JP4628863B2 - Surface protection film - Google Patents

Description

  The present invention relates to a surface protective film excellent in scratch resistance, and having excellent adhesion to a complicated surface and solvent resistance.

In recent years, for example, a printed film (hereinafter, referred to as a visual marking film) is attached to a car body of an automobile or a train and used for advertising purposes is increasing.
Automobiles and train bodies are complex surfaces (curved surfaces, bent surfaces, surfaces with protrusions, etc.), and the characteristics required for visual marking films are no slack or wrinkles. It can follow the shape of and can be attached neatly. This is due to the property that the film expands and adheres following the shape of the surface, and even if the film is stuck with a certain expansion, the film will not shrink and peel off after that.

Visual marking film is often used outdoors, and its surface is damaged by various external factors. There are also problems such as deterioration of the visual marking film and fading of printing ink due to ultraviolet rays. In order to solve these problems, it has been common to use a surface protective film made of a fluororesin laminated on the surface side of the visual marking film.
However, in the case of a fluororesin film, there is a problem that a halogen component gives an environmental load when discarded.

In addition, as an example of other surface protection film, removability made of synthetic resin is used to prevent scratches, dust adhering and contamination during processing of liquid crystal panels and polarizing plates used in personal computers and word processors. A certain surface protective film is applied to a liquid crystal panel or a polarizing plate for protection.
Non-chargeable with an alkali metal ion source between the adhesive layer and the base material layer made of synthetic resin as a surface protection film that can release static electricity that occurs when the surface protection film with removability is released A film provided with an ethylene copolymer ionomer resin layer is disclosed. However, this surface protective film is intended to be applied to a flat portion such as a liquid crystal panel or a polarizing plate, and is not sufficient for protecting a complicated surface such as an automobile body.

JP-A-11-165368

  The present invention is excellent in scratch resistance and further required as a protective film for protecting a complex surface, that is, when a film is stuck on a complex surface, it does not loosen or wrinkle and follows the surface shape. As a result of diligent investigations to find a film that can be pasted and excellent in solvent resistance, it was obtained.

  In the present invention, 95-20% by weight of a hydrogenated resin of a copolymer of an aromatic vinyl hydrocarbon and a conjugated diene having a glass transition point (Tg) of less than 40 ° C. and a glass transition point (Tg) of 40 ° C. or more. Hydrogenated resin of a copolymer of a certain aromatic vinyl hydrocarbon and conjugated diene, binary copolymer resin with (meth) acrylic acid ester containing aromatic vinyl hydrocarbon as the main component, or aromatic hydrocarbon as the main component A layer (A) composed of 5 to 80% by weight of a terpolymer of a (meth) acrylic acid ester and a conjugated diene and a layer (B) made of an ionomer resin are laminated. Features.

  Since the present invention is configured as described above, the following effects can be obtained.

  A surface protective film that is less damaged by various external factors (for example, rubbing with a car wash brush, impact with rolled up pebbles, etc.) due to outdoor use has been obtained.

  In addition, even when pasted on curved surfaces, bent surfaces, surfaces with protrusions, etc., there is no slack or wrinkle, and a surface protective film that can be adhered cleanly following the shape of the surface has been obtained. .

  The solvent resistance was also good.

A layer (A) becomes a layer which expresses the sticking property (followability to a surface shape) to the surface of a complicated shape.
And a layer (B) becomes a layer which expresses damage resistance and solvent resistance, without impairing the function of a layer (A).
Therefore, the layer (B) is always configured to be outside.

First, the layer (A) will be described in detail.
The resin constituting the layer (A) is composed of 95 to 20% by weight of a hydrogenated resin of a copolymer of aromatic vinyl hydrocarbon and conjugated diene having a glass transition point (Tg) of less than 40 ° C. and a glass transition point (Tg). ) Is a hydrogenated resin of a copolymer of an aromatic vinyl hydrocarbon and a conjugated diene having a temperature of 40 ° C. or higher, a binary copolymer resin with a (meth) acrylic acid ester having an aromatic vinyl hydrocarbon as a main component, or an aromatic It consists of 5 to 80% by weight of at least one ternary copolymer resin of (meth) acrylic acid ester and conjugated diene mainly composed of a group hydrocarbon.

Here, the hydrogenated resin of a copolymer of aromatic vinyl hydrocarbon and conjugated diene having a glass transition point (Tg) of less than 40 ° C. is a copolymerization ratio of two monomers, a polymerization form (random or block) For example, there is a slight difference in the degree of softness (Shore A hardness) and mechanical properties. Examples of the copolymerization ratio include 50 to 80% by weight of aromatic vinyl hydrocarbon and 50 to 20% by weight of conjugated diene, but it is preferable to increase the amount of aromatic vinyl hydrocarbon. This is because when the conjugated diene increases, the surface protection film becomes more elastic and the surface protection film is easily peeled off by elastic return after the surface protection film is attached.

As the aromatic vinyl hydrocarbon, for example, styrene, α-styrene, p-methylstyrene, o-methylstyrene and derivatives thereof can be used. Styrene is particularly preferred.
The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3 butadiene, and the like. A derivative thereof or the like can be used. In particular, 1,3-butadiene is preferred.
Specific examples of the hydrogenated resin of a copolymer of aromatic vinyl hydrocarbon and conjugated diene include styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-butylene-ethylene (SEBC), and styrene. N-ethylene-styrene-butylene-styrene. Among these, SEBS and SEBC are preferable, and SEBS is particularly preferable.
Here, the glass transition point (Tg) of the hydrogenated resin of the copolymer of aromatic vinyl hydrocarbon and conjugated diene is −5 ° C. or higher and lower than 40 ° C., and the melt flow rate at 230 ° C. and 21.2 N load ( MFR) is 2 to 15 g / 10 min, preferably 2.7 to 5.4 g / 10 min.

  The layer (A) is an aromatic vinyl having a glass transition point (Tg) of 40 ° C. or higher with respect to 95 to 20% by weight of the hydrogenated resin of the copolymer of the aromatic vinyl hydrocarbon and the conjugated diene. Hydrogenated resin of copolymer of hydrocarbon and conjugated diene, binary copolymer resin with (meth) acrylic acid ester having aromatic vinyl hydrocarbon as main component or aromatic vinyl hydrocarbon as main component ( 5-80 weight% of at least 1 sort (s) of the ternary copolymer resin of meth) acrylic acid ester and conjugated diene is contained. If the blending amount is less than 5% by weight, substantially no improvement in the waist is seen, and if it exceeds 80% by weight, the waist becomes too stiff and the suitable followability to complicated surfaces is impaired, which is not preferable. .

Here, regarding the aromatic vinyl hydrocarbon and the conjugated diene in the hydrogenated resin of a copolymer of an aromatic vinyl hydrocarbon and a conjugated diene having a glass transition point (Tg) of 40 ° C. or higher, the glass transition point ( Tg) is the same as the hydrogenated resin of a copolymer of aromatic vinyl hydrocarbon and conjugated diene having a temperature of less than 40 ° C, but the glass transition point (Tg) is 40 ° C or more and less than 60 ° C, 230 ° C, The melt flow rate (MFR) at a load of 21.2 N is 2 to 15 g / 10 min, preferably 2.7 to 5.4 g / 10 min.

  Next, a binary copolymer resin with a (meth) acrylic acid ester having an aromatic vinyl hydrocarbon as a main component or a ternary of a (meth) acrylic acid ester with an aromatic vinyl hydrocarbon as a main component and a conjugated diene. In the copolymer resin, (meth) acrylic acid means acrylic acid and / or methacrylic acid. Examples of (meth) acrylic acid esters include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and derivatives thereof. Among them, methyl methacrylate or ethyl methacrylate Is preferred.

  As mentioned above, the conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3. Butadiene and its derivatives can be used. In particular, 1,3-butadiene is preferred.

Furthermore, various additives such as an ultraviolet absorber, an antioxidant, a light stabilizer, a colorant, an antistatic agent, a lubricant and the like can be appropriately added to the layer (A) depending on the product application.

Next, the layer (B) will be described.
Layer (B) consists of an ionomer resin. The ionomer resin is obtained by neutralizing a carboxyl group of a copolymer of ethylene and an unsaturated carboxylic acid with a metal ion.
Here, as unsaturated carboxylic acid, methacrylic acid and acrylic acid can be used, for example.
The content of unsaturated carboxylic acid in the copolymer of ethylene and unsaturated carboxylic acid is 2 to 30% by weight, preferably 3 to 25% by weight. When the content of the unsaturated carboxylic acid is less than 2% by weight, the scratch resistance is inferior, and when it is more than 30% by weight, the stiffness of the film becomes weak.
As metal ions, Na ⁺ , Li ⁺ , Mg ²⁺ and Zn ²⁺ are used, and in particular, Na ⁺ and Zn ²⁺ are generally used frequently.
In the present invention, it is desirable to use an ionomer resin having a melt flow rate at 190 ° C. and a load of 21.2 N of 0.5 to 15 g / 10 minutes, preferably 1.0 to 5.5 g / 10 minutes. If the melt flow rate is out of the above range, film formation becomes difficult, which is not preferable.

Furthermore, various additives such as ultraviolet absorbers, antioxidants, light stabilizers, colorants, antistatic agents, lubricants and the like may be added to the layer (B) to the extent that the physical properties are not impaired.

Here, examples of the layer structure of the surface protective film include those composed of two layers (B) / (A) and those composed of three layers (B) / (A) / (B).

The thickness of the surface protective film consisting of two layers (B) / (A) can be exemplified as follows.
The total thickness is 30 to 500 μm. This thickness range is preferable in consideration of handling properties during work, bulkiness of the adherend, and the like.
The thickness of the layer (A) is 25 to 495 μm, preferably 30 to 480 μm.
When the thickness of the layer (A) is less than 25 μm, it is not preferable because the followability to a complicated surface is impaired when the surface protective film is stuck. On the other hand, when the thickness is larger than 480 μm, the thickness of the layer (B) is decreased, and sufficient scratch resistance and solvent resistance cannot be obtained.

Next, the surface protective film composed of three layers (B) / (A) / (B) can be exemplified as follows.
A layer (B) is further provided on the layer (A) side of the surface protective film comprising the two layers (B) / (A). Further, the ionomer resin of the layer (B) provided may be the same ionomer resin as that of the layer (B) in the two-layer structure, but another ionomer resin may be used.

Moreover, what consists of (B) / (A) / (C) can also be illustrated as an example of the surface protection film of 3 layer structure.

Here, the layer (C) is a layer made of polyolefin. Examples of the polyolefin include, for example, an ethylene homopolymer, a copolymer of ethylene and a C _{3 to} C ₈ α-olefin, a copolymer of ethylene and an unsaturated carboxylic acid, and a copolymer of ethylene and an unsaturated carboxylic acid ester. Examples include polymers, copolymers of ethylene and vinyl acetate, propylene homopolymers, and copolymers of propylene and C _{2 to} C ₈ (excluding C ₃ ) α-olefins, ethylene homopolymers or ethylene And copolymers of C _{3 to} C ₈ α-olefins are preferred.

Further, the main reason for providing the provided layers (B) and (C) is to prevent curling.

Next, the manufacturing method of the surface protective film of the said 2 layer structure and 3 layer structure is demonstrated.
Examples of the production method include known methods capable of producing a multilayer film, but the most preferable T-die coextrusion method will be described.
When manufacturing a two-layer surface protective film, the resin constituting the layer (A) and the resin constituting the layer (B) are charged into two extruders, respectively, and the three-layer surface protection is provided. In the case of producing a film, the resin constituting the layer (A) in one extruder, the resin constituting the layer (B) in one extruder, and the layer (B) in the other extruder The resin constituting B) or the resin constituting the layer (C) is added. The resin charged in an extruder heated to a predetermined temperature is kneaded, compressed, and measured by a screw while melting, and is laminated from each extruder through a multi-die for two layers or three layers at the same time. Extruded. This is once cooled and solidified through a cooling roll and taken up.

When the surface protective film is actually used, one layer (layer (A) side in the case of two layers, layer (B) or layer (C) on the adherend side in the case of three layers) is used. )), An adhesive layer for sticking and fixing is laminated together with a release paper.

Hereinafter, examples will be described in detail together with comparative examples.
The following characteristics were obtained by the following method.

● A scratch-resistant sample film is cut into a length of 150 mm and a width of 100 mm to obtain a test piece. Using a pencil scratch tester manufactured by Imoto Seisakusho Co., Ltd., a pencil with a pencil hardness of 9H was used as a contact, and a scratch test was performed with a load of 100 g. The case where no scratches that can be visually confirmed were not recognized was indicated as “◯”, and the case where scratches were observed was indicated as “X”.
● A solvent-resistant sample film is cut into a size of 100 mm long × 25 mm wide to obtain a test piece. Fill the beaker with gasoline as a solvent. The test piece is immersed in gasoline at room temperature for 30 minutes, then taken out and dried. The case where the appearance of the film did not change (whitening, swelling, cracking, etc.) was marked with ◯, and the changed appearance was marked with ×.
● Adhesion
When a surface protective film is stuck along a complicated surface, the film expands and adheres closely to the shape of the surface.
First, an acrylic resin adhesive is coated on one surface of a sample film to provide an adhesive layer. This was cut into 50 mm length × 50 mm width to obtain a test piece. And while pressing the adhesive layer surface of the sample heated to 80 ° C against the metal surface with hemispherical protrusions (diameter 7mm, height 2mm) (rivets), especially the protrusions should be pressed firmly with no gaps To wear. If it is pasted in the same shape as the projection shape, it will be marked as ◯, and if it is a shape different from the projection shape (for example, it is lifted up and swollen as a whole).
● Non-peeling property A property that prevents the film from shrinking and peeling even after being applied with a certain extension.
The same sample with the adhesive layer used for the measurement of the adhesion is stretched by 20% in the vertical and horizontal directions. The extension is maintained for 5 minutes and then released, and the remaining extension ratios in the longitudinal and transverse directions are measured again. If the residual elongation ratio exceeds 10%, it is evaluated as “B”.

Example 1
Layer (A):
Styrene-butadiene random copolymer hydrogenated resin (Asahi Kasei Chemicals Co., Ltd., product SS9000 Tg = 20 ° C) 60% by weight and styrene-butadiene random copolymer hydrogenated resin (Asahi Kasei Chemicals Co., Ltd., product L607 Tg = 50 ° C) Blend with 40% by weight.
Layer (B):
100% by weight of ionomer resin (produced by Mitsui DuPont Polychemical Co., Ltd., varieties High Milan 1554 MFR = 1.3).

The resin constituting each layer is supplied to two screw extruders (barrel temperatures of 180 to 225 ° C.) and co-extruded from a two-layer T die at 220 ° C., and this is passed through a cooling roll at 70 ° C. After cooling and solidifying, a two-layer surface protective film was continuously formed and wound.

The total thickness of the obtained film was 60 μm, the thickness of layer (A) was 55 μm, and the thickness of layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Example 2)
Layer (A):
Styrene-butadiene random copolymer hydrogenated resin (Asahi Kasei Chemicals Co., Ltd., grade SS9000 Tg = 20 ° C) 60% by weight and styrene-methyl methacrylate copolymer resin (Denki Kagaku Kogyo Co., Ltd., TX polymer, grade TX-500R-301) (Vicat softening point 88 ° C.) blended with 40% by weight.
Layer (B):
100% by weight of ionomer resin (same as in Example 1).

The resin constituting each layer is supplied to two screw extruders (barrel temperatures of 180 to 225 ° C.) and co-extruded from a two-layer T die at 220 ° C., and this is passed through a cooling roll at 70 ° C. After cooling and solidifying, a two-layer surface protective film was continuously formed and wound.

The total thickness of the obtained film was 60 μm, the thickness of layer (A) was 55 μm, and the thickness of layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Example 3)
Layer (A):
Styrene-butadiene random copolymer hydrogenated resin (Asahi Kasei Chemicals Co., Ltd., grade SS9000 Tg = 20 ° C) 50% by weight and styrene-methyl methacrylate-butadiene copolymer resin (Denki Kagaku Kogyo Co., Ltd., TH polymer grade TH23 Vicat softening) Blend with 50 wt.
Layer (B):
100% by weight of ionomer resin (same as in Example 1).

The resin constituting each layer is supplied to two screw extruders (barrel temperatures of 180 to 225 ° C.) and co-extruded from a two-layer T die at 220 ° C., and this is passed through a cooling roll at 70 ° C. After cooling and solidifying, a two-layer surface protective film was continuously formed and wound.

The total thickness of the obtained film was 60 μm, the thickness of layer (A) was 55 μm, and the thickness of layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

Example 4
Layer (A):
To 100 parts by weight of the same dry blend as in Example 3, 25 parts by weight of a colorant masterbatch (variety PS-M SSC98H822 (D) black manufactured by Dainichi Seika Co., Ltd.) was added, and biaxial melt extrusion kneading was performed. While pelletized.
Layer (B):
100% by weight of ionomer resin (same as in Example 1).

The resin constituting each layer is supplied to two screw extruders (barrel temperatures of 180 to 225 ° C.) and co-extruded from a two-layer T die at 220 ° C., and this is passed through a cooling roll at 70 ° C. After cooling and solidifying, a two-layer surface protective film was continuously formed and wound.

The obtained film was black and opaque, and the total thickness of the film was 60 μm, the thickness of the layer (A) was 55 μm, and the thickness of the layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Example 5)
Using the same resin as in Example 1, the resin constituting the layer (A) is one extruder (barrel temperature 180 to 225 ° C.), the resin constituting the layer (B) is two extruders (each Barrel temperature 180 to 225 ° C.), and the layer (A) is co-extruded from a three-layer T die at 220 ° C. so that the layer (B) is on the outer surface. It was cooled and solidified through a cooling roll at 0 ° C., and a three-layer surface protective film was continuously formed and wound.

The total thickness of the obtained film was 60 μm, the thickness of the layer (A) was 50 μm, and the thickness of the layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Example 6)
Except for using the same resin as in Example 2, co-extrusion was carried out in the same manner as in Example 5 to obtain a surface protective film consisting of 3 layers.

The total thickness of the obtained film was 60 μm, the thickness of the layer (A) was 50 μm, and the thickness of the layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Example 7)
Except for using the same resin as in Example 3, co-extrusion was carried out in the same manner as in Example 5 to obtain a three-layer surface protective film.

The total thickness of the obtained film was 60 μm, the thickness of the layer (A) was 50 μm, and the thickness of the layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Example 8)
Using the constituent resin of the same layer (A) and layer (B) as in Example 1, and further using a low-density polyethylene resin (density 0.915, MFR 2.0) as the layer (C), the layer (A) The resin constituting the layer (B) is placed in one extruder (barrel temperature 180 to 225 ° C), the resin constituting the layer (B) is placed in one extruder (each barrel temperature 180 to 225 ° C), and the layer (C) The constituent resin is supplied to each extruder (each barrel temperature 180 to 225 ° C.), and the layer (B) / layer (A) / layer (C) is ordered in order of layer 3B T-die at 220 ° C. Co-extrusion was performed, and this was cooled and solidified through a cooling roll at 70 ° C., and a surface protective film consisting of three layers was continuously formed and wound.

The total thickness of the obtained film was 60 μm, the thickness of layer (A) was 50 μm, the thickness of layer (B) was 5 μm, and the thickness of layer (C) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

Example 9
Except for using the same resin as in Example 4, co-extrusion was carried out in the same manner as in Example 5 to obtain a surface protective film consisting of three layers.

  The obtained film was black opaque, the total thickness of the film was 60 μm, the thickness of the layer (A) was 50 μm, and the thickness of each of the layers (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Comparative Example 1)
A film comprising three layers in the same manner as in Example 1 except that 100% by weight of a styrene-butadiene random copolymer hydrogenated resin (product type SS9000 Tg = 20 ° C., manufactured by Asahi Kasei Chemicals Corporation) is used as the layer (A). Got.

The total thickness of the obtained film was 60 μm, the thickness of layer (A) was 55 μm, and the thickness of layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

(Comparative Example 2)
In the same manner as in Example 1 except that 100% by weight of styrene-methyl methacrylate-butadiene copolymer resin (TP polymer, type TH23, Vicat softening point 84 ° C., manufactured by Denki Kagaku Kogyo Co., Ltd.) is used as the layer (A). A film consisting of layers was obtained.

The total thickness of the obtained film was 60 μm, the thickness of layer (A) was 55 μm, and the thickness of layer (B) was 5 μm. The film was appropriately cut to prepare a sample for evaluation, and scratch resistance, solvent resistance, adhesion, and non-peelability were measured. The results are summarized in Table 1.

Claims (1)

Aromatic vinyl having a glass transition point (Tg) of less than 40 ° C. and a hydrogenated resin of a copolymer of aromatic vinyl hydrocarbon and conjugated diene of 95 to 20% by weight and a glass transition point (Tg) of 40 ° C. or higher. Hydrogenated resin of copolymer of hydrocarbon and conjugated diene, binary copolymer resin of (meth) acrylic acid ester having aromatic vinyl hydrocarbon as main component or aromatic hydrocarbon as main component (meta ) A surface comprising a layer (A) composed of 5 to 80% by weight of at least one ternary copolymer resin of acrylate ester and conjugated diene and a layer (B) made of an ionomer resin. Protective film.