Title of Invention	AN UNDER-PACKING FOR A BLANKET CYLINDER IN PRINTING PRESSES
Abstract	The self-levelling under-packing for printing presses, in particular offset presses, comprises at least one polyester-based layer and at least one polyurethane elastomer layer joined inseparably together.

Full Text

1 SELF-LEVELLING UNDER-PACKING FOR PRINTING PRESSES The present invention relates to under-packing for printing presses, particularly offset. With particular but non-exclusive reference to offset printing presses, these basically comprise three cylinders: the plate cylinder, the.blanket cylinder covered with rubber-coated fabric, and the impression cylinder. Below the said covering, the blanket cylinder comprises traditional under-packing formed, from individually removable (incompressible) gauged paper sheets for adapting the working diameter of the cylinder, and a separate under-blanket generally consisting of elastically compressible polybutadiene. For levelling purposes, it is already known in the printing press sector to also use, as under-packing, polyester films coated with adhesive on one side. The drawback of using paper and polyester is that both are rigid (hence not properly self-levelling), the former also not being fire-retardant From another patent of the same applicant (European patent 1,323,527), it is already known to use as under-packing a series of sheets (of paper or polyurethane) joined together by known pressure sensitive adhesive which enables the individual sheets to be removed to adapt the under-packing (of rubber-coated fabric) to the required thickness. An object of the present invention is to provide under-packing for printing presses which is able to satisfy a large series of requirements which the current art only partially satisfies; more precisely the under-packing of the invention is able to satisfy the following requirements: ecocompatibility, 2 flame retardance, resistance 1o solvents and to mechanical stresses, excellent machinability, long life, considerable versatility of use, excellent adaptation to the cylinder and resilient elasticity, better constructional geometry of the point of printing, considerable screen spreading uniformity, better printing stability. This and further objects which will be more apparent from the ensuing detailed description are attained by an under-packing for printing presses in accordance with the technical teachings of the accompanying claims. The invention will be more apparent from the following detailed description, provided by way of non-limiting example, of some preferred embodiments thereof presented in the form of examples on the basis of the following schematic figures from 1 to 3, all showing sections through different versions of under-packing of the invention. The under-packing of the invention (always indicated by 1) consists in its most general expression of a composite comprising a non-elastic part (defined as rigid for simplicity) indicated by 2 formed from a film based on high-limpidity polyester (PES) (for example transparent antinewton polyester, the term "antinewton" indicating that it has been slightly roughened by physical treatment to facilitate bonding to the other layer) as produced by POLICROM Inc., of Bensalem, Pennsylvania (USA) and by Toray, Japan), and an elastomeric covering 3 (on one side of the PES film) based on polyurethane and/or thermoplastic polyurethane (for example the products known by the name Estane 54660 and 58271 of NOVEON Inc, USA). On the opposite side to that with the elastomeric covering, the composite can present one or more strips of adhesive, or be completely adhesive- 3 coated, with products pf known type enabling facilitated attachment and detachment (pressure sensitive). For connection to the metal surface of a cylinder or of a "metal blanket", the adhesive, as already stated, will involve the whole surface in question. The adhesive is indicated by 4 in Figure 1. The composite can be obtained by known covering methods for producing composite film, for example by blade spreading/by calendering, by coextrusion or a combination of calendering and coextrusion. The thickness of the applied elastomer can vary from a minimum of 20 µm up to 1000 µm (for each layer, with a maximum of three layers in the case of a composite with more than one layer inseparably joined together). The thickness of the pplyester based film can vary between 40-100 µm (with one side totally adhesive-coated and including not more than 5 µm of adhesive in its thickness) and between 50-350 µm (without adhesive coating) or with partial adhesive coating along an edge strip. The examples are as follows: EXAMPLE 1 A polyester based film of 40 µm thickness totally adhesive-coated on one face (protected by a removable silicon-coated film) is covered on its non-adhesive side in known manner (blade spreading) with a 100 µm thickness of elastomer based on high solid polyurethane in DMF (dimethylforrnarnide) splvent. The adhesive is of the kind known as attach/reattach known as pressure sensitive. In particular the chemical/physical characteristics of the polyurethane are the following: 4 Shore hardness A 75-95 DIN 53505 Density g/cm3 1.10-1.25 DIN 53479 Cyclic compression % 60% compressible DIN 53517 Resilience % 30-40 DIN 53512 Solvent resistance resistant The test consisted of carrying out a cycle of one million compressions (of 60% on the compressible side) without undergoing any thickness decrease in 5 cm elastomeric discs subjected to 60% compressive load on the elastomer side with preload of 2N, cycle frequency 20Hz. EXAMPLE 2 Using the calendering method, a polyester based film of 40 µm thickness is covered on one side with an elastomer layer (based on high solid polyurethane) of 160 µm thickness. Reference should be made to Example 1 for adhesive-coating details. EXAMPLE 3 Using the known coextrusion method, a 100 µm polyester based film is combined with a 100 µm film of elastomer based on thermoplastic polyurethane. EXAMPLE 4 A 625 µm elastomer layer based on thermoplastic polyurethane is applied by calendering to a 175 µm standard polyester based film. EXAMPLE 5 The composite is formed from a 350 µm polyester based film and a 450 µm blade-spread layer of polyurethane based elastomer. EXAMPLE 6 5 The composite is formed from a 500 µm polyester based film and a 1000 µm calendered layer of polyurethane based elastomer. EXAMPLE 7 A 300 µm layer of polyurethane is applied (by blade-spreading) onto a first layer formed from a 175 µm polyester based film. A 50 µm polyester based film is then applied (by calendering) to the polyurethane layer, followed (by calendering) by a 255 µm elastomer layer (thermoplastic polyurethane), then finally by a 20 nm layer of thermoplastic polyurethane of different characteristics, for example hardness. EXAMPLE 8 (Figure 2) A first composite - obtained by calendering is formed from a 175 µm film (2a) of polyester, and a 600 µm polyurethane elastomer layer (3a) - is calendered on a second identical composite again formed from a 175 µm film (2a) of polyester, and a 600 µm polyurethane elastomer layer (3a). The result represents a different requirement of the user which is satisfied with a simple combining of two identical composites, i.e. of the same composite. EXAMPLE 9 (Figure 3) A coextruded and calendered multi-layer composite formed from a 350 µm first polyester film (2b), a 600 µm layer of thermoplastic polyurethane elastomer (3b), a 50 µm second polyester film (2b) and a 550 µm second polyurethane elastomer layer (3b). EXAMPLE 10 At least one 50 µm polyester film coated with pressure sensitive adhesive (i.e. detach/reattach) is applied to a composite comprising a 225 µm 6 polyurethane film and a 175µm polyester film. Instead of one adhesive-coated film, two or three can be used stacked individually and removable for thickness adaptation purposes. The scope of the invention also includes traditional methods for combining several composites together to obtain a resultant composite of adequate thickness possessing the required chemical/physical characteristics. 7 CLAIMS 1. Self-levelling under-packing for printing presses, particularly offset presses, characterised by comprising at least one polyester-based layer and at least one polyurethane elastomer layer joined inseparably together. 2. Under-packing as claimed in claim 1, wherein the polyester-based layer is between 50 µm and 350nm and the polyurethane elastomer layer is between 20 µm and 1000 µm. 3. Under-packing as claimed in claim 1, wherein the polyester-based layer is adhesive-coated on one side, in which case the thickness, including the adhesive, is between 40 and 100 µm, the adhesive thickness not exceeding about 5 µm. 4. Under-packing as claimed in claim 1 and 2, wherein several polyester-based layers and several polyurethane elastomer layers are provided, at least some of the layers of the one alternating with layers of the other. 5. Under-packing as claimed in one or more of the preceding claims, characterised in that the elastomeric component presents the following chemical/physical characteristics. Shore hardness A 75-95 DIN 53505 Density g/cm3 1.10-1.25 DIN 53479 Cyclic compression % 60% compressible DIN 53517 Resilience % 30-40 DIN 53512 Solvent resistance resistant (the cyclic compression test consisting of carrying out a cycle of one million compressions (of 60% on the compressible side, i e. on the 8 polyurethane elastomer side) without undergoing any thickness decrease). 6. Under-packing as claimed in claim 5, wherein the same chemical- physical characteristics apply to the polyurethane elastomer. 7. Under-packing as claimed in one or more of the preceding claims, wherein if several superposed polyester layers are used, some are removably joined together by a pressure sensitive adhesive strip along one of their edges. 8. Under-packing as claimed in one or more of the preceding claims, characterised in that if several polyurethane elastomer layers are used, at least one of these layers presents different characteristics, for example shore hardness, from the remaining layers. 9. Under-packing as claimed in one or more of the preceding claims, wherein the removable polyester layers are not more than three in number, with none of them exceeding 50 µm thickness. The self-levelling under-packing for printing presses, in particular offset presses, comprises at least one polyester-based layer and at least one polyurethane elastomer layer joined inseparably together.

Documents:

00001-kol-2005 abstract.pdf

00001-kol-2005 claims.pdf

00001-kol-2005 correspondence-1.1.pdf

00001-kol-2005 correspondence.pdf

00001-kol-2005 description(complete).pdf

00001-kol-2005 drawings.pdf

00001-kol-2005 form-1.pdf

00001-kol-2005 form-2.pdf

00001-kol-2005 form-3.pdf

00001-kol-2005 form-5.pdf

00001-kol-2005 priority document.pdf

1-kol-2005-granted-abstract.pdf

1-kol-2005-granted-claims.pdf

1-kol-2005-granted-correspondence.pdf

1-kol-2005-granted-description (complete).pdf

1-kol-2005-granted-drawings.pdf

1-kol-2005-granted-examination report.pdf

1-kol-2005-granted-form 1.pdf

1-kol-2005-granted-form 18.pdf

1-kol-2005-granted-form 2.pdf

1-kol-2005-granted-form 3.pdf

1-kol-2005-granted-form 5.pdf

1-kol-2005-granted-priority document.pdf

1-kol-2005-granted-reply to examination report.pdf

1-kol-2005-granted-specification.pdf

1-kol-2005-granted-translated copy of priority document.pdf