JP2001002974A - Film formation of hydroxyalkyl alkyl cellulose ether - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a film of water-soluble cellulose ether for covering seeds, agrochemicals, detergents, clothes, foods or the like by which a uniform film of a hydroxyalkyl alkyl cellulose ether can be efficiently formed without causing fluid dripping. SOLUTION: A hydroxyalkyl alkyl cellulose ether having 45-65 deg.C dissolving temperature in water is dispersed in the hot water having a temperature higher by 5-50 deg.C than the dissolving temperature to provide a slurry, and the obtained slurry is coated on a substrate. The resultant coated part is cooled to a temperature lower by 5-20 deg.C than the dissolving temperature and dried to provide the objective film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a water-soluble cellulose ether film for coating seeds, agricultural chemicals, detergents, clothing, foods and the like.

[0002]

2. Description of the Related Art Some foodstuffs such as seeds and laver and agricultural preparations are sometimes coated with a film so that the contents are not changed by the influence of air. For seeds and the like, this coating prevents germination during storage and protects the seeds from being harmed by harmful fungi. In addition, in order to prevent the flavor from being impaired by moisture, it is common practice to store it in a bag made of polyethylene or the like, but in order to protect the surface of the seaweed from moisture, the surface of the seaweed must be protected. Coating with a film is also being considered. Furthermore, in agricultural preparations, not only the stability during storage, but also some measures have been taken to ensure that the coating material disintegrates or dissolves properly when the preparation is used, and that the preparation components act at the desired time. .

[0003] In recent years, as such a coating method, a film-forming polymer which is soluble in water instead of an organic solvent has been often used. In particular, hydroxyalkylalkylcellulose ethers such as water-soluble hydroxypropylmethylcellulose (HPMC) and hydroxyethylmethylcellulose (HEMC) are water-soluble polymers derived from plants, and monomers that remain in the body like synthetic polymers It is widely used because of its high safety to the human body.

However, when an aqueous solution of a hydroxyalkylalkylcellulose ether is prepared and applied to a substrate, there is a problem that the viscosity is too high as compared with the synthesized polyvinyl alcohol or the like. In other words, when preparing a coating by preparing a concentrated aqueous solution and spray coating or dipping a substrate, there are problems such as difficulty in spraying and difficulty in forming a thin and uniform coating by dipping. there were. Further, when a film is to be formed by the dipping method, there is also a problem that since the fluidity of the aqueous solution is good, dripping occurs and it is difficult to form a uniform film.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method of forming a hydroxyalkylalkylcellulose ether film which can efficiently form a uniform film without causing dripping. With the goal.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the dissolution temperature in water was 45 ° C.
C. to 65.degree. C. in a hot water at a temperature of 5.degree. C. to 50.degree. C. higher than its melting temperature to form a slurry. The present inventors have found that a method for forming a film of a hydroxyalkylalkylcellulose ether by cooling the coated part at a temperature lower by 20 ° C. to 20 ° C. and then drying can efficiently form a uniform film without causing dripping. It is something that has been done.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail, but the present invention is not limited only to the following embodiments. The hydroxyalkylalkylcellulose ether of the present invention has a dissolution temperature in water of 45 ° C to 65 ° C. For example, hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEM)
C), hydroxyethylethylcellulose (HEEC), hydroxypropylhydroxyethylmethylcellulose (HPHEMC) and the like, but are not limited thereto.

Specifically, examples of the hydroxyalkylalkyl cellulose ether of the present invention include a methoxyl group of 19% to 30% and a hydroxypropoxyl group of 13%.
Hydroxypropyl methylcellulose ether having methoxyl groups of 19% to 30%, hydroxyethoxyl groups of 9% to 20%, and ethoxyl groups of 11% to 2%.
1%, hydroxyethyl ethyl cellulose ether having 40% to 57% hydroxyethoxyl groups, 4 to 12% hydroxypropoxyl groups, 4 to 12% hydroxyethoxyl groups, and hydroxypropyl hydroxyethyl methyl cellulose having 19 to 30% methoxyl groups Ether and the like.

The term "dissolution temperature" used in the present invention means that when a 1% by weight aqueous solution of a hydroxyalkylalkylcellulose ether to be used is prepared, the hydroxyalkylalkylcellulose ether is heated at a temperature of 70 ° C. or higher. After obtaining a dispersion having no viscosity by dispersing in a dispersion, when the viscosity is measured while cooling the dispersion, the viscosity which emerges from a specific temperature or less, once the dispersion is reduced to 5 ° C or less. When the viscosity is reduced while heating the dispersion after cooling to develop the viscosity, it refers to the temperature that matches the observed viscosity value. In the present invention, a hydroxyalkylalkylcellulose ether having a dissolution temperature of 45 ° C to 65 ° C is used.

In the present invention, if a hydroxyalkylalkylcellulose ether having a dissolution temperature of less than 45 ° C. is used, it is necessary to lower the cooling temperature before the drying step to 45 ° C. or less and raise the temperature during drying. It takes time and heat, but if the dissolution temperature exceeds 65 ° C., the thermal gelation after dissolution becomes insufficient, so the solution may fall out when trying to obtain a film by dipping or the like. .

The hot water slurry having a temperature equal to or higher than the dissolving temperature of the hydroxyalkylalkylcellulose ether is in a state in which the fibrous cellulose ether is dispersed and entangled. When the slurry is once cooled and then heated to a temperature equal to or higher than the dissolution temperature of the hydroxyalkylalkylcellulose ether, the solution undergoes thermal gelation and the solution viscosity increases apparently. Therefore, the hot water slurry used to achieve the object of the present invention is 5 to 50 ° C. higher than the dissolution temperature,
It is preferably a slurry obtained by dispersing in hot water at 70 ° C to 95 ° C.

The particle size of the hydroxyalkylalkylcellulose ether is not particularly limited, but is preferably 70% or more, and preferably 90% or more, which passes through a sieve having 150 μm openings to facilitate dispersion slurry. Can be Further, the average molecular weight of the hydroxyalkylalkylcellulose ether is not particularly limited because the slurry is prepared from the slurry before the viscosity is developed.
00,000 and the viscosity of 2% by weight aqueous solution is 3 m
It is preferably about Pa · s or more. The hydroxyalkylalkylcellulose of the present invention can be produced, for example, by the method described in JP-A-5-345801 and JP-A-1-217001.

The method of forming a film in the present invention may be a method such as spraying, casting, dipping, or the like. In addition, as long as the object of the present invention is not impaired, inorganic fillers such as ceramics capable of forming a film in these methods, coloring agents such as lipstick, methyl orange and methyl let, polyvinyl alcohol, sodium polyacrylate, poly Organic binders such as acrylamide and carboxymethyl cellulose can also be added. Further, the formed film can be peeled off and used in the form of a tape.

In the present invention, after the slurry is applied on the substrate, the temperature is preferably 5 ° C. to 20 ° C., more preferably 5 ° C. to 1 ° C.
The reason why the coated portion is cooled at a temperature lower by 5 ° C. is to sufficiently dissolve the hydroxyalkylalkylcellulose ether at this temperature. If the temperature is higher than this, the dissolution becomes insufficient, and if the temperature is lower, there is a possibility that much time and heat will be required in the subsequent drying step. The drying step in the present invention is performed at 50 ° C to 100 ° C, preferably 80 ° C to 100 ° C, for 0.5 to 24 hours.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Examples 1 to 5 and Comparative Examples 1 to 3
The characteristics of the hydroxyalkylalkylcellulose ether used in the above are described in Table 1.

[0016]

[Table 1]

In each of Examples and Comparative Examples having the characteristics shown in Table 1, 250 ml of a slurry was prepared in a 300 ml beaker using a hydroxyalkylalkylcellulose ether having passed at least 70% of a 150 μm sieve. . Grape seeds were pinched with tweezers, dipped once in slurries adjusted under the respective conditions, pulled up, and dried. The dried seed was cut with a cutter knife, and the cross section was observed with a microscope. If the thickness non-uniformity exceeds 40% of the total thickness, the film thickness is assumed to be non-uniform, and if the film is insufficiently transparent due to fogging, the film is non-uniform. Was evaluated.

Further, using a microscope slide glass heated to a temperature similar to the slurry temperature on a hot plate,
The slide glass is immersed up to half the length of the slide glass in a beaker containing the slurry at the predetermined temperature, taken out vertically, cooled to the predetermined cooling temperature using a drier, and then heated and dried from a vertical surface. It was observed whether or not a film was formed with the slurry dropped. Table 1 shows the above results.

[0019]

According to the present invention, it is possible to form a hydroxyalkylalkylcellulose ether film which can efficiently form a uniform film without dripping.

Claims (2)

[Claims] 1. A slurry in which a hydroxyalkylalkylcellulose ether having a dissolution temperature in water of 45 ° C. to 65 ° C. is dispersed in hot water at a temperature 5 to 50 ° C. higher than its dissolution temperature to obtain a slurry. A method for forming a film of a hydroxyalkylalkylcellulose ether, wherein the film is coated on the substrate, the coated part is cooled at a temperature lower by 5 ° C to 20 ° C than the melting temperature, and then dried. 2. The method according to claim 1, wherein the hydroxyalkylalkylcellulose ether is hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, or hydroxyethylethylcellulose.
The described method.