CA1126026A - Pressure-sensitive mark-recording systems - Google Patents
Pressure-sensitive mark-recording systemsInfo
- Publication number
- CA1126026A CA1126026A CA328,731A CA328731A CA1126026A CA 1126026 A CA1126026 A CA 1126026A CA 328731 A CA328731 A CA 328731A CA 1126026 A CA1126026 A CA 1126026A
- Authority
- CA
- Canada
- Prior art keywords
- benzyl phthalate
- aliphatic
- chromogen
- michler
- hydrol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M5/00—Duplicating or marking methods; Sheet materials for use therein
- B41M5/124—Duplicating or marking methods; Sheet materials for use therein using pressure to make a masked colour visible, e.g. to make a coloured support visible, to create an opaque or transparent pattern, or to form colour by uniting colour-forming components
- B41M5/165—Duplicating or marking methods; Sheet materials for use therein using pressure to make a masked colour visible, e.g. to make a coloured support visible, to create an opaque or transparent pattern, or to form colour by uniting colour-forming components characterised by the use of microcapsules; Special solvents for incorporating the ingredients
- B41M5/1655—Solvents
Abstract
PRESSURE-SENSITIVE MARK-RECORDING SYSTEMS
ABSTRACT
The invention relates to pressure-sensitive mark-recording systems, for example carbonless copying paper, in which the chromogen is a derivative of diphenylmethanol or diphenylmethylamine, and the solvent comprises an aliphatic benzyl phthalate, e.g., an alkyl benzyl phthalate.
ABSTRACT
The invention relates to pressure-sensitive mark-recording systems, for example carbonless copying paper, in which the chromogen is a derivative of diphenylmethanol or diphenylmethylamine, and the solvent comprises an aliphatic benzyl phthalate, e.g., an alkyl benzyl phthalate.
Description
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PRESSURE-SENSITIVE-MARK-RECORDING S~STEMS
BACKGROUND OF THE INVENTION
This invention relates to solutions which are useful in the production of pressure-sensitive mark-recording systems and to such systems thus produced.
The most familiar form of pressure-sensitive mark-recording system is th`e so-called carbonless copying paper which comprises a two-sheet system in which the under surface of the kop sheet has a coating of microcapsules of a solution of a colorless chromogen, while the upper surface of the lower (receiver) sheet has an absorbent coating including a sensitizing agent for the chromogen. Whe~ a marking instrument is applied to the top sheet, the microcapsules are locally ruptured, thereby releasing the chromogen solution from the affected microcapsules to react with the underlying sensitizing agent and form colored marks on the receiver sheet corresponding to the marks applied to the top ` sheet.
A successful carbonless copying paper system needs to meet a number of criteria. For example the marks on the receiver sheet should develop rapidly to a legible intensity of color and a legible mark should persist for as long as the sheet is required to be kept.
Whether the various cr-iteria are met depends on a number of factors including the nature of the chromogen, the ,. . .
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solvent and the sensitizing agent, and many difrerent materials.of each catetory have been proposed. Chromo-gens which have been proposed include phthalide deriva-tives, for example crystal violet lactone, and Malachite 5 green lactone, indole~substituted pyromellitides, leucauramines, and diphenylmethane derivakives such as Michler's hydrol. Solvents which have been proposed include hydrocarbons, for instance petroleum fractions or synthetic hydrocarbons such as hydrogenated terphenyls, halogenated hydrocarbons, for instance chlorinated biphenyls, and esters, for instance alkyl adipates and alkyl phthalates~ The sensitizing agent is usually an acid clay, for example an attapulgite or bentonite clay, ~ or an acidic organic polymer, for example a phenol-15 aldehyde polymer or a partially or wholly hydrolyzed styrene-maleic anhydride or ethylene-maleic anhydride polymer.
The chromogens which are probably most fre-quently referred to in the art are the phthalide deriva-tives, especially crystal violet lactone. These chromogensare usually used in solution in a hydrocarbon type solvent~
One reason for this choice of solvent is that although the phthali.de color-formers are soluble i.n esters, for example, it is found that esters and certain other solvents having similar polarity to the esters, show too great a tendency to compete with the chromogen in affinity . ~or the sensitizing agent, so that in some cases, no color development occurs. This is especially so with certain acid clay sensitizing agents.
' Certain chromogens that are diphenyl methane derivatives are less sub~ect to this limitation and can be used in conjunction with solvents such as esters, advantages of the latter over hydrocarbons being that the chromogens dissolve more readily and have higher solubilitiesO The use of diphenyl methane derivatives, for instance Michler's hyd'rol, as chromogens in pressure' - -3~ 6~ ~ ~
sensitive mark-recording systems is described in, for example, British Patent Specification 1,381,928 and U.S. Patent Specification 4,000,087, which is herein incorporated by reference.
The present invention concerns an improvement relating to the use in pressure-sensitive mark-recording systems, of chromogens that are diphenyl methane deriva-tives.
A solution of the invention is a solution of a chromogen which is a derivative of diphenylmethanol or diphenylmethylamine in a solvent comprising an aliphatic benzyl phthalate; and a pressure-sensitive mark-recording system of the invention comprises (a) sheet material, (b) mark-forming components supported by the sheet material and arranged in juxtaposition but in unreactive condition, ;` - the said components comprising a chromogen which is a derivative of diphenylmethanol or of diphenylmethylamine, and an acid clay sensitizer for the chromogen which pro-duces a color from the chromogen when brought into contact with the chromogen in the presence of a liquid solvent for the chromogen comprising an aliphatic benzyl phthalate and (c) the said solvent supported by the sheet material but separated from the sensitizing agent by a physical barrier which is rupturable on the application of a marking instrument to the sheet material.
Compared with the solvents, for example xylene or dibutyl phthalates, hitherto proposed for use in conjunction with chromogens that are diphenylmethane derivatives, use of solvents in accordance with the present invention results in an improvement in the resistance to fading of the marks on the receiver sheet during storage, particularly if storage occurs under conditions where fading is due to the action of oxygen.
In an aliphatic benzyl phthalate useful in the present invention, one of the phthalate carboxyl groups lS esterified by an aliphatic group and the other by a .
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,, ~Z6~26 benzyl group. The term "aliphatic group" herein means organic groups which are acyclic (straight or branched chain) and devoid of olefinic unsaturation and which, except for the possible presence of oxygen in certain types of groups hereinafter described, contain only carbon and hydrogen. The aliphatic group can, for example, contain up to 24 carbon atoms. It can, for example, be an alkyl group, for example an ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-hexyl, isohexyl, n-octyl, 2-ethylhexyl, decyl, tetra-; decyl or octadecyl group. Preferred alkyl groups contain from 2 to 12 carbon atoms. The aliphatic group can be an alkoxyalkyl or a group derived from an alkyl group by the replacement of more than one -CH2- group by the 15 same number of oxygen atoms, and it may thus be, for instance3 an ethoxyethyl or a 336,g-trioxaundecyl group.
The aliphatic group can also be one derived from an alkyl ester of a hydroxy-carboxylic acid, for example a Cl 18 alkyl ester of glycolic acid, 3-hydroxypropionic acid 20 or y-hydroxybutyric acid; or from a hydroxyalkyl ester of a carboxylic acid, where the hydroxyalkyl radical and the carboxylic acid may each contain up ~ to 12 carbon atoms. Examples of such aliphatic groups s are butoxycarbonylmethyl, (2-ethylhexyloxy)carbonylmethyl,
PRESSURE-SENSITIVE-MARK-RECORDING S~STEMS
BACKGROUND OF THE INVENTION
This invention relates to solutions which are useful in the production of pressure-sensitive mark-recording systems and to such systems thus produced.
The most familiar form of pressure-sensitive mark-recording system is th`e so-called carbonless copying paper which comprises a two-sheet system in which the under surface of the kop sheet has a coating of microcapsules of a solution of a colorless chromogen, while the upper surface of the lower (receiver) sheet has an absorbent coating including a sensitizing agent for the chromogen. Whe~ a marking instrument is applied to the top sheet, the microcapsules are locally ruptured, thereby releasing the chromogen solution from the affected microcapsules to react with the underlying sensitizing agent and form colored marks on the receiver sheet corresponding to the marks applied to the top ` sheet.
A successful carbonless copying paper system needs to meet a number of criteria. For example the marks on the receiver sheet should develop rapidly to a legible intensity of color and a legible mark should persist for as long as the sheet is required to be kept.
Whether the various cr-iteria are met depends on a number of factors including the nature of the chromogen, the ,. . .
- .
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.
, . .
.
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solvent and the sensitizing agent, and many difrerent materials.of each catetory have been proposed. Chromo-gens which have been proposed include phthalide deriva-tives, for example crystal violet lactone, and Malachite 5 green lactone, indole~substituted pyromellitides, leucauramines, and diphenylmethane derivakives such as Michler's hydrol. Solvents which have been proposed include hydrocarbons, for instance petroleum fractions or synthetic hydrocarbons such as hydrogenated terphenyls, halogenated hydrocarbons, for instance chlorinated biphenyls, and esters, for instance alkyl adipates and alkyl phthalates~ The sensitizing agent is usually an acid clay, for example an attapulgite or bentonite clay, ~ or an acidic organic polymer, for example a phenol-15 aldehyde polymer or a partially or wholly hydrolyzed styrene-maleic anhydride or ethylene-maleic anhydride polymer.
The chromogens which are probably most fre-quently referred to in the art are the phthalide deriva-tives, especially crystal violet lactone. These chromogensare usually used in solution in a hydrocarbon type solvent~
One reason for this choice of solvent is that although the phthali.de color-formers are soluble i.n esters, for example, it is found that esters and certain other solvents having similar polarity to the esters, show too great a tendency to compete with the chromogen in affinity . ~or the sensitizing agent, so that in some cases, no color development occurs. This is especially so with certain acid clay sensitizing agents.
' Certain chromogens that are diphenyl methane derivatives are less sub~ect to this limitation and can be used in conjunction with solvents such as esters, advantages of the latter over hydrocarbons being that the chromogens dissolve more readily and have higher solubilitiesO The use of diphenyl methane derivatives, for instance Michler's hyd'rol, as chromogens in pressure' - -3~ 6~ ~ ~
sensitive mark-recording systems is described in, for example, British Patent Specification 1,381,928 and U.S. Patent Specification 4,000,087, which is herein incorporated by reference.
The present invention concerns an improvement relating to the use in pressure-sensitive mark-recording systems, of chromogens that are diphenyl methane deriva-tives.
A solution of the invention is a solution of a chromogen which is a derivative of diphenylmethanol or diphenylmethylamine in a solvent comprising an aliphatic benzyl phthalate; and a pressure-sensitive mark-recording system of the invention comprises (a) sheet material, (b) mark-forming components supported by the sheet material and arranged in juxtaposition but in unreactive condition, ;` - the said components comprising a chromogen which is a derivative of diphenylmethanol or of diphenylmethylamine, and an acid clay sensitizer for the chromogen which pro-duces a color from the chromogen when brought into contact with the chromogen in the presence of a liquid solvent for the chromogen comprising an aliphatic benzyl phthalate and (c) the said solvent supported by the sheet material but separated from the sensitizing agent by a physical barrier which is rupturable on the application of a marking instrument to the sheet material.
Compared with the solvents, for example xylene or dibutyl phthalates, hitherto proposed for use in conjunction with chromogens that are diphenylmethane derivatives, use of solvents in accordance with the present invention results in an improvement in the resistance to fading of the marks on the receiver sheet during storage, particularly if storage occurs under conditions where fading is due to the action of oxygen.
In an aliphatic benzyl phthalate useful in the present invention, one of the phthalate carboxyl groups lS esterified by an aliphatic group and the other by a .
.
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~":. . ..
,, ~Z6~26 benzyl group. The term "aliphatic group" herein means organic groups which are acyclic (straight or branched chain) and devoid of olefinic unsaturation and which, except for the possible presence of oxygen in certain types of groups hereinafter described, contain only carbon and hydrogen. The aliphatic group can, for example, contain up to 24 carbon atoms. It can, for example, be an alkyl group, for example an ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-hexyl, isohexyl, n-octyl, 2-ethylhexyl, decyl, tetra-; decyl or octadecyl group. Preferred alkyl groups contain from 2 to 12 carbon atoms. The aliphatic group can be an alkoxyalkyl or a group derived from an alkyl group by the replacement of more than one -CH2- group by the 15 same number of oxygen atoms, and it may thus be, for instance3 an ethoxyethyl or a 336,g-trioxaundecyl group.
The aliphatic group can also be one derived from an alkyl ester of a hydroxy-carboxylic acid, for example a Cl 18 alkyl ester of glycolic acid, 3-hydroxypropionic acid 20 or y-hydroxybutyric acid; or from a hydroxyalkyl ester of a carboxylic acid, where the hydroxyalkyl radical and the carboxylic acid may each contain up ~ to 12 carbon atoms. Examples of such aliphatic groups s are butoxycarbonylmethyl, (2-ethylhexyloxy)carbonylmethyl,
2(ethylcarbonyoxy)ethyl and 7(2,6,6,8-tetramethyl-4-oxa-3-s oxononyl).
As used herein3 the term "benzyl" is intended to cover both unsubstituted benzyl C6H5CH2- and alkyl-substituted benzyl. For example, the nucleus of the ~ 30 benzyl group may contain up to three alkyl substituents3 s~ each, for example, being an alkyl group having up to four carbon atoms, for instance methyl or ethyl; or one or both methylene hydrogen atoms of the benzyl group may be replaced by a similar alkyl group.
~ 35 Contemplated equivalents for use in the present sS~ invention are aliphatic benzyl phthalates as defined and ,. . . .
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s' ~
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~5~ ~ 1~ 6~ ~ 6 described above except for the presence of one or more substituents on the aliphatic group or the benzyl group, the presence of which does not significantly affect the performance of the phthalates as dye solvents. Those skilled in the art would recognize various substituents which could be present on these aliphatic and/or benzyl groups which substituents would not be expected to significantly affect the performance of the phthalates as dye solvents. ~lso contemplated as equivalents are aliphatic benzyl phthalates as defined and described above except for the presence of a certain degree of olefinic unsaturation which does not significantly affect the performance of the phthalates as dye solvents.
Variations such as these are considered to be within the skill of the art and would not be a departure from the spirit of the present invention.
Specific examples of aliphatic benzyl phthalates useful in the present invention are butyl unsubstituted-benzyl phthalates, for instance n-butyl benzyl phthalate and isobutyl benzyl phthalate, octyl unsubstituted-benzyl phthalates, for instance n-octyl benzyl phthalate and 2-ethylhexyl benzyl phthalate, and 7(2,6,6,8-tetramethyl-4-oxa 3-oxononyl) unsubstituted-benzyl phthalate.
Those skilled in the art would know methods for the preparation of aliphatic benzyl phthalates useful in the present invention. Such preparation is described in U.S. Patent 3,483,247 issued December 9, 1969 to R. H.
Mills. Various aliphatic benzyl phthalates useful in the present invention are commercially available.
The solvents used in the present invention can contain more than one aliphatic benzyl phthalate, for example mixtures of alkyl benzyl phthalates having a range of alkyl group sizes, for instance a C5-C7, a C7-Cg or a C8-Cl2 range. The solvents may optionally contain other components,-for instance dialkyl phthalates such as dibutyl phthalate and dioctyl phthalates, and various ., .
,~ - , - .
~' ' : .
-6- ~ ~ ~6~26 hydrocarbons, for example C6 1~ alkylbenzenes, kerosene or other petroleum fractions which are useful as diluents in certain circumstances to reduce the viscosity of the solvent. Preferably the solvent contains at least 50 percent by weight of an aliphatic benzyl phthalate or of a mixture of aliphatic benzyl phthalates. The proportions by weight of the aliphatic benzyl phthalate and the diluent in mixtures may, for example, range from 50:50 to 90:10, for example 60:40, 70:30, 75:25 or 80:20. For rapid development of print intensity, the solvent is preferably one having a viscosity in the range 5 to 15 centistokes at 38C.
The concentration of the chromogen in a solution of the invention is generally of the same order as that in known solutions of chromogens which are diphenylmethanol or diphenylmethylamine derivatives, for example from 0.25 -to 5 percent, more particularly from o.LI to 4.0 percent by weight of the solution.
Chromogens ~hich are especially suitable for use in the present invention include Michler's hydrol, i.e., bis (p-dimethylaminophenyl)methanol, its ethers, for example the methyl ether of Michler's hydrol and the benzyl ether of Michler's hydrol~ aromatic sulfonic and sulfinic esters of Michler's hydrol, for example the p-toluenesulfinate of Michler~s hydrol, and derivatives of bis(p-dimethylaminophenyl) methylamine, for example N[bis(p-dimethylaminophenyl) methyl~morpholine.
Several encapsulation systems have been pro-posed for the encapsulation of the chromogen solution for use in carbonless copying paper~ and the capsu~e walls in such systems generally may be formed from either natural or synthetic polymeric material. In the present invention, the capsule wall or shell is preferably made from a synthetic polymer, for example a polyurethane resin, a urea-formaldehyde resin, a melamine-formaldehyde resin or a polyamide resinO The use of such resins as ~ . .
.
.~ .
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~7~ ~ ~ 2 ~ ~ 6 shell-forming material in encapsulation is describea in, for example, U.S. Patent 3,016,308, British Patent 989,264 and U.S. Patent 3,429,827. Shells of this kind can be made significantly less permeable to the aliphatic benzyl phthalates used in the present invention than shells made of natural polymeric material such as gelatin.
The acid clay used as sensitizing agent for the chromogen in the present invention can be any of those conventionally used for this purpose, including bentonite and attapulgite. The naturally occurring clay may be subjected to various treatments such as o acid extraction or calcination before use as the sensi-tizing agent.
The mark-recording system of the present invention can be prepared according to well known conventional . procedures. Descriptions of methods for preparing both ~; the dye-carrying paper and clay-coated receiving paper are to be found in the literature.
Although a preferred embodiment of this inven-tion comprises a two-sheet system wherein the acid clay is carried by one sheet and a marking fluid comprising a chromogen and solvent is carried by a second sheet, the invention is not limited to such systems alone. The only essential requirement is that the chromogen and the acid clay be maintained in a separate or unreactive condi-.:
`; tion until pressure is applied to the system and that .~ upon the application of pressure the chromogen and acid i clay are brought into reactive contact. Thus it is ~; 30 possible to have the chromogen and acid clay present in 'i` a dry and unreactive state on a common carrier and to have the solvent alone carried on a separate sheet where-~` upon the application of pressure would release the solvent into the chromogen-acidic material mixture and promote localized reaction and color development. Obviously, many other arrangements, configurations and relationships ,~ . .
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of the solvent and the mark forming materials with respect to their encapsulation and location on the supporting sheet or webs can be envisaged, and such arrangements are within the scope of the present inven-tion. For example, it is possible to coat a singlepaper or support member with all the components of this system to form a single self-contained unit which can be marked by the movement of a stylus or other pressure-imparting means upon the surface of the paper. Such papers are particularly useful for use in inkless recording instruments.
Solutions of the invention were evaluated by the following technique:
A 0.5 percent by weight solution of Michler's hydrol p-toluene-sulfinate in the solvent was preparedO
To estimate print intensity, a plate engraved with a pattern of dots was coated with sufficient of the solu-tion to give a coating 18 microns in thickness, using a doctor blade. A carriage-supported roller having a paper sheet coated with an acid clay sensitizing agent wrapped round the roller was then moved slowly across the solution-coated plate under constant pressure. Color developed on the paper. The paper was removed from the roller, and the intensity of color was measured using a Macbeth RD 514 reflectometer calibrated against a "perfect white" of 0.07 units of optical density and a "perfect black" of 1.78 units of optical density, using standard "perfect white" and "perfect black" plates supplied by the manufacturer. After the initial reading, the paper was transferred to a cabinet at 75C. and 40 percent relative humidity. It was removed at intervals for further color intensity measurements.
To obtain the results shown in the tables below, the color intensity was measured each time at 25 different points on the paper surface and the values were averaged.
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The following abbreviations are used:
DBP - dibutyl phthalate DOP - dioctyl phthalate BBP - butyl benzyl phthalate OBP - octyl benzyl phthalate TBP - 2,6~6,8-tetramethyl-4-oxa-3-oxonon-7-yl benzyl phthalate ALB - (C8-alkyl)benzene Table 1 shows the results obtained using one manufacturer's clay-coated receiver sheets, the solvent in each case being a blend of the phthalate with either ALB in the proportions by weight 7:3 or with kerosene in the proportions by weight 8:2.
_ TIME (HOURS) Solvent 0 3 6 7 22.5 25.5 l DBP/ALB 7:3 0.616 0.532 0.492 2 OBP (Sample 1)/
ALB 7:3 0.628 o.648 0.577 20 3 OBP (Sample 2)/
ALB 7:3 o.606 0.624 0.544 4 OBP (Sample 3)/
~ ALB 7:3 o.600 0.635 0.566 ,~ 5 TBP/ALB 7:3 0O579 0.602 0.553 '25 6 OBP (Sam~le. 1)/
Kerosene 8:2 0.6210.585 0O577 0.571 ~-7 DBP/Kerosene 8:2 0.6010.568 0.519 0.472 ~ i;
~i' Comparison of Solvent 1 with Solvents 2-5, or of Solvent 6 with Solvent 7 shows that the print intensity fades significantly more slowly when the phthalate is an aliphatic benzyl phthalate than when the phthalate is , ~. .
dibutyl phthalateO
Table 2 shows the results obtained using a second l~ manufacturer's clay-coated receiver sheets.
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TABLE 2 ~ 6~26 TIME (HOURS) :, , Solvent 0 3 5.5 7 22 25.5 29.5 8 DBP 0.720 0.545 0.436 0O388 9 BBP 0.671 0.621 0.565 o.489 10 DBP/Kerosene 8:2 0.612 0.456 0.426 0.271 0.195 11 OBP/Kerosene 8:2 0.652 o.565 0.532 o.466 O 39 The superiority of the alkyl benzyl phthalates , over dibutyl phthalate is shown by a comparison of Solvent '~ 9 with Solvent 8 and of Solvent 11 with Solvent 10.
% ~ Table 3 shows the results obtained using the second manufacturer~s clay coated receiver sheets, the . 15 solvent being in each case a blend of the phthalate with ALB in the proportions by weight 7:3.
., ~ TIME (HOURS) %
: PHTHALATE 6.5 23 3o ~ . 20 DBP 0.776 0.582 0.360 0.313 :.; DOP 0.630 0.380 0.35 :::~ OBP (Sample 1) 0.689 0.628 0.417 0.401 OBP (Sample 2) o.656 0.626 0.507 0.468 '%~ OBP (Sample 3) 0.658 0.611 0.473 0.416 .~ 25 TBP 0.713 0.629 0.434 o.384 ".
,~i Color intensities are again shown to fade more ~ slowly when the solvent comprises an aliphatic benzyl ,~ phthalate than when the solvent comprises a dialkyl phthalate.
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As used herein3 the term "benzyl" is intended to cover both unsubstituted benzyl C6H5CH2- and alkyl-substituted benzyl. For example, the nucleus of the ~ 30 benzyl group may contain up to three alkyl substituents3 s~ each, for example, being an alkyl group having up to four carbon atoms, for instance methyl or ethyl; or one or both methylene hydrogen atoms of the benzyl group may be replaced by a similar alkyl group.
~ 35 Contemplated equivalents for use in the present sS~ invention are aliphatic benzyl phthalates as defined and ,. . . .
:: .
i:, .
s' ~
~ .
~5~ ~ 1~ 6~ ~ 6 described above except for the presence of one or more substituents on the aliphatic group or the benzyl group, the presence of which does not significantly affect the performance of the phthalates as dye solvents. Those skilled in the art would recognize various substituents which could be present on these aliphatic and/or benzyl groups which substituents would not be expected to significantly affect the performance of the phthalates as dye solvents. ~lso contemplated as equivalents are aliphatic benzyl phthalates as defined and described above except for the presence of a certain degree of olefinic unsaturation which does not significantly affect the performance of the phthalates as dye solvents.
Variations such as these are considered to be within the skill of the art and would not be a departure from the spirit of the present invention.
Specific examples of aliphatic benzyl phthalates useful in the present invention are butyl unsubstituted-benzyl phthalates, for instance n-butyl benzyl phthalate and isobutyl benzyl phthalate, octyl unsubstituted-benzyl phthalates, for instance n-octyl benzyl phthalate and 2-ethylhexyl benzyl phthalate, and 7(2,6,6,8-tetramethyl-4-oxa 3-oxononyl) unsubstituted-benzyl phthalate.
Those skilled in the art would know methods for the preparation of aliphatic benzyl phthalates useful in the present invention. Such preparation is described in U.S. Patent 3,483,247 issued December 9, 1969 to R. H.
Mills. Various aliphatic benzyl phthalates useful in the present invention are commercially available.
The solvents used in the present invention can contain more than one aliphatic benzyl phthalate, for example mixtures of alkyl benzyl phthalates having a range of alkyl group sizes, for instance a C5-C7, a C7-Cg or a C8-Cl2 range. The solvents may optionally contain other components,-for instance dialkyl phthalates such as dibutyl phthalate and dioctyl phthalates, and various ., .
,~ - , - .
~' ' : .
-6- ~ ~ ~6~26 hydrocarbons, for example C6 1~ alkylbenzenes, kerosene or other petroleum fractions which are useful as diluents in certain circumstances to reduce the viscosity of the solvent. Preferably the solvent contains at least 50 percent by weight of an aliphatic benzyl phthalate or of a mixture of aliphatic benzyl phthalates. The proportions by weight of the aliphatic benzyl phthalate and the diluent in mixtures may, for example, range from 50:50 to 90:10, for example 60:40, 70:30, 75:25 or 80:20. For rapid development of print intensity, the solvent is preferably one having a viscosity in the range 5 to 15 centistokes at 38C.
The concentration of the chromogen in a solution of the invention is generally of the same order as that in known solutions of chromogens which are diphenylmethanol or diphenylmethylamine derivatives, for example from 0.25 -to 5 percent, more particularly from o.LI to 4.0 percent by weight of the solution.
Chromogens ~hich are especially suitable for use in the present invention include Michler's hydrol, i.e., bis (p-dimethylaminophenyl)methanol, its ethers, for example the methyl ether of Michler's hydrol and the benzyl ether of Michler's hydrol~ aromatic sulfonic and sulfinic esters of Michler's hydrol, for example the p-toluenesulfinate of Michler~s hydrol, and derivatives of bis(p-dimethylaminophenyl) methylamine, for example N[bis(p-dimethylaminophenyl) methyl~morpholine.
Several encapsulation systems have been pro-posed for the encapsulation of the chromogen solution for use in carbonless copying paper~ and the capsu~e walls in such systems generally may be formed from either natural or synthetic polymeric material. In the present invention, the capsule wall or shell is preferably made from a synthetic polymer, for example a polyurethane resin, a urea-formaldehyde resin, a melamine-formaldehyde resin or a polyamide resinO The use of such resins as ~ . .
.
.~ .
: ~ .
~7~ ~ ~ 2 ~ ~ 6 shell-forming material in encapsulation is describea in, for example, U.S. Patent 3,016,308, British Patent 989,264 and U.S. Patent 3,429,827. Shells of this kind can be made significantly less permeable to the aliphatic benzyl phthalates used in the present invention than shells made of natural polymeric material such as gelatin.
The acid clay used as sensitizing agent for the chromogen in the present invention can be any of those conventionally used for this purpose, including bentonite and attapulgite. The naturally occurring clay may be subjected to various treatments such as o acid extraction or calcination before use as the sensi-tizing agent.
The mark-recording system of the present invention can be prepared according to well known conventional . procedures. Descriptions of methods for preparing both ~; the dye-carrying paper and clay-coated receiving paper are to be found in the literature.
Although a preferred embodiment of this inven-tion comprises a two-sheet system wherein the acid clay is carried by one sheet and a marking fluid comprising a chromogen and solvent is carried by a second sheet, the invention is not limited to such systems alone. The only essential requirement is that the chromogen and the acid clay be maintained in a separate or unreactive condi-.:
`; tion until pressure is applied to the system and that .~ upon the application of pressure the chromogen and acid i clay are brought into reactive contact. Thus it is ~; 30 possible to have the chromogen and acid clay present in 'i` a dry and unreactive state on a common carrier and to have the solvent alone carried on a separate sheet where-~` upon the application of pressure would release the solvent into the chromogen-acidic material mixture and promote localized reaction and color development. Obviously, many other arrangements, configurations and relationships ,~ . .
' ~ .
. . ~ .
.' ::
~' , ~
-8- ~ 2 ~
of the solvent and the mark forming materials with respect to their encapsulation and location on the supporting sheet or webs can be envisaged, and such arrangements are within the scope of the present inven-tion. For example, it is possible to coat a singlepaper or support member with all the components of this system to form a single self-contained unit which can be marked by the movement of a stylus or other pressure-imparting means upon the surface of the paper. Such papers are particularly useful for use in inkless recording instruments.
Solutions of the invention were evaluated by the following technique:
A 0.5 percent by weight solution of Michler's hydrol p-toluene-sulfinate in the solvent was preparedO
To estimate print intensity, a plate engraved with a pattern of dots was coated with sufficient of the solu-tion to give a coating 18 microns in thickness, using a doctor blade. A carriage-supported roller having a paper sheet coated with an acid clay sensitizing agent wrapped round the roller was then moved slowly across the solution-coated plate under constant pressure. Color developed on the paper. The paper was removed from the roller, and the intensity of color was measured using a Macbeth RD 514 reflectometer calibrated against a "perfect white" of 0.07 units of optical density and a "perfect black" of 1.78 units of optical density, using standard "perfect white" and "perfect black" plates supplied by the manufacturer. After the initial reading, the paper was transferred to a cabinet at 75C. and 40 percent relative humidity. It was removed at intervals for further color intensity measurements.
To obtain the results shown in the tables below, the color intensity was measured each time at 25 different points on the paper surface and the values were averaged.
-9~ 6~
The following abbreviations are used:
DBP - dibutyl phthalate DOP - dioctyl phthalate BBP - butyl benzyl phthalate OBP - octyl benzyl phthalate TBP - 2,6~6,8-tetramethyl-4-oxa-3-oxonon-7-yl benzyl phthalate ALB - (C8-alkyl)benzene Table 1 shows the results obtained using one manufacturer's clay-coated receiver sheets, the solvent in each case being a blend of the phthalate with either ALB in the proportions by weight 7:3 or with kerosene in the proportions by weight 8:2.
_ TIME (HOURS) Solvent 0 3 6 7 22.5 25.5 l DBP/ALB 7:3 0.616 0.532 0.492 2 OBP (Sample 1)/
ALB 7:3 0.628 o.648 0.577 20 3 OBP (Sample 2)/
ALB 7:3 o.606 0.624 0.544 4 OBP (Sample 3)/
~ ALB 7:3 o.600 0.635 0.566 ,~ 5 TBP/ALB 7:3 0O579 0.602 0.553 '25 6 OBP (Sam~le. 1)/
Kerosene 8:2 0.6210.585 0O577 0.571 ~-7 DBP/Kerosene 8:2 0.6010.568 0.519 0.472 ~ i;
~i' Comparison of Solvent 1 with Solvents 2-5, or of Solvent 6 with Solvent 7 shows that the print intensity fades significantly more slowly when the phthalate is an aliphatic benzyl phthalate than when the phthalate is , ~. .
dibutyl phthalateO
Table 2 shows the results obtained using a second l~ manufacturer's clay-coated receiver sheets.
,.. .
.
.$. .
, ,, ~ , , . ' ' .
~, ..
, .
TABLE 2 ~ 6~26 TIME (HOURS) :, , Solvent 0 3 5.5 7 22 25.5 29.5 8 DBP 0.720 0.545 0.436 0O388 9 BBP 0.671 0.621 0.565 o.489 10 DBP/Kerosene 8:2 0.612 0.456 0.426 0.271 0.195 11 OBP/Kerosene 8:2 0.652 o.565 0.532 o.466 O 39 The superiority of the alkyl benzyl phthalates , over dibutyl phthalate is shown by a comparison of Solvent '~ 9 with Solvent 8 and of Solvent 11 with Solvent 10.
% ~ Table 3 shows the results obtained using the second manufacturer~s clay coated receiver sheets, the . 15 solvent being in each case a blend of the phthalate with ALB in the proportions by weight 7:3.
., ~ TIME (HOURS) %
: PHTHALATE 6.5 23 3o ~ . 20 DBP 0.776 0.582 0.360 0.313 :.; DOP 0.630 0.380 0.35 :::~ OBP (Sample 1) 0.689 0.628 0.417 0.401 OBP (Sample 2) o.656 0.626 0.507 0.468 '%~ OBP (Sample 3) 0.658 0.611 0.473 0.416 .~ 25 TBP 0.713 0.629 0.434 o.384 ".
,~i Color intensities are again shown to fade more ~ slowly when the solvent comprises an aliphatic benzyl ,~ phthalate than when the solvent comprises a dialkyl phthalate.
,,~ ,~
- -'~ ' ' .~
.~
, ~ .
:
:
Claims (10)
1. A pressure-sensitive mark-recording system comprising (a) sheet material, (b) mark-forming compo-nents supported by the sheet material and arranged in juxtaposition but in unreactive condition, the said components comprising a chromogen which is a derivative of diphenylmethanol or diphenylmethylamine and an acid clay sensitizer for the chromogen which produces a color from the chromogen when brought into contact with the chromogen in the presence of a liquid solvent for the chromogen and (c) the said liquid solvent supported by the sheet material but separated from the sensitizing agent by a physical barrier which is rupturable on the application of a marking instrument to the sheet material, characterized in that the liquid solvent comprises an aliphatic benzyl phthalate.
2. A system in accordance with Claim 1 wherein the aliphatic group of the aliphatic benzyl phthalate is an alkyl group containing up to 24 carbon atoms.
3. A system in accordance with Claim 2 wherein the aliphatic benzyl phthalate is a butyl unsubstituted-benzyl phthalate or an octyl unsubstituted-benzyl phthalate.
4. A system in accordance with Claim 1 wherein the aliphatic group of the aliphatic benzyl phthalate is derived from an alkyl ester of a hydroxy-carboxylic acid or from a hydroxy (C1-12 alkyl) ester of a C1-12-carboxylic acid.
5. A system in accordance with Claim 4 wherein the aliphatic benzyl phthalate is 7(2,6,6,8-tetramethyl-4-oxa-3-oxononyl) unsubstituted-benzyl phthalate.
6. A system in accordance with Claim l in which the aliphatic group of the aliphatic benzyl phthalate is an alkyl group containing from 2 to 12 carbon atoms.
7. A system in accordance with Claim 1, 2 or 3, wherein the solvent is a mixture of at least one aliphatic benzyl phthalate and a hydrocarbon diluent, which mixture contains at least 50 percent by weight of aliphatic benzyl phthalate.
8. A system in accordance with Claim 4, 5 or 6, wherein the solvent is a mixture of at least one aliphatic benzyl phthalate and a hydrocarbon diluent, which mixture contains at least 50 percent by weight of aliphatic benzyl phthalate.
9. A system in accordance with Claim 1, 2 or 3, wherein the chromogen comprises a compound selected from the group consisting of Michler's hydrol, ethers of Michler's hydrol, aromatic sulfonic esters of Michler's hydrol and aromatic sulfinic esters of Michler's hydrol.
10. A system in accordance with Claim 4, 5 or 6, wherein the chromogen comprises a compound selected from the group consisting of Michler's hydrol, ethers of Michler's hydrol, aromatic sulfonic esters of Michler's hydrol and aromatic sulfinic esters of Michler's hydrol.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB25960/78 | 1978-05-31 | ||
| GB2596078 | 1978-05-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1126026A true CA1126026A (en) | 1982-06-22 |
Family
ID=10236113
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA328,731A Expired CA1126026A (en) | 1978-05-31 | 1979-05-30 | Pressure-sensitive mark-recording systems |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0005921B1 (en) |
| JP (1) | JPS552090A (en) |
| AT (1) | ATE1699T1 (en) |
| AU (1) | AU528695B2 (en) |
| CA (1) | CA1126026A (en) |
| DE (1) | DE2963924D1 (en) |
| FI (1) | FI70180C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57116690A (en) * | 1981-01-13 | 1982-07-20 | Ricoh Co Ltd | Thermal recording material |
| US5318940A (en) * | 1992-12-02 | 1994-06-07 | Koch Industries, Inc. | Carbonless paper solvent comprising diisopropylbiphenyl and triisopropylbiphenyl and products utilizing same |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3016308A (en) * | 1957-08-06 | 1962-01-09 | Moore Business Forms Inc | Recording paper coated with microscopic capsules of coloring material, capsules and method of making |
| US3684549A (en) * | 1970-10-12 | 1972-08-15 | Joseph L Shank | Pressure sensitive transfer coating |
| JPS4931414A (en) * | 1972-07-05 | 1974-03-20 | ||
| DE2334227A1 (en) * | 1973-07-05 | 1975-01-23 | Basf Ag | HANDLING, PRESSURE-SENSITIVE TRANSPARENCY |
| US4093278A (en) * | 1976-12-27 | 1978-06-06 | Monsanto Company | Dye solvents for pressure-sensitive copying systems |
-
1979
- 1979-05-10 EP EP79300801A patent/EP0005921B1/en not_active Expired
- 1979-05-10 AT AT79300801T patent/ATE1699T1/en active
- 1979-05-10 DE DE7979300801T patent/DE2963924D1/en not_active Expired
- 1979-05-24 FI FI791647A patent/FI70180C/en not_active IP Right Cessation
- 1979-05-28 AU AU47478/79A patent/AU528695B2/en not_active Ceased
- 1979-05-29 JP JP6569279A patent/JPS552090A/en active Pending
- 1979-05-30 CA CA328,731A patent/CA1126026A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FI791647A (en) | 1979-12-01 |
| EP0005921A1 (en) | 1979-12-12 |
| AU528695B2 (en) | 1983-05-12 |
| EP0005921B1 (en) | 1982-10-27 |
| FI70180B (en) | 1986-02-28 |
| DE2963924D1 (en) | 1982-12-02 |
| FI70180C (en) | 1986-09-15 |
| AU4747879A (en) | 1980-02-07 |
| JPS552090A (en) | 1980-01-09 |
| ATE1699T1 (en) | 1982-11-15 |
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| MKEX | Expiry | ||
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