JPH11208162A - Secret card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a card having no flow trouble of a hot-gluing resin at an exposed step and pseudo-adhering in a wide temperature range at a low temperature. SOLUTION: A laminate obtained by doubling one composite sheet formed by adhering a polypropylene film surface of a composite biaxially oriented polypropylene film having a hot-gluing resin layer on one side surface to a support so that the resin layer is disposed at an inside, and thermally press bonding it, comprises a copolymer of a propylene and other α-olefin in the hot-gluing resin of the resin layer, a blocking resistant agent selected from an organic or inorganic fine particles of 0.05 to 0.5 wt.% in the resin layer so that a releasing strength at 180 degrees at 25 deg.C of thermally press bonded of the resin layers under the conditions of 90 deg.C, 2 kg/cm<2> , 0,5 sec at insides of the biaxially oriented polypropylene films is 30 g/25 to 350 g/25 mm, and the laminate having a step of at least one position near superposed ends of the laminate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to communication or transportation using a single card, such as a postcard, in which information inside is not seen while moving, and by recording information inside, only one card is recorded. And a secret card whose information amount is larger than that of the secret card.

[0002]

2. Description of the Related Art In recent years, secret cards such as the present invention have been used as postcards requiring confidential communication or postcards intended to double the amount of information such as direct mail. It has become.

[0003] Japanese Patent Application Laid-Open No. 1-16692 discloses that "a sheet material consisting of two leaves which can be folded inward at a broken line and whose edges do not completely coincide with each other at the time of folding and produce a level difference, and a pseudo adhesive layer. A normal postcard consisting of a transparent pseudo-adhesive laminate consisting of two films that are peelably adhered through each other (when the sheets are folded, each film makes the opposite surface of each leaf non-peelable to the sheet material) Adhesion) "is described.

In the above publication, the method of forming a pseudo-adhesive laminate is as follows: (1) a method in which each film is closely adhered and integrated by a pseudo-adhesive layer before folding the sheet material; At the same time, two methods, that is, a method in which a film and a pseudo adhesive layer are closely adhered and integrated, are exemplified. Also,
Regarding the bonding between the pseudo-adhesive laminate and the sheet material, (a) a method of bonding each film to each leaf of the sheet material by heat-sensitive bonding or pressure-sensitive bonding at the time of feeding, (b) a sheet material which has been printed before cutting and before cutting. A method in which a pseudo-adhesion laminate is formed, (c) a method in which a film in which a pseudo-adhesion raw material film is formed on one of the films, a method of forming a pre-cut sheet material before cutting, is exemplified. . Cross-sectional schematic diagrams corresponding to the above examples are shown in FIGS. 1 (a), 1 (b) and 1 (c).

FIG. 2 is a schematic cross-sectional view of a completed normal postcard manufactured by the above-described methods. According to this method, since a layer having a low melting point, such as a pseudo-adhesion layer, is not exposed during thermocompression bonding, there is an advantage that there is no problem of adhesion to a heat roll or the like. However, as can be seen from FIG. 2, when the peeling is started from the step portion, it is not certain from which part the peeling force acts, and it is not clear which of the pseudo adhesive layer and the two-leaf film to peel. In such a case, while the one film and the pseudo-adhesive layer are peeled off, the other film and the pseudo-adhesive layer are also peeled off at the same time.

On the other hand, Japanese Utility Model Application Laid-Open No. 3-124885 discloses that the back side of a stretched polypropylene film having a surface coated and heat-sealed on one surface of the substrate is adhered to the film surface. "A secret card that is folded inward in half".
FIG. 3D shows a schematic sectional view before bending in this case, and FIG. 4 shows a schematic sectional view after bending. According to this method, the pseudo adhesion layer becomes two layers, and when peeling is started from the step portion, a peeling force acts on an interface between the two pseudo adhesion layers,
It has the advantage that the peeling place is fixed. Further, this publication exemplifies coating of polyethylene as a pseudo-adhesion layer.

[0007]

The present inventor has conducted studies based on these prior arts, and as a result, has found that the above-mentioned Japanese Utility Model Application Laid-Open No. H3-1248 has been disclosed.
In No. 85, it has been found that when the sheet is folded in half and bonded by a hot roll or a hot plate, there is a problem that the heat-adhesive resin at the exposed step portion flows and adheres to the roll or the like. In addition, polyethylene resin is in a pseudo-adhesion state only in a narrow temperature range, and if the temperature at the time of pseudo-bonding is low, the adhesive strength is weak, and if the temperature is high, complete adhesion is obtained,
There was a problem that peeling from the base film also occurred. An object of the present invention is to solve these two problems.

[0008]

In order to solve the above problems, the present invention employs the following constitution. That is, the present invention provides a composite sheet formed by bonding a polypropylene film surface of a composite biaxially stretched polypropylene film having a heat-adhesive resin layer on one surface to a support, wherein the heat-adhesive resin layer is A secret card that is a laminate that is folded in two so as to be heated and pressed and that satisfies the following conditions (1) to (4): (1) The heat-adhesive resin forming the heat-adhesive resin layer contains a copolymer of propylene and another α-olefin. (2) The heat-adhesive resin layer contains 0.05 to 0.5% by weight of an anti-blocking agent selected from organic or inorganic fine particles. (3) The composite biaxially oriented polypropylene films are bonded together with the heat-adhesive resin layer inside at a temperature of 90 ° C., a pressure of 2 kg / cm ² ,
The thermocompression bonding was performed at a temperature of 25 ° C for 1 second at a time of 0.5 seconds.
Peel strength when peeling at 80 degrees is 30 g / 25 mm or more
The range is 350 g / 25 mm. (4) The laminate has at least one near the edge of the overlap.
It has a step portion at each point.

Further, the present invention includes, in the above invention, an embodiment in which the heat-adhesive resin layer contains a slip agent having a melting point of 70 ° C. or higher.

[0010] Further, the present invention includes, in each of the above inventions, an embodiment in which the heat-adhesive resin layer contains crystalline polybutene.

In the present invention, in each of the above inventions, the antiblocking agent is selected from silica, talc, calcium carbonate, and silicone particles, and the average particle size is 0.1 to 10 μm.
And at least one type of fine particles.

The present invention also includes a postcard using the secret card according to any one of the above-mentioned inventions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As a support used in the present invention,
Is a sheet of paper, plastic, non-woven fabric, etc.
However, when used as a postcard, the basis weight is 100
~ 300g / m ^Two Degree, especially 140-200 g / m^Twoof
Paper is preferred. In addition, general cards include polyethylene
Cards made of renterephthalate are preferred.

On the outer surface of the support, that is, on the surface on which the composite biaxially oriented polypropylene is not bonded, for example, letters of "postcard" or "postal code field" may be printed. , Tint block printing, color coloring, or decoration such as vapor deposition.

The composite biaxially oriented polypropylene contains a biaxially oriented polypropylene film as a base material layer and a propylene-α-olefin copolymer as a heat-adhesive resin layer.
The α-olefin is a lower α-olefin other than propylene, for example, ethylene, butene, pentene, and butadiene. As the resin used for the biaxially stretched polypropylene film, a propylene homopolymer can be used, but it is a copolymer containing propylene as a main component and has a difference in transparency and rigidity of 20% or more from that of the propylene homopolymer. Anything that does not have to be used. Further, if necessary, other resins and additives may be added to the extent that the above-mentioned purpose is not impaired.

The biaxial stretching method of polypropylene includes:
Either simultaneous biaxial stretching or sequential biaxial stretching may be used. The stretching ratio is required to be 3 × 3 or more in vertical and horizontal directions. In consideration of transparency and rigidity, sequential biaxial stretching is performed,
It is particularly preferred that the film be stretched 5 times to 9 times horizontally. The thickness of the composite biaxially oriented polypropylene film is 9 to 4
0 μm, preferably 12 to 30 μm.

In the present invention, the polypropylene biaxially stretched film is used because the film has high transparency and excellent gloss, so that the print on the support can be seen well and gives a clear impression. Also, because the rigidity of the film is high, the rigidity of the completed card is excellent.

Although various types of heat-adhesive resins can be considered, in the present invention, the use of a propylene-α-olefin copolymer is essential for the following reasons. That is, as a method for producing a composite film, a method in which polypropylene and a heat-adhesive resin are coextruded or laminated in the form of a raw sheet and then biaxially stretched, or a uniaxially-stretched polypropylene and extrusion-laminated with the heat-adhesive resin Then, according to any of the methods of performing biaxial stretching, the bonding strength between the biaxially stretched polypropylene and the heat-adhesive resin layer is increased. The bonding strength is highest when the heat-adhesive resin contains a copolymer containing a propylene component as a main component. Further, according to this production method, the recovered portion generated during the production can be used again as a film raw material. On the other hand, the method of coating a heat-adhesive film after producing biaxially oriented polypropylene requires a separate surface treatment and undercoat to increase the adhesive strength, and the production is complicated. For the above reasons, in the present invention, propylene-α
Requires the inclusion of an olefin copolymer.

A composite biaxially oriented polypropylene-based film using a biaxially oriented polypropylene film as a base material and a propylene-α-olefin copolymer as a heat-adhesive resin has been conventionally known. A conventionally known composite film of this type is for performing heat sealing with a heat-adhesive resin, and there is no known composite film using the copolymer for the purpose of forming a pseudo-adhesion layer by low-temperature sealing.
Conventional thermo-adhesive resins for heat sealing are 11
It is sealed at a temperature of about 0 ° C. to 130 ° C. and adheres sufficiently after the sealing so as not to peel off. Therefore, it does not adhere at a low temperature such as 90 ° C. Conversely, those having a layer that can be sealed at a low temperature, such as an ethylene-vinyl acetate copolymer or a hot melt agent, are also known, but these are permanently bonded, and are not excellent in pseudo-adhesive suitability. .

Here, an example of manufacturing a postcard for direct mail according to the present invention will be described. When the sheet is folded and quasi-adhered and transported as a postcard, the side on which the destination is described is referred to as side A, and the side which becomes the back side of the postcard during transport is referred to as side B. In addition, the inner surfaces that are pseudo-adhered when transported are referred to as C surface and D surface. A roll of printed paper is produced by printing the A and B sides on the back side of the rolled paper and printing the C and D side information on the front side. At the time of this printing, a plurality of the same ones are printed in the width direction. The surface of the printing paper (surfaces C and D) is bonded by dry lamination to the polypropylene film surface (surface on which no heat-adhesive resin layer is present) of the wound composite biaxially oriented polypropylene with an adhesive to form a composite sheet. Manufacture winding. Thereafter, the sheet is cut vertically and horizontally to produce a composite sheet (one side is AB side and the opposite side is CD side) one by one, which is approximately twice as large as the postcard. A notch as shown in (e) is provided. Incidentally, the step portion in the present invention,
This is as shown in the plan views shown in FIGS. 5 (e) and 5 (f), and a schematic sectional view passing through the step is shown in FIG. However, in the case of trouble caused by the flow of the resin exposed at the step portion when bonding with a hot roll or the like, FIG.
(E) is excellent. The composite sheet is folded in two with the heat-adhesive resin layer as the inner surface, and thermocompression-bonded by upper and lower rolls heated to about 100 to 150 ° C. to produce the secret card of the present invention.

Heat is hardly transmitted due to the heat insulating property of the paper when pressed by a hot roll. However, if the temperature of the roll is too high, the paper will curl or the thermal adhesiveness of the step (notch) A trouble occurs in which the resin flows and adheres to a roll or the like. In addition, since printing is performed, the way of transmitting heat of each part is not always uniform. For the above reasons, the thermo-adhesive resin used in the present invention needs to be able to adhere in a pseudo-adhesion state at a low temperature and in a wide temperature range, and therefore requires the following three conditions. (1) The heat-adhesive resin forming the heat-adhesive resin layer contains a copolymer of propylene and another α-olefin. (2) The heat-adhesive resin layer contains 0.05 to 0.5% by weight of an anti-blocking agent selected from organic or inorganic fine particles. (3) The composite biaxially oriented polypropylene films are bonded together with the heat-adhesive resin layer inside at a temperature of 90 ° C., a pressure of 2 kg / cm ² ,
The thermocompression bonding was performed at a temperature of 25 ° C for 1 second at a time of 0.5 seconds.
Peel strength when peeling at 80 degrees is 30 g / 25 mm or more
The range is 350 g / 25 mm.

A propylene-α-olefin copolymer is used as a main component of the heat-adhesive resin, but in order to satisfy the above conditions, the propylene component must be 80 to 95%.
% By weight. Further, in order to enhance pseudo-adhesion in a wide temperature range, it is also an effective method to further add crystalline polybutene to the copolymer. In this case, the propylene-based copolymer is 65-95.
% By weight and polybutene in the range of 5 to 35% by weight.

The anti-blocking agent selected from organic or inorganic fine particles contained in the heat-adhesive resin layer is contained in an amount of 0.05 to 0.5% by weight based on the total weight of the resin layer. As the organic fine particles, polymethyl methacrylate resin, polystyrene resin, polyamide resin, three-dimensionally crosslinked silicone particles, and the like can be used. As the inorganic particles, silica, talc, calcium carbonate and the like can be used. The particle size of the fine particles is 0.1 to 10 μm, preferably 0.1 to 10 μm.
5 to 5 μm. These particles not only prevent blocking of the film, but also when heated with a roll,
It plays an important role of preventing the resin from flowing from the exposed steps (notches).

It is preferable that the heat-adhesive resin of the present invention contains a slip agent in order to prevent various troubles during handling of the composite film. Preferably, the slip agent has a melting point of 70 ° C. or higher. As a slip agent having a melting point of 75 ° C. or more, stearamide (75
° C), oleic amide (109 ° C) and the like.
Particularly, a slip agent having a melting point of 90 ° C. or more is preferable. The slip agent may be added to the heat-adhesive resin layer, but it is better to be present in the biaxially oriented polypropylene layer.
It may be added to the polypropylene resin layer and supplied by a method of naturally transferring to the thermo-adhesive resin layer during stretching. The slip agent may be present in the composite biaxially stretched composite film in a total amount of about 50 to 500 ppm.

[0025]

According to the present invention, it is possible to form a pseudo-adhesion state in a wide temperature range without a trouble that the heat-adhesive resin of the exposed step portion adheres to a roll or the like. Was.

[0026]

[Example] <Peel strength of composite biaxially oriented polypropylene>
The heat-adhesive resin layers of the composite biaxially stretched polypropylene film are overlapped with each other, and a 10 mm × 30 mm seal bar is stabilized at a temperature of 90 ° C., pressure-bonded at a pressure of 2 kg / cm ² , and a time of 0.5 seconds, and then at room temperature. After cooling, a test piece having a width of 25 mm is cut out, and the strength at the time of peeling at a head speed of 300 mm / min is measured using Tensilon. <Example 1> Polypropylene (MFR2.
7 g / 10 min, melting point: 158 ° C.) and polybutene-1 (MFR: 4.0 g / 10 min, melting point: 104)
° C) and 10% by weight of ethylene-propylene copolymer (M
FR 6.0 g / 10 min) was used at 90 wt%, and the resin to be laminated contained 0.15 wt% of silica having an average particle size of 1.2 μm. In addition, 1
50 ppm of oleamide was added. The raw polypropylene film was uniaxially stretched 5 times in the longitudinal direction, the laminated resin was extrusion-laminated, and then stretched 9 times in the transverse direction to obtain a composite biaxially stretched polypropylene film. The total thickness is 2
0 μm, of which the thickness of the heat-adhesive resin layer was 2 μm. <Example 2> Polybutene-1 (MFR2
0.0g / 10 min), 5% by weight of ethylene-propylene-butene tertiary random copolymer (MFR 7.0 g / 1)
A composite biaxially-stretched polypropylene film was obtained in the same manner as in Example 1 except that a composition (95% by weight of the butene component was 20% in the whole of the laminated resin) in which 95% by weight was blended with 0 wt. Was. Note that silica was added in the same manner as in Example 1. <Example 3> Polybutene-1 (MFR2
0.0 g / 10 min), 35% by weight, ethylene-propylene copolymer (MFR 6.0 g / 10 min, melting point 132 ° C.)
Was obtained in the same manner as in Example 1 except that a composition in which was blended 65% by weight was obtained. Note that silica was added in the same manner as in Example 1. <Production of composite sheet> The polyurethane surface of the composite biaxially stretched polypropylene film obtained in each of the above examples and the printed surface on which information was printed on high-quality paper of 160 g / m ^{2 in} terms of size were measured using a polyurethane adhesive. And a dry laminator. The sheet was cut to a predetermined size (double the size of a postcard) to obtain a composite sheet. The composite sheets are stacked and one corner is cut out by a right-angled triangle of 5 mm × 5 mm (FIG. 5).
It was punched out with a puncher to make (e). Each of the notched composite sheets was folded in half with the surface of the heat-adhesive resin layer inward.
The paper was passed through a heating roller and subjected to thermocompression bonding to obtain a completed secret card. <Peeling strength> The peeling strength of each composite biaxially stretched polypropylene of Examples 1 to 3 was measured by the above-described measuring method, and it was 105 g / 25 mm in Example 1, 30 g / 25 mm in Example 2, and 30 g / 25 mm. 280g / 25mm for 3
Met. The peel strength of the secret card as a finished product was 70 g / 25 mm in Example 1, 60 g / 25 mm in Example 2, and 100 g / 25 mm in Example 3. Further, in each of the examples, attachment of the resin to the heat roll was not observed.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a related art relating to formation of a film and a pseudo adhesive layer.

FIG. 2 is a schematic cross-sectional view of a related art of a secret postcard.

FIG. 3 is a schematic sectional view common to the prior art and the present invention.

FIG. 4 is a schematic diagram common to the prior art and the present invention.

FIG. 5 is a schematic view of a step portion according to the present invention.

Claims (5)

[Claims] 1. A composite sheet formed by adhering a polypropylene film surface of a composite biaxially stretched polypropylene film having a heat-adhesive resin layer on one surface to a support, such that the heat-adhesive resin layer has an inner side A secret card that folds into two pieces and heat-presses them to satisfy the following conditions (1) to (4). (1) The heat-adhesive resin forming the heat-adhesive resin layer contains a copolymer of propylene and another α-olefin. (2) The heat-adhesive resin layer contains 0.05 to 0.5% by weight of an anti-blocking agent selected from organic or inorganic fine particles. (3) The composite biaxially oriented polypropylene films are bonded together with the heat-adhesive resin layer inside at a temperature of 90 ° C., a pressure of 2 kg / cm ² ,
The thermocompression bonding was performed at a temperature of 25 ° C for 1 second at a time of 0.5 seconds.
Peel strength when peeling at 80 degrees is 30 g / 25 mm or more
The range is 350 g / 25 mm. (4) The laminate has at least one near the edge of the overlap.
It has a step portion at each point. 2. The secret card according to claim 1, wherein the heat-adhesive resin layer contains a slip agent having a melting point of 70 ° C. or higher. 3. The secret card according to claim 1, wherein the heat-adhesive resin layer contains crystalline polybutene. 4. The anti-blocking agent is selected from silica, talc, calcium carbonate, and silicone particles, and is at least one type of fine particles having an average particle size of 0.1 to 10 μm. Item 4. The secret card according to any one of Items 3. 5. A postcard using the secret card according to any one of claims 1 to 4.