JP3347884B2 - Surface protection film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the processing of metal plates such as stainless steel plates, aluminum plates, colored steel plates, and colored aluminum plates, during transportation or storage, when dust adheres or scratches on the surfaces of these plates. The present invention relates to a surface protective film used for preventing sticking, which is preferably used when performing mechanical processing such as drawing while being attached to an adherend.

[0002]

2. Description of the Related Art Conventionally, as a surface protective film suitable for machining a metal plate or the like, since the mechanical processing is performed while temporarily attaching the surface protective film to an adherend surface, the quality required for the surface protective film is originally required. It is required to have machinability in addition to the properties of temporary adhesion and removability. As a material with this machinability, among the existing films, a soft vinyl chloride resin film is the most suitable.Therefore, a soft vinyl chloride resin film formed by extrusion molding is used as a base material. A method is widely used in which an adhesive layer is provided and adhered to an adherend, or a polyvinyl chloride sol is directly applied to the adherend to form a dry film.

[0003] However, a film made of a soft vinyl chloride resin has a problem of hygiene and pollution since it emits a toxic gas at the time of disposal and incineration after its use. Adoption has been considered.

For example, JP-A-53-21239 discloses a technique in which a copolymer obtained by copolymerizing ethylene with an α-olefin having 4 or more carbon atoms is used as a raw material of a base film. This is a so-called linear low-density polyethylene, which aims to utilize the mechanical strength and flexibility provided by the copolymer resin.

On the other hand, Japanese Patent Publication No. 1-12655 discloses that
A technique using a film formed from a blend of polyethylene and polypropylene as a base material is disclosed. That is, the purpose is to combine the flexibility of polyethylene and the excellent mechanical strength of polypropylene.

[0006]

However, among the surface protective films based on the above-mentioned olefin-based resin film, those whose base material is composed of a copolymer, it is difficult to increase the content of α-olefin in the copolymerization step. Difficult,
The resulting film has excessive flexibility,
On the other hand, when the base material is made of a blend, it is extremely difficult in technology to uniformly mix both resins at a predetermined mixing ratio, and a material having desired mechanical properties cannot be obtained. was there.

[0007] The present invention solves the above-mentioned problems of the surface protective film, and is particularly suitable for use in machining such as drawing, and does not cause any problem on sanitation or pollution. It was made to provide things.

[0008]

In the surface protective film of the present invention According to an aspect of the olefin resin forming the substrate is made of a propylene copolymer which is copolymerized by reactor blending process. Here, the reactor blending method is
This is a polymerization method in which a plurality of types of polymers can be continuously produced by performing multi-stage polymerization of two or more stages, instead of completing polymerization once, and using a mechanical method to produce different types of polymers. Where a mixed resin consisting of a polymer is obtained,
This is a method completely different from the so-called ordinary polymer blending method, and is a method for producing a blend type copolymer resin at a molecular level. By finely dispersing the components of the resin thus obtained, a material faithfully embodying the machinability having different properties, which is possessed by the resins to be mixed, can be obtained. As a specific manufacturing method, for example, a method described in JP-A-3-205439 is used.

In the present invention,Olefin resin
Is a rubber component consisting of an ethylene-propylene component
Below, simply referred to as a rubber component) is 30 to 60% by weight,
If the amount of ethylene in the rubber component is not more than 20% by weight
No. If the rubber component is less than 30% by weight,
Cuts easily occur during drawing, exceeding 60% by weight
This leads to excessive flexibility and mechanical strength
Generally lacking and poor machinability
is there. Also, the amount of ethylene in the rubber component was reduced to 20% by weight.
If not, it becomes hard and difficult to bend,
Possibility of following work during machining is poor, and cuts occur during drawing.

In addition, the olefin used in the present invention
The resin has a crystallinity of 40-70% and a density of 0.8
85 to 0.915 g / cm ³ and MFR of 5 g / 1
Must be 0 minutes or less.

When the crystallinity is less than 40%, the modulus of elasticity of the base material is reduced, so that the initial tensile strength is reduced, and the film is excessively stretched at the time of forming a film, attaching a film, or peeling off. Workability is deteriorated, and conversely, crystallinity is 7
If it exceeds 0% , it becomes hard and poor in stress relaxation,
This is because floating occurs during drawing.

[0012] Density mechanical properties decreases in general is less than ^{0.885g / cm 3, 0.915g / cm} 3 cold working follow-up property is deteriorated becomes poor flexibility exceeds, drawing This is because a break sometimes occurs.

When the MFR exceeds 5 g / 10 minutes,
The mechanical properties generally deteriorate, and the workability is reduced due to cutting during bending or stretching during peeling.

When the base material for the surface protective film of the present invention is obtained using the above-mentioned raw materials, the thickness of the base material varies depending on the thickness of the adherend to be applied.
In the case of an adherend having a thickness of 1 mm or less, which is frequently used in drawing, the thickness is preferably about 30 to 70 μm.

The pressure-sensitive adhesive used in the surface protective film of the present invention may be any one of a rubber type and an acrylic type as long as it can satisfy the function as the surface protective film. As a means for forming the agent layer, any of a coating method and a co-extrusion method can be adopted. The thickness of the pressure-sensitive adhesive layer thus obtained is usually 3
５０50 μm.

In order to enhance the practicality of the surface protective film, a release agent may be used on the back surface of the base material, or the surface may be hard to slip due to the flexibility of the base material. In a raw material for laminating another resin layer or forming a base material, other compounds such as low-density polyethylene (LDP) may be used as long as the intended effects of the present invention are not impaired.
E), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE) polypropylene and the like may be mixed and used within a range of 50% by weight, or an additive such as a pigment may be used. It is preferable to use a material based on, because it is easy to improve other film physical properties while reducing the influence on the stress relaxation performance of the film. When a desired copolymer is obtained by the above-described reactor blending method, another α-olefin may be included in order to further impart another function in the polymerization vessel.

[0017]

The surface protective film of the present invention uses various types of machinability such as bending, punching, drawing, etc. since the above-mentioned polyolefin resin forming the base material is used. It has become something.

[0018]

Embodiments of the present invention will be described below in detail.

Example 1 As a propylene copolymer copolymerized by a reactor blending method, KS-021P (trade name, rubber component content = 45% by weight, ethylene content in rubber component = 20) manufactured by Himont Co., Ltd. % By weight, crystallinity = 48%, density = 0.892 g / cm ³ , MFR =
(0.8 g / 10 minutes), an olefin resin film having a thickness of 70 μm is formed by an inflation method, and one surface of the obtained film is subjected to a corona discharge treatment, and then a pressure-sensitive adhesive solution (manufactured by Soken Chemical Co., Ltd .; AG105) was applied to a dry thickness of 5 μm, and dried to obtain a sample of the surface protective film.

Example 2 The same propylene copolymer as in Example 1 and polypropylene [AG352 manufactured by Mitsubishi Kasei Co., Ltd.]
1 (trade name)] in a ratio of 3: 1 by weight (rubber component amount = 34% by weight, ethylene amount = 20% by weight or more, crystallinity = 53%, density = 0.8
A sample of the surface protective film was obtained in the same manner as in Example 1, except that 93 g / cm ³ and MFR = 2.8 g / 10 min) were used.

Example 3 The same propylene copolymer as in Example 1 was used as the resin for forming the middle layer, and polypropylene [AG3521 (trade name) manufactured by Mitsubishi Kasei Co., Ltd.] was used as the resin for forming the inner and outer layers. By the inflation method, the thickness constitution is 10:50:10 and the total thickness is 70 μm.
m of an olefin-based resin film, and
A sample of the surface protective film was obtained in the same manner as described above.

(Comparative Example 1) Linear ultra-low-density polyethylene (Ultzex 3520 (trade name) manufactured by Mitsui Petrochemical Industries, Ltd.) and polypropylene [AG3521 manufactured by Mitsubishi Kasei Co., Ltd.
(Trade name)] in a ratio of 3: 1 by weight [rubber component amount = less than 3% by weight, ethylene amount = less than 20% by weight, crystallinity = 68%, density = 0.
904 g / cm ³ , MFR = 3.3 g / 10 min], and a sample of the surface protective film was obtained in the same manner as in Example 1.

(Comparative Example 2) A propylene copolymer copolymerized by a reactor blend method [ KT-011P (trade name) manufactured by Himont Co., Ltd .;
Rubber component amount = 27% by weight, ethylene amount = 20% by weight or more, crystallinity = 75%, density = 0.892 g / cm ³ ,
MFR = 10.0 g / 10 min], except that
In the same manner as in Example 1, a sample of the surface protective film was obtained.

Comparative Example 3 A propylene copolymer copolymerized by a reactor blend method [KS-051P (trade name) manufactured by Himont Co., Ltd .;
Rubber content = 50% by weight, ethylene content = 20% by weight or more, crystallinity = 36%, density = 0.890 g / cm ³ ,
MFR = 0.8 g / 10 min], and a sample of the surface protective film was obtained in the same manner as in Example 1.

(Comparative Example 4) A propylene copolymer [KS-021P (trade name) manufactured by Himont) and polypropylene [AG3521 (trade name) manufactured by Mitsubishi Kasei] in a weight ratio of 1: 3. [A mixed resin [rubber component amount = 11% by weight, ethylene amount = 20% by weight or more, crystallinity = 64%, density = 0.899 g / cm ³ ,
MFR = 4.5 g / 10 min), except that a sample of the surface protective film was obtained in the same manner as in Example 1.

(Comparative Example 5) A propylene copolymer [KS-021P (trade name) manufactured by Himont) and a linear low-density polyethylene [Ultzex 35 manufactured by Mitsui Petrochemical Co., Ltd.]
20L (trade name)] in a ratio of 1: 3 by weight [rubber component amount = 11% by weight,
(Ethylene content = 20% by weight or more, crystallinity = 62%, density = 0.923 g / cm ³ , MFR = 3.2 g / 10 min)
A surface protective film sample was obtained in the same manner as in Example 1, except that was used.

The surface protection film samples obtained in each of the above Examples and Comparative Examples were subjected to bending, punching, and drawing, and were evaluated for their machinability. It is shown in FIG. In Table 1, the crystallinity of the film-forming resin is also shown.
The density, MFR, rubber component amount, ethylene amount and the like are indicated.
The test method and evaluation are as follows.

Bendability: Each sample was adhered to a stainless steel plate (thickness: 0.6 mm, # SUS430BA), bent at 90 ° by a press machine, and cut and peeled off the film near the bent portion after processing. Observe the condition of the stainless steel plate visually. The evaluation was ◎ when the state of the metal plate after cutting and peeling of the film near the bending portion did not show any abnormality, △ when one showed an abnormality, and × when both showed an abnormality. And

Punching workability: Each sample was affixed to the same stainless steel plate as described above, a round hole having a diameter of 20 mm was punched out with a press machine, and the cut surface after punching and the state of the stainless steel plate after peeling were visually observed. The evaluation was ◎ when no abnormality was found in both the cut surface and the state of the metal plate after peeling, Δ when one was abnormal, and X when both were abnormal.

Drawability: Each sample was affixed to the same stainless steel plate as described above, and was formed into a column having a diameter of 30 mm and a depth of 15 m.
m, and left in a constant temperature room at 40 ° C. for 1 day, then visually observe the floating state of the film.
Peel off the film and observe whether the peeled film is cut or not. In the evaluation, the floating state of the film was evaluated as ◎ when the film did not float, and was evaluated as x when the film was floating.

Peeling workability: The processed film was peeled off, and the film was peeled cleanly, and the case where the film was stretched was evaluated as ○.

[0032]

[Table 1]

As is evident from the results in Table 1, in each of the examples, excellent evaluations of the machinability were obtained, whereas in Comparative Example 1, the amount of the rubber component was extremely small. ,
Floating or cutting occurs during drawing. In the case of Comparative Example 2, the degree of crystallinity was high, the stress relaxation was poor, floating occurred during drawing, the MFR was extremely large, the mechanical strength was generally reduced, and the bending workability was poor. In addition, cuts occurred during drawing. In the case of Comparative Example 3, the crystallinity was low, the bending workability and the punching workability were slightly poor, and the drawing workability was good, but it was elongated at the time of peeling. In the case of Comparative Example 4, since the amount of the rubber component was small, the stress relaxation was poor, so that floating occurred at the time of drawing and cutting occurred. Further, in the case of Comparative Example 5, since the amount of the rubber component was small and the density was high, the stress relaxation property was poor, so that floating occurred at the time of drawing and cutting occurred.

[0034]

According to the surface protective film for drawing of the present invention, the polyolefin-based resin forming the base material is as described above.
Of propylene-based copolymers according to
Since it has tools, it has excellent machinability such as bending workability, punching workability, and drawing workability.

Therefore, it is suitable for use in surface protection of an adherend through a metal plate processing step, in particular, one subjected to drawing . In addition, since an olefin resin film is used as the base material, there is no problem such as toxic gas generation during incineration and the temperature dependence is small compared to those using a soft vinyl chloride resin film base material. It is not necessary to change or adjust the composition of the base material, and the specific gravity is small, so the size of the product can be increased and the workability at the site can be improved. it can.

Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C09J 7/02 C08L 23/14 Patent file (PATOLIS) JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A surface protection film in which an adhesive layer is formed on one surface of a substrate made of an olefin resin film, wherein the olefin resin forming the substrate is copolymerized by a reactor blend method. from union
In the olefin resin , the rubber component composed of an ethylene-propylene component is 30 to 60% by weight, the amount of ethylene in the rubber component is 20% by weight or more, and the crystallinity is 40 to 70%. Density 0.885 to 0.915 g /
cm ^3, drawing a surface protective film, wherein the or less MFR5g / 10 min.