JPH0354700B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an easily adhesive roughened polyester film. Highly roughened polyester films made of polyethylene terephthalate are widely used as release films, transfer films, tracing films, label films, and the like. These highly roughened polyester films can be produced using a method in which the surface of the film is roughened by physical or chemical treatment, a coating method in which a roughening substance is applied to the film surface, and an inorganic material is added to the film material. A kneading method that roughens the surface by mixing and dispersing organic substances is known, and the present invention uses the above-mentioned coating method and kneading method together to create a highly rough surface with new properties. It provides a polyester film. In order to obtain a highly roughened polyester film with a gloss level (60 degrees) of 60 or less as defined in JIS-Z8741 by the kneading method, polyester When melt-extruding the film, the filter becomes clogged quickly, and when the film is stretched, there are many breaks, which reduces productivity, and furthermore, the mechanical strength of the obtained film decreases. On the other hand, if a highly roughened polyester film with a glossiness (60 degrees) of 60 or less is to be obtained by a coating method, it is generally necessary to apply the roughening composition liquid in two or more parts. In order to apply the coating in one go, the speed must be extremely reduced, and in any case, productivity is low. Further, when drying the coated film, it is subjected to severe heat treatment, resulting in a large decrease in mechanical strength, and furthermore, since the coating amount is large, the coated film curls significantly. Conventional roughening compositions for roughening polyester films use polyurethane, melamine, etc., but the above-mentioned roughening compositions do not have sufficient adhesion to polyester films, and There is also a problem that the adhesion to ultraviolet curable ink is insufficient, and if ultraviolet curable ink cannot be used, deep printing cannot be achieved. As a result of intensive research to eliminate the drawbacks of the above-mentioned kneading method and coating method, the present inventor found that by using the kneading method and coating method together under specific conditions, the mechanical strength does not decrease. This paper proposes a method for efficiently producing a highly roughened polyester film with good adhesion to ultraviolet curable ink. In other words, the present invention provides that (1) softening point
30 to 70% by weight of a saturated copolymerized ester component with a glass transition temperature of 150°C or higher and a glass transition temperature of 45°C or higher, and (2) a softening point of 130°C.
Hereinafter, a composition consisting of 70 to 30% by weight of a saturated copolymerized ester component having a glass transition temperature of 10°C or less and (3) 10 to 40 parts by weight of an inorganic particle component based on 100 parts by weight of the above mixed copolymerized ester is solidified. This is a method for producing an easily adhesive, roughened polyester film, characterized in that the glossiness is 60 or less by coating the film at a rate of 2 to 6 g/m ² . The polyester film in this invention is an aromatic polyester film, and includes polyethylene terephthalate, an isophthalic acid component having 80 mol% or more of ethylene terephthalate units, an ethylene terephthalate copolymer having an oxybenzoic acid component, polytetramethylene terephthalate,
Known kneading inorganic substances and organic polymer substances are mixed and dispersed into a polyester consisting of 2,6-naphthalene dicarboxylic acid and ethylene glycol, and the kneaded polyester is melt-extruded in a conventional manner. The film is formed into a film and stretched uniaxially or biaxially. The amount of the inorganic substance and organic polymer substance to be kneaded is adjusted so that the polyester film has a gloss level of 110 or less and a low surface roughness. If the gloss of the polyester film exceeds 110, the amount of surface roughening composition applied cannot be effectively reduced. The composition coated on one side of the above-mentioned low surface roughening polyester film includes (1) a saturated copolymer ester component having a softening point of 150°C or higher and a glass transition temperature of 45°C or higher;
~70% by weight, (2) 70 to 30% by weight of a saturated copolymerized ester component with a softening point of 130°C or lower and a glass transition temperature of 10°C or lower, and (3) inorganic particles based on 100 parts by weight of the above mixed copolymerized ester. The composition consists of 10 to 40 parts by weight of the ingredients. In addition, the softening point of the copolymerized ester is
JIS-K2531, glass transition temperature is a value measured by DSC method. The above copolymerized ester is composed of a saturated dibasic acid and a glycol, and the saturated dibasic acid is terephthalic acid or a total of 40% of terephthalic acid and isophthalic acid.
Dibasic acids other than terephthalic acid and isophthalic acid include adipic acid,
Examples include aliphatic dicarboxylic acids such as sebacic acid and azelaic acid, and aromatic dicarboxylic acids such as orthophthalic acid and diphenyldicarboxylic acid. In addition, the glycols of the copolymerized ester include ethylene glycol, 1,2-propylene glycol, 1,
One or more of 3-propylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, etc. are used. Also, oxyacids such as oxybenzoic acid may be used. The softening point and glass transition temperature of the copolymerized ester can be appropriately determined depending on the type of dibasic acid and glycol, the mixing ratio of the two dibasic acids or the two glycols, the polymerization conditions, and the like. The mixing ratio of (1) copolymerized ester component with a high softening point and (2) copolymerized ester component with a low softening point is 30 to 70% by weight of the former (1) in the total copolymerized ester component,
The latter (2) is 70 to 30% by weight. If the mixing ratio of the copolymerized ester component in the former (1) is less than 30% by weight, the tackiness of the coating film will increase, and if it exceeds 70% by weight, the adhesion to polyester film will decrease. The inorganic particle component (3), which is another component in the above composition, preferably has a particle size of 0.1 to 20 microns,
One or two of silica, kaolin, talc, titanium dioxide, calcium carbonate, and barium sulfate are used. The blending amount of (3) inorganic particles varies depending on the particle size and coating amount, but is 10 to 40 parts by weight based on 100 parts by weight of the total amount of copolymerized esters (1) and (2), and 10 to 40 parts by weight. If it is less than 40 parts by weight, the coating film will not have sufficient surface roughness, and if it exceeds 40 parts by weight, the inorganic particles will be unevenly dispersed in the composition liquid. The above compositions contain organic polymers such as styrene polymers, cellulose derivatives, polyisocyanates, and organic titanates for the purpose of preventing adhesion of the coating film and improving coating film hardness, chemical resistance, heat resistance, etc. A hardening agent such as may be added. Further, if necessary, pigments, colorants, heat stabilizers, light absorbers, antistatic agents, etc. may be added. However, if the above additives are added in too large an amount, the adhesion of the coating film to the polyester film will decrease, so if
It is preferably less than % by weight. The above composition is applied as a solution of an organic solvent to the above polyester film by a method such as gravure coating, kiss coating, reverse coating, or knife coating, and then dried. The coating amount of the composition is 2 to 6 g/m ² solids,
If the coating amount is less than 2g/ ^m2 , the surface roughness will be sufficient, that is, the gloss will not be less than 60, and the coating amount will not be less than 60.
If the amount exceeds g/m ² , a large amount of heat is applied for drying after coating, which reduces the mechanical strength of the coating film and further causes curling. The polyester film obtained by the method described above has a highly rough surface with a gloss level of 60 or less on the surface with the coating, and a deep printing layer is formed on this coating using ultraviolet curable ink. can do. The polyester film produced by the method of this invention not only has good adhesion to ultraviolet curable ink, but also has no decrease in mechanical strength.
It goes without saying that it can be widely used in transfer films, release films, tracing films, and the like. This invention will be explained below by way of examples. Note that parts and percentages in the examples are based on weight. Example 1 Polyethylene terephthalate (intrinsic viscosity
0.62, a value measured at 30°C in a mixed solvent with a ratio of phenol to tetrachloroethane of 60:40) was formed into a film using a conventional method and sequentially biaxially stretched to form a polyethylene terephthalate film with a thickness of 25 microns. Obtained. The gloss of this film was 90. On the other hand, (1) A mixed acid of terephthalic acid and isophthalic acid (molar ratio 50:50) and a mixed glycol of ethylene glycol and neopentyl glycol (molar ratio
60:40) and a copolymerized ester (softening point
160℃, glass transition temperature 69℃) 50 parts. (2) A copolymerized ester ( Softening point: 120℃, glass transition temperature: 5℃)
35 copies. (3) 20 parts of silica with an average particle size of 2.5 microns. (4) 15 parts nitrocellulose. (5) Polyisocyanate (product name Coronate HL)
(manufactured by Nippon Polyurethane Co., Ltd.) 10 copies. A solution of the composition (solvent toluene/methyl ethyl ketone = 8/2, solid content 20%) was prepared, and this composition solution was applied to the surface of the polyethylene terephthalate film at a coating amount of 3.5 g/m ² solid content. The film was then dried at 145°C for 8 seconds to obtain a highly roughened film. The tensile strength of the resulting highly rough polyester film and the adhesiveness of the ultraviolet curing ink are shown in the table together with comparative examples. Comparative Example 1 Polyethylene terephthalate (intrinsic viscosity
0.63) was biaxially stretched in the same manner as in the example to obtain a polyethylene terephthalate film with a thickness of 25 microns. Since this film has a highly rough surface with a gloss level of 55, roughening by a coating method was omitted. Comparative example 1
In this method, the film was often broken during stretching, and the pressure increase rate due to filter clogging during film formation was about 10 times that of Example 1. Comparative Example 2 Polyethylene terephthalate containing 0.05% silica powder with an average particle size of 2 microns (intrinsic viscosity 0.62)
Biaxially stretched to a thickness of 25 microns as in the example.
A polyethylene terephthalate film with a gloss level of 200 was obtained. A liquid with the same composition as in the example was applied to the surface of this polyethylene terephthalate film at a solid content of 3.5 g/
After applying the first coat with a solid content of 3.5 g/m ² and drying at 145°C for about 8 seconds, the second coat was applied with a solid content of 3.5 g/m2.
It was dried at 150°C for about 20 seconds to a thickness of m ² .

[Table] The ink adhesion in the table above is based on the acrylic UV curing ink (product name: FD) applied to the highly rough side of the film.
-SS, manufactured by Toyo Ink Mfg. Co., Ltd.), and after curing by irradiation with an ultraviolet lamp, the adhesion between the ink and the film was tested by peeling with cellophane tape. As seen in the table above, the examples include Comparative Example 1, which uses only the kneading method, and Comparative Example 2, which mainly uses the coating method.
The tensile strength is greater than that of Furthermore, Comparative Example 1 had extremely poor ink adhesion. In addition, in the compositions in the above examples in which component (4) nitrocellulose and component (5) polyisocyanate were omitted, there was a slight difference in the surface hardness of the coating film compared to the examples, but the tensile strength No difference was observed in ink adhesion, productivity, etc.

Claims (1)

[Claims] 1. On the surface of a kneaded-type roughened polyester film with a glossiness of 110 or less, (1) a saturated copolymer ester component with a softening point of 150°C or higher and a glass transition temperature of 45°C or higher;
70% by weight, (2) 70 to 30% by weight of a saturated copolymerized ester component with a softening point of 130°C or less and a glass transition temperature of 10°C or less, and (3) an inorganic particle component based on 100 parts by weight of the above mixed copolymerized ester. 1. A method for producing an easily adhesive roughened polyester film, which comprises applying a composition comprising 10 to 40 parts by weight at a solid content of 2 to 6 g/m ² to give a glossiness of 60 or less. 2. The method for producing an easily adhesive roughened polyester film according to claim 1, wherein the roughened polyester film is formed from a polyester containing 80 mol% or more of ethylene terephthalate units.