JPS6311997B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to pressure-sensitive copying paper, and in particular, when exposed to sunlight or fluorescent light, the copying paper itself becomes colored or the copied print becomes discolored. Regarding pressure-sensitive copying paper. 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. 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 capable of 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 colored images obtained by contact reaction of these coloring agents with the coloring agent are generally not sensitive to sunlight or fluorescent lamp 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 non-volatile organic solvent containing a coloring agent.
This pressure-sensitive copying paper is characterized in that it contains mercaptans having a boiling point of 0.degree. C. or higher. The mercaptans used in the present invention are mercaptans such as alkyl monomercaptans, alkyl dimercaptans, aromatic monomercaptans, aromatic dimercaptans, and derivatives thereof. Various compounds are known as these mercaptans, but in the present invention, since such mercaptans are contained in the organic solvent of the microcapsule production system, they are particularly solid at room temperature or
Mercaptans having a boiling point of 150°C or higher are selectively used. That is, in the preparation of microcapsules, the process of dissolving a color former, etc. in an organic solvent is usually carried out at a high temperature of 80 to 120°C, and furthermore, the color former microcapsule composition is coated on a support and then dried at a high temperature. It is common to Therefore, when mercaptans with a boiling point of 150°C or less are included in such an organic solvent, such low-boiling mercaptans will volatilize during the preparation of microcapsules or during the coating and drying process of the microcapsule composition as described above. By doing so, not only the desired effect of the present invention cannot be sufficiently obtained, but also the working environment is contaminated, the coloring agent is accompanied when the mercaptan evaporates from the microcapsules, and the coloring property is deteriorated. This also causes damage to the pressure-sensitive copying paper, such as emitting a strange odor when used. Therefore, in the present invention, as mentioned above, mercaptans that are solid at room temperature or have a boiling point of 150° C. or higher are selectively used. Examples of such mercaptans include the following compounds. n-dodecyl mercaptan, tert-dodecyl mercaptan, n-hexadecyl mercaptan,
tert-hexadecyl mercaptan, decyl mercaptan, toluenethiol, benzyl mercaptan, dodecyl-benzyl mercaptan, 4-tert
-butylthiophenol, 4-tert-butyl-0
-thiocresol, 2-mercaptobenzothiazole, 2-mercaptotorthiazole, decanedithiol, toluene-3,4-dithiol, dithiohydroquinone, dithiocatechol, dithioresorcin, p-xylene-α,α′-dithiol, 2
-Mercaptobenzimidazole, 2-mercapto-toluimidazole, etc. In the present invention, mercaptans are generally used at 0.2 parts by weight per 100 parts by weight of the organic solvent containing the color former.
It is added in an amount of 20 parts by weight, preferably 0.5 to 6 parts by weight, and adding too much is not only economically disadvantageous but also undesirable because it impairs the stability of the microcapsule oil system. The present inventors added, in addition to the above mercaptans, a second component in an organic solvent containing a color former.
It has also been found that by adding at least one compound represented by the following general formula () or (), the above-mentioned three effects of improving light resistance, which are the objects 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 trialkyl 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, ditridecylthiopropionate, 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 mercaptans, for example, both of them can be used in combination, and each of the different compounds Of course, it is also possible to use them together. The amount of these second component compounds to be used is generally determined by the type of mercaptan as 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 it within the range of Furthermore, in the present invention, in addition to the mercaptans and the phosphite trialkyl ester compound or thioether derivative as the second component, as a third component, for example, p-benzquinone, α-
Quinones such as naphthoquinone, β-naphthoquinone, and anthraquinone, and compounds such as nickel dibutyldithiocarbamate, α-tocopherol, and 1,1-diphenyl-2-picrylhydrazyl.
It has also become clear that the effect of improving the light resistance of the present invention can be further enhanced by adding more than one species to the organic solvent at the same time. Among these third component substances, quinones and dibutyldithiocarbamine nickel are particularly effective, and the amount of the third component used is preferably 0.1 to 3.0 parts by weight per 100 parts by weight of the organic solvent. 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-dinatopyran,
3-Ethyl-spiro-dinaphthopyran, 3,3'-
Dichloro-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, 3
- Spiropyran compounds such as propyl-spiro-dibenzopyran. 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, xylene, toluene, etc., aromatic carbonization such as hydrogenated terphenyl, alkylnaphthalene, alkylated diphenylalkane, alkylated triphenyl dimethane, alkylated diphenyl, etc. Hydrogens are generally used, 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 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 liquid. In addition, methods for forming the coloring agent layer on the support include an air-knife coater, a roll coater,
Examples include coating methods such as a gravure coater and a 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 further ensure the effects of the present invention, 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
4 parts of n-dodecyl mercaptan and then 4 parts of n-dodecyl mercaptan.
A color former oil was prepared by dissolving a portion of the solution. Separately, add 20 parts of pork skin acid-treated gelatin and 20 parts of gum arabic to 60°C water.
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 make the liquid.
The pH was adjusted to 4.2 to induce coacervation. The liquid is further cooled while stirring, and the formed coacelvation film is gelled until the liquid temperature reaches 10℃.
Add 12 parts of 37% formalin solution after
Next, a 5% aqueous sodium hydroxide solution was added to adjust the pH to 9, and stirring was continued for 4 hours to prepare a capsule dispersion. 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 A top paper was obtained in the same manner as in Example 1, except that 4 parts of 4-tert-butylthiophenol was used instead of n-dodecylmercaptan. Example 3 A top paper was obtained in the same manner as in Example 1, except that 4 parts of 2-mercaptobenzothiazole was used instead of n-dodecylmercaptan. Example 4 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 5 In Example 4, tris(nonylphenyl)
A top paper was obtained in the same manner as in Example 4, except that 4 parts of dilauryl thiodipropionate was used instead of phosphorite. Example 6 A top paper was obtained in the same manner as in Example 4, except that 0.5 part of nickel dibutyldithiocarbamate was further added to the color former oil. Comparative Example 1 A top paper was obtained in the same manner as in Example 1 except that n-dodecylmercaptan was 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 The seven types of upper paper obtained in Examples 1 to 6 and Comparative Example 1 were exposed with the coloring agent layer coated side facing up and exposed to sunlight for 30 and 60 minutes. The coloring 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. The two maximum absorption wavelengths λ ₁ and λ ₂ were read from each of the obtained spectral absorption curves, and the light resistance value A was determined from the following equation 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 Seven types of upper paper obtained in the Examples and Comparative Examples were stacked 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, respectively, 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 B = 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 resistance to sunlight irradiation. There is little coloring on the CB surface even when the CB surface is exposed to sunlight, and even when printed images are recorded after being irradiated with sunlight, there is little shift in the maximum absorption wavelength of the colored image and little decrease in absorption density.
It was an extremely excellent pressure-sensitive copying paper with excellent color development after light fastness on the CB surface, and little discoloration of the print due to sunlight exposure, with these three light fastness properties improved in a well-balanced manner. 【table】

Claims (1)

[Scope of Claims] 1. A pressure-sensitive copying paper using microcapsules encapsulating a non-volatile organic solvent containing a color former, wherein the organic solvent contains mercaptans that are solid at room temperature or have a boiling point of 150°C or higher. Pressure-sensitive copying paper that is characterized by its tightness. 2. The pressure-sensitive copying paper according to claim 1, further comprising at least one compound represented by the following general formula () or () in the organic solvent. (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.) The pressure-sensitive copying paper according to claim 1, wherein the pressure-sensitive copying paper is contained in an amount of 0.2 to 20 parts by weight. 4. The pressure-sensitive copying paper according to claim 2, which contains at least one compound represented by formula () or () in an amount of 0.2 to 8 parts by weight per 100 parts by weight of an organic solvent.