JPH10230964A - Packaging material with releasing function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the sealing having sufficient adhesive strength on the surface of the release agent layer by forming the release agent layer to be cracked when the packaging material is expanded on the surface of an expandable base material, and setting the area ratio of cracked parts after expansion to be in the prescribed range. SOLUTION: The packaging material is constituted by forming a release agent layer 2 on the whole surface of one side of the base material 1. The release agent is applied to the surface of the base material 1 to continuously form the release agent film approximately over the whole surface. Then, the packaging material is expanded and cracks are formed on the release agent layer 2 for discontinuity. The cracked parts enable the sealing on the surface of the release agent layer 2. In the expanded packaging material, the area ratio of the cracked parts per unit surface area of the release agent layer 2 is 10-80%. The releasing function to smoothly peel the adhesive stuff from the packaging material is simultaneously secured while the adhesive strength in sealing is kept by setting the area ratio in this range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material having a releasing function that can directly package various kinds of adhesive articles in a state where they can be peeled off from the article. The present invention relates to a packaging material having a release function capable of performing a sealing process (adhesion process).

[0002]

2. Description of the Related Art An adhesive is often used as a simple means for adding an adhesive function to various articles. For example, a sanitary napkin (hereinafter, referred to as a napkin) has a pressure-sensitive adhesive layer formed on a surface thereof to prevent displacement during use. In such a napkin, usually, after protecting the adhesive layer with release paper, the entire napkin is individually sealed and packaged with a packaging material such as a plastic film. in this case,
The opening of the packaging material after packaging the napkin is sealed by various sealing processes such as a heat sealing method and a press sealing method. On the other hand, recently, a method of directly packing a napkin with an adhesive with a packaging material having a release function on the surface thereof without protecting the adhesive layer with release paper has become mainstream. As a packaging material having a releasing function, a packaging material in which various releasing agents such as silicone are applied to the surface of a substrate made of a plastic film or the like is generally used. When a packaging material having such a release function is used, a release paper for protecting the pressure-sensitive adhesive layer is not required, so that the generation of dust when using a napkin is reduced, and it is economically advantageous.

[0003]

However, in the case of a packaging material having a release agent layer formed on the surface of the base material, if the packaging material is to be sealed, the processed surface is the surface coated with the release agent (release surface). (The surface of the mold agent layer), it was impossible to perform a sealing process having sufficient hermeticity. In addition, in order to achieve a seal process having a sufficient hermeticity, a release agent is applied to a base material so that only a portion in contact with the adhesive layer is provided,
A packaging material in which a release agent is not applied to a sealing surface has also been proposed. However, such packaging materials require the release agent to be applied in a pattern, so that the manufacturing process becomes more complicated and product yields are higher than those that do not require the release agent to be applied in a pattern. Therefore, there is a problem that the cost is high in view of the above.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a packaging material having a release function in which a release agent layer is formed on the surface of a base material, in which the sealing surface is separated. An object of the present invention is to provide a packaging material having a release function capable of performing a sealing process having a sufficient adhesive strength even on the surface of a mold agent layer.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have formed a release material layer on the surface of a stretchable base material to produce a packaging material. The release agent layer causes a crack when the packaging material is stretched, and the area ratio of the crack portion per unit surface area of the release agent layer after the packaging material is stretched is set to a specific range. As a result, the present inventors have found that the above problems can be solved, and have reached the present invention.

That is, the present invention relates to a packaging material having a release agent layer formed on the surface of a stretchable base material, wherein the release agent layer causes cracks when the packaging material is stretched. ,
The area ratio of cracks per unit surface area of the release agent layer after the packaging material is stretched is 10 to 80%. (Claim 1) The packaging material of the present invention is characterized in that the area ratio of cracks per unit surface area of the release agent layer in the seal processing portion is 10% or more. (Claim 2) The present invention further relates to a packaging material having the release function according to claim 1 or 2 used as an individual packaging material for an adhesive article. (Claim 3)

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a state before a stretching process of a packaging material having a mold release function (hereinafter, simply referred to as a packaging material) of the present invention, in which a release agent layer 2 is formed on one entire surface of a substrate 1. Make up the packaging material.

In the present invention, the release agent layer formed on the surface of the substrate is, as shown in FIG. 1, immediately after the release agent is applied to the surface of the substrate and cured or dried. A continuous release agent film is formed on almost the entire surface. Thereafter, by subjecting the packaging material having the above configuration to a stretching treatment, the release agent layer is cracked and discontinuous. In the present invention, the cracks generated in the release agent layer when the packaging material is subjected to the stretching treatment are usually defined as follows: the surface of the release agent layer of the packaging material after the stretching treatment is subjected to a scanning electron microscope (SEM) at a magnification of 100 to 100%.
It refers to a fine crack that can be confirmed by observing at 1000 times. In the portion where the release agent layer is cracked (cracked portion), the surface of the base material as the base is exposed, or the applied amount of the release agent is smaller in that portion compared to other portions. It is formed so that it becomes. In the packaging material of the present invention, it is possible to make the surface of the release agent layer a sealed surface by the cracks generated in the release agent layer. FIG. 2 shows an electron micrograph (magnification: 300 times) of the surface of the release agent layer after the packaging material of the present invention is subjected to a stretching treatment (100% stretching) when observed with a SEM. In the case of the packaging material of FIG. 2, it can be seen that countless cracks are formed in the release agent layer in a direction substantially perpendicular to the stretching direction of the packaging material.

[0009] The packaging material of the present invention needs to have a crack in the release agent layer when the packaging material is stretched as described above. From the viewpoint of compatibility of the release function, the area ratio of the crack portion per unit surface area of the release agent layer after the packaging material is stretched, which is measured by the method described below, is 10 to 80%, preferably 30 to 80%. It needs to be 70%. When the area ratio of the release agent layer crack portion is lower than 10%, the sealing strength (adhesion strength) at the time of sealing the surface of the release agent layer of the packaging material becomes insufficient, and the sealability as the packaging material becomes poor. Deteriorate. Further, when the area ratio of the cracked portion is higher than 80%, the release function is reduced, and the adhesive article cannot be peeled smoothly from the packaging material.

In the present invention, the area ratio of the crack per unit surface area of the release agent layer is determined by measuring the Si-Kα ray intensity on the surface of the release agent layer after stretching the packaging material using an electron beam microanalyzer. The color mapping image obtained is obtained by image analysis processing.

Hereinafter, the method of measuring the area ratio of cracks per unit surface area of the release agent layer in the present invention will be described in more detail. 1) The Si-Kα ray intensity on the surface of the packaging material release agent layer after the stretching treatment was measured with an electron beam microanalyzer (EPM-810,
(Manufactured by Shimadzu Corporation) to obtain a Si-Kα ray intensity color mapping image. The analysis conditions of the electron beam microanalyzer are as follows: ・ Acceleration voltage: 15 kV, sample current: 10 nA ・ Beam scan: 100 μm × 140 μm, beam diameter: 1 μm 2) Unit surface area of the obtained Si-Kα ray intensity color mapping image (100 μm × 100 μm) is subjected to image analysis processing using an image processing apparatus (Image Command 5098 Model No. TMN-1528-01, Nippon Avionics Co., Ltd.), and the area ratio of the crack is measured. At this time, the Si-Kα ray intensity was 40 cps.
Image analysis is performed using the following portions as cracks, and the portion where the Si-Kα line intensity is higher than 40 cps as a release agent layer, and the area ratio of the cracks is determined.

The packaging material of the present invention is obtained by forming a release agent layer on the surface of a base material and then stretching the packaging material.
In order to form a crack in the release agent layer, the base material itself needs to be made of a stretchable material. The stretchable base material as referred to in the present invention is a machine having a stretchability that follows the stretching process for forming a crack in the release agent layer as described above, and is sufficient as a packaging material even after the stretching process. The material, configuration, and the like are not particularly limited as long as they have a proper strength. Further, since the packaging material of the present invention is subjected to sealing after forming a crack in the release agent layer, the base material itself needs to have sealability by a heat sealing method, a press sealing method, or the like. There is.

The substrate used in the packaging material of the present invention is not particularly limited as long as it satisfies the above-mentioned characteristics. For example, a plastic film mainly composed of a polyolefin-based thermoplastic resin is used. It preferably comprises As such a polyolefin-based thermoplastic resin, for example, polyethylene, polybutene, polyhexene, polyoctene or the like can be used alone or in a mixture, but polyethylene is particularly preferably used. As the polyethylene, any one of an ultra-low density, a low density, a linear low density, a medium density, and a high density single product or a blend product can be used. Particularly preferred is a linear low density polyethylene and / or a low density polyethylene. Polyethylene content is 1
5% by weight or more, or a high-density polyethylene content of 80% by weight or less. If necessary, a material having a melting point higher than that of ultra-low-density and low-density polyethylene can be added to improve heat resistance. Such a material has a melting point of 185 ° C. or less, preferably 11
0 ° C to 180 ° C. Further, for example, an elastomer component such as a styrene-based, polyolefin-based, or polyester-based elastomer can be added, preferably in an amount of 40% by weight or less, to improve flexibility.

Here, specific examples of the polymer constituting the thermoplastic plastic film include, for example, ultra-low density,
Low density, linear low density, medium density, high density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth)
Single or two or more composite resins selected from methyl acrylate copolymer, ethylene-ethyl (meth) acrylate copolymer, polyethylene-propylene copolymer, olefin-based elastomer, styrene-based elastomer, polyisobutylene, and butyl rubber Consists of Here, as the olefin-based elastomer, ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EP
DM), styrene-based elastomers such as ethylene-propylene-based and ethylene-butene-based elastomers, such as styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), or These hydrogenated products are mentioned.

In the present invention, the substrate may have a single-layer structure as described above. For example, the substrate may be composed of at least two or more layers, and one side or both sides may have a melting point of 5 ° C. or more as compared with the layer. Having a low heat seal layer is preferable in that heat seal can be performed easily and reliably. That is, when heat-sealing, if the heat is strong in a single layer, there is a risk that holes will be formed in the base material, and it is difficult to control the heat-sealing. There is an effect that can be issued.
Examples of such a substrate include, as a heat seal layer, two or more layers composed of a low-density polyethylene (melting point: 100 ° C.) and a high-density polyethylene (melting point: 120 ° C.). In this case, the release agent layer is provided on the low-density polyethylene side which is the heat seal layer. Further, as the substrate of the present invention, a laminate of a thermoplastic film, a nonwoven fabric, and a woven fabric is also preferable.

In the present invention, by blending the above-mentioned polymer, the surface of the base material can be roughened like a satin surface or an embossed surface. In addition, there is an effect that the running performance of the line can be improved by reducing the dynamic friction coefficient.
By such a blend, in the case of those having poor compatibility, they are mixed so as to be separated from each other due to a difference in interfacial tension at the time of dissolution, and therefore, in the surface state, uniform mixing cannot be obtained, and the surface becomes rough without being smooth. Therefore, the surface is considered to be a matte surface or an embossed surface. The roughness of this surface is
Usually, it is 0.2 to 30 μm, preferably 2 to 5 μm, but when embossing or satin is formed by a roll or the like described later, it is preferable that the thickness be within １ ／ of the film. In addition, by blending polymers having different properties, it becomes possible to blend such polymers having only the merits of each other, and it is possible to obtain a polymer having a new function, for example, a function having a balance between softness and good stiffness. There is. Also, by blending a relatively soft polymer or elastomer as described above, the peeling sound can be reduced when the packaging material is peeled from the adhesive article, and there is also an effect that the use is not noticed by others.

As a more aggressive method for forming a matte or embossed surface, besides the above-described polymer blend method,
It can also be formed by a roll surface that comes into contact with the film at the time of its production, for example, after T-die extrusion. When forming an embossed surface in the present invention, the latter method is more preferable.

Further, as the substrate of the present invention, at least one surface of the multilayer thermoplastic film composed of at least two layers may be a matte or embossed surface made of the polymer blend. By making such a multilayer, it is possible to composite the properties of the polymer film of each layer, like a polymer blend,
There is an advantage that it is possible to add a new function, for example, the function addition such as the improvement of the heat sealing property and the tear strength and the good texture.

As another specific embodiment of the substrate of the present invention,
For example, at least one surface of the thermoplastic film may be a matte or embossed surface having a surface roughness (Ra) of, for example, about 以下 or less of the film thickness, and a release agent layer may be provided on the other surface. The structure has effects such as softness when touched, high-grade appearance, and improvement in line running performance (reduction in dynamic friction coefficient). In another embodiment, at least one surface of the thermoplastic film is a matte or embossed surface having a surface roughness (Ra) of 1/2 or less of the film thickness, and a release agent layer is formed on the surface. It can also be provided.

In this case, the coefficient of static friction of the release surface or the embossed surface of the release surface is less than 1.5, preferably 0.1.
2 to 1.0, the coefficient of kinetic friction is less than 1.2, preferably 0.1.
It is desirably 1 to 1.0. By setting it in this range, the running property on the line can be improved, and there is an effect that wrinkles, meandering, cutting and the like hardly occur at the time of contact with the roll.

The thickness of the substrate is not particularly limited, and is usually 1 m
m or less, but 10 in terms of softness and flexibility
To 50 μm, particularly preferably 20 to 40 μm.

In the present invention, a certain degree of strength is required from the viewpoint of the transfer of the base material on the line, and the tensile strength of the base material in the MD direction is usually 300 gf / 10 mm or more, particularly 3 gf / mm.
100-1000gf / 10mm, TD direction tensile strength is 2
It is preferably at least 00 gf / 10 mm, particularly preferably 300 to 1000 gf / 10 mm.

In the present invention, as described above, the material constituting the release agent layer causes a crack in the release agent layer when the packaging material is stretched, so that the area ratio of the crack portion falls within a specific range. The material is not particularly limited as long as it can be adjusted, and a material having a releasing function satisfying such characteristics can be appropriately selected and used.

As a material constituting the release agent layer, for example, a silicone release agent such as a thermosetting type, an ultraviolet curing type, an electron beam curing type, a fluorine type release agent, or a long-chain alkyl type release agent ( In general, a long-chain alkyl component such as a long-chain alkyl isocyanate is reacted with a polymer of a long-chain alkyl acrylate having 12 or more carbon atoms, a copolymer of a long-chain alkyl acrylate with another vinyl monomer, or polyvinyl alcohol. And the like, and those which satisfy the above-mentioned characteristics can be appropriately selected from known release agents such as a reactant obtained by the above method. In particular, when the substrate is formed of a thermoplastic plastic film, it is preferable to use an ultraviolet-curable or electron beam-curable silicone release agent that does not require heat treatment when forming the release agent layer.

The thickness of the release agent layer formed on the surface of the substrate is not particularly limited, but is usually 0.05 to 4.0.
μm is preferable, and 0.3 to 1.5 μm is more preferable.

In the present invention, the release agent can be applied to either one side or both sides of the substrate. Further, the release agent can be applied to the entire surface of the substrate or only to a part thereof.

The method for applying the release agent to the substrate is not particularly limited, and an appropriate coating apparatus such as a multi-roll type or offset / gravure roll type can be used.

In the packaging material of the present invention, a release agent is applied to the surface of the substrate, and dried or subjected to various curing treatments (for example, irradiation with ultraviolet rays or electron beams) to form a release agent layer. Thereafter, a crack is formed in the release agent layer by stretching the packaging material. Such a stretching method is not particularly limited, and a known stretching method such as a tenter stretching method and a roll stretching method, which are used for a normal plastic film stretching process, may be appropriately selected and used. it can. The stretching conditions are also not particularly limited, and are stretched according to the type of the base material such that the area ratio of the release agent layer cracks formed by the stretching process satisfies the specific range defined in the present invention. Processing conditions can be set.

As described above, the packaging material of the present invention can be stretched in advance before the sealing process.
For example, after packaging an adhesive article with a packaging material that has not been stretched, a stretching process can be performed only on the sealed portion to form a crack in the release agent layer. At this time, the area ratio of the crack portion per unit surface area of the release agent layer in the seal processing portion is 1
It must be 0% or more, preferably 15% to 95%. If the area ratio of the crack portion per unit surface area of the release agent layer in the seal processing portion is lower than 10%, the adhesive strength of the seal processing portion becomes insufficient, and the sealability as a packaging material deteriorates. Here, the area ratio of the crack portion per unit surface area of the release agent layer in the seal processing portion, the release agent layer surface Si-Kα line intensity of the seal processing portion was measured under the same conditions as above, The obtained color mapping image was obtained by performing image analysis processing under the same conditions as described above.

In the case where a crack is formed in the release agent layer of the sealed portion, a stretching process for forming the crack may be performed during the sealing process. That is, the packaging material of the present invention
An external force applied to the packaging material during the sealing process can be used to cause a crack in the release agent layer. The sealing method in this case is not particularly limited, but, for example, between two rolls in contact at different rotational speeds (at least one roll is a heating roll for heat sealing). Through the sealing portion of the packaging material (the portion where the packaging materials overlap), and the stretching and sealing of the packaging material can be performed simultaneously. In this case, a crack can be generated in the release agent layer of the packaging material by utilizing the shearing force between the rolls. Further, by using a heat sealing machine having a heat sealing bar having a projection (projection) formed on the surface, stretching of the packaging material and sealing can be performed simultaneously. In this case, at the time of the heat sealing process, the packaging material is stretched at the convex portion of the heat seal bar, so that the release agent layer of the packaging material can be cracked. In addition to the above, when an external force for causing a crack in the release agent layer can be applied to the packaging material during the sealing process, the stretching process can be performed simultaneously with the sealing process. Therefore, in this case, it is not necessary to stretch the packaging material in advance, so that the productivity of the sealing process can be further improved.

FIG. 3 is an electron micrograph (FIG. 3.a: FIG. 3.a) of the packaging material of the present invention after heat sealing, peeling off the sealed portion, and observing the surface of the release agent layer by SEM.
Magnification 100 times, FIG. 3.b: magnification 300 times). In the case of the packaging material shown in FIG. 3, the packaging material undergoes the same operation as stretching when the heat sealing process is performed (the packaging material is stretched), and countless cracks are formed only in the release agent layer of the seal processing portion. You can see that.

The packaging material of the present invention can be provided in a state where the packaging material has been stretched in advance, that is, in a state where a crack can be formed in the release agent layer so that sealing can be performed. After providing the packaging material in a state where stretching is not performed, and after packaging the adhesive article with such packaging material,
The stretching process may be performed during the sealing process to form a crack in the release agent layer.

FIG. 4 is an enlarged sectional view schematically showing a case where the packaging material of the present invention is used as an individual packaging material (individual packaging sheet) for a napkin with an adhesive. After the napkin B is packaged with the packaging material A that has not been subjected to the stretching treatment, the napkin B is subjected to stretching treatment only to the seal processing portion C composed of the surfaces of the release agent layers of the packaging material, and the cracking portion is formed in the release agent layer. Is formed and sealing is performed.

In the present invention, the method of sealing the packaging material after the stretching treatment is not particularly limited, and for example, a heat sealing (thermal bonding) method or a press sealing method can be used. The packaging material of the present invention,
The surface of the release agent layer on which the cracks are formed is used as a seal processing surface. In such cracks, the base material layer serving as a base is exposed or the amount of the release agent applied is small, so that even if the surface of the release agent layer is used as a sealing surface, there is sufficient sealing strength (adhesion). Strength). In the present invention, the sealing surface of the packaging material may be formed between the surfaces of the release agent layers of the packaging material, or the surface of the release agent layer and the surface of the base material (for example, when the release agent layer is formed). (The surface opposite to the surface that has been set).

In the present invention, from the viewpoint of maintaining the hermeticity of the contents after the sealing process, the sealing strength indicating the adhesive strength of the sealing portion is 2 g / 25 mm or more, and the upper limit is preferably the breaking strength of the base material or less. Means that the seal strength is 5g / 25mm ~
Desirably, it is 1000 g / 25 mm. Here, the breaking strength of the base material refers to a strength in a case where the base material is broken without being peeled off from the seal portion when measuring the seal strength, and refers to a state where the adhesive strength of the seal portion is very strong. If the sealing strength is less than 2 g / 25 mm, the sealed portion tends to peel off easily, and the hermeticity of the contents tends to deteriorate.

As the packaging material of the present invention, besides being used as an individual packaging material of the sanitary napkin with an adhesive shown in FIG. It can be used as a packaging material for packaging directly without using.

[0037]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

(Reference Example 1) 100 parts by weight of a cationic polymerization type ultraviolet curable silicone release agent (TPR6500, manufactured by Toshiba Silicone Co., Ltd.) and a photoinitiator (UV) were coated on one entire surface of a low-density polyethylene film having a thickness of 30 μm. −93
10C, manufactured by Toshiba Silicone Co., Ltd.) A release agent adjusted to 2 parts by weight was applied to a thickness of 0.7 μm, and UV was applied.
Light was applied to form a release agent layer to prepare a packaging material before the stretching treatment.

Reference Example 2 A release agent prepared with 100 parts by weight of an addition-reaction-type thermosetting silicone release agent and 2 parts by weight of a platinum-based curing catalyst was applied to the entire surface of one side of a low-density polyethylene film having a thickness of 30 μm. The coating material was applied so as to have a thickness of 0.3 μm, and a release agent layer was formed in a hot air drier to prepare a packaging material before the stretching treatment.

Example 1 The packaging material (25 mm width × 100 mm length) obtained in Reference Example 1 before the stretching treatment was stretched 100% in the flow direction (MD direction) of the substrate. At this time, the stretching process is performed using a tensile tester at a tensile speed of 50 mm.
/ Min. After the stretching treatment, when the surface of the release agent layer was observed with an SEM (magnification: 300 times), it was observed that cracks were generated in the release agent layer. The area ratio of the cracks per unit surface area of the release agent layer after the stretching treatment was 15%.

(Example 2) The packaging material (25 mm width x 100 mm length) obtained in Reference Example 1 before the stretching treatment was processed in the same manner as in Example 1 in the flow direction (MD direction) of the substrate. To 150%. After the stretching treatment, when the surface of the release agent layer was observed with an SEM (magnification: 300 times), it was observed that cracks were generated in the release agent layer. The area ratio of the cracks per unit surface area of the release agent layer after the stretching treatment was 50%.

Example 3 The packaging material (25 mm width × 100 mm length) obtained in Reference Example 1 before the stretching treatment was processed in the same manner as in Example 1 in the flow direction (MD direction) of the substrate. To 200%. After the stretching treatment, when the surface of the release agent layer was observed with an SEM (magnification: 300 times), it was observed that cracks were generated in the release agent layer. The area ratio of cracks per unit surface area of the release agent layer after the stretching treatment was 75%.

Example 4 A heat-sealing machine having a heat-sealing bar having a surface on which the release agent layers of the packaging material obtained in Reference Example 1 before the stretching treatment were overlapped to form projections on the surface. Heat seal processing. In the case of this embodiment, at the time of heat seal processing, the packaging material is stretched at the convex portion of the heat seal bar, and a crack is generated in the release agent layer at that portion, so that heat seal having sufficient sealing strength for practical use is performed. Was done. After the heat sealing, the sealed portion of the packaging material was peeled off, and the area ratio of the cracked portion per unit surface area of the release agent layer in the sealed portion of one of the packaging materials was measured. As a result, the area ratio was 53%.

Comparative Example 1 The packaging material before the stretching treatment obtained in Reference Example 1 was used without stretching.
At this time, the area ratio of cracks per unit surface area of the release agent layer was 0.
%Met.

(Comparative Example 2) The packaging material (25 mm width x 100 mm length) obtained in Reference Example 1 before the stretching treatment was processed in the same manner as in Example 1 in the flow direction (MD direction) of the substrate. To 50%. After the stretching treatment, the surface of the release agent layer is
When observed by EM (magnification: 300 times), it was observed that cracks were generated in the release agent layer. The area ratio of cracks per unit surface area of the release agent layer after stretching was 5%.
%Met.

(Comparative Example 3) The packaging material (25 mm width x 100 mm length) obtained in Reference Example 1 before the stretching treatment was processed in the same manner as in Example 1 in the flow direction (MD direction) of the substrate. To 300%. After the stretching treatment, when the surface of the release agent layer was observed with an SEM (magnification: 300 times), it was observed that cracks were generated in the release agent layer. The area ratio of the cracks per unit surface area of the release agent layer after the stretching treatment was 85%.

(Comparative Example 4) The packaging material (25 mm width x 100 mm length) obtained in Reference Example 2 before the stretching treatment was processed in the same manner as in Example 1 in the flow direction (MD direction) of the substrate. To 100%. After the stretching treatment, when the surface of the release agent layer was observed with an SEM (magnification: 300 times), no crack was generated in any part of the release agent layer.

(Comparative Example 5) The surfaces of the release agent layers of the packaging material obtained in Reference Example 2 before the stretching treatment were overlapped with each other, and heat sealing was performed in the same manner as in Example 4. No heat sealing was performed.

The samples obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated as follows.

[Heat Seal Strength] The surface of the release agent layer of each sample was superimposed on each other, and a heat seal machine (TP-701SH) was used.
Using EAT SEAL TESTER and TESTER SANGYO CO. LTD), heat sealing was performed under the following conditions. After the heat sealing, the heat sealing strength was measured at a tensile speed of 300 mm / min (T-peel test) using a tensile tester.
The surface shape of the heat seal bar of the heat sealer used in this evaluation was flat.・ Heat sealing temperature: 130 ° C. ・ Crimping time: 2 seconds ・ Crimping condition: 4 kg / cm 2 ・ Crimping area: 10 mm × 30 mm

[Peeling Force] An adhesive tape (trade name: F-140BK, manufactured by Nitto Denko Corporation) was adhered to the surface of the release agent layer of the sample (10 mm width) by reciprocating a 2 kg roller once.
After leaving at room temperature for 30 minutes, the peeling force when peeling the adhesive tape from the sample (packaging material) side was measured at a tensile speed of 300 mm / min (180 ° peeling) using a tensile tester.

Table 1 shows the results.

[0053]

[Table 1]

As is clear from Table 1, the packaging materials of Examples 1 to 3 have the crack area ratio per unit surface area of the release agent layer formed by the stretching treatment within the specific range specified in the present invention. , So that it has sufficient heat sealing strength even if the sealing surface is between the release agent layer surfaces, and that the release agent layer also has releasability from the adhesive tape. I understand. On the other hand, in the packaging material of Comparative Example 3, since the area ratio of the crack portion exceeds 80% specified in the present invention, the releasability from the adhesive tape is reduced.
Further, in the packaging materials of Comparative Examples 1, 2, and 4, no cracks were formed in the release agent layer, or even if cracks were formed, the area ratio was more than 10% specified in the present invention. It can be seen that heat sealing could not be performed or the sealing strength was extremely low due to the low temperature.

[0055]

According to the present invention, the packaging material having a releasing function according to the present invention can perform a sealing process having a sufficient adhesive strength even when the surface of the releasing agent layer is used as a sealing surface. At the same time, the release agent layer can maintain sufficient releasability from various adhesive articles. Therefore, by using the packaging material of the present invention,
It is possible to produce a packaging material having a release function without going through a complicated manufacturing process that has been conventionally used such that a release agent is not applied only to the seal processing portion. Furthermore, in the packaging material of the present invention, when the same external force as in the stretching process can be applied to the packaging material during the sealing process, the step of forming a crack in the release agent layer is performed simultaneously with the sealing process. Therefore, the packaging material does not need to be stretched in advance, and the workability of the sealing process can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a packaging material having a releasing function according to the present invention.

FIG. 2 is an electron micrograph (magnification: 300 times) of the surface of a release agent layer observed with an SEM after the packaging material having a release function of the present invention is stretched.

FIG. 3 shows the surface of the release agent layer in the sealed portion after heat-sealing the packaging material having a release function of the present invention.
M when observed at M (a: magnification of 10
0 times, b: 300 times magnification).

FIG. 4 is an enlarged sectional view schematically showing a case where the packaging material having a releasing function of the present invention is used as an individual packaging material for a sanitary napkin with an adhesive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Release agent layer 3 Adhesive layer A Packaging material B Napkin C Seal processing part

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 83:00 B29L 9:00

Claims (4)

[Claims] 1. A packaging material having a release agent layer formed on a surface of a stretchable base material, wherein the release agent layer causes a crack when the packaging material is stretched. Wherein the area ratio of the cracks per unit surface area of the release agent layer after stretching is 10 to 80%. 2. A packaging material having a release agent layer formed on the surface of a stretchable base material, wherein the area ratio of cracks per unit surface area of the release agent layer in a sealing portion of the packaging material is 1%.
A packaging material having a release function of 0% or more. 3. The packaging material having a release function according to claim 1, which is used as an individual packaging material for an adhesive article. 4. The packaging material having a release function according to claim 1, which is used as an individual packaging material for a sanitary napkin.