JPH07156358A - Easy adhesive film for in-mold and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an easy adhesive film for in-mold having excellent adhesive properties at the time of molding by providing an aqueous polyester coating layer having specified secondary transition point on one or both side surfaces of a polyester film. CONSTITUTION:An easy adhesive film for in-mold comprising a coating layer having a thickness of 0.05-0.3mum and made of an aqueous polyester having a secondary transition point of 40 85 deg.C and formed on one or both side surfaces of a polyester film. A base film is coated with the aqueous polyester as an aqueous solution with the polyester as a main ingredient. As the aqueous liquid, the form of water solution, water dispersion or emulsion is suitable. A coating amount is desirably to become a range of 0.05-0.3mum of a thickness of a coating layer, or preferably 0.07-0.25mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-adhesive film for in-molding and a method for producing the same, and more particularly, an easy-adhesive film for in-molding useful as a supporting film for a transfer type printing film loaded in a mold in injection molding or the like. Film and its manufacturing method.

[0002]

2. Description of the Related Art When the adhesiveness between the medium layer of a transfer film for in-mold and the base film is low, the original release surface of the medium layer does not separate smoothly from the layer having the printing layer and the base film and the medium layer at the time of molding. It often peeled off. In addition, there were many problems that the base film and the medium layer were peeled off due to strain due to stretching during molding.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an easily adhesive film for in-mold which is excellent in adhesiveness during molding and a method for producing the same.

[0004]

According to the present invention, one of the objects of the present invention consists essentially of an aqueous polyester having a second-order transition point of 40 to 85 ° C on one side or both sides of the polyester film. This is achieved by an easily-adhesive film for in-mold forming a coating layer having a thickness of 0.05 to 0.3 μm.

Another object of the present invention is to provide a polyester film having a second-order transition point of 40 to 40 on one side or both sides.
This is achieved by the method for producing an easily adhesive film for in-mold by coating an aqueous liquid containing an aqueous polyester at 85 ° C. as a main component, drying and then stretching.

Since the coating layer in the easily adhesive film for in-molding of the present invention has high adhesiveness, it is possible to perform uniform transfer without peeling off the interface during molding.

The polyester forming the base film of the film of the present invention is terephthalic acid, isophthalic acid, 2,
Produced from aromatic dicarboxylic acid components such as 6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid and aliphatic or alicyclic glycol components such as ethylene glycol, 1,4-butanediol and 1,6-hexanediol To be done. Specific examples thereof include polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate. Copolymerized polyesters containing the above polyester as a main component can of course be used. Organic or inorganic fine particle fillers may be added to these polyesters as needed.

As such fine particles, those which are usually added to a polyester film are used. Examples thereof include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, carbon black, silicon carbide, Examples thereof include tin oxide, acrylic resin particles, polystyrene resin particles, melamine resin particles, and silicone resin particles. Further, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, other resins and the like can be appropriately added to the polyester.

The polyester film as the base film in the present invention may have a thickness generally used as an in-mold film and has a thickness of 10 to 150 μm.
m, preferably 20 to 100 μm.

In the easily-adhesive film for in-molding of the present invention, a coating layer made of an aqueous polyester is formed on one side or both sides of the base film. The aqueous polyester forming this coating layer has a second-order transition point (Tg) of 40 to 85 ° C, preferably 45 to 80 ° C. When the second-order transition point (Tg) of the water-based polyester is less than 40 ° C, the resulting film has low heat resistance and poor blocking resistance, which is disadvantageous. On the other hand, when it exceeds 85 ° C, adhesiveness is poor. Not desirable.

The aqueous polyester forming the coating layer is a water-soluble or dispersible polyester. As such an aqueous polyester, terephthalic acid, isophthalic acid,
Phthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid,
Polycarboxylic acid components such as phenylindane dicarboxylic acid, adipic acid, sebacic acid, 5-Na sulfoisophthalic acid, trimellitic acid, dimethylolpropionic acid and ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1 It is produced from polyhydroxy compound components such as 1,6-hexanediol, 1,6-cyclohexanedimethanol, glycerin, trimethylolpropane and alkylene oxide adducts of bisphenol A.

When it is necessary to impart hydrophilicity to the water-based polyester, SO3Na is added to the polyester.
A group or a COONa group may be introduced, or a polyether component may be introduced. These aqueous polyesters are used in the form of an aqueous solution, an aqueous dispersion or an emulsion to form a coating layer. To form a coating layer,
Other than the water-based polyester, other resins, antistatic agents, organic or inorganic fillers, colorants, surfactants, ultraviolet absorbers and the like can be added.

The aqueous polyester is applied on the base film as an aqueous solution containing it as a main component. The aqueous liquid is suitably in the form of an aqueous solution, an aqueous dispersion or an emulsion.

The coating is applied to an unstretched film, a uniaxially stretched film, a biaxially stretched film and the like, but it is preferable to apply it to a film stretched in the machine direction. After coating, transverse stretching, and in some cases, re-longitudinal stretching or re-lateral stretching can be performed. The coating amount is such that the thickness of the coating layer is 0.05 to 0.3 μm.
The amount is preferably in the range of 0.07 to 0.25 μm. If the thickness of the coating film is less than 0.05 μm, the adhesive strength will be insufficient, while if it exceeds 0.3 μm, blocking is likely to occur. The easily-adhesive film thus obtained is well adhered to the medium layer of the in-mold transfer film and has high practicality.

The medium layer serves as a release layer in the in-mold molding and has releasability from the other printed top coat layer. The medium layer is usually formed by applying and drying a solution of melamine resin or the like. Therefore, the medium layer plays an important role in controlling transferability in the transfer foil.

In the present invention, as a medium layer, a methyl ethyl ketone / toluene solution of melamine resin was applied to form a film having a thickness of 1 μm, and the adhesive strength was evaluated as follows.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples. The adhesive strength evaluation was measured by the following method.

<Evaluation of Adhesive Strength> A medium layer was provided on the coated surface of the film, and the state of the medium layer was observed when the laminate was formed by a hot pressing method and then placed on a mold. A: No change B: Partial peeling C: Whole peeling

Example 1 An unstretched sheet of calcium carbonate-containing polyethylene terephthalate having an intrinsic viscosity of 0.62 was stretched 3.6 times in the machine direction, and then terephthalic acid-isophthalic acid-5-K sulfoisofuric acid-ethylene glycol-neopentyl. An aqueous liquid having a concentration of 8% of a composition comprising 85% by weight of glycol copolymerized polyester P (Tg = 68 ° C.) and 15% by weight of polyoxyethylene nonylphenyl ether was applied by a roll coater, and was dried in the lateral direction 3. The film was stretched 8 times and heat-set at 220 ° C. to obtain a film (40 μm). The thickness of the coating layer was 0.15 μm. The characteristics of this film are shown in Table 1.

Comparative Example 1 Table 1 shows the characteristics of the film obtained in the same manner as in Example 1 except that the coating was not performed.

Examples 2 to 7 Table 1 shows the results obtained in the same manner as in Example 1 except that the coating agent and the coating amount were changed.

[0022]

[Table 1]

<Composition of polyester for coating> Q: 2,6-naphthalenedicarboxylic acid-terephthalic acid-
5-Na sulfoisophthalic acid-ethylene glycol-copolymerized polyester of ethylene oxide adduct of bisphenol A (Tg = 53 ° C.) R: terephthalic acid-isophthalic acid-ethylene gucoryl-1,4-butanediol-diethylene gucoryl- Polyethylene glycol copolyester (Tg = 47
℃)

[0024]

EFFECTS OF THE INVENTION According to the present invention, an easily adhesive film for in-mold which is excellent in adhesiveness during molding and a method for producing the same are provided.

Claims (3)

[Claims] 1. An in-mold product comprising a polyester film, on one or both sides of which a second-order transition point is substantially formed of an aqueous polyester having a secondary transition point of 40 to 85 ° C. and a thickness of 0.05 to 0.3 μm. Easy-adhesive film. 2. A film for in-molding, further comprising a medium layer formed on the surface of the coating layer of the film according to claim 1. 3. A polyester film is coated on one side or both sides thereof with an aqueous liquid containing a water-based polyester having a second-order transition point of 40 to 85 ° C. as a main component, dried, and then stretched. A method for producing the easily adhesive film for in-mold described.