JP2015044959A - Adhesive film for protecting glass substrate surface and adhesive used for adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film used for protecting the surface of the glass substrate of a cellular phone, etc., and an adhesive for forming the adhesive layer of the adhesive film.SOLUTION: The adhesive layer provided in a film substrate includes a (meta) acrylic based polymer using a (meta) acrylic based monomer having a 1-18C alkyl group as a principal component, as an adhesive component and at least one kind of polyether compounds having a 2-8C repeating structural unit in a repeating structural unit of alkylene oxide. In this case, the polyether compound is preferably included by 5-70 pts.wt. to the (meta) acrylic based polymer of 100 pts.wt. and is preferably polypropylene glycol, poly oxypropylene glyceryl ether or a polyalkylene glycol derivative, having an average molecular weight of 250-4000.

Description

  The present invention relates to a protective adhesive film (a glass substrate surface protecting adhesive film) used for preventing scratches and dirt on the surface of a glass substrate such as a mobile phone or a display. The present invention also relates to an adhesive for producing this protective adhesive film.

So far, silicone adhesives have been used as adhesive films for protecting the surface of glass substrates such as mobile phones and displays, from the viewpoint of air release and wettability at the time of bonding. Agents are expensive and alternatives are sought. A low-priced urethane-based fine pressure-sensitive adhesive is also used as an alternative to the silicone pressure-sensitive adhesive, but such a urethane-based fine pressure-sensitive adhesive has a problem that the weather resistance is not good.
In addition, in Patent Document 1 below, as an alternative to an expensive silicone adhesive, an adhesive layer in which a fatty acid ester is added as a plasticizer to an inexpensive acrylic adhesive is provided, and workability such as wettability and air release is provided. An improved protective adhesive film is disclosed.

  However, the protective pressure-sensitive adhesive film described in Patent Document 1 in which a fatty acid ester is added as a plasticizer to the pressure-sensitive adhesive layer has a large surface resistance value of the pressure-sensitive adhesive layer, so that static electricity is generated and dust easily adheres to the surface. There was a problem.

JP 2010-209324 A

The present invention solves the above-mentioned problems in the prior art, and is a protective adhesive film that is less expensive than a silicone adhesive and has excellent air bleedability, wettability, and dust adhesion prevention properties when affixed to a glass substrate surface. It is also an object of the present invention to provide an adhesive suitable for the production of such a protective adhesive film.
In order to solve the above problems, the present inventors have conducted various studies on the properties of the adhesive layer of the protective adhesive film, and as a result, when using an adhesive in which a polyether compound having a specific structure is added as a plasticizer, Not only can the air release and wettability be improved when sticking to the glass substrate surface, but also the surface resistance value of the adhesive layer can be reduced, thereby attaching a protective adhesive film to the glass substrate surface. The present invention has been completed by finding that it is possible to effectively prevent the attachment of dust.

  The pressure-sensitive adhesive film of the present invention that can solve the above-mentioned problems is used for the purpose of protecting the surface of a glass substrate such as a mobile phone or a display, and is a film substrate that constitutes the protective pressure-sensitive adhesive film. At least one surface is provided with a pressure-sensitive adhesive layer formed by coating a pressure-sensitive adhesive, and the pressure-sensitive adhesive has an acrylic monomer having an alkyl group having 1 to 18 carbon atoms as a pressure-sensitive adhesive component, and And / or at least one polyether compound containing a (meth) acrylic polymer mainly composed of a methacrylic monomer and having a repeating structural unit having 2 to 8 carbon atoms in the repeating structural unit of alkylene oxide. It is characterized by including.

  In the pressure-sensitive adhesive film having the above-mentioned characteristics, the polyether compound is contained in an amount of 5 to 70 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. It is what.

  Further, the present invention is the pressure-sensitive adhesive film having the above characteristics, wherein the polyether compound is selected from the group consisting of polypropylene glycol, polyoxypropylene glyceryl ether, and polyalkylene glycol derivatives having an average molecular weight of 250 to 4000. It is at least one kind or more. Note that the term “average molecular weight” used in the present specification indicates a weight average molecular weight unless otherwise specified.

Furthermore, the present invention provides the pressure-sensitive adhesive film having the above characteristics, wherein the pressure-sensitive adhesive layer has an adhesive strength of 0.001 to 5.0 N / 25 mm, and the pressure-sensitive adhesive layer has a surface resistance value of 10 ¹² Ω. It is also characterized by being less than.

  Moreover, this invention is an adhesive for manufacturing the adhesive film used by sticking for the purpose of surface protection of a glass substrate, and the said adhesive is a C1-C18 alkyl as an adhesive component. A repeating structure containing a (meth) acrylic polymer having an acrylic monomer and / or methacrylic monomer as a main component, and having 2 to 8 carbon atoms in the repeating structural unit of alkylene oxide as a plasticizer It contains at least one kind of polyether compound having a unit.

  In the pressure-sensitive adhesive having the characteristics described above, the polyether compound may be contained in an amount of 5 to 70 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. It is what.

  Further, the present invention is the pressure-sensitive adhesive having the above characteristics, wherein the polyether compound is selected from the group consisting of polypropylene glycol, polyoxypropylene glyceryl ether, and polyalkylene glycol derivatives having an average molecular weight of 250 to 4000. It is also characterized by at least one or more.

  The pressure-sensitive adhesive film of the present invention is excellent in air bleedability, wettability and dust adhesion prevention when being attached to the surface of a glass substrate. The said adhesive film can be implement | achieved.

It is a figure which shows the layer structure of the adhesive film which concerns on embodiment of this invention, In this adhesive film, the release liner 3 has the objective of protecting the surface of the adhesive layer 2 provided in the single side | surface of the film base material 1. FIG. Are stacked.

Hereinafter, the component of the adhesive of this invention used when forming the adhesive layer in the adhesive film of this invention is demonstrated.
First, the pressure-sensitive adhesive component in the pressure-sensitive adhesive of the present invention is a (meth) acrylic polymer mainly composed of an acrylic monomer having an alkyl group having 1 to 18 carbon atoms and / or a methacrylic monomer. Both have excellent transparency and durability.
Examples of the monomer constituting the (meth) acrylic polymer particularly preferable in the present invention include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylate-n-propyl, ( Examples include isopropyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylexyl (meth) acrylate, and these may be used alone or in combination of two or more.

The plasticizer contained in the pressure-sensitive adhesive of the present invention is a polyether compound having 2 to 8 carbon atoms in the repeating unit of alkylene oxide, and such a polyether is included in the pressure-sensitive adhesive of the present invention. It is sufficient that at least one compound is contained, and the polyether compound having such a chemical structure can be added to and used in almost all solvent-type pressure-sensitive adhesives. Since this compound contains an alkylene oxide unit structure in the molecule, the surface resistance value of the pressure-sensitive adhesive layer formed by coating the pressure-sensitive adhesive of the present invention was added with a conventional fatty acid ester. It is lower than the surface resistance value of the pressure-sensitive adhesive layer, and exhibits excellent dust and dirt adhesion prevention performance.
In addition, the pressure-sensitive adhesive of the present invention to which a polyether compound having a specific chemical structure is added as a plasticizer is a point of performance such as air detachability, temporary fixability, wettability, workability, removability, and workability. Is excellent, and shows performance equal to or higher than that of a conventional pressure-sensitive adhesive in which a fatty acid ester is added to an acrylic pressure-sensitive adhesive.

In the present invention, various commercially available products having the above-mentioned chemical structure can be used as the above-mentioned polyether compound. Particularly suitable plasticizers are polypropylene glycol and polyoxypropylene glyceryl ether having an average molecular weight of 250 to 4000. A polyalkylene glycol derivative. Examples of such polypropylene glycol and polyoxypropylene glyceryl ether include Uniol (registered trademark) manufactured by NOF Corporation. Examples of the polyalkylene glycol derivative include compounds in which one or both of OH groups present at both ends of polyethylene glycol or polypropylene glycol are substituted with an alkyl group. For example, Unilube (registered trademark) manufactured by NOF Corporation, Surfynol (trade name) manufactured by Nissin Chemical Industry Co., Ltd. can be used. The latter compound is a compound obtained by adding ethylene oxide to a compound having a symmetrical structure in which (CH ₃ ) ₂ CHCH ₂ C (CH ₃ ) (OH) groups are bonded to both sides of an acetylene group.
In addition, in this invention, said polyether compound is 5-70 weight part with respect to 100 weight part of (meth) acrylic-type polymers, Preferably it is 10-50 weight part, More preferably, it is a ratio of 15-40 weight part. Blended.

  Moreover, in the adhesive film of this invention, the adhesive layer formed by coating the said adhesive is laminated | stacked on the single side | surface or both surfaces of the film base material (support film), and it is hereafter shown in FIG. The present invention will be described by showing specific examples of the adhesive film of the present invention.

  The pressure-sensitive adhesive film of the present invention illustrated in FIG. 1 is composed of a film base 1 and a pressure-sensitive adhesive layer 2 provided on one side of the film base 1, and the material of the film base 1 is particularly limited. However, a polyethylene terephthalate (PET) film is preferable from the viewpoint of transparency and adhesiveness with the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer. The thickness of the film substrate 1 constituting the adhesive film of the present invention is generally about 12 to 100 μm, preferably about 16 to 50 μm, and particularly preferably about 25 to 38 μm. Under the present circumstances, the surface by the side of the adhesive layer 2 of the film base material 1 may be given the corona treatment for the purpose of improving the adhesive force with the adhesive layer 2.

  In the present invention, as shown in FIG. 1, the release liner 3 is generally laminated on the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive layer 2, and the release liner 3 is separated from the surface. A release-treated PET film coated with a mold is common. Moreover, it is preferable that the antistatic layer is formed in the surface side of the film base material 1 by coating with an antistatic agent.

  In order to form the pressure-sensitive adhesive layer 2 in the present invention, the above-mentioned pressure-sensitive adhesive component and plasticizer are blended at a predetermined ratio to prepare the pressure-sensitive adhesive of the present invention, which is dissolved in a suitable solvent to form a pressure-sensitive adhesive solution. The solution is formed on the substrate by various coating methods. At this time, the coating method of the pressure-sensitive adhesive solution is not particularly limited, and various known coating methods can be used. For example, a die coater, a comma coater, a knife coater, a gravure coater, a roll coater, or the like can be used. In the present invention, the thickness of the pressure-sensitive adhesive layer 2 is not particularly limited, but is applied so that the film thickness after drying is 5 to 100 μm, preferably 10 to 25 μm.

The pressure-sensitive adhesive film of the present invention having the pressure-sensitive adhesive layer 2 formed by coating the pressure-sensitive adhesive to which the above polyethers are added as a plasticizer has a pressure-sensitive adhesive force of the pressure-sensitive adhesive layer 2 of 0.001 to 5.0 N. / 25 mm, preferably 0.001 to 3.0 N / 25 mm, and suitable as an adhesive film used for the purpose of protecting the surface of a glass substrate such as a cellular phone (low adhesive strength) )have. At this time, if the adhesive strength of the adhesive layer 2 is less than 0.001 N / 25 mm, the adhesive strength is weak and the protective adhesive film may be easily peeled off. It is not preferable because the force is strong and it is difficult to peel easily.
Further, the pressure-sensitive adhesive layer 2 in the present invention has a surface resistance value of less than 10 ¹² Ω due to a polyether compound containing an alkylene oxide unit added as a plasticizer, and therefore when a fatty acid ester is used as a plasticizer (> 10 Compared to ¹² Ω), dust is less likely to adhere. The antistatic function for preventing the adsorption of dust to the film generally starts to show an effect when the surface resistance value is less than 10 ¹² Ω, and preferably less than 10 ¹¹ Ω.
Hereinafter, although the specific example of this invention is shown, this invention is not limited to this.

Example 1: Production example of pressure-sensitive adhesive film for protecting a glass substrate surface of the present invention First, as a pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer, a pressure-sensitive acrylic adhesive (having an alkyl group having 1 to 18 carbon atoms). (Adhesive with (meth) acrylic monomer as main component and (meth) acrylic polymer as main component and adhesive strength in the range of 0.05 to 0.5 N / 25 mm to SUS adherend) Three types of commercially available plasticizers, Uniol D1000 (average molecular weight 1000), Surfynol 485 (molecular weight 798), and Unilube MB7 (average molecular weight 700) are added to this adhesive. did. Each addition amount (in Table 1 shows parts by weight relative to 100 parts by weight of the acrylic polymer) is added to each of the three types of pressure-sensitive adhesives of the present invention (coating liquid for forming a pressure-sensitive adhesive layer). Obtained. As a film substrate, a commercially available PET film having a thickness of 50 μm was prepared.
And each said coating liquid was coated so that the adhesive layer thickness after drying might be set to 20 micrometers, and the adhesive layer was formed by performing drying, and the protective adhesive film of this invention was produced.

  Similarly, as a comparative example, two types of commercially available adhesives (product name: CT3020 and CT3088, manufactured by DIC Corporation) to which a fatty acid ester was added were prepared. Two types of fatty acid ester, isopropyl myristate [IPM-R] (molecular weight 270) and isopropyl palmitate [IPP-R] (molecular weight 298), were added as plasticizers to prepare an acrylic adhesive as in the examples. did. This compound is added to the acrylic pressure-sensitive adhesive in the amount shown in Table 1, and coated on a 50 μm-thick PET film so that the thickness of the pressure-sensitive adhesive layer after drying is 20 μm. To prepare a protective adhesive film. Further, the above-mentioned acrylic light-adhesive pressure-sensitive adhesive without adding a fatty acid ester is coated on the PET film so that the thickness of the pressure-sensitive adhesive layer after drying is 20 μm, followed by drying to obtain a protective pressure-sensitive adhesive film. Produced.

With respect to the protective adhesive film of the present invention obtained above and the protective adhesive film of the comparative example, the removability, the air escape time, and the surface resistance value were evaluated. Each evaluation method is as follows.
(Removability)
Cut the measurement sample (protective adhesive film) into a size of 25mm x 150mm, attach it to the adherend (glass plate), press it back and forth with a 2kg rubber roller, store it at 80 ° C for 240 hours, and store at 60 ° C and 95% RH After storage for × 240 hours and weather resistance test for 500 hours (using a sunshine weather meter), it was evaluated whether or not the protective adhesive film could be removed again.
(Air out time)
The sample to be measured (protective adhesive film) is cut into a size of 80 mm x 80 mm and brought into contact with the surface of a 4-inch square glass plate in an atmosphere at a temperature of 23 ° C and a relative humidity of 50%. The time required for this was measured.
(Surface resistance value)
The surface resistance value was measured using a super insulation meter (SM-8200 manufactured by Toa DKK Corporation) as a measuring device.
The results obtained from the above measurements are shown in Table 1 below.

  As shown in Table 1 above, the pressure-sensitive adhesive film of the present invention having a pressure-sensitive adhesive layer containing a specific polyether compound as a plasticizer is shorter than the conventional pressure-sensitive adhesive film not containing a plasticizer, And it was confirmed that the surface resistance value of an adhesive layer is small. In addition, the adhesive film of the present invention has a lower surface resistance value of the adhesive layer than that of a conventional adhesive film to which a fatty acid ester is added, and also protects the surface of a glass substrate such as a mobile phone in terms of adhesive strength. It was confirmed that the film had an adhesive force suitable as an adhesive film used for the purpose.

  The pressure-sensitive adhesive film produced using the pressure-sensitive adhesive of the present invention is suitable as a film for preventing scratches and dirt on the surface of a glass substrate such as a mobile phone or a display, and compared with a pressure-sensitive adhesive film coated with a silicone pressure-sensitive adhesive. And has the advantage of being inexpensive.

DESCRIPTION OF SYMBOLS 1 Film base material 2 Adhesive layer 3 Release liner (release processing film)

Claims (7)

  A pressure-sensitive adhesive film that is used by being attached for the purpose of protecting the surface of a glass substrate, and is formed by coating a pressure-sensitive adhesive on at least one surface of a film substrate constituting the pressure-sensitive adhesive film. A layer is provided, and the pressure-sensitive adhesive contains, as a pressure-sensitive adhesive component, a (meth) acrylic polymer containing an acrylic monomer having an alkyl group having 1 to 18 carbon atoms and / or a methacrylic monomer as a main component, And the adhesive film for glass substrate surface protection containing at least 1 sort (s) of the polyether compound which has a repeating structural unit whose carbon number in the repeating structural unit of an alkylene oxide is 2-8.   The said polyether compound is contained in the ratio of 5-70 weight part with respect to 100 weight part of said (meth) acrylic-type polymers, The adhesive film for glass substrate surface protection of Claim 1 characterized by the above-mentioned.   3. The polyether compound according to claim 1, wherein the polyether compound is at least one selected from the group consisting of polypropylene glycol having an average molecular weight of 250 to 4000, polyoxypropylene glyceryl ether, and polyalkylene glycol derivative. The adhesive film for surface protection of a glass substrate as described in 2. The pressure-sensitive adhesive force of the pressure-sensitive adhesive layer is 0.001 to 5.0 N / 25 mm, and the surface resistance value of the pressure-sensitive adhesive layer is less than 10 ¹² Ω. The adhesive film for glass substrate surface protection of 1 item | term.   A pressure-sensitive adhesive for producing a protective pressure-sensitive adhesive film used for the purpose of protecting the surface of a glass substrate, wherein the pressure-sensitive adhesive component is an acrylic monomer having an alkyl group having 1 to 18 carbon atoms and / or It contains a (meth) acrylic polymer mainly composed of a methacrylic monomer and at least one polyether compound having a repeating structural unit having 2 to 8 carbon atoms in the repeating structural unit of alkylene oxide. A protective adhesive film adhesive.   The pressure-sensitive adhesive for protective adhesive film according to claim 5, wherein the polyether compound is contained in a proportion of 5 to 70 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.   7. The polyether compound is at least one selected from the group consisting of polypropylene glycol, polyoxypropylene glyceryl ether, and polyalkylene glycol derivatives having an average molecular weight of 250 to 4000. The adhesive for protective adhesive films as described in 2.

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