JP3633649B2 - How to make pressure-sensitive copying paper - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for producing a carbonless copy paper, and more specifically, an oil-based ink containing color former microcapsules is prepared, and this is printed by a pressure transfer type printing machine to form a coating layer thereof. Specifically, the present invention relates to a method for producing pressure-sensitive copying paper in which a coating layer can be freely provided at a desired location by printing using oil-based ink containing microcapsules. By mixing a solvent that is compatible with both the vehicle of oil-based ink and the surface layer of the capsule wall material in the capsule aqueous dispersion, the moisture is evaporated and removed so that the microcapsules do not coagulate with each other. A color former microcapsule-containing oil-based ink is prepared by dispersing and dispersing while maintaining the physical properties such as elasticity and strength of the material. The coating layer pressure transfer method consisting, i.e., the ordinary printing method, to a method to create a pressure-sensitive copying paper, characterized in that applying to a predetermined portion of the seat surface.
[0002]
[Prior art]
Conventionally, a microcapsule containing a color former is generally produced in an aqueous system, and when the aqueous coating thus produced is partially printed by flexographic printing on the sheet surface, wrinkles are formed in the portion. Therefore, a coating layer is provided on the entire surface of the sheet by air knife coating or the like. Therefore, the coating layer can be freely formed on a predetermined portion of the sheet surface using a conventional pressure transfer type printing machine. It wasn't.
[0003]
Therefore, when a coloring function is provided only on a predetermined part of the sheet surface, the color is developed on one side of the sheet that contacts the copy sheet (hereinafter referred to as the upper sheet) coated with color former microcapsules on one side of the sheet. The developer of the copy paper (hereinafter referred to as the lower paper) coated with the colorant or the copy paper (hereinafter referred to as the middle paper) in which the microcapsules of the color developer and the color developer are applied to both sides of the sheet. Printing with a special ink that inhibits color development, that is, desensitization printing, was performed on a predetermined portion of the coated surface.
[0004]
[Problems to be solved by the invention]
However, in such a configuration that partially prevents color development by desensitizing printing, if there is uneven printing or if the printing amount is small, the color development reaction cannot be inhibited, and thus it is necessary to inhibit color development. Since the desensitized ink is a special ink, the tack is higher and the flow is lower than the normal ink. It was necessary to use a unit or reduce the operation speed, resulting in poor productivity and high costs.
Furthermore, conventional pressure-sensitive copying paper is usually made of high-quality paper for copying because of its applicability, and is not suitable for printing paper such as art paper, coated paper, gravure paper, synthetic paper, thin paper, and sandwich paper. It was extremely unsuitable, and in particular, it was practically impossible to make upper sheets or medium sheets made of these sheets.
[0005]
Therefore, in the present invention, color former microcapsules can be freely applied to a predetermined portion of the sheet surface in parallel with printing of a predetermined item on the sheet surface by a conventional pressure transfer type printing machine for all types of printing paper. An object of the present invention is to provide a method for producing a pressure-sensitive copying paper, which is characterized by forming a coating film.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the pressure-sensitive copying paper producing method of the present invention is a pressure-sensitive copying paper producing method in which a coating layer of oil-based ink containing a color former microcapsule is provided on a predetermined portion of a sheet surface,
In a microcapsule aqueous dispersion obtained by forming microcapsules in an aqueous system, a solvent compatible with both the vehicle of the oil-based ink and the surface layer of the capsule wall material is mixed with the vehicle, and at this time, the boiling point is higher than the boiling point of water. By using a vehicle having water and vaporizing and removing the water, the microcapsules can be dispersed and dispersed in the vehicle without agglomerating the microcapsules with each other and while maintaining the physical properties of the capsule wall material. the color former microcapsules containing oil-based ink comprising, by printing in a predetermined portion of the sheet surface with a printing press of pressure transfer method, and forms the subject film layer. A relief offset printing press can be used as the printing press. The water can be vaporized and removed by vacuum distillation.
[0007]
[Action]
The oil-based ink containing the color former microcapsule prepared by the oil-based printing ink and the color former microcapsule is replaced in the oil-based ink vehicle while maintaining the physical properties such as elasticity and strength when the capsule is formed in the aqueous system. Because it is in a distributed state, it can be printed by a pressure transfer type printing machine. Therefore, for any type of printing paper, it can be freely applied to a predetermined part of the sheet surface in parallel with normal printing on the sheet surface. Furthermore, a coating layer of oil-based ink containing color former microcapsules can be formed.
[0008]
【Example】
The present invention will be described in detail based on the following examples. First, a microcapsule containing a color former generated in an aqueous system is dispersed in an oil-based printing ink vehicle. The preparation method will be described in detail.
[0009]
The color former that is the core material of the microcapsule and the capsule wall material in the present invention is not particularly limited, and the color former is a dye or dye precursor that reacts with the developer to develop color, For example, leuco dyes such as crystal violet lactone, and other dyes such as xanthene, merocyanine, thiazine, azine, methine, azo, pyrazoline, stilbene, coumarin, and phenylmethane. Examples of the dye precursor include diphenylmethane compounds, triphenylmethane compounds, bisphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds, and mixtures thereof.
[0010]
On the other hand, the capsule wall material is polyamide, polyurethane, polyester, polyurea, polysulfonamide, polysulfonate, polyurea, etc., and the capsule wall generating means is a conventionally used method, for example, in situ method, interface A condensation polymerization method, a coacervation method, or an orifice method can be used, and these are encapsulated in an aqueous system.
[0011]
For example, a partial hydrolysis product of styrene maleic anhydride having a leuco dye as a color former, an acid catalyst and an emulsifying function, and melamine or urea and formalin as a reaction component for forming a polymer, or an initial polycondensate thereof. A melamine or urea-formalin resin used as a capsule wall material by an in situ method and dispersed in an aqueous system is most suitable in the present invention.
[0012]
In addition, a capsule wall material and a layer of an acid catalyst having an emulsification / dispersion function, for example, a partial hydrolyzate of a styrene maleic anhydride copolymer, form a surface layer on the microcapsule so as to cover the capsule wall material. In this case, the hydrophilic group of the acid catalyst exposed on the surface of the capsule wall material, for example, styrene maleic anhydride copolymer, the carboxyl group is hydrogen-bonded to water molecules in an aqueous dispersion state. When a solvent sharing hydrophilicity and hydrophobicity is mixed with the liquid, the hydrophilic groups of this solvent hydrogen bond with the hydrophilic groups of the acid catalyst while the surface of the capsule wall material is water-retained. The vehicle components are those that are compatible with each other via the acid catalyst.
[0013]
Note that the amount of this solvent added to the microcapsule aqueous dispersion is the minimum amount that can maintain the affinity function corresponding to the total surface area of the microcapsule particles, while taking into consideration the decrease in printability due to excessive addition amount, etc. In addition, 5 to 100% by weight is appropriate, preferably 20 to 85% by weight, and more preferably 30 to 70% by weight, based on the solid content of the microcapsule aqueous dispersion.
[0014]
In the present invention, the vehicle component of the oil-based ink needs to be selectively vaporized and removed by vacuum distillation, and therefore has a boiling point at least higher than that of water. For example, in the UV curable type, acrylic acid is ester-reacted or ether-reacted to have an unsaturated group, that is, methyl acrylate, methyl acrylate, polyhydric alcohol acrylate, epoxy acrylate, urethane Monomers or oligomers such as acrylates, polyester-based acrylates, polyether-based acrylates, or oxidative polymerization types, for example, vegetable oils, dryness such as flaxseed oil and cinnaqi oil mainly composed of oleic acid, linolenic acid, and linoleic acid Oils, semi-drying oils such as soybean oil, or mixed glycerides of unsaturated fatty acids such as non-drying oils such as castor oil.
[0015]
Next, the water in the mixed liquid of the microcapsule aqueous dispersion and the oil-based ink is vaporized and removed by vacuum distillation, and the individual microcapsule particles are replaced with water-based oils in the form of independent primary particles. However, as a condition for vaporizing and removing the water in the liquid mixture by this vacuum distillation, for example, when the solvent that is compatible with both the vehicle component and the surface layer of the capsule wall material is glycerin (boiling point 290 ° C.) The mixed solution is heated to 30 to 90 ° C. under reduced pressure (about 10 Pa) by vacuuming. However, since the ink is easily separated at a high temperature, 30 to 70 ° C. is preferable. Finally, the water content of the mixed solution is about 5 to 15% by weight, preferably about 8 to 12% by weight.
[0016]
As described above, in the mixed liquid of the microcapsule aqueous dispersion and the oil-based ink, the solvent sharing the hydrophilicity and the hydrophobicity is in a state of having affinity for the surface layer of the capsule wall material with the hydrophilic group. Has a group and affinity with the vehicle component. That is, the microcapsule is replaced by a hydrophilic solvent and a hydrophobic solvent that share affinity for the surface layer of the wall material, and further by affinity with the oil system, whereby the oil-based ink containing the color former microcapsule is prepared. Is.
[0017]
The above steps will be described in detail with specific examples, but the present invention is not limited to the following examples.
In a 300 ml sealed container connected to a vacuum pump, styrene maleic anhydride copolymer was dissolved together with a small amount of sodium hydroxide, and this was added to 194 parts of alkylnaphthalene in 200 parts of an aqueous solution prepared to 5 wt% and pH 4.6. 6 parts of crystal violet lactone are heated and dissolved, and this is emulsified and dispersed to produce an emulsion having an average particle size of 2 μm. 60 parts of melamine-formalin initial polycondensate is added to this emulsion, and the temperature of the system is adjusted to 75. 80 parts of the 50% by weight microcapsule dispersion obtained by stirring at 2 ° C. for 2 hours and 20 parts of glycerin are mixed and sufficiently stirred.
[0018]
Next, with stirring, 20 parts of UV curable oily varnish is added to the mixture and mixed, heated to 40 ° C., and further evacuated to bring the pressure inside the flask to about 10 Pa. While maintaining this state for about 1 to 2 hours while reducing the pressure, the water content is removed and the water content is reduced to about 10% by weight. Then, 30 parts of a printing ink preparation agent is added to the obtained oil-based ink so as to be suitable for the printing machine to be used, and the mixture is sufficiently stirred to prepare the color ink microcapsule-containing oil-based ink of the present invention.
[0019]
The characteristics of the oil-based ink containing the color former microcapsule prepared are as follows: the oil-based ink vehicle maintains the physical properties such as elasticity and strength when the microcapsule is formed in an aqueous system. FIG. 1 shows this state together with an enlarged sectional view of the microcapsule.
[0020]
[Figure 1]
[0021]
Next, a detailed description will be given of a method in which a coating layer made of oil-based ink containing a color former microcapsule is printed and formed on a desired portion of a sheet surface to be copied by a pressure transfer type printing machine.
[0022]
The color former microcapsule-containing oil-based ink in the present invention can be prepared in the same manner as a conventional kneaded ink. In a printing machine, the ink is generally transferred from an ink fountain to a plate by a roller, In such a case, the capsule is transferred and pressure-bonded to the printing body without being broken. Or, when ink is scraped off by a doctor blade in intaglio printing, the capsule material is not broken by specifying the blade material, and it can be handled in the same way as normal printing ink. Ink, screen ink, etc. can be optionally prepared. Therefore, even those containing microcapsules are excellent in printability, and after printing, they are dried on the surface of the printing medium to form a film. It sticks. In addition, it has suitable fluidity and drying properties. For example, fluidity has the ability to transfer ink from the ink fountain to the calling roller and spread on the roller, and to transfer from the plate to the substrate. Furthermore, in terms of drying property, there is no problem in obtaining a sufficiently dried film from the stage where the ink is set in a semi-solid state.
[0023]
Hereinafter, the formation of the coating layer will be described in more detail with reference to FIG.
As schematically shown in FIG. 2, in this example, the prepared color ink microcapsule-containing oil-based ink 1 was copied using a letterpress offset rotary printing press P on two sides of a high-quality paper for foam. At a printing speed of 600 ft / min at a printing speed of 2 g / m ² at a printing speed of 600 ft / min, and partially through a UV dryer D, a coating layer 1 ′ of oil-based ink containing color former microcapsules Is produced. In this embodiment, based on the same operation, by replacing the high-quality paper for foam with the conventional paper for copying, a paper for copying partially having a coating layer of oil-based ink containing color former microcapsules is also prepared. be able to.
[0024]
[Figure 2]
[0025]
As described above, in this embodiment, without using a special apparatus, it is possible to freely create upper and middle sheets of partial copies in which a coloring layer is provided on a predetermined portion of the sheet surface by normal letterpress offset printing, These are subjected to predetermined printing by a printing machine (not shown) and combined with a conventional lower sheet, for example, as shown in FIG. A copy sheet for partial copying can be freely formed, for example, by combining the upper copy sheet 3 and the intermediate copy sheet 4 and the existing lower copy sheet 5 having the coating layer 1 'to form a three-part copy sheet set. Can be created.
[0026]
[Fig. 3]
[0027]
【The invention's effect】
According to the present invention, a coating layer of oil-based ink containing a color former microcapsule on a copy paper can be freely provided at a desired location to be copied by a pressure transfer type printing machine. There is no need for desensitization printing that hinders printing, and partial copy paper can be freely created for all types of printing paper.
Furthermore, even when printed on the sheet surface, the ink does not easily penetrate into the fiber, and there is no hindrance to the transfer of the color former in the capsule to the developer, and the surface and side surfaces of the color development layer are hardened with the ink material. Therefore, the use of a protective agent is unnecessary, and the effect is wide-ranging, such as the color development becomes clearer than before.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a color former microcapsule-containing oil-based ink and an enlarged cross-sectional view of a capsule.
FIG. 2 is a schematic view of a method for producing pressure-sensitive copying paper by a pressure transfer type printing machine according to the present invention.
FIG. 3 is a schematic cross-sectional view of a pressure-sensitive copying form set formed according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Color-former microcapsule containing oil-based ink B ... Oil-based printing ink C ... Color-former microcapsule C1 ... Color-former C2 ... Capsule wall material C3 ... Solvent which is compatible with the vehicle and capsule wall material of oil-based printing ink 1 '... Color development Coating layer 2 of oil-based ink containing agent microcapsule ... Fine paper for foam 3 ... Copy upper paper 4 ... Copying paper 5 ... Copy lower paper 6 ... Developer M ... Cut-off machine line G ... Binding glue

Claims (3)

A method for producing pressure-sensitive copying paper in which a coating layer of oil-based ink containing a color former microcapsule is provided on a predetermined portion of a sheet surface,
In a microcapsule aqueous dispersion obtained by forming microcapsules in an aqueous system, a solvent compatible with both the vehicle of the oil-based ink and the surface layer of the capsule wall material is mixed with the vehicle, and at this time, the boiling point is higher than the boiling point of water. By using a vehicle having water and vaporizing and removing the water, the microcapsules can be dispersed and dispersed in the vehicle without aggregating each other and maintaining the physical properties of the capsule wall material. the color former microcapsules containing oil-based ink comprising, by printing in a predetermined portion of the sheet surface with a printing press of pressure transfer method, a method of creating pressure-sensitive copying paper, which comprises forming the target layer. The method according to claim 1, wherein a relief printing press is used as the printing press. The method according to claim 1 or 2, wherein the water is vaporized and removed by vacuum distillation.

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