Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
  • B29C33/40—Plastics, e.g. foam or rubber
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
  • H01J9/241—Manufacture or joining of vessels, leading-in conductors or bases the vessel being for a flat panel display
  • H01J9/242—Spacers between faceplate and backplate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
  • B29C33/40—Plastics, e.g. foam or rubber
  • B29C33/405—Elastomers, e.g. rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/42—Moulds or cores; Details thereof or accessories therefor characterised by the shape of the moulding surface, e.g. ribs or grooves
  • B29C33/424—Moulding surfaces provided with means for marking or patterning
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
  • B29C33/48—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with means for collapsing or disassembling
  • B29C33/50—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with means for collapsing or disassembling elastic or flexible
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
  • H01J19/02—Electron-emitting electrodes; Cathodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
  • H01J2211/20—Constructional details
  • H01J2211/34—Vessels, containers or parts thereof, e.g. substrates
  • H01J2211/36—Spacers, barriers, ribs, partitions or the like
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2329/00—Electron emission display panels, e.g. field emission display panels
  • H01J2329/86—Vessels
  • H01J2329/8625—Spacing members

Definitions

• the present invention relates to a mold and a method of manufacturing a mold, and more particularly to a flexible mold and a method of manufacturing same which is useful for molding a fine structure and which is especially excellent in antistatic performance.
• the present invention also relates to a method of manufacturing a fine structure using such a flexible mold.
• the present invention can be advantageously used for manufacturing ribs of a back panel for a plasma display panel.
• CRTs cathode ray tubes
• a PDP has the construction as shown schematically in Fig. 1.
• the PDP 50 includes only one discharge cell 56 for display for the sake of simplicity, it generally includes a multiplicity of minute discharge cells for display. More specifically, each discharge cell 56 for display is defined as surrounded by a pair of glass substrates, that is, a front glass substrate 61 and a back glass substrate 51, which are spaced apart from and opposed to each other, and a fine structure of ribs 54 (barrier ribs, sometimes called partition walls or barriers) of a specified shape disposed between these glass substrates.
• the front glass substrate 61 comprises a transparent display electrode 63 consisting of scanning electrode and sustaining electrode, a transparent dielectric layer 62, and an overlying transparent protective layer 64.
• the back glass substrate 51 comprises an address electrode 53 and an overlying dielectric layer 52.
• the display electrodes 63 and the address electrodes 53 are perpendicular to each other, and are respectively arranged spaced apart in a regular pattern.
• Each discharge cell for display 56 has a fluorescent layer 55 formed on the interior wall thereof, and has a rare gas (for example, Ne-Xe gas) hermetically sealed in the inside so as to enable light emitting display by means of plasma discharge between above-mentioned electrodes.
• a rare gas for example, Ne-Xe gas
• the ribs 54 consist of a fine structure of ceramics, and together with address electrodes 53, are usually provided on the back glass substrate 51, as shown schematically in Fig. 2, in advance of forming a back panel for PDP. Since the shape and dimensional precision of the ribs significantly affect the performance of PDP, various improvement have been made on the mold used for manufacturing ribs and on the manufacturing method.
• barrier ribs characterized in that metal or glass is used as the mold material and that coating liquid for forming ribs (partition wall) is disposed between the surface of a glass substrate and the mold material, and the mold material is removed after the coating liquid is hardened and thereafter the substrate having the hardened coating liquid transferred thereon is baked (See Japanese Unexamined Patent Publication (Kokai) No. 9-12336).
• the coating liquid has glass powder of low melting point as a main component.
• a method for manufacturing a substrate for PDP comprising the steps of filling a mixture of ceramic or glass powder with a solvent and a binder consisting of an organic additive into a silicone resin mold having cavities for the partition walls, and joining this mixture integrally to a back panel formed of ceramics or glass (See Japanese Unexamined Patent Publication (Kokai) No. 9-134676).
• a method for manufacturing partition walls comprising the steps of forming a partition wall member having a predetermined softness in the shape of a plate of a predetermined thickness on a surface of a substrate, molding the partition wall member under pressure by a press mold provided with a shape corresponding to the partition wall to be formed, releasing the press mold from the partition wall member, and heat-treating the molded partition wall member at a predetermined temperature, has also been proposed (Japanese Unexamined Patent Publication (Kokai) No. 9-283017).
• Japanese Unexamined Patent Publication (Kokai) No. 9-283017 Japanese Unexamined Patent Publication (Kokai) No. 9-283017.
• a mold is usually formed of resin material, electrification due to static electricity is likely to occur during its usage, and as a result, the mold tends to attract dust or powder of the molding material, or debris of ribs, so that frequent cleaning is required or the quality of obtained back panel may be adversely affected.
• one approach is a method for antistatic processing of a mold used for manufacturing a substrate for PDP, using an ionic conductive material, preferably lithium perchlorate.
• an ionic conductive material preferably lithium perchlorate.
• Lithium perchlorate has relatively low ionization energy (high solubility in solvents) compared to other common salts, so that, when blended to organic material such as resins, it increases the electrical conductivity of the material.
• surface electrical resistance of the mold was decreased as a result of the antistatic processing, and adherence of dust or the like could be thereby avoided.
• antistatic processing could be performed successfully irrespective of surrounding environment.
• a flexible mold comprising a mold layer having a groove pattern of specified shape and size on the surface thereof, wherein said mold layer contains lithium salt of an organic fluorine compound as an antistatic agent.
• a method of manufacturing a flexible mold comprising a mold layer having a groove pattern of specified shape and size, said method comprising the steps of: forming a layer of a photocurable resin material by coating a photocurable resin material containing a lithium salt of an organic fluorine compound as an antistatic agent to a predetermined film thickness on a metal master pattern having on the surface thereof a protrusion pattern in shape and size corresponding to said groove pattern of said mold; laminating a transparent support consisting of a film of plastic material on said metal master pattern to thereby form a laminate of said metal master pattern, said layer of a photocurable resin material, and said support; irradiating said laminate with light from the side of the support to harden said layer of photocurable resin material; and releasing said mold layer formed by the hardening of said photocurable resin material together with said support from said metal master pattern.
• a method of manufacturing a fine structure having a protrusion pattern of specified shape and size on the surface of a substrate comprising the steps of: providing a flexible mold which has on the surface thereof a groove pattern of shape and size corresponding to said protrusion pattern, said mold layer containing a lithium salt of an organic fluorine compound as an antistatic agent; placing a curable molding material between said substrate and said mold layer of said mold, and filling said molding material into said groove pattern of the mold; curing said molding material and forming a fine structure consisting of said substrate and the protrusion pattern integrally connected thereto; and releasing said fine structure from the mold.
• FIG. 1 is a cross-sectional view schematically showing an example of conventional
• Fig. 2 is a perspective view showing a back panel for PDP used in the PDP of Fig. 1.
• Fig. 3 is a perspective view showing a flexible mold according to an embodiment of the present invention.
• Fig. 4 is a cross-sectional view taken along line IV-IV of the mold in Fig. 3.
• Fig. 5a-5c is a cross-sectional view showing a method of manufacturing a flexible mold according to the present invention.
• Fig. 6a-6c is a cross-sectional view showing a method of manufacturing a back panel for PDP according to the present invention.
• Fig. 7 is a graph plotting the relation between surface resistance and added amount of lithium salt solution relative to the amount of resin material.
• Fig. 8 is a graph plotting the relation between electrification voltage and added amount of lithium salt solution relative to the amount of resin material.
• the flexible mold and the method of manufacturing same, and the method for manufacturing a fine structure according to the present invention may be advantageously carried out in various embodiments, respectively.
• Embodiments of the present invention will be described in detail below with reference to manufacture of ribs for PDP as a typical example of fine structures. It is to be understood that the present invention is by no means restricted to manufacture of ribs for PDP.
• the ribs 54 for PDP are provided on the back glass substrate 51 to form a back panel for PDP.
• the spacing C of the ribs 54 may vary depending upon the size of the screen, and is typically in the range of about 150 to 400 ⁇ m.
• the ribs should satisfy two requirements, that is, “there should be no such defects as inclusion of air bubbles, deformation, and the like" and "the pitch of ribs should have high precision.”
• the precision of the pitch ribs are required to be provided at the specified location with little deviation relative to address electrodes, and indeed the tolerance of the position is within a few tens of ⁇ m.
• Fig. 4 is a cross-sectional view taken along the line IV-IV of Fig. 3, although the shape and size of the flexible mold of Fig. 3 is not accurately reproduced.
• the flexible mold 10 has a groove pattern of predetermined shape and size on the surface thereof.
• the groove pattern is a straight rib pattern composed of a plurality of grooves 4 arranged generally in parallel to each other at a constant spacing.
• the grooves 4 have sides (side walls) preferably inclined as shown in the Figure 4 so as to permit the ribs to be easily released from the mold. Also, terminating ends of the grooves extending in the longitudinal direction have preferably inclined end surfaces.
• Width 1 of the plane portion that lies between two grooves 4 is typically in the range of about 50 to 250 ⁇ m, and preferably in the range of about 100 to 200 ⁇ m.
• the flexible mold 10 is formed so as to be provided on the surface with grooves 4 opened on top plane as shown in Figure 4, so that it can be advantageously used for molding ribs for PDP having a protrusion pattern, for example, a straight protrusion pattern, a lattice-like protrusion pattern, etc.
• the flexible mold 10 may be formed only of a mold layer 11, or may include additional layers as required, or optional processing may be performed on various layers composing the mold.
• the flexible mold is preferably composed of a support 1 and a mold layer 11 having a groove 4 thereon. Each of the support 1 and the mold layer 11 is preferably transparent.
• the flexible mold of the present invention is characterized in that the mold layer contains lithium salt of an organic fluorine compound as an antistatic agent.
• the lithium salt of an organic fluorine compound is used, when blended to the constituent material (molding material, preferably resin material) of the mold layer, in an amount effective for sufficient function as an antistatic agent in the blend or obtained mold and for avoiding occurrence of undesired electrification due to static electricity.
• Lithium salt of an organic fluorine compound to be blended to the mold layer used in the present invention is not particularly restricted.
• Lithium salt of an organic fluorine compound suitable in the practice of the present invention is preferably: (1) a compound having excellent stability to moisture, that is, a compound that does not substantially decomposed in the presence of moisture;
• a compound having excellent thermal stability that is a compound that does not substantially decomposed when heated to an elevated temperature, for example, to about 100 °C; more specifically, a compound that remains stable and does not give rise to thermal decomposition when heated to an elevated temperature of 200 °C or higher, preferably about 300 to 350 °C, during the course of molding process using the mold;
• the lithium salt compound used in the present invention is required to satisfy at least one of these requirements, and satisfies most preferably all of these requirements.
• suitable lithium salts of organic fluorine compounds to be used in the invention include, but are not limited to, CF 3 SO 3 Li, (CGriF2 Clean + ⁇ SO 2 ) 2 NLi wherein n is an integer of 1 or 2, LiSO 3 C 2 F 4 SO 3 Li, CF 3 CO 2 Li, C F 9 SO 3 Li, (CF 3 CO) 2 NLi, (CF 3 SO 2 ) 3 CLi, and (CF 3 SO 2 ) 2 CFLi.
• These lithium salts may be used alone or in a mixture of two or more of them.
• lithium salts can be used advantageously in the present invention for reasons as described below.
• Lithium salts such as CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, (C 2 FsSO 2 ) 2 NLi are preferred.
• lithium salts such as CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, (C 2 F 5 SO 2 )2NLi are stable at temperature up to 350°C.
• these lithium salts have a low oxidative property so that they can be easily blended to the mold material and there is no difficulty in the management of the obtained blend.
• the entire process beginning from the preparation of the mold material, manufacture of the mold, to the storage of the mold can be implemented far more easily.
• lithium salts of organic fluorine compounds have remarkably excellent antistatic performance. These lithium salts have low ionization energy like lithium perchlorate, and can be advantageously used as an antistatic agent.
• lithium salts having -SO 2 group in the molecule for example (C n F2 n+ iSO2)2NLi, have especially high electrical conductivity.
• imide salts such as (C n F2n + iSO2)2NLi have two -SO2 groups in the molecule and especially high electrical conductivity can be expected from these salts.
• ionizing solvent may be used in varied amount for dissolving lithium salts, and is typically used preferably in an amount in the range of about 0.01 to 10% by weight, more preferably in the range of about 0.1 to 1.0% by weight, relative to total weight of the mold material.
• Effective blended amount of lithium salt in the mold layer may be varied depending upon various factors such as the kind of lithium salt and the kind of the mold material, and typically, it is preferably in the range of about 0.01 to 5% by weight, and more preferably in the range of about 0.05 to 1% by weight, relative to total weight of the mold material. If the blended amount of such lithium salt is less than 0.01% by weight, desired antistatic effect cannot be obtained. If, on the contrary, the blended amount is more than 5% by weight, the antistatic effect is saturated.
• the mold layer is preferably formed of hardened piece of a photocurable resin material.
• the mold layer that can be used advantageously for implementing the present invention is a thin film that is formed by hardening a resin material by application of heat, light, or other energy after the film is formed by coating a curable resin material.
• the curable resin material is, therefore, preferably a heat-curable resin material or photocurable resin material.
• a photocurable resin material can be advantageously used, since it does not require a large and long heating furnace for forming the mold layer, and hardening can be carried out in relatively shore period.
• the photocurable resin material is preferably a photocurable monomer or oligomer, more preferably an acrylic monomer or oligomer, and most preferably a (meth)acrylate, that is, an acrylate or methacrylate, monomer or oligomer.
• the flexible mold having such a mold layer permits a photocurable molding material to be used in the manufacture of PDP ribs or other fine structures.
• These acrylic monomers or oligomers may be used alone or in an arbitrary combination of two or more of them. Although features of acrylate monomers or oligomers are described above, similar features can be obtained for methacrylate monomers or oligomers.
• the curable resin material may contain an optional additives. For example, when the curable resin material is a photocurable resin material, suitable additives may include a photoinitiator.
• the most suitable compound should be selected in accordance with the type of the curable resin material, and examples may include 2-hydroxy-2-methyl- 1 -phenyl-propane- 1 -on, bis(2,4,6-trimethylbenzoyl)-phenyl phosphin oxide.
• These photoinitiators may be used alone or in combination of two or more of them.
• the photoinitiator may be used in widely variable amount depending upon the type of the curable resin material, and is typically used in an amount in the range of about 0.1 to 10% by weight, and preferably in the range of about 0.5 to 2% by weight, relative to the total amount of the curable resin material.
• lithium salt of an organic fluorine compound used in the present invention other antistatic agent such as lithium perchlorate, lithium nitrate, etc., may be used in additional small amount, as long as the operative effect of the present invention is not adversely affected, or rather, the operative effect of the present invention can be thereby improved.
• antistatic agent such as lithium perchlorate, lithium nitrate, etc.
• additives that can be used include, for example, amine surfactants, ionic surfactants, etc.
• the mold layer may be used in varied thickness depending upon such factors as shape and size of ribs. Typically, the thickness of the mold layer is in the range of about 5 to 1000 ⁇ m, preferably in the range of about 100 to 500 ⁇ m. If the mold layer is too thin, ribs of specified height cannot be formed. The thickness of the mold layer may be suitably modified depending upon the presence or absence of a support.
• the mold layer is preferably carried by a support.
• the support that carries the mold layer may be composed of an arbitrary material, and since flexibility suitable for handling needs to be given to the mold, it is preferably composed of a support material having suitable hardness or softness.
• the support material a material that is much harder than the mold material forming the mold layer involved in forming the groove (preferably, a photocurable material such as photocurable resins), preferably a plastic material having a high glass transition temperature. Since, in general, hardening shrinkage of a photocurable resins is about a few %, if a soft plastic film is used for the support, the hardening shrinkage of the former may give rise to dimensional change in the support itself and dimensional accuracy of the groove pitch cannot be controlled within a few tens of ppm.
• the plastic film is hard, since dimensional accuracy of the groove pitch of the mold depends only upon the dimensional change of the plastic film, in order to provide a mold having desired dimensional accuracy of the groove pitch, it is sufficient to perform post-processing such that dimension of the plastic film is as intended and shows no change in the mold after the manufacture.
• Hardness of the support material may be expressed, for example, as rigidity to tension, that is, as tensile strength.
• the tensile strength of the support material is typically at least about 5 kg/mm , and preferably at least about 10 kg/mm . If the tensile strength of the support material is less than 5 kg/mm , workability in the handling is degraded when the obtained mold is released from the metal master pattern 5 or when the PDP rib is released from the mold, and this may lead to breaking or rupture.
• Preferable support for implementing the present invention is a film of plastic material having good workability in handling as well as good hardness.
• plastic material suitable for the support examples include, but are not limited to, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), stretched polypropylene, polycarbonate, triacetate, etc.
• PET film is particularly useful for the support, and for example, polyester film such as Tetron film may be advantageously used as the support.
• PET film is particularly useful for the support, and for example, polyester film such as Tetron film may be advantageously used as the support.
• These plastic films may be used alone as a single layer film or two or more of them may be used in combination as a composite film or a laminated film.
• plastic film or other support may be used in varied thickness depending upon the construction of the mold or the PDP, and the thickness is typically in the range of about 50 to 500 ⁇ m, and preferably in the range of about 100 to 300 ⁇ m. If thickness of the support is outside of above-mentioned range, workability in handling may be degraded. The thicker the support, the more advantageous it is in strength.
• the present invention also relates to a method of manufacturing the flexible mold as described above.
• the method of manufacturing the flexible mold according to the present invention comprises, in particular, the steps of: forming a layer of a photocurable resin material by coating a photocurable resin material containing a lithium salt of an organic fluorine compound as an antistatic agent to a predetermined film thickness on a metal master pattern having on the surface thereof a protrusion pattern in shape and size corresponding to the groove pattern of the mold; laminating a transparent support consisting of a film of plastic material on said metal master pattern to thereby form a laminate of said metal master pattern, said layer of a photocurable resin material, and said support; irradiating said laminate with light from the side of the support to harden said layer of photocurable resin material; and releasing said mold layer formed by the hardening of said photocurable resin material together with said support from said metal master pattern.
• a flexible mold for manufacturing a substrate (back panel) for PDP as shown in Fig. 2, which has the construction as shown schematically in Figs. 3 and 4, may be manufactured advantageously by following steps as shown in order in Fig. 5.
• a metal master pattern 5 having shape and size corresponding to the substrate for PDP to be manufactured, a support 1 consisting of a transparent plastic film (hereinafter refe ⁇ ed to as support film), and a laminate roll 23 are provided.
• the metal master pattern 5 has partition walls 14 on the surface thereof which are of the same pattern and shape as the ribs on the back panel for PDP.
• photocurable mold material 11 is coated to the end surface of the metal master pattern 5 in a specified amount.
• a flexible and elastic material is used as the support film 1 , even if shrinkage of the photocurable mold material 11 takes place, close contact with the support film 1 prevents dimensional change of 10 ppm or greater as long as the support film itself does not deform.
• the laminate roll is slid on the metal master pattern 5 in the direction of an a ⁇ ow.
• the mold material 11 is evenly distributed evenly in specified thickness, and gaps between the partition walls 14 are filled with the mold material 11.
• the flexible mold 10 is released without impairing its integrity from the metal master pattern 5. If necessary, the flexible mold 10 may be placed in a thermohygrostat and subjected to a conditioning process following a predetermined schedule. With this conditioning process, undesired dimensional change of the obtained mold can be suppressed, and a mold having proper size can be obtained.
• the flexible mold of the present invention can be manufactured relatively simply, irrespective of the size and dimensions, as long as suitable well known and conventional laminating means and coating means are employed.
• a large-size flexible mold can be manufactured simply and easily with no limitation.
• the flexible mold of the present invention is useful in the manufacture of various fine structures.
• the flexible mold of the invention is useful for molding of ribs for PDP with straight rib pattern or lattice rib pattern.
• a large screen size PDP with rib structure that does not permit leakage of UV light from discharge cells for display can be easily manufactured simply by employing a laminate roll in place of vacuum equipment and/or complicated process.
• the present invention is therefore also directed to a manufacturing process for manufacturing fine structures using the flexible mold of the invention.
• the method of manufacturing a fine structure comprises, in particular, the steps of: providing a flexible mold that has on the surface thereof a groove pattern of shape and size co ⁇ esponding to the protrusion pattern of the fine structure, said mold layer containing a lithium salt of an organic fluorine compound as an antistatic agent; placing a curable molding material between said substrate and said mold layer of said mold, and filling said molding material into said groove pattern of the mold; curing said molding material and forming a fine structure consisting of said substrate and the protrusion pattern integrally connected thereto; and releasing said fine structure from said mold.
• the fine structure may have various structures, and is typically exemplified by a substrate (back panel) for PDPs which is provided with ribs on a glass plate.
• a substrate back panel
• the manufacturing process of a substrate for PDP as shown in Fig. 2 will be described below with reference to Fig. 6.
• Manufacturing equipment as shown in Figs. 1 to 3 of Japanese Unexamined Patent Publication (Kokai)
• a glass plate is provided with electrodes arranged in parallel to each other at a constant spacing, and is set on a surface plate.
• the flexible mold 10 of the present invention is placed at specified position on the glass plate 31, and the glass plate 31 and the mold 10 are suitably aligned with each other.
• the flexible mold 10 is preferably provided in advance with an alignment mark such as a cross mark formed in an area other than the rib-forming area. Since the mold 10 is optically transparent, the alignment with the electrodes on the glass plate 31 can be carried out easily. More specifically, the alignment may be performed visually, or by using a sensor such as a CCD camera, such that the grooves of the mold 10 are set in parallel to the electrodes on the glass plate 31. If necessary, temperature and humidity may be adjusted to bring the grooves into coincidence with the spacing between adjoining electrodes on the glass plate 31. This adjustment is required because the mold 10 and the glass plate 31 expands or contracts to different extent in accordance with change of temperature and humidity.
• a laminate roll 23 is placed on an end portion of the mold 10.
• the laminate roll 23 is preferably a rubber roll.
• the one end portion of the mold 10 is preferably fixed on the glass plate 31, so that displacement of the mold 10 with respect to the glass plate 31 may be avoided after the alignment has been completed.
• rib precursor 33 required to form ribs is supplied onto the glass plate 31.
• the rib precursor can be supplied using, for example, a hopper with nozzle for paste.
• rib precursor means any molding material that can be formed into the rib molding as the intended end product, and there is no special limitation as long as the rib molding can be formed.
• the rib precursor may be thermo-setting or photocurable.
• a photocurable rib precursor can be used very effectively in combination with the above-described transparent flexible mold.
• the flexible mold rarely includes air bubbles or defects such as deformations, and can suppress uneven scattering of light. Therefore, the molding material is hardened uniformly to form ribs of constant and good quality.
• An example of composition suitable for the rib precursor is a composition basically including:
• a ceramic component for giving the shape of the ribs such as aluminum oxide
• a glass component for filling the gap between the ceramic component and adding density to the ribs such as lead glass or phosphate glass
• a binder for containing, holding and binding ceramic component with each other, and its curing agent or polymerization initiator Hardening of the binder component is preferably achieved not by heating or warming, but by i ⁇ adiation with light, since thermal deformation of the glass plate no longer needs to be considered in this case.
• an oxidation catalyst consisting of oxides, salts or complexes of chromium (Cr), manganese
• Mn iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), indium (In) or tin (Sn), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), iridium (Ir), platinum (Pt), gold (Au) or cerium (Ce) may be added to the composition.
• the rib precursor 33 is not supplied uniformly to the entire glass plate 31. As shown in Fig. 6(A), the rib precursor
• the rib precursor 33 has only to be supplied to the portion of the glass plate 31 near the laminate roll 23, since, in the step described later, the laminate roll 23 is moved on the mold 10 so as to spread the rib precursor 33 uniformly on the entire glass plate 31.
• the rib precursor 33 has viscosity of typically about 20,000 cps or less, preferably about 5,000 cps or less. If the viscosity of the rib precursor is higher than about 20,000 cps, it is difficult to spread the rib precursor sufficiently with the laminate roll, and as a result, air may be entrained into the groove portion of the mold, and may become a cause of defects of the ribs.
• the viscosity of the rib precursor is about 20,000 cps or less, the laminate roll needs to be moved from one end of the glass plate to the other end only once for spreading the rib precursor uniformly between the glass plate and the mold and filling all groove portions uniformly without giving rise to inclusion of air bubbles.
• Method of supplying the rib precursor is not restricted to the above-described method.
• the rib precursor may be coated to the entire surface of the glass plate, although this is not shown.
• the rib precursor for coating has the same viscosity as described above.
• the viscosity of the rib precursor is typically about 20,000 cps or less, preferably 5,000 cps or less.
• a rotary motor (not shown) is driven to move the laminate roll 23 on the mold 10 as shown by the a ⁇ ow in Fig. 6(A). While the laminate roll 23 is thus moved on the mold 10, pressure is applied to the mold 10 successively from one end portion to the other end portion by the weight of the laminate roll 23 itself so that the rib precursor 33 is spread between the glass plate 31 and the mold 10 and is filled into the grooves of the mold 10. Thus, the rib precursor successively replaces air in the grooves and is filled into it.
• the rib precursor may be spread in the thickness in the range of a few ⁇ m to a few tens ⁇ m by suitably controlling the viscosity of the rib precursor, or the diameter, weight or moving speed of the laminate roll.
• the laminate consisting of the glass plate 31 and the mold 10 is placed in a i ⁇ adiation apparatus (not shown), and the rib precursor 33 is i ⁇ adiated with light such as ultraviolet ray (UV) via the glass plate 31 and the mold 10, as shown in Fig. 6(B). After hardening, a molding of the rib precursor, that is, the rib per se is obtained.
• UV ultraviolet ray
• the glass plate 31 and the mold 10 are removed from the irradiation apparatus, and the mold 10 is separated and removed, as shown in Fig. 6(C). Since the mold 10 of the present invention is excellent in ease of handling, if a material of low adhesion is used as coating layer of the mold, the mold 10 can be easily separated and removed with small force without damaging the rib 34 adhered to the glass plate 31. It should be appreciated that no large scale apparatus is required for the separation and removal of the mold.
• Total pitch (distance between the centers of ribs at both ends) was 900.221 mm.
• a photocurable resin was prepared by mixing aliphatic urethane acrylate oligomer (manufactured by Daicel-UCB, Co.), phenoxyethyl acrylate, and 2-hydroxy-2-methyl-l-phenyl-propane-l-one (photoinitiator: Trade name "Darocure 1173"; manufactured by Chiba Speciality chemicals, Co.) in weight ratio of 100:25:1.25. Then, a propylene carbonate solution of (CF 3 SO 2 )2NLi was added to this mixture as an antistatic agent. The amount of the added antistatic agent was 0.5% by weight relative to the amount of UV-curable resin. Concentration of the lithium salt was 20% by weight. The UV-curable resin for forming mold layer was thus obtained.
• PET film of 1300 mm in width and 100 ⁇ m in thickness (Trade name, "HPE”; manufactured by Teijin Co.) was provided. Then, the above-described UV-curable resin was coated in the shape of a line to the upstream end of the prepared metal master pattern. Then, above-described PET film was laminated on the surface of the metal master pattern so as to cover it. When a laminate roll was used carefully to press the PET film, the UV-curable resin was filled into the recesses of the metal master pattern.
• the UV-curable resin was i ⁇ adiated via the PET film using a fluorescent lamp (manufactured by Mitsubishi- Osram Co.) with light having wavelength of 300 to 400 nm for 30 seconds.
• the UV-curable resin was hardened and the mold layer was thus obtained.
• the PET film together with the mold layer was released from the metal master pattern, and thus a flexible mold having a multiplicity of grooves of shape and size co ⁇ esponding to the ribs on the metal master pattern was obtained. Thickness of the mold layer was about 300 ⁇ m.
• the mold was a ⁇ anged in alignment to a glass substrate for PDP.
• the mold was placed with the groove-pattern facing the glass substrate.
• photosensitive ceramic paste was filled between the mold and the glass substrate.
• the ceramic paste used had following composition.
• photocurable oligomer dimethacrylate of bisphenol-A-diglycidyl ether (manufactured by Kyoeisya Chemical Co.) 21.0 g photocurable monomer: triethyleneglycol dimethacrylate (manufactured by Wako Pure Chemicals Industries, Co.) 9.0 g diluent:
• photoinitiator bis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (Trade name "Irgacure 819"; manufactured by Chiba Speciality Chemicals, Co.)
• surfactant phosphate propoxyalkyl polyol 3.0
• inorganic particle mixed powder of lead glass frit and ceramic particles (manufactured by Asahi Glass, Co.) 180.0 g
• the mold was laminated so as to cover the surface of the glass substrate.
• laminate roll was used carefully to press the mold against the substrate, the ceramic paste was completely filled into the grooves of the mold.
• a fluorescent lamp manufactured by Philips Co.
• Philips Co. was used to i ⁇ adiate the ceramic paste with light having wavelength of 400 to 450 nm for 30 seconds from both sides via the mold and the glass substrate.
• the ceramic paste was hardened to form the ribs.
• the glass substrate together with the ribs formed thereon was separated from the mold, and a back panel for PDP consisting of the glass substrate with ribs formed thereon was obtained as intended.
• Example 7 The procedure described in Example 1 was repeated to fabricate a flexible mold.
• lithium salt solutions of different concentration as shown in Fig. 7, that is:
• propylene carbonate solution C20...20% by weight propylene carbonate solution were used, and blended amount of the lithium salt solution relative to the amount of resin was also varied in the range of 1 to 5% by weight.
• each of the lithium salt solutions was blended to resin in different blending amount to prepare UV-curable resin
• each of the UV-curable resins was coated to PET film of 100 ⁇ m in thickness and i ⁇ adiated with UV-light to fabricate the mold with a mold layer of 300 ⁇ m in thickness.
• Example 2 The procedure described in Example 1 above was repeated to fabricate a flexible mold.
• lithium salt solution in the form of 20%> by weight propylene carbonate solution (C20) was used and the blended amount of the lithium salt solution relative to total amount of resin was varied in the range of 0.0 to 2.0% by weight.
• UV-curable resin was prepared by blending the lithium salt solution in different blended amount, each UV-curable resin was coated to a PET film of 100 ⁇ m in thickness and was i ⁇ adiated with UV light to form the mold with a mold layer of 300 ⁇ m in thickness.
• the test specimen was fixed at one side thereof to a transverse member and was suspended vertically like a Noren. With the test specimen suspended, the adhered PET film was peeled off at the speed of about 300 mm/s, and the electrification voltage (Kv) immediately after peeling was measured at temperature of 22 °C and relative humidity (RH) of 55%. Measurement result as plotted in Fig. 8 was thus obtained.
• a commercially available electrification measuring apparatus (Model FMX-002; manufactured by SIMCO Co.) was used for the measurement of electrification voltage. As can be seen from the graph shown in Fig. 8, the electrification voltage of the mold can be lowered by adding the lithium salt solution, and by increasing the blended amount of the lithium salt solution relative to the total amount of resin.

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