JP7724090B2 - Method for manufacturing adhesive sheet, and adhesive sheet - Google Patents

Description

The present invention relates to a method for manufacturing an adhesive sheet, and an adhesive sheet.

Adhesive sheets have an adhesive layer containing adhesives formed on a substrate, and are used for fixing parts in various industrial fields such as office equipment, home appliances, and automobiles. They are also used in a wide range of other applications, such as labels for displaying various types of information.

For example, Patent Document 1 discloses a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed by irradiating an adhesive composition containing (A) a (meth)acrylic acid ester polymer whose main monomer is a (meth)acrylic acid alkyl ester having an alkyl group of 1 to 18 carbon atoms, (B) an unsaturated group-containing phosphorus-based compound having an unsaturated group in the molecule, and (C) a photopolymerization initiator, with active energy rays.

Attempts are being made to control the adhesive properties of adhesive sheets by subjecting them to various treatments.

For example, Patent Document 2 discloses a method for reducing the adhesiveness of the winding surface of an adhesive tape roll by supplying a precursor containing an organic polyfunctional silane to a plasma flow, directing the precursor-enriched plasma flow to the winding surface, and covering the winding surface with a SiO _x coating.

JP 2010-229367 A Special table 2019-531360 publication

It is desirable for the adhesive sheet described above to have a strong bond between the substrate and the adhesive layer so that the adhesive layer does not peel off from the substrate during use. However, Patent Documents 1 and 2 do not take this into consideration.

The combination of the substrate and adhesive layer is important to ensure adhesion between them, so there are restrictions on the selection of materials for the substrate and adhesive layer.

In this regard, attempts have been made to provide an intermediate layer between the substrate and the adhesive layer, or to apply a surface treatment to the surface of the substrate, but there is still room for improvement in terms of improving the adhesion between the substrate and the adhesive layer.

The present invention was made in consideration of these circumstances, and aims to provide a method for manufacturing an adhesive sheet that has high adhesion between the substrate and the adhesive layer and does not peel off from the substrate during use, and an adhesive sheet.

As a result of extensive research into achieving the above-mentioned objectives, the inventors discovered a method for manufacturing an adhesive sheet that includes the steps of: applying a coating liquid containing an organometallic compound onto the surface of a substrate to form an organometallic compound layer having a thickness of 0.01 to 1 μm; irradiating the organometallic compound layer with energy to convert at least a portion of the organometallic compound in the organometallic compound layer into a metal oxide to form a metal oxide layer that is then further hydrophilized; and forming an adhesive layer on the surface of the metal oxide layer, thereby completing the present invention.

In other words, the present invention is as follows:

(1)
The method for producing a pressure-sensitive adhesive sheet includes the steps of: applying a coating liquid containing an organometallic compound onto the surface of a substrate to form an organometallic compound layer having a thickness of 0.01 to 1 μm; irradiating the organometallic compound layer with energy to convert at least a portion of the organometallic compound in the organometallic compound layer into a metal oxide, thereby forming a metal oxide layer and further hydrophilizing the metal oxide layer; and forming an adhesive layer on the surface of the metal oxide layer.
(2)
The method for producing a semiconductor device according to (1), wherein the energy irradiation is carried out in an air atmosphere.
(3)
The method for producing a film according to (1) or (2), wherein the energy irradiation is carried out under atmospheric pressure.
(4)
The method according to any one of (1) to (3), wherein the metal oxide layer has a water contact angle of 50° or less on the surface.
(5)
The method according to any one of (1) to (4), wherein the organometallic compound is at least one selected from the group consisting of organosilicon compounds, organoaluminum compounds, organotitanium compounds, organovanadium compounds, organozirconium compounds, organoniobium compounds, organomolybdenum compounds, organohafnium compounds, organotantalum compounds, organotungsten compounds, organocerium compounds, organonickel compounds, organochromium compounds, organocobalt compounds, organotin compounds, and organocopper compounds.
(6)
The pressure-sensitive adhesive sheet includes a substrate, a metal oxide layer formed on the surface of the substrate, and a pressure-sensitive adhesive layer formed on the surface of the metal oxide layer opposite the substrate, wherein the metal oxide layer is an organometallic compound layer having a thickness of 0.01 to 1 μm obtained by applying a coating liquid containing an organometallic compound, and the organometallic compound layer is subjected to a hydrophilization treatment by irradiating the organometallic compound layer with energy.

The present invention provides a method for producing an adhesive sheet that has high adhesion between the substrate and the adhesive layer, and that does not peel off from the substrate during use, as well as an adhesive sheet.

FIG. 1 is a conceptual diagram illustrating an example of a manufacturing method according to this embodiment, in which FIG. 1( a) is a cross-sectional schematic diagram of a laminate produced by the manufacturing method according to this embodiment, FIG. 1( b) is a cross-sectional schematic diagram of a treated laminate obtained by subjecting the laminate of FIG. 1( a) to a hydrophilic treatment, and FIG. 1( c) is a cross-sectional schematic diagram of an example of a pressure-sensitive adhesive sheet obtained by the manufacturing method according to this embodiment. FIG. 2 is a cross-sectional view of a pressure-sensitive adhesive sheet with a release substrate obtained by the production method according to this embodiment.

The following describes in detail the form for carrying out the present invention (hereinafter simply referred to as the "present embodiment"). The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out with appropriate modifications within the scope of its gist.

In the drawings, identical elements will be given the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

Figure 1 is a conceptual diagram illustrating an example of a manufacturing method according to this embodiment. Figure 1(a) is a cross-sectional schematic diagram of a laminate produced by the manufacturing method according to this embodiment. Figure 1(b) is a cross-sectional schematic diagram of a laminate after a hydrophilization treatment has been performed on the laminate of Figure 1(a). Figure 1(c) is a cross-sectional schematic diagram of an example of a pressure-sensitive adhesive sheet obtained by the manufacturing method according to this embodiment.

The method for producing the pressure-sensitive adhesive sheet 1 according to this embodiment includes the steps of:
(1) a step of applying a coating liquid containing an organometallic compound onto the surface of a substrate 10 to form an organometallic compound layer 21 having a thickness of 0.01 to 1 μm;
(2) a step of irradiating the organometallic compound layer 21 with energy to convert at least a part of the organometallic compound in the organometallic compound layer 21 into a metal oxide to form a metal oxide layer 20, and further making the metal oxide layer 20 hydrophilic;
(3) forming an adhesive layer 30 on the surface of the metal oxide layer 20;
The pressure-sensitive adhesive sheet 1 obtained by the manufacturing method according to this embodiment includes at least a substrate 10, a metal oxide layer 20, and a pressure-sensitive adhesive layer 30 (see FIG. 1(c)).

According to the manufacturing method of this embodiment, by performing step (2), not only is the organometallic compound layer 21 converted into a metal oxide layer 20, but its surface can also be made hydrophilic. This allows the metal oxide layer 20 to function as an easy-adhesion layer, and also provides the metal oxide layer 20 with the function of inhibiting the interlayer migration of low-molecular-weight substances.

Each process is explained below.

<Step (1)>

(1) First, a coating liquid containing an organometallic compound, which is a precursor of a metal oxide, is applied to the surface of the substrate 10 to form an organometallic compound layer 21 having a thickness of 0.01 to 1 μm.

The material of the substrate 10 is not particularly limited, and any material commonly used for a pressure-sensitive adhesive sheet 1 can be used. Specific examples of the substrate 10 include resin, paper, nonwoven fabric, metal, or composite sheets of these.

Resins that can be used for the substrate 10 include, for example, polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers; polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; acetate resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polystyrene, and polyvinyl chloride. Among these, polyolefins and polyesters, which have low adhesion to the adhesive layer 30, are preferred, and polypropylene, polyethylene, and polyethylene terephthalate are even more preferred, from the perspective of better demonstrating the effects of this embodiment. It is preferable that no easy-adhesion layer be interposed between the substrate 10 and the organometallic compound layer 21.

These may be used alone or in combination of two or more types.

Examples of paper that can be used as the substrate 10 include kraft paper (acidic or neutral), fine paper, medium-quality paper, lightly coated paper, coated paper, liner, semi-glassine paper, glassine paper, one-sided glazed paper, parchment paper, and white paperboard.

The substrate 10 may also contain additives such as colorants such as dyes and pigments, antioxidants such as anilides and phenols, UV absorbers such as benzophenones and benzotriazoles, light stabilizers, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, crosslinking agents, catalysts, plasticizers, leveling agents, thickeners, softeners, dispersants, etc.

The substrate 10 may be a single layer, or may be composed of two or more layers. When it is composed of two or more layers, two or more of the above-mentioned types may be used in combination, or it may have a known functional layer in addition to the above-mentioned layers. When the substrate 10 is composed of two or more layers, it preferably does not include an easy-adhesion layer.

The dimensions and shape of the substrate 10 are not particularly limited, and suitable dimensions and shapes can be adopted depending on the application. For example, the thickness of the substrate 10 is preferably 20 to 150 μm. The lower limit of this thickness is more preferably 25 μm or more, even more preferably 30 μm or more, and even more preferably 35 μm or more. The upper limit of this thickness is more preferably 80 μm or less, even more preferably 70 μm or less, and even more preferably 60 μm or less.

When manufacturing the pressure-sensitive adhesive sheet 1 according to this embodiment, the substrate 10 is preferably a long substrate, as this allows for continuous supply of the substrate 10, which offers significant advantages in mass production. The longitudinal length of such a long substrate is typically 10 to 10,000 m, and preferably 100 to 3,000 m. The lateral length of the long substrate is typically 0.1 to 5 m, and preferably 0.2 to 2 m. In this specification, the term "long substrate" includes both "a long substrate wound into a roll" and "a substrate unwound from a roll of long substrate."

The organometallic compound used should be one that changes into a metal oxide when exposed to energy. It is also preferable that the organometallic compound dissolves in a solvent and can be applied as a solution. Because solution application is a wet process coating that does not use a vacuum, it offers advantages over dry process coating in terms of film formation cost and film formation speed, improving mass productivity.

Suitable examples of organometallic compounds include at least one selected from the group consisting of organosilicon compounds, organoaluminum compounds, organotitanium compounds, organovanadium compounds, organozirconium compounds, organoniobium compounds, organomolybdenum compounds, organohafnium compounds, organotantalum compounds, organotungsten compounds, organocerium compounds, organonickel compounds, organochromium compounds, organocobalt compounds, organotin compounds, and organocopper compounds.

Of these organometallic compounds, organosilicon compounds and organotitanium compounds are more preferred.

The organosilicon compound may be at least one selected from the group consisting of organopolysiloxanes such as polydimethylsiloxane and polymethylphenylsiloxane; silicon alkoxides such as silicon tetramethoxide, silicon tetraethoxide, silicon tert-butoxide, silicon tetra-n-butoxide, and silicon tetraisopropoxide; and hydrolysis products thereof.

Examples of organic titanium compounds include at least one selected from the group consisting of titanium acetylacetone complexes such as titanium acetylacetonate, titanyl acetylacetonate, and titanium diisopropoxide; and titanium alkoxides such as titanium tetraethoxide, titanium tetra-n-butoxide, and titanium tetraisopropoxide.

These may be used alone or in combination of two or more types.

Specific examples of combinations of two or more compounds include an organosilicon compound and an organotitanium compound; an organosilicon compound and an organocopper compound; an organotitanium compound and an organocopper compound; an organosilicon compound, an organotitanium compound and an organocopper compound; etc.

The coating liquid containing the organometallic compound can contain at least the organometallic compound described above and a solvent. The solvent is not particularly limited, and a known solvent can be selected depending on the type of organometallic compound.

An organic solvent can be used as the solvent. Specific examples of solvents include alcohols, acetone, ethyl acetate, acetic acid, tetrahydrofuran (THF), diethyl ether (DME), methyl ethyl ketone (MEK), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), toluene, carbon tetrachloride, and n-hexane.

Examples of alcohols include monoalcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, and phenethyl alcohol; diols such as ethylene glycol, propylene glycol, and butanediol; triols such as triethylene glycol; and polyols such as polyethylene glycol.

The concentration of the organometallic compound in the coating solution is not particularly limited, but is preferably 0.1 to 10% by mass. The lower limit is more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. The upper limit is more preferably 5% by mass or less, and even more preferably 3% by mass or less. By setting the concentration of the organometallic compound within this range, it is possible to more accurately control the thickness of the organometallic compound layer 21 and to suppress defects in the appearance of the coating film, such as repelling and streaks.

The coating solution containing the organometallic compound can be applied by known methods. For example, it can be formed by applying the solution to the surface of the substrate 10 using a coating machine such as a bar coater, die coater, gravure coater, roll coater, blade coater, air knife coater, or size press coater. Of these, methods using a bar coater, die coater, or gravure coater are preferred from the standpoint of ease in forming a coating film.

After application, further processes such as heat drying may be carried out as necessary.

According to this embodiment, step (1) can be performed continuously in a roll-to-roll manner. Specifically, the substrate 10 (long substrate) wound around a core is unwound while being applied with appropriate tension in the transport direction, and passed through a coater to apply a coating liquid containing an organometallic compound to the surface of the substrate 10. After passing through the coater and forming a coating film, the substrate 10 is transported to a drying oven, where the coating film is dried to form an organometallic compound layer 21, after which the substrate 10 is wound around the core.

The thickness of the organometallic compound layer 21 thus formed is 0.01 to 1 μm. If the thickness is less than 0.01 μm, sufficient adhesion between the substrate and the adhesive layer cannot be achieved. Furthermore, if the thickness exceeds 1 μm, the organometallic compound layer may not be sufficiently converted to metal oxide by the energy irradiation in step (2) (e.g., the surface of the organometallic compound layer 21 that contacts the substrate 10 may not be sufficiently modified), resulting in insufficient adhesion between the substrate 10 and the metal oxide layer 20. For example, if the thickness of the organometallic compound layer 21 exceeds 1 μm, even if the irradiated surface can be modified to some extent by energy irradiation, the opposite surface (back surface) may not be sufficiently modified, and a large amount of organometallic compound may remain. Generally, organometallic compounds have low cohesion, and adhesion tends to decrease due to cohesive failure of the organometallic compound. Therefore, a thickness exceeding 1 μm will not be sufficient (however, the effect of this embodiment is not limited to this).

From this perspective, the lower limit of the thickness of the organometallic compound layer 21 is preferably 0.03 μm or more, and more preferably 0.05 μm or more. The upper limit of this thickness is preferably 0.5 μm or less, and more preferably 0.2 μm or less.

<Step (2)>

Next, (2) energy is irradiated onto the organometallic compound layer 21, converting at least a portion of the organometallic compound in the organometallic compound layer 21 into metal oxide to form the metal oxide layer 20, which is then further rendered hydrophilic.

By performing step (2), a highly hydrophilic metal oxide layer 20 can be formed on the surface of the substrate 10. This makes the surface of the metal oxide layer 20 hydrophilic, thereby increasing adhesion to the adhesive layer 30. The reason why the metal oxide layer 20 becomes hydrophilic is unclear, but it is presumed to be for the following reason. First, by irradiating the organometallic compound layer 21 with energy, at least a portion of the organometallic compounds in the organometallic compound layer 21 are converted to form the metal oxide layer 20. Then, water molecules present in the atmosphere, etc., are added to the surface of the metal oxide layer 20. As a result, hydroxyl groups (-OH) are added to the surface of the metal oxide layer 20, making the surface of the metal oxide layer 20 hydrophilic, thereby firmly adhering the adhesive layer 30 and the metal oxide layer 20.

Furthermore, the presence of the metal oxide layer 20 between the substrate 10 and the adhesive layer 30 also provides a barrier function that prevents low molecular weight compounds (e.g., plasticizers, oils, etc.) contained in the substrate 10 and/or adhesive layer 30 from migrating to the adhesive layer 30 and/or substrate 10.

Furthermore, the presence of hydroxyl groups (-OH) on the surface of the metal oxide layer 20 allows them to actively bond with crosslinking agents (e.g., isocyanate-based crosslinking agents) or silane coupling agents contained in adhesives, etc., which is expected to also improve adhesion (however, the effects of this embodiment are not limited to these).

Methods for quantitatively evaluating the hydroxyl groups (-OH) on the surface of the metal oxide layer 20 include X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermal desorption spectroscopy (TPD), and labeling agent methods.

In this regard, when using a substrate 10 that has low adhesion to the adhesive layer 30 (e.g., a hydrophobic substrate 10), conventional attempts have been made to improve adhesion to the adhesive layer 30 by performing surface treatments such as corona treatment to add functional groups to the treated surface, making the surface hydrophilic. However, such corona treatments only improve hydrophilicity by adding hydrophilic functional groups similar to those of ambient gases (air, nitrogen, oxygen, carbon dioxide, etc.), and therefore have limitations on the improvement in hydrophilicity. For example, when corona treatment is performed on a polypropylene substrate, the amount of hydrophilic functional groups added to the substrate surface is small, resulting in insufficient hydrophilicity of the treated substrate surface.

The metal oxide is the same metal species as the organometallic compound described above. Specific examples of the transformation from an organometallic compound to a metal oxide include:
In the case of an organic silicon compound, it changes to silicon oxide ( _SiO2 , etc.),
In the case of an organoaluminum compound, it will change to aluminum oxide (Al ₂ O ₃ etc.),
In the case of an organic titanium compound, it will change to titanium oxide ( _TiO2 , etc.),
In the case of organic _vanadium compounds, they are converted into _vanadium oxides ( _V2O5 , _VO2 , _V2O3 , _{V6O13 ,} etc.),
In the case of an organic zirconium compound, it changes to zirconium oxide ( _ZrO2 , etc.),
In the case of an organic niobium compound, it changes to niobium oxide (Nb ₂ O ₅ , NbO ₂ , Nb ₂ O _{3 ,} etc.),
In the case of organic molybdenum compounds, they are converted into molybdenum oxides (MoO ₂ , MoO ₃ , Mo ₂ O _5, etc.),
In the case of organic hafnium compounds, they are converted into hafnium oxide ( _HfO2 , etc.),
In the case of an organic tantalum compound, it changes to tantalum oxide (Ta ₂ O ₅ , etc.),
In the case of an organic tungsten compound, it changes to tungsten oxide ( _WO3 , etc.),
In the case of organic cerium compounds, they are converted into cerium oxide (Ce ₂ O ₃ , CeO ₂ , etc.),
In the case of organic nickel compounds, they change to nickel oxide (NiO, etc.),
In the case of organic chromium compounds, they are converted into _chromium oxides (CrO, _Cr2O3 , _CrO3 , etc.),
In the case of organic cobalt compounds, they are converted into cobalt oxide (CoO, etc.),
In the case of organotin compounds, they are converted into tin oxide ( _SnO2 , etc.),
In the case of an organic copper compound, it is converted into copper oxide (Cu ₂ O, CuO, etc.).

Among metal oxides, silicon oxide, aluminum oxide, titanium oxide, nickel oxide, molybdenum oxide, chromium oxide, cobalt oxide, copper oxide, etc. are preferred. Of these, silicon oxide and titanium oxide are more preferred from the standpoints of transparency and hydrophilicity.

The metal oxide contained in the metal oxide layer 20 may be a single metal oxide or a composite metal containing two or more metal oxides.

As an example, a case will be described in which an organometallic compound layer 21 is formed using polydialkylsiloxane (—OSiR ₂ —; R represents an alkyl group) as the organosilicon compound, and then a silicon oxide metal oxide layer 20 is formed. First, when the organometallic compound layer 21 is irradiated with energy equivalent to the band gap energy (approximately 8.2 eV) of silicon oxide (O═Si═O), bonds such as Si—O, Si—C, and Si—H are broken, decomposing the polydialkylsiloxane. Furthermore, the polydialkylsiloxane bonds with oxygen in the air (oxidation), converting it to silicon oxide (O═Si═O), forming the metal oxide layer 20. Furthermore, one of the oxygen atoms (O) of the silicon oxide reacts with trace amounts of water molecules (H ₂ O) and hydrogen radicals (·OH) present in the air, generating hydrophilic hydroxyl groups (—OH) on the surface of the metal oxide layer 20. For example, when energy is irradiated onto the surface of the silicon oxide layer (metal oxide layer 20), some of the bridging oxygen atoms are released, creating oxygen defects. The aforementioned water molecules and the like dissociate and adsorb to these oxygen defects, generating surface hydroxyl groups. It is believed that this mechanism contributes to the development or improvement of hydrophilicity in the silicon oxide layer, which is the metal oxide layer 20 (however, the effects of this embodiment are not limited to these).

As another example, a case will be described in which an organometallic compound layer 21 is formed using titanium alkoxide as the organotitanium compound, and then a titanium oxide metal oxide layer 20 is formed. First, when titanium alkoxide is irradiated with energy equivalent to the band gap energy (approximately 3.2 eV), it is decomposed and oxidized, converting the titanium alkoxide to titanium oxide (O=Ti=O), thereby forming the metal oxide layer 20. Furthermore, when the titanium oxide is irradiated with energy equivalent to the band gap energy (approximately 3.2 eV), one of the oxygen atoms (O) of the titanium oxide reacts with a trace amount of water molecules (H ₂ O) present outside, generating hydrophilic hydroxyl groups (—OH) on the surface of the titanium oxide. This is thought to result in the development or improvement of hydrophilicity (however, the effects of this embodiment are not limited to this).

As described above, when hydroxyl groups are formed on the surface of the metal oxide layer 20 (formation of surface hydroxyl groups), external water molecules are adsorbed thereto through hydrogen bonding or the like, further improving hydrophilicity. In other words, not only chemically adsorbed water but also physically adsorbed water can contribute to hydrophilicity. As a result, a surface structure is formed in which hydrophilic and hydrophobic regions are mixed, and the water contact angle when water is dripped can be controlled to a suitable angle (e.g., 50° or less) as described below, further improving the adhesion between the substrate 10 and the adhesive layer 30. From this perspective, a preferred embodiment of this embodiment is one in which hydroxyl groups are present on the surface of the metal oxide layer 20.

In this embodiment, it is sufficient to apply energy to the organometallic compound layer 21 by irradiation, converting the organometallic compound to a metal oxide, and then adding hydroxyl groups. Energy irradiation is preferably performed by plasma treatment, excimer lamp treatment, low-mercury lamp treatment, electron beam treatment, gamma ray treatment, etc., and more preferably by excimer lamp treatment. When excimer lamp treatment is performed, a xenon excimer lamp is preferably used. Note that in this embodiment, it is preferable to irradiate the organometallic compound layer 21 with energy equivalent to the band gap energy of the metal oxide, and more preferably to irradiate the organometallic compound layer 21 with energy equal to or greater than the band gap energy of the metal oxide. Irradiating this level of energy allows the metal compound in the organometallic compound layer 21 to be efficiently converted (modified) into a metal oxide.

In this embodiment, when performing excimer lamp treatment, it is preferable to irradiate the organometallic compound layer 21 with energy having a peak wavelength of 200 nm or less (a suitable example is vacuum ultraviolet light; VUV). The lower limit of the peak wavelength is preferably 100 nm or more, more preferably 120 nm or more, even more preferably 140 nm or more, and even more preferably 150 nm or more. The upper limit of the peak wavelength is more preferably 180 nm or less. It is also preferable to irradiate the organometallic compound layer 21 with an irradiation energy in the range of 10 to 3000 mJ/ ^cm² . By irradiating energy under these conditions, it is possible to efficiently impart energy equal to or greater than the band gap energy of the metal oxide in the metal compound layer 21. As a result, the molecular bonds of the metal compound in the organometallic compound layer 21 are broken and decomposed, and the metal oxide is bonded (oxidized) with oxygen in the air, thereby efficiently forming the metal oxide layer 20 as described above.

One conventional film-forming technology is a vapor deposition method such as chemical vapor deposition (CVD). Vapor deposition involves, for example, heating a vapor deposition material (precursor) under reduced pressure or vacuum to generate a raw material gas, which is then deposited on a substrate to form a layer. Because this type of CVD method requires reduced-pressure equipment, the equipment configuration becomes large and it is not a simple manufacturing method for adhesive sheets. It is also not practical from the perspective of manufacturing costs. Furthermore, because the film formation depends on the material of the substrate, there are restrictions on the combination of substrate and vapor deposition material (material selectivity).

In addition, in the semiconductor manufacturing field, atmospheric pressure MOCVD methods have also been attempted, in which CVD is performed at atmospheric pressure using organometallic compounds (metal organics: MO) or organometallic complexes. While atmospheric pressure MOCVD has the advantage of being able to be performed at atmospheric pressure, it requires precise control of the source gas and carrier gas to achieve uniform film formation. Furthermore, the atmospheric pressure MOCVD method used in semiconductor manufacturing is limited by the fact that the source gas is toxic, making it difficult to simplify the reactor configuration. Thus, atmospheric pressure MOCVD cannot be considered a simple method for producing pressure-sensitive adhesive sheets. Furthermore, as mentioned above, the difficulty in controlling the source gas and carrier gas can lead to uneven film formation and product problems, such as difficulty in achieving a uniform hydrophilic surface.

However, the manufacturing method according to this embodiment first forms an organometallic compound layer 21 on a substrate, converts this into a metal oxide layer 20, and then makes this layer hydrophilic. Therefore, unlike conventional vapor deposition methods, this method has the advantage of not requiring manufacturing under vacuum and can be manufactured using a simple device configuration. Furthermore, it is possible to form a uniform metal oxide layer 20 and make it highly hydrophilic.

In this embodiment, step (2) allows for continuous energy irradiation in a roll-to-roll manner. Specifically, the substrate 10 (long substrate) on which the organometallic compound layer 21 obtained in step (1) is formed is unwound while applying an appropriate amount of tension in the transport direction, and is transported to an energy irradiation device, where energy is irradiated onto the organometallic compound layer 21. The substrate 10 is then wound onto a core.

As described above, according to this embodiment, step (2) does not necessarily have to be performed under reduced pressure, but can be performed under atmospheric pressure. Therefore, from the standpoint of eliminating restrictions on the device configuration and achieving superior manufacturing costs, it is preferable to perform energy irradiation under atmospheric pressure.

Furthermore, according to this embodiment, from the viewpoint of efficiently converting the organometallic compound to a metal oxide and further efficiently hydrophilizing the surface of the metal oxide layer 20, energy irradiation is preferably performed in an oxygen-containing atmosphere. Taking into consideration factors such as simplicity and cost, it is more preferable to perform the energy irradiation in an atmospheric atmosphere (air atmosphere). The oxygen-containing atmosphere may be any atmosphere containing oxygen, such as an atmosphere with an increased or decreased oxygen partial pressure in the atmosphere (air). In all of these atmospheres, oxygen (O ₂ ) is present, allowing these oxygen atoms to be introduced into the organometallic compound, thereby efficiently converting it to a metal oxide. Furthermore, these oxygen atoms can also be introduced into the surface of the metal oxide layer 20, allowing hydroxyl groups (—OH) to be efficiently introduced into the surface of the metal oxide layer 20. As a result, the hydrophilicity of the metal oxide layer 20 can be further improved, and the adhesion between the substrate 10 and the adhesive layer 30 can be further improved. Furthermore, since the process does not require an inert gas atmosphere such as nitrogen gas or a rare gas, it also has the advantages of simplicity and low manufacturing costs. These advantages are particularly pronounced in an atmospheric atmosphere.

The energy irradiation conditions in step (2) are not particularly limited. For example, when excimer lamp treatment is used, the irradiation time is preferably 1 to 200 seconds, more preferably 5 to 100 seconds, and even more preferably 10 to 50 seconds. Furthermore, when excimer lamp treatment is used, the irradiation distance from the irradiation target (substrate 10, etc.) is preferably 0.01 to 100 mm, more preferably 0.05 to 50 mm, and even more preferably 0.1 to 10 mm. By using such irradiation time and irradiation distance, a more uniform metal oxide layer 20 can be formed and greater hydrophilicity can be imparted.

The thickness of the metal oxide layer 20 is preferably 0.01 to 1 μm. The lower limit of this thickness is more preferably 0.03 μm or more, and even more preferably 0.05 μm or more. The upper limit of this thickness is more preferably 0.5 μm or less, and even more preferably 0.2 μm or less. Setting the lower limit of this thickness within this range further improves the hydrophilicity effect in step (2), and setting the upper limit of this thickness within this range further improves the effects of the transformation from the organometallic compound to a metal oxide and the hydrophilic modification of the metal oxide surface in step (2), thereby further improving the adhesion between the substrate 10 and the metal oxide layer 20.

The surface of the metal oxide layer 20 preferably has a water contact angle of 50° or less, more preferably 30° or less, and even more preferably 10° or less. In particular, it is preferable that the surface on the adhesive layer 30 side has the water contact angle described above. By setting the upper limit of the water contact angle within this range as a degree of hydrophilization, restrictions on the type of adhesive used in the adhesive layer 30 can be relaxed. In other words, adhesion to the substrate 10 can be improved for a wide range of adhesives. Furthermore, quality defects such as adhesive residue can be more effectively suppressed.

<Step (3)>

Next, (3) an adhesive layer 30 is formed on the surface of the metal oxide layer 20. According to this embodiment, by forming the adhesive layer 30 in a state where the surface of the metal oxide layer 20 has been hydrophilized and has been given high hydrophilicity (a suitable example is a state where the water contact angle of the metal oxide layer 20 is 50° or less), high adhesion between the substrate 10 and the adhesive layer 30 can be obtained.

One method for forming the adhesive layer 30 is to apply the adhesive composition that will become the adhesive layer 30 to the surface of the metal oxide layer 20 using a coating machine such as a bar coater, die coater, gravure coater, roll coater, blade coater, air knife coater, or size press coater to form a layer. Among these, methods using a bar coater, die coater, or gravure coater are preferred from the perspective of ease of layer formation.

The adhesive for the adhesive composition can be, for example, a known acrylic adhesive, rubber adhesive, silicone adhesive, epoxy adhesive, ester adhesive, etc.

The adhesive composition may also contain additives such as colorants (e.g., dyes, pigments), antioxidants (e.g., anilides, phenols), UV absorbers (e.g., benzophenones, benzotriazoles), light stabilizers, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, crosslinking agents, and solvents. In other words, the adhesive layer 30 may contain these additives as needed. As described below, the metal oxide layer 20 can effectively inhibit the migration of low-molecular-weight compounds to other layers, and therefore can also inhibit the migration of low-molecular-weight additives, etc., to other layers.

According to this embodiment, step (3) can be carried out continuously in a roll-to-roll manner. Specifically, the substrate 10 (long substrate) wound around a core is unwound in the transport direction while being applied with appropriate tension, and passed through a coater to coat the surface of the metal oxide layer 20 with a coating liquid containing an adhesive composition. The substrate 10, which has passed through the coater and on which a coating film has been formed, is then transported to a drying oven, where the coating film is dried to form an adhesive layer 30, after which the substrate 10 is wound around the core.

According to this embodiment, the pressure-sensitive adhesive sheet 1 can be manufactured by carrying out the above-described steps (1) to (3). The above-described steps (1) to (3) may be carried out using continuous in-line equipment, or each of steps (1) to (3) may be carried out using offline equipment. The pressure-sensitive adhesive sheet 1 can also be used as a pressure-sensitive adhesive sheet with a release substrate, which further comprises a release substrate. A pressure-sensitive adhesive sheet with a release substrate can be manufactured, for example, by the following method.

Figure 2 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet with a release substrate obtained by the manufacturing method according to this embodiment.

The adhesive sheet 4 with a release substrate is formed by laminating a release substrate 40 on the surface of the adhesive layer 30 of the adhesive sheet 1 shown in Figure 1. This adhesive sheet 4 with a release substrate can be obtained, for example, by the following manufacturing method.

First, the above-described steps (1) and (2) are performed to prepare a treated laminate 3 (see Figure 1(b)) having a substrate 10 and a metal oxide layer 20.

Then, an adhesive composition that will form the adhesive layer 30 is prepared and applied to the surface of the release substrate 40 by the method described in step (3) to form the adhesive layer 30. This prepares a release substrate 40 (release substrate 5 with adhesive layer) on which the adhesive layer 30 has been formed.

Then, the treated laminate 3 and the release substrate 5 with an adhesive layer are bonded together so that the metal oxide layer 20 of the treated laminate 3 comes into contact with the adhesive layer 30 of the release substrate 5 with an adhesive layer, thereby obtaining an adhesive sheet 4 with a release substrate (see Figure 2).

The release substrate 40 is not particularly limited and any known material can be used.

As explained above, the manufacturing method according to this embodiment makes it possible to obtain a highly adhesive pressure-sensitive adhesive sheet 1 without peeling the substrate 10 and the adhesive layer 30. Furthermore, it is also possible to impart to the metal oxide layer 20 the function of inhibiting the migration of low-molecular-weight substances to other layers.

A suitable example of the pressure-sensitive adhesive sheet 1 includes a substrate 10, a metal oxide layer 20 formed on the surface of the substrate 10, and a pressure-sensitive adhesive layer 30 formed on the surface of the metal oxide layer 20 opposite the substrate 10. The metal oxide layer 20 is a metal oxide layer that has been hydrophilized by irradiating an organometallic compound layer having a thickness of 0.01 to 1 μm obtained by applying a coating liquid containing an organometallic compound with energy. For example, when the organometallic compound is an organosilicon compound, the pressure-sensitive adhesive sheet 1 contains silicon oxide (metal oxide) that has been hydrophilized by irradiating the organosilicon compound with energy, and is confirmed to have peaks derived from hydroxyl-containing compounds such as silanols by labeling analysis using an XPS apparatus.

The adhesive sheet 1 obtained in this manner can be suitably used as a sheet for general labels, a sheet for processing electronic components, a sheet for displays, a sheet for automobiles, a sheet for windows, etc.

The present invention will be explained in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples in any way. Note that percentages and parts are by weight unless otherwise specified.

<Example 1>

(Formation of an organometallic compound layer)

100 parts by weight of addition reaction curing polyorganosiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KS835, addition reaction curing PDMS) was diluted with toluene to prepare a 10% by weight solution, to which 2 parts by weight of platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name: PL-50T) was added to prepare an organometallic compound coating solution.

Next, the organometallic compound coating solution was applied to the surface of substrate 10 (polypropylene (PP), manufactured by Oji F-Tex Co., Ltd., product name: Alphan PK-002, thickness 40 μm). Then, by heating and drying at 90°C for 1 minute, an organometallic compound layer 21 with a dry thickness of 0.05 μm was formed on substrate 10. This resulted in a laminate 2 (substrate 10/organometallic compound layer 21, see Figure 1(a)).

(Formation of metal oxide layer 20 and hydrophilization treatment)

The surface of organometallic compound layer 21 of the obtained laminate 2 (substrate 10/organometallic compound layer 21) was irradiated with ultraviolet light having a peak wavelength of 172 nm for 30 seconds using a xenon excimer lamp (manufactured by Hamamatsu Photonics KK, product name: FLAT EXCIMER EX-mini, ^L12530-01 ) in an air atmosphere and at atmospheric pressure, with a distance of 1 mm between the light irradiation window and the laminate, to impart energy in the range of 10 to 3000 mJ/cm2, thereby converting the organometallic compound to metal oxide ( _SiO2 ), thereby producing post-treatment laminate 3 (substrate 10/metal oxide layer 20, see Figure 1(b)). Note that the energy imparted to the organometallic compound by the excimer lamp treatment was equal to or greater than the band gap energy of the metal oxide ( _SiO2 ).

The change from the organometallic compound layer 21 to the metal oxide layer 20 was confirmed by XPS analysis, which confirmed the occurrence of a chemical shift due to Si ³⁺ and a chemical shift due to Si ⁴⁺ after the excimer lamp treatment, confirming that PDMS had changed to SiO ₂ .
The presence of hydroxyl groups (-OH) was confirmed by labeling analysis of the surface of the metal oxide layer 20 using an X-ray photoelectron spectrometer (XPS device; manufactured by ULVAC-PHI, Inc., product name: Quantum 2000). The water contact angle of the surface of the metal oxide layer 20 obtained in this manner was measured.

The change from the organometallic compound layer 21 to the metal oxide layer 20 was confirmed by measuring peaks derived from C1s, O1s, and Si2p using an XPS device and by the elemental composition, confirming that PDMS had changed to _SiO2 .

In addition, the hydroxyl groups (-OH) on the surface of the metal oxide layer 20 were labeled with a labeling reagent, and then measured using X-ray photoelectron spectroscopy (XPS) to confirm the presence of hydroxyl groups on the surface of the metal oxide layer 20 (labeling analysis).

(Formation of adhesive layer 30)

80 parts by mass of 2-ethylhexyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare an acrylic acid ester copolymer (weight average molecular weight: 600,000). The resulting acrylic acid ester copolymer was mixed with 2 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name: Coronate L) as a crosslinking agent, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition with a solids concentration of 25% by mass.

The resulting adhesive composition coating solution was applied using a knife coater to the release-treated surface of a release substrate 40 (manufactured by Lintec Corporation, product name: SP-PET382150, adhesive sheet with a thickness of 38 μm, see Figure 2), one side of which had been treated with a silicone-based release agent, so that the dry thickness would be 25 μm. The adhesive layer 30 was then formed by heating at 100°C for 1 minute.

Next, the release substrate 40 on which the adhesive layer 30 was formed was attached to the treated laminate 3 (substrate 10/metal oxide layer 20, see Figure 1(b)) so that the metal oxide layer 20 of the treated laminate 3 was in contact with the adhesive layer 30. This was then cured for 7 days under conditions of 23°C and 50% RH to produce an adhesive sheet 4 with a release substrate (substrate 10/metal oxide layer 20/adhesive layer 30/release substrate 40, see Figures 2 and 1(c)).

<Example 2>

Except for the fact that the thickness of the organometallic compound layer 21 and the thickness of the metal oxide layer 20 were set to 0.1 μm, an adhesive sheet 4 with a release substrate was produced in the same manner as in Example 1. The energy imparted to the organometallic compound by the excimer lamp treatment was equal to or greater than the band gap energy of the metal oxide (SiO ₂ ).

As a result of analysis in the same manner as in Example 1, it was confirmed that the organometallic compound layer 21 had changed into a metal oxide layer 20 made of SiO ₂ , and that hydroxyl groups (—OH) were present on the surface.

<Example 3>

A release substrate-attached pressure-sensitive adhesive sheet 4 was produced in the same manner as in Example 1, except that 100 parts by mass of titanium oligomer (manufactured by Matsumoto Fine Chemical Co., Ltd., trade name: Orgatix PC-250; organic titanium compound) was diluted with ethanol to prepare a 2 mass% organometallic compound solution. The energy imparted to the organometallic compound by excimer lamp treatment was equal to or greater than the band gap energy of the metal oxide (TiO ₂ ).

As a result of analysis in the same manner as in Example 1, it was confirmed that the organometallic compound layer 21 had changed into a metal oxide layer 20 made of _TiO2 , and that hydroxyl groups (-OH) were present on the surface.

<Example 4>

Except for the fact that the thickness of the organometallic compound layer 21 and the thickness of the metal oxide layer 20 were 0.1 μm, an adhesive sheet 4 with a release substrate was produced in the same manner as in Example 3. The energy imparted to the organometallic compound by the excimer lamp treatment was equal to or greater than the band gap energy of the metal oxide (TiO ₂ ).

As a result of analysis in the same manner as in Example 1, it was confirmed that the organometallic compound layer 21 had changed into a metal oxide layer 20 made of _TiO2 , and that hydroxyl groups (-OH) were present on the surface.

<Comparative Example 1>

A pressure-sensitive adhesive sheet with a release substrate was prepared in the same manner as in Example 1, except that a metal oxide layer 20 was not formed on the surface of the substrate 10.

<Comparative Example 2>

A pressure-sensitive adhesive sheet with a release substrate was prepared in the same manner as in Example 1, except that the thickness of the organometallic compound layer 21 and the metal oxide layer 20 were both 0.003 μm.

As a result of analysis in the same manner as in Example 1, it was confirmed that the organometallic compound layer 21 had changed into a metal oxide layer 20 made of SiO ₂ , and that hydroxyl groups (—OH) were present on the surface.

<Comparative Example 3>

A pressure-sensitive adhesive sheet with a release substrate was prepared in the same manner as in Example 3, except that the thickness of the organometallic compound layer 21 and the metal oxide layer 20 were both 3.0 μm.

As a result of analysis in the same manner as in Example 1, it was confirmed that the organometallic compound layer 21 had changed into a metal oxide layer 20 made of SiO ₂ , and that hydroxyl groups (—OH) were present on the surface.

<Evaluation Method>

Each physical property was evaluated according to the methods described below. The pressure-sensitive adhesive sheet 1 (see Figure 1) to be measured was prepared by removing the release substrate 40 from the pressure-sensitive adhesive sheet 4 with release substrate (see Figure 2).

(Surface analysis)

As described above, the surface analysis of the organometallic compound layer 21 and the metal oxide layer 20 was carried out in accordance with the following method.
The change from the organometallic compound layer 21 to the metal oxide layer 20 was confirmed by XPS analysis to see whether or not there was a change from the organometallic compound to the metal oxide before and after the treatment.
Then, the surface of the metal oxide layer 20 was subjected to labeling analysis using an XPS device to confirm whether or not hydroxyl groups (—OH) were present.

(Thickness measurement)

The thickness of the organometallic compound layer 21 and the thickness of the metal oxide layer 20 were measured under the following conditions using a reflective film thickness meter (manufactured by Filmetrics, product name: F20) and a spectroscopic ellipsometer (product name: M-2000) manufactured by J. A. Woollam Japan.
Measurement range 0.001 to 0.5 μm: Spectroscopic ellipsometer Measurement range 0.5 to 10 μm: Reflection film thickness meter

(Water contact angle measurement)

In accordance with JIS R 3257, the contact angle of the surface of the metal oxide layer 20 with 2 μL of water was measured using a fully automatic contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., product name: DM-701).

(Adhesion test)

The adhesiveness of the adhesive sheet was evaluated by a rub-off test. Specifically, the surface of the adhesive layer was rubbed strongly with a fingertip five times over a distance of 3 cm, and then visually inspected to see if any of the adhesive had come off from the surface of the adhesive layer.
Good: No peeling of the adhesive from the surface of the adhesive layer was visually confirmed.
×: Peeling off of the adhesive from the surface of the adhesive layer was visually confirmed.

(Mineral oil migration inhibition test)

Furthermore, a mineral oil migration inhibition test was conducted on the PSA sheets 1 of Examples 1 to 4 (see Figure 1(c)), and the effect of inhibiting the migration of low molecular weight compounds was also verified. Specifically, mineral oil (components: hydrogen-treated heavy naphthenic oil) was applied to the surface of the metal oxide layer 20 of the post-treatment laminate 3 at the stage of Figure 1(b) using a bar coater, and the sheet was left to stand at room temperature for seven days. The condition after seven days was then observed. As a result, it was confirmed by visual inspection that the mineral oil had not penetrated into the substrate 10 in any of Examples 1 to 4.

The manufacturing conditions and evaluation results for each example and comparative example are shown in Tables 1 and 2.

From the above, it was confirmed that this example at least makes it possible to produce an adhesive sheet in which the metal oxide layer is highly hydrophilic, the adhesive layer has high adhesion to the substrate, the substrate and adhesive layer do not peel off during use, and the migration of low-molecular-weight compounds can be suppressed.

1: Adhesive sheet 2: Laminate 3: Treated laminate 4: Adhesive sheet with release substrate 5: Release substrate with adhesive layer 10: Substrate 20: Metal oxide layer 21: Organometallic compound layer 30: Adhesive layer 40: Release substrate

Claims (6)

a step of directly applying a coating liquid containing an organometallic compound onto the surface of a substrate to form an organometallic compound layer having a thickness of 0.01 to 1 μm;
a step of irradiating the organometallic compound layer with energy to convert at least a part of the organometallic compound in the organometallic compound layer into a metal oxide to form a metal oxide layer, and further making the metal oxide layer hydrophilic;
forming an adhesive layer directly on the surface of the metal oxide layer ;
Including,
the metal oxide layer is a single layer,
The energy is irradiated by an excimer lamp treatment.
A method for manufacturing an adhesive sheet. The energy irradiation is carried out in an atmospheric environment.
The method of claim 1. The energy irradiation is carried out under atmospheric pressure.
The method according to claim 1 or 2. the metal oxide layer has a surface water contact angle of 50° or less;
The method according to any one of claims 1 to 3. the organometallic compound is at least one selected from the group consisting of organosilicon compounds, organoaluminum compounds, organotitanium compounds, organovanadium compounds, organozirconium compounds, organoniobium compounds, organomolybdenum compounds, organohafnium compounds, organotantalum compounds, organotungsten compounds, organocerium compounds, organonickel compounds, organochromium compounds, organocobalt compounds, organotin compounds, and organocopper compounds;
The method according to any one of claims 1 to 4. A substrate;
a metal oxide layer formed directly on the surface of the substrate;
an adhesive layer formed directly on the surface of the metal oxide layer opposite to the substrate;
Including,
the metal oxide layer is a metal oxide layer obtained by applying a coating liquid containing an organometallic compound to an organometallic compound layer having a thickness of 0.01 to 1 μm, and then subjecting the organometallic compound layer to a hydrophilic treatment by irradiating the organometallic compound layer with energy ;
the metal oxide layer is a single layer,
The energy is irradiated by an excimer lamp treatment.
Adhesive sheet.