JPS6311996B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to pressure-sensitive copying paper, and in particular to pressure-sensitive copying paper that does not cause coloring of the copying paper itself or discoloration of copied prints when exposed to sunlight or fluorescent light. Regarding. Usually, pressure-sensitive copying paper is coated on one side of a support with a color-forming agent microcapsule composition whose main component is microcapsules containing oil droplets in which an electron-donating organic coloring agent (hereinafter simply referred to as coloring agent) is dissolved. A coloring agent composition containing an electron-accepting coloring agent (hereinafter simply referred to as a coloring agent) as a main component that changes color when it comes into contact with the coloring agent is applied to the upper paper and one side of the support, On the other side, there is an inner paper coated with a color former microcapsule composition and a lower paper coated with a color former composition on one side of the support. It has been put into practical use as a copy set by combining the paper and the bottom paper in that order. Further, self-coloring pressure-sensitive copying paper, in which a coloring agent and a coloring agent are coated on the same side of a support and which allows pressure-sensitive recording on a single sheet, is well known as a form of pressure-sensitive copying paper. Coloring agents for such pressure-sensitive copying paper include triallylmethane compounds, diphenylmethane compounds,
Various compounds such as xanthene compounds, thiazine compounds, and spiropyran compounds are known, but the color formers obtained by contact reaction of these color formers with color formers generally do not react with sunlight or fluorescent light. When exposed to light, the color density tends to decrease or the color tone changes easily, resulting in poor printing light resistance. In particular, xanthene compounds have poor light resistance, and for example, fluoran dyes such as those exemplified in U.S. Pat. It forms a black-green image by reacting with the ink, but the light resistance of the print is extremely poor and the color changes to red. In addition, in the case of a color former layer containing a fluoran dye, the color former layer itself is colored red by irradiation with sunlight, etc. (hereinafter referred to as CB surface coloring).
Then, copying is performed using a color former layer that has been irradiated with sunlight etc. (hereinafter referred to as printing after CB surface light resistance)
It has defects such as only being able to obtain colored images with a reddish tinge. In view of the current situation, the inventors of the present invention have found that even when using the above-mentioned xanthene compounds as a coloring agent, especially fluoran dyes which have extremely poor light resistance, the printing has excellent light resistance, does not color the CB surface, and has the ability to print on the CB surface. The present invention was completed as a result of extensive research into pressure-sensitive copying paper that does not change color after being exposed to light. The present invention provides a pressure-sensitive copying paper using microcapsules encapsulating a nonvolatile organic solvent containing a coloring agent, in which the organic solvent contains 0.2 to 10 parts by weight of an alkylphenol compound per 100 parts by weight of the organic solvent. This is a pressure-sensitive copying paper that is characterized by its tightness. The alkylphenol compounds used in the present invention are phenols and derivatives thereof in which at least one of the 2nd and 6th positions is substituted with an alkyl group, an alkylene group, or a hydroxyl group. Specifically, the following compounds are exemplified. 2,6-
Dimethylphenol, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4-methylphenol, 3-methyl-6-tert-butylphenol,
2,4-di-tert-butylphenol, 2-5-di-tert-butyl-4-methylphenol, 2,6-
di-tertbutyl-4oxymethylphenol,
2,4,6-tri-tert-butylphenol, 2,
4,6-tri-dimethylaminomethyl-phenol, 2-butyl-4-methoxyphenol, 2,
6-di-tert-butyl-4-ethylphenol,
2,4-dimethyl-6-tertbutylphenol,
2,4-dimethyl-6-(2'-methylcyclohexyl)phenol, catechol, 4-tert-butylcatechol, 4,6-di-tert-butylresorcin, 2-tert-butylhydroquinone, 2,6-di-
tert-butylhydroquinone, 2,6-di-tert-amylhydroquinone, 2,2'-methylenebis(4-methyl-6-tertbutylphenol), 2,2'-methylenebis(4-ethyl-6-tertbutylphenol), 2,2'-methylenebis(4,6-di-tertbutylphenol), 4,4'-methylenebis(3-
Methyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(2-methyl-6-
tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,
4'-propylidene bis(2,6-di-tert-butylphenol), 4,4'-isopropylidene bis(2,6-di-tert-butylphenol), 4,4'-
Cyclohexylidene bis(2,6-di-tertbutylphenol), 4,4'-bis(2,6-di-tert
butylphenol), 4,4'-bis(2-tertbutylphenol), 2,2'-methylenebis[6-(α
-methylcyclohexyl)-4-methylphenol], 4,4'-thiobis(3-methyl-6-tertbutylphenol), 4,4'-thiobis(2,6-
di-tert-butylphenol), 4,4'-thiobis(2-methyl-6-tert-butylphenol), 2,
2'-thiobis(4-methyl-6-tertbutylphenol), 2,2'-thiobis(4,6-di-tertbutylphenol), 2,2'-thiobis(4,6-
di-tertbutylresorcin), 1,1'-thiobis(2-naphthol), 1,3,5-trimethyl-
2,4,6-tris(3,5-di-tertbutyl-
4-hydroxybenzyl)benzene, 1,1,3
-Tris(5-tertbutyl-4-hydroxy-2
-methylphenyl)butane, 1,3,5-tris(3,5-di-tertbutyl-4-hydroxybenzyl)isocyanurate, octadecyl-3-
(3,5-di-tertbutyl-4-hydroxyphenyl)propionate, 6-(4-oxy-3,
5-di-tertbutylanilino)-2,4-bis(n-octylthio)-1,3,5-triazine,
(4-oxy-3,5-di-tertbutylbenzyl)
Ethyl phosphate, (4-oxy-3,5-
di-tertbutylbenzyl) octadecyl phosphate, tetrakis-[methylene (3,5-di-
tertbutyl-4-hydroxyphenyl)propionate]methane, 2,2'-thiodiethylbis[3
-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide), 1,6- Hexanediol bis-3-(3,5-di-tertbutyl-hydroxyphenyl)propionate and the like. Among these alkylphenol compounds, especially
2,6-di-tertbutyl-4-methylphenol, 4-tertbutylcatechol, 2,2'-methylenebis(4-methyl-6-tertbutylphenol), 2,2'-methylenebis(4-ethyl-6 −
tertbutylphenol), 4,4'-thiobis(3-
Methyl-6-tert-butylphenol) is effective even when added in small amounts, so it does not impair the stability of the microcapsule oil system and improves the light resistance of printing.
It is more preferably used because it provides a good balance of the three effects of preventing discoloration on the CR surface and preventing discoloration of printing after light-fastening on the CB surface. In the present invention, the alkylphenol compound is an organic solvent containing a color former.
It is generally added in an amount of 0.2 to 10 parts by weight, preferably 0.5 to 6 parts by weight, per 100 parts by weight.
Adding too much is not only economically disadvantageous but also undesirable because it impairs the stability of the microcapsule oil system. The present inventors decided to add at least one compound represented by the following general formula () or () as a second component in addition to the above-mentioned alkylphenol compound into an organic solvent containing a color former. Therefore, it has been found that the three effects of improving light resistance, which are the objectives of the present invention, can be further enhanced. (In the formula, R ₁ , R ₂ , and R ₃ each represent a C ₄ to C ₂₀ alkyl group, a phenyl group, or a C ₇ to _{C 20} alkyl phenyl group.) (In the formula, R ₄ and R ₅ each represent a C ₁ to _{C 6} alkylene group, and R ₆ and R ₇ each represent a C ₈ to _{C 22} alkyl group.) Phosphous acid represented by the general formula () Among tolyalkyl ester compounds, compounds particularly preferably used in the present invention include tris(nonylphenyl) phosphite, di(nonylphenyl)-dinonylphenyl phosphite, diphenyl-isooctyl phosphite, and diphenyl-isodecyl phosphite. , triisooctyl phosphite, triisodecyl phosphite, and the like. Furthermore, among the dialkyl ester derivatives of thioether represented by the general formula (), compounds particularly preferably used in the present invention include:
Dilaurylthiodipropionate, dimyristylthiodipropionate, dicetylthiodipropionate, ditridecylthiodipropionate, laurylstearylthiodipropionate, distearyl-β・β′-thiodibutyrate, 3-carboxylate Examples include lauryloxyethyl-4'-carborauryloxypropyl thioether and 4-carbostearyloxypropyl-5'-carborauryloxybutyl thioether. In the present invention, at least one of the above-mentioned phosphorous acid trialkyl ester compounds or thioether derivatives is used in combination with an alkylphenol compound, and for example, both of them can be used together, and furthermore, each of the different types can be used together. Of course, it is also possible to use the compounds together. The amount of these second component compounds to be used is generally determined by the type of alkylphenol compound that is the first component, but is 0.2 to 8 parts by weight per 100 parts by weight of the organic solvent containing the color former. It is desirable to use within the range of parts by weight. Furthermore, in the present invention, in addition to the alkylphenol compound and the phosphorous acid trialkyl ester compound or thioether derivative as the second component substance, examples of third component substances such as p-benzquinone, α-naphthoquinone, β-naphthoquinone, anthraquinone, etc. quinones, nickel dibutyldithiocarbamate, α-tocopherol, 1,
It has also become clear that the effect of improving the light resistance of the present invention can be further enhanced by simultaneously adding one or more compounds such as 1-diphenyl-2-picrylhydrazyl into an organic solvent. Among these third component substances, quinones and nickel dibutyldithiocarbamate are particularly effective, and the amount of these third component substances used is 0.1 to 100 parts by weight of the organic solvent.
Preferably, 3.0 parts by weight is added. The dye used in the present invention is not particularly limited, but the following specific examples may be mentioned. 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide (hereinafter referred to as crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)phthalide, 3
-(p-dimethylaminophenyl)-3-(1,2
-dimethylindol-3-yl)phthalide, 3
-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p
-dimethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-
Dimethylaminophthalide, 3,3-bis(1,2
-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide, 3,3-bis(2-phenylindole) -3-yl)-5-dimethylaminophthalide, 3
Triallylmethane compounds such as -p-dimethylaminophenyl-3-(1-methylpyrrol-2-yl)-6-dimethylaminophthalide. 4,4'-
Bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine,
Diphenylmethane compounds such as N-2,4,5-trichlorophenylleucoauramine. Rhodamine B-anilinolactam, Rhodamine B-(p-
nitroanilino)lactam, rhodamine B-(p
-chloroanilino)lactam, 7-dimethylamino-2-methoxyfluorane, 7-diethylamino-2-methoxyfluorane, 7-diethylamino-3-methoxyfluorane, 7-diethylamino-3-chlorofluorane, 7-diethylamino- 3-chloro-2-methylfluoran, 7-diethylamino-2,3-dimethylfluoran, 7-
Diethylamino-(3-acetylmethylamino)
Fluoran, 7-diethylamino-(3-methylamino)fluorane, 3,7-diethylaminofluorane, 7-diethylamino-3-(dibenzylamino)fluorane, 7-diethylamino-3
-(methylbenzylamino)fluoran, 7-diethylamino-3-(chloroethylmethylamino)
Fluoran, 7-diethylamino-3-(diethylamino)fluoran, 2-(N-methyl-N-
phenyl)amino-6-(N-ethyl-N-p-
toluyl)aminofluorane, 2-methyl-6-
(N-p-tolyl-N-ethylamino)fluoran, 3-diethylamino-7,8-benzfluoran, 3-chloro-6-cyclohexylaminofluorane, 2-mesidino-8-diethylaminobenz(C)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluorane, 3-diethylamino-7-cyclohexylaminofluorane, 3-diethylamino-7-(N-cyclohexyl-N -benzylamino)fluoran, 2-anilino-3-methyl-
6-(N-ethyl-p-toluidino)fluorane,
2-p-Toluidino-3-methyl-6-(N-ethyl-p-toluidino)fluoran, 3-(N-
xanthene compounds such as cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane; Thiazine compounds such as benzoyl leucomethylene blue and p-nitrobenzyl leucomethylene blue. 3-Methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,
3'-dichloro-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-
naphtho-(3-methoxy-benzo)spiropyran,
Spiro compounds such as 3-propyl-spirozodinafzopyran. In the present invention, the nonvolatile organic solvent containing the coloring agent is not particularly limited, and one or more organic solvents used in the field of microcapsules for pressure-sensitive copying paper are normally selected and used. can do. Specifically, mineral oils such as petroleum, kerosene, xine, toluene, etc., aromatic hydrocarbons such as hydrogenated terphenyl, alkylnaphthalene, alkylated diphenylalkane, alkylated triphenyl dimethane, alkylated diphenyl, etc. etc. are common, and aliphatic hydrocarbons, alcohols, ketones, and esters may be mixed and used as appropriate. There are no particular limitations on the method for producing microcapsules, and examples include a coacervation method using gelatin, gum arabic, etc. as a wall film-forming substance, urea-formaldehyde, isocyanate,
A synthetic capsule method using nylon or the like as a wall membrane is appropriately used. Furthermore, according to the conventional technology, starch,
Adhesives such as casein, polyvinyl alcohol, and acrylamide-based synthetic polymers, stilting agents such as pulp powder and raw starch powder, dyes, and various other auxiliary agents are appropriately added to form a color former layer coating solution. Further, examples of the method for forming the color former layer on the support include coating methods such as an air knife coater, roll coater, gravure coater, and blade coater, and various printing methods. The coloring agent layer used in combination with the coloring agent layer in the pressure-sensitive copying paper of the present invention includes clay minerals such as acid clay, activated clay, attapulgite, zeolite, bentonite, etc., and organic materials such as tannic acid and gallic acid. The main components are coloring agents and adhesives such as acids, phenolic resins, and salicylic acid derivatives, and optionally inorganic pigments such as zinc oxide, titanium oxide, magnesium oxide, and calcium carbonate, as well as various auxiliary agents. . Examples and comparative examples are listed below in order to make the effects of the present invention even clearer, but the present invention is not limited to these examples.
In addition, unless otherwise specified, parts and % in the examples represent parts by weight and % by weight, respectively. Example 1 In a mixed organic solvent consisting of 80 parts of isopropylnaphthalene and 20 parts of kerosene, 2-
(N-methyl-N-phenyl)amino-6-(N-
Ethyl-N-p-tolyl)aminofluorane 4
2,2'-methylenebis(4-
4 parts of methyl-6-tert-butylphenol was dissolved to obtain a color former oil. Separately, 20 parts of pork skin acid-treated gelatin and 20 parts of gum arabic were dissolved in 500 parts of water at 60°C, and a coloring agent oil was mixed into this solution and emulsified and dispersed until the emulsion particle size became 5μ. . To this dispersion, 800 parts of warm water at 60°C was added under stirring, and then 10% acetic acid was added to adjust the pH of the liquid to 4.2 to cause coacervation. The liquid was further cooled while stirring to gel the formed coacervation film, and after the liquid temperature reached 10°C, 12 parts of a 37% formalin solution was added, followed by a 5% formalin solution.
A capsule dispersion was prepared by adding an aqueous solution of caustic soda to adjust the pH to 9 and continuing stirring for 4 hours. The capsule solid content is added to the obtained capsule dispersion liquid.
30 parts pulp powder and 15 parts starch solution to 100 parts
(as solid content) and further added water to prepare a color former layer coating liquid with a solid content concentration of 15%. The dry coating amount of the obtained color former layer coating liquid was 4 g/
It was coated on base paper so as to have a size of m ² and dried to obtain a top paper. Example 2 In Example 1, a mixed organic solvent was added to the color former oil.
For every 100 parts, additionally tris(nonylphenyl)
A top paper was obtained in exactly the same manner as in Example 1 except that 4 parts of phosphorite was added. Example 3 A top paper was obtained in the same manner as in Example 2, except that 0.5 part of nickel dibutyldithiocarbamate was further added to the color former oil. Example 4 In Example 2, tris(nonylphenyl)
A top paper was obtained in the same manner as in Example 2, except that 4 parts of dilauryl thiodipropionate was used instead of phosphorite. Comparative Example 1 In Example 1, 2,2'-methylenebis(4
A top paper was obtained in the same manner as in Example 1, except that methyl-6-tert-butylphenol) was not used. Comparative Example 2 In Example 1, 2,2'-methylenebis(4
Example 1 except that 4 parts of bisphenol A was used instead of (methyl-6-tert-butylphenol)
The upper paper was obtained in the same manner as above. Example 5 Two parts of 2-(3',5'-di-tertbutyl-2'-hydroxyphenyl)-5-chlorobenzotriazole were dissolved in an organic solvent consisting of 100 parts of isopropylnaphthalene, and 2 parts of 2-(3',5'-di-tertbutyl-2'-hydroxyphenyl)-5-chlorobenzotriazole were dissolved as a color former. -(N-methyl-
N-phenyl)amino-6-(N-ethyl-N-
After dissolving 4 parts of p-tolyl)aminofluorane, 2,2'-methylenebis(4-methyl-6-
A color former oil was prepared by adding 2 parts of dilauryl thiodipropionate (2 parts of dilauryl thiodipropionate) and 0.5 part of nickel dibutyl dithiocarbamate. A top paper was obtained in exactly the same manner as in Example 1 except that this color former oil was used. Example 6 In Example 5, 2,2'-methylenebis(4
A top paper was obtained in the same manner as in Example 5, except that 2 parts of 2,6-di-tert-butyl-4-methylphenol was used instead of (methyl-6-tert-butylphenol). Example 7 The same procedure as in Example 5 was repeated except that 2 parts of tris(nonylphenyl) phosphorite was used in place of dilauryl thiodipropionate and 0.5 part of anthraquinone was used in place of nickel dibutyldithiocarbamate. I got the paper. Comparative Example 3 In Example 5, 2,2'-methylenebis(4
A top paper was obtained in the same manner as in Example 5, except that dilauryl thiodipropionate and nickel dibutyl dithiocarbamate were not used. Example 8 90 parts of hydrogenated terphenyl, 10 parts of chlorinated paraffin
After dissolving 3 parts of crystal violet lactone as a color former and 1 part of benzoylleucomethylene blue in a mixed solvent consisting of ) A color former oil was prepared by adding 2 parts of phosphorite. A top paper was obtained in exactly the same manner as in Example 1, except that the obtained color former oil was used. Example 9 In Example 8, 2,2'-methylenebis(4
-Methyl-6-tert-butylphenol) was replaced with 2 parts of 4-tert-butylcatechol, and
- A top paper was obtained in the same manner as in Example 8, except that a color former oil containing 0.5 parts of naphthoquinone was used. Comparative Example 4 In Example 8, 2,2'-methylenebis(4
A top paper was obtained in the same manner as in Example 8, except that methyl-6-tertbutylphenol) and tris(nonylphenyl) phosphorite were not used. Preparation of bottom paper 100 parts of activated clay, 10 parts of 20% caustic soda, 20 parts of styrene-butadiene latex (as solid content),
and 300 parts of water to prepare a coloring agent coating liquid,
This coating liquid was applied onto base paper at a dry coating weight of 6 g/m ² and dried to obtain a base paper. Evaluation test (i) CB surface coloring Obtained in Examples 1 to 9 and Comparative Examples 1 to 4
Turn the coloring agent layer coated side of the 13 types of upper paper facing up.
After irradiating with sunlight for 30 and 60 minutes, the coloring of the coloring layer was visually evaluated. The results are shown in Table 1. (ii) Color development of print after CB surface lightfastness.
Overlap the coloring agent layer of each bottom paper, 600Kg/cm ²
The color was developed by applying a load pressure of . The spectral absorption curve of the colored coloring agent layer was measured using a UVIDEC-505 self-recording spectrophotometer manufactured by JASCO Corporation. Separately, the upper paper, which had not been exposed to sunlight, was combined with the lower paper to develop color in the same manner, and the spectral absorption curve was similarly measured. From each of the obtained spectral absorption curves, two or one maximum absorption wavelength λ ₁ ,
The light resistance value A was determined from the following formula by reading λ ₂ and using the absorption concentration at the maximum absorption wavelength. The results are listed in Table 1. Lightfastness value A = Absorption density after sunlight irradiation / Absorption density before sunlight irradiation × 100 (iii) Printing lightfastness Each of the 13 types of upper paper obtained in Examples and Comparative Examples was overlaid with the lower paper, and the weight was 600 kg. / ^cm2
The color was developed by applying a load pressure of . After the colored paper was left in a dark place for 1 hour, the spectral absorption curve was measured.The colored surface was then irradiated with sunlight for 1 hour and 3 hours, and each spectral absorption curve was measured. The absorption maximum wavelengths λ ₃ and λ ₄ were read from the spectral absorption curves before and after sunlight irradiation, and the light resistance value B was determined from the absorption concentration at each absorption maximum wavelength using the following formula, and the results are shown in Table 1. . Light fastness value = Absorption density after sunlight irradiation / Absorption density before sunlight irradiation × 100 As is clear from the results in Table 1, the pressure-sensitive copying paper obtained in each example of the present invention has a high absorption density after sunlight irradiation. Also, there is little coloration on the CB surface, and even when printing is recorded after irradiation with sunlight, there is little shift in the absorption maximum wavelength of the colored image and little decrease in absorption density, so the coloring property of the print after lightfastness on the CB surface is excellent. It was an extremely excellent pressure-sensitive copying paper with little discoloration or discoloration of printed characters due to irradiation, and a well-balanced improvement in these three light fastness properties.

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Claims (1)

[Scope of Claims] 1. In a pressure-sensitive copying paper using microcapsules encapsulating a non-volatile organic solvent containing a color former, 0.2 to 10 parts of an alkylphenol compound is added to 100 parts by weight of the organic solvent in the organic solvent. A pressure-sensitive copying paper characterized by containing parts by weight. 2. The method according to claim 1, wherein the organic solvent further contains at least one compound represented by the following general formula () or () in an amount of 0.2 to 8 parts by weight per 100 parts by weight of the organic solvent. Pressure-sensitive copy paper. (In the formula, R ₁ , R ₂ , and R ₃ each represent a C ₄ to C ₂₀ alkyl group, a phenyl group, or a C ₇ to _{C 20} alkyl phenyl group.) (In the formula, R ₄ and R ₅ each represent a C ₁ to _{C 6} alkylene group, and R ₆ and R ₇ each represent a C ₈ to C ₂₂ alkyl group.)