JP2005154492A - Antistatic self-adhesive film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic self-adhesive film excellent in transparency and re-releasability by solving problems caused by peeling electrification of conventional antistatic self-adhesives in optical applications. <P>SOLUTION: The antistatic self-adhesive film comprises a plastic film and, laminated on at least one surface thereof, a self-adhesive layer formed of an antistatic polyurethane self-adhesive comprising a hydroxyl group-containing polyurethane (A), an ionic compound (B) and a trifunctional isocyanate compound (C). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antistatic pressure-sensitive adhesive film and a method for producing the same. In detail, this invention relates to the adhesive film suitable for the surface protection film for protecting the to-be-adhered body surface mechanically and electrically for a predetermined period. In more detail, the adhesive of this invention is used suitably for the adhesive film for surface protection of optical components, such as a liquid crystal panel, a plasma display, a polarizing plate, and CRT (CRT).

  Conventionally, the surface of various displays such as word processors, computers, mobile phones, TVs, or optical components such as polarizing plates and laminates equivalent thereto, electronic substrates, and the like, usually for the purpose of surface protection and imparting functionality, A transparent surface protective film (base film) such as polypropylene is laminated via an adhesive.

  In many cases, these surface protective pressure-sensitive adhesive films are peeled and removed after finishing the role of surface protection, for example, after the incorporation of a liquid crystal display or the like is completed. However, there is a problem that static electricity is generated when the surface protective adhesive film is peeled off and entraps surrounding dust. Furthermore, there may be a problem that the liquid crystal and the electronic circuit are destroyed due to peeling electrification generated when the surface protective adhesive film is peeled off.

Therefore, various measures as described below have been proposed as means for imparting antistatic properties to the surface protective adhesive film.
For example,
(1) imparting antistatic properties to the substrate film itself constituting the surface protective adhesive film;
(2) Between the base film and the pressure-sensitive adhesive layer constituting the surface protective pressure-sensitive adhesive film, on the side where the pressure-sensitive adhesive layer of the base film is not laminated, or between the base film and the pressure-sensitive adhesive layer In between, provide a layer having antistatic performance,
(3) Giving antistatic properties to the pressure-sensitive adhesive layer constituting the surface protective pressure-sensitive adhesive film, and the like.

The method (1) is a method in which a conductive base material is prepared by kneading an anionic compound such as an organic sulfonate group, a metal powder, or a conductive filler such as carbon black with a thermoplastic resin such as polyester or polyethylene as a raw material for the base film. In this case, the transparency of the base film is lowered or the film is colored.
By the way, while the surface protective adhesive film is stuck on the adherend, the surface protective appearance of the adherend needs to be continuously inspected through the adhesive film. Therefore, the surface protective pressure-sensitive adhesive film pressure-sensitive adhesive sheet itself is required to be excellent in transparency and optically free from defects.
Therefore, when the surface protection adhesive film using an antistatic agent containing base film is stuck on a to-be-adhered body, there exists a problem that an adherend surface becomes difficult to see. There is also a problem that the base film becomes expensive.

The method (2) has various variations as described below (Japanese Patent Laid-Open Nos. 7-26223, 11-256116, 2001-219520, 2002-060707). JP, 2002-275296, A, etc.).
(2-1) depositing a metal compound on at least one surface of the base film;
(2-2) An anionic surfactant such as a quaternary ammonium salt, a long-chain alkyl compound having a sulfonate group, a thiophene derivative, or a nitrogen element ionized in the main chain on at least one surface of the base film And a layer containing various antistatic agents such as sulfonate group-modified polystyrene.
However, since an anionic surfactant such as a long-chain alkyl compound having a sulfonate group has a relatively low molecular weight, a part of the antistatic agent moves through the antistatic coating film to form a base film. There is a problem of accumulating at the interface and transferring to the opposite surface of the base film, and a problem that the antistatic property decreases with time.
In addition, since the polymer having nitrogen element ionized in the main chain, sulfonate group-modified polystyrene, and the like have a relatively high molecular weight, the above-described problems do not occur. However, in order to obtain good antistatic performance, it is necessary to add a large amount of antistatic agent, and it is not economical because it is necessary to increase the thickness of the antistatic layer. Furthermore, when scrap film that has not been turned into a product (for example, film edges cut and removed in the manufacturing process) is collected and used as a recycled material for film production, it is included in the recycled material during melt film formation. There arises a problem that the antistatic agent component is thermally deteriorated, and the film to be regenerated is extremely colored and lacks practicality (recoverability is poor). In addition, there are disadvantages that the films are difficult to peel (block) and the coating film is easily scraped, and the solution is desired.

The method (3) is a method of imparting antistatic performance to the peeling interface where static electricity is generated, and a method of forming a pressure sensitive adhesive using a resin having antistatic performance, and a pressure sensitive adhesive containing an antistatic agent-containing pressure sensitive adhesive. There is a method of forming a layer (Patent Document 1: JP-A-1-253482).
In the former case, the antistatic performance of the resin itself, which can be paraphrased as electrical conductivity, is insufficient.
In the latter case, examples of the antistatic agent used include various surfactants and conductive powders such as carbon black. However, when a surfactant-containing pressure-sensitive adhesive is used, the surfactant generally tends to be concentrated on the surface of the pressure-sensitive adhesive layer, i.e., the bonding interface with the adherend, and the pressure-sensitive adhesive performance is low due to the surfactant. Very sensitive. That is, when moisture reduces the cohesive force of the pressure-sensitive adhesive layer and peels off the surface protective pressure-sensitive adhesive film, a part of the pressure-sensitive adhesive layer tends to remain on the adherend (so-called “glue residue”). On the other hand, when a conductive pressure-sensitive adhesive containing conductive powder such as carbon black is used, there arises a problem that transparency of the pressure-sensitive adhesive layer and the surface protective pressure-sensitive adhesive film is lowered or the film is colored.

The use of an antistatic agent that is excellent in transparency and hardly causes coloring problems is disclosed in Japanese Patent Application Laid-Open No. 08-170065.
However, the invention described in Patent Document 2 is for an electrode pad that is applied to a living body although it relates to a conductive adhesive, and the conductive adhesive described in Patent Document 2 is used for a surface protective adhesive film. Was not at all usable.
JP-A-1-253482 JP-A-8-170065

  The object of the present invention is to provide excellent transparency and little coloration suitable as a pressure-sensitive adhesive for surface protective adhesive films of optical members such as various displays and polarizing plates. An object is to provide an antistatic pressure-sensitive adhesive film using the pressure-sensitive adhesive.

  As a result of intensive studies, the inventor made the specific hydroxyl group-containing polyurethane (A) contain the ionic compound (B) and cured it with the specific polyisocyanate compound (C), thereby charging with appropriate conductivity. The present inventors have found that an antistatic adhesive can be obtained, and further found that an antistatic adhesive film can be obtained by laminating it on a plastic film, thereby completing the present invention.

  That is, the present invention provides a pressure-sensitive adhesive layer formed of an antistatic polyurethane pressure-sensitive adhesive containing a hydroxyl group-containing polyurethane (A), an ionic compound (B) and a trifunctional isocyanate compound (C) as a plastic film. The present invention relates to an antistatic pressure-sensitive adhesive film that is laminated on at least one surface.

  Further, the present invention is obtained by reacting the polyol component (a1) having an alkylene oxide chain, the polyester polyol component (a2), and the diisocyanate compound (a3) under a hydroxyl group-excess condition. The antistatic pressure-sensitive adhesive film according to the invention is a hydroxyl group-containing polyurethane (A).

  The present invention also relates to the antistatic pressure-sensitive adhesive film according to any one of the above inventions, wherein the trifunctional isocyanate compound (C) is a trimethylolpropane adduct or isocyanurate.

The present invention also relates to the antistatic pressure-sensitive adhesive film according to any one of the above inventions, wherein the alkylene oxide chain in the polyol component (a1) is an ethylene oxide chain and a propylene oxide chain.
Furthermore, the present invention relates to the antistatic pressure-sensitive adhesive film according to the invention, wherein the weight ratio of the ethylene oxide chain to the propylene oxide chain is EO / PO = 10/90 to 50/50.

  The present invention also relates to the antistatic pressure-sensitive adhesive film according to any one of the above inventions, wherein the polyol component (a1) is a trifunctional polyether polyol.

  The present invention also provides the antistatic pressure-sensitive adhesive according to any one of the above inventions, wherein the ionic compound (B) is contained in an amount of 0.1 to 50% by weight in a solid content of 100% by weight of the antistatic polyurethane pressure-sensitive adhesive. Related to film.

  The present invention also relates to the antistatic pressure-sensitive adhesive film according to any one of the above inventions, wherein the ionic compound (B) is an inorganic salt.

  In the present invention, the hydroxyl group-containing polyurethane (A) comprises a polyol component (a1) having an alkylene oxide chain, a polyester polyol component (a2), and a diisocyanate compound (a3), and the polyol components (a1) and (a2). The antistatic pressure-sensitive adhesive film according to any one of the above inventions, wherein the reaction is performed at an equivalent ratio of total hydroxyl group / isocyanate group = 65/35 to 50/50.

  Further, the present invention is characterized in that the molar ratio of the polyol component (a1) having an alkylene oxide chain to the polyester polyol component (a2) is (a1) / (a2) = 90/10 to 40/60. The present invention relates to an antistatic pressure-sensitive adhesive film according to any one of the above inventions.

  The present invention also relates to the antistatic pressure-sensitive adhesive film according to any one of the above inventions, wherein the hydroxyl group-containing polyurethane (A) has a weight average molecular weight of 30,000 to 150,000.

  The present invention also relates to the antistatic pressure-sensitive adhesive film according to any one of the above inventions, which is for protecting the surface of an optical member or an electronic member.

  Moreover, this invention relates to the method of protecting the surface of an optical member thru | or an electronic member using the antistatic adhesive film in any one of the said invention.

Furthermore, the present invention provides a first component comprising a polyol component (a1) having an alkylene oxide chain, a polyester polyol component (a2), and an ionic compound (B).
The second component containing the diisocyanate compound (a3) is added in a range where the isocyanate groups are relatively small relative to the total hydroxyl groups of the polyol components (a1) and (a2),
The first component and the second component are reacted to obtain a hydroxyl group-containing polyurethane (A),
Next, a polyurethane composition formed by adding the trifunctional isocyanate compound (C),
A method for producing an antistatic pressure-sensitive adhesive film, which is coated on a release sheet, dried, laminated with a plastic film on the surface of the pressure-sensitive adhesive layer, and reacted with a hydroxyl group-containing polyurethane (A) and a trifunctional isocyanate compound (C). About.

  According to the present invention, an antistatic pressure-sensitive adhesive film having a low surface resistance value and excellent transparency and removability can be obtained.

The antistatic pressure-sensitive adhesive film of the present invention has a structure in which an antistatic polyurethane pressure-sensitive adhesive having a relatively good conductivity and a plastic film are laminated, and takes various forms in consideration of its use and required performance. be able to.
Of various embodiments of the antistatic pressure-sensitive adhesive film of the present invention, a case where it is used as a protective film for a polarizing plate will be described with reference to the drawings.
FIG. 1 shows an antistatic polyurethane adhesive layer on the polarizing plate side of a PET film.
FIG. 2 shows an antistatic polyurethane adhesive layer on both the polarizing plate side and the opposite side of the PET film.
FIG. 3 shows an antistatic coating agent layer on the polarizing plate side of the PET film, and further an antistatic polyurethane adhesive layer.
FIG. 4 shows an embodiment in which an antistatic polyurethane adhesive layer is located on the polarizing plate side of the PET film and an antistatic coating layer is located on the opposite side.
When used for protecting the surface of an optical member or an electronic member as in the present invention, the configuration shown in FIGS. 3 and 4 can be employed in order to further reduce the peel charge amount.
Moreover, in the use which gives functionality to a plastic film, it takes the form as shown in FIG. 2 and the functional film can be further bonded.
In consideration of workability and production cost, the case of FIG. 1 is most preferable.

First, the antistatic polyurethane adhesive will be described.
The antistatic polyurethane pressure-sensitive adhesive contains a hydroxyl group-containing polyurethane (A), an ionic compound (B), and a trifunctional isocyanate compound (C).

  Examples of the polyol component (a1) having an alkylene oxide chain used in the present invention include a known polyether polyol, a reaction product of a known polyether polyol and polyisocyanate and having a terminal hydroxyl group. .

  As the known polyether polyol used in the present invention, a repeating structure of an alkylene oxide chain such as a methylene oxide chain, an ethylene oxide chain (EO), a propylene oxide chain (PO), or a butylene oxide chain may be used alone or in two types. What has the above can be used and what has both an ethylene oxide chain (EO) and a propylene oxide chain (PO) is preferable.

The alkylene oxide chain part in the polyether polyol, particularly the ethylene oxide chain part, forms a complex (complex) with the ionic compound (B) described later, and when an electric potential is applied, the ionic conductivity is expressed, and the current flows through the adhesive. Flows. As for the conductivity, the resistance value on the surface of the pressure-sensitive adhesive layer is preferably 10 ¹⁰ Ω / □ or less. More preferably, it is 10 ⁸ Ω / □ or less.

  Since the conductivity due to the ionic compound (B) is difficult to develop when only the PO chain is used, it is preferable that the PO chain is less from the viewpoint of conductivity. However, if only the EO chain is present, the pressure-sensitive adhesive layer produced tends to be hard, and it becomes difficult to ensure adhesion to various optical members. Therefore, the weight ratio of the EO chain to the PO chain is preferably EO / PO = 10/90 to 50/50.

  The polyether polyol (a1) used in the present invention may be linear or may have a partly branched structure, and it is preferable to use one having a partly branched structure.

  Moreover, as the polyether polyol (a1), it is preferable to use a liquid which is liquid at room temperature in a relatively low molecular weight region having a number average molecular weight of about 500 to 5,000. When such a polyether polyol is used, a pressure-sensitive adhesive having excellent adhesion and wettability can be obtained. When a relatively high molecular weight viscous liquid or solid polyether polyol is used, the tackiness of the product obtained by reacting the trifunctional isocyanate compound (C) is lowered, which is not preferable.

  As the polyester polyol component (a2) used in the present invention, a known polyester polyol can be used. Examples of the acid component include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, trimellitic acid, and the like, and the glycol component includes ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol. , 3-methyl-1,5-pentanediol, 3,3′-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, polyol component Examples include glycerin, trimethylolpropane, and pentaerythritol. Other examples include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly (β-methyl-γ-valerolactone), and polyvalerolactone.

  The molecular weight of the polyester polyol (a2) can be used from a low molecular weight to a high molecular weight, but it is preferable to use a polyester polyol (a2) that is liquid at room temperature in a relatively low molecular weight region of about 500 to 5,000. When such a polyester polyol is used, an adhesive having excellent adhesion and wettability can be obtained. It is not preferable to use a polyester polyol that is solid at room temperature because the adhesive properties are likely to deteriorate.

  The purpose of using the polyester polyol (a2) is to control the tackiness of the polyurethane (A). The content is preferably polyether polyol (a1) / polyester polyol (a2) = 90/10 to 40/60 in terms of molar ratio as compared with the amount of polyether polyol (a1). More preferably, it is 70 / 30-50 / 50. When the polyester polyol (a2) is less than 10 mol%, the cohesive strength of the polyurethane (A) is insufficient, and when it is more than 60 mol%, the tackiness is lowered, which is not preferable.

  As the diisocyanate compound (a3) used in the present invention, a known diisocyanate compound (a3) can be used.

  Examples of the known diisocyanate compound (a3) include aromatic diisocyanates, aliphatic diisocyanates, araliphatic diisocyanates, and alicyclic diisocyanates.

  As aromatic diisocyanates, 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate Examples thereof include isocyanate, 4,4′-toluidine diisocyanate, dianisidine diisocyanate, and 4,4′-diphenyl ether diisocyanate.

  Aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4 , 4-trimethylhexamethylene diisocyanate and the like.

  Examples of the araliphatic diisocyanate include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene, 1, Examples include 4-tetramethylxylylene diisocyanate and 1,3-tetramethylxylylene diisocyanate.

  Examples of alicyclic diisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4- Examples include cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane, 1,4-bis (isocyanate methyl) cyclohexane, and the like. .

  As the diisocyanate compound (a3) used in the present invention, it is preferable to use 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate).

Examples of the ionic compound (B) used in the present invention include sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, Inorganic salts such as ammonium sulfate, potassium nitrate, sodium nitrate, sodium carbonate, sodium thiocyanate,
Organic salts such as sodium acetate, sodium alginate, sodium lignin sulfonate, and sodium toluene sulfonate are listed. These can be used alone or in combination. From the viewpoints of conductivity and safety, sodium chloride, potassium chloride, lithium perchlorate and the like are preferable.

  Moreover, it is preferable that the content is 0.1 to 50 weight% in 100 weight% of adhesive solid content. More preferably, it is 1 to 30% by weight. If it is less than 0.1% by weight, sufficient ionic conductivity cannot be obtained, and even if it contains more than 50% by weight of the ionic compound (B), the effect of improving the conductivity can hardly be expected. And, since the whitening of the coating film tends to occur due to a decrease in compatibility with the resin, it is not preferable.

  The trifunctional isocyanate compound (C) used in the present invention is a trifunctional isocyanate compound formed from the diisocyanate compound (a3) provided for the formation of the polyurethane (A). Specifically, a so-called adduct obtained by modifying the diisocyanate compound (a3) with a trifunctional polyol component, a burette obtained by reacting the diisocyanate compound (a3) with water, and an isocyanurate ring formed from three molecules of the diisocyanate compound (a3). A trimer (isocyanurate form) having the following can be used. In the present invention, the trimethylolpropane adduct of the adducts is used for the application that emphasizes the flexibility of the coating, and the isocyanurate is the trifunctional isocyanate compound (C ) Is preferred.

Next, a method for producing the antistatic pressure-sensitive adhesive of the present invention will be described.
A polyol component (a1) having an alkylene oxide chain, a polyester polyol (a2), and a diisocyanate compound (a3) are charged together and reacted to obtain a polyurethane (A), and then an ionic compound (B) and a trifunctional isocyanate compound ( A method of adding C) is also possible in some cases. However, in consideration of the solubility of the ionic compound (B), it is preferably produced by the following method.

That is, a first component containing a polyol component (a1) having an alkylene oxide chain, a polyester polyol (a2), and an ionic compound (B) is obtained, and the diisocyanate compound (a3) is added to the first component under hydroxyl-excess conditions. It is preferable to obtain a hydroxyl group-containing polyurethane (A) by adding a second component containing) and reacting the hydroxyl group with an isocyanate group.
The first component and the second component can contain an organic solvent that does not affect the reaction between the hydroxyl group and the isocyanate group. Examples of the organic solvent that can be used include organic solvents generally used in the urethane reaction, such as toluene and ethyl acetate.

In obtaining the first component, the polyol component (a1) having an alkylene oxide chain, the polyester polyol (a2) and the ionic compound (B) can be mixed at once, or the polyol component (a1 having an alkylene oxide chain). ) And the polyester polyol (a2) may be mixed in advance, and the ionic compound (B) may be added and mixed therewith, or the ionic compound (B1) may be added to the polyol component (a1) having an alkylene oxide chain. ) May be added and mixed to dissolve the ionic compound (B) in advance, and then the polyester polyol (a2) may be added.
The reaction between the first component and the second component is a reaction between a hydroxyl group and an isocyanate group, and the equivalent ratio of the total hydroxyl group and isocyanate group of the polyol component (a1) and the polyester polyol (a2) is OH / NCO. = 65/35 to 50/50 is preferable. When the OH ratio exceeds 65, the number of unreacted hydroxyl components increases, and even after completion of the urethane reaction, it remains as a monomer, so that the cohesive force of the pressure-sensitive adhesive is reduced and the removability is often poor. On the other hand, if it is 50 or less, excess isocyanate groups remain in the urethane resin, which is not preferable because the stability of the resin solution deteriorates.

Moreover, it is preferable to use a catalyst when the polyol component (a1) and polyester polyol (a2) having an alkylene oxide chain are reacted with the diisocyanate compound (a3).
As the catalyst used in the present invention, a known catalyst can be used. Examples thereof include tertiary amine compounds and organometallic compounds.

  Examples of the tertiary amine compound include triethylamine, triethylenediamine, N, N-dimethylbenzylamine, N-methylmorpholine, 1,8-diaza-bicyclo (5,4,0) undecene (abbreviated as DBU) and the like.

Examples of organometallic compounds include tin compounds and non-tin compounds.
Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, Examples include triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

  Examples of non-tin compounds include titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanate and butoxytitanium trichloride, lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate and lead naphthenate, 2- Examples include iron series such as iron ethylhexanoate and iron acetylacetonate, cobalt series such as cobalt benzoate and cobalt 2-ethylhexanoate, zinc series such as zinc naphthenate and zinc 2-ethylhexanoate, and zirconium naphthenate. It is done.

  As the catalyst used in the present invention, dibutyltin dilaurate (DBTDL), tin 2-ethylhexanoate and the like are preferable, and depending on the case, they can be used alone or in combination.

The antistatic pressure-sensitive adhesive of the present invention is obtained by adding a trifunctional isocyanate compound (C) to a composition containing the hydroxyl group-containing polyurethane (A) and the ionic compound (B) obtained as described above. . The hydroxyl group-containing polyurethane (A) and the trifunctional isocyanate compound (C) are preferably (A) / (C) = 99.9 / 0.1 to 70/30 (weight ratio), 99/1 More preferably, it is -80/20 (weight ratio).
It is not preferable that the hydroxyl group-containing polyurethane (A) is too much because the coating film becomes too soft and re-peelability tends to be poor.
On the other hand, when the hydroxyl group-containing polyurethane (A) is relatively small, it is not preferable because the coating film becomes too hard and it becomes difficult to develop adhesiveness.
The antistatic pressure-sensitive adhesive of the present invention can contain a catalyst involved in the reaction between a hydroxyl group and an isocyanate group as in the case of obtaining the hydroxyl group-containing polyurethane (A).

  If necessary, the antistatic pressure-sensitive adhesive of the present invention may be used in combination with other resins such as acrylic resins, polyester resins, amino resins, epoxy resins, and polyurethane resins. Depending on the application, additives such as tackifiers, talc, calcium carbonate, titanium oxide, etc., colorants, ultraviolet absorbers, antioxidants, antifoaming agents, light stabilizers, etc. may be blended. good.

By using the antistatic pressure-sensitive adhesive of the present invention, a pressure-sensitive adhesive film in which a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive and a plastic film are laminated can be obtained. It can also be coated.
The pressure-sensitive adhesive film can be obtained by applying or impregnating a pressure-sensitive adhesive to various substrates, and drying and curing it. Alternatively, a pressure-sensitive adhesive is applied on the release sheet, dried, and various substrates are laminated on the surface of the pressure-sensitive adhesive layer being formed, and the reaction between the polyurethane (A) and the isocyanate compound (C) proceeds. Can also be obtained.
By applying the pressure-sensitive adhesive of the present invention to a transparent plastic film among the substrates, a surface protective pressure-sensitive adhesive film for an optical member can be suitably obtained.

  Examples of the plastic film include a polyvinyl chloride film, a polyethylene terephthalate (PET) film, a polyurethane film, a nylon film, a treated polyolefin film, and an untreated polyolefin film.

The antistatic pressure-sensitive adhesive of the present invention is preferably applied to a substrate so as to have a thickness of about 2 to 200 μm when dried and cured. If it is less than 2 μm, the ionic conductivity becomes poor, and if it exceeds 200 μm, the production and handling of the pressure-sensitive adhesive sheet becomes difficult.
In this way, an antistatic pressure-sensitive adhesive film having a pressure-sensitive adhesive layer having a surface resistance of 10 ⁰⁸ Ω / □ or less can be obtained.

  Used when an antistatic coating layer having no adhesiveness is provided between the adhesive layer and the plastic film or on the opposite side (top coat) of the plastic film that is not the adhesive layer side as shown in FIGS. Examples of the antistatic agent that can be used include metal fillers, quaternary ammonium salt derivatives, surfactants, and conductive resins.

  Examples of the metal filler include metal oxides such as tin oxide, zinc oxide, iron oxide and antimony oxide, and metals such as carbon, silver and copper. In consideration of the transparency of the coating film, tin oxide, antimony oxide and the like are preferable.

  As the quaternary ammonium salt derivative, a polymer of a (meth) acrylate monomer having a quaternary ammonium salt or a copolymer with another (meth) acrylate monomer can be used.

  The antistatic treatment coating agent layer of the present invention preferably has a thickness of 0.1 μm to 50 μm, more preferably 1 μm to 20 μm, as a coating film. If it is 0.1 μm or less, the antistatic performance cannot be sufficiently exhibited, and if it is 50 μm or more, there are problems in cost, coatability and the like.

Synthesis example 1
68 g of polyester polyol P-1010 (bifunctional polyester polyol, OH number 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, Polyether polyol G-3000B (trifunctional polyether polyol, PO chain 100 wt%, OH value 56, molecular weight 3000, manufactured by Asahi Denka Co., Ltd.) 265 g, toluene 125 g, lithium perchlorate 9 g, 2-ethylhexanoic acid as catalyst After 0.03 g of iron and 0.04 g of lead naphthenate were charged and the solution was sufficiently uniform, 24 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.) was added dropwise over 1 hour and reacted at 90 ° C. for 3 hours. It was.
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 115 g of toluene was added. This reaction solution was colorless and transparent, had a solid content of 60%, a viscosity of 3,000 cps, and an Mw (weight average molecular weight) of 50,000.

Synthesis example 2
68 g of polyester polyol P-1010 (bifunctional polyester polyol, OH number 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 265 g of polyether polyol GL-3000 (trifunctional polyether polyol, EO / PO = 20/80 wt%, OH number 56, molecular weight 3000, manufactured by Asahi Denka Co., Ltd.), 125 g of toluene, 9 g of lithium perchlorate, DBTDL0 as a catalyst 0.09 g and 0.04 g of tin 2-ethylhexanoate were charged, and after the solution was sufficiently uniform, 24 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.) was added dropwise over 1 hour, and the reaction was carried out at 90 ° C. for 2 hours. went.
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 115 g of toluene was added. This reaction solution was colorless and transparent, had a solid content of 60%, a viscosity of 3,500 cps, and a Mw (weight average molecular weight) of 60,000.

Synthesis example 3
68 g of polyester polyol P-1010 (bifunctional polyester polyol, OH number 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 265 g of polyether polyol GL-3000 (trifunctional polyether polyol, EO / PO = 20/80 wt%, OH number 56, molecular weight 3000, manufactured by Asahi Denka Co., Ltd.), 125 g of toluene, 10 g of lithium chloride, and DBTDL 0.10 g as a catalyst After adding 0.05 g of tin 2-ethylhexanoate and the solution was sufficiently uniform, 24 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.) was added dropwise over 1 hour and reacted at 90 ° C. for 2 hours. .
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 115 g of toluene was added. This reaction solution was colorless and transparent, had a solid content of 60%, a viscosity of 3,400 cps, and a Mw (weight average molecular weight) of 55,000.

Synthesis example 4
68 g of polyester polyol P-1010 (bifunctional polyester polyol, OH number 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 265 g of polyether polyol GL-3000 (trifunctional polyether polyol, EO / PO = 20/80 wt%, OH value 56, molecular weight 3000, manufactured by Asahi Denka Co., Ltd.), 125 g of toluene, 10 g of lithium perchlorate, DBTDL0 as a catalyst .10 g, 0.05 g of tin 2-ethylhexanoate, and 24 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.) were charged all at once and reacted at 90 ° C. for 3 hours.
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 115 g of toluene was added. This reaction solution was slightly cloudy and had a solid content of 58%, a viscosity of 3,300 cps, and an Mw (weight average molecular weight) of 50,000.

Synthesis example 5
A hydroxyl group-containing polyurethane solution having a colorless and transparent solid content of 60%, a viscosity of 3,500 cps, and a Mw (weight average molecular weight) of 60,000 was obtained in the same manner as in Synthesis Example 2 except that lithium perchlorate was not used.

Synthesis Example 6
325 g of polyester polyol P-2010 (bifunctional polyester polyol, OH number 56, molecular weight 2,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 125 g of toluene, 8 g of lithium perchlorate, and 0.08 g of DBTDL and 0.04 g of iron 2-ethylhexanoate were charged as a catalyst, and 24 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.) was added dropwise over 1 hour. The reaction was performed for 2 hours.
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 115 g of toluene was added. This reaction solution was cloudy and opaque, had a solid content of 60%, a viscosity of 3,000 cps, and a Mw (weight average molecular weight) of 70,000.

Synthesis example 7
68 g of polyester polyol P-1010 (bifunctional polyester polyol, OH number 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 20 g of dimethyl polyethylene glycol, 50 g of toluene, 8 g of lithium perchlorate, and 0.1 g of dioctyltin dilaurate as a catalyst were added. After the solution was sufficiently uniform, 9 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer) was added dropwise over 1 hour. Then, the reaction was performed at 90 ° C. for 2 hours.
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 15 g of toluene was added. This reaction solution was colorless and transparent, had a solid content of 60%, a viscosity of 1,500 cps, and a Mw (weight average molecular weight) of 50,000.

Synthesis example 8
68 g of polyester polyol P-1010 (bifunctional polyester polyol, OH number 112, molecular weight 1,000, manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, After charging 20 g of monomethyl polyethylene glycol, 50 g of toluene, 4 g of lithium perchlorate, and 0.1 g of dioctyltin dilaurate as a catalyst, and the liquid was sufficiently uniform, 11 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer) was added dropwise over 1 hour. Then, the reaction was performed at 90 ° C. for 2 hours.
After confirming disappearance of the isocyanate group with an infrared spectrophotometer (IR), the mixture was cooled and 15 g of toluene was added. This reaction solution was colorless and transparent, had a solid content of 60%, a viscosity of 1,300 cps, and Mw (weight average molecular weight) of 45,000.

[Example 1]
6 g of a hexamethylene diisocyanate trimethylolpropane adduct 75% ethyl acetate solution was added as a curing agent to the solution containing 100 g of the hydroxyl group-containing polyurethane obtained in Synthesis Example 1 as a solid content to obtain an adhesive.
The obtained pressure-sensitive adhesive was coated on a release paper so as to have a dry coating film thickness of 25 μm, dried at 100 ° C. for 2 minutes, and then laminated with a polyethylene terephthalate film (thickness 25 μm) on the pressure-sensitive adhesive layer being formed. The test was allowed to proceed for 1 week at room temperature to obtain a test adhesive film.
Using the pressure-sensitive adhesive film, the adhesive strength, surface resistance value, removability, and transparency were evaluated according to the following methods.

<Adhesive strength>
The release paper of the pressure-sensitive adhesive tape for test was peeled off, and the exposed pressure-sensitive adhesive layer was attached to a glass plate having a thickness of 0.4 mm at 23 ° C.-65% RH and roll-bonded according to JIS. After 24 hours, the peel strength (180 degree peel, pulling speed 300 mm / min; unit g / 25 mm width) was measured with a shopper type peel tester.

<Surface resistance value>
The release paper of the pressure-sensitive adhesive tape for test was peeled off, and the exposed pressure-sensitive adhesive layer surface was measured using a surface resistance measuring device (manufactured by Mitsubishi Chemical Corporation) (Ω / □).
Less than 10 ⁰⁸ ◎
10 ⁰⁹ -10 ¹⁰ ○
10 ¹¹ -10 ¹² △
10 ¹³ or more ×

<Removability>
After peeling off the release paper of the test adhesive tape and sticking the exposed adhesive layer to the glass plate, it was left under the condition of 60 ° C.-95% RH, cooled to 23 ° C.-65% RH, and then peeled off. The adhesive residue was visually evaluated. After peeling
No adhesive transfer to the adherend ◎
Very few ○
Partially △
Fully migrated ×
As evaluated.

<Transparency>
After peeling the release paper of the test adhesive tape and sticking the exposed adhesive layer to a glass plate, it was left under the condition of 60 ° C.-95% RH, cooled to 23 ° C.-65% RH, and then visually. evaluated.
Colorless and transparent ◎
Very slightly cloudy ○
Those that are cloudy or aggregated △
Not transparent ×

[Examples 2, 4], [Comparative Examples 1, 2, 5, 6]
A pressure-sensitive adhesive was obtained in the same manner as in Example 1 except that each polyurethane obtained in Synthesis Examples 2, 4, 5, 6, 7, and 8 was used and evaluated in the same manner as in Example 1.

[Example 3]
Using the polyurethane obtained in Synthesis Example 3, a pressure-sensitive adhesive was obtained in the same manner as in Example 1 except that 4 g of hexamethylenediamine isocyanurate was used instead of hexamethylene diisocyanate trimethylolpropane adduct as a curing agent. ,evaluated.

[Comparative Example 3]
A pressure-sensitive adhesive was obtained and evaluated in the same manner as in Example 2 except that the polyurethane obtained in Synthesis Example 2 was used and no hexamethylene diisocyanate trimethylolpropane adduct was used as a curing agent.

[Comparative Example 4]
Using the polyurethane obtained in Synthesis Example 2, a pressure-sensitive adhesive was obtained and evaluated in the same manner as in Example 2 except that 8 g of hexamethylene diisocyanate was used as a curing agent instead of hexamethylene diisocyanate trimethylolpropane adduct.

[Comparative Example 7]
A 4-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, dropping funnel, polycaprolactone diol (molecular weight 2000) 80 g, dimethyl polyethylene glycol 20 g, lithium perchlorate 4 g, and dioctyltin dilaurate 0 as a catalyst 0.1 g was charged and mixed with sufficient stirring, and then 10 g of a 75% ethyl acetate solution of hexamethylene diisocyanate trimethylolpropane adduct was added as a curing agent to obtain a pressure-sensitive adhesive, which was evaluated in the same manner as in Example 1.

As described above, it can be seen that the antistatic pressure-sensitive adhesive film of the present invention is excellent in surface resistance (conductivity), transparency and removability.
On the other hand, since the adhesive of the adhesive film shown in Comparative Example 1 does not contain an ionic compound, it has good removability and removability, but has no conductivity. Since the pressure-sensitive adhesive of the pressure-sensitive adhesive film shown in Comparative Example 2 does not have an alkylene oxide chain, the ionic compound is aggregated without being dissolved, resulting in poor transparency and surface resistance. Since the adhesive of the adhesive film shown in Comparative Example 3 did not contain any curing agent, the removability was poor. Since the adhesive for the adhesive film shown in Comparative Example 4 was not a trifunctional but a bifunctional curing agent, the cohesive force was insufficient and the removability was poor. In Comparative Example 5, since polyurethane containing a component having an alkylene oxide chain but not reacting with the diisocyanate compound (a3) was used, the cohesive force was insufficient, and further, the re-peelability was poor because it bleeds to the adherend. became. Since Comparative Example 6 had an alkylene oxide chain but had only one hydroxyl group in the molecule that reacted with the diisocyanate compound (a3), the cohesive force was insufficient and the removability deteriorated as described above.
In Comparative Example 7, after the polyurethane (A) was obtained in advance as in the present invention, the polyurethane (A) was further crosslinked with an isocyanate component between the release paper and the polyethylene terephthalate film to form an adhesive layer. Instead, the adhesive layer is formed by reacting the hydroxyl component and the isocyanate component between the release paper and the polyethylene terephthalate film, so that the conductivity is excellent, but the cohesive force is insufficient and the removability is low. It is defective.

: An antistatic pressure-sensitive adhesive film in which an antistatic polyurethane pressure-sensitive adhesive layer is laminated on the polarizing plate side of the PET film. : An antistatic pressure-sensitive adhesive film in which an antistatic polyurethane pressure-sensitive adhesive layer is laminated on both the polarizing plate side and the opposite side of the PET film. : Antistatic pressure-sensitive adhesive film in which an antistatic coating agent layer and an antistatic polyurethane pressure-sensitive adhesive layer are laminated on the polarizing plate side of the PET film. An antistatic pressure-sensitive adhesive film in which an antistatic polyurethane pressure-sensitive adhesive layer is laminated on the polarizing plate side of the PET film and an antistatic coating layer is laminated on the opposite side.

Explanation of symbols

1: Plastic film substrate (PET)
2: Antistatic polyurethane adhesive layer 3: Polarizing plate 4: Antistatic coating layer

Claims (14)

A pressure-sensitive adhesive layer formed of an antistatic polyurethane pressure-sensitive adhesive containing a hydroxyl group-containing polyurethane (A), an ionic compound (B) and a trifunctional isocyanate compound (C) is provided on at least one surface of a plastic film. Laminated antistatic adhesive film. Hydroxyl group-containing polyurethane (A) obtained by reacting a polyol component (a1) having an alkylene oxide chain, a polyester polyol component (a2), and a diisocyanate compound (a3) under hydroxyl-excess conditions. The antistatic pressure-sensitive adhesive film according to claim 1, wherein The antistatic pressure-sensitive adhesive film according to claim 1 or 2, wherein the trifunctional isocyanate compound (C) is a trimethylolpropane adduct or isocyanurate. The antistatic pressure-sensitive adhesive film according to any one of claims 1 to 3, wherein the alkylene oxide chain in the polyol component (a1) is an ethylene oxide chain and a propylene oxide chain. The antistatic pressure-sensitive adhesive film according to claim 4, wherein a weight ratio of the ethylene oxide chain to the propylene oxide chain is EO / PO = 10/90 to 50/50. The antistatic pressure-sensitive adhesive film according to any one of claims 1 to 5, wherein the polyol component (a1) is a trifunctional polyether polyol. The antistatic pressure-sensitive adhesive film according to any one of claims 1 to 6, comprising 0.1 to 50% by weight of the ionic compound (B) in a solid content of 100% by weight of the antistatic polyurethane pressure-sensitive adhesive. The antistatic pressure-sensitive adhesive film according to any one of claims 1 to 7, wherein the ionic compound (B) is an inorganic salt. The hydroxyl group-containing polyurethane (A) comprises a polyol component (a1), a polyester polyol component (a2) and a diisocyanate compound (a3) having an alkylene oxide chain, and the total hydroxyl group / isocyanate group of the polyol components (a1) and (a2). The antistatic pressure-sensitive adhesive film according to claim 1, which is reacted at an equivalent ratio of = 65/35 to 50/50. 10. The molar ratio of the polyol component (a1) having an alkylene oxide chain and the polyester polyol component (a2) is (a1) / (a2) = 90/10 to 40/60. The antistatic pressure-sensitive adhesive film according to any one of the above. The antistatic pressure-sensitive adhesive film according to any one of claims 1 to 9, wherein the hydroxyl group-containing polyurethane (A) has a weight average molecular weight of 30,000 to 150,000. The antistatic pressure-sensitive adhesive film according to any one of claims 1 to 11, which is used for protecting a surface of an optical member or an electronic member. A method for protecting the surface of an optical member or an electronic member using the antistatic pressure-sensitive adhesive film according to claim 1. In the first component including the polyol component (a1) having an alkylene oxide chain, the polyester polyol component (a2) and the ionic compound (B),
The second component containing the diisocyanate compound (a3) is added in a range where the isocyanate groups are relatively small relative to the total hydroxyl groups of the polyol components (a1) and (a2),
The first component and the second component are reacted to obtain a hydroxyl group-containing polyurethane (A),
Next, a polyurethane composition formed by adding the trifunctional isocyanate compound (C),
A method for producing an antistatic pressure-sensitive adhesive film, which is coated on a release sheet, dried, laminated with a plastic film on the surface of the pressure-sensitive adhesive layer, and reacted with a hydroxyl group-containing polyurethane (A) and a trifunctional isocyanate compound (C). .

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