Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/124—Duplicating or marking methods; Sheet materials for use therein using pressure to make a masked colour visible, e.g. to make a coloured support visible, to create an opaque or transparent pattern, or to form colour by uniting colour-forming components
  • B41M5/1243—Inert particulate additives, e.g. protective stilt materials

Definitions

• This invention relates to a pressure-sensitive copying paper, particularly, a pressure-sensitive copying paper free from smudge.
• Pressure-sensitive copying papers consist basically of (a) an upper sheet obtained by coating one side of a substrate such as a paper with microcapsules containing an oil type solution containing an electron- donating, colorless dye as a color former and drying the coated substrate, (b) a lower sheet obtained by coating one side of a substrate with a coating fluid containing an electron-accepting, solid acid (a color developer) and an adhesive and drying the coated substrate, and optionally (c) an intermediate sheet obtained by coating one side of a substrate with said microcapsules and the other side of the substrate with said electron-accepting, solid acid and said adhesive and drying the coated substrate (such pressure sensitive copying papers being referred to as separating type pressure sensitive paper).
• separating type pressure sensitive paper There are also self-contained type pressure-sensitive copying papers wherein a substrate is coated at same one side with color former-containing microcapsules and a color developer.
• smudging a phenomenon having a particle diameter larger than that of the microcapsules is used together with the microcapsules as a capsule- protecting agent (hereinunder referred to as a "stilt").
• a capsule- protecting agent hereinunder referred to as a "stilt"
• the stilt there are generally used cellulose fine powders, starch grains, beads of various plastics, etc.
• starch grains show a fairly good effect in smudge prevention.
• starches have a specific gravity of 1.6 which is considerably larger than that (about 1) of microcapsules and moreover there are used starches having particle diameters ordinarily of 20 to 30 u
• starch grains cause precipitation, whereby the coating fluid causes compositional change during a continuous, long term coating operation and there occurs quality deterioration of sheets due to color development, smudging, etc. of microcapsules-coated sheet surfaces.
• the particle diameters and hardnesses of starch grains reduce the color developability between a color former and a color developer at a low writing pressure, whereby color development becomes insufficient in copying of a large number of sheets.
• cellulose fine powders are obtained by grinding a wood pulp mechanically or chemically, and their particle sizes are broad with a medium size being about 30 p in width and about 100 p in length and their specific gravities are about 1.
• a coating fluid as a stilt, because its specific gravity is about same as the specific gravity of microcapsules, there is no anxiety for the cellose fine powders to precipitate. Therefore, there is no compositional change of the coating fluid even in long term coating and accordingly there occurs no quality deterioration of coated sheets and the color developability at a low writing pressure is good.
• the present inventors made an extensive study on further improvement of the smudge preventability of a coating containing microcapsules and cellulose fine powder fluid free from precipitation and excellent in color developability at a low writing pressure. As a result, it was found that combined use of (a) a cellulose fine powder as a stilt and (b) a fatty acid amide as a lubricant in a coating fluid shows an outstanding smudge prevention effect without sacrifying the merits of an original coating fluid. Based on this finding, the present invention has been attained.
• the fatty acid amide gives little effect for improvement of smudge prevention.
• the fatty acid amide is used in a coating fluid containing microcapsules and starch grains or plastic beads as a stilt, the fatty acid amide gives little effect for improvement of smudge prevention but, when the fatty acid amide is used in a coating fluid containing microcapsules and a cellulose fine powder as a stilt, the fatty acid amide does show an outstanding effect.
• the fatty acid amide as a lubricant when used in a coating fluid containing microcapsules and a cellulose fine powder as a stilt, the fatty acid amide is located close to the surface of a coated layer due to the affinity of the amide with the coated layer when the coating fluid is coated at a high speed by a coater or the like and dried rapidly or due to the migration of the amide and thereby the fatty acid amide can function well as a lubricant.
• fatty acid amide used as a lubricant in the present invention there can be mentioned fatty acid amides such as stearamide, ethylenebisstearamide and the like. In combination with these fatty acid amides there may be used other lubricants such as aliphatic hydrocarbons (a paraffin, a polyethylene and the like), higher fatty acids derived from tallow, coconut oil and the like, higher aliphatic alcohols, metal soaps (calcium stearate, zinc stearate and the like), and higher fatty acid esters.
• aliphatic hydrocarbons a paraffin, a polyethylene and the like
• higher fatty acids derived from tallow coconut oil and the like
• metal soaps calcium stearate, zinc stearate and the like
• the amounts of the cellulose fine powder (stilt) and the fatty acid amide (lubricant) used in the present invention 5 to 70 parts by weight (hereinunder referred to simply as parts) of the cellulose fine powder is preferable relative to 100 parts of microcapsules.
• the fatty acid amide is used in an amount of 0.9 part or less, the effect is low.
• it is used in an amount of 16 parts or more color developability is badly affected. Therefore, 1 to 15 parts of the fatty acid amide is preferable. 15 to 60 parts of the cellulose fine powder and 2 to 10 parts of the fatty acid amide are more preferable.
• the microcapsules can be produced, for example, by the following methods.
• the colorless dye which is a color former there can be used known leuco dyes for pressure-sensitive recording, such as, for example, a triphenylmethane compound, a diphenylmethane compound, a xanthene compound, a thiazine compound and a spiropyran compound.
• color formers are dissolved or dispersed in an appropriate oily solvent, emulsified into minute droplets in water or in a hydrophilic solvent and then microencapsulated by one of the above mentioned encapsulation methods.
• oily solvent there are used nonvolatile solvents such as alkylnaphthalenes, diaryl- ethanes, alkylbiphenyls, hydrogenated terphenyls and esters.
• the electron-accepting substance which is a color developer and forms a color by contacting with the above mentioned color former
• inorganic color developers e.g. acid clay, active clay, attapulgite, zeolite
• phenols phenol-aldehyde polymers
• phenol- acetylene polymers phenol- acetylene polymers
• maleic acid-modified rosin aromatic carboxylic acids (e.g. salicylic acid or its derivatives) and their metal salts, etc.
• a coating fluid is coated on a substrate at a high speed by the use of a coater having a coater head such as an air knife, a blade roll, a bar or the like.
• the present invention will be described more specifically by means of Examples.
• the pressure-sensitive copying paper of the present invention is not restricted to a separating type mentioned in Examples but does also include a self-contained type.
• aqueous solution containing 10% of an ethylene-maleic anhydride copolymer, 10 parts of urea, 1 part of resorcin and 200 parts of water were mixed and made into a solution.
• the solution was adjusted to a pH of 3.5 by the use of a 20% aqueous sodium hydroxide solution.
• a dye solution obtained by dissolving 10 parts of Crystal Violet Lactone in 90 parts of diisopropylnaphthalene was dispersed in the above aqueous solution to prepare an oil-in-water type emulsion having oil droplets of 3 to 5 u in diameter. Thereto was added 25 parts of a 37% aqueous formaldehyde solution. The system was kept at 55°C with stirring.
• a coating fluid having a total solid content of 20% was prepared by mixing the following materials.
• This fluid was coated on a plain paper of 40 g/m 2 by the use of an air knife coater at a speed of 100 m/min so that the coated amount became 5 g/m 2 , and the coated paper was dried to obtain a color former sheet.
• a color developer sheet there was used a pressure-sensitive copying paper (Mitsubishi NCR paper CF) wherein a substrate was coated at one side with a solid acid as an electron-accepting substance (oil-soluble phenol resin of novolac type). These sheets were superimposed so that their coated sides faced with each other. Then, color development characteristic and smude-preventing characteristic were examined. The results are shown in Table 1.
• Crystal Violet Lactone 2 Parts was dissolved in 100 parts of Hisol SAS-295 (diarylethane type solvent, manufactured by Nippon Petrochemicals Co., Ltd.). This solution was subjected to dispersion and emulsification. Encapsulation was conducted by a coacervation method using gelatin-gum arabic. The microcapsule dispersion had a microcapsule content of 20% and the microcapsules had an average particle diameter of 10 u.
• a coating fluid having a total solid content of 20% was prepared by mixing the following materials.
• Example 1 The same procedure as in Example 1 was conducted except that ethylenebisstearamide used in Example 1 was not added. The results are shown in Table 1.
• Example 1 The same procedure as in Example 1 was conducted except that KC Flock used in Example 1 was replaced by wheat starch. The results are shown in Table 1.
• color development (T.I.) is given as a concentration of a color developed by a typewriter and smudging (F.S.) is an index indicating the staining of a coating layer due to friction. They are given by the following formula.
• ⁇ , ⁇ and X are results by visual evaluation.

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• Color Printing (AREA)

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• 1983
  • 1983-04-04 JP JP58059059A patent/JPS59184695A/ja active Pending
• 1984
  • 1984-04-03 WO PCT/JP1984/000160 patent/WO1984003860A1/ja active IP Right Grant
  • 1984-04-03 EP EP84901410A patent/EP0141856B1/de not_active Expired
  • 1984-04-03 DE DE8484901410T patent/DE3472930D1/de not_active Expired
  • 1984-04-03 AU AU28102/84A patent/AU565566B2/en not_active Ceased

Patent Citations (4)

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