Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J201/00—Adhesives based on unspecified macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F3/00—Labels, tag tickets, or similar identification or indication means; Seals; Postage or like stamps
  • G09F3/08—Fastening or securing by means not forming part of the material of the label itself
  • G09F3/10—Fastening or securing by means not forming part of the material of the label itself by an adhesive layer

Definitions

• the technology disclosed in this specification relates to a pressure-sensitive adhesive sheet in which a printed portion is provided on at least one surface of the pressure-sensitive adhesive layer.
• Adhesive sheets equipped with an adhesive layer are used in a variety of fields, such as for fixing components of electronic devices, screen protection sheets, wallpaper and other construction materials, printed materials and laminated sheets for printed materials, and various tapes.
• the pressure-sensitive adhesive sheet there are cases where it is desired that the adhesive sheet stick firmly to the adherend and not be easily peeled off, and cases where it is desired that it be easy to reapply when pasting.
• Patent Document 1 discloses that a graphic adhesive sheet that is easy to reapply is created by forming a non-adhesive polymer having a predetermined pattern on the adhesive surface of the adhesive layer. It describes what you can do.
• the adhesive force of the adhesive sheet to the adherend is better to be stronger, and in other cases, it is better to be weaker.
• adhesive sheets that are easy to reapply and are difficult to peel off after pasting, but other properties may be required.
• properties such as adhesive strength and ease of application and peeling can be easily controlled by appropriately changing the thickness of the adhesive layer, the thickness of the printed part, etc.
• FIG. 1 is a cross-sectional view showing an example of a pressure-sensitive adhesive sheet according to an embodiment of the present disclosure.
• FIG. 2 is a plan view of the adhesive sheet shown in FIG. 1 when viewed from the printing section side.
• FIG. 3 is a photographic diagram showing an enlarged printing section in area A shown in FIG. 2.
• FIG. 4 is a sectional view showing a pressure-sensitive adhesive sheet according to a first modification of the present disclosure.
• FIG. 5 is a plan view schematically showing a method of printing a pressure-sensitive adhesive sheet according to a second modification of the present disclosure.
• FIG. 6 is a diagram showing microscopic photographs of the adhesive sheets of Examples 1 to 3 in which the thickness of the printed part is 2 ⁇ m (ink amount K10%), and the measurement results of the number of dots and dot size in the printed part.
• FIG. 1 is a sectional view showing an adhesive sheet 10, which is an example of an embodiment disclosed in this specification, and FIG. 2 is a plan view of the adhesive sheet 10 of this embodiment when viewed from the printing unit 5 side It is a diagram.
• FIG. 3 is a photographic diagram showing an enlarged printing section in area A shown in FIG. 2.
• the adhesive sheet 10 of this embodiment has very little tack when no load is applied, it can be stored in a roll even when the release liner 7 is not provided.
• the release liner 7 is not provided, there are advantages such as saving resources and reducing the diameter of the roll.
• the loop tack value of the adhesive layer 3 with respect to the stainless steel (SUS) plate can be made less than 1.0 N/25 mm. Can be done.
• the adhesive force of the adhesive layer 3 to the SUS steel plate after 24 hours at 23°C, a load of 2 kg during bonding, a relative humidity of 50%, and a peeling angle of 180 degrees is 0.05 N/25 mm or more. good.
• the adhesive sheet 10 can be fixed by applying a load to the sheet. This makes the pasting process easy.
• the adhesive surface has minute irregularities before pasting, air bubbles are less likely to enter during pasting, and air remaining between the adhesive and the adherend after crimping can be easily expelled.
• the adhesive sheet 10 of this embodiment by changing the thickness of the printed portion 5, etc., it is possible to adjust the tack value and adhesive force to desired values even when using the same adhesive. Become. For example, it becomes possible to produce a slightly adhesive sheet using an inexpensive strong adhesive type adhesive instead of using a relatively expensive slightly adhesive type adhesive.
• the adhesive sheet 10 of the present embodiment by applying a load after bringing the adhesive layer 3 into contact with an adherend, seepage of the constituent components (adhesive components) of the adhesive layer 3 can be promoted. In addition, by leaving it in a state where it is peeled off from the adherend, the adhesive component that has once oozed out can be quickly restored to its pre-pressing state by its elastic force. Therefore, the adhesive sheet 10 can be used repeatedly.
• the adhesive sheet 10 can also be used, for example, as a temporary fixing sheet such as a sticky note.
• the first tack value for the SUS steel plate of the adhesive layer 3 occurs in the printing area 12 immediately after applying a load of 300 g/cm 2 for 10 seconds using the pressing means, and after applying the load, the first tack value is generated from the pressing means.
• the first tack value is generated from the pressing means.
• the second tack value smaller than the first tack value may remain.
• the third tack value for the SUS steel plate of the adhesive layer 3 occurs, and the adhesive layer 3 peels off from the pressing means after the application of the load.
• either the tack on the PET film may disappear, or a fourth tack value smaller than the third tack value may remain.
• the storage elastic modulus G' of the adhesive layer 3 at 23° C. and a frequency of 1 Hz may be 1.0 ⁇ 10 4 Pa or more and 5.0 ⁇ 10 6 Pa or less, and 9 It may be .0 ⁇ 10 4 Pa or more and 2.0 ⁇ 10 6 Pa or less.
• the storage modulus represents the hardness of the adhesive layer 3, and the inventors of the present invention have found that as the storage modulus decreases, the adhesive layer 3 tends to flow more easily, and the adhesive component tends to ooze out from the printed area 5. I know it will happen.
• the storage modulus is 5.0 ⁇ 10 6 Pa or less, the tack can be kept small and the adhesive strength can be exerted to the extent that it does not easily peel off after being attached to an adherend.
• the storage elastic modulus of the adhesive layer 3 is 1.0 ⁇ 10 4 Pa or more, the adhesive component can be exuded by making the printed part 5 have an appropriate thickness, and the storage elastic modulus is 9.
• the pressure is 0 ⁇ 10 4 Pa or more, it is easy to restore the state to a state with small tack after applying a load to cause tack, and therefore it becomes easy to use repeatedly.
• the storage elastic modulus of the adhesive layer 3 is 1.5 ⁇ 10 5 Pa or more, the holding power of the adhesive layer 3 described later can be improved.
• the glass transition temperature (Tg) of the adhesive layer 3 may be ⁇ 50° C. or higher. In this case, when the pressure-sensitive adhesive sheet 10 is used at room temperature, the pressure-sensitive adhesive layer 3 has appropriate fluidity, so that the constituent components of the pressure-sensitive adhesive layer 3 are likely to ooze out from the printed area 5.
• the holding force duration at 40°C may be 1000 seconds or more, and the amount of deviation (mm /50,000 seconds) is preferably 1 mm or less. If the adhesive sheet 10 has excellent holding power, it will be less likely to peel off or fall off from an adherend when used, for example, as a label, a graphic sheet, or the like.
• the holding power of the adhesive sheet 10 can be fully demonstrated by applying appropriate pressure by hand, roller, etc. after bonding it to an adherend. This is because the amount of adhesive component seeping out from the printing section 5 increases due to pressurization. When the adhesive component oozes out from the printed area 5, the amount of displacement of the adhesive sheet 10 becomes smaller as the adhesive layer 3 has a stronger cohesive force.
• the printing section 5 is composed of a large number of dots 15 made of cured ink.
• the diameter of the dots 15 is not particularly limited, but may be, for example, 0.1 ⁇ m or more and 100 ⁇ m or less, 0.1 ⁇ m or more and 50 ⁇ m or less, or 1 ⁇ m or more and 30 ⁇ m or less.
• the diameter of the dots 15 depends on the printing press used. If the dot diameter is 50 ⁇ m or less, it becomes easier to precisely control the tack and adhesive force of the adhesive sheet 10.
• the diameters of the dots 15 may be uniform, but may also have moderate variations.
• the printing section 5 may include an average of five or more dots 15 per 0.5 mm square. The larger the dot diameter, the easier it is to reduce the loop tack value even if the density (number density) of the dots 15 is small.
• the average thickness of the printed portion 5 may be approximately 0.1 ⁇ m or more and 20 ⁇ m or less, preferably 1 ⁇ m or more and 6 ⁇ m or less. If the average thickness of the printed area 5 is less than 0.1 ⁇ m, the gaps between the dots 15 will become large, and a large amount of adhesive component will easily seep out from these gaps, which will reduce the tack strength and adhesive force of the adhesive sheet 10. This is almost the same as the case where dots 15 are not provided.
• the thickness of the printed portion 5 exceeds 20 ⁇ m, the amount of components of the adhesive layer 3 that seep out may become small, making it difficult to attach it to an adherend.
• the types of adhesives that can be used as the main ingredient of the adhesive layer 3 can be further expanded.
• the total light transmittance of the adhesive sheet 10 will be 50% or more even if black ink or color ink is used to form the printed portion 5. It is semi-transparent. However, by making the thickness of the printing section 5 greater than 6 ⁇ m and less than 20 ⁇ m, it becomes possible to form a desired image with the printing section 5 while keeping the loop tack value less than 1.0 N/25 mm.
• the dots 15 may be arranged regularly or irregularly.
• the dots 15 are arranged irregularly. Further, the sizes of the dots 15 constituting the printing section 5 may be the same, but may also be non-uniform.
• the ink used to form the printed portion 5 is not limited, and one or more types of ink selected from photo-curable ink, electron beam-curable ink, and solvent-based ink can be used; If it is a photo-curable ink or electron beam-curable ink that is cured by UV) or visible light, the ink can be difficult to diffuse into the adhesive layer 3 when forming the printed part 5, and the thickness required for the printed part 5 can be reduced. This is preferable because it is easier to secure. Furthermore, since UV curable ink and electron beam curable ink can be cured instantly after printing, the production time of the adhesive sheet 10 can be reduced by using these inks compared to the case where solvent-based ink is used. Can be shortened.
• the color of the ink used to form the printing section 5 is not particularly limited, and may be only black (K), for example, cyan (C), magenta (M), yellow (Y), and black (K). , white (W), gray, light cyan, light magenta, red, and transparent, or a combination of a plurality of colors may be used.
• K black
• M magenta
• Y yellow
• K black
• W white
• gray light cyan
• light magenta light magenta
• red red
• transparent or a combination of a plurality of colors
• the thickness of the printed portion 5 may be the same as when using one color of ink.
• the printing section 5 can be formed by a printing method in which ink is ejected using a known inkjet printer or the like.
• the printed portion 5 is formed by solid printing such as offset printing, gravure printing, or silk screen printing, the adhesive layer 3 will be covered without any gaps, and the adhesive component will not be able to seep out.
• halftone dots with a diameter of 0.1 ⁇ m or more and 50 ⁇ m or less, which is about the same as the dots 15, are formed in the printing area 12 by offset printing or gravure printing, the components in the adhesive layer 3 cannot be realized. It is possible.
• using an inkjet printer eliminates the need to create plates, allowing you to freely change the density and formation position of the dots 15 in a short time. can do.
• the surface roughness (Ra) of the printed portion 5 may be 0.3 ⁇ m or more and 10 ⁇ m or less. Since the printing section 5 is composed of a large number of dots 15, when the printing section 5 is not provided, the surface roughness is greater than when a printing section is provided by offset printing or silk screen printing.
• the adhesive used for forming the adhesive layer 3 is a medium adhesive type or a strong adhesive type.
• a pressure-sensitive adhesive it is possible to produce a pressure-sensitive adhesive sheet 10 that exhibits a wide range of adhesive strength.
• a strong adhesive type adhesive by setting the printed area 5 thicker, it is possible to create an adhesive sheet 10 that exhibits slight adhesiveness in the printed area 12, and by reducing the thickness of the printed area 5, It also becomes possible to produce a pressure-sensitive adhesive sheet 10 that exhibits tackiness.
• the adhesive used to form the adhesive layer 3 is not particularly limited, but includes, for example, acrylic adhesive, acrylic-urethane adhesive, urethane adhesive, silicone adhesive, polyester adhesive, and rubber adhesive. It may be one kind or a mixture of two or more kinds selected from these agents. As the adhesive used, water-based adhesives, solvent-based adhesives, solvent-free adhesives, etc. can be used.
• the thickness of the adhesive layer 3 is not particularly limited, but may be about 10.0 times or less the average thickness of the printed portion 5.
• the thickness of the adhesive layer 3 may be, for example, 0.5 ⁇ m or more and 100 ⁇ m or less, or 2 ⁇ m or more and 50 ⁇ m or less. If the thickness of the adhesive layer 3 is within this range, it becomes easy to set the loop tack value and adhesive force within the desired range in the printing area 12 as well.
• the loop tack value and adhesive strength increase as the thickness of the adhesive layer 3 increases. This is thought to be because the thicker the adhesive layer 3 is, the more easily the adhesive component oozes out from the printed area 5 due to the pressure applied during bonding after the printed area 5 is formed.
• the adhesive layer 3 may contain additives such as a tackifier, an antistatic agent, a coloring agent, and a filler, if necessary. At least one of the adhesive and the additive for forming the adhesive layer 3 may contain a biological component.
• the adhesive layer 3 may contain about 10% by mass or more and 50% by mass or less of a terpene-based or rosin-based tackifier.
• the biomass degree of the adhesive layer 3 may be, for example, about 10% or more and 50% or less.
• the base material known materials such as resin sheets, synthetic paper, paper, nonwoven fabrics, woven fabrics, etc., and laminates thereof can be used.
• the constituent materials of the resin sheet include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polyimide (PI), etc. can be used.
• the thickness of the base material 1 is not particularly limited, but may be, for example, about 2 ⁇ m or more and 300 ⁇ m or less, or 5 ⁇ m or more and 250 ⁇ m or less. At least one surface of the base material 1 may be provided with an easily adhesive layer or an antistatic layer, if necessary.
• a biomass material or a recycled material may be used partially or entirely in order to reduce the environmental load.
• FIG. 4 is a cross-sectional view showing an adhesive sheet 20 according to a first modification of the present disclosure.
• the adhesive sheet 20 according to the present modification includes an adhesive layer 3 and a printed portion 5 formed on at least one surface of the adhesive layer 3, from which constituent components of the adhesive layer 3 seep out. It is equipped with The adhesive sheet 20 according to this modification differs from the adhesive sheet 10 shown in FIG. 1 in that the base material 1 is not provided.
• a release liner 7 is bonded to the surface of the adhesive layer 3 on which the printed portion 5 is provided, and a second release liner 17 is bonded to the other surface of the adhesive layer 3.
• the peeling force required to peel off the release liner 7 and the peeling force required to peel off the second release liner 17 may be approximately the same, but it is possible to make a difference between them and use the release liner on the light release side. It may be made so that it can be easily peeled off.
• the other configurations of the adhesive sheet 20 are basically the same as those of the adhesive sheet 10.
• the printed portion 5 may be formed after manufacturing and pasting the adhesive layer 3 on the adherend.
• the adhesive strength of the surface (first surface) on the side where the printed portion 5 of the adhesive layer 3 is provided is the same as that of the surface (second surface) on the opposite side to the same adherend.
• the adhesive force is smaller than that of .
• the loop tack value of the first surface of the adhesive layer 3 is smaller than the loop tack value of the second surface. Therefore, it is possible to realize a double-sided adhesive sheet having different adhesive strengths on one side and the other side of the adhesive layer 3.
• the adhesive used in the adhesive sheet 20 according to this modification is not particularly limited.
• the area of the adherend that is substantially in contact with the adhesive component is smaller than on the opposite side, so that the adherend is less likely to be contaminated by the adhesive.
• the adhesive sheet 20, like the adhesive sheet 10, can be used in various fields.
• pressure-sensitive adhesive sheet in which pressure-sensitive adhesive layers are provided on both sides of a core material, and a printed portion is provided on at least one pressure-sensitive adhesive layer.
• FIG. 5 is a plan view schematically showing a method of printing a pressure-sensitive adhesive sheet 30 according to a second modification of the present disclosure.
• the adhesive sheet 30 according to this modification differs from the adhesive sheet 10 shown in FIG. 1 in that a plurality of printing areas are provided on the adhesive layer 3 within the sheet.
• a first print area 12A and a second print area 12B are formed on the adhesive layer 3 provided on one surface of the base material 1.
• a first printing section 5A formed of a cured ink is provided on the first printing area 12A, and a second printing section 5B is provided on the second printing area 12B.
• the average thickness of the first printed portion 5A and the second average thickness may be the same or different.
• a part of the adhesive layer 3 may not be covered by the printed part and may be exposed.
• the total area of the printing area may be 1% or more and 100% or less of at least one surface of the adhesive layer 3. If the print area is less than 1%, the adhesive strength and loop tack value of the adhesive sheet as a whole will be approximately the same as those without the print area, so the effect of forming the print area will be weakened.
• the planar shape of the first printing area 12A and the second printing area 12B may be a strip shape in which the flow direction (coating progress direction) is longer than the width direction, as shown in FIG. 5, or may be in any other shape. There may be. Further, the size of each printing area is not particularly limited.
• the thickness of the first printed part 5A on the first printed area 12A and the thickness of the second printed part 5B on the second printed area 12B do not need to be constant, and may differ partially. You can leave it there.
• the thickness of the first printed portion 5A and the second printed portion 5B may decrease in a gradation pattern from the outside to the inside in the width direction. Thereby, in the first printing area 12A and the second printing area 12B, it is possible to design the adhesive force to become stronger as it goes inward from the end.
• a known line inkjet printer can be used. After forming the adhesive layer 3 on one side of the base material 1 using a coating machine and drying it, for example, UV curing is applied to the exposed surface of the adhesive layer 3 from the head 23 of a line inkjet printer extending in the width direction.
• the first printing section 5A and the second printing section 5B are formed by ejecting ink and then UV irradiation. Note that if a long printing time is acceptable, the printing section may be formed using a serial head type inkjet printer.
• the adhesive sheet 30 may be aged at 40° C. for about 3 days, or aging may be performed in advance before forming the printed portion. Alternatively, the printed portion may be formed after cutting the adhesive sheet to a desired size using a slitter before forming the printed portion.
• a slitter is used to cut the adhesive sheet 30 in the machine direction.
• a printing area 12A By separating the adhesive sheet into three areas: a printing area 12A, a second printing area 12B, and an area where no printing area is provided, it becomes possible to produce three types of adhesive sheets with one coating. Thereafter, by cutting the produced adhesive sheet in the width direction, a lithographic pressure-sensitive adhesive sheet of a desired size can be produced.
• the adhesive strength at both ends in the width direction is equal to that of the central part.
• a pressure-sensitive adhesive sheet with weaker adhesive force can be produced. With this adhesive sheet, if it becomes necessary to peel off the adhesive sheet after it has been pasted on an adherend, it can be easily peeled off from the adherend by peeling from the end where the adhesive strength is weak. .
• an inkjet printer it is possible to arbitrarily adjust the thickness and formation position of the printed area without creating a plate.
• the pressure-sensitive adhesive sheet 10 of the present embodiment shown in FIG. 1 and the pressure-sensitive adhesive sheets 20 and 30 according to its modified examples are stored and when an order is received from a customer.
• printing parts that exhibit tack and adhesive strength according to customer requests can be formed on demand, reducing the amount of product inventory compared to storing adhesive sheets with different tack and adhesive strengths. can be significantly reduced.
• the adhesive sheet 10 of the present embodiment and the adhesive sheets 20 and 30 according to the modified examples described above are examples of the present invention, and the constituent materials and thickness of the base material 1, adhesive layer 3, printed part 5, etc.
• the shape, formation position, etc. can be changed as appropriate without departing from the spirit of the present invention.
• adhesive compositions A and B were coated onto the release agent layer of a commercially available release liner having a PET film having a thickness of 50 ⁇ m and on which a release agent layer containing a silicone release agent was formed using a known comma-type coater.
• E was applied and dried to form an adhesive layer.
• the thickness of the adhesive layer formed using adhesive compositions A and B was 10 ⁇ m and 20 ⁇ m, and the thickness of the adhesive layer formed using adhesive composition E was 10 ⁇ m.
• the coated side of the release liner was bonded to one side of the base material to transfer the adhesive layer onto the base material, and then aged at 40° C. for about 3 days to form a pressure-sensitive adhesive sheet.
• Comparative Examples 1 to 4 are various pressure-sensitive adhesive sheets without a printed part.
• adhesive compositions C and D adhesive sheets with adhesive layer thicknesses of 10 ⁇ m, 20 ⁇ m, and 30 ⁇ m were coated directly onto the substrate using a comma-type coater in Comparative Examples 5 to 10. It was created as
• This tablet was placed between the plates of a rheometer (product name: AR2000ex), and the storage modulus G' and loss modulus G'' were measured at a frequency of 1 Hz, a strain amount of 0.05%, and a measurement temperature of -40 to 100°C. was measured. Moreover, the value of loss elastic modulus G''/storage elastic modulus G' was calculated as a loss tangent. The temperature at which the loss tangent was maximum was read as the glass transition temperature of the adhesive layer.
• ⁇ Measurement of thickness of printed part> On a PET film with a thickness of 50 ⁇ m, ink amounts were set to K10%, K20%, K30%, K40%, and K50% using a UV inkjet printer (“UJF-6042MkII” manufactured by Mimaki Engineering Co., Ltd.). A printed part was formed. The total thickness of each sheet sample was measured using a constant pressure thickness measuring device, and the thickness of each printed portion was calculated by subtracting the thickness of the PET film (50 ⁇ m) from the measured value.
• the thickness of the printed area (ink thickness) is approximately 2 ⁇ m at 10% K, the thickness of the printed area is approximately 3 to 4 ⁇ m at 20% K, the thickness of the printed area is approximately 5 ⁇ m at 30% K, and the thickness of the printed area is approximately 5 ⁇ m at 40% K.
• the thickness of the printed part was about 7 ⁇ m, K was 50%, and the thickness of the printed part was about 10 ⁇ m.
• the adhesive sheet whose adhesive surface was exposed by peeling off the release liner was attached to a SUS steel plate polished with 360 degree waterproof paper by a method conforming to JIS Z 0237, and the adhesive force was measured. Specifically, a test piece of an adhesive sheet cut to a width of 25 mm was pasted on a SUS steel plate as an adherend, and then pressed with a 2 kg roller twice in a reciprocating manner, and then heated at 23°C and a relative humidity of 50% for 20 minutes or It was left standing for 24 hours. The adhesive force (N/25 mm) was measured as the force required to peel these test pieces from the SUS steel plate using a universal material testing machine under conditions of a peel angle of 180° and a peel rate of 300 mm/min.
• the release liner After cutting out a test piece with a width of 25 mm and a length of 150 mm from the adhesive sheet, the release liner is peeled off and the release liner is divided into two pieces.
• the divided release liners each having a width of 25 mm were attached to each other so as to cover only 25 mm from both ends of the exposed surface of the adhesive layer (100 mm of the adhesive layer of the test piece was left exposed).
• the test piece was set in a loop shape on the upper grip part of the tensile testing machine so that the adhesive side was facing outside.
• the upper grip part After setting the SUS steel plate on the lower grip part of the tensile testing machine, the upper grip part is lowered at a speed of 300 mm/min until the height from the lower grip part is 20 mm, and the adhesive surface of the test piece and the SUS It was brought into contact with a steel plate. Immediately after contact, the upper grip part was raised to its original position at a speed of 300 mm/min, and the maximum value of the tensile load required to peel off the test piece from the SUS steel plate was measured. The measurement was repeated three times, and the average of the measurements was recorded as the loop tack value. The measurements were performed under conditions of 23° C. and 50% relative humidity.
• ⁇ Restoration test> The adhesive sheet from which the release liner had been removed was placed on an electronic balance, and the bottom surface of a stainless steel cylinder (pressing means) was pressed against the adhesive surface on which the printed portion was formed. After applying a predetermined load for 10 seconds to confirm the presence or absence of tack, a PET film was attached to the adhesive surface after a period of time.
• the loads due to the cylinders were 300 g/cm 2 , 1000 g/cm 2 , and 2000 g/cm 2 , respectively. In each case, the time from peeling off the cylinder until the PET film no longer stuck to the adhesive surface was measured.
• a test piece with a width of 25 mm and a length of 100 mm was cut out from the adhesive sheet, and a square portion of 25 mm x 25 mm at one end of this test piece was attached to a SUS steel plate.
• the square portion attached to the SUS steel plate was strongly crimped with uniform force using a squeegee.
• the SUS steel plate was held vertically so that the square part of the adhesive sheet was located above, and in this state, a 1 kg weight was suspended from the other end of the adhesive sheet located below. In this state, the time until the adhesive sheet was completely peeled off was measured as the retention force duration. In addition, the amount of displacement of the adhesive sheet (unit: mm) after 50,000 seconds had elapsed from the start of the measurement was measured as a value representing the holding force. Note that the measurement was performed at 40°C.
• Table 1 shows the storage modulus, loss modulus, loss tangent, and glass transition temperature of the adhesive compositions A to E after curing that form the adhesive layer.
• Tables 9 to 12 show the results of the tack restoration test.
• FIG. 6 shows the measurement results and micrographs of the number of dots and dot size (dot diameter) in the printed part of the adhesive sheet where the printed part thickness is 2 ⁇ m.
• the ink amount was K10% (the thickness of the printed area was about 2 ⁇ m), it was confirmed that the printed area was composed of many dots of various sizes.
• the K value expressed as a percentage is a value indicating the amount of ink, and is a term used in the dedicated software of the UV inkjet printer used this time. It was confirmed that the average number of dots of different sizes included in a 0.5 mm square area was 5 or more for all test pieces.
• the dot diameter was approximately 23 ⁇ m to 30 ⁇ m for large dots and approximately 14 ⁇ m to 18 ⁇ m for small dots. Note that it is thought that the density of dots increases as the amount of ink increases, but when the amount of ink exceeds K30%, the overlap between dots increases, making it difficult to count the number of dots.
• the adhesive sheet disclosed in this specification can be used in various fields as a label or graphic sheet, a member fixing sheet, various protective sheets, a temporary fixing sheet for articles, etc.
• Base material 3 Adhesive layer 5 Printing section 5A First printing section 5B Second printing section 7 Release liner 10, 20, 30 Adhesive sheet 12 Print area 15 Dots 17 Second release liner 20 Adhesive sheet 23 Head

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• 2023
  • 2023-05-01 JP JP2023553092A patent/JP7461690B1/ja active Active
  • 2023-05-01 CN CN202380038144.3A patent/CN119173599A/zh active Pending
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