TWI761306B - adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive sheet with less performance degradation due to narrowing. The adhesive sheet provided by the present invention has an adhesive layer on at least one surface of the foam substrate. In the above-mentioned adhesive sheet, the relationship between the 100% modulus M [N/mm ² substrate] of the adhesive sheet and the density D [g/cm ³ ] of the above-mentioned foam substrate satisfies the following formula: 9.0≦(M /D).

Description

adhesive sheet

The present invention relates to an adhesive sheet provided with a foam base material.

This application claims priority based on Japanese Patent Application No. 2015-120669 filed on June 15, 2015 and Japanese Patent Application No. 2016-112701 filed on June 6, 2016, all contents of these applications is incorporated into this specification by reference.

In general, adhesives (also known as pressure-sensitive adhesives. The same below) have the following properties: they exhibit a soft solid (viscoelastic) state in the temperature region around room temperature, and are simply adhered to the is attached to the body. Taking advantage of such properties, adhesives are widely used in various fields for bonding or fixing purposes, for example, in the form of a substrate-attached adhesive sheet in which an adhesive layer is provided on at least one surface of the substrate.

Compared with the adhesive sheet with a plastic film without a cell structure as the base material, an adhesive sheet with a base material (adhesive sheet with a foam base material) is used as the base material. Therefore, it can be advantageous in terms of shock absorption property and unevenness followability. Moreover, compared with the adhesive sheet which uses a nonwoven fabric as a base material, it can become advantageous in water resistance, sealing property, etc.. Therefore, the adhesive sheet with the foam base material can be preferably used for bonding or fixing parts in portable electronic machines. Patent Document 1 and Patent Document 2 are listed as technical documents related to the adhesive sheet with a foam base material.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2013/154137

[Patent Document 2] Japanese Patent Application Laid-Open No. 2013-213104

In recent years, from the viewpoint of miniaturization and weight reduction of in-house products, narrowing of the adhesive sheet used for joining parts and the like has been demanded. For example, for an adhesive sheet used for fixing a protective member (eg cover glass) of a display part of a portable electronic device, from the viewpoints of increasing the size of the information display part, improving the designability, and improving the degree of freedom of design, etc. Considering it, it is meaningful to narrow the width of the adhesive sheet.

However, when the width of the adhesive sheet is narrowed, there is a tendency that the bonding performance (for example, the pressing force) of the parts decreases. In this regard, the inventors of the present invention have focused on the following point: when the width of the adhesive sheet is about 1 mm or less, a phenomenon is observed, that is, the decrease in bonding performance exceeds the bonding area due to the narrowing of the width. reduce the expected extent. The present invention has been made in view of this fact, and an object thereof is to provide an adhesive sheet with less reduction in performance due to narrowing.

An adhesive sheet provided by this specification has an adhesive layer on at least one surface of a foam base material, and the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet and the above-mentioned foam base The relationship of the density D [g/cm ³ ] of the material satisfies 9.0≦(M/D). The adhesive sheet having a higher 100% modulus M in comparison with the density D as described above can be suppressed in the degree of performance degradation caused by the narrowing. In addition, M in the above formula represents the adhesive sheet in the unit of N/mm ² base material (here, the so-called "/mm ² base material" means "the cross-sectional area per 1 mm ² of the foam base material") The numerical part of the 100% modulus, and M itself is a dimensionless number (the same as M in other formulas described in this specification). In addition, D in the above formula is a numerical value when the density of the foam base material is expressed in the unit of g/cm ³ , and D itself is a dimensionless number (the same D in other formulas described in this specification) . However, when describing the preferable numerical range of M or D, etc. in this specification, in order to make it easy to read, there are cases where these numerical values are expressed in units with exact units (the same applies to other symbols).

Another adhesive sheet provided by this specification has an adhesive layer on at least one side of the foam base material, and the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet and the above-mentioned foam The relationship of the thickness Hs [mm] of the base material satisfies 0.75<M×Hs. Adhesive sheets having such properties show strong resistance to elongation (tensile deformation). Therefore, even if the width is narrowed, damage to the joint portion (peeling of the adhesive sheet, breakage of the foam base material, etc.) due to impact tends to be less likely to occur, which is preferable.

In another preferred aspect, the 100% modulus M of the above-mentioned adhesive sheet is preferably higher than 4.0 N/mm ² of the base material. It is shown that the adhesive sheet of such 100% modulus M has a tendency to be less likely to cause damage to the junction due to impact even if the width is narrowed, so it is preferable.

The adhesive sheet disclosed here can be preferably implemented in a state in which the thickness Hs of the above-mentioned foam base material is 0.06 mm to 0.30 mm (eg, 0.10 mm to 0.30 mm). According to the adhesive sheet having the foam base material of such a thickness, the thickness reduction of the joint portion and the good impact resistance can be achieved in a well-balanced manner.

A preferred aspect of the adhesive sheet is that the relationship between the pressing and bonding force S _1.0 [N] when the width is 1.0 mm and the pressing and bonding force S _0.3 [N] when the width is 0.3 mm satisfies the following formula: 0.3≦S _0.3 /S _1.0 . As described above, the pressure-sensitive adhesive sheet having a smaller reduction in the pressure-bonding force as the width of the adhesive sheet is narrowed can be suitably used, for example, in the form of a portion having a width of less than 1.0 mm in at least one portion (typically, The form of the joint member with a linear portion less than 1.0mm in width).

The adhesive sheet disclosed herein is typically constructed in the form of a double-sided adhesive sheet having adhesive layers on both sides of the above-mentioned foam substrate. The adhesive sheet in this form (double-sided adhesive sheet with foam base material) has the following advantages: the use of the adhesive sheet for joining or fixing parts is good in workability.

The adhesive sheet disclosed herein suffers from reduced performance due to narrowing as described above It is less suitable for joining parts of portable electronic equipment. The adhesive sheet disclosed herein can be preferably used, for example, as a fixing member for fluid-tightly bonding a display portion or a display portion protective member of a portable electronic device to a casing to protect the casing. The contained electronic equipment is not affected by water or dust.

1, 2, 3‧‧‧Double-sided adhesive sheet

11‧‧‧First Adhesive Layer

11A‧‧‧First Adhesive Surface

12‧‧‧Second adhesive layer

12A‧‧‧Second Adhesive Surface

15‧‧‧Foam substrate

15A‧‧‧Side 1

15B‧‧‧Side 2

17‧‧‧Release liner

17A‧‧‧Front of release liner

17B‧‧‧Back side of release liner

21‧‧‧Stainless steel plate

21A‧‧‧Through Hole

22‧‧‧Glass

23‧‧‧Rod

24‧‧‧Support Desk

31‧‧‧Polycarbonate sheet

32‧‧‧Glass

120‧‧‧Dust resistance evaluation test device

121‧‧‧Top Plate

122‧‧‧Spacers

123‧‧‧Double-sided adhesive sheet

125‧‧‧Case for evaluation

127‧‧‧Opening

128‧‧‧Space Department

Hs‧‧‧Thickness of foam substrate

Ht‧‧‧Total thickness of adhesive sheet

FIG. 1 is a schematic cross-sectional view showing the structure of an adhesive sheet according to an embodiment.

FIGS. 2( a ) and 2 ( b ) are explanatory diagrams showing evaluation samples used in the measurement of the pressing force, and FIG. 2( a ) is a plan view and FIG. 2( b ) is a cross section AA′ picture.

FIG. 3 is an explanatory diagram showing a method of measuring the pressing force.

FIGS. 4( a ) and 4 ( b ) are explanatory views showing evaluation samples used in the drop durability test, and FIG. 4( a ) is a plan view and FIG. 4( b ) is a cross-sectional view of BB′ .

FIG. 5 is an exploded perspective view showing a schematic configuration of a dustproof property evaluation test apparatus.

FIG. 6 is a cross-sectional view showing a schematic configuration of a dustproof evaluation test apparatus.

Hereinafter, preferred embodiments of the present invention will be described.

Here, matters other than the matters specifically mentioned in this specification and necessary for the implementation of the present invention can be identified by the industry based on the instructions for implementation of the invention described in this specification and the technical common sense at the time of filing the application. understood. The present invention can be implemented according to the contents disclosed in this specification and common technical knowledge in the field.

In addition, in the following drawings, the same code|symbol is attached|subjected and demonstrated to the member and the part which perform the same function, and the repeated description is abbreviate|omitted or simplified. In addition, the embodiment described in the drawings is a schematic diagram for the purpose of clearly explaining the present invention, and does not accurately represent the size or reduction ratio of the adhesive sheet of the present invention actually provided as a product.

In this specification, the so-called "adhesive" refers to a material having the following properties as described above: it exhibits the state of a soft solid (viscoelastic body) in a temperature region around room temperature, and is easily adhered by pressure. on the attached body. The so-called adhesive here is as defined in "CADahlquist, "Adhesion: Fundamental and Practice", McLaren & Sons, (1966) P.143", generally speaking, it can have a complex tensile elastic modulus E*(1Hz). )<10 ⁷ dyne/cm ² (typically at 25°C with the above properties). In addition, the so-called "base polymer" of the adhesive refers to the main component (that is, the 50% by weight or more of the rubber-like polymer). In addition, in this specification, the "main component" means the component which accounts for 50 weight% or more when it does not specifically describe.

<Foam base material>

The foam base material constituting the adhesive sheet disclosed herein is a base material having a portion having cells (cell structure), and is typically a base of a layered foam (foam layer) comprising at least one layer material. The above-mentioned foam base material may be a base material including one or more foam layers. The above-mentioned foam base material may be, for example, a base material substantially including only one or two or more foam layers. Although it does not specifically limit, as a suitable example of the foam base material in the technique disclosed here, the foam base material which consists of a single-layer (one-layer) foam layer is mentioned.

The thickness Hs of the foam base material is not particularly limited, and can be appropriately set according to the strength or flexibility of the adhesive sheet, the purpose of use, and the like. From the viewpoint of reducing the thickness of the joint portion, the thickness Hs of the foam base material is usually 0.70 mm or less, preferably 0.40 mm or less, and more preferably 0.30 mm or less. With regard to the technique disclosed here, from the viewpoint of workability when processing the adhesive sheet into a narrow width, the thickness Hs of the foam base material can be 0.20 mm or less (typically 0.18 mm or less, for example, 0.16 mm or less). ) is preferably implemented. In addition, from the viewpoint of the impact resistance of the self-adhesive sheet, the thickness Hs of the foam base material is suitably 0.05 mm or more, preferably 0.06 mm or more, more preferably 0.07 mm or more (for example, 0.08 mm or more). . The technology disclosed herein enables the thickness Hs of the foam substrate to be 0.10 mm or more (typically more than 0.10 mm, preferably 0.12 mm or more, e.g. Such as 0.13mm or more) is preferably implemented. When the thickness of a foam base material becomes large, there exists a tendency for the desired impact resistance to be exhibited even if it becomes narrower. In addition, the impact resistance of an adhesive sheet can be evaluated by, for example, a drop durability test or a water repellency test after dropping, which will be described later.

The density D of the foam base material (referring to the apparent density. Hereinafter, it is the same unless otherwise stated) is not particularly limited, but may be, for example, 0.1 to 0.9 g/cm ³ . From the viewpoint of impact resistance, the density D of the foam base material is suitably 0.8 g/cm ³ or less, preferably 0.7 g/cm ³ or less (for example, 0.6 g/cm ³ or less). In one aspect, the density D of the foam substrate may be less than 0.5 g/cm ³ or less than 0.4 g/cm ³ (eg, 0.5 g/cm ³ or less). In addition, from the viewpoint of impact resistance, the density D of the foam base material is preferably 0.12 g/cm ³ or more, more preferably 0.15 g/cm ³ or more, still more preferably 0.2 g/cm ³ or more (for example, 0.3g/ ^cm3 or more). In one aspect, the density D of the foam substrate may be 0.4 g/cm ³ or more, 0.5 g/cm ³ or more (eg, more than 0.5 g/cm ³ ), and further may be 0.55 g/cm 3 ³ or more. In addition, the density D (apparent density) of a foam base material can be measured based on JISK6767.

In a preferred aspect, the density D of the foam base material may be 0.3-0.8 g/cm ³ . The foam base material whose density is in the above-mentioned range is easy to obtain the one with good shock absorption and a higher value of (M/D). Therefore, the adhesive sheet provided with such a foam base material can have favorable impact resistance of a junction part, and can suppress the degree of the performance reduction by narrowing.

The average cell diameter of the foam base material is not particularly limited, but is preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 150 μm or less, from the viewpoint of suppressing performance degradation due to narrowing. The average cell diameter of the foam substrate is preferably 120 μm or less, more preferably 100 μm or less (typically 90 μm or less, for example, 80 μm or less, and further 70 μm or less, from the viewpoint of exerting higher performance in terms of water repellency and dust resistance. ). In the technique disclosed here, by reducing the average cell diameter of the foam base material, for example, there is a tendency that even if it is impacted in a narrow width, such as the water repellency after dropping described later, It is easy to maintain waterproof or dust resistance. Moreover, since it becomes effective also as one method of making the value of the said M/D large, it is preferable to make an average bubble diameter small. The lower limit of the average cell diameter is not particularly limited, but from the viewpoint of impact resistance, it is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and still more preferably 40 μm or more (for example, 50 μm or more). In one aspect, the average bubble diameter may be 55 μm or more, or 60 μm or more. In addition, the average cell diameter here means the average cell diameter in sphere conversion obtained by observing the cross section of the foam base material with an electron microscope.

The bubbles contained in the foam base material preferably have a shape that is relatively close to a circle in a plan view of the foam base material. That is, it is preferable that the average cell diameter in the advancing direction of the foam base material (hereinafter also referred to as "MD") and the average cell diameter in the width direction (hereinafter also referred to as "CD") are not too different. Regarding the degree of difference between the shape of the above-mentioned cells and the circle, the ratio of the average cell diameter in MD (MD average cell diameter) to the average cell diameter in CD (CD average cell diameter) of the foam base material, That is, the "aspect ratio (MD/CD)" represented by the following formula is grasped as an index. The closer the aspect ratio (MD/CD) is to 1, the closer the shape of the air cells contained in the foam base material in plan view is to a circle.

Aspect ratio (MD/CD)=MD average bubble diameter/CD average bubble diameter

In one aspect of the technology disclosed herein, the aspect ratio (MD/CD) of the cells contained in the foam substrate is preferably 0.7 or more, more preferably 0.75 or more, and still more preferably 0.8 or more, for example Can be more than 0.85. In one aspect, the aspect ratio may be greater than 0.9, or greater than 0.95 (eg, greater than or equal to about 1.0). Moreover, the said aspect ratio (MD/CD) becomes like this. Preferably it is 1.3 or less, More preferably, it is 1.25 or less, More preferably, it is 1.2 or less, For example, 1.15 or less may be sufficient. By not making the aspect ratio (MD/CD) less than 1, the workability of the adhesive sheet using the foam base material can be improved. Moreover, by making the said aspect ratio (MD/CD) not more than 1, the water repellency (for example, the water repellency after dropping described later) or the dust resistance of the adhesive sheet using the said foam base material can be improved. For the foam base material constituting the adhesive sheet that can be used in the form of a narrow portion (especially in the form of an annular member having a narrow portion) as will be described later In other words, it is particularly significant that the above-mentioned aspect ratio (MD/CD) is close to 1.

Here, the MD of the foam base material refers to the extrusion direction in the production process of the foam base material. Although not particularly limited, the MD in a strip-shaped foam base material such as a strip usually corresponds to the longitudinal direction thereof. In addition, the CD of a foam base material means the direction orthogonal to the MD of this foam base material, and along the surface of this foam base material. The thickness direction (hereinafter also referred to as "VD") of the foam base material is a direction orthogonal to both the above-mentioned MD and the above-mentioned CD.

The MD average cell diameter of the foam substrate can be measured as follows.

That is, the above-mentioned foam base material is cut along a plane parallel to MD and VD (that is, a plane whose direction of the vertical line is consistent with CD) at the approximate center of its CD, and is scanned by a scanning electron microscope (SEM). ) photographed the central portion of the cut surface. The photographed image was printed on A4 size paper, and a straight line with a length of 60 mm parallel to MD was drawn on the image. At this time, the magnification of the SEM is adjusted so that about 10 to 20 air bubbles exist on a straight line of 60 mm. The MD average cell diameter was calculated by the following formula by visually counting the number of cells present on the above-mentioned straight line.

MD average bubble diameter (μm)=60(mm)×10 ³ /(number of bubbles (piece)×magnification)

The CD average cell diameter of the foam base material can be measured as follows.

That is, the said foam base material was cut|disconnected along the plane parallel to its CD and VD (that is, the plane which the perpendicular|vertical line direction matched MD), and the center part of the cut surface was photographed by SEM. The photographed image was printed on A4 size paper, and a straight line with a length of 60 mm parallel to the CD was drawn on the image. At this time, the magnification of the SEM is adjusted so that about 10 to 20 air bubbles exist on a straight line of 60 mm. The CD average cell diameter was calculated by the following formula by visually counting the number of cells present on the above-mentioned straight line.

CD average bubble diameter (μm)=60(mm)×10 ³ /(number of bubbles (piece)×magnification)

In addition, when drawing a straight line, it is set so that a straight line does not come into contact with a bubble point and penetrates a bubble as much as possible. In the case of a part of the bubbles in contact with the direct point, the bubbles The count is 1. Furthermore, when the both ends of the straight line did not penetrate the air bubbles and were in the state of being located in the air bubbles, the air bubbles were counted as 0.5.

The average cell diameter of the foam base material in each direction can be adjusted, for example, by adjusting the composition of the foam base material (the amount of foaming agent used, etc.) or the production conditions (conditions in the foaming step, the stretching step, etc.). control.

As the foam substrate in the technology disclosed herein, it is preferable to use the relationship between the 10% compressive strength C ₁₀ [kPa] and the 30% compressive strength C ₃₀ [kPa] to satisfy the following formula: (C ₃₀ /C ₁₀ )≦5.0. Here, the 10% compressive strength of the foam substrate refers to the load when the sample is measured by sandwiching a pair of flat plates and compressing it with a thickness equivalent to 10% of the original thickness (the compression ratio is 10%). load), the above-mentioned measurement sample is obtained by cutting the foam base material into a square shape of 30 mm square, and stacking the square shape to make a thickness of about 2 mm. That is, it refers to the load when the above-mentioned measurement sample is compressed to a thickness corresponding to 90% of the original thickness. The 30% compressive strength C ₃₀ [kPa] and the 25% compressive strength C ₂₅ [kPa] described later also refer to the load when the measurement sample is compressed at a thickness corresponding to 30% or 25% of the initial thickness.

The compressive strength at an arbitrary compression ratio of the foam base material was measured in accordance with JIS K 6767. As a specific measurement procedure, the measurement sample is placed in the center of the pair of flat plates, the space between the flat plates is narrowed, and the flat plate is continuously compressed to an arbitrary compression ratio. load. The compressive strength of the foam substrate can be controlled, for example, by the degree of crosslinking or density of the material constituting the foam substrate, the size or shape of the cells, and the like.

A smaller compressive strength ratio (C ₃₀ /C ₁₀ ) means that the difference in the degree of compression has less effect on the compressive strength. For example, there are unevennesses such as level difference or damage on the joint surface of the adhesive sheet, or the width of the adhesive sheet is different, or a part of the joint part of the adhesive sheet is subjected to greater stress than the other parts. At the same time, there may be cases where one part of the adhesive sheet is compressed more than the other part. When the width of the adhesive sheet is narrowed, there is a tendency that the difference in the degree of compression due to the above-mentioned step difference or local difference in width becomes more pronounced. If the difference in compressive strength caused by the difference in the degree of compression is too large, there may be a situation where the strain is concentrated in the part where the degree of compression changes, which becomes the starting point for peeling of the adhesive sheet or damage to the foam substrate. The adhesive sheet using the foam base material with a smaller (C ₃₀ /C ₁₀ ) is less likely to cause the above-mentioned peeling or damage to the foam base material due to the small difference in compressive strength caused by the above-mentioned compression degree. . This situation can become advantageous from the viewpoint of improving impact resistance. From the viewpoint of obtaining a better effect, (C ₃₀ /C ₁₀ ) is more preferably 4.5 or less, and still more preferably 4.0 or less. (C ₃₀ /C ₁₀ ) may be 3.5 or less. Although the lower limit of (C ₃₀ /C ₁₀ ) is not particularly limited, for example, it is suitably 2.5 or more, and may be 3.0 or more.

The 25% compressive strength C ₂₅ of the foam base material is not particularly limited, but may be, for example, 20 kPa or more (typically, 40 kPa or more). C ₂₅ is usually preferably 250 kPa or more, preferably 300 kPa or more (for example, 400 kPa or more). An adhesive sheet provided with such a foam base material can exhibit good durability against impacts such as falling even if it is narrow. For example, it becomes better to prevent the breakage of the adhesive sheet caused by the impact. The upper limit of C ₂₅ is not particularly limited, but usually 1300 kPa or less (for example, 1200 kPa or less) is suitable. In one aspect, C ₂₅ may be 1000 kPa or less, 800 kPa or less, and further 600 kPa or less (eg, 500 kPa or less). According to the relationship between C ₂₅ [kPa] and apparent density D[g/cm ³ ], the following formula is satisfied: 150≦C ₂₅ ×D≦400 (for example, 200≦C ₂₅ ×D≦350, preferably 240≦C ₂₅ ×D≦300), the adhesive sheet for the foam base material can achieve better results.

In another preferred aspect, the C ₂₅ of the foam substrate can be set to 20kPa-200kPa (typically 30kPa-150kPa, such as 40kPa-120kPa). Since the compressive strength of the adhesive sheet provided with such a foam base material is comparatively low in density, it can be excellent in cushioning properties even in a narrow width. For example, by absorbing the drop impact by the foam base material, the peeling of the adhesive sheet can be better prevented. According to the relationship between C ₂₅ [kPa] and apparent density D[g/cm ³ ], the following formula is satisfied: 100≦C ₂₅ /D≦400 (eg 150≦C ₂₅ /D≦350, preferably 200≦C ₂₅ /D≦300), the adhesive sheet for the foam base material can achieve better results.

The tensile elongation of the foam substrate is not particularly limited. For example, a foam substrate having a tensile elongation in the running direction (MD) of 200% to 800% (more preferably 400% to 600%) can be suitably used. Moreover, it is preferable that it is a foam base material whose tensile elongation in the width direction (TD) is 50% to 800% (more preferably, 200% to 500%). The elongation of the foam base material is measured according to JIS K 6767. The elongation of the foam substrate can be controlled by, for example, the degree of crosslinking, the apparent density (expansion rate), and the like.

The tensile strength (tensile strength) of the foam base material is not particularly limited. For example, a foam substrate having a tensile strength in the running direction (MD) of 5 MPa to 35 MPa (preferably 10 MPa to 30 MPa) can be suitably used. Moreover, the tensile strength of the width direction (TD) is preferably a foam base material of 1 MPa to 25 MPa (more preferably 5 MPa to 20 MPa). The tensile strength of the foam base material can be measured according to JIS K 6767. The tensile strength of the foam substrate can be controlled by, for example, the degree of crosslinking, the apparent density (expansion rate), and the like.

The material of the foam substrate is not particularly limited. Generally, a foam base material including a foam layer formed of a foam body of a plastic material (plastic foam body) is preferable. The plastic material (meaning including rubber material) used to form the plastic foam is not particularly limited, and can be appropriately selected from known plastic materials. Plastic materials can be used alone or in combination of two or more.

Specific examples of plastic foams include foams made of polyolefin resins such as polyethylene foams and polypropylene foams; polyethylene terephthalate foams, polynaphthalene foams, etc. Polyester resin foams such as ethylene dicarboxylate foams and polybutylene terephthalate foams; polyvinyl chloride resin foams such as polyvinyl chloride foams; Foams made of vinyl acetate-based resins; Foams made of polyphenylene sulfide resins; Foams made of aliphatic polyamide (nylon) resins; Foams made of amide resins such as foams; foams made of polyimide resins; foams made of polyether ether ketone (PEEK); foams made of styrene resins such as polystyrene foams urethane resin foams, such as polyurethane resin foams, etc. Also, as a plastic foam, Rubber-based resin foams such as polychloroprene rubber foams can also be used.

As a preferable foam, a polyolefin resin foam (henceforth "polyolefin foam") can be illustrated. As the plastic material (that is, the polyolefin-based resin) constituting the polyolefin-based foam, various known or conventional polyolefin-based resins can be used without particular limitation. For example, polyethylene such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE), polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc. . As an example of LLDPE, a Ziegler-Natta catalyst type linear low density polyethylene, a metallocene catalyst type linear low density polyethylene, etc. are mentioned. Such a polyolefin resin can be used individually by 1 type or in combination of 2 or more types suitably.

As a suitable example of the foam base material in the technique disclosed here, from the viewpoints of impact resistance, water resistance, dust resistance, etc., polyethylene-based foams that substantially contain a foam of polyethylene-based resins can be exemplified Polyolefin-based foam substrates such as bulk substrates and polypropylene-based foam substrates substantially including foams of polypropylene-based resins. Here, the polyethylene-based resin refers to a resin with ethylene as the main monomer (that is, the main component in the monomer). In addition to HDPE, LDPE, LLDPE, etc., it may also contain ethylene with a copolymerization ratio of more than 50% by weight. Ethylene-propylene copolymer or ethylene-vinyl acetate copolymer, etc. Similarly, the so-called polypropylene-based resin refers to a resin containing propylene as a main monomer. As the foam base material in the technique disclosed herein, a polyethylene-based foam base material can be preferably used.

The manufacturing method of the said plastic foam (typically, a polyolefin-type foam) is not specifically limited, Various well-known methods can be suitably employ|adopted. For example, it can be manufactured by a method including the above-mentioned plastic material or the above-mentioned plastic foam forming step, cross-linking step and foaming step. Also, an extension step may be included as desired.

As a method of crosslinking the above-mentioned plastic foam, for example, a chemical crosslinking method using an organic peroxide or the like, or an ionizing radiation crosslinking method by irradiating ionizing radiation, etc., can be used in combination. As said ionizing radiation, an electron beam, an alpha ray, a beta ray, a gamma ray etc. can be illustrated. The amount of ionizing radiation is not particularly limited, and the foam substrate can be considered The target physical properties (for example, the degree of cross-linking), etc., are set to an appropriate irradiation dose.

In the above-mentioned foam base material, fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, anti-aging agents, etc. can also be prepared as needed. Various additives such as fuels, surfactants, etc.

The foam base material in the technique disclosed here may be colored so that the adhesive sheet provided with the foam base material may express desired creativity or optical properties (eg, light-shielding property, light-reflecting property, etc.). About this coloring, a well-known organic or inorganic coloring agent can be used individually by 1 type, or can be used in combination of 2 or more types suitably.

For example, when the adhesive sheet disclosed here is used for light-shielding purposes, the visible light transmittance of the foam base material is not particularly limited, but is preferably 0% as in the visible light transmittance of the adhesive sheet described later. ~15%, more preferably 0%~10%. Furthermore, when the adhesive sheet disclosed here is used for light reflection purposes, the visible light reflectance of the foam base material is the same as the visible light reflectance of the adhesive sheet, preferably 20% to 100% , more preferably 25%~100%.

The visible light transmittance of the foam substrate can be obtained by the following method: using a spectrophotometer (for example, a spectrophotometer manufactured by Hitachi High-Tech Co., Ltd., model "U-4100"), at a wavelength of 550 nm, measure The intensity of light that is irradiated from one surface side of the foam base material and transmitted to the other surface side. The visible light reflectance of a foam base material can be calculated|required by measuring the intensity|strength of the light reflected by irradiating one surface of a foam base material at wavelength 550nm using the said spectrophotometer. In addition, the visible light transmittance or visible light reflectance of the adhesive sheet can also be obtained by the same method.

When the adhesive sheet disclosed herein is used in light-shielding applications, the foam base material is preferably colored black. Black is preferably 35 or less (eg, 0 to 35), and more preferably 30 or less (eg, 0 to 30) in terms of L* (brightness) defined in the L*a*b* colorimetric system. Furthermore, a* or b* specified in the L*a*b* color system can be appropriately selected according to the value of L*, respectively. It does not specifically limit as a* or b*, Preferably both are -10~10 (more preferably -5~5, More preferably, it is in the range of -2.5~2.5). For example, it is preferable that both a* and b* are 0 or approximately 0.

Furthermore, in this manual, L*, a*, b* specified in the L*a*b* colorimetric system can be determined by using a colorimeter (such as a colorimeter manufactured by Minolta, trade name "CR"). -200") was measured and obtained. Furthermore, the L*a*b* color system is the color space recommended by the International Commission on Illumination (CIE) in 1976, which refers to the color space known as the CIE1976 (L*a*b*) color system. In addition, the L*a*b* color system is defined in JIS Z 8729 in Japanese Industrial Standards.

As the black colorant used to color the foam substrate black, for example, carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide can be used , aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium zirconium Compounds, complex oxide-based black pigments, anthraquinone-based organic black pigments, etc. From the viewpoint of cost and availability, carbon black can be exemplified as a preferable black colorant. The usage-amount of a black coloring agent is not specifically limited, It can be set as the quantity suitably adjusted so that desired optical characteristics may be provided.

When the adhesive sheet disclosed herein is used in light reflection applications, the above-mentioned foam substrate is preferably colored white. White is preferably 87 or more (eg, 87 to 100), and more preferably 90 or more (eg, 90 to 100) in terms of L* (brightness) defined in the L*a*b* colorimetric system. The a* or b* specified in the L*a*b* color system can be appropriately selected according to the value of L*, respectively. As a* or b*, for example, both of them are preferably in the range of -10 to 10 (more preferably -5 to 5, and still more preferably -2.5 to 2.5). For example, it is preferable that both a* and b* are 0 or approximately 0.

Examples of the white colorant used when coloring the foam base material white include titanium oxide (titanium dioxide such as rutile-type titanium dioxide and anatase-type titanium dioxide), zinc oxide, aluminum oxide, silicon oxide, and zirconium oxide. , magnesium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate (light calcium carbonate, heavy calcium carbonate, etc.), barium carbonate, zinc carbonate, aluminum hydroxide, calcium hydroxide , Magnesium Hydroxide, Hydroxide Zinc, aluminum silicate, magnesium silicate, calcium silicate, barium sulfate, calcium sulfate, barium stearate, zinc white, zinc sulfide, talc, silica, alumina, clay, kaolin, titanium phosphate, mica, gypsum , white carbon, diatomite, bentonite, zeolite, sericite, halloysite and other inorganic white colorants, or acrylic resin particles, polystyrene resin particles, polyurethane resin Particles, amide-based resin particles, polycarbonate-based resin particles, silicone-based resin particles, urea-formalin-based resin particles, organic-based white colorants such as melamine-based resin particles, etc. The usage-amount of a white coloring agent is not specifically limited, It can be set as the quantity suitably adjusted so that desired optical characteristics may be provided.

For the surface of the foam substrate, appropriate surface treatment can also be performed as required. The surface treatment may be, for example, a chemical or physical treatment for improving adhesion to adjacent materials (eg, an adhesive layer). Examples of the surface treatment include corona discharge treatment, chromic acid treatment, ozone exposure, flame exposure, ultraviolet irradiation treatment, plasma treatment, application of a primer (primer), and the like.

<Adhesive>

The adhesive sheet disclosed herein has an adhesive layer on at least one side of the foam substrate. The type of the adhesive constituting the adhesive layer is not particularly limited. The above-mentioned adhesive can be an adhesive formed from an adhesive composition, and the above-mentioned adhesive composition includes, for example, an adhesive selected from the group consisting of acrylic series, polyester series, urethane series, polyether series, rubber series, and polysiloxane series. , 1 or 2 or more of various polymers (adhesive polymers) such as polyamide-based and fluorine-based polymers as the base polymer (the main component in the polymer component, that is, the component that accounts for more than 50% by weight) . The technique disclosed here can be preferably implemented in the form of an adhesive sheet containing an acrylic adhesive, for example.

The so-called "acrylic adhesive" here refers to an adhesive that uses an acrylic polymer as a base polymer. The "acrylic polymer" refers to a monomer having at least one (meth)acryloyl group in one molecule (hereinafter, this may be referred to as an "acrylic monomer") as a main constituent monomer component (The main component of the monomer, that is, the main component that constitutes the acrylic polymer 50% by weight or more of the total amount of monomers) of the polymer. In addition, in this specification, the "(meth)acryloyl group" refers to the meaning of an acryl group and a methacryloyl group inclusively. Similarly, the so-called "(meth)acrylate" refers to the meaning of acrylate and methacrylate inclusively.

The said acrylic polymer is a polymer which has an alkyl (meth)acrylate as a main structural monomer component typically. As said (meth)acrylic-acid alkylester, the compound represented by following formula (1) can be used suitably, for example.

CH ₂ =C(R ¹ )COOR ² (1)

Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. R ² is an alkyl group having 1 to 20 carbon atoms. From the standpoint of easily obtaining an adhesive excellent in adhesive properties, R ² is preferably an alkyl group having 2 to 14 carbon atoms (hereinafter, the range of such carbon number is represented as C _2-14 ) (a methyl group). base) alkyl acrylate. Specific examples of the C _2-14 alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopropyl Amyl, neopentyl, n-hexyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, n-nonyl, isononyl, n-decyl, isodecyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, etc.

In a preferred aspect, the total amount of monomers used in the synthesis of the acrylic polymer is about 50% by weight or more (typically 50-99.9% by weight), more preferably 70% by weight or more (typically is 70 to 99.9 wt %), for example, about 85 wt % or more (typically 85 to 99.9 wt %) is composed of (meth)acrylic acid alkanes selected from the group consisting of R in the above formula ( ¹ ) being C _2-14 Base ester (more preferably C _4-10 (meth)acrylic acid alkyl ester. Especially preferably one or both of n-butyl acrylate and 2-ethylhexyl acrylate) or 2 or more of them Take up. According to the acrylic polymer obtained by the composition of such a monomer, it is easy to form an adhesive exhibiting good adhesive properties, which is preferable.

Although not particularly limited, as the acrylic polymer, a polymer obtained by copolymerizing an acrylic monomer having a hydroxyl group (-OH) (hydroxyl-containing acrylic monomer) can be preferably used. By. According to the acrylic polymer of the copolymerization composition, it is easy to obtain an adhesive excellent in the balance of adhesive force and cohesion force and excellent in releasability, which is preferable.

The hydroxyl group-containing acrylic monomer may be used alone or in combination of two or more. Specific examples of the hydroxyl group-containing acrylic monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (meth)acrylate ) 2-hydroxybutyl acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate and other hydroxyalkyl esters of (meth)acrylate. Further, (4-hydroxymethylcyclohexyl)methyl acrylate, polypropylene glycol mono(meth)acrylate, N-hydroxyethyl(meth)acrylamide, and N-hydroxypropyl(meth)propylene can be exemplified. Amide, etc. Among them, hydroxyalkyl (meth)acrylate is preferable, and an alkyl group in the above-mentioned hydroxyalkyl group is a linear hydroxyalkyl (meth)acrylate having 2 to 4 carbon atoms.

The hydroxyl-containing acrylic monomer is preferably used in a range of about 0.001 to 10% by weight in the total amount of the monomers used in the synthesis of the acrylic polymer. Thereby, the adhesive sheet which can balance the above-mentioned adhesive force and cohesion force at a higher level can be realized. By setting the usage-amount of the hydroxyl-containing acrylic monomer to about 0.01 to 5 wt % (eg, 0.05 to 2 wt %), even better results can be achieved. Alternatively, the acrylic polymer in the technology disclosed herein may be one in which a hydroxyl group-containing acrylic monomer is not copolymerized.

啉、乙烯醚類等。例如，較佳為使含有羧基之單體作為上述其他單體進行共聚而成之丙烯酸系聚合物。 In the acrylic polymer in the technique disclosed here, monomers other than the above (other monomers) may be copolymerized within a range not significantly impairing the effects of the present invention. This monomer can be used for the purpose of, for example, adjustment of the glass transition temperature of an acrylic polymer, adjustment of adhesive properties (eg, peelability). For example, examples of monomers that can improve the cohesive force and heat resistance of the adhesive include sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl esters, and aromatic vinyl compounds. Wait. In addition, as a monomer that can be introduced into the acrylic polymer as a functional group that can become a crosslinking point, or can contribute to the improvement of the adhesive force, a carboxyl group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer can be exemplified. Monomers containing amine groups, monomers containing amine groups, monomers containing amide groups, monomers containing epoxy groups, (meth)acryloyl groups

Lin, vinyl ethers, etc. For example, an acrylic polymer obtained by copolymerizing a carboxyl group-containing monomer as the other monomer described above is preferable.

Examples of the sulfonic acid group-containing monomer include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, and (meth)acrylamidopropanesulfonic acid , (meth) sulfopropyl acrylate, (meth) acryloxynaphthalene sulfonic acid, sodium vinyl sulfonate, etc.

As a monomer containing a phosphoric acid group, 2-hydroxyethyl acrylyl phosphate can be exemplified.

As a cyano group containing monomer, acrylonitrile, methacrylonitrile, etc. are illustrated.

As vinyl esters, vinyl acetate, vinyl propionate, vinyl laurate, etc. are illustrated, for example.

As the aromatic vinyl compound, styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, other substituted styrenes, and the like can be exemplified.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itonic acid, maleic acid, fumaric acid, crotonic acid, and isobutylene. acid etc.

Examples of the acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, the acid anhydride body of the above-mentioned carboxyl group-containing monomer, and the like.

Examples of the acylamide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N -Dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N,N - Dimethylaminopropyl acrylamide, N,N-dimethylaminopropyl methacrylamide, diacetone acrylamide, etc.

Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylamine (meth)acrylate. Propyl ester, etc.

As a monomer containing an imide group, cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, iconimide, and the like can be exemplified.

As an epoxy group-containing monomer, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether, etc. can be illustrated.

As vinyl ethers, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, etc. can be illustrated.

Such "other monomers" may be used alone or in combination of two or more, but the total amount of the other monomers described above is preferably set as the total amount of the monomers used in the synthesis of the acrylic polymer About 40 wt% or less (typically 0.001 to 40 wt%), more preferably about 30 wt% or less (typically 0.01 to 30 wt%, for example, 0.1 to 10 wt%). When a carboxyl group-containing monomer is used as the above-mentioned other monomers, the content thereof can be set to, for example, 0.1 to 10% by weight of the total amount of the above-mentioned monomers, usually 0.2 to 8% by weight, for example, 0.5 to 10% by weight. 5% by weight. Moreover, when vinyl esters (for example, vinyl acetate) are used as the above-mentioned other monomers, the content thereof can be, for example, 0.1 to 20 wt % of the total amount of the above-mentioned monomers, and usually 0.5 to 10 wt % is appropriate. weight%.

The copolymerization composition of the acrylic polymer is appropriately designed so that the glass transition temperature (Tg) of the acrylic polymer is -15°C or lower (typically -70°C to -15°C), preferably -25°C or lower (for example, -60°C to -25°C), more preferably -40°C or lower (for example, -60°C to -40°C). From the viewpoint of the impact resistance of the self-adhesive sheet, etc., it is preferable to set the Tg of the acrylic polymer to be equal to or less than the above upper limit value. The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the kind or usage ratio of the monomers used in the synthesis of the polymer).

Here, in this specification, the Tg of a polymer means the Tg calculated|required by Fox formula from the copolymerization composition of this polymer. The Fox formula is a relational expression between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing the monomers constituting the copolymer as shown below.

1/Tg=Σ(Wi/Tgi)

Furthermore, in the above Fox formula, Tg represents the glass transition temperature of the copolymer (single Position: K), Wi represents the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), Tgi represents the glass transition temperature (unit: K) of the homopolymer of monomer i.

As the glass transition temperature of the homopolymer used for the calculation of Tg, the value described in a known document was used. For example, regarding the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomers.

2-ethylhexyl acrylate -70℃

n-Butyl acrylate -55℃

Ethyl Acrylate -22℃

Methyl acrylate 8℃

Methyl methacrylate 105℃

Cyclohexyl methacrylate 66℃

2-Hydroxyethyl acrylate -15℃

Vinyl acetate 32℃

Styrene 100℃

Acrylic 106℃

Methacrylic acid 228℃

Regarding the glass transition temperature of homopolymers of monomers other than those exemplified above, use "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) ) the value recorded. Regarding the monomers in which plural values are described in this document, the highest value is used.

Regarding the monomers whose glass transition temperature of the homopolymer is not described in the above-mentioned documents, the value obtained by the following measurement method was used (refer to Japanese Patent Application Laid-Open No. 2007-51271). Specifically, 100 parts by weight of monomers, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen introduction pipe, and a reflux condenser. Stirring was performed for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature was raised to 63°C for 10 hours. answer. Next, it cooled to room temperature, and obtained the homopolymer solution whose solid content concentration is 33 weight%. This homopolymer solution was cast-coated on a release liner and dried to prepare a test sample (a sheet-like homopolymer) having a thickness of about 2 mm. The test sample was punched into a disc shape with a diameter of 7.9 mm, sandwiched by parallel plates, and a viscoelasticity test device (manufactured by TA Instruments, ARES) was used. While giving a shear strain of 1 Hz at a frequency, the test sample was set between -70 and 150. The viscoelasticity was measured by the shear mode at a temperature increase rate of 5°C/min within the temperature range of °C, and the peak top temperature of tan δ (loss tangent) was taken as the glass transition temperature.

Although not particularly limited, the above-mentioned acrylic polymer is preferably a monomer whose glass transition temperature of the homopolymer is below -45°C in the total amount of the monomers used in the synthesis of the acrylic polymer. The ratio is 50% by weight or more (more preferably 70% by weight or more, for example, 85% by weight or more). According to the acrylic polymer of such a copolymerization composition, there exists a tendency for impact resistance to improve. The upper limit of the above ratio is not particularly limited, and may be 100% by weight of the total amount of the above monomers. From the viewpoint of the cohesiveness of the adhesive, etc., it is usually appropriate to set the ratio of the monomer whose glass transition temperature of the homopolymer is -45°C or lower in the total amount of the monomers to 99% by weight or less, preferably to be 97% by weight or less.

In the technique disclosed here, the method for obtaining the acrylic polymer is not particularly limited, and a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, etc. can be suitably used as a method for synthesizing an acrylic polymer. Various aggregation methods. For example, a solution polymerization method can be preferably used. As a method for supplying monomers in the solution polymerization, a single charging method in which all the monomer raw materials are supplied at one time, a continuous supply (dropwise addition) method, a divided supply (dropwise addition) method, and the like can be suitably used. The polymerization temperature can be appropriately selected according to the types of monomers and solvents used, the types of polymerization initiators, and the like, and can be set to, for example, about 20°C to 170°C (typically, 40°C to 140°C).

The initiator used in the polymerization can be appropriately selected from known or conventional polymerization initiators according to the type of the polymerization method. For example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(2-methylpropionate) can be preferably used amidinopropane) dihydrochloride Azo-based polymerization initiators such as salts. Other examples of polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate; peroxide-based initiators such as benzyl peroxide, tert-butyl hydroperoxide, and hydrogen peroxide; Substituted ethane-based initiators such as phenyl-substituted ethane; aromatic carbonyl compounds, etc. As still another example of a polymerization initiator, the redox type initiator which utilizes the combination of a peroxide and a reducing agent is mentioned. Examples of the redox-based initiator include a combination of a peroxide such as aqueous hydrogen peroxide and ascorbic acid, a combination of a peroxide such as aqueous hydrogen peroxide and an iron (II) salt, a persulfate and hydrogen sulfite The combination of sodium, etc. A polymerization initiator can be used individually by 1 type or in combination of 2 or more types. The usage-amount of a polymerization initiator should just be a normal usage-amount, For example, it can select from the range of about 0.005-1 weight part (typically 0.01-1 weight part) with respect to 100 weight part of all monomer components.

The solvent (polymerization solvent) used in the solution polymerization can be appropriately selected from known or conventional organic solvents. For example, any one solvent or a mixed solvent of two or more selected from the following solvents can be used: aromatic compounds (typically aromatic hydrocarbons) such as toluene and xylene; acetates such as ethyl acetate; Aliphatic or alicyclic hydrocarbons such as alkane, cyclohexane, methylcyclohexane; halogenated alkanes such as 1,2-dichloroethane; isopropanol, 1-butanol, second butanol, third Lower alcohols such as butanol (for example, monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone, acetylacetone, and the like. For example, a polymerization solvent (which may be a mixed solvent) having a boiling point in the range of 40°C to 150°C (preferably 60°C to 150°C, typically 70°C to 130°C) can be used.

According to the solution polymerization, a polymerization reaction liquid in the form of an acrylic polymer dissolved in an organic solvent can be obtained. The adhesive layer in the technique disclosed herein can be formed from an adhesive composition comprising the above-mentioned polymerization reaction solution or an acrylic polymer solution obtained by appropriately post-processing the reaction solution. As the said acrylic polymer solution, what prepared the said polymerization reaction liquid to the appropriate density|concentration as needed can be used. Alternatively, an acrylic polymer can be synthesized by a polymerization method other than solution polymerization (eg, emulsion polymerization, photopolymerization, bulk polymerization, etc.), and the acrylic polymer can be dissolved in an organic solvent Acrylic polymer solution prepared in

The weight-average molecular weight (Mw) of the acrylic polymer is not particularly limited, and may be, for example, in the range of 10×10 ⁴ to 500×10 ⁴ . From the viewpoint of easily obtaining a balance of adhesive properties, the Mw of the acrylic polymer is preferably in the range of 10×10 ⁴ to 150×10 ⁴ , more preferably in the range of 15×10 ⁴ to 100×10 ⁴ , and further More preferably, it is in the range of 20×10 ⁴ to 75×10 ⁴ . In addition, the Mw of the acrylic polymer is calculated by GPC (gel permeation chromatography) of the solvent-soluble fraction (eg, tetrahydrofuran-soluble fraction) of the acrylic polymer in terms of standard polystyrene conversion. form.

Adhesive compositions (eg, acrylic adhesive compositions) of the techniques disclosed herein may include tackifying resins. The tackifier resin is not particularly limited. For example, various tackifier resins such as rosin-based, terpene-based, hydrocarbon-based, epoxy-based, polyamide-based, elastic-based, phenol-based, and ketone-based resins can be used alone. Or use two or more in combination.

Specific examples of rosin-based tackifier resins include unmodified rosin (raw rosin) such as rosin gum, wood rosin, and tall oil rosin; these unmodified rosins are modified by hydrogenation, disproportionation, polymerization, and the like. Modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosin, etc.); other various rosin derivatives, etc. Examples of the above-mentioned rosin derivatives include those obtained by esterifying unmodified rosin with alcohol (that is, an esterified product of rosin), and modified rosin (hydrogenated rosin, disproportionated rosin) with alcohol. , polymerized rosin, etc.) are esterified (that is, the esterification of modified rosin) and other rosin esters; unmodified rosin or modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin) by unsaturated fatty acid. etc.) modified rosin with unsaturated fatty acid; rosin ester modified with unsaturated fatty acid obtained by modifying rosin ester with unsaturated fatty acid; unmodified rosin, modified rosin ( Rosin alcohols obtained by reducing the carboxyl groups in hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid-modified rosins or unsaturated fatty acid-modified rosin esters; unmodified rosin, modified rosin, various Metal salts of rosins (especially rosin esters) such as rosin derivatives; by using acid catalysts in rosins (unmodified rosin, Modified rosin, various rosin derivatives, etc.) are added with phenol and thermally polymerized to obtain rosin phenol resin, etc.

Examples of terpene-based tackifier resins include terpene resins such as α-pinene polymers, β-pinene polymers, dipentene polymers, and the like; modified terpene resins, etc. As an example of the said modified terpene resin, a terpene phenol resin, a styrene modified terpene resin, an aromatic modified terpene resin, a hydrogenated terpene resin, etc. are mentioned.

烯、雙戊烯等)之聚合物或其氫化物；對芳香族系烴樹脂或脂肪族‧芳香族系石油樹脂之芳香環進行氫化而成之脂環式烴系樹脂等。 Examples of hydrocarbon-based tackifier resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic-aromatic petroleum resins (styrene-olefin-based copolymers, etc.), Various hydrocarbon-based resins such as aliphatic and alicyclic petroleum resins, hydrogenated hydrocarbon resins, fenugreek-based resins, and fenugreek-based resins. Examples of the aliphatic hydrocarbon resin include polymers of one or more aliphatic hydrocarbons selected from olefins and dienes having about 4 to 5 carbon atoms and dienes. As an example of the said olefin, 1-butene, isobutene, 1-pentene, etc. are mentioned. As an example of the said diene, butadiene, 1, 3- pentadiene, isoprene, etc. are mentioned. Examples of the aromatic hydrocarbon resin include vinyl group-containing aromatic hydrocarbons having about 8 to 10 carbon atoms (styrene, vinyltoluene, α-methylstyrene, indene, methylindene, etc.) polymers, etc. Examples of aliphatic cyclic hydrocarbon resins include alicyclic hydrocarbon resins obtained by polymerizing so-called "C4 petroleum fractions" or "C5 petroleum fractions" after cyclodimerization; alkene compounds (cyclopentadiene, dicyclopentadiene, ethylene norm

alkene, dipentene, etc.) polymers or their hydrogenated products; alicyclic hydrocarbon resins obtained by hydrogenating aromatic rings of aromatic hydrocarbon resins or aliphatic/aromatic petroleum resins.

In the technique disclosed herein, as the tackifier resin, one having a softening point (softening temperature) of about 100°C or higher (preferably about 120°C or higher, more preferably about 135°C or higher) can be preferably used. According to the adhesive containing the tackifying resin which has a softening point of the said lower limit or more, the adhesive sheet which is more excellent in repellency resistance can be implement|achieved. The sticky tree exemplified above Among the resins, terpene-based tackifying resins (eg, terpene phenol resins), rosin-based tackifying resins (eg, esterified polymer rosin) with such softening points can be preferably used. The aforementioned tackifying resin can be preferably used, for example, in a state containing a terpene phenol resin having a softening point of 135° C. or higher. Moreover, according to the adhesive agent containing the tackifier resin whose softening point is 140 degreeC or more, especially excellent repellency resistance can be achieved. For example, a terpene phenol resin having a softening point of 140°C or higher can be preferably used. The upper limit of the softening point of the tackifier resin is not particularly limited, and can be set to, for example, about 200° C. or lower (typically, about 180° C. or lower). In addition, the softening point of tackifier resin can be measured according to the softening point test method (ring and ball method) prescribed|regulated in JIS K2207.

The amount of tackifier resin used is not particularly limited, and can be appropriately set according to the target adhesive properties (adhesion force, etc.). For example, on the basis of the solid content, the ratio is preferably about 10 to 100 parts by weight (more preferably 15 to 80 parts by weight, and still more preferably 20 to 60 parts by weight) with respect to 100 parts by weight of the acrylic polymer Use tackifying resin.

As an example of a suitable composition of the acrylic adhesive disclosed herein, there may be mentioned: a composition comprising a tackifier resin having a softening point of 120° C. or higher in a ratio of 20 to 60 parts by weight relative to 100 parts by weight of the acrylic polymer; The composition and the like of a tackifier resin having a softening point of 135° C. or higher are included in a ratio of 10 to 50 parts by weight relative to 100 parts by weight of the acrylic polymer. According to the acrylic adhesive of such a composition, there exists a tendency for repulsion resistance and softness to be suitably compatible.

唑啉系交聯劑、氮丙啶系交聯劑、三聚氰胺系交聯劑、過氧化物系交聯劑、脲系交聯劑、金屬烷氧化物系交聯劑、金屬螯合物系交聯劑、金屬鹽系交聯劑、碳二醯亞胺系交聯劑、胺系交聯劑等)中適宜選擇而使用。交聯劑可單獨使用1種或組合使用2種以上。交聯劑之使用量並無特別限制，例如可自相對於丙烯酸系聚合物100重量份而大約為10重量份以下(例如大約0.005~10重量份、較佳 為大約0.01~5重量份)左右之範圍內選擇。 In the adhesive composition, a cross-linking agent may also be used as required. The type of cross-linking agent is not particularly limited, and can be selected from known or conventional cross-linking agents (such as isocyanate-based cross-linking agents, epoxy-based cross-linking agents,

oxazoline-based cross-linking agent, aziridine-based cross-linking agent, melamine-based cross-linking agent, peroxide-based cross-linking agent, urea-based cross-linking agent, metal alkoxide-based cross-linking agent, metal chelate-based cross-linking agent A linking agent, a metal salt-based cross-linking agent, a carbodiimide-based cross-linking agent, an amine-based cross-linking agent, etc.) are appropriately selected and used. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types. The usage amount of the crosslinking agent is not particularly limited, for example, it can be about 10 parts by weight or less (for example, about 0.005 to 10 parts by weight, preferably about 0.01 to 5 parts by weight) relative to 100 parts by weight of the acrylic polymer. selection within the range.

The adhesive composition may optionally contain leveling agents, cross-linking aids, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antistatic agents, antiaging agents, ultraviolet absorbers, and antioxidants , light stabilizers and other general additives in the field of adhesive compositions. Regarding such various additives, conventionally known ones can be used, and since they do not particularly feature the present invention, detailed descriptions are omitted.

<Adhesive Sheet>

The adhesive sheet disclosed here (which may be in the form of a strip, etc.) includes a foam base material and an adhesive layer disposed on at least one surface of the foam base material. The adhesive sheet may be in the form of a single-sided adhesive sheet having an adhesive layer only on one surface of the foam base material, and only the one surface becomes an adhesive surface (adhesive surface). Such a single-sided adhesive sheet is, for example, fixed to the adherend by a method other than adhesion (such as a method of using an adhesive, a method of thermal fusion, etc.) Can be used for joining or fixing parts. The adhesive sheet disclosed herein is typically in the form of a double-sided adhesive sheet having an adhesive layer on both sides of a foam substrate (a double-sided adhesive sheet with a foam substrate). Well implemented. Such a double-sided adhesive sheet is advantageous, for example, from the viewpoints of the easiness of the joining operation of the parts, the stability of the joining quality, and the like.

The adhesive sheet disclosed herein may be, for example, a double-sided adhesive sheet having the cross-sectional structure schematically shown in FIG. 1 . The double-sided adhesive sheet 1 includes a sheet-like foam substrate 15 , and a first adhesive layer 11 and a second adhesive layer 12 respectively supported on both surfaces of the substrate 15 . More specifically, the first adhesive layer 11 and the second adhesive layer 12 are respectively provided on the first surface 15A and the second surface 15B (both are non-peelable) of the base material 15 . The double-sided adhesive sheet 1 before use (before being attached to the body to be adhered) can be overlapped with the release liner 17 whose front 17A and back 17B are both release surfaces as shown in FIG. 1 and wound into a spiral shape. form. In the double-sided adhesive sheet 1 of this form, the surface of the second adhesive layer 12 (the second adhesive surface 12A) is protected by the front surface 17A of the release liner 17, and the surface of the first adhesive layer 11 (the first adhesive surface 12A) is protected by the release liner 17. face 11A) by peeling The backside 17B of the release liner 17 is protected. Alternatively, the first adhesive surface 11A and the second adhesive surface 12A may be protected by two independent release liners, respectively.

As a release liner, a conventional release paper etc. can be used, and it does not specifically limit. For example, it can be used: a release liner with a release treatment layer on the surface of a liner substrate such as plastic film or paper; a release liner containing a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) etc.) release liner for low-adhesion materials, etc. The peeling treatment layer may be formed by surface-treating the liner base material with a peeling agent such as polysiloxane, long-chain alkyl, fluorine, and molybdenum sulfide, for example.

As a method of forming the adhesive layer on the foam base material, various methods known in the past can be applied. For example, the method of directly coating the adhesive composition on the foam substrate (direct method); coating the adhesive composition on a suitable peeling surface to form an adhesive layer on the peeling surface, A method (transfer method) in which the adhesive layer is attached to a foam base material and transferred. These methods can also be used in combination. Moreover, you may employ|adopt a different method with respect to a 1st adhesive bond layer and a 2nd adhesive bond layer. The adhesive composition can be applied, for example, using a gravure roll coater, a reverse roll coater, a touch roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, or the like known or conventionally used. The coating machine is carried out. In the case of using an adhesive composition containing a solvent, it is preferable to dry the adhesive composition under heating from the viewpoints of promoting the crosslinking reaction and improving the production efficiency.

The thickness of the adhesive layer is not particularly limited, and can be set according to the use purpose or target performance of the adhesive sheet. For example, the thickness of the adhesive layer can be set to about 5 μm to 150 μm. From the viewpoint of balancing the thinning of the adhesive sheet and the adhesive performance at a high level, the thickness of the adhesive layer is usually preferably about 10 μm or more (preferably about 15 μm or more, more preferably about 20 μm or more, for example, about 25 μm or more) ), and preferably about 100 μm or less (preferably about 90 μm or less, more preferably about 80 μm or less, for example, about 60 μm or less). In one aspect, the thickness of the adhesive layer may be, for example, about 10 μm to 100 μm (preferably about 15 μm to 90 μm, more preferably about 20 μm to 80 μm). right). From the viewpoint of thinning of the adhesive sheet, etc., the thickness of the adhesive layer can be set to be about 50 μm or less, and can also be set to be about 40 μm or less (for example, about 35 μm or less).

The total thickness of the adhesive sheet disclosed here is not particularly limited, but is usually preferably about 0.07 mm or more (typically about 0.08 mm or more, preferably about 0.09 mm or more, more preferably about 0.10 mm or more, for example, about 0.07 mm or more). 0.12mm or more), or about 0.15mm or more. In addition, the total thickness of the adhesive sheet is usually preferably about 0.80 mm or less (typically about 0.50 mm or less, preferably about 0.40 mm or less, more preferably about 0.35 mm or less), and may be about 0.30 mm or less ( For example, about 0.25 mm or less, and further about 0.20 mm or less). By setting the total thickness of the adhesive sheet to be equal to or less than the above-mentioned upper limit value, it can be advantageous in terms of film reduction, miniaturization, weight reduction, and resource saving of products. Moreover, by making the total thickness of an adhesive sheet more than the said lower limit, it becomes possible to show outstanding impact resistance, waterproofness, dustproofness, etc.. In one aspect, the total thickness of the adhesive sheet can be in the range of about 0.07mm to 0.80mm (for example, about 0.08mm to 0.50mm), or it can also be in the range of 0.09mm to 0.40mm (typically, about 0.10mm to 0.35mm). , for example, a range of about 0.12mm to 0.30mm, and further to a range of about 0.12mm to 0.25mm), or a range of about 0.15mm to 0.35mm.

In the adhesive sheet disclosed herein, the ratio of the thickness Hs [mm] of the foam base material to the total thickness Ht [mm] of the adhesive sheet is not particularly limited. From the viewpoint of making it easier to effectively balance impact resistance and adhesive performance, it is usually appropriate to set Hs/Ht to be about 20 to 80%, preferably about 30 to 70% (for example, about 40 to 60%). ).

Furthermore, in the case of an adhesive sheet in a form in which the adhesive surface is protected by a release liner, the thickness of the release liner is not included in the total thickness of the adhesive sheet here. Therefore, in the double-sided adhesive sheet shown in FIG. 1, for example, the thickness Ht from the first adhesive surface 11A to the second adhesive surface 12A (that is, the thickness from one of the adhesive surfaces to the other adhesive surface) is used as The total thickness of the adhesive sheet.

The adhesive sheet disclosed herein can also be used without greatly impairing the effects of the present invention. Within the range, layers other than the foam base material and the adhesive layer (intermediate layer, primer layer, etc.. Hereinafter also referred to as "other layers") are included. For example, the other layers described above may be provided between the foam base material and the surface (adhesion surface) of the adhesive layer. In the adhesive sheet having such a configuration, the thicknesses of the other layers described above are included in the total thickness of the adhesive sheet.

The adhesive sheet of a preferred aspect of the technology disclosed herein is the 100% modulus M [N/mm ² substrate] of the adhesive sheet and the density D [ The relationship of g/cm ³ ] satisfies 9.0≦(M/D). An adhesive sheet satisfying such a relationship can be suppressed in the degree of performance degradation due to narrowing. Although the reason does not need to be clearly explained, it can be considered as follows, for example. That is, a larger M/D of the adhesive sheet means that the adhesive sheet exhibits higher resistance to tensile deformation in comparison with the density of the foam substrate. Here, when the adhesive sheet is deformed by tensile stress, the contact area (adhesion area) between the adhesive sheet and the adherend generally decreases. For a narrow adhesive sheet, since the adhesive area is small from the beginning, there is a tendency that the reduction of the adhesive area caused by the tensile deformation has a particularly large influence on the adhesive performance. An adhesive sheet with a larger M/D is less likely to reduce the adhesive area against tensile stress, and it is considered that this situation advantageously contributes to suppressing the degree of performance degradation caused by narrowing.

In a preferred aspect, the value of M/D may be greater than 9.5, may be greater than 10.0, and may be greater than 10.5 (eg, greater than or equal to 11.0). When the value of M/D becomes larger, there is a tendency that the degree of performance degradation due to narrowing can be suppressed more favorably. The upper limit of M/D is not particularly limited, but from the viewpoint of the ease of manufacture and availability of the foam base material, it is usually 50 or less, preferably 40 or less, more preferably 30 or less (for example, 25 or less). ). In a preferred aspect, M/D may be 20 or less, or 15 or less.

Here, the 100% modulus M [N/mm ² base material] of the adhesive sheet is measured as follows. That is, a sample (adhesive sheet) to be measured was cut into a size of 10 mm in width and 40 mm in length to prepare a test piece. At this time, the longitudinal direction of the test piece was oriented so as to coincide with the advancing direction (MD) of the sample. The test piece was placed vertically in the tensile testing machine with the test length (length between the chucks) set to 10 mm in a measurement environment with a temperature of 23 °C and 50% RH, and a tensile speed of 50 mm/min was Stretch vertically. The strength when the change rate of the above-mentioned test length is 100% (when extending to 20 mm) is converted into the strength per unit cross-sectional area of the foam base material, and the obtained value [N/mm ² base material] is used as the above-mentioned sample. 100% modulus on MD (hereinafter also referred to as "MD modulus").

Except that the longitudinal direction of the test piece is the width direction (TD) perpendicular to the MD of the sample, the 100% modulus [N/mm] in the TD of the sample is obtained in the same manner as in the above-mentioned measurement of the MD modulus. ² Substrate] (hereinafter also referred to as "TD modulus").

By averaging the above-mentioned MD modulus and the above-mentioned TD modulus, the 100% modulus M [N/mm ² base material] of the above-mentioned sample was obtained.

From the viewpoint of reducing the directional dependence of the impact resistance, it is preferable that the MD modulus and the TD modulus are not extremely different from each other. Although not particularly limited, the ratio of the MD modulus [N/mm ² base material] to the TD modulus [N/mm ² base material] can be set to, for example, 0.3 to 3, usually preferably 0.5 to 2. within the range, more preferably within the range of 0.6 to 1.5.

The 100% modulus M of the adhesive sheet disclosed here is not particularly limited, for example, it may be 2.5 N/mm ² or more for the base material. If the 100% modulus M of the adhesive sheet is high, even in a narrow adhesive sheet, there is a tendency that damage to the foam base material caused by an external force such as impact is better prevented. In addition, there is a tendency that it becomes easier to suppress the reduction in performance accompanying the narrowing. From this viewpoint, the 100% modulus M is preferably higher than 4.0 N/mm ² for the base material, more preferably 4.5 N/mm ² for the base material or more, and still more preferably 5.0 N/mm ² for the base material or more (typically and said more than 5.0 N/mm ² substrate, for example, 5.5 N/mm ² substrate or more). In a preferred aspect, the 100% modulus M of the adhesive sheet can be above 6.0 N/mm ² of the substrate. In addition, from the viewpoint of flexibility and the like, the 100% modulus M of the adhesive sheet is usually 12.0 N/mm ² or less for the base material, preferably 10.0 N/mm ² or less for the base material, and more preferably 8.0 N/mm ² base materials or less. The 100% modulus M of the adhesive sheet can be controlled by, for example, the degree of crosslinking or density (apparent density) of the foam substrate, the size or shape of the air cells, and the like.

Furthermore, with regard to the reason for expressing the 100% modulus M of the adhesive sheet as a value per unit cross-sectional area (/mm ² substrate) of the foam substrate, the adhesive layer is the adhesive sheet disclosed here due to the adhesive layer. The contribution to the 100% tensile strength is usually very small, so if the cross-sectional area of the adhesive layer is included when the above-mentioned tensile strength is converted into per unit cross-sectional area, the characteristics of the adhesive sheet suitable for the purpose of this application are It becomes difficult to grasp.

The adhesive sheet disclosed herein preferably has a 100% modulus M [N/mm ² substrate] and a density D [g/cm ³ ] of the foam substrate and an average cell diameter P [ μm] satisfies the following formula: 70≦(M/D)/(P×10 ⁻³ ). The adhesive sheet that satisfies the above formula has a foam base material with less performance degradation (for example, reduction in pressing force) due to narrowing, and a larger number of cells in terms of density, so for example, it can be It is excellent in the performance of maintaining the waterproofness or dustproofness even if it is impacted in a narrow width, as will be described later in terms of water resistance after being dropped. From the viewpoint of obtaining a more suitable effect, the value of (M/D)/(P×10 ^-3 ) is preferably 90 or more, more preferably 120 or more, still more preferably 150 or more, and may be 170 or more. The upper limit of the value of (M/D)/(P×10 ^-3 ) is not particularly limited, but is usually 700 or less, preferably 500 or less, from the viewpoints of easiness of material acquisition and easiness of manufacture, and typically It is 300 or less, and 250 or less may be sufficient as it. Furthermore, P in the above formula is a numerical value when the average bubble diameter converted from the above sphere is expressed in the unit of [μm], and P itself is a dimensionless number (P in other formulas described in this specification is also same).

A preferred aspect of the adhesive sheet is that the relationship between the 100% modulus M [N/mm ² substrate] and the 25% compressive strength C ₂₅ [kPa] of the foam substrate satisfies the following formula: 35≦M/( C ₂₅ × 10 ^-3 ). Such an adhesive sheet exhibits good cushioning properties against compressive stress and strong resistance to elongation, so that it has good shock absorption even in a narrow width, and the performance is reduced due to the narrow width. less. According to the adhesive sheet whose M/(C ₂₅ ×10 ^-3 ) is 40 or more (more preferably 45 or more, still more preferably 50 or more, for example, 55 or more), more favorable results can be achieved. The upper limit of M/(C ₂₅ ×10 ^-3 ) is not particularly limited, but may be, for example, 300 or less (preferably 200 or less, more preferably 150 or less, typically 100 or less).

A preferred other aspect of the adhesive sheet is 100% modulus M [N/mm ² substrate] and C ₂₅ [kPa] of the foam substrate and density D [g/cm ³ of the foam substrate ] satisfies the following formula: 10≦(M×D)/(C ₂₅ ×10 ⁻³ ). Since such an adhesive sheet has a high 100% modulus M in comparison with compressive strength and density, it tends to exhibit good cushioning properties against compressive stress and strong resistance to elongation. Therefore, even if it is a narrow width, it becomes possible to have favorable shock absorption, and to reduce the performance degradation by narrow width. According to the adhesive sheet in which (M×D)/(C ₂₅ ×10 ^-3 ) is 15 or more (eg, 18 or more), better results can be achieved. The upper limit of (M×D)/(C ₂₅ ×10 ^-3 ) is not particularly limited, but may be, for example, 50 or less (preferably 40 or less, typically 30 or less).

Another preferred aspect of the adhesive sheet of the technology disclosed herein is the 100% modulus M [N/mm ² substrate] of the adhesive sheet and the thickness Hs of the foam substrate constituting the adhesive sheet The relationship of [mm] satisfies 0.50≦M×Hs. Such an adhesive sheet tends to exhibit good impact resistance (for example, durability against drop impact) even if its width is narrowed. The reason for this is considered to be that the adhesive sheet with an M×Hs value of 0.50 or more generally exhibits high resistance to tensile deformation and is less likely to reduce the adhesive area due to tensile stress. Although not particularly limited, from the viewpoint of further improving the impact resistance of the narrow width, the value of M×Hs is preferably 0.60 or more, more preferably 0.70 or more (for example, more than 0.75), and still more preferably 0.80 or more ( e.g. 0.90 or more). The upper limit of the value of M×Hs is not particularly limited, but from the viewpoint of flexibility and the like, it is usually 10.0 or less, preferably 3.0 or less, and more preferably 2.0 or less (for example, 1.5 or less).

The pressing force of the adhesive sheet disclosed here is not particularly limited. A preferred aspect of the adhesive sheet has a pressing force of 70 N or more (more preferably 100 N or more, still more preferably 130 N or more, for example 170 N or more) when the width of the adhesive sheet is 1.0 mm. The bonding reliability of such an adhesive sheet is high, so it is preferable.

The above-mentioned pressing and bonding force is defined as the following maximum stress: by the adhesion of a window frame shape (called "frame shape" or simply "frame shape") with a width of 59cm, a length of 113cm, and a width of 1.0mm A sheet (typically, a double-sided adhesive sheet) was bonded by crimping a stainless steel (SUS) plate and a glass plate for 10 seconds under a load of 50 N, thereby producing a sample for evaluation. A load speed of /min presses the glass sheet in the thickness direction of the glass sheet from the inside to the outside up to the maximum stress observed during the separation of the glass sheet from the stainless steel sheet. More specifically, the pressing adhesion force can be measured in accordance with the procedure described in the embodiments to be described later. Furthermore, the pressing and bonding force of the single-sided adhesive sheet is as long as the adhesive surface is attached to the glass plate, and the surface without the adhesive layer is fixed to the SUS plate by a method other than adhesion and sufficient adhesive strength can be obtained. Just do the measurement.

In addition, in the following description, the pressing adhesion force measured using the window frame-shaped adhesive sheet of width 59 mm, vertical 113 mm, and width 1.0 mm as described above is expressed as "pressing adhesion force at a width of 1.0 mm" Or the case of "pressing adhesion force (1.0mm width)". Similarly, there is a method for expressing the pressing adhesion force measured using a window frame-shaped double-sided adhesive sheet of width 59 mm, vertical 113 mm, and width A mm as "pressing adhesion force at width A mm" or "pressing adhesion force (A mm) wide)”. The pressing adhesive force (A mm width) can be measured in the same manner as the pressing adhesive force (1.0 mm width), except that a window frame-shaped adhesive sheet having a width of 59 mm, a length of 113 mm, and a width of A mm is used.

In a preferred aspect of the adhesive sheet, the pressing force S _1.0 [N] when the width is 1.0 mm is set to 100%, and the pressing force S _0.3 [N] when the width is 0.3 mm is 27% or more of S _1.0 . That is, S _0.3 /S _1.0 is 27% or more. More preferably, S _0.3 /S _1.0 is 30% or more (for example, more than 30%). The value of S _0.3 /S _1.0 is preferably as close to 100% as possible, and therefore the upper limit is not particularly limited, but is usually 50% or less, typically 40% or less.

Furthermore, the above-mentioned S _0.3 is a numerical value representing the pressing force when the width is 0.3 mm in the unit of [N] (Newton), and S _0.3 itself is a dimensionless number. The same applies to S _1.0 and S _0.5 and S _0.7 described later.

Another preferred aspect of the adhesive sheet is to set the pressing and bonding force S _1.0 [N] when the width is 1.0 mm to 100%, and the pressing and bonding force S _0.5 [N] when the width is 0.5 mm is more than 50% of S _1.0 , more preferably more than 50% (for example, more than 52%). The closer the value of S _0.5 /S _1.0 is to 100%, the better. Therefore, the upper limit is not particularly limited, but is usually 70% or less, typically 60% or less.

As described above, the reduction ratio of the pressing adhesive force is equal to or less than the same (preferably 1.1 times or less, more preferably 1.0 times or less, for example, less than 1.0 times) in comparison with the reduction ratio of the width. Since the reduction in the pressing force due to the narrow width is small, it can be suitably used, for example, in the form of a joining member having a portion with a width of less than 1.0 mm (typically, a linear portion with a width of less than 1.0 mm) in at least one part. .

In addition, the small decrease in the pressing force due to the narrowing of the adhesive sheet means that the pressing force varies less with respect to the variation in width (especially, within a range of 1 mm or less in width). Such an adhesive sheet can be used suitably in the form of a joining member which has a linear part in at least one part, and the width|variety of the said linear part differs in one part and another part. For the adhesive sheet having parts with different widths as described above (especially the joint member whose width of at least a part of the linear part is less than 1.0mm), if the adhesive performance (such as pressing and bonding force) caused by the different widths ) is too large, the strain is concentrated in the part where the width changes, which can become the starting point of peeling of the adhesive sheet or damage to the foam substrate. The pressure-sensitive adhesive sheet having a small change in the pressing force with respect to the width change is less likely to be peeled or damaged as described above, and thus can be excellent in impact resistance.

Although not particularly limited, the adhesive sheet disclosed herein preferably satisfies at least one of the following conditions: the pressing force (0.7mm width) is 50N or more (more preferably 70N or more, further more preferably 90N or more, for example 120N or more); pressing adhesion force (0.5mm width) is 35N or more (more preferably 50N or more, more preferably 65N or more, for example, 85N or more); and pressing adhesion force (0.3mm width) is 20N or more (more preferably 30N or more, more preferably 40N or more, for example, 50N or more).

Such an adhesive sheet can be excellent in adhesion reliability and is also suitable for narrowing.

The adhesive sheets disclosed herein can have desired optical properties (transmittance, reflectance, etc.). For example, the visible light transmittance of the adhesive sheet used in the light-shielding application is preferably 0% or more and 15% or less (more preferably 0% or more and 10% or less). Moreover, the visible light reflectance of the adhesive sheet used for the light reflection application is preferably 20% or more and 100% or less (more preferably 25% or more and 100% or less). The optical properties of the adhesive sheet can be adjusted by, for example, coloring the foam base material as described above.

The adhesive sheet disclosed here is preferably a halogen-free type from the viewpoint of preventing corrosion of metals. In the case where the adhesive sheet is a halogen-free type, it can be an advantageous feature when, for example, the adhesive sheet can be used for fixing electric/electronic parts. Moreover, since generation of the halogen-containing gas at the time of combustion can be suppressed, it is also preferable from the viewpoint of reducing the environmental burden. The halogen-free adhesive sheet can be obtained by using the following methods alone or in a suitable combination: not intentionally using a halogen compound as a raw material for the foam substrate or adhesive; Foam base material; in the case of using additives, additives derived from halogen compounds, etc. are not used.

The object to which the adhesive sheet disclosed herein is attached (adhered body) is not particularly limited. The adhesive sheet disclosed here can be used, for example, in the form of being attached to an adherend including the following materials: metal materials such as stainless steel (SUS) and aluminum; inorganic materials such as glass and ceramics; polycarbonate (PC) , polymethyl methacrylate (PMMA), polypropylene, polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer resin (ABS), impact-resistant polystyrene (HIPS) ), PC-ABS blended resin, PC-HIPS blended resin and other resin materials; natural rubber, butyl rubber and other rubber materials; and composite materials of these.

The adhesive sheet disclosed herein has less performance degradation due to narrowing, and thus can become suitable as an adhesive sheet used for bonding or fixing purposes in mobile devices requiring strong narrowing. . Moreover, since the adhesive sheet disclosed here contains a foam base material, it can be excellent in shock absorption, waterproofness, dustproofness, and the like. This feature can be used to better apply to electronic equipment, such as the display part of portable electronic equipment For fixing, for fixing display protection components of portable electronic devices, for fixing keyboard module components for mobile phones, for fixing decorative panels of TVs, for fixing battery packs of personal computers, for lens waterproofing of digital video cameras, etc. in use. As a particularly preferable use, a portable electronic device use can be mentioned. In particular, it can be preferably used in a portable electronic machine with a liquid crystal display device. For example, in such a portable electronic device, it is suitable for the purpose of joining a display part (which can be a display part of a liquid crystal display device) or a display part protective member to a casing.

In addition, the said display part protection member is a member which has the area|region which shows translucency in the thickness direction typically (henceforth a "translucent member"), and may be called a "lens". Here, the term "lens" in this specification includes both the concept of a person exhibiting a refracting action of light and a person not exhibiting a refracting action of light. That is, the "lens" in this specification also includes a translucent member that does not have a refraction effect, for example, a protective panel that simply protects the display portion of a portable electronic device. The said protection panel can also be grasped as a display part protection member or a display part cover member which has translucency. When the above-mentioned protective panel is made of glass, the protective panel may also be called "cover glass". However, the material of the above-mentioned protective panel or the above-mentioned lens is not limited to glass, as long as it is a material that can exhibit light transmittance.

In addition, in this specification, the so-called portable electronic device generally refers to an electronic device that is carried and used, and is not particularly limited other than that. The so-called "carrying" here is not sufficient if it is simply carried, but refers to a level of portability that can be carried relatively easily by an individual (standard adult). Examples of the so-called "portable electronic device" here include mobile phones, smart phones, tablet PCs, notebook PCs, and the like. Such a portable electronic device may also be a terminal of a so-called wearable type (for example, a wristband type such as a watch type, a head-mounted type such as a glasses type, and the like). For example, the above-mentioned portable electronic devices may have telephones, clocks, cameras, glasses, personal computers and other information terminals, health management tools such as sphygmomanometers or pulse meters, and pedometers, music players, animation players, audio recording, video recording, etc. 1 or more than 2 functions.

The adhesive sheets disclosed herein can be in the form of joining members processed into various profiles. It is used to join or fix the parts constituting the portable electronic equipment (such as the display part or the joint of the display part protective member and the casing, preferably a light-transmitting display part protective member (typically a protective panel) connection to the housing). As a preferable form of such a joining member, there is a narrow portion having a width of less than 2.0 mm, and the average width W [mm] of the narrow portion is less than 1.0 mm (more preferably 0.7 mm or less, still more It is preferably a form of 0.5 mm or less, for example, 0.3 mm or less). According to the adhesive sheet disclosed herein, even when it is used as a joining member having such a narrow portion shape (eg, frame shape), good performances (pressing adhesive force, shock absorption, etc.) can be exhibited. In addition, the average width W [mm] of the narrow width part of an adhesive sheet is obtained by dividing the total area of the narrow width part contained in this adhesive sheet by the total length. When the width of the narrow portion is constant, the width of the narrow portion is the same as the above average width.

The narrow width portion is typically linear. The linear shape here refers to a concept that includes not only a linear shape, a curved shape, a broken line shape (for example, an L-shape), but also an annular shape such as a frame shape or a circular shape, or a composite shape or an intermediate shape thereof. The above-mentioned so-called annular refers to the following concept: not limited to being formed by a curved line, but also includes, for example, a shape along the outer periphery of a quadrangle (frame shape) or a shape along the outer periphery of a fan shape, and a part or the whole of which is formed in a straight line. ring. The length of the said narrow width part is not specifically limited. For example, in the form in which the length of the above-mentioned narrow portion is 10 mm or more (typically 20 mm or more, for example, 30 mm or more), the effect of applying the technique disclosed herein can be suitably exerted. The width of the above-mentioned narrow width portion may be constant or may be partially different.

With regard to the adhesive sheet disclosed here, according to the relationship with the 100% modulus M [N/mm ² base material] of the adhesive sheet and the thickness Hs [mm] of the foam base material, the above-mentioned narrow width portion can be The average width W [mm] is preferably used in a shape of 0.4/(M×Hs) or more. According to the adhesive sheet of such a shape, a junction portion having good impact resistance can also be formed between the narrow portion and the adherend. Adhesive sheet according to a shape in which the average width W [mm] of the narrow portion is 0.5/(M×Hs) or more (more preferably 0.6/(M×Hs) or more, for example, 0.7/(M×Hs) or more) , it can achieve better performance (for example, the performance of forming a joint whose waterproofness or dustproofness is hardly damaged even if it is impacted by a drop).

The adhesive sheet disclosed here can take advantage of the advantages of good bonding performance, waterproof performance (for example, waterproof performance after being dropped), dustproof performance, etc., even if the width is narrowed, and can be in the form of an annular bonding member having the above-mentioned narrow width portion. It is suitably used, for example, as a fixing member for fluid-tightly joining a display portion of a portable electronic device or a display portion protection member to a casing, thereby protecting the electronic device accommodated in the casing from water or The effect of dust. Therefore, according to the present specification, there is provided a fixing member for fixing a display portion or a display portion protective member of a portable electronic device to a casing comprising any of the adhesive sheets disclosed herein. The above-mentioned fixing member typically has an annular planar shape. The ring shape of the ring-shaped fixing member is not particularly limited, and may be, for example, a rectangle (frame shape), a circle, a polygon other than a rectangle (eg, a triangle), and other special shapes. Moreover, in the above-mentioned concept of ring, in addition to a ring that includes one sheet and is completely closed (that is, a ring without joints), the following shapes are also included: The end and the end of the material are overlapped to form a closed loop shape; or the end and the end of one sheet or a plurality of sheets are arranged in a close manner, and the above-mentioned close arrangement is sealed as needed. The shape of a closed loop can be formed. Furthermore, the so-called proximity here includes the concept of abutment (the state where the distance is zero). 0.1 to 5 mm), more preferably 0 to 2 mm (typically 0.1 to 2 mm), and still more preferably 0 to 1 mm (typically 0.1 to 1 mm). As a method of sealing the overlapping portion or the portion that is close (for example, abutting), a method of packing with a sealing material such as an adhesive, or a method of welding the ends to each other (for example, heat welding) can be used.

In addition, the adhesive sheet disclosed here can utilize the feature of less variation in adhesive performance (for example, pressing adhesive force) with respect to variation in width (especially variation within a range of 1 mm or less in width), and is preferably in the following form Used as the above-mentioned joint member (for example, a fixing structure used to fix the display part of the portable electronic device or the display part protection member on the casing piece), that is, a shape (typically annular) that continuously includes a portion W1 having a first width and a portion W2 having a second width greater than the first width, and the first width is less than 1 mm form. Since the concentration of the strain at the part where the width changes (the turning point between the W1 part and the W2 part) is alleviated in such a joint member, peeling of the adhesive sheet or damage to the foam base material starting from this part is less likely to occur. Therefore, it can become excellent in impact resistance.

Furthermore, the matters disclosed by this specification include the following.

(1) An adhesive sheet having an adhesive layer on at least one surface of a foam base material, and the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet and the above-mentioned foam The relationship of the density D [g/cm ³ ] of the bulk substrate satisfies 9.0≦(M/D).

(2) An adhesive sheet having an adhesive layer on at least one surface of a foam base material, and the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet and constituting the adhesive The relationship of the thickness Hs [mm] of the foam base material of the sheet satisfies 0.75<M×Hs.

(3) The adhesive sheet according to the above (1) or (2), wherein the 100% modulus M of the above-mentioned adhesive sheet is higher than 4.0 N/mm ² of the base material.

(4) The adhesive sheet according to any one of (1) to (3) above, wherein the thickness Hs of the foam base material is 0.10 mm to 0.30 mm.

(5) The adhesive sheet according to any one of the above (1) to (4), wherein the visible light transmittance of the adhesive sheet is 0% or more and 15% or less.

(6) The adhesive sheet according to any one of (1) to (5) above, wherein the foam base material is colored black.

(7) The adhesive sheet according to any one of (1) to (6) above, wherein the foam base material is a polyolefin-based foam base material.

(8) The adhesive sheet according to any one of (1) to (7) above, wherein the foam base material is a polyethylene-based foam base material.

(9) The adhesive sheet according to any one of the above (1) to (8), which is constituted in the form of a double-sided adhesive sheet having an adhesive layer on both surfaces of the foam base material.

(10) The adhesive sheet according to any one of (1) to (9) above, wherein the adhesive layer has a thickness of 20 μm to 80 μm.

(11) The adhesive sheet according to any one of the above (1) to (10), wherein the total thickness Ht of the adhesive sheet is 0.10 mm to 0.35 mm (eg, 0.15 mm to 0.35 mm).

(12) The adhesive sheet according to any one of the above (1) to (11), wherein the percentage of the thickness Hs [mm] of the foam base material in the total thickness Ht [mm] of the adhesive sheet The ratio is 30~70%.

(13) The adhesive sheet according to any one of (1) to (12) above, wherein the adhesive layer is an adhesive layer using an acrylic polymer as a base polymer.

(14) The adhesive sheet according to any one of the above (1) to (13), wherein the adhesive layer is an adhesive layer using an acrylic polymer as a base polymer, and the Tg of the acrylic polymer is - Below 40℃.

(15) The adhesive sheet according to any one of the above (1) to (14), wherein the adhesive layer is an adhesive layer using an acrylic polymer as a base polymer, and the adhesive layer used in the synthesis of the acrylic polymer is In the total amount of the monomers used, the proportion of the monomers whose Tg of the homopolymer is -45°C or lower is 70% by weight or more (preferably 85% by weight or more).

(16) The adhesive sheet according to any one of the above (1) to (15), wherein the adhesive layer is an adhesive layer using an acrylic polymer as a base polymer, and the adhesive layer used in the synthesis of the acrylic polymer is 0.2 to 8% by weight of the total amount of monomers used is a monomer containing a carboxyl group.

(17) The adhesive sheet according to any one of (1) to (16) above, wherein the adhesive layer contains 20 to 80 parts by weight of tackifier with respect to 100 parts by weight of the base polymer of the adhesive layer resin.

(18) The adhesive sheet according to any one of (1) to (17) above, wherein the adhesive layer contains a softening point of 20 to 60 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer It is a tackifying resin above 120℃.

(19) The adhesive sheet according to any one of (1) to (18) above, wherein the adhesive layer is cross-linked by an isocyanate-based cross-linking agent.

(20) The adhesive sheet according to any one of the above (1) to (19), wherein the pressing force S _1.0 [N] when the width is 1.0 mm and the pressing force S _0.3 [N] when the width is 0.3 mm The relationship satisfies the following formula: 0.3≦S _0.3 /S _1.0 .

(21) An adhesive sheet having an adhesive layer on at least one surface of a foam substrate, and a double-sided adhesive sheet having an adhesive layer on both surfaces of the foam substrate The foam base material is a polyethylene foam base material, the adhesive layer is an adhesive layer with an acrylic polymer as the base polymer, and the acrylic polymer is synthesized in the More than 85% by weight of the total amount of monomers used are monomers whose Tg of the homopolymer is below -45°C, and the above-mentioned adhesive layer contains 20-80 parts by weight relative to 100 parts by weight of the above-mentioned base polymer. For the tackifying resin, the thickness Hs of the foam base material is 0.06mm~0.30mm (for example, 0.10mm~0.30mm), and the total thickness Ht of the adhesive sheet is 0.10mm~0.35mm (for example, 0.15mm~0.35mm) ), the relationship between the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet and the density D [g/cm ³ ] of the above-mentioned foam base material satisfies 9.0≦(M/D).

(22) An adhesive sheet having an adhesive layer on at least one surface of a foam substrate, and a double-sided adhesive sheet having an adhesive layer on both surfaces of the foam substrate The foam base material is a polyethylene foam base material, the adhesive layer is an adhesive layer with an acrylic polymer as the base polymer, and the acrylic polymer is synthesized in the In the total amount of the monomers used, more than 85% by weight of the homopolymer is a monomer whose Tg is below -45°C, and the above-mentioned adhesive layer contains 20-80 parts by weight relative to 100 parts by weight of the above-mentioned base polymer. For the tackifying resin, the thickness Hs of the above-mentioned foam base material is 0.06mm~0.30mm (for example, 0.10mm~0.30mm), the total thickness Ht of the above-mentioned adhesive sheet is 0.15mm~0.35mm, and 100 mm of the above-mentioned adhesive sheet The relationship between the % modulus M [N/mm ² base material] and the thickness Hs [mm] of the foam base material constituting the adhesive sheet satisfies 0.75<M×Hs.

(23) The adhesive sheet according to any one of (1) to (22) above, which is used for bonding parts of portable electronic equipment.

[Example]

Hereinafter, some embodiments related to the present invention will be described, but the present invention is not intended to be limited to those shown in the embodiments. In addition, in the following description, "part" and "%" are based on weight unless otherwise specified.

<Production of adhesive sheet>

(example 1)

Into a reaction vessel with a stirrer, a reflux condenser, a thermometer, a dripping device and a nitrogen introduction tube, put 2.9 parts of acrylic acid, 5 parts of vinyl acetate, 92 parts of n-butyl acrylate, 0.1 part of 2-hydroxyethyl acrylate, and As a polymerization solvent, 30 parts of ethyl acetate and 120 parts of toluene were stirred for 2 hours while introducing nitrogen gas.

After the oxygen in the polymerization system was removed as described above, 0.2 part of 2,2'-azobisisobutyronitrile (AIBN) was added, the temperature was raised to 60°C, and a polymerization reaction was carried out for 6 hours to obtain a polymer containing a polymer solution. The solid content of the polymer solution was 40.0%, and the Mw of the polymer was 50×10 ⁴ .

In the above polymer solution, with respect to 100 parts of the polymer in the polymer solution, the trade name "PENSEL D-125" (rosin-based tackifier resin, solid content of 100% manufactured by Arakawa Chemical Industry Co., Ltd.) was added. ) 10 parts, trade name "SUPER ESTER A-100" (rosin-based tackifier resin, solid content of 100%) manufactured by Arakawa Chemical Industry Co., Ltd. 10 parts, trade name "Foralyn 8020F manufactured by Eastman Chemical Co., Ltd." ” (rosin-based tackifier resin, solid content: 100%) 5 parts, and Arakawa Chemical Industry Co., Ltd. trade name “Tamanol 803L” (terpene phenol resin, solid content: 100%) 15 parts, stir well until dissolved. Further, an aromatic polyisocyanate (trade name "CORONATE L", available from Japan Polyurethane Industry Co., Ltd.) was added as a crosslinking agent at a ratio of 2.0 parts to 100 parts of the polymer in the polymer solution. Company manufacture, solid content is 75%), and it stirred well to obtain a solvent-based adhesive composition.

Two commercially available release liners (trade name "SLB-80W3D", manufactured by Sumika Paper Co., Ltd.) were prepared. The above-mentioned adhesive composition was coated on one surface (release surface) of each of these release liners so that the thickness after drying was 50 μm, and dried at 100° C. for 2 minutes, whereby the above-mentioned two release liners were applied. Adhesive layers are respectively formed on the peeling surfaces of the pads. These adhesive layers were respectively attached to a polyethylene-based foam sheet (thickness: 0.15 mm, density: 0.56 g/cm ³ , 10% compressive strength (C ₁₀ ) that had been subjected to corona discharge treatment on both sides; 167 kPa, 25% compressive strength (C ₂₅ ) of 468 kPa, 30% compressive strength (C ₃₀ ) of 627 kPa, average cell diameter of 55 μm; hereinafter referred to as “substrate 1A”) on both sides. The above-mentioned release liner is directly left on the adhesive layer to protect the surface (adhesive surface) of the adhesive layer. After passing the obtained structure once through a laminator (0.3 MPa, speed of 0.5 m/min) at 80°C, it was aged in an oven at 50°C for one day. Thus, the double-sided adhesive sheet of Example 1 was obtained.

(Example 2)

A polyethylene-based foam sheet (thickness: 0.15 mm, density: 0.56 g/cm ³ , 10% compressive strength (C ₁₀ ): 100 kPa, 25% compressive strength (C ₂₅ ) with corona discharge treatment on both sides was used. ) was 365 kPa, the 30% compressive strength (C ₃₀ ) was 515 kPa, and the average cell diameter was 155 μm; hereinafter referred to as “substrate 1B”) instead of the substrate 1A, the same procedure as in Example 1 was carried out to obtain Example 2 Double-sided adhesive sheet.

(Example 3)

A polyethylene-based foam sheet (thickness 0.15 mm, density 0.37 g/cm ³ , 10% compressive strength (C ₁₀ ), 34 kPa, 25% compressive strength (C ₂₅ ) with corona discharge treatment on both sides was used. ) was 92 kPa, the 30% compressive strength (C ₃₀ ) was 117 kPa, and the average cell diameter was 90 μm; hereinafter referred to as “substrate 2A”) instead of the substrate 1A, the same operation as in Example 1 was carried out to obtain Example 3 Double-sided adhesive sheet.

(Example 4)

A polyethylene-based foam sheet (thickness: 0.20 mm, density: 0.20 g/cm ³ , 10% compressive strength (C ₁₀ ): 19 kPa, 25% compressive strength (C ₂₅ ) with corona discharge treatment on both sides was used ) was 47 kPa, the 30% compressive strength (C ₃₀ ) was 59 kPa, and the average bubble diameter was 90 μm; hereinafter referred to as “substrate 3A”) instead of the substrate 1A, the same operation as in Example 1 was carried out to obtain Example 4. Double-sided adhesive sheet.

(Example 5)

Except for using a polyethylene-based foam sheet (thickness: 0.08 mm, density: 0.56 g/cm ³ , 10% compressive strength (C ₁₀ ): 148 kPa, 25% compressive strength (C ₂₅ ) is 448kPa, 30% compressive strength (C ₃₀ ) is 617kPa, and the average bubble diameter is 55μm; hereinafter referred to as "substrate 4A") instead of the aspect of substrate 1A, and will be attached to both sides of the substrate 4A Except that the thickness of the adhesive bond layer was all set to 35 micrometers, it carried out similarly to Example 1, and obtained the double-sided adhesive sheet of Example 5.

For the double-sided adhesive sheet of each example (original adhesive sheet for fixing member production), the MD modulus and TD modulus were measured by the above-mentioned methods. As a result, the MD modulus of Example 1 was 6.5N/ ^mm2 . TD modulus is 6.2N/mm ² substrate, MD modulus of Example 2 is 5.6N/mm ² substrate, TD modulus is 4.5N/mm ² substrate, MD modulus of Example 3 is 4.5N/mm ² substrate, TD modulus is 6.5N/mm ² substrate, MD modulus of example 4 is 6.1N/mm ² substrate, TD modulus is 3.1N/mm ² substrate, MD modulus of example 5 is 6.4N/mm ² substrate, TD modulus is 6.2N/mm ² substrate. Table 1 shows the results of determining the 100% modulus M [N/mm ² base material], M/D, and M×Hs of the adhesive sheet of each example from these equivalent values.

<Pressure Adhesion Force Measurement>

The double-sided adhesive sheet was cut into a window frame shape (frame shape) having a width of 59 mm, a length of 113 mm, and a width of 1.0 mm as shown in FIG. 2 to obtain a window frame-shaped double-sided adhesive sheet. Using this window frame-shaped double-sided adhesive sheet, a glass plate (Gorilla glass manufactured by Corning, Inc.; the same below) with a width of 59 mm, a length of 113 mm, and a thickness of 1 mm was attached to a central portion having a diameter of 15 mm with a load of 50 N. A stainless steel plate (SUS plate) (70 mm in width, 130 mm in length, and 2 mm in thickness) of the through-holes was press-bonded for 10 seconds, and by this bonding, a sample for evaluation was obtained.

Fig. 2 is a schematic view of the above-mentioned sample for evaluation, wherein (a) is a plan view and (b) is a cross-sectional view thereof AA'. In FIG. 2 , reference numeral 2 denotes a window frame-shaped double-sided adhesive sheet, reference numeral 21 denotes a SUS plate, reference numeral 22 denotes a glass plate, and reference numeral 21A denotes a through hole provided in the SUS plate 21 .

The samples for evaluation were placed in a universal tensile and compressive testing machine (device name "Tensile Compression"). shrinkage tester, TG-1kN", manufactured by Minebea Co., Ltd.). Then, the round bar was passed through the through hole of the SUS plate, and the round bar was lowered at a speed of 10 mm/min, thereby pressing the glass plate in a direction away from the SUS plate. Next, the maximum stress observed during the period until the glass plate and the SUS plate were separated was measured as the pressing force. In addition, the measurement was performed in the environment of 23 degreeC and 50%RH.

3 is a schematic cross-sectional view showing a method of measuring the pressing force, the reference numeral 2 is a window frame-shaped double-sided adhesive sheet, the reference numeral 21 is a SUS plate, the reference numeral 22 is a glass plate, the reference numeral 23 is a round bar, and the reference numeral 24 is a support tower. The sample for evaluation was fixed on the support table 24 of the above-mentioned testing machine as shown in FIG. 3 , and the glass plate 22 of the sample for evaluation was pressed by the round bar 23 passing through the through hole 21A of the SUS plate 21 . Furthermore, in the above-mentioned measurement of the pressing adhesion force, the SUS plate 21 was not bent or damaged by the load applied by pressing the glass plate 22 with the round bar 23 .

Except having changed the width|variety of the said window frame-shaped adhesive sheet to 0.7 mm, 0.5 mm, and 0.3 mm, it carried out similarly to the above, and produced the sample for evaluation, and similarly measured the pressing adhesion force.

The obtained results are shown in Table 2. "-" in the table means no evaluation.

As shown in Table 2, if the adhesive sheet of Example 1 using the base material A1 is compared with the adhesive sheet of Example 2 using the base material B1, the retention rate of the pressing force when the width of Example 1 is 0.5 mm (S _0.5 /S _1.0 ) is higher, and the advantage of Example 1 is more obvious with regard to the retention rate of the pressing and bonding force (S _0.3 /S _1.0 ) when the width is 0.3 mm. As a result, although the pressing and bonding force at a width of 1.0 mm was the same as that of Example 1 and Example 2, the pressing and bonding force at a width of 0.5 mm was about 10% higher than that of the adhesive sheet of Example 1, and the pressing force was about 0.3 mm wide. Then the force system example 1 is more than 20% higher. In addition, about a commercially available adhesive sheet including an acrylic pressure-sensitive adhesive layer and not having a foam base material, the pressure-bonding force of each of the sample widths was measured in the same manner, and calculated from the results (S _0.5 /S _1.0 ) And (S _0.3 /S _1.0 ), the results (S _0.5 /S _1.0 ) were 46%, and (S _0.3 /S _1.0 ) was 20%.

<Drop durability test>

The double-sided adhesive sheet was cut into a window frame shape (frame shape) with a width of 59 mm, a length of 113 mm, and a width of 1.0 mm as shown in Figures 4(a) and (b) to obtain a window frame-shaped double-sided adhesive sheet. Using the window frame-shaped double-sided adhesive sheet, a polycarbonate plate (70mm in width, 130mm in height, 2mm in thickness) and a glass plate (59mm in width, 113mm in length, 0.5mm in thickness) were crimped for 10 seconds with a load of 50N. In this way, bonding was performed to obtain a sample for evaluation.

FIGS. 4( a ) and ( b ) are schematic views of the sample for evaluation, (a) is a plan view, and ( b ) is a BB′ cross-sectional view. In FIG. 4, the code|symbol 3 is a window frame-shaped double-sided adhesive sheet, the code|symbol 31 is a polycarbonate plate, and the code|symbol 32 is a glass plate.

A plumb of 160 g was attached to the back surface of the polycarbonate plate of the sample for evaluation (the surface on the opposite side to the surface to be attached to the glass plate). A drop test was performed on the sample for evaluation with the above-mentioned plumb at normal temperature (about 23° C.), that is, it was freely dropped 60 times from a height of 1.2 m onto a concrete plate. At this time, the direction of falling was adjusted so that the six surfaces of the sample for evaluation described above were sequentially turned downward. That is, 10 cycles of one drop pattern are performed on each of the six surfaces.

Moreover, the number of times of dropping until the polycarbonate plate and the glass plate peeled off (separated) was evaluated as the drop durability at room temperature by visually observing whether or not the bonding between the polycarbonate plate and the glass plate was maintained per drop. The state where peeling was not confirmed even after being dropped 60 times was evaluated as "more than 60".

Except having changed the width of the said window frame-shaped adhesive sheet to 0.7 mm, 0.5 mm, and 0.3 mm, it carried out similarly to the above, produced the sample for evaluation, and performed the drop durability test similarly.

<Water resistance test after falling>

According to IPX7 standard (JIS C 0920/IEC60529), the water resistance of the sample for evaluation after the above-mentioned drop durability test (after being dropped 60 times) was evaluated. That is, the sample for evaluation after the above-mentioned drop durability test was immersed in a water tank with a water depth of 1 m for 30 minutes in a standard state (23° C., 50% RH), and the presence or absence of water seepage into the interior was confirmed.

The obtained results are shown in Table 3.

<Dustproof test>

The dust resistance test was performed using the dust resistance evaluation test apparatus shown in FIGS. 5 and 6 . Here, FIG. 5 is an exploded perspective view showing a schematic configuration of a dustproof evaluation test apparatus, and FIG. 6 is a cross-sectional view of the dustproof evaluation test apparatus. In Figs. 5 and 6, reference numeral 120 denotes a dustproof evaluation test device, reference numeral 121 denotes a top plate, reference numeral 122 denotes a spacer, reference numeral 123 denotes a double-sided adhesive sheet obtained by punching a frame shape into a window frame shape, and reference numeral 125 denotes evaluation. In the case of the case, reference numeral 127 denotes an opening (a square shape with a length of one side of 52 mm), and reference numeral 128 denotes a space portion. The dust-proofness evaluation test apparatus 120 can form a substantially cuboid-shaped sealable space portion 128 inside by screwing a substantially quadrangular flat top plate 121 to the evaluation box 125 . Furthermore, the opening portion 127 is an opening portion of the space portion 128 . In addition, the top plate 121 has a quadrilateral (trapezoid) cutout in plan view that serves as an opening.

On the lower surface facing the opening 127 of the top plate 121, a square plate-shaped spacer 122 larger than the opening 127 is mounted so as to face the entire surface of the opening 127. A double-sided adhesive sheet 123 having a window of substantially the same size as the opening 127 is installed on the lower surface of the spacer 122 at a position opposite to the opening 127 . Therefore, by screwing the top plate 121 , the double-sided tape 123 is fixed between the spacer 122 and the peripheral edge of the opening 127 . Therefore, by screwing the top plate 121 to the evaluation case 125 , the space portion 128 in the evaluation case 125 is sealed by the tape 123 and the spacer 122 . The thickness of the spacer 122 is selected according to the total thickness of the adhesive sheet of the evaluation object so as to compensate for the difference in the total thickness of the adhesive sheet of each example.

From the opening 127 in the box 125 for evaluation, 0.1 g of cornstarch as dust is put into the space 128, the spacer 122 is arranged through the window frame-shaped double-sided tape 123, and the top plate 121 is screwed to the evaluation. The dust-proofness evaluation test apparatus 120 which accommodated the above-mentioned dust (not shown) in the space part 128 sealed with the window frame-shaped double-sided tape 123 was produced by the case 125. This dustproofness evaluation test apparatus 120 was put into a drum-type drop tester (rotary-type drop tester), and was rotated at a speed of 3 rpm. The device was stopped every 10 rotations, the dust-proof evaluation test device 120 was taken out, and the dust contained in the space portion 128 was visually observed whether or not the dust was exposed from the seal of the window frame-shaped double-sided tape 123 and adhered to the dust-proof evaluation test device 120. On the outer surface, record the number of revolutions until dust adhesion is confirmed.

The double-sided adhesive sheet of each example was used to form a frame shape having a square opening with a length of 52 mm on one side and a width of 1 mm (that is, the outer peripheral shape was a square shape with a side of 54 mm) or a width of 0.5 mm. The window frame-shaped double-sided tape 123 punched so as to have a frame shape of mm (that is, the outer peripheral shape is a square shape with one side of 53 mm) was subjected to the above-mentioned dustproof test. The results are shown in Table 3.

As shown in Table 3, in the evaluation with a width of 1.0 mm, the adhesive sheets of Examples 1 and 2 both showed good drop durability and water resistance after dropping, and no particularly poor performance was found. On the other hand, in the case of a width of 0.5 mm and a width of 0.3 mm, the drop of the adhesive sheet of Example 1 Durability is significantly higher. In addition, in the evaluation of width 0.7 mm, no difference was found in the drop durability, but the adhesive sheet of Example 2 showed water seepage in the water repellency test after being dropped, and it was found that the adhesive sheet was damaged. On the other hand, when the width of the adhesive sheet of Example 1 was 0.7 mm, it also showed good water repellency after the drop durability test. In addition, when the width of the adhesive sheet of Example 5 was 0.5 mm or more, the same as the adhesive sheet of Example 1, it showed good drop durability and water resistance after being dropped, and also showed the adhesiveness of Comparative Example 2 when the width was 0.3 mm. The sheet has higher drop durability. In addition, the dustproof properties of the adhesive sheets of Examples 1 and 5 were superior to those of the adhesive sheet of Example 2 when the width was 1.0 mm and the width was 0.5 mm.

From the above evaluation results, it can be seen that, compared with the adhesive sheet of Example 2, the adhesive sheets of Examples 1 and 5 have less reduction in performance with narrowing. In the adhesive sheets of Example 1 and Example 5, the use of the adhesive sheet of Example 2 and the use of the foam base material with a smaller average cell diameter favorably contributed to the difference in the water repellency after dropping with a width of 0.7 mm. In addition, the value of (M/D)/(P×10 ⁻³ ) obtained as the ratio of the value of M/D to the average bubble diameter P [μm] was 207.8 in Example 1 and 207.8 in Example 2. It was 57.6 in Example 3, 165.2 in Example 4, 255.6 in Example 4, and 201.3 in Example 5.

The specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the patent application. Various changes and modifications to the specific examples illustrated above are also included in the technology described in the scope of the patent application.

1‧‧‧Double-sided adhesive sheet

11‧‧‧First Adhesive Layer

11A‧‧‧First Adhesive Surface

12‧‧‧Second adhesive layer

12A‧‧‧Second Adhesive Surface

15‧‧‧Foam substrate

15A‧‧‧Side 1

15B‧‧‧Side 2

17‧‧‧Release liner

17A‧‧‧Front of release liner

17B‧‧‧Back side of release liner

Hs‧‧‧Thickness of foam substrate

Ht‧‧‧Total thickness of adhesive sheet

Claims (8)

An adhesive sheet, which is provided with an adhesive layer on at least one surface of a foam base material, the adhesive layer is an adhesive layer with an acrylic polymer as a base polymer, and the weight of the acrylic polymer The average molecular weight (Mw) is 20×10 ⁴ to 75×10 ⁴ , and the above-mentioned adhesive layer contains 20 to 60 parts by weight of the base polymer of the adhesive layer relative to 100 parts by weight of the base polymer. The softening point is an increase of 120°C or higher. Adhesive resin, and the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet is higher than 4.0 and 12.0 or less, and the 100% modulus M [N/mm ² base material] of the above-mentioned adhesive sheet is the same as the above The relationship between the density D[g/cm ³ ] of the foam base material satisfies 9.0≦(M/D)≦50, and the pressing force of the adhesive sheet when the width is 1.0 mm is 70N or more. The adhesive sheet according to claim 1, wherein the thickness Hs of the foam base material is 0.06mm~0.30mm. For the adhesive sheet of claim 1 or 2, the relationship between the pressing and bonding force S _1.0 [N] when the width is 1.0 mm and the pressing and bonding force S _0.3 [N] when the width is 0.3 mm satisfies the following formula: 0.3≦S _0.3 / S _1.0 . The adhesive sheet of claim 1 or 2, which is constituted in the form of a double-sided adhesive sheet having adhesive layers on both surfaces of the foam base material. The adhesive sheet according to claim 1 or 2, wherein the total thickness Ht of the above-mentioned adhesive sheet is 0.10 mm to 0.35 mm. The adhesive sheet according to claim 1 or 2, wherein the ratio of the thickness Hs [mm] of the above-mentioned foam base material to the total thickness Ht [mm] of the above-mentioned adhesive sheet is 30-70%. The adhesive sheet according to claim 1 or 2, wherein the above-mentioned foam base material is polyolefin-based Foam base. The adhesive sheet of claim 1 or 2 is used for bonding parts of portable electronic equipment.

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