JP7625209B2 - Adhesive tapes and adhesive products - Google Patents

Description

The present invention relates to an adhesive tape that can conform to curves and curved surface shapes, improves the efficiency of bonding work, reduces material waste, and improves the appearance quality.

Conventionally, adhesive tapes disclosed include a tape having a hot-melt polyurethane adhesive layer on the surface of a polyurethane resin film (see, for example, Patent Document 1); a release film having shape-following properties imparted by laminating multiple thermoplastic resins with different softening points (see, for example, Patent Document 2); an adhesive sheet having a hot-melt adhesive coating having elasticity on at least one side of a support sheet having elasticity and heat resistance (see, for example, Patent Document 3); an adhesive sheet containing cellulose-based fibers and an elastomer-based impregnating agent on the main surface of the support and having a breaking elongation of more than 8% (see, for example, Patent Document 4); an adhesive tape using a foam substrate and a tackifier resin with a softening temperature lower than that of thermoplastic rubber (see, for example, Patent Document 5); and a laminated film using a layer containing polyarylene sulfide and a polyolefin-based resin layer (see, for example, Patent Document 6).

JP 11-172209 A Patent Publication 2005-205745 JP 08-120231 A Special table 09-508933 Patent Publication 2000-073025 JP2007-190689

However, the technology of Patent Document 1 has high peel strength and poor releasability due to the affinity between the urethane film and the urethane adhesive, the technology of Patent Document 2 requires a lamination process and material costs due to the use of multiple thermoplastic resins in the release film, the technology of Patent Document 3 has high peel strength between components A and B and poor releasability, the technology of Patent Document 4 has poor conformability due to the suppression of elongation by the cellulose-based fibers, the technology of Patent Document 5 is easy to bend and deform the adherend after adhesion, but the modulus of the tape itself is low, so the substrate is easily stretched more than necessary during adhesion, resulting in poor workability and releasability, and the technology of Patent Document 6 has poor heat resistance because it cannot withstand the ironing and pressing temperatures used in thermoplastic hot melt adhesion work due to its low glass transition temperature.

On the other hand, when adhesive tape is applied to curves or curved shapes, there are problems such as wrinkles due to the difference between the inner and outer circumferences and the time required for the application process. In order to solve these problems, many adhesive tapes have been produced in which the adhesive sheet is punched or molded into the desired curve shape. However, adhesive tapes punched or molded into the desired curve shape have waste because the parts other than the molded or punched parts are unnecessary, and there is a problem of environmental burden due to plastic waste. In addition, there is a drawback in that processing equipment and process time are required for molded cutting or punching, and production and material costs are high. Therefore, the object of the present invention is to provide an adhesive tape and adhesive processed product that has heat resistance that can withstand the adhesion of thermoplastic hot melt, and has the ability to follow curves and curved shapes despite being a linear tape, and can improve the efficiency of the application process by omitting the molded cutting or punching process, reduce material waste, and improve the appearance quality.

The adhesive tape and adhesive processed product of the present invention that can achieve the above object have the following configuration.
(1) The adhesive tape of the present invention has at least an adhesive layer made of component A and a release layer made of component B covering one side of the adhesive layer, wherein the stress of the release layer at 50% elongation is in the range of 1 to 25 MPa or less and the stress of the adhesive layer at 50% elongation is in the range of 1 MPa to 6 MPa, and the peel strength between the adhesive layer and the release layer is in the range of 0.05 N/cm to 0.5 N/cm.
(2) More preferably, said component A is a thermoplastic hot melt.
(3) More preferably, in the adhesive tape, the softening point T _B1 of the component B is 100° C. or higher, the softening point T _A1 of the component A is 100° C. or lower, and the softening point ratio (T _B1 /T _A1 ) is in the range of 2 to 5.
(4) More preferably, in the adhesive tape, the melting point temperature T _B2 of component B is higher than the melting point temperature T _A2 of component A, and the ratio of the melting points (T _A2 /T _B2 B) is in the range of 1.5 to 2.5.
(5) More preferably, in the adhesive tape, the visible light transmittance VT _B of component B is 75% or less, the visible light transmittance VT _A of component A is 60% or more, and the ratio of the visible light transmittances (VT _B /VT _A ) is 80% or less.

(6) More preferably, in the adhesive tape, the breaking strength BS _B of component B is higher than the breaking strength BS _A of component A, and the breaking strength ratio (BS _B /BS _A ) is 1 or more.
(7) More preferably, the adhesive tape has a yield point elongation of 25% to 27%, a yield point stress of 7 MPa to 16 MPa, and a lower yield point stress in the range of 7 MPa to 16 MPa.
(8) Another preferred embodiment of the adhesive processed product of the present invention is an adhesive processed product using at least the adhesive tape, the adhesive processed product having an adhesive part consisting of at least an adherend and an adhesive layer of the adhesive tape, the adhesive part having at least a curved shape with a radius of curvature in the range of 5 cm to 30 cm at least in a part thereof, the width of the adhesive tape being in the range of 5 mm to 30 mm, and the ratio of the maximum thickness to the minimum thickness (maximum thickness/minimum thickness) of the thickness at the outer edge part and the thickness at the inner edge part in the longitudinal direction of the curved shape of the adhesive part being in the range of 101 to 150%.

The present invention makes it possible to obtain an adhesive tape that can conform to curves and curved surface shapes, improves the efficiency of bonding work, reduces material waste, and improves the appearance quality.

FIG. 1 is a cross-sectional view of the adhesive tape of the present invention before single-sided bonding processing. FIG. 2 is a cross-sectional view of the adhesive tape shown in FIG. 1 after one-sided bonding processing. FIG. 3 is a cross-sectional view of the adhesive tape shown in FIG. 1 after double-sided adhesive processing. FIG. 4 is an exploded perspective view of the adhesive tape of the present invention when used for a curved adhesive portion (before one-sided adhesive processing). FIG. 5 is an exploded perspective view of the adhesive tape of the present invention when used for a curved adhesive portion (double-sided adhesive processing). FIG. 6 is an enlarged cross-sectional view of a portion of the adhesive processed product of FIG. FIG. 7 is an image showing the distortion evaluation of the adhesive processed product of the present invention (after one-sided adhesive processing). FIG. 8 is an image showing a distortion evaluation of a conventional adhesively processed product (after one-sided adhesive processing). FIG. 9 is a photograph showing the appearance of the adhesive processed product of the present invention shown in FIG. 7 (after one-sided adhesive processing). FIG. 10 is a photograph showing the appearance of the conventional adhesively processed product shown in FIG. 9 after one-sided adhesive processing.

The adhesive tape and adhesive processed product of the present invention will be described in detail below with reference to the drawings.
(Description of the invention and drawings)
Fig. 1 is a cross-sectional view of the adhesive tape of the present invention before one-sided bonding processing. As shown in Fig. 1, the adhesive tape 1 of the present invention is composed of an adhesive layer 1a made of component A and a release layer 1b made of component B, and at least one surface of the adhesive layer 1a is covered with the release layer 1b. The component B functions as a release material, and the component A functions as an adhesive, and they fulfill their respective roles as an adhesive tape.
Before being subjected to adhesive processing, the adhesive tape 1 has an adhesive layer 1a and a release layer 1b which are integrated together as shown in Fig. 1. An adhesive processed product using the adhesive tape 1 of the present invention has an adhesive part consisting of the adhesive layer 1a and an adherend 2, and the adhesive part is formed by adhesive processing the adhesive tape 1 to the adherend 2.

Adhesive processing is mainly classified into single-sided adhesive processing and double-sided adhesive processing.
The single-sided adhesive processing is a process in which one side of the adhesive layer 1a of the adhesive tape 1 is adhered to an adherend 2 as shown in FIG. 1, and then the release layer 1b is removed to expose the other side of the adhesive layer 1a as shown in FIG. 2.
The state of the adhesive part after the one-sided bonding process is such that one side of the adhesive layer 1a of the adhesive tape 1 is in contact with the adherend 2, the other side is exposed, and the release layer 1b has been removed.
As shown in FIG. 3, double-sided adhesive processing is a process in which the surface of adhesive layer 1a of adhesive tape 1 exposed in single-sided adhesive processing is adhered to another adherend 2', so that both surfaces of adhesive layer 1a are adhered to adherend 2 and adherend 2'.
In the state of the adhesive part after double-sided adhesive processing, both sides of the adhesive layer 1a of the adhesive tape 1 are in contact with the adherend 2 and the adherend 2', and the release layer 1b has been removed. The adhesive part may be formed in any shape along the longitudinal direction of the adhesive tape 1, such as a curved/arc-shaped, straight line, zigzag, or dotted line.

<Elongation stress>
FIG. 4 is an exploded perspective view of the adhesive tape of the present invention when used in a curved adhesive part (before one-sided adhesive processing). When the adhesive tape 1 of the present invention processed into a straight line is applied to a curved or arcuate adhesive part to form an adhesive part, the arc length is different between the outer edge 7 and the inner edge 6 of the adhesive tape 1. When the adhesive tape 1 of the present invention is formed into a curved or arcuate adhesive part, the adhesive tape 1 has a suitable stress for stretching, so that wrinkles due to the distortion of the inner and outer circumference difference can be reduced. By setting the stress at 50% elongation of the component B constituting the release layer 1b to 1 MPa or more and 25 MPa or less, the appearance quality of the adhesive processed product can be improved. The stress at 50% elongation represents the elongation stress under a certain elongation condition. If the stress at 50% elongation is less than 1 MPa, there is a problem that the deformation is large and the shape stability is poor, and conversely, if it is 25 MPa or more, the ability to follow the curve or arc shape is poor. More preferably, it is in the range of 5 MPa or more and 20 MPa or less. By setting the stress at 50% elongation of the component A constituting the adhesive layer 1a to 0.5 MPa or more and 10 MPa or less, the appearance quality of the adhesive processed product can be improved. If the stress at 50% elongation is less than 0.5 MPa, there is a problem that deformation is large and shape stability is poor, and conversely, if it is 10 MPa or more, it is poor in conformity to curves and arc shapes. More preferably, it is in the range of 1 MPa or more and 6 MPa. The stress at 50% elongation is measured based on JIS K 7127 under the condition of a tensile speed of 100 mm/min.

<Radius of curvature of adhesive joint>
When the adhesive part is formed in a curved or arc shape, the difference in arc length between the outer edge 7 and the inner edge 6 of the adhesive part changes depending on the radius of curvature, and the difference in arc length also changes the distortion wrinkles due to the difference in inner and outer circumference, so it is preferable that the radius of curvature of the adhesive part is in a range where the above-mentioned wrinkles are unlikely to occur. From the viewpoint of appearance quality, it is preferable that the radius of curvature of the adhesive part of the adhesive processed product is 5 cm or more and 30 cm or less. The radius of curvature of the adhesive part represents the radius of curvature of the inner edge 6 of the adhesive layer 1a forming the adhesive part. If the radius of curvature of the adhesive part is less than 5 cm, there is a problem that the difference in arc length between the outer edge and the inner edge is large and distortion wrinkles due to the difference in inner and outer circumference are likely to occur, and conversely, if the radius of curvature is greater than 30 cm, the difference in appearance quality due to the configuration of the tape body becomes small.

<Adhesive tape width>
The wrinkles caused by the difference in arc length between the outer edge 7 and the inner edge 6 of the adhesive layer 1a when the adhesive part is formed in a curved or arc shape vary depending on the width of the adhesive tape 1 as well as the radius of curvature of the adhesive part. The width of the adhesive tape 1 is preferably set to a range in which the above-mentioned wrinkles are unlikely to occur. From the viewpoint of appearance quality, the width of the adhesive tape 1 is preferably 5 mm or more and 50 mm or less. The width of the adhesive tape 1 represents the length in the direction perpendicular to the longitudinal direction of the adhesive tape 1. If the width of the adhesive tape 1 is less than 5 mm, there is a problem that processing defects such as twisting and meandering due to thinness are likely to occur, and conversely, if it is 50 mm or more, bending when bonding in a curved or arc shape is difficult, and the difference in arc length between the outer edge and the inner edge of the adhesive part becomes large, and distortion wrinkles due to the difference in inner and outer circumferences are likely to occur. When the radius of curvature of the adhesive part of the adhesive processed product is 5 cm or more and 30 cm or less, the width of the adhesive tape 1 is preferably 5 mm or more and 30 mm or less, more preferably 5 mm or more and 15 mm or less.

<Thickness ratio of inner and outer edges>
In the adhesive processed product 9 using the adhesive tape 1 of the present invention, when the adhesive part is formed in a curved or arc-shaped shape, the difference between the thickness at the outer edge of the adhesive layer 1a in the longitudinal direction and the thickness at the inner edge is small, i.e., the ratio of the maximum thickness to the minimum thickness (maximum thickness/minimum thickness) of the two values is small, which is preferable in terms of appearance quality because the difference in thickness is less likely to be visually recognized, and the step, shadow, and wrinkles due to the thickness difference are less likely to be visually recognized. The ratio of the maximum thickness to the minimum thickness (maximum thickness/minimum thickness) of the thickness at the outer edge of the adhesive part in the longitudinal direction and the thickness at the inner edge is preferably 101% or more and 150% or less. If the ratio of the maximum thickness to the minimum thickness (maximum thickness/minimum thickness) of the thickness at the outer edge of the curved or arc-shaped adhesive part in the longitudinal direction and the thickness at the inner edge is less than 101% or more than 150%, the step, shadow, and wrinkles due to the thickness of the outer edge or inner edge are more likely to be visually recognized. More preferably, it is in the range of 101% to 120%. The thickness of the adhesive joint is measured based on JIS K 7130: 1999 Plastics - Films and Sheets - Thickness Measurement Method. The means for adjusting the thickness of the adhesive joint may be any method, depending on the production method, such as various molding methods such as T-die, injection, and inflation, and coating methods such as knife overcoating and gravure, but T-die molding is preferred in terms of applicable thickness, shape, etc.

<Ratio of inner and outer edge lengths>
In the adhesive processed product 9 using the adhesive tape 1 of the present invention, when the adhesive part is formed into a curved or arc-shaped shape, the difference between the length of the adhesive layer 1a in the longitudinal direction at the outer edge and the length of the inner edge is small, i.e., the ratio of the two (outer edge length/inner edge length) is small, which is preferable in terms of adhesive workability and appearance quality, since distortion and wrinkles due to the difference between the inner and outer circumferences are less visible. It is also preferable from the viewpoint of adhesive workability and appearance quality that the ratio of the length of the adhesive part in the longitudinal direction at the outer edge and the length of the inner edge (outer edge length/inner edge length) is less than 140%. If the ratio of the length of the adhesive part in the longitudinal direction at the outer edge and the length of the inner edge (outer edge length/inner edge length) is 140% or more, wrinkles and shadows due to distortion due to the difference between the inner and outer circumferences are easily visible, and there is a problem that adhesive processing is difficult. More preferably, it is in the range of 100% to 130%. The ratio of the inner edge length to the outer edge length of the adhesive portion was calculated by taking the center point of the arc with the largest radius of curvature among the arc-shaped portions of the adhesive portion, drawing two radius lines from this center point to the outer edge of the adhesive portion, measuring the arc length of the inner edge and the arc length of the outer edge between the two radius lines, and then calculating the ratio between the two, i.e., dividing the arc length of the outer edge by the arc length of the inner edge, using the following formula (arc length of the outer edge ÷ arc length of the inner edge).

<Peel strength>
The adhesive tape 1 of the present invention has a step of removing the release layer 1b after adhering one side of the adhesive layer 1a of the adhesive tape 1 to the adherend 2, i.e., peeling the adhesive layer 1a from the release layer 1b, as shown in the above-mentioned single-sided adhesive processing and FIG. 2. In the peeling step, it is preferable to impart a suitable peel strength between the adhesive layer 1a and the release layer 1b, so that the adhesive layer 1a and the release layer 1b can be easily peeled off from each other and do not naturally peel off except in the above-mentioned step. The peel strength between the adhesive layer 1a and the release layer 1b is preferably 0.05 N/cm or more and 0.5 N/cm or less from the viewpoint of ease of peeling when removing the release layer 1b after adhering one side of the adhesive layer 1a to the adherend 2 in the above-mentioned single-sided adhesive processing. If the peel strength between the adhesive layer 1a and the release layer 1b is less than 0.05 N/cm, there is a problem that the adhesive layer 1a and the release layer 1b are likely to naturally peel off from each other outside the adhesion process, and conversely, if it is 0.5 N/cm or more, the adhesive layer 1a and the release layer 1b are unlikely to peel off from each other after one-sided adhesion processing. More preferably, it is in the range of 0.05 to 0.2 N/cm. The peel strength between the adhesive layer 1a and the release layer 1b is measured at a tensile speed of 300 mm/min based on the JIS L 1093 (2011) 7.1.1A-1 method. The means for adjusting the peel strength of the adhesive layer 1a and the release layer 1b may vary depending on the manufacturing method, but may include coating the adhesive layer 1a on the release layer 1b using the T-die method or various coating methods, or conversely, coating the adhesive layer 1a on the release layer 1b using various coating methods similar to those described above, or manufacturing the adhesive layer 1a and the release layer 1b separately and then laminating them by applying heat or the like. However, from the standpoint of cost and ease of production, a means of continuous processing such as coating the adhesive layer 1a on the release layer 1b or coating the release layer 1b on the adhesive layer 1a is preferred, and preparation by the T-die method is preferred as this means.

<Adhesive Layer>
As the type of component A constituting the adhesive layer 1a, an organic adhesive is mainly used. The types of organic adhesives are broadly classified into natural resin-based adhesives such as natural rubber casein, semi-synthetic adhesives such as cellulose acetate, and synthetic resin-based adhesives using polyurethane, acrylic, etc., with synthetic resin-based adhesives being preferred in terms of processability and cost.
The types of synthetic resins are subdivided into resin systems using polyurethane, polyester, PVA, vinyl chloride, acrylic resin, polyethylene, ethylene-vinyl acetate polymer, polyamide systems, etc., elastomer systems using silicone rubber, nitrile rubber, etc., and composite systems using nylon-epoxy, vinyl-phenolic, etc., and more preferably, thermoplastic systems are preferred because they have flexibility while providing excellent strength of component A itself.
In terms of the form of synthetic resins, there are dry-solidification types such as water-soluble, latex, and dispersion types; chemical reaction types in which a crosslinking reaction occurs when the base resin and curing agent are mixed to harden; hot melt types that are solid at room temperature but melt when heated and harden when cooled; and pressure-sensitive types that apply pressure to a highly viscous, flowable liquid to create an adhesive. Of these, the hot melt type (thermoplastic hot melt) is more preferred as it has excellent adhesive strength at the interface between the adherend and component B.
As the resin component of the thermal melt type (thermoplastic hot melt), ethylene-vinyl acetate polymer, polyamide, polyester, polyurethane, polyolefin, etc. are preferably used, but polyurethane is more preferable because it has high processability and is excellent in heat resistance, adhesive strength, and durability due to a crosslinking reaction with moisture (humidity) contained in the air.

<Release Layer>
The type of component B constituting the release layer is not particularly limited as long as it is a resin having a stress in the range of 1 to 6 MPa at an elongation of 50%, and examples include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polylactic acid, polycarbonates, polystyrene, polyphenylene sulfite, fluorine-based resins, and mixtures thereof. Among these, polyolefin-based resins can be preferably used from the viewpoint of excellent productivity, elongation, and flexibility. In addition, a mixture in which a polyolefin-based resin is mixed with synthetic rubber up to about 40% by mass is also suitable as component B.

<Method of adhesive processing>
As a method for bonding the adhesive tape 1 to the adherends 2, 2', the heat pressing method, high frequency heating method, and ultrasonic processing method are mainly used, but any of them may be used, and the heat pressing method is more preferable because of its excellent cost and productivity.

<Softening property>
Since the adhesive tape 1 of the present invention is subjected to the adhesive processing by heating as described above, it is preferable that the component A constituting the adhesive layer 1a is easily softened and the component B constituting the release layer 1b is not easily softened under the heat processing temperature conditions from the viewpoint of adhesion to the adherend and adhesive processing stability. The softening point T _B1 of the component B is preferably 100°C or more from the viewpoint of adhesion to the adherend and adhesive processing stability. If the softening point T _B1 of the component B is less than 100°C, there is a problem that the shape retention as a release material is poor. More preferably, it is in the range of 130°C or more and 240°C or less. The softening point T _A1 of the component A is preferably 40°C or more and 130°C or less from the viewpoint of adhesion to the adherend and adhesive processing stability. If the softening point T _A1 of the component A is less than 40°C, there is a problem that the temperature becomes close to room temperature and the shape cannot be maintained, and conversely, if it is 130°C or more, the processability and moldability as an adhesive resin are poor. More preferably, it is in the range of 50° C. or higher and 110° C. or lower. In the present invention, since component B plays the role of a release agent, it is preferable that the softening point of component B is higher than that of component A which plays the role of an adhesive, that is, the softening point T _B1 of component B is 100° C. or higher and the softening point T _A1 of component A is less than 100° C., from the viewpoint of shape retention as a release agent. More preferably, the ratio of the two (T _B1 /T _A1 ) is in the range of 2 to 5. The softening point was measured using a DMAQ800 manufactured by TA Instruments in a temperature rise/control force mode at a temperature rise rate of 10° C./min, and the temperature at the first change point of the load value was obtained.

<Melting property>
As a more preferred embodiment, under the heating processing temperature conditions, the component A constituting the adhesive layer 1a is easily melted, and the component B constituting the release layer 1b is not easily melted, which is preferable in terms of excellent adhesion to the adherend and adhesion processing stability. With regard to the melting point temperature, it is preferable that the melting point temperature T _B2 of the component B is higher than the melting point temperature T _A2 of the component A from the viewpoint of shape stability during adhesion processing. If the melting point temperature T _A2 of the component A is lower than the melting point temperature T _B2 of the component B, there is a problem that the component B, which is the release material, melts before the component A, which is the adhesive resin, melts during adhesion processing, causing a problem of interference with the adhesion work. More preferably, the ratio (T _B2 /T _A2 ) of the melting point temperature T _B2 of the component B to the melting point temperature T _A2 of the component A is in the range of 1.5 to 2.5. The melting point was measured using a DMAQ800 manufactured by TA Instruments in a temperature rise/control force mode at a temperature rise rate of 10° C./min, and the point at which the strain displacement amount changed significantly was taken as the melting point.

<Breaking strength>
In the adhesive tape of the present invention, it is necessary that the release layer 1b does not break during the adhesive processing, and it is preferable from the viewpoint of workability that the component B constituting the release layer 1b has a predetermined breaking strength. It is also preferable from the viewpoint of shape retention that the breaking strength BS _B of component B is higher than the breaking strength BS _A of component A. If the breaking strength BS _B of component B is lower than the breaking strength BS _A of component A, there is a problem that the component B constituting the release layer 1b cannot maintain the shape of component A during one-sided adhesive processing. The breaking strength is measured according to JIS K 7127 under the condition of a tensile speed of 100 mm/min.

<Visibility>
The adhesive tape 1 of the present invention is preferably suppressed from the viewpoint of workability so that the position and outline of the adhesive tape 1 can be easily visually recognized during the adhesive processing, that is, made difficult to see through. From the viewpoint of the visibility of the adhesive tape during the adhesive processing, it is preferable that the visible light transmittance VT _B of the component B constituting the release layer 1b is 0.75 or less. Also, from the viewpoint of the appearance quality of the adhesive processed product 9, it is preferable that the visible light transmittance VT _A of the component A constituting the adhesive layer 1a is 0.6 or more. If the visible light transmittance VT _A of the component A is less than 0.6, there is a problem that the component A causes the shading of the adhesive part of the adhesive processed product 9 after the double-sided adhesive processing, and the appearance quality is reduced. On the other hand, if the visible light transmittance VT _B of the component B exceeds 0.75, the component B is difficult to visually recognize during the single-sided adhesive processing, and the workability is poor. More preferably, the ratio of the visible light transmittances of the components B and A (VT _B /VT _A ) is in the range of 80% or less. The visible light transmittance is measured based on JIS A5759. The visible light transmittance may be adjusted by any method, such as mixing a pigment or dye with Component A and Component B, or by various printing methods, such as gravure printing, inkjet printing, and screen printing, or vapor deposition, but the method of mixing an appropriate amount of pigment is preferred from the viewpoints of cost, simplicity, and coloring stability.

<Yield point elongation stress>
In order to impart the adhesive tape 1 of the present invention with the ability to conform to curves and other bent shapes during single-sided bonding processing, it is preferable from the standpoint of workability and appearance quality that the adhesive tape 1 is easily plastically deformed in response to the elongation or load applied during processing.
A preferred form of the adhesive tape 1 that is prone to plastic deformation during single-sided adhesive processing is that the elongation and load at which the adhesive tape 1 undergoes plastic deformation, i.e., the yield point elongation, yield point stress, and lower yield point stress, are equivalent to the ranges of the respective values applied during processing. The yield point elongation of the adhesive tape 1 is preferably 25% or more and 27% or less from the viewpoint of the ability to follow a curved shape such as a curve during single-sided adhesive processing. The yield point elongation of such an adhesive tape represents the magnitude of elongation at which, when tension is applied to the adhesive tape 1, the deformation of the adhesive tape 1 increases rapidly beyond the elastic limit and does not return to its original state. If the yield point elongation of the adhesive tape 1 is less than 25%, there is a problem that the adhesive tape is difficult to plastically deform in response to the elongation or load applied during processing, resulting in poor workability and poor appearance quality. Conversely, if it is more than 27%, the adhesive tape is deformed more than necessary and is poor in shape retention. More preferably, the yield point elongation of component B is in the range of 6% to 18% and the yield point elongation of component A is in the range of 15% to 45%. The yield point elongation of such an adhesive tape is measured based on JIS K 7127. The means for adjusting the yield point elongation of the adhesive tape may be any method such as increasing or decreasing the thickness of the adhesive layer 1a and/or the release layer 1b, stretching, or selecting the components A and B. However, from the viewpoint of the ability to follow a curved shape such as a curve during one-sided bonding processing, adjustment by the stretching conditions of the adhesive layer 1a and/or the release layer 1b is preferred.

The yield stress and lower yield stress of the adhesive tape 1 of the present invention are preferably 7 MPa or more and 16 MPa or less from the viewpoint of the ability to follow a curved shape such as a curve during one-sided adhesive processing. The yield stress and lower yield stress of the adhesive tape 1 represent the magnitude of stress when the deformation of the adhesive tape increases rapidly beyond the elastic limit and does not return to the original state when a load is applied to the adhesive tape 1. Among them, the lower yield stress represents the minimum stress when yielding. If the yield stress and lower yield stress of the adhesive tape 1 are less than 7 MPa, the adhesive tape 1 is subject to a large elastic deformation and is deformed more than necessary, resulting in poor shape retention. On the other hand, if the yield stress and lower yield stress are 16 MPa or more, the adhesive tape 1 is difficult to plastically deform in response to the elongation or load applied during processing, resulting in poor workability and appearance quality. More preferably, the yield stress of component B is in the range of 17 MPa to 53 MPa and the component A is in the range of 1 MPa to 5 MPa, and the lower yield stress of component B is in the range of 12 MPa to 39 MPa and the component A is in the range of 1 to 5 MPa.
The yield point stress and lower yield point stress of the adhesive tape 1 are measured based on JIS K 7127, and the measured values of the yield point and lower yield point are obtained from an elongation-stress curve. The means for adjusting the yield point stress and lower yield point stress of the adhesive tape 1 may be any method, such as increasing or decreasing the thickness of the adhesive layer 1a and/or the release layer 1b, stretching, or selecting the components A and B. However, from the viewpoint of the ability to follow a curved shape such as a curve during one-sided bonding processing, adjustment by the stretching conditions of the adhesive layer 1a and/or the release layer 1b is preferred.

<Adherend>
As the material for the adherends 2, 2', mainly woven or knitted fiber fabrics or nonwoven fabrics are used. Woven or knitted fabrics are more preferable because they have excellent strength. When woven fabrics are used, generally, plain weave, twill weave, satin weave, and their variations and multiaxial weaves are preferably used. When knitted fabrics are used, plain knit, rib knit, pearl knit, tricot, raschel, Milanese, etc. are preferably used. When nonwoven fabrics are used, papermaking methods, chemical adhesion methods, heat fusion methods, water jet punch methods, melt blow methods, flash spinning methods, etc. are preferably used.

<Applications>
The adhesive processed product 9 using the adhesive tape 1 of the present invention may be used for any of a variety of purposes, such as clothing, hats, gloves, futons, sheets, curtains, tents, sleeping bags, umbrellas, bags, and the like.
The adhesive processed product 9 of the present invention may be constructed by combining an adhesive part using the adhesive tape 1 of the present invention with a sewn part using a sewing machine. The sewn part using a sewing machine may be replaced with an adhesive part. That is, the adhesive part can be used as a seam for joining at least the adherends together.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. The adhesive tapes and adhesive processed products used in the examples and comparative examples were evaluated by the following methods.

(Measurement items)
[Disposal loss rate (%)]
The waste loss rate (%) in the cutting process or molding process of the adhesive tape or the like of the present invention was calculated by measuring the cut cross-sectional area of the tape and the area other than the adhesive part generated, i.e., the waste area, and calculating the ratio of the waste area to the cut cross-sectional area of the tape, i.e., the waste area divided by the cut cross-sectional area of the tape, using the following formula (waste area ÷ cut cross-sectional area of the tape).

[Ratio of inner edge length to outer edge length of adhesive joint (%)]
An adhesive processed product having an arc-shaped joint was produced using the adhesive tape or the like of the present invention, and the ratio of the inner edge length to the outer edge length of this adhesive part was determined by taking the center point of the arc with the largest radius of curvature among the arc-shaped parts of the adhesive part, drawing two radius lines from this center point to the outer edge of the adhesive part, measuring the arc length of the inner edge and the arc length of the outer edge between the two radius lines, and then dividing the ratio between the two, i.e., the arc length of the outer edge by the arc length of the inner edge, using the following formula (arc length of the outer edge ÷ arc length of the inner edge).

[Thickness ratio (%)]
An adhesive processed product having an arc-shaped joint was produced using the adhesive tape of the present invention, and the ratio of the thickness at the outer edge of the adhesive part in the longitudinal direction to the thickness at the inner edge was measured based on JIS K 7130: 1999 Plastics - Film and Sheet Thickness Measurement Method, and the ratio was calculated by dividing the thickness at the maximum part by the thickness at the minimum part, that is, by the following formula (thickness at maximum part ÷ thickness at minimum part).

[Processing speed (cm/min)]
The processing speed of the adhesive processed product using the adhesive tape of the present invention is calculated by dividing the processing time required for one-sided adhesive processing of the adhesive part by the length in the longitudinal direction of the adhesive tape, that is, by the following formula (for one-sided adhesive processing) The processing time required was divided by the length of the adhesive tape in the longitudinal direction.

(evaluation)
[Appearance quality]
The appearance quality of the adhesive processed products, which were subjected to adhesive processing using the adhesive tape of the present invention, i.e., the degree of wrinkles and distortion, was evaluated on a 7-point scale (-3 to 3, in 1-point increments). The higher the evaluation score, the better the appearance quality. The average of the evaluation scores of the five evaluators was regarded as the evaluation result, and an evaluation result of 1 point or more was regarded as good. The evaluation criteria are shown in Table 1.

[Adhesion workability]
Five workers evaluated the ease of adhesive processing when using the adhesive tape of the present invention, i.e., the degree of conformity to curved shapes such as curves of the adhesive part during one-sided adhesive processing, on a seven-point scale (-3 to 3, in 1-point increments). The higher the evaluation score, the better the adhesive workability. The average of the evaluation scores of the five workers was regarded as the evaluation result, and an evaluation result of 1 point or more was regarded as good. The evaluation criteria are shown in Table 1.

[Environmental friendliness]
The ratio of the waste area to the cut cross-sectional area of the tape when adhesive processing was performed using the adhesive tape of the present invention was measured, and evaluated on a 7-point scale (-3 to 3, in 1-point increments) according to the evaluation criteria in Table 1. The higher the evaluation score, the better the environmental friendliness and reduction in material waste loss. An evaluation result of 1 point or more was considered good. The evaluation criteria are shown in Table 1.

[Visibility]
Five workers evaluated the ease of visibility of the adhesive tape when the adhesive tape of the present invention was used for adhesive processing, i.e., the degree of visibility of the position and outline of the adhesive tape body during one-sided adhesive processing, on a 7-point scale (-3 to 3, in 1-point increments). The higher the evaluation score, the better the visibility. The average of the evaluation scores of the five workers was regarded as the evaluation result, and an evaluation result of 1 point or more was regarded as good. The evaluation criteria are shown in Table 1.

[Color uniformity inside and outside the adhesive joint]
Five workers evaluated the color uniformity inside and outside the adhesive joint when the adhesive tape of the present invention was used for bonding, i.e., the degree of shading visible between the adhesive joint and the adjacent area after double-sided adhesive processing, on a 7-point scale (-3 to 3, in 1-point increments). The higher the evaluation score, the less noticeable the shading in the adhesive joint is, i.e., the better the color uniformity inside and outside the adhesive joint is. The average evaluation score of the five workers was taken as the evaluation result, and an evaluation result of 1 point or more was considered good. The evaluation criteria are shown in Table 1.

[Releasability]
Five workers performed adhesion processing using the adhesive tape of the present invention, and the peelability of the release layer, i.e., the ease of peeling when peeling and removing the release layer from the adhesive layer after adhering one side of the adhesive layer of the adhesive tape to an adherend in a single-sided adhesion processing, was evaluated on a 7-point scale (-3 to 3, in 1-point increments). The higher the evaluation score, the better the releasability. The average evaluation score of the five workers was regarded as the evaluation result, and an evaluation result of 1 point or more was regarded as good. The evaluation criteria are shown in Table 1.

[comprehensive evaluation]
The total scores of the evaluation items of appearance quality, adhesive workability, environmental friendliness, visibility, color uniformity inside and outside the adhesive part, and releasability were calculated and used as the overall evaluation. The higher the evaluation score, the better the overall evaluation, and an evaluation result of 9 points or more was considered to be a good adhesive tape or adhesive processed product. The evaluation criteria are shown in Table 2.

Example 1
An adhesive processed product having the shape shown in Fig. 5 was produced. A resin having a softening point of 150°C and a melting point of 199°C, which is a mixture of 70% by mass of polypropylene and 30% by mass of synthetic rubber, was used as component B, and the resin was extruded and stretched into a sheet shape by extrusion so that the film thickness was 50 μm, the stress at 50% elongation was 8.2 MPa, and the breaking strength was 30.5 MPa, to obtain a release layer 1b. The amount of pigment was adjusted so that the visible light transmittance of the release layer 1b was 45%.
Next, a resin mainly composed of a polyester-based polyurethane resin having hot melt adhesive properties with a softening point of 60°C and a melting point temperature of 115°C was used as component A, and the resin was extruded and stretched into a sheet shape by an extrusion method so as to have a film thickness of 100 μm, a stress of 3.4 MPa at an elongation of 50%, and a breaking strength of 26.7 MPa, to obtain an adhesive layer 1a. The amount of pigment blended was adjusted so that the visible light transmittance was 89%.
The obtained adhesive layer 1a was applied in sheet form onto the release layer 1b and laminated to form an adhesive sheet consisting of the adhesive layer 1a and the release layer 1b. The adhesive sheet was then slit to obtain an adhesive tape having a width of 10 cm and a peel strength of 0.18 N/cm.

Next, a taffeta fabric having a warp density of 250 threads/inch and a weft density of 164 threads/inch, consisting of a 17 dtex-7f nylon filament false twisted yarn for the warp and a 26 dtex-20f nylon filament false twisted yarn for the weft, was used as the adherend, and the exposed surface of the adhesive layer 1a of the adhesive tape was placed against the adherend, heated to 100°C with an iron, and one-sided adhesive processing was performed so as to draw a curve with a radius of curvature of 30 cm.
Next, the release layer 1b was peeled off and removed, and the adhesive layer 1a was sandwiched between two adherends as shown in Figure 5, and double-sided adhesive processing was performed using a flat plate hot press under conditions of a temperature of 150°C, a pressure of 200 g/ ^cm2 , and a time of 10 seconds to obtain an adhesive processed product.
The waste rate of the obtained adhesive tape, the ratio of the inner edge length to the outer edge length of the adhesive part, the thickness ratio, and the processing speed were measured.
Next, the appearance quality, adhesion workability, environmental friendliness, visibility, color uniformity inside and outside the adhesive joint, and releasability were evaluated according to the evaluation criteria shown in Table 1, and the overall evaluation was performed according to the evaluation criteria shown in Table 2. Table 3 shows the respective values and the evaluation results.
The adhesive sheet obtained in Example 1 was slit into adhesive tapes with tape widths of 10 mm, 30 mm, and 50 mm, and adherends with radii of curvature of 10 cm, 30 cm, and 40 cm were bonded to one side of the adhesive tapes with different tape widths, and the distortion was evaluated. An image of the distortion evaluation is shown in FIG. 7, and an external appearance photograph is shown in FIG. 9.

Example 2
In the adhesive tape of Example 1, a resin having a softening point of 151°C and a melting point temperature of 206°C, consisting of a mixture of 90% by mass of polypropylene and 10% by mass of synthetic rubber, was used as component B, and the resin was extruded and stretched to a stress of 14.5 MPa at an elongation of 50% and a breaking strength of 56.3 MPa to obtain a release layer. A sheet-shaped adhesive tape was produced in the same manner as in Example 1, and slit processing was performed to obtain an adhesive tape with a width of 30 mm and a peel strength of 0.12 N/cm. An adhesive processed product was produced under the same conditions as in Example 1, except that the curvature radius of the adhesive part was 10 cm. Table 3 shows the respective values and evaluation results.

Example 3
In the adhesive tape of Example 1, a resin having a softening point of 155°C and a melting point temperature of 197°C, which is a mixture of 80% by mass of polypropylene and 20% by mass of synthetic rubber, was used as component B, and a release layer having a stress of 11.4 MPa at 50% elongation, a breaking strength of 51 MPa, and a visible light transmittance of 65% was obtained. A sheet-shaped adhesive tape was produced in the same manner as in Example 1, and slit processing was performed to obtain an adhesive tape with a width of 5 mm and a peel strength of 0.16 N/cm. An adhesive processed product was produced under the same conditions as in Example 1, except that the curvature radius of the adhesive part was 5 cm. Table 3 shows the respective values and evaluation results.

Example 4
In the adhesive tape of Example 1, a resin mainly composed of polyethylene with a softening point of 80°C and a melting point temperature of 150°C was used as component B, and a release layer with a stress of 12.7 MPa at an elongation of 50%, a breaking strength of 22.1 MPa, and a visible light transmittance of 97% was obtained. A sheet-shaped adhesive tape was produced in the same manner as in Example 1, and slit processing was performed to obtain an adhesive tape with a width of 30 mm and a peel strength of 0.09 N/cm. An adhesive processed product was produced under the same conditions as in Example 1, except that the curvature radius of the adhesive part was 30 cm. Table 3 shows the respective values and the evaluation results.

(Comparative Example 1)
In the adhesive tape of Example 1, a resin mainly made of polypropylene with a softening point of 142°C and a melting point of 202°C was used as component B to form a release layer with a film thickness of 400 μm, a stress of 27 MPa at 50% elongation, a breaking strength of 72 MPa, and a visible light transmittance of 65%, and a resin mainly made of polyester polyurethane resin used in Example 1 was used as component A to form an adhesive layer with a film thickness of 30 μm and a stress of 0.5 MPa at 50% elongation, to obtain an adhesive tape with a width of 50 mm and a peel strength of 1 N/cm. The radius of curvature of the adhesive part was 40 cm, and the adhesive processed product was produced so that it was otherwise the same as in Example 1. Table 3 shows the numerical values and evaluation results.

(Comparative Example 2)
In the adhesive tape of Example 1, a resin mainly composed of polyester polyurethane resin with a softening point of 60°C and a melting point temperature of 115°C was used as component B to form a release layer with a film thickness of 50 μm, a stress of 0.5 MPa at 50% elongation, a breaking strength of 26 MPa, and a visible light transmittance of 89%, and a resin mainly composed of polyester polyurethane resin used in Example 1 was used as component A to form an adhesive layer with a film thickness of 30 μm, a stress of 0.5 MPa at 50% elongation, and a breaking strength of 27 MPa, to obtain an adhesive tape with a width of 30 mm. The radius of curvature of the adhesive part was 4 cm, and the adhesive processed product was produced so that it was otherwise the same as in Example 1. The peel strength could not be measured because the break occurred before the peeling of component A and component B. Table 3 shows the respective values and the evaluation results.

(Comparative Example 3)
In the adhesive tape of Example 1, a release paper laminated with polypropylene on both sides of a cellulose paper fiber was used as component B constituting the release layer, forming a release layer with a film thickness of 300 μm, stress at break MPa at 50% elongation, break strength of 45.9 MPa, and visible light transmittance of 19%, and a resin mainly composed of nylon resin with a softening point of 67°C and a melting point temperature of 136°C was used as component A constituting the adhesive layer, forming an adhesive layer with a film thickness of 100 μm, stress at 50% elongation, stress of 18.7 MPa, break strength of 47.5 MPa, and visible light transmittance of 18%, to obtain an adhesive tape with a width of 50 mm and a peel strength of 0.01 N/cm. The radius of curvature of the adhesive part was 10 cm, and an adhesive processed product was produced so that it was the same as Example 1 except for these.
The softening point and melting point of component B constituting the release layer were not measurable because the component did not exhibit a softening point and decomposition occurred before melting. Table 3 shows the respective values and the evaluation results.
The adhesive sheet obtained in Comparative Example 3 was slit into adhesive tapes with tape widths of 10 mm, 30 mm, and 50 mm, and adherends with radii of curvature of 10 cm, 30 cm, and 40 cm were bonded to one side of the adhesive tapes with different tape widths, and the distortion was evaluated. Figure 8 shows an image of the distortion evaluation, and Figure 10 shows a photograph of the appearance.

(Comparative Example 4)
In the adhesive tape and adhesive processed product of Comparative Example 3, an adhesive sheet consisting of an adhesive layer and a release layer was formed, and then the adhesive sheet was cut using a laser cutter along the curved shape of the adhesive part to obtain an adhesive tape with a curvature radius of 4 cm, a tape width of 4 mm, and a peel strength of 0.01 N/cm. The curvature radius of the adhesive part was set to 4 cm, and the adhesive processed product was otherwise identical to Comparative Example 3. Table 3 shows the numerical values and evaluation results.

The adhesive tapes and adhesive processed products of Examples 1 to 4 were adhesive tapes and adhesive processed products with excellent appearance quality, adhesive workability, environmental friendliness, color uniformity inside and outside the adhesive part, and release property by setting the stress at 50% elongation of the adhesive layer and release layer and the peel strength of the adhesive layer and release layer within preferred ranges. The adhesive tapes and adhesive processed products of Examples 1 and 2 were adhesive tapes and adhesive processed products with further excellent visibility by setting the visible light transmittance of the adhesive layer and release layer within preferred ranges.
Moreover, according to Example 3 and Figs. 7 and 9, it was confirmed that by using the adhesive tape of the present invention having a curved adhesive part with a radius of curvature in the range of 5 cm to 30 cm and a tape width in the range of 5 mm to 30 mm, an adhesive processed product without wrinkles or distortion can be obtained.

The adhesive tape and adhesive processed product of Comparative Example 1 had a high stress at 50% elongation of the release layer, a high peel strength of the adhesive layer and release layer, and a high yield point stress of the adhesive tape, resulting in an adhesive tape and adhesive processed product with poor adhesive workability and releasability.
The adhesive tape and adhesive processed product of Comparative Example 2 had a low stress at 50% elongation in the adhesive layer and release layer, a high visible light transmittance in the release layer, and a small radius of curvature in the adhesive part, resulting in an adhesive tape and adhesive processed product with poor visibility, adhesive workability, and releasability.
The adhesive tape and adhesive processed product of Comparative Example 3 had a high stress at 50% elongation of the release layer and a high yield point stress of the adhesive tape, and also had low peel strengths of the adhesive layer and release layer, a low visible light transmittance of the adhesive layer, and a wide width of the adhesive tape, resulting in an adhesive tape and adhesive processed product that were inferior in appearance quality, adhesive workability, color uniformity inside and outside the adhesive part, and releasability.
7 to 10 show that, compared with the adhesive sheet of Example 1, the adhesive processed product using the adhesive sheet of Comparative Example 3 has more wrinkles and is more likely to become distorted.
The adhesive tape and adhesive processed product of Comparative Example 4 were subjected to molding and cutting as a countermeasure to the poor appearance quality and adhesive workability of Comparative Example 3, and while this improved the appearance quality and adhesive workability, it resulted in a large waste loss rate and an adhesive tape and adhesive processed product that were inferior in environmental friendliness.
That is, the more requirements of the invention the adhesive tape and adhesive processed product satisfy, the more excellent the adhesive tape and adhesive processed product will be overall.

The present invention can be used as adhesive tape and adhesive processed products for clothing, miscellaneous goods, bedding, and industrial materials.

1: Adhesive tape 1a: Adhesive layer 1b: Release layer 2, 2': Adherend 3: Tape width 4: Adhesive portion 5: Radius of curvature 6: Outer edge portion 7: Inner edge portion 8: Thickness 8a: Thickness at outer edge portion 8b: Thickness at inner edge portion 9: Adhesive processed product

Claims (8)

An adhesive layer made of component A;
a release layer comprising component B and covering one side of the adhesive layer;
wherein the stress of the release layer at 50% elongation is in the range of 1 MPa to 25 MPa, the stress of the adhesive layer at 50% elongation is in the range of 1 MPa to 6 MPa, and the peel strength between the adhesive layer and the release layer is in the range of 0.05 N/cm to 0.5 N/cm. The adhesive tape according to claim 1, wherein component A is a thermoplastic hot melt. The softening point T _B1 of the component B is 100° C. or higher,
The softening point T _A1 of the component A is less than 100° C.,
3. Adhesive tape according to claim 1, characterized in that the softening point ratio (T _B1 /T _A1 ) is in the range of 2-5. The melting point temperature T _B2 of the component B is higher than the melting point temperature T _A2 of the component A,
4. Adhesive tape according to claim 1, characterized in that the ratio of the melting point temperatures (T _B2 /T _A2 ) is in the range of 1.5 to 2.5. The visible light transmittance VT _B of the component B is 75% or less,
The visible light transmittance VT _B rate of the component A is 60% or more,
5. The adhesive tape according to claim 1, wherein the visible light transmittance ratio (VT _B /VT _A ) is 80% or less. 6. The adhesive tape according to claim 1, wherein the breaking strength BS _B of said component B is higher than the breaking strength BS _A of said component A, and the breaking strength ratio (BS _B /BS _A ) is 1 or more. The adhesive tape has a yield point elongation of 25% to 27%;
The yield stress is 7 MPa to 16 MPa,
7. The adhesive tape according to claim 1, wherein the lower yield stress is from 7 MPa to 16 MPa. An adhesive processed product using the adhesive tape according to any one of claims 1 to 7,
The adhesive processed product has an adhesive part consisting of at least an adherend and an adhesive layer of the adhesive tape,
The adhesive portion has at least a part of a curved shape with a radius of curvature in the range of 5 cm to 30 cm,
The width of the adhesive tape is in the range of 5 mm to 30 mm;
A bonded product, characterized in that the ratio of the maximum thickness to the minimum thickness (maximum thickness/minimum thickness) of the thickness at the outer edge portion in the longitudinal direction of the curved shape of the bonded portion to the thickness at the inner edge portion is in the range of 101 to 150%.

Images