NL8900585A - A FADING BRAKING SEAL FOR A COLOR SHAPER. - Google Patents

Description

893015 / TK / HH

A fading inhibiting compound for a color former.

Inventors mentioned by Applicant are Teijiro Kitao, and Hironori Oda.

The invention relates to a new agent for inhibiting the blurring or decolorization of images with a color obtained by a color former.

Color formers have been used to produce recording materials such as pressure sensitive recording materials, heat sensitive recording materials, laser printer and heat transfer recording materials, etc. The color formers are generally excellent in color forming ability and the like, but have the drawback that the color obtained has low stability and tends to fade or discolour when exposed to light or after contact with a plasticizer.

Attempts have been made to overcome this drawback by using 2-hydroxybenzophenone or the like ultraviolet absorbents to inhibit fading by exposure to light. However, the use of these ultraviolet absorbers has resulted in poor effects being produced and uneconomical in that they are expensive. On the other hand, an antipyrine complex of zinc thiocyanate has been used to prevent fading by contact with a plasticizer (e.g., Japanese Unexamined Patent Application No. 11286/1984). However, the complex is completely ineffective in preventing fading from exposure to light.

The present invention aims to provide a new fading inhibiting compound that prevents fading of images with a color obtained by a color former.

Another object of the invention is to provide a new fade inhibitory compound which effectively fades images with a color obtained by a color former or by 8900585 '.

-2- 4 exposure to light or through contact with a plasticizer may occur.

Other objects and features of the invention will become more apparent from the following description.

The invention provides an agent for preventing fading or decolorization of images having a color obtained with a color former, the agent consisting essentially of a transition metal salt or zinc salt of at least one compound selected from the group consisting of saturated or unsaturated lower aliphatic hydroxycarboxylic acids, saturated or unsaturated lower aliphatic dicarboxylic acids, aromatic dicarboxylic acids and aromatic hydroxycarboxylic acids, and a method of preventing fading or decolorization of images having a color obtained with a color former, and characterized in that the method comprises adding the agent to the color former.

In order to overcome the drawback of the prior art, extensive research has been conducted to develop a new and effective fade inhibiting compound that can prevent fading or decolorization of images having a color obtained with a color former. Research showed that the above-mentioned compounds can obtain an excellent inhibitory action against fading or decolorization by exposure to light or by contact with a plasticizer.

The present invention is based on this new finding.

Examples of useful saturated or unsaturated lower aliphatic hydroxycarboxylic acids are (X-oxyisobutyric acid, oxy -oxybutyric acid, citric acid, tartaric acid, lactic acid, glycolic acid, malic acid, etc. Examples of useful saturated or unsaturated lower aliphatic dicarboxylic acids are chloromalei. neic acid, maleic acid, succinic acid, 1,2-cyclopentanedicarboxylic acid, fumaric acid, methylmalonic acid, oxalic acid, etc. Examples of useful aromatic dicarboxylic acids are isophthalic acid, 2,3-quinolin dicarboxylic acid, 89 00 5 85 -3-chlorophthalic acid, 1,2-naphthalenedicarboxylic acid, naphthalic acid, pyridine-2,3-dicarboxylic acid, 2,3-naphthalenedicarboxylic acid, benzene tetracarboxylic acid, phthalic acid, etc. Examples of useful aromatic hydroxycarboxylic acids are salicylic acid, 5 2-oxyterephthalic acid, 5-oxy-o-toluic acid, 1-oxy-2-naphthoic -acid, 2-oxy-1-naphthoic acid, 3-oxy-2-naphthoic acid, 8-oxy-1-naphthoic acid, 2,4-dioxybenzoic acid, mandelic acid, 2,6-dioxy-benzoic acid, 1,4-dioxy-2 - anthraquinone carboxylic acid, gallic acid, etc. Van these acids are preferred aromatic dicarboxylic acids, aromatic hydroxycarboxylic acids and the like.

A transition metal salt or zinc salt of at least one of the compounds is used as the active ingredient for the fade-inhibiting compound of the invention. Preferred metals are, for example, manganese, iron, cobalt, nickel, zinc, etc. Useful salts can be any of the internal salts and intermolecular salts.

The term "color former" as used herein for which the fade-inhibiting compound of the invention may be used refers to colorless or light-colored basic dyes commonly used in the art and capable of carrying both positive and negative charges in the molecule. Preferred examples of color formers for which the fading inhibiting compound of the invention may be used are lactone-based dyes, fluorane-based dyes, etc. Examples of lactone-based dyes are 3,3-bis (p-dimethylaminophenyl) - 6-dimethylaminophthalide (known name: crystal violet lactone), 3,3-bis (p-dimethylaminophenylphthalide), 3,3-bis [p-di (n-butyl-30-aminophenyl) -phthalide, N-j9- (2 -carboxyphenyl) -6- (diethylamino) -3H-xanthen-3-ylidene -N-ethyl ethanolamine 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, 3,3-bis (1-ethyl-2- 35-methylindol-3-yl) phthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methyl-indol-3-yl) phthalide, 3- (4-morpholinophenyl) -3- (1,2 -dimethylindol-3-yl) -4,5,6,7-tetrachlorophthalide, 3- (1-benzyl-2-methylindol-3-yl) -8- (methyl-2-methylindol-3-yl) phthalide ., 5-8900585.

-4- * 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-dimethyl 5-aminophthalide, 3,3-bis (p-dimethylaminophenyl) -6 aminophthalide, 3,3-bis (p-dimethylaminophenyl) -6- (p-tolluene sulfonamide) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-nitrophthalide, 3,3-bis (p-dimethylaminophenyl) -6-monoethylamino phthalide, 3 , 3-bis (p-dimethylaminophenyl-6-chlorophthalide, 3,3-bis (p-dimethylaminophenyl) 10 -6-ethoxyphthalidef 3,3-bis (p-dimethylaminophenyl) -6-diethyl aminophthalide, 3- (4 -diethylaminophenyl) -3- (1,2-dimethylindole -3-yl-naphthalide, 3- (4-diethylaminophenyl) -3- (1-phenylpyrrol -3-yl) naphthalide, etc. Examples of fluoro-based dyes are 3-dimethylamino -7-methoxyfluoroan, 3-15 diethylamino-6-methoxyfluoroan, 3-diethylamino-7-methoxy-fluorane, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethyla mino-6,7-dimethyl-fluoran, 3-dimethylamino-7,8-benzofluoran, 3- (N-ethyl-p-toluidino) -7-methylfluoran, 3-diethylamino-7-N-acetyl-N-20 methyl aminofluorane , 3-diethylamino-7-N-methylaminofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-N-methyl-N-benzylaminofluoran, 3-diethylamino-7-N-chloroethyl -N-methylaminofluorane, 3-diethylamino -7-N-diethylamino-fluoro, 3- (N-ethyl-p-toluidino) -6-methyl-7-phenylamino-25 fluoro, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluoro, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino -7- (2-carbomethoxyphenylamino) fluoro, 3- (N-ethyl -N-isoamyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-cyclohexyl-N-30-methylamino) -6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3- piperidino-6-methy1-7-phenylaminofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 3-diethylamino-7- (o-chlorophenylamino) fluoro, 3-dibutyl-amino-7- (o-chlorophenylamino) - fluorane, 3-pyrrolidino-6-35 m ethyl 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-Nn-hexyl) 89 00585. -5-p amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-ethylhexyl) amino-6-methyl-7-phenylaminofluorane, etc.

These color formers are allowed to impart a color in the presence of a color developing agent by conventional means such as heating, printing or the like. Useful color developing agents can be those commonly used to develop colors by contact with the color former.

Preferred examples of color developing agents are bisphenol A, 4,4'-cyclohexylidene diphenol, benzyl p-hydroxybenzoate, dimethyl-4-hydroxyphthalate, 4-hydroxy-4'-isopropoxy diphenyl sulfone, etc.

When used, the fading inhibitor of the invention is preferably added in an appropriate amount to a color former for the manufacture of the recording materials. The fading inhibiting compound used can effectively prevent images of color given by the dye from fading or decolorization by exposure to light or by contact with a plasticizer. The amount of the fading inhibitory compound employed can be suitably determined without specific limitation depending on the nature of the active ingredient, type of color former, time period to maintain the inhibitory effect, etc.

A suitable amount of the inhibitory compound used is about 0.5 to about 300 parts by weight per 100 parts by weight of color former.

For example, the fading inhibiting compound of the invention is applied to the following methods for the production of recording materials such as heat sensitive recording materials, pressure sensitive recording materials, heat transfer recording materials, laser printer recording materials, etc. In the manufacture thereof, usually a binder such as polyvinyl alcohol, hydroxyethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer or the like dispersed in water. Thereafter, a color former, a color developing agent, and the fading inhibitor are added 8900585.

The compound of the invention is added simultaneously or separately to the dispersion, and the mixture is dispersed with a stirrer such as a ball mill, grinder, sand mill or the like, to form a coating composition. The obtained coating composition is applied to a substrate, such as paper, plastic film, synthetic paper or the like, to form a recording layer thereon. If required, the color former and other ingredients can be contained in microcapsules prior to the manufacture of the coating composition.

The coating composition may further contain adjuvants, if required, containing, for example, a dispersant, a sensitizer, ultraviolet absorber, antifoaming agent, colorant, anti-adhesive, inorganic pigment, and the like. Usually, however, an ultraviolet absorbent need not be included in the coating composition when practicing the invention.

According to the invention, a particular fading inhibiting compound is offered which can excellently prevent the images having a color imparted by a color former from fading or decolorization by exposure to light or by contact with a plasticizer such as diisobutyl adipate, dioctyl adipate or the like ali -phatic dibasic esters, or dibutyl phthalate, di-2-hexyl-25 phthalate or the like phthalates. According to the invention, a special method is also offered which prevents images having a color obtained with a color former from fading by using the fading inhibiting compound according to the invention. The active ingredient for the fade-inhibiting compound of the invention is easy and inexpensive to prepare, and obviates the need for expensive ultraviolet absorbers, and is therefore clearly cost effective.

The invention will be further described by the following examples and comparative examples. However, the invention is not limited to the examples. In the examples and comparative examples, all parts are 89 00585. " % To 7 parts by weight unless otherwise indicated.

Example I

3,3-Bis (p-dimethylaminophenyl) -6-dimethylamino-5-phthalide with low light stability and used as a typical color former was dissolved in dimethyl sulfoxide to 3 at a concentration of 8 x 10 mol / liter. A test compound was dissolved in the solution to a concentration of 1 x 10 4 mol / liter. An amount of 54.8 mg bisphenol A was added to 10 ml of the solution, then the mixture was heated for 1 hour to color. 10 µl of the colored mixture was added dropwise to a cellulose plate for thin layer chromatography and dried.

Thereafter, the resulting spot was externally irradiated with light (> 300 nm, using a 100W high pressure mercury vapor lamp) for 3 hours without using a filter.

After irradiation, the spot was subjected to chromatography using an organic solvent and the amount of unreacted colored dye was determined with a chromatograph (manufactured by Shimadzu Corporation) to obtain the conversion percentage (%).

25 Table A below shows the results.

30 35 8900585. " -8-

TABLE A

Test connection conversion ~ TT ratio _Structure _____ (%) _

Ni 46 formula 1

Zn 66 formula 2 Z n 7 3 HOCH2COOM1 / 2 Ni 0

Ni 17 formula 3 Λ Λ

Zn 20

Ni 16 formula 4

Zn 31 formula 5 Zn 66 89 005 85. "-9- TABLE A (continued) * _Pr ect compound_ conversion ratio _ Structure __ (¾) _ formula 6 Zn 15 NI 0 formula 7

Zn 22 formula 8 N I 0

Ni 36 formula 9 ^

Zn 5 0 formula 10 Zn 3 7 formula 11 Zn 15 8900585.

-10- TABLE A (continued)

Test compound_ conversion w ratio _Structure_ iVJ · (%) 5 formula 12 Z n 2 2 10 (blank) g4

Example II

A heat sensitive recording paper sheet was prepared in the following manner using the fade inhibiting compound of the present invention.

(1) Preparation of solution A.

3,3-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide 10 parts 25 10 wt% aqueous solution of polyvinyl alcohol 30 parts

Water 105 parts

These ingredients were dispersed with a ball mill.

(2) Preparation of solution B.

Zinc salt of 1-hydroxy-2-naphthoic acid 30 parts 35 10 wt% aqueous solution of polyvinyl alcohol 30 parts 6900585.

3 -11-

Water 70 parts

These ingredients were dispersed with a ball mill.

5 (3) Preparation of solution C.

Bisphenol A 30 parts 10 wt% aqueous solution of polyvinyl alcohol 30 parts

Water 70 parts

These ingredients were dispersed with a ball mill.

(4) Formation of a recording layer.

A liquid coating composition was prepared by adding 145 parts of solution A, 43 parts of solution B, 87 parts of solution C, 30 parts of silica pigment (oil-2q absorption: 180 ml / 100 g), 30 parts of 10 wt% aqueous solution of polyvinyl alcohol and 175 parts of water and stirring the mixture.

The thus obtained liquid coating composition was applied in an amount of 5.3 g / m (m-2 ^ if dried) on an uncoated paper sheet weighing 50 g / m 2 with a roller coater and dried, forming of a heat sensitive recording paper sheet.

Example III

2Q A heat-sensitive recording paper sheet was formed in the same manner as in Example I except using the same amount of 3- (4-diethylamino-phenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide in instead of 3,3-bis (p-dimethylaminophenyl) 6-dimethylaminophthalide which has been used for the preparation of solution A.

Example IV

A heat sensitive recording paper sheet was

89 00585 .V

-12- formed in the same manner as in Example I, except using the same amount of 3-dimethyl-amino-7,8-benzofluorane instead of 3,3-bis (p-dimethyl-aminophenyl) -6- dimethylamino phthalide used for the preparation of solution A.

Comparative example 1

A heat-sensitive recording paper sheet was formed in the same manner as in Example II, with the exception of not using solution B.

Comparative example 2

A heat-sensitive recording paper sheet was formed in the same manner as in Example III, with the exception of not using solution B.

Comparative example 3

A heat-sensitive recording paper sheet was formed in the same manner as in Example IV, with the exception of not using solution B.

Six types of heat-sensitive recording paper sheets obtained in Examples II to IV and Comparative Examples 1 to 3 were tested for light resistance. More specifically, these recording paper sheets were each allowed to develop a color under the following conditions: temperature of 150 ° C, pressure of 2 kg / cm 2 and touch duration of 1 sec. The colored parts were irradiated with light (using a 300 W high pressure mercury vapor lamp) for a certain period of time without using a filter.

Macbeth densitometer RD-918 (manufactured by Macbeth Co., Ltd.) was used to determine the density of the color. The color was rated over time based on the reflection density (optical density), and the fading percentage was given according to the following equation: 89 00585.

-13- 4

Fade Percentage (%} = (Original Density Density Over Time) ^ Original Density _ Table B below shows the results.

D

TABLE B

Irradiation time 28 hours 65 hours 89 hours 115 hours 10 _; _: ___ fade percentage (%)

Example II 0 11.0 14.0 14.0

Example III 0 0 0.5 1.8 15 Example IV 5.9 16.1 16.9 17.8

Comparative example 1 18.2 45.2 58.2 66.4

Comparative example 2 19.0 43.8 44.2 44.6 20 Comparative example 3 17.3 35.6 46.2 53.8

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

Then, the recording paper sheets obtained in Examples II to IV and Comparative Examples 1 to 3 were tested for plasticizer resistance.

More specifically, the recording paper sheets were each developed to develop a color in the same manner as above and applied to a polyvinyl chloride film containing 50% by weight diisobutyl adipate as a plasticizer. The relationship between the time course and the density (optical density} of images was determined with the Macbeth densitometer RD-918, and the fading percentage was determined.

Table C below shows the results.

8900585.

-14-

TABLE C

Time lapse 2 hours 6 hours 10 hours 22 hours 5 --- '

Blur rate (%)

Example II 4.5 6.0 6.1

Example III 0 2.9 5.9 11.0

Example IV 3.4 6.7 8.1 8.7

Comparative example 1 40.0 60.0 67.2 69.6

Comparative example 2 45.0 62.2 65.8 66.7

Comparative example 3 50.0 62.7 70.4 73.2 15 _________

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

20

Examples V and VI

Heat-sensitive recording paper sheets were formed in the same manner as in Example II, except using the same amount of zinc salt of 2-hydroxy-3-naphthoic acid (in Example V) or the nickel salt of 2-hydroxy-3-naphthoic acid (in Example VI) for preparing solution B of Example II.

The recording paper sheets obtained in Examples V and VI were examined for the light resistance in the same manner as above with the results shown below in Table D.

900585.

35 -15-

TABLE D

Irradiation duration 28 hours 65 hours 89 hours 119 hours

Blur rate (%)

Example V 9.7 16.2 20.7 24.1

Example VI 0 2.4 5.1 7.2 8900585

Claims (6)

A means for preventing fading or decolorization of images having a color obtained with a color former, the agent consisting essentially of a transition metal salt or zinc salt of at least one compound selected from the group consisting of saturated or unsaturated lower aliphatic hydroxycarboxylic acids, saturated or unsaturated lower aliphatic dicarboxylic acids, aromatic dicarboxylic acids and aromatic hydroxycarboxylic acids. Agent according to claim 1, characterized in that the agent consists essentially of a transition metal salt or zinc salt of at least one compound selected from the group consisting of aromatic dicarboxylic acids and aromatic hydroxycarboxylic acids. Agent according to claim 1, characterized in that the transition metal is manganese, iron, cobalt or nickel. Agent according to claim 1, characterized in that the color former is a lactone-based dye or a fluorane-based dye. A method for preventing fading or decolorization of images having a color obtained with a color former, characterized in that the method comprises adding to the color former an agent as defined in claim 1. A method according to claim 5, characterized in that the amount of the agent to be added is about 0.5 to about 300 parts by weight per 100 parts by weight of the color former. 30 35 S9 00585.