GB2030159A

GB2030159A - Wipe-off marking ink for writing boards

Info

Publication number: GB2030159A
Application number: GB7836686A
Authority: GB
Original assignee: Pilot Pen Co Ltd; Pilot Man Nen Hitsu KK
Current assignee: Pilot Corp
Priority date: 1978-09-13
Filing date: 1978-09-13
Publication date: 1980-04-02
Also published as: FR2436170B1; FR2436170A1; GB2030159B

Abstract

A wipe-off marking ink comprises: i) 1 to 15% of a pigment; ii) 1 to 15% of a resin; iii) (A) 1 to 15% of an aliphatic dibasic acid ester; and iv) (B) 0.2 to 12% of a modified silicone oil, a sulfuric acid ester of a polyoxyethylene alkyl ether or salt thereof or a phosphoric acid ester of a polyoxyethylene alkyl ether or a salt thereof, dispersed or dissolved in 43 to 96.8% of a volatile solvent. %

Description

SPECIFICATION Marking ink for a writing board The present invention relates to a marking ink for use on a writing board and which has the property such that when the ink is marked onto a writing board having a smooth surface and which is impervious to a liquid ink, such as, for example, ceramic board, plastic board, metal board or other board made of various materials, the marked ink can be erased easily by lightly rubbing the board with a dry cloth or soft paper and to a process for its preparation.

Conventional marking inks for writing boards which contain a pigment, a resin and a volatile solvent, use a non-volatile liquid additive which is quite incompatible with the resin. An ink marked on the writing board can then be erased due to the fact that the resin is deposited by the evaporation of the volatile solvent, and the marked ink is thus transformed into a wet aggregation of coarse particles which is easiy wiped out from the board surface. However, in this case, the case with which the ink may be erased decreases with the lapse of time, In addition to the above type of ink, an ink has been proposed which may be wiped from a writing board after it is transformed into a plastic film when marked on the board, This ink, however, may adhere to the surface of a writing board to such an extent that it cannot be erased.This normally depends upon temperature and humidity, and for this reason, good erasability cannot be obtained throughout all seasons of the year.

In order to overcome the above mentioned disadvantages, various additives have now been examined. As a result, it has been found that, the use of a combination of (A) a dibasic acid ester and (B) an inorganic acid ester type active agent as an additive is advantageous. Aromatic carboxylic acids are, however, not usable as an acid component of the additive (A) because they provide very inferior erasability. As the alcohol component of the additive (A), aliphatic alcohols are preferred. It should be noted that dibasic acid esters of the unsaturated aliphatic type are not preferred as an additive since the additive should always have lubricity because such esters if used may possibly be modified due to the effect of temperature or oxygen in the air during their residence time on a writing board, particularly if they are on the board for a long period of time.

A marking ink which can be easily erased should have the requirement that the saturated aliphatic dibasic acid ester is itself very difficu It to dry. That is, one of the important requirements of the ink of the present invention is prevention of the erasability of the ink from deteriorating with the lapse of time. For thins purpose, a preferred condition meeting the above mentioned requirement is that the aliphatic dibasic ester used should have a boiling point of not less than 300"C (at 760MM Hg).

In accordance with the present invention, an additive (A), use is made of aliphatic dibasic acid esters, preferably having the following formula: R'OOC B R - COOR' wherein R is a C4to C10 alkylene group and R' is a C4to C10 alkyl group. Preferred examples of such esters are dibutyl adipate, dioctyl adipate, dioctyl azelate, dibutyl sebacate, dioctyl sebacate and dioctyl dodecane diacid. It is preferable that these aliphatic dibasic acid esters are used in a quantity of from 1 to 15% by weight based on the final weight of product containing solvent. That is, in the case where the ester additive (A) is used in a quantity of less than 1% by weight, the marked ink will already have unsatisfactory erasability at the time of initial marking.On the other hand, when the ester additive (A) is present in an amount greater than 15% by weight, the viscosity of the ink is increased, and the marked ink is liable to dry slowly. More preferably, additive (A) is used in a quantity of from 4 to 12% by weight and most peferably from 7 to 10% by weight based on the weight of the final product. Turning now to additive (B), this additive should dissolve or swell the resin used in the present invention, but this requirement alone is not sufficient for the purpose of the present invention.In addition, it is necessary to select an additive which is not influenced by temperature and/or humidity with regard to the erasion of the marked ink, and also which causes little difference between the erasability of the ink immediately after writing and that after the lapse of time, i.e. it should not adversely affect the erasability of the ink as a whole. That is, even if the additive (B) is slightly compatible with any pigment used as a solids content other than the resin used in the present invention, it adversely affects the erasability of the ink. In addition, the hygroscopicity of the additive (B) is preferably as low as possible and it is further necessary, of course, that the hygroscopicity has no adverse effect on the erasability and resistance to whitening of the marked ink.On the basis of the above requirements, it has been found that inorganic acid ester type active agents such as the sulfuric acid esters of polyoxyethylene alkyl ethers and the phosphoric acid esters of polyoxyethylene alkyl ethers or salts thereof together with modified silicone oils are very useful additives. Preferably, the additive (B) has one of the following structures: RO--(CH2CH20),S03M;

wherein R is a C8 to C30 alkyl or alkyl phenyl group, M is a hydrogen atom, an ammonium or an alkanol amine group, M' is a hydrogen or barium atom, an ammonium an alkanolamine or a polyalkylenediamine group and n an n' represent an average addition mole number of ethylene oxide, i.e. n is a number from 2 to 60 and n' is a number from 2 to 20.

The modified silicone oils preferably have the following formula:

wherein m is a number fro 2 to 500, and R is a C1 to C4 alkyl group, an amino group, an alkylamino group, a phenyl group, a polyoxyethylene group or a polyoxypropylene group. It is preferable that the total quantity of the additives (B) satisfying the above mentioned requirements is 0.2 to 12% by weight based on the final product. When the additive (B) is used in a quantity of less than 0.2% by weight, the marked ink is plastic and normally does not form a continuous film easily. As a result, the resin adheres to the surface of a writing board, resulting in poor erasability.On the other hand, in the case where the additive (B) is present in an amount of greater than 12% by weight, the marked ink dries slowly and when the ink is erased, it tends to flow, thus staining the surface of the writing board upon which it is used. It is more preferable that additive (B) is used in quantity of from 0.5 to 7% by weight, most preferably, 0.8 to 3% by weight, based on the total weight of the final product. In the foregoing description, two kinds of additives essential to the present invention have been illustrated.That is, (A) aliphatic dibasic acid esters: these esters have the lubricity which is required for peeling the marked ink after drying; and (B) sulphuric acid esters of polyoxyethylene alkyl ethers, phosphoric acid esters of polyoxyethylene alkyl ethers and modified silicone oils; these compounds serving to form a plastic continuous film of the marked ink after its drying.

When only one of the additives (A) or (B) is used, the erasability of the marked ink is substantially decreased. For example, when only the additive (A) is used, the resulting marked ink becomes almost impossible to erase after a time of about 10 to 24 hours has elapsed. This tendency is particularly conspicuous as humidity increases. Similarly, when only the additive (B) is used, the marked ink tends to be influenced by temperature and humidity and the erasability of the ink becomes unstable. That is, when the temperature of a writing board is increased or when the humidity of the room is significantly low, the erasability of the marked ink is greatly reduced from the time of initial application.

Thus, when the additives (A) and (B), which are essential to the ink of the present invention, are used in an adequate quantity in combination with each other, the marked ink has superiority in terms of the erasability of the marked ink at the initial time of application and also after the elapse of time under conditions of both high and low humidity at high temperatures, high and low humidity at low temperatures, as well as at normal conditions (20"C, 60% RH) as compared with conventional commercial marking ink used on writing boards.

Turning now to the resin used in the present invention, it is essential that it should be dissolved or swollen in the additive (B). Suitable examples of the resin satisfying the above mentioned requirement and also having a protective colloidal property for pigments are styrenemaleic acid copolymers, cellulose derivatives such as ethyl cellulose, nitrocellulose, carboxymethyl cellulose, hydroxypropyl cellulose and cellulose acetate butyrate and also vinyl type polymers such as polyvinyl pyrrolidone, polyvinyl butyral and copolymers of polyvinyl pyrrolidone and polyvinyl acetate.

The pigment used in the ink of the present invention may be any pigment having clear colour tone and high tinting power and also which can be rendered sufficiently stable as colloid by use of the above described resin. Organic pigments having such properties are preferred. Such pigments pre-dispersed in the resin may also be used.Suitable examples of commercially available pigments subjected to such a surface treatment are NC Printing Colours (surface-treated with nitrocellulose, manufactured by BASF Company), Microlith A Colours (surface -treated with cellulose derivatives, manufactured by Ciba-Geigy Company), Superapal Colours (surface-treated with a styrene-maleic acid copolymer, manufactured by BASF Company), and pigments surface-treated with polyvinyl butyral such as Black 2 x 8A - 734, Blue 2 x S5A 760, Red 3 x 1A - 843 and Green 3 x 4A - 041 (all these latter colours are manufactured by Sumika Colour Company).

The pigment is used in a quantity in the range of from 1 to 15% by weight, preferably 3 to 10% by weight, based on the total weight of final product. The resin is generally used in a similar quantity to that of the pigment i.e. 1 to 15% preferably 3 to 10% by weight, again based on the weight of the final product.

Finally, as the volatile solvent in the ink of the present invention, aliphatic lower alcohols, ketones, esters, aromatic hydrocarbons or mixtures thereof are preferably used. The solvent is used in a quantity of from 43 to 96.8% by weight based on the weight of the final product, i.e. the marking ink.

In order to further illustrate the present invention, the following specific Examples are set forth, it being understood that these examples are non-limitry.

In Example 1, an ink is prepared by using a non-surface-treated pigment. In Examples 2 to 9, inks are prepared by using surface-treated pigments.

In Comparative Examples 1 and 2, inks are prepared by using additive (B) only, and in Comparative Examples 3 and 4, inks are prepared by using additive (A) only. The composition of the inks of these Examples except for Example 1 is shown in Table 1.

Each of the inks of the Examples and the Comparative Examples was charged into a marking pen, and writing was conducted on an enamelled board. The erasability of the marked ink was then tested, the results being summarized in Table II.

Example 1 8.0 g of Sumiton Fast Red GR (a condensed azo type pigment, manufactured by Sumitomo Kagaku Kogyo K.K), 8.0g of S-lec BL-1 (polyvinyl butyral, manufactured by Sekisui Kagaku Kogyo K.K), 30.0 g of isopropyl alcohol, 35.0g of ethyl alcohol and 5.0g of Plysurf A 208B (phbsphoric ester of polyoxyethylene alkyl ester, manufactured by Daiichi Kogyo Seiyaku K.K) were milled in a ball mill for 24 hours in order to disperse the pigment. 78g of ehtyl alcohol, 20g of n-butanol and 1 6g of dioctyl sebacate were then added to 86g of the dispersion and the mixture was stirred in a dispenser for 2 hours to produce a red ink.

Table I

Surface treated pigment Additive (A) aliphatic dibasic acid ester name quantity Chemical name (%) 2 NC Printing E;lue 7 Dioctyl adipate 639 (C1 42595) 3 Microlith Black 8 Dioctyl azelate (C-A) (C1 77266) 4 Suprapal Black 8 Dibutyl sebacate X-60 (Cl 77266) 5 Blue 2xS5A-760 7 Dioctyl azelate (Cl 69800) o 6 Red3x1A-843 9 Dioctylesebacate (Cl 15865) E x w 7 Black 2xS8A-734 8 Dioctyl dodecane (Cl 77266) diacid 8 Green 3x4A-041 9 Dioctyl adipate (C1 Pigment Blue 15) 9 Blue 2xS5A-760 7 Dioctyl azelate (Cl 69800) 1 Microlith Black C-A 8 > 2 SuprapalBlackX-60 8 LO) 3 ff 3 Blue2xS5A-760 7 Dioctyl azelate F E e O 4 Black 2xS8A-734 8 Dioctyl dodecane diacid Table I

Additive (A) Additive (B) Aliphatic dibasic sulfuric or acid ester phosphoric acid ester of poly oxyethylene Solvent ether, modified silicone oil Quantity (%) name quantity (%) % 2 10 Hitenol 5 78 335T 3 10 Emal 20T 3 79 4 4 RS-710 6 82 5 9 Plysurf 5 79 A208S a) ,, 6 10 LM-600 2 79 E Co 7 7 6 Hitenol 4 82 12 8 8 Plysurf 2 77 A208S Hitenol 4 335T O 9 10 KF-857 5 78 n x 1 Emal 20T 3 x w > 2 RS-710 6 ma 3 9 Co 3 9 E 0 o" 4 6 Illustration of Table 1 Preparation of the ink: In Examples 2 to 9 and Comparative Examples 1 to 4, all the ingredients were stirred in a disperser at a high speed for 2 hours.

Additive (B) Hitenol 335 T and Hitenol 12: Each is a sulfuric acid ester of polyoxyethylene alkyl ethers manufactured by Daiichi Kogyo Seiyaku K.K.

Emal 20T: A sulfuric acid ester of polyoxyethylene alkyl ethers manufactured by Kao-Atlas K.K.

Plysurf A 208S: A phosphoric acid ester of polyoxyethylene alkyl ethers manufactured by Daiichi Kogyo Seiyaku K.K. RS-710 and LM-600: Each is a phosphoric acid ester of polyoxyethylene alkyl ethers manufactured by General Aniline & Film Corp. United States.

KF-857: An amino modified silicone oil manufactured byShinetsu Kagaku Kogyo K.K.

Solvent: A mixed solvent consisting of ethanol, isopropanol and n-butanol in a weight ratio of 7:3:1 was used in each Example and Comparative Example.

Room Low Inltlal temperature humidity erasability aging aging erasability erasability 1 () &commat;) 2 3 - 4 (g) (H) 0 '1 E 5 5 x 6 6 7 () tH) 0 8 9 z z 1 1 A x xx a, A x xx E . 2 O x /, ox x A Erasability Erasablhty High humidity on a board aging at a high erasability temperature 1 ~ 2 O () 3 O (ç) 4 4 (H) 0 E 5 6 6 7 (ç) 0 8 0 9 0 0 a, A a xx 2 A xx E:E 3 xx A ow 4 xx A

Illustration of Table II = = verygood; O = Good; A = Slightly poor; x = poor; and xx = Very poor.

Initial erasability: Erasion is carried out in an atmosphere having a relative humidity of 60% at a temperature of 20"C one minute afterwriting.

Room temperature aging erasability: After the lapse ofone month.

Low humidity aging erasabllity: After the lapse of one month in an atmosphere of 25+5% RH.

High humidity aging erasability: After the lapse of one month in an atmosphere of 90 + 5% RH.

Erasability on a board at a high temperature: After the lapse of one month on a board maintained at a temperatureof 60"C.

It is apparent from Table II that the marking inks of the present invention are superior to the inks prepared by using either of the additives (A) and (B) alone (Comparative Examples 1 to 4) in respect of various performances of the initial erasability, room temperature aging erasability, low humidity aging erasability, high humidity aging erasability and erasability on a board at a high temperature.

Claims

1. A marking ink which can be erased from a writing board by wiping which comprises: i) 1 to 15% by weight, based on the total weight of the ink, of a pigment; ii) 1 to 15% by weight, based on the total weight of the ink, of a resin; iii) an additive (A) which consists of 1 to 15% by weight, based on the total weight of the ink, of an aliphatic dibasic acid ester; and iv) an additive (B) which consists of 0.

2 to 12% by weight, based on the total weight of the ink, of a compound selected from modified silicone oils, sulfuric acid esters of polyoxyethylene alkyl ethers and salts thereof and phosphoric acid esters of polyoxyethylene alkyl ethers and salts thereof, dispersed or dissolved in 43 to 96.8% by weight, based on the total weight of ink, of a volatile solvent 2.A marking ink as claimed in claim 1, wherein the aliphatic dibasic acid ester has the formula: R'OOC-R-COOR' wherein R is C4to C10 alkylene group and R' is a C4to C10 alkyl group.

3. A marking ink as claimed in claim 1 or claim 2, wherein additive (B) is a sulfuric acid ester of a polyoxyethylene alkyl ether or a salt thereof.

4. A marking ink as claimed in claim 3 wherein the sulphuric acid ester of a polyoxyethylene alkyl ether has the formula: RO-(CH2CH20)nSO3M wherein n is a number from 2 to 60, R is a C8 to C30 alkyl or alkyl phenyl group and M is a hydrogen atom or an ammonium or alkanolamine group.

5. A marking ink as claimed in claim 1 or claim 2, wherein additive (B) is a phosphoric acid ester of a polyoxyethylene alkyl ether or a salt thereof.

6. A marking ink as claimed in claim 5 wherein the phosphoric acid ester of polyoxyethylene alkyl ether is selected from compound represented bytheformulae:

[RO-(CH2CH20),]3P=O, or mixtures thereof, wherein n' is a number from 2 to 20, R is a C8 to C30 alkyl or alkyl phenyl group, and M is hydrogen, alkanol-amine, polyalkylenediamine or Bai.

7. A marking ink as claimed in claim 1 or claim 2, wherein additive (B) is a modified silicone oil.

8. A marking ink as claimed in claim 7 wherein the modified silicone oil has the formula:

wherein m is a number from 2 to 500 and R is a C1 to C4 alkyl, an amino, an alkylamino, a phenyl, a polyoxyethylene group or a polyoxypropylene group.

9. A marking ink as claimed in any of claims 1 to 8 wherein the pigment is present in an amount of from 3 to 10% by weight based on the total weight of the ink, the resin is present in an amount of from 3 to 10% by weight based on the total weight of the ink, the additive (A) consists of from 4 to 12% by weight based on the total weight of ink of an aliphatic dibasic ester and the additive (B) consists of from 0.5 to 7% by weight based on the total weight of the ink of a compound selected from modified silicone oils, sulfuric acid esters of polyoxyethylene alkyl ethers and salts thereof or phosphoric acid esters of polyoxyethylen alkyl ethers and salts thereof.

10. A marking ink as claimed in any of claims 1 to 9 wherein the aliphatic dibasic ester is present in an amount of from 7 to 10% by weight based on the total weight of ink.

11. A marking ink as claimed in claim 3 or claim 4 wherein the sulfuric acid ester of a polyoxyethylene alkyl ether or salt thereof is present in an amount of from 0.8 to 3% by weight based on the total weight of ink.

12. A marking ink as claimed in claim 5 or claim 6 wherein the phosphoric acid ester of a polyoxyethylene alkyl ether or salt thereof is present in an amount of from 0.8 to 3% by weight based on the total weight of ink.

13. A marking ink as claimed in claim 7 or claim 8 wherein the modified silicone oil is present in an amount of from 0.8 to 3% by weight based on the total weight of ink.

14. A marking ink as claimed in any of claims 1 to 13 wherein the resin is a styrene-maieic acid copolymer, ethyl cellulose, nitrocellulose, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate butyrate, polyvinyl pyrrolidine, polyvinyl butyrate or a copolymer of polyvinyl pyrrolidone and polyvinyl acetate.

15. A marking ink as claimed in any of claims 1 to 14 wherein the volatile solvent is an aliphatic lower alcohol, a ketone, an ester, an aromatic hydrocarbon or mixtures thereof.

16. A marking ink as claimed in claim 1 substantially as herein described with reference to the Examples.

17. A process for the preparation of a marking ink as claimed in Claim 1 which comprises dispersing or dissolving: i) 1 to 15% by weight, based on the total weight of the ink, of a pigment; ii) 1 to 15% by weight, based on the total weight of the ink of a resin; iii) an additive (A) which consists of 1 to 15% by weight, based on the total weight of the ink, of an aliphatic dibasic acid ester; and iv) an additive (B) which consists of 0.2 to 12% by weight, based on the total weight of the ink, of a compound selected from modified silicone oils, sulfuric acid esters of polyoxyethylene alkyl ethers and salts thereof and phosphoric acid esters of polyoxyethylene alkyl ethers and salts thereof, in 43 to 96.8% by weight, based on the total weight of the ink, of a volatile solvent.

18. A process as claimed in claim 17, wherein the pigment is pre-dispersed in the resin.

19. A process as claimed in claim 17 substantially as herein described with reference to the Examples.

20. A marking ink as claimed in claim 1 whenever prepared by a process as claimed in any of claims 17 to 19.