JP2005289515A - Envelope paper with transparent window having suitability for ink jet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an envelope paper which has suitability for an ink jet recording on the addressing face of the envelope paper and has a see-through transparent window, without using a different material from the envelope paper and can be bonded using heat-sealing property (melt bonding) without using an adhesive. <P>SOLUTION: In the envelope paper having a basis weight of 100 g/m<SP>2</SP>or lower, in which an ink-receiving layer having suitability for ink jet recording is provided on one surface of a paper layer composed of a synthetic pulp and a natural pulp, the surface for addressing or the like as the outside of the envelope paper is served as the ink-receiving layer, the paper layer contains synthetic pulp and the surface of the envelope is pressurized with a hot stamp (heat press) heated at the melting point of the synthetic pulp or higher to make a part of the envelope transparent and to provide a see-through transparent window, and when the envelope paper is processed, the envelop paper can be bonded using the heat-sealing property (melt bonding) without using the adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to envelope paper, particularly suitable for ink-jet recording on the address side, and a part of the envelope is made transparent with a hot stamp (heat press) without using a film of a different material from the envelope paper, and a transparent window is attached. The present invention relates to an envelope paper that can be bonded using heat sealability (heat fusion) without using glue.

  Conventionally, cellulose-based paper has been mainly used as a material for envelope paper. When making envelopes from cellulosic paper, it is usually done with starch paste or an organic adhesive. However, since an adhesive is used to make an envelope, it naturally requires time to dry the adhesive. There was a limit to speeding up the envelope creation process. In recent years, materials such as synthetic paper, film, or nonwoven fabric made of thermoplastic resin have begun to be used as envelope paper materials, and these synthetic paper, film, or nonwoven fabric are made into bags by a continuous heat-sealing bag making machine. Has been made.

  In recent years, mail-related products such as saving the trouble of writing addresses on envelopes have been known by using envelopes with a transparent film attached to only the address part of mails, so-called envelopes with windows. The film sticking process of the mold becomes complicated, and a film made of a material different from paper, such as a biodegradable film, is also required (Patent Documents 1 and 2).

  As various businesses become more internationalized, the appeal of their business to customers has become increasingly important. There is direct mail as the means. Since direct mail has a large amount of information, so-called confidential postcards are not enough, usually enough information is enclosed in an envelope and sent to a specific or unspecified customer.

  Recently, with the progress of computers, the display of a screen can be displayed in full color, and there is a strong demand for outputting this screen as a hard copy as it is. Actually, all the texts in the office can be said to be printed in black, but recently, the use of a large number of colors and drawings enables accurate and quick communication of document contents, and there is a demand for it. Colorization is progressing in all fields, and in the recording field, colorization is progressing not only in full color by ink jet recording but also in electrophotography.

  However, when full-color inkjet recording is performed on envelope paper, recording is of course possible, but the image is very bad and dull, which is insufficient for the purpose of publicity.

Patent Document 3 includes a portion corresponding to a window of a base paper obtained by blending 60 to 80% of a short fiber made of a wood pulp and a thermoplastic synthetic resin having a melting point of 100 to 180 ° C. with respect to the wood pulp and made by a paper machine. A method for producing an envelope paper with a window is disclosed, in which a transparent or translucent window is provided by heat-pressing on a hot plate at 120 to 180 ° C. However, this patent document 3 does not mention ink recording suitability, and does not mention the ink receiving layer at all.
... JP-A-10-297645 ... JP 2003-128080 ... Japanese Patent Publication No. 52-15686

  The subject of the present invention relates to envelope paper, and in particular, is suitable for inkjet recording on the address side of envelope paper, has a transparent window with internal transparency without using a film of a different material from envelope paper, and does not use glue. It is to provide an envelope paper that can be bonded using heat sealability (heat fusion).

  The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention relates to an envelope paper having a basis weight of 100 g / m 2 or less in which an ink receiving layer suitable for ink jet recording is provided on one side of a base paper layer made of synthetic pulp and natural pulp, and a destination outside the envelope paper. The surface of the ink is used as an ink-receiving layer surface, the base paper layer contains synthetic pulp, and a part of the envelope is pressed by pressurizing the surface of the envelope with a hot stamp (heat press device) heated above the melting point of the synthetic pulp. The present invention relates to an envelope paper characterized in that it can be made transparent, provided with a transparent window with internal transparency, and can be bonded using heat sealability (heat fusion) without using glue during envelope molding.

  In one advantageous embodiment of the invention, the synthetic pulp is a polyolefin-based synthetic pulp.

  In another advantageous embodiment, the melting point of the synthetic pulp is 150 ° C. or less.

  In yet another advantageous embodiment, the base paper contains synthetic pulp and natural pulp in a weight percentage of 10/90 to 80/20.

  By adopting the above-described configuration, the present invention is suitable for inkjet recording on the address side of the envelope paper, and a part of the envelope is hot stamped (hot press) without using a film of a different material from the envelope paper. There is provided an envelope paper which has a transparent window with transparency and has a transparent inside and can be mechanically bonded in a short time using heat sealability (heat fusion) without using glue.

  Next, the envelope paper of the present invention will be specifically described.

The present invention provides an envelope paper in which an ink receiving layer is provided on a base paper, the envelope paper containing synthetic pulp in the base paper and having a transparent window with internal transparency. More preferably, it is an envelope paper using a base paper obtained by mixing polyolefin synthetic pulp with natural fibers.
(Synthetic pulp)
Examples of the synthetic pulp include ethylene and other olefin homopolymers such as polyethylene and polypropylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, and ethylene-4-methylpentene-1 copolymer. Synthetic pulp mainly composed of synthetic resin such as polyolefin resin such as copolymer with α-olefin, polystyrene, polymethyl methacrylate, polyacrylonitrile, vinyl chloride resin, vinylidene chloride resin, nylon, polyester, polyfluoroethylene Among them, synthetic pulp of polyolefin resin is inexpensive and is preferably used. The synthetic pulp is selected to be transparent with a hot stamp heated to the melting point or higher in order to provide a transparent window on the envelope paper. However, when considering heat sealing under the user, it is advantageous that the melting point of the synthetic pulp is 150 ° C. or less.

  Examples of polyolefin resins include homopolymers of olefins such as polyethylene, polypropylene and 4-methylpentene-1, ethylene-propylene copolymers, ethylene-butene-1 copolymers, and ethylene-4-methylpentene-1 copolymers. Examples thereof include copolymers of ethylene and other α-olefins such as polyethylene and polypropylene, which are particularly suitable because they are particularly inexpensive and have the property of achieving the object of the present invention. .

  Moreover, although the average fiber length of a synthetic pulp is not limited, when workability | operativity and workability are considered, it is preferable to exist in the range of 0.1-5 mm especially.

  Further, the freeness of the synthetic pulp is preferably about 0.1 to 20 seconds / g from the viewpoints of the obtained sheet strength and papermaking property. That is, when the freeness is less than 0.1 seconds / g or more than 20 seconds / g, the papermaking property and the sheet strength are insufficient.

  When pulping the synthetic resin, various additives can be added within a range not impairing the object of the present invention. Examples of additives include flame retardants, antioxidants, antistatic agents, weathering stabilizers, pigments and the like.

  A known method can be applied to produce synthetic pulp from this synthetic resin, and the production method is described in detail in Encyclopedia of Chemical Technology 3rd ed, Vol. 19, P420-425. For example, there are a method of beating after melt-spun fibers are cut short, and a method of beating after melting or emulsion flushing.

  As a method for producing a synthetic pulp according to the present invention, a method of flash spinning a solution or emulsion of a resin composition is suitable. Among them, an emulsion flash method using polyvinyl alcohol (PVA) as a hydrophilizing agent is particularly preferable, and a pulp having a good fiber shape suitable for paper production can be obtained. As for the addition amount of PVA, 0.01 to 10 weight% is preferable with respect to the synthetic pulp whole quantity containing PVA. When the added amount of PVA is less than 0.01% by weight, the binding and hydrophilicity of the pulp are insufficient, and when it exceeds 10% by weight, the hydrophilicity becomes too strong, which is inconvenient as envelope paper.

(Natural pulp)
As the natural pulp used in the present invention, wood bleached chemical pulp represented by L-BKP (hardwood bleached kraft pulp) and N-BKP (conifer bleached kraft pulp) is mainly used. If necessary, mechanical pulp such as GP (crushed wood pulp), TMP (thermomechanical pulp), BCTMP (chemical thermomechanical pulp), non-wood pulp such as kenaf, cotton linter, hemp, etc. I can do it.

(Base paper)
Although the blending ratio of synthetic pulp and natural pulp varies depending on the type of natural pulp used, the blending ratio is usually 10/90 to 80/20 wt%, preferably 20/80 to 70/30 wt%, more preferably 30 / 70-60 / 40 weight% is good. If the blending ratio of the synthetic pulp is less than 10% by weight, the transparency effect by hot stamping (hot press) is insufficient, and if it exceeds 80% by weight, the strength is insufficient, and the paper breaks easily in the coating process. It is also economically disadvantageous. The appropriate blending ratio of synthetic pulp is determined while observing the transparency effect by hot stamping (hot pressing).

(Internal medicine)
Usually, paper strength agents, fillers, bands, yield improvers, dyes, fluorescent dyes and the like are appropriately used in the paper stock. The following can be exemplified as these preferable ones, but the present invention is not limited thereto.

  As the paper strength agent, cationic starch, polyacrylamide, or the like is used. As the filler, calcium carbonate, talc, clay, synthetic zeolite, calcium silicate, titanium and the like are used. As the yield improver, colloidal silica, polyacrylamide, polyethyleneimine, or the like is used. Dyes and fluorescent dyes are added to adjust the hue of paper, and direct dyes, basic dyes, acid dyes, and the like are used. As the internal sizing agent, when calcium carbonate is used for the filler, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), neutral rosin, etc. are used, and a filler other than calcium carbonate is used. In some cases, fortified rosin and saponified rosin are mainly used.

(Manufacturing method of base paper)
The method for producing the base paper is not particularly limited, and the base paper can be produced in a single layer or in combination using a known long web paper machine, round net paper machine, twin wire paper machine, on-top wire paper machine, etc. . Using a size press, a film transfer roll coater or a metering size press on the base paper, appropriately selecting starch, polyvinyl alcohol, polyacrylamide, sizing agent, fixing agent, water-resistant agent, crosslinking agent, etc. A size press or gate roll layer may be provided. The basis weight of the base paper is not particularly limited but ranges usually about 50 to 100 g / m ^2.

(Ink receiving layer)
The ink receiving layer provided on the base paper is mainly composed of an inorganic pigment and a water-soluble polymer binder. However, in order to further enhance the transparency effect, the ink receiving layer may be free of an inorganic pigment. As the inorganic pigment in the present invention, porous synthetic amorphous silica, porous synthetic amorphous alumina and the like are preferable in order to obtain the necessary pore volume and ink absorbability. If necessary, for example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, titanium dioxide, calcium sulfate, barium sulfate, diatomaceous earth, colloidal silica, magnesium carbonate, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum hydroxide, Satin white, lithium silicate, magnesium oxide, mica, natural zeolite, synthetic zeolite, pseudoboehmite, hydroxyapatite, intercalation compound, and the like can be used.

  Examples of the water-soluble polymer binder in the recording layer used in the present invention include the following. For example, polyvinyl alcohol, silyl modified polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl pyridine, polyethylene oxide, polypropylene oxide, starch, modified starch, soy protein, sodium alginate, polystyrene sulfonate soda, casein, Gelatin, terpene and the like. Among these, the use of polyvinyl alcohol is more preferable from the viewpoint of binder strength, affinity with pigments, and viscosity control during preparation of the coating liquid. Here, the saponification degree and the polymerization degree of polyvinyl alcohol are not particularly limited.

  As adhesives other than these water-soluble polymers, vinyl acetate, ethylene vinyl acetate copolymer, acrylic polymer, urea resin, melamine resin, polyurethane resin, styrene-butadiene copolymer, modified styrene-butadiene copolymer, acrylonitrile -Butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic ester-methacrylic ester copolymer, vinyl acetate-maleic ester copolymer, acrylic-vinyl acetate copolymer, starch-acrylonitrile graft polymer Can be used in combination with the water-soluble polymer binder. These adhesives are usually used in an amount of about 10 to 100 parts by weight with respect to 100 parts by weight of the pigment, but the ratio is not particularly limited as long as it is an amount sufficient for binding of the pigment.

  The ink receiving layer can be formed on the base paper by applying a coating liquid mainly composed of an inorganic pigment and a water-soluble polymer binder.

  The coating liquid used for the ink receiving layer includes a dispersant, an antifoaming agent, a pH adjusting agent, a lubricant, a wetting agent, a release agent, a water retention agent, a thickening agent, a surfactant, a preservative, Softener, wax, antistatic agent, antistatic agent, sizing agent, waterproofing agent, dye fixing agent, plasticizer, fluorescent whitening agent, coloring pigment, coloring dye, flow improver, printability improver, reducing agent, Ultraviolet absorbers, antioxidants, fragrances, deodorizers and the like can be appropriately selected and added. Further, for example, the place and method of adding these to the silica slurry or the binder are not limited.

  The ink receiving layer is prepared by applying a coating liquid prepared in this manner to a general coating method, for example, blade coater, roll coater, reverse roll coater, air knife coater, die coater, bar coater, gravure coater, curtain coater, The ink jet recording paper of the present invention can be obtained by applying a single layer or multiple layers on a base paper with an off-machine coater or an on-machine coater by a coating method such as a Chambrex coater, a lip coater, or a rod coater. An air knife coater is preferred because of the liquidity of the coating solution.

  The coating amount of the ink receiving layer of the present invention is preferably 5 to 15 g / m 2 as a dry weight per side from the viewpoints of coating amount necessary for ink jet printing and uniformity and economical efficiency. When the coating amount is less than 5 g / m 2, in ink jet printing, ink overflow, bleeding, uneven coloring, etc. occur due to insufficient ink absorption capacity. When the coating amount is more than 15 g / m 2, the strength of the coating layer is lowered, and the coating layer falls off. Moreover, the effect of transparency of the envelope is reduced by hot stamping (heat pressing).

  Examples of the drying method after coating include hot air drying, infrared drying and drum drying, but are not particularly limited in the present invention.

  Further, after applying the ink receiving layer, a smoothing process may be performed using a calendar device such as a super calendar, a machine calendar, or a soft calendar, if necessary. Usually, even if these finishing processes are not performed, the envelope paper of the present invention has sufficient smoothness.

(Function)
The envelope paper of the present invention comprises a base paper layer in which an ink receiving layer having ink jet recording suitability on the address side and a polyolefin synthetic pulp are blended. The transparent window is formed using the fact that the polyolefin synthetic pulp melts and the base paper becomes transparent by pressurizing the surface of the envelope paper with a hot stamp (heat press) heated to a temperature higher than the melting point. Yes. The envelope paper is preprinted with ink-jet printing on the address and the like, and an envelope is prepared by thermally bonding a base paper blended with polyolefin synthetic pulp with a heat-sealing bag making machine.

Example:
EXAMPLES Hereinafter, although this invention is explained in full detail based on the illustrated Example, this invention is not limited to these Examples.
In the examples, “parts” and “%” represent “parts by weight” and “% by weight” unless otherwise specified.

<Create base paper>
Polycation synthetic pulp 40 parts (trade name: SWP E620, manufactured by Mitsui Chemicals, fiber length 1.2 mm, freeness 6 sec / g) and Canadian standard freeness (CSF) 400 cc of LBKP 80 parts cation is added to the pulp slurry. Starch 0.8%, talc 5%, internal sizing agent (Colopearl E-5H, manufactured by Seiko PMC Co., Ltd.) 0.3%, sulfuric acid band 0.3%, and paper making with a long net paper machine, polyvinyl alcohol ( Product name: PVA-117 (manufactured by Kuraray Co., Ltd.) 2 parts, surface sizing agent (trade name: SS373, manufactured by Seiko PMC Co., Ltd.) 0.3 part, water size 97.7 parts of size press liquid 2 g in solid content / m2 (two-sided) are deposited, and paper making envelopes for base paper having a basis weight of 70 g / m ^2.

<Preparation of coating liquid for ink receiving layer>
To 100 parts of synthetic amorphous silica (trade name: Silojet P409, manufactured by Grace Devison), 0.2 part of acetic acid was added as a pH adjuster, and a 20% pigment slurry was prepared with a Cowles disperser. To this pigment slurry, 25 parts of polyvinyl alcohol (trade name: PVA-117, manufactured by Kuraray Co., Ltd.), 40 parts of ethylene vinyl acetate copolymer (trade name; Sumikaflex 450, manufactured by Sumitomo Chemical Co., Ltd.) and 10 parts of dye fixing agent ( Product name: SR1001, manufactured by Sumitomo Chemical Co., Ltd.), 0.5 part of anionic fluorescent whitening agent (product name: Hackol PHNL, manufactured by Showa Chemical Industry Co., Ltd.) is added and stirred, water is further added, and the solid content concentration 18% of coating solution was obtained.

<Formation of ink receiving layer>
The obtained coating solution was applied to one side of the above base paper with an air knife coater so that the dry coating amount was 10 g / m 2, and dried with hot air using an air dryer to obtain the envelope paper of the present invention.
<Formation of transparent windows>
After cutting the envelope paper into an envelope size, a hot stamp (heat press) heated to 150 ° C. was applied to the surface of the envelope paper to effect transparency of the base paper to obtain an envelope paper with a transparent window.
<Description of manufactured envelope>
FIG. 1 is a developed view of the front side of an envelope manufactured according to the present invention, FIG. 2 is a plan view of the addressed surface of the envelope after processing, and FIG. 3 is a plan view of the back surface of the envelope after processing.

FIG. 1 is a front plan view showing an example of envelope paper of the present invention when opened. FIG. 2 is a front plan view of an envelope showing an example of the present invention. FIG. 3 is a plan view of the back side of an envelope showing an example of the present invention.

Claims (4)

In an envelope paper having a basis weight of 100 g / m ² or less, in which an ink receiving layer suitable for inkjet recording is provided on one side of a base paper layer made of synthetic pulp and natural pulp, the ink receiving surface such as a destination on the outside of the envelope paper The surface of the envelope is made transparent by pressurizing the surface of the envelope with a hot stamp (heat press) heated to a melting point or higher of the synthetic pulp. Envelope paper, which has an adhesive transparent window and can be bonded using heat sealability (heat fusion) without using glue during envelope molding. The envelope paper according to claim 1, wherein the synthetic pulp is a polyolefin-based synthetic pulp. The envelope paper according to claim 1, wherein the synthetic pulp has a melting point of 150 ° C. or less. The envelope paper according to any one of claims 1 to 3, wherein the base paper contains synthetic pulp and natural pulp in a weight percentage of 10/90 to 80/20.

Images