Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
  • C09J175/04—Polyurethanes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/48—Polyethers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/48—Polyethers
  • C08G18/4804—Two or more polyethers of different physical or chemical nature
  • C08G18/4812—Mixtures of polyetherdiols with polyetherpolyols having at least three hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
  • C08G18/6505—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen the low-molecular compounds being compounds of group C08G18/32 or polyamines of C08G18/38
  • C08G18/6511—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen the low-molecular compounds being compounds of group C08G18/32 or polyamines of C08G18/38 compounds of group C08G18/3203
  • C08G18/6517—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen the low-molecular compounds being compounds of group C08G18/32 or polyamines of C08G18/38 compounds of group C08G18/3203 having at least three hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
  • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
  • C08G18/6603—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
  • C08G18/6607—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
  • C08G18/6611—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203 having at least three hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
  • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
  • C08G18/6666—Compounds of group C08G18/48 or C08G18/52
  • C08G18/667—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
  • C08G18/6674—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
  • C08G18/6677—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203 having at least three hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
  • C08G18/75—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic
  • C08G18/751—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring
  • C08G18/752—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group
  • C08G18/753—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group containing one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate group
  • C08G18/755—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group containing one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate group and at least one isocyanate or isothiocyanate group linked to a secondary carbon atom of the cycloaliphatic ring, e.g. isophorone diisocyanate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/02—Non-macromolecular additives
  • C09J11/06—Non-macromolecular additives organic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
  • C09J175/04—Polyurethanes
  • C09J175/08—Polyurethanes from polyethers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks

Definitions

• the present invention relates to a pressure-sensitive adhesive, in particular for bonding optical components, according to claim 1.
• Pressure-sensitive adhesives are used very widely today. For example, there are a wide variety of applications in the industrial sector. Adhesive tapes based on pressure-sensitive adhesives are used in the electronics sector or in the consumer electronics sector. Due to the high number of pieces of pressure-sensitive adhesive tapes can be processed very quickly and easily, so that other processes, such. Riveting or welding, too expensive. In addition to the normal connection function, these pressure-sensitive adhesive tapes may also have to take on additional functions. So this can be e.g. be a thermal conductivity, an electrical conductivity or an optical function. In the latter case, e.g. Pressure-sensitive adhesive tapes are used, which have light-absorbing or light-reflecting functions. Another optical function is, for example, a suitable light transmission.
• pressure-sensitive adhesive tapes and PSAs are used, which are very transparent, have no intrinsic color and also have high light stability.
• a pressure sensitive adhesive for optical purposes in addition to the connection function has the function of excluding air, since air has a refractive index of 1 and the optical films or glasses have a generally much higher refractive index. The difference in the refractive indices leads to a reflection during the transition from air to the optical component, which reduces the transmission.
• One way to solve this problem is to use antireflective coatings, which facilitate the passage of light into the optical component and reduce the reflection.
• an optical pressure-sensitive adhesive which has a similar refractive index as the optical component. As a result, the reflection on the optical component is significantly minimized and the transmission increased.
• a typical application is, for example, the bonding of touch panels on the LCD or OLED display (indium tin oxide) for capacitive touch panels. Further typical applications are the use as single-sided pressure-sensitive adhesive tape for reinforcing glass as splinter protection, the bonding of ITO films (indium tin oxide) for capacitive touch panels or surface protection films for optical films, such as, for example, polarizer films.
• optical components such as films or glasses, have a relatively high refractive index, so that pressure-sensitive adhesives are required which likewise have a high refractive index. This is how most of them are visually bonded
• Substrates have a refractive index of 1, 45 - 1, 70 on. Another requirement is the neutrality of the PSA formulation. So should the PSA no
• Contain acidic functions e.g. Contact with ITO films may negatively affect the electrical conductivity over a longer period of time.
• UV stability e.g. for outdoor applications also used optical PSAs, but exposed to UV light.
• acrylate PSAs For transparent bonds, a large number of acrylate PSAs are known which are used in the optical range and have very different refractive indices.
• No. 6,703,463 describes acrylic PSAs which have a refractive index below 1.40. This is achieved by fluorinated acrylate monomers. The refractive index is thus significantly below the desired range.
• JP 2002-363523 A describes acrylate PSAs having a refractive index between 1.40 and 1.46. Again, fluorinated acrylate monomers are used. Also, this refractive index is well below the desired range.
• various acrylic pressure-sensitive tapes e.g. 3M 8141. These conventional acrylate PSAs are in a refractive index range of 1.47 to 1.48.
• US 2002/0098352 A1 describes acrylic PSAs with aromatic comonomers which have a refractive index of 1.49-1.60. This is within the desired range, but there are also disadvantages associated with the aromatics. This allows them to absorb UV light in the short-wave range, which negatively influences the transmission stability and the tendency to yellowing.
• EP 1 652 889 A1 describes PSA compositions based on polydiorganosiloxanes for optical applications. Silicone compounds generally have a low refractive index, so that these adhesives are not optimally suited for optical applications.
• PSAs are known as pressure-sensitive adhesives. Based on polyurethane, hydroxyl-bearing double-bond-containing polyol components are used. Polyurethane pressure-sensitive adhesives based thereon are listed, for example, in JP 02003476 A, WO 98/30648 A1, JP 59230076 A, JP 2001-146577 A, US Pat. No. 3,879,248 A, US Pat. No. 3,743,616 A, US Pat. Nos. 3,743,617, 5,486,570 and 3,515,773 , A disadvantage is the oxidative sensitivity of these pressure-sensitive adhesives, caused by the double bonds in the polymer main chain. This leads after some time to a laking and / or yellowing and / or blunting the pressure sensitive surface.
• a suitable adhesive should have a high optical transparency and a high UV stability.
• the invention relates to a pressure-sensitive adhesive based on polyurethane, in which the polyurethane is composed of the following catalytically reacted starting materials in the ratios indicated: a) at least one aliphatic or alicyclic polyisocyanate, the functionality of which is in each case less than or equal to 3 b) a combination of at least one polypropylene glycol diol and at least one polypropylene glycol triol, wherein the ratio of the number of hydroxyl groups of the diol component to the number of hydroxyl groups of the triol component is less than 10, preferably between 0.2 and 5, wherein the ratio of the number of isocyanate groups to the total number of hydroxyl groups is between 0.65 and 1, 2, preferably between 0.95 and 1, 05, more preferably between 1, 0 and 1, 05, and wherein the diols and triols are each alternatively selected and combined as follows:
• Diols having a molecular weight of less than or equal to 1000 are combined with triols whose molecular weight is greater than or equal to 1000, preferably greater than or equal to 3000,
• Diols with a molecular weight greater than 1000 are combined with triols whose molecular weight is less than 1000.
• a carbodiimide with a proportion of 0.25-2.5 wt .-%
• the PSA thus has in particular no aromatic comonomers, yet a high refractive index, in particular greater than 1, 48 is adjustable.
• the light transmission of such a PSA formulation is in particular greater than 86% and the haze at less than 5% according to ASTM D 1003.
• Pressure-sensitive adhesive in particular suitable for bonding in the optically transparent region.
• the PSA is characterized by a high refractive index, high transmission and high UV stability.
• the PSA is preferably used for bonding optical components in consumer electronics goods.
• T ( ⁇ ) + p ( ⁇ ) + a ( ⁇ ) 1
• T ( ⁇ ) describes the proportion of the transmitted light
• p ( ⁇ ) the proportion of the reflected light
• a ( ⁇ ) the proportion of the absorbed light ( ⁇ : wavelength)
• the total intensity of the incident light is normalized to 1.
• Optical components designed for transmission should be characterized by values of T ( ⁇ ) close to unity. This is achieved by reducing p ( ⁇ ) and a ( ⁇ ) in magnitude.
• Polyurethane-based pressure-sensitive adhesives normally have no appreciable absorption in the visible range, ie in the wavelength range between 400 nm and 700 nm. This can be easily checked by measurements with a UV-Vis spectrophotometer. Of crucial interest is therefore p ( ⁇ ). Reflection is an interface phenomenon that depends on the refractive indices n dl of two contacting phases i and is described by the Fresnel equation:
• aliphatic or alicyclic polyisocyanates or polyisocyanates with not aromatically bound isocyanate groups be used.
• aliphatic or alicyclic polyisocyanates are suitable in order to also produce the other desired property profile of the polyurethane PSA in accordance with the requirements of optical applications.
• the surface-specific selectivity of the pressure-sensitive adhesive properties can be adjusted by using aliphatic or alicyclic polyisocyanates, but also pressure-sensitive adhesives having high transparency.
• aliphatic or alicyclic diisocyanates are used as the polyisocyanates. These form a better network and thus enable an optimization of the adhesive properties in terms of cohesion and reversibility.
• aliphatic or alicyclic diisocyanates each having asymmetrical molecular structure, in which therefore the two isocyanate groups each have a different reactivity.
• the otherwise typical tendency for tacky polyurethanes to "greasy" is significantly reduced by the use of aliphatic or alicyclic diisocyanates with unsymmetrical molecular structure
• Unsymmetrical molecular structure means that the molecule has no symmetry elements (for example, mirror planes, symmetry axes, symmetry centers), that is, no symmetry operation can be carried out, which generates a congruent with the starting molecule molecule.
• pressure-sensitive adhesive of suitable polyisocyanates are: butane-1,4-diisocyanate, tetramethoxybutane-1,4-diisocyanate, hexane-1,6-diisocyanate,
• isophorone diisocyanate is used.
• aliphatic diols are preferably used.
• a combination of at least one polypropylene glycol diol and at least one polypropylene glycol triol is used to produce high bond strength, high transmission polyurethanes.
• polypropylene glycols it is possible to use all commercial polyethers based on propylene oxide and a difunctional initiator in the case of the diols and of a trifunctional starter in the case of the triols.
• these include both the conventional, that is usually prepared with a basic catalyst such as potassium hydroxide, polypropylene glycols, as well as the particularly pure polypropylene glycols, the DMC (double metal cyanide) catalyzed produced, and their preparation, for example, in US 5,712,216 A, US 5,693,584 A, WO 99/56874 A1, WO 99/51661 A1, WO 99/59719 A1, WO 99/64152 A1, US 5,952,261 A, WO 99/64493 A1 and WO 99/51657 A1.
• the bond strength can be influenced and adjusted in accordance with the application. Surprisingly, it was found that the
• Adhesive strength increases, the higher the ratio of the number of diol-OH groups to the
• Triol-OH groups is.
• the bond strength range which can be adjusted within the specified limits, is approximately in the range of 1.0 to 15.0 N / cm measured on steel according to PSTC-1 (see description of test methods) and in
• a bismutcarboxylat- or bismutcarboxylatderivat restroomn catalyst or catalyst mixture whose use for accelerating polyurethane reactions is known.
• Such a catalyst substantially controls the pressure-sensitive adhesive properties of the polyurethane in such a way that a surface-specific selectivity of the pressure-sensitive adhesive properties is achieved.
• bismuth carboxylates are bismuth trisdodecanoate, bismuth trisdecanoate, bismuth trisneodecanoate, bismuth trisoctanoate, bismuth trisisooctanoate, bismuth trishexanoate, bismuth trispentanoate, bismuth trisbutanoate, bismuth trispropanoate or bismuth trisacetate.
• the polyurethane-based PSA contains further formulation constituents such as, for example, additional catalysts or rheological additives.
• rheological additives examples include fumed silicas, phyllosilicates (for example bentonites), high molecular weight polyamide powders or castor oil derivative powders.
• care must be taken that they are chosen so that they do not adversely affect the transmission of the PSA. This is achieved by having these additives on the order of magnitude (spatial extent) which is in the range of the wavelength of visible light (400-800 nm) or less.
• care must also be taken to ensure that these substances have no tendency to migrate towards the substrate to be bonded so that staining does not occur in this way. For the same reason, the concentration of these substances, in particular the liquid, is to be kept as low as possible in the overall composition.
• plasticizers or tackifier resins should therefore be avoided if possible - in individual cases, however, their use may still be useful.
• the light stabilizers c) are selected from the group of substituted triazines.
• the triazines are chosen so that they have a good compatibility with the polyurethanes. This is e.g. achieved by substituents.
• preferred embodiments of the triazines have at least one aromatic substituent, more preferably at least 2 aromatic substituents, and most preferably 3 aromatic substituents. These aromatics themselves may in turn be substituted with at least one aliphatic substituent. In the simplest form, this may be a methyl group.
• hydroxyl groups such as hydroxyl groups, ether groups, aliphatic chains having 2 to 20 C atoms, which are linear, branched or cyclic and in turn may contain one to 5 oxygen atoms in the form of ether groups, hydroxy groups, ester groups, carbonate groups.
• sunscreens are available from Ciba under the trade name Tinuvin®.
• Tinuvin® 400, Tinuvin® 405, Tinuvin® 479 and Tinuvin® 477 suitable light stabilizers that can be used.
• Other light stabilizers used are hindered amines. Particular preference is given to using substituted N-methylpiperidine derivatives. These are sterically hindered, for example in position 1 and 5, by aliphatic groups, such as methyl groups. More preferably, four methyl groups are used for steric hindrance. To achieve good solubility with the polyurethane, as well as to increase the evaporation temperature, become long aliphatic substituents used.
• the substituents may be linear, cyclic or branched, contain up to 20 carbon atoms, contain up to 8 O atoms, which are for example in the form of ester groups, ether groups, carbonate groups or hydroxyl groups.
• For the effect compounds with only one N-methylpiperidine can be used. But there are also known dimeric N-methylpiperidine derivatives which have a sunscreen function. These can also be combined with the monomeric compounds.
• sterically hindered phenols are used as anti-aging agent d.
• Sterically hindered phenols have in a preferred embodiment in both ortho positions to the hydroxy group tert-butyl groups.
• the sterically hindered phenols should be additionally substituted.
• the substituents may be linear, cyclic or branched, contain up to 20 C atoms, contain up to 8 O atoms, e.g. in the form of ester groups, ether groups, carbonate groups or hydroxy groups.
• Commercially available compounds are e.g. Irganox® 1 135 or Irganox® 1330 from Ciba.
• carbodiimides are added to the polyurethanes.
• numerous carbodiimides such as dicyclohexylcarbodiimide (boiling point 122 ° C) or N 1 N-diisopropylcarbodiimide (boiling point 148 ° C) are not suitable because they have too high a vapor pressure.
• 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride is preferably used, which has a melting point of about 110 ° C.
• polymeric carbodiimides are also known, as are commercially available, for example, from Rheinhausen as Stabaxol® P 200.
• the premixed polyaliphatic glycol combination (polyol component) and, in a container B, essentially the isocyanate component are initially introduced in a container A, with the other formulation constituents optionally having been previously admixed to these components in a customary mixing process.
• the polyol and the isocyanate component are conveyed by precision pumps through the mixing head or the mixing tube of a multi-component mixing and dosing, where homogeneously mixed and reacted.
• the mixed, chemically reactive components are applied immediately thereafter to a web-shaped carrier material, which preferably moves at a constant speed.
• the type of carrier material depends on the article to be produced.
• the coated with the reactive polyurethane composition carrier material is passed through a heat channel in which the polyurethane composition cures to PSA.
• the application weight of the polyurethane compound is freely selectable. It depends on the article to be produced.
• the coated carrier material is finally wound up in a winding station.
• the process described makes it possible to work solvent and water-free.
• the solvent and water-free working is the preferred method, but not mandatory.
• the components can be diluted appropriately.
• the back side of the sheet material may be precoated with a release varnish or may carry a separating coextruded or extruded backsize coating.
• FIG. 1 a single-sided pressure-sensitive adhesive tape
• FIG. 2 a pressure-sensitive adhesive tape on both sides
• FIG. 3 shows a carrier-free pressure-sensitive adhesive tape (transfer adhesive tape).
• the pressure-sensitive adhesive tape 1 shows a single-sided adhesive pressure-sensitive adhesive tape 1 for use in the bonding of optical components, in particular of optical films.
• the pressure-sensitive adhesive tape 1 has an adhesive layer 2 which has been produced by coating one of the previously described pressure-sensitive adhesive onto a carrier 3.
• the PSA coating is preferably between 5 and 250 g / m 2 .
• the pressure-sensitive adhesive has a transmittance of at least 86%, especially in the visible range of light, making it particularly suitable for optical use.
• a transparent carrier 2 is also used as carrier 2.
• the carrier 2 is thus also transparent in the visible light range, and therefore preferably has a transmittance of at least 86%.
• a release film which covers the adhesive layer 2 before using the pressure-sensitive adhesive tape 1 and protects. The release film is then removed from the adhesive layer 2 prior to use.
• the transparent PSA may preferably be protected with a release film. Furthermore, it is possible that the carrier film is provided with one or more coatings.
• the product structure shown in FIG. 2 shows a pressure-sensitive adhesive tape 1 with a transparent carrier 3, which is coated on both sides with a pressure-sensitive adhesive and thus has two adhesive layers 2.
• the PSA per side is again preferably between 5 and 250 g / m 2 .
• At least one adhesive layer 2 is preferably covered with a release film. If the adhesive tape is rolled up, it can also cover the second adhesive layer 2 if necessary. But it can also be provided more separation films.
• the carrier film is provided with one or more coatings. Furthermore, only one side of the pressure-sensitive adhesive tape may be provided with the inventive PSA and on the other side another transparent PSA may be used.
• the product structure shown in Fig. 3 shows a pressure-sensitive adhesive tape 1 in the form of a transfer adhesive tape, i. a carrier-free pressure-sensitive adhesive tape 1.
• a transfer adhesive tape i. a carrier-free pressure-sensitive adhesive tape 1.
• Pressure-sensitive adhesive is coated on one side on a release film 4 and thus forms a
• the pressure-sensitive adhesive coating is usually between
• This pressure-sensitive adhesive layer 2 is still covered on its second side with a further release film. To use the pressure sensitive adhesive tape, the release liners are then removed.
• release films for example, release papers or the like. Can be used. In this case, however, the surface roughness of the release paper should be reduced in order to realize the smoothest possible PSA side.
• a carrier films As a carrier films, a variety of highly transparent polymer films can be used. In particular, special high-transparency PET films can be used. For example, films from Mitsubishi with the trade name Hostaphan TM or the company Toray with the trade name Lumirror TM are suitable.
• the Haze value a measure of the haze of a substance, should in a preferred design have a value of less than 5% according to ASTM D 1003.
• a high haze value means low visibility through the corresponding substance.
• the light transmission is preferably at 550 nm at greater than 86%, particularly preferably greater than 88%.
• a other very preferred species of polyesters are the polybutylene terephthalate films.
• polyester films In addition to polyester films, it is also possible to use highly transparent PVC films. These films may contain plasticizers to increase flexibility. Furthermore, PC, PMMA and PS films can be used. In addition to pure polystyrene, other comonomers, such as styrene, can be used to reduce the tendency to crystallize in addition to styrene. Butadiene, use.
• polyethersulfone and polysulfone films can be used as support materials. These are e.g. from BASF under the trade names Ultrason TM E and Ultrason TM S. Furthermore, particularly preferably highly transparent TPU films can also be used. These are e.g. commercially available from the company Elastogran GmbH. It is also possible to use highly transparent polyamide and copolyamide films and also films based on polyvinyl alcohol and polyvinyl butyral.
• multilayer films may also be used, e.g. be prepared coextruded.
• the abovementioned polymer materials can be combined with one another.
• the films can be treated.
• Coats may be made, for example with zinc oxide, or it may be applied coatings or adhesion promoters.
• Another possible additive is UV protection agents, which may be present as additives in the film or may be applied as a protective layer.
• the film thickness is in a preferred embodiment between 4 .mu.m and 150 .mu.m, more preferably between 12 .mu.m and 100 .mu.m.
• the carrier film may, for example, also have an optical coating.
• an optical coating are in particular coatings that reduce the reflection. This is achieved for example by lowering the refractive index difference for the transition air / optical coating.
• MgF 2 is used as a single layer to minimize reflection.
• MgF 2 has a refractive index of 1.35 at 550 nm.
• metal oxide layers in different layers can be used to minimize the reflection. Typical examples are layers of SiO 2 and TiO 2 .
• Other suitable oxides include hafnium oxide (HfO 2 ), magnesium oxide (MgO), silicon monoxide (SiO), zirconium oxide (ZrO 2 ) and tantalum oxide (Ta 2 Os).
• nitrides can also be used, such as SiN x .
• fluorinated polymers can also be used as low refractive index layers. These are also very often used in combination with the aforementioned layers of SiO 2 and TiO 2 .
• sol-gel processes can be used.
• silicones, alkoxides and / or metal alkoxides are used as mixtures and coated therewith. Siloxanes are thus also a widely used basis for reflection-reducing layers.
• the typical coating thicknesses are between 2 and 1000 A (0.2 to 100 nm), preferably between 100 and 500 A (10 to 50 nm). In some cases - depending on the layer thickness and chemical composition of the individual or the plurality of optical layers - color changes, which in turn can be controlled or changed by the thickness of the coating. For the solution-coated siloxane process, layer thicknesses greater than 1000 A (100 nm) can also be achieved.
• Another way to reduce reflection is to create certain surface structures.
• porous coating and the production of stochastic or periodic surface structures.
• the distance between the structures should be clearly none other than the wavelength range of the visible light.
• the optical layers can be vacuum-coated, such as by vacuum deposition techniques.
• CVD Chemical Vapor Deposition
• PIAD Plasma Ion Assisted Deposition
• release films To protect the open PSA, it is preferably covered with one or more release films.
• release papers may also be used, although not very preferably, such as, for example, glassine, HDPE or LDPE tow papers, which in one embodiment have siliconization as the release liner.
• a release film is used.
• the release film has in a very preferred design a siliconization as a release agent.
• the film separator should have an extremely smooth surface, so that no structuring of the PSA by the release liner is made. This is preferably achieved through the use of antiblock-free PET films in combination of solution-coated silicone systems.
• pressure-sensitive adhesives and pressure-sensitive adhesive tapes described above are particularly suitable for use in optical applications, wherein preferably permanent bonds with residence times of more than one month are made.
• a single-sided pressure-sensitive adhesive tape is particularly suitable for bonding e.g. Glass windows, wherein the pressure-sensitive adhesive tape can take the function of splinter protection or sunscreen has UV and heat-absorbing effect.
• double-sided pressure-sensitive adhesive tapes can be used to bond touch panels to displays
• membrane touch switches can be provided with protective films
• anti-scratch films can be glued on
• ITO films can be bonded for capacitive touch panels.
• the device was operated in conjunction with a thermostat from Lauda.
• the peel strength (bond strength) was tested according to PSTC-101.
• the adhesive tape is applied to a glass plate.
• a 2 cm wide strip of adhesive tape is glued by rolling it twice over twice with a 2 kg roll.
• the plate is clamped and the self-adhesive strip on its free end to a tensile testing machine subtracted at a peel angle of 180 ° at a speed of 300 mm / min.
• the force is given in N / cm.
• Haze is determined according to ASTM D1003.
• the composite of pressure-sensitive adhesive and glass plate is irradiated in the size 4 x 20 cm 2 for 300 h with Osram Ultra Vitalux 300 W lamps at a distance of 50 cm.
• Irradiation is determined according to test method C, the transmission.
• the pressure-sensitive adhesive is used as a one-sided pressure-sensitive adhesive tape (50 g / m 2 coat, 50 ⁇ m
• PET film of the type Mitsubishi RNK 50 Glued air-free to a glass plate.
• Test strip has the dimension 2 cm wide and 10 cm long. It is determined according to test method B, the bond strength to glass.
• Such a bonding compound is placed in a removable air conditioning cabinet and stored for 1000 cycles.
• One cycle includes: storage at -40 ° C for 30 minutes heating up to 85 ° C within 5 minutes - storage at 85 ° C for 30 minutes cooling to -40 ° C within 5 minutes
• the PSA is adhesively bonded as a one-sided pressure-sensitive adhesive tape (50 g / m 2 , 50 ⁇ m PET film of the type Mitsubishi RNK 50) to a glass plate free of air bubbles.
• the test strip has the dimension 2 cm wide and 10 cm long. It is determined according to test method B, the bond strength to glass. At the same time, such a bonding compound is placed in an alternating climate chamber and stored for 1000 hours at 60 ° C. and 95% relative humidity. Subsequently, the bond strength according to test method B is determined again.
• the coatings were made in the examples on a conventional continuous coating laboratory coating equipment.
• the coating was carried out in a clean room ISO 5 according to standard ISO 14644-1.
• the web width was 50 cm.
• the coating gap width was variably adjustable between 0 and 1 cm.
• the length of the heat channel was about 12 m.
• the temperature in the heat channel was divisible into four zones and each freely selectable between room temperature and 120 C.
• a conventional multicomponent mixing and dosing plant with a dynamic mixing system was used.
• the mixing head was designed for two liquid components.
• the mixing rotor had a variable speed up to max. about 5000 rpm.
• the metering pumps of this plant were gear pumps with a delivery capacity of max. about 2 l / min.
• the polyol components were manufactured in a conventional heated and evacuated mixing vessel. During the approximately two-hour mixing process, the temperature of the mixture was adjusted to about 70 ° C, vacuum was applied to degas the components.
• Table 1 Base materials used for the production of the polyurethane pressure-sensitive adhesives with trade names and manufacturers
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Comparative Example 2 (V2) Polyurethane composition: NCO / OH ratio: 0.95
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Comparative Example 4 (V4) Polyurethane composition: NCO / OH ratio: 0.99
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Example 1 Polyurethane composition: NCO / OH ratio: 0.99
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Example 2 Polyurethane composition: NCO / OH ratio: 0.99
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Example 3 Polyurethane composition: NCO / OH ratio: 0.99
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Polyurethane composition NCO / OH ratio: 0.74
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Example 5 Polyurethane composition: NCO / OH ratio: 1.0
• test samples were coated with 50 g / m 2 polyurethane pressure-sensitive adhesive on a 75 micron thick polyester release film.
• Table 3 shows that all the inventive examples are suitable for permanent bonding.
• comparative examples V9 and V1 1 clearly show too low adhesive forces.
• V9 is an example of the fact that the right composition of the polycyanates and polyols is crucial to achieve a sufficiently high bond strength.
• V1 1 is again an example of the microphase separation produced by the incompatibility of the resin, which reduces the bond strengths that can be achieved.
• Table 5 shows that the comparative examples V1 to V4 as well as V7 to V1 1 show a significant drop in transmission.
• different light stabilizers based on sterically hindered amines were used, but obviously they did not achieve adequate stabilization, even in different combinations and with different proportions. Due to the yellowing after the light resistance test, such adhesive formulations are not suitable for optical applications.
• all inventive examples show a very good stability and no or only a very small drop in transmission. This also applies to Comparative Examples V4 and V5, which additionally contain sterically hindered phenols with sulfur in the side groups.
• Another aging test involves an alternating climate test. Here, the situation is simulated that the adhesive is exposed to a very different climate, which in turn may be the case in outdoor optical applications. The climate change test was carried out according to test method F. The results are shown in Table 6.
• the measurement results show that only very specific pressure-sensitive adhesives with very defined adhesive formulations can meet all requirements. It turned out that also anti-aging agents show efficacy in certain combinations. Also carbodiimide additives required to achieve moisture resistance. In addition, all of the inventive examples meet the requirements with regard to optical transparency and bond strengths also for permanent applications.
• inventive examples are thus very well suited for use in optical applications.
• Typical applications are e.g. glass window gluing for splinter protection or as sunlight protection, or the bonding of touch panels or membrane touch switches or the bonding of anti-scratch films or the bonding of ITO films for capacitive touch panels.
• adhesions were once again made to an ITO film from Nitto Denko and then, in contact with Examples 1 to 5, the electrical conductivity as a function of time and at 60 ° C. storage was determined. The measurements showed that the electrical conductivity remained constant within a range of ⁇ 10% at 60 ° C for 4 weeks.
• the inventive examples show a very good neutrality towards ITO and do not damage the electrical conductivity of this material.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Adhesive Tapes (AREA)
• Polyurethanes Or Polyureas (AREA)
• Laminated Bodies (AREA)

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• 2009
  • 2009-02-20 DE DE102009009757A patent/DE102009009757A1/de not_active Withdrawn
• 2010
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  • 2010-02-05 CN CN201080010956XA patent/CN102348734A/zh active Pending
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