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 novel construction of a pressure sensitive record paper. More particularly, it relates to an improvement in a self-contained color forming pressure sensitive record paper comprising a base sheet coated with single record layer of a mixture of color former-containing microcapsules and color developer-containing microcapsules.
• An ordinary so-called pressure sensitive paper system is composed of a so-called top sheet comprising a support material coated thereon with a layer of capsules containing a color former such as crystal violet lactone or benzoyl leuco methylene blue and an undersheet comprising a base sheet coated with a layer of an activated clay or an organic acidic substance such as acid clay, activated clay, a phenolic resin, or an aromatic carboxylic acid compound.
• a so-called top sheet comprising a support material coated thereon with a layer of capsules containing a color former such as crystal violet lactone or benzoyl leuco methylene blue
• an undersheet comprising a base sheet coated with a layer of an activated clay or an organic acidic substance such as acid clay, activated clay, a phenolic resin, or an aromatic carboxylic acid compound.
• Such a record paper is composed of two layers of different composition coated one upon another on one and the same base sheet, the undercoating layer generally comprising microcapsules containing a color former dissolved in an oily liquid and the overcoating comprising dispersed color developer which develops color upon contact with the color former.
• the capsules in the area where the marking pressure has been applied are ruptured to release the oily liquid containing the color former which produces colored image upon contact with the color developer.
• Such a type of pressure sensitive record paper is usually called self-color developing pressure sensitive record paper or self-contained record paper. This invention is to provide a novel construction of an advanced self-contained record paper.
• the conventional self-contained record paper is manufactured by a two-step process comprising a step of providing an undercoating of microcapsules and another step of providing an overcoating of color developer; consequently, the productivity including operation efficiency and product yield is greatly diminished.
• the conventional method requires increased expenses for the process control in order to avoid unintentional folding or creasing of paper which are apt to occur and to avoid unintentionally applied slight pressure during manufacture, which causes smudging due to color development.
• the present inventors were engaged in developing methods for manufacturing in one step a self-contained color developing pressure sensitive record paper and have provided a number of novel techniques.
• the present inventors propose a new construction for obtaining a single coating-type self-contained color developing pressure sensitive paper of higher quality, which is characterized by being incorporated in the coating layer with a capsule-protective agent to keep the capsules from unintentional rupture.
• the present inventors utilized, heretofore, chiefly starch particles as a capsule-protective agent for the single coating-type self-contained color developing record paper.
• starch in order to achieve satisfactorily the object of capsule protection, it was necessary to add starch in an amount as large as 150 parts by weight or more for 100 parts by weight of capsules at the inevitable sacrifice of the important color developing performance of the record paper.
• starch is added in an amount sufficient for protecting the record paper from smudging due to unintentional color development, some reduction in the intensity of developed color is resulted at the same time.
• the present invention as claimed is intended to remove such drawbacks of the previous technique.
• a powdered polyolefin is used in place of starch.
• a powdered polyolefin is incorporated in place of starch, there is obtained an enormous result that while the protective effect against smudging is sufficiently exhibited, the image color developing ability remained at a high level. This result has led the present inventors to the accomplishment of this invention.
• Another important feature of the present record paper is a marked reduction in the smudging due to unintentional folding of the record paper.
• a conventional self-contained color developing pressure sensitive paper whether a multi-coating type or a single-coating type, is subject to smudging due to color development along the crease line, whereas the single-coating type record paper according to this invention is more resistant to such smudging and is of better practical use, compared with starch-containing one. The reason for this cannot be explained, but the fact remains evident.
• the powdered polyolefin can be used.jointly with starch particles without much losing the advantage of the former.
• the processes for producing microcapsules suitable for use in the method of this invention include:
• Suitable color formers are known leuco dyes for pressure sensitive recording such as, for example, triphenylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds and spiropyrane compounds. These color formers are dissolved or dispersed in a suitable oily solvent, or emulsified to minute droplets in water or a lyophilic solvent and are then microencapsulated by a suitable method.
• Suitable oily solvents are selected from nonvolatile solvents such as alkylnaphalenes, diarylethanes, alkylbiphenyls, hydrogenated terphenyls, and esters.
• microcapsules containing color developers are those having capsule walls substantially made of a urea-formaldehyde resin, the intenral phase being acidic organic substances dissolved in or swollen with an oily solvent.
• the methods of microencapsulation using a urea-formaldehyde resin as wall material have been described in Japanese Patent Application Liad-open 9,079/76; Japanese Patent Publications 30,282/71 and 23,165/72.
• Suitable oily solvents for dissolving or swelling the color developers are selected from toluene, xylene, alkylnaphthalenes, diarylethanes, alkylbiphenyls, and esters.
• Desirable color developers among acidic organic compounds are various oil-soluble phenolic resins and oil-soluble aromatic carboxylic acid compounds.'
• Suitable polyolefins include homopolymers of olefins such as, for example, ethylene, propylene and styrene, copolymers of two or more olefins, and blends of these polymers.
• An aqueous suspension of powdered polyolefins can be prepared by modifying a polyolefin resin with an unsaturated carboxylic acid such as, for example, maleic anhydride, melting the modified resin together with, if necessary, a surface active agent, and dispersing in hot water (Japanese Patent Application Liad-open 36,540/75) or by heating a mixture of a polyolefin, organic solvent, nonionic surface active agent and water at a temperature above the melting point of said polyolefin, then cooling the heated mixture to a temperature below the melting point of said polyolefin to obtain an emulsion which is then freed from the organic solvent (Japanese Patent Application Liad-open, 138,735
• powdered polyolefins having a particle diameter of 5 to 30 ⁇ and in spherical form, which are suitable as a microcapsule-protective agent according to this invention.
• a desirable result is obtained by adding to the coating composition a powdered polyolefin in the form of an aqueous dispersion as such.
• the particle diameter of the powdered polyolefin is preferably 10 to 30 p.
• the softening point should be higher than the maximum temperature of the paper material during application of the pressure sensitive record coating and is preferably 70°C or higher.
• the amount to be added of the powdered polyolefin is preferably 50 to 250%, most preferably 100 to 200% based on weight of capsules to obtain a single coating-type self-contained pressure sensitive record paper in which the capsules are properly protected against unintentionally applied pressure and which shows satisfactory density of the impressed image.
• the amount of the powdered polyolefin may be replaced by an appropriate amount of starch at the sacrifice of the reduction effect of the smudging due to folding of the record paper.
• the practical amount to be replaced is at most 70% thereof.
• plastic pigments in the self-contained pressure sensitive record paper (Patent Application 134,732/77; title: self-contained color developing pressure sensitive record paper).
• the plastic pigments are generally finely divided particles, 1.0 p or less in diameter, and has no capsule-protective ability against unintentional application of pressure.
• Plastic pigments are easily distinguishable from the powdered polyolefin (about 20 p in diameter and has an excellent capsule-protective ability against unintentionally applied pressure) for use according to this invention, and are used for the purpose entirely different from that of this invention.
• a single coating-type self-contained color-developing pressure sensitive record paper is prepared by mixing together an aqueous dispersion of a powdered polyolefin, microcapsules containing a color fomrer, microcapsules containing a color developer, and, if necessary, a water-soluble amino resin such as a cation-modified urea resin or a cation-modified polyamide-epichlorohydrin resin; adding to the resulting mixture a binder such as polyvinyl alcohol, latex, hydroxyethylcellulose or oxidized starch, a clay such as kaolin clay, montmorillonite clay or talc, and other customary additives to obtain a coating composition; then applying to the base paper said coating composition by means of an air knife coater, blade coater, roll coater, bar coater or other coating machines.
• a binder such as polyvinyl alcohol, latex, hydroxyethylcellulose or oxidized starch, a clay such
• this invention is very useful for the manufacture of single coating-type self-contained color developing pressure sensitive record papers.
• TI is the intensity of image color developed by the impression with a typewriter
• FS is the smudge caused by friction TI and FS were calculated from the following formula:
• a larger value of TI or FS indicates a lower intensity of image color or a lighter smudge.
• the color development by creasing was evaluated from the reflection density measured by means of a microdensitometer on the area where smudge has been developed by creasing. A smaller value indicates a lighter smudge.

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• 1978
  • 1978-06-26 JP JP7726478A patent/JPS553969A/ja active Pending
• 1979
  • 1979-06-25 EP EP79102082A patent/EP0006599B1/en not_active Expired
  • 1979-11-22 AU AU53089/79A patent/AU518408B2/en not_active Ceased
  • 1979-11-26 NL NL7908566A patent/NL7908566A/nl not_active Application Discontinuation
  • 1979-11-28 CH CH1056779A patent/CH641093A5/de not_active IP Right Cessation

Patent Citations (6)

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