JPH1142705A - Production of biaxially stretched surface-roughened film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a biaxially stretched surface-roughened film composed of a resin compsn. wherein an amorphous polyamide resin is compounded with a thermoplastic polyester resin and having high surface haze and high strength, with good operability. SOLUTION: A mixture of 85-92 wt.% of a thermoplastic polyester resin A and 15-8 wt.% of an amorphous polyamide resin B having glass transition temp. higher than that of the resin A, having critical surface tension different from that of the resin A by 0.1 dyn/cm or more and having melt viscosity at 280 deg.C and a shearing speed of 10<-2> sec<-1> of 500-50000 poise is melted to be formed into an unstretched film and this film is stretched longitudinally and laterally successively to produce a biaxially stretched film. In this sequential biaxially stretched film producing method, longitudinal stretching is performed so that the double refractive index of the film after longitudinal stretching becomes 120×10<-3> -150×10<-3> and, next, lateral stretching is performed under a condition of temp. 90-150 deg.C and lateral stretching magnification of 3.0-4.0 times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester biaxially stretched roughened film having irregularities on the film surface by a sequential biaxial stretching method.

[0002]

2. Description of the Related Art Polyester biaxially stretched films represented by polyethylene terephthalate films have excellent physical and chemical properties, and are used for magnetic recording materials, packaging materials, electric insulating materials, photosensitive materials, various photographic materials, synthetic materials. It is used for many purposes such as paper.

[0003] Polyester films have different required characteristics depending on the application, but it is necessary to roughen the surface from the viewpoints of processability during manufacturing and processing, workability during handling, and writing. is there.

[0004] As a method of roughening the film surface,
Sand blasting method in which hard granular sand is sprayed on the film surface to roughen it, method of coating resin containing inorganic fine particles on the film surface, kneading inorganic fine particles such as silica and titanium dioxide in the resin for the film in advance And a chemical etching method in which the film surface is eroded with an acid, an alkali, a solvent, or the like. Roughening of the polyester film is mainly performed by a sand blast method or a coating method, and it is difficult to reduce the film haze to 40% or more because each is a treatment of the film surface.

Japanese Patent Application Laid-Open No. 6-206291 discloses a thermoplastic polyester resin having a high glass transition temperature of 90 to 96% by weight and a thermoplastic resin having a high glass transition temperature, such as an amorphous polyamide resin.
A biaxially stretched surface-roughened film comprising 1% by weight and a method for producing the same are disclosed.

However, in this method, although a film having good optical properties can be obtained, the strength of the obtained film tends to be reduced by adding an amorphous polyamide. In particular, when a high degree of surface roughening or high surface haze is required, a method of increasing the amount of the amorphous polyamide is adopted as a standard method. Become. In particular, if the strength in the vertical direction is insufficient, processing defects are likely to occur in processing steps such as printing and lamination.

[0007]

SUMMARY OF THE INVENTION The present invention provides a biaxially stretched, roughened film having a high surface haze and a high strength, which comprises a resin composition obtained by blending an amorphous polyamide resin with a thermoplastic polyester resin. It is intended to provide a method of manufacturing well.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. The gist of the present invention is that the thermoplastic polyester resin A has a glass transition temperature of 85 to 92% by weight, which is higher than that of the resin A, and has a critical surface tension. Is different from that of resin A by at least 0.1 dyn / cm, and has a melt viscosity of 500 to 50,000 poise at a temperature of 280 ° C. and a shear rate of 10 ² sec ^-1 .
In a method of producing a biaxially stretched film by a sequential biaxial stretching method in which a mixture consisting of 15 to 8% by weight is melt-formed into a non-stretched film, longitudinally stretched, and then transversely stretched, the film is stretched in a longitudinal direction. After longitudinal stretching so that the refractive index is 120 × 10 ^-3 to 150 × 10 ^-3 , the temperature is 90 to 150 ° C., and the transverse stretching ratio is 3.0.
A method for producing a biaxially stretched roughened film, characterized in that the film is transversely stretched under conditions of up to 4.0 times.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, as the thermoplastic polyester resin A, polyethylene terephthalate (PE)
T), polybutylene terephthalate (PBT), poly-
1,4-cyclohexylene dimethylene terephthalate (P
CT), poly-p-ethyleneoxybenzoate (PE
OB) and their copolymers or mixtures are preferably used.

The glass transition temperature (Tg) is measured by a differential thermal analysis (DSC) method.
Is about 50 ° C, PCT is about 95 ° C, and PEOB is about 60 ° C.

Next, the resin B used in the present invention is:
Tg is higher than that of resin A, and critical surface tension is higher than that of resin A.
Is an amorphous polyamide different from that of No. 0.1 dyn / cm or more.

If the Tg of the resin B is lower than that of the resin A, the resin B is plastically deformed together with the resin A during stretching, and the resin B does not become a nucleus, so that an intended roughened film cannot be obtained.
The resin B preferably has a Tg higher than that of the resin A by 10 ° C. or more, particularly preferably 20 ° C. or more. The higher the Tg of the resin B, the more
Although the surface roughening effect is easily exhibited, the temperature is preferably 200 ° C. or less in consideration of workability during polycondensation or melt film formation.

The resin A and the resin B are melt-mixed to form a composition in which the resin A forms a sea component and the resin B forms an island component, and is extruded into a film and further stretched. However, if the critical surface tension of the resin B is the same as or close to that of the resin A, compatibility is recognized, and the desired roughened film cannot be obtained. The difference between the critical surface tensions of the resin A and the resin B needs to be 0.1 dyn / cm or more.
/ Cm or more is desirable.

Further, the resin B is used at a temperature of 280 ° C. and a shear rate of 10
The melt viscosity at ² sec ^-1 must be in the range of 500 to 50000 poise. When the melt viscosity is less than 500 poise, the particles of the resin B dispersed in the matrix of the resin A become small, and the degree of film surface projection formation and concealing properties become insufficient. The particles become too large, the operability deteriorates, and the physical properties of the obtained film are impaired.

The resin B dispersed in the resin A is preferably as spherical as possible and has an average particle diameter of preferably 0.5
It is preferable that the thickness be in the range of 6.0 to 6.0 μm, more preferably in the range of 1.0 to 5.0 μm.

Examples of the resin B include 5-t-butylisophthalic acid, 1,1,3-trimethyl-3-phenylindane-
3,5-dicarboxylic acid, 3-aminomethyl-3,5,5-trimethyl-cyclohexylamine, 1,3-diaminocyclohexane, metaxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 2,4, 4-trimethylhexamethylenediamine, bis (4-aminocyclohexyl)
Amorphous polyamides containing components such as methane as constituents are preferred.

Other components constituting the amorphous polyamide include ethylenediamine, tetramethylenediamine, hexamethylenediamine, phenylenediamine, adipic acid, sebacic acid, cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid,
ε-caprolactam or ε-aminocaproic acid, 11-aminoundecanoic acid, ω-laurolactam or 12-aminododecanoic acid, 4-aminobenzoic acid and the like.

The ratio of the resin A to the resin B is as follows:
It is necessary that 85% by weight and resin B be 8 to 15% by weight. By mixing both resins at a ratio within this range, melt-mixing with a single-screw or twin-screw extruder to form a film, a film in which resin B is dispersed in resin A in a submicron class size is obtained. .

In the present invention, first, resin A and resin B
And an unstretched film is formed by a conventional method using a mixture of the above components at a predetermined ratio. That is, resin A and resin B
Is melt-kneaded with a single-screw or twin-screw extruder to finely disperse the resin B in the resin A, extrude it from a T-die into a film, and cool it with a casting roller. At this time, the degree of fine dispersion is adjusted by the conditions of melt-kneading according to the mixing ratio of both resins and the degree of surface roughening. Suitable melt-kneading conditions can be easily determined by experimentally kneading with the extruder used.

Next, after stretching the unstretched film longitudinally,
The film is biaxially stretched by transverse stretching, but it is necessary to longitudinally stretch the film after longitudinal stretching so that the birefringence of the film is 120 × 10 ⁻³ to 150 × 10 ⁻³ . If the birefringence of the film after longitudinal stretching is smaller than this range, a film with a desired longitudinal strength is not obtained, while if it exceeds this range, in the subsequent transverse stretching step, from the clip gripping portion Is continuously broken, and a stretched film cannot be obtained.

The longitudinal stretching can be performed using a usual roll stretching machine, and may be either one-stage stretching or multi-stage stretching of two or more stages. The stretching ratio is adjusted so that the birefringence falls within the above range. Just do it. A film having a higher longitudinal stretching ratio gives a film having a higher surface haze. However, if it is too high, the birefringence exceeds the above range, making it impossible to perform transverse stretching smoothly. The temperature for longitudinal stretching is 85 to
A suitable temperature is 90 ° C.

The transverse stretching can be performed using a normal tenter type transverse stretching machine, and after preheating with hot air at 85 to 110 ° C.,
The film is stretched under hot air at 90 to 150 ° C with a transverse stretching ratio of 3.0 to 4.0.
When the transverse stretching temperature is out of the above range, breakage occurs during transverse stretching, and a stretched film cannot be obtained. On the other hand, if the transverse stretching ratio is less than 3.0 times, an intended film having a large transverse strength cannot be obtained. The higher the transverse stretching ratio,
Although the strength in the transverse direction of the film increases, the haze of the film surface decreases. When the transverse stretching ratio exceeds 4.0 times, a film having a desired high surface haze cannot be obtained.

The roughened film obtained by the method of the present invention has a surface haze of 30 or more and a tensile strength at break in the longitudinal direction of 20 or more.
It has excellent properties of not less than 0 MPa and tensile strength in the transverse direction of not less than 150 MPa, and is useful as a matte film for packaging, a matte film for photographic printing, a matte film for aluminum vapor deposition, a synthetic paper, and the like.

In the present invention, the roughened film may be a laminated film with another thermoplastic resin film such as a PET film. In particular, a laminated film with a polyester film such as a PET film can be efficiently produced by a co-extrusion method.

[0026]

Next, the present invention will be described specifically with reference to examples. In addition, the measuring method is as follows. (a) Birefringence The birefringence was determined by measuring the retardation with a polarizing microscope manufactured by Nikon Corporation and dividing this by the film thickness. (b) Tensile rupture strength 150 mm in length in the longitudinal or transverse direction from the biaxially stretched film,
A 10 mm wide sample was collected and used for Shimadzu Autograph.
Using AG-100E type, the distance between chucks is 100mm.
, And broken at a tensile speed of 500 mm / min to measure the strength at that time. (c) All hazes Using a haze meter manufactured by Tokyo Denshoku Co., Ltd., ASTM D1003-61
It measured according to. (d) Internal haze After coating α-bromonaphthalene on the film surface and eliminating irregularities on the film surface, the haze was measured in the same manner as for all the haze. (e) Surface haze Calculated by subtracting the internal haze from the total haze.

Example 1 Using an equal weight mixture of phenol and ethane tetrachloride as a solvent, the intrinsic viscosity measured at a temperature of 20 ° C. is 0.78, the critical surface tension is 41 dyn / cm, the Tg is 70% by weight, and 90% by weight of PET. Viscosity of 2600 poise, critical surface tension of 46 dyn / cm, Tg of 1
50 ° C EMS amorphous polyamide resin "Grivory-XE
3038 "(copolymer of isophthalic acid, terephthalic acid, hexamethylenediamine and bis- (4-amino-3-methylcyclohexyl) methane) was fed to a single screw extruder at a temperature of 280 ° C. The mixture was melt-kneaded, extruded from a T-die having a width of 630 mm, brought into close contact with a rotating drum at 20 ° C. by an electrostatic application casting method, and rapidly cooled to obtain a substantially amorphous unstretched film. Next, the unstretched film was guided to a longitudinal stretching machine consisting of a series of heating rollers having different peripheral speeds, and 90
The film was heated to a temperature of 300 ° C., longitudinally stretched 3.0 times, and cooled to 30 ° C. to obtain a longitudinally stretched film. Subsequently, this longitudinally stretched film is guided to a tenter-type transverse stretching machine to be gripped by clips,
After preheating with hot air at 90 ° C, the film was stretched 3.3 times at 100 ° C. Thereafter, a constant width heat treatment was performed at 230 ° C. in the same tenter, and a relaxation treatment was performed at a temperature of 200 ° C. to obtain a biaxially stretched film having a thickness of 12 μm.

Examples 2 to 6 A biaxially stretched film was obtained in the same manner as in Example 1 except that the longitudinal stretching ratio, the transverse stretching temperature, the transverse stretching ratio, and the thickness of the stretched film were changed as shown in Table 1. .

Example 7 An unstretched film equivalent to that of Example 1 was guided to a longitudinal stretching machine.
The film was heated to 15 ° C., stretched 1.5 times, cooled to 90 ° C., further stretched 2.6 times, and cooled to 30 ° C. to obtain a longitudinally stretched film. Thereafter, the film was transversely stretched in the same manner as in Example 1 under the conditions shown in Table 1 to obtain a biaxially stretched film having a thickness of 12 μm.

Comparative Examples 1 to 7 Biaxial stretching was performed in the same manner as in Example 1 except that the longitudinal stretching ratio, the transverse stretching temperature, the transverse stretching ratio, and the thickness of the stretched film were changed as shown in Table 1.

Table 1 summarizes the characteristic values of the biaxially stretched films obtained in the above Examples and Comparative Examples.

[0032]

[Table 1]

In each of the examples, a biaxially stretched roughened film having high tensile strength at break and high surface haze could be produced with good operability. On the other hand, in the comparative example, there were problems such as low tensile strength in the longitudinal or transverse direction, low surface haze, poor transverse stretchability, and inability to obtain a biaxially stretched film.

[0034]

According to the present invention, it is possible to produce a successively biaxially stretched roughened film having excellent mechanical properties, moderate surface haze and low glossiness with good operability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 77:00

Claims (1)

[Claims] 1. A thermoplastic polyester resin having a glass transition temperature of 85 to 92% by weight which is higher than that of resin A, a critical surface tension different from that of resin A by 0.1 dyn / cm or more, and
Melt viscosity of 500 at 280 ° C and shear rate of 10 ² sec ^-1
Up to 50,000 poise amorphous polyamide resin B 15 to 8% by weight
Melt-formed into a non-stretched film,
After longitudinal stretching, in the method of manufacturing a biaxially stretched film by sequential biaxial stretching method of transverse stretching, longitudinal stretching so that the birefringence of the film after longitudinal stretching is 120 × 10 ^-3 ~ 150 × 10 ^-3 And then subjecting the film to transverse stretching at a temperature of 90 to 150 ° C. and a transverse stretching ratio of 3.0 to 4.0 times.