GB2085450A - Phenolic resin-cyclopentadiene polymer offset printing ink composition - Google Patents

Abstract

An offset printing ink composition comprises a vehicle resin prepared by reacting 5 to 100 parts of a phenolic resin prepared by the condensation of a phenol including an alkyl substituent group having 4 to 9 carbon atoms with formalin with 100 parts of a modified resin said prepared by reacting 1 to 15 parts of unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides and mixtures thereof with 100 parts of a resin obtained by copolymerizing 5 to 100 parts by weight of straight-chain alpha - olefins, drying oils, fatty acids and mixtures thereof with 100 parts by weight of a five-member cyclic compound having a conjugated double bond or bonds and represented by the general formula of: <IMAGE> wherein R is alkyl group having 1 to 3 carbon atoms and n is zero or an integer and/or a Diels-Alder addition product thereof.

Description

SPECIFICATION Offset printing ink composition This invention relates to a printing ink composition for offset printing.

In offset printing, the inked image is first transferred from a print roller to a rubber blanket, and then printed on a sheet of paper. The pring roller has a surface composed of hydrophilic portions (non-image portions) containing water and repelling oily ink and ink-holding portions (image portions) containing oily ink and repelling water. The most widely used offset printing inks are resin varnishes containing vehicle resins, such as alkyphenol resins, phenolic resins modified with rosin or maleic acid resins, which resins are dissolved in drying oils such as linseed oil. The most commonly used vehicle resins are phenolic resins modified with rosin.

Although a printing ink vehicle composed of a phenolic resin modified with rosin, a solvent and/or a drying oil is excellent in quality, it has disadvantages that it is expensive and contains rosin which is a material of natural origin and unstable in supply. In place of the phenolic resin modified with rosin, it has been proposed to use so-called petroleum resins synthesized by polymerizing cracked oil fractions obtained as the by-products of the petroleum or petrochemical industries. Although these petroleum resins have advantages that the supply and cost thereof are stable, their qualities are not fully satisfactory when used as the vehicle resins for the printing inks.

The principal properties, i.e. printability, required for the printing ink, particularly when to be used for offset printing are as follows: (1) The ink must have an appropriate fluidity represented by the viscosity and the yield value.

(2) A good balance should be retained at the interface between the hydrophilic portion and the ink-holding portion so as to form an image on a plane over which water and an ink contact with each other.

(3) A pigment must be uniformly dispersed in the ink.

(4) The printed face should have a beautiful gloss and uniform printed matter should be obtainable.

(5) The time required for setting or drying should be short and the ink should not suffer blocking.

(5) The printed face should have a resistance against friction. In order to prepare an offset printing ink satisfying the aforementioned properties, the vehicle resin used therein must satisfy the following requirements.

(1) It must have a high softening point but it should not have too high a molecular weight.

(2) It must have a polar group which has a good affinity with the pigment, to improve the dispersibility of the pigment.

(3) It must be easily soluble in a hydrocarbon solvent which has a high boiling point and contains only a small amount of an aromatic compound.

(4) It must have a sufficient solubility in a drying oil, such as linseed oil.

Particularly, with the development of printing technology in recent years, it is required to increase the printing speed. In reply to this requirement, the offset rotary printing process is increasingly used. In the offset rotary printing process wherein the ink is heated to dryness, it is eagerly desired to use a high boiling point hydrocarbon solvent, such as a paraffin solvent, which contains an aromatic compound in an amount as small as possible, or preferably no aromatic compound at all, to improve the environment at the working sites and to exclude the pollution problem caused by the exhaust gases. However, there has not yet been developed an offset printing ink having a satisfactory printability, as described above. Accordingly, there is an increasing demand for an offset printing ink having a satisfactory printability.

It has been already known from United States Patent No. 3,084,147 that a vehicle resin soluble in a hydrocarbon solvent, such as benzene, toluene, xylene, cyclohexane or isooctane, can be prepared by thermally polymerizing cyclopentadiene at a high temperature of from 250 to 350"C in the presence of an inert hydrocarbon solvent, such as benzene, toluene, xylenene or isooctane. The dicyclopentadiene resin prepared by this known method is soluble in a hydrocarbon solvent including benzene, toluene, xylene, solvent naphtha and Solvent No. 5 (Trade name produced by Nippon Oil Co., Ltd.). However, since this dicyclopentadiene resin has no polar group, it cannot be applied for a variety of uses due to its poor miscibility and poor adhesive property to other materials.An ink prepared by adding various solvents and pigments to the aforementioned resin is not satisfactory as an offset printing ink, since the dispersibility of pigments in the ink is unsatisfactory, leading to an uneven printed face having a bad gloss.

Another proposal has been made in Japanese Patent Provisional Publication No.

24405/1972, wherein an acrylic ester or maleic acid anhydride is added to said dicyclopentadiene resin followed by hydrolysis to prepare a carboxylic acid-containing resin, which is then reacted with a polyhydric alcohol and a higher unsaturated carboxylic acid to produce a resin for printing inks. However the resin prepared in accordance with this proposal, although it has a high softening point to give an offset printing ink to be set and dried within a time substantially equal to that required for setting and drying conventional offset printing inks, has a poor solubility in the petroleum-based hydrocarbon solvents used as the solvent for the offset printing ink. As the results, the fluidity of the ink prepared therefrom is poor and the gloss of the ink is poor.A further disadvantage of the use of this vehicle resin is that it forms gels during the preparation of a varnish, to give a cloudy varnish having a bad hue. To be useful the softening point of the resin must be lowered to improve the solubility in the solvents, resulting in prolongataion of time required for setting and drying. For these reasons, this resin is not of practical use.

Alternatively, United States Patent No. 2,608,550 discloses a resin prepared by thermally copolymerizing dicyclopentadiene and maleic acid anhydride. However, the resin taught by this prior Patent, which has a relatively low content of maleic acid, has a generally inconveniently high softening point and is poor in dispersibility of pigments and also poor in miscibility with other filler materials. If the content of maleic acid anhydride is increased to overcome the aforementioned disadvantages, there is a tendency of discolouration and gellation and the resultant resin becomes poor in its weather-proof properties.

United States Patent No. 2,608,550 discloses an alkyd resin produced from a so-called alkyd composition including a polybasic acid component consisting of a resin prepared by thermally polymerizing dicyclopentadiene with maleic acid anhydride. However, the alkyd resins taught by this prior patent have, in general, high molecular weights and poor solubilities in the high boiling point hydrocarbon solvents used for the printing inks and in drying oils. As the results, a printing ink prepared from any of these alkyd resins is poor in fluidity, inferior in gloss when printed and tends to scatter in the form of mists from the print roller to stain papers, resulting in a serious misting problem. For these reasons, the alkyd resins of this prior Patent are not of practical use.

Although a drying oil, such as linseed oil, has been used in the conventional offset printing ink varnish, the amount used tends to be decreased with the increase in printing speed to obviate the problems of staining of the ground region caused by the use of a drying oil, and to obviate the occurrence of misting and retardation of setting.

Many of the above problems and disadvantages are overcome by the present invention, which provides a printing ink composition for offset printing, comprising a vehicle resin which is prepared by reacting (a) from 5 to 100 parts by weight of a reaction product of a C49 alkyl-substituted phenol with formalin, and (b) 100 parts by weight of a modified resin that has been prepared by the action of from 1 to 1 5 parts by weight of an unsaturated carboxylic acid, an unsaturated carboxylic anhydride or a mixture thereof on 100 parts by weight of a resin which is a copolymer of (i) from 5 to 100 parts by weight of a straightchain a-olefin, a drying oil, a fatty acid or a mixture thereof, and (ii) 100 parts by weight of a cyclopentadiene compound having the general formula

in which R represents an alkyl group having from 1 to 3 carbon atoms and n is O or a whole number up to 6, or a Diels-Alder addition product thereof, optionally in admixture with an unsaturated aromatic compound.

In the composition of this invention specific examples of the cyclopentadiene compound (ii) include cyclopentadiene and methylcyclopentadiene, and examples of Diels-Alder addition products thereof include dicyclopentadiene, cyclopentadiene-methylcyclopentadiene codimer and tricyclopentadiene. Mixtures of the aforementioned compounds may be also used. Amongst these, cyclopentadiene, dicyclopentadiene and mixtures thereof are the most preferred.

It is not essential that the purity of the cyclopentadiene compound (ii) should be high.

However, it is preferred that this component should contain at least 80% by weight of cyclopentadiene, dicyclopentadiene or an alky-substituted derivative thereof. For example, it may be possible to use a concentrated fraction obtained by thermally dimerizing cyclopentadiene and/or methylcyclopentadiene contained in a C5 fraction produced by cracking naphtha at a high temperature to obtain a mixture of dicyclopentadiene, dimethylcyclopentadiene, cyclopentadiene-methylcyclopentadiene codimer, cyclopentadien-isoprene codimer and cyclopentadienepiperylene codimer, followed by removing the major part of C5 fractions such as C5 olefins and C5 paraffins by means of distillation.

Further, the cyclopentadiene compound (ii) may contain an additional unsaturated compound, particularly an unsaturated aromatic compound, in an amount less than that of the five-member cyclic compound and/or the Diels-Alder addition product thereof. For example this additional unsaturated compound may be styrene, cu-methylstyrene, vinyltoluene, indene, methylindene or a mixture thereof, and the so-called C9 fraction obtained as a by-product of the cracking of naphtha is preferred from the industrial point of view.

The component (i) used to prepare the copolymer resin, if a straight-chain a-olefin, is preferably chosen from those having 4 to 40 carbon atoms, the most preferred being chosen from those having 6 to 20 carbon atoms. Commercially available pure a-olefins may of course be used as the straight-chain a-olefins. However from the industrial point of view, it is recommended to use mixed a-olefins prepared by (1) the oligomerization of ethylene or (2) the thermal cracking of paraffin waxes.

By the oligomerization of ethylene as set forth by (1) above, straight-chain a-olefins having even numbers of carbon atoms are separated at high purity and no other isomers are contained in the separated product. By the thermal cracking of paraffin waxes as set forth by (2) above, straight-chain a-olefins are produced at a purity of about 90%, the balance being branched chain olefins, diolefins and naphthene, and the product as such may be used as copolymer component (i) in this invention without any inconvenience.

More specific examples of the a-olefins (i) include 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and mixtures thereof. An olefin mixture produced by the process as set forth by (1 ) above is commercially available from Mitsubishi Kasei Co. Ltd. under the Trade Mark of Dialene, and a product produced by the process as set forth by (2) above is commercially available from Shevron Corporation under the Trade Mark of Shevron a-Olefin. A mixture of two or more of the a-olefins described above may be used as the copolymer component (i).

The drying oils which may be used as the copolymer component (i) in this invention include vegetable and animal oils and fats having iodine values of not less than 120, those particularly preferred being drying vegetable oils, such as linseed oils, tung oil, soy-bean oil and dehydrated castor oil. The boiled oils obtained by subjecting the aforementioned drying oils to thermal processing may be used.

The fatty acids which may be used as the copolymer component (i) in this invention include saturated or unsaturated synthetic fatty acids, such as myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, and fatty acids of natural origins, such as fatty acids of linseed oil and fatty acids of tall oil. Tall oil which has a high content of fatty acids may also be used as the copolymer component (i).

A mixture of two or more of the aforementioned compounds may be used as the copolymer component (i).

The copolymer resin that is prepared from components (i) and (ii) is prepared by reacting 100 parts by weight of the component (ii) with from 5 to 100 parts, preferably 5 to 50 parts by weight of the component (i), either in the presence or absence of a catalyst. When the reaction is carried out in the absence of a catalyst, the mixture of said components (i) and (ii) is heated at 200 to 300"C for 30 minutes to 1 5 hours, preferably 1 to 7 hours, to prepare the resin.When a catalyst is used, which may be a Freidel-Crafts catalyst such as boron trifluoride, complexes thereof with phenol, ether or acetic acid, or aluminium chloride, the catalyst is preferably added to the monomer mixture in an amount of 0.1 to 10 wt.% preferably 0.3 to 2 wt. % based on the total weight of the monomers, and the mixture is reacted at a reaction temperature of from - 30"C to + 100"C, preferably from 0 C to 50"C, for a reaction time of from 10 minutes to 20 hours, preferably from 1 to 1 5 hours.

The copolymer resin prepared as above is further modified by the action of an unsaturated carboxylic acid, an unsaturated carboxylic acid anhydride or a mixture thereof, to provide the modified resin (b). Preferred examples of the unsaturated carboxylic acids and anhydrides thereof which may be used in this invention include monohydric or polyhydric unsaturated carboxylic acids and anhydrides thereof having generally 3 to 32, more preferably 3 to 15, carbon atoms. For example, the unsaturated acids and anhydrides may be acrylic acid, methacrylic acid, maleic acid, maleic acid anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, fumaric acid, citraconic acid, itaconic acid, fatty acids of drying oils such as fatty acids of linseed oil, and mixtures thereof. The most preferable are maleic acid and maleic acid anhydride.

The amount of the unsaturated carboxylic acid or anhydride used to achieve the necessary modification of the copolymer resin is such that 1 to 1 5 parts, preferably 1 to 10 parts, by weight of the acid or anhydride is added to 100 parts by weight of the copolymer resin. The modification treatment is preferably effected at a temperature of from 100 to 300"C, preferably 150 to 250"C, in the presence of a known radical reaction initiator, such as an organic peroxide, for from 30 minutes to 1 5 hours, preferably 1 to 8 hours. If an unsaturated polycarboxylic acid or an hydride thereof is used, it is preferred that the reaction be carried out without using a catalyst.If an unsaturated monocarboxylic acid or an anhydride thereof is used, it is preferred that the reaction be carried out in the presence of a catalyst.

The modified resin (b) may be produced by a one-step process which comprises adding the unsaturated carboxylic acid or anhydride thereof at an initial or intermediate stage of the step for thermally polymerizing the mixture of the components (i) and (ii), and thermally polymerizing the mixture at a temperature of from 200 to 300"C in the presence or absence of a solvent.

The modified resin (b) may if desired be further modified by esterification with an alcohol to control the solubility and softening point of the resultant resin (b) or to control the molecular weight of the final vehicle resin. The alcohols used for this purpose include monohydric and polyhydric alcohols. Monohydric alcohols having not less than 6 carbon atoms, preferably 8 to 1 8 carbon atoms, are particularly preferred to improve the solubility of the final vehicle resin.

The quantity of the alcohol is preferably such that the molar ratio of the carboxylic groups to the alcohol groups contained in the modified resin (b) is up to 1:1 and the molar ratio of the carboxylic acid anhydride group to the alcohol group contained in the modified resin (b) is up to 1:2. The esterification may be effected firstly by heating to melt the modified resin (b) or dissolving the same in a hydrocarbon solvent, such as benzene, toluene or xylene, follwed by the addition of the alcohol, and reacting at 150 to 250"C for from 30 minutes to 10 hours, preferably from 1 to 1 5 hours.

The vehicle resin is prepared by reaction of the above modified resin (b) with an alkylsubstituted phenolic resin (a). The phenolic resin (a) is a condensation reaction product of a phenol which includes alkyl substituent groups having 4 to 9 carbon atoms, with formalin.

Specific examples of industrially preferred phenols include p-tert-butylphenol, sec-butylphenol, ptert-octylphenol and nonylphenol.

Instead of reacting the modified resin (b) with a previously prepared phenolic resin (a), the resin (a) may be prepared in situ by reacting the substituted phenol and formaldehyde in the presence of the modified resin (b) using an acid or alkali catalyst or without using a catalyst to obtain the intended vehicle resin.

5 to 100 parts, preferably 10 to 50 parts, by weight of the phenolic resin (a) are used, per 100 parts by weight of the modified resin (b). The reaction may be effected simply by mixing the modified resin (b) with the phenolic resin (a) to obtain a mixture which is melted and heated at 150 to 250"C for fromm 30 minutes to 10 hours, peferably from 1 to 5 hours. If necessary, an acid catalyst, such as oxalic acid, toluenesulphonic acid or a Friedel-Crafts catalyst, or an alkali catalyst, such as a metal oxide or metal hydroxide or ammonia, may be used.

It is desirable that the vehicle resin should have a osftening point of not lower than 100"C, preferably higher than 130"C. If the softening point of the vehicle resin is lower than 1 O0'C, the printing ink prepared therefrom is apt to suffer misting and blocking and the drying speed of the printing ink is extremely lowered.

It is also desirable that the acid value of the vehicle resin be 5 to 50, preferably 5 to 20. If the acid value of the vehicle resin is lower than the aforementioned range, the printing ink prepared therefrom has a poor solubility. On the contrary, if the acid value of the vehicle resin exceeds the aforementioned range, the solubility thereof in paraffin solvents becomes poor and the offset printing ink prepared therefrom has a poor resistance to emulsification.

The offset printing ink of this invention may be prepared from the above vehicle resin in accordance with any known method. For instance, 100 parts by weight of the vehicle resin may be dissolved at room temperature or under heating in a mixture composed of 50 to 200 parts by weight of a high boiling point hydrocarbon solvent and 0 to 1 50 parts, preferably 5 to 50 parts, by weight of a drying oil to prepare a varnish having a viscosity of 200 to 600 poises at room temperature. An ink composition according to this invention may be obtained by adding one or more pigments to the varnish and kneading by means of rollers or other kneaders.

The high boiling point hydrocarbon solvents which may be used to formulate the ink should have boiling points ranging from 200 to 350"C, preferably 250 to 330"C, and the aromatic content thereof is preferably not higher than 50 wt.%, peferably less than 30 wt.%. Particularly preferred solvents are high boiling point paraffin solvents having boiling points ranging within 200 to 350"C and containing substantially no aromatic compounds. As the oily component, long oil alkyd resins may be used, other than drying oils such as linseed oil and tung oil.

EXAMPLES The invention is illustrated by the following Synthesis Examples, illustrating the preparation of vehicle resins for use in the formation of printing inks according to the invention, and in the following Examples, illustrating the preparation of printing inks therefrom.

Synthesis Example 1 820 g of 97% dicyclopentadiene and 180 g of 1-hexene were charged into an autoclave having a capacity of 2 liters, and heated to 260"C for 5 hours in the nitrogen atmosphere under agitation. The autoclave was cooled after the completion of heating, and the content in the autoclave was distilled at 210"C/2 mmHg to remove unreacted materials and oligomers. 893 g of a resin was left in the autoclave. The softening point of the resin was 139.0 C.

100 g of the resin was heated to 200"C to melt the same, and added with 3.0 g of maleic acid anhydride and reacted for 4 hours under agitation to obtain a modified resin (MR-1) modified with maleic acid anhydride. The softening point of the modified resin (MR-1) was 151.0 C and the acid value thereof was 13.7. Subsequently, 85g of the modified resin (MR-1) was added with 1 5g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin, and reacted at 200"C for 2 hours, whereby a Vehicle Resin (VR-1) having a softening point of 173.5"C and an acid value of 13.0 was obtained.

Synthesis Example 2 760g of 97% dicyclopentadiene and 2409 of 1-decene were charged into an autoclave having a capacity of 2 liters, and reacted at 280"C for 5 hours. The following procedures were similar to Synthesis Example 1 to obtain 930g of a Resin. The softening point of the Resin was 137.0 C.

100g of the resin was heated to 200"C to melt the same, and added with 5.0g of maleic acid anhydride and reacted for 3 hours under agitation to obtain a modified resin modified with maleic acid anhydride. The softening point of the modified resin was 152.O"C, and the acid value thereof was 24.3. Subsequently, 829 of the modified resin was added with 3.09 of decanol and heated at 200"C for one hour, and then added with 21 g of a resol-type phenolci resin which had been prepared by the condensation reaction between p-nonylphenol and formalin. The admixture was reacted at 200"C for 3 hours to obtain a Vehicle Resin (VR-2) having a softening point of 165.5"C and an acid value of 19.6.

Synthesis Example 3 7909 of 97% dicyclopentadiene and 210 g of an a-olefin mixture consisting of a-olefins having 6 to 10 carbon atoms (Dialene 610 produced by Mitsubishi Kasei Co., Ltd.) were charged in an autoclave having a capacity of 2 liters, and reacted at 280"C for 2.5 hours. The following procedures were similar to Synthesis Example 1 to obtain 9209 of a Resin having a softening point of 143.0 C.

1009 of the Resin was heated to 200"C to melt the same, added with 3.09 of maleic acid anhydride, and reacted for 4 hours under agitation to obtain a Modified Resin The softening point of the Modified Resin was 155.O"C, and the acid value thereof was 13.9. Subsequently, 859 of the Modified Resin (11-3) was added with 159 of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-butylphenol and formalin, and reacted at 220"C for 2 hours to obtain a Vehicle Resin (VR-3) having a softening point of 183.5"C and an acid value of 13.1.

Synthesis Example 4 The by-product C5 fraction (Boiling Point: 28"-60"C) obtained at the step of producing ethylene and propylene through steam cracking of naphtha was heated at 120"C for 4 hours and distilled to remove the unreacted C5 fraction to obtain a mixture containing 85% of dicyclopentadiene and the remainder of codimers of cyclopentadiene with isoprene or piperylene. 8509 of this mixture containing 85% of dicyclopentadiene and 150g of 1-decene were charged into an autoclave having a capacity of 2 liers, and reacted at 260"C for 6 hours. The following procedures were similar to Synthesis Example 1 to obtain 8409 of a Resin having a softening point of 135"C.

1009 of the Resin was heated to 200"C to melt the same, added with 4.09 of maleic acid anhydride, and reacted for 4 hours under agitation to obtain a Modified Resin modified with maleic acid anhydride. The softening point of the Modified Resin was 144.5 C and the acid value thereof was 17.7. Subsequently, 90g of the Modified Resin was added with 3.09 of 2ethylhexanol, and heated and agitated at 200"C for one hour. Then, 16.49 of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octyphenol and formalin was added, and reacted at 200'C for 3 hours to obtain a Vehicle Resin (VR-4) having a softening point of 158.5"C and an acid value of 16.0.

Comparative Synthesis Example 1 10009 of 97% dicyclopentadiene and 400g of xylene which acted as a solvent were charged into an autoclave having a capacity of 2 liters, and reacted at 260"C for 2 hours. The following procedures were similar to Synthesis Example 1 to obtain 820g of a Resin having a softening point of 150"C.

1009 of the Resin was heated to 200"C to melt the same, added with 3.09 of maleic acid anhydride, and reacted for 4 hours to obtain a Modified Resin The softening point of the Modified Resin was 159.5"C and the acid value thereof was 13.0. Subsequently, 85g of the Modified Resin was added with 1 5g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin, and reacted at 200"C for 2 hours to obtain a Vehicle Resin (VR-a) having a softening point of 176.5"C and an acid value of 12.7.

Comparative Synthesis Example 2 1009 of the Resin obtained in Synthesis Example 1 was heated to 200"C to melt the same, and added with 25g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin. The mixture was heated and agitated at 200"C for 2 hours to obtain a Vehicle Resin (VR-6) having a softening point of 169.0 C.

Comparative Synthesis Example 3 8009 of 97% dicyclopentadiene and 2009 of 2,4-dimethyl-1-heptene having methyl group branched from a double bond portion and obtained by trimerization of propylene were charged into an autoclave having a capacity of 2 liters, and reacted at 280"C for 5 hours. The content in the autoclave was distilled at 210"C/2 mmHg to remove unreacted materials and oligomers.

After distillation, 7809 of a Resin was left in the autoclave. The softening point of the Resin was 145"C.

1009 of the Resin was heated to 200"C to melt the same, added with 3.09 of maleic acid anhydride, and reacted for 4 hours to obtain a Modified Resin. The softening point of the Modified Resin was 158.O"C and the acid value thereof was 14.0. Subsequently, 859 of the Modified Resin was added with 1 5g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin, and reacted at 200"C for 2 hours to obtain a Vehicle Resin (VR-c) having a softening point of 178.0 C and an acid value of 13.0.

EXAMPLES I to 4 and COMPARATIVE EXAMPLES 1 to 5 Varnishes were prepared by using the Vehicle Resins obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 to 3 and also using the Modified Resin (MR-1) obtained in Synthesis Example 1 and a control resin. Inks were prepared by using these varnishes, and the properties of the inks were tested. The test results are shown in the following Table I under the captions of Examples 1 to 4 and Comparative Examples 1 to 5.

Preparation of Varnish: 58g of each of the vehicle resins was added with 10g of linseed oil and 20-409 of a high boiling point paraffin solvent (NISSEKI Solvent No. O-H see Remark 1 given below), and heated to 180"C to melt the reisn to prepare a varnish having a viscosity of 300-400 poises.

Preparation of Ink: Using each of the varnishes, an ink was prepared in accordance with the following prescription, using a mixing roller assembly composed of three rollers.

Prescription of Ink: Pigment (Carmine 6B: see Remark 2 given below) 1 4 grams Varnish 50 grams Solvent (NISSEKI Solvent No.0-H 1 5 grams Test Method and Test Result on the Properties of Ink: Gloss: 0.4 cc of each ink was applied on art paper, using an RI Tester (see Remark 3 given below), and dried for 10 seconds in an overn maintained at 150"C. The gloss of the dried ink was determined using a 60 degrees 60 degrees glossmeter.

Drying Time: 0.4 cc of each ink was applied on parchment paper, using the aforementioned RI Tester, and dried in an oven maintained at 150do. The time until the ink had reached the state at which the ink did not stick to a finger was measured.

Misting: 2.4 cc or each ink was put on an Inkometer (Trade Mark) (see Remark 4 given below) rotating at 1 200 rpm. Scattering of ink on the art paper spread beneath the roller after the lapse of 3 minutes was observed.

Ernulsification Property of Ink: Water was added to each of the prepared inks to emulsify the ink, and the fluidity of emulsified ink was determined. Offset printing inks are, in general, partially emulsified when they contact with water at the printing step. Only the inks which give emulsions having good fluidity can be applied for practical uses.

Remark 1: A pure paraffinic hydrocarbon solvent having boiling points of 250"-265"C and containing no aromatic compound, and produced by Nippon Oil Company Limited.

Remark 2: Produced by Toyo Ink Mfg. Co., Ltd.

Remark 3: A tester for testing printability and produced by Akira Seisakusho Co., Ltd.

Remark 4: Produced by Toyo Seiko Co., Ltd.

Table I Viscosity Gloss of Dryin Emulsification Used of Varnish Appearance the Printed Time Property of Resin (Poise, at 25 C) of Varnish Face (Sec.) Misting Ink Example 1 VR-1 537 Clear 71 8 Not-observed Good Example 2 VR-2 581 Clear 67 6 Not-observed Good Example 3 VR-3 589 Clear 67 7 Not-observed Good Example 4 VR-4 528 Clear 65 6 Not-observed Good The solubility of the resin in a paraffin solvent was so poor that a Comp. clear varnish was not prepared and no ink composition could be prepared Ex. 1 VR-a therefrom.

Comp. Cloudy Ex. 2 VR-b 551 Bad Hue 41 17 Oserved Poor Comp.

Ex. 3 MR-1 516 Cloudy 52 12 Observed Poor Comp. Control Ex. 4 Resin* 586 Clear 66 7 Not-observed Rather Poor Comp.

Ex. 5 VR-c 570 Cloudy 50 10 Not-observed Rather Poor *Note: Control Resin: A phenolic resin modified with rosin available from Arakawa Chemical Co., Ltd. under the Trade Name of Tamanol &num;361.

As shown in Examples 1 to 4 set forth in Table I, the offset printing ink compositions according to this invention are excellent in gloss and good in emulsification, misting and drying properies. It should be clear from Table I that the vehicle resins according to this invention give excellent offset printing ink compositions when dissolved in paraffin solvent.

As will be apparent from Comparative Example 1, a uniform ink composition cannot be prepared from a vehicle resin which does not contain an a-olefin since the solubility of such a resin in a solvent is poor.

Comparative Example 2 is an exemplified ink composition prepared by using a resin which has not been modified with an acid, and shows that the drying and emulsification properties of such an ink are inferior since the modification reaction with a phenolic resin is incomplete to give a resin, the softening point of which is too low.

In comparative Example 3, a resin which has not been modified with a phenolic resin is used.

This Comparative Example shows that such a resin cannot be used to prepare an ink for practical application since the ink is unsatisfactory in gloss, drying time and emulsification property.

In Comparative Example 4, an ink is prepared by using a phenolic resin modified with rosin which is excellent in solubility in a paraffin solvent. When comparing this Comparative Example with the Examples of this invention, it should be noted that the emulsification property of the offset printing ink compositions according to this invention are improved over the conventional ink composition prepared by using a phenolic resin modified with rosin.

The vehicle resin used in Comparative Example 5 is prepared by using 2,4-dimethyl-1-heptene having a branched chain on a double bond portion as the a-olefin. As will be understood from this Comparative Example, a compound having a branched chain on a double bond portion is relatively inactive and hardly introduced into the resin. As a result, the solubility of the resultant resin in a paraffin solvent is unsatisfactory to make it difficult to prepare a clear varnish. It is also shown that the gloss of the printed face is not satisfactory.

Synthesis Example 5 850g of 97% dicyclopentadiene and 250g of linseed oil were charged into an autoclave having a capacity of 2 liters, and heated at 260"C for 3.5 hours in the nitrogen atmosphere under agitation. The autoclave was cooled after the completion of heating, and the content in the autoclave was distilled at 210"C/2 mmHg to remove the unreacted materials and oligomers.

920g of a resin (R-5) was left in the autoclave. The softening point of the resin (R-5) was 136.5"C.

150g of the resin (R-5) was heated to 200"C to melt te same, added with 4.5g of maleic acid anhydride, and reacted for 4 hours under agitation to obtain a modified resin (MR-5) modified with maleic acid anhydride. The softening point of the modified resin (MR-5) was 147.0 C and the acid value thereof was 13.5. Subsequently, 1 00g of the modified resin (MR-5) was added with 1 7.6g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin, and reacted at 200"C for 2 hours to obtain a Vehicle Resin (VR-5) having a softening point of 169.5"C and an acid value of 12.7.

Synthesis Example 6 800g of 97% dicylopentadiene and 200g of tall oil were charged into an autoclave having a cpacity of 2 liters, and reacted at 260"C for 6 hours. The following procedures were similar to Synthetic Example 5 to obtain 925g of a resin. The softening point of the resin was 138.5"C.

150g of the resin was heated to 200"C to melt the same, added with 7.sag of maleic acid anhydride and reacted for 3 hours under agitation to obtain a modified resin modified with maleic acid anhydride. The softening point of the modified resin was 158.0 and the acid value thereof was 24.2. Subsequently, 100g of the modified resin was added with 4.2g of decanol, an heated and agitated at 200"C for one hour. Then, 20.2g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-nonylphenol and formalin was added, and reacted at 200"C for 3 hours to obtain a Vehicle Resin (VR-6) having a softening point of 160.5"C and an acid value of 19.4.

Synthesis Example 7 800g of 97% dicyclopentadiene, 100g of linseed oil and 100g of 1-hexene were charged into an autoclave having a capacity of 2 liters, and reacted at 280"C for 2 hours. The following procedures were similar to Synthesis Example 5 to obtain 932g of a resin having a softening point of 146.0 C.

150g of the resin was heated to 200"C to melt the smae, added with 4.5g of maleic acid anhydride, and reacted for 3 hours under agitation to obtain a modified resin modified with maleic acid anhydride. The softening point of the modified resin was 155.0 C and the acid value thereof was 13.7. Subsequently, 1009 of the modified resin was added with 17.6g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert octylphenol and formalin, and reacted at 200"C for 2 hours to obtain a Vehicle Resin (VR-7) having a softening point of 175.0 C and an acid value of 1 2.2.

Synthesis Example 8 The by-product C5 fraction (Boiling Point: 28 to 60 C) obtained at the step of producing ethylene and propylene through steam cracking of naphtha was heated at 120"C for 4 hours and distilled to remove the unreacted C5 fraction to obtain a mixture containing 85% of dicyclopentadiene and the remainder of codimers of cyclopentadiene with isoprene of piperylene. 8509 of this mixture containing 85% dicyclopentadiene and 250g of linseed oil were charged in an autoclave having a capacity of 2 liters, and reacted at 260"C for 4 hours. The following procedures were similar to Synthesis Example 5 to obtain 8729 of a resin having a softenting point of 137.O'C.

150g of the resin was heated to melt the same, added with 5.39 of maleic acid anhydride, and reacted for 4 hours under agitation to obtain of a modified resin.

The softening point of the modified resin was 148.5 C and the acid value thereof was 16.9.

Subsequently, 1009 of the modified resin was added with 3.09 of 2-ethylhexanol, and heated and agitated at 200"C for 2 hours. Then, 18.29 of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin was added, and reacted at 200 C for 2 hours to obtain a Vehicle Resin (VR-8) having a softening point of 157.5 C and an acid value of 14.1.

Comparative Synthesis Example 4 10009 of 95% dicyclopentadiene and 4009 of xylene which acted as a solvent were charged into an autoclave having a capacity of 2 liters, and reacted at 260"C for 3 hours. The following procedures were similar to Synthesis Example 5 to obtain 800g of a resin having a softening point of 152.0 C.

150g of the resin was heated at 200"C to melt the same, added with 5.39 of maleic acid anhydride, and reacted for 3 hours under agitation to obtain a modified resin. The softening point of the modified resin was 165.0 C and the acid value thereof was 16.5. Subsequently, 1009 of the modified resin was added with 3.09 of decanol, and heated and agitated at 200 C.

Then, 1 8.2g of a resol-type phenolic resin which had been prepared by the condensation reaction between p-ter-obtylphenol and formalin was added, and reacted at 200"C for 2 hours to obtain a Vehicle Resin (VR-d) having a softening point of 170.5 C and an acid value of 13.9.

Comparative Synthesis Example 5 1009 of the resin (R-5) obtained in Synthesis Example 5 was heated to 200 C to melt the same, and added with 17.69 of a resol-type phenolic resin which had been prepared by the condensation reaction between p-tert-octylphenol and formalin. The mixture was heated and agitated at 200 C for 2 hours to obtain a Vehicle Resin (VR-e) having a softening point of 155.0 C.

EXAMPLES 5 to 8 and COMPARATIVE EXAMPLES 6 to 9 Varnishes were prepared by using the Vehicle Resins obtained in Synthesis Examples 5 to 8 and Comparative Synthesis Examples 4 and 5 and also using the Modified Resin (MR-5) of Example 5 and a control resin. Inks were prepared by using these varnishes, and the properties of the inks were tested. The test results are shown in the following Table II under the captions of Examples 5 to 8 and Comparative examples 6 to 9.

Preparation of Varnish: 50g of each of the vehicle resins was added with 20g of linseed oil, and heated at 240 C for 90 minutes, Then, and appropriate amount ranging within 20 to 409 of a petroleum hydrocarbon solvent (NISSEKI Solvent No. 5: see Remark 5 given below) to control the viscosity of the resultant varnishes within the range of 500 to 600 poises.

Preparaz-ion of Ink: Using: each of the varnishes, an ink was prepared in accordance with the following prescripSon, using a mixing roller assembly composed of three rollers.

Prescription of Ink: Pigment (Carmine 6B; see Remark 2 given in previous Examples) 14 grams Varnish 50 grams Solvent (NISSEKI Solvent No. 5) 5 grams Wax Compound 2 grams Drier (Cobalt Naphthenate) 0.3 grams Test Method and Test Result of the Properties of Ink: Gloss: 0.4 cc of each ink was applied on art paper, using the RI Tester (See Remark 3 given in the previous Examples) and allowed to stand for 24 hours. To gloss of the dried ink was determined, using a 60 degrees-60 degrees glossmeter.

Setting Time: 0.4 cc of each ink was applied on a sheet of art paper, using the aforementioned RI Tester, and another blank sheet of art paper was overlaid on the inked face and pressed, using the roller of the RI Tester. The interval of time from the time at which the ink was applied to the time at which the blank sheet of art paper was overlaid on the inked face was varied to find the interval of timer required for the ink not to stick to the blank sheet of art paper.

Misting: 2.4 cc of each ink was put on the Inkometer (see Remark 4 given in the previous Examples) rotating at 1 200 rpm. Scattering of ink on the art paper spread beneath the roller after the lapse of 3 minutes was observed.

Drying Time: 0.4 cc of each ink was applied on a sheet of art paper using the aforementioned RI Tester, and the time required for the ink to be dried was determined, using a tester for detecting the dryness of ink (see Remark 6 given below).

Emusification Property of Ink: Water was added to each of the prepared inks to emulsify the ink, and the fluidity of emulsified ink was determined. Offset printing inks are, in general, partially emulsified when they contact with water at the printing step. Only the inks which give emulsions having good fluidity can be applied for practical uses.

Control Resin: A phenolic resin modified with rosin produced by Dainippon Ink 8 Chemical Co., Ltd. and commercially available under the Trade Name of Beckacite 1126HV.

Remark 5: A solvent for ink having boiling points of 276 311 or and containing 23 wt.% of aromatic compounds, and produced by Nippon Oil Company Limited.

Remark 6: A tester produced by Toyo Seiki Co., Ltd.

Table II Viscosity of Setting Drying Emulsification Varnish Gloss of the Time Time Property of Used Resin (poise, at 25 C) Printed Face (min.) (hr.) Misting Ink Example 5 VR-5 570 61 6 3.0 Not-observed Good Example 6 VR-6 550 62 6 3.0 Not-observed Good Example 7 VR-7 560 66 8 3.0 Not-observed Good Example 8 VR-8 520 62 6 3.0 Not-observed Good Comp.

Ex. 6 VR-d 510 46 7 3.0 Observed Rather Poor Comp.

Ex. 7 VR-e 570 46 6 3.0 Observed Rather Poor Comp.

Ex. 8 MR-5 590 44 10 4.5 Observed Poor Comp.

Ex. 9 Control Resin 550 57 6 3.0 Not-observed Rather poor Referring to Examples 5 to 8 shown in Table II, it should be clear that the offset printing ink compositions according to this invention are excellent in gloss and good in emulsification, misting, setting and drying properties.

In contrast thereto, an ink using a vehicle resin which contains neither a drying oil nor a fatty acid component is unsatisfactory in that the gloss of the printed face is poor with attendant misting and in that the emulsification property thereof is unsatisfactory, as will be clear from Comparative Example 6 shown in the Table.

Comparative Example 7 is an exemplified ink composition prepared by using a resin which has not been modified with an acid, and shows that the gloss and emulsification property of such an ink are unsatisfactory and that the resin suffers misting.

In Comparative Example 8, a resin which has not been modified with a phenolic resin is used.

This Comparative Example shows that an ink prepared by using such a resin is unsatisfactory in gloss, settling, drying and emulsification properties and suffers misting.

In Comparative Example 9, an ink is prepared by using a known control resin commonly used in the art. This known resin is a phenolic resin modified with rosin. It will be understood by comparing the examples of this invention with this Comparative Example that the gloss and emulsification property of the offset printing ink compositions according to this invention are improved over those of the conventional ink composition prepared by using the known phenolic resin modified with rosin.

Claims (15)

1. A printing ink composition for offset printing, comprising a vehicle resin which is prepared by reacting (a) from 5 to 100 parts by weight of a reaction product of a C49 alkyl-substituted phenol with formalin, and (b) 100 parts by weight of a modified resin that has been prepared by the action of from 1 to 1 5 parts by weight of an unsaturated carboxylic acid, an unsaturated carboxylic anhydride or a mixture thereof on 100 parts by weight of a resin which is a copolymer of (i) from 5 to 100 parts by weight of a straight-chain a-olefin, a drying oil, a fatty acid or a mixture thereof, and (ii) 100 parts by weight of a cyclopentadiene compound having the general formula

in which R represents an alkyl group having from 1 to 3 carbon atoms and n is 0 or a whole number up to 6, or a Diels-Alder addition product thereof, optionally in admixture with an unsaturated aromatic compound.

2. A printing ink composition according to claim 1, wherein the copolymer component (ii) is cyclopentadiene, methylcyclopentadiene, dicyclopentadiene, cyclopentadiene-methylcyclopentadi- ene codimer, tricyclopentadiene or a mixture thereof.

3. A printing ink composition according to claim 1, wherein the copolymer component (ii) is a concentrated distillate obtained by removing the major part of C5-fractions from a mixture prepared by the thermal dimerization of cyclopentadiene and methylcyclopentadiene contained in the Cs-fractions of by-product cracked oils obtained by thermally cracking naphtha.

4. A printing ink composition according to any preceding claim, wherein the copolymer component (ii) comprises the cyclopentadiene compound and/or the Diels-Alder addition product thereof in admixture with an unsaturated aromatic compound in an amount not more than the amount of the cyclopentadiene compound and/or the Diels-Alder addition product thereof.

5. A printing ink composition according to any preceding claim, wherein the copolymer component (i) comprises a straight-chain a-olefin with from 4 to 40 carbon atoms.

6. A printing ink composition according to claim 5, wherein the straight-chain a-olefin is 1hexene, 1-heptene, 1-octene, 1-nonene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octade- cene, 1-eicosene or a mixture thereof.

7. A printing ink composition according to any preceding claim, wherein the copolymer component (i) comprises a drying oil having an iodine value of not less than 1 20 and selected from the group consisting of vegetable oils and fats, animal oils and fats and mixtures thereof.

8. A printing ink composition according to claim 7, wherein the drying oil is linseed oil, tung oil, soy-bean oil, dehydrated castor oil, boiled linseed oil, boiled tung oil, boiled soy-bean oil, boiled dehydrated castor oil or a mixture thereof.

9. A printing ink composition according to any preceding claim, wherein the copolymer component (i) comprises a fatty acid selected from the group consisting of myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, fatty acids of linseed oil, fatty acids of tall oil, tall oil mainly composed of fatty acids and mixtures thereof.

1 0. A printing ink composition according to any preceding claim, wherein the acid or acid anhydride used to obtain the modified resin (b) is acrylic acid, methacrylic acid, maleic acid, maleic acid anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, fumaric acid, citraconic acid, itaconic acid, a fatty acid of a drying oil or a mixture thereof.

11. A printing ink composition according to any preceding claim, wherein the modified resin (b) is further modified by esterification with a monohydric or polyhydric alcohol.

12. A printing ink composition according to any preceding claim, wherein the phenol used to prepare component (a) of the vehicle resin is p-tert-butylphenol, sec-butylphenol, p-tert octylphenol, nonylphenol or a mixture thereof.

1 3. A printing ink composition according to any preceding claim, further comprising 50 to 200 parts by weight of a hydrocarbon solvent having a boiling point of from 200" to 350'C, and 0 to 150 parts by weight of a drying oil, the content of aromatic compounds in said hydrocarbon solvent being less than 50% by weight.

1 4. A printing ink composition according to claim 13, wherein the hydrocarbon solvent is a paraffin.

15. A printing ink composition for offset printing, comprising a vehicle resin substantially as described in any of Synthesis Examples 1 to 8 herein.

1 6. A printing ink composition for offset printing, substantially as described in Examples 1 to 8 herein.