Removable ink composition and process for removing said ink composition from printed articles

Abstract: A removable ink composition comprising (A) a urethane resin and/or an acrylic resin and (B) one or more substances selected from the group consisting of styrene-acrylic acid copolymers, styrene-maleic acid resins, rosin-maleic acid resins and phenol resins as main components of a vehicle and a process for removing an ink composition from printed articles which comprises treating articles printed with this ink composition with an aqueous alkali solution. Prints of the above ink composition on plastic films and plastic containers can be removed and decolorized in a short time by treating the ink composition with a dilute aqueous alkali solution having a concentration of 1 to 3%.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a removable ink composition used for prints on plastic containers and plastic films, and more particularly, to an ink composition which is used for prints on plastic films and plastic containers and can be removed and decolorized easily by treating the ink composition with a dilute aqueous alkali solution and a process for removing the ink composition from articles printed with the ink composition. 2. Description of the Related Arts Various containers made of polyethylene terephthalate have been used widely as containers of refreshing drinks, cosmetics, seasonings and drugs. Trade names and descriptions about contents are directly printed on the surface of these containers or printed on labels which are attached to the surface of these containers. Environmental pollution caused by disposed containers, labels and packaging bags made of plastics which are hardly decomposed in the natural condition has recently become a problem and it is urgently required to decrease the amount of such disposed articles. Recovery of plastic materials from containers of refreshing drinks which are generally called PET bottles has been advanced considerably. The recovered plastic materials are fabricated again to prepare secondary products. Plastic articles such as containers from which the materials are recovered are attached with printed shrink films. Secondary products fabricated using the recovered plastic materials are not free from various colors unless inks used in the prints are removed or decolorized before the fabrication. Therefore, it is necessary that inks used in the prints be removed or decolorized to obtain secondary products having properties similar to products which are made of new materials. A printing ink containing a polyurethane resin is described in EP-A- 0 604 890. The printing ink contains a polyurethane resin, a coloring agent and an organic solvent. Besides the polyurethane resin a further binder resin may be present. Coatings for treatment of wood material are described in EP -A- 0 373 882. The intention of these coatings is to provide a permanent aspect to wood material. They contain acrylic resins, styrene-maleic anhydride resins, pigments and fillers. Ink compositions with the property of dissolving in solvents and in an alkaline solution are described in JP -A- 01 193 378. As the process for decolorizing printed plastic articles, for example, a process in which plastic articles are treated with a cleaning liquid containing an organic solvent which dissolves or swells the coating material of the prints and a caustic alkali as essential components, is known (Japanese Patent Publication Showa 52(1977)-26549). This process has a drawback in that the organic solvent contained in the waste liquid must be separated and recovered and the operations of separation and recovery must be additionally conducted. Moreover, gravure ink compositions generally used for plastic films and plastic containers are prepared by adding pigments to a vehicle containing a urethane resin or an acrylic resin as the main component, cellulose resins, vinyl acetate resins and rosin. Therefore, it is difficult to remove or decolorize the ink compositions used in the prints by treating the ink compositions with an aqueous solution of sodium hydroxide having a concentration of 1 to 3%. It is urgently required that the above problems be solved and colorless materials be recovered from plastic films and plastic containers by treating ink compositions used in the prints on plastic films and plastic containers with a dilute alkali solution. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink composition which is used for prints on plastic films and plastic containers and can be removed and decolorized in a short time by treating the ink composition with a dilute aqueous alkali solution having a concentration of 1 to 3%. As the result of intensive studies by the present inventors to solve the above problems, it was found that an ink composition comprising a vehicle obtained by adding one or more substances selected from the group consisting of styrene-acrylic acid copolymers, styrene-maleic acid resins, rosin-maleic acid resins and phenol resins to the main component which is a urethane resin and/or an acrylic resin shows no decrease in the printing property on plastic films and that prints using the ink composition can be removed in a short time by treating the ink composition with a dilute aqueous alkali solution having a concentration of 1 to 3%. The present invention has been completed on the basis of this knowledge. Accordingly, the present invention provides (1) A removable ink composition comprising (i) a component (A) comprising a urethane resin and a cellulosic resin and (ii) a component (B) comprising a vehicle comprising as a main component one or more substances selected from the group consisting of styrene-acrylic acid copolymer, styrene-maleic acid resin, rosin-maleic acid resin and a phenol resin, wherein the removable ink composition is resistant to water and is removable by a dilute aqueous alkali solution having a concentration of 1 to 3 %; (2) The removable ink composition according to (1), wherein the component (A) comprises an acrylic resin; (3) The removable ink composition according to (1) or (2), wherein an amount of the component (B) is less than the amount of the component (A); (4) The removable ink composition according to any of (1) to (3), which further comprises at least one pigment selected from the group consisting of an organic pigment and an inorganic pigment; (5) The removable ink composition according to any of (1) to (4), which further comprises powder of synthetic resins; (6) A process for removing an ink composition from printed articles which comprises treating articles printed with an ink composition according to any of (1) to (5) with an aqueous alkali solution. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is described more specifically in the following. The component (A) comprises a urethane resin and a cellulosic resin. As the urethane resin of component A used in the present invention, linear polyurethane-polyurea resins are mainly used. More specifically, for example, (a) a urethane prepolymer which is obtained by the reaction of a mixture of a dihydroxy compound having carboxyl group and a polyol compound having terminal hydroxyl groups and a molecular weight of 1,000 to 6,000 with a diisocyanate compound in an amount by equivalent larger than that of hydroxyl group in the above mixture and which has isocyanate groups at the chain ends and dicarboxyl groups inside the molecular chain and (b) a chain extender of a diamine compound are reacted in an organic solvent to obtain a resin intermediate containing carboxyl group, and the carboxyl group in the obtained resin intermediate is neutralized with a polyamide resin having an amine value of 100 to 500 to prepare a polyurethane-polyurea resin. The prepared resin can be used as the urethane resin of component A. Two-component type urethane resins can also be used as the urethane resin of component A. As the acrylic resin, homopolymers or copolymers of an acrylic ester or a methacrylic ester can be used. Examples of the preferable acrylic ester and methacrylic ester (hereinafter, abbreviated as the (meth)acrylic ester) used in the present invention include methyl (meth)acrylate, ethyl (meth)acrylate and butyl (meth)acrylate. Examples of the copolymer include copolymers of two or more types of the above (meth)acrylic esters and copolymers of one or more types of the above (meth)acrylic esters and one or more compounds selected from the group consisting of styrene, (meth)acrylic acid, acrylonitrile, vinyl acetate and butadiene. Preferable examples of the styrene-acrylic acid copolymer used as component B in the present invention include copolymers which contain 20 to 40% by weight of styrene, 5 to 15% by weight of methyl methacrylate, 10 to 30% by weight of butyl acrylate and 10 to 20% by weight of acrylic acid as the main components and have an acid value of 100 to 240, a molecular weight of 1,600 to 20,000 and Tg of 60 to 85°C. As the phenol resin, resins containing as the main component a phenolformaldehyde resin of the resol type or the novolak type which is obtained by the reaction of phenol having no substituents, a phenol having substituents or a derivative thereof with formaldehyde can be used. Phenol-formaldehyde resins of the resol type are preferably used. As the styrene polymer and styrene-maleic acid resin used in the present invention, a homopolymer of styrene, copolymers of styrene and maleic anhydride and copolymers of styrene and a monoester of maleic acid which have an acid value of 180 to 280 and a molecular weight of 2,000 to 70,000 are used. The above polymers and copolymers having a low molecular weight, i.e., the polymers and copolymers having an acid value of 180 to 280, Tg of 60 to 70°C and a molecular weight of 2,000 to 20,000, are preferably used. As the rosin-maleic acid resin, rosin-maleic acid resins having an acid value of 110 to 300 and Tg of 130 to 150°C and soluble in an alcohol are preferably used. In the present invention, the ink composition may comprise other resins in addition to components A and B as the components of the vehicle. The other resin may be any type of resin as long as the resin can be used for ink compositions for gravure printing or flexo printing. Examples of such resins include chlorinated polyolefin resins, polyamide resins, coumarone resins, ketone resins, vinyl acetate resins, polyvinyl butyral resins, epoxy resins, urea resins, ethylene-vinyl acetate resins, polyester resins, chorinated rubbers and cyclized rubbers. The components of the vehicle in the present invention are used in amounts such that the amount of component B is 5 to 95 parts by weight and preferably 20 to 80 parts by weight per 100 parts by weight of component A. When the amount of component B is less than 5 parts by weight, the ink composition is not removed or decolorized after the printed article is dipped into a dilute alkali solution for about 30 minutes and such an amount is not preferable. When the amount of component B exceeds 95 parts by weight, folding resistance, crumpling resistance and water resistance are adversely affected and such an amount is not preferable. In the present invention, pigments which are generally used in ink compositions for gravure printing are used. Examples of the pigment include inorganic pigments such as ultramarine blue, Prussian blue, cobalt blue, red iron oxide, iron black, yellow iron oxide, titanium dioxide, carbon black, zinc oxide and titanium black; and organic pigments such as monoazo pigments, disazo pigments, condensed azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, thioindigo pigments, dioxazine pigments and pyrolopyrrole pigments. The used amount of the pigment varies depending on the color tone and color density to be exhibited. The pigment is generally used in an amount in the range of about 0.3 to 50% by weight of the total amount of the ink composition. The ink composition of the present invention also contains fillers, wax, fine powder of plastics and plasticizers in order to maintain properties of the ink composition such as viscosity, fluidity and the thixotropic property, to provide printed faces with the slipping property and to form printed faces with gloss or without gloss. Examples of the filler include silica, alumina, talc, kaolin and calcium carbonate. Examples of the wax include polyethylene wax and polypropylene wax. Examples of the fine powder of plastics include fine powder of styrene resins, acrylic resins, polyurethane resins, polyimide resins, melamine resins and benzoguanamine resins. Examples of the plasticizer include esters of phthalic acid such as dibutyl phthalate, dioctyl phthalate and dicyclohexyl phthalate; esters of phosphoric acid such as tricresyl phosphate and trichloroethyl phosphate; dioctyl adipate; diisobutyl adipate; dioctyl sebacate; epoxidized linseed oil; epoxidized soy bean oil and sulfonamide plasticizers. In the present invention, an organic solvent such as ethyl acetate, butyl acetate, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, methanol, ethanol, isopropanol (IPA), propyl acetate, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, toluene and xylene is used as an essential component. The organic solvent is used in an amount such that the ratio by weight of the total amount of components A and B, the pigments and other additives to the amount of the organic solvent is 20:80 to 50:50 and preferably 25:75 to 40:60. When the ratio by weight is less than 20:80, the physical properties of the layer of prints coating the surface of an article are insufficient. When the ratio by weight exceeds 50:50, fluidity of the ink composition decreases to cause inferior workability. Therefore, such ratios are not preferable. The layer of prints on a polyester film formed with the ink composition of the present invention exhibits physical properties as satisfactory as those exhibited by the layers formed with conventional ink compositions. When the film having the above layer of prints is dipped into an aqueous solution of sodium hydroxide having a concentration of 1 to 3% at 80 to 90°C and the solution is stirred for 20 to 30 minutes, the layer of prints can be completely removed from the surface of the film. When the film from which the printed layer has been removed is washed with water and dried, a clear film having no layer of prints at all can be obtained. When plastic containers of refreshing drinks which are attached with shrink labels printed with the ink composition of the present invention on the surface or is printed with the ink composition of the present invention directly on the surface is treated with a dilute aqueous alkali solution, the layer of prints can be removed very easily and the containers can be decolorized. Thus, the containers are easily made colorless. The colorless containers can be pulverized, pelletized and reused as a material resin for various products. The same advantageous result can be obtained when plastic containers attached with printed shrink labels are treated with a dilute aqueous alkali solution after the plastic containers have been pulverized. To summarize the advantages obtained by the present invention, the ink composition of the present invention exhibits the same properties, such as printing property on plastic products, as conventional ink compositions for gravure printing on plastics. Layers of prints on various types of plastic articles printed with the ink composition of the present invention can be easily removed and decolorized by dipping the plastic articles into a relatively dilute aqueous alkali solution in a short time. Therefore, the used plastic articles can advantageously be reused as a material for plastic articles. EXAMPLES The present invention is described more specifically with reference to the following examples. Example 1 The following components were placed into a paint shaker and dispersed for 30 to 60 minutes to obtain a printing ink composition. colored (parts by weight) white (parts by weight) Urethane resin 35 27 trade name, SANPRENE IB104; manufactured by SANYO KASEI Co., Ltd.; a toluene-MEK-IPA solution; solid content, 30% by weight Cellulose resin 2 an ethyl acetate-IPA solution; nitrocellulose, 30% by weight Cellulose resin 10 an ethyl acetate-IPA solution; cellulose acetate butyrate, 10% by weight Polyethylene wax 0.5 0.5 Methyl ethyl ketone 25.0 14.0 Toluene 20.0 10.0 Isopropyl alcohol 2.0 3.0 Styrene-acrylic acid resin 5.0 5.0 trade name, JOHNCRYL 682; manufactured by JOHNSON POLYMER Company; acid value 235; molecular weight, 1,600; Tg, 57°C Copper phthalocyanine blue pigment 10.0 Titanium dioxide 30.0 Examples 2 to 18 Printing ink compositions were obtained in accordance with the same procedure as that in Example 1 using the components shown in Table 1-1 to Table 2-3. Comparative Example 1 A printing ink composition was obtained in accordance with the same procedure as that in Example 1 except that component B (the styrene-acrylic acid resin) was not used. Comparative Example 2 A printing ink composition was obtained in accordance with the same procedure as that in Example 10 except that component B (the styrene-acrylic acid resin) was not used. Example 1 Example 2 Example 3 colored white colored white colored white Component A urethane resin (30%) 1) 35.0 27.0 35.0 27.0 35.2 27.0 cellulose resin (30%) nitrocellulose 2.0 - 2.0 - 2.0 - cellulose resin (10%) nitrocellulose - 10.0 - 10.0 - - 10.0 polyethylene wax 0.5 0.5 0.5 0.5 0.5 0.5 methyl ethyl ketone 25.0 14.0 20.0 6.0 17.0 4.0 toluene 20.0 10.0 10.0 4.0 27.0 2.0 isopropyl alcohol 2.0 2.0 2.0 2.0 2.0 1.0 Component B styrene-acrylic acid resin 50% 2) 5.0 5.0 20.0 20.0 25.0 25.0 phenol resin (65%) 3) - - - - - - styrene-maleic acid resin (40%) 4) - - - - - - Organic pigment copper phthalocyanine blue 10.0 - 10.0 - 10.0 - Inorganic pigment titanium dioxide - 30.0 - 30.0 - 30.0 Example 4 Example 5 Example 6 colored white colored white colored white Component A urethane resin (30%) 1) 35.0 27.0 35.0 27.0 35.0 27.0 cellulose resin (30%) nitrocellulose 2.0 - 2.0 - 2.0 - cellulose resin (10%) nitrocellulose - 10.0 - 10.0 - 10.0 polyethylene wax 0.5 0.5 0.5 0.5 0.5 0.5 methyl ethyl ketone 20.0 9.0 30.0 16.0 17.0 4.0 toluene 10.0 5.0 14.0 8.0 8 8.0 2.0 isopropyl alcohol 2.0 2.0 2.0 2.0 2.0 1.0 Component B styrene-acrylic acid resin 50% 2) - - - - - - phenol resin (65%) 3) 3.0 3.0 5.0 5.0 25.0 25.0 styrene-maleic acid resin (40%) 4) - - - - - - Organic pigment permanent carmine pigment 5) 10.0 - 10.0 - 10.0 - Inorganic pigment titanium dioxide - 30.0 - 30.0 - 30.0 Example 7 Example 8 Example 9 colored white colored white colored white Component A urethane resin (30%) 1) 35.0 27.0 35.0 27.0 35.0 27.0 cellulose resin (30%) nitrocellulose 2.0 - 2.0 - 2.0 - cellulose resin (10%) nitrocellulose - 10.0 - 10.0 - 10.0 polyethylene wax 0.5 0.5 0.5 0.5 0.5 0.5 methyl ethyl ketone 27.0 18.0 30.0 17.0 17.0 3.0 toluene 14.0 8.0 15.0 8.0 8.0 2.0 isopropyl alcohol 2.0 2.0 2.0 2.0 2.0 2.0 Component B styrene-acrylic acid resin 50% 2) - - - - - - phenol resin (65%) 3) - - - - - - styrene-maleic acid resin (40%) 4) 3.0 3.0 5.0 5.0 25.0 25.0 Organic pigment disazo yellow pigment 6) 8.0 - 8.0 - 8.0 - Inorganic pigment titanium dioxide - 30.0 - 30.0 - 30.0 Example 10 Example 11 Example 12 colored white colored white colored white Component A acrylic resin (35%) 7) 40.0 27.0 40.0 27.0 40.0 27.0 cellulose resin (20%) nitrocellulose 10.0 7.0 10.0 7.0 10.0 7.0 urethane resin (30%) 1) 10.0 10.0 10.0 10.0 10.0 10.0 polyethylene wax 0.5 2.5 0.5 2.5 0.5 2.5 ethyl acetate 10.0 7.0 3.0 1.0 2.0 - isopropyl alcohol 24.0 12.0 6.0 2.0 2.0 - Component B styrene-acrylic acid resin 50% 2) 4.0 4.0 20.0 20.0 25.0 25.0 phenol resin (65%) 3) - - - - - - styrene-maleic acid resin (40%) 4) - - - - - - Organic pigment permanent carmine pigment 5) 10.0 - 10.0 - 10.0 - Inorganic pigment titanium dioxide - 30.0 - 30.0 - 30.0 Example 13 Example 14 Example 15 colored white colored white colored white Component A acrylic resin (35%) 7) 40.0 27.0 40.0 27.0 40.0 27.0 cellulose resin (20%) nitrocellulose 10.0 7.0 10.0 7.0 10.0 10.0 urethane resin (30%) 1) 10.0 10.0 10.0 10.0 10.0 10.0 polyethylene wax 0.5 2.5 0.5 2.5 0.5 2.5 ethyl acetate 9.0 8.0 8.0 7.0 5.0 2.0 isopropyl alcohol 19.0 13.0 17.0 12.0 8.0 2.0 Component B styrene-acrylic acid resin 50% 2) - - - - - - phenol resin (65%) 3) 2.0 2.0 4.0 4.0 16.0 16.0 styrene-maleic acid resin (40%) 4) - - - - - - Organic pigment copper phthalocyanine blue 10.0 - 10.0 - 10.0 - Inorganic pigment titanium dioxide - 30.0 - 30.0 - 30.0 Example 16 Example 17 Example 18 colored white colored white colored white Component A acrylic resin (35%) 40.0 27.0 40.0 27.0 40.0 27.0 cellulose resin (20%) nitrocellulose 10.0 10.0 10.0 10.0 10.0 10.0 uretbane resin (30%) 10.0 10.0 10.0 10.0 10.0 10.0 polyethylene wax 0.5 2.5 0.5 2.5 0.5 2.5 ethyl acetate 8.0 6.0 7.0 5.0 2.0 - isopropyl alcohol 18.0 11.0 17.0 10.0 2.0 - Component B styrene-acrylic acid resin 50% - - - - - - phenol resin (65%) - - - - - - styrene-maleic acid resin (40%) 3.0 3.0 5.0 5.0 25.0 25.0 Organic pigment copper phthalocyanine blue 10.0 - 10.0 - 10.0 - Inorganic pigment titanium dioxide - 30.0 - 30.0 - 30.0 Shrink films of polyethylene terephthalate were printed with the printing ink compositions obtained above in Examples and Comparative Examples and the properties for printing and easiness of removal with an aqueous alkali solution were examined. The obtained results are shown in Table 3-1 to Table 3-3. The tests and the evaluations were conducted in accordance with the following methods. 1. Preparation of printed films for the tests Using a bar coater #5, shrink films of polyethylene terephthalate SC004 (45 µm) and SC007 (50 µm) both manufactured by TOYO BOSEKI Co., Ltd. were coated with ink compositions to prepare films coated with colored ink compositions, films coated with white ink compositions and films having a layer of a colored ink composition laminated on top of a layer of a corresponding white ink composition. 2. Test methods The adhesion test by a pressure sensitive adhesive plastic tape was conducted using a pressure sensitive adhesive plastic tape manufactured by NICHIBAN Co., Ltd. and separation of the layer was visually observed. The scratch resistance was evaluated by scratching the coated surface by nails and scratches formed on the coated surface were visually observed. The crumpling resistance was evaluated by crumpling the film ten times by hands and cracks formed on the coated surface were visually observed. The folding resistance was evaluated by folding the coated film and then squeezing the folded portion twice by fingers and cracks formed on the coated surface were visually observed. The slipping property was evaluated by placing a coated surface on top of another coated surface and also on top of a surface not coated with the ink composition and then rubbing the films lightly to each other and the easiness of slipping felt by hands was compared. The water resistance was evaluated by dipping the coated film into water at room temperature for 24 hours and whitening and change in adhesion of the coating layer were observed. The easiness of removal by the alkali treatment was evaluated by dipping a coated film into an aqueous solution of sodium hydroxide having a concentration of 3% at 80 to 90°C while the solution was stirred by a spatula at a time interval of 5 minutes and removal of the coating layer was visually observed. The results are shown in accordance with the following criterion: good: removed in 20 minutes or less fair: removed in 21 to 30 minutes poor: not removed after 30 minutes Adhesion to plastic tape Scratch resistance Crumpling resistance Folding resistance Slipping property Water resistance Removal by alkali treatment Comparative Example 1 colored good fair good good poor to fair good poor to fair white good fair good good poor to fair good poor to fair Comparative Example 2 colored fair to good fair poor to fair poor to fair fair good poor white fair to good fair poor to fair poor to fair fair good poor Example 1 colored good fair to good good good fair good good white good good good good fair good good Example 2 colored good fair to good good good fair good good white good good good good fair good good Example 3 colored good good fair to good fair to good fair to good good good white good good fair fair fair to good fair to good good Example 4 colored good fair good good fair good fair to good white good fair good good fair good fair to good Example 5 colored good fair to good fair to good fair to good fair to good good good white good good fair to good fair fair to good good good Adhesion to plastic tape Scratch resistance Crumpling resistance Folding resistance Slipping property Water resistance Removal by alkali treatment Example 6 colored good good fair to good fair to good fair to good fair to good good white good good fair fair fair to good fair to good good Example 7 colored good fair fair to good fair to good fair good fair to good white good fair fair to good fair to good fair to good good fair to good Example 8 colored good fair to good fair to good fair to good fair to good good fair to good white good fair to good fair to good fair to good fair to good good fair to good Example 9 colored good fair to good fair to good fair to good fair to good good good white good fair to good fair to good fair to good fair to good fair to good good Example 10 colored good fair to good fair to good fair to good good good good white good good fair to good fair to good good good good Example 11 colored good good fair fair to good good good good white good good fair fair to good good good good Example 12 colored good good fair fair good good good white good good fair fair good good good Adhesion to plastic tape Scratch resistance Crumpling resistance Folding resistance Slipping property Water resistance Removal by alkali treatment Example 13 colored good fair fair to good fair to good good good fair white good good fair to good fair to good good good fair to good Example 14 colored good fair to good fair to good fair to good good good good white good good fair to good fair to good good good good Example 15 colored good good fair fair good good good white good good fair to good fair to good good good good Example 16 colored good fair fair fair fair good fair white good fair to good fair fair fair to good good fair Example 17 colored good fair to good fair fair to good fair to good good fair white good fair to good fair fair to good good good good Example 18 colored good fair to good fair fair to good fair to good fair to good fair to good white good good fair fair to good good fair to good good

Claims: A removable ink composition comprising (i) a component (A) comprising a urethane resin and a cellulosic resin and (ii) a component (B) comprising a vehicle comprising as a main component one or more substances selected from the group consisting of styrene-acrylic acid copolymer, styrene-maleic acid resin, rosin-maleic acid resin and a phenol resin, wherein the removable ink composition is resistant to water and is removable by a dilute aqueous alkali solution having a concentration of 1 to 3 %. The removable ink composition according to claim 1, where the component (A) comprises an acrylic resin The removable ink composition according to claim 1 or claim 2, wherein an amount of the component (B) is less than the amount of the component (A). The removable ink composition according to any of Claims 1 to 3, which further comprises at least one pigment selected from the group consisting of an organic pigment and an inorganic pigment. The removable Ink composition according to any of Claims to 4, which further comprises powder of synthetic resins. A process for removing an ink composition from printed articles which comprises treating articles printed with an ink composition according to any of claims 1 to 5 with an aqueous alkali solution.

Inventors: AWAYA KATHUFUMI, IIBOSHI KATSUFUMI, KONDO MASAHIRO, MIZUMOTO TAKAO, OGISU YASUYUKI, TAKAHASHI MASAYUKI, AWAYA, KATHUFUMI, IIBOSHI, KATSUFUMI, KONDO, MASAHIRO, MIZUMOTO, TAKAO, OGISU, YASUYUKI, TAKAHASHI, MASAYUKI
Applicants: DAINICHISEIKA COLOR CHEM, DAINICHISEIKA COLOR & CHEMICALS MFG. CO. LTD.
Application year: 1999
Main classification: C09D11
IPC codes: C09D11, C09D9