TWI542658B - Pressure-sensitive adhesive film or sheet, surface-protective film or sheet, and method of use for protecting surface of article - Google Patents

Description

Pressure sensitive adhesive film or sheet, surface protective film or sheet, and method for protecting the surface of the article

The present invention relates to a pressure sensitive adhesive film or sheet, a surface protective film or sheet, and a method for protecting the surface of an article.

The adhesive film or sheet is used as a surface protective film for protecting the surface of the article from dust adhesion, soiling, scratching, and the like.

In recent years, it has also been used as a surface protection film for precision electronic parts.

For adhesive films or sheets, it is required that the adhesion between the adhesive layer and the adherend has moderate strength. The "appropriate strength" refers to a strength that does not naturally peel off by itself or falls off due to slight vibration or impact, and does not leave an adhesive layer on the surface of the adherend when peeling, and the strength can be smoothly peeled off.

An adhesive film or sheet which satisfies such a required property is a film or sheet composed of an ethylene-vinyl acetate copolymer.

Patent Document 1 (Japanese Patent Laid-Open No. Hei 6-146516) describes a surface protective film characterized in that the adhesive layer is composed of a vinyl acetate content of 3 to 7% by weight and a melt flow rate of 2 to 20 g/10. Each of 100 parts by weight of the ethylene-vinyl acetate copolymer contains 0.5 to 2 parts by weight of the adhesion-imparting agent. It is described that the surface protective film exhibits an appropriate initial adhesion, and even if heat treatment (particularly, UV irradiation) is performed, the adhesion does not increase significantly, and the contamination of the object to be protected is not caused.

Patent Document 2 (Japanese Patent Laid-Open No. 2008-255233) describes a stickiness A film or sheet comprising a polypropylene resin substrate layer (A) and an adhesive layer (B); the adhesive layer (B) is composed of a vinyl acetate unit having a vinyl acetate unit content of 7.5 to 50% by weight of ethylene/vinyl acetate It is composed of an ester copolymer.

It is described that the adhesion between the adhesive film or the substrate layer and the adhesive layer is high, and the adhesive layer has a moderate adhesive force to the surface of the object to be adhered, and the substrate layer has thermal characteristics such as softening temperature and heat distortion temperature, and is pulled. It has excellent mechanical properties such as tensile strength, impact resistance, and stiffness, as well as optical properties such as fog value, gloss, and light transmittance. Further, there is almost no fisheye, and the surface is smooth and the appearance is excellent.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. Hei 6-146516

Patent Document 2: Japanese Patent Laid-Open Publication No. 2008-255233

The ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 7% by weight as described in Patent Document 1 (Japanese Laid-Open Patent Publication No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei. Therefore, in order to obtain the required initial adhesion, it is necessary to contain a large amount of an adhesion-imparting agent. Moreover, the adhesive force tends to be stronger than the initial adhesive force. Further, when the surface protective film is peeled off, there is a tendency that the adhesive layer is likely to remain on the surface of the adherend, and the stain resistance to the adherend is insufficient under strict evaluation conditions.

The ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 7.5 to 50% by weight described in Patent Document 2 (Japanese Laid-Open Patent Publication No. 2008-255233) has sufficient initial adhesion to the adherend. However, there is a strong tendency for the adhesion to be stronger than the initial adhesion force over time.

Therefore, it is conventionally known that a film or sheet composed of an ethylene-vinyl acetate copolymer has a balance between adhesion and stain resistance, and those skilled in the art are eager to further improve.

Therefore, an object of the present invention is to provide a pressure-sensitive adhesive film which is excellent in the balance between adhesiveness and stain resistance when the adhesive layer is pressed against the adhesive body at room temperature without actively heating the adhesive layer. sheet.

According to the present invention, there is provided a pressure-sensitive adhesive film or sheet comprising an adhesive layer comprising an ethylene/vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less. And an adhesion-imparting agent having a softening temperature of 95° C. or more and 150° C. or less measured according to the GIS K2207-1996 ring method; and the total amount of the ethylene/vinyl acetate copolymer and the adhesion-imparting agent is 100 parts by mass. In the case of the above-mentioned adhesion-imparting agent, the content is 0.1 parts by mass or more and 1.0 part by mass or less.

According to the invention, by using a vinyl acetate content of 7.5% by mass or more Further, the ethylene/vinyl acetate copolymer of 20% by mass or less can maintain an appropriate initial adhesion and reduce the amount of the adhesion-imparting agent added, and as a result, the stain resistance to the adherend can be improved. Therefore, a pressure-sensitive adhesive film or sheet excellent in initial adhesion and balance with stain resistance to the adherend can be obtained.

Further, by including an adhesion-imparting agent having a softening temperature of 95 ° C or more and 150 ° C or less, the improvement of the adhesion with time can be suppressed.

Further, according to the present invention, there is provided a method for protecting the surface of an article by using the above-mentioned pressure-sensitive adhesive film or sheet for protecting the surface of the article.

According to the present invention, it is possible to provide a pressure-sensitive adhesive film or sheet excellent in balance between adhesiveness and stain resistance.

The above and other objects, features and advantages of the present invention will become more apparent from

Hereinafter, embodiments of the present invention will be described.

The pressure-sensitive adhesive film or sheet of the present embodiment includes an adhesive layer containing an ethylene/vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less; and according to JIS K2207 - the adhesion-imparting agent having a softening temperature of 95 ° C or more and 150 ° C or less measured by the method of the method of the method of the invention, wherein the amount of the ethylene/vinyl acetate copolymer and the adhesion-imparting agent is 100 parts by mass, the adhesion-imparting agent The content is 0.1 parts by mass or more and 1.0 part by mass or less.

Further, the adhesive force between the adhesive layer of the present invention and the adherend does not mean that the adhesive layer is adhered to the adherend and heated under heating conditions such as a melting point of an adhesive such as a hot-melt adhesive. Rather, it indicates that the adhesive layer is adhered to the adherend in a temperature environment not exceeding the melting point, and the interlayer peel strength at the subsequent step is performed.

(adhesive layer)

First, each component of the adhesive layer constituting the pressure-sensitive adhesive film or sheet of the present embodiment will be described.

"ethylene/vinyl acetate copolymer"

The ethylene/vinyl acetate copolymer (EVA) which is an essential component of the adhesive layer of the present embodiment is a copolymer of ethylene and vinyl acetate.

The ethylene/vinyl acetate copolymer of the present embodiment is a vinyl acetate component unit content of 7.5% by mass or more and 20% by mass or less, preferably 8% by mass or more and 15% by mass or less, more preferably 9% by mass or more. And 12% by mass or less. If the vinyl acetate content is within the above range, a pressure-sensitive adhesive film or sheet having a moderate initial adhesion can be obtained.

The ethylene/vinyl acetate copolymerization system of the present embodiment preferably has a melt flow rate (MFR) (according to JIS K7210-1999) of 1 g/10 min or more and 50 g/10 min or less, preferably at 190 ° C under a load of 2160 g. It is 2 g/10 minutes or more and 30 g/10 minutes or less.

When the MFR is at least the above lower limit value, a pressure-sensitive adhesive film or sheet excellent in smoothness and initial adhesion of the film can be obtained. Also, if the MFR is above When the amount of the low molecular component is less than the upper limit, the adhesion of the film and the pressure-sensitive adhesive film or sheet which is more excellent in the stain resistance of the protective substrate can be obtained.

"adhesive agent"

The adhesion-imparting agent which is an essential component of the adhesive layer of the present embodiment is formulated to improve the adhesion of the ethylene/vinyl acetate copolymer.

Examples of the adhesion-imparting agent include petroleum-based resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic-aromatic copolymerization hydrocarbon resins, and alicyclic hydrocarbon resins; terpene resins and coumarone- Terpene resin such as a fluorene resin or a terpene phenol resin; a polymerized rosin resin; an (alkyl) phenol resin; a xylene resin; or such a hydride. Among these, a hydride of a petroleum resin or a hydride of a particularly preferred alicyclic hydrocarbon resin (also referred to as "alicyclic saturated hydrocarbon resin") is preferred.

An olefin resin may also be contained in these adhesion-imparting agents.

The softening temperature of the tackifier according to JIS K2207-1996 Ring and Ball method is 95 ° C or higher, preferably 98 ° C or higher. When the softening temperature is at least the above lower limit value, a pressure-sensitive adhesive film or sheet which suppresses the increase with time can be obtained.

Further, the softening temperature of the adhesion-imparting agent measured according to JIS K2207-1996 Ring and Ball method is 150 ° C or lower, preferably 130 ° C or lower, more preferably 110 ° C or lower. When the softening temperature is at most the above upper limit value, a pressure-sensitive adhesive film or sheet having an excellent initial adhesion can be obtained.

The pressure-sensitive adhesive film or sheet of the present embodiment has an adhesion increase as shown in the following formula (1). The rate (%) is preferably 0% or more and 400% or less, more preferably 0% or more and 300% or less. The adhesion enhancement rate can be set within the above range by adding a predetermined amount of the above-mentioned adhesion-imparting agent.

Adhesion improvement rate (%) = [(adhesion after aging at 60 ° C, 7 days - initial adhesion) / initial adhesion] × 100 (1)

Further, by adding a predetermined amount of the above-mentioned adhesion-imparting agent, the adhesion improvement rate can be suppressed as compared with the resin before the addition of the adhesion-imparting agent.

The adhesion-imparting agent having a softening temperature of 95 ° C or higher may be, for example, ARKON P-100 (softening temperature: 100 ° C), ARKON P115 (softening temperature: 115 ° C), ARKON P125 (softening temperature: 125 ° C) manufactured by Arakawa Chemical Industries, Ltd. ), ARKON P140 (softening temperature 140 ° C), PINECRYSTAL KE-604 (softening temperature 122 ° C or more and 134 ° C or less); YA Polyara T1 (softening temperature 145 ° C), CLEARON P150 (softening temperature 150) manufactured by YASUHARA CHEMICAL CORPORATION °C) and so on.

When the total amount of the ethylene/vinyl acetate copolymer and the adhesion-imparting agent is 100 parts by mass, the content of the adhesion-imparting agent is 0.1 part by mass or more, preferably 0.2 part by mass or more. Preferably, it is 0.3 parts by mass or more. When the content of the adhesion-imparting agent is at least the above lower limit value, a pressure-sensitive adhesive film or sheet having an excellent initial adhesion can be obtained.

In addition, the content of the adhesion-imparting agent is 1.0 part by mass or less, preferably 0.9 part by mass or less, and particularly preferably 0.8 part by mass or less. If the content of the adhesion-imparting agent is less than or equal to the above upper limit value, the adhesion can be improved over time, A pressure-sensitive adhesive film or sheet which is more excellent in balance with the stain resistance of the adherend.

Further, in the adhesive layer of the present embodiment, an additive which is generally used in a polymer field such as an antioxidant, an ultraviolet absorber, a light stabilizer, and an anti-adhesive agent can be further blended to the extent that the adhesive layer property is not impaired.

(Modulation method of resin composition)

The resin composition used in the formation of the pressure-sensitive adhesive layer of the present embodiment is subjected to dry blending or melt blending simultaneously or sequentially by, for example, the above-mentioned ethylene-vinyl acetate copolymer, the above-mentioned adhesion-imparting agent, and other additives as needed. And get.

As the dry blending system, various mixers such as a Henschel mixer and a drum mixer can be used.

Further, in the case of melt blending, a kneading device such as a uniaxial or biaxial extruder, a Banbury mixer, a drum, a kneader, or the like may be used, for example, at a temperature of about 140 ° C or higher and 230 ° C or lower. Melt and knead.

(pressure-sensitive adhesive film or sheet)

Next, the pressure sensitive adhesive film or sheet will be described.

The method for producing the pressure-sensitive adhesive film or sheet of the present embodiment is not particularly limited, and for example, it can be obtained by molding the resin composition into a single layer film or a sheet shape. In this case, the obtained single layer film or sheet corresponds to the adhesive layer of the present embodiment. Further, it can also be obtained by forming an adhesive layer on at least one of the base materials using the above resin composition.

The latter method is generally employed in which the above resin composition is used to form an adhesive layer on at least one of the substrates.

The base material is not particularly limited, and examples thereof include various thermoplastic resin films or sheets which are formed by using one or two or more kinds of thermoplastic resins such as polyester, polyamide or polyolefin.

Here, examples of the polyolefin include polypropylene, a block system or a random propylene polymer having a vinyl component as a copolymer component; low density polyethylene, high density polyethylene, linear low density or ultra low An ethylene-based polymer such as density polyethylene; an ethylene-propylene copolymer or the like.

Further, paper, metal foil, non-woven fabric, or the like may be used as the substrate.

In the present embodiment, a substrate containing a polyolefin such as polyethylene or polypropylene in the above is particularly preferable.

When a base material containing a polyolefin is used, a film or sheet excellent in interlayer adhesion between the adhesive layer and the substrate and excellent in transparency can be obtained.

When a thermoplastic resin film is used as the substrate, it is possible to further prepare, for example, an antioxidant, a UV absorber, a hindered amine light stabilizer, etc., in the thermoplastic resin to be a substrate, for the purpose of preventing deterioration or the like. Agent; antistatic agent; carbon black, calcium oxide, magnesium oxide, cerium oxide, zinc oxide, titanium oxide and other fillers; additives such as pigments.

The thickness of the substrate is not particularly limited, and is usually 1 μm or more and 500 μm or less, preferably 10 μm or more and 200 μm or less.

The resin composition of the present embodiment is used to form an adhesive layer on a substrate. The method may be, for example, a solution coating method in which a solution or a hot melt of a resin composition is applied to a substrate; after being applied to a separator substrate by a solution coating method, the transfer is formed by transfer a method of adhering a layer; extruding a resin composition onto a substrate to perform a hot melt coating method for forming a coating; and coextruding the substrate and the resin composition by two or more layers to form a film a method of extrusion laminating a resin composition on a substrate according to a single layer; a method of performing extrusion lamination of the adhesive layer and the resin composition in two layers; and an adhesive layer, a film or a laminate layer A method of performing thermocompression bonding of the support substrate forming material or the like is carried out by a known method.

Among these, a method in which a base material composed of a thermoplastic resin and a resin composition are co-extruded by two or three or more layers by a inflation method or a T-die method is preferably used.

In the present embodiment, the thickness of the adhesive layer formed on the substrate is appropriately determined in accordance with the adhesive force or the like, and is generally preferably 1 μm or more and 250 μm or less, and more preferably 5 μm or more and 100 μm or less.

Further, in the case where a single layer film or sheet of a substrate is not provided, the thickness of the adhesive layer formed on the substrate is preferably 5 μm or more and 300 μm or less, more preferably 10 μm or more and 200 μm or less.

In the pressure-sensitive adhesive film or sheet of the present embodiment, the adhesive layer is applied to the surface of the rigid (rigid) adherend, and the adhesive layer is applied only by pressure without being actively heated. When it is not needed, it can be easily peeled off by hand without leaving any contaminants on the surface of the adherend. The adhered system can be enumerated as follows: Surface protection for products such as synthetic resin sheets, decorative sheets, metal sheets, and coated steel sheets.

Further, examples thereof include surface protection for window glass, automotive paint, and surface protection for solder substrate immersion of printed circuit boards.

In addition, a liquid crystal panel, a reflector, a phase difference plate, a cymbal, a light guide plate, a polarizing plate, a plasma display panel, and the like, such as a liquid crystal display device, a plasma display device, and an organic thin film EL device, may be mentioned. Precision electronic components such as organic phosphor films, transparent electrodes, flexible printed circuit boards, and rigid printed circuit boards. The pressure-sensitive adhesive film or sheet of the present embodiment is particularly preferably used as the film or sheet for surface protection. Another embodiment provides a method for protecting the surface of an article by applying the pressure sensitive adhesive film or sheet to protect the surface of the article. Examples of the article to be surface-protected include the above-mentioned adherend.

The embodiments of the present invention have been described above, but these are merely examples of the present invention, and various configurations other than the above may be employed.

[Examples]

Hereinafter, the embodiment and the comparative example will be described with respect to the present embodiment, but the embodiment is not limited to these.

[raw material]

In the examples and comparative examples, the following raw materials were used.

EVA1: ethylene/vinyl acetate copolymer (MFR = 9 g/10 min, ethylene content = 90% by mass, vinyl acetate content = 10% by mass)

Adhesive-imparting agent 1: alicyclic saturated hydrocarbon resin (Arkon Chemical Co., Ltd., ARKON P-100, softening temperature 100 ° C)

Adhesive-imparting agent 2: alicyclic saturated hydrocarbon resin (Arkon Chemical Co., Ltd., ARKON M-90, softening temperature 90 ° C)

‧MFR: JIS K7210-1999 (190 ° C, 2160 g load)

‧ Melting point: JIS K7121-1987

‧ Softening temperature: JIS K2207-1996 (Universal Law)

[Resin composition]

[Evaluation sample preparation]

Use 40mm The resin composition described in the above Table 1 was subjected to extrusion processing at a thickness of 90 μm to prepare a film for evaluation. The extrusion processing was carried out under the conditions of a resin temperature of about 180 ° C and a processing speed of 10 m / min.

[evaluation method]

(1) Adhesion evaluation

According to JIS Z0237, the above-mentioned film for evaluation (width: 25 mm) is overlapped with an acrylic plate (width: 30 mm, length: 150 mm, thickness: 2 mm) which is an adherend, and is carried out by a manual roll (width: 45 mm, weight: 2 kg). Reciprocating pressure Samples for evaluation are available. This was subjected to aging according to the conditions described below, and then pulled at an angle of 300 mm/min and 180 degrees, and the adhesion was evaluated. In addition, in the evaluation, in order to reduce the influence of the measurement deviation, the measurement was performed five times, and the average value of the three measurement values excluded from the maximum value and the minimum value was used as the adhesion value. In addition, in order to compare the degree of adhesion promotion by aging, the value obtained by the following calculation formula is used as the adhesion enhancement rate (the lower the adhesion enhancement rate, the better the initial strength can be maintained).

Adhesion improvement rate (%) = [(adhesion after 60 ° C aging - initial adhesion) / initial adhesion] × 100

‧ Condition 1 (Initial Adhesion): The sample for evaluation to be laminated was allowed to stand in an environment of 23 ° C × 50% RH for 30 minutes, and then measured.

‧ Condition 2 (adhesion after aging at 60 ° C for 3 hours): The sample for evaluation evaluation was allowed to stand in an oven adjusted to 60 ° C for 3 hours. Subsequently, the mixture was allowed to stand in an environment of 23 ° C × 50% RH for 30 minutes, and then measured.

‧Condition 3 (adhesion after aging at 60 ° C, 7 days): The sample for evaluation evaluation was allowed to stand in an oven adjusted to 60 ° C for 7 days. Subsequently, the mixture was allowed to stand in an environment of 23 ° C × 50% RH for 30 minutes, and then measured.

(2) Pollution resistance assessment

The light is irradiated from the thickness direction of the acrylic sheet (30 mm × 2 mm surface) measured by the above adhesive force, and the haze of the surface of the acrylic sheet (the surface to which the adhesive layer is contacted) is used as a pollution index, and visually performed. Evaluation.

○: no pollution

△: slightly polluted

×: Serious pollution

[evaluation result]

The above evaluation results are summarized in Table 2.

The pressure-sensitive adhesive film of the present embodiment can obtain an effect of improving the initial adhesion and suppressing the adhesion enhancement rate as compared with EVA alone. In addition, the stain resistance to the adherend is excellent from the initial stage of adhesion to storage after high temperature storage. On the other hand, in the pressure-sensitive adhesive films described in Comparative Examples 5 to 6, the initial adhesion was improved as compared with the individual EVA, but the adhesion improvement rate was deteriorated.

The present application claims priority on the basis of Japanese Patent Application No. 2011-158626, filed on Jul. 20, 2011, the entire disclosure of which is incorporated herein.

Claims (8)

A pressure-sensitive adhesive film or sheet comprising an adhesive layer comprising: an ethylene/vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less; and according to JIS K2207-1996 An adhesion-promoting agent of a hydride of an alicyclic hydrocarbon resin having a softening temperature of 95 ° C or more and 130 ° C or less as measured by a ring and ball method; and a total amount of the ethylene/vinyl acetate copolymer and the above-mentioned adhesion-imparting agent When the amount is 100 parts by mass, the content of the above-mentioned adhesion-imparting agent is 0.1 part by mass or more and 1.0 part by mass or less. A pressure-sensitive adhesive film or sheet comprising an adhesive layer comprising: an ethylene/vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less; according to JIS K2207-1996 The adhesion-imparting agent of the hydride of the alicyclic hydrocarbon resin having a softening temperature of 95 ° C or more and 130 ° C or less as determined by the method; and a group selected from the group consisting of an antioxidant, an ultraviolet absorber, a light stabilizer, and an anti-adhesive agent When the total amount of the ethylene/vinyl acetate copolymer and the adhesion-imparting agent is 100 parts by mass, the content of the adhesion-imparting agent is 0.1% by mass. Parts or more and 1.0 part by mass or less. The pressure-sensitive adhesive film or sheet according to the first or second aspect of the patent application, wherein the adhesion enhancement rate (%) represented by the following formula (1) is 0% or more and 400% or less; the adhesion enhancement rate (%) = [(adhesion after aging at 60 ° C, 7 days - initial adhesion) / initial adhesion] × 100 (1). The pressure-sensitive adhesive film or sheet according to claim 1 or 2, wherein the ethylene/vinyl acetate copolymer has a melt flow rate (190 ° C, 2160 g load) measured according to JIS K7210-1999, 1 g/ 10 minutes or more and 50 g/10 minutes or less. A pressure-sensitive adhesive film or sheet according to claim 1 or 2, wherein the adhesive layer is formed on at least one side of the substrate. The pressure-sensitive adhesive film or sheet of claim 5, wherein the substrate comprises polyethylene or polypropylene. A surface protective film or sheet comprising the pressure-sensitive adhesive film or sheet of any one of claims 1 to 6. A method for protecting a surface of an article, which is a pressure-sensitive adhesive film or sheet according to any one of claims 1 to 6 for protecting a surface of an article.