DE3907872A1 - BALANCE TEMPERATURE FOR COLOR PICTURES - Google Patents

Abstract

An agent for preventing the fading or discoloration of coloured images produced by using a color former, the agent being a transition metal salt or zinc salt of a saturated or unsaturated lower aliphatic hydroxycarboxylic acid, a saturated or unsaturated lower aliphatic dicarboxylic acid, an aromatic dicarboxylic acid or an aromatic hydroxycarboxylic acid, is added to the heat - or pressure - sensitive material containing the color former. The preferred stabilisers are Zn and Ni salts of hydroxynaphthoic acids added to heat-sensitive materials containing colour formers such as crystal violet lactone.

Description

The invention relates to a new active substance for Inhibition of fading or discoloration of images, which are colored by a color former.

Color formers are used to prepare recording materials, such as pressure sensitive recording material, heat sensitive Recording material, recording material used for laser printers and for thermal transfer. The color formers are generally excellent in color-forming ability, but have the disadvantage that the resulting Color has a low stability, and that they fade or discoloration tends when exposed to light or comes in contact with a plasticizer.

It has been attempted to overcome this disadvantage by use of 2-hydroxybenzophenone or similar ultraviolet absorbers Exclude and fading due to exposure to light to inhibit. The use of these ultraviolet absorbers However, it raises the problems that they are less effective and uneconomical because they are expensive. on the other hand became an antipyrine complex of zinc thiocyanate for protection used before fading on contact with a plasticizer;  see. JP-A 11 286/1984. However, the complex is for prevention fading due to exposure to light completely ineffective.

The invention is based on the object, a new fading inhibitor to provide that is capable of effective the fading of images through a color former are colored, both under the action of light and in contact to prevent with a plasticizer. This task will solved by the invention.

The invention relates to those characterized in the claims Items.

Examples of suitable saturated or unsaturated lower aliphatic hydroxycarboxylic acids are α- hydroxyisobutyric acid, γ- hydroxybutyric acid, citric acid, tartaric acid, lactic acid, glycolic acid and malic acid. Examples of suitable saturated or unsaturated lower aliphatic dicarboxylic acids are chloromaleic acid, maleic acid, succinic acid, 1,2-cyclopentanedicarboxylic acid, fumaric acid, methylmalonic acid and oxalic acid. Examples of suitable aromatic dicarboxylic acids are isophthalic acid, 2,3-quinolinedicarboxylic acid, chlorophthalic acid, 1,2-naphthalenedicarboxylic acid, naphthalic acid, pyridine-2,3-dicarboxylic acid, 2,3-naphthalenedicarboxylic acid, benzene tetracarboxylic acid and phthalic acid. Examples of suitable aromatic hydroxycarboxylic acids are salicylic acid, 2-hydroxyterephthalic acid, 5-hydroxy-o-toluic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-1-naphthoic acid, 3-hydroxy-2-naphthoic acid, 8-hydroxy-1 naphthoic acid, 2,4-dihydroxybenzoic acid, mandelic acid, 2,6-dihydroxybenzoic acid, 1,4-dihydroxy-2-anthraquinonecarboxylic acid, gallic acid. Of these acids, the aromatic dicarboxylic acids and the aromatic hydroxycarboxylic acids are preferred.

A transition metal salt or zinc salt of at least one the above compounds is used as the active component for  used the fade inhibitor of the invention. preferred Metals include e.g. As manganese, iron, cobalt, nickel and Zinc. Suitable salts may be both internal and intermolecular Be salts.

The term "color former" for which the fade inhibitor The invention is applicable to colorless or weakly colored basic dyes known in the art are known and which are both positive and negative Carry charges in the molecule. Examples of preferred Color formers for which the fade inhibitor of the invention is applicable, lactone-based dyes and Fluoran. Examples of lactone-based dyes are

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (common name: crystal violet lactone),
3,3-bis (p-Dimethylaminophenylphthalid)
3,3-bis [p-di (n-butylaminophenyl) phthalide],
N- [9- (2-carboxyphenyl) -6- (diethylamino) -3H-xanthen-3-ylidene] -N-ethyl-ethane-amine chloride,
3- [2-methyl-4- (diethylamino) -phenyl] -3- (1,2-dimethyl-3-indolyl) -phthalide,
3- (p-dimethylaminophenyl) -3- (1-ethyl-2-methyl-3-indolyl) -4,5,6,7-tetrachlorophthalide,
Phthalide 3,3-bis (1-ethyl-2-methylindole-3-yl),
3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide,
3- (4-morpholinophenyl) -3- (1,2-dimethylindol-3-yl) -4,5,6,7-tetrachlorophthalide,
3- (1-Benzyl-2-methyl-indol-3-yl) -8- (methyl-2-methyl-indole-3-yl) -phthalide,
5-nitro-3,3-bis (4-dimethylaminophenyl) phthalide,
5-amino-3,3-bis (4-dimethylaminophenyl) phthalide,
5-benzoylamino-3,3-bis (4-dimethylaminophenyl) phthalide,
3,3-bis (p-dimethylaminophenyl) -4,5,6,7-tetrachlorophthalide,
3,3-bis (p-diethylaminophenyl) -6-dimethylaminophthalide,
3,3-bis (p-dimethylaminophenyl) -6-aminophthalide,
3,3-bis (p-dimethylaminophenyl) -6- (p-toluenesulfonamide) phthalide,
3,3-bis (p-dimethylaminophenyl) -6-nitrophthalide,
3,3-bis (p-dimethylaminophenyl) -6-monoäthylaminophthalid,
3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide,
3,3-bis (p-dimethylaminophenyl) -6-äthoxyphthalid,
3,3-bis (p-dimethylaminophenyl) -6-diäthylaminophthalid,
3- (4-diethylaminophenyl) -3- (1,2-dimethylindol-3-yl) -naphthalide and
3- (4-diethylaminophenyl) -3- (1-phenylpyrrol-3-yl) naphthalide.

Examples of fluorine-based dyes are

3-dimethylamino-7-methoxyfluorane,
3-diethylamino-6-methoxyfluorane,
3-diethylamino-7-methoxyfluorane,
3-diethylamino-7-chlorofluoran,
3-diethylamino-6-methyl-7-chlorofluoran,
3-diethylamino-6,7-dimethylfluoran,
3-dimethylamino-7,8-benzofluoran,
3- (N-ethyl-p-toluidino) -7-methylfluoran,
3-diethylamino-7-N-acetyl-N-methylaminofluoran,
3-diethylamino-7-N-methylaminofluoran,
3-diethylamino-7-dibenzylaminofluoran,
3-diethylamino-7-N-methyl-N-benzylaminofluoran,
3-diethylamino-7-N-chloroethyl-N-methylaminofluoran,
3-diethylamino-7-N-diäthylaminofluoran,
3- (N-ethyl-p-toluidino) -6-methyl-7-phenylaminofluoran,
3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluoran,
3-diethylamino-6-methyl-7-phenylaminofluoran,
3-dibutylamino-6-methyl-7-phenylaminofluoran,
3-diethylamino-7- (2-carbomethoxyphenylamino) fluoran,
3- (N-ethyl-N-isoamyl) amino-6-methyl-7-phenylaminofluoran,
3- (N-cyclohexyl-N-methylamino) -6-methyl-7-phenylaminofluoran,
3-pyrrolidino-6-methyl-7-phenylaminofluoran,
3-piperidino-6-methyl-7-phenylaminofluoran,
3-diethylamino-6-methyl-7-xylidinofluoran,
3-diethylamino-7- (o-chlorophenylamino) fluoran,
3-dibutylamino-7- (o-chlorophenylamino) fluoran,
3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran,
3- (N-methyl-Nn-amyl) amino-6-methyl-7-phenylaminofluoran,
3- (N-ethyl-Nn-amyl) amino-6-methyl-7-phenylaminofluoran,
3- (N-methyl-Nn-hexyl) amino-6-methyl-7-phenylaminofluoran,
3- (N-ethyl-N, N-hexyl) amino-6-methyl-7-phenylaminofluoran and
3- (N-ethyl-N- β- ethylhexyl) -amino-6-methyl-7-phenylaminofluoran.

These color formers stain in the presence of a color developing agent under normal conditions, such as heating or exerting from pressure. Useful color developing agents are the usually for developing in contact with above colors Used color formers. Examples of preferred Color developing agents are bisphenol A, 4,4'-cyclohexylidenediphenol, Benzyl p-hydroxybenzoate, dimethyl 4-hydroxyphthalate and 4-hydroxy-4'-isopropoxydiphenylsulfone.

For practical use, the fade inhibitor of the invention preferred in the preparation of the recording material in an appropriate amount added to the color former. The used bleach inhibitor may be the one used by the Dye image color effectively prevents bleaching or discoloration due to exposure to light or Protect contact with a plasticizer. The used amount the fade inhibitor is not particularly critical. you depends on the type of active component, the Color former and from the period over which the inhibitory effect is to be maintained. A suitable Amount of inhibitor used is about 0.5 to 300 parts by weight per 100 parts by weight of the color former.

The fade inhibitor of the invention may be used for the manufacture of recording material, such as heat-sensitive recording material, pressure-sensitive recording material, Thermal transfer recording material and recording material used for laser printers as follows.  

For the preparation of the material is usually a binder, such as polyvinyl alcohol, hydroxyethyl cellulose, styrene Maleic anhydride copolymer or styrene-butadiene copolymer, dispersed in water. Then a color former, a color developing agent and the fade inhibitor of Invention added simultaneously or separately to the dispersion, and the mixture is treated with a stirrer, such as a ball mill, a grinder or a sand mill, dispersed a coating composition is produced. The resulting coating composition is applied to a substrate, such as paper, plastic film or synthetic paper applied and results on it a recording layer. If necessary, you can the color former and other components prior to manufacture the coating composition are enclosed in microcapsules. The coating composition may, if necessary, further Excipients contain, for. A dispersant, a sensitizer, an ultraviolet absorber, an antifoam, a dye, a detackifier or an inorganic Pigment. In general, however, when using the Invention an ultraviolet absorber in the coating composition not mandatory.

The fade inhibitor of the invention protects images, which are colored by a color former, excellent before fading or discoloring due to exposure to light or contact with a plasticizer, such as diisobutyl adipate, Dioctyladipinate or similar aliphatic, divalent Ester or dibutyl phthalate, di-2-ethylhexyl phthalate or similar phthalates. The invention further provides a method to protect images through a color former colored before fading by using the fade inhibitor the invention. The active component of the Bleach inhibitor of the invention is lightweight and inexpensive produce and makes the expensive ultraviolet absorber superfluous. It is therefore also economically advantageous.  

The examples and comparative examples illustrate the invention without restricting it. In the examples and comparative examples the proportions are parts by weight, provided that not otherwise stated.

Example 1

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide having a low photostability is dissolved as a typical color former in dimethylsulfoxide to a concentration of 8 × 10 ^-3 mol / l. Then, a compound to be tested is dissolved in the solution to a concentration of 1 × 10 ^-4 mol / l. 54.8 mg bisphenol A are added to 10 ml of the solution. Then the mixture is heated for color development for 1 hour. 10 μl of the colored mixture are applied dropwise to a cellulose plate for thin layer chromatography and dried.

The resulting spot is then irradiated externally with light ( λ <300 nm, 100 W high-pressure mercury vapor lamp) for 3 hours without a filter.

After irradiation, the stain is stained using a organic solvent subjected to chromatography, and the amount of undecomposed dye is measured with a chromatoscanner (Shimadzu Corporation), where the percentage Decomposition is determined. The results are in summarized in Table I below.  

Table I

example 2

A heat-sensitive recording sheet becomes as follows prepared using the fading inhibitor of the invention.

1. Preparation of the solution A

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide 10 parts 10 wt .-% aqueous solution of polyvinyl alcohol 30 parts water 105 parts

The components are dispersed in a ball mill.  

2. Preparation of solution B

Zinc salt of 1-hydroxy-2-naphthoic acid 30 parts 10 wt .-% aqueous solution of polyvinyl alcohol 30 parts water 70 parts

The components are dispersed in a ball mill.

3. Preparation of solution C

Bisphenol A 30 parts 10 wt .-% aqueous solution of polyvinyl alcohol 30 parts water 70 parts

The components are dispersed in a ball mill.

4. Preparation of the recording layer

A liquid coating composition is prepared by mixing 145 parts solution A, 43 parts solution B, 87 parts solution C, 30 parts of silica pigment (oil absorption: 180 ml / 100 g), 30 parts of a 10 wt .-%, aqueous solution of polyvinyl alcohol and 175 parts of water and stirring the mixture manufactured.

The liquid coating composition thus obtained is treated with a Flushing roller in an amount of 5.3 g / m² (after drying) weighing on an uncoated sheet of paper 50 g / m² applied and dried, being a heat-sensitive Recording sheet is created.  

example 3

A heat-sensitive recording sheet becomes as in Example 1, but with an equal amount of 3- (4- Diethylaminophenyl) -3- (1-ethyl-2-methylindole-3-yl) phthalide in place of 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide is used for the preparation of solution A.

example 4

A heat-sensitive recording sheet becomes as in Example 1, but with an equal amount of 3-dimethylamino 7,8-benzofluorane instead of 3,3-bis (p-dimethylaminophenyl) - 6-dimethylaminophthalide for the preparation of solution A is used.

Comparative Example 1

A heat-sensitive recording sheet becomes as in Example 2, but without solution B, prepared.

Comparative Example 2

A heat-sensitive recording sheet becomes as in Example 3, but without solution B, prepared.

Comparative Example 3

A heat-sensitive recording sheet becomes as in Example 4, but without solution B, prepared.

Six types of heat-sensitive recording sheets, those in Examples 2 to 4 and Comparative Examples 1 to 3 are tested for light resistance. The color of the recording sheets will be among the following Conditions developed: temperature 150 ° C; Pressure 2 kg / cm²; Contact time 1 second. The colored areas are with  Light (300 W high-pressure mercury vapor lamp) over a certain Time irradiated without using a filter.

Macbeth densitometer RD-918 (Macbeth Co., Ltd.) becomes Determination of color density used. The color is in the sense a reflection density (optical density) against time evaluated, and the percent bleaching is after the given the following equation.

The results are listed in Table II below.

Table II

Fig. 1 shows the difference of the results in Table II, between Example 2 and Comparative Example 1.

Subsequently, the recording sheets, which are in the Examples 2 to 4 and Comparative Examples 1 to 3 be tested for plasticizer resistance. The color of the Recording sheets are developed as above. The Leaves are then covered with a layer of polyvinyl chloride, containing 50% by weight of diisobutyl adipate as plasticizer,  coated. The relationship between time and density The images (optical density) are mixed with a Macbeth Densitometer RD-918 evaluated, and the percent bleaching is determined.

The results are summarized in Table III below.

Table III

Fig. 2 shows the difference of the results between Example 2 and Comparative Example 1 in comparison.

Examples 5 and 6

Heat sensitive recording sheets become as example 2, but with an equal amount of zinc salt of 2-hydroxy-3-naphthoic acid (in Example 5) or Nickel salt of 2-hydroxy-3-naphthoic acid (in Example 6) for Preparation of Solution B in Example 2 is used.

The recording sheets obtained in Examples 5 and 6 Become as above on the light resistance tested. The results are shown in Table IV below listed.  

Table IV

Claims (11)

1. Use of a transition metal salt or zinc salt of at least one saturated or unsaturated lower one aliphatic hydroxycarboxylic acid, a saturated or unsaturated lower aliphatic dicarboxylic acid, an aromatic dicarboxylic acid or an aromatic Hydroxycarboxylic acid to prevent bleaching or coloring pictures that come with a Color former are colored. 2. The embodiment of claim 1, wherein a transition metal salt or zinc salt of at least one aromatic Dicarboxylic acid or aromatic hydroxycarboxylic acid used becomes. 3. The embodiment of claim 1 or 2, wherein the transition metal Manganese, iron, cobalt or nickel is. 4. The embodiment of claim 1 to 3, wherein the color former a lactone-based dye or a dye is fluoran based. 5. Coating composition for color recording material containing a binder, a color former, a color developing agent, a fade inhibitor and optionally usual auxiliaries, characterized that the fade inhibitor is a transition metal salt or Zinc salt of at least one saturated or unsaturated lower aliphatic hydroxycarboxylic acid, a saturated or unsaturated lower aliphatic Dicarboxylic acid, an aromatic dicarboxylic acid or an aromatic hydroxycarboxylic acid.   6. A composition according to claim 5, wherein the fading inhibitor a Transition metal salt or zinc salt of at least one aromatic dicarboxylic acid or aromatic hydroxycarboxylic acid is. 7. A composition according to claim 5 or 6, in which the transition metal Manganese, iron, cobalt or nickel is. 8. A composition according to claim 5 to 7, in which the color former Lactone-based dye or a dye Fluoranebase is. 9. Method of protection against fading or discoloration of Illustrations that are colored with a color former, wherein the coating composition used to make the image adding a fade inhibitor, characterized in that as a fading inhibitor a transition metal salt or zinc salt of at least a saturated or unsaturated lower aliphatic Hydroxycarboxylic acid, a saturated or unsaturated lower aliphatic dicarboxylic acid, a aromatic dicarboxylic acid or an aromatic hydroxycarboxylic acid used. 10. The method according to claim 9, characterized in that the fading inhibitor in an amount of 0.5 to 300 parts by weight per 100 parts by weight of the color former used. 11. Active substance for preventing fading or discoloration of pictures colored with a color former are consisting of a transition metal salt or zinc salt of at least one saturated or unsaturated lower aliphatic hydroxycarboxylic acid, a saturated or unsaturated lower aliphatic dicarboxylic acid, an aromatic dicarboxylic acid or a aromatic hydroxycarboxylic acid.