GB2503645A - Diacetylenes and their use in forming an image on a substrate - Google Patents

Abstract

The invention relates to a compound of the formula wherein R is H or an organic group of up to 20 C atoms; and Q is a hydrocarbon chain of up to 20 C atoms optionally interspersed with one or more heteroatoms. The diacetylenes of the invention are useful for providing an image on a substrate. In particular the compounds may exhibit polychromism and thus be useful for forming an image on a substrate or in a formulation by irradiation (optionally activated by another stimulus such as heat) resulting in a colour change. The diacetylenes may be applied to a substrate, e.g. as part of an ink formulation, or incorporated into a plastics formulation. Preferred compounds are diacetylenic bis-amides 10,12-docosadiynedioic acid bis(cyclopropylamide) and 10,12-pentacosadiynedioic acid bis(cyclopropylamide).

Description

DIACETYLENES AND THEIR USE IN FORMING AN IMAGE ON A

SUBSTRATE

Field of the Invention

This invention relates to diacetylenes and their use in forming an image on a substrate.

Background of the Invention

Diacetylenes are compounds that can be represented by the formula R-CC-CC-R. The ability of diacetylenes to give rise to visibly coloured polydiacetylenes is known. Polydiacetylenes often exhibit polychromism, i.e. they can display more than one visibly distinct colour. Typically, when exposed to UV light, a diacetylene initially gives rise to a blue coloured polydiacetylene.

Heating the blue polydiacetylene induces thermal perturbations into the polydiacetylene backbone that converts it into a red coloured form. Further heating of the red polydiacetylene will often produce a yellow polydiacetylene, but this species is usually transient and will revert to the red form upon cooling.

Diacetylenes can be used in multi-colour imaging applications.

Summary of the Invention

One aspect of the present invention is a diacetylene compound of the form u I a

R-CEC-CEC-Q-CO-NH

wherein R is H or an organic group of up to 20 C atoms; and o is a hydrocarbon chain of up to 20 C atoms optionally interspersed with one or more heteroatoms.

The present invention in another respect is a method of forming an image on a substrate, which comprises applying to the substrate, or incorporating within the substrate, the diacetylene compound, and irradiating the substrate to impart colour to the substrate.

Compounds of the invention have low molecular mass relative to known heat-activatable diacetylenes. They can give better colour yield for a given applied amount, and give rise to brighter and more vivid colours.

Description of the Invention

Preferred compounds of the invention are symmetrical and have the form u I a

NH-CO-Q-CEC-CEC-Q-CO-NH

wherein each 0 is as defined in claim 1. A particularly preferred compound of the invention is 10,12-docosadiynedioic acid bis(cyclopropylamide). Another is 10,12-pentacosadiynedioic acid bis(cyclopropylamide).

Compounds of the invention are amides. It is possible that the amide group can be replaced by another linking group such as, ester, thioester, ether, thioether, carbonyl, urethane, urea, amine etc. There may be more than one such group. It will also be appreciated that the ring may include a heteroatom andlor be substituted by one or more organic groups, e.g. OH or halogen.

It is particularly preferred that the diacetylene compound is activatable.

"Activatable" means that the diacetylene compound exists in an initial form that is unreactive to UV light and can be converted into a form that is reactive to UV light by application of a stimulus. Examples of suitable stimuli include radiation and direct contact heat. The activation can be reversible or irreversible. After activation, the diacetylene compound reacts to UV light (200 to 400 nm) to form a coloured polydiacetylene.

In addition to the diacetylene, and whether applied together with it or separately, e.g. in a separate layer, the invention includes the use of any other colour-generating system. For example, the diacetylene gives rise to blue and red and another system comprises either a yellow or green-generating system.

Suitable other chemistries include: other diacetylenes particularly activatable diacetylene that only give rise to yellow or green colours; charrables; transition metal oxyanions such as molybdates; and charge transfer complexes.

Particularly preferred are leuco dyes, including the photochromic and halochromic type. Examples of photochromic leuco dyes include spiroxazines and naphthopyrans. Examples of suitable halochromic types include phthalides, fluorans, triarylmethanes, benzoxazines, quinazolines, spiropyrans, quinones, thiazines and oxazines.

If the leuco dye is halochromic, it is preferably used in combination with an acid or base-generating agent. Acid-generating agents are preferred, in particular thermal acid-generating agents (TAGs). These are species that liberate acid when heated. Any TAG may be used in the present invention, but it is particularly preferred to use a TAG that gives rise to a system requires significantly more energy to undergo a colour change reaction than that needed to activate the diacetylene compound, and thereby allows a second colour-change reaction to take place whilst causing the diacetylene compound to become deactivated and incapable of undergoing colour change reactions.

Preferred examples of suitable TAGs are disclosed in W02006/108745, W02007/088104, W02008/110487, W02009/010393, and W02010/049281.

More preferred examples are the amine salt boron and silicon complex TAGs as disclosed in W02006/108745. Examples of such TAGs include tn-n-butylammonium borodibenzilate and tri-n-butylammonium borodisalicylate.

In use of the invention, the diacetylene is typically applied as a layer to any suitable substrate. Examples include paper, corrugated paperboard, cardboard, polymer films, such as PET, PE and PP, particularly BOPP films, cellulose films, ridged 3-D plastics articles, metals and metal foils, textiles, foodstuffs and pharmaceutical preparations.

The diacetylene layer can be applied using an ink formulation which can be water or organic solvent-based or a mixture of the two. The ink can be applied using any suitable coating technique. It is preferable that the ink also comprises a binder. The binder can be any suitable binder. Preferably, the binder is a polymeric binder. Examples of suitable polymeric binders includes acrylic polymers, styrene polymers and hydrogenated products thereof, vinyl polymers, polyolefins and hydrogenated or epoxidised products thereof, aldehyde polymers, epoxide polymers, polyamides, polyesters, polyurethanes, sulphone-based polymers and natural polymers and derivatives thereof. The polymeric binder can also be a mixture of polymeric binders.

Other possible components in the ink formulations include: polymers, light/energy absorbing agents, UV absorbers such as 2-hydroxy-4-methoxybenzophenone, surfactants, wetting agents, drying promoters, colourants such as traditional dyes and pigments, tinting agents, fluorescent agents, plasticisers, optical brighteners, oxidizing or reducing agents, stabilizers, light stabilizing agents such as hindered amines, rheology modifiers such as thickening or thinning agents, humectants, solvents, adhesion promoters, acid or base scavenging agents or retarders.

Activation/imaging can be carried out using any suitable system that can apply energy to the substrate. The energy can be direct heat as applied by a thermal print head, or radiation such as light. The radiation can be broadband or mono-chromatic, coherent or non-coherent. The radiation can in the wavelength range 100 nm to 32 microns. It can be supplied by a light-emitting diode or a lamp that emits UV, visible or IR radiation, or by a laser such as a UV, visible, or IR laser. The IR laser can be a mid-IR CO2 laser or a near-IR Nd:YAG or fibre laser operating with an emission wavelength in the range 700 nm to 2500 nm. The light sources can be a single source such as a steered beam system or an array of sources.

The substrate and/or the ink formulation can also comprise a NIR-absorber. These are preferred if the imaging system comprises a NIR laser with an emission wavelength in the range 700 nm to 2500 nm. Any suitable NIR-absorber can be used. It is preferred if the absorbance profile or Imax of the NIR-absorber approximately matches the emission wavelength of the laser.

More preferred NIR-absorbers have negligible impact on the background colour of the substrate. The most preferred NIR absorbers include: inorganic copper salts such as copper (II) hydroxyl phosphate; organic NIR dyes and pigments, such as N,N,N, PT-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoroantimonate); non-stoichiometric inorganic compounds, such as reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxides, reduced antimony tin oxide, or doped metal oxides such as AZO and ETO; and conductive polymers such as PEDOT.

The following Examples illustrate the invention.

Example I

Synthesis of 10,1 2-docosadiynedioic acid bis(cyclopropylamide) 10,12-Docosadiynedioic acid was purchased from GFS Chemical, Columbus, OH, USA. All other reagents and solvents were standard laboratory grade and purchased from Sigma-Aldrich.

10,12-Docosadiynedioic acid (18.1 g, 0.O5mol) was dissolved in anhydrous THF (300 ml) at 20°C. The solution was filtered under vacuum to remove the small quantity of insoluble matter that remained. To this solution was added oxalyl chloride (25.4 g, 0.2mol) followed by a few drops of dimethylformamide. The reaction mixture was then left stirring at 20°C for 4 hours. After this time the THE and excess oxalyl chloride were removed under rotary evaporation to leave an oily acid chloride intermediate compound. The acid chloride was then re-dissolved in fresh anhydrous THF (250 ml).

Cyclopropylamine (6.28 g, 0.11 mol) and N-methylmorpholine (11.13 g, 0.11 mol) was dissolved in anhydrous THF (50 ml). The cyclopropylamine solution was then added to the acid chloride solution over 5 minutes. The reaction mixture was then left stirring at 20°C for 2 hours. After this time the resultant white precipitate was collected under vacuum filtration, washed in water (100 ml), followed by THF (100 ml) and dried in a vacuum oven at 25°C.

Yield = 17.6g, 0.O4mol, -80%, melting point = 156°C.

Example 2

Printed Substrate The 10,12-docosadiynedioic acid bis(cyclopropylamide) was formulated into a water-based liquid ink as follows: Component Quantity (g) Joncryl 7085 (ex. BASE, aqueous styrene acrylic binder 15.0 solution) ___________________ Water 15.0 Dispelair CF49 (ex. Blackburn Chemicals, mineral oil 0.2 defoamer) ___________________ Agitan 350 (ex. Munzing, non ionic surfactant defoamer) 0.2 Dispex A40 (ex. BASE, ammonium salt of an acrylic 0.4 polymer in water, dispersing agent) __________________ r-ITO nanopowder (NIR absorber) 2.5 10,12-Docosadiynedioic acid bis(cyclopropylamide) 7.5 The above components were mixed using a Silverson mixer and then milled using a 50 ml bead mill until a particle size of less than 5 microns as measured on a Hegmann gauge was obtained.

The following components were then added to the milled dispersion prepared above using a Silverson mixer.

Component Quantity (g) Joncryl 8052 (ex. BASF, aqueous emulsion binder) 35.0 Joncryl 8064 (ex. BASF, aqueous styrene-acrylic 20.0 emulsion binder) ___________________ Tyzor LA (ex. Camida, titanium lactate in an aqueous 1.0 solution, adhesion promoter ___________________ The finished ink formulation was drawn down onto white paper using flexographic printing technique. A dry coat weight of 6-8 gsm was obtained.

A 20W, 1550 nm fibre laser controlled by an IBM compatible PC was then used to activate regions of the printed substrate where an image was required. The activated substrate was then flood-illuminated using a germicidal UV lamp (266 nm), and only in the regions that were pre-activated using the NIR fibre laser were blue images obtained. The unactivated regions remained white.

The blue images were transformed into magenta and red by the application of heat.

Example 3

Plastics Coloration Using a 20 ton Battenfeld injection moulding machine, 10,12-docosadiynedioic acid bis(cyclopropylamide) (0.5%) was applied to the following resins at 200°C: Lupolen 1800 H -LDPE (ex. LyondellBasell).

Hastalen ACP5831 D -HDPE (ex. LyondellBasell).

Borealis HG 385 MO -PP (ox. Borealis).

And at 280°C Melinar B60 (ex. DuPontSA).

Application to LDPE, HDPE and PP resins was at 0.5% using an injection-moulding machine operating at 200°C. In each case, injection moulding produced a dual thickness plaque measuring approximately 20 x mm.

The plastic plaques were exposed to germicidal UV light (266 nm) which caused the plaques comprising the 10,12-docosadiynedioic acid bis(cyclopropylamide) to change colour.

Claims (10)

1. CLAIMSI. A diacetylene compound of the formulaR-CEC-CEC-Q-CO-NHwherein R is H or an organic group of up to 20 C atoms; and 0 is a hydrocarbon chain of up to 20 C atoms optionally interspersed with one or more heteroatoms.
2. 2. A compound according to claim 1, which is symmetrical and has the form u I a

   NH-CO-Q-CEC-CEC-Q-CO-NHwherein each Q is as defined in claim I.
3. 3. A compound according to claim I, which is i0,12-docosadiynedioic acid bis(cyclopropylamide).
4. 4. A substrate on or within which is a compound according to any preceding claim.
5. 5. A plastics formulation comprising a compound according to any of claims ito 3.
6. 6. A method of marking a substrate according to claim 4 or a formulation according to claim 5, which comprises irradiation of the substrate or formulation, to form a coloured image.
7. 7. A method according to claim 6, which comprises an initial step of activating the compound.
8. 8. A method according to claim 7, wherein the activating is by heat.
9. 9. A method according to claim 7 or claim 8, wherein the activated compound is converted into its coloured form using light having a wavelength in the range of 200 to 450 nm.
10. 10. A method according to any of claims 6 to 9, wherein a near infrared-absorbing agent which absorbs light at a wavelength in the range 700 to 2500 nm, is also applied to the substrate, in the same layer as, or a different layer from, the diacetylene compound.