DE3802271A1 - MICROCAPSULES CONTAINING COLOR IMAGE - Google Patents

Description

The manufacture and use of chemical containing microcapsules Copy systems are known. Such systems with paper as Carrier material is manufactured on a large scale using technology. As Core liquids contain the microcapsules of the prior art high-boiling, usually aromatic liquids or polychlorinated Alkanes. To reduce the cost, aliphatics are often added to the aromatics, the aromatic liquid serves as a solvent for the Color formers. Aliphates alone are not suitable as they are suitable for the Prior art color formers none for use in Copy systems have sufficient solvency.

It is also known that the known color formers dissolve well in lower alcohols. Because of the water solubility of the lower alcohols , such solutions cannot be enclosed in microcapsules by the known processes.

The object of the invention was to provide more than core liquid for microcapsules to provide suitable liquids.

The invention relates to microcapsules containing color formers, which are characterized in that, as the core material, they contain a solution of the color formers in at least one C ₈ -C ₁₄ -alkanol (core liquid) which is liquid at room temperature.

The alkanols to be used according to the invention have in comparison to the Core solvents of the prior art have clear advantages in the Solution properties. The alkanols allow the production of stable ones Solutions of color formers which are otherwise critical in solubility, so that improved mixtures can be produced for the encapsulation.

The alkanols to be used according to the invention solve the known ones Color formers quickly at temperatures up to 95 ° C and give after cooling stable solutions from which the color formers do not crystallize. With carbonless systems made from these microcapsules deliver vivid, clear copies.

C ₈ to C ₁₄ alkanols which are liquid at room temperature or mixtures of these alkanols are suitable as the core liquid. The boiling point should be <180 ° C. The alkanols generally have primary hydroxyl groups. The alkyl radical of the alkanols can be linear or branched.

The preferred alkanols are those obtained by hydrogenation of oxo reaction products of Δ -1-C ₇ - to C ₁₃ -olefins.

The alkanols can be used alone or as a mixture with those as the core liquid known organic liquids e.g. aromatic hydrocarbon substances from the group of alkylnaphthalenes, terphenyls and / or Alkylbenzenes and polychlorinated paraffins can be used.

Known color formers come into consideration, e.g. those from the Group of the lactones, such as crystal violet lactone, the fluoranes such Fluoranlactones, rhodamine lactones, diazarhodamine lactones, phthalides, Spirodipyrans such as dibenzodipyrans or mixtures of these compounds in Consider. With regard to the color formers, reference is made to the following literature pointed out:

DE-A 16 71 545, 20 24 859, 21 30 845, 21 30 846, 21 55 987, 24 22 899, 22 43 483, 23 23 803, 24 24 935, 22 62 127, 22 02 315, 21 22 997, 22 02 315, 21 55 997, 24 30 568, 25 09 793, 26 11 600, 31 14 968 and 33 37 387, JP-OS 273/1977; GB-A-20 97 013 and EP-A-10 740.

The alkanols, their mixtures with the known core liquids, which the Color formers can be dissolved in known processes in Microcapsules are included, e.g. according to the procedure of EP-B 26 914, EP-A 82 635, EP-A 1 33 295 and US-A 28 00 457.

As wall materials e.g. Hydroxypropyl cellulose, Carboxymethyl cellulose, gelatin, gum arabic and melamine formaldehyde Pre-condensation products into consideration.

The invention is illustrated by the following examples. The parts specified below are parts by weight.

example 1

a) 5.5 parts of color former mixture of 0.5 parts of crystal violet lactone, 0.8 parts of N-benzoyl leukomethylene blue, 0.5 parts of color former DE-A-23 23 803, Example 1, 1.25 parts of color former DE-A-22 27 597, Example 2, 0.5 part color former of DE-A-22 43 483, Example 5 and 2.0 parts of color formers from DE-A 24 22 899, Example 2, are dissolved in 94.5 parts of isotridecanol at 95 ° C. Doing so Obtain clear solution, even after cooling to room temperature (20 ° C) remains clear.  

The isotridecanol used is a mixture obtained by oxo reaction of the olefin obtainable from butene-1 and butene-2 and hydrogenation of the reaction product formed in the oxo reaction was obtained.

b) 380 parts of the solution obtained according to a) (core liquid) are stirred with a dissolver ( n = 2000 rpm) in 80 parts of a 20% aqueous solution of poly-2-acrylamido-2-methylpropanesulfonic acid / sodium salt and 62 parts of a melamine-formaldehyde precondenser (from 1 mol of melamine and 5.25 mol of formaldehyde and 560 parts of water) emulsified at 28-29 ° C. Then the number of revolutions of the dissolver disc is increased to 6000 rpm and adjusted to pH 3.6 with 10% formic acid.

After about 30 minutes the formation of Microcapsules are observed. The dispersion is still 0.5 hours stirred further, then stirred at 60 rpm for 1 hour at 60. After that increase the temperature to 75 ° C and stir at 500 rpm for 2 hours to. After cooling, the dispersion is adjusted to pH 7 with triethanolamine set.

The finished microcapsule dispersion contains after particle size measurement in the Coulter-Counter TF microcapsules with an average diameter of 5-6 µm. The solids content is about 40%.

c) Checking the carbon copy properties:
32 parts of the microcapsule dispersion obtained according to b) are mixed in by slow stirring
5.1 parts of cellulose flour (Arbocel 600/50 from Rettenmayer, Holzmühle, Germany),
5.1 parts of acrylic ester copolymer (50% dispersion in water) and
57.8 parts of water mixed.

This coating color was applied with a 30 μm spiral doctor blade on coating base paper of 50 g / m ² ); Application weight atro 8 g / m ² .

The donor sheet (CB) obtained was together with CF sheets (activated clay) (CB) in a typewriter (Olympia, Standard 200).

The intensity of the copy is determined on the third copy.  

For this purpose, the carbon copy set on an area of approx. 5 × 5 cm with small letters next to and on top of each other described.

The reflectance of the blank papers was measured at 88% and that of the 3rd copy with 37%. I.e. the copy shows one Intensity of 51% and thus corresponds to the intensity of Copies obtained with microcapsules that Color former solutions in diisopropylnaphthalene and aliphatic Contain hydrocarbons.

Example 2

5.55 g are added to 47.5 parts of isotridecanol mixture and 47 parts of isodecanol of the color former mixture given in Example 1 dissolved at 95 ° C. The The clear solution obtained remains clear even after cooling to 20.degree.

The isotridecanol mixture was made from tetramer propylene by oxosynthesis and Get hydrogenation of the oxo product.

The solution obtained was in microcapsules according to Example 1b) encapsulated.

Deliver recording papers made with the microcapsules obtained easy to read copies.

Example 3

In 75.0 parts of the isotridecanol mixture used in Example 1 and 19.5 parts of di-isopropylnaphthalene (KMC 113 of the trade) becomes 5.5 parts of the color former mixture given in Example 1 dissolved at 95 ° C. The Solution remains clear even after cooling. This solution was developed after the in Example 1 b) encapsulated process. The one with these Microcapsules coated CB papers are easy to read with CF papers Copies.

Claims (4)

1. Microcapsules containing color formers, characterized in that they contain, as the core material, a solution of the color formers in at least one C ₈ - to C ₁₄ -alkanol (core liquid) which is liquid at room temperature. 2. Microcapsules containing color formers according to claim 1, characterized in that the core liquid is a mixture of C ₈ - to C ₁₄ alkanols and the aromatic hydrocarbons and / or polychloroparaffins known as solvents. 3. microcapsules containing color formers according to claim 1 or 2, characterized in that the core liquid to 10 to 100 wt.%, Based on the core liquid, consists of C ₈ - to C ₁₄ alkanols. 4. microcapsules containing color formers according to claim 1, 2 or 3, characterized in that isotridecanol is used as the alkanol.