JP3136570B2 - Polyester laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for various labels, delivery slips, recording paper for printers, etc., and has improved adhesion such as oxidation polymerization type ink, UV curing type ink and back carbon ink. The present invention relates to a polyester-based laminated film having properties.

[0002]

2. Description of the Related Art Synthetic paper made from synthetic resin as a main raw material is superior to natural paper in terms of water resistance, moisture absorption dimensional stability, surface smoothness, gloss and sharpness of printing, and mechanical strength. I have. The conventional white film for synthetic paper is made of olefin resin as the main raw material, to which inorganic fillers and a small amount of additives are added, and which are produced by generating fine bubbles by a biaxially stretched film forming method. I was But,
Such olefin-based synthetic papers have poor heat resistance and poor adhesion to natural paper, easily causing wrinkles, and a difference in expansion and contraction between the olefin-based synthetic paper and natural paper over time. However, there is a disadvantage that it is difficult to operate the collator, and there is a disadvantage that inks suitable for printing are limited. Further, the above-mentioned synthetic paper has a drawback that carbon ink adhesion and toner adhesion are insufficient.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to improve dimensional stability and mechanical properties by improving a resin composition of a surface layer. Polyester laminate film with excellent strength, various ink adhesion and toner adhesion, clear and durable printing, printing and copying, etc., suitable for general labels, barcode labels, delivery slips and various information recording papers Is to provide.

[0004]

According to the present invention, there is provided a polyester-based laminated film comprising a base polyester film having a large number of fine cavities, at least one surface of which is composed of a copolymerized polyester resin (A) containing a branched glycol as a constituent, A surface layer comprising a composition containing a resin (B) containing an isocyanate group and a surface roughening substance (C) is laminated, thereby achieving the object of the present invention.

The base film used in the polyester laminated film of the present invention mainly comprises a resin composition obtained from a polymer mixture obtained by mixing a polyester having an ethylene terephthalate repeating unit and a polystyrene resin in a uniaxial orientation. It is manufactured by doing. This substrate film has many fine cavities on its surface and inside. As the polystyrene resin, it is preferable to use a resin having an extractable amount of n-hexane of 50% by weight or less.

In order to obtain an intended laminated film in the present invention, at least one surface of the base film is provided
A composition containing a copolymerized polyester resin (A) containing a branched glycol as a component, a resin (B) containing a block type isocyanate group, and a surface roughening substance (C) is applied, and a heat fixing treatment is performed. To form a surface layer.

The copolymerized polyester resin (A) containing a branched glycol as a constituent component used in the polyester laminated film of the present invention is water-soluble or water-dispersible, and its composition is polyester: butyl cellosolve:
Water = 30: 15: 55 (weight ratio). Further, the resin (A) has a sulfonic acid group.

The branched glycol component contained in the copolymerized polyester resin (A) includes 2,2-dimethyl
-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3- Propanediol, 2-methyl-2-butyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol, 2,2-diethyl
-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2,2-di-n- Butyl-1,3-propanediol, 2-
n-butyl-2-propyl-1,3-propanediol, and 2,
2-di-n-hexyl-1,3-propanediol and the like. The above-mentioned branched glycol component is contained in all the glycol components preferably in a proportion of 10 mol% or more, more preferably in a proportion of 20 mol% or more. As the glycol component other than the above-mentioned compound contained in the above-mentioned copolymerized polyester resin (A), ethylene glycol is most preferable. If the amount is small, diethylene glycol, propylene glycol, butanediol, hexanediol or 1,4-cyclohexanedimethanol may be used.

As the dicarboxylic acid component contained as a component in the copolymerized polyester resin (A), terephthalic acid and isophthalic acid are most preferred. If the amount is small, other dicarboxylic acid components, for example, fatty acid dicarboxylic acids such as adipic acid, sebacic acid and azelaic acid; and aromatic dicarboxylic acids such as diphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid are added to form a copolymer. It may be polymerized.

The resin (B) containing a blocked isocyanate used in the polyester laminated film of the present invention is a heat-reactive water-soluble urethane in which terminal isocyanate groups are blocked by a hydrophilic group (hereinafter referred to as a block). It is a resin and usually has a composition of urethane: water = 20: 80 (weight ratio).

Examples of the isocyanate group blocking agent include bisulfites and phenols, alcohols, lactams, oximes and active methylene compounds containing a sulfone group. The blocked isocyanate group renders the urethane prepolymer hydrophilic or water-soluble. When thermal energy is applied to the resin (B) during the drying or heat setting process during film production, the blocking agent comes off from the isocyanate group, so that the resin (B) is mixed together in a self-crosslinked network. The water-dispersible copolymerized polyester resin (A) is immobilized and also reacts with the terminal groups of the resin (A). The resin (B) at the time of preparing the coating solution is hydrophilic and thus has poor water resistance. However, when the thermal reaction is completed through the steps of coating, drying and heat setting, the hydrophilic group of the urethane resin (B), that is, the blocking agent However, a coating film having good water resistance can be obtained. Among the above-mentioned blocking agents, bisulfites which are suitable for the heat treatment temperature and heat treatment time and are particularly suitable as those widely used industrially are bisulfites.

The chemical composition of the urethane prepolymer used in the resin (B) is as follows: (1) a compound having two or more active hydrogen atoms in a molecule and having a molecular weight of 200 to 2;
2,000 compounds, (2) an organic polyisocyanate having two or more isocyanate groups in the molecule, or (3) a chain extender having at least two active hydrogen atoms in the molecule. And a compound having an isocyanate group at the terminal.

What is generally known as the compound of the above (1) is a compound containing two or more hydroxyl groups, carboxyl groups, amino groups or mercapto groups at the terminal or in the molecule. Particularly preferred compounds are Polyether polyols, polyester polyols, polyether ester polyols and the like can be mentioned. Examples of polyether polyols include compounds obtained by polymerizing alkylene oxides such as ethylene oxide and propylene oxide, or compounds obtained by polymerizing styrene oxide and epichlorohydrin, or random copolymerization, block copolymerization, or addition polymerization to a polyhydric alcohol. And the like. Polyester polyols and polyetherester polyols mainly include linear or branched compounds, and include polyvalent saturated and unsaturated carboxylic acids such as succinic acid, adipic acid, phthalic acid and maleic anhydride, or the carboxylic acids. Acid anhydrides and the like, ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol,
Condensation with polyvalent saturated and unsaturated alcohols such as 1,6-hexanediol and trimethylolpropane, polyalkylene ether glycols such as relatively low molecular weight polyethylene glycol and polypropylene glycol, or a mixture of these alcohols Can be generated. Further, polyester polyols include polyesters obtained from lactones and hydroxy acids, and polyetherester polyols include polyetheresters obtained by adding ethylene oxide or propylene oxide to polyesters produced in advance. Can be

As the organic polyisocyanate (2), isomers of toluylene diisocyanate, 4,4'-
Aromatic diisocyanates such as diphenylmethane diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and 2,2,4- Examples thereof include aliphatic diisocyanates such as trimethylhexamethylene diisocyanate, and polyisocyanates obtained by adding one or more of these compounds to trimethylolpropane or the like in advance.

Examples of the chain extender having at least two active hydrogens of the above (3) include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol and 1,6-hexanediol, glycerin, trimethylolpropane and the like. And polyhydric alcohols such as pentaerythritol, diamines such as ethylenediamine, hexamethylenediamine and piperazine, aminoalcohols such as monoethanolamine and diethanolamine, thiodiglycols such as thiodiethylene glycol, and water.

In order to synthesize the urethane prepolymer of the above (3), a single-stage or multi-stage isocyanate polyaddition method using the above chain extender is carried out at a temperature of 150 ° C. or less, preferably 70 to 120 ° C. Let react for minutes to several hours. The equivalent ratio of isocyanate groups to active hydrogen atoms can be freely selected as long as it is 1 or more, but it is necessary that free isocyanate groups remain in the obtained urethane prepolymer. Further, the content of free isocyanate groups may be 10% by weight or less, but is preferably 7% by weight or less in consideration of the stability of the aqueous urethane prepolymer solution after blocking.

The urethane prepolymer obtained is preferably blocked with bisulfite. The mixture is mixed with an aqueous solution of bisulfuric acid, and the reaction is allowed to proceed with good stirring for about 5 minutes to 1 hour. The reaction temperature is preferably set to 60 ° C. or lower. Thereafter, the mixture is diluted with water to an appropriate concentration to obtain a heat-reactive water-soluble urethane composition. When the composition is used,
It is adjusted to an appropriate concentration and viscosity.
When heated to around ° C, the bisulfite of the blocking agent is dissociated, and the active isocyanate groups are regenerated. Thus, a polyurethane polymer is formed by intramolecular or intermolecular polyaddition reaction of the prepolymer or other functional groups. It has the property of causing addition to a group.

As an example of the resin (B) containing a blocked isocyanate group described above, Elastron H-3 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. is typically exemplified. Elastrone is obtained by blocking an isocyanate group with sodium bisulfite, and is water-soluble because a carbamoyl sulfonate group having strong hydrophilicity is present at a molecular terminal.

Surface roughening substance (C) used in the present invention
Is not particularly limited as long as the particles are in close contact with the binder of the resin composition, and particularly have an average particle diameter of 0.6 to 6 μm.
Inorganic or organic particles are preferred. More preferably, the inorganic particles are silica or calcium carbonate, and the organic particles are melamine or benzoguanamine / melamine copolymer resin. When inorganic and organic particles other than the above-mentioned composition are used, there is a possibility that adhesion to the binder may not be sufficiently obtained. When the inorganic particles or the organic particles constituting the surface roughening substance (C) are both smaller than the average particle diameter, the composition of the inorganic particles is silica or calcium carbonate,
Further, even if the composition of the organic particles is a melamine-based or benzoguanamine-melamine resin, sufficient adhesion between the carbon ink and the toner cannot be obtained. Similarly, if the average particle size is not less than the above, sufficient adhesion to the binder cannot be obtained.

In the present invention, the weight ratio of the resin (A) to the resin (B) is preferably (A) :( B) = 10: 90 to 90:10, and more preferably (A) :( B) = 30: 70 ~
70:30. When the ratio of the resin (A) to the solid content is 10% by weight or less, the adhesion of the surface layer to the substrate film is inappropriate, and when it exceeds 90% by weight, the UV curing of the surface layer of the substrate film is performed. Sufficient adhesion of the mold ink cannot be obtained. The addition amount of the surface roughening substance (C) used in the present invention to the coating solution (resin composition) is as follows:
It is preferably from 1% by weight to 30% by weight, more preferably from 3% by weight to 5% by weight. When the ratio of the surface roughening substance (C) is 1% by weight or less, sufficient adhesion between the carbon ink and the toner cannot be obtained, and the writing property is poor. When the ratio of the surface roughening substance (C) exceeds 30% by weight, sufficient adhesion to the surface layer of the base film cannot be obtained.

In order to form a surface layer on a substrate film,
A resin composition is prepared by previously mixing predetermined amounts of a copolymerized polyester resin (A) containing a branched glycol as a constituent, a resin (B) containing a blocked isocyanate group, a surface roughening substance (C) and a solvent. Then, the resin composition may be applied using a normal coating device such as a gravure coater, a reverse kiss coater, a reverse roll coater, a multilayer curtain coater, a bar coater, or an air doctor coater, and the application method is not limited to this. I don't care.

The resin composition used in the present invention may further contain an antistatic agent, an antiblocking agent, an antioxidant, a surfactant, a lubricant and the like, if necessary.

The polyester laminated film of the present invention comprises:
The coating liquid may be applied to at least one surface of the base film containing the microvoids stretched in the uniaxial direction, and the film may be further manufactured by a method of stretching in a direction perpendicular to the direction of the further uniaxial stretching. I don't care.

The thickness of the coating solution on the polyester-based laminated film in the present invention is preferably 0.01 to 5 μm,
More preferably, it is in the range of 0.05 to 2 μm. In this case, the thickness of the surface layer is about 0.01 to 0.6 μm (dry state). When the thickness of the coating liquid is 0.01 μm or less, the adhesion of the surface layer to the base film is not sufficiently obtained, or the adhesion of the surface roughening substance (C) to the surface layer is not sufficiently obtained. When the thickness of the coating liquid exceeds 5 μm, it is difficult to uniformly apply the coating liquid due to problems such as physical properties and rheology of the coating liquid and equipment.

The polyester-based laminated film of the present invention comprises:
General labels, stickers, delivery slips, information recording paper, and packaging paper because of good ink adhesion in oxidation polymerization type inks and UV curable inks, and good durability, abrasion resistance, and adhesion to toner in back carbon ink. And so on. Especially when used for delivery slips, it can be manufactured thinner because it has more stiffness than ordinary paper, and it is necessary to draw a large number of sheets with the same pen thickness or to draw clearly Becomes possible.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
The present invention is not limited by the following examples. The measurement and evaluation of various characteristics in the present invention were performed according to the following methods.

(1) Ink Adhesion The adhesion of the UV curable ink was evaluated based on the following method. The UV curable ink was printed on a base film using a Tetron screen (# 300 mesh), and then exposed to UV light at 500 mj. A cross-cut surface was placed on the cured ink layer, and a 90 ° peeling test was performed using a cellophane tape.

The adhesion of the oxidative polymerization type ink was evaluated based on the following method. After printing the oxidative polymerization type ink on the base film by using a Tetron screen (# 250 mesh), leave it for 16 to 24 hours, then insert a cross cut surface, perform a 90 ° peel test with a cellophane tape, and evaluate similarly. did.

(2) Carbon Adhesion Characters were written on the surface layer using carbon black, and the character portions were rubbed with a Gakushin type fastness tester. 1,000g
The readability of the character after reciprocating 50 times under the load was visually evaluated.

(Example 1) As a raw material, a water-dispersible copolymerized polyester resin (A) (manufactured by Toyobo Co., Ltd., MD-16) containing a branched glycol as a constituent, a thermal reaction type containing a blocked isocyanate group Water-soluble urethane resin (B) (Elastron H-3, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
In addition, benzoguanamine / melamine copolymerized organic particles (C) (manufactured by Nippon Shokubai Kagaku Co., Ltd.) having an average particle diameter of 2 μm were used. First, the organic particles (C) are sufficiently dispersed in a mixture of water and isopropyl alcohol using a homogenizer or a Dynomill, and then 1.5% by weight of the resin (A) and the resin ( B) 1.5% by weight
And 3% by weight of organic particles (C) were sufficiently mixed to prepare a coating resin composition. This resin composition for application was applied on a base film (white polyester film) using a wire bar (No. 5). The coating amount of the coating liquid was about 10 g (wet state) per 1 m ^{2 of the} base film. The coating solution was dried at 70 ° C. for 60 seconds, and then heat-treated at 200 ° C. for 30 seconds.

Table 1 shows the results of evaluation of the properties of the obtained laminated film. The adhesion of the surface layer to the substrate film was extremely good. The adhesion between the base film provided with the surface layer and the main binder resin (ink, carbon ink, toner, etc.) of the surface layer material in various applications was also extremely excellent.

(Example 2) In the same manner as in Example 1, 6% by weight of the resin (A), 6% by weight of the resin (B), and 12% by weight of the organic particles (C) were sufficiently mixed and applied. A resin composition for use was prepared. This resin composition for application was applied on a base film (unstretched white polyester) using a wire bar (No. 5). The coating amount of the coating liquid was about 10 g (wet state) per 1 m ^{2 of the} base film.
After stretching the base film coated with the coating solution four times, 2
Heat treatment was performed at 20 ° C. for 30 seconds. Table 1 shows the results of evaluating the properties of the obtained laminated film. The adhesion of the surface layer to the substrate film was extremely good. The adhesion between the base film provided with the surface layer and the main binder resin of the surface layer material for various uses was also extremely excellent.

Example 3 A polyester-based laminated film was obtained in exactly the same manner as in Example 1 except that silica-based inorganic particles having an average particle size of 2.5 μm were used instead of the organic-based particles. Table 1 shows the results of evaluating the characteristics of the obtained film. The adhesion of the surface layer to the substrate film was very good. The adhesion between the base film provided with the surface layer and the main binder resin of the surface layer material for various uses was also extremely excellent.

Example 4 A polyester laminated film was obtained in exactly the same manner as in Example 2 except that calcium carbonate-based inorganic particles having an average particle size of 1.2 μm were used instead of the organic particles. Table 1 shows the results. The adhesion of the carbon ink was somewhat insufficient.

Example 5 0.3% by weight of resin (A)
A polyester-based laminated film was obtained in exactly the same manner as in Example 1 except that the amount of the resin (B) was changed to 2.7% by weight. Table 1 shows the results. The adhesion of the surface layer to the substrate film was somewhat insufficient.

Example 6 2.7% by weight of resin (A)
Example 1 except that the amount of the resin (B) was changed to 0.3% by weight.
In the same manner as in Example 1, a polyester-based laminated film was obtained. Table 1 shows the results. The adhesion of the UV-curable ink was somewhat insufficient.

(Example 7) The average particle size of the organic particles was set to 0.1.
A polyester-based laminated film was obtained in exactly the same manner as in Example 1 except that the thickness was changed to 5 μm. Table 1 shows the results. The adhesion of the carbon ink was somewhat insufficient.

[0038]

[Table 1]

Note) I.C: In-line coating O.C: Off-line coating ：: Extremely good ○: Good △: Somewhat bad ×: Very bad

[0040]

As is apparent from the above description, according to the polyester-based laminated film of the present invention, it is possible to obtain a drawing property with improved adhesion of an oxidation polymerization type ink, a UV curable ink and a back carbon ink. A base film having the same can be provided.

Continuation of front page (56) References JP-A-3-292338 (JP, A) JP-A-2-50835 (JP, A) JP-A-58-78761 (JP, A) JP-A-62-97890 (JP) JP-A-2-158633 (JP, A) JP-A-51-109980 (JP, A) JP-A-60-106838 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B32B 1/00-35/00 C08J 7/04 B41M 1/00-3/18

Claims (2)

(57) [Claims] 1. A polyester base film having a large number of fine cavities, a copolymerized polyester resin (A) containing a branched glycol as a component, a resin (B) containing a block type isocyanate group, and a surface on at least one surface of the film. A polyester-based laminated film, wherein a surface layer made of a composition containing a roughening substance (C) is laminated. 2. The method according to claim 1, wherein the surface-roughening substance has an average particle size of 0.3-1.
The polyester-based laminated film according to claim 1, wherein the particles are particles of 0 µm.