JP3120581B2 - Release paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release paper. In particular, the present invention relates to a release paper capable of providing an adhesive paper having excellent curl behavior and excellent light transmittance.

[0002]

2. Description of the Related Art Adhesive paper is generally composed of a surface substrate, an adhesive and a release paper.
Labels, stickers, stickers,
It is used after being processed into the form of patches.

[0003] As the surface substrate, high-quality paper type, coated paper type, cast coated paper type,
It can be classified into other special types. As special types, aluminum foil laminated paper, aluminum evaporated paper, resin-impregnated paper, thermal recording paper, etc. are used.

As the adhesive, rubber-based and acrylic-based adhesives are often used. Among them, acrylic esters, acrylic acid, methacrylic acid, acrylamide, vinyl acetate, and the like are mainly used.
Acrylics containing styrene, acrylonitrile or the like as a main component are increasing.

[0005] Release papers can be classified into polyethylene laminate type, glassine type, super calendered craft type, clay coat type, aqueous resin coat type, film base type and the like. Among them, polyethylene laminate type and glassine type are often used. The polyethylene laminate type
High-quality paper, kraft paper, etc. are used as base paper, and polyethylene is laminated to prevent penetration of a release agent such as silicon. As the polyethylene, a high pressure method low density polyethylene is typical.

When glassine paper is used as the base paper, the release agent is less likely to seep into the base paper, so that the release agent may be directly applied. A feature of the glassine type is that light transmission is good.
Measurement labels attached to meat, fresh fish, prepared foods, and the like in supermarkets and the like are often used by printing a barcode or the like on an adhesive paper having thermal paper as a base material.

The adhesive paper after printing and die-cutting is set in a roll in a label printer, and a bar code,
The price and the like are printed. At this time, in order to detect the position of the surface base material, a difference in light transmittance between the adhesive paper and the release paper is used. For this reason, it is common to use a glassine type having good light transmittance as a release paper used for such purposes.

However, a drawback of the glassine-type release paper is that the pulp fibers are highly beaten and have a high density, so that the dimensional change at the time of dehumidification is large, and curling is likely to occur.
The pulp fiber expands at the time of moisture absorption, but the glassine paper has a high density so that the expanded portion cannot be alleviated. If one side absorbs moisture, for example, it curls immediately. Such curl caused by the release paper leads to various operational problems. For example, printing, die-cutting (punching), misalignment of printing by a label printer, and the like, lead to poor running performance.

As a method for correcting the curl of the adhesive paper, a curl breaker for correcting the curl by squeezing or a method for humidifying the back side of the release paper is used, but the complexity of the process is inevitable. Under such circumstances, it has been desired to develop a release paper which has excellent light transmittance and good curl behavior.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a release paper having excellent light transmittance and good curl behavior.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a release paper used for pressure-sensitive adhesive paper obtained by laminating a surface substrate, a pressure-sensitive adhesive layer and a release paper. Method, No. 5m-74), for a glossy paper of 80 to 200 seconds, and an opacity (JIS-P8138) of 5 after treatment.
Release paper characterized in that paper that has been calendered to have a value of 5 or more and 70 or less is used as a base paper.

The release paper manufactured in this way has a smaller dimensional change during moisture absorption and desorption than glassine paper, and has excellent curl behavior. In addition, penetration of a release agent such as silicon into base paper can be prevented by laminating a conventionally known polyethylene or the like, and providing an undercoat layer containing polyvinyl alcohol, casein, acrylic resin, or the like as a main component. Can also be prevented.

As a technique for adjusting the smoothness of paper, there is a method of making a raw material mainly composed of cellulose pulp, drying it with a Yankee dryer, and increasing the smoothness of only one side of the paper in contact with the dryer (produced by this method). There is known a method of increasing the smoothness of both sides of the paper by calendering the paper produced by drying with a multi-cylinder dryer with a known machine calender or super calender.

Comparing the characteristics of the papers manufactured by the above two methods, the single-sided paper has higher smoothness on one side and a lower density than paper calendered after drying and manufacturing with a multi-tube dryer. . According to the research results of the present inventors, the use of plain paper as the base paper for release paper is well suited to the purpose of the present invention, to provide an adhesive paper having excellent curl behavior. . This is, for example,
No. 0-53075. However, the present inventors have found that the use of ordinary single-sided glossy paper as a base paper for release paper has a problem in light transmittance.

In the present invention, in order to solve this problem, calendering of single gloss paper is performed so that the opacity (JIS-P8138) after processing is 55 or more and 70 or less. The smoothness of the glossy surface of the single gloss paper used in the present invention is 80 to 2
00 seconds, more preferably 100 to 150 seconds. 80
If the time is less than seconds, the papermaking wet paper is not sufficiently dried by the Yankee dryer, and the paper is high in moisture, so that wrinkles are likely to be generated. In addition, the higher the smoothness, the smaller the amount of polyethylene lamination required, which is desirable from the viewpoint of economical efficiency. 5
It is necessary to set it to 5% or more, which is not preferable because the load on the Yankee dryer is increased and productivity is reduced.

In the present invention, calendering is performed in order to make the single-sided glossy paper a base paper for release paper having good light transmittance.
Opacity (JIS-P8138) after processing is 55 or more and 7
0 or less. Calendering is frequently performed mainly for the purpose of smoothing paper in pigment coated paper and the like.For example, a machine calender combining metal rolls, a super calender combining elastic rolls and metal rolls Calendars, soft calendars, etc. can be used.

The present invention improves the light transmittance of the paper and makes the surface and thickness of the entire paper more uniform by such calendering. The opacity of the paper after the processing (JIS-P8138) ) Is set to 55 or more and 70 or less, and calendar processing is performed by adjusting processing conditions such as linear pressure and the number of times of processing.

In order to make the opacity of the paper smaller than 55, the calendering conditions must be extremely increased.
Not only is it not practical, but also leads to a decrease in paper strength and also to a paper breakage during die cutting, which is not preferable. On the other hand, if it is larger than 70, the light transmittance becomes poor, and the position of the label cannot be detected by the positioning sensor in the labeler, which causes a problem.

As the metal roll used for the calender, for example, a chill roll, an alloy chill roll, a steel roll, or a metal roll having a hard chrome-plated roll surface can be appropriately selected and used. Examples of the elastic roll include natural rubber, styrene rubber, nitrile rubber, chloroprene rubber, chlorosulfonated ethylene rubber, butyl rubber, polysulfide rubber, silicon rubber, fluorine rubber, urethane rubber, aromatic polyamide resin, polyimide resin, and polyether. An elastic roll made of various plastic resins such as resin, polyester resin, polycarbonate resin, epoxy resin and phenol resin, cotton, paper, wool, Teflon, nylon or a mixture thereof can be used.

When processing a glossy paper by calendering with such a pressurizing device, conditions are adjusted using the nip pressure and the like as variables. The calendaring may be performed in one stage or two or more stages. Regarding the nip pressure, the treatment linear pressure in a calendar of a combination of metal rolls that is usually used is about 1 to 50 kg / cm. Therefore, the adjustment range of the processing linear pressure can be widened to 3 to 500 kg / cm.

As the pulp used in the present invention, various types of pulp can be used. As a preferable pulp, for example, chemical pulp obtained by digesting a lignocellulosic material derived from softwood and hardwood with an alkaline cooking chemical is used. Examples include pulp and deinked waste paper pulp (DIP).

As chemical pulp, Kraft pulp (digestion liquor, NaOH + Na ₂ S), polysulfide pulp (digestion liquor, NaOH + Na ₂ SX), soda pulp (digestion liquor, NaOH), sulfite pulp (digestion liquor, Na
₂ SO ₃ ), sodium carbonate pulp (pulping liquor, Na ₂ C
O ₃ ) and oxygen soda pulp (pulping liquor, O ₂ + NaO
H).

In producing these pulps, a cyclic keto compound (for example, anthraquinone, 1,4-dihydro-9,10-diketoanthracene) may be added as a cooking aid to the cooking liquor for cooking. Among the digested pulp, kraft pulp is more preferable for the purpose of the present invention. The kraft pulp may be pulp obtained by a so-called modified alkaline cooking method (MCC method), which includes divided addition of a cooking liquor, cocurrent cooking and countercurrent cooking inside a digester. These chemical pulps can be unbleached, bleached, or unbeaten,
It is used alone or as a mixture in the state of beaten pulp.
Of course, it may be used by mixing with DIP.

As the papermaking and drying apparatus in the present invention, it is highly desirable that the apparatus for drying the wet paper after the papermaking is a Yankee dryer, but other than that, for example, the type of the wire part is any. Is also good.
There is no problem even if the multi-cylinder dryer is installed before the Yankee dryer. The calendar is preferably of either an on-machine type or an off-machine type.

The base paper for release paper thus obtained is subjected to polyethylene lamination and then coated with a release agent to form release paper. Polyethylene is usually extruded
Laminate on the glossy surface of the base paper so as to have a thickness of 10 to 20 μm. Although there are various types of release agents, a common silicon-based release agent may be used, and the release agent is applied using various coaters such as a Meyer bar.

The adhesive paper may be processed by any known method, but the release paper according to the present invention is a weighing label which uses a photoelectric tube to adjust the position when labeling a label because of its good light transmittance. Ideal for use.
In particular, it is suitable for use as an adhesive paper using a thermal recording paper having a protective layer provided on a thermal recording layer as a surface substrate.
When the heat-sensitive recording paper provided with the protective layer on the heat-sensitive recording layer is an adhesive paper, the curling behavior is worse than that of the high-quality paper. This is considered to be due to the fact that the difference in expansion and contraction from the release paper increases because expansion and contraction is suppressed by the protective layer. Such a thermosensitive recording paper is described in, for example, JP-A-59-45191.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, of course, are not intended to limit the scope of the present invention. % Indicates% by weight. Unbleached pulp is produced by a kraft digestion method using a conifer consisting of domestic hardwood, 15% Douglas fir, 10% hemlock, and 75% domestic pine in a Kamiya continuous digester, followed by oxygen bleaching and C- A bleached bleached pulp (hereinafter, LBKP) and a softwood bleached pulp (hereinafter, NBKP) having a whiteness of 85 were produced by bleaching in a sequence consisting of EHD.

These pulp are used for freeness (CS.
F) was separately beaten to 530 ml of LBKP and 580 ml of NBKP, blended so that LBKP: NBKP = 50: 50, and the following papermaking chemicals were added at a ratio of absolutely dry pulp to 100%. Cationized starch (Oji National, Kate F): 0.8% Rosin emulsion (Arakawa Chemical, SPN): 1.1% Anion-modified polyacrylamide (same as above, polystron): 0.3% From this stock Using a well-known Fourdrinier Yankee dryer type paper machine, single-sided glossy paper A having a rice tsubo of 50 g / m ² was produced. The smoothness of the glossy surface of the single-sided paper thus obtained was 120 seconds, and the water content was 6.
5%.

In the production of the matte paper A, the freeness of the pulp was LBKP 420 ml and NBKP 450 ml.
Single-sided paper B was produced in the same manner as single-sided paper A except that the ratio was set to LBKP: NBKP = 70: 30. The smoothness of the glossy surface of the single-sided paper thus obtained was 190 seconds, and the water content was 6.5%.

In the production of the matte paper A, the freeness of the pulp is LBKP 600 ml, NBKP 610 ml,
Single-sided paper C was produced in the same manner as single-sided paper A except that the ratio was set to LBKP: NBKP = 30: 70. The smoothness of the glossy surface of the single-sided glossy paper thus obtained was 85 seconds, and the water content was 6.5%.

In the production of the single-sided glossy paper A, the paper was peeled off from the Yankee dryer in a state where the water content was 8.2% so as to make the smoothness less than 80 seconds, and an attempt was made to wind it into a roll. I couldn't wind up well. Also,
When the paper was kept in contact with a Yankee dryer for a long time to increase the smoothness to more than 200 seconds, the paper water content was reduced to 4% or less. This also causes a problem in that the production capacity is reduced.

The matte papers A, B, and C were processed using a machine calender and a super calender while changing the pressing conditions and the number of treatments so that the opacity shown in Table 1 was obtained. 7 types of samples obtained in the above process, and for comparison, calendered paper without calendaring, A, B, C, and 64 g
/ M ² opacity of glassine paper (JIS-P8138)
Was measured.

If the opacity is 70 or less, there is no problem in detecting the position of the surface substrate with the phototube by the labeler.

Polyethylene (Sumikacene L-402, manufactured by Sumitomo Chemical Co., Ltd.) having a thickness of 10 μm was applied to the glossy surfaces of the eight types of calendered calendered samples and the uncalendered calendered papers A, B, and C. After lamination, a release agent silicone SRX-211 (manufactured by Toray Silicone Co., Ltd.) was applied with a Mayer bar at 0.5 g / m ² (in terms of solid content) and dried and cured to produce a release paper. Also, the same release agent was applied to the above-mentioned glassine paper in a coating amount of 1.0.
g / m ² (solid content).

An acrylic emulsion pressure-sensitive adhesive (Sibinol AT-560, manufactured by Seiden Chemical Co.) was applied to the release agent-coated surface of these release papers with a Mayer bar so that the dry weight was 25 g / m ² . Subsequently, a rice tsubo 7 having a protective layer provided on the heat-sensitive recording layer as a surface base material on the pressure-sensitive adhesive layer was used.
Thermal recording paper of ² g / m ² was overlaid and bonded with a press roll.

The curl characteristics under high humidity, the die cut suitability of the 11 kinds of adhesive papers thus obtained, and the peelability were examined in order to determine whether or not polyethylene was effectively laminated. Curling characteristics under high humidity are 30 ° C, 85
A sample cut to A4 size under a% RH environment was placed on a horizontal table, and the heights of the four corners from the horizontal table were examined. There is no problem if it is 15 mm or less. The die-cutting suitability was examined by checking whether paper breakage occurred when die-cutting was performed in an actual machine. ○ indicates that the die cutting was successfully performed, and X indicates that the die cutting was not successfully performed and the release paper was cut. Regarding the releasability, the surface base material was peeled off by hand, and it was examined whether or not it could be peeled off without any problem. ○ indicates that the release paper was torn without any problem, and x indicates that the release paper was torn because the release was not successful.
Table 1 summarizes these results.

Table 1. Flat paper Calender Opacity Die cut High humidity Peelability-Processing suitability Curl Example 1A Yes 57.2 ○ 5 ○ Example 2 A Yes 63.2 ○ 8 ○ Example 3B Yes 62.6 ○ 12 ○ Execution Example 4 B provided 65.5 ○ 14 ○ Example 5C provided 67.8 ○ 4 ○ Example 6 C provided 69.4 ○ 8 ○ Comparative Example 1 A None 73.2 ○ 10 ○ Comparative Example 2 B None 75. 2 ○ 13 ○ Comparative example 3 C None 77.0 ○ 9 × Comparative example 4 A Yes 54.3 × 5 ○ Comparative example 5 Glassine paper 67.2 ○ 30 ○

From Table 1, it can be seen that the opacity was adjusted to the range specified in the present invention by calendering.
Each of the six types has not only a light transmittance that does not hinder the position adjustment with the phototube at the time of labeling by the labeler, but also a value of the high-humidity curl exceeding the allowable limit of 15 mm. No evaluation was made, and the evaluation of die-cut characteristics and peelability was also excellent. On the other hand, in the case of Comparative Examples 1 to 3 in which the calendar processing was not performed and the opacity exceeded the upper limit of the numerical value specified in the present invention, the light transmittance that hindered the position adjustment with the photoelectric tube was observed. belongs to. In addition, even though calendering is performed, Comparative Example 4 in which the opacity shows a numerical value lower than the lower limit of the numerical range of the present invention has sufficient light transmittance, but has a problem in die cut suitability, It can be seen that the glassine paper of Comparative Example 5, which has no problem in opacity, die cut suitability, and peelability, has a problem that the high-humidity curl characteristic is extremely poor.

As described above, the present invention provides curling characteristics,
The present invention has been able to provide a release paper which has excellent releasability and has light transmittance which does not cause a problem in alignment of a surface substrate with a photoelectric tube.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Shichi 1 Oji-cho, Kasugai-shi, Aichi Oji Paper Kasugai Mill Co., Ltd. (56) References JP-A-2-14100 (JP, A) JP-A-1- 223184 (JP, A) JP-A-60-110999 (JP, A) JP-A-5-331793 (JP, A) JP-A-62-197483 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) D21H 25/00-27/42 C09J 7/00-7/04 B32B 1/00-35/00

Claims (2)

(57) [Claims] In a release paper used for an adhesive paper obtained by laminating a surface substrate, an adhesive layer and a release paper, the smoothness on the glossy side (J. TAPPI paper pulp test method, No. 5m-7)
4) Release paper characterized by using, as a base paper, a paper obtained by calendering a single glossy paper of 80 to 200 seconds and a opacity (JIS-P8138) of 55 to 70 after processing. 2. The release paper according to claim 1, wherein the heat-sensitive recording paper provided with a protective layer on the heat-sensitive recording layer is used as an adhesive paper used as a surface substrate.