JP5861186B2 - Manufacturing method of pressure-sensitive adhesive film for sealing fine holes - Google Patents

Description

  The present invention relates to an adhesive film for sealing fine holes.

In recent years, element parts having fine holes with a diameter of several tens of μm, such as ejection ports of ink jet recording heads, which are widely used in copying machines, printers, and other image forming apparatuses, are used in many fields. Metals, plastics, and ceramics are used as materials for these element parts.
In the distribution process, the micropores of these component parts are often covered with an adhesive film, and the adhesive film is peeled off when used in a product or immediately before use.
However, problems such as leakage of contents due to insufficient adhesive force of the adhesive film in the distribution process and adhesive layer residue generated when the adhesive film is peeled are often caused.
In order to cope with these problems, a polymer having an epoxy group and / or an oxetanyl group, and a substance capable of providing a substance that acts as a polymerization initiator of the reactive group by reacting with a liquid of the content, A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer is known (Patent Document 1).

  On the other hand, a surface protective film for a touch panel that has a self-adhesive layer on one side of the base film and can be detachably attached to the surface of the touch panel by this self-adhesive force. A silicone rubber pressure-sensitive adhesive layer having (ΣD3 to 10) of 1500 ppm or less is known (Patent Document 2).

  However, the conventional adhesive tape has a problem that when the adhesive force of the adhesive layer increases, the adhesive layer residue increases, and when the adhesive force decreases, the contents leak easily.

JP2009-149069 Japanese Patent No. 4366346

  The present invention has been made to cope with such a problem, and is suitable for sealing fine holes without contaminating the fine hole periphery of an element part having fine holes with an adhesive layer residue or the like. An object of the present invention is to provide a pressure-sensitive adhesive film for sealing micropores having an excellent adhesive force.

The pressure-sensitive adhesive film for sealing micropores of the present invention comprises a base film, a silicone pressure-sensitive adhesive layer, and a release film laminated in this order, directly or via other layers,
The silicone adhesive layer is a silicone compound having a polydimethylsiloxane skeleton, a silicone oil having a polydimethylsiloxane skeleton that does not contain an epoxy group and an oxetanyl group in the molecule , an organopolysiloxane resin , M units (R ₃ SiO _0.5 Where R is CH ₃ —, C ₆ H ₅ —, or C _n H _{2n + 1} — (where n is an integer of 6 or less) and an MQ resin composed of Q units (SiO ₂ ). An adhesive layer obtained by crosslinking the silicone composition with an electron beam,
The compounding amount of the organopolysiloxane resin is more than 15% by mass and less than 50% by mass with respect to the total amount of the silicone composition.
180 degree peeling adhesive force with respect to the glass plate of this adhesion layer is 0.1-2.0 N / 25mm, and measured value (eta) it by an ultra micro hardness meter is 40-80%, It is characterized by the above-mentioned.
In particular, the other layer is a surface treatment layer or a thin surface layer of the base film.

Moreover, a co-crosslinking agent is further blended in the silicone composition.
The base film and the release film are made of a polyethylene terephthalate film.

  In the present invention, a silicone composition containing an organopolysiloxane resin is used as an adhesive layer crosslinked with an electron beam, so that it has excellent anti-contamination properties and an optimum high sealing property for sealing micropores. .

  The base film used in the present invention is a film made of polyester, polyamide, polyolefin, polycarbonate, acrylic resin, fluororesin, or the like. Among these, a polyester film is preferable in terms of dimensional stability and economy. A particularly preferable base film is a polyethylene terephthalate film from the viewpoint of availability. These base films can be subjected to coloring processing, antibacterial processing, hard processing, antistatic processing, antifouling processing and antiglare processing. By using these processed films, adhesive for micropore sealing The properties as a film become more desirable. In addition, by applying surface treatment such as easy adhesion treatment, corona treatment, plasma treatment, primer treatment, etc., or by providing a surface thin layer having these surface treatment capabilities, the adhesion to the silicone adhesive layer is further strengthened. Can do. In addition, although the thickness of the said base film is not specifically limited, 5-500 micrometers, especially 10-200 micrometers are preferable at the point of handleability.

  Although the release film used in the present invention is not particularly limited, it is possible to use a long-chain alkyl group-containing resin or a commercially available release polyethylene terephthalate film in which a release layer made of a fluorine compound is laminated.

In the silicone adhesive layer, an organopolysiloxane resin is blended with a silicone compound having a polydimethylsiloxane skeleton.
The silicone compound is preferably a silicone compound that does not contain an epoxy group or an oxetanyl group in the molecule, and a polydimethylsiloxane skeleton silicone compound as a main component (70% by mass or more, more preferably 90% by mass or more, further preferably Is preferably included as 100% by mass). In particular, the silicone compound having a polydimethylsiloxane skeleton is preferably an uncrosslinked product having a number average molecular weight (Mn) of 50,000 to 500,000. The uncrosslinked Mn is more preferably 80,000 to 400,000, and more preferably 100,000 to 350,000.

  By using an uncrosslinked product of a silicone compound, solubility in a solvent and fluidity can be secured, and formation of an adhesive layer is facilitated. Moreover, since Mn of 50,000 or more of an uncrosslinked body improves crosslinkability, it is suitable. If the Mn of the uncrosslinked product is 500,000 or less, it is possible to suppress deterioration in operability during production such as the viscosity of the coating solution becoming too high in the production method described later. Therefore, it is a preferred embodiment to form an uncrosslinked layer of silicone compound and then perform crosslinking.

  As an uncrosslinked silicone compound satisfying the above contents, for example, a commercially available silicone oil can be used. When using silicone oil, it is preferable to use non-reactive dimethyl silicone oil which does not contain an epoxy group and oxetanyl group in the molecule among straight silicone oils. Thereby, the silicone compound after crosslinking has a polydimethylsiloxane skeleton. The methyl phenyl type silicone oil has a poor cross-linkability, and the reactive methyl hydrogen type silicone oil has poor storage stability, which may adversely affect quality and operability. If it is less than (more preferably less than 5% by mass), a silicone compound having no polydimethylsiloxane skeleton, such as methylphenyl type, methylhydrogen type, or various modified types, can be blended.

  The uncrosslinked silicone compound may contain a polyalkylalkenylsiloxane skeleton silicone compound as long as it is less than 30% by mass. Further, the amount of the silicone compound having a polyalkylalkenylsiloxane skeleton should be as small as possible. It is preferably made of only a polydimethylsiloxane skeleton silicone compound that does not contain a polyalkylalkenylsiloxane skeleton silicone compound.

  The adhesive layer in the present invention may contain a reinforcing agent such as silica as long as the effect of the present invention is not hindered, but it is particularly preferable that no reinforcing agent is contained.

In the pressure-sensitive adhesive layer of the present invention, an organopolysiloxane resin is blended with the uncrosslinked silicone compound.
As the organopolysiloxane resin, an MQ resin composed of M units (R ₃ SiO _0.5 ) and Q units (SiO ₂ ) can be preferably used. Here, R represents CH ₃ —, C ₆ H ₅ —, C _n H _{2n + 1} — (n is an integer of 6 or less) and the like. In particular, R is preferably CH ₃ — because it is a more stable group. MQ resins having a molar ratio of M units to Q units of 0.5 to 1.5 are preferred.
By blending MQ resin into the uncrosslinked silicone compound, the adhesive force of the adhesive layer is improved, and cross-linking with an electron beam eliminates contamination of the adherend.
When the silicone-based pressure-sensitive adhesive containing the organopolysiloxane resin is blended with the uncrosslinked silicone compound, the silicone is blended so that the blending amount as the organopolysiloxane resin is more than 15% by mass and less than 50% by mass. Formulate adhesive.

  The compounding amount of the organopolysiloxane resin is more than 15% by mass and less than 50% by mass, preferably 20% by mass, based on the total amount of the silicone composition, ie, the total amount of the silicone compound and the organopolysiloxane resin. It is 40 mass% or less. When it is 15% by mass or less, the adhesive strength is reduced, and when it is 50% by mass or more, adhesive residue is generated.

A co-crosslinking agent can be blended in the silicone adhesive layer. The co-crosslinking agent can increase the adhesive strength with the polyester film serving as the base film.
Examples of the co-crosslinking agent include (meth) acrylic acid derivatives and allyl derivatives. Among them, derivatives having 2 or more, particularly 3 or more unsaturated bonds are preferable. These compounds are widely used as rubber co-crosslinking agents, and examples include esters of polyhydric alcohol and (meth) acrylic acid, allyl esters of polycarboxylic acid, triallyl isocyanurate, triallyl cyanurate, and the like. .

The ester of the polyhydric alcohol and (meth) acrylic acid is an ester compound obtained by esterifying two or more alcoholic hydroxyl groups of a polyhydric alcohol having two or more alcoholic hydroxyl groups with (meth) acrylic acid. Specifically, for example, ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Neopentyl glycol di (meth) acrylate, 2,2'-bis [4- (meth) acryloxydiethoxyphenyl] propane, glycerol di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, tetramethylolmethane di (meth) acrylate, tetramethylolmethanetri (meth) acrylate, Examples include tramethylol tetra (meth) acrylate, dimer diol di (meth) acrylate, and the like, and particularly compounds containing three or more (meth) acryloyl groups are preferable. In addition, although said compound illustrated each single ester compound of acrylic acid and methacrylic acid, the form of mixed ester of acrylic acid and methacrylic acid may be sufficient.
Examples of the allyl ester of polyvalent carboxylic acid include phthalic acid diarylate, trimellitic acid diarylate, and pyromellitic acid tetraarylate.

Any one of the above-mentioned co-crosslinking agents may be used alone, or two or more thereof may be used in combination. The co-crosslinking agent used in the present invention is not limited to the above exemplary compounds.
0.2-20 mass% is preferable with respect to the whole silicone composition, and, as for the compounding quantity of the said co-crosslinking agent, 0.5-10 mass% is more preferable.

The silicone composition is crosslinked with an electron beam to obtain an adhesive layer.
It is thought that when the silicone composition is irradiated with an electron beam, hydrogen is extracted from the methyl group of polydimethylsiloxane and a crosslinking reaction occurs between adjacent silicone compounds from which hydrogen is extracted from the methyl group. Yes. Therefore, in the crosslinking method using an electron beam, it is not necessary to add an additive such as a peroxide for radical generation or a crosslinking catalyst to the silicone compound. For this reason, the contamination of the adherend due to the residue of these additives is suppressed, and it is not necessary to consider the pot life after blending the crosslinking catalyst, etc., so that the crosslinking is completed efficiently in a short time. There are merits such as higher.

  The electron beam cross-linking method is preferable because of the availability of an irradiation apparatus (EB irradiation apparatus). The electron beam irradiation dose in the EB irradiation apparatus is in the range of 50 to 300 kGy, preferably 100 to 200 kGy. By setting the electron beam irradiation amount to 50 kGy or more, the crosslinking reaction of the silicone compound can be promoted, and the adhesive residue on the adherend can be reduced and the repairability can be improved when re-peeling. On the other hand, by making the electron beam irradiation amount 300 kGy or less, it is possible to suppress a decrease in sealing performance due to excessive progress of the crosslinking reaction.

180 degree peeling adhesive force with respect to the glass plate of the adhesion layer in the adhesive film for micropore sealing obtained by electron beam crosslinking is 0.1 to 2.0 N / 25 mm, preferably 0.12 to 1.6 N / 25 mm. . If it is less than 0.1 N / 25 mm, the adhesive strength decreases, and if it exceeds 2.0 N / 25 mm, the adhesive layer residue increases.
Further, the measured value ηit measured by an ultra micro hardness meter is 40 to 80%. If ηit is less than 40%, the adhesive layer residue tends to increase, and if it exceeds 80%, the sealing performance may be deteriorated.
The ranges of the above-mentioned adhesive strength and ηit can be achieved by setting the range of the pressure-sensitive adhesive layer and the electron beam cross-linking conditions within the above ranges.

  The adhesive strength can be measured by a 180 degree peeling method with respect to a glass plate according to JIS Z0237. As the glass, a float glass having a thickness of 3 mm and a width of 30 mm is used. The sample has a width of 25 mm, and is attached to the glass by reciprocating twice at a speed of about 29 mm / second using a 2 kg roller. The peeling speed is 300 mm / min, and after leaving for 24 hours in an atmosphere of 23 ° C. after the sticking, a tensile test is performed in an atmosphere of 23 ° C., and the maximum tensile strength is defined as adhesive strength (N / 25 mm).

Further, the measured value ηit by the ultra-micro hardness meter is a value measured by the following method.
(1) Sample preparation The sample is cut into approximately 2cm squares, and the opposite side of the measurement surface on a glass plate of 1mm or more is used as an adhesive such as a baseless acrylic double-sided adhesive (thickness 25μm) or cyanoacrylate. And fix. After standing for 30 minutes or more after fixing, the separator on the measurement surface is peeled off and measured.
(2) Measuring device As a measuring device, Shimadzu Corporation dynamic microhardness meter DUH-211 is used.
(3) Measurement conditions Measurement conditions are as follows.
(I) Setting Test mode Load-unloading test Indenter 115 degree triangular pyramid indenter
Indenter elastic modulus: 1.140E + 006 N / mm ²
Indenter Poisson's ratio: 0.07
Soft sample measurement Yes (ii) Conditions Test force 0.50 mN (or 0.70 mN)
Load speed 0.0150 mN / sec Load holding time 2 seconds Unloading holding time 5 seconds (4) Data n number Average value of each 3 Note that the measured values are machine compliance correction (Cf) and projection area function correction (Ap) In addition, the values after correction (As) of the contact area function are described. The details of these correction principles are described in the instruction manual for DUH-211.
(5) Meaning of measured value ηit The measured value ηit measured by the ultra-micro hardness meter has the following meaning.
Mechanical work by pushing, the mechanical work W _total by pushing, part of it is consumed as the plastic deformation amount W _plast. At the time of unloading of the test force, the remaining part is _released as the elastic deformation work W _elast , so ηit is defined as W _elast / W _total (%).

The pressure-sensitive adhesive film for sealing micropores of the present invention is prepared by dissolving or dispersing the above-mentioned uncrosslinked silicone compound and MQ resin in a solvent, and adding an adhesion improver as necessary to prepare a coating solution. It is obtained by applying an electron beam cross-linking treatment under the above conditions after coating on a substrate film by a coating method.
Uncrosslinked silicone oil and MQ resin are well soluble in aromatic hydrocarbons such as toluene, and are preferably dissolved in these solvents and applied by a coating method.
As the coating method, various coating methods such as reverse coating method, gravure coating method, rod coating method, bar coating method, Mayer bar coating method, die coating method, spray coating method and the like can be used.
When an uncrosslinked silicone oil is used, a compound plasticizing step by kneading or the like necessary for dissolving a conventional millable type silicone rubber compound in a solvent is unnecessary. In addition, the obtained coating solution has good storage stability, and does not cause a thickening phenomenon such as gelation, which is often seen when preparing a solution of a silicone rubber compound. Furthermore, since the production | generation of the foreign material by the silicone rubber compound not melt | dissolving which may generate | occur | produce in the solutionization of a silicone rubber compound is suppressed, there exists a merit that a coating liquid with high clarity is obtained.
An uncrosslinked adhesive layer is laminated on the base film by drying after coating on the base film.
The said drying can be set from the material of a base film, thickness, the drying furnace length of an installation, etc. In many cases, when the temperature is rapidly applied to the vicinity of the boiling point of the solvent, a phenomenon called bumping occurs, and appearance defects such as bubbles are likely to occur. Therefore, it is preferable to gradually raise the temperature.

It is preferable to laminate the release film on the surface of the non-crosslinked adhesive layer laminated on the base film and perform electron beam crosslinking treatment from the release film.
The pressure-sensitive adhesive film for sealing micropores after the electron beam crosslinking treatment is wound into a roll.
The fine hole sealing pressure-sensitive adhesive film after the electron beam cross-linking treatment is used after being slit or / and cut into dimensions according to the application.

  The adhesive film for sealing micropores of the present invention preferably has a base film thickness of 20 to 200 μm, an adhesive layer thickness of 10 to 60 μm, and a release film thickness of 10 to 100 μm.

  The pressure-sensitive adhesive film for sealing micropores of the present invention is suitable as a pressure-sensitive adhesive film for sealing micropores in element parts in which micropores with a diameter of several tens of μm are provided on a base material such as metal, plastic, and ceramics. Can be used.

Example 1
(1) Preparation of pressure-sensitive adhesive layer-forming coating solution A non-crosslinked polydimethylsiloxane skeleton having substantially no reinforcing agent such as silica and having a number average molecular weight of 240,000 (measured by GPC method, converted to polystyrene) 67 parts by mass of silicone oil , which is a reactive silicone compound, was dissolved in toluene. This is a silicone compound containing 60% by mass of MQ resin in solids (Toray Dow Corning, SD4580PSA, solids 60% by mass), 56 parts by mass, and trimethylolpropane trimethacrylate (expressed as TMP in Table 1). ) 1.3 parts by mass was added and dissolved uniformly to obtain a coating liquid having a solid content of 30% by mass. In Table 1, the silicone compound is the total amount of the non-reactive silicone oil and the silicone compound excluding the MQ resin in the silicone-based pressure-sensitive adhesive containing MQ resin.

(2) Formation of pressure-sensitive adhesive layer and adhesion of release film The above coating solution is supplied to a roll coater and dried on an easy-adhesion-treated surface of a polyethylene terephthalate film (thickness 38 μm) subjected to easy-adhesion treatment on one side. The coating was applied so that the subsequent thickness was 45 μm, and subsequently introduced into an oven and dried at 90 ° C. A laminate in which an uncrosslinked silicone adhesive layer was formed on one side on a base film was obtained.
Next, a pressure roller (pressure 30 N / cm) was placed on the surface of the pressure-sensitive adhesive layer while a polyethylene terephthalate film (thickness 75 μm) on which a release layer made of a fluorine-based compound was laminated so that the release layer and the pressure-sensitive adhesive layer were in contact with each other. ² ) A pressure-release release film was attached.

(3) Electron beam irradiation The above film laminate is continuously introduced into an electron beam irradiation apparatus, and the adhesive layer is crosslinked by irradiating an electron beam with an energy of 200 KV and 150 kGy from the release film side. The pressure-sensitive adhesive film for sealing fine holes provided with the pressure-sensitive adhesive layer was wound into a roll.
Table 1 shows the structure of the obtained pressure-sensitive adhesive film for sealing fine holes and the electron beam irradiation conditions. In Table 1, the release film was omitted. In addition, the blending ratio of the silicone compound and the MQ resin was displayed by omitting the decimal part.

(4) Evaluation The peelable film is peeled off from the adhesive film for sealing micropores wound up in a roll shape, and the 180 degree peel adhesive strength, the measurement with an ultra-micro hardness meter, the contamination property, the adhesive layer residue property, the sealing property Evaluated. The 180 degree peel adhesion and the measurement with an ultra-micro hardness meter were performed by the above-described methods.

  For contamination, a polyethylene terephthalate film having a thickness of 100 μm is placed on the adherend surface of a glass plate, and the adhesive surface of the sample is bonded thereon. Thereafter, the sample was peeled off after standing at 60 ° C. for 48 hours, and the presence or absence of contamination of the surrounding glass surface on which polyethylene terephthalate was placed was visually observed. The case where the glass surface was clean was marked with ○, and the case where it was contaminated was marked with ×.

The adhesive layer residue property was implemented in the same manner as the above-mentioned contamination property, and the presence or absence of the adhesive layer residue on the glass surface was visually observed. The case where the glass surface was clean was marked with ◯, and the case where the adhesive layer remained was marked with ×.
The sealing property was evaluated based on the presence or absence of liquid leakage when the sample was bonded to the micropores of a container having micropores with a diameter of 50 μm on the entire bottom and the container was filled with purified water. The case where liquid leakage occurred was marked as x, and the case where liquid leakage was not observed was marked as ◯.
The results are shown in Table 2.

Examples 2-9, Comparative Examples 1-6
A microporous sealing film was prepared in the same manner as in Example 1 except that the configuration of the microporous sealing film and the electron beam irradiation conditions were as shown in Table 1. The obtained adhesive film for sealing micropores was evaluated in the same manner as in Example 1. The results are shown in Table 2. In addition, Comparative Example 3 uses 221 parts by mass of a polyorganosiloxane having an alkenyl group instead of a silicone compound having a dimethylsiloxane skeleton (manufactured by Toray Dow Corning Co., Ltd., SD7226, solid content 30% by mass), and a platinum catalyst. (Toray Dow Corning Co., Ltd., NC-25) was added to adjust the coating solution and crosslinked by heating at 120 ° C. during coating. Comparative Examples 4 and 5 are commercially available acrylics It is an adhesive film having a resin as an adhesive layer.

  The pressure-sensitive adhesive film for sealing micropores of the present invention is excellent in adhesive force and can be used as a pressure-sensitive adhesive film for sealing various micropores because no residue of the pressure-sensitive adhesive layer is observed.

Claims (4)

A base film, a silicone pressure-sensitive adhesive layer, and a release film are laminated in this order, directly or via other layers, and a method for producing a pressure-sensitive adhesive film for sealing micropores,
180 degree peeling adhesive force with respect to the glass plate of the silicone adhesive layer is 0.1 to 2.0 N / 25 mm, and a measured value ηit by an ultra micro hardness meter is 40 to 80%,
The silicone adhesive layer is prepared by adding M units (R ₃ SiO _0.5 , where R is CH ₃ —, C ₆ H ₅ —, or C to silicone oil having a polydimethylsiloxane skeleton that does not contain an epoxy group and oxetanyl group in the molecule. _n H _{2n + 1} − (where n represents an integer of 6 or less) and a Q composition (SiO ₂ ), and a silicone composition in which the MQ resin is blended. A method for producing a pressure-sensitive adhesive film for sealing micropores, comprising cross-linking a composition that exceeds 15% by mass and less than 50% by mass with an electron beam with respect to the total amount of the silicone composition . The method for producing a pressure-sensitive adhesive film for sealing micropores according to claim 1, wherein the other layer is a surface treatment layer or a surface thin layer of the base film. The method for producing a pressure-sensitive adhesive film for sealing micropores according to claim 1 or 2, wherein a co-crosslinking agent is further blended in the silicone composition. The method for producing an adhesive film for sealing micropores according to any one of claims 1 to 3, wherein the base film and the release film are made of a polyethylene terephthalate film.