JPH106452A - Thermocompression bondable and repeelable laminated sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a laminated sheet which shows a stable peeling strength, i.e., a wide range of temperatures at which thermocompression bonding is possible, even if the temperatures for thermocompression bonding slightly fluctuates, in the manufacture of the laminated sheet which can be thermocompression bonded and repeeled. SOLUTION: This thermocompression bondable and repeelable laminated sheet consists of a base material layer, a biaxially stretched polypropylene film layer and a thermocompression bondable resin layer stacked in that order, and the thermocompression bondable resin layer comprises a copolymer of propylene and α olefine and crystalline polybutene. The copolymer of propylene and α olefin is preferably a copolymer of ethylene and propylene or a copolymer of ethylene, propylene and butene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated sheet which can be folded and thermocompressed, and which can be re-peeled.

2. Description of the Related Art A thermocompression-bondable and re-peelable sheet as in the present invention is used, for example, in a post-peelable postcard.
When used as a postcard, other people cannot see the information during communication, that is, there is a function of protecting privacy, and in the case of, for example, two-fold, the area where information can be written is doubled. There is. Conventionally known techniques for such a sheet include Japanese Utility Model Laid-Open No.
JP-A-147069, JP-A-2-55197, JP-A-3-124885, JP-A 5-1
No. 1570 and the like.

[0002] Japanese Patent Application Laid-Open No. H11-163873 discloses a technique of laminating a plurality of sheets of paper having substantially the same area via a peelable adhesive layer. However, there is a troublesome process of bonding two separate objects after printing. Discloses a configuration in which paper and a transparent resin film are attached to each other, and the film is folded inward with the film as an inner surface. Although this method is more advanced than the above, it has a drawback that if the pressure is too strong, the peeled surface will not be obtained or the paper and the film will peel off because the resin film is a single layer.

[0003] discloses a configuration in which a stretched polypropylene having a heat seal layer is bonded to a base material such as paper. As the heat seal layer, polyethylene is exemplified, and some of the above disadvantages have been solved.

[0004]

As exemplified above, when polyethylene is used as the thermocompression bonding resin layer, it is difficult to control the peeling force, and it is necessary to prevent the peeling during transportation. Therefore, if an attempt is made to provide a certain degree of bonding strength, the bonding will be strong. That is, the selection range of the thermocompression bonding temperature is extremely narrow. In addition, a phenomenon occurs in which a layer is peeled between the polyethylene and the polypropylene, which causes a problem that the appearance after the peeling is different between the left and right. An object of the present invention is to provide a laminated sheet which is relatively easy to manufacture, can be thermocompression-bonded at a relatively low temperature and in a wide temperature range, and can easily adjust the peeling force.

[0005]

The present invention employs the following configuration in order to solve the above-mentioned problems. That is, the first of the present invention
The invention discloses that "a base material layer, a biaxially oriented polypropylene film layer, and a thermocompression bonding resin layer are laminated in this order, and the thermocompression bonding resin layer is made of a copolymer of propylene and α-olefin and crystalline polybutene. And a thermocompression-bondable laminated sheet. " Further, the second invention of the present invention is characterized in that, in the first invention, the copolymer of propylene and α-olefin is an ethylene-propylene copolymer or an ethylene-propylene-butene copolymer. It is a laminated sheet.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the substrate layer of the present invention, paper, paperboard, synthetic paper and the like can be used. The biaxially oriented polypropylene film layer is preferably a polypropylene homopolymer.
Alternatively, a copolymer containing propylene as a main component may be used, but any copolymer having almost the same strength, transparency, and stiffness as polypropylene may be used. Biaxial stretching refers to a film stretched simultaneously or sequentially in both the machine and transverse directions. The stretching ratio is at least 3 × 3 or more, preferably 3 to 6 times in the machine direction and 5 to 9 times in the transverse direction.
A transparent film of about μ is desirable.

[0007] The thermocompression-bondable resin layer laminated on the polypropylene film must be a mixture of a copolymer of propylene and α-olefin and crystalline polybutene. As the α-olefin, ethylene, butene, butadiene, pentene, and the like can be used, and a terpolymer of these two and propylene may be used. For example, an ethylene / propylene copolymer and an ethylene / propylene / butene copolymer are preferred. Propylene accounts for 8% of the copolymer.
The content is preferably from 0 to 95% by weight. Crystalline polybutene refers to a homopolymer of polybutene-1.

The mixing ratio of the copolymer and the crystalline polybutene is 65 to 95% by weight for the copolymer and 5 for the polybutene.
A range of ~ 35% by weight is preferred. 5 crystalline polybutene
%, The temperature for thermocompression bonding increases, and the peeling force becomes too strong. In addition, 35% of crystalline polybutene
When the temperature exceeds the above range, the temperature for thermo-compression bonding is lowered, but the range of the compression temperature at which an appropriate peel strength is obtained is narrowed. Further, as for the thermocompression bonding layer, when the lamination thickness is large, when the thermocompression bonding is performed, the peeling force is increased, so that the peeling feeling is deteriorated. The thickness of the layer is preferably from 0.2μ to 5μ.

In the laminated sheet of the present invention, the most common method is to bond the polypropylene surface of the biaxially stretched polypropylene film on which the thermocompression bonding resin layer is laminated to the base material layer with an adhesive. The thermocompression-bondable resin layer can be supplied as a composite film by, for example, a continuous biaxial stretching method of polypropylene and a method of laminating and stretching a thermocompression-bondable resin after unstretched raw fabric or uniaxial stretching. In addition, it is natural that printing is performed on one side or both sides of the base material layer, if necessary, before laminating the composite film on the base material layer.

The sheet of the present invention is used, for example, by folding it into two with the thermocompression-bondable resin layer as the inner surface and thermocompression bonding. 3
Folding and four-folding are also possible, but even in that case, at least the surface to be thermocompression bonded is the thermocompression-bondable resin layer.

[0011]

EXAMPLES In this example, each evaluation method was evaluated by the following methods. In this example, M shown as a physical property value of the resin
FR indicates a melt flow ratio, and Tmp indicates a melting point. (1) Heat sealing strength Laminated surfaces of the films are superimposed on each other and 2k at each temperature
After heat-sealing at a pressure of g / cm ² for 1 second with a seal bar having a width of 10 mm, a test piece of 25 mm was cut out, and the strength when the heat-sealed portion was peeled off at a crosshead speed of 300 mm / min was shown.

(2) Peel strength A film obtained by laminating (bonding) a pressure-bonded film and a support, that is, a paper obtained by thermocompression bonding the film laminated surfaces of a support composite sheet to a test piece having a width of 25 mm is cut into a test piece having a width of 300 mm. The strength when the pressure-bonded surface was peeled off at / min.

(3) Feeling of peeling The easiness of peeling (peeling feeling including sound) when the paper whose thermocompression-bonded surfaces are thermocompression-bonded by hand is peeled off is shown.

Example 1 Polypropylene (MFR / 2.7 g / 10 min, Tmp 158 ° C.) was used as the base material layer, and polybutene-1 (MFR / 4.0 g) was used as the resin to be laminated.
/ 10 min, Tmp 104 ° C.)
Propylene copolymer (MFR / 6.0 g / 10 min, Tm
p132 ° C.) of 90% by weight.
The composite biaxially stretched polypropylene film having a thickness of 20 μ was obtained by successively biaxially stretching. Further, a film obtained by subjecting the non-laminated surface to a corona treatment was laminated (bonded) on a paper having a basis weight of 200 g / m ² to obtain a pressure-bonded paper. Next, the pressure-bonded paper was heat-sealed at a processing temperature of 90 ° C. The heat sealing strength of the film itself before bonding and the peel strength and peeling feeling of the heat-sealed pressure-bonded paper were measured, and the results are shown in Table 1.

Example 2 Polybutene was used as the resin to be laminated.
1 (MFR / 20.0 g / 10 min) in 5% by weight of an ethylene-propylene-butene random copolymer (MFR /
A pressure-bonded paper was obtained in the same manner as in Example 1, except that a composition in which 7.0 g / 10 minutes and Tmp of 132 ° C. were blended in an amount of 95% by weight (the weight fraction of butene was 20% based on lamiresin). Next, the pressure-bonded paper was heat-sealed at a processing temperature of 90 ° C. The heat sealing strength of the film itself before bonding and the peel strength and peeling feeling of the heat-sealed pressure-bonded paper were measured, and the results are shown in Table 1.

Example 3 Polybutene was used as the resin to be laminated.
1 (MFR / 20.0 g / 10 min) was 35% by weight of an ethylene-propylene copolymer (MFR / 6.0 g / 10 min).
(Tmp, 132 ° C.) was obtained in the same manner as in Example 1 except that a composition in which 65% by weight of T.P. Next, the pressure-bonded paper was heat-sealed at a processing temperature of 90 ° C. Measure the heat-sealing strength of the film itself before bonding and the peel strength and peel feeling of the heat-sealed pressure-bonded paper,
Table 1 shows the results.

Comparative Example 1 An ethylene-propylene copolymer (MFR / 6.0 g / 10 min, Tmp
A pressure-bonded paper was obtained in the same manner as in Example 1 except that the temperature was 132 ° C.). Next, the pressure-bonded paper was heat-sealed at a processing temperature of 120 ° C. The heat sealing strength of the film itself before bonding and the peel strength and peeling feeling of the heat-sealed pressure-bonded paper were measured, and the results are shown in Table 1. FIG. 1 shows the heat sealing temperature and the heat sealing strength of the example and the comparative example.

[0018]

[Table 1]

[0019]

FIG.

[0020]

According to the present invention, the temperature range in which thermocompression bonding can be performed is greatly expanded, and the quality (peel strength) of the product is stabilized. Therefore, the working efficiency of thermocompression bonding increases. In addition, at the time of peeling, it peels with an appropriate resistance, and furthermore, it peels cleanly between the thermocompression bonding resin layers, so that the appearance after peeling is good,
The printed content is clearly visible.

Claims (2)

[Claims] 1. A base material layer, a biaxially stretched polypropylene film layer, and a thermocompression bonding resin layer are laminated in this order, and the thermocompression bonding resin layer is made of a copolymer of propylene and α-olefin and crystalline polybutene. A laminated sheet capable of thermocompression bonding. 2. The laminated sheet according to claim 1, wherein the copolymer of propylene and α-olefin is an ethylene / propylene copolymer or an ethylene / propylene / butene copolymer.