Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
  • B32B17/10559—Shape of the cross-section
  • B32B17/10577—Surface roughness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/10165—Functional features of the laminated safety glass or glazing
  • B32B17/10247—Laminated safety glass or glazing containing decorations or patterns for aesthetic reasons
• • 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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/22—Plastics; Metallised plastics
• • 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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
• • E—FIXED CONSTRUCTIONS
  • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
  • E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
  • E06B9/00—Screening or protective devices for wall or similar openings, with or without operating or securing mechanisms; Closures of similar construction
  • E06B9/24—Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blinds
• • 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
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
  • C09J2301/12—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers
  • C09J2301/122—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers the adhesive layer being present only on one side of the carrier, e.g. single-sided adhesive tape
• • 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
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
  • C09J2301/302—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C

Definitions

• the present invention relates to an adhesive sheet which can be attached as a decorative sheet onto window glass and the like, for protection of privacy, prevention of glass breakage, prevention of fragment scattering and for protective effects such as heat shielding, soundproofing and vibration resistance.
• the present invention further relates to a window glass structure which employs this type of adhesive sheet.
• Japanese Unexamined Patent Publication (Kokai) No. 7-42456 discloses a heat shielding sheet for windows and other glass objects, wherein the surface base is formed from a synthetic resin sheet and a grid-like spacer is integrated with the sheet, with an adhesive applied onto the tips of the spacer.
• This sheet forms airtight spaces between the base, spacer and glass when attached to window glass, and can therefore provided a heat shielding effect.
• the spacer used here consists of a relatively hard resin, it has a poor breakage-preventing and vibration resistance effect for window glass.
• the application step for the adhesive is also plagued with difficulties. Adhesive sheets and the like wherein the adhesive layers themselves have irregularities are well-known.
• 7-126582 discloses an adhesive tape provided with a support and an adhesive layer formed on the support having irregularities in an orderly form and arrangement, having a pitch of 1 mm or less on the surface.
• the irregularities on this adhesive tape have a very fine structure consisting of protrusions with a height of 20 gm or less and pits with a depth which is 10-90% of the height of the protrusions, while the adhesive comprises an n-butyl acrylate/acrylic acid copolymer and a polyisocyanate compound in a proportion of 1 g to 100 g of the copolymer.
• the adhesive layer of the article is formed by ultraviolet polymerization using as the starting monomers 90 parts of isooctyl acrylate, 10 parts of acrylic acid and a relatively small amount of a crosslinking agent (0.1 part of 1,6-hexanediol diacrylate).
• International Patent Publication (WO) 95/11655 discloses a tape having an adhesive layer with a microsized structural surface similar to the one mentioned above.
• the conventional type of adhesive sheets mentioned above can provide some degree of effect when attached to window glass, but they are not capable of achieving at the same time the effects as a protective sheet particularly desired in the technical field, namely those of improving the decorative properties, preventing breakage of glass and its scattering, and providing heat shielding, soundproofing and vibration resistance. Furthermore, they have provided no concrete suggestion of additionally providing a privacy-protecting effect (an effect of blocking the view from outside to inside when attached to window glass or the like).
• the present invention provides an adhesive sheet comprising (i) a base with two opposite main sides and (ii) a plurality of protrusions made of an adhesive crosslinked polymer, which are arranged in a pattern on the first main side of the base, wherein when the elastic modulus G of the protrusions is measured by dynamic viscoelasticity measurement with a frequency of 1 rad/sec and in shear mode, the elastic modulus G is in the range of 5 x 10 ⁇ - 4 x 10 ⁇ dyn /cm ⁇ (at 25°C) and the reduction in the logi oG is less than 1.0 (at 25-125°C), the pattern formed by the protrusions can be observed through the base from the second main side thereof on which no such protrusions are arranged, and the surface roughness Ra of the sections of the first main side of the base on which no such protrusions are arranged is in the range of 0.4-200 ⁇ m as measured using a contact needle surface roughness tester under conditions with a contact needle R
• the plurality of protrusions arranged on one main side of the base are preferably arranged in such a pattern that a plurality of geometrically shaped depressions are formed around them and so that the sections where no protrusions are arranged constitute the floors of the depressions.
• the floors of the depressions have the surface roughness Ra specified above, and are of a sufficient roughness as to cause light diffusion.
• the window glass structure according to the invention may be any of a variety of the forms mentioned below, and for example, a combination of one adhesive sheet and one window glass may be used, or one adhesive sheet may be placed between two window glasses, i.e. the second main side of the adhesive sheet which has no protrusions may be also attached to the surface of a separate window glass. Two or even more adhesive sheets of the invention may also be used if necessary for the window glass structure.
• Fig. 1 is a perspective view of an example of an adhesive sheet according to the invention.
• Fig. 2 is a cross-sectional view of the adhesive sheet of Fig. 1 along line II-II.
• Fig. 3 is a perspective view of an example of a window glass structure according to the invention.
• Fig. 4 is a perspective view of another example of a window glass structure according to the invention.
• Fig. 5 is a graph showing the heat shielding effects of adhesive sheets according to the invention. DETAILED DESCRIPTION OF THE INVENTION
• the adhesive sheet of the present invention comprises (i) a base with two opposite main sides and (ii) a plurality of protrusions made of an adhesive crosslinked polymer, which are arranged in a pattern on the first main side of the base.
• the adhesive sheet of the invention is particularly suited for attachment to either or both sides of a window glass to provide a decorative function or protective effects including protection of privacy, prevention of glass breakage, prevention of fragment scattering and for protective effects such as heat shielding, soundproofing and vibration resistance.
• At least one side of the base is provided with at least one continuous or non-continuous protrusion made of an adhesive polymer, and since the adhesive polymer of the protrusions is crosslinked and has a prescribed elastic modulus as mentioned above, it can be simply attached to an adherend (for example, window glass) without requiring separate adhesion means, to form relatively large spaces there between the adherend and the sheet. Furthermore, as a result of formation of these spaces, deformation or destruction of the spaces by plastic deformation (natural flow) of the protrusions and external forces is prevented, and it thus becomes possible to stably support the volume and shape of the spaces.
• adherend for example, window glass
• the protrusions on the main side of the base have the aforementioned prescribed elastic modulus (value of the storage elastic modulus G and degree of change in logi oG), are effectively capable of elastic deformation when subjected to external force and have suitable adhesive strength, and can therefore exhibit the effects of preventing breakage of adherends such as glass, preventing scattering of fragments of broken glass, etc, as well as shielding of heat and vibration resistance.
• the elastic modulus G (value measured at 25°C) of the protrusions on the main side of the base in the adhesive sheet of the invention as measured by dynamic viscoelasticity measurement with a frequency of 1 rad/sec and in shear mode is less than 5 x 10 ⁇ dyn/cm ⁇ , the protrusions undergo plastic flow with time, making it impossible to form spaces between the sheet and the surface of the adherend. Conversely, if the elastic modulus G exceeds 4 x 10 ⁇ dyn/cm ⁇ the adhesion of the protrusions will be lower.
• the lower adhesion of the protrusions will tend to result in a reduction in the vibration resistance effect expected by the invention, and may also prevent achievement of airtightness at the interface between the protrusions and the adherend surface, when airtight spaces are formed between the sheet and the adherend surface.
• the elastic modulus G of the protrusions at 25°C is preferably in the range of 6 x 10 ⁇ - 2 x l ⁇ 6 dyn/cm ⁇ . Outside of this range it is possible that no notable improvement will be seen in the effects of preventing glass breakage or preventing scattering of glass fragments.
• the reduction in the logi ⁇ G of the protrusions is 1.0 or greater in the range of 25-125°C, that is to say if the change in logjoG in this temperature range is less than -1.0, the protrusions of the attached adhesive sheet will undergo plastic flow with time, making it impossible to support the spaces formed between the sheet and the adherend. Such plastic flow will not occur if logjoG does not decrease or if it increases.
• logi QG elastic modulus of the protrusions
• a crosslinked adhesive polymer by polymerizing monomer components including an alkyl (meth)acrylate, an ethylenic unsaturated acid and a crosslinking monomer with at least 2 (meth)acrylic groups in the molecule, and doing so with the content of the crosslinking monomer in the range of 0.5-5 wt% with respect to the total monomer components.
• monomer components including an alkyl (meth)acrylate, an ethylenic unsaturated acid and a crosslinking monomer with at least 2 (meth)acrylic groups in the molecule.
• the surface roughness Ra of the sections of the first main tide of the base on which no protrusions are arranged is in the range of 0.4-200 ⁇ m, and therefore light striking those sections is scattered rendering the surface opaque or semi-transparent, to exhibit a privacy-protecting effect. If the surface roughness Ra of the floor of the depressions is too low, light will not be scattered and thus the privacy-protecting effect will be reduced, whereas if the surface roughness Ra is too large, in cases where the height of the protrusions is relatively low there will be a smaller space between the adherend and the adhesive sheet, thus reducing the other protective effects other than privacy protection. From this standpoint, then, the surface roughness Ra of the floor of the depressions is preferably in the range of 0.5-100 ⁇ m, and more preferably 0.6-
• the surface roughness Ra of the top faces of the protrusions, in combination with the surface roughness Ra of the depressions, is preferably to the range of 0.001- 10 ⁇ m, and especially 0.005-5 ⁇ m, after attachment to the window glass, etc. This will allow the adhesive sheet of the invention to have a greater decorative effect while also exhibiting a privacy-protecting effect.
• the pattern formed by the protrusions and depressions is recognized as a decorative pattern by observation from the other main side of the base (side which is not adhered to the adherend) or, in the case of a light-transparent adherend, from the back side of the adherend (side on which the adhesive sheet is adhered); thus, a larger difference in the surface roughness Ra of each will result in more effective enhancement of the decorative property. Consequently, the difference in the surface roughness Ra of the protrusions and the depressions is generally preferred to be 0.5 or greater, and especially 0.75 or greater.
• the term "surface roughness Ra" as used throughout this specification is the value measured using a contact needle surface roughness tester under conditions with a contact needle R of 5 ⁇ and a cutoff value of 0.8 mm.
• the difference in the surface roughness Ra of the protrusions and the depressions may be achieved, for example, by subjecting only the floor of the depressions to roughening treatment by mat working or the like to render it semitransparent.
• Mat working involves, for example, imparting the desired surface roughness to the surface of a releasable negative frame (details given below) for preparation of the adhesive sheet in a reproducible manner.
• the top faces (adhesive sides) of the protrusions of the reproduced adhesive sheet may have the same roughness as the floor of the depressions.
• the volume for each airtight space is preferably determined so as to be within an optimum range. That is, the volume of each depression enclosed by the protrusions is preferably in the range of 1 600 mmA If the volume of the depression is less than 1 mm ⁇ , the heat shielding and vibration resistance effect will tend to be reduced, whereas if it exceeds 600 mm ⁇ the effect of preventing breakage may be reduced.
• the volume of the depression is preferably in the range of 4-300 mmr 5 , and more preferably 5-200 mm ⁇ .
• the base of the adhesive sheet of the invention may comprise a crosslinked adhesive polymer, and thus when formed integrally with the protrusions a particularly excellent effect of glass breakage prevention and vibration resistance is exhibited.
• a sheet may also function as a double-sided adhesive sheet.
• a light- transparent flexible support may be attached to the second main side of the base, to readily produce a single-sided adhesive sheet.
• the light transmittance of the flexible support carrying the adhesive sheet is normally 60% or greater, preferably 70% or greater, and most preferably 80% or greater.
• the material used for the flexible support may be a polyester resin, acrylic resin, polyolefin resin, vinyl chloride resin, fluororesin, polycarbonate resin or polyimide resin.
• the thickness of the flexible support is usually in the range of 10-200 ⁇ m.
• the interface between the main side of the base and the flexible support may be subjected to simple adhesion treatment such as corona treatment or primer treatment.
• the adhesive sheet of the present invention may be an adhesive sheet formed with protrusions also provided on the second main side of the base in order to have adhesive protrusions on both of the opposite main sides, or 2 adhesive sheets may be placed together to form an adhesive sheet with a double-layered structure. In the latter case, airtight spaces may also be included in the interior of the adhesive sheet in addition to the spaces between the adherend and the adhesive sheet. This construction can be employed to easily increase the vibration resistance and breakage preventing effects.
• FIG. 1 is a perspective view showing an embodiment of an adhesive sheet according to the present invention
• Fig. 2 is a cross-sectional view of the same taken along line II-II in Fig. 1.
• the base 1 and the protrusions 2 on the first main side 11 of which the adhesive sheet 10 is made are formed integrally from the same material, and spaces 3 are formed which are enclosed between adjacent protrusions.
• the side opposite the first main side 11 of the base 1 has been roughened at the sections constituting the floors of the spaces 3, while the opposite second main side is flat.
• the protrusions 2 on the base 1 are arranged in a grid-like pattern, thus forming rectangular depressions 3.
• the pattern of the protrusions 2 and the shape of the depressions (spaces) may be any of various types for particular desired effects.
• the main side 11 with the protrusions is attached to an adherend such as window glass (not shown) by contact with its surface.
• adherend such as window glass (not shown)
• the adhesive top faces 21 of the protrusions 2 of the adhesive sheet 10 are adhered to the adherend, and the spaces 3 are thereby sealed by the adherend, resulting in formation of a plurality of discrete airtight spaces between the 3 surfaces of the sides of the protrusions 2, the first main side 11 which has been roughened and the surface of the adherend.
• a light-transparent flexible support may be attached to the second main side 12 of the base 1 to make a single-sided adhesive sheet.
• the protrusions formed arranged on the first main side of the base of the adhesive sheet according to the invention may form a pattern of any shape, so long as the effect of the invention is not impeded.
• the pattern of the protrusions is preferably one which has a roughly rectangular cross-section.
• a rectangular cross-section for the protrusions gives an adhesive side of sufficient area, and is satisfactory workable.
• a cross-section of the protrusions gives rectangles of width 0.1-10 mm, especially 0.5-5 mm, or trapezoids of upper base 0.1-8 mm, especially 0.2-3 mm and lower base 0.2-10 mm, especially 0.5-5 mm.
• the base may be either of the following general two forms: (I) Consisting of the same crosslinked adhesive polymer as the protrusions and preferably formed integrally with the protrusions.
• the preferred form is that described above in (I) wherein the protrusions and the base are integrally formed, in order to facilitate production of single- sided adhesive sheets, to increase cohesion at the interface between the protrusions and the base, and to provide a better effect of softening relatively strong impacts (i.e., an effect of vibration resistance and breakage prevention).
• the thickness of the base is usually 0.05-3 mm, preferably 0.1-1 mm, and especially 0.2-0.7 mm. If the base is too thin there will be a tendency for a reduced effect of softening external forces, and when employing a form wherein the sheet is adhered to the adherend to form airtight spaces between them, there will be a possibility of lower supportability of the airtight spaces. Conversely, if it is too thick the adhesive sheet becomes too bulky, thus reducing its ease of use and appearance when attached.
• depressions created around the protrusions must form spaces (throughout the present specification these will be referred to as "airtight spaces” or “open spaces” in communication with the exterior) between the adhesive sheet and the adherend in order to exhibit the different objects mentioned above.
• the depressions may be arranged in any of a variety of patterns, and for example, may be arranged to form a regular geometric pattern across roughly the entire surface of the roughly flat main side of the base on which the depressions are to be formed. Otherwise, the depressions may be arranged so that the pattern formed by the protrusions and depressions is recognized as a decorative pattern (relatively complex characters or images). In either case, the height of the protrusions is preferred to be essentially uniform. This will effectively increase the adhesive strength against the adherend.
• the aforementioned geometric pattern may be, for example, a lattice design, lace (diced design) or other pattern.
• the number of depressions provided per unit area is normally 0.3-50 per cm ⁇ , and preferably 0.5-25 per cm ⁇ . With too few depressions there is a risk of less prevention of breakage to the adherend as well as lower heat shielding and vibration resistance effects, and with too many the substantial space volume between the adherend and the adhesive sheet will inevitably be smaller than the prescribed range, which may make it impossible to achieve a vibration resistance effect.
• the depth of the depressions i.e. the height of the protrusions.
• the vibration resistance effect may be reduced, and there may be a reduction in the vibration resistance and breakage preventing effects for the adherend.
• a variety of different shapes may be employed for the depressions. Examples include geometric solids such as cylinders, prisms, pyramids, cones, truncated pyramids, truncated cones, deformed spheres, deformed ellipsoids and the like.
• the airtight spaces may have any one or combination of two shapes selected from the group consisting of such shapes.
• the aforementioned protrusions are preferably formed of a crosslinked polymer with adhesive properties.
• the protrusions which are formed from this specified type of polymer are used to ensure adhesion of the adhesive sheet with adherends. They also provide an excellent effect of supporting the airtight spaces, when airtight spaces are formed between the adherend and adhesive sheet. In cases where the airtight spaces are deformed or lost, the air in the inner spaces:
• (a) may leak from the gaps at the adhesion interface between the protrusions and adherend surface, or
• the adhesive crosslinked polymer is employed for excellent adhesion, to increase the shape supportability of the protrusions and to improve air blockage (permeation resistance), i.e., for increased airtightness. Also, the elastic characteristics which are governed by the aforementioned prescribed ranges serve to provide suitable cohesive force for the protrusions and increase air blockage.
• the adhesive crosslinked polymer is a crosslinked acrylic-based polymer prepared by polymerizing monomer components consisting substantially of an alkyl (meth)acrylate, an ethylenic unsaturated acid and a crosslinking monomer with at least 2 (meth)acrylic groups in the molecule.
• the crosslinked acrylic- based polymer is especially superior for airtightness. The airtightness can be particularly increased if the content of the crosslinking monomer is in the range of 0.5-5 wt% with respect to the total monomer components.
• the content of the crosslinking monomer is less than 0.5 wt% there is a tendency toward lower air blockage and shape support, while if it exceeds 0.5 wt% there is a tendency toward lower adhesion.
• a particularly suitable range for the content of the crosslinking monomer is 0.7-2 wt%.
• Isooctyl acrylate is preferred as the alkyl (meth)acrylate, i.e. alkyl acrylate or alkyl methacrylate, for formation of the adhesive polymer. Isooctyl acrylate imparts effective adhesion to the adhesive sides of the protrusions, facilitating attachment of the adhesive sheet.
• alkyl (meth)acrylates which may be used include any one or mixture of 2 or more alkyl acrylates or alkyl methacrylates wherein the alkyl group is one selected from among methyl, ethyl, isopropyl, butyl, isobutyl, isooctyl, 2-methylbutyl, 2-ethylhexyl, lauryl, stearyl, cyclohexyl, isobornyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, hydroxyethoxyethyl, methoxyethyl, ethoxyethyl, dimethylaminoethyl, diethylaminoethyl and glycidyl.
• the ethylenic unsaturated acid is preferably (meth)acrylic acid, i.e. acrylic acid or methacrylic acid.
• the (meth)acrylic acid effectively increases the cohesive strength of the adhesive polymer, improves the shape support of the protrusions, and effectively increases the airtightness of the airtight spaces
• other ethylenic unsaturated acids which may be used include any one or combination of 2 or more selected from among ⁇ - hydroxyethylcarboxylic acid, itaconic acid, maleic acid and fumaric acid.
• the crosslinking monomer with 2 or more (meth)acrylic groups in the molecule is preferably 1,6-hexanediol diacrylate.
• 1,6-hexanediol diacrylate effectively increases the crosslinked density of the adhesive polymer, and can provide a satisfactory balance between the adhesion, the shape supportability of the spaces and the air blockage.
• the adhesive crosslinked polymer may be obtained by polymerizing a monomer component containing the components mentioned above as the starting material, by heat or by irradiation with ultraviolet, electron or other rays.
• the adhesive sheet may be formed by contacting the monomer with a molding frame having the desired geometric structure and completing polymerization and crosslinking in the frame.
• a component which includes a monomer component containing no crosslinking monomer may be partially polymerized in advance to prepare a partially polymerized syrup with an adjusted viscosity, and a mixture of this syrup and the crosslinking monomer may then be contacted with the frame while completing polymerization and crosslinking.
• the viscosity of the syrup is normally 100-100,000 cps.
• a polymerization initiator may also be used for more efficient polymerization.
• the polymerization initiator may be, for example, a benzophenone-based photoinitiator (such as 'Trgacure 651TM" by Ciba Geigy Inc.).
• As adhesive polymers there may be used, in addition to the aforementioned acrylic- based polymers, also rubber-based polymers such as silicone rubber, butyl rubber and styrene rubber, or polymers such as polyurethane.
• the peel strength of the adhesive sheet whose protrusions have been adhered to an adherend, when peeled from the adherend surface at 25°C is preferably in the range of 200-2,500 g/25 mm, and especially in the range of 350-2,000 g/25 mm. If the peel strength is less than 200 g/25 mm there may be a lower effect against vibrations, while if it is greater than 2,500 g/25 mm workability may be impaired, as it may become difficult to peel off the adhesive sheet after it has been attached and positioning of the sheet will also be more difficult.
• the adhesive sheet of the invention when used as a protective adhesive sheet for window glass, it is convenient if the adhesive sheet which is being used can be peeled from the glass and reattached after cleaning the window glass. From this viewpoint, it is particularly preferred for the peel strength to be less than 1,000 g/25 mm. The peel strength can be controlled by adjusting the amount of the crosslinking monomer.
• the adhesive sheet may be produced by the following reproduction method.
• the monomer containing isooctyl acrylate and acrylic acid in the prescribed proportion and a polymerization initiator are placed in a stirring apparatus and subjected to ultraviolet polymerization with stirring.
• This step ends with partial polymerization, to a viscosity in the range of 100-100,000 cps, to prepare a partially polymerized syrup.
• a crosslinking monomer and additional photoinitiator are uniformly mixed to prepare the starting composition for the adhesive sheet.
• the inside of the stirrer is purged with an inert gas, usually nitrogen gas or the like.
• a positive frame made of relatively hard plastic is prepared to have the desired geometric structure.
• the plastic used may be an acrylic resin or polycarbonate resin.
• the release resin is contacted with the positive frame, and the ultraviolet cured release resin is released from the positive frame to give a negative frame.
• a positive frame there may be mentioned the "Acrysandy Panel (tradename)” series by Acrysandy Co.
• a release resin there may be mentioned "Molding Silicon SE9555 (tradename)” by Toray-Dow Corning Co.
• the desired roughness is imparted to the top faces of the protrusions of the negative frame at this time.
• the desired roughness can be imparted to the top faces of the protrusions of the negative frame by a method wherein the floor sections of the depressions of the positive frame are provided with roughness by sandblasting or other surface polishing means. Also, after roughening the surface of the negative frame, it may be completed by coating with a fluororesin such as TeflonTM.
• the surface roughness of the top faces of the protrusions of the negative frame is usually in the range of 0.4-200 ⁇ m.
• the starting composition of the adhesive sheet is contacted with the molded negative frame and a transparent release film is used to cover the composition.
• the negative frame and release film are situated apart at a prescribed spacing so as to form the section for the base of the adhesive sheet and the sections for the protrusions.
• the release film is irradiated with ultraviolet rays from the top to complete the curing reaction, and the negative frame and release film are separated. This gives an adhesive sheet made of the cured composition.
• the release film may be used for shielding of oxygen, and also has the effect of flattening the other main side of the base of the adhesive sheet.
• a flexible support anchored to the base, as described earlier, may also be used instead of the release film.
• a flexible plastic film such as polyester (PET) is used as the release film.
• the following method may also be used to set the thickness of the base. That is, after casting an excess of the starting composition onto the negative frame, covering it over with the release film (or flexible support) and forming a composition-containing laminate, the laminate is passed through the gaps of a knife coater containing gaps fixed at the prescribed spacing, and the excess portion of the starting composition is discharged from the edges of the laminate, for adjustment of the thickness and flatness of the base section.
• the wavelength of the ultraviolet rays is usually 300-400 nm, and the irradiation intensity is in the range of 330- 1,000 J/cm 2 .
• a glass plate of sufficient thickness may be used as the positive frame material, and the flat side of the glass plate may be engraved by the sanding method to form the desired irregularity pattern for formation of the positive frame.
• the negative frame used may be one wherein the molding side of the metal frame has been fluororesin-treated using TeflonTM or the like.
• the base and the protrusions may also be formed from different materials and attached together.
• the base may be a film which has been subjected to mat working on one main side and over the entire surface rendered semi- transparent with diffusion, with the protrusions formed on the mat-worked side using the aforementioned negative frame and a monomer component which gives an adhesive polymer upon polymerization. That is, in this method the adhesive sheet is formed using the mat-worked film instead of a release film.
• the base is virtually transparent at the sections where the adhesive polymer is attached (i.e., at the protrusions).
• the protrusions to be linked (i.e. established so as to surround the depressions), for increased adhesive strength between the protrusions and the base.
• Other additives i.e. established so as to surround the depressions
• the adhesive sheet of the present invention may also contain various additives commonly used for pressure-sensitive adhesives, so long as the effect of the invention is not impeded.
• Additives which may be used here include, for example, tackifiers, plasticizing agents, ultraviolet absorbers, antioxidants, coloring materials and fillers.
• the adhesive sheet of the invention may be used to form a window glass structure for protection of window glass.
• the window glass according to the invention may be of any of a variety of forms, and the one produced as follows is an example thereof.
• the adhesive sheet is attached in such a manner that the top faces (adhesive sides) of the protrusions contact with the surface of the window glass adherend (adherend surface), after which light pressure is applied from the non-adhesive side of the adhesive sheet by the hand or a pressure roller to adhere the adhesive side to the adherend surface. Since the protrusions contain an adhesive polymer, the adhesive sheet can be adhered to an adherend surface by light pressure application as for a common pressure-sensitive adhesive sheet.
• the attached adhesive sheet forms a plurality of discrete airtight spaces sealed between the depressions and the adherend surface.
• the elastic modulus of the protrusions is within a prescribed range while the airtight spaces are supported from collapse by a constant air pressure, to thus increase the effect of supporting the shape and volume of the airtight spaces.
• the pressure application is a pressure which does not cause collapse of the airtight spaces in the process of attachment, and may be for example, in a range under 10 kPa.
• Fig. 3 is a cross-sectional view of a window glass structure produced in the manner described above.
• an adhesive sheet 10 according to the invention is attached to one side of a window glass 31 with the top faces 21 of the protrusions 2 as the joining sides.
• the double window glass structure shown in Fig. 4 can be produced as a modified form of the illustrated window glass structure.
• This drawing shows an adhesive sheet 10 according to the invention sandwiched between two window glasses 31 and 32.
• Such a double window glass structure naturally provides the same effect as the window glass structure shown in Fig. 2, but also achieves a vast improvement especially in soundproofing and vibration resistance.
• the window glass structure shown in Fig. 4 be positioned so that the window glass 31 is on the interior side, and the adhesive sheet of the invention attached over the window glass 31.
• the term "window glass” is used in a broad sense to include, in addition to window glass mounted for the purpose of lighting of homes and buildings, also glass mounted for lighting of various articles or erected structures, as well as for related purposes.
• Example 1 Construction of adhesive sheet A partially polymerized syrup was prepared by ultraviolet polymerization from a preliminary component including a monomer component comprising 90 parts by weight of isooctyl acrylate and 10 parts by weight of acrylic acid, and using 0.1 part by weight of Irgacure 651TM (product of Ciba-Geigy Co.) as a photoinitiator. To the syrup there were added 1 part by weight of 1,6-hexanediol diacrylate as a crosslinking monomer and 0.2 part by weight of additional photoinitiator (Irgacure 651TM) , and mixing to uniformity produced a starting composition for an adhesive sheet.
• Irgacure 651TM additional photoinitiator
• a glass plate with a thickness of about 5 mm was engraved by the sanding method, irregularities were formed therein in such a manner that the irregularities in the adhesive sheet prepared therefrom would be rectangular solids of the desired dimensions, and this was used as the positive molding frame for ultraviolet curing performed by the method described in the previous paragraph (Production of adhesive sheet).
• the irregularities were formed so as to surround depressions on the base, to obtain the adhesive sheet for this example (30 cm length x 30 cm width x 1.5 mm total height of base + protrusion).
• a flexible support namely the PET film "Lumila-50TTM" (50 ⁇ m thickness, 0.01 ⁇ m surface roughness Ra) by
• the shape of the depressions in the resulting adhesive sheet was rectangular, the ⁇ unit volume was 9 mm ⁇ (3 mm length x 3 mm width x 1 mm depth), and they were arranged at a proportion of 9 per cm 2 (on the horizontal plane, in a grid-like pattern).
• the protrusions were arranged in a grid-like manner around the depressions, and the width measured on the adhesive side was 1 mm. Evaluation of adhesive sheet:
• the elastic modulus G (storage elastic modulus, dyn /cm 2 ) of the protrusions of the adhesive sheet was measured by dynamic viscoelasticity measurement with a frequency of 1 rad/sec and in shear mode.
• the measuring apparatus used was a "Model name: RDA II" Dynamic Analyzer produced by Rheometrix Co.
• the sample holder for the measurement was a horizontal plate with a diameter of 7.9 mm.
• the change, or reduction in the logi ⁇ G was calculated from the fluctuating value against a reference elastic modulus G at 25 °C read from a viscoelastic spectrum obtained in the range of 25-125°C.
• the volume of the airtight spaces formed by the depressions was calculated from the volume of one depression of the adhesive sheet before its attachment to an object.
• the depression was of a shape lacking one side of a geometrical form such as a truncated pyramid or rectangle, it was calculated from those geometrical dimensions.
• the shape provision was evaluated based on whether airtight spaces could be formed or not. Cases where spaces (airtight spaces in this case) could not be formed between an adherend and the adhesive sheet corresponding to the depressions of the adhesive sheet when the adhesive sheet was attached to the adherend (a slide glass was used in this evaluation test) were judged as NG, and those where airtight spaces could be formed were judged as OK.
• the slide glass was a "MICRO SLIDE GLASS White/Green Polish No. 1 (tradename)" produced by Mitsunami Glass Industries, and had dimensions of 76 mm length x 26 mm width x 1 mm thickness. (5) Shape supportability
• the shape supportability was evaluated based on the change in the airtight spaces with time. After attaching the adhesive sheet to an adherend (the same type of slide glass as above was used in this evaluation test), the spaces immediately after attachment were compared with the spaces after 5 months following the attachment, and cases where virtually no change occurred were judged as OK, while those in which a clear change was seen were judged as NG. This comparison was made using 20x magnified images (taken through the slide glass) immediately after attachment and 5 months thereafter.
• Breakage-preventing effect (impact resistance effect) The breakage-preventing effect was evaluated by the falling ball impact test in the following manner.
• the adhesive sheet was attached so as to cover roughly the entire surface of one side of a breakable test piece (same type of slide glass as above) for use as the sample.
• a 2 kg-weight pressure adhesive roller was used for pressure adhesion by one pass over the adhesive sheet positioned on the test piece.
• the sample prepared in this manner was positioned on an iron plate via a "FUJI PAPI (tradename)" paper towel manufactured by Taiyo Paper Industries, in such a manner that the attaching side of the adhesive sheet was facing upward, and an iron ball with a diameter of 15 mm and a mass of 30 g was dropped from prescribed heights.
• the testing environment was a temperature of 25 °C and a relative humidity of 60% RH. (7) Peel strength
• the peel strength is the value of the peel resistance measured when the adhesive sheet attached to the slide glass is peeled off using a tensile tester at a pulling rate of 300 mm/min in a 180° direction under conditions of 25°C environment temperature and 60% relative humidity.
• the measured peel resistance is indicated by a maximum value and minimum value. Consequently, the measurement results given in Table 1 are shown as the maximum value (Max.), minimum value (Min.) and the average value which is 1/2 of their sum. (8) Surface roughness
• the surface roughness Ra of the floors of the depressions and of the top faces of the protrusions of the adhesive sheet was measured using a surface roughness tester (SE-30K) manufactured by Kosaka Laboratory, Ltd., under conditions with a contact needle R of 5 ⁇ and a cutoff value of 0.8 mm. (9) Privacy protecting effect
• the privacy protecting effect was evaluated on the basis of whether or not the state of the interior of an experimental room could be seen from outside after actually attaching an adhesive sheet of plane dimensions 30 x 30 cm to a window glass of the room.
• the effect in cases where the state of the interior could be seen from the outside was judged as "NO", and in that in cases where the state of the interior could barely be seen was judged as
• Example 2 25 mm- (5 mm length x 5 mm width x 1 mm height)
• Example 3 80 mm- (10 mm length x 10 mm width x 0.8 mm height)
• Example 4 150 mm- (10 mm length x 10 mm width x 1.5 mm height)
• An adhesive sheet was prepared by repeating the method described in Example 1. For comparison in this example, however, a flat adhesive layer was formed to a thickness of about 1.5 mm, without adding an irregularity pattern on the surface of the adhesive sheet.
• Example 5 Evaluation of the resulting adhesive sheet in the manner described in Example 1 gave a surface roughness Ra of 0.03 ⁇ and a judgment of "NO" for the privacy protecting effect for this example. Also, the value determined for the breakage preventing effect was a peel strength of 1150 g/25 mm at 30 cm, 180°.
• Example 5 Evaluation of the resulting adhesive sheet in the manner described in Example 1 gave a surface roughness Ra of 0.03 ⁇ and a judgment of "NO" for the privacy protecting effect for this example. Also, the value determined for the breakage preventing effect was a peel strength of 1150 g/25 mm at 30 cm, 180°.
• An adhesive sheet for this example was constructed by repeating the method described in Example 1 above, except that the volume of the depressions of the adhesive sheet was adjusted to 400 mm-* (20 mm length x 20 mm width x 1 mm height). Evaluation of heat shielding effect
• Fig. 5 is a graph showing the results with the temperature difference (°C) from the reference adhesive sheet plotted against time
• Example 3 it was possible to maintain the temperature of the water to as high as about 2.2°C after standing for 50 minutes.
• the adhesive sheet of Example 5 it was possible to maintain the temperature of the water to as high as about
• An adhesive sheet for this example was constructed by repeating the method described in Example 1 above, except that the shape and volume of the depressions of the adhesive sheet were adjusted as follows.
• Depression shape roughly square truncated pyramid (adhesive side wider)
• Example 6 The procedure described in Example 6 was repeated. However, for this example the crosslinking monomer content was changed from 1 part by weight to the amounts listed in Table 2 below. The resulting adhesive sheets were evaluated in the same manner as described in Example 1, giving the results summarized below in Table 2.
• Example 6 The procedure described in Example 6 was repeated. However, for comparison in this example, only isooctyl acrylate was used as the monomer component, and no crosslinking monomer was used. The resulting adhesive sheet was evaluated in the same manner as described in Example 1, giving the results summarized below in Table 3. With the adhesive sheet of this example it was impossible to form spaces between the adherend and the adhesive sheet. Comparative Example 3
• Example 6 The procedure described in Example 6 was repeated. However, for comparison in this example, no crosslinking monomer was used.
• the resulting adhesive sheet was evaluated in the same manner as described in Example 1, giving the results summarized below in Table 3. With the adhesive sheet of this example it was impossible to maintain the spaces between the adherend and the adhesive sheet.
• the adhesive sheet of this example was prepared by repeating the procedure described in Example 1, except that a release film (PET film silicone-treated on one side) was used instead of the flexible support.
• a release film PET film silicone-treated on one side
• the vibration resistance effect of the resulting adhesive sheet was evaluated in the following manner. First, 2 aluminum panels of 25 mm length x 100 mm width x 2 mm thickness were provided, and an adhesive sheet cut to roughly the same planar dimensions was sandwiched between them to adhere the 3 members together. The plurality of depressions created airtight spaces between the irregular adhesive side of the adhesive sheet and the facing side of one of the aluminum panels.
• a vibration detector was positioned at roughly the center of the surface of one of the two adhered aluminum panels (aluminum panels adhered to the irregular adhesive side of the adhesive sheet), on the side which was not adhered to the adhesive sheet for this example, and then the surface of the other aluminum panel (at the surface not adhered to the sheet) was plucked once with a metal rod with a diameter of about 3.5 mm, at approximately the center.
• the vibrations transmitted from the plucked aluminum panel to the other aluminum panel on which the vibration detector was positioned were detected with a commercially available vibration detector, an "Acceleration Pickup (tradename)" manufactured by PCB (PIEZOELECTRONICS) Co.
• the damping constant hi was determined using the vibration analyzer: "3562A (product no.) Dynamic Signal Analyzer” manufactured by Hewlett Packard, Inc. Three measurements were taken, and their average was used as the measured value. The measured value for this example was 2.0, as listed in Table 4.
• the damping constant is the value of the first vibrational amplitude divided by the second vibrational amplitude, and thus a larger constant represents a greater damping factor, or vibration resistance effect. Comparative Example 4
• the adhesive sheet of this example was prepared by repeating the procedure described in Comparative Example 1, except that a release film (PET film silicone-treated on one side) was used instead of the flexible support.
• a release film PET film silicone-treated on one side
• Example 11 1 ram* (1 mm length x 1 mm width x 1 mm height)
• Example 12 4 mm* (2 mm length x 2 mm width x 1 mm height)
• Example 13 25 mm* (5 mm length x 5 mm width x 1 mm height)
• Example 14 100 mm* (10 mm length x 10 mm width x 1 mm height)
• the damping constants hi for vibrations transmitted to the protrusions "ides of the resulting adhesive sheets from their bases were measured in the same manner as for Example 10, .giving the results shown below in Table 4.
• the damping constant was measured in the same manner as Example 10. In this example, however, a vibration detector was positioned on the aluminum panel adhered against the flat side of the adhesive sheet (side opposite the irregular adhesive side) to cause vibration in the other aluminum panel, and the degree of vibration transmitted from the protrusions of the sheet to the base side was measured.
• the damping constants (this will be referred to as "damping constant h2" for distinction from the aforementioned damping constant hi for vibrations transmitted from the base to the protrusion side) of each example were larger than the damping constants hi.
• the resistance against vibrations (h2) preventing transmission of vibrations applied from the protrusions to the base side was higher than the resistance against vibrations (hi) preventing transmission of vibrations applied from the base to the protrusion side, thus demonstrating anisotropy of the vibration resistance effect.
• Such an adhesive sheet having an anisotropic vibration resistance effect may be utilized, for example, in the following manner.
• An adhesive sheet of the invention including no flexible support is used to construct a double-layered structure for a window. That is, the adhesive sheet is sandwiched between two window glass panes to adhere the three members together and construct a double window.
• the double window constructed in this manner is fitted in the window section of a room so that the window glass on which the protrusions are adhered faces the outside. This allows vibrations transmitted from the outside, i.e. entrance of noise into the room, to be effectively prevented. It also provides protection of privacy and heat shielding and prevents breakage of glass or scattering of glass fragments, while further providing a decorative property.
• the window glass with the protrusions adhered thereto may be oriented toward the inside, and a separate adhesive sheets of the invention (with a flexible support) attached to the inwardly facing glass surface.
• Example 4 (having both flat adhesive sides) measured in the same manner, and therefore a greater vibration resistance effect was achieved by the presence of the spaces (airtight spaces) between the aluminum panel and the adhesive sheet. Furthermore, all of the sheets of Examples 11 to 14 also had greater vibration resistance effects than Comparative Example 4, due to the spaces (airtight spaces) formed with the adherend (aluminum panel).
• a protective adhesive sheet which, when attached to an adherend, particularly window glass, is capable of simultaneously exhibiting effects of improved decorative property, prevention of breakage and fragment scattering of the adherend, heat shielding, soundproofing and vibration resistance, and when attached to window glass or the like also provides an excellent effect of privacy protection.
• the adhesive sheet of the present invention is also noteworthy in light of the fact that it can be easily attached to adherends where needed without using separate adhesion means.
• the invention further provides a window glass structure which has these excellent characteristics.

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• 1997
  • 1997-11-10 JP JP9307598A patent/JPH11181367A/ja active Pending
• 1998
  • 1998-10-14 WO PCT/US1998/021613 patent/WO1999024519A1/en active Application Filing
  • 1998-10-14 AU AU98016/98A patent/AU9801698A/en not_active Abandoned

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