JPH038898A - Partially transparent paper - Google Patents

Abstract

PURPOSE:To obtain the title paper capable of clearly, simply forming transparent parts such as marks and/or characters on a base paper by impregnating a base paper with an ionizing radiation-curable resin followed by ionizing irradiation to cure the resin. CONSTITUTION:At least part of a base paper (e.g. one of a variety of base papers 20-300g/m<2> in areal weight) is impregnated with an ionizing radiation- curable resin [e.g. polyalkylene glycol poly(meth)acrylate] followed by ionizing irradiation (pref. using electron beams or ultraviolet rays) to cure the resin, thus obtaining the objective transparent paper. In case ultraviolet rays are to be used, it is preferable that said resin is incorporated with a photo-initiator such as benzoin.

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to partially transparent paper, and in particular, partially transparent paper that allows transparent parts such as marks, letters, and patterns to be clearly and simply formed on a base paper. Regarding chemical paper. It is something.

"Conventional technology" Conventionally, when producing partially transparent paper, a laid/dandy roll or a watermark/dandy roll is used in the wire part at the papermaking stage, and the protrusions formed on the dandy roll surface are applied to the wet paper. Marks, letters, and designs are applied by pressing hard and making the area thinner.

However, when changing the design, etc., the work of replacing the fine brass plate in the shape of predetermined characters or designs pasted on the wire mesh overlying the cylindrical frame is a complicated task. In addition, since the paper web of the wire part stretches considerably while running through the paper machine, the circumferential spacing of the designs on the surface of the dandy roll must be shorter than that of dry paper, and the width of the dandy roll This method has the disadvantage that the distance in the direction needs to be slightly larger than the required distance for drying paper in consideration of the shrinkage of the paper width, which requires precise work. Furthermore, paper machines typically produce wide widths and high speeds, making them unsuitable for producing a wide variety of products and small lots to meet the diverse needs of the market.

Another possibility is to infiltrate resin or the like in a pattern, but the current situation is that bleeding occurs and a clear pattern cannot be obtained.

``Problems to be Solved by the Invention'' The present invention provides a partially transparent paper in which patterns such as marks, characters, designs, etc. are clearly made transparent on a base paper.

"Means for Solving the Problem" As a result of intensive research into materials for forming patterns on base paper, the present inventors discovered that by using a special resin that hardens when irradiated with ionizing radiation, the impregnated portion of the resin They found that it became clearly transparent. That is, the present invention
This partially transparent paper is made by impregnating at least a portion of a base paper with an ionizing radiation-curable resin and curing the resin by irradiating the base paper with ionizing radiation.

"Function" The present invention is a paper on which marks, letters, designs, etc. are transparently expressed.

The base paper used is not particularly limited;
General high-quality paper with a basis weight of about 300 g/rtf,
Various base papers can be used, such as medium-quality paper, low-grade paper, and synthetic valve-containing paper. In addition, coated paper with a pigment coating layer on one or both sides of the base paper, art paper, various coated papers such as cast coated paper, and heat-sensitive recording layers or pressure-sensitive recording layers on one or both sides of the base paper or coated paper. It is also possible to use various types of recording paper provided with a recording layer such as an electrostatic recording layer or an electrostatic recording layer.

These base papers are printed and impregnated with an ionizing radiation-curable resin to provide patterns, etc. At this time, printing and impregnation can be performed from one side of the base paper, or in some cases from both sides. In addition, for the base paper provided with a coating layer or recording layer, printing or impregnation may be performed from above the coating layer or recording layer, or printing or impregnation may be performed from the side on which the coating layer or recording layer is not provided. Methods are possible and are selected appropriately.

The ionizing radiation-curable resin used in the present invention is not particularly limited as long as it is cured by ionizing radiation, and examples thereof include the following prepolymers (oligomers), monomers, and mixtures thereof. .

(a) Prepolymers include (1) poly(meth)acrylates of aliphatic, alicyclic, araliphatic, aromatic di- to hexavalent polyhydric alcohols and polyalkylene glycol; (2) aliphatic; Polyhydric alcohol poly(
meth)acrylate; (3L HoIJ (meth)acryloyloxyalkylate ester; (4), polyester poly(meth)acrylate; (5
), Epoxy poly(meth)acrylate; (6), Polyurethane (meth)acrylate; (7), Polyamide poly(meth)acrylate; (8), Polysiloxane poly(meth)acrylate; (9), Side chain and Prepolymers such as vinyl or diene low polymers having (meth)acryloyloxy groups at the terminals; GO), oligoester (meth)acrylate modified products described in (1) to (9) above;

(b) Monomers include (1) carboxyl group-containing monomers represented by ethylenically unsaturated mono- or polycarboxylic acids, and carboxylic acid group-containing monomers such as their alkali metal salts, ammonium salts, and amine salts. (2), an amide group-containing monomer represented by ethylenically unsaturated (meth)alkylamides or alkyl-substituted (meth)acrylamides, and vinyllactams such as N-vinylpyrrolidone; (3), aliphatic or sulfonic acid group-containing monomers represented by aromatic vinyl sulfonic acids and their alkali metal salts, ammonium salts, amine salts; (4), ethylenically unsaturated ethers, etc. Representative hydroxyl group-containing monomer; (5), dimethylaminoethyl (meth)acrylate-
Amino group-containing monomer such as 2-vinylpyridine; (6),
Quaternary ammonium base-containing monomer; (7), alkyl ester of ethylenically unsaturated carboxylic acid; (8), nitrile group-containing monomer such as (meth)acrylonitrile; (9), styrene; (10), Esters of ethylenically unsaturated alcohols such as vinyl acetate and (meth)allyl acetate; OI), mono(meth)acrylates of alkylene oxide addition polymers of active hydrogen-containing compounds; 02),
A bifunctional monomer containing an ester group represented by a diester of a polybasic acid and an unsaturated alcohol; 2) consisting of an alkylene oxide addition polymer of an active hydrogen-containing compound and a diester of (meth)acrylic acid; Functional monomer; 04), bisacrylamide such as N-N-methylenebisacrylamide; 05), bifunctional monomer such as divinylbenzene, divinylethylene glycol, divinyl ether, divinyl ketone; 06), containing active hydrogen (+7), polyfunctional unsaturated monomers such as trivinylbenzene; Toluene, xylene, methyl acetate, as appropriate
Printing and impregnation may be performed by diluting it with an organic solvent such as methyl ethyl ketone. Note that, if an ionizing radiation-curable resin is colored by adding an appropriate coloring pigment or dye, the transparent portion can also be colored.

The ionizing radiation curable resin to be used may be printed and impregnated with the viscosity appropriately adjusted depending on the barrier properties of the target base paper, and the viscosity is not limited.

Printing methods include direct methods and indirect methods, and are appropriately carried out using various coating devices such as letterpress printing, flexographic printing, planography, intaglio printing, gravure printing, and screen printing.

The amount of printing impregnation in the printing impregnation part of the ionizing radiation curable resin is preferably adjusted in the range of 0.05 to 100% by weight based on the base paper.If it is less than 0.05% by weight, sufficient transparency will not be obtained. If it exceeds 100% by weight, not only will the transparency effect be saturated, but the required energy will increase and the production rate will decrease.

By printing such resin, the paper of the present invention has the following properties:
The resin in the printed area efficiently impregnates the base paper, and when it is irradiated with ionizing radiation and cured, the resin-impregnated area becomes clearly transparent, so marks, letters, designs, etc. become transparent without blurring. This makes it possible to provide a partially transparent paper that is transparent.

Examples of ionizing radiation used include electron beams, ultraviolet rays,
Examples include α-rays, β-rays, T-rays, and X-rays.

Since α-rays, β-rays, T-rays, and X-rays are associated with the problem of danger to the human body, electron beams and ultraviolet rays are preferably used because they are easy to handle and are widely used industrially.

When using an electron beam, the amount of electron beam irradiated is 0.1~
15 Mrad, more preferably 0.5-5 Mrad
It is desirable to adjust within the range of . By the way, 0°1 M
If it is less than 15 Mra, the resin will be insufficiently cured.
If it exceeds d, the paper strength will decrease significantly. As the electron beam irradiation method, a scanning method, a curtain beam method, a broad beam method, etc. can be appropriately adopted, and an appropriate acceleration voltage for electron beam irradiation is about 100 to 300 kV. Incidentally, electron beam irradiation has the advantage that productivity is higher than that of ultraviolet irradiation, and there is no problem of odor or coloring caused by addition of a photoinitiator.

When using ultraviolet rays, it is necessary to incorporate a photoinitiator into the ionizing radiation curable resin, such as thioxanthone, benzoin, benzoin argyl ether xanthone, dimethylxanthone, benzophenone, anthracene, benzyl, 2,2-jethoxy Acetophenone, benzyl dimethyl ketal, diphenyl disulfide, anthraquinone, 1-chloroanthraquinone, 2-ethylanthraquinone, 2-ter-butylanthraquinone, N
One or more photoinitiators such as N'-tetraethyl-4,4'-diaminobenzophenone and 1,1-dichloroacetophenone are appropriately blended.

Incidentally, the amount of photoinitiator used is 0.0% in the ionizing radiation curable resin.
It is desirable to blend in an amount of about 1 to 10% by weight, preferably about 0.5 to 5% by weight. Furthermore, in addition to such photoinitiators to accelerate curing, e.g. triethanolamine, 2-dimethylaminoethanol, dimethylaminobenzoic acid, isoamyl dimethylaminobenzoate, dioctylaminobenzoic acid, lauryl dimethylaminobenzoate Zero tertiary amines such as
．． It can also be blended in an amount of about 0.05 to 3% by weight.

As a light source for ultraviolet irradiation, an ultraviolet lamp (for example, a low pressure, medium pressure, or high pressure mercury lamp with an operating pressure of a few millimeters and 11 g to about 10 atmospheres), a xenon lamp, a tungsten lamp, etc. is used, and the radiation output is 5000 to 8000 μW/
Ultraviolet rays having an intensity of about ld are preferably irradiated.

In this way, various base papers, coated papers, recording papers, etc. on which watermark patterns and the like are formed can be obtained efficiently and simply.

In addition, this partially transparent paper can be further coated with pigment, resin, recording material, etc. on the resin-printed and impregnated side and/or the opposite side, and can be used for printing paper such as coated paper, carbonless paper ( It can be used in a variety of applications, including making information paper such as pressure-sensitive copying paper and heat-sensitive recording paper.

When a coating layer is provided after the transparentization, the function of the coating layer is less likely to be impaired by the impregnated resin. Further, the coating layer has the advantage that the partially transparent portion is appropriately concealed and the watermark effect is enhanced. On the other hand, when a watermark pattern or the like is formed by directly printing or impregnating the coating layer on or behind the coating layer of coated paper, recording paper, etc., it is excellent in terms of processing such as small lofts and a wide variety of products.

"Examples" The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these. In addition, unless otherwise specified, "1 part" and "%" in the examples are respectively "1 part" and "%".
"parts by weight" and "11%" are shown.

Example 1 Oligoester acrylate (manufactured by Toagosei Kagaku Kogyo Co., Ltd., Aronixst 8
030) 50 parts of monofunctional acrylate (manufactured by Toagosei Kagaku Kogyo Co., Ltd., Aronix M-'101) A floral pattern was printed on the ionizing radiation curable resin adjusted to 50 parts using a letterpress printing machine, After impregnation, an electrocurtain type electron beam irradiation device (manufactured by ESI, CB-150) was applied.
The resin was cured with an irradiation dose of 2 Mrad using a mold) to obtain paper in which the floral pattern part was partially transparent.

Comparative Example 1 20% polyisoprene was applied on the high quality paper used in Example 1.
Using a transparent ink containing 10% dehydrated castor oil and 70% toluene, a floral pattern was printed using a letterpress printing machine, and dried to obtain partially transparent paper.

The two types of partially transparent papers thus obtained were subjected to a 60°C accelerated deterioration test for bleeding for 30 days.

As a result, the paper of the example had no bleeding and the pattern was maintained clearly, but the paper of the comparative example had some bleeding and it was difficult to distinguish the floral pattern.

Example 2 The resin used in Example 1 was printed and impregnated with the company name mark using the printing equipment of Toppan Printing, and then the same process as in Example 1 was carried out. By hardening the resin, we obtained a cast coat with a transparent company name mark.

Example 3 A company name mark was printed and impregnated in the same manner as in Example 2 from the opposite side of a commercially available heat-sensitive recording paper to the side on which the heat-sensitive recording layer was provided, and then the resin was cured to make the company name mark part transparent. A thermosensitive recording paper was obtained.

Example 4 By the same method as Example 2 on base paper of tsubo [50 g/m]
The company name mark is printed and impregnated. A coating liquid containing pigment and adhesive as main components is applied to the printing impregnated side of this base paper in a dry weight of 1.
It was coated at a weight of 5 g/bo, dried, and then supercalendered to obtain coated paper on one side with the company name mark in a watermark.

Example 5 A company name mark was printed and impregnated on a base paper having a basis weight of 45 g/rrr in the same manner as in Example 2. On the print-impregnated surface of this base paper, apply a dry type of paint for heat-sensitive recording paper at 5 g/rrr.
A heat-sensitive recording paper with a watermark-like company name mark was obtained.

Example 6 A company name mark was printed and impregnated on base paper of 140 g/% by the same method as in Example 2. On the opposite side of the base paper from the print-impregnated side, a paint for carbonless paper (color former layer) was applied to a dry weight of 4 g/bot, and the company name mark was placed in a watermark-like manner. A top sheet of carbonless paper was obtained.

"Effects" As described above, according to the present invention, transparent parts such as marks, letters, designs, etc. can be provided on paper easily and efficiently, so that various partially transparent papers can be provided.

In addition, the transparent treated area can maintain clarity without blurring.

[Brief explanation of drawings]

1 to 3 each show an example of the partially transparent paper of the present invention. Figure 1 shows the case where base paper is used as the base paper, Figure 2 shows the case where the base paper has a coating layer (Innnnn coated recording layer, etc.), and Figure 3 shows the case where the base paper is partially transparent. FIG. 6 is a cross-sectional view illustrating a case where a coating layer (pigment coating layer, recording layer, etc.) is further provided later. 1: Partially transparent paper 2: Transparent part 3: Base paper 4: Base paper 5: Coat layer

Claims (1)

[Claims] A partially transparent paper obtained by impregnating at least a portion of a base paper with an ionizing radiation-curable resin and curing the resin by irradiating the base paper with ionizing radiation.