JPH0747640A - Laminated film - Google Patents

Abstract

PURPOSE:To provide a thermoplastic film excellent in transparency, antistatic properties under low humidity conditions and water resistance. CONSTITUTION:By laminating a dielectric layer wherein the peak due to a thermal stimulation current is observed at 401 or lower to at least the single surface of a thermoplastic film, antistatic properties extremely good under low humidity conditions are imparted to the non-laminated surface of the film even after lamination.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is transparent and has excellent antistatic properties under low humidity, and also exhibits antistatic properties on the surface on which an antistatic layer is not laminated and the laminated surface. The present invention relates to an antistatic thermoplastic laminated film having excellent film strength.

[0002]

2. Description of the Related Art Conventionally, films made of thermoplastic resins such as polyolefins, polyesters, polyamides, polystyrenes and polyvinyl chlorides, particularly oriented polypropylene, polyesters and polyamides films, have excellent mechanical properties and heat resistance. It has properties such as transparency and transparency, and is widely used as packaging materials and industrial materials.

However, these films have the drawback that, since the resin itself is an insulator, they are extremely prone to being charged with electricity, and are apt to cause problems due to static electricity, especially in low humidity.

Conventionally, various measures have been taken to impart antistatic properties to these films. For example, a film having a surface having an antistatic property, an ionic compound, a conductive substance such as a metal powder or a metal oxide, or the like is kneaded into the film composition or blended in a coating agent. The method of applying it to was used.
However, the method of using a surfactant and an ionic compound as an antistatic agent has a low antistatic property under low humidity,
There is a problem that the surface where the antistatic layer is not laminated or the surface where the antistatic layer is further laminated has no antistatic property, and the use is limited. Further, when the amounts of the surfactant and the ionic compound are increased to sufficiently satisfy the antistatic property, there is a contradictory problem that water resistance, blocking resistance and coating film strength become insufficient. On the other hand, the method using a conductive substance is
There is no problem that the antistatic property deteriorates even in low humidity or on the surface on which the antistatic layer is not laminated or further laminated, but it is necessary to add a large amount of a conductive substance in order to impart the antistatic property. However, there is a problem that transparency is lowered. Further, there is a problem that such a conductive material is expensive.

Therefore, it is more transparent than before and is excellent in antistatic property under low humidity, and the antistatic property appears on the surface on which the antistatic layer is not laminated and the laminated surface, and further the water resistance and the coating strength are improved. There has been a demand for the development of an excellent thermoplastic film.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art. The object of the present invention is to provide a transparent and excellent antistatic property under low humidity and to laminate an antistatic layer. It is an object of the present invention to provide a thermoplastic film exhibiting antistatic properties on the uncoated surface and the laminated surface, and also having excellent water resistance and coating film strength.

[0007]

The laminated film of the present invention is characterized in that the dielectric film is laminated on at least one surface of a thermoplastic film, on which a dielectric substance whose peak due to a thermal stimulation current is observed at 40 ° C. or lower is laminated. To do.

The thermoplastic film used in the present invention is not particularly limited as long as it is a thermoplastic resin capable of forming a transparent film, but is a polyolefin resin such as polyethylene, polypropylene or syndiotactic polystyrene, polyethylene terephthalate, polyethylene. Polyester resin typified by isophthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate and their copolymers, polyether resin typified by polyoxymethylene, nylon-6, nylon-66
Polyamide-based resin typified by polymethaxylene adipazide, polystyrene, poly (meth) acrylic acid ester, polyacrylonitrile, polyvinyl acetate, and vinyl-based resin typified by their copolymers, polycarbonate-based resin Cellulosic resins typified by cellophane, acetate, etc., as well as polyimide, polyetherimide, polyphenylene sulfide,
Polyethersulfone, polysulfone, polyetherketone, polyetherketoneketone, fluorine-containing polymers, many other resin simple substances, copolymers, mixtures, and laminates, which are unstretched or uniaxial or orthogonal. Examples include an oriented film stretched in the axial direction.

As the substrate film, biaxially stretched films of polypropylene, polyester, polyamide and the like are suitable from the viewpoints of heat resistant dimensional change and mechanical strength, as well as moldability and economy.

The thickness of the film is not particularly limited,
It is usually 1 to 250 μm, and 3 to 1 as an industrial material.
50 μm is particularly preferable.

The base film may be a simple substance or a composite multilayer film, and the composite method and the number of layers in the multilayer film are arbitrary.

As the dielectric of the laminated film of the present invention,
A peak due to thermal stimulation current is observed at 40 ° C or less
It is not particularly limited as long as it is. Preferably with good transparency
It is of organic type. More preferably, acrylic poly
It is a mer type antistatic agent. Specifically, it has a cationic group
Acrylic polymers, especially those with quaternary nitrogen
preferable. In addition, water-soluble medium (water / IPA = 1/1 weight
%) Solution viscosity at a solid concentration of 20% when dissolved in
Is preferably 100 to 300 cps. Solution viscosity
If the degree is 100 cps or less, the water resistance is poor and 300 c
If it is more than ps, the antistatic property becomes poor. Invitation of the present invention
It is preferable that the electric body has a peak of 40 ° C or less due to the thermal stimulation current
It is observed below 25 ℃, and further below 0 ℃.
Those are preferable. Also, thermal stimulation of the dielectric layer at 25 ° C or less
The charge density calculated from the peak area due to the current is 1.0 x 1
0^-8C / m²Above, moreover 1.0 × 10¹⁷C / m²Above
Preferably there is. Again at 25 ° C and 15% RH
Surface resistance value is 10¹³Ω / □ or less, further 10 ¹²
It is preferably C / □ or less. Thermally stimulated current
If the peak is observed above 40 ° C, the charge density is 1.0
× 10^-8C / m²In the following cases, the surface resistance value is 10
¹³If it is more than Ω / □, the antistatic property is poor and
In addition, the anti-lamination surface and the antistatic property after lamination are poor.

In the present invention, the above compounds may be used alone or in combination of two or more. Further, it may be used in combination with other conventionally known antistatic agents. Further, it may be laminated by mixing with a binder resin composed of an organic polymer which is soluble or dispersible in a solvent. If necessary, additives such as a cross-linking agent, a colorant, an anti-blocking agent, a cross-linking agent, an antioxidant, a UV inhibitor and a lubricant composed of inorganic or organic particles may be contained. Here, it is preferable to further add a cross-linking agent to the acrylic polymer, and specifically, it is preferable to add an epoxy compound and an isocyanate as the cross-linking agent. First, the weight ratio of the epoxy compound to the acrylic polymer is 0.02 to
It is preferable to add it in a ratio of 0.2. If the above ratio is 0.02 or less, the water resistance and blocking resistance of the film will be poor, and if it is 0.2 or more, the antistatic property will be poor. Next, isocyanate is preferably added to the acrylic polymer in a ratio of 0.1 to 0.4.
If the above ratio is 0.1 or less, the coating strength of the film will be poor, and if it is 0.4 or more, the antistatic property will be poor. Furthermore, the glass transition temperature (Tg) of the dielectric layer is 40 to 7
It is preferably in the range of 0 ° C. If the temperature is 40 ° C. or lower, the blocking resistance is poor, and if it is 70 ° C. or higher, the antistatic property is poor. Furthermore, the pencil hardness is HB
If it is less than the above range, the coating strength is poor. The means for mixing when mixing and laminating the multi-components is not limited, and known methods such as a high-speed stirring method, a high-pressure dispersion method, and an ultrasonic dispersion method can be arbitrarily used. A method combining these methods is also suitable. The dielectric of the present invention is not particularly limited as long as a peak due to a thermal stimulation current is observed at 40 ° C. or less, but it is preferable to satisfy the above conditions in order to satisfy various properties as a film.

The method for laminating the compound or the composition containing the compound on the surface of the base film is not particularly limited, but a coating method of applying a solution or dispersion on the surface of the base film is particularly preferable. That is, it is preferable to apply the composition on the surface of the base material film, and then carry out drying and heat treatment. As a coating method, a usual method such as a roll coating method such as gravure or reverse, a doctor knife method, an air knife, or a nozzle coating method can be used. Alternatively, a spraying method may be used.

The coating may be carried out on the surface of the film after the production. For example, in the case of a biaxially stretched film, it is preferable that the coating is conducted after the film production process, that is, the cast raw fabric or the uniaxial stretching, and then the stretching treatment is carried out. . In particular, it is preferable to carry out the stretching treatment in a state where the water content of the coating film after coating is 2% or less after the raw material for casting or uniaxial stretching. The thickness of the layer containing the compound laminated by such a method is not particularly limited, but is 0.01 to 5.0 μm.
m is preferred. If it is less than 0.01 μm, sufficient antistatic properties cannot be obtained, and if it is 5.0 μm or more, blocking resistance is poor.

The compound may be laminated on one side or on both sides, but since the characteristic of the method of the present invention is that the opposite side of the coated surface is not charged, the method of coating on one side is recommended. To be done. The laminated film produced by the above method is particularly useful as a base material for magnetic recording media such as video tapes, audio tapes, computer tapes and floppy disks. Also, general industrial films, such as membranes, telephone cards, labels, microfilms, diazo films,
It is also useful as a base material for OHP films and the like.

Examples Next, examples and comparative examples of the present invention will be shown. Used in the present invention
The evaluation method is shown below. 1) Solution viscosity An aqueous solution with a solid content of 20% without adding a crosslinking agent
It measured at 25 degreeC using the Brookfield viscometer. 2) Thermally stimulated current The base film is coated with the coating film forming composition to form a laminated film.
The film is made and the thermal stimulating current made by US SOLOMAT
(TSC) measuring device, upper electrode (area 38mm ²)When
Insert a laminated film between the lower electrodes, and in a He atmosphere
After applying an electric field of 300 V / mm for 2 minutes at a temperature of 25 ° C
After cooling to −150 ° C. and removing the electric field, the temperature rising rate is 7
The measurement was carried out in the range of -150 to 100 ° C at a temperature of ° C / min. 3) Surface resistance Takeda Riken specific resistance measuring device applied voltage 500V, 2
It was measured under the conditions of 3 ° C. and 40% RH. 4) Water resistance The laminated film was immersed in water and left at 26 ° C for 16 hours.
It is expressed as the ratio of the surface resistance value of the dielectric layer after dipping and before dipping.
did. 5) Tg (glass transition temperature) The film-forming composition was vacuum dried, and then DS manufactured by Shimadzu Corporation
Using C (Differential Scanning Calorimeter) in nitrogen stream at 20 ℃ / mi
n. The measurement was performed at the temperature rising rate of. 6) Pencil hardness The pencil hardness of the dielectric layer of the laminated film is based on JIS standard.
I measured it. 7) Charge decay time Using a static decay meter manufactured by US ETS,
Insert the sample between the electrodes in an atmosphere of 23 ° C and 15% RH.
Applying a voltage of 5.0 kV, the applied voltage becomes 5.0 kV
Ground the electrode at
Decay time t until reaching 0.05kV₉₉Was measured. 8) Coating strength Take gauze on the tester industry academic vibration type friction fastness tester
It was reciprocated on the surface of the dielectric layer 10 times with a load of 200 g.
Occasionally, if the dielectric layer does not peel off, ○ means that the dielectric layer does not peel off.
did. 9) Blocking resistance Laminated films are stacked on top of each other and tested by a tester industry tabletop type.
Using a press machine, 5.6kg / cm²The load of
In addition, after standing at 50 ° C for 24 hours, the laminated films are
Complete when blocking does not occur when separated.
When all blocking occurs, 1 is set, and 4 or more blocks
It was supposed to have a cocking property.

Example 1 Copolymerization of methyl methacrylate / ethyl acrylate / 2-hydroxyethyl methacrylate / dimethylaminoethyl methacrylate quaternary compound at a weight composition ratio of 44/20/6/30 was carried out by a conventional method. An aqueous polymer solution was obtained. To this aqueous copolymer solution, 5% by weight of glycerol polyglycidyl ether as an epoxy compound was added to the solid content of the copolymer of 75%, and 2-methylimidazole as a crosslinking curing agent was added to the glycerol polyglycidyl ether at 3% by weight. 0.0 wt% was added and mixed. Next, as a blocked isocyanate compound, Elastron MF9 (manufactured by Dai-ichi Kogyo Co., Ltd.) was used as the solid content of the copolymer 7
20% by weight to 5, and Cat 64 (manufactured by Daiichi Kogyo Co., Ltd.) as a cross-linking curing agent was added to and mixed with 5.0% by weight of the blocked isocyanate compound to form a coating film having a solid content of 7% An aqueous solution of the composition for use was obtained. 280-30 polyethylene terephthalate with an intrinsic viscosity of 0.65
After melt extruding at 0 ° C. and cooling with a cooling roll at 15 ° C. to obtain an unstretched film, the unstretched film was stretched 3.5 times in the machine direction between a pair of rolls at 85 ° C. having different peripheral speeds. An aqueous solution of the coating film-forming composition is applied by a kiss coating method so that the thickness after drying is 0.15 μm, and then the water content of the coating film is adjusted to 2% or less with a tenter at 70 ° C. It was pre-dried and further stretched 3.5 times in the transverse direction at 98 ° C, and then heat set at 200 to 220 ° C to obtain a biaxially stretched coated polyester film having a thickness of 20 µm. The characteristics of the obtained film are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that 7% by weight of an epoxy compound and 18% of a blocked isocyanate compound were added to 75% of the solid content of the copolymer in the aqueous copolymer solution. went.

Example 3 The procedure of Example 1 was repeated except that the viscosity of the aqueous copolymer solution was changed as shown in Table 1.

Example 4 Example 4 was repeated except that the substrate film of Example 1 was changed as shown in Table 1 and the stretching and heat setting conditions were changed appropriately.

Example 5 The same procedure was carried out except that the film shown in Table 1 was laminated on the laminated film obtained in Example 1.

Example 6 Example 6 was repeated except that the amount of the epoxy compound added in Example 1 was changed to 1% by weight.

Example 7 The amount of the blocked isocyanate compound added in Example 1 was 5
It carried out similarly except having changed into weight%.

Example 8 The procedure of Example 1 was repeated except that the viscosity of the aqueous copolymer solution was changed as shown in Table 1.

Example 9 The composition for coating film formation of Example 1 was treated with Chemistat 6300H.
(Sanyo Chemical Co., Ltd.) except that it was performed in the same manner.

Comparative Example 1 20% by weight of an epoxy compound and 50% of a blocked isocyanate compound were added to a solution having a solid content of 75%.
It carried out similarly except having changed so that it might be added.

Comparative Example 2 The procedure of Example 1 was repeated except that the viscosity of the aqueous copolymer solution was changed as shown in Table 1.

Comparative Example 3 The same procedure was carried out except that the coating film forming composition of Example 1 was changed to Bayronal (water dispersible composition of polyester resin RV280 manufactured by Toyobo Co., Ltd.). As shown in Tables 1 and 2, in each of the antistatic films of Examples, the peak due to the thermal stimulation current of the coat layer was observed at 40 ° C. or less, and the charge decay property appeared even at low humidity, and even on the anti-coated surface. Laminated products also show good charge decay characteristics. In addition, Examples 1, 2, 3, 4, and 7 have good water resistance,
Nos. 4, 6 have good coating strengths, and Examples 1, 2, 3, 4,
6 and 7 also show good blocking resistance. on the other hand,
In Comparative Examples 1, 2, and 3, no peak due to the thermal stimulation current of the coat layer was observed at 40 ° C. or lower, and the antistatic property did not appear.

[0030]

As described above, the antistatic polyester film of the present invention has excellent antistatic properties at low humidity, excellent antistatic properties on the anti-lamination surface and after lamination, and has excellent water resistance, coating strength and resistance. Since it is also excellent in blocking properties, it can be widely and suitably used as a base material for magnetic recording media, general industrial films, and various packaging films.

[0031]

[Table 1]

[0032]

[Table 2]

[Brief description of drawings]

FIG. 1 shows a spectrum of thermally stimulated current (TSC), where the horizontal axis represents temperature and the vertical axis represents current. The area represents the amount of electric charge.

[Explanation of symbols]: T due to polarization of the thermoplastic film (base film)
SC peak: TSC peak due to polarization of laminated body (dielectric)

Claims (6)

[Claims] 1. At least one surface of the thermoplastic film,
A film in which a dielectric material having a peak due to a thermal stimulation current is observed at 40 ° C or lower. 2. The charge density as determined from the peak area of the dielectric layer according to claim 1 due to a thermally stimulated current of 25 ° C. or less is 1.0 × 10 ⁻⁸ C / m ² or more. The laminated film described. 3. 25 of said dielectric layer according to claim 1 or 2.
The laminated film according to claim 1 or 2, which has a surface resistance value of 10 ¹³ Ω / □ or less at 15 ° C and 15% RH. 4. The laminated film according to claim 1 or 2.
The ratio of the surface resistance values at 25 ° C. and 15% RH of the dielectric layer after immersion in 5 ° C. water for 24 hours and before immersion is 1
It is 00 or less, The laminated film in any one of Claims 1-3. 5. The glass transition temperature (Tg) of the dielectric layer of the laminated film according to any one of claims 1 to 4 is in the range of 40 to 70 ° C. The laminated film described. 6. The laminated film according to any one of claims 1 to 5, wherein the dielectric layer of the laminated film according to any one of claims 1 to 5 has a pencil hardness of HB or more.