JPH0796561B2 - Photosoluble and thermally crosslinkable water-soluble cellulose derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention has the same physical properties as novel cellulose derivatives, especially existing water-soluble cellulose ethers.
The present invention relates to a water-soluble cellulose derivative which is free from defects in adhesive strength and water resistance due to its water solubility and has both photocrosslinking property and heat crosslinking property and which is extremely useful in industry.

(Prior Art) Conventionally, water-soluble cellulose ethers represented by methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, etc. are thickening agents such as emulsion-based paints, paper coating agents, and various adhesives. , Film-forming agents, water-holding agents and fluidity improvers for cement mortar, binders used in the production of ceramic-based and cement-based extrusion moldings, etc., but they have some unsolved problems. .

(Problems to be Solved by the Invention) For example, when a water-soluble cellulose ether is used for an emulsion paint, a paper coating agent, an adhesive, etc., the film formed by drying after coating has poor water resistance. In addition, in these applications, the viscosity of the coating does not increase so much until the contained water evaporates to a considerable extent, so it may cause sagging in the middle or it takes a long time to develop the desired adhesive strength. It is a problem that work efficiency does not increase.

On the other hand, the hydrogen atom of the hydroxyl group of the water-insoluble cellulose ether or ester having an average degree of substitution per unit glucose ring (hereinafter simply referred to as DS) of 2.0 to 2.9 is replaced with N-methylene acrylamide having an average degree of substitution of 0.05 to 0.5. Group (-CH _2-
A polymerizable product soluble in an organic solvent substituted with (NH-CO-CH = CH ₂ ) is known (Japanese Patent Laid-Open No. 144301/1985), but this problem is solved by using a water-soluble cellulose ether. What you have done is unknown.

Therefore, the object of the present invention, while having the same physical properties as existing water-soluble cellulose ethers, without causing sagging due to being water-soluble, the adhesive force is expressed in a short time,
It is intended to provide a novel water-soluble cellulose derivative having improved water resistance and further having both photo-crosslinking property and heat-crosslinking property.

(Means for Solving the Problems) The inventors of the present invention have solved the problems of the water-soluble cellulose ethers as described above, and made effective use of their excellent properties. 1-4
Having at least one of the hydroxyalkyl group and the carboxymethyl group of
The hydrogen atom of the hydroxyl group of cellulose ether having a total DS of 0.3 or more and less than 2.0 is an N-methylene acrylamide group (-CH
_{Those 2 -NH-CO-CH = CH} 2) water-soluble cellulose derivatives having a photocrosslinkable and thermal crosslinkable consisting replaced with heading that matches the above-mentioned object, the present invention has been completed is there.

Hereinafter, the details of the present invention will be described.

A methyl group constituting the water-soluble cellulose derivative of the present invention,
Examples of the water-soluble cellulose ether having at least one of a hydroxyalkyl group having 1 to 4 carbon atoms and a carboxymethyl group as a substituent include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose and the like. It

The present invention provides a water-soluble cellulose ether of this type,
The total DS of the substituents is 0.3 or more and less than 2.0, and the hydrogen atom of the glucose ring is an N-methylene acrylamide group (-CH ₂
Those with a _{-NH-CO-CH = CH 2} ) that is substituted with structure. Here, the total DS is limited to 0.3 or more and less than 2.0. If it is less than 0.3, water solubility is lost, and if it is 2.0 or more, cost is high and economic efficiency is lost. Is not expected. The DS of the N-methylene acrylamide group is not particularly limited, but is preferably 0.05 or more in order to achieve the object of the present invention.

The production of the water-soluble cellulose derivative of the present invention is generally carried out by using a cellulose ether having the above DS as a starting material.
It is carried out by reacting N-methylol acrylamide. This method is carried out by dissolving or dispersing the above-mentioned cellulose ether, N-methylol acrylamide, an acid catalyst, a polymerization inhibitor, etc. in an organic solvent such as water or alcohol, acetone, etc., or a mixed solvent thereof, and then adding the required amount of the solvent.
N-methylol acrylamide is reacted by giving the temperature and time required for the reaction, and then it is achieved by appropriately performing a post-treatment, instead of this, cellulose,
In the production process of cellulose ether that is reacted with an etherifying agent such as methyl chloride, ethylene oxide, propylene oxide, monochloroacetic acid, etc.
A method in which N-methylolacrylamide is allowed to coexist and a cellulose ether formation reaction and an N-methylolacrylamide reaction are allowed to proceed simultaneously may be used.

The acid catalyst used in the former method includes phosphoric acid, hydrochloric acid, paratoluenesulfonic acid, ammonium chloride, citric acid, tartaric acid, and the like, and the polymerization inhibitor includes hydroquinone, hydroquinone methyl ether, parabenzoquinone, and the like. These can be appropriately selected and used in consideration of the solubility in the solvent used.

As the post-treatment step, for example, a volatile component such as a solvent is removed from the reaction solution after the reaction through a drying step, and the obtained crude product is washed with an appropriate solvent and dried to give a purified product. It is done in a way of getting.

In the production of this water-soluble cellulose derivative, a solvent, cellulose ether, N-methylol acrylamide, a mixture of acid catalysts, polymerization inhibitors, etc., by a suitable drying method such as vacuum drying, oven drying, drum drying, spray drying. By the heat treatment, the above-mentioned reaction can be carried out simultaneously with the drying.

When the product is dissolved in the reaction solution, a solvent that is a poor solvent for the product and that mixes uniformly with the reaction solution is added as a precipitating agent to the reaction solution to precipitate the desired product. The product can also be obtained by performing a purification operation after separation by filtration, centrifugation, or the like.

On the other hand, when the product is dispersed without being dissolved in the reaction solution, directly after separation by filtration or centrifugation,
It can be commercialized through a refining operation.

The water-soluble cellulose derivative according to the present invention has a chemical structure in which hydrogen atoms of hydroxyl groups contained in cellulose ether are partially
It was replaced with N-methylol acrylamide. For this reason, this water-soluble cellulose derivative has basically the same physical properties as cellulose ether, but (polymerization or cross-linking reaction proceeds in the presence of a polymerization initiator, by irradiation with light such as ultraviolet rays or electron beams, or heat treatment. It also has the function of the N-methylene acrylamide group.

The water-soluble cellulose derivative of the present invention having such properties is used as a polymerization initiator in emulsion coatings, paper coating agents such as overcoats of thermal paper, adhesives, etc. When light irradiation or heat treatment is applied after coating together, a cross-linking reaction occurs between the cellulose derivatives to solidify, so that no sagging occurs and the adhesive strength is instantly developed to improve work efficiency and water resistance. It is possible to solve all the problems with water-soluble cellulose ethers up to now, such as improvement in

In addition, when conventional photo-curable resin (photo-curable monomer, photo-curable oligomer) is used together, the photo-curable resin can be given water wettability, blocking resistance, and strain resistance. It is expected that demand will increase in the fields of photo-curable coatings, inks, adhesives, etc. that use photo-curable resins.

The photocurable resin used here includes photocurable monomers such as 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate, and trimethylolpropane triacrylate, polyester acrylate, epoxy acrylate, polyurethane acrylate, and polyether. Photocurable oligomers such as acrylates and the like,
Examples of the polymerization initiator used in combination with these resins include benzoyl peroxide, benzyl, biacetyl, azobisisobutyronitrile and the like.

(Examples) Hereinafter, specific embodiments of the present invention will be described with reference to Examples.
The invention is not limited to this example.

Example 1. In a reactor equipped with a stirring blade, ethyl acetate (1) was put, and 0.2 g of hydroquinone, 0.4 g of 85% phosphoric acid and 75 g of N-methylolacrylamide were added and dissolved while stirring. Next, 100 g of hydroxypropyl cellulose (DS: 1.75) was added, and the reaction was carried out at a reaction temperature of 50 ° C. for 6 hours. After cooling the reaction,
The crude product obtained by filtration was poured into hot water at 90 ° C., washed and dried to obtain a purified product. DS of each substituent of this purified product
Was as follows:

Hydroxypropyl group: DS = 1.73 N-methyleneacrylamide group: DS = 0.45 Example 2. A beaker was charged with 1-tert-butanol and 85%
Phosphoric acid 2.0 g, hydroquinone methyl ether 6 g, and N-methylol acrylamide 300 g were added and dissolved. 1,000 g of hydroxypropyl cellulose used in the previous example while stirring
Was added and mixed. The prepared slurry was filtered, and the filtration operation was stopped when 800 g of the filtrate was discharged. The remaining cake was flat-filled in an aluminum container and then placed in a dryer at 50 ° C. and heated for 10 hours. The crude product obtained next
It was poured into hot water at 90 ° C, washed, and then dried to obtain a purified product.
The DS of this purified product was as follows.

Hydroxypropyl group: DS = 1.74 N-methyleneacrylamide group: DS = 0.31 Example 3. Instead of hydroxypropylcellulose in Example 1, methylcellulose (DS = 1.81) was used,
When the completely same operation as Example 1 was performed, DS of the obtained purified product was as follows.

Methyl group: DS = 1.80 N-methylene acrylamide group: DS = 0.31 Example 4. The same as in Example 1 except that carboxymethyl cellulose (DS = 0.65) was used in place of hydroxypropyl cellulose in Example 1. After performing the operation,
The DS of the obtained purified product was as follows.

Carboxymethyl group: DS = 0.63 N-methyleneacrylamide group: DS = 0.37 Example 5. 100 g of the cellulose derivative obtained in Examples 1 to 4 and 3 g of biacetyl were dissolved in 400 g of pure water and cast on a glass plate. Then, it was left at a temperature of 20 ° C. to obtain a semi-dried film having a thickness of 50 μm. Ultraviolet rays were applied to this film at a running speed of 5 m / min using a high pressure mercury lamp with a lamp input of 80 W / cm.
Irradiated twice. The obtained film is left at room temperature under reduced pressure,
The water remaining in the film was removed. After dipping 5 g of this film in 500 g of pure water for 1 hour, the amount of the dissolved film was measured, and the insolubilization rate was determined by the following formula, which was used as a measure of crosslinkability and solvent resistance.

The results are shown in the attached table.

Example 6. 100 g of the cellulose derivative obtained in Examples 1 to 4 and 3 g of azobisisobutyronitrile dissolved in 400 g of pure water were cast on a glass plate and then heat-treated at 100 ° C. for 5 hours. A film having a thickness of 100 μm was obtained. This film was subjected to the same treatment as in the previous example to obtain the insolubilization rate, and the results are also shown in the following separate table.

(Effects of the Invention) The water-soluble cellulose derivative according to the present invention is used together with a polymerization initiator in emulsion coatings, paper coating agents such as overcoats of thermal paper, adhesives, etc. After coating, and then light irradiation or heat treatment, a cross-linking reaction occurs between the cellulose derivatives to solidify, so that sagging does not occur, and the adhesive strength is instantly developed to improve work efficiency and also water resistance. It is possible to solve all the problems with water-soluble cellulose ethers up to now such as improvement. In addition, when conventional photo-curable resin (photo-curable monomer, photo-curable oligomer) is used together, the photo-curable resin can be given water wettability, blocking resistance, and strain resistance. It is expected that demand will increase in the fields of photo-curable coatings, inks, adhesives, etc. that use photo-curable resins.

Claims (1)

[Claims] 1. A methyl group, a hydroxyalkyl group having 1 to 4 carbon atoms, and at least one of carboxymethyl groups as a substituent, and the average degree of substitution (DS) of those substituents per unit glucose ring. total has a photocrosslinkable and thermal crosslinkable formed by replacing a hydrogen atom of the hydroxyl group of the cellulose ether is less than 0.3 to 2.0 is N- methylene acrylamide group _{(-CH 2 -NH-CO-CH} = CH 2) of Water-soluble cellulose derivative.