produce one of the silane coupler grafted cellulose derivatives according to the present invention.

This silane coupler grafted cellulose derivative was added to ethyl acetate in a solid content ratio (NV) = 10 w
t%, and a curing agent (manufactured by Toyo Ink Mfg. Co., Ltd., 50 wt% containing p-toluenesulfonic acid dihydrate)
An isopropanol solution) was added and stirred, and coated with a wire bar on a surface of kraft paper having a basis weight of 310 g / m ² manufactured by Utsunomiya Paper Co., Ltd. so that the absolute dry weight was 2 g / m ^2. Drying at 1 ° C. for 1 minute gave an impregnated paper of Example 3.

Example 4 Grafted 3-glycidoxytrimethoxysilane (trade name S5, manufactured by Chisso Corporation)
One of the silane coupler-grafted cellulose derivatives according to the present invention was produced in the same manner as in Production Example 1, except that the addition amount of 10) was increased to 3 times the mol of the carboxylic acid equivalent of the cellulose derivative, In the same manner as in Example 3, the obtained silane coupler grafted cellulose derivative was dissolved in ethyl acetate at a solid content ratio (N.V.) of 10 wt%, and a curing agent (p-toluene sulfone, manufactured by Toyo Ink Mfg. Co., Ltd.) Acid dihydrate-containing 50 wt% isopropanol solution) was added and stirred to a kraft paper having a basis weight of 310 g / m ² manufactured by Utsunomiya Paper Co., Ltd., and the absolute dry weight was 2 g / m ² with a wire bar. Coating to become 1
After drying at 20 ° C. for 1 minute, an impregnated paper of Example 4 was obtained.

The grafted 3-glycidoxytrimethoxysilane (trade name S51, manufactured by Chisso Corporation)
One of the silane coupler-grafted cellulose derivatives according to the present invention was produced in the same manner as in Example 1 except that the added amount of 0) was increased to 4 times the mol of the carboxylic acid equivalent of the cellulose derivative. This was gelled due to insolubility of the solvent.

Since the gelation occurred when the amount of the silane coupling agent to be grafted was increased, it is considered that the cellulose derivatives were cross-linked by the silane coupling agent. From this, it was found that the use of the impregnating agent by complexing the silane coupling agent in the present reaction system had a limit of 3 times mol to the carboxylic acid equivalent of the cellulose derivative.

Comparative Example 3 The base paper used in Examples 3 and 4 in which the impregnating liquid according to the present invention was not applied was used as Comparative Example 3.

<Comparative Example 4> 3-Glycidoxypropyltrimethoxysilane (trade name S510, manufactured by Chisso Corporation), which is a raw material of the impregnating agent according to the present invention, was used as a catalyst for ring-opening and crosslinking of epoxy groups. A number-average molecular weight Mn of about 1,0 was obtained by adding 0.0005 mol of a boron fluoride methanol complex (BF ₃ .2CH ₃ OH) and reacting with stirring.
00 (polystyrene equivalent) oligomer (trimer to pentamer)
Which is added to ethyl acetate in a solid content ratio (N.V.).
= 10 wt%, and a curing agent (50% by weight containing p-toluenesulfonic acid dihydrate, manufactured by Toyo Ink Mfg. Co., Ltd.)
(Isopropanol solution) and agitated kraft paper (basis weight: 310 g / m ² ) manufactured by Utsunomiya Paper Co., Ltd.
Was coated with a wire bar so as to have a dry weight of 2 g / m ² and dried at 120 ° C. for 1 minute to obtain an impregnated paper of Comparative Example 4.

<< Test 1 >> (Test for Evaluating Strength and Rigidity of Impregnated Paper) In order to evaluate the paper strength and rigidity of the six types of impregnated paper and the two types of base paper (blank), JIS P8125 “Paperboard by the load bending method” "Bending stiffness tester BST-1" manufactured by Yoshizawa Industries Co., Ltd.
50M ". The measuring method is as follows. Cut the paper sample in parallel to the coating direction to 6 cm long x 4 cm wide,
The yield value (gf) and the angle at that time (initial gradient; deg) were obtained by fixing one end of the paper and bending the center of the paper under the environment of C. The yield value is considered to evaluate the hardness of the paper, and the initial gradient is considered to evaluate the rigidity. Table 1 shows the measurement results.

[0047]

[Table 1]

Considering from Table 1, it can be seen that the impregnated paper (Comparative Examples 2 and 4) having a three-dimensional structure of siloxane by a silane coupling polymer alone not complexed with a cellulose derivative, and the silane coupling of the present invention. Paper having a three-dimensional structure of siloxane inside with an impregnating agent for a composite material in which an agent and a cellulose derivative are covalently bonded (Example 1,
Comparing the physical properties of Example 2 and Examples 3 and 4), when the coating amount was very small, ie, about 2 g / m ² ,
It can be seen that the impregnated paper of the present invention has clearly improved both hardness and rigidity, whereas the impregnated paper of the present invention has no improvement in physical properties with respect to the base paper (Comparative Examples 1 and 3). This is presumably because the silane coupler grafted cellulose derivative according to the present invention, which has improved affinity for paper, as well as siloxane bonds, which is thought to provide strength to paper, provided higher strength.

<< Test 2 >> (Test of Water Absorption and Water Repellency of Impregnated Paper) JISP 8140 "Method of Testing Water Absorption of Paper and Paperboard (Cup Method)" to evaluate the surface water absorption and water repellency of the prepared samples And JISP8137 "Method of testing water repellency of paper and paperboard". According to this method, the improvement effect of the impregnated paper on the low water resistance, which is an inherent disadvantage of the paper, can be measured. Table 2 shows the measurement results.

[0050]

[Table 2]

From Table 2, it can be seen that the impregnated papers of Examples 3 and 4 of the present invention have improved water absorption and water repellency compared to the base paper of Comparative Example 3. Although low water absorption and high water repellency were expected from the water repellency of the organic portion of Comparative Example 4 which was the impregnated paper of the silane coupling agent polymer, the impregnated paper of the present invention (Examples 3 and 4) Showed a higher value. Further, the effect of further decreasing the water absorption as the amount of grafting of the silane coupling agent was increased from Examples 3 to 4 was observed.

<< Test 3 >> (Boiling Water Resistance Test of Impregnated Paper) As the evaluation of the water resistance of the impregnated surface of the prepared sample, the boiling water resistance was evaluated by referring to JIS K5400 “General test of paint: 8.20 boiling water resistance”. The same test was conducted except that the temperature was 30 minutes in boiling water. Table 3 shows the evaluation results. In the table, ○ indicates good, Δ indicates slightly good, and × indicates bad.

[0053]

[Table 3]

Considering from Table 3, it can be seen that Examples 1 and 2,
The silane coupler-grafted cellulose derivative-impregnated papers of the present inventions 3 and 4 have very small coating amounts,
It has been found that the silane coupler-grafted cellulose derivative according to the present invention has a good boiling water resistance and no delamination of the impregnated paper, and also acts as a paper strength enhancer due to the high affinity for paper of the silane coupler-grafted cellulose derivative according to the present invention. In the impregnated papers of the silane coupling agent polymers of Comparative Examples 2 and 4, the impregnated surface did not change much, but delamination occurred. This suggests that the silane coupler-grafted cellulose derivative-impregnated paper of the present invention has further improved water resistance by increasing its coating amount or by impregnating the paper with all layers.

[0055]

The silane-coupler-grafted cellulose derivative-impregnated paper of the present invention is composed of a material system that does not impose an environmental burden, that is, the functional group of the cellulose derivative reacts with the functional group of the organosilane to form an organic material. It is formed by covalent bonding and impregnated with a hybridized functional cellulose derivative having an alkoxysilane group. After impregnation, the alkoxysilane group is hydrolyzed and condensed to form a strong siloxane network. Thereby, the strength and rigidity of the paper are improved, and the water absorption and the water repellency are also improved, that is, the water resistance is excellent. Further, since it is a hybrid material with a cellulose derivative, flexibility, which is a disadvantage of a siloxane bond, is also improved. Furthermore, since cellulose molecules, which are constituents of paper, are used as the trunk polymer, they have high affinity with paper, have excellent dimensional stability, and have unprecedented water resistance. Therefore, the silane coupler-grafted cellulose derivative-impregnated paper of the present invention is a paper excellent in water resistance and rigidity that can be substituted for aluminum used for beverage cans and food cans, and subjected to severe water resistance conditions such as retort sterilization treatment. It is suitable as paper that can withstand below.

Claims (3)

[Claims] 1. A compound of the general formula In the hydroxyl groups of cellulose carboxylic diesters, which are cellulose derivatives represented by the formula, (wherein R ₁ is hydrogen or various ester groups described below, and R ₂ and R ₃ are the same or different carbon atoms. Compounds such as lower alkyl ester groups, nitrate ester groups, nitrite ester groups, monochloroacetic acid ester groups, mercaptoacetic acid ester groups, and cinnamic acid ester groups of Formulas 2 to 4, wherein the total degree of ester group substitution is DS. = 2.0 or more and 2.7 or less, and n represents 10 or more. Wherein a reactive carboxy group is introduced by reacting a dicarboxylic anhydride represented by the formula (wherein R ₄ represents an aromatic compound such as an alkyl group having 1 to 8 carbon atoms or a phthal group). Using a diesterified cellulose dibasic acid ester represented by the general formula: The functional group of the silane coupling agent (-
R ₈ is polymerized or reacted with a carboxyl group of a cellulose derivative under the reaction conditions of copolymerization of two or more types, wherein R ₅ , R ₆ and R ₇ are the same or different and have different carbon numbers. 1-4 lower alkyl group, R ₈ is an epoxycyclohexyl group, to a compound having an epoxy group such as glycidyl group) general formula 5] A functional cellulose derivative to which a silane coupler represented by the following is added or graft-polymerized is included, and a site of an alkoxysilyl group is hydrolyzed and condensed to give a general formula: An impregnated paper having excellent water resistance and rigidity, characterized by using an impregnating agent having a siloxane network structure represented by the formula: (In the formula, m represents 1 or more, and R ₉ represents a compound having a structure obtained by ring-opening polymerization of an epoxy group.) 2. A polyfunctional reagent which reacts with the functional group -R _{8 of the} general formula [Chemical Formula 4] is added or added to a graft polymerization reaction system. Embedded image or a functionalized cellulose derivative to which a graft polymerization has been added, and a site of an alkoxysilyl group is hydrolyzed and condensed to give a compound represented by the general formula: The impregnated paper having excellent water resistance and rigidity according to claim 1, wherein an impregnating agent having a siloxane network structure represented by the following formula is used. (In the formula, R ₁₀ represents a structure in which a compound having a difunctional dicarboxylic anhydride, an amino group, an epoxy group, an isocyanate group, or the like has reacted.) 3. The siloxane network structure is formed by hydrolysis-condensation of an alkoxysilyl group, and uses p-toluenesulfonic acid dihydrate as a catalyst. 2. The impregnated paper according to 2 which is excellent in water resistance and rigidity.