Ink composition for marking pen

Abstract: An ink composition according to the present invention includes (1) a leafing type fine metal powder having a median particle size of from about 4 µm to about 11 µm, the powder being present in an amount, relative to the total amount of the ink composition, within the range of from about 10% to about 38% by weight, the powder being selected from a copperalloy, aluminum, copper, or zinc whose surface is treated by a saturated fatty acid having 16 to 22 carbon atoms, or salts thereof. The ink composition further includes (2) a petroleum resin having iodine value of not more than 30 (g/100g), whereby the resin is present in an amount, relative to the total amount of the ink composition, within the range of from about 10% to about 30% by weight; (3) at least two kinds of hydrocarbon solvents, whereby the solvents are present in an amount, relative to the total amount of the ink composition, within the range of from about 32%to about 80% by weight.

Description: The present invention relates to an ink composition for use in a marking pen and, more particularly, to a metallic luster ink composition which provides bright and opacifying handwriting having a metallic luster of gold, silver, copper, red or blue on various written objects, which is free of degeneration and discoloration, appears as a metallic luster color as if obtained by a fresh ink composition even after long-term storage, and is superior in redispersion of metal powder pigment. A marking pen typically includes a penholder having an ink container therein, a penpoint attached to the leading end of the penholder, and an ink efflux adjusting equipment which provides an ink from the penholder to the penpoint. Such a penpoint is usually made of, for example, a bundle of fibers, a plastic rod having a penetrating hole, or the like. The ink efflux adjusting equipment employs, for example, an ink feeding mechanism which provides an ink from the ink container to the penpoint through a valve in accordance with a press operation, an ink feeding mechanism which leads an ink from the ink container to the penpoint by way of a helical core, or the like. An ink stirring ball typically is sealed in the in:k container, as required. Conventionally, a metallic luster ink composition for use in a marking pen has been used for obtaining metallic luster handwriting on a surface of metal, glass, plastic, paper, or the like. Such a conventional ink composition comprises metal deposited plastic foil fractions dispersed in a vehicle including an organic solvent and a resin dissolved therein. However, handwriting obtained using the above-mentioned ink composition is inferior in metallic luster performance. To improve this performance, so-called leafing-type fine metal powder, each piece having the shape of a scale,surface-treated with a higher fatty acid or its salt to enhance a metallic luster performance, has been used. Japanese Patent Publication (unexamined) No. Hei 1-56109 discloses an ink composition comprising a leafing-type fine metal powder, an organic solvent and a hydrocarbon base resin or a xylene resin dissolved in the solvent. The organic solvent is usually selected from an aromatic hydrocarbon, an aliphatic hydrocarbon, an alicyclic hydrocarbon, a ketone and an ester. The fine metal powder typically is selected from aluminum, copper, zinc and copper alloy, each surface-treated with a fatty acid such as palmitic acid, stearic acid, oleic acid, or the like. Japanese Patent Publication (unexamined) No. Hei 1-56109 discloses a metallic luster ink composition comprising a leafing-type fine metal powder, a solution for dispersing the powder, a rust-preventive agents and a dispersant. An alkyl phenol denatured xylene resin, xylene resin or a petroleum resin is dissolved in a mixture of a mineral spirit or a xylol of an aromatic base solvent and an isobutyl ketone, a n-hexane or a methylcyclohexane. The handwriting obtained by use of the ink has a bright and reflective metallic luster color. However, when the ink is kept in the marking pen for a long period, for example, for more than three months, handwriting obtained by the ink is sometimes less reflective and exhibits a simple metallic color with no metallic luster, compared to handwriting obtained by a fresh ink. Thus, conventional ink containing a leafing-type fine metal powder shows an inferior quality after long-term storage. Further, redispersion of the metal powder is inadequate. In view of the foregoing disadvantages that are inherent in conventional ink composition, the present invention aims to solve the above problems of an ink composition for use in marking pen. Hence, it is an object of the present invention to provide an ink composition for use in a marking pen which even after long-term storage is free of degeneration and discoloration and can give clear and reflective handwriting having a metallic luster of gold, silver, copper, or the like, on various written objects as if obtained by fresh ink. It further is an object to provide an ink composition that is superior in redispersion of metal powder. The present invention provides an ink composition comprising: (1) leafing-type fine metal powder having a median particle size of from 4 µm to 11 µm, the powder being present in an amount, relative to the total amount of the ink composition, within the range of from 10% to 38% by weight, the powder being selected from a copper alloy, aluminum, copper, and zinc whereby each surface is treated with a saturated fatty acid having 16 to 22 carbon atoms, or a salt thereof; (2) a petroleum resin having an iodine value of less than 30 (g/100g), the resin being present in an amount, relative to the total amount of the ink composition, within the range of from 10% to 30% by weight; (3) at least two kinds of hydrocarbon solvents of different vapour pressure, the solvents being present in an amount, relative to the total amount of the ink composition, within the range of from 32% to 80% by weight. The ink composition may further comprise at least one additive selected from (4) pigments, fatty dyes, rust-preventive agents, leafing type additive agents and pigment dispersants. The present invention also provides the use of a petroleum resin having an iodine value of not more than 30 (g/100g), in a proportion of from 10% to 30% by weight, to inhibit deterioration and change of metallic lustre in an ink composition which also comprises components (1) and (3) specified above, in the proportions there specified. The invention further provides the use of at least two hydrocarbon solvents, in the proportion specified in (3) above, to improve redispersion of the metal powder in an ink composition comprising a petroleum resin having an iodine number of not more than 30 (g/100g) and also comprising a metal powder as specified above, the proportions of the resin and metal powder being as specified above. Usually, any leafing type fine metal powder can be used so long as it achieves the foregoing objects of the invention. A leafing type fine metal powder having a median particle size of from 4 µm to 11 µm can be used in the present invention. The surface of the metal powder may be treated with a saturated fatty acid such as palmitic acid, stearic acid and the like each having 16 - 22 carbon atoms, or salts or mixtures thereof. The leafing type fine metal powder is typically distributed in an ink composition so that the powder preferably is condensed on a surface of the handwriting and thus a metallic luster is obtained by the increased reflection property of the handwriting. As petroleum resins used in the present invention, an aromatic base petroleum resin and an aliphatic base resin made of a by-product from petroleum cracking, or a hydrogenation petroleum resin preferably can be used. The hydrogenated petroleum resin can be obtained by adding hydrogen to a petroleum resin polymerized with an acidic catalyst based on a higher unsaturated hydrocarbon. The chemical structure of the petroleum resin is complex, and a saturated hydrocarbon ring usually is pendent to a long chain on an aliphatic saturated hydrocarbon chain in almost all of the structures. It is said that some of the carbon-carbon bonds of the aromatic base resin and the aliphatic base resin are unsaturated. Though the unsaturated bond content depends on the degree of hydrogenation petroleum resin, a petroleum resin having a fairly low content of unsaturated bonds is preferably used. The reason for using petroleum resins having a fairly low content of the unsaturated bond is as follows. When a leafing-type fine metal powder and a petroleum resin having a high iodine value, i.e., a petroleum resin having a fairly high content of unsaturated bonds, are used in a metallic luster inks,it is conceivable that electrons transfer at the double bond among the fine metal powder and between a saturated fatty acid and a resin. Thus, oxidation of metal powder and/or lost of leafing occurs, resulting in deterioration of metallic luster color and change in color. To prevent the deterioration and change of metallic luster color,hydrogenated saturated petroleum resin is used, giving an ink composition in which change in quality and color can be prevented, because it was found that in the unsaturated bonds in a resin, the fine metal powder electrons that may transfer at the double bond between the fine metal powder and a saturated fatty acid, may be reduced. As a result of an intensive study of the maximum limit amount of double bonds which have this effect in practice, it was found that an iodine value is not more than 30(g/100g). Thus, the iodine value is reduced to not greater than 30(g/100g), more preferably to not greater than 15(g/100g). In practice, the iodine value is from 0 to 30(g/100g), preferably from 0 to 15(g/100g). The iodine value can be controlled by the amount of hydrogenation, and these skilled in the art are capable of controlling the iodine content using the guidelines provided herein. As aromatic units in the petroleum resin, units derived from styrene, α-methyl styrene, and/or units derived from vinyl toluene and units derived from α-methyl styrene are preferably used. The iodine value thereof is preferably reduced to not greater than (g/100g), more preferably reduced within the range of from 0 to 10(g/100g), and most preferably reduced within the range of from 0 to 5(g/100g). As an aromatic base petroleum resin, a resin obtained by polymers of high purity is preferably used. When petroleum resins comprising units derived from styrene are used, the resins preferably have a molecular weight lower than that generally applicable to polystyrene, more particularly, a molecular weight within the range of 300 - 1000, and an iodine value which is controlled to within the range of from 0 to 10(g/100g). For example, PICCOLASTIC A5 (brand name) made by RIKA-HERCULES INC. or PICCOLASTIC 75 (brand name) made by RIKA-HERCULES INC. are preferably used. When α-methyl styrene units are present, resins having a molecular weight within the range of 600-1100 are preferred. More preferably, resins having an iodine value of 0-5(g/100g) are used. For example, KLISTALEX 3085 (brand name) made by RIKA-HERCULES INC. or KLISTALEX 3100 (brand name) made by RIKA-HERCULES INC. are preferably used. When both vinyl toluene and α-methyl styrene units are present, resins having a molecular weight within the range of 900-4000 are preferably used. More preferably, resins having an iodine value of 0 to 5 (g/100g) are used. For example, PICCOTEX LC (brand name) made by RIKA-HERCULES INC. preferably is used. On the other hand, when the marking pen filled with the above described luster color ink is left for a period of time, the fine metal powder dispersed in the organic solvent will deposit. Therefore, shaking the marking pen is required for stirring the ink and redispersing the deposited fine powder by using the ball in the ink container. However,redispersion deteriorates with long-term storage. Therefore, to improve this redispersion, a mixture of more than two different solvents is used in the present invention. When the ratio of the solvent weight of the solvent having a higher vapor pressure to the solvent weight of the solvent having a lower vapor pressure falls within the range of from 25: 100 to 400:100, convection of the solvents is enhanced to suppress sedimentation of the leafing-type fine metal powder. As a result, the formation of undissolved lumps is avoided and re-dispersion of the powder is improved. When two or more solvents in ratios outside the above-mentioned ranges are used, the fine metal powder sediments and is liable to form undissolved lumps. The proportion of the leafing-type metal powder, based on total amount of the ink composition, should fall within the range of from 10 to 38% by weight, preferably from 31 to 35% by weight. If the amount of the fine metal powder relative to that of the ink composition is less than 10% by weight, the handwriting will look weak, or will be inferior in opacifying effect. On the other hand, if the amount of the fine metal powder relative to that of the ink composition exceeds 38% by weight, the ink will flow with difficulty, or will solidify after long-term storage. The proportion of petroleum resin relative to the total amount of ink composition should fall within the range of from 10 to 30% by weight, preferably from 15 to 27% by weight. If the amount of petroleum resin relative to the total amount of the ink composition is less than 10% by weight, the re-dispersion will be reduced during the storage, and the handwriting will have less metallic luster and will fade because of losing adhesion to written objects. On the other hand, if the proportion of petroleum resin relative to that of the ink composition exceeds 30% by weight, the ink will flow only with diffiulty because of increased ink viscosity. The proportion of the solvents relative to the total amount of the ink composition should fall within the range of from 32 to 80% by weight. If the amount of solvent relative to the total amount of the ink composition is less than 32%, the ink will flow only with difficulty or may solidify after long-term storage. If the amount of solvent relative to that of the ink composition exceeds 80% by weight, the handwriting will probably look weak or will be inferior in opacifying effect. The amount of solvent relative to the total amount of the ink composition depends on the resin dissolving power of the solvent and its vapor pressure. If solvents of the alicyclic saturated hydrocarbon series are used, the amount thereof is preferably 40% - 60% by weight. Additives such as fatty dyes, rust-preventive agents, leafing-type additive agents, pigment dispersants, the like, or a pigment and a colorant which dissolve in the above-mentioned solvents may be added to the ink composition. Those skilled in the art are capable of adding these additives depending upon the intended application properties desired of the ink composition. The invention now will be explained by reference to particularly preferred embodiments as illustrated in the following non-limiting examples. Examples According to the weight ratio shown in tables 1 and 2, a resin was added to one or more solvents and dissolved therein by stirring at a temperature of 50 °C. After the resultant solution was cooled to room temperature, a fine metal powder was added to the solution. Metallic luster ink compositions for use in a marking pen were obtained after the resultant mixture was stirred for dispersion. By using marking pens filled with the metallic luster ink compositions, prepared above, hand writing was obtained from ink compositions when used in marking pens. The metallic luster of the hand writing after short-time storage, the metallic luster of the hand writing after long-term storage, and the redispersion after long-term storage were evaluated, and the test results are shown in Tables 1 and 2. The marking pens used in the examples were those available as PAINT MARKER HOSOJI (brand name) made by SAKURA COLOR PRODUCTS CORPORATION. These marking pens have a penholder having an ink container inside, a penpoint attached to the end of the penholder, and an ink efflux adjusting equipment which provides an ink from the penholder to the penpoint. This ink efflux adjusting equipment includes a mechanism which provides an ink from the ink container to the penholder through a valve corresponding to a press operation. A stirring hard ball is sealed in the ink container. The details of mixture used in Tables 1 and 2 are shown as follows. (1) SUPER 300: made by ECKART-WERKE, STANDART BRONZE POWDER SUPER 3000 RICHGOLD (surface treated with stearic acid, median particle size is 4 µm; fine copper alloy powder of leafing type) . (2) ROTOFLEX: made by ECKART-WERKE, STANDART BRONZE POWDER ROTOFLEX RICHGOLD (surface treated with stearic acid, median particle size is 5 µm; fine copper alloy powder of leafing type) . (3) RESIST ROTOFLEX: made by ECKART-WERKE, STAMDART BRONZE POWDER RESIST ROTOFLEX RICHGOLD (surface treated with stearic acid, median particle size is 4 µm; fine copper alloy powder of non-leafing type). (4) CHROMAL X: made by ECKART-WERKE, STANDART ALUMINUM POWDER CHROMAL X (surface treated with stearic acid, median particle size is 9 µm; fine aluminum powder of leafing type). (5) ALPASTE 1230M : made by TOYO ALMINUM K.K.A1230 (surface treated with palmitic acid, median particle size is 10 µm; Fine copper aluminum powder of non-leafing type). (6) MARUKAREZ H925: made by MAKUZEN PETROCHEMICAL COMPANY, LIMITED MARUKAREZ H925 (Petroleum resin. The iodine value is 10 (g/100g)). (7) MARUKAREZ H505: made by MARUZEN PETROCHEMICAL COMPANY, LIMITED MARUKAREZ H505 (Petroleum resin. The iodine value is 30 (g/100g)). (8) NEOPOLYMER 170S: made by NIPPON OIL COMPANY, NISSEKI NEOPOLYMER 170S (Petroleum resins. The iodine value is 47 (g/100g)). (9) MARUKAREZ M845: made by MARUZEN PETROCHEMICAL COMPANY, LIMITED, MARUKAREZ M845 (Alicyclic hydrocarbon resin. The iodine value is 190 (g/100g) ) . (10) MARUKAREZ S100A: made by MARUZEN PETROCHEMICAL COMPANY, LIMITED, MARUKAREZ S100A ( Aliphatic hydrocarbon resin. The iodine value is 150 (g/100g)). (11) REGALITE R -90: made by RIKA-HERCULES INC. REGALITE R-90 (Alicyclic hydrocarbon resin. The iodine value is less than 1.6 (g/100g)) . (12) PICCOLASTIC A75: made by RIKA-HERCULES INC. PICCOLASTIC A75 (Resin containing units derived from styrene. The iodine value is 3.2(g/100g)). (13) PICCOTEX: made by RIKA-HERCULES INC. PICCOTEX (Resin containing units derived from vinyl toluene and units derived from α-methyl styrene. The iodine value is 3.2(g/100g).) (14) KLISTALEX 3085: made by RIKA-HERCULES INC. KLISTALEX 3085 (Resin containing units derived from vinyl toluene and units derived from α-methyl styrene. The iodine value is 3.2(g/100g).) (15) MCH : made by MARUZEN PETROCHEMICAL COMPANY, LIMITED (Methylcyclohexane vapor pressure at 22.0°C is 44 mmHg. Alicyclic hydrocarbon resin solvent.) (16) ECH : made by MARUZEN PETROCHEMICAL COMPANY, LIMITED (Ethylcyclohexane vapor pressure at 20.6°C is 10 mmHg. Alicyclic hydrocarbon resin solvent.) The designations in (1) to (16) above and in Tables 1 and 2 are trade marks. "Initial metallic luster" was evaluated from handwriting on a black art paper. The handwriting was obtained on the day when the ink was sealed in the marking pen. The criteria are as follows. Evaluation A: Initial metallic luster reached the level expected. Evaluation B: Initial metallic luster did not reach the level expected, however it was fairly good. Evaluation C: Initial metallic luster did not reach the level expected. "Metallic luster after long-term storage" was evaluated from handwriting on black art paper. The criteria are the same as mentioned above. The ink was sealed in a marking pen, and the pen was stored at 50 °C for one month. Then, the pen was shaken for redispersing the deposited fine metallic powder by using the ball in the ink container. The criteria for evaluating the ink are as follows. Evaluation A: Initial metallic luster reached the level expected. Evaluation B: Initial metallic luster did not reach the level expected, however it was fairly good. Evaluation C: Initial metallic luster did not reach the level expected. "Re dispersion" was estimated from the number of times of shaking a marking pen, which had been stored at 50 °C for one month, to make it possible to move a hard ball in the ink container for re-dispersing the fine metal powder. The criteria are as follows. Evaluation A:The number of times of shaking the pen is not more than 10. Evaluation C:The number of times of shaking the pen exceeds 10. Material used in Ink composition EXAMPLE No. 1 2 3 4 5 6 7 8 9 10 11 Metal powder SUPER 3000 (1) 33 20 30 28 20 ROTOFLEX (2) 11 16 25 16 RESIST ROTOFLEX (3) CHROMAL X (4) 16 30 20 16 ALPASTE 1230M (5) Resin MARUKAREZ H-925 (6) 14 23 12 23 MARUKAREZ H-505 (7) 26 15 16 16 REGALITE R-90 (11) 28 PICCOLASTIC A75 (12) 25 PICCOTEX LC (13) 20 KRISTALEX 3085 (14) 30 Solvent MCH (15) 11 30 45 28 28 20 10 35 26 5 40 ECH (16) 30 30 16 20 30 22 40 25 16 56 8 Evaluation Initial metallic luster A A A A A A A A A A A Metallic luster after long-term storage A A A A A A A A A A A Re-dispersion after long-term storage A A A A A A A A A C C Material used in Ink composition COMPARATIVE EXAMPLE No. 1 2 3 4 5 6 Metal powder SUPER 3000 (1) 33 ROTOFLEX (2) 11 11 RESIST ROTOFLEX (3) 36 CHROMAL X (4) 16 ALPASTE 1230M (5) 30 Resin MARUKAREZ H-925 (6) 12 14 MARUKAREZ H-505 (7) 16 26 15 NEOPOLYMER 1708 (8) 23 MARUKAREZ M-845 (9) 14 MARUKAREZ S-100A (10) 15 Solvent MCH (15) 30 45 28 28 41 ECH (16) 30 16 20 30 60 Evaluation Initial metallic luster A A C C A A Metallic luster after long-term storage C B C C A A Re-dispersion after long-term storage A A A A C C As can be seen from the foregoing results given above, in the comparative Examples 1 and 2, which use a petroleum resin having an iodine value of greater than 30 (g/100g), the initial metallic luster is fairly good, however, the metallic luster after long-term storage is poor. In comparative Example 1, which uses MARUKAREZ M845 having an iodine value of 190 (g/100g), the metallic luster after long-term storage is fairly poor. In comparative Examples 3 and 4 which use a non-leafing type fine metal powder, the initial metallic luster is poor. In comparative Examples 5 and 6 which use only one solvent, re-dispersion after long-term storage is poor. In Examples 10 and 11 which use two kinds of solvents whereby the ratio of the solvent having the higher vapor pressure to the solvent having the lower vapor pressure is outside the range of from 25:100 to 400:100, the re-dispersion after long-term storage is poor. On the other hand, in all Examples according to the present invention, both the initial metallic luster and the metallic luster after long-term storage are good. In addition re-dispersion after long-term storage was good. It is understood from the above that the ink composition for use in marking pen according to the present invention is free of degeneration and discoloration and can give a clear and reflective handwriting having metallic luster as if obtained by fresh ink even after long-term storage and is superior in redispersion of metal powder. In the following claims, unless this is clearly inappropriate in any particular case, the feature(s) of any one of the claims may if desired be combined with the feature(s) of one or more of the other claims.

Claims: A metallic luster ink composition for use in a marking pen, comprising: (1) a leafing-type fine metal powder having a median particle size of from 4µm to 11µm, the powder being present in an amount, relative to the total amount of the ink composition, within the range of from 10% to 38% by weight, the fine metal powder being selected from one or more of the group consisting of a copper alloy, aluminium, copper, and zinc, each powder being surface treated with a saturated fatty acid having 16 to 22 carbon atoms, or a salt thereof; (2) a petroleum resin having an iodine value of less than 30 (g/100g), the resin being present in an amount, relative to the total amount of the ink composition, within the range of from 10% to 30% by weight; and (3) at least two hydrocarbon solvents of different vapour pressure, the solvents being present in an amount, relative to the total amount of the ink composition, within the range of from 32% to 80% by weight. An ink composition as claimed in claim 1, wherein the petroleum resin has an iodine value of from 0 to 15. An ink composition as claimed in claim 1 or claim 2, wherein the petroleum resin has an iodine value of from 0 to 10, preferably from 0 to 5. An ink composition as claimed in any one of claims 1 to 3, further comprising at least one additive selected from the group consisting of a pigment, a fatty dye, a rust-preventive agent, a leafing type additive agent and a pigment dispersant. An ink composition as claimed in any one of claims 1 to 4, wherein the weight ratio of the hydrocarbon solvent having the higher vapor pressure to the hydrocarbon solvent having the lower vapor pressure falls within the range of from 25: 100 to 400: 100. An ink composition as claimed in any one of claims 1 to 5, wherein at least one of the hydrocarbon solvents is an alicyclic saturated hydrocarbon solvent. An ink composition as claimed in any one of claims 1 to 5, wherein said at least two hydrocarbon solvents are selected from methylcyclohexane and ethylcyclohexane. An ink composition as claimed in any one of claims 1 to 7, wherein the leafing-type fine metal powder comprises a copper alloy. An ink composition as claimed in any one of claims 1 to 8, wherein the leafing-type fine metal powder comprises aluminium. An ink composition as claimed in any one of claims 1 to 9, wherein the leafing-type fine metal powder comprises copper. An ink composition as claimed in any one of claims 1 to 10, wherein the leafing-type fine metal powder comprises zinc. An ink composition as claimed in any one of claims 1 to 11, wherein the petroleum resin comprises units selected from the group consisting of styrene, α-methyl styrene, both vinyl toluene and α-methyl styrene, and mixtures thereof. An ink composition as claimed in claim 12, wherein the petroleum resin comprises units derived from styrene and has a molecular weight within the range of from 300 to 1000. An ink composition as claimed in claim 12, wherein the petroleum resin comprises units derived from α-methyl styrene and has a molecular weight within the range of from 600 to 1100. An ink composition as claimed in claim 12, wherein the petroleum resin comprises units derived from vinyl toluene and units derived from α-methyl styrene and has a molecular weight within the range of from 900 to 4000. An ink composition as claimed in any one of claims 1 to 15, wherein the leafing-type metal powder is present in an amount within the range of from 31% to 38% by weight. An ink composition as claimed in any one of claims 1 to 16, wherein the petroleum resin is present in an amount within the range of from 15% to 27% by weight. A marking pen containing an ink composition as claimed in any one or more of claims 1 to 17. The use of a petroleum resin having an iodine value of not more than 30 (g/100g), in the proportions specified in claim 1, to inhibit deterioration and change of metallic luster of an ink composition which also comprises components (1) and (3) specified in claim 1, in the proportions specified in claim 1. The use of at least two hydrocarbon solvents as specified in claim 1, in the proportion specified in claim 1, to improve redispersion of the metal powder in an ink composition comprising a petroleum resin having an iodine value of not more than 30 (g/100g) and also comprising component (1) specified in claim 1, the proportions of the resin and of component (1) being as specified in claim 1. The use as claimed in claim 19 or claim 20, wherein the ink composition is as claimed in any one of claims 2 to 17.

Inventors: OKUDA YASUJI, YAMASAKI HIROFUMI, YOKOI MASAKAZU, OKUDA, YASUJI, YAMASAKI, HIROFUMI, YOKOI, MASAKAZU, Okuda, Yasuji, c/o Sakura Color Prod. Corp., Yamasaki, Hirofumi, c/o Sakura Color Prod. Corp., YOKOI, MASAKAZU, C/O SAKURA COLOR PRODUCTS CORP.
Applicants: SAKURA COLOR PROD CORP, SAKURA COLOR PRODUCTS CORPORATION
Application year: 1996
Main classification: C09D11
IPC codes: C09D11