JPS62180780A - Production of film having excellent transparency and writing quality - Google Patents

Abstract

PURPOSE:To obtain a film having excellent transparency and writing quality by dissolving an initial polycondensation product of a melamine resin and cellulose ether, etc., into an org. solvent, dispersing inorg. powder into the solvent and coating such soln. on a synthetic resin film. CONSTITUTION:The initial polycondensation product of the melamine resin and the cellulose ether or cellulose ester are dissolved in the org. solvent. A coating compsn. prepd. by uniformly dispersing the inorg. powder such as silica into said org. solvent is coated on the transparent plastic film. the film is then subjected to a heating treatment to evaporate the org. solvent and to form the melamine resin. As a result, the film having the excellent writing quality and transparency is efficiently produced.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention has excellent transparency and writability, making it useful as a tracing film used in design drawings and original drawing paper for creating positive blueprints. The present invention relates to a method for manufacturing a film.

(B) Problems to be Solved by the Prior Art and the Invention Traditionally, transparent paper called tracing paper has been used when creating design drawings and positive blueprints. Tracing paper is obtained by highly beating chemical pulp and making paper, so it has the disadvantages of being weak in strength and prone to shrinkage due to humidity changes, resulting in poor dimensional stability. Therefore, film-based materials (so-called tracing films), which are strong and have excellent dimensional stability, are often used when creating design drawings and positive blueprints. Film□・Be□−
Because the ones originally have poor writing ability with pencils, etc.,
Its surface is roughened to improve pencil writing performance. The surface is roughened by physically roughening it with abrasive sand using liquid honing or gas honing.
This is done by washing off and removing the abrasive sand. However, this method has disadvantages in that the time required for polishing is relatively long, the production speed of a film with a roughened surface (so-called tracing film) is slow, and productivity is low.

Therefore, the present invention aims to improve the productivity of so-called tracing films by imparting pencil-like properties to the surface of the film without subjecting the film to physical tlFlff'.

(c) Means and action to solve the problem, that is, the present invention is to dissolve the initial polycondensate of melamine resin and cellulose ether or cellulose ester in an organic solvent, and uniformly distribute the inorganic powder in the organic solvent. A film with excellent transparency and writability, characterized in that a dispersed coating composition is applied to a plastic film and then heat treated to evaporate the organic solvent and produce a melamine resin. This relates to the manufacturing method.

In the present invention, a coating composition is first prepared. The coating composition is an organic solvent-based composition comprising an initial polycondensate of melamine resin dissolved in an organic solvent, cellulose ether or cellulose ester, and an inorganic powder dispersed in the organic solvent.

Initial polycondensates of melamine resin include (mono-hexa)methylolmelamine, alkoxylated products thereof,
Alternatively, polymer resins whose degree of polycondensation has advanced to a certain degree are used.

The initial polycondensate of melamine resin becomes a thermosetting melamine resin by heating, but it is preferable to use a curing catalyst in order to facilitate curing. Examples of curing catalysts for the initial polycondensate of melamine resin include ammonium salt catalysts such as ammonium chloride, diammonium phosphate, and ammonium sulfamate, hydrochloric acid or sulfamate salts of organic amino alcohols, dimethylaniline hydrochloride, and pyridine.
Examples include hydrochloric acid catalysts, organic amine salt catalysts such as picoline-monochloroacetic acid, and inorganic metal catalysts such as magnesium chloride, zinc chloride, and zinc sulfate.

The initial polycondensate of melamine resin becomes a three-dimensional network polymer by heat treatment and adheres well to the base film.

As the cellulose ether, methylcellulose, ethylcellulose, benzylcellulose, tritylcellulose, cyanethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, oxyethylcellulose, etc. are used. Cellulose esters include cellulose acetate, cellulose propionate, cellulose butyrate, and cellulose nitro.

Cellulose sulfate, cellulose phosphate, etc. are used. Cellulose ether or cellulose ester contributes to the film-forming properties of the coating composition.

Any organic solvent may be used as long as it dissolves both the melamine resin and cellulose ether or cellulose ester. For example, acetone, butyl alcohol.

Isopropyl alcohol, acetic acid, methyl, ethanol, or a mixture thereof is used. The reason why an organic solvent is used in the present invention is that it has better affinity with the film than water and does not cause uneven coating.

The inorganic powder to be dispersed in the organic solvent may be one that is insoluble or has extremely low solubility in the organic solvent used, such as zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, and tin oxide. , titanium Mide, iron oxide, copper oxide.

Metal or non-gold rFA oxides such as lead oxide, bismuth oxide, magnesium oxide, and manganese oxide, QPAs such as calcium carbonate and calcium sulfate, silicon compounds such as silicon dioxide, natural pigments such as kaolin, bentonite, and clay, aluminum, and iron. , various metal powders such as zinc. Further, the particle size of the inorganic powder may be about 320 mesh baths. The inorganic powder is used to form fine irregularities on the surface of the coating film obtained by applying the coating composition, and contributes to improving the writability with a pencil.

The mixing ratio of each component of the coating composition used in the present invention is as follows. □ The amount of cellulose ether or cellulose ester is
The amount is about 30 to 150 parts by weight based on 100ffx parts of the initial polycondensate of the melamine resin. If the amount of cellulose ether or cellulose ester is less than 30i [196], the coating film formed by coating will be damaged. l! ! The film properties tend to deteriorate and the surface becomes uneven, and if the amount exceeds 150 parts by weight, the adhesion to the base plastic film deteriorates and the coating film tends to peel off.

The amount of inorganic powder is a first for melamine resin! 1JI polycondensate 1
The amount is about 20 to 80 parts by weight per 00 parts by weight. When the amount of inorganic powder is less than 20 parts by weight, it tends to be difficult to form uniform and fine irregularities on the surface of the coating film, and when it exceeds 80 parts by weight, the adhesion between the coating film and the plastic film that is the paste becomes difficult. Since a large amount of inorganic powder is present on the surface, the coating film tends to peel off easily.

The amount of organic solvent is not particularly limited, but it is preferably an amount that provides a viscosity that allows the coating composition to be easily coated and that allows the above-mentioned components to be uniformly dissolved or dispersed.

Such a preferable amount is about 500 to 2000 parts by weight per 100 parts by weight of the initial polycondensate of melamine resin.

The coating composition thus obtained is applied to a transparent plastic film, and then heat treated. The heat treatment is carried out under conditions such that the initial polycondensate of the melamine resin undergoes further polycondensation to form a three-dimensional network polymer. Therefore, if a curing catalyst of the initial polycondensate of melamine resin is incorporated into the coating composition, the temperature may be about 90 to 100°C, and if not, the temperature is 150 to 200°C.
It is a condition of degree. This heat treatment simultaneously evaporates the organic solvent.

By the method explained above, it is possible to obtain a film having fine irregularities on the base plastic film, a flat surface, and a coating film with good adhesion to the plastic film, and this film has transparency and writing resistance. It has excellent characteristics.

(d) Examples Example 1 The following coating composition was applied to the surface of a 15 μm thick transparent polyester film using a #4 bar coater.

Methylolmelamine (Nippon Carbide Kogyo A1!! Nikaresin S-305) 8.4 parts by weight Ethyl cellulose 4.0 parts by weight Silicon dioxide 3.0 parts by weight Butyl alcohol 100 parts by weight Afterwards temperature 150°C
The sample was introduced into a hot air dryer heated to 100 mL and heat-treated for 1 minute to obtain a film on which a coating film was formed.

On the coating surface of this film, [JjB, HB.

When I used each 3H pencil and drew a line with a ruler,
I was able to draw clear line diagrams. In addition, when a positive blueprint was created using the film on which this line diagram was drawn as the original, a clear line diagram similar to the original was able to be reproduced.

Example 2゜Example 1. Example 1 except that the following coating composition was used in place of the coating composition of Example 1. A film with a coating film formed thereon was obtained in the same manner as above.

Methylolmelamine (Nippon Carbide Industries (II i!
J Nikaresin S-305) 5.0 parts by weight Methyl cellulose 6.0 parts by weight Titanium powder 3.0 parts by weight Isopropyl alcohol 100ili1 Example 2.
The film obtained in Example 1 also exhibited good writability and transparency as in Example 1.

(E) As described in detail of the invention, according to the method of the present invention, a specific coating composition is applied to a plastic film,
Then, a film with excellent writability and transparency can be obtained by simply performing a heat treatment. Therefore, there is no need to use the conventional process of polishing and removal of polishing sand, which is a complicated process and has a slow processing speed, thereby streamlining the production process and improving the production speed (about 3 to 5 times faster production speed). ).

Claims (1)

[Claims] A coating composition in which an initial polycondensate of a melamine resin and a cellulose ether or a cellulose ester are dissolved in an organic solvent and an inorganic powder is uniformly dispersed in the organic solvent is coated on a plastic film, A method for producing a film with excellent transparency and writability, characterized by evaporating the organic solvent and producing a melamine resin by subsequent heat treatment.