JP2007007979A - Material to be recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the adhesion between an ink and a porous layer after the formation of an image onto a material to be recorded in an inkjet recording system and to improve printing properties/designability by providing a transparent portion in the material to be recorded so as to establish a constitution contrasting the portion with an opaque portion in a thermosensitive recording system. <P>SOLUTION: In the material to be recorded having the porous layer formed by a wet freezing method on at least one side of a base material, a resinous portion is melted by heating the porous layer up to at least the grass transition point of a resin included in the porous layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording material having a porous layer formed by a wet coagulation method.

1. In the case of using as an ink jet recording medium As a printing method for a recording material, an ink jet recording method has attracted attention. In this method, printing is performed by spraying fine particles of ink onto a recording material, which is widely used for household printers. In recent years, due to its characteristics, this ink jet recording system is not limited to printing characters or the like on commonly used photographic paper, but is widely used in the industrial marking field such as a printing system for cardboard and paper packs. It is becoming.

  In the past, ink jet recording systems have had the problem of poor fixing of ink to a recording material. In order to deal with these problems, a conventional general method has been proposed in which an ink receiving layer is formed on a recording material and a cationic substance is contained in the layer. This is to solve the above problem by adding a specific function to the recording material.

  On the other hand, there is one that attempts to improve the fixing by processing in the printing process. For example, Patent Document 1 proposes a method in which a porous polymer resin layer is formed on a substrate, an image is formed using an ink jet recording method, and the porous layer is heated after the image is formed. . The heat treatment is aimed at densifying the porous layer and fixing the image.

  However, in Patent Document 1 described above, the particle size distribution of the ink to be applied and the pore diameter of the porous portion of the recording layer must be adjusted to have a certain relationship, and an appropriate pore diameter is formed. It was difficult to do.

2. When used as a thermal recording medium A printing method based on a thermal recording method (including a case where a similar recording method can be used in a thermal transfer recording method) is generally well known as in the ink jet recording method. In this method, a portion corresponding to character information and image information is heated by a thermal head, and the surface layer of the recording material is colored.

  As this heat-sensitive recording medium, Patent Document 2 has a concealing layer composed of a porous film whitened when a resin varnish comprising a resin component, a parent solvent and a poor solvent for the resin component is dried, and the concealing layer is heated. Then, what is made transparent is proposed. This is characterized in that when the masking layer is heated, the resin component in the masking layer is melted and re-solidified to be transparent.

In Patent Document 2, a porous layer is used as a concealing layer, and a dry method using two kinds of solvents (a parent solvent and a poor solvent) is used as a method for making the layer porous. .
However, in order to adjust this concealing layer to an appropriate porosity, it is difficult to achieve an appropriate porosity by this dry method.

JP 11-192775 A Japanese Patent Laid-Open No. 7-270551

  In view of the above problems, the present invention provides: 1. improving the ink adhesion of a recording material on which an image is formed by an inkjet recording method; The object is to increase the printability, designability, and diversification of image display of the recording material for thermal recording.

As a result of intensive studies to achieve the above object, the present inventors have achieved that the recording material provided with the porous layer by the wet coagulation method exceeds the glass transition point of the resin contained in the porous layer. It has been found that the object can be achieved by heating and melting the resin portion of the porous layer.
The present invention has been completed based on such findings.

That is, the present invention
(1) In a recording material having a porous layer formed by a wet coagulation method on at least one side of a base material, the porous layer is heated to a temperature higher than the glass transition point of the resin contained in the porous material. A recording material characterized by melting the resin portion,
(2) The recording material according to (1), wherein an ink is fixed by heating the porous layer after an image is formed on the porous layer by an ink jet recording method, and
(3) When the opacity before heating of the porous layer is (A) and the opacity after heating is (B) by heating the porous layer, (A) to (B ) Minus 3% or more, the recording material according to (1),
Is to provide.

  The recording material of the present invention improves the adhesion between the ink after image formation and the recording layer when using the inkjet recording method, and improves the transparency of the heated part when using the thermal recording method. By doing so, it is possible to make a difference in opacity from the unheated portion, to enable character recognition, and to obtain an exceptional effect that it is possible to provide a novel design with a good design.

The present invention is described in detail below.
The recording material of the present invention is a recording material in which a porous layer (also referred to as a recording layer) is provided on at least one surface of a substrate, and the porous layer is coated with a coating liquid containing a resin and a solvent. It is characterized by being formed by wet coagulation after the work.
The substrate used in the present invention is not particularly limited as long as it can be coated with the coating liquid according to the present invention, and is not limited to a sheet-like material, but includes a molded body (a sheet-like material molded). ) Etc. can be used. For example, a plastic film, a metal film, a fiber cloth, etc. can be mentioned. Of these, a plastic film is preferably used.
Examples of the plastic film mainly include, for example, inexpensive industrial polyethylene terephthalate (PET) films and polypropylene (PP) olefin films.
Moreover, there is no restriction | limiting in particular about the thickness of a base material, However, Usually, it is about 10-1000 micrometers, Preferably it is 15-500 micrometers.

  A biodegradable plastic can also be used as the substrate. Biodegradable plastics are characterized by low combustion energy and no generation of toxic gases, and are environmentally friendly plastics that are decomposed and metabolized by microorganisms over time, and eventually return to nature as water and carbon dioxide. . Typical examples of the biodegradable plastic include polylactic acid, a mixture of starch and modified polyvinyl alcohol, polybutylene succinate / adipate copolymer, polycaprolactone, polyhydroxybutyrate / valerate copolymer and the like. In particular, polylactic acid is preferable from the viewpoint of the speed of decomposition and strength. In addition, in order to improve the strength of the base film, other plastics can be added to and mixed with the biodegradable plastic as long as the biodegradability is not impaired.

  The base material may be a single layer structure or a multilayer structure. Examples of a method for forming a multilayer structure include a method of bonding layers through an adhesive, a plurality of resin compositions extruded from a plurality of extruders. A film formed by any known method such as a so-called co-extrusion method for forming a film and a so-called extrusion laminating method in which a film is directly laminated onto a film while being extruded from an extruder and laminated.

Furthermore, for the purpose of improving adhesion and wettability with a porous layer or the like, a surface treatment can be applied to one or both surfaces of the substrate by an oxidation method, an unevenness method, or the like as desired.
Examples of the oxidation method include corona discharge treatment and hot air treatment, and examples of the unevenness method include a sand blast method and a solvent treatment method. These surface treatment methods are appropriately selected depending on the type of the substrate, but in general, corona discharge treatment is preferably used in terms of effects and operability. Moreover, an easily bonding process can also be given to the base-material surface.

  Next, the porous layer is provided by applying a coating liquid containing a resin on at least one surface of the base material, and the coating method uses a wet coagulation method. Here, the wet coagulation method refers to a solution obtained by dissolving a resin in an organic solvent as a coating solution, and after the coating solution is applied on a substrate, it has compatibility with the solvent but is incompatible with the resin. It means that the organic solvent is replaced by passing through a solvent, which is gelled, solidified, and dried to form a porous layer. The formed coating layer is formed in a porous structure, and its mechanism is that when the organic solvent is solidified through a liquid that is a non-solvent for the resin, the escape route becomes a cavity when the organic solvent escapes into the liquid. This is because the cavity becomes a hole. The number of times this solution is passed is usually 2 times, but the temperature of the solution is 15 to 40 ° C., preferably 20 to 30 ° C., preferably 60 to 100 ° C. for the second time, Preferably they are 80 degreeC or more and 95 degrees C or less. By adjusting the temperature in this way, the number and size of the holes can be adjusted, and by increasing the temperature, the holes can be enlarged. The pore diameter varies depending on various inks. For example, when pigment ink is used, the pore diameter is preferably adjusted to about 0.1 to 10 μm. By adjusting to this range, the ink fixing after heating the recording layer becomes better.

  Examples of the resin used in the coating liquid of the present invention include resins made of acrylic, styrene, urethane, vinyl acetate, vinyl chloride or copolymers thereof. For example, when a specially modified urethane resin is used, the isocyanate group (NCO) remaining when gelling by wet coagulation reacts with water to generate a small amount of carbon dioxide gas, thereby forming a finer porous layer. Can be formed.

  The organic solvent used in the coating solution may be any solvent that dissolves the resin that forms the porous layer. Examples thereof include dimethylformamide (DMF), N-methylpyrrolidone, dimethyl sulfoxide, dimethylacetamide, tetrahydrofuran, γ-butyrolactone, and the like. Among these, DMF is preferably used from the viewpoint of processability, simplicity, and low cost of the porous membrane.

  Next, examples of the liquid that does not dissolve the resin in the wet coagulation method include water, ethanol, methanol, etc. Among them, water is preferably used. This is because water is very easy to handle.

  Moreover, a filler can also be added with respect to the said coating liquid as needed. For example, silica, clay, talc, diatomaceous earth, calcium carbonate, calcined kaolin, titanium oxide, zinc oxide, satin white and the like can be used. Of these, calcium carbonate and titanium oxide are preferably used. By using this, it is inexpensive and printability and whiteness are improved.

  Furthermore, in the porous layer, an antifoaming agent, an antistatic agent, an ultraviolet absorber, a fluorescent whitening agent, a preservative, a pigment dispersant, a thickening agent, as necessary, within a range where the object of the present invention is not impaired. Various additives such as can be contained.

The recording material of the present invention has a porous layer on at least one surface of the substrate, and the porous layer may be provided on one surface of the substrate or on both surfaces for the purpose of preventing curling. Also good. Moreover, in order to improve adhesiveness with a base material, you may provide an anchor coat layer.
Furthermore, a layer other than the porous layer may be provided. For example, for the purpose of improving the concealing property, a layer having an appropriate opacity may be provided, or an ultraviolet absorbing layer may be provided. Further, a layer for preventing curling may be provided.

  Such a porous layer of the recording material of the present invention and other optional layers are formed by applying a coating liquid in which necessary components are dispersed or dissolved in a solvent and drying the coating liquid. For coating, various conventionally known methods such as reverse roll coating, air knife coating, gravure coating, blade coating, and lip die coating can be used.

  The thickness of the recording layer (after drying) is preferably in the range of 0.1 to 150 μm, more preferably in the range of 2 to 50 μm. If the thickness is less than this range, the ink absorption capacity is insufficient and bleeding tends to occur. Conversely, if the thickness is greater than this range, the recording layer strength may be reduced.

In the present invention, in order to fix the ink, the adhesion of the ink can be improved by heating the recording layer printed by the ink jet recording method. In this case, the heating conditions need to be set as appropriate depending on the type of the thermoplastic resin in the coating layer, but at least the glass transition point needs to be heated. By applying heat above the glass transition point, the resin in the recording layer is melted, the pore diameter is enlarged, and the penetration of the ink into the porous layer is promoted. In addition, when using several resin, a glass transition point will be calculated according to the addition amount.
The heating method is not particularly limited, and various general methods such as a hot air drying furnace, an infrared drying furnace, and a hot plate can be adopted.

  In the present invention, the ink used for the ink jet recording system is not particularly limited as long as it is an ink that can be sprayed on a recording material by the ink jet recording system, such as a dye ink or a pigment ink, and various inks can be used. It can be used. In particular, when the pigment ink is used, the fixing of the ink can be improved.

  As described above, the ink is printed on the recording material on which the porous layer (recording layer) is formed by using the wet coagulation method, and the printed ink is applied to the recording material by heating the recording layer after printing. It is possible to fix the ink. For example, a heating process is provided after the marking process using the ink jet recording method, whereby further ink adhesion can be achieved.

Further, when the recording material is heated by the thermal recording method, the transparency of the portion to which the heat is applied can be improved. This is also because the resin in the porous layer melts and the pores are crushed.
In the present invention, when the opacity before heating of the recording material is (A) and the opacity after heating is (B), the difference (AB) is 3% or more, more preferably Adjust to 10% or more. By doing in this way, the difference in opacity is conspicuous, and it can be suitably used for a poster or the like. In order to adjust to this range, it is necessary to heat above the glass transition point of the resin used, and the transparency can be further improved by not adding a filler.
The opacity referred to here is a numerical value measured based on JIS P8138.
The thermal recording printer used in the present invention is not particularly limited, and a commonly used printer can be used as appropriate.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

1. When used as an inkjet recording medium (Example 1)
A coating liquid having the following composition-1 was applied to one side of a 100 μm thick polyester film (ER PT0007, manufactured by Galware) and dried to form a recording layer having a coating thickness of 20 μm. A color recording image was formed on the recording layer using the following ink jet printer.
(1) Tektronix PHASER 850 manufactured by Fuji Xerox Co., Ltd. (Ink used: four-color pigment-based liquid inks of yellow, magenta, cyan, and black)
(2) Epson's Calario PM-800 (ink used: yellow, magenta, cyan, black four-color dye-based liquid ink)
After forming a color recording image, hot air drying was performed at 120 ° C. for 1 minute, and the performance was evaluated.
The evaluation results are shown in Table 1.
Composition-1
Vinyl chloride-vinyl acetate copolymer (Solvine C, manufactured by Nissin Chemical Industry Co., Ltd., glass transition point 70 ° C.) 13.2 parts by mass Polyacrylate resin (Veslon W241 B2 × 51, manufactured by Toho Textile Co., Ltd., glass transition point 60 ° C. ) 6.2 parts by mass Polyvinyl butyral resin (ESREC BMS, manufactured by Sekisui Chemical Co., Ltd., glass transition point 92 ° C.) 2.9 parts by mass DMF 77.7 parts by mass The glass transition point of these mixed resins was 70 ° C. It was.

(Example 2)
The performance was evaluated in the same manner as in Example 1 except that the following composition-2 was used instead of composition-1 as the composition of the coating liquid to be used.
The evaluation results are shown in Table 1.
Composition-2
Acrylonitrile-styrene copolymer resin (Litac A, manufactured by Nippon A & L Co., Ltd., glass transition point, 108 ° C.) 16.7 parts by mass DMF 53.0 parts by mass Di2-ethylhexyl adipate (DOA, manufactured by Taoka Chemical Co., Ltd.) 2.5 Part by weight Light calcium carbonate (light calcium carbonate, manufactured by Maruo Calcium Co., Ltd., average particle size 2 μm) 24.5 parts by mass Titanium dioxide (Taipeke R-820, manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.3 μm) 3.1 parts by mass

(Comparative Example 1)
The performance was evaluated in the same manner as in Example 1 except that the temperature of hot air drying was 60 ° C.
The evaluation results are shown in Table 1.

(Comparative Example 2)
The performance was evaluated in the same manner as in Example 2 except that the temperature of hot air drying was 60 ° C.
The evaluation results are shown in Table 1.

The performance of the recording material was evaluated according to the following method.
(1) Printability by inkjet recording method The recorded part of the printed matter immediately after printing with Fuji Xerox Tektronix PHASER 850 and Epson's Calario PM-800 was visually observed, and the color reproducibility was evaluated as follows.
○: A clear image is formed.
Δ: Slightly poor ink absorbability and poor image quality.
X: The outflow of ink is recognized and the image is blurred.
(2) Ink Adhesion by Inkjet Recording Method The ink adhesion is evaluated by a cross-cut tape method (based on JIS K-5400). Cuts reaching the substrate surface through the recording layer after drying with hot air were made in a grid pattern, and a cellophane tape piece (Nichiban, No. 405, width 18 mm) was pasted on the grid pattern. After rubbing strongly with the thumb five times, the cellophane tape was suddenly pulled away in the direction of 45 degrees and evaluated from the area of the defect portion of the recording layer of the total square area attached to the cellophane tape side.
○: No missing part is seen.
(Triangle | delta): The area of a defect | deletion part is 50% or less.
X: The area of a defect | deletion part exceeds 50%.

2. When used as a thermal recording medium (Example 3)
A coating liquid having the above composition-1 was applied to one side of a 100 μm-thick polyester film (ER PT0007, manufactured by Galware Co., Ltd.) and dried to form a recording layer having a coating thickness of 20 μm. For the recording layer, a bar code printer (B-474-TS15) manufactured by TOSHIBA TEC was used to print an image in the thermal mode, and the performance was evaluated.
The evaluation results are shown in Table 2.

Example 4
The performance was evaluated in the same manner as in Example 3 except that the composition-2 was used instead of the composition-1 as the composition of the coating liquid to be used.
The evaluation results are shown in Table 2.

(Example 5)
A coating liquid having the above composition-1 was applied to one side of a 100 μm-thick polyester film (ER PT0007, manufactured by Galware Co., Ltd.) and dried to form a recording layer having a coating thickness of 20 μm. The recording layer was heated at 120 ° C. for 1 minute to evaluate its performance.
The evaluation results are shown in Table 2.

(Example 6)
A coating liquid having the following composition-3 was applied to one side of a 100 μm thick polyester film (ER PT0007, manufactured by Galware) and dried to form a recording layer having a coating thickness of 3 μm. The recording layer was heated at 120 ° C. for 1 minute to evaluate its performance.
The evaluation results are shown in Table 2.
Composition-3
Saturated copolymer polyester resin (Byron 200, manufactured by Toyobo Co., Ltd., glass transition point 67 ° C.) 32 parts by mass DMF 68 parts by mass

(Comparative Example 3)
The performance was evaluated in the same manner as in Example 5 except that the heating condition was 60 ° C. for 1 minute.
The evaluation results are shown in Table 2.

(Comparative Example 4)
As a composition of the coating liquid to be used, the performance was evaluated in the same manner as in Example 5 except that the above composition-2 was used instead of the composition-1, and the heating condition was changed to 60 ° C. for one minute. .
The evaluation results are shown in Table 2.

(1) Transparency by heating The opacity of the recording layer (A) before heating and the recording layer (B) after heating was measured, and the transparency was evaluated. As an opacity meter, PF-10 manufactured by Nippon Denshoku Industries Co., Ltd. was used.
◎: AB is 30% or more ○: AB is 10% or more and less than 30% △: AB is 3% or more and less than 10% ×: AB is less than 3%

  The recording material of the present invention includes identification card, driver's license, commuter pass, cash card, ID card, product display label (barcode), advertising label (sticker), general-purpose label, electric paper, molding process It is used for general commercial printed matter such as articles, posters, calendars, magazines, etc., or printed matter for packaging such as packaging sheets and decorative boxes, and is particularly suitable for printing with various printers such as an ink jet recording method or a thermal recording method.

Claims (3)

  In a recording material having a porous layer formed by wet coagulation on at least one side of a substrate, the porous layer is heated to a temperature higher than the glass transition point of the resin contained in the porous material. A recording material characterized by melting a part.   The recording material according to claim 1, wherein after the image is formed on the porous layer by an ink jet recording method, the porous layer is heated to fix the ink.   By heating the porous layer, when the opacity before heating the porous layer is (A) and the opacity after heating is (B), subtract (B) from (A). The recorded material according to claim 1, wherein the difference is 3% or more.