Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M7/00—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock
  • B41M7/02—Dusting, e.g. with an anti-offset powder for obtaining raised printing such as by thermogravure ; Varnishing

Definitions

• the substrates are also provided with a printed image, but the embossing phase is omitted.
• the relief is created by coating the print with a thermoplastic resin.
• the process is such that the substrate is printed with the printing inks customary for this in the offset printing process.
• a finely powdered thermoplastic synthetic resin is sprinkled on the still moist and sticky surface of the print. The excess is suctioned off from the non-printed and thus non-adhesive areas.
• the resin is heated up to temperatures above its melting point.
• thermoplastic synthetic resins A number of demands are placed on the thermoplastic synthetic resins, the most important of which are that the resin has no or as little self-coloring as possible and can be ground to a fine powder which does not block even under conditions of use and thus remains free-flowing, and that runs under the influence of heat in a smooth, scratch-free surface.
• Adequate adhesion to the various substrates in particular paper, cardboard, metal and glass, good flexibility, compatibility with the background color and non-stick surfaces are also required.
• polyamide resins based on dimerized fatty acids and ethylenediamine previously used for this purpose meet a number of these requirements, but are still in need of improvement.
• a major disadvantage is that these resins tend to deposit mixture components on the surface (sweating, blooming). This gives the surface a greasy appearance on the one hand, and on the other hand a clear and undesirable loss of gloss occurs.
• thermoplastic polyamides which are characterized in that fatty acids distilled as dimerized fatty acids according to A) with a proportion of dimerized acids of about> 90 wt .-% and hydrogenated fatty acids as dimerized fatty acids according to B) with an iodine number between 10 - 30 can be used alone or in a mixture.
• thermoplastic polyamides which are characterized in that 0.5 equivalents of components A) and B) in a mixing ratio of 1: 1, 0.1-0.5 wt .-%, based on A. ) and B) on azelaic acid, 0.5 equivalents of components D) and E) and 0.9-1.0 equivalents of ethylenediamine F) and up to 0.1 equivalents of 1,2-diaminopropane or poly (oxypropylene) diamine a molecular weight around 400 can be used.
• thermoplastic polyamides which are characterized in that to improve the leveling properties 0.1 to 0.3 wt .-%, based on acid components A) to E), a leveling agent based on silicones and / or polyacrylates can also be used.
• dimerized fatty acid refers to the commercially available polymerized fatty acids which have iodine numbers from approximately 90 to 130 and whose dimeric fatty acid content has been increased to approximately 85-100% by the generally customary processes.
• the iodine number can be reduced to values of up to about 10 by generally known hydrogenation processes.
• the iodine number is determined by the methods customary in practice and is given in iodine per 100 g of substance.
• the polymerized fatty acids can be prepared by the usual methods (compare, for example, US Pat. No. 2,482,761, US Pat. No. 3,256,304) from unsaturated natural and synthetic monobasic aliphatic acids having 12-22, preferably 18, carbon atoms.
• Typical, commercially available, polymeric fatty acids have the following composition before distillation:
• dimer acid fraction After distillation, the dimer acid fraction should be practically free of monocarboxylic acids and the proportion of trimerized and higher polymerized fatty acids should be ⁇ -_ 2% by weight.
• the composition of the fatty acids is determined by conventional gas chromatography methods (GLC), the indication of the dimer content in addition to the dimerized fatty acids also including the small proportions of fully or partially decarboxylated dimerization products necessarily formed in the dimerization process.
• LLC gas chromatography methods
• the dimeric fatty acids which are preferably used according to the invention have iodine numbers between 10-40 for the hydrogenated acids, 90-130 for the unhydrogenated acids and have proportions of dimeric acids between 70-100% by weight.
• the oleic acid and isostearic acid according to D) and E) used to produce the polyamide resins used according to the invention are commercially available technical products.
• the ratio of the distilled fatty acids A) and B), which have a content of approximately 85-100% by weight, preferably 90-99% by weight, and in which the proportion of tri- and higher-polymerized components is 2-2% , to the oleic acid / isostearic acid mixture D) and E) is in the range from 0.5: 0.5 to 0.75: 0.25.
• the co-dicarboxylic acids optionally used according to the invention for the production of the resins are aliphatic unbranched dicarboxylic acids, such as in particular azelaic acid and sebacic acid. These acids can be used in amounts of up to 2% by weight, based on the total amount of the dimerized fatty acids specified under A) and B). In addition to the two co-dicarboxylic acids mentioned, those with a shorter or longer chain can also be used if necessary. As a rule, however their use is not preferred.
• the ether diamines which can be used in the preparation of the resins used according to the invention are the commercially available compounds with molecular weights of about 200-2,000, such as, in particular, the 1,12-diamino-4,9-dioxadodecane, prepared by cyanoethylation of alpha-omega-diols with subsequent hydrogenation .
• the poly (oxyalkylene) polyamines which are obtained by known processes by catalytic aminolysis of poly (oxylalkylene) diols can also be used.
• the commercially available compounds with molecular weights between 400 and 2000 are preferably used.
• the ether diamines are added in amounts of 0.05 to 0.1 equivalents, based on total amine, compounds with low molecular weights being at the upper limit.
• the ratio of ethylenediamine to the co-diamines is in the range from 1.0: 0 to 0.8: 0.2.
• the ratio of the acid components to the amine equivalents is approximately equivalent, preferably the polyamides have amine and acid numbers in the sum of ⁇ 10.
• the polyamide resins used according to the invention can be ground to a powder even at normal temperature, which, even under application conditions, does not block without further additives and remains free-flowing. Therefore, precise and sharply delimited zones can be achieved even with very small or detailed printed images.
• the grain size of the powder can be varied as required and is between 50-250 microns, preferably between 80-160 microns.
• the melting point of the resins is adapted to practical requirements. It is so low that the melting temperatures do not adversely affect substrates or the base lacquer, but on the other hand it is so high that there is no blocking even at application temperatures.
• the melting range (measured according to the ring and ball method) is between 95 - 125 C, preferably between 110 - 120 C.
• the resins have a narrow melting range, so that rapid freedom from sticking and blocking is achieved in the cooling stage which follows the melting phase. This is of considerable interest for achieving fast cycle times.
• the polyamides according to the invention are well compatible with the customary background paints present, so that at the melting temperatures, which can be up to 100 ° C. above the melting point of the polyamide, a good flow of the melt and thus a perfect surface after solidification is ensured.
• the melt viscosities which were measured uniformly at 160 ° C. using a rotary viscometer with a plate / cone device from Haake according to the device manufacturer, are in the range from approximately 0.1 to 0.5 Pa.s, preferably 0.2 up to 0.3 Pa. s.
• the coating resists all usual loads, such as B. Rolling up or kinking without flaking or cracking in relief.
• the further improved flow properties of the molten resins lead to a smooth, shiny and crater-free surface and make the polyamides used according to the invention particularly suitable for use as relief prints.
• customary leveling agents based on silicone or acrylate can also be used.
• the amounts are between about 0.1 to 1.0, preferably 0.2 to 0.3% by weight, based on the total amount of fatty acids.
• Antioxidants and optical brighteners can also be used in the usual amounts.
• the resins used according to the invention can be prepared by the known processes by melt condensation at temperatures between 180-230 ° C., preferably 200-210 ° C., optionally with the use of conventional catalysts such as phosphoric acid, phosphorous acid and hypophosphorous acid, in amounts of up to 0.5% by weight. -%, based on fatty acids.
• 150 g of dimerized, distilled, hydrogenated fatty acid (B) 0.375 equiv. Were placed under nitrogen in a 1 l three-necked flask equipped with a stirrer, thermometer and descending condenser; 150 g dimerized, distilled fatty acid (A) 0.375 equiv .; 50 g isostearic acid (E) 0.125 equiv .; 50 g oleic acid (D) 0.125 equiv .; 42.3 g ethylenediamine (F) 1.0 equiv .; 1 g of hypophosphorous acid (50%) (0.25% by weight based on A, B, D, E), mixed together as a catalyst and heated to 200 ° C. in 2 hours.
• hypophosphorous acid 50%) (0.25% by weight based on A, B, D, E), mixed together as a catalyst and heated to 200 ° C. in 2 hours.
• thermoplastic polyamide obtained had a ring and ball softening point (DIN 52011) of 113 ° C, a viscosity of 0.28 pa's at 160 ° C (measured on the PK 401 W rotary viscometer from Haake (Karlsruhe) according to their instructions), an acid number of 4.3 and an amine number of 1.2.
• the polyamide resin according to the invention according to Example 1 was ground in a laboratory mill and a grain fraction of 160-80 micrometers was sieved out using a sieve set.
• a blue pigmented, highly viscous offset ink manufactured by Hostmann Steinberg, type N 466009
• the cardboard prepared in this way was then placed in a convexograph (Grafra company) and irradiated from above with IR radiators from a distance of approximately 30 cm. After a residence time of 3-5 seconds, the powder melted and ran into a smooth, closed, glossy film which solidified immediately after removal from the heating zone. Since the polyamide resin has practically no intrinsic color, no change in the blue tone of the printing ink was observed. The polyamide film also had sharp boundaries that corresponded exactly to the printed image.
• Heating power 1950 watts.

Landscapes

• Polyamides (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Duplication Or Marking (AREA)
• Printing Methods (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6411770

Family Applications (1)

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Cited By (5)

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Citations (4)

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• 1990
  • 1990-08-07 DE DE4024981A patent/DE4024981A1/de not_active Withdrawn
• 1991
  • 1991-07-02 EP EP19910110922 patent/EP0470364A3/de not_active Withdrawn
  • 1991-07-09 US US07/727,545 patent/US5214124A/en not_active Expired - Fee Related
  • 1991-08-01 JP JP3192837A patent/JPH04261890A/ja active Pending
  • 1991-08-07 CA CA002048589A patent/CA2048589A1/fr not_active Abandoned

Patent Citations (4)

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