JP2006225803A - Repeelable compression-adhered recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repeelable compression-adhered recording paper having a sealer-processing aptitude and a smooth peel feeling. <P>SOLUTION: This repeelable compression-adhered recording paper having a layer consisting of a pressure sensitive adhesive composition, without showing stickiness and adhesion at a normal temperature and normal pressure but showing adhering property on compression, on at least its one side surface is characterized by consisting of a stock paper before coating, satisfying formula (1) by taking an average unit weight of the stock paper for the recording paper before the coating as X, and a standard deviation of the unit weights as Y, and a base agent of the adhesive of the pressure sensitive adhesive layer as a modified natural rubber latex is characterized by containing 3-20 pt.wt. surfactant based on 100 pts.wt. modified natural rubber latex. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a releasable pressure-sensitive recording paper having sealer processing suitability and smooth peeling feeling.

  In recent years, releasable pressure-sensitive recording sheets have become widespread as confidential postcards as means for notifying personal information such as savings and balances from banks, credit companies, insurance companies, government offices, and the like. After applying a pressure sensitive adhesive to the base material, common information is printed by offset printing, gravure printing, etc. Personal information is printed by laser beam printing (LBP) method, inkjet (IJ) method, etc. The surfaces can be bonded together by applying an appropriate pressure, mailed to each individual, and then peeled off to obtain information.

  As a method of adhering a releasable pressure-sensitive recording paper, it is often used to pressure-bond with a sealer. This adjusts the width | variety (sealer gap) between the rolls of a sealer, and obtains the target moderate peel strength.

  In addition, the releasable pressure-sensitive recording paper needs to be strong enough not to be peeled off during mailing, while the addressee is strong enough to smoothly peel the pressure-bonded part. Therefore, adjustment of peel strength is an important issue.

  However, conventional re-peelable pressure-sensitive recording paper has been difficult to adjust because of a large change in peel strength when the sealer gap is changed. For example, when the sealer gap is narrower than the appropriate width, the peel strength is remarkably increased and not only difficult when peeling, but if it exceeds the surface strength of the paper, the paper breaks and the content information can be read. There is a risk of disappearing. On the other hand, when the sealer gap is wide, an appropriate peel strength cannot be obtained, and there is a possibility of opening at the time of mailing.

  Further, a material having a large unevenness (variation) in peel strength is not preferable because even if the peel strength is appropriate, a smooth peel feeling cannot be obtained. In severe cases, a local increase in peel strength due to unevenness may lead to paper breakage.

  Therefore, the object of the present invention is to reduce the dependence of the peel strength on the sealer gap when crimping with a sealer, that is, it is possible to give a constant peel strength with a constant sealer gap and to be able to peel smoothly. It is to provide a peelable pressure-sensitive recording sheet.

As a result of earnest research to solve the above-mentioned problems, the present inventor does not exhibit tackiness and adhesiveness at normal temperature and normal pressure, exhibits adhesiveness when pressed, and can be peeled off after pressure bonding. In a releasable pressure-sensitive recording paper having an adhesive layer on at least one side, when the average basis weight of the base paper before coating of the paper is X and the standard deviation of the basis weight is Y,

And the pressure-sensitive adhesive layer is solved by a releasable pressure-sensitive recording sheet characterized by comprising 3 to 20 parts by weight of a surfactant per 100 parts by weight of a modified natural rubber latex. I found it.

  By adopting such a configuration, it is possible to provide a releasable pressure-sensitive recording paper that can give a certain peel strength with a certain sealer gap and can be peeled smoothly when crimping with a sealer. Can do.

  Hereinafter, the present invention will be described in more detail. That is, the present invention has found that the peeling strength is partially significantly increased due to the overlapping of the fine irregularities of the basis weight due to deterioration of the formation, thereby causing paper breakage. Furthermore, by resolving this problem, it has become possible to obtain a releasable pressure-sensitive recording paper having a feeling of peeling that is difficult to tear.

  In general, it is known that paper with poor formation has a large basis weight unevenness. In the present invention, 4900 data of the basis weight of a minute portion of 1 mm × 1 mm was measured for basis weight unevenness, and the standard deviation calculated from these values was used.

  The standard deviation increases as the basis weight increases. Therefore, the value obtained by dividing the standard deviation by the square root of the basis weight is commonly used as a measure of formation (“standardized standard deviation”), and when the average basis weight X and the standard deviation Y of basis weight are used.

It is shown by the formula of

  When crimping the stacked sheets, if the parts with high basis weight overlap each other, the peel strength will rise significantly compared to other parts, and conversely if the parts with low basis weight overlap each other, the peel strength will be different It tends to decrease significantly compared to the portion. This tendency is large for paper with large basis weight unevenness. As a result, not only does the paper peel off worse, but if the unevenness is severe, there is a risk of paper tearing starting from a portion having a high peel strength. As a result of the experiment, the “standardized standard deviation” of the basis weight of a minute portion of 1 mm × 1 mm is less than 0.6 (preferably less than 0.55), and excellent in peeling feeling and less likely to tear. It was confirmed that it was obtained.

  In the present invention, it was also found that the dependence on the sealer gap can be further reduced by adding a surfactant to the pressure-sensitive adhesive composition. The mechanism is not clear, but due to the buffering effect of the surfactant, the adhesive action (mutual dispersion action) between the natural rubber components that occurs when the stacked sheets are pressure-bonded is suppressed. It is considered possible. In addition, the addition of a surfactant can improve miscibility among natural rubber components, fine particles, cationic components, etc., and therefore can suppress a significant increase in local peel strength due to aggregation or the like. it is conceivable that.

  As the surfactant used in the present invention, one or more surfactants can be appropriately selected from known anionic surfactants, cationic surfactants, nonionic surfactants, and the like. Is preferable. Examples of anionic surfactants include fatty acids, sulfonic acids, phosphoric acids, succinic acids, sulfosuccinic acids, carboxylic acids, and polycarboxylic acids, and cationic surfactants include alkylamine salts. Benzylamine salt system, polyamine and the like.

  Nonionic surfactants include ether, alkylphenol, ester, alkylolamide, glycerin, glycerin ester, sorbitan ether, sorbitan ester, sorbitan ester ether, ethylene oxide, propylene oxide. Examples thereof include those having a large HLB (hydrophilic / lipophilic balance) value.

  When the content of the surfactant in the pressure-sensitive adhesive composition is less than 3 parts by weight relative to 100 parts by weight of the modified natural rubber latex, the effect of suppressing the sealer gap dependency is small. On the other hand, when the amount exceeds 20 parts by weight, the coating liquid is remarkably foamed, so that coating becomes difficult. Further, it is not preferable in terms of workability such as a decrease in peel strength and deterioration in printing / printing suitability. Therefore, in the present invention, the content of the surfactant in the modified natural rubber latex needs to be 3 to 20 parts by weight. The content of the surfactant is preferably 4 to 18 parts by weight.

  Examples of the modified natural rubber latex in the pressure-sensitive adhesive composition used in the present invention include, for example, a product obtained by graft polymerization of methyl methacrylate on natural rubber.

  In these pressure-sensitive adhesive compositions, one or more of known tackifiers (terpene phenol resin, polybutene resin, rosin ester resin, petroleum resin, etc.) can be used as necessary.

  These pressure sensitive adhesive compositions include silica, calcium carbonate, kaolin, aluminum hydroxide, clay, magnesium oxide, magnesium hydroxide, talc, titanium oxide, zinc oxide, calcium sulfate, barium sulfate, polyethylene, polypropylene, polystyrene. One or more kinds of known fine particle fillers such as urea formalin resin can be used as necessary.

  In addition, in the pressure-sensitive adhesive composition, a dispersant, an antifoaming agent, an anti-aging agent, an antioxidant, an ultraviolet absorber, an antifungal agent, a deodorant, a water-proofing agent, a fluorescent enhancement agent, if necessary. Additives such as whitening agents can be added.

The pressure-sensitive adhesive composition is applied by a general coater such as an air knife coater, roll coater, blade coater, rod blade coater, bar coater, die coater, etc., but the coating amount is 3 to 3 by dry weight. It is desirable to adjust in the range of 15 g / m ² . The reason why the coating amount is limited to the above range is that if it is less than 3 g / m ^2, it is not preferable because it is inferior in terms of visual quality such as print quality and printing finish, and further the peel strength is lowered. On the other hand, when the coating amount exceeds 15 g / m ² , the visual appearance such as the print quality and the print finish is improved, but the practicality is inferior from the economical viewpoint, the writing property is poor, and paper dust is generated. It is easy to do and is not preferable.

Example:
The present invention will be described with reference to the following examples and comparative examples, but the present invention is not limited to these examples. In addition, all the weight parts (part) of an Example and a comparative example shall show with the numerical value in conversion of solid content.

  The basis weight unevenness of the paper was measured by the AMBERTEC BETA FORMATION TESTER (total of β-line) and the basis weight of a minute part of 1 mm × 1 mm unit (4900 data). Average basis weight X, standard deviation Y of basis weight

From the equation, the “standardized standard deviation” of the basis weight unevenness was calculated.

  The pressure-sensitive adhesive composition used in the present invention includes 100 parts of amorphous silica, 100 parts of methyl methacrylate-grafted natural rubber latex, 20 parts of modified polyvinyl alcohol as a binder, 20 parts of cationic resin, and an anion as a surfactant. A blend of 5 parts of Perex NB-L (manufactured by Kao Corporation) was made. Next, when this pressure-sensitive adhesive composition is defined as an average basis weight X and a standard deviation Y of basis weight,

Values to obtain a coating to removability crimping recording sheet as coating amount in fine paper 127.9 g / m ² is about 0.5 is 7 g / m ² (dry weight). This was designated Example 1.

  The obtained releasable pressure-sensitive recording paper was evaluated by a peel strength test, peel strength variation evaluation, print suitability test, IJ suitability test, and paper breakage test.

  A releasable pressure-sensitive adhesive recording sheet was prepared in the same manner as in Example 1 except that the pressure-sensitive adhesive composition of Example 1 was changed to Emulgen 420 (manufactured by Kao Corporation) which is nonionic as the surfactant. This was taken as Example 2.

  A releasable pressure-sensitive recording sheet was prepared in the same manner as in Example 1 except that the compounding part of the surfactant was changed to 15 parts in the pressure-sensitive adhesive composition of Example 1, and this was designated as Example 3. .

Comparative Example 1
As the base paper before coating, the average basis weight X and the standard deviation Y of basis weight

A re-peelable pressure-sensitive recording sheet was prepared in the same manner as in Example 1 except that the quality was changed to 127.9 g / m ² of high-quality paper having a value of about 0.8.

Comparative Example 2
A re-peelable pressure-sensitive recording sheet was prepared in the same manner as in Example 1 except that the compounding part of the surfactant was changed to 1 part in the pressure-sensitive adhesive composition of Example 1, and this was designated as Comparative Example 2. .

Comparative Example 3
A re-peelable pressure-sensitive recording sheet was prepared in the same manner as in Example 1 except that the compounding part of the surfactant was changed to 30 parts in the pressure-sensitive adhesive composition of Example 1, and this was designated as Comparative Example 3. .

  Various characteristics of the releasable pressure-sensitive recording paper obtained in the above Examples and Comparative Examples were evaluated according to the following test methods.

  Peel test (strength): Cut into a width of 100 mm and a length of 100 mm, and the coated surfaces were overlapped and pressure-bonded using a dry sealer (Pressle Econo: manufactured by Toppan Foams Co., Ltd.). Next, the width direction center part of this sample was cut | judged to 25 mm width, and 23 degreeC and 50% R. H. Peeling strength gf / 25mm was obtained by peeling with a strograph M-1 type (manufactured by Toyo Seiki Seisakusho) at a speed of 300 mm / min and peeling (T-type peeling) strength and averaging the resistance values. A: 100 to 150 gf / 25 mm, O: 50 to less than 100 gf / 25 mm, Δ: 20 to less than 50 gf / 25 mm, X: 0 to less than 20 gf / 25 mm, A and O indicate a practical level of peel strength, Δ And x indicate levels that cannot be practically used. In the following, ◎ indicates excellent performance, ○ indicates performance at practical level, Δ indicates performance level that cannot withstand practical use, and × indicates unsatisfactory performance level.

  Peel test (variation): In accordance with the above-described peel strength test, crimping is performed so that the peel (T-type peel) strength is 40 gf / 25 mm. Peeling was performed with a strograph M-1 type (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a speed of 300 mm / min and peeling (T-type peeling) strength, and the variation from the average value of the resistance values was compared. A: Variation is less than 0-5%, O: Variation is less than 5-10%, Δ: Variation is less than 10-15%, X: Variation is 15% or more.

  Printing suitability test: An RI-3 type printing suitability tester (manufactured by Meisei Seisakusho) was used to visually observe and evaluate ink density, printing durability, and the like. The case where there was no peeling of the coating layer with ink or paper was marked as ◎, ○, Δ, ×.

  Inkjet (IJ) printability test: Cytex 1040 black ink was injected into an ink cartridge of an inkjet printer (HP DeskJet 560J, manufactured by Hewlett Packard), and a test print pattern (characters, lines, solid) was printed and evaluated by visual feeling. . The clear images and prints obtained were marked with ◎, ○, Δ, and ×.

  Paper tearing suitability test: Crimped so that the peel (T-type peel) strength is 100 gf / 25 mm according to the peel strength test. Thereafter, the degree of paper breakage was evaluated by visual sensation. The coating layers were not peeled off due to peeling and the paper was not torn.

  The test results of the releasable pressure-sensitive recording paper prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1 below.

  As can be seen from Table 1, the releasable pressure-sensitive recording paper of the present invention of the Examples exhibits excellent effects such as peel test (strength), peel test (variation), printability, IJ printability, and paper breakability.

  In contrast, “standardized standard deviation” (when the average basis weight is X and the standard deviation of basis weight is Y,

In the case of Comparative Example 1 deviating from the range defined in claim 1 (less than 0.6), paper breakage is likely to occur and it is not practical.

  When the surfactant of the pressure sensitive adhesive composition deviates from the range of 3 to 20 parts with respect to 100 parts of the modified natural rubber latex and is 1 part of Comparative Example 2, the paper breaks as in Comparative Example 1. Is likely to occur and is not practical. Similarly, in the case of Comparative Example 3 in which the surfactant of the pressure-sensitive adhesive composition is 30 parts, the peel strength, printability, and IJ suitability are poor and cannot be put into practical use.

Claims (2)

In a releasable pressure-sensitive adhesive recording sheet having a pressure-sensitive adhesive layer on at least one side that does not exhibit tackiness and adhesiveness at normal temperature and normal pressure but does not exhibit adhesiveness when pressed and can be peeled after pressure bonding. When the average basis weight of the base paper before construction is X and the standard deviation of basis weight is Y,

And a pressure-sensitive adhesive layer comprising 3 to 20 parts by weight of a surfactant per 100 parts by weight of a modified natural rubber latex. The releasable pressure-sensitive recording sheet according to claim 1, wherein the surfactant is nonionic.