KR102006365B1 - Pressure-sensitive adhesive film or sheet, surface protecting film or sheet, and method for using pressure-sensitive adhesive film or sheet to protect surface of article - Google Patents

Abstract

The pressure-sensitive adhesive film or sheet of the present invention comprises 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 a tackifier having a hydrogenation rate of 50% or more and less than 90% do.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure sensitive adhesive film or sheet, a surface protective film or sheet, and a pressure sensitive adhesive film or sheet used for protecting the surface of an article. PRESSURE-SENSITIVE ADHESIVE FILM OR SHEET TO PROTECT SURFACE OF ARTICLE}

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

BACKGROUND ART [0002] Adhesive films or sheets have been used as surface protective films for protecting surfaces of products from adherence, contamination, scratches and the like of dust.

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

In the adhesive film or sheet, the adhesive strength between the adhesive layer and the adherend is required to be moderately strong. The suitable strength is a strength that does not cause self-peeling, light vibration, or dropping off by itself, and when peeled off, it can be smoothly peeled off without leaving an adhesive layer on the surface of the adherend.

A pressure-sensitive adhesive film or sheet that satisfies such a demand property includes a film or sheet made of an ethylene-vinyl acetate copolymer.

In Patent Document 1 (Japanese Unexamined Patent Publication (Kokai) No. 6-145616), a pressure-sensitive adhesive layer is prepared by mixing 100 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 7% by weight and a melt flow rate of 2 to 20 g / And 0.5 to 2 parts by weight of a tackifier is added to the surface protective film. This surface protective film exhibits an appropriate initial adhesive strength, and even if a heat treatment, particularly UV irradiation, is performed, the adhesive force does not rise remarkably, and it is said that there is no contamination to the protective material.

Patent Document 2 (Japanese Unexamined Patent Publication No. 2008-255233) discloses a pressure-sensitive adhesive sheet comprising a polypropylene resin base layer (A) and a pressure-sensitive adhesive layer (B) comprising an ethylene / vinyl acetate copolymer having a vinyl acetate unit content of 7.5 to 50 wt% (B) are described.

This adhesive film or sheet has a high interlaminar bond strength between the base layer and the adhesive layer and the adhesive layer has an appropriate adhesive strength to the surface of the object to be adhered and the base layer has a softening temperature, The optical characteristics such as thermal characteristics, tensile strength, impact resistance, mechanical properties such as stiffness, haze, gloss, light transmittance, and the like are excellent. Moreover, there is little occurrence of fish eye, the surface is smooth, .

On the other hand, Patent Document 3 (Japanese Patent Laid-Open No. 2010-171419) discloses a resin composition comprising (A) an ethylene / vinyl acetate copolymer resin and (B) a hydride of a C9 aromatic hydrocarbon resin having high compatibility with (A) , And the hydrogenation rate of the hydride of the C9 type aromatic hydrocarbon resin (B) is 40% or more.

This solar cell encapsulation material sheet is excellent in workability in processing such as melting and processing, has high transparency, excellent in light resistance and heat resistance, and high in stability.

Japanese Patent Application Laid-Open No. 6-145616 Japanese Unexamined Patent Application Publication No. 2008-255233 Japanese Patent Application Laid-Open No. 2010-171419

The film made of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 7 wt% described in Patent Document 1 (Japanese Unexamined Patent Publication (Kokai) No. 6-145616) did not have sufficient adhesion to an adherend. Therefore, in order to obtain a desired adhesive force, it has been necessary to add a large amount of a tackifier.

However, when a large amount of the tackifier is contained in the adhesive layer, the adhesive layer tends to remain on the surface of the adherend when the adhesive film is peeled off. That is, the stain resistance to the adherend is lowered.

In addition, there is a desire to reduce the use amount of the tackifier since the tackifier is relatively expensive and there is a fear of supply uneasiness accompanied by an increase in demand worldwide.

Also, the ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 7.5 to 50 wt% described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2008-255233) did not have sufficient adhesion to the adherend. In addition, there was a strong tendency that the adhesive strength increased gradually with time from the initial adhesion strength.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a pressure-sensitive adhesive film or a pressure-sensitive adhesive film having a desired adhesive force and reduced use amount of a tackifier when the pressure-sensitive adhesive layer is pressed against an adherend under a room temperature condition, Sheet.

According to the present invention,

An ethylene / vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less,

A tackifier having a hydrogenation rate within a range of 50% or more and less than 90%

Sensitive adhesive film or sheet having a pressure-sensitive adhesive film or sheet.

According to the present invention,

There is provided a surface protecting film or sheet comprising the pressure-sensitive adhesive film or sheet.

According to the present invention, an ethylene / vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less and a tackifier having a hydrogenation rate of 50% or more and less than 90% A pressure-sensitive adhesive film or sheet having an adhesive force can be obtained.

Further, according to the present invention,

There is provided a method of using the pressure-sensitive adhesive film or sheet for protecting the surface of an article.

According to the present invention, it is possible to provide a pressure-sensitive adhesive film or sheet having a desired adhesive force while reducing the amount of the tackifier used.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments.

Hereinafter, an embodiment of the present invention will be described.

The pressure-sensitive adhesive film or sheet in the present embodiment is preferably a pressure-sensitive adhesive film or sheet 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 a tackifier having a hydrogenation rate of 50% Layer.

The adhesive strength between the adhesive layer and the adherend in the present invention is not an adhesive layer to be adhered and adhered to an adherend under a heating condition equal to or higher than the melting point of an adhesive such as a hot melt adhesive, The peel strength between layers when an adhesive layer is adhered to an adherend under pressure is shown.

(Adhesive layer)

First, the components of the pressure-sensitive adhesive film constituting the pressure-sensitive adhesive film or sheet in the present embodiment will be described.

&Quot; Ethylene-vinyl acetate copolymer "

The ethylene-vinyl acetate copolymer (EVA), which is an essential component of the present invention, is a copolymer of ethylene and vinyl acetate.

The ethylene-vinyl acetate copolymer of the present invention has a unit content of vinyl acetate component 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, particularly preferably 9% % Or less. When the vinyl acetate content is within the above range, a pressure-sensitive adhesive film or sheet having an appropriate initial adhesive strength is obtained.

If the vinyl acetate content is not less than the lower limit value, a pressure-sensitive adhesive film or sheet having an even better initial adhesion can be obtained. On the other hand, when the content of vinyl acetate is not more than the upper limit, a pressure-sensitive adhesive film or sheet in which the adhesion with time is suppressed is obtained. That is, the stain resistance to an adherend is further improved.

The ethylene-vinyl acetate copolymer of the present embodiment is not particularly limited, but preferably has a melt flow rate (MFR) (according to JIS K7210-1999) at 190 ° C under a load of 2160 g of preferably 1 g / 10 min Or more and 50 g / 10 min or less, particularly preferably 2 g / 10 min or more and 30 g / 10 min or less.

When the MFR is at least the lower limit value, the smoothness and the initial adhesion of the film are further improved. On the other hand, if the MFR is less than the upper limit value, the blocking property of the film and the stain resistance to the protective substrate are further improved because the low molecular weight component is reduced.

&Quot; Tackifier "

The tackifier, which is an essential component of the present invention, is blended to improve the adhesive strength of the adhesive layer.

Examples of the tackifier include hydrogenated products of petroleum resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic-aromatic copolymerized hydrocarbon resins, and alicyclic hydrocarbon resins; Hydrogenated products of terpene resins such as pinene resin, coumaroneindene resin and terpene phenol resin; Hydrogenated products of polymerized rosin-based resins; Hydrogenated products of (alkyl) phenolic resins; A hydrogenated product of a xylene-based resin; Hydrogenated products of styrene-based resins, and the like. Among these, hydrogenated products of petroleum resins are preferable, and hydrogenated products of alicyclic hydrocarbon resins (also referred to as alicyclic saturated hydrocarbon resins) are particularly preferable.

These tackifiers may contain an olefin resin.

As the hydrogenation product of a petroleum-based resins, vinyl toluene, indene, α- methyl styrene, such as C ₈ ~C hydrogenation product of a resin containing as a main component a vinyl aromatic hydrocarbon, such as _10.

Examples of the hydrogenated product of the terpene resin include hydrogenated products such as an? -Pinene polymer, a? -Pinene polymer, a dipentene polymer, and a terpene / phenol copolymer.

Examples of the hydrogenated product of the polymerized rosin-based resin include hydrogenated rosin, glycerin ester of hydrogenated rosin or a polymer thereof, and pentaerythritol ester of hydrogenated rosin or a polymer thereof.

Examples of the hydrogenated product of the styrene-based resin include hydrogenated products such as homopolymers of styrene-based monomers, styrene-olefin copolymers, vinyltoluene-alpha-methylstyrene copolymer and the like.

The tackifier of the present invention has a hydrogenation rate within a range of 50% or more and less than 90%, preferably 55% or more and 80% or less, particularly preferably 60% or more and 70% or less .

When the hydrogenation rate is within the above range, a pressure-sensitive adhesive film or sheet having a desired adhesive force in a smaller amount can be obtained, so that the use amount of the tackifier can be reduced.

The hydrogenation rate can be measured by the NMR measurement method described in Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2010-171419). Specifically, it is calculated from the following equation (1) from the H-spectrum area of an aromatic ring which appears near 7 ppm of 1 H-NMR of the tackifier.

Hydrogenation rate = {1- (spectral area of hydrogenation product of tackifier / spectral area of hydrogenation tackifier)} 100 (%) (One)

The tackifier is not particularly limited, but the softening temperature measured in accordance with the JIS K2207-1996 ring method is preferably 80 占 폚 or higher, and more preferably 85 占 폚 or higher. When the softening temperature is not lower than the lower limit value, the obtained pressure-sensitive adhesive film or sheet obtains further excellent initial adhesion and excellent handling properties.

The tackifier is not particularly limited, but the softening temperature measured according to the JIS K2207-1996 ring method is preferably 150 占 폚 or lower, more preferably 140 占 폚 or lower. When the softening temperature is not more than the upper limit value, the adhesion of the obtained pressure-sensitive adhesive film or sheet can be further suppressed.

The content of the tackifier in the present embodiment is not particularly limited. When the total amount of the ethylene-vinyl acetate copolymer and the tackifier is 100 parts by mass, the content is preferably at least 0.1 part by mass More preferably 0.3 part by mass or more, particularly preferably 0.5 part by mass or more. When the content of the tackifier is lower than or equal to the above lower limit value, a pressure-sensitive adhesive film or sheet having an even better initial tackiness can be obtained.

The content of the tackifier is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, still more preferably 2.2 parts by mass or less, and particularly preferably 1.5 parts by mass or less. When the content of the tackifier is not more than the upper limit, a pressure-sensitive adhesive film or sheet having a more excellent balance between the inhibition of the adhesion of the adhesive with time and the stain resistance to the adherend can be obtained.

"Other additives"

The adhesive layer in the present embodiment may further contain an additive usually used in the field of polymers such as an antioxidant, an ultraviolet absorber, a light stabilizer, and an anti-blocking agent to such an extent that the properties of the adhesive layer are not impaired .

(Production method of pressure-sensitive adhesive film or sheet)

The pressure-sensitive adhesive film or sheet in the present embodiment is obtained, for example, by molding the ethylene-vinyl acetate copolymer and the resin composition containing the tackifier in a single-layer film or sheet form. In this case, the obtained single layer film or sheet corresponds to the adhesive layer of the present embodiment. It is also possible to obtain an adhesive layer on at least one surface of a substrate using the resin composition.

Usually, a method of forming an adhesive layer on at least one surface of a substrate using the latter resin composition is used.

"materials"

When the pressure-sensitive adhesive layer of the resin composition is formed on at least one surface of the substrate, the substrate to be used is not particularly limited, but it is preferable to use one or more thermoplastic resins such as polyester, polyamide and polyolefin , Stretched or non-stretched thermoplastic resin films or sheets.

Examples of the polyolefin include a block-type or random-type propylene-based polymer having a polypropylene or ethylene component as a copolymerization component; Ethylene-based polymers such as low-density polyethylene, high-density polyethylene, linear low-density or ultra-low density polyethylene; Ethylene-propylene copolymer, and the like.

Examples of the substrate include paper; Metal foil; Nonwoven fabrics are also used.

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

When a substrate comprising a polyolefin is used, a film or sheet having good interlayer adhesiveness between the adhesive layer and the substrate and having excellent transparency can be obtained.

When a thermoplastic resin film is used for the base material, for the purpose of preventing deterioration, for example, an antioxidant; Ultraviolet absorber; Light stabilizers such as hindered amine light stabilizers; An antistatic agent; Additives such as fillers and pigments such as carbon black, calcium oxide, magnesium oxide, silica, zinc oxide and titanium oxide may be further added to the thermoplastic resin as a base material if necessary.

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

&Quot; Method of preparing resin composition "

The resin composition used for forming the pressure-sensitive adhesive layer of the present embodiment can be obtained, for example, by simultaneous or sequential dry blending or melt blending of the ethylene / vinyl acetate copolymer, the tackifier, Loses.

For the dry blend, various mixers such as a Henschel mixer and a tumbler mixer can be used.

In the case of melt-blending, a kneading device such as a single-screw or twin-screw extruder, a banbury mixer, a roll or a kneader can be used. For example, Knead.

&Quot; Method of forming adhesive layer on substrate "

The method for forming the pressure-sensitive adhesive layer of the resin composition of the present embodiment from a substrate can be, for example, a solution coating method in which a solution or a hot melt of a resin composition is applied to a substrate; A method of transferring and transferring the formed pressure-sensitive adhesive layer on a separator substrate in accordance with a solution coating method; A hot melt coating method in which a resin composition is extruded and formed on a substrate; A method in which a substrate and a resin composition are co-extruded and formed into a multilayer of two or more layers; A method in which a resin composition is extruded and laminated on a substrate in a single layer; A method of extrusion laminating the adhesive layer and the resin composition into two layers; A method of thermal lamination of a pressure-sensitive adhesive layer and a supporting substrate forming material such as a film or a laminate layer; And the like.

Among them, a method of co-extruding a resin composition together with a substrate made of a thermoplastic resin into a multilayer of two or more layers by an inflation method or a T-die (T-die) method is preferable.

In the present embodiment, the thickness of the pressure-sensitive adhesive layer to be formed on the base material is appropriately determined depending on the adhesive force and the like, but it is generally preferably 1 m or more and 250 m or less, more preferably 5 m or more and 100 m or less.

In the case of a single layer film or sheet having no substrate, it is preferably 5 占 퐉 or more and 300 占 퐉 or less, more preferably 10 占 퐉 or more and 200 占 퐉 or less.

The pressure-sensitive adhesive film or sheet in this embodiment is attached only by pressure without being actively heated so that the pressure-sensitive adhesive layer is opposed to the surface of the rigid (rigid) adherend. When it is unnecessary, it is easily peeled off by a hand so that no contaminants remain on the surface of the adherend. As the adherend, for example, a product surface protection such as a synthetic resin plate, a veneer sheet, a metal plate, and a coated steel sheet can be given.

It can also be used for protection of the window glass surface, for the burning of automobiles, for surface protection at the time of solder deposition of a printed board, and the like.

A liquid crystal panel plate as a component of a liquid crystal display, a plasma display, and an organic thin film EL device; Precision electronic parts such as a reflection plate, a retardation plate, a prism sheet, a light guide plate, a polarizing plate, a plasma display panel plate, an organic phosphor thin film, a transparent electrode, a flexible printed substrate and a rigid printed substrate. The pressure-sensitive adhesive film or sheet in the present embodiment is particularly suitably used as these surface-protecting films or sheets.

Another embodiment of the present invention can provide a method of using the pressure-sensitive adhesive film or sheet for protecting the surface of an article. Examples of the article to be subjected to surface protection include the adherend described above.

Although the embodiments of the present invention have been described above, they are examples of the present invention, and various configurations other than the above may be adopted.

Example

Hereinafter, the present invention will be described by way of examples and comparative examples, but the present invention is not limited thereto.

[Raw material]

In the Examples and Comparative Examples, the following materials were used.

EVA 1: ethylene-vinyl acetate copolymer (MFR = 9 g / 10 min, ethylene content = 90 mass%, vinyl acetate content = 10 mass%

Adhesion imparting agent 1: Alicyclic saturated hydrocarbon resin (Alkon M-90, produced by Arakawa Chemical Industries, Ltd., softening temperature 90 캜, hydrogenation rate of 60% or more and 70% or less)

Adhesion imparting agent 2: Alicyclic saturated hydrocarbon resin (Alkon M-100 made by Arakawa Chemical Industries, Ltd., softening temperature 100 캜, hydrogenation rate 60% or more and 70% or less)

Adhesion imparting agent 3: Alicyclic saturated hydrocarbon resin (Alkon M-115 made by Arakawa Chemical Industries, Ltd., softening temperature 115 캜, hydrogenation rate 60% or more and 70% or less)

Adhesion imparting agent 4: Alicyclic saturated hydrocarbon resin (Alkon M-135 made by Arakawa Chemical Industries, Ltd., softening temperature: 135 캜, hydrogenation rate: 60% or more and 70% or less)

Adhesion imparting agent 5: Alicyclic saturated hydrocarbon resin (Alcon P-100 manufactured by Arakawa Chemical Industries, Ltd., softening temperature 100 캜, hydrogenation rate of 90% or more)

MFR: JIS K7210-1999 (190 占 폚, 2160 g load)

Softening temperature: JIS K2207-1996 (ring method)

[Evaluation sample production]

A resin composition having a blend ratio (parts by mass) shown in Table 1 was extruded to a thickness of 90 占 퐉 using a 40 mm? T die molding machine (manufactured by Nakatani Kika Co., Ltd.) to produce an evaluation film. The extrusion processing was carried out under the conditions of a resin temperature of about 180 캜 and a processing speed of 10 m / min.

[Assessment Methods]

(1) Evaluation of cohesion

(25 mm width) and an acrylic plate (30 mm wide, 150 mm long, and 2 mm thick) serving as a substrate were superimposed on each other and subjected to two round trips (45 mm in width and 2 kg in weight) And a sample for evaluation was obtained. This was allowed to stand for 30 minutes in an atmosphere of 23 ° C × 50% RH, peeled off at an pulling speed of 300 mm / min and 180 °, and the adhesive strength was evaluated. In this evaluation, in order to lessen the influence of the measurement deviation, the measurement was carried out five times each, and a value obtained by averaging three measurement values excluding the maximum value and the minimum value was used as the adhesive force.

[Evaluation results]

Table 1 summarizes the above evaluation results.

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2011-249318, filed on November 15, 2011, the disclosure of which is incorporated herein in its entirety.

Claims (8)

An ethylene / vinyl acetate copolymer having a vinyl acetate content of 7.5% by mass or more and 20% by mass or less,
A tackifier having a hydrogenation rate of 50% or more and less than 90%,
It is provided with an adhesive layer comprising a,
The pressure sensitive adhesive film or sheet whose softening temperature measured based on JISK2207-1996 ring and ball method of the said tackifier is 100 degreeC or more and 150 degrees C or less. The method of claim 1,
When the total amount of the ethylene-vinyl acetate copolymer and the tackifier is 100 parts by mass,
Wherein the content of the tackifier is 0.1 parts by mass or more and 5.0 parts by mass or less. 3. The method according to claim 1 or 2,
The pressure-sensitive adhesive film or sheet wherein the tackifier comprises a hydrogenated product of an alicyclic hydrocarbon resin. 3. The method according to claim 1 or 2,
Wherein the melt flow rate (190 占 폚, 2160 g load) of the ethylene-vinyl acetate copolymer measured in accordance with JIS K7210-1999 is 1 g / 10 min or more and 50 g / 10 min or less. 3. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive layer is formed on at least one surface of the substrate. The method of claim 5, wherein
Wherein the substrate comprises polyethylene or polypropylene. The surface protection film or sheet containing the pressure-sensitive adhesive film or sheet of Claim 1 or 2. The method of using the pressure sensitive adhesive film or sheet of Claim 1 or 2 in order to protect the surface of an article.