CZ258296A3 - Micro-capsule with dispersion - Google Patents

Abstract

The microcapsules of a dispersion for producing pressure-sensitive printing papers contain as solvent 10 to 30 % by weight of a liquid paraffin oil at room temperature, 25 to 60 % by weight of a liquid vegetable oil at room temperature or 15 to 60 % by weight of a mixture of 5 to 30 % by weight of a liquid paraffin oil at room temperature and 10 to 55 % by weight of a liquid vegetable oil at room temperature, the balance consisting of a solid or semi-solid vegetable oil at room temperature. The solvent contained in the core of the capsules is liquid at room temperature and the capsule wall is made of polycarbamide.

Description

(57)

Dispersion microcapsules for the production of pressure-sensitive recording papers comprise a solvent consisting of 10 to 30 wt. % paraffin oil, liquid at room temperature or from 25 to 60 wt. % vegetable oil, liquid at room temperature or from 15 to 60 wt. % of a mixture consisting of 5 to 30 wt. % paraffin oil, liquid at room temperature and from 10 to 55 wt. vegetable oil liquid at room temperature, and the residue which is vegetable oil, solid or semi-solid at room temperature. The solvent is liquid at room temperature and the capsule wall material consists of polyurea.

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The present invention relates to a microcapsule dispersion for the production of pressure-sensitive recording papers, wherein the core solvent contained in the microcapsule comprises a dye semifinished product or a mixture of dye semifinished products and a vegetable oil that is solid or semi-solid at room temperature.

BACKGROUND OF THE INVENTION

Dispersions of nicocapsules of the aforementioned kind and its use have long been known. Essentially, two different types of capsule wall materials are used, namely water-soluble capsule wall materials, such as porcine skin gelatin, acacia and water insoluble, such as polyisocyanate as one of the ingredients used to make polyurea capsules. In addition, spacers, for example starch grains or cellulose fibers, and a suitable binder for fixing the microcapsules to the paper surface are also added to the micro-capsule dispersions.

A number of suggestions are known from the prior art relating to suitable solvents or oils and mixtures thereof for absorbing dye preform compounds. For simplicity, these microcapsule components are hereinafter referred to as core solvents.

From D3-A-22 51 350 diphenyl alkanes, alkyl substituted diphenyl alkanes, diphenyl alkenes and / or somewhat are known as core solvents for the semi-finished dyes.

-2alkylsubstituted diphenylalkenes. To dilute to 1 part of the core solvent of the invention disclosed herein, 3 parts of a diluent, including, but not limited to, paraffin oil, castor oil, hoof oil, olive oil, soybean oil, cottonseed oil, oil from coconut or rapeseed oil or organic solvents such as aromatic gasoline or alkenylbenzene. The diluent of these diluents is in the form of a solvent

they have to change the physical properties and the vapor pressure in order to achieve better manipulation or for those nological reasons.

PS-A-26 40 197 relates to a formulation for the release of coloring agents for pressure-sensitive copying systems in which the color acceptors consist of acidic resins. According to the present invention, a mixture of partially hydrogenated terphenyl and alkylbenzene components is used which is liquid at room temperature and which can be

Coconut fat, solid at room temperature.

In more recent development work, vegetable oils, animal oils and physiologically acceptable mineral oils have been used more and more.

EP-A-0 262 569 discloses as a core solvent a composition comprising at least 80% by weight. from vegetable oil, animal oil, or para-3-ol oil using a triphenylmethane leuco dye semi-finished product and the microcapsule wall material is water soluble or water dispersible prior to microcapsule formation.

SP-A-0 520 639 also contemplates a core solvent which contains vegetable oil for the production of a pressure-sensitive microcapsule used for recording paper. A further component of this composition is the non-aromatic monocarboxylic acid ester component of a saturated or unsaturated linear or branched hydrocarbon chain having at least 3 carbon atoms in the chain.

In contrast, AP-A-0 573 210 proposes a core solvent which does not contain the ester component mentioned above, wherein the vegetable oil used as the core solvent has a softening temperature range of about 20-25 ° C and at least consists of the bulk of the vegetable oil being solid or semi-solid within this temperature range. but the proposal is not without deficiencies.

Although the polyisocyanate has been shown to be soluble or at least very dispersible at room temperature and solid or semi-solid vegetable oils as a component used in the manufacture of polymorphic capsules, the dissolution of this component in organic solvents can be omitted, which has hitherto 4 is necessary, for example in isopropylnaphthalene. However, experiments carried out by the inventors themselves have shown that, in a temperature range near room temperature, solid or semi-solid mixtures of core solvents can lead to production disturbances in the manufacture of urea capsules. These drawbacks do not occur in the production of microcapsules on a laboratory scale using stirrer containers, but can be immediately observed when a dispersing unit consisting essentially of a dispersing head, a condenser and a conduit connecting these elements is used in a continuous or discontinuous production operation. in which the resulting core solvent droplets are routed through conduits from the dispersing head to the cooler, and parts of the cooler sprayed with cooling water may solidify and, as a result, deposits of oil blends having a relatively wide range of softening temperatures. This has a negative effect on obtaining a perfect dispersion of microcapsules.

Based on the identified drawbacks, it is an object of the present invention to provide a microcapsule dispersion which, in view of the components of the core solvent used, allows a problem-free production of the capsules. Only oils of vegetative origin should be used at the same time. A further object is to provide a high-density microcapsule, and again to reach the polyurea as a well-proven capsule wall material.

-5-Summary of the invention

To solve this problem, he therefore proposes a dispersion of microcapsules for the production of pressure-sensitive recording paper in which the core solvent contained in the microcapsules comprises a dye semifinished product or a mixture of dye semifinished products and vegetable oil which is solid or semisolid at room temperature. The composition according to claim 1, wherein the core solvent consists of 10 to 30 wt. from paraffin oil, liquid at room temperature, the remainder being a solid or semi-solid vegetable oil at room temperature, or from > 25 to 60 wt. vegetable oil, liquid at room temperature, the remainder: is a vegetable oil, solid or semi-solid at room temperature or from 15 to 60 wt. from a mixture of 5 to 30 wt. % of paraffin oil, liquid at room temperature and from 10 to 55 wt. vegetable oil, liquid at room temperature, the remainder: being a vegetable oil, solid or semi-solid at room temperature; the core solvent is liquid at room temperature and the capsule wall material is polyurea.

The term "room temperature" used in the specification and claims means that the solvent solvent is above 20 ° C liquid. The term "liquid" is understood to be capable of flowing.

The term paraffin oil in the specification and claims of the present invention is to be understood as meaning the basic petroleum or basic paraffinic mineral oil products, for example, white oil and spindle oil, Chlorine paraffin, proposed several times as a core solvent, is not within the scope of the present invention. included.

A smaller amount of paraffin oil additive than liquid vegetable oil is sufficient to adjust the liquid state of the core solvent. If, according to a first embodiment, liquid paraffin oil is used as the sole additive to a core solvent, consisting, moreover, of vegetable oil which is solid or semi-solid, amounts of additives of at least 10% by weight, preferably not more than 20% by weight, are required. In a second embodiment using liquid vegetable oils, the minimum amount of additive is more than 25% by weight. and may be up to 60 wt. According to a third embodiment, mixtures of liquid paraffin oil with liquid vegetable oil and a solid or semi-solid vegetable oil are also possible and, on the other hand, amounts of paraffin oil of less than 10 wt. but to which a larger amount of liquid vegetable oil would then have to be added than would be necessary with liquid paraffin oil.

According to a preferred embodiment of the invention, the core solvent consists of 30 to 90 wt. vegetable oil, solid or semi-solid at room temperature, the remainder: is paraffin oil, liquid at room temperature. The preferred core solvent mixture, which consists only of vegetable oils, consists of 60 to 70% by weight. According to the invention, vegetable oils, solid or semi-solid at room temperature, are preferably used as coconut oil, palm oil and vegetable oil. palm kernel oil or mixtures thereof. As vegetable oils liquid at room temperature, rapeseed oil, sunflower oil, cottonseed oil, olive oil, corn oil, thistle oil or mixtures of these oils are preferred.

Further suitable is a mixture of dye preforms which contains 2-phenyl-4- (4-diethylaminophenyl) -4- (4-methoxyphenyl) -6-methyl-7-dimethylamino-4H-benzo-3,1-oxazine as coloring agent. The coloring agents are highly soluble in the core solvent mixtures according to the invention and, on the other hand, also guarantee a high microcapsule dispersion efficiency according to the invention.

According to the invention, it is furthermore provided that the core solvent contained in the microcapsules does not solidify at temperatures above 13 ° C.

Spacers, binders and spreading aids can be added to the microcapsule dispersion. These measures are not the same as the application of the microcapsule dispersion to a suitable base paper and the method of application used.

Examples of the invention

The following examples explain the invention, Examples 1 and 2

Production of microcapsule dispersion:

In a mixture consisting of 90 parts by weight of oil

% of paraffin oil (white oil 1 1020 from Parafluid) dissolve a mixture of semi-finished dyes consisting of 60 parts by weight of 2-phenyl-4/4-diethylaminophenyl / -4- (4-methoxy-phenyl) -6-methyl-7-dimethylamino -4H-benz, 3.1t oxazine (baymicror® SN 2601 from BAIER, see also EP-A-0 573 210), parts by weight, fluorine-based dye preform and 20 parts by weight. CVI to produce a dye concentration in the core solvent of 6 44 447 g of the coloring agent mixture produced was added 71 g of diisocyanate followed by 992 g of 1% polyvinyl alcohol solution (as emulsifier) in demineralized water. . In addition, the dispersing head of the dispersing unit connected to the cooling device via a line is filled and the dispersion is started.

After passing through the water-cooled cooling device, a portion of the liquid passes through the throttle orifice of the dispersing unit and is fed into a separate stirrer vessel while the other portion of the liquid is fed back into the dispersing head. A 5.4 ( ⁵³⁾ solution of diethylenetriamine (DET) in demineralized water was added to a separate stirrer vessel and the defoaming agent was dropped. A temperature of 25 ° C is set in the stirrer vessel. A capsule is formed having an average size of 5.1 .mu.m, a 3.6 $ capsule having a size of > 10 µm.

Using the same dye semifinished blend as above but with an oil blend having a white oil content of 20 parts by weight, a micro-capsule dispersion was produced under the same process conditions, with average grain sizes of 5.9 µm and average size 15.3 $ microcapsules / µm.

in either case of the core assembly.

At the end of the experiment, no case of solvent deposition was observed on the cooling microcapsule dispersion produced. cellulose fibers as spacers and 17 wt. - calculated as dry weight, based on the content of all solids of the coating color of the microcapsules - oxidized starch solution as binder. Then, the prepared microcapsule paint was coated using a wire skate coating device with a coating weight

5.5 g / m &lt; 2 &gt; on a conventional coating paper and dried. The manufactured CB-sheet was described in contact with a conventional CP-sheet. A well-readable transcript was created with improved light fastness. Further experiments have shown improved impermeability and high light stability of the capsule.

Examples 3 to 4 and comparative example:

The following examples serve as proof that

The core solvent mixtures according to the invention are comparable to the recording papers known in the prior art with respect to the stability of the capsules and / or the intensity of the font image with respect to the impermeability of the capsules and with respect to aging resistance.

The dye semifinished product mixture described in Examples 1 and 2 was used and the dye concentration was adjusted to 6% in the core solvents below. The production of the microcapsules was carried out as in Examples 1 and 2, and the microcapsules produced for the production of GPB-sheets were coated on a wood-free, mass-coated coating paper 42 g / m @ 2 which had on one side already been coated with a CP layer. consisted of acidic clays, on the side opposite the GP-layer, with a coating weight setting of 6 g / m. In addition to the microcapsules, the paint also contained ground cellulose as spacers with butadiene styrene latex as a binder. The coating of the microcapsule dispersion was carried out by roller roller.

Core solvent composition:

Comparative example:

100 $ coconut oil corresponding to EP-A-0 573 210 coconut oil type as in example 1

Example 3

0 coconut oils as in the equilibrium example <$> white oil, as in example 1 'VSI *' * · -

-11Example 4% coconut oil as in the straightening example% white oil as in example 1

Roller test:

This test is used to test the stability of the capsules under different pressures.

A Burner thrust testing device was used. The 24 x 4.5 test strips of the CPB sheets produced were combined with another OP sheet so that the CB side was adjacent to the CP side.

The samples were subjected to 3 defined pressures between the aluminum cylinder and the rubber fabric support.

The decrease in CP-sheet clarity was measured. The results of the experiment are shown in the following table

Test result: roller test pressure comparative example Example 3 Example 4

196.2 ΓΓ / 20 kp / 3

490.5 ¥ 50 kp / 8 686.7 N / 70 kp / 12

4

9

12

The higher numerical values correspond to a greater coloring. In the present case, the values found are so close to each other under the same compressive stress (20,50 or 70 kp) that differentiation by

-1ϋMoving test

This examination serves to test the tightness of the capsules

Samples of CEB sheets according to ΒΙΪΊ-Α5, according to Comparative Example and Examples 3 and 4 were placed over a standard CE-sheet and loaded with 500 g, based on said area. Aging was performed for 6 days at 70 ° C and at an atmosphere set at 75 $ relative humidity. The coloring on the CE layer of the CE sheet, caused by the coloring component from damaged or defective microcapsules from leaf to leaf, is detected.

According to visual observation of CE-sheets, no differences can be detected between samples.

Aging :

The CEB sheets of Comparative Example and Examples 3 and 4 are stored in the dark at 70 ° ^C and 75 relative humidity. Aged samples were taken

C * O ' ^w fcj w are combined and described by a standard CE-list, EoEotom is used to determine the image intensity compared to a sample that has not undergone aging. The result can be seen from the following table.

Sensing aging

Comparative Example Example 3 Example 4

95 1 °

As the table shows, the values are here again

-13 so close to each other that it is not possible to make differentiation.

Note:

The sensed aging described in the 3rd submitted experimental reports corresponds essentially to the Accelerated Ageing described essentially on page 7, line 15 fx. EP-A-0 573 210, except that according to EP-A-0 573 210 the CP-color of the CPE-sheet is determined and not the loss of writing power. Aging of the subscription:

The transcripts of the CEB-sheets according to Comparative Example and Examples 3 and 4 on the CP-sheet were illuminated for 6 days with a daylight lamp and the intensity loss relative to the initial intensity was determined. Also, no differences between the capsules could be detected.

Comparative example Example 3 example 4% 15 $ 76 $

It has thus been shown that the use of the core solvent mixture according to the invention does not give rise to any negative effect of the writing performance and the aging resistance of the pressure-sensitive transfer papers known from SP-A-O-573 210.

Claims (6)

PATSNT KÁR O K ϊ 1. A microcapsule dispersion for the production of a novel pressure-sensitive paper in which the core solvent contained in the microcapsule comprises a dye preform or a mixture of dye preforms and vegetable oil solid or semi-solid at room temperature, characterized in that the core solvent consists of 1θ up to 30 phy> wt. from paraffin oil, liquid at room temperature, the remainder being vegetable oil, solid or semi-solid at room temperature, or from 25 to 60 phy. vegetable oil, liquid at room temperature, the remainder being vegetable oil, solid or semi-solid at room temperature or from 15 to 60 phy. % of a mixture of 5 to 30 phy. % paraffin oil, liquid at room temperature and 10 to 55 phy. vegetable oil, liquid at room temperature, the remainder being vegetable oil, solid or semi-solid at room temperature, the core solvent is liquid at room temperature, and the capsule wall material consists of a polyurea _{having a} The microcapsule dispersion according to claim 1, wherein the core solvent consists of 80 to 90 phy. oil-solid, semi-solid at room temperature, the remainder being paraffin oil, liquid at room temperature. 3. A microcapsule dispersion according to claim 1, wherein the core solvent consists of 60 to 70% by weight. vegetable oil, solid or semi-solid at room temperature, the remainder being vegetable oil, liquid at room temperature. Microcapsule dispersion according to one of claims 1 to 3, characterized in that the core solvent comprises as vegetable oil, solid or semi-solid at room temperature, coconut oil, palm oil and palm kernel oil or a mixture of these oils. Microcapsule dispersion according to one of claims 1 to 4, characterized in that the core solvent contains as vegetable oil, liquid at room temperature, rapeseed oil, sunflower oil, cottonseed oil, olive oil, corn oil, thistle oil or a mixture of these oils. . Microcapsule dispersion according to one of Claims 1 to 5, characterized in that a mixture of dye preforms containing a dye preform containing 2-phenyl-4- (4-diethylaminophenyl) -4- (4-methoxyphenyl) dye is present in the core solvent. -6-methyl-7-dimethylamino-4n-benz-3-ol 1-oxazine. -167. A microcapsule dispersion according to any one of claims 1 to 6, characterized in that the core solvent contained in the microcapsule does not solidify at temperatures above 18 ° C.