GB2314852A

GB2314852A - Ink composition

Info

Publication number: GB2314852A
Application number: GB9714219A
Authority: GB
Inventors: Kirsten Buehrke
Original assignee: JS Staedtler GmbH and Co KG
Current assignee: JS Staedtler GmbH and Co KG
Priority date: 1996-07-04
Filing date: 1997-07-04
Publication date: 1998-01-14
Anticipated expiration: 2017-07-04
Also published as: GB2314852B; JP3072834B2; DE19626842A1; FR2750702A1; DE19626842C2; IT1293070B1; ITRM970393A0; FR2750702B1; JPH1060355A; ITRM970393A1; GB9714219D0

Abstract

An ink with prolonged "cap off time", in particular a non-aqueous ink for writing, drawing, painting, printing or marking, or a writing or marking liquid, comprises an organic solvent, a binding agent, a drying retardant, a colourant and optionally also further additives, wherein the retardant comprises a paraffin wax and/or a polyolefin wax, which preferably is or are insoluble in organic solvents. In the prefered composition, the binding agent is a phenol formaldehyde resin or an adduct of fumaric acid and colophony, and the solvent is n-propanol, i-propanol, a mixture thereof or ethanol.

Description

2314852 INK COMPOSITION The present invention relates to an ink, in

particular an ink with prolonged "cap-off time", and a method of producing such an ink, and has particular reference to an ink for writing, drawing, painting, printing or marking which preferably results in permanent, i.e. water-resistant, strokes.

Inks of that kind are known, above all as marking liquids. Such marking inks mostly include organic solvents, for example alcohols or glycol ether, binding agents soluble in solvents, surfactants, preferably fluorine surfactants, and dyes soluble in solvents, for example solvent dyes or basic dyes. Basic dyes in that case can be converted into a lake by an acid resin or binding agent. Glycols, for example 1, 2 polypropylene glycol, are used as drying retarders for finer line widths.

The main disadvantage of these markers is their low "cap-off time", i.e. the time for which a marking or writing instrument of that kind can remain lying unclosed without drying out. Even after a relatively short time, most conventional ink applications exhibit poor initial writing behaviour or no longer function at all or must be re-activated by, for example, writing or drawing movements. After one day, or at the latest after a few days, these instruments may have dried to such an extent that they can no longer be re-activated and thereby become completely unusable.

In JP-P/AS 6-47 660 there is disclosed an ink with an increased "cap-off time", which can be stored over a longer time span without a protective cap. This ink is composed of a dye, an organic solyent, resin, decaglycerine and w_,-olefin (alpha-olefines). Olefin is the group 2 designation for acyclic or cyclic aliphatic hydrocarbons with one or more reactive double bonds in the molecule. When,e--olefines are present, the double bond lies between the first and second hydrocarbon atoms and is highly capable of reaction in view of the unsaturated character. A disadvantage of this ink is the presence ofec-olefines, which can lead to the ink not being stable in storage due to reaction of the <-olefin with other ink components.

In addition, "permanent markers" or "non-dry permanent markerC are also known, which have a "cap-off time" of about 14 days. The "non-dry inks" therein contain, for example, n-propanol, n-butanol, 3methylbenzoic acid, water, toluene, acetic acidn-butyl ester, propionic acid, propyl ester, xylene and solvent dyestuffs. The main disadvantage of these inks is that they exhibit initial writing difficulties even after a short time and regenerate only in use, when a normal ink flow sets in again.

A further disadvantage is to be seen in the poor wetting capability of non-absorbent substrates, such as foils, with the result that nonwetted, discrete locations are formed in the case of application over an area. Equally disadvantageous is the lacking colour brilliance of the ink which, after drying, has a turbid appearance, particularly in the case of use on non-absorbent backgrounds. This is readily recognised with foils which have been written on and are viewed in transmitted light.

Moreover, solvent inks are known for smooth surfaces,, in particular "white board markerC, with pigments as colouring agents. In this case, the pigments are combined with a binding agent as carrier, such as polyvinyl butyral or nitrocellulose, to form a pigment preparation. A 3 disadvantage is that these, too, offer only a low "cap-off time".

There is therefore still a need for an ink, for example a writing or marking liquid based on organic solvents, with an extended "cap-off time", i.e. which enables a writing or marking instrument to remain unclosed over a longer time without the i nk in the applicator tip drying to such an extent that the instrument becomes unusable. Moreover, particularly in the case of permanent inks, i.e. water-resistant inks, a good transparency and luminosity of strokes is desirable after drying of the ink, especially on non-absorbent surfaces and for transmitted light applications or markings, for example glass surfaces or foils for daylight projection.

According to the present invention there is provided an ink with prolonged "cap-off time", particularly a non-aqueous ink for writing, drawing, painting, printing or marking or a writing or marking liquid, comprising organic solvents, binding agents, drying retarders, colourants and possibly further additives, characterised in that the drying retarder is a paraffin wax and/or a polyolefin wax.

"Prolonged cap-off time" in the present context signifies that the ink in the applicator does not dry out even in the case of longer storage with unclosed writing tip or with a closure cap removed, in particular the applicator should be able to remain open for a longer time, preferably several hours or even days.

The ink is preferably a non-aqueous ink for writing, drawing, painting, printing or marking, or a writing or marking liquid, and the paraffin wax and/or a polyolefin wax is or are preferably insoluble in organic solvents. For preference, a polyethylene wax is used.

The paraffin or polyolefin wax can be present as an aqueous wax 4 dispersion before addition to the other components of the ink mixture, for example as a commercial product already dispersed in water and possibly provided with a stabilising agent and/or with other additives, wherein the proportion of wax or solid substance can amount to 20 to 70 % by weight, preferably 30 to 6M. by weight and more preferably to 50% by weight.

The paraffin used in the wax dispersion preferably has a chain length of at least 17 carbon atoms and the organic solvent an evaporation number greater than 15, preferably 16, wherein diethylether = 1 is to be started from as comparison value. The solvent can be an n-propanol, ipropanol or ethanol or a mixture of i-propanol and n-propanol.

The binding agent can be an acid resin, especially in the case of use of basic dyes as colourant, and preferably is soluble in the organic solvent. The binding agent can be, for example, a phenol formaldehyde resin or an adduct of fumaric acid and colophony. If basic dyes are used, acid resins need not be used. Advantageously, the colourant is a dye or a pigment insoluble in water or a dye soluble in water and convertible into a lake, in particular converted into a lake by the binding agent. 20 Solvent substances or basic dyes are particularly suitable, wherein basic dyes can be converted into a lake or made to react with an acid resin on mixing with the other ink components. The colourant and the binding agent are preferably dissolved in the organic solvent. 25 The colourant can also advantageously be present as a dye preparation or liquid dye dissolved in organic solvents, preferably in npropanol, in particular as a commercial product, before addition to the other components of the ink mixture.

As additional dispersing aid, the ink can contain 3-methylbenzoic acid.

It is of particular advantage if the ink does not contain any fluorine surfactants, preferably no surfactants at all.

It has proved as favourable if the ink comprises 60 to 90% by weight of organic solvents, 1 to 10% by weight of binding agents, 0.01 to 5% of paraffin and/or polyolefin wax, 1 to 30 % by weight of colourant, 0 to 8 % by weight of a 3-methylbenzoic acid, and 0.01 to 10% by weight of water and/or additives.

For the production of an ink according to the invention, a first mixture (AB) can initially be produced as a dispersion of paraffin or polyolefin wax with 20 to 70% by weight of paraffin and/or polyolefin content (A) in water (B) or be procured as a commercial product, a second mixture (CDE) is then produced, in which the binding agent (C) and optionally also the 3-methylbenzoic acid (D) is or are stirred into the solvent (E) and dissolved therein, the colourant (F) is then added to the second mixture (CDE) and mixed in thoroughly until dissolved, converted into a lake or completely dispersed, and then the first mixture (AB) or the wax dispersion is added and stirred in thoroughly.

A colourant (F), which is initially present as a solvent dye (F1) insoluble in water, as a basic dye (F2) soluble in water or as a pigment preparation (FR), can also be added to the second mixture (CDE) of binding agent (C), solvent (E) and possibly 3-methylbenzoic acid (D).

The colourant (F) can initially also be present in liquid or in pasty form as a solvent dye (F1) insoluble in water and dissolved in n propanol (E1), as a dye (F2) soluble in water and optionally converted into a lake by the binding agent (C), or as a colour pigment (F3) preliminarily dispersed in n-propanol (E1), in a given case as a commercial product.

In a preferred example, the first mixture (AB) can comprise 0.01 to 5 % by weight, preferably 0.1 to 0.5% by weight, of wax (A) or paraffin wax (A1) and/or polyolefin wax (A2), which was dispersed in water (B). The production of the ink can, however, also take place in such a manner that initially 1 to 10 % by weight of binding agent (C), preferably an acid resin such as an adduct of fumaric acid and colophony (Cl) or a phenol formaldehyde resin (C2), is intermixed with the solvent (E) and the dye (F) and the wax dispersion (AB) is then stirred into this mixture (CEF) Embodiments of the ink and examples of the production thereof are described more particularly in the following.

Encompassing example: 60 to 95 % by weight of organic solvent 1 to 10 % by weight of binding agent 0.01 to 5 % by weight of paraffin and/or polyolefin wax 1 to 30 % by weight of dye 0.01 to 5 % of water 0 to 8 % by weight of 3-methylbenzoic acid 0 to 5 % by weight of other additives Formulation examples for dyestuff inks:

Example M: (yellow ink) n-propanol 90.6% by weight water 0.4 % by weight binding agent 3.8 % by weight 3-methylbenzoic acid 0.2 % by weight - 7 paraffin wax 0.2 % by weight solvent yellow 146 4.8% by weight' Example 1.2: (red ink) n-propanol 87.1 % by weight water 0.2 % by weight binding agent 3.3 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.2 % by weight solvent red 68 6.2 % by weight solvent orange 97 1.6 % by weight solvent red 49 0.3 % by weight solvent yellow 143 0.9 % by weight Example 1.3: (blue ink) n-propanol 87.3 % by weight water 0.3 % by weight binding agent 3.5 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.2 % by weight solvent blue 129 8.5 % by weight Example 1.4: (orange ink) n-propanol 90.3 % by weight water 0.3 % by weight binding agent 3.6 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.1 % by weight solvent red 68 3.6 % by weight solvent yellow 143 1.9 % by weight 8 Example 1.5: (green ink) n-propanol 88.8 % by weight water 0.5 % by weight binding agent 3.6 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.2 % by weight solvent blue 129 4.7 % by weight solvent yellow 143 2.0 % by weight Example 1.6: (lilac ink) n-propanol 89.8 % by weight water 0.6 % by weight binding agent 3.5 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.5 % by weight basic red 1:1 2.2 % by weight solvent violet 9 2.3 % by weight solvent red 49 0.9 % by weight Example 1.7: (brown ink) n-pronanol 91.3 % by weight water 0.2 % by weight binding agent 3.7 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.2 % by weight solvent brown 52 3.6 % by weight solvent orange 0.7 % by weight solvent red 0.1 % by weight 9 - Example 1.8: (black ink) n-propanol 84.2 % by weight water 0.3 % by weight binding agent 3.2 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.1 % by weight solvent brown 52 3.2 % by weight solvent violet 9 1.6 % by weight Example 1.91: (black ink) n-propanol 84.0 % by weight water 0.2 % by weight binding agent 3.2 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.2 % by weight solvent brown 52 10.6 % by weight solvent violet 9 1.6 % by weight Example 1.92: (blue ink) n-propanol 89.3% by weight water 0.3 % by weight binding agent 3.5 % by weight 3-methylbenzoic acid 0.2 % by weight paraffin wax 0.2 % by weight solvent blue 129 5.5 % by weight solvent violet 9 1.0 % by weight Example 1.93: (black ink) n-propanol 76.0 % by weight water 3.8 % by weight binding agent 2.9 % by weight 3-methylbenzoic acid 4.3 % by weight paraffin wax 2.0 % by weight solvent brown 52 9.6 % by weight solvent violet 1.4 % by weight Example 2: pigment ink: (blue pigment ink) n-propanol 37.4 % by weight i-propanol 37.6 % by weight paraffin wax 0.5 % by weight methoxypropyl acetate 18.8 % by weight polyvinyl butyral 1.9 % by weight pigment blue 15:3 3.8 % by weight Example 3: manufacturing example 1:

The manufacture of the ink takes place according to a first method in such a manner that a first mixture (AB) is produced initially in a first step either as dispersion of wax or as dispersion of paraffin wax or polyolefin wax with a content (A1/A2) of 20 to 70 % by weight of either wax or paraffin or polyolefin in water (B), wherein this mixture (AB) can also be presentas a commercial product, that a (second) mixture (CDE) is produced, wherein the binding agent (C) and in a given case the 3-methylbenzoic acid (D) are stirred into the solvent (E) and dissolved in this, that the dye (F) is added to and thoroughly mixed into this second mixture (CDE) ' unti 1 its dissolution, conversion into a lake or complete dispersion, where i n a] so the dye can be present as a commercial product, preferably as dye paste or as liquid dyestuff, and that the first mixture (AB) or the wax dispersion of the mixture (CDEF) is then added and likewise stirred in thoroughly.

In this case, a dye (F), which is initially present as solvent dye (F1) insoluble in water or as basic dye (F2) soluble in water or as pigment preparation (F3X), is added to the second mixture of binding agent (C), solvent (E) and, in a given case, 3-methylbenzoic acid (D).

Example 4: manufacturing example 2:

According to another method, the dye (F) can initially be present in liquid or pasty form as solvent dye (F1), which is insoluble in water and dissolved in n-propanol (E1) or as dye pigments (F3) also preliminarily dispersed in n-propanol (El).

Example 5: manufacturing example 3:

Alternatively, in yet another method - the first mixture (AB) can contain 0.01 to 5, preferably 0.1 to 0.5 % by weight of paraffin wax (A1) and/or polyolefin wax (A2), which was preliminarily dispersed in water (B).

Example 6: manufacturing example 4:

According to a further method, 1 to 10 % by weight of binding agent (C), preferably an acid resin, such as for example an adduct of fumaric acid and colophony (Cl), or a phenol -formaldehyde resin (C2) is intermixed with the solvent (E) and the dye (F) and the wax dispersion (AB) is then stirred into this mixture (CEF).

The following advantages may be achieved: a) "Cap-off time": The "Cap-off time" of pens with a permanent solvent ink embodying the invention may be increased to, on average, a good 2 to 4 weeks. Pens with the ink start to write satisfactorily even after 14 days exposure of the applicator tip to atmosphere and are immediately usable without restriction. Thereagainst, in the case of prior art pens there may be difficulties in initial writing after only 1.1. hours of exposure and the ink flow may be restored, it at all, only during the writing process. b) Transparency of the strokes: The strokes of inks embodying the invention are transparent and luminous even after thorough drying. Thus, the inks are suitable for non-absorbent surfaces and for surfaces subjected to transmitted light. c) Further properties are to be emphasised: The general properties of inks embodying the invention are comparable with those of known permanent solvent inks, i.e. they are suitable for writing on a wide variety of backgrounds and have correspondingly firm adhesion. Since the physical values, for example density and viscosity, are very similar in view of the components present, inks embodying the invention can be used in regular marker pens or wick-type writing devices with maintenance of the accustomed ink flow.

The fastness to light substantially corresponds with that of known, commercially available inks and the colour tones largely correspond with those of commercially available "permanent inks".

In order to achieve a high "cap-off time", for preference a dye (F) and a binding agent (C) are initially dissolved in an organic solvent (E) and interspersed with a small proportion of a paraffin or polyolefin wax dispersion (AB). The solvent (E) in this case need not dissolve the paraffin or polyolefin wax (A). The "cap-off time" can be improved slightly by the addition of 3-methylbenzoic acid (D).

The ink preferably has the following components:

to 95 % by weight of an organic solvent, in which paraffin waxes or polyolefin waxes are not soluble, 1 to 10 % by weight of a binding agent soluble in the organic solvent, 0.05 to 8 % by weight of 3-methylbenzoic acid (optional additive), 0.05 to 5 % by weight of paraffin or polyolefin wax dispersion (wherein this range is applicable to a wax dispersion with a proportion of about 30% by weight of solid substance_; if the proportion is different, then the content of the dispersion in the ink should correspondingly vary), 1 to 30 % by weight of dye, which is preferably soluble in a solvent or present as a pigment, which when used in solvent systems is mostly "coated" on a binding agent, soluble in solvent, as carrier.

The "cap-off time" is increased in the case of use of a paraffin wax dispersion in a pigment ink just as in the case of use in a dye ink. A marker with a regular, alcohol pigment ink will dry out after about 3 hours. The same ink with the addition of paraffin wax dispersion can thereagainst be stored in an exposed state for about 2 days, possibly even longer. Although initial writing difficulties may be present possibly after one day, the marker will satisfactorily regenerate at this time, thus make itself reusable. A high "cap-off time" of more than 14 days, which is possible for dye inks, is not at present applicable to pigment inks. For this purpose, modification of the composition is - 14 required.

In general, it can be stated that dyes for the use in "cap-off inks" are more suitable, according to present knowledge, than pigments. Dyes are dissolved in inks, whereas pigments are in solid undissolved form.

Pigment inks are thus always subject to the risk that the colourant precipitates and clogs the writing tip. Due to the ink loss occurring in the case of open storage of a pen, solid pigment particles deposit more rapidly at the tip, whereas dyes concentrate in the writing tip, the ink becomes "thicker" and the dye content in the remaining solvent becomes higher, but solid dye encrustations do not initially form.

In addition, pigments at present available for use in solvent inks are coated onto a binding agent, thus a "carrier". Such binding agents are usually polyvinylbutyral, sometimes nitrocellulose. The latter greatly increases the viscosity of an ink, so that pigments with the former as carrier appear to be more suitable for inks of that kind.

Polyvinylbutyral is very greasy and sticky when dissolved. This greasy, thread-pulling and adhesive property of the resin has an unfavourable effect on the "cap-off behaviour" of the ink, since the writing tips will gum up correspondingly quickly in the case of loss of solvent. Moreover, for purposes of the stabilisation of a pigment ink it is necessary to add further polyvinylbutyral to the "pigment preparation". The solid substance proportion of a sticky component is thereby increased and the "cap-off property" reduced. In addition, the pigments, as solid colourant bodies, can make the formation of a paraffin wax skin somewhat more difficult and thus not prevent evaporation of the solvent to the extent applicable to dye inks. Nevertheless, pigments are suitable as colourants in "cap-off inks". As already explained, markers - with pigment ink, to which a paraffin wax dispersion has been added, can be stored open for about 45 hours, whilst markers with conventional ink dry out after about 3 hours.

In the following, the effect of the individual components is described.

a) Solvent (E):

For a "cap-off inC, a solvent (E) is used in which paraffins or polyolefins, more particularly paraffin waxes or polyolefin waxes, do not dissolve. For preference, the solvent has an evaporation number approximately equal t o 16 (for diethylether = 1). If the evaporation number is higher, the drying time of the ink strokes is correspondingly prolonged. Especially suitable is n-propanol, with which the paraffin or pololefin wax dispersion is particularly compatible. In principle, a proportion of about 75 to 92 % by weight of the solvent in the ink, in dependence on the quantitative addition of dye, is desfrable.

b) Binding agnet (C):

The adhesive strength of the "cap-off inC on non-absorbent backgrounds is improved by the addition of a binding agent (C). In the case of basic dyes, an acid resin should be used in order to convert the otherwise in part water-soluble dyes in the ink into a lake and thus into a water insoluble state. In a preferred "cap-off inC, about 3 to 4 % by weight of binding agent is used. In this range, a good adhesion of the ink strokes on non-absorbent backgrounds is achieved without negatively influencing the "cap-off ink".

c) Dyes (F):

For a "cap-off inC as permanent writing liquid on a solvent base, appropriate soluble dyes, for example solvent dyes or basic dyes, should be used. Basic dyes in this case are, as described in b) above, converted into a lake for purposes of the water resistance. Solvent dyes, which are preferably obtainable in pasty form, are particularly suitable, but without addition of a setting agent, although preliminarily dissolved in, for example n-propanol, to assist processing and setting of colour.

The pasty aggregate state of the pure dye and the dispensing with a setting agent have the effect that crystallisation of dye and setting agent is not possible.

In order to achieve the highest possible "cap-off time", the dye content, especially of powder dyes, should be kept as low as possible. The higher the dye content, the lower the "cap-off time". Pens with black ink can be stored open for about 2 to 3 weeks, whereas pens with, for example, yellow ink can be stored open for a good 4 weeks. The high dye content of the black ink thus causes a shortening of the "cap-off time".

d) 3-methylbenzoic acid (D):

A paraffin wax dispersion can be worked more finely and stably into a solvent, preferably n-propanol, if 3-methylbenzoic acid is added to the solvent. In that case, a 3-methylbenzoic acid concentration of only 0.2% by weight may be sufficient to achieve an improvement in "cap-off time". However, the acid does not have to be used in the ink, since good "capoff times" can be achieved without it.

e) Surfactant It is desirable that fluorine surfactants should not be present in the "cap-off inC, as is otherwise usual in regular permanent solvent inks. The "cap-off time" of the ink is otherwise drastically reduced.

f) Paraffin wax dispersion (AB):

The paraffin or polyolefin waxes are dispersed in water. In that case, natural rubber such as gumgahtti (or also a surfactant) can be used as dispersing agent.

Paraffins are saturated, aliphatic hydrocarbons and are also known as alkane. They are solid and wax-like above a chain length of 17 carbon atoms and are called "hard paraffin" or also "paraffin wax" in this state. Paraffins with a molar mass of more than 1000 gram/molecules are often termed polyolefin (literature: Rbmpps Chemie-Lexikon, "Paraffine").

Paraffin wax dispersions and/or polyolefin wax dispersions can be used for the "cap-off ink". A suitable polyolefin wax is,. for example, polyethylene (PE) with a molar mass of less than 10,000 gram/molecules, also called LDPE. This low molecular PE is by its nature wax-like. Since a polyolefin wax is a long-chain paraffin or paraffin wax (or hard paraffin), only paraffin wax is discussed in the following, but polyolefin wax is also intended in the same sense.

In the case of a solid substance content of the paraffin dispersion of about 35%, about 0.4 to 0.5 % of paraffin dispersion should be used in the ink. There is then obtained an ink with higher "cap-off time" and also shorter drying time of the strokes.

The ink is turbid after addition of the dispersion. With time, a somewhat fine precipitation forms. The ink can be filtered by a filter with a pore size of 5 micrometres until it appears clear.

The paraffin wax does not dissolve in the ink base, but is merely finely distributed therein. When a marker is filled with this ink, a largely homogeneous mixture of the ink with the paraffin wax is situated in the reservoir and the tip. If the marker is stored in open state, the 18 paraffin wax prevents strong evaporation of the solvent by the formation of a skin at the ink surface. Consequently, a marker with a wedge tip can be stored open for a good 2 to 4 weeks instead of only a few hours. Only after this time has so much solvent escaped, in spite of the paraffin wax skin, that the pen dries out. Since small quantities of solvent always evaporate over time notwithstanding the paraffin wax addition, the ink of a pen kept open appears somewhat dark and stronger when first used. After only a short initial amount of use, the colour tone is restored. It is possible to use different concentrations of the paraffin wax dispersion. In principle, the "cap-off time" is lower for smaller paraffin wax concentrations than for higher concentrations. If a large quantity of paraffin wax is used, the drying time for the ink strokes increases parallelly to the "cap-off time" in the respect that the strokes remain sticky over a longer time.

In order to achieve a rapid drying time of the. ink strokes with simultaneously good "cap-off time", an addition of about 0.4 to 0.5 % by weight of a paraffin wax dispersion with a solid substance content of about 35% is particularly advantageous. Paraffin wax dispersions with a differing solid substance proportion can vary correspondingly in dependence on their quantitative addition.

If a liquid paraffin is used in place of a paraffin wax dispersion, an increase in the "cap-off time" is not observable. The liquid paraffin intermixes extremely finely with the solvent. This is presumably due to the small chain length of the liquid paraffins by comparison with the hard paraffins. The effect of the paraffin on the "cap-off time" is drastically reduced as a consequence.

If a writing instrument or pen has dried out at the writing tip - 19 after open storage for too long a period of time, but has not dried out completely, then it can be regenerated by storage in a closed state.

As explained, the surfactants usual for permanent solvent inks, especially fluorine surfactants, are preferably not used in the "cap-off ink". Surfactants, however, allow a go-od wetting of smooth surfaces.

The wetting properties of the "cap-off inC can for this reason be slightly poorer than for the regular inks. In the case of application of wide ink strokes, punctiform, non-wetted places in the ink area can arise and are recognisable in transmitted light. For most applications, however, this effect does not arise.

Claims

- 20 CLAIMS 1. An ink with delayed tendency to dry out when exposed to

atmosphere in an applicator, the ink comprising an organic solvent, a binding agent, a colourant and a drying retardant which comprises at least one of a paraffin wax and a polyolefin wax.
2. An ink as claimed in claim 1, wherein the ink is a non-aqueous ink.
3. An ink as claimed in claim 1 or claim 2, wherein the or each wax of the retardant is insoluble in organic solvents.
4. An ink as claimed in any one of the preceding claims, wherein the retardant is a polyethylene wax.
5. An ink as claimed in any one of the preceding claims, wherein the or each wax of the retardant is in the form of an aqueous dispersion before addition to other components of the ink.
6. An ink as claimed in claim 5, wherein the at least one wax is paraffin wax and the paraffin used in the dispersion has a chain length of at least 17 carbon atoms.
7. An ink as claimed in claim 5 or claim 6, wherein the dispersion has a solids proportion of 20 to 70 weight percent before addition to the other components of the ink.
8. An ink as claimed in claim 7, wherein the solids proportion is 30 to 60 weight percent.
9. An ink as claimed in any one of the preceding claims, wherein the organic solvent has an evaporation number greater than 15 starting from diethylether = 1 as comparison value.
10. An ink as claimed in claim 9, wherein the evaporation number is 16.
11. An ink as claimed in any one of the preceding claims, wherein the organic solvent comprises an n-propanol.
12. An ink as claimed in any one of the preceding claims, wherein the organic solvent comprises an i-propanol or an ethanol.
13. An ink as claimed in any one of the preceding claims, wherein the 10 organic solvent comprises a mixture of i-propanol and n-propanol.
14. An ink as claimed in any one of the preceding claims, wherein the binding agent comprises an acid resin.
15. An ink as claimed in any one of the preceding claims, wherein the binding agent is soluble in the organic solvent.
16. An ink as claimed in any one of the preceding claims, wherein the binding agent comprises a phenol formaldehyde resin.
17. An ink as claimed in any one of the preceding claims, wherein the binding agent comprises an adduct of fumaric acid and colophony.

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18. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a water-insoluble dye or water-insoluble pigment.
19. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a water-soluble dye convertible into a lake by the 5 binding agent.
20. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a solvent dye or a basic dye.
21. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a basic dye which reacts with or is converted into a 10 lake by an acid resin on addition to other components of the ink.
22. An ink as claimed in any one of the preceding claims, wherein the colourant and the binding agent are dissolved in the organic solvent.
23. An ink as claimed in any one of the preceding claims, wherein the colourant has the form of a liquid dye dissolved in organic solvent 15 before addition to other components of the ink.
24. An ink as claimed in claim 23, wherein the solvent in which the liquid dye is dissolved is n-propanol.
25. An ink as claimed in any one of the preceding claims, comprising a dispersant.
26. An ink as claimed in claim 25, wherein the dispersant is a 3methylbenzoic acid.
27. An ink as claimed in any one of the preceding claims, wherein the ink composition is free of fluorine surfactant.
28. An ink as claimed in any one of the preceding claims, wherein the ink composition is free of all surfactants.
29. An ink as claimed in any one of the preceding claims, comprising 60 to 95 weight percent of organic solvent, 1 to 10 weight percent of binding agent, 0.01 to 5 weight percent of paraffin wax and/or polyolefin wax, 1 to 30 weight percent of colourant, 0 to 8 weight percent of 3methylbenzoic acid and 0.01 to 10 weight percent of water and/or another additive or other additives.
30. An ink substantially as hereinbefore described with reference to any one of Examples 1.1 to 2.
31. A method of producing an ink as claimed in claim 1, comprising the steps of producing a first mixture in the form of an aqueous dispersion of wax, paraffin wax or polyolefin wax with a wax, paraffin or polyolefin content of 20 to 70 weight percent, producing a second mixture comprising an organic solvent and a binding agent, adding a colourant to the second mixture and mixing in until dissolved, converted into a lake or fully dispersed, and then mixing together the first and second mixtures.

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32. A method as claimed in claim 31, wherein the second mixture further comprises 3-methylbenzoic acid.
33. A method as claimed in claim 31 or claim 32, wherein the colourant has the form of a water-insoluble solvent dye, a water-soluble basic dye or a pigment.
34. A method as claimed in claim 33, wherein the colourant is in the form of a liquid or pasty water-insoluble solvent dye dissolved in npropanol, a liquid or pasty water-soluble dye, or pigments dispersed in n-propanol.
35. A method as claimed in any one of claims 31 to 34, wherein the first mixture comprises 0.01 to 5 weight percent of wax, paraffin wax and/or polyolefin wax dispersed in water.
36. A method as claimed in claim 35, wherein the first mixture comprises 0.1 to 0.5 weight percent of the wax, paraffin wax and/or polyolefin wax.
37. A method as claimed in any one of claims 31 to 36, wherein the second mixture comprises 1 to 10 weight percent of the binding agent.
38. A method as claimed in claim 37, wherein the binding agent comprises an acid resin.
39. A method as claimed in claim 38, wherein the binding agent comprises 20 an adduct of fumaric acid colophony or a phenol formaldehyde resin.

'I
40. A method as claimed in claim 31 and substantially as hereinbefore described with reference to any one of Examples 3 to 6.

39. A method as claimed in claim 38, wherein the binding agent comprises 20 an adduct of fumaric acid colophony or a phenol formaldehyde resin.

40. A method as claimed in claim 31 and substantially as hereinbefore described with reference to any one of Examples 3 to 6.

Amendments to the claims have been filed as follows - Z6 CLAIMS I An ink with delayed tendency to dry out when exposed to atmosphere in an applicator, the ink comprising an organic solvent, a binding agent, a colourant and a drying retardant which comprises at least one of a paraff in wax and a polyolef in wax, wherein the or each wax of the retardant is insoluble in the organic solvents predominantly used.

2. An ink as claimed in claim 1, wherein the ink is a non-aqueous ink.

3. An ink as claimed in claim I or claim 2, wherein the ink is usable for writing, drawing, painting, printing or marking.

4. An ink as claimed in any one of the preceding claims, wherein the retardant is a polyethylene wax.

5. An ink as claimed in any one of the preceding claims, wherein the or each wax of the retardant is in the form of an aqueous dispersion before addition to other components of the ink.

6. A19 ink as claimed in claim 5, wherein the at least one wax is paraffin wax and the paraffin used in the dispersion has a chain length of at least 17 carbon atoms.

7. An ink as claimed in claim 5 or claim 6, wherein the dispersion has a solids proportion of 20 to 70 weight percent before addition to the other components of the 4.nk.

-ion is 30 ' S. An ink as claimed in claim 7, wherein the solids proport Io weight percent.

9. An ink as claimed in any one of the preceding claims, wherein the organic solvent has an evaporation number greater than 15 starting from diethylether = 1 as comparison value.

10. An ink as claimed in claim 9, wherein the evaporation number is 16.

11. An ink as claimed in any one of the preceding claims, wherein the organic solvent comprises an n-propanol.

12. An ink as claimed in any one of the preceding claims, wherein the organic solvent comprises an i-propanol or an ethanol.

13. An ink as claimed in any one of the preceding claims, wherein the 10 organic solvent comprises a mixture of i-propanol and n-propanol.

14. An ink as claimed in any one of the preceding claims, wherein the binding agent comprises an acid resin.

15. An ink as claimed in any one of the preceding claims, wherein the binding agent is soluble in the organic solvent.

16. An ink as claimed in any one of the preceding claims, wherein the binding agent comprises a phenol formaldehyde resin.

17. An ink as claimed in any one of the preceding claims, wherein the binding agent comprises an adduct of fumaric acid and colophony.

18. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a water-insoluble dye or water-insoluble pigment.

19. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a water-soluble dye convertible into a lake by the binding agent.

20. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a solvent dye or a basic dye.

21. An ink as claimed in any one of the preceding claims, wherein the colourant comprises a basic dye which reacts with or is converted into a 10 lake by an acid resin on addition to other components of the ink.

22. An ink as claimed in any one of the preceding claims, wherein the colourant and the binding agent are dissolved in the organic solvent.

23. An ink as claimed in any one of the preceding claims, wherein the 1 colourant has the form of a liquid dye dissolved in organic solvent 15 before addition to other components of the ink.

24. An ink as claimed in claim 23, wherein the solvent in which the liquid dye is dissolved is n-propanol.

25. An ink as claimed in any one of the preceding claims, comprising a dispersant.

- 1 - 2q - 26. An ink as claimed in claim 25, wherein the dispersant is a 3methylbenzoic acid.

27. An ink as claimed in any one of the preceding claims, wherein the ink composition is free of fluorine surfactant.

28. An ink as claimed in any one of the preceding claims, wherein the ink composition is free of all surfactants.

29. An ink as claimed in any one of the preceding claims, comprising 00 to 95 weight percent of organic solvent, 1 to 10 weight percent of binding agent, 0.01 to 5 weight percent of paraffin wax and/or polyolefin wax, 1 to 30 weight percent of colourant, 0 to 8 weight percent of 3methylbenzoic acid and 0.01 to 10 weight percent of water and/or another additive or other additives.

30. An ink substantially as hereinbefore described with reference to any one of Examples 1.1 to 2.

31. A method of producing an ink as claimed in claim 1, comprising the steps of producing a first mixture in the form of an aqueous dispersion of wax, paraffin wax or polyolefin wax with a wax, paraffin or polyolefin content of 20 to 70 weight percent, producing a second mixture comprising an organic solvent and a binding agent, adding a colourant to the second mixture and mixing in until dissolved, converted into a lake or fully dispersed, and then mixing together the first and second mixtures.

32. A method as claimed in claim 31, wherein the second mixture further comprises 3-methylbenzoic acid.

33. A method as claimed in claim 31 or claim 32, wherein the colourant has the form of a water-insoluble solvent dye, a water-soluble basic dye or a pigment.

34. A method as claimed in claim 33, wherein the colourant is in the form of a liquid or pasty water-insoluble solvent dye dissolved in npropanol, a liquid or pasty water-soluble dye, or pigments dispersed in n-propanol.

35. A method as claimed in any one of claims 31 to 34, wherein the first mixture comprises 0.01 to 5 weight percent of wax, paraffin wax and/or polyolefin wax dispersed in water.

36. A method as claimed in claim 35, wherein the first mixture comprises 0.1 to 0.5 weight percent of the wax, paraffin wax and/or polyolefin wax.

37. A method as claimed in any one of claims 31 to 36, wherein the second mixture comprises 1 to 10 weight percent of the binding agent.

38. A method as claimed in claim 37, wherein the binding agent comprises an acid resin.