LU81937A1 - SINGLE PRESSURE SENSITIVE CHROMOGENEOUS RECORDING PAPER OF THE SINGLE LAYER TYPE - Google Patents

Description

! i J “- ™ - GRAND-DUCHY OF LUXEMBOURG D * 50.891 \” "8Ίό-3,7 du., 29. nQy! ßIttDlSl X5Γ, / 9 (ŒæO Minister rSrSrSa of the National Economy and the Middle Classes

Book title: ........................................

LUXEMBOURG Industrial Property Service

Patent Application I. Application

The ... sQciét.ê ..... said; ...... MITSUBISHI ..... PAPERMILLS., ..... LTD ..., ..... 6-2 .. .................................................. .. (1)

Marunouchi-2-chome, Chiyoda-ku, TOKYO, Japan, represented by Mister Jacques ..... de Muyser acting as agent ^ deposit ........ this ..vfagt-neuf november 19oo sixty- nineteen.................

at ......... i.§ ............... hours, at the Ministry of National Economy and the Middle Classes, in Luxembourg: 1. this request for obtaining a patent for an invention concerning: "Autonomous chromogenic recording paper sensitive ..... to .................. ^ ... ..pres.s.iQ.n ..... dtt ..... typ © ...... âi ..... Tan.e ..... s..e.ule .. ....layer"..,......................................... .................................................. ...........................

declares, assuming responsibility for this declaration, that the inventor (s) is (are): VQir .... au .... vers.o ............ .................................................. .................................................. .................................................. .................................................. ........ (5) 2. the delegation of power, dated ........ ï.Ql.vYQ ................. ......................... le .i.3 ..... noyeinbr.e ..... 1979 3. description in language fÇânÇ ^ iS6 ....................................... of the invention in two copies; 4 ........... U ........... drawing boards, in two copies; 5. the receipt of the taxes paid to the Luxembourg Registration Office on ...... 21 .... nQveiiibra .... ig7.â .............. .................................................. .................................................. .................................................. .....................................

(6) ............................................... ............................................... filed (s) ) in (7) ............................................. .................................................. .......................................

the ................................................. .................................................. .................................................. .................................................. .................................................. ...................... (8). on behalf of ............................................... .................................................. .................................................. .................................................. ................................................ (9 ) elect domicile for him / her and, if designated, for his / her representative, in Luxembourg ______________________________________ 35. bd. Royal ............................................... (io ) requests the issuance of a patent for the subject described and represented in the abovementioned appendices, - with postponement of this grant to .................... ..... ........ months.

Vfî ... 9.X .......................

II. Deposit Minutes

The above application for a patent for invention has been filed with the Ministry of National Economy and the Middle Classes, Industrial Property Service in Luxembourg, dated: November 29, 1979 / <? Pr. The Minister at .................. 3 pm / S / • d.X of the National Economy and Average desolasses, BUh 11 'iiÆ ν' · -.

η,,. a 68007 _ \%: -r Jy_ / _ "'f \ 1 *" /; 1. - Koji TOYAMA, lo5, Sakaemachi, Takasagocho, TAKASAGO-SHI, Japan 2, - Mitsuru FUCHIGÄMI, lo5, Sakaemachi, Takasagocho, TAKASAGO-SHI,

Japan 3. - Isao NAGAYASU, lo5, Sakaemachi, Takasagocho, TAKASAGO-SHI,

Japan 4, - Hirokazu TSUKAHARA, lo5, Sakaemachi, Takasagocho, TAKASAGO- SHI, Japan i: D. 50 * 891 t ï (! Brief Description filed in support of a request for

PATENT

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Luxembourg I formed by: MITSUBISHI PAPER MILLS, LTD.

for: Single layer chromogenic pressure sensitive recording paper of the single layer type,

AT

i; The present invention relates to a new structure of a pressure-sensitive recording paper. More particularly, the invention relates to an improvement made to an autonomous chromogenic pressure-sensitive recording paper comprising a support sheet coated with a single recording layer consisting of a mixture of microcapsules containing a chromogenic coupler and of microcapsules containing a color developer.

An ordinary so-called pressure-sensitive paper system consists of a so-called upper sheet comprising a support material coated with a layer of capsules containing a chromogenic coupler such as crystallized violet lactone or benzoyl-leucomethylene blue, as well as of an underlying sheet comprising a support sheet coated with a layer of an activated clay or an organic acid substance such as acid clay, activated clay, a phenolic resin or a compound of an acid aromatic carboxylic. When the two sheets are brought together so that their coated surfaces come into contact with each other and when local pressure is exerted on the top sheet by means of a writing instrument, a color image appears on the underlying leaf under the effect of localized pressure.

Recently, pressure-sensitive recording paper has been described in which the above-mentioned color-forming mechanism is used to obtain a character printing image without having to use a conventional inked tape for typewriters.

4s

This recording paper is made up of two layers of a different anoloidous composition, the one being generally made up of microcapsules containing a chromogenic coupler dissolved in an oily liquid, while the upper coating is made up of a chromogenic revelate. dispersed developing colors when it comes into contact with this chromogenic coupler. When localized marking pressure is applied to the coating layers, the capsules in the area where the marking pressure is applied are broken and release the oily liquid containing the chromogenic coupler forming colored images on contact with the chromogenic developer . This type of pressure-sensitive recording paper is usually called "color-developing pressure-sensitive recording paper" or "self-contained recording paper". The present invention provides a new structure of an improved stand-alone recording paper.

Conventional stand-alone recording paper is made by a two-step process, the first of which consists of forming an underlying coating of microcapsules, while the second of which consists of forming an upper coating of a color developer; as a result, productivity (encompassing operational efficiency and product yield) is significantly reduced. In addition to the increased costs resulting from the application of two layers of an aqueous composition, the conventional method also requires additional expenditure for its control in order to avoid the folding or wrinkling which the paper may accidentally undergo, as well as in order to '' avoid the accidental application of light pressure during manufacture, which will give rise to the formation of stains following the development of colors.

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Under these conditions, the Applicant undertook to develop processes with a view to manufacturing, in a single step, an autonomous chromogenic pressure-sensitive recording paper and it brought a certain number of new techniques.

According to the present invention, a new structure is proposed in order to obtain a stand-alone chromogenic pressure-sensitive recording paper of the single-layer type of superior quality, this paper being characterized in that, in the coating layer, an agent protecting the capsules against accidental breakage.

! Hitherto, the Applicant has mainly used starch particles as a protective agent! capsule maker for single layer chromogenic recording paper of the single layer type. However, in order to ensure satisfactory protection of the capsules, it was necessary to add the starch in an amount as high as 150 parts by weight or more per 100 parts by weight of capsules, this inevitably to the detriment of the chromogenic yield. important recording paper. When the starch is added in an amount sufficient to protect the recording paper from soiling due to accidental chromogenic development, there is at the same time some reduction in the intensity of the developed color.

The object of the present invention is to avoid these drawbacks of the prior art. According to the present invention, instead of starch, a powdered polyolefin is used. When incorporating a poly-; - 5 - ί

Iolefin powder instead of starch, we get a surprising result because, although the protective effect against soiling is sufficient, -the ability to chromogenic development of the image remains at a high level. This result has enabled the Applicant to arrive at the present invention.

Although the reason for this phenomenon has not yet been sufficiently explained, the superiority of a powdered polyolefin over starch particles seems to come from the difference in hardness, for comparison, by machine coated, a single layer chromogenic pressure sensitive recording paper of the single layer type is prepared in which starch particles are incorporated as protective agent for the capsules, as well as another paper in which incorporates a powdered polyolefin, then prints are formed therein by means of a typewriter without using an inked ribbon. The printed and unprinted areas of the two recording papers were examined using a scanning electron microscope. In the case of recording paper containing starch, it is noted that the starch particles remain unchanged in both the printed areas and the unprinted areas, while only the microcapsules are broken in the printed areas; in the case of recording paper containing a polyolefin, the microcapsules and the polyolefin particles are neither broken nor deformed in the unprinted areas while, in the printed areas, the! - · | microcapsules are broken and the polyolefin particles t i present held signs of rupture or deformation.

The above considerations seem to suggest that the polyolefin particles act satisfactorily as an agent to protect the capsules from relatively low localized pressures, while they are broken or deformed by a strong impact such as that exerted during of printing with a typewriter, while the effective rupture of the microcapsules is hardly hindered. This appears to be the cause of the desirable chromogenic development occurring when printing with a typewriter.

Another important feature of the recording paper of the present invention is the marked reduction in the formation of soiling due to accidental folding of the recording paper. Whether it is of the multi-layer or single-layer type, in a conventional chromogenic pressure-sensitive self-contained paper, stains are formed as a result of chromic development! homogeneous occurring along the fold line, while the single layer type recording paper according to the present invention better resists this formation of stains and offers better practical use. tick compared to that containing starch. Onne

I can explain the reason for this phenomenon, but the fact remains obvious.

According to the literature [”Kagaku Daijiten” (Comprehensive Chemical Dictionary), published by Kyoritsu -

Publishing Ce.], The densities of the starch grains and of the polyethylene are respectively 1.62-1.65 and 0.9-0 * 96, which suggests a significant difference in hardness.

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In Japanese patent application 117 * 734/77 (title: "Pressure-sensitive copy paper") of the Applicant, it has already been described that a powdered polyolefin was useful as a protective agent for the microcapsules in a pressure sensitive recording paper | if we. However, this patent application relates only to a top sheet in a set of pressure-sensitive copy sheets of a separate type (set of several copy sheets essentially comprising a sheet coated with microcapsules, i.e. the top sheet, and a sheet coated with a solid acid, i.e. the underlying sheet or a self-contained copy paper of the multi-layer type.

It is understood that these are the last studies which have revealed the specific effect of a polyolefin, an effect which is completely! different from that of starch in recording paper i; autonomous of the single layer type and, moreover, | results of these studies resulted in the present invention, ij; j Since, in self-recording paper of the single layer type, the chromogenic coupler (pressure sensitive dye) and developer j chromogenic (acidic substance) are enclosed in capsules, '5' r, it is likely that the total quantity of capsules per unit, of surface is approximately equal to twice that of the type with ► 'Ir several layers} in consequence, not only the granula- | rity of the particles, but also the physical properties i 'of the protective agent of the capsules exert an im-1 effect on the resistance of the capsules to rupture, g In order to satisfy the conditions required for obtaining a quality design, the polyolefin powder i can be used in conjunction with ä »starch particles without significantly altering the benefits of this polyolefin.

Without any limiting nature, among the methods which can be adopted according to the present invention for the formation of microcapsules, mention will be made of: (1) the separation of the phases in aqueous solutions (see, for example, the United States patents of America Nos. 2,800,457 and 2,800,458), (2) interfacial polymerization (for example, Japanese patent publications 19 * 574/63, 446/67 and 771/67), (3) polymerization of monomers (for example , Japanese Patent Publication No. 9,168 / 61 in Japanese Patent Application Published but Unexamined 9,079 / 76), (4) cooling a melt dispersion (for example, British Patents No. I 952,807 and 965.074), and (5) spray drying (for example, U.S. Patent No. 3 * 111,407 and British Patent 930,422),

Among the suitable color couplers: there are the leuco dyes known for pressure-sensitive recording papers, for example, triphenylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds and spiropyran compounds. These chromogenic couplers are dissolved or dispersed in a suitable oily solvent or emulsified into tiny droplets in water or a lyophilic solvent, then coated in microcapsules by an appropriate "" process. The suitable oily solvents are chosen from non-volatile solvents such as alkyl naphthalenes, diarylethanes, alkyl diphenyls, terphenyls, hydrogenated and esters.

The most suitable microcapsules containing chromogenic developers are those in which the walls consist essentially of a urea / formaldehyde resin, the internal phase consisting of acidic organic substances dissolved in or swollen with an oily solvent. The microcapsule coating processes in which a urea / formaldehyde resin is used as the material forming the walls, have been described in the published but unexamined Japanese patent application t 9.079 / 76, the Japanese patent publications 30.282 / 71 and 23.165 / 72. Oily solvents suitable for dissolving or swelling the color developers are chosen from toluene, xylene, alkyl naphthalenes, diarylethanes, alkyl diphenyls and esters. Among the acidic organic compounds, desirable color developers are different oil-soluble phenolic resins and different compounds of oil-soluble aromatic carboxylic acids.

Among suitable polyolefins are homopolymers of olefins such as, for example, ethylene, propylene and styrene, copolymers of two or more olefins, as well as blends of these polymers. An aqueous suspension of powdered polyolefins can be prepared by modifying a polyolefin resin with an unsaturated carboxylic acid such as, for example, maleic anhydride, by melting the modified resin if necessary with a surfactant. dispersing agent in hot water (Japanese patent application published but not examined 36,540 / 75) or by heating a mixture of a polyolefin, an organic solvent, a surfactant! non-ionic active ingredient and water at a temperature above the melting point of the polyolefin, then cooling the heated mixture to a temperature below the melting point]

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of this polyolefin to obtain an emulsion which is then released from the organic solvent (Japanese patent application published but not examined 138,735 / 76). However, the powdered polyolefins which can be used are not necessarily prepared by the above methods.

According to the methods described above, it is easy to obtain powdered polyolefins whose particles have a diameter of between 5 and 30 J * · and which are in spherical form, these polyolefins being suitable as a protective agent for microcapsules according to the present invention. A desirable result is obtained by adding a powdered polyolefin to the coating composition in the form of an aqueous dispersion as such.

Preferably, the particle diameter of the powdered polyolefin is between 10 and 30 µm. The softening point should be higher than the maximum paper temperature during the application of the pressure-sensitive recording layer and , preferably, this softening point is 70 ° C or more. Preferably, the quantity in which the powdered polyolefin must be added, is between $ 50 and $ 250, better still, between $ 100 and $ 200, calculated, * on the weight of the capsules in order to obtain a recording paper. Completely self-contained pressure sensitive of the single layer type in which the capsules are suitably protected against accidentally applied pressure, while imparting satisfactory density to the printed image.

The amount of the polyolefin powder can be replaced by an appropriate amount of starch, but at the expense of the effect of reducing stains resulting from folding the recording paper. The practical amount to replace is $ 70 maximum.

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Previously, the Applicant has proposed using plastic pigments in pressure-sensitive autonomous recording paper (Japanese patent application 134,732 / $ 77 title: "chromogenic pressure-sensitive autonomous recording paper"). However, plastic pigments are generally finely divided particles with a diameter of 1 jx or less and they have no ability to protect the capsules from accidental application of pressure. The plastic pigments can be easily distinguished from the powdered polyolefin (diameter! About 20 μm and excellent ability to protect the capsules against accidental application of pressure) used according to the present invention; moreover, they are used for purposes totally different from those of the present invention.

In actual practice, a single layer, pressure sensitive, chromogenic self-recording recording paper is prepared by mixing together an aqueous dispersion of a powdered polyolefin, microcapsules containing a chromogenic coupler, microcapsules containing a developer. chromogenic and, if necessary, a resin. water-soluble amine such as a cation-modified urea resin or a cation-modified polyamide / epichlorohydrin resin, by adding, to the mixture obtained, a binding agent such as polyvinyl alcohol, a latex, hydroxy- ethyl cellulose or oxidized starch, a clay such as kaolin, montmorillonite or talc, as well as other usual additives in order to obtain a coating composition, then by applying this composition to the support paper by means of '' an air knife, blade, roller, bar or other coating machine.

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As described above, the present invention is very useful for the manufacture of self-contained chromogenic pressure sensitive recording papers of the single layer type.

The invention will be illustrated in more detail "by the following examples which however do not limit it in any way. In these examples, all parts are by weight. Example 1

Preparation of microcapsules containing a chromogenic coupler:

A solution is prepared by mixing 100 parts of a 10% aqueous solution of a copolymer of ethylene and maleic anhydride, 10 parts of urea, 1 part of resorcinol and 200 parts of water. The solution obtained is adjusted to a pH of 3.5 with an aqueous solution of sodium hydroxide at $ 20. A solution of a chromogenic coupler is prepared by dissolving 10 parts of crystallized violet lactone in 90 parts of diisopropylnaphthalene. This solution is dispersed in the aqueous solution prepared above to obtain an oil-in-water type emulsion containing dispersed oil droplets with a diameter of 3 to 5 J * ·· After adding 25 parts of formalin to $ 37, the emulsion is kept at a temperature of 55 ° C. After 2 hours, around each droplet, a wall is formed consisting of a membrane of the urea / formaldehyde condensate. The emulsion is then adjusted to a pH of 9.5 by adding dropwise a 20% aqueous solution of sodium hydroxide in order to complete the coating in capsules, while a dispersion of micro- capsules containing a chromogenic coupler.

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Preparation of microcapsules containing a chromogenic developer

A solution is prepared by mixing together 200 parts of a 10% aqueous solution of an ethylene / maleic anhydride copolymer, 20 parts of urea, 2 parts of resorcinol and 400 parts of water. The solution obtained is adjusted to a pH of 3.5 with an aqueous solution of sodium hydroxide at $ 20. A color developing solution is prepared by dissolving 100 parts of a p-phenylphenol / formaldehyde resin in 100 parts of diisopropylnaphthalene while heating. This solution is dispersed in the aqueous solution obtained above to form a crumb of the oil-in-water type containing oil droplets with a diameter of 3 to 5 µi. The emulsion is mixed with 50 parts of 37% formalin and kept at a temperature of 55 ° C while stirring. After two hours, around each droplet of oil, a wall is formed consisting of a membrane of a urea / formaldehyde condensate. The emulsion is adjusted to a pH of 9f5 in order to complete the coating in capsules and a dispersion of microcapsules containing a color developer is obtained.

Preparation of a stand-alone chromogenic recording paper · * pressure sensitive, single layer type;

A uniform and autonomous coating composition is prepared by mixing the dispersions obtained i: above capsules containing a chromogenic coupler and capsules containing a chromogenic developer, respectively in the amounts of 20 parts by weight and 30 parts by weight, 300 parts of a 5% aqueous polyvinyl solution 3 30 parts of kaolin, 40 parts of a 5% aqueous solution of a cation-modified polyamide / epichlorohydrin resin and 200 parts (80 parts dry) of a dispersior / at 40 / w of polyethylene powder in water ("Chemi-Pearl" i

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sold by "Mitsui Petrochemical Co." J softening point: 76 ° C. Diameter of the particles of the dispersed polyethylene: The above coating composition is applied to a support sheet with a basis weight of 50 g / m2 and at a rate of 8-9 g. / m2 by means of an air knife coating apparatus in order to obtain an autonomous chromogenic pressure-sensitive recording paper of the single-layer type.

Comparative example 1

Preparation of a single layer chromogenic pressure sensitive recording paper of the single layer type:

One obtains a self-recording chromogenic pressure-sensitive recording paper of the type to one! layer by repeating the processes of Example 1, with the exception that, instead of powdered polyethylene, 150 parts of starch particles and 50 parts of water are used. Example 2

Preparation of self-contained chromogenic pressure-sensitive recording paper of the single-layer type î

A self-adhesive, chromogenic pressure-sensitive recording paper of the single-layer type is obtained by repeating the procedures of Example 1, with the exception that the amount of the aqueous dispersion at 40% I of the powdered polyethylene is 150 parts (60 dry parts) instead of 200 parts.

Example 3

Preparation of a single layer chromogenic pressure-sensitive recording paper I of the single layer type:

A single layer chromogenic pressure sensitive recording paper of the single layer type is obtained by repeating the procedures of Example 1, with this

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t * - 15 - <] at 40% polyethylene powder, 100 parts (40 parts dry) of this dispersion are used, 75 parts of particles! starch and 25 parts of water.

Example 4

Preparation of a single layer chromogenic pressure sensitive recording paper of the single layer type:

A single layer chromogenic pressure sensitive recording paper of the single layer type is obtained by repeating the procedures of Example 1, with the exception that instead of polyethylene, polyethylene powder modified with a carboxy group is used having a point! softening of 70 ° C and en particles with a diameter of 20 jx.

EXAMPLE 5 The tests for determining the quality are carried out on the sheets of chromogenic pressure-sensitive autonomous recording paper of the single-layer type which were obtained in examples 1 to 4 and in the comparative example. 1 · The results obtained are shown in the table below.

. TI FS Chromo development {%) {%) gene due to crease; Example 1 54 96 0.12 I Comparative example 1 70 95 0.32

Example 2 54 94 0.17

Example 3 57 95 0.20; Example 4 50 97 0.14 i! In the table above, "TI" indicates the intensity of the color of the image developed by printing with a typewriter, while "FS" indicates the soils - 16 - 1 4 lures caused by friction; the TI and FS values are calculated by the following formula:

Reflective power of the printed area or the soiled area_ χ

Reflective power of the unaffected area K ‘/ 0} *

A higher TI or FS value indicates a lower or more intense color in the image | weak formation of stains. The chromogenic development resulting from creasing is evaluated according to the reflection density measured by means of a microdensitometer in the area where. the stains result from wrinkling. A lower value indicates a lower level of soiling · From the results shown in the table above, it can be seen that, compared to the self-contained pressure sensitive recording paper of the single layer type obtained Comparative example 1, the papers obtained in accordance with the present invention in examples 1 to 4 have markedly higher TI values and that much less soil is formed there as a result of crumpling, while the FS values remain comparable, which demonstrates the remarkable effect exerted by powdered polyolefins.

Claims (4)

1. Autonomous chromogenic pressure-sensitive recording paper of the single-layer type obtained by applying, to a sheet of support paper, a coating of a uniform mixture of an aqueous suspension of microcapsules containing a chromogenic coupler and an aqueous suspension of microcapsules containing a chromogenic developer, in order to “then carry out drying, characterized in that a powdered polyolefin is added to this coating mixture. 2. Registration paper according to resale | dication 1, characterized in that the polyolefin powder is added in an amount of 50 to 250 parts by weight per 100 parts by weight of the total quantity of capsules. 3. Recording paper according to claim 2, characterized in that the quantity of the polyolefin powder is replaced at a rate of $ 70 maximum by starch particles. 4. Recording paper according to any one of claims 1 to characterized in that the polyolefin powder contains a major amount of polyethylene t whose particles have an average diameter of 10 'to 30 and which are added in the form of an aqueous dispersion. I \ '.