JP3405124B2 - Silane polymer impregnated paper - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an impregnated paper having excellent water resistance or rigidity.

[0002]

2. Description of the Related Art In recent years, research and development have been actively carried out all over the world for converting conventionally used living materials into materials that do not have an impact on the environment, from the heightened awareness of environmental protection. Materials that use synthetic polymers such as polyolefins and aromatic polyesters are used in large quantities because they are indispensable for daily life, and while paper-based materials that are less burdensome in terms of environment and resources are attracting attention. The demand is increasing more and more.

The materials for beverage cans and food cans that are consumed in large quantities require water resistance and rigidity that can withstand the heat treatment process of sterilization, so aluminum is mainly used, and recycling is performed by separating and collecting garbage. However, there are concerns about the cost of material recycling and environmental pollution such as throwing it away in recreation areas.

Under these circumstances, attention has been paid to papers that do not give an environmental load, and the demand for them is increasing year by year. Paper can be widely used for recycling. In recent years, recycled paper has been actively used in the paper manufacturing industry, and even if it is combined with other combustible waste, it can be converted into energy by thermal recycling. .

However, the structure of paper is a structure in which cellulose molecules are hydrogen-bonded, and is essentially weak to water and poor in rigidity. To improve water repellency, it is often laminated with plastic or aluminum, but this is not an essential improvement in water resistance of paper. As a method of imparting 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 it as a cross-linking agent such as an aziridine compound or ethylene urea. Is often insufficient.

Further, as a water resistant paper utilizing a composite with ceramics, a urethane resin solution has a particle size of 0.02 to 10
Some papers impregnate paper with a mixture of silica-based fine particles in the μm range, and some impregnate alkoxysilane or its silanol-condensed prepolymer to improve water resistance, but the interaction between paper and impregnant is mainly It is only a hydrogen bond between hydrogen atom and oxygen atom, and it cannot be said that it is a strong bond.Because the behavior of external constituents such as water and heat is different between the constituents of paper, cellulose and silica, the dimensional stability is often low. .

For example, when the impregnated paper composited with the above-mentioned ceramic is immersed in water, the hydrogen bond between the ceramic and cellulose is once broken, and when heated and dried in that state, phenomena such as curling and wrinkling may occur. .

Further, when the main component of the impregnating agent is polysiloxane, the siloxane bond is very strong and imparts hardness to the paper, but on the other hand, it is considered to be brittle like glass and lack in rigidity of paper.

[0009]

In the prior art, the effect of water repellency is more important than making the paper itself water resistant, and even in the case of chemicals that impart water resistance,
Insufficient rigidity or weak interaction between the impregnating agent and cellulose, which is a constituent of the paper, often causes the shape to change due to changes in the external environment. An object of the present invention is to provide an impregnated paper having water resistance and rigidity and excellent dimensional stability.

[0010]

Means for Solving the Problems As a result of earnest studies to achieve the above-mentioned problems, the inventors of the present invention gave water resistance and rigidity with a chemical agent that does not affect the environment, and By adding a cross-linking agent that binds a certain cellulose molecule and the impregnating agent with a strong interaction, the inventors have invented an impregnated paper excellent in dimensional stability.

That is, according to the first aspect of the present invention, the functional group (R ₁ ) represented by the general formula [Chemical Formula 1] is polymerized alone or copolymerized with two or more kinds of silane coupling agents. A silane polymer-impregnated paper containing an oligomer or a polymer, which is hydrolyzed and condensed to have a siloxane network structure represented by the general formula [Chemical formula 2].

A second invention is the same as in the first invention, wherein the oligomer or polymer is added at a position of R ₁ shown in the general formula [Chemical formula 1] as shown in the general formula [Chemical formula 3]. A structure polymerized with a functional reagent (R ₅ ) is included,
It is a silane polymer-impregnated paper characterized in that it is hydrolyzed and condensed to have a siloxane network structure represented by the general formula [Chemical formula 4].

A third invention is the same as the first and second inventions, wherein the siloxane network structure is produced by hydrolyzing and condensing an alkoxysilyl group,
It is a silane polymer-impregnated paper characterized by using p-toluenesulfonic acid dihydrate as a catalyst.

A fourth invention is the same as the first and second inventions, except that the silane polymer [Chemical formula 1] and [Chemical formula 3] are used.
Is a silane polymer-impregnated paper having a number average molecular weight of 500 to 50,000.

The fifth aspect of the present invention is the same as those of the first, second, third and fourth aspects, wherein the compound represented by the general formula:
It is a silane polymer-impregnated paper containing a mixture of hydroxymethylcarboxylic acids represented by.

That is, the main characteristics of the impregnated paper of the present invention are:
Alkoxy groups of the silane coupling agent as monomers; - and that (Formula _{1] OR 1, -OR 2,} -OR 3) condensation of which form a strong siloxane network in a paper done after impregnation the paper, The various functional groups (R ₄ ) of the silane coupling agent are crosslinked before impregnation. Therefore, the impregnated paper of the present invention includes a bond for imparting flexibility, in addition to the siloxane bond which is considered to be hard but to be brittle, on the other hand, the brittleness which is a defect of the siloxane network is supplemented.

This means that when an impregnating solution in which an impregnating agent is dissolved is applied to a polyester film or the like with a wire bar, when all the substituents are silane compounds having an alkoxy group, they are simply condensed by hydrolysis. A coating film cannot be formed, but a substituent (R ₄ ) other than the alkoxy group of the present invention
It is also clear from the fact that a coating film in which the impregnating agent obtained by polymerizing the above is similarly condensed by hydrolysis is formed. perhaps,
When the paper is impregnated, it is considered that the film is formed in the paper.

Further, since the portion of the impregnating agent of the present invention where R ₄ is polymerized is an organic compound, it is considered to have a water repellent effect.

Further, the impregnating agent of the present invention has the following simple composition.
To a condensate of alkoxysilane
Is lacking in flexibility and water repellency of [Chemical formula 1] and [Chemical formula 2]
-R _FourCan be controlled by the type of functional group of
It

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The R ₄ site of the silane coupling agent, which is the main component of the impregnating agent of the silane polymer-impregnated paper of the present invention, is a reactive functional group such as an amino group and an epoxycyclohexyl. Groups, glycidyl groups, vinyl groups, acrylic groups, aliphatic groups including isocyanate groups,
Alternatively, an aromatic group is desirable, and the impregnating agent according to the present invention is an oligomer or polymer in which the functional groups of these coupling agents are polymerized singly or in a combination of two or more kinds. Further, the polyfunctional reagent according to claim 3 other than the silane coupling agent may be polymerized. The polymerization method is a known method suitable for each functional group, such as condensation by acid or base, ring-opening polycondensation, ionic polymerization, free radical vinyl polymerization, cross-linking by high energy irradiation (gamma ray irradiation), cross-linking by UV irradiation, Crosslinking by plasma discharge treatment and the like can be mentioned, but it is preferable that the conditions are such that an alkoxy group is not hydrolyzed and condensed to form a siloxane network.

The conditions under which the siloxane bond can be formed by hydrolysis of the alkoxy group of the silane coupling agent, which is the main component of the impregnating agent according to the present invention, and condensation by heat treatment, are generally those of the sol-gel method. Based on the findings, p. H. Is 4 or less, or p. H.
Is 10 or more, condensation starts. Specifically, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid or the like can be used as the acid. As the alkali, ammonia, hydroxylamine or the like which can be removed by volatilization after the treatment can be used. The impregnating agent of the present invention is characterized in that the p-toluenesulfonic acid dihydrate according to claim 3 is used, and since the catalyst is an organic Bronsted acid, the impregnating agent is dissolved. The solvent of the liquid can be unified with the organic solvent. Further, the hydrolysis of the alkoxy group of the impregnating agent is also affected by the water content in the air, but the main thing is the water of crystallization of 2 molecules coordinated to p-toluenesulfonic acid, so at the same time as the catalytic effect during the heat drying treatment. 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 only by the organic solvent, the solid content ratio (N.V.) can be increased.

As the polyfunctional reagent, the functional group of the silane coupling agent (-R _{4 in} [Chemical Formula 1]) which is the main agent of the impregnating agent is used.
Those that react with are preferable, and since they are dissolved in an organic solvent before impregnation with paper, a bifunctional that does not gel is desirable. Specifically, the hydroxymethylcarboxylic acid compound according to claim 5, an active vinyl compound, an aziridine compound, an epoxide compound such as epichlorohydrin, an acid anhydride such as succinic anhydride and phthalic anhydride, and toluylene diene. A diisocyanate such as an isocyanate and an asymmetric bifunctional reagent having two functional groups having different reactivity may be used.

The hydroxymethylcarboxylic acids [Chemical formula 5] mentioned as the additives relating to the present invention are additives having excellent dimensional stability and anti-wrinkle property among many cellulose cross-linking agents, and are suitable for water and organic solvents. The effect of making the cellulose difficult to swell is high. This is considered to be due to the effect that the hydroxyl group of the cellulose molecule reacts with the methylol group or the carboxyl group to crosslink.

The function of the hydroxymethylcarboxylic acids is, in particular, an acid for hydrolysis which is added before impregnating the paper, a silanol group and a hydroxyl group of the cellulose molecule generated by hydrolysis by heating and drying after impregnation, or
It is considered that the same groups are crosslinked with each other, or the bond with the cellulose molecule is enhanced to improve the dimensional stability and wrinkle resistance of the paper itself.

Specific examples of hydroxymethylcarboxylic acids to be used do not use formaldehyde as a raw material, and examples thereof include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid.
Background Art In recent years, formaldehyde has been generated as a problem from adhesive raw materials for wallpaper and decorative paper. -Hydroxymethyl compounds have limited uses. Further, the carboxy group-containing compound added to the impregnating agent of the present invention is soluble in an organic solvent, but it is considered that the latter urea derivative is soluble only in water or formamide having strong basicity.

The method for producing an impregnating solution in which the impregnating agent according to the present invention is dissolved is prepared by dissolving the above-mentioned polymerized silane coupling agent or hydroxymethylcarboxylic acid in an organic solvent. To adjust. The organic solvent used here is not particularly limited as long as it dissolves the polymerized silane coupling agent or the additive, but it is too volatile in consideration of the stability of the coating liquid as the impregnating liquid. (Low boiling) solvents are not preferred. In addition, it is desirable that it is less harmful to the human body. Specifically, tetrahydrofuran, ethers such as dioxane, ethanol, alcohols such as propanol,
Examples thereof include ketones such as acetone and methyl ethyl ketone, toluene, aromatic hydrocarbons such as xylene, esters such as ethyl acetate, or a mixture thereof.

The paper used in the present invention includes Japanese paper, imitation paper, non-woven fabric, high-quality paper, art paper, coated paper, pure white roll paper, birchment paper, kraft paper, or corrugated cardboard for use in jute liners, craft liners, and coated paper. Examples include liners.

Next, as the method of applying the impregnating liquid, the usual roll coating method, doctor blade coating method,
Impregnation can be performed by any of the knife edge coating method, curtain coating method, gravure coating method, bar coating method, reverse coating method, kiss coating method and the like. The coating speed and the drying conditions are not particularly limited, but it is preferable to perform the coating within a range that does not adversely affect the paper or the impregnating liquid of the support.

The effective impregnation amount of the impregnating liquid on the paper substrate is usually 2
In 25 g / m ^2, as a standard, with a small coating amount of 4g / m ² (dry weight basis), to impart excellent water resistance to the paper, the rigidity and the like. The impregnated amount was measured by leaving the impregnated paper and the base paper (unimpregnated paper) in an electric dryer at 120 ° C. for 2 hours to obtain an absolutely dry state, and the impregnated amount per square meter was determined from the weight difference between the two. .

[0030]

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

<Example 1> First, an impregnating liquid for impregnating a base paper is prepared. 100 parts by weight of 2 in a 500 ml beaker
-(3,4-epoxycyclohexyl) trimethoxysilane (manufactured by Chisso Corporation, trade name; S530) was charged,
Stannous chloride (Sn) as a catalyst for epoxy group ring-opening crosslinking
Cl ₂ ) 0.003 mol dissolved in 1 g of methanol was added to 0.0005 with respect to the silane coupling agent.
A mol amount (0.068 parts by weight) is added, and the mixture is reacted with stirring with a stirrer. When an exothermic reaction occurs and the exotherm stops after a while, the reaction is terminated. At this time, if the exothermic reaction does not occur, the reaction is induced by heating. The number average molecular weight of the silane polymer obtained by this synthetic method is
By gel permeation chromatography (GPC) measurement, it was about 13,500 in terms of polystyrene. Next, this reaction product was dissolved in i-propanol at a solid content ratio (N.V.) = 20 wt%, and a curing agent (Toyo Ink Mfg. Co., Ltd., p-toluenesulfonic acid dihydrate-containing 50 wt%) was added. % I-propanol solution) was added and stirred to prepare an impregnating solution.

The impregnating solution was coated on a non-clay surface of a coated ivory (manufactured by Nippon Paper Industries Co., Ltd.) having a basis weight of 320 g / m ^{2 with} a wire bar so that the absolute dry amount was 4 g / m ² . It was dried at 150 ° C. for 1 minute to obtain the impregnated paper of Example 1.

<Example 2> Impregnation liquid 5 prepared in Example 1
A new impregnating solution was prepared by adding 10 parts by weight of 2,2-bis (hydroxymethyl) propionic acid as an additive to 20 parts by weight, and using this impregnating solution, as in Example 1, a basis weight of 320
coat Ivory g / m ² to Nonkurei surface (Japan Paper Co., Ltd.) with a wire bar, was applied as absolute dry amount is 4g / m ^2, and dried for 1 minute at 0.99 ° C, carried out Example 2
To obtain an impregnated paper.

<Example 3> Impregnating liquid 5 prepared in Example 1
A new impregnating solution was prepared by adding 15 parts by weight of 2,2-bis (hydroxymethyl) propionic acid as an additive to 20 parts by weight.
coat Ivory g / m ² to Nonkurei surface (Japan Paper Co., Ltd.) with a wire bar, was applied as absolute dry amount is 4g / m ^2, and dried for 1 minute at 0.99 ° C, carried out Example 3
To obtain an impregnated paper.

<Embodiment 4> Impregnation liquid 5 prepared in Embodiment 1
20 parts by weight of 2,2-bis (hydroxymethyl) propionic acid as an additive was added to 20 parts by weight to prepare a new impregnating solution.
coat Ivory g / m ² to Nonkurei surface (Japan Paper Co., Ltd.) with a wire bar, was applied as absolute dry amount is 4g / m ^2, and dried for 1 minute at 0.99 ° C, carried out Example 4
To obtain an impregnated paper.

Comparative Example 1 The base paper used in Example 1 which was not coated with the impregnating liquid according to the present invention was used as Comparative Example 1.

The boiling water resistance and rigidity of the four kinds of impregnated paper and one kind of base paper (blank) produced were evaluated according to the evaluation methods shown below. The results are shown in Tables 1 and 2. Boiling resistance ... Each sample was immersed in boiling water for 1 hour, and the state of the paper was evaluated by visual observation. Rigidity ... To evaluate the paper hardness and rigidity of the impregnated paper, refer to JIS P8125 "Testing method for stiffness of paperboard by load bending method" and refer to "Bending stiffness tester BST-150M" manufactured by Yoshizawa Industry Co., Ltd. It evaluated using. The measurement method is to measure the paper sample in the vertical direction 5 parallel to the coating direction.
The sample was cut into a size of 4 cm × 4 cm, and one end of the paper was fixed in an environment of 60 ° C. and the center of the paper was bent to determine the yield value (gf) and the angle at that time (initial slope; deg). The yield value is considered to be the evaluation of paper hardness, and the initial gradient is considered to be evaluation of rigidity.

[0038]

[Table 1]

[0039]

[Table 2]

From Tables 1 and 2, it is understood that the base paper impregnated with the impregnating liquid of the present invention has improved boiling water resistance and rigidity (Examples 1 to 4). In particular, the effect was remarkable when 2,2-bis (hydroxymethyl) propionic acid was added (Examples 2 to 4).

[0041]

The composition of the silane polymer-impregnated paper of the present invention in the paper has a structure in which a functional group other than the alkoxy group of the silane coupling agent is polymerized, and the organic cross-linking portion imparts flexibility and water repellency. In some cases, a hydroxymethylcarboxylic acid compound is added to enhance the interaction with the cellulose molecules that are components of the paper to improve dimensional stability, and a siloxane network formed by hydrolysis-condensation after impregnation of the paper. By forming the, the hardness of the paper can be improved.
Therefore, the silane polymer-impregnated paper of the present invention is a water resistant rigid paper that can substitute for aluminum used in beverage cans and food cans, and is suitable as a paper that can withstand retort sterilization.

Front page continuation (72) Inventor Junichi Kaminaga 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (56) Reference JP-A-6-343197 (JP, A) JP-A 64-6198 ( JP, A) JP 2-264074 (JP, A) JP 3-124865 (JP, A) JP 55-137295 (JP, A) JP 8-81632 (JP, A) JP Hei 10-183496 (JP, A) Japanese Patent Publication No. 4528003 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (5)

(57) [Claims] 1. A general formula: An oligomer or polymer polymerized alone at the site of the functional group (R ₁ ) represented by or copolymerized with two or more kinds of silane coupling agents is included, and is hydrolyzed.
When condensed, the general formula: A silane polymer-impregnated paper having a siloxane network structure such as (In the formula, R ₁ , R ₂ and R ₃ are the same or different and each is a lower alkyl group having 1 to 4 carbon atoms, R ₄ is an amino group, a vinyl group, an acryl group, a methacryl group, an epoxycyclohexyl group and a glycidyl group. A structure in which a compound having a group or the like is polymerized or copolymerized by two or more kinds is shown. N is 2 or more.) 2. The oligomer or polymer at the position of R ₁ shown in the general formula [Chemical formula 1] is represented by the general formula [Chemical formula 3] A structure polymerized by using a polyfunctional reagent (R ₅ ) as described above, which is hydrolyzed and condensed to give a compound represented by the general formula: The silane polymer-impregnated paper according to claim 1, which has a siloxane network structure such as: (In the formula, R ₁ , R ₂ and R ₃ are the same as those described above. Further, R ₅ is a bifunctional amino group, vinyl group, acryl group, methacryl group, epoxy group, halogen group, alcohol group, A structure in which a compound having an isocyanate group or the like is alone or polymerized is shown. M is 2 or more.) 3. The siloxane network structure is formed by hydrolyzing and condensing an alkoxysilyl group,
The silane polymer-impregnated paper according to claim 1, wherein p-toluenesulfonic acid dihydrate is used as a catalyst. 4. The silane polymer [Chemical Formula 1] and [Chemical Formula 3]
Has a number average molecular weight of 500 to 50,000. 3. The silane polymer-impregnated paper according to claim 1 or 2, wherein 5. The silane polymer-impregnated paper according to any one of claims 1 to 4, wherein as an additive, a compound represented by the general formula: A silane polymer-impregnated paper containing a mixture of hydroxymethylcarboxylic acids represented by: (In the formula, R ₆ represents an alkyl group having 1 to 5 carbon atoms.)