JP3443479B2 - Flexible laminated polyester film for window application - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible laminated polyester film for adhering windows. More specifically, the present invention is used for adhering to windows of automobiles, windows of buildings, etc. for the purpose of shading and preventing scattering. The present invention relates to a flexible laminated polyester film for window sticking, which has excellent workability in sticking and has little shrinkage after sticking.

[0002]

2. Description of the Related Art At present, heat resistance, water resistance, chemical resistance, mechanical strength, etc. are excellent in the windows of automobiles and windows of buildings for the purpose of shading and preventing scattering. Polyester film is mainly used. However, this polyester film is poor in flexibility when it is applied to the surface to be adhered, so that the adhesiveness is particularly poor for those having a curved surface, and there is a problem of poor workability in which air bubbles are partially formed. It was. In addition, it causes shrinkage after bonding, which has been a problem in practical use and appearance.

[0003]

In view of the above circumstances, the inventors of the present invention have conducted extensive studies on the development of a polyester film excellent in workability and heat shrinkage resistance, and as a result, have obtained a laminated polyester film having a specific structure. Has found that the above-mentioned problems can be solved and completed the present invention.

That is, the gist of the present invention is a polyester film which is composited by co-extrusion and comprises at least three polyester layers of A layer, B layer and C layer, of which the outer layer is the outer layer. A layer and C layer which are are substantially homopolyester, and B which is an intermediate layer
A flexible laminated polyester film for window bonding, wherein the layer is a copolyester having a melting point of 150 to 250 ° C.

The present invention will be described in more detail below. In the present invention, the composite polyester film,
A film extruded by a so-called coextrusion method in which all layers are melt extruded together from an extrusion die,
It is a film that is later oriented in the biaxial directions of the machine direction and the transverse direction. In the present invention, the polyester constituting the outer layers A and C in the composite layer is substantially homopolyester. Such a polyester is obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol and
Examples include diethylene glycol and 1,4-cyclohexanedimethanol. Typical polyesters include polyethylene terephthalate (PET) and polyethylene-2,6-naphthalene dicarboxylate (PE).
N) etc. are illustrated.

In the present invention, of the composite layers,
The polyester constituting the intermediate layer B has a melting point of 150.
It consists of a copolyester having a temperature of ℃ to 250 ℃. The polyester is a copolymer containing 3 to 30 mol% of the third component. Examples of the dicarboxylic acid component of the copolymerized polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid,
Sebacic acid and oxycarboxylic acid (for example, P-
Oxybenzoic acid and the like), and glycol components include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like. To be

Among the composite layers, preferred as the particles contained in the polyester constituting the outer layers A and C, the average particle diameter is 0.02 to 3.0 μm,
Silicon oxide, alumina, calcium carbonate, kaolin and JP-B-59-5, which are preferably 0.02-2.0 μm,
Examples thereof include crosslinked polymer fine powder as described in Japanese Patent No. 216. These particles may be used alone or in combination of two or more. And the content is 0.02-1.0% by weight, and further 0.04-
A range of 0.5% by weight is preferred. The content of particles is 0.0
If it is less than 2% by weight, the winding property in the film manufacturing process tends to be poor. The content of particles is 1.0% by weight.
When it exceeds, the degree of roughening of the film surface becomes too large and the transparency may be impaired. Among the composite layers, it is preferable that the copolymerized polyester forming the intermediate layer B does not substantially contain particles. The substantially particle-free copolyester is the above-mentioned copolyester, in which the amount of insoluble residual particles when a biaxially stretched film of the copolyester alone is dissolved in an o-chlorophenol solvent, It means less than 0.02% by weight. The intermediate layer may be a laminate.

[0008] Of the composite layers, the method of blending the particles with the polyester constituting the outer layers A and C is not particularly limited, and a known method can be adopted. For example, it can be added at any stage of producing a polyester, but is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification, or after the completion of the transesterification reaction and before the start of the polycondensation reaction, The polycondensation reaction may proceed. Further, a method of blending a slurry of particles dispersed in ethylene glycol or water with a polyester raw material using a kneading extruder with a vent, or a method of blending dried particles and a polyester raw material using a kneading extruder. Done by In the present invention, in the composite polyester film, it is also a preferable method to contain an organic lubricant in the A layer and the C layer in addition to the above-mentioned particles in order to improve the slipperiness of the film.

The kind of the organic lubricant is not particularly limited, but aliphatic compounds, fatty acid esters, alkylenebisaliphatic compounds, aromatic amides and the like are preferable.
As the aliphatic compound, those having a large number of carbon atoms such as montanic acid are preferable. Further, examples of the aliphatic ester include montanic acid ethylene glycol ester and the like. Examples of the alkylenebis aliphatic and aromatic amides include hexamethylenebisbehenamide, hexamethylenebisstearylamide, N, N′-distearylterephthalamide and the like. The content of these organic lubricants in the film is preferably 500 ppm or less, more preferably 200 ppm or less. If these lubricants are mixed in too much, there is a possibility that the adhesiveness at the time of applying various coatings to the film may be deteriorated, or that the tint of the film may be too yellow.

Further, for the purpose of improving the adhesiveness of the film, it is also preferable that the layer A and the layer C contain polyalkylene glycols. Examples of the polyalkylene glycol include polyethylene glycol, polytetramethylene glycol, polypropylene glycol and the like. As a method of containing these polyalkylene glycols in the film, during transesterification,
Any method such as addition to the reaction system during polymerization, blending with a polymer obtained by copolymerizing polyalkylene glycol, kneading at the time of drying the polyester, or kneading at the time of extrusion may be used. However, the polyalkylene glycol has a molecular weight of 1 so as not to impair the transparency of the film of the present invention.
It is preferable to use 0000 or less, more preferably 8000 or less, and the content in the film is preferably 1.0% by weight or less, more preferably 0.5% by weight or less.

Further, the outer layer may contain additives such as a stabilizer and an antioxidant, if necessary. In the present invention, in the B layer of the intermediate layer, an anthraquinone-based dye, a phthalocyanine-based dye, a disperse dye, an oil-soluble dye, etc. are appropriately selected in order to adjust the visible light transmittance, and are contained alone or in combination of several kinds. be able to. The content of these in the polyester is preferably 10% by weight or less. When it exceeds 10% by weight, the visible light transmittance is adjusted in a wide range, but the B layer is easily deteriorated, which is not preferable. Further, for the purpose of blocking infrared rays, ultraviolet rays, etc., an infrared absorbing agent, an ultraviolet absorbing agent, etc. may be contained.

In the present invention, in the composite polyester film, the proportion of the layer composed of the copolyester is 30 to 90%, more preferably 40 to 80%.
%, Particularly 50 to 70% is preferable. This value is 3
If it is less than 0%, the workability tends to be poor at the time of sticking to windows of automobiles. Further, if it exceeds 90%, the mechanical strength tends to decrease.

In the present invention, the heat shrinkage ratio in the MD (longitudinal) direction and the TD (horizontal) of the composite polyester film
The sum of the absolute values of the heat shrinkage in the directions is within 0.5%, preferably within 0.4%, and more preferably within 0.3%. If this value exceeds 0.5%, shrinkage may occur after the bonding process, the bonding area may decrease, and the light-shielding / scattering-preventing effect may decrease.

The laminated polyester film of the present invention may have any thickness as long as it can be formed into a film.
A film having a thickness of 250 μm, preferably 10 to 120 μm, and more preferably 15 to 60 μm exhibits excellent effects. If this value is less than 5 μm, the effect of preventing scattering when the adherend is damaged tends to decrease.
Further, if this value exceeds 250 μm, the bonding workability is deteriorated, which is not preferable. Next, the method for producing the polyester film of the present invention will be specifically described, but the film of the present invention is not limited to the following production examples.

That is, using the above-mentioned polyester raw material, using a plurality of extruders, a plurality of layers of a multi-manifold die or a feed block, the respective polyesters are laminated and a plurality of layers of molten sheets are extruded from a die, A method of obtaining an unstretched sheet by cooling and solidifying with a cooling roll is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to enhance the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and / or the liquid application adhesion method is preferably adopted.

In the electrostatic application contact method, usually, a linear electrode is stretched on the upper surface side of the sheet in a direction orthogonal to the flow of the sheet,
By applying a DC voltage of about 5 to 10 kV to the electrodes, an electrostatic charge is applied to the sheet to improve the adhesion between the sheet and the drum. In addition, the liquid application contact method is a method for improving the adhesion between the drum and the sheet by uniformly applying the liquid to the whole or part of the surface of the rotary cooling drum (for example, only the portions that contact both ends of the sheet). Is. In the present invention, both may be used together if necessary.

Then, the obtained unstretched film is biaxially stretched and biaxially oriented. That is, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120.
C., preferably 80 to 110.degree. C., and the draw ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Then, stretching is performed in a direction orthogonal to the stretching direction of the first stage. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 11
It is 5 ° C., and the draw ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Then, in order to keep the heat shrinkage rate within the scope of the claims, heat treatment is performed at a temperature of 130 to 250 ° C. below the melting point of the copolyester used and under relaxation of 30% or less. An axially stretched film is obtained. So-called in-line coating can be applied to treat the film surface during the stretching step. It is not limited to the following, but especially after the first stage stretching is completed and before the second stage stretching, the antistatic property, the slip property, the adhesive property, etc. are improved, and the secondary processability is improved. For the purpose, the coating treatment with an aqueous solution, an aqueous emulsion, an aqueous slurry or the like can be performed.

In the above stretching, stretching in one direction is performed in two.
It is also possible to use a method that is performed in more than one step. In that case,
Finally, it is preferable that the stretching ratio in each of the two directions be within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area ratio becomes 10 to 40 times. Further, if necessary, it may be stretched again in the machine direction and / or the transverse direction before or after the heat treatment. The film thus obtained has, for example, a hard coat layer formed on the surface thereof, and then a pressure-sensitive adhesive layer containing a UV absorber, an infrared absorber, etc. formed on the surface opposite to the hard coat layer surface. Then, it is laminated with a separator (release paper) in which a release agent is applied to a polyester film or the like to obtain a window sticking film.

[0019]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples and comparative examples, “part” means “part by weight”. The measuring method used in the present invention is as follows. (1) Melting point of copolymerized polyester The melting point is the endothermic peak temperature due to crystal melting obtained at a temperature rising rate of 16 ° C./min with DSC7 type manufactured by Perkin Elmer. The sample used for this measurement is a film obtained by biaxially stretching the polyester used for the intermediate layer of the B layer alone.

(2) Film Lamination Thickness After fixing and molding a small sample film piece with epoxy resin,
After cutting with a microtome, the cross section of the film was observed with a transmission electron microscope. In the cross section, the interface is observed almost parallel to the film surface by light and dark. The distance from the interface to the film surface and the distance to the intermediate layer were averaged for one transmission electron micrograph to calculate the thickness. This was performed on at least 50 photographs, and 10 points from the thickest measured value and 10 points from the thinned value were deleted, and the arithmetic mean of 30 points was taken as the film thickness. Based on this film thickness, the copolymer layer ratio was calculated by the following formula.

[0021]

[Equation 1]

(3) Heat shrinkage rate A sample whose length has been measured in advance is 100 ° C. without tension.
After heat treatment for 2 hours in the hot air circulation type constant temperature bath of
The following formula was calculated by measuring the length of the sample.

[0023]

[Equation 2] The absolute values of the values measured in the MD direction and the TD direction were added and divided into the following ranks. ◯: The added value is 0.5% or less ×: The added value exceeds 0.5%

(4) Laminating workability A hard coat layer is formed on the surface of the polyester film,
A pressure-sensitive adhesive layer was formed on the surface opposite to that, and a separator (release paper) was laminated on the adhesive layer to prepare a window laminating film. The film for window sticking is visually judged on the inside of the windows of automobiles using curved glass when the films are stuck together by a general method, and it is divided into the following ranks and it is used as a guide for workability. did. ○: Almost no air bubbles entered △: Some air bubbles entered ×: Many air bubbles entered

<Production of Polyester> Production Example 1 (Polyester A1) 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, heated and heated to distill off methanol. Then, the transesterification reaction was carried out, and it took 4 hours from the start of the reaction to raise the temperature to 230 ° C. to substantially end the transesterification reaction. Next, 0.04 parts of fine silica particles having an average particle diameter (d50) of 0.035 μm and an average particle diameter (d50) of 1.54
Ethylene glycol slurry containing 0.0125 parts of μm amorphous silica was added to the reaction system, and 0.04 parts of ethyl acid phosphate and 0.04 parts of antimony trioxide were added, and then 100 minutes later. Temperature 280
C., the pressure was set to 15 mmHg, and thereafter the pressure was gradually reduced to 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyester A1. The content of fine silica particles in the polyester A1 was 0.04% by weight, and the content of amorphous silica particles was 0.0125% by weight.

Production Example 2 (Polyester A2) In Production Example 1, 0.04 parts of fine silica particles having an average particle diameter (d50) of 0.035 μm and an average particle diameter (d50) of 1.5 are used.
Polyester A2 was obtained in the same manner as in Production Example 1 except that ethylene glycol slurry containing 0.0125 parts of 4 .mu.m amorphous silica was not added to the reaction system.

Production Example 3 (Copolyester B1) Melting point was the same as in Production Example 1 except that the dicarboxylic acid component was changed to 90 parts of dimethyl terephthalate and 10 parts of dimethyl isophthalate and no particles were added. A copolyester B1 having a temperature of 230 ° C. was obtained.

Production Example 4 (Polyester B2) The same as Production Example 1 except that the dicarboxylic acid component was changed to 80 parts of dimethyl terephthalate and 20 parts of dimethyl isophthalate and no particles were added, and the melting point was 200 ° C. Copolymerized polyester B2 of

Example 1 Polyester A1 was dried at 180 ° C. for 4 hours in an inert gas atmosphere, and copolyester B1 was dried at 160 ° C. for 24 hours in a vacuum dryer, and melted at 290 ° C. in a separate melt extruder. The polymer was extruded, and these polymers were joined together in a feed block to be laminated, and were cooled and solidified on a cooling roll whose surface temperature was set to 40 ° C. by an electrostatic application adhesion method to obtain a laminated unstretched sheet. The obtained sheet was stretched 3.5 times in the machine direction at 85 ° C. Then, the film was introduced into a tenter and stretched 3.7 times in the transverse direction at 100 ° C.
Heat treatment was performed at 0 ° C. with relaxation of 7%, the layer constitution was A1 / B1 / A1, and the thickness of each layer was 15/20 /
A laminated film having a thickness of 15 (μm) and a thickness of 50 μm was obtained.

Example 2 By the same method as in Example 1, the layer constitution was A1 / B1 / A.
A laminated film having a thickness of 50 μm and a thickness of each layer of 10/30/10 (μm) was obtained. Example 3 The heat treatment temperature after stretching in the transverse direction in Example 1 was 1
By the same method as in Example 1 except that the temperature was 80 ° C., the layer constitution was A 1 / B 2 / A 1, and the thickness of each layer was 15/2.
A laminated film having a thickness of 0/15 (μm) and a thickness of 50 μm was obtained. Example 4 By the same method as in Example 3, the layer constitution was A1 / B2 / A.
A laminated film having a thickness of 50 μm and a thickness of each layer of 10/30/10 (μm) was obtained.

Comparative Example 1 By the same method as in Example 1, the layer constitution was A1 / B1 / A.
1 and the thickness of each layer was 23/4/23 (μm) to obtain a laminated film having a thickness of 50 μm. Comparative Example 2 The heat treatment temperature after stretching in the transverse direction in Example 1 was 2
By the same method as in Example 1 except that the temperature was 30 ° C., the layer constitution was A1 / A2 / A1 and the thickness of each layer was 15/20.
A laminated film having a thickness of / 15 (μm) and a thickness of 50 μm was obtained. Comparative Example 3 By the same method as in Example 1, the layer constitution was B1 / B1 / B.
A 50 μm thick monolayer film having a thickness of 1 was obtained. Since the obtained film was whitened when the window sticking film was formed, the sticking workability (x) was evaluated at this point. The results obtained above are summarized in Table 1 below.

[0032]

[Table 1]

[0033]

EFFECTS OF THE INVENTION According to the present invention, when laminating to windows of automobiles, windows of buildings, etc. for the purpose of shielding light, preventing scattering, etc., the laminating workability is excellent, and shrinkage after laminating does not occur. It is possible to provide a small amount of film for window attachment, and its industrial value is high.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-264843 (JP, A) JP-A-6-220406 (JP, A) JP-A-7-60926 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (2)

(57) [Claims] 1. A polyester film composited by coextrusion, comprising at least three polyester layers of A layer, B layer and C layer, wherein:
The outer layers A and C are substantially made of homopolyester, the intermediate layer B is a copolyester having a melting point of 150 to 250 ° C., and the thickness ratio of the B layer to the total film thickness is 30 to 30. 90% flexible laminated polyester film for window sticking. 2. An M of a composite polyester film
The sum of absolute values of the heat shrinkage rate in the D direction and the heat shrinkage rate in the TD direction is within 0.5%.
Flexible laminated polyester film for paste 1 Symbol placement of the window.