JPH09291262A - Protecting sheet for coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a waterdrop-shielding and protecting sheet for a coating film, having specific moisture permeability without causing the deterioration or discoloration even when bonding and protecting the coating film surface in a hydrous state and capable of continuing the state for a long period and continuing the bonded state without peeling the sheet by forming a tacky layer on a supporting substrate. SOLUTION: This waterdrop-shielding and protecting sheet for a coating film is obtained by forming (B) a tacky layer [e.g. a porous layer comprising a rubber-based tacky containing an A-B-A type block copolymer (concretely a styerene-ethylene.butylene copolymer-styrene type polymer or a styrene- butadiene-styrene type polymer, especially a hydrogenation treated material thereof) as a component] on (A) a supporting substrate such as a porous film (e.g. the once excellent in water resistance such as a polyolefin) and is prepared so as to provide 10-2000g/m<2> .24hr moisture permeability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet for protecting a coating film, which hardly deteriorates or discolors a coating film and is suitable for protecting the surface of automobile bodies and parts, painted steel plates and the like.

[0002]

2. Description of the Related Art When a painted automobile or its parts are loaded on a truck or ship and transported to a remote place such as overseas, it is coated with various floating substances such as dust, rain, etc. or colliding objects. There is a demand for means for preventing film damage, gloss blurring or discoloration. Heretofore, as a preventive measure, a method in which a coating material containing wax as a main component is applied in a thickness of 5 to 40 μm has been known. However, it is difficult to form a uniform thickness of the wax coating, uniform protection cannot be obtained, it is easily soiled, it is vulnerable to acid rain, and wax and the like penetrate the coating and cause discoloration. However, there is a problem in that it takes a lot of labor to apply and remove the wax coating film, and it is easy to induce environmental problems such as the use of solvent and the treatment of waste liquid.

[0003] On the other hand, various surface protection sheets having an adhesive layer provided on a supporting substrate are known, and for an adherend having a coating film, a radiation-curable adhesive having a low glass transition point is used. There has been proposed a layer provided with an adhesive layer or a rubber-based pressure-sensitive adhesive layer such as polyisobutylene (JP-A-2-199184).
JP-A-6-73352). According to such a sheet system, the above-mentioned problem can be overcome. However, there is a problem that when the protective sheet, which has adhesively protected the coating surface, is peeled off, the coating is deteriorated or discolored, and there is a case where contamination that cannot be easily removed occurs. Was.

[0004]

The inventors of the present invention have conducted intensive studies to overcome the above-mentioned problems, and have found that the above-mentioned problem of deterioration and discoloration of the coating film occurs when a protective sheet is adhered to the coating film surface. It was clarified that the cause was that moisture was mixed into the water and sealed for a long time. However, in the case of water that can be easily perceived by large water droplets such as rainwater, the increase in the labor involved in the pre-wiping process and post-replacement process is exceptional, and long-term mixing of water can be easily avoided. It is difficult to eradicate the intrusion of water since the same discoloration of the coating film and the like occurs even when water which is difficult to perceive such as water droplets is mixed.

Therefore, according to the present invention, even if the coating surface is adhered and protected in a state containing water, even if the coating is continued for a long period of time, no deterioration or discoloration of the coating occurs, and the adhesion state is maintained without peeling off the protective sheet. The task is to develop a sheet for protecting coatings that can be made.

[0006]

According to the present invention, a support substrate is provided with an adhesive layer, which has a water-drop shielding property and a moisture permeability of 10 to 2000 g / m ^2.
-Provides a coating film-protecting sheet characterized by being for 24 hours.

[0007]

EFFECTS OF THE INVENTION By means of the coating film protection sheet having the above-mentioned structure with controlled water vapor transmission rate, even if the coating film surface is adhesively protected in a state of containing water, the water vaporizes and volatilizes through the coating film protection sheet. , It is possible to prevent deterioration and discoloration of the coating film even if the adhesive state of the sheet is continued as it is. You can get a sheet. Further, due to the water drop shielding property, it is possible to prevent infiltration of rainwater and the like.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The coating film-protecting sheet of the present invention comprises a supporting substrate provided with an adhesive layer, and has a water-drop shielding property and a moisture permeability of 10
~ 2000 g / m ² · 24 hours. From the standpoint of evaporation of mixed water and prevention of infiltration of rainwater, etc., the water vapor transmission rate is preferably 15 to 1800 g / m ² · 24 hours, especially 20 to
It is 1500 g / m ² · 24 hours.

Therefore, as the supporting base material, at least an appropriate material having the above-mentioned moisture permeability is used. Preferably, 50 g / m ² · 24 hours or more, especially 500 to 500
00g / m ² · 24 hours, especially 1000 to 10000g
/ M ² · It has a water drop shielding property showing a moisture permeability of 24 hours. From this point of view, the supporting base material that can be preferably used is a porous film made of plastic.

The plastic forming the porous film may be any suitable one, preferably one having excellent water resistance and the like. By the way, examples include polyolefins such as polyethylene and polypropylene, polyesters and polyurethanes, ethylene / vinyl acetate copolymers and polytetrafluoroethylene, polyvinyl chloride and polyvinylidene chloride, polyamides and acetal resins, polystyrenes and polycarbonates. To be

For the porous film, for example, a method of casting a dispersion liquid such as an emulsion, a method of stretching the film, a method of removing the mixed fine particles from a film containing fine particles for removal by an elution treatment, an embossing process on the film It may be formed by an appropriate method such as a method of performing a perforation treatment such as the above, or a sintering method of performing fusion treatment of resin powder under heating. From the viewpoints of evaporating mixed water and preventing infiltration of rainwater and the like, those having an average pore diameter of 10 μm or less, preferably 5 μm or less, particularly 0.001 to 2 μm are preferable. The thickness of the supporting substrate is 5 to 500 μm or less, especially 10 to 300 μm, 20 to 20 μm.
200 μm is typical, but not limited to this.

For forming the adhesive layer, a suitable adhesive such as rubber or acrylic can be used. The rubber-based pressure-sensitive adhesive is preferably one that does not have an unsaturated bond or uses a rubber-based polymer having a small content thereof in view of long-term stability of performance. Examples of the rubber-based polymer include polyisobutylene and butyl rubber, styrene-ethylene / butylene copolymer-styrene and styrene-butadiene-styrene, and A-B-A type block polymers composed of hydrogenated products thereof. Can be given.

When preparing the rubber-based pressure-sensitive adhesive, one type or two types are used.
More than one rubber-based polymer can be used. Further, for the purpose of controlling the adhesive properties and the like, for example, α-pinene and β-pinene polymers, diterpene polymers and α-pinene.
Terpene resins such as phenolic copolymers, aliphatic resins and aromatic resins, hydrocarbon resins such as aliphatic / aromatic copolymers, other rosin resins and coumarone indene resins,
Appropriate tackifiers such as (alkyl) phenolic resins, xylene-based resins and alkyd-based resins can be added.

Further, an appropriate softening agent depending on the rubber type polymer such as low molecular weight polyisobutylene to polyisobutylene, paraffin type oil to ABA type block polymer, etc. is blended as necessary to obtain adhesive properties. Etc. can be controlled. In addition, for the purpose of improving the moisture permeability of the pressure-sensitive adhesive layer, particularly a rubber-based pressure-sensitive adhesive layer, a compound having high polarity, hydrophilicity and water-absorbing property, such as a water-absorbing resin and an emulsifier, may be blended. In addition, appropriate additives such as fillers, pigments, antioxidants and stabilizers can be added as necessary.

On the other hand, the water vapor permeability can be improved also by the method of forming the adhesive layer as a porous layer. The adhesive layer formed of a porous layer can be formed by, for example, a method of fiberizing the adhesive by a melt-blowing method or a curtain spray method and depositing it into a non-woven fabric, a method of partially coating the adhesive into dots, etc. It can be performed by an appropriate method.

The coating film protective sheet can be formed by, for example, a method of applying a solution of a pressure-sensitive adhesive solvent or a hot-melt solution of the pressure-sensitive adhesive to a supporting substrate, a method of transferring the pressure-sensitive adhesive layer formed on the separator, and the like. It can be performed according to the method for forming the adhesive sheet. The thickness of the pressure-sensitive adhesive layer to be formed may be appropriately determined, and is generally 200 μm or less, especially 5 to 50 μm. The adhesive layer, if necessary, until it is put into practical use,
It is protected by temporarily attaching a separator or the like.

The adhesive layer in the coating film-protecting sheet preferably has a continuous film structure from the viewpoint of water drop shielding property, but it may be a porous layer as described above. Also in the case of an adhesive layer composed of a porous layer, it is possible to form an adhesive layer having a moisture permeability and a water drop shielding property due to its porous state. Further, in the present invention, the object can be achieved even by a system in which only the supporting base material has the function of blocking water droplets. Therefore, in the present invention, it is sufficient that the coating film protective sheet as a whole achieves the water drop shielding property. The water drop shielding property means a function of preventing the intrusion of water drops such as rainwater, and intrusion of water in a mist state or below is allowed.

The coating film-protecting sheet of the present invention is, for example, an automobile body or its parts coated with a coating film of melamine / alkyd series, melamine / acrylic series, or urethane series, or a metal plate such as a steel plate or the like. It is preferably used for collision of microscopic substances on an adherend having a coating film formed of the molded product, surface protection from chemicals and the like. Especially,
It can be advantageously used when moisture is likely to be mixed in when the protective sheet is bonded, or when rainwater or the like easily enters the interface between the sheet and the coating film when stored outdoors.

[0019]

【Example】

Example 1 A toluene solution of a rubber-based pressure-sensitive adhesive comprising a mixture of 90 parts of polyisobutylene having a viscosity average molecular weight of 1,000,000 (parts by weight, the same applies hereinafter) and 10 parts of polyisobutylene having a viscosity average molecular weight of 80,000 and having a thickness of polyethylene. It is 90μm, and the water vapor transmission rate is 3600g / m ² · It is applied to a porous film (Porum # 70 manufactured by Tokuyama Soda Co., Ltd.) for 24 hours, and it is applied at 80 ° C for 2
After drying for a minute, a coating film-protecting sheet having an adhesive layer having a thickness of 15 μm was obtained.

Example 2 A coating film-protecting sheet was obtained in the same manner as in Example 1 except that 5 parts of an anionic emulsifier (sodium dodecylbenzene sulfonate) was added to the rubber adhesive.

Example 3 10 parts of a water-absorbent resin (AQUALIC CA ML-100 manufactured by Nippon Shokubai Co., Ltd.) having a deionized water absorption capacity of 200 g / g and a maximum particle size of 10 μm was added to a rubber adhesive. A coating film protection sheet was obtained in the same manner as in Example 1.

Example 4 As a rubber-based pressure-sensitive adhesive, an ABA type block polymer consisting of styrene-ethylene / butylene copolymer-styrene (Shell Chemical Co., Ltd., Kraton G-1657) 100
And hydrogenated petroleum resin (Arakawa Chemical Co., Alcon P-1
00) A coating film-protecting sheet was obtained in the same manner as in Example 1 except that 40 parts of the mixture was used.

Example 5 The rubber-based pressure-sensitive adhesive obtained in Example 4 was kneaded in a kneader at 160 ° C. to form chips, and the chips were put into a die to be made into fibers having an average diameter of about 20 μm by a melt blow method and placed on a separator. A coating film protection sheet was obtained in the same manner as in Example 1 except that a porous adhesive layer deposited as a porous layer having a basis weight of 20 g / m ² was used. In addition, the above-mentioned melt blow is performed by a die temperature of 200 ° C, a hot air temperature of 210 ° C, and a hot air pressure of 1.0 to 2.0.
It was performed under the conditions of kg / cm ² and a line speed of 3 m / min by the conveyor.

Comparative Example 1 Polypropylene / polyethylene (weight ratio:
9/1) 40 μm thick film (non-porous material)
Was used in the same manner as in Example 1 to obtain a coating film protecting sheet.

Comparative Example 2 A coating film protection sheet was obtained in which the coating film protection sheet obtained in Comparative Example 1 was formed with through holes having a diameter of about 0.5 mm at a rate of 6 holes / cm ² .

Evaluation test The following tests were carried out on the coating film protective sheets obtained in Examples and Comparative Examples. Water vapor transmission rate The water vapor transmission rate was examined according to JIS K 0208.

Moisture volatility Water is sprayed onto the melamine / acrylic coating film on the iron plate to adhere a coating film protection sheet thereon, and the coating film protection sheet is peeled off after standing at 40 ° C. for 48 hours. Then, it was examined whether or not water remained on the coating film.

Water-drop shielding property A film-protecting sheet is adhered to a melamine / acrylic film on an iron plate while forming a bubble portion having a diameter of about 1 cm, and shower water is sprinkled on the film for 10 minutes to protect the film. The sheet was peeled off, and it was examined whether water penetrated into the bubble portion.

The above results are shown in the following table. *: 3000 or more

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenichi Shibata, 1-2 Shimohozumi, Ibaraki-shi, Osaka Prefecture Nitto Denko Corporation (72) Naoyuki Nishiyama, 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Prefecture Nitto Denko Co., Ltd. (72) Inventor Mitsuru Toda 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Co., Ltd. (72) Inventor, Koharu Matsui 4-1-1, Higashi-Hachiman, Hiratsuka, Kanagawa Incorporated (72) Inventor Takeshi Eda 33-1 Kanzaki-cho, Amagasaki-shi, Hyogo Kansai Paint Co., Ltd. (72) Inventor Hiroshi Ueda 33-1 Kanzaki-cho, Amagasaki-shi, Hyogo In Kansai Paint Co., Ltd.

Claims (4)

[Claims] 1. A coating film-protecting sheet comprising a supporting substrate provided with an adhesive layer, which has a water-drop-shielding property and a moisture permeability of 10 to 2000 g / m ² · 24 hours. 2. The coating film protecting sheet according to claim 1, wherein the supporting base material is a porous film. 3. The coating film protective sheet according to claim 1 or 2, wherein the adhesive layer comprises a rubber-based adhesive containing one or more of polyisobutylene, butyl rubber or ABA type block polymer as a component. . 4. The coating film protecting sheet according to claim 1, wherein the adhesive layer is a porous layer.