JPH08218043A - Adhesive film for surface protection - Google Patents

Abstract

PURPOSE: To obtain an adhesive film hard to develop its breakage, bite and/or lifting in processing objects and in its application onto members with three- dimensional curved surface, or its tearing when peeled off, good in peel workability. CONSTITUTION: This adhesive film for surface protection is such as to have an adhesive layer on one surface of a substrate; and the substrate has the following physical properties: tensile modulus: >=4kgf/mm<2> but <30Kgf/mm<2> ; the residual stress 10min after 10% extension: <=4kgf/mm<2> ; and the Elmendorf tear strength: >=200gf/100μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an adhesive film (adhesive film for surface protection) used for protecting the surface of a metal plate such as a stainless plate, an aluminum plate, a steel plate, a plastic plate or a coated plate of these. For details, when used for applications involving stretching of an adhesive film, such as surface protection of a member during processing or surface protection of a member having a three-dimensional curved surface, the film tears, galling, floating, and The present invention relates to an adhesive film for surface protection, which is less likely to cause contamination of a protected material and tear during peeling.

[0002]

2. Description of the Related Art When transporting or storing a member such as a metal plate such as a stainless steel plate, an aluminum plate, a steel plate, a plastic plate or a coated plate thereof, or cutting, punching, punching, bending or roll forming the member. When processing such as drawing, an adhesive film for surface protection is attached to the surface to prevent the surface from being soiled or scratched.

[0003]

As the above-mentioned adhesive film for surface protection, those using soft vinyl chloride as a base material, those using plastic materials such as polyethylene, polypropylene and polyester have been used conventionally. However, when using soft vinyl chloride, when it is discarded after use, chlorine gas is generated when it is incinerated, so it cannot be incinerated as it is. Therefore, for example, it is necessary to install a device for chlorine gas removal in an incinerator. There was a problem.

On the other hand, when a plastic material such as polyethylene, polypropylene or polyester is used, the film is torn, gnawed, floated or protected when the object to be protected is processed or attached to a member having a three-dimensional curved surface. It was not satisfactory in terms of pollution. Explaining this point in more detail, when attaching the surface protective adhesive film to a member such as a stainless plate, an aluminum plate, a metal plate such as a steel plate, a plastic plate or a coated plate thereof,
The film is usually stretched by about 2 to 3% and attached, and residual stress is generated at this time. After that, when the object to be protected is subjected to processing such as cutting, punching, punching, bending, roll forming and drawing, the film is further stretched and the residual stress is further increased. In addition, when a film is attached to a member having a three-dimensional curved surface, the film is greatly stretched and the residual stress caused by it is also large. Therefore, if the object to be protected to which the film is attached is left as it is, the film is peeled off from the free end portion or the like. In order to prevent this peeling, it is conceivable to increase the adhesive force of the film, but according to this, when peeling the film from the protected object after use, the force required for the work also increases, so workability is improved. Deteriorate. Therefore, it is conceivable to reduce the residual stress of the film. For this purpose, it is conceivable to reduce the initial strength of the base material when it is stretched. Tearing and galling are likely to occur, resulting in poor workability. Here, since the film is usually attached to the adherend along the M direction, workability at the time of attaching the film deteriorates particularly when the strength in the M direction becomes small.

Further, in the case of the film using the above plastic material, particularly in the case of using a substrate containing polypropylene, there is a problem that the workability is poor because the film is likely to tear when peeled off.

The object of the present invention is to solve the above-mentioned problems and to prevent film tearing, galling, floating during processing of an object to be protected and attachment to a member having a three-dimensional curved surface, and contamination or peeling of the object to be protected. An object of the present invention is to provide an adhesive film for surface protection which is less likely to tear.

[0007]

The inventors of the present invention have found that the tensile modulus of the base material and the residual stress after 10 minutes of elongation by 10%, and the member having a three-dimensional curved surface during processing of the object to be protected. After repeated research focusing mainly on the correlation with the degree of occurrence of film tearing, galling, floating, etc. during application, the tensile elastic modulus was 4 Kgf / mm ² or more and less than 30 Kgf / mm ² and 10 % Residual has a residual stress of 0.4 Kgf / after 10 minutes
If the tearability of the Elemendorff is not more than mm ² and the thickness of the base material is 100 μm and is not less than 200 gf, the film may be torn or gnaw during the processing of the object to be protected and the attachment to a member having a three-dimensional curved surface, It has been found that an adhesive film for surface protection is obtained in which floating and contamination of the protected object or tearing at the time of peeling does not easily occur.

The present invention has been made based on the above findings and has the following gist. That is, the adhesive film for surface protection of the present invention comprises a pressure-sensitive adhesive layer on one surface of a substrate, and the substrate has a tensile elastic modulus of 4 Kgf / mm ² or more and less than 30 Kgf / mm ² . The residual stress after 10 minutes of elongation of 10% is 0.4 Kgf / mm ² or less, and the thickness is 1
The tearability of the Elemendorff at 00 μm is 200 gf or more. In the present invention, the tensile elastic modulus of the base material is measured according to JIS K 7127 (measurement conditions are: base material thickness 100 μm, width 10 mm, distance between grippers 100 mm, pulling speed 1 mm / min, 23 ° C.). Value) (in both the M and T directions), the residual stress is
A sample with a thickness of 100 μm, a width of 20 mm and a length of 50 mm is 23 ° C.
After 10% elongation at a tensile speed of 300 mm / min, the elongation is stopped, and the stress 10 minutes later is taken as the value (both M and T directions). Further, the tearability of the Elemendorff is a value (both in the M direction and the T direction) obtained by measurement according to JIS P 8116 (measurement conditions are a substrate thickness of 100 μm and 23 ° C.).

[0009]

According to the present invention, the tensile elastic modulus of the base material and the residual stress after 10 minutes of elongation by 10% are set within a specific range so that the material to be protected and a member having a three-dimensional curved surface can be obtained. Prevents the film from tearing when it is peeled off by reducing the occurrence of tearing, galling, floating, etc. of the film during sticking, and by setting the tearability of the Elemendorf at a thickness of 100 μm within a specific range It is something that is done.

In the present invention, the base material is first stretched.
Elastic modulus is 4 Kgf / mm²Above, 30Kgf / mm²Less than preferred
The elastic modulus in the M direction is 10 Kgf / mm²Above, 30Kgf / mm²
And the residual stress after 10 minutes of elongation of 10% is less than 0.
4 kgf / mm²Below, preferably 0.35Kgf / mm²Also below
Of is used. Tensile elastic modulus of the above substrate is 4 Kgf / mm²that's all
When the film is peeled, tearing is less likely to occur, especially
Elastic modulus in D direction is 10 Kgf / mm²Being above, the film
Good workability when pasting. Meanwhile, 30 Kgf / mm ²Less than
If there is, it is attached at the time of processing or to a member with a three-dimensional curved surface
The film has good followability and the film does not float.
Unlikely to occur. In addition, 10 minutes after the above base material is elongated by 10%,
Residual stress of 0.4Kgf / mm²The film is
It is less likely to peel off from the end after being attached to the object to be protected.
Yes.

Further, in the present invention, the tearability of the Elemendorff when the thickness of the substrate is 100 μm is 200 gf or more, preferably 300 gf or more. When the tearability of the above-mentioned Elemendorff is less than 200 gf, the film tends to tear when peeling off the film, resulting in poor workability.

As the material of the above-mentioned base material, the tensile elastic modulus,
Residual stress after 10% elongation and 10 minutes and thickness 100
Any element can be used as long as the tearability of Elemendorff at μm is within the above range, but in order to prevent harmful gas from being generated by incineration at the time of disposal, a resin other than vinyl chloride resin is used. It is desirable to use.

Examples of the material of the base material include a hard segment and a soft segment, the hard segment being polypropylene, the soft segment being (1) a copolymer of propylene and ethylene, (2) propylene and a formula CH. ₂ = CHR (wherein R represents an aliphatic or aromatic group having 2 to 8 carbon atoms), one kind selected from a copolymer with an α-olefin and (3) a copolymer of propylene and a diene compound Alternatively, a resin having two or more kinds of resins is preferably used.

Examples of the α-olefin include butene-1,
Pentene-1, 4-methylpentene-1, hexene-1, octene-1, styrene and the like are exemplified as preferable ones.

Preferred examples of the diene compound include butadiene, 1,4-hexadiene, 1,5-hexadiene, ethylidene, norbornenediene and the like.

It is preferable that the hard segment and the soft segment in the resin are present in a state where the compatibility is good, whereby the tearability and elongation of the film are good, and the processability and the peelability are good. preferable. As the above-mentioned good compatibility, the hard segment and the soft segment are bound by block copolymerization and exist in the same molecule, or IPN (interpenetrating network; interpen).
An example is a state in which a structure such as etrating polymer network) exists and the compatibility is good.

The content of the soft segment is 30 to 300 parts by weight, preferably 40 to 200 parts by weight, based on 100 parts by weight of the hard segment. When the soft segment is 30 parts by weight or more, the relaxation property and tearability are good, while when it is 300 parts by weight or less, the effect of rubber elasticity is not excessive and the relaxation property is good.

The polymer constituting the hard segment or soft segment is exemplified by homo, block or random polymers.

The above resin may be mixed with another appropriate resin to obtain desired substrate characteristics. For example, the tensile elastic modulus of the base material can be increased by further mixing the resin having a hard segment and the soft segment as described above with a resin such as polypropylene.

If necessary, titanium oxide may be added to the above resin.
Inorganic fillers such as zinc oxide and calcium carbonate, amine-based, quinoline-based, hydroquinone-based, phenol-based, antioxidants and antioxidants such as phosphite-based, salicylic acid derivatives, benzophenone-based, benzotriazole-based,
One or more of hindered amine-based UV absorbers, lubricants, plasticizers and the like may be blended within a range not deviating from the gist of the present invention.

The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is as follows:
Adhesives known in the art such as acrylic adhesives and rubber adhesives can be used.

The thickness of the base material is usually 20 to 200.
It is appropriate that the pressure-sensitive adhesive layer has a thickness of about 1 to 20 μm.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following examples. It should be noted that the present invention is not limited to these examples as a matter of course.

Example 1 Resin having 100 parts by weight of a hard segment made of polypropylene and 150 parts by weight of a soft segment made of an ethylene-propylene copolymer (trade name CA-22).
A; manufactured by Highmont Co.) 100 parts by weight, 20 parts by weight of homopolypropylene having an MFR (melt flow rate) of 2.0 g / 10 minutes and a density of 0.9 g / cm ³ were mixed by extrusion molding to give a thickness of 100. A base material of ± 5 μm was prepared. The tensile modulus of the base material, the residual stress after 10 minutes of elongation by 10%, and the tearability of the Elemendorf were measured in both the M direction and the T direction, respectively, and as shown in Table 1. Then, one surface of this substrate was subjected to corona discharge treatment, and an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm was formed on this treated surface to prepare an adhesive film for surface protection.

[0025]

[Table 1]

Example 2 and Comparative Examples 1 to 5 In the above-mentioned Example 1, a base material was prepared in the same manner except that the resin constituting the base material was changed to that shown in Table 2, and an adhesive film for surface protection was prepared. It was made. The tensile modulus of each base material, the residual stress 10 minutes after elongation by 10% and the tearability of the Elemendorff were measured, and the results are shown in Table 1.

[0027]

[Table 2]

(Evaluation of Surface Protective Adhesive Film) Each of the surface protective adhesive films prepared in Examples 1 to 2 and Comparative Examples 1 to 5 was evaluated in the following points, and the results shown in Table 1 were obtained. Was obtained. [Floating during processing] 0.7 mm thick stainless steel plate (SUS-304
2% stretch the adhesive film for surface protection on (BA)
After pressing with a 2 kg roller, punching was performed with a diameter of 20 mm and a pitch of 22 mm. Twenty-four hours after this processing, the presence or absence of floating was examined, and those in which floating did not occur were rated as ◯, and those in which floating did not occur were rated as x. [Attachability (following property) to a protected object having a three-dimensional curved surface]
A stainless steel plate (SUS-304BA) was molded into a hemispherical shape (diameter 10 cm) as shown in Fig. 1. After attaching an adhesive film for surface protection to the curved surface, this molded product was line D shown in the same figure.
It was cut at the position. Twenty-four hours after this processing, the presence or absence of floating was examined, and those in which floating did not occur were rated as ◯, and those in which floating did not occur were rated as x. [Elongation] Peel off the adhesive film for surface protection attached to the stainless steel plate, and if the elongation did not occur at that time, or if only the elongation that did not hinder the peeling work occurred, ○, peeling work becomes difficult The case where some degree of elongation occurred was defined as x. [Tearing at the time of peeling] When the tearing did not substantially occur during the above-mentioned peeling work, it was marked with ◯, and when it did, it was marked with x.

[0029]

[Effect] The adhesive film for surface protection of the present invention has a tensile elastic modulus of 4 Kgf / mm ² or more and less than 30 Kgf / mm ² , and 10 or less.
% The residual stress after 10 minutes of elongation is 0.4 Kgf / mm ² or less is used, so there is little occurrence of film tearing, galling, or floating when processing the protected object. ing.

Further, since the tearability of the Elemendorff is 200 gf or more when the thickness of the above-mentioned substrate is 100 μm, the film is less likely to tear when peeled off,
Therefore, the peeling workability of the film is good.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an object to be protected having a three-dimensional curved surface used for evaluation of an adhesive film for surface protection in Examples.

Front Page Continuation (72) Inventor Hirohito Onishi 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (4)

[Claims] 1. A base material having a pressure-sensitive adhesive layer on one surface thereof, wherein the base material has a tensile elastic modulus of 4 Kgf / mm ² or more, 30 Kg.
Adhesion for surface protection, which is less than f / mm ² , has a residual stress of 0.4 Kgf / mm ² or less after 10 minutes of elongation of 10%, and has a tearability of 200 gf or more of the Elemendorff at a thickness of 100 μm. the film. 2. The adhesive film for surface protection according to claim 1, wherein the substrate is made of a resin other than vinyl chloride resin. 3. The material of the base material has a hard segment and a soft segment, the hard segment is polypropylene, the soft segment is (1) a copolymer of propylene and ethylene, (2) propylene and the formula CH ₂ = CHR
(Wherein R represents an aliphatic group or an aromatic group having 2 to 8 carbon atoms), and one or two kinds selected from a copolymer with an α-olefin and (3) a copolymer of propylene and a diene compound. The adhesive film for surface protection according to claim 1, wherein the adhesive film comprises each of the above resins. 4. The adhesive film for surface protection according to claim 3, wherein the soft segment is contained in an amount of 30 to 300 parts by weight based on 100 parts by weight of the hard segment.