GB2456564A

GB2456564A - Environmentally friendly printing ink compositions

Info

Publication number: GB2456564A
Application number: GB0800975A
Authority: GB
Inventors: Carlton Nix
Original assignee: Sun Chemical Ltd
Current assignee: Sun Chemical Ltd
Priority date: 2008-01-18
Filing date: 2008-01-18
Publication date: 2009-07-22
Also published as: GB0800975D0

Abstract

A printing ink is compostable to European standard EN13432. The ink preferably includes a solvent e.g. water, ethanol, ethyl acetate; a binder resin e.g. a rosin, a soybean protein; and a pigment e.g. talc, chalk, kaolin. Also shown is a packaging material having the printing ink printed on it.

Description

£ Intellectual D Property Offic 3zc

For Cre .'ivily and Innovation

Application No. GB0800975.5 R.TM : 12 May 2008

The following terms are registered trademarks and should be read as such wherever they occur in this document:

EDENOL, TEXAPRINT, FOAMASTER, TEGO, LARAPRINT, EUROVIT

UK Intellectual Property Office is am operating name of The Patent Office

2456564

ENVIRONMENTALLY FRIENDLY INK COMPOSITIONS

The present invention relates to an environmentally friendly printing ink composition.

5 In recent years, attention has increasingly focussed on the impact of human activity on the environment, and much effort has gone into minimising this impact and avoiding the discharge of toxic, damaging, or merely undesirable, materials into the environment.

Packaging materials are among the most wasteful, and, in many ways, 10 dangerous, of materials. Although often presented as unnecessary, they are needed to carry or protect goods or to identify or secure them in shops. Accordingly, attempts axe regularly made to minimise their environmental impact, with varying, although to date, small, degrees of success.

No-one can be unaware of the pressure currently to avoid the use of plastic 15 carrier bags - this demonstrates one option for dealing with the problem, which is to educate the public, a process to which the public can sometimes be sadly resistant. Another option is to encourage reuse of such materials, an option which is also demonstrated by plastic carrier bags, where many supermarkets now offer the shopper the option of buying or even being given stronger and reusable bags.

20 A further option is to replace non-biodegradable materials with biodegradable ones. Thus, instead of making packaging out of a material that will merely be used for land fill and which will remain intact for centuries or even millennia, materials that can be digested by natural processes, ideally by composting, are used, thus not merely avoiding yet more land fill, but actually producing a useful product, the compost. The 25 European standard EN13432, for example, provides a standard for compostability which several packaging manufacturers are aiming to achieve or, indeed, have achieved.

In order to meet the requirements of this standard in relation to packaging, it is not necessary that each individual component of the packaging should meet its

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requirements, rather the packaging as a whole must meet its requirements. Thus,

printed matter can meet the standard even though the ink used on the packaging itself does not. To date, where there has been an attempt to ensure that packaging meets the standard, this has been achieved by keeping the amount of ink below the percentage that 5 would trigger failure to meet the standard. Since inks commonly contain many petrochemical-derived materials, the inks used to date themselves would not meet the standard, and certainly would not be compostable. However, this has not been considered a problem since it has been possible to reduce the amount of ink so that the amount commonly used is very small in relation to the amount of substrate.

10 Nevertheless, we believe that it would be desirable to be able to compost the whole of such materials, including the ink, completely, and we have now surprisingly found that it is possible to make an ink which is perfectly compostable according to European standard EN13432.

Thus, the present invention consists in a printing ink which is compostable to 15 European standard EN13432.

Hereafter, where reference is made to a material being "compostable", this means that it is compostable to European standard EN13432.

A printing ink will contain at least the following components:

a solvent;

20 a binder resin;

a pigment.

However, in practice, several other components will also be present, as described in more detail hereafter. In order to achieve the desired compostability, we prefer that all of the materials used should be themselves compostable, although, in 25 actual practice, an ink may be acceptable provided that at least 50%, more preferably at least 80%, and most preferably 100%, of the dry ink film by weight of the components of the ink are compostable. Nonetheless, it is preferred that as much of the ink as possible should be compostable.

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We also prefer that the components of the ink, or at least 50%, more preferably 80%, and most preferably 100%, of the dry ink film by weight of the components of the ink should be of natural origin, i.e. derived from natural products, other than products of the petrochemical industry, by simple separation or purification steps. Indeed, it is 5 preferred that as much of the ink as possible should be of natural origin, and most preferably essentially the whole of the components of the ink is of natural origin.

The nature of the solvent will depend on the resin chosen. However, it is preferred that the solvent should be water and so the resin is preferably chosen to enable this. Alternatively, where an organic solvent is required, this may be, for example, 10 ethanol or ethyl acetate. Preferably, the ethanol would be bioethanol, and the ethyl acetate would be naturally derived, for example from molasses. The solvent will preferably comprise from 50 to 70% by weight of the ink.

The nature of the binder resin will depend on the solvent used. In the case of a water-based ink, preferred resins include shellac, polysaccharide resins, 15 arabinogalactans, soybean proteins, or rosins (including tree rosin, copal and sandarac), of which sandarac is particularly preferred. In the case of solvent-based inks, preferred resins include: shellac, zein corn protein, tree rosin, sandarac or dammar. The resin will preferably comprise from 1 to 20% of the ink.

The third essential ingredient of the ink is a colorant. This may be a dye or 20 pigment. Examples include: carmine lake natural red 4 (cochineal), natural yellow 3 lake (from plants), madder lake natural red 9 (madder root), indigo lake natural blue 2 (woad), chlorophylin green lake (plant matter), vegetable or bone black, titanium white, iron oxides, talc, chalk, kaolin and other earth pigments. The colorant will preferably comprise from 1 to 20% by weight of the ink.

25 Optional components of the inks include:

waxes, for both water- and solvent- based inks, preferably carnauba wax or candelilla wax, and preferably in an amount of from 0.5 to 2% by weight of the ink;

plasticisers, for both water- and solvent- based inks, for example glycerol, castor oil, or other plant oil derivatives such as those sold under the trade names Edenol EFC

100 (ex Cognis Corporation), AEP 100 (ex Chimista, LLC), AEP 200 (ex Chimista, LLC) or Texaprint SDM (ex Cognis Corporation), preferably in an amount of from 1 to 5% by weight of the ink;

surfactants, for both water- and solvent- based inks, for example Lipotin A (ex Evonik Industries, a soya derivative) or Saponin surfactant (a natural plant surfactant), preferably in an amount of from 0.2 to 2% by weight of the ink.

In the case of water-based inks, further optional components may be present, for example:

anti-foaming agents, such as Foamaster 350 (a triglyceride ex Cognis Corporation) or Tego LA-E 685 (a natural vegetable oil ex Evonik Industries), preferably in an amount of from 0.2 to 1% by weight of the ink;

amines, such as ammonia, 2-dimethylamino-2-methyl-l-propanol (DMAMP) or monoethanolamine (MEA), preferably in an amount of from 1 to 5% by weight of the ink; and other additives, such as eucalyptus oil, or other antimicrobials, preferably in an amount of from 0.2 to 1% by weight of the ink.

The ink may be manufactured by simple mixing or by bead-milling if necessary in the usual way for this type of ink and may be used in various types of printing process, for example flexographic printing.

There is no particular restriction on the nature of the substrate on which the printing ink of the present invention is used. However, we prefer that this substrate should, like the printing ink, be compostable to European standard EN13432. The substrate may, for example, be a paper or cardboard, or it may be a plastics material.

The invention is further illustrated by the following non-limiting Examples.

EXAMPLES 1-4

The ingredients listed in the following Table 1 were mixed to form inks:

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Table 1

Material

Supplier

Comment

Ex.1

Ex.2

Ex.3

Ex.4

Yellow

Green

Red

Black

Water

54.3

53.1

60.3

52.1

Shellac

Suter

Excretion of the lac beetle

15.8

17.5

12.5

17.5

Glycerol

Tennant

By-product of bioethanol from rapeseed

6.3

7.0

6.0

7.0

DMAMP

Banners

3.6

4.2

3.0

4.2

Lanco 1955 SF

Capricorn/Noveon

Camauba wax from palm leaves

1.0

0.5

1.0

Laraprint B50

Lonza

Arabinogalactan from larch leaves

3.0

1.5

3.0

Foamaster 350

Cognis

Triglyceride from plant oil

0.2

Natural Yellow

Sensient Food Colours

Beta-carotene derived from carrots etc. *

15.8

-

Natural Green

Sensient Food Colours

Chlorophyll, the green pigment of plants *

-

16.0

-

Eurovit Carmine 2XYAJF

Sensient Food Colours

Laked red from cochineal beetles *

16.0

Eurovit Black P-WD E-153

Sensient Food Colours

Carbon black from vegetable matter

15.0

Total

100

* the natural dyes were laked onto a small amount of aluminium silicate which is produced by processing naturally occurring minerals

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EXAMPLE 5

Shellac ink

25% Shellac 50.0

Foamaster 350 0.5

Lanco 1955 SF 0.5

Laraprint B50 6.5

Water 2.5

SunsperseRed 184 40

EXAMPLE 6

5 Natural ink

The following components were mixed to form an ink:

Water 28.5

25% Shellac 50.0

Cochineal Red PWD 16.0

Carnauba wax 0.5

Laraprint B50 1.5

Foamaster 350 0.5

Glycerol 3.0

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EXAMPLE 7

Polysaccharide ink

The following components were mixed to form an ink:

Polysaccharide 37.5

Water 20.0

Foamaster 350 0.5

Lanco 1955 SF 0.5

Laraprint B50 1.5

TPQ4571 40

EXAMPLE 8 (Comparative)

5 Zein ink

The following components were mixed to form an ink:

Zein com protein 15.0

Glycerol 10.0.

Ketjenflex 8 Plasticiser (ex 10.0 Akzo Nobel Chemicals)

Water 15.0

n-propanol (ex Univar Ltd.) 50.0

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EXAMPLE 9

Compost test

A set of cress tests was prepared, comparing inks of the present invention with the ink of Example 8 and a blank compost/sand standard. The inks were tested by the 5 coated sand method as set out in EN 13432.

The sand was coated with the inks to give the maximum amount of permitted test material which is 2% plus a safety factor of 10%, therefore 2.2% of the inks were incorporated in the compost under test.

The cress test is used to determine possible toxic effect of a test item to the 10 emergence and growth of terrestrial plants. The cress plant is chosen as a representative for dicotyledonous plants and because of its sensitive germination. The test includes germination and growth of the cress seeds in mixtures of reference substrate and compost. The germination rate is measured and at the end of the test, and the fresh yield weight of the plants is determined for each test series and compared with the blank 15 standard. Where there is no significant difference between the test compost and the blank compost, the test items residuals can be considered to be non toxic to plants.

The ink containing compost was prepared by mixing an exact amount of test item with mature compost to obtain a concentration of 2.2% dry ink in the final compost. This is the maximum test concentration used under EN 13432.

20 The inks were mixed 80 parts ink to 20 parts water. These dilute mixtures were added to dry sand at a concentration of 27.8% on a weight basis and thoroughly mixed. The water was evaporated off in an oven at 50°C until dry. 10% of the sand / ink mix was added to the mature compost to give a residue of 2.2% ink in the test compost, the maximum amount that would be tested. 10% of dry sand was added to the compost 25 control blank standard.

The cress plant growth tests were done in 250ml pots containing a mixture of compost and the ink coated sand to give the desired concentration of dry ink. These test composts were aged in dark humid conditions for four weeks at 25°C prior to planting with the cress seeds to lessen the effects of any toxic materials that may be present. The

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minimum acceptable maturing period is 9 days under CN 13432 but 12 weeks is the full maturing period.

Once matured, 50ml of de-ionised water were added to each pot and 100 cress seeds put on the surface of each of the test pots. These were covered with a small 5 amount of sand and then a glass plate, this is to help retain the moisture.

The seeds were germinated in the dark for three days at 22°C and then allowed to grow in bright daylight conditions for a further four days before harvesting. Water was added in measured amounts to each pot as required.

The seedlings were then counted, to give the germination rate for each test 10 compost (Table 2), and then the above soil plant material was weighed to give the fresh plant yield (Table 3).

Table 2

Average Germination

Compost/sand

79.5

Compost/polysaccharide ink (Ex. 7)

92

Compost/zein ink (Ex. 8)

57

Compost/natural ink (Ex. 6)

77

Compost/shellac ink (Ex. 5)

75

10 Table 3

Test material

Average yield (in grammes)

Compost/sand

6.31

Compost/polysaccharide ink (Ex. 7)

6.275

Compost/zein ink (Ex. 8)

1.97

Compost/natural ink (Ex. 6)

6.28

Compost/shellac ink (Ex. 5)

6.48

The toxicity of possible residuals of the test item was evaluated by comparing the plant yield results of the test compost to the blank compost standard.

The average germination rate for all of the compost test mixes were not 5 significantly different from each other apart from the zein ink, which gave a much lower germination rate.

Even at the maximum test level, the Natural ink, Polysaccharide ink and the Shellac ink all gave plant germination and fresh cress yield values similar to the compost/sand only standard.

10 The cress seeds germinated and grown in the zein ink of cornstarch and sulphonamide plasticiser fared very badly, giving poor germination and very stunted growth. It is doubtful that any inks containing these items would pass the EN 13432 test.

Claims

CLAIMS: 11

1. A printing ink which is compostable to European standard EN13432.

2. A printing ink according to Claim 1, in which at least 50% of the dry ink film by weight of the components of the ink are compostable to European standard EN13432.

3. A printing ink according to Claim 2, in which at least 80% of the dry ink film by weight of the components of the ink are compostable to European standard EN13432.

4. A printing ink according to Claim 1, in which essentially all of the components of the ink are compostable to European standard EN13432.

5. A printing ink according to any one of the preceding Claims, in which at least 50% of the dry ink film by weight of the components of the ink are of natural origin, other than from the petrochemical industry.

6. A printing ink according to Claim 5, in which at least 80% of the dry ink film by weight of the components of the ink are of natural origin, other than from the petrochemical industry.

7. A printing ink according to Claim 6, in which essentially all of the components of the ink are of natural origin, other than from the petrochemical industry.

8. A printing ink according to any one of the preceding Claims, comprising at least: a solvent; a binder resin; and a pigment.

9. A printing ink according to any one of the preceding Claims, in which the solvent is water, ethanol or ethyl acetate.

10. A printing ink according to Claim 9, in which the solvent is water and the binder is shellac, a polysaccharide resin, an arabinogalactan, a soybean protein or a rosin.

11. A printing ink according to any one of Claims 1 to 9, in which the solvent is nonaqueous and the binder is shellac, zein corn protein, tree rosin, sandarac or dammar.

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12. A printing ink according to Claim 9, in which the colorant is carmine lake natural red 4, natural yellow 3 lake, madder lake natural red 9, indigo lake natural blue 2, chlorophylin green lake, vegetable or bone black, titanium white, iron oxides, talc, chalk, kaolin or another earth pigment.

13. A printing ink according to any one of the preceding Claims, in which a solvent comprises from 50 to 70% by weight of the ink.

14. A printing ink according to any one of the preceding Claims, in which the binder comprises from 1 to 20% by weight of the ink..

15. A printing ink according to any one of the preceding Claims, in which the colorant comprises from 1 to 20% by weight of the ink.

16. A packaging material comprising a substrate printed with a printing ink according to any one of the preceding Claims.

17. A packaging material according to Claim 16. in which the substrate is compostable to European standard EN 13432.

18. A packaging material according to Claim 17, in which the substrate is a paper or cardboard.

19. A packaging material according to Claim 17, in which the substrate is a plastics material.