Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/775—Photosensitive materials characterised by the base or auxiliary layers the base being of paper
  • G03C1/79—Macromolecular coatings or impregnations therefor, e.g. varnishes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/56—Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/58—Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof

Definitions

• This invention relates to base paper for photographic prints and in particular to resin coated photographic base paper in which at least the face side resin coating is a multilayer coating.
• the base paper used for photographic prints typically comprises a high quality paper substrate which has a coating on one or both sides. It acts to provide a suitable physical base structure for the image carrying layer(s), usually in one or more layers of gelatin based photographic emulsion.
• Historically such papers carried a surface coating of baryta (barium sulphate).
• baryta barium sulphate
• synthetic polymeric material typically a polyolefin resin.
• the resin coating particularly provides protection to the paper from the relatively agressive materials and conditions used in modern processing especially of colour prints.
• Such paper is commonly known as photographic base paper often abbreviated to “photobase”, and the polymer coated type as “resin coated photographic base paper” often abbreviated to “resin coated photobase”.
• the uncoated paper is commonly referred to as "raw photobase”.
• the side of a sheet of photobase which is to be coated with the photographic emulsion is commonly known as the “face side” and the other side as the “wire side” (because it is this side that is in contact with the Foudrinier "wire” during papermaking).
• the coating of resin on the face side of the paper is known as the “face side resin coating” and that on the wire side of the paper the “wire side resin coating”.
• the face side resin coating is typically pigmented to prevent (or at least reduce) the loss in photo-definition arising from internal reflection of incident light in developed prints made from it.
• the pigment used is usually a white pigment such as titanium dioxide.
• French Patent Specification No. 2 099 168 of Fuji Photo Film describes a two layer coating in which the first (inner) layer is of polyethylene and is extrusion coated at a temperature of 320 to 350°C and a second (outer) layer of polyethylene is coated at 260 to 300°C.
• the intent is that by coating the inner layer at a high temperature atmospheric oxidation at such high temperature can be turned to advantage to increase the adhesion between the resin coating and the base paper.
• British Specification No. 1 339 045 also of Fuji Photo Film has a two layer face side polyethylene resin coating in which the opacifying pigment is concentrated in the second (outer) layer.
• British Patent Specification 2 061 131 of Felix Schoeller is to photobase in which the face side resin coating,has two layers in which the inner layer is not stabilised against oxidative degradation and the outer layer is so stabilised. Atmospheric oxidation of the inner layer can promote adhesion between the coating and the substrate.
• LDPE low density polyethylene
• HDPE high density polyethylene
• the maximum amount used is relatively small because it is prone to give rise to "gels". Gels are small regions of resin which are harder than the resin in the surrounding area. As they tent to protrude from the surface of the resin, they give rise to faults in the layer of photographic emulsion coated on top of the resin.
• the gain in stiffness that can be achieved in practice by blending HDPE and LDPE in the face side resin is thus modest.
• stiff resins such as polypropylene (PP) or polycarbonate (PC) cannot be satisfactorily blended with LDPE to form an homogeneous coating which adheres well to the base paper.
• the resin coating on the wire side of the photobase can contain a relatively high amount of HDPE because the presence of gels is less objectionable and, because the wire side resin does not need to be pigmented, there is less likelihood of forming gels in the absence or at low concentrations of a pigment like TiO2. This can be used to make a stiffer wire side coating to compensate for curl caused by the coating of a gelatin based photographic emulsion on the photobase.
• the present invention accordingly provides resin coated photographic base paper comprising a substrate of paper carrying on its face side a composite coating comprising from 10 to 50 g.m ⁇ 2 of an extruded first coating layer of a low density polyethylene or a blend of low density and high density polyethylenes containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment and, overlying the first coating layer and firmly bonded thereto, from 0.1 to 18 g.m ⁇ 2 of an extruded second coating layer of a polymer having a stiffness modulus of at least 2.0 GPa.
• a polycarbonate resin layer as the second layer in the base paper of the invention which, accordingly, includes resin coated photographic base paper comprising a substrate of paper carrying on its face side a composite coating comprising from 10 to 50 g.m ⁇ 2 of an extruded first coating layer of a low density polyethylene or a blend of low density and high density polyethylenes containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment and, overlying the first coating layer and firmly bonded thereto, from 0.1 to 18 g.m-2 of an extruded second coating layer of a polycarbonate resin.
• the invention specifically includes the provision of a polyolefin resin coating on the wire side of the paper.
• a wire side resin coating improves the resistance of the photobase to the ingress of developer and fixer solutions and chemicals used in making photographic prints.
• the wire side resin coating may also comprise more than one layer and, in particular, it can include an outer layer of a stiff polymer.
• the invention accordingly includes resin coated photographic base paper comprising a substrate of paper carrying on its face side a composite coating comprising from 10 to 50 g.m ⁇ 2 of an extruded first coating layer of a low density polyethylene or a blend of low density and high density polyethylenes containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment and, overlying the first coating layer and firmly bonded thereto, from 0.1 to 18 g.m ⁇ 2 of an extruded second coating layer of a polymer having a stiffness modulus of at least 2.0 GPa, in particular where the second coating layer is of a polycarbonate resin, and carrying on its wire side a coating of from 10 to 50 g.m-2 of a polyolefin resin, optionally which wire side coating comprises from 10 to 50 g.m ⁇ 2 of a first wire side coating layer of an extruded polyolefin resin and overlying the first wire side coating layer and firmly bonded thereto,
• the second layer of the face side coating is of a polymer having a stiffness modulus of at least 2.0 GPa.
• LDPE has a modulus of about 0.23 GPa
• HDPE of about 1.2GPa
• PP of about 1.4 GPa
• PC of about 2.5 GPa
• Stiffness moduli as referred to herein are those measured according to American Standard Test Method (ASTM) D 790-80. Because of its high stiffness polycarbonate is an especially good material for the second layer, and the use of polycarbonate for the second layer constitutes a specific and important aspect of this invention.
• the polymer used in the second layer must be substantially colourless, capable of being extruded typically at temperatures up to 300°C, substantially inert to light and in particular resistant to discolouration on exposure to light, it must not interfere with photographic emulsion and it must be substantially inert to the materials used in developing and fixing a photographic image.
• Polymers which could be used as the second layer include PC, mentioned above, polyamides such as Nylon 11, Nylon 6 and Nylon 66, and polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).
• Polymers such as polystyrene and polyvinylchloride are generally not sufficiently heat and/or light stable to be suitable and the stabilizers commonly used currently are either not acceptable in photobase or reduce the stiffness of the polymer so much as to make it unsuitable.
• the second layer of the stiff polymer may be of a single homopolymer, as described above, or it may be a co-polymer or a blend of polymeric materials having the required stiffness.
• a single "second layer" of stiff polymer it is possible that multiple layers of the same, or more usually differing compositions can be employed. Examples of such multiple layers within the second layer could include a clear stiff outer layer and a pigmented stiff inner layer or a stiff outer layer with an inner layer of a blend of the outer layer polymer with the first layer polymer e.g. to give a PC/PC + LDPE/LDPE structure for the face side resin coating with the LDPE and possibly the blend layer containing pigment.
• One reason for including a layer (or layers) of a polymer blend is to enhance the effective adhesion between the "first" and "second” layers. This, and other methods of enhancing adhesion, are discussed further below.
• the second layer of stiff polymer, is thin in that it constitutes an amount of 0.1 to 18 g.m ⁇ 2, corresponding approximately, depending on the densities of the polymer used, to a thickness of 0.1 to 15 »m.
• the densities of some stiff polymers, referred to above, are HDPE 0.95, PP 0.9, PC 1.2 g.cm ⁇ 3. Broadly, the heavier (thicker) the second layer the greater the improvement in stiffness.
• the stiff polymers notably polycarbonate, are generally more expensive than the polyethylene used conventionally and, thus, the use of second layers containing less than 15 g.m ⁇ 2 polymer is desirable to save cost.
• the second layer of stiff polymer adheres well to the first layer.
• blends in an intermediate layer has been referred to above. This can be done when the respective polymers can be blended to give an adequately homogenous and stable blend. Usual!y, the blend will have physical properties intermediate the individual components depending on the proportions.
• Another possibility is to provide an intermediate layer between the "first" and "second” coating layers of a polymer which strongly adheres to the first and second coating layers.
• Suitable strongly adhesive polymers include ethylene-vinyl acetate copolymers (EVA), ethylene-acrylic acid copolymers (EAA), ethylene-methacrylic acid copolymers (EMA) and the ethylene-vinylacetate terpolymers, ethylene terpolymers and chemically modified polyolefin resins such as those sold under the trade designations CXA by DuPont, Modic by Mitsubishi and Plexar by Chemplex.
• the intermediate layer will typically be from 1 to 10 g.m ⁇ 2 and more commonly from 4 to 9 g.m ⁇ 2.
• the intermediate layer may be of the strongly adhesive polymer in a blend with, for example, polyethylene.
• Such blends can contain up to 75% by weight of the other polymer given that the blend has appropriate properties.
• the use of such blends can be important especially where the intermediate layer is pigmented as pigments are usually used as masterbatches in e.g. low density polyethylene.
• the provision of a strongly adherent intermediate layer is considered to be a specific and important subsidiary feature of the invention. It is of particular value when the second layer is of polycarbonate resin.
• the invention accordingly, further includes resin coated photographic base paper comprising a substrate of paper carrying on its face side a composite coating comprising from 10 to 50 g.m ⁇ 2 of an extruded first coating layer of a low density polyethylene or a blend of low density and high density polyethylenes containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment, overlying the first coating layer, a second coating layer of from 0.1 to 18 g.m ⁇ 2 of a polycarbonate resin, and intermediate the said first and second coating layers, a layer of from 1 to 10 g.m ⁇ 2 of a polymer, which is strongly adhesive towards both the first and second layers, serving to firmly bond the said first and second layers where the photobase includes a wire side resin coating with a second coating layer of stiff polymer an intermediate layer of a strongly adhesive polymer can be included.
• an intermediate layer of a strongly adhesive polymer it may, advantageously include a pigment, and in particular titanium dioxide, as described in more
• a known problem in making resin coated photobase is in ensuring good adhesion between the resin coasting and the raw paper base.
• Methods of overoming this difficulty are known but the use of a coextrusion technique in this invention opens up the possibility of deliberately coextruding a polymer layer between the pigmented LDPE first coating layer and the raw base which serves to ensure good adhesion.
• the coatweights used will typically be similar to those for the "intermediate" layer referred to above and will usually be from 1 to 10 g.m ⁇ 2, more commonly from 4 to 9 g.m ⁇ 2.
• the polymers which can be used for this include those indicated above as being suitable for inclusion in a strongly adhesive layer between the "first" and "second" coating layer.
• the invention accordingly, further includes resin coated photographic base paper comprising a substrate of paper carrying on its face side a composite coating comprising from 10 to 50 g.m ⁇ 2 of an extruded first coating layer of a low density polyethylene or a blend of low density and high density polyethylenes containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment, overlying the first coating layer, a second coating layer of from 0.1 to 18 g.m ⁇ 2 of a polycarbonate resin, and intermediate the base paper and the said first coating layer, a layer of from 1 to 10 g.m-2 of a polymer, which is strongly adhesive towards both the base paper and the first coating layer, serving to firmly bond the said base paper and the first coating layer.
• the effect of providing a thin second layer of a stiff polymer overlying a pigmented first layer in the face side resin coating is to increase the stiffness of the photobase.
• the increase in stiffness which might be expected from consideration of photobase according to this invention as a compound beam is difficult to assess precisely because it depends on assumptions on the behaviour of the various parts of the photobase and the interactions at the interfaces between polymer and polymer and polymer and paper. Nevertheless, from baseline properties the increase observed is generally greater than would be expected.
• the second layer being thin, experiences a degree of orientation during extrusion and/or cooling which causes the second layer to have a higher stiffness than the polymer itself (published stiffness data being for test "plaques" typically several mm thick) or that the photobase is made stiffer by the composite structure.
• the second layer can be unpigmented or pigmented with conventional opacifying pigment.
• the stiff polymers used in the second layer can be relatively difficult to coextrusion coat onto paper if they contain large amounts of pigment, e.g. greater than about 5%.
• the amount of opacifying pigment can be similar to that used in the first layer. If used the opacifying pigment will normally be a white pigment typically titanium dioxide. There can be a benefit in using low pigment loadings in the second layer in that it can enable the use of higher pigment loadings in the first layer. This is discussed in more detail below.
• the first layer is of LDPE or a blend of at least 50% by weight, and more usually at least 70% by weight, of LDPE with HDPE and contains opacifying pigment.
• the opacifying pigment is usually white, in which case it is almost invariably titanium dioxide and usually rutile, although it can be black e.g. carbon black as is used in making photobase for so-called "instant" prints.
• the overall amount of pigment is such as to give the desired degree of opacity and, as indicated above, the amount used is at least 5% by weight. When rutile titanium dioxide is used the amount is typically at least 8% by weight and commonly 12 to 15% by weight of the layer.
• the method of this invention enables the use of satisfactorily high concentrations of anatase to achieve good opacity and tint without the severe production problems usually encountered.
• concentration of pigment can be up to 25% by weight and possibly higher e.g. up to 35% by weight.
• a strongly adhesive intermediate layer it can be pigmented and the amount of pigment used will typically be similar to those used in the LDPE (first) layer.
• the range of pigment content referred to above are typical of conventional resin coated photobase which has a face side resin coating thickness of from 20 to 40 »m. Because the method of present invention enables the use of higher concentration of pigment it is possible to use somewhat thinner pigmented layers than previously considered appropriate whilst maintaining opacity.
• the wire side polyolefin resin coating according to the invention can be of a conventional type for photobase. Typically it will be of LDPE or a blend of LDPE and HDPE which may include more than 50% by weight e.g. up to 75% by weight HDPE.
• the amount of the wire side coating will typically be from 5 to 50 and more commonly from 15 to 35 g.m ⁇ 2. Whilst it is possible to include pigment in the wire side resin coating, it is not necessary or particularly advantageous to do so. When an overlying layer of stiff polymer and, optionally, an intermediate layer of strongly adhesive polymer are used the thickness of these layers will typically be similar to those for the face side resin coating.
• the surface finish on both wire and face side resin coatings can be gloss, silk, stipple or other finish as desired.
• the maximum degree of gloss on the face side resin coating which can be obtained in the product and by the method of the present invention is higher than with equivalent currently commercially available materials.
• the improvement in the maximum degree of gloss is particularly noticeable when the second layer is polycarbonate. Morever, this improvement can be maintained at higher line speeds than are practical for producing gloss surfaces on LDPE coatings. This is an important practical advantage.
• the outer surface of the wire side resin can be further treated with a conventional coating to aid writability.
• a further and entirely unexpected advantage in using a stiff polymer, specifically polycarbonate, second layer in the face side resin coating is that the incidence of pitting is reduced as compared with that obtained with a pigmented LDPE monolayer. We do not understand why this result is obtained but it is important, particularly as it can be achieved with low coatweights of the second layer.
• the photographic base paper of this invention is made by extrusion coating multiple layers of various polymeric resins onto paper. At least some of the layers are sufficiently thin that, using current technology, it would be impratical and might not be possible to undertake commercial production by extruding such unsupported thin layers. This difficulty can be overcome by using a coextrusion coating method in which two or more coating layers are extruded through a single extrusion die and, thus, simultaneously coated onto the substrate. In practical operation, we expect that all layers (two or more) in the multi-layered coating will be coextruded in a single coating operation.
• the invention includes a method of making resin coated photographic base paper which comprises co-extruding onto the face side of a paper substrate a composite coating of from 10 to 50 g.m ⁇ 2 of a first layer of a low density polyethylene or a blend of low density and high density polyethylenes containing at least 50% by weight low density polyethylene, the first layer containing at least 5% by weight of opacifying pigment, and, disposed on the side of the first layer remote from the paper substrate from 0.1 to 18 g.m ⁇ 2 of a second layer of a polymer having a stiffness modulus of at least 2.0 GPa.
• the second layer is particularly preferably of a polycarbonate resin.
• the co-extruded structure can specifically include further layers such as a layer between the "first" and “second” coating layers of a polymer which is strongly adherent to the first and second layers.
• the invention further includes a method of making resin coated photographic base paper which comprises co-extruding onto the face side of a paper substrate a composite coating of first and second layers as set out above and, before or after co-extruding the coating on the face side of the paper, extrusion coating a coating of from 10 to 50 g.m ⁇ 2 of a polyolefin resin onto the wire side of the paper substrate.
• the coating on the wire side of the substrate can be a multilayer coating, as is described above and when this is so it can be co-extruded in a manner similar to that described above for the face side resin.
• the relative amounts of layers in the face side coating can be controlled by regulating the output of the corresponding extruders.
• Conventional co-extrusion equipment can be used provided that it can effect extrusion at the temperatures used in making resin coated photobase which are typically 280 to 320°C which is rather higher than in other applications.
• the wire side resin coating can be extrusion or co-extrusion coated before or after the co-extrusion coating of the face side and can be carried out in line on a tandem coater or off line in a separate coating step.
• the adhesion between gelatin based photographic emulsion and the types of polymeric resin used in photobase is not particularly good and the surface of the face side resin is treated e.g. by treatment with a corona discharge, to enhance adhesion of the emulsion.
• This technique can be applied to resin coated photobase of and made by the method of the present invention.
• the enhanced adhesion between photobase and emulsion generated by corona treatment will decay over time but it is possible to apply an anti-adhesion decay agent to prevent this, typically, a solution of gelatin which generates a very thin layer of gelatin of typically less than 1 g.m ⁇ 2 which adheres firmly to the photobase and provides a good bond with the photographic emulsion.
• the invention includes further treating corona treated photobase with an anti-adhesion decay agent, especially a solution of gelatin to form a very thin layer of gelatin thereon.
• the invention includes photographic printing paper which comprises photobase of or made by the method of the present invention carrying on top of the second layer a layer of a photographic emulsion.
• the layer of anti-adhesion decay agent will lie between the second layer and the layer of photographic emulsion.
• test methods were as follows:
• test methods are as follows:
• a strip of paper 1.5 inches (38.1 mm) wide is clamped so that 2.25 inches (57.2 mm) of the strip protrudes vertically upwards from a horizontal lamp.
• a probe carrying a force sensor is positioned to move in a line 4 cm above the clamping plane, perpendicular to the mid-line along the test strip. The probe is moved to deflect the test strip to a position such that the angle between the line connecting the probe tip and the clamp is 15° from the vertical, within a period from 2.5 to 30 seconds.
• the stiffness is the measured force at this position.
• the Kenley test instrument gives the result in grams force but are expressed herein as milliNewtons (mN). (The value obtained properly has the dimensions force x length ⁇ 1 but as the effective length is defined by the width of the test piece, Kenley rigidity is always quoted as the measured force).
• This test is carried out in a rectangular sample of paper 70 mm by 38.1 mm.
• the sample is clamped in vertically disposed jaws with the long edges of the paper horizontal and the short edges vertical.
• the clamping jaws are mounted to be rotatable about a vertical axis.
• the paper is positioned to contact a vertically disposed knife edge, attached to a force sensor, and positioned 25 mm from the clamping locus in the plane of the paper surface.
• the clamping jaws are rotated, under machine control, through a preset angle (15°).
• the rigidity of the sample is the maximum force detected by the sensor.
• the instrument gives a digital reading in milliNewtons(mN). (As with the Kenley test instrument the result properly has dimensions of force x length ⁇ 1 but is always quoted as force as indicated by the readout.)
• Raw photographic base paper having a grammage of 170 g.m ⁇ 2 was resin coated on a pilot 2-layer co-extrusion coating line using a matt chill roll.
• Various coating structures were produced as set out in Table 2a below.
• the control structure was made by co-extruding pigmented LDPE in both extrusion channels of the co-extruder onto the new base paper to give effectively a monolayer.
• the three layer structures were made by first extruding a monolayer coating the raw base with the specified coatweight of pigmented LDPE and subsequently co-extrusion coating on top the specified EVA/PC layer.
• the photobase was subsequently mono-extrusion coated on the wire side with an unpigmented coating of 27 g.m ⁇ 2 of a 1:1 blend of LDPE and HDPE.
• the results of stiffness testing are set out in Table 2b below.
• the polymers used in the face side resin coatings were as follows:
• the pigmented EVA used was a blend of Escorin EVA (71.19%) and Ampacet masterbatch (28.9%).
• Raw photographic base paper having a grammage of 165 g.m ⁇ 2 was resin coated by co-extrusion using a gloss chill roll.
• Various coating structures were produced as described below with the coatweights (as measured on the product) given in Table 3a below.
• Pigmented resin layers were made up using appropriate amounts of unpigmented resin and of TiO2 masterbatch.
• the products made according to the invention had a face side coating comprising an inner layer of a pigmented blend of LDPE and HDPE (57.8% LDPE + 13.3% HDPE + 28.9% TiO2 masterbatch in LDPE) an intermediate layer of pigmented EVA (71.1% EVA + 28.9% TiO2 masterbatch in LDPE) and an outer layer of PC, and a wire side coating comprising an inner layer of a blend of 50% LDPE and 50% HDPE, an intermediate layer of unpigmented EVA and an outer layer of PC.
• the inner and intermediate layers on both sides of the photobase are difficult to distinguish from each other in the product.
• Table 3a below the intended or "target" coatweights for the individual inner intermediate (“inter”) and outer layers are given with the measured coatweight (derived from thickness measurement) of the inner and inter layers combined and of the outer layer, which can be distinguished by microscopic examination.
• control samples were used in this Example.
• the control was of a standard commercial resin coated photobase for colour printing based on a 165 g.m ⁇ 2 raw base with a mono-extruded face side resin coating of 30 g.m ⁇ 2 of a pigmented blend of LDPE and HDPE) and a mono-extruded wire side resin coating of 30 g.m ⁇ 2 of an unpigmented blend of 50% LDPE and 50% HDPE.

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• Spectroscopy & Molecular Physics (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Laminated Bodies (AREA)
• Paper (AREA)

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• 1984
  • 1984-11-24 GB GB848429729A patent/GB8429729D0/en active Pending
• 1985
  • 1985-11-19 EP EP19850308401 patent/EP0183467B2/en not_active Expired - Lifetime
  • 1985-11-19 DE DE8585308401T patent/DE3567973D1/de not_active Expired
  • 1985-11-22 ES ES549189A patent/ES8702668A1/es not_active Expired
  • 1985-11-22 JP JP26363885A patent/JPS61132949A/ja active Granted

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