GB1563669A

GB1563669A - Lithographic printing ink and liquid vehicle for use therein

Info

Publication number: GB1563669A
Application number: GB2634/78A
Authority: GB
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 1977-02-07
Filing date: 1978-01-23
Publication date: 1980-03-26
Also published as: IT7867238A0; FR2401209A1; BE863624A; FR2396032A1; FR2401209B1; DK54578A; GB1563670A; AU517975B2; AU3299778A; CA1123997A; SE7801356L; NO780399L; NL7801394A; CH627776A5; DE2803943A1; JPS5398385A

Abstract

The solvent in the ink contains at least 70 % by weight of saturated aliphatic hydrocarbon and an addition polymer of one or a number of ethylenically unsaturated monomers with a mean molecular weight of between 1,000 and 15,000. The temperature at which the polymer changes from the vitreous state to the rubbery state is of the order of 40 to 200 DEG C. The presence of the polymer in the ink solvent permits a rapid drying when heated without the incorporation of additives intended to promote its curing.

Description

(54) LITHOGRAPHIC PRINTING INK AND LIQUID VEHICLE FOR USE THEREIN (71) We, ROHM AND HAAS COMPANY, a corporation organised under the laws of the State of Delaware, United States of America of Independence Mall West, Philadelphia, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to lithographic printing inks comprising a polymeric binder, and liquid vehicles for use therein.

In U.S. Patent No. 3,940,353 there is disclosed a copolymer containing 40 to 60% by weight of isobornyl methacrylate and having an average molecular weight of between 1,000 and 8,500. This polymer is useful as a pigment dispersant and in laquers, and in blends with materials such as alkyds, vinyl resins and cellulose ester resins. The materials shown in the examples of that patent are insoluble in aliphatic hydrocarbons, although if styrene is substituted for methyl methacrylate, they possibly could be soluble in certain cases.

Hurwitz et al patent No. 3,681,298 relates to the same copolymer and claims the copolymer per se. Hurwitz et al disclose pigments such as carbon black an phthalocyanine blue. Cenci et al patent No. 3,485,775 relates to an isobornyl methacrylate copolymer as a modifier for polyvinyl chloride, the acrylic polymer having a number average molecular weight of between 10,000 and 1,500,000. The polymer contains 25 to 75 parts of isobornyl methacrylate with 70 to 25 parts by weight of methyl methacrylate, optionally with up to 10% of other unsaturated monomers based on the combined weight of the first two. The polymer is dry blended with polyvinyl chloride and molded or extruded.

Acrylic copolymers for inks are also known, as shown for example in U.S. Patent Nos.

3,271,347 (Aronoff et al) and 3,764,587 (Zunker). The inherent viscosity of the polymer of the latter patent, a measure of molecular weight, is between 0.2 to 0.35 measured at 25"C, using 25 milligrams of polymer in 5 cc. of chloroform, which suggest a Mw of 100,000 or greater. The monomers in the polymer are such as would yield a very rubbery, soft, product, having a very low calculated Tg as defined herein. The Aronoff et al polymer in one embodiment is primarily of vinylidene chloride, with acrylic and methacrylic acid or itaconic acid, with the optional inclusion of other monomers. The vinylidene chloride copolymers have molecular weights in the range of 3,000 to 5,000. Aronoff et al also mention all acrylic copolymers, the invention being in the inclusion of polyoxyethylene ethers.No method of preparing the acrylic polymer is disclosed nor are molecular weights.

The specific acrylics disclosed have extremely low calculated Tg'5. Aronoff et al disclose solvents including aliphatic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, etc.

The present invention is in the discovery that the utilization of an addition polymer containing polymerized ethylenically unsaturated monomers, particularly those prepared from a narrow class of certain monomers, including homopolymers but most preferably interpolymers from certain comonomers in critical ratios, along with a particular class of aliphatic hydrocarbons solvents, as an essential component in a printing ink, gives a quick-set ink or a heat-set ink with excellent characteristics, without the need to use additives to provide hardness, such as nitrocellulose, cellulose acetate butyrate, polyamides, alkyds, and the like.

In accordance with the present invention, therefore, there is provided a lithographic printing ink vehicle comprising a hydrocarbon solvent containing at least 70% by weight of one or more saturated aliphatic hydrocarbons and having a kauri-butanol number of from 18 - 31, and, dissolved in said solvent, a polymeric binder, wherein said binder is an addition polymer of one or more ethylenically unsaturated monomers, said polymer having a weight average molecular weight (Mw) in the range 1,000 to 15,000 and a calculated Tg of from 40 to 2000C. Also provided in accordance with this invention are printing inks comprising such a vehicle into which has been incorporated a pigment.

A particular feature of the polymers used as binders in the present invention is the molecular weight thereof. The molecular weight must be between 1,000 and 15,000, preferably between 4,000 and 12,000, on a weight average basis, (Mw), and between 1,000 and 7,500, preferably between 1,500 and 5,500, on a number average molecular weight basis (Mn). Molecular weight is critical since the polymer viscosity at a constant solids content is proportional to molecular weight, particularly Mw. Another important property of the polymer is the T thereof and consequently the selection of monomers and proportions thereof depends upon their influence on the Tg. 'T is a conventional criterion of polymer hardness and is described by Flory, 'Principles of Polymer Chemistry.' pp. 56 and 57 (1953), Cornell University Press.See also 'Polymer Handbook', Bandrup and Immergut, Sec. III, pp. 61-63, Interscience (1966). While measurement of the T can be used, it is difficult to obtain an accurate value on low molecular weight polymers, and it may be calculated as described by Fox, Bull. Am. Physics Soc. 1,3, p. 123 (1956), or by the use of "Rohm and Haas Acrylic Glass Temperature Analyzer" Publication No. CM-23 L/cb, Rohm and Haas Company, Philadelphia, Pa., 19105, which are incorporated herein by reference.While the actual Tg'S of the polymers of the invention are lower than the calculated Tg because of low molecular weights, the calculated T values, which are essentially the same as the measured Tg'S of high molecular weight (3100,000, Mn) polymers, are relevant indicia of the relative Tg's of different polymers. Examples of the T of high molecular weight (100,000) homopolymers, and the inherent Tg values thereof which permit such calculation, are as follows: Homopolymer Tg 2-ethylhexyl acrylate -90 C.

n-decyl methacrylate -600C.

n-butyl acrylate -56"C.

n-tetradecyl methacrylate -9 C.

n-tetradecyl acrylate 20"C.

t-butyl acrylate 43"C.

methyl methacrylate 105"C.

styrene 100"C.

acrylic acid 106"C.

isobornyl methacrylate 1800C.

Another critical requirement of the invention is that there be a balance between the second order transition temperature (tug), and molecular weight. The calculated Tg of the polymers used according to the invention. having molecular weights within the ranges specified above, have a value falling between about 40"C. and about 200"C. preferably between about 50"C. and 1200C. The approximate calculated Tg of a high molecular weight homopolymer of isobornyl methacrylate is about 1800C. However, as specified, the actual molecular weight is much lower and thus the actual may be lower than the "calculated" value.The calculated value is given as a significant index of the lower, but relative actual T of the low molecular weight polymer. In general, copolymers are preferred. Thus, in addition to monomers such as isobornyl methacrylate, other monomers may be used in suitable amounts, particularly those which give polymers having high calculated T 's i.e. if prepared as high molecular weight polymers, such polymers would have high Tg values matching the calculated value, provided of course that the low molecular weight polymers of the invention are soluble in the specified low kauri-butanol (KB) value solvents.

Examples of other useful monomers are isobutyl methacrylate (Tg 49"C), tertbutylaminoethyl acrylate (Tg 30"C.), methacrylic acid (Tg 100"C.), dimethylaminoethyl methacrylate (Tg 180C.), diinethylaminoethyl acrylate, acrylic acid (T 105"C.), maleic anhydride, itaconic acid, oxazolidinylethyl methacrylate, and styrene (Tg 100"C.). Others include acrylate and methacrylate derivatives of dicyclopentadiene, such as dicyclopentenyl methacrylate and acrylate, butyl methacrylate (Tg 20"C.), isobornyl acrylate, and vinyl aromatics such as a-chloro styrene, a-methyl styrene, and vinyltoluene.Methyl methacrylate (Tg105 C.) can be used, but only in limited amounts, because of limited solubility. As noted above, such limited amounts can be readily ascertained.

Isobornyl methacrylate and/or isobutyl methacrylate are preferred components of the polymer. When isobornyl methacrylate is utilized in a copolymer, it is used in an amount of about 1 to 40%, more preferably from about 5 to 35%. Where isobornyl methacrylate is omitted, and isobutyl methacrylate is a component of the polymer, usually it is present in an amount of between about 50% and 100% by weight, the remainder preferably being one or more of the other monomers mentioned heretofore, and more preferably one or more of the vinyl aromatics, tert-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, maleic anhydride, acrylic acid, methacrylic acid, itaconic acid, or oxazolidinylethyl methacrylate.The nitrogen-containing and carboxylic acid containing monomers are used in the very small amounts, if at all, and preferably in an amount of from about 0% to about 5%, preferably at least 0.5% by weight of the total monomers. For example, a copolymer of vinyl toluene/isobutyl methacrylate in the ratio of 50/50, or a polymer of styrene/isobutyl methacrylate in the ratio of 30/70 are useful, with or without the nitrogen containing or carboxylic acid containing monomers in small amounts. The preferred copolymers contain both isobornyl methacrylate and isobutyl methacrylate.Particularly preferred are copolymers of interpolymers containing from 35% to 75% isobutyl methacrylate and from 15% to 40%, more preferably below 35%, isobornyl methacrylate, any remainder being other ethylenically unsaturated monomers such as styrene, methacrylic acid, dimethylaminoethyl methacrylate and the like.

The polymers are preferably prepared by high temperature solution polymerization, which is known to give low molecular weight polymers, although low molecular weights can be obtained by other methods such as the inclusion of a molecular weight regulator such as an aliphatic mercaptan, for example, n-dodecyl mercaptan. In a preferred polymerization procedure, the low KB (kauri-butanol) predominantly aliphatic hydrocarbon solvent is mcluded as at least one of the solvents utilized in the polymerization. For example, the combination of xylenes, or other suitable hydrocarbon, and a hydrocarbon solvent having a KB value of about 25 may be used with a suitable polymerization catalyst or initiator, and the residual monomers and xylene or other hydrocarbon stripped off by distillation after completion of the polymerization.

Another means of obtaining low molecular weight polymers involves the utilization of a particular anionically initiated polymerization procedure, using methanol and e.g., sodium methoxide, in particular using acrylic ester and methacrylic ester monomers. These polymers have an extremely narrow distribution of molecular weights and are prepared by a unique procedure described in British Patents Nos. 1,393,273 and 1,431,446 and U.S.

Patent No. 4,056,559. These patents are incorporated herein by reference as describing the methods of obtaining low molecular weight or oligomeric polymers of alkyl acrylates and alkyl methacrylates as well as teaching methods of transesterifying the resulting polymers to obtain for example oxazolidine groups, oxazolidinyl acrylates and methacrylates, isobornyl acrylates and methacrylates and the like. Also well adapted to transesterification is low molecular weight polymethyl methacrylate, utilizing an alcohol such as isobornyl alcohol and a catalyst such as sodium methoxide, and in which the displaced methanol is distilled off, resulting in polyisobornyl methacrylate.

The liquid solvents in the printing ink vehicle of this invention are conventional solvents in the printing ink industry, but they find unique applicability when combined with the resins of the invention. The solvents have a KB value of between 18 and 31, preferably between 21 and 28. Typical products have a minimum of about 70% paraffins, i.e., consisting essentially of saturated hydrocarbons with no more than about 25% aromatics, on a weight basis. They may contain small percentages of aliphatic olefins, less than 10%, and preferably less than about 5%. The average molecular weight is between about 160 and 240.They have an initial boiling point of between about 400" and about 600"F., with a final boiling point of between about 475" and 700 F. The preferred initial boiling point is between about 400 and 450"F. with a final boiling point of between 475 and 600"F. The aniline point is between about 150 and 200. Suitable products are obtained from Magie Bros. Oil Company, 9101 Fullerton Avenue, Franklin Park, Illinois 60131. Suitable products are sold as Magie Oil 400, 405, 415, 440, Deo 440, 470, 4600, 500, Deo 520, 535, 5300, 590, 625, and Deo 620. Other boiling ranges are usuable provided the KB value is as specified.

In the final ink composition, typical pigments that can be used include carbon black, phthalocyanine blue, titanium dioxide, lithol rubin reds, ultramarine blue, hansa yellow, and the like. A suitable pigment:binder ratio is between .01:1 and 2:1, weight basis.

Determination of the properties of the polymers are by conventional methods. The kauri-butanol value is the number of milliliters of the hydrocarbon or other liquid required to cause cloudiness when added to 20 gms of a solution of kauri gum and butyl alcohol, in which there is 100 gms of kauri gum and 500 gms of butyl alcohol. This is basically ASTM method D-1133, Volume 20.

Molecular weight is determined by gel permeation chromotography, utilizing polymethylmethacrylate for calibration.

Second order transition temperature or glass transition temperature (Tg) is the temperature at which the polymer changes from a glossy state to a rubbery state, calculated as noted above.

The ink has excellent scuff and abrasion resistance, blocking resistance and heat-smear resistance even without the polymeric additives noted above, such as the cellulose esters. In addition to good quick fast-set and heat-set, and other superior qualities, the products have excellent gloss and excellent adhesion to porous and non-porous substrates. In addition, the resins of the invention are useful for pigment flushing, which flushed pigments can be let down with more of the resin of the invention and formulated into lithographic quick-set and heat-set inks.

Specific Embodiments In the following examples, the monomer abbreviations have the following meanings: iBMA isobutyl methacrylate iBOMA isobornyl methacrylate ST styrene MAA methacrylic acid VT vinyltoluene MMA methyl methacrylate t-BAEMA tertiary butylaminoethyl methacrylate Also in the examples, the Magie Oil 535 and 470 have the following properties: : 470 535 API gravity 43.7 36.9 Flash F. 230 285 KB Number 26.9 25.4 Aniline Point F. 170 173 % Aromatics (wt.) 10 22 % Olefins (wt.) 5 2 % Paraffins (wt.) 85 76 Average Arithmatical Molecular Weight 205 235 Regarding typical distillations, Magie Oil 470 has an initial boiling point of 470"F. and a final boiling point of 515"F., while Magie Oil 535 has an initial boiling point of 524"F. and end point of 595"F.

Unless otherwise specified herein all parts and ratios are by weight. Temperatures are either "C. or "F., as specified.

Example I Preparation of a Polymer of the Composition iBMAliBOMAlMAA115714013 Wt. % 1. Equipment 5 hter, 4 neck round bottom flask equipped with stirrer, condenser, thermometer and addition funnel with an N2 inlet. The flask is heated with an oil bath.

2. Charges A. Xylene 239 B. Magie 535 oil 200 C. Tertiary butyl perbenzoate (85%) 51.6 D. Magie 535 oil 145 E. Isobutyl methacrylate 1000 F. Isobornyl methacrylate 701 G. Methacrylic acid 53 H. Tertiary butyl perbenzoate (85%) 25.8 I. Magie 535 oil 50 J. Magie 535 oil 744 3. Procedure 1. Prepare initiator feed (C & D) and monomer feed (E, F, & G).

2. Charge A & B to the flask and heat to 1500 C. Maintain an N2 atmosphere throughout the reaction.

3. When heat is at 1500C. begin to add the monomer and initiator feeds. Charge these feeds linearly over 5 hours.

4. When feeds are complete, cool the system to 1300C. over 0.5 hours.

5. At 1300C. chase with (H & I) over 0.5 hr. Hold at 1300C. for 1 hour.

6. Gradually apply vacuum and increase temperature to a maximum of 1500C. and 25 mm. vacuum to remove xylenes and unreacted iBMA.

7. When analytical results indicate that residual monomers are within specification, cool to 100 C. and dilute to 60% solids with J.

Characterization Polymer Solids 60 + 2 wt. % Viscosity ca. 200,000 cps &commat; 25 C.

Color Clear amber solution, free from particulate matter Calculated Tg = 93 C.

Mn = # 4300 Mw = # 9500 Examples Il-V By a similar procedure to that described the polymer compositions shown below and with the given properties are obtained as solutions in eigher Magie Oil 535 or 470 as shown.

Composition (wt.%) Solvent ViscositylSolids 2. iBMA/iBOMA/ST/MAA Magie 535 127,000 / 60% 40/ 18 / 40 / 2 Calculated Tg = 89 C.

Mn = # 4770 Mw = # 11,000 3. iBMA/iBOMA/VT/MAA Magie 535 128,000 / 60% 55/ 19 / 24 /2 Calculated Tg = 81 C.

Mn = # 2600 Mw = # 8300 4. iBMA/iBOMA/MMA/MAA Magie 535 178,000 / 60% 59/ 29 / 10 / 2 Calculated Tg = 85 C.

Mn = # 4100 Mw = # 10,500 5. iBMA/iBOMA/MMA/t-BAEMA Magie 535 170,000 / 60% 59/ 29 / 10 I 2 Calculated Tg = 82 C. Mn = # 3100 Mw = # 8700 Example VI Quick-Set Inks Blue Ink Based on Polymers 6α (or 7b) aiBMA/iBOMA/MAA 69/ 29/ 2 Calculated Tg = 79 C.

Mw = 7,000-8,500; Mn = 2,000-2,500 biBMA/iB OMA/t-BAEMA/MAA 68/ 28/ 3 / 1 Calculated Tg = 76 C.

Mw = 8.000 Mn = 3,500 These polymers are prepared similarly to the foregoing.

Formulation: Phthalo Blue 14.7 Polymer 6 (60% Solids in Magie Oil 535 76.7 Magie Oil 535 8.6 Total 100.0 Constant: Total Solids % 60.7 Pigment/Binder Ratio 24/76 Red Ink Based on Polymer 6 or 7 Formulation: Lithol Rubine 14.7 (Red pigment) Polymer 6 (60% Solids in Magie Oil 535) 76.7 Magie Oil 535 8.6 Total 100.0 Constant: Total Solids 60.7 Pigment/Binder Ratio 24/76 Blue Ink Based on Polymer 6 plus a Commercial Quick-Set Varnish Formulation: Phthalo Blue 16.7 Polymer 6 (60% Solids in Magie 535) 20.1 Magie Oil 535 3.2 Uroset (Urethane - modified alkyd to give fast drying)l 50.3 Alvco 19641 (Waxy slip aid) 7.4 Cobalt Naphthenate (6% metal) 1.7 Manganese Naphthenate (6% metal) 0.6 Total 100.0 Constant: Total Solids 66.1% Pigment/Binder Ratio 25/75 Example VII Heat-Set Inks Black Ink Based on Polymer 6 Formulation:: Carbon Black 10.0 Polymer 6 (60% Solids in Magie Oil 470) 84.4 Magie Oil 470 2.7 Microfive VI-FS2 (Waxy slip aid) 2.9 Total 100.0 Constant: Total Solids 63.6% Pigment/Binder Ratio 16/84 Lawyer Chemical Co. 2Dura Commodities Corp.

The following is a sample calculation of the glass transition temperature of polymer No.

6, iBMA/iBOMA/MAA 69/29/2, using the Fox equation.

The Fox equation is: 1 ~ wt. fraction Monomer &num;1 + Tg Copol. Tg Homopolymer &num;1 wt. fraction Monomer &num;2 + Tg Homopolymer &num;2 etc.

The temperatures in the equation are degrees Kelvin. Thus, for copolymer &num;6, 1 ~ .69 ~ .29 = .02 Tg 332 443 501 Tg = 352"K. = 79"C.

In conclusion, attention is directed to out copending application No. 7901744 (serial No.

1563670) which is divided herefrom and in which certain of the polymers described herein are claimed per se.

WHAT WE CLAIM IS: 1. A lithographic printing ink vehicle comprising a hydrocarbon solvent containing at least 70% by weight of one or more saturated aliphatic hydrocarbons and having a kauri-butanol number of from 18 - 31, and, dissolved in said solvent, a polymeric binder, wherein said binder is an addition polymer of one or more ethAenically unsaturated monomers, said polymer having a weight average molecular weight (Mw) in the range 1,000 to 15,000 and a calculated Tg of from 40 to 200"C.

2. An ink vehicle according to claim 1, wherein said polymer has a Mw in the range 4,000 to 12,000 and a calculated Tg in the range 50 to 1200C.

3. An ink vehicle according to claim 1 or 2, wherein the polymer is an addition polymer containing units derived from one or more of the following: isobutyl methacrylate, isobornyl methacrylate, isobornyl acrylate, dicyclopentenyl methacrylate, dicyclopentenyl acrylate or a vinyl aromatic compound.

4. An ink vehicle according to claim 3, wherein the polymer is an addition copolymer containing from 1 - 40% by weight of polymerised isobornyl methacrylate, the balance being composed of units derived from one or more ethylenically unsaturated comonomers

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Example VII Heat-Set Inks Black Ink Based on Polymer 6 Formulation: Carbon Black 10.0 Polymer 6 (60% Solids in Magie Oil 470) 84.4 Magie Oil 470 2.7 Microfive VI-FS2 (Waxy slip aid) 2.9 Total 100.0 Constant: Total Solids 63.6% Pigment/Binder Ratio 16/84 Lawyer Chemical Co. 2Dura Commodities Corp. The following is a sample calculation of the glass transition temperature of polymer No. 6, iBMA/iBOMA/MAA 69/29/2, using the Fox equation. The Fox equation is:

1 ~ wt. fraction Monomer &num;1 + Tg Copol. Tg Homopolymer &num;1 wt. fraction Monomer &num;2 + Tg Homopolymer &num;2 etc.

which do not adversely affect the solubility of the polymer in the solvent.

5. An ink vehicle according to claim 4, wherein the polymer contains from 5 - 35% by weight of polymerised isobornyl methacrylate.

6. An ink vehicle according to claim 3, wherein the polymer contains from 50 - 100% by weight of polymerised isobutyl methacrylate, and the balance, if any, is composed of units derived from one or more ethylenically unsaturated comonomers which do not adversely affect the solubility of the polymer in the solvent.

7. An ink vehicle according to claim 3, wherein the polymer contains from 35 - 75% by weight of polymerised isobutyl methacrylate and from 15 to 40% by weight of isobornyl methacrylate, and the balance, if any, is composed of units derived from one or more ethylenically unsaturated comonomers which do not adversely affect the solubility of the polymer in the solvent.

8. An ink vehicle according to any one of claims 4 - 7, wherein the balance of the polymer contains units derived from one or more of the following: t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, maleic anhydride, acrylic acid, methacrylic acid, itaconic acid, oxazolidinylethyl methacrylate or a vinyl aromatic compound.

9. An ink vehicle according to claim 8, wherein the balance of the polymer contains from 0.5 to 5% by weight, based on the weight of the polymer of t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, maleic anhydride, acrylic acid, methacrylic acid, itaconic acid or oxazolidinylethyl methacrylate.

10. An ink vehicle according to any one of the preceding claims, wherein the solvent has a kauri-butanol number of from 21 - 28.

11. A lithographic printing ink comprising a vehicle according to any one of the preceding claims and a pigment.

12. A lithographic printing ink according to claim 11 wherein the weight ratio of pigment: binder is from .01:1 to 2:1.

13. An ink according to claim 11 substantially as hereinbefore described in Example VI or VII.