Ink-jet printing process using polymeric biguanides

Details Ink-jet printing process using polymeric biguanides Ink-jet printing process using polymeric biguanides

2001-05-15

2002-11-26

Hallacher, Craig (Department: 2853)

Incremental printing of symbolic information

Ink jet

Medium and processing means

C347S100000, C347S105000

Reexamination Certificate

active

06485139

ABSTRACT:

BACKGROUND OF INVENTION
The present invention relates to an ink jet printing method, to recording sheets, to compositions suitable for use in the preparation of recording sheets and to a set of liquids suitable for use in an ink jet printer.
SUMMARY OF INVENTION
Ink jet printing (IJP) is a non-impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate. The images prepared by IJP desirably meet many demanding requirements. For example, they should be sharp and non-feathered and should also exhibit high water-fastness, light-fastness, humidity-fastness and optical density. Furthermore the recording sheets printed with the images are preferred to dry quickly so that sheets printed shortly afterwards do not smudge the image. The sheets preferably do not crack significantly, even when printed with pigment-based inks, and they should not markedly affect the shade or hue of the ink in such a way that an incorrectly coloured image results. The recording sheets ideally are not such that they stick together during storage or after printing.
We have found that the many of these demanding requirements can be satisfied by using the processes, compositions and recording sheets according to the present invention as described in more detail below.
European patent application No. 0 291 214 A2 describes an information device in the form of a substrate which carries concealed information which becomes detectable by suitably treating the substrate, e.g. by washing. The device could use a number of fixing agents used to write the concealed information, including polyhexamethylene biguanide (“PHMB”).
SUMMARY
DETAILED DESCRIPTION OF INVENTION
According to a first aspect of the present invention there is provided an ink jet printing process comprising the steps (a) and (b) in any order or simultaneously:
(a) applying by means of an ink jet printer an ink to a substrate in a localised manner to form an image on the substrate; and
(b) applying to the substrate a composition comprising a binder and a polymeric biguanide which has a repeat unit of the Formula (1) or a salt thereof:
wherein:
X and Y are the same or different and represent divalent organic linking groups.
X and Y are preferably each independently optionally interrupted alkylene, more preferably optionally interrupted C
2-12
-alkylene and especially C
4-8
-alkylene; arylene, more preferably C
6-10
-arylene, especially phenylene; and aralkylene, more preferably C
7-11
-aralkylene, especially benzylene or xylylene.
When X and Y are interrupted alkylene, they are preferably interrupted by —O—, —S—, —NH—, —C(═O)— or phenylene.
Examples of preferred alkylene groups represented by X and Y include —(CH
2
)
6
, —(CH
2
)
8
—, —CH
2
CH(−)(CH
2
)
4
CH
3
, 1,4-2,3- and 1,3-butylene, 2,5-hexylene, 2,7-heptylene and 3-methyl-1,6-hexylene.
Examples of preferred interrupted alkylene groups represented by X and Y include —CH
2
C
6
H
4
CH
2
—, —CH
2
OC
6
H
4
OCH
2
—, —CH
2
OC
6
H
10
OCH
2
—, —(CH
2
)
3
O(CH
2
)
3
— and —(CH
2
)
2
S(CH
2)
2
—.
It is especially preferred that X and Y are C
4-8
-alkylene, more especially hexylene.
The nature of the terminating groups on the polymeric biguanide is not believed to be critical. However, preferred terminating groups include acyl, more preferably CH
3
CO; H; optionally substituted alkyl, more preferably optionally substituted C
1-10
alkyl; acyloxy, preferably —OC(O)(C
1-4
alkyl); halo more preferably F or Cl; cyano; optionally substituted amino; a group of the formula:
and optionally substituted phenyl. Preferred optional substituents on the terminating groups include C
1-4
-alkyl, halo (especially Cl), nitro and C
1-4
-alkoxy (especially methoxy). The terminating group at each end of the polymer may be the same or different.
The polymeric biguanide is typically in the form of a mixture of polymer chains, many or all of which are of different lengths. Preferably, the number of individual biguanide units in a polymer chain:
taken together, is from 3 to about 80.
In view of the foregoing preferences the polymeric biguanide preferably comprises one or more poly(hexamethylene biguanide) polymer chains in which the individual polymer chains, excluding the terminating groups, are of Formula (2) and salts thereof:
wherein:
n is from 2 to 40.
n is preferably from 2 to 30, more preferably from 4 to 15.
When the polymeric biguanide is a mixture of poly(hexamethylene biguanide) polymer chains of the Formula (2) it is especially preferred that the average value of n in the mixture is 12.
Preferably, the number average molecular weight of the polymeric biguanide is from 1100 to 3300.
Preferably the polymeric biguanide is in the form of a salt. Preferred salts are those with organic or inorganic acids, especially water-soluble salts, for example the hydrochloride, gluconate or acetate salt.
The polymeric biguanides may be prepared by the reaction of a bisdicyandiamide of the formula:
with a diamine of the formula H
2
N—Y—NH
2
; or by reaction between a diamine salt of dicyanimide having the formula:
with a diamine of the formula H
2
N—Y—NH
2
wherein X and Y are as hereinbefore defined.
These methods of preparation are described in more detail in GB 702,268 and GB 1,152,243 and any of the polymeric biguanides described therein may be used in the present invention.
The polymeric biguanide is preferably colourless, or substantially colourless.
The binder is preferably a polymeric binder, more preferably a water-soluble or water-dissipatable polymeric binder or a hydrophobic binder. Preferred water-soluble binders include starches, preferably hydroxy alkyl starches, for example hydroxyethylstarch; celluloses, for example celluslose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethyl methyl cellulose, carboxymethlycellulose (and salts thereof) and cellulose acetate butyrate; gelatin; gums, for example guar, xanthan gum and gum arabic; polyvinylalcohol; polyvinylphosphate; polyvinylpyrrolidone; polyvinylpyrrolidine; polyethylene glycol; hydrolysed polyvinylacetate; polyethylene imine; polyacrylamides, for example polyacrylamide and poly(N,N-dimethyl acrylamide) and polyacrylamido-2-methyl propane sulphonic acid); acrylamide-acrylic acid copolymers; polyvinylpyridine; polyvinylphosphate; vinylpyrrolidone-vinyl acetate copolymers; vinyl pyrrolidone-styrene copolymers; polyvinylamine; poly(vinyl pyrrolidonedialkylaminoalkyl alkylacrylates), for example poly vinylpyrrolidone-diethylaminomethylmethacrylate; acid-functional acrylic polymers and copolymers, for example poly(meth)acrylic acid and copolymers of (meth)acrylic acid and other (meth)acrylate monomers; amine-functional acrylic polymers and copolymers, for example polydimethylaminoethylmethacrylate; acid or amine functional urethane polymers, preferably those containing dimethylolpropanoic acid and/or pendant or terminal polyethylene glycols; ionic polymers, especially cationic polymers, for example poly (N,N-dimethyl-3,5-dimethylene piperidinium chloride); polyesters, preferably those which carry water-solubilising groups, especially sulphonic acid groups, for example polyesters obtainable by polymerising a polyol with sodiosulphoisophthalic acid.
The water-soluble binders are preferred over water-dissipatable binders due to their fast dry times and lower tendency to block the fine jets used in ink jet printers. A combination of water-soluble binders and water-dissipatable binders can also be beneficial in terms of improved mechanical strength, reduced tendency for sheets to stick together and good ink absorbency.
Preferred water-dissipatable binders are water dissipatable polymers, more preferably latex polymers, for example cationic, non-ionic and anionic styrene-butadiene latexes; vinyl acetate-acrylic copolymer latexes; acrylic copolymer latexes which carry quaternary ammonium groups, for example containing copolymerised dimethylaminoethyl (meth)acrylate; and dispersions of polyester, polyurethane, (meth)acrylate or vinyl polymers an

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