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
  • B41M5/132—Chemical colour-forming components; Additives or binders therefor
  • B41M5/155—Colour-developing components, e.g. acidic compounds; Additives or binders therefor; Layers containing such colour-developing components, additives or binders
• • 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
  • B41M5/132—Chemical colour-forming components; Additives or binders therefor
  • B41M5/136—Organic colour formers, e.g. leuco dyes
  • B41M5/145—Organic colour formers, e.g. leuco dyes with a lactone or lactam ring
  • B41M5/1455—Organic colour formers, e.g. leuco dyes with a lactone or lactam ring characterised by fluoran compounds

Definitions

• the invention relates to pressure-sensitive recording sheets, in particular a color developing sheet for pressure-sensitive recording sheets, which gives a recording image with increased image density and superior light fastness.
• the pressure-sensitive recording sheets consist of an upper sheet (CB-coated underside) and a lower sheet (CF-coated upper side).
• the underside of the upper sheet is coated with microcapsules which contain an electron-donating, colorless or slightly colored chromogenic dye which is dissolved in an organic solvent (capsule oil).
• the surface of the lower sheet is coated with a color development layer containing an electron-accepting color development agent. If the surface coated with microcapsules is placed on the surface coated with a color development layer and a localized print, e.g. B. by a ballpoint pen, a typewriter, etc., on the pressure-sensitive recording sheets, the microcapsules break under the applied pressure, and the capsule oil containing the chromogenic dye gets into the layer containing the color developing agent. The chromogenic dye reacts with the color developing agent to form an image in the desired recording pattern.
• a localized print e.g. B. by a ballpoint pen, a typewriter, etc.
• the surface of the middle sheet (CFB-coated top and bottom) is coated with a layer comprising a color developing agent, and the bottom of the middle sheet is coated with microcapsules containing the chromogenic dye. If you put one or more CFB sheets between the CB and CF sheets, you can get one or more copies.
• the activated clay is produced by treating the acidic clay or the like with a mineral acid for the purpose of dissolving aluminum, iron and other basic components and thereby increasing its specific surface area - A specific surface area of over 200 m 2 / g a preferred color development effect.
• Activated clay has the advantage that it is much cheaper than known organic color developing agents.
• the color for the image of the pressure-sensitive recording sheets was only blue because crystal violet lactone (CVL), benzoyl leuco methylene blue (BLMB), etc. were used as color formers.
• CVL crystal violet lactone
• BLMB benzoyl leuco methylene blue
• the market has asked for pressure sensitive recording sheets which provide a black image.
• mixtures of two or more different dyes, which have several shades, have been proposed; see Japanese Patent Publications 4,698 / 1970,4 614/1971 etc.
• the black color developing dye can be combined by the combination of blue and yellow-orange dye, blue and yellow and yellow-orange and red dye, three basic dyes such as blue-green-red dyes, etc., or two dyes combined with each other Form counter colors, be produced.
• fluoran dyes which themselves form a black color have been developed.
• dyes of this type are 3 diethylamino 6-methyl) 7-anitinoftuoran, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (ortho, para-dimethylanilino) -fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, etc.
• fluoran dyes when used with inorganic color developing agents such as activated clay, have the disadvantages that they give a reddish-black or greenish-black image, the resulting image undergoes hue change or fading, becoming reddish brown, and that an image with a persistent Hue cannot be obtained.
• the invention has for its object to provide pressure-sensitive recording sheets in which a pure black colored image with increased image density, superior light fastness and little change in color tone can be achieved with a color development sheet, a transfer sheet and a black-forming fluoran dye.
• a transfer sheet which has a coating which consists of microcapsules which contain a colorless or slightly colored fluoran dye of the formula (I) which develops a black color
• a color development sheet which has a color development layer which contains at least activated clay, zinc carbonate and a thiourea compound.
• dyes are dissolved in an organic solvent and by preservation processes (see, for example, US Pat. No. 2,800,457), interfacial polymerization processes (see, for example, Japanese Patent Publication 19 578/1963), "in-situ” polymerization processes (see, for example, Japanese Patent publication 45 133/1974) and the like encapsulated. They are then applied to a support to make a transfer sheet.
• the color development sheet according to the invention which is used in combination with the above transfer sheet, consists of a support and a color development layer lying on the support, which contains activated clay, zinc carbonate and a thiourea compound.
• the use of zinc carbonate and thiourea compound in addition to activated clay in the color development layer in conjunction with the fluoran dyes used according to the invention leads to a purely black colored image with an increased image density and improved light fastness and less change in color.
• the addition of thiourea compound leads to a purely black color, improved light fastness and less color change.
• thiourea compounds according to the invention are thiourea, trimethylthiourea, diethylthiourea, dibutylthiourea, dilaurylthiourea, ethylene thiourea, diphenylthiourea and the like.
• thiourea compounds trimethylthiourea, diethylthiourea, dibutylthiourea and diphenylthiourea are preferred according to the invention.
• the addition of zinc carbonate leads to increased image density, superior light fastness and improved color tone.
• the zinc carbonate of the present invention includes zinc carbonate and basic zinc carbonate, which are available on the market.
• the addition of zinc oxide results in a lower image density and inferior light fastness and the image becomes reddish when exposed to sunlight or ultraviolet.
• binders in the color development layer are natural or synthetic polymers such as starch, carboxymethyl cellulose, methyl cellulose, gelatin, gum arabic, polyvinyl alcohol, casein, styrene-butadiene copolymer latices and the like.
• inorganic pigments are natural or synthetic inorganic pigments such as clay, talc, kaolin, calcium carbonate, basic magnesium carbonate, barium sulfate, barium carbonate, aluminum hydroxide, zinc white and the like.
• the color development sheet of the present invention it is advantageous to use 3 to 20 parts by weight of zinc carbonate, 1 to 30 parts by weight of the thiourea compound per 100 parts by weight of the activated clay and 10 to 40 parts by weight of the binder based on 100 parts by weight. Parts total solids content to use.
• color development layer it is also advantageous to apply the color development layer to a support in a coating coloring amount of 3-10 g / m 2 .
• a solution of 20 parts by weight of gum arabic in 160 parts by weight of water was added to the dispersion, and 550 parts by weight of water were added with further stirring. Then, a 10% aqueous acetic acid solution was added to adjust the pH of the solution to 4.4 while the complex preservation was carried out. All of the above processes were carried out at a solution temperature of over 50 ° C.
• the coating color obtained was applied to a base paper having a weight of 40.g / m 2 in a coating amount of 7 g / m 2 , thereby obtaining a color developing sheet.
• the transfer sheet of Example 1 was used as such.
• the color developing sheets were prepared in the same manner as in Example 1, using different thiourea compounds and zinc carbonate and varying the amounts.
• the transfer sheet of Example 1 was used.
• the color development sheets were prepared in the same manner as in Example 1, with the color development sheets containing the components described in Table I. Thiourea was immediately dissolved in the activated clay dispersion because thiourea is readily soluble in water.
• a transfer sheet and a color development sheet are placed on top of each other so that the coated surfaces of the sheets touch each other.
• the stacked sheets are written on with a typewriter so that a color forms.
• the reflectance of the sheet 24 hours after color development was measured using a Hunter reflectometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) using an amber filter.
• the color development rate is calculated from the reflectance 1 0 of the sheet before the color development and the reflectance 1 1 of the sheet 24 hours after the color development as follows:
• the hue of the color developing sheet on which an image has been formed according to the procedure described in (1) is evaluated with the naked eye 24 hours after the color development.
• the color developing sheet on which an image was formed according to the procedure described in (1) is irradiated with sunlight for 2 hours, after which the light fastness is evaluated.
• the color developing sheet on which an image was formed according to the method described in (1) is irradiated with sunlight for 2 hours, the change in hue is evaluated with the naked eye.
• Examples 1 to 8 give high image density, pure black color development with superior lightfastness and with improved color change.
• Comparative experiments 1 to 5 result in high image density, but lead to reddish-black coloring, result in inferior light fastness and / or change in color.
• Comparative experiments 6 to 11 show pure black color development or a slightly reddish black, but lead to lower image density.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Color Printing (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (5)

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• 1981
  • 1981-12-08 JP JP56196384A patent/JPS5898281A/ja active Granted
• 1982
  • 1982-11-19 US US06/442,966 patent/US4473832A/en not_active Expired - Lifetime
  • 1982-12-06 DE DE8282111278T patent/DE3263698D1/de not_active Expired
  • 1982-12-06 EP EP82111278A patent/EP0081228B1/de not_active Expired
  • 1982-12-06 AT AT82111278T patent/ATE13159T1/de not_active IP Right Cessation

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