JP2023170081A - Film, tape and adhesive patch using the same - Google Patents

Abstract

To provide a film made of, for example, a hard plastic material having heat resistance and gas barrier properties, and capable of having both stretchability and breakage resistance, and a tape and an adhesive patch using the same.SOLUTION: A film with a convex and concave shape in which a convex portion and a concave portion are repeatedly arranged on both a front surface and a bottom surface, a relation among a height difference h between a concave surface and a convex surface, an average thickness t of the film, and a corner shape portion r satisfies t<r<h, a thickness of a thinnest portion of the film is -20% or more and 0% or less than the average thickness, and a breaking strength measured according to JISK7127:1999 is 5 N/15 mm or more and 30 N/15 mm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a film, a tape and a patch using the same.

In general, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and capable of mass production, and are used for a variety of purposes. Its uses are wide-ranging, such as packaging materials for foodstuffs, medicines, etc., tapes, optical films, protective films, and construction materials. Specific materials include, for example, thermoplastic resins such as polyethylene, polypropylene, polystyrene, polycarbonate, polyamide, polyethylene terephthalate, and polybutylene terephthalate, and thermosetting resins such as epoxy resins, polyurethane, and polyimide.

The materials used for plastic films each have unique properties such as mechanical properties, thermal properties, and chemical properties, and appropriate materials are selected depending on the purpose.

However, it may be difficult to satisfy multiple characteristics simultaneously. For example, it is difficult to satisfy heat resistance, gas barrier properties, and elasticity at the same time based on material properties alone. This is because materials having heat resistance and gas barrier properties are limited to relatively hard materials.

Therefore, as a technique for imparting elasticity to hard materials that have heat resistance and gas barrier properties, as shown in Patent Document 1 and Patent Document 2, a structure such as fine creases is created in the film. Attempts are being made to achieve both of the contradictory characteristics described above.

JP2019-89321A Japanese Patent Application Publication No. 2020-185084

However, a film such as that disclosed in Patent Document 1 has a problem in that its breaking strength tends to be lower than that of a general smooth film. This is because stress during expansion and contraction tends to concentrate at the corners of the folds, making it easier to break starting from there.

On the other hand, Patent Document 2 proposes to suppress stress concentration by rounding the corners of the fold in order to suppress the above-mentioned decrease in breaking strength. However, factors that lead to a decrease in breaking strength include not only stress concentration at the corners but also stress concentration due to thickness differences inherent in the film. In other words, in order to produce a film with creases as described above, a film that originally has a uniform thickness is fitted into a mold to create an uneven structure, which tends to cause thickness differences due to the sloped portion being stretched during the formation of the structure. In some cases, the reduction in breaking strength could not be suppressed only by rounding the corners r.

As a result, for example, when used as a base material for tapes or patches, or when used as a stretchable functional film with a functional layer such as a gas barrier layer or conductive layer on one or both sides, it is difficult to attach it to an object. This causes problems such as the film being torn during handling or peeling.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a film that is made difficult to break while imparting elasticity to a resin material, and a tape and a patch using the same.

In order to solve the above problems, one of the typical films of the present invention is
The film has an uneven shape on both the front and back surfaces, the uneven shape is a repeating array of protrusions and depressions, and the adjacent protrusions and depressions share a sloped part arranged between them. , the back surface has an uneven shape that follows the uneven shape of the front surface,
A film in which the height difference h between the surface of the concave portion and the surface of the convex portion is greater than the average thickness t of the film,
In the cross section of the film, the roundness r of the connecting part connecting the top of the convex part or the bottom of the concave part and the slope part, or the cross-sectional center line of the top of the convex part or the bottom of the concave part is approximated by a part of a circle. If possible, the radius r of the circle is larger than the average thickness t of the film and smaller than the height difference h,
The thickness of the thinnest part of the film is -20% or more and 0% or less of the average thickness t of the film,
This is achieved when the breaking strength measured in accordance with JIS K7127:1999 is 5 N/15 mm or more and 30 N/15 mm when pulled in the direction in which the convex portions and the concave portions are repeatedly arranged.

According to the present invention, it is possible to provide a film that is made difficult to break while imparting elasticity to a resin material, and a tape and a patch using the same.
Problems, configurations, and effects other than those described above will be made clear by the following description of the embodiments.

FIG. 1 is a cross-sectional view showing an example of the film of this embodiment. FIG. 2 is a sectional view showing an example of the film of this embodiment. FIG. 3 is a perspective view showing an example of the extending direction of the uneven shape in the film of this embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
Note that each figure is a schematic diagram, and the size, shape, etc. of each part are appropriately exaggerated or simplified to facilitate understanding. Further, to simplify the explanation, corresponding parts in each figure are given the same reference numerals.

As shown in FIG. 1, the film 1 of this embodiment has a concave and convex shape in which convex portions 2 and concave portions 3 are repeatedly formed with a slope portion 4 interposed therebetween. Further, the unevenness on the back surface of the film 1 is formed in an uneven shape so as to follow the unevenness on the front surface, and the film 1 has a wavy shape when viewed from above.

Further, as shown in FIG. 3, the film 1 has convex portions 2 and concave portions 3 repeatedly formed along the extending direction (left-right direction in the figure). The convex portions 2 and the concave portions 3 extend in a direction intersecting (in this case perpendicular to) the extending direction of the film 1 at a uniform height.

The uneven cross-sectional shape of the film 1 is a trapezoidal shape in which the protrusions 2 and the recesses 3 have flat parts at the top 2a and the bottom 3a, as shown in FIG. The top portion 2a and the bottom portion 3a have an arcuate shape with no flat portions.

When the film 1 has a trapezoidal shape as shown in FIG. The cross section of a corner (connection) 5 connecting the top 2a of the portion 2 and the bottom 3a of the recess 3 with the slope 4 has a roundness r. At this time, the roundness r is determined by the cross-sectional center line (between the front and back surfaces of the film) in the cross section of the relevant location (the cross section cut along a plane perpendicular to the direction in which the convex portions 2 or concave portions 3 extend (direction perpendicular to the paper surface in FIGS. 1 and 2)). When a line connecting intermediate points is approximated by a part of a circle, it is defined as being calculated by the radius of the circle.
On the other hand, when the film 1 has an arc shape as shown in FIG. 2, the cross section of the entire top 2a or the entire bottom 3a has a roundness r. In other words, when the cross-sectional center line of the top 2a of the convex portion 2 or the bottom 3a of the concave portion 3 can be approximated by a part of a circle, the radius of the circle is defined as the roundness r.

The film 1 has thick parts and thin parts in the film 1 due to the method for producing the uneven shape described below, and the average thickness of these parts is defined as t.

The film 1 has a roundness r (μm) and an average thickness t (μm) of the following with respect to the height difference h (μm), which is the distance between the highest position of the convex part 2 and the lowest position of the concave part 3 on the front surface (back side). The following relationship is satisfied, and the thickness of the thinnest part of the film is -20% or more with respect to the average thickness t.
Formula (1): t < r < h

If the height difference h is small relative to the average thickness t (t>h), the uneven shape will not have a wavy shape, and the effect of imparting stretchability to the film 1 will not be exhibited. Therefore, the height difference h needs to be relatively larger than the average thickness t.

Furthermore, if the roundness r is equal to or less than the average thickness t (r≦t), the stress concentration at the corners becomes large during tension, resulting in a significant decrease in the breaking strength.

Furthermore, if the height difference h is less than or equal to the roundness r (h≦r), the film 1 as a whole loses its unevenness and becomes shaped like a flat film, which weakens the elasticity effect. Therefore, it is easier to obtain the elasticity effect by making the height difference h relatively larger than the roundness r.

Further, it is preferable that the difference in thickness within the film 1 is small, and the thickness of the thinnest part within the film 1 must be in the range of -20% or more and 0% or less with respect to the average thickness t. be. If the thickness of the thinnest part deviates from the above range, the stress concentration on the thin film portion during tension will increase, resulting in a decrease in breaking strength.

Further, the film 1 needs to have a breaking strength of 5 N/15 mm or more and 30 N/15 mm or less when pulled in a direction in which the uneven shape is repeated, as measured in accordance with JIS K7127:1999. If the breaking strength is lower than 5 N/15 mm, products using the film 1, such as tapes and adhesive patches, tend to tear during use and become difficult to handle. Moreover, when the breaking strength exceeds 30 N/15 mm, it becomes difficult for the film to satisfy formula (1), and the stretching effect becomes difficult to be exhibited.

The average thickness t of the film 1 is preferably 10 μm or more and 50 μm or less. If the average thickness t is less than 10 μm, the film 1 is likely to break when stretched. Moreover, when the average thickness t is thicker than 50 μm, it leads to a decrease in the elasticity of the film.

It is not necessary that all the uneven shapes in the film 1 be the same, and the shapes may be a combination of FIGS. 1 and 2, for example. Furthermore, it is not necessary to make the pitch of the unevenness and the height difference h the same for all the unevenness, and it is possible to obtain the effects of the present invention even if the pitch and height difference h of the unevenness change.

Further, the roundness r of the corners 5 existing in the convex part 2 and the concave part 3 does not have to be all the same, and even if the roundness r differs from corner to corner, the present invention can be applied as long as it satisfies formula (1). It is possible to obtain the effect of

The film 1 of the present invention does not necessarily have to have a single layer structure, as shown in FIG. Also good. Examples of the functional layer include a stretch auxiliary layer, a conductive layer, and a barrier layer. Furthermore, a printed layer, an adhesive layer, etc. may be laminated on the front or back surface of the film 1 in a subsequent step.

Examples of materials constituting the film 1 include thermosetting resins, UV curable resins, and thermoplastic resins. Examples of curable resins include acrylic resins, epoxy resins, and urethane resins, and examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, ethylene vinyl acetate, polyvinyl alcohol, and ethylene-vinyl alcohol copolymers. , polyvinylidene chloride, polyacrylonitrile, polylactic acid, cyclic polyolefin, polyacetal, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, and derivatives thereof. However, these materials are not particularly limited, and these materials may be used alone, or a plurality of these materials may be used in combination.

As for the manufacturing method of the film 1, various methods can be selected and used as appropriate, such as a manufacturing method using hot press and a manufacturing method using extrusion molding.

In the production method using heat press, the original flat film is passed between a pair of heated rolls with an uneven surface or through a pair of heated flat presses to create an uneven shape. It is possible to produce a film 1 provided. At this time, precise alignment is performed between the pair of heating rolls or between the upper and lower concave and convex shapes of the pair of flat plates, so that the front and back surfaces of the film 1 after heat pressing have a continuous uneven shape. It is important that

Furthermore, in another manufacturing method using heat press, a plurality of flat films having mold releasability are stacked together, or a flat film holding a plurality of layers having mold releasability is stacked between heated rolls having an uneven shape, or By passing it through a heated flat plate press, it is possible to give it an uneven shape. At this time, by adjusting the pressing depth and pressing pressure, the desired uneven shape is imparted to the surface and layer interface of the flat film, and after cooling, the multiple layers of the film with the uneven shape are peeled off. 1 can be manufactured.

In the extrusion manufacturing method, the resin is heated and melted, extruded through a T-die, and cooled while applying nip pressure using a cooling roll and a nip roll provided with an uneven shape in the cooling process to form a film. Therefore, it is possible to provide continuous uneven shapes on the front and back surfaces of the film. Even in the extrusion manufacturing method, precise alignment between the cooling roll and the uneven shape of the nip roll is required.

Furthermore, in another manufacturing method by extrusion molding, a plurality of extruders are used and a plurality of types of resin are coextruded by a feed block method or a multi-manifold method, so that the film 1 is disposed on one surface. It is possible to obtain a film with a multilayer structure of more than one layer. At this time, in the cooling process to form a film, the surface on which the film is placed is cooled while applying nip pressure using a cooling roll whose surface has irregularities corresponding to the irregular shape. It is possible to form At this time, if the difference in height of the uneven shape is large relative to the thickness of the film in contact with the cooling roll, the uneven shape is similarly added to the interface on the opposite side of the film to the cooling roll, so the uneven shape is imparted after cooling. By peeling the resulting film from the multilayer film, it is possible to obtain a film 1 having an uneven cross-section with a undulating shape.

In all of the above-described methods for producing the film 1, an originally flat film or a flat extruded molten resin is fitted into a mold to give it an uneven shape. When providing an uneven shape in this manner, the originally flat film is stretched by the slope portion 4 of the film 1, so it is inevitable that a difference in thickness will occur within the film 1.

At this time, methods for reducing the thickness difference as much as possible include making the inclination angle of the slope part 4 as gentle as possible and not making the height difference h too large.By controlling these in a well-balanced manner, the formula ( It becomes possible to obtain an uneven shape that achieves 1).

It is also possible to laminate functional layers such as a printed layer, a vapor deposition layer, an anchor coat layer, etc. on the surface of the produced film 1 in a post-process. Furthermore, the film 1 can also be laminated with another resin.

The produced film 1 takes advantage of its easy-to-stretch, hard-to-break properties and can be used as a tape base material (a base material for laminating an adhesive layer to form a tape) and a patch base material (a base material for forming a patch by laminating an adhesive layer). It can be used for applications such as a stretchable circuit base material provided with a conductive layer, an electronics member, and a stretchable gas barrier film provided with a gas barrier layer.

Although the embodiments of the present invention have been illustrated above, the present invention is not limited to the above embodiments.

Examples based on the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
As the material for the film 1, polyethylene terephthalate (PET) manufactured by Bell Polyester Products Co., Ltd. with the product name EFG70 was selected. Furthermore, as the resin material to be coextruded with the film 1, the product name Novatec LD LC600A, which is low density polyethylene (LDPE) manufactured by Japan Polyethylene Co., Ltd., was selected.
Then, the two selected resins were co-extruded by extrusion molding, and then, in the cooling process to form a film, they were cooled while applying nip pressure using a cooling roll with an uneven shape. . Thereafter, the coextruded low-density polyethylene layer was peeled off to produce a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces of the film.
The average thickness t of the produced film 1 was 16 μm, the thickness of the thinnest part was 13 μm, the roundness r was 20 μm, the height difference h was 60 μm, and the breaking strength measured according to JISKK7127:1999 was 7.4 N/15 mm.

(Example 2)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 16 μm, the thickness of the thinnest part was 14 μm, the roundness r was 40 μm, the height difference h was 50 μm, and the breaking strength measured according to JISKK7127:1999 was 8.6 N/15 mm.

(Example 3)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The produced film 1 had an average thickness t of 11 μm, a thickness of the thinnest part of 9 μm, a roundness r of 30 μm, a height difference h of 60 μm, and a breaking strength measured according to JISKK7127:1999 of 5.3 N/15 mm.

(Example 4)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 27 μm, the thickness of the thinnest part was 23 μm, the roundness r was 50 μm, the height difference h was 60 μm, and the breaking strength measured according to JISKK7127:1999 was 26.7 N/15 mm.

(Example 5)
Using the same material and manufacturing method as in Example 1, a film 1 having continuous arcuate concavo-convex shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 14 μm, the thickness of the thinnest part was 12 μm, the roundness r was 50 μm, the height difference h was 60 μm, and the breaking strength measured according to JISKK7127:1999 was 7.8 N/15 mm.

(Example 6)
Using the same material and manufacturing method as in Example 1, a film 1 having continuous arcuate concavo-convex shapes on the front and back surfaces was produced.
The produced film 1 had an average thickness t of 20 μm, a thickness at the thinnest part of 17 μm, a roundness r of 75 μm, a height difference h of 80 μm, and a breaking strength measured according to JISKK7127:1999 of 14.2 N/15 mm.

(Example 7)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 35 μm, the thickness of the thinnest part was 30 μm, the roundness r was 45 μm, the height difference h was 80 μm, and the breaking strength measured according to JISKK7127:1999 was 25.4 N/15 mm.

(Comparative example 1)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 16 μm, the thickness of the thinnest part was 11 μm, the roundness r was 20 μm, the height difference h was 60 μm, and the breaking strength measured according to JISKK7127:1999 was 3.6 N/15 mm.

(Comparative example 2)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 16 μm, the thickness of the thinnest part was 13 μm, the roundness r was 40 μm, the height difference h was 30 μm, and the breaking strength measured according to JISKK7127:1999 was 17 N/15 mm.

(Comparative example 3)
Using the same materials and manufacturing method as in Example 1, a film 1 having continuous trapezoidal uneven shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 16 μm, the thickness of the thinnest part was 13 μm, the roundness r was 10 μm, the height difference h was 60 μm, and the breaking strength measured according to JISKK7127:1999 was 3.2 N/15 mm.

(Comparative example 4)
Using the same material and manufacturing method as in Example 1, a film 1 having continuous arcuate concavo-convex shapes on the front and back surfaces was produced.
The average thickness t of the produced film 1 was 16 μm, the thickness of the thinnest part was 13 μm, the roundness r was 70 μm, the height difference h was 60 μm, and the breaking strength measured according to JISKK7127:1999 was 8.7 N/15 mm.

(Comparative example 5)
Using the same material and manufacturing method as in Example 1, a film 1 having continuous arcuate concavo-convex shapes on the front and back surfaces was produced.
The produced film 1 had an average thickness t of 20 μm, a thickness at the thinnest part of 14 μm, a roundness r of 75 μm, a height difference h of 80 μm, and a breaking strength measured according to JISKK7127:1999 of 4.2 N/15 mm.

(Comparative example 6)
Using the same material and manufacturing method as in Example 1, a film 1 having continuous arcuate concavo-convex shapes on the front and back surfaces was produced.
The produced film 1 had an average thickness t of 8 μm, a thickness at the thinnest part of 7 μm, a roundness r of 50 μm, a height difference h of 60 μm, and a breaking strength measured according to JISKK7127:1999 of 3.2 N/15 mm.

(Stretchability evaluation)
As a performance evaluation of each Example and Comparative Example, elasticity was evaluated.
The elasticity was evaluated as "○" if the test subject felt a sufficient stretch feeling with his or her hand, and "x" if the test subject felt that the stretch was insufficient. It should be noted that this evaluation was conducted by each of the five test subjects, and the answer that received the most responses was adopted as the final evaluation result.
(Rupture resistance evaluation)
As a performance evaluation of each Example and Comparative Example, evaluation of breakage resistance was performed.
For the evaluation of break resistance, films that did not break when the film was pulled by hand or required a strong force to break were rated "○", and films that easily broke even with a weak force were rated "x". It should be noted that this evaluation was conducted by each of the five test subjects, and the answer that received the most responses was adopted as the final evaluation result.

Table 1 shows a list of conditions and evaluation results for each example and comparative example.

(Evaluation results)
From the evaluation results of the examples in Table 1, the average thickness t, roundness r, and height difference h of the produced film 1 satisfy formula (1), and the thickness of the thinnest part is -20% or more with respect to the average thickness. It can be seen that in the case of , the breaking strength is greater than 5 N/15 mm, resulting in good stretchability and breaking resistance. Moreover, this result was the same whether the cross-sectional shape was trapezoidal or circular.
On the other hand, if the relationship of average thickness t<roundness r<height difference h (formula (1)) is not satisfied, or if the thickness of the thinnest part is less than 20% of the average thickness t, the elasticity and rupture It was not possible to satisfy both tolerance requirements. In particular, when the roundness r is less than the average thickness t, when the thickness of the thinnest part is thin, and when the average thickness t is too thin, the fracture resistance evaluation is "x", and when the roundness r is more than the height difference It was found that when the average thickness t is too thick, the elasticity evaluation becomes "x".

This specification includes disclosures of the following inventions.
(Invention A)
The film has an uneven shape on both the front and back surfaces, the uneven shape is a repeating array of protrusions and depressions, and the adjacent protrusions and depressions share a sloped part arranged between them. , the back surface has an uneven shape that follows the uneven shape of the front surface,
A film in which the height difference h between the surface of the concave portion and the surface of the convex portion is greater than the average thickness t of the film,
In the cross section of the film, the roundness r of the connecting part connecting the top of the convex part or the bottom of the concave part and the slope part, or the cross-sectional center line of the top of the convex part or the bottom of the concave part is approximated by a part of a circle. If possible, the radius r of the circle is larger than the average thickness t of the film and smaller than the height difference h,
The thickness of the thinnest part of the film is -20% or more and 0% or less of the average thickness t of the film,
When pulled in the direction in which the convex portions and the concave portions are repeatedly arranged, the breaking strength measured according to JIS K7127:1999 is 5 N/15 mm or more and 30 N/15 mm.
A film characterized by

(Invention B)
The uneven shape of the cross section of the film is a trapezoidal shape having a flat part in the convex part and the concave part, or an arc shape without a flat part in the convex part and the concave part.
The film of invention A characterized by the following.

(Invention C)
The average thickness t of the film is 10 μm or more and 50 μm or less,
A film according to invention A or invention B, characterized in that:

(Invention D)
A tape formed by using the film of any one of Inventions A to C as a base material and laminating it with an adhesive layer.

(Invention E)
A patch comprising the film of any one of inventions A to C as a base material and laminated with an adhesive layer.

Since the film 1 of the present invention has good stretchability and breakage resistance, it is expected to be used as a film that is stretchable yet resistant to tearing in applications where large loads are applied during tension, such as base materials for tapes and adhesive patches. be done.

1...Film 2...Protrusion 2a...Top 3...Concave 3a...Bottom 4...Slope 5...Corner in trapezoidal cross-section

Claims (5)

The film has an uneven shape on both the front and back surfaces, the uneven shape is a repeating array of protrusions and depressions, and the adjacent protrusions and depressions share a sloped part arranged between them. , the back surface has an uneven shape that follows the uneven shape of the front surface,
A film in which the height difference h between the surface of the concave portion and the surface of the convex portion is greater than the average thickness t of the film,
In the cross section of the film, the roundness r of the connecting part connecting the top of the convex part or the bottom of the concave part and the slope part, or the cross-sectional center line of the top of the convex part or the bottom of the concave part is approximated by a part of a circle. If possible, the radius r of the circle is larger than the average thickness t of the film and smaller than the height difference h,
The thickness of the thinnest part of the film is -20% or more and 0% or less of the average thickness t of the film,
When pulled in the direction in which the convex portions and the concave portions are repeatedly arranged, the breaking strength measured according to JIS K7127:1999 is 5 N/15 mm or more and 30 N/15 mm.
A film characterized by The uneven shape of the cross section of the film is a trapezoidal shape having a flat part in the convex part and the concave part, or an arc shape without a flat part in the convex part and the concave part.
The film according to claim 1, characterized in that: The average thickness t of the film is 10 μm or more and 50 μm or less,
The film according to claim 1, characterized in that: A tape formed by using the film according to any one of claims 1 to 3 as a base material and laminating it with an adhesive layer. A patch comprising the film according to any one of claims 1 to 3 as a base material and laminated with an adhesive layer.

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