JP6224169B2 - Fixing member and portable electronic device - Google Patents

Description

  The present invention relates to a fixing member for fixing a display unit or a display unit protection member of a portable electronic device to a housing.

  As a means for joining a display unit protection member (such as a cover glass) and a housing of a portable electronic device, a pressure-sensitive adhesive sheet with a base material (a pressure-sensitive adhesive sheet with a foam base material) using a foam having a cellular structure as a base material is used. It is known. Such a pressure-sensitive adhesive sheet with a foam base material can be advantageous in terms of waterproofness, dustproofness, and the like as compared with a pressure-sensitive adhesive sheet using a nonwoven fabric as a base material. In addition, it can be advantageous in terms of impact absorption and flexibility as compared with a pressure-sensitive adhesive sheet using a plastic film having no cell structure as a base material. Patent documents 1 and 2 are mentioned as technical literature about an adhesive sheet with a foam substrate.

International Publication No. 2013/154137 JP 2013-213104 A

  In recent years, a display unit or a display unit protection member and a housing can be joined in a narrower area from the viewpoint of increasing the screen size of an information display unit of a portable electronic device, improving design, and improving design flexibility. It has been requested. However, when the region that can be used for bonding becomes thin, it becomes difficult to realize a highly reliable bonding structure (for example, a bonding structure that can exhibit good durability against a drop impact). The present invention has been made in view of such circumstances, and provides a technique capable of bonding a display unit or a display unit protection member of a portable electronic device and a housing with high reliability even if a region usable for bonding is thin. The purpose is to do.

According to the present specification, there is provided a fixing member for fixing the display unit or the display unit protection member of the portable electronic device to the housing (in this specification, it may be referred to as “fixing member for display unit or the like”). Is done. The fixing member includes a foam base material and an adhesive layer disposed on at least one surface of the foam base material. The fixing member has a narrow portion having a width of less than 2.0 mm. The fixing member includes an average width W [mm] of the narrow width portion, a 100% modulus M [N / mm ² base material] of the fixing member, and a thickness Hs [mm] of the foam base material. The relationship is configured to satisfy the following formula: 0.4 / (M × Hs) ≦ W;

According to the fixing member configured in this manner, an appropriate average width W is ensured in the narrow width portion according to the characteristics of the fixing member, so that the display unit or the display unit protection member of the portable electronic device is mounted. Can be reliably fixed to the body. Note that M in the above formula represents the 100% modulus of the fixing member as N / mm ² substrate (here, “/ mm ² substrate” means “per 1 mm ² cross-sectional area of the foam substrate”). )), And M itself is a dimensionless number (the same applies to M in other formulas described herein). Hs in the above formula is a numerical part when the thickness of the foam substrate is expressed in mm, and Hs itself is a dimensionless number (other formulas described in this specification). Same for Hs in the middle). W in the above formula is a numerical part when the average width of the narrow portion in the fixing member disclosed herein is expressed in units of mm, and W itself is a dimensionless number (this specification) The same for W in the other formulas described in 1). However, in describing the preferable numerical ranges of M, D, and W in the present specification, for the sake of readability, these numerical values may be described with a unit (confirmed). The same applies to symbols).

  In the fixing member according to a preferred aspect, the area Ao of the window section defined by the inner edge of the fixing member is 10 times or more the area Af of the fixing member. As described above, in the fixing member having the large area Ao of the window portion relative to the area Af of the fixing member, the effect of applying the technique disclosed herein can be better exhibited.

  In the fixing member disclosed herein, the average width W [mm] of the narrow portion is preferably 1.0 times or more the thickness Hf [mm] of the fixing member in the narrow portion. The fixing member having such a configuration tends to exhibit better durability against impact. Moreover, it is advantageous from the viewpoint of the moldability (for example, the punchability from the original fabric) of the fixing member having the shape including the narrow width portion that W is 1.0 times or more of Hf.

In the fixing member disclosed herein, the relationship between the 100% modulus M [N / mm ² base material] of the fixing member and the thickness Hs [mm] of the foam base material constituting the fixing member is 0. It is preferable that 50 ≦ M × Hs is satisfied. The fixing member having such characteristics exhibits a strong resistance to elongation (tensile deformation). For this reason, even if the width is narrowed, it is preferable because damage to the joint due to impact (peeling of the fixing member, tearing of the foam base material, etc.) tends not to occur.

Further, according to this specification, the display unit or the display unit protection member, the housing to which the display unit or the display unit protection member is fixed, the display unit and the housing, or the display unit protection member, A portable electronic device including a fixing member interposed between the housing and the housing is provided. The fixing member includes a foam base material and an adhesive layer disposed on at least one surface of the foam base material. The fixing member has a narrow portion having a width of less than 2.0 mm, the width W [mm] of the narrow portion, the 100% modulus M [N / mm ² base material] of the fixing member, and the above The relationship with the thickness Hs [mm] of the foam substrate satisfies the following formula: 0.4 / (M × Hs) ≦ W; The display unit or the display unit protection member and the housing are liquid-tightly joined by a seal unit including the fixing member. The portable electronic device having such a configuration can be bonded with high reliability even if the bonding area between the display unit or the display unit protection member and the housing is thin. As the fixing member constituting the seal portion, any of the fixing members disclosed herein can be preferably used.

It is a top view which shows typically the fixing member which concerns on 1st Embodiment. It is the II-II sectional view taken on the line of FIG. It is sectional drawing which shows typically the principal part of the portable electronic device which concerns on one Embodiment. It is a top view which shows typically the fixing member which concerns on 2nd Embodiment. It is a principal part enlarged view which shows typically the state which sealed the opening part of the fixing member which concerns on 2nd Embodiment. It is a top view which shows typically the principal part of the fixing member which concerns on 3rd Embodiment. It is a top view which shows typically the principal part of the fixing member which concerns on the modification of 3rd Embodiment. It is sectional drawing which shows typically the fixing member with a peeling liner in which the fixing member which concerns on one Embodiment was protected by a pair of release liner. It is explanatory drawing which shows the sample for evaluation used for a drop durability test.

Hereinafter, preferred embodiments of the present invention will be described.
Here, matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings on the implementation of the invention described in the present specification and the common general technical knowledge at the time of filing. It can be understood by those skilled in the art based on this. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.
In the following drawings, members / parts having the same action may be described with the same reference numerals, and redundant descriptions may be omitted or simplified. In addition, the embodiment described in the drawings is schematically illustrated for clearly explaining the present invention, and does not accurately represent the size and scale of the fixing member or the like of the present invention that is actually provided as a product. .

In this specification, the “pressure-sensitive adhesive” refers to a material that exhibits a soft solid (viscoelastic body) state in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure as described above. . Here, the term pressure-sensitive adhesive, "CA Dahlquist," Adhesion: Fundamental and Practice ", McLaren & Sons, (1966) P. 143 ," as defined in the, in general, the complex tensile modulus E ^{* (1Hz} ) <10 ⁷ dyne / cm ² of material (typically a material having the above properties at 25 ° C.). The “base polymer” of the pressure-sensitive adhesive is the main component (that is, 50% by weight of the rubber-like polymer) of the rubber-like polymer (polymer exhibiting rubber elasticity in the temperature range near room temperature) contained in the pressure-sensitive adhesive. Component which occupies the above). In the present specification, the “main component” means a component occupying 50% by weight or more unless otherwise specified.

In this specification, the “portable electronic device” means a general electronic device that is carried and used, and is not particularly limited. Here, “portable” means that it is not enough to be able to carry it alone, but means that the individual (standard adult) has a level of portability that can be carried relatively easily. To do. Examples of the “portable electronic device” include a mobile phone, a smartphone, a tablet PC, a notebook PC, and the like. Such a portable electronic device may be a so-called wearable type terminal (for example, a wristband type such as a wristwatch type, a head mount type such as a glasses type). The portable electronic device includes, for example, a telephone, a clock, a camera, glasses, a personal computer or other information terminal, a health management tool such as a blood pressure monitor, a pulse meter, a pedometer, a music player, a video player, a recording, a recording, or the like. It may have the above functions.
The fixing member disclosed herein is used in such a portable electronic device for joining the display unit of the portable electronic device (which may be a display unit of a liquid crystal display device) or the display unit protection member and the housing. obtain. In particular, in a portable electronic device having a liquid crystal display device, it is suitable for applications in which a display unit or a display unit protection member and a housing are joined.

  Note that the display portion protection member is typically a member having a region that transmits light in the thickness direction (hereinafter also referred to as “light-transmitting member”), and may be referred to as a lens. . Here, in this specification, the “lens” is a concept including both a lens that exhibits light refraction and a lens that does not exhibit light refraction. That is, the “lens” in the present specification includes a light transmissive member having no refractive action, for example, a protective panel that simply protects a display unit of a portable electronic device. The protective panel can also be grasped as a display part protection member or a display part cover member having light transmittance. When the material of the protective panel is glass, the protective panel can also be referred to as “cover glass”. However, the material of the protective panel or the lens is not limited to glass, and may be any material that can exhibit light transmittance.

<Fixing member>
The fixing member disclosed herein includes a foam base material and an adhesive layer disposed on at least one surface of the foam base material. Therefore, the fixing member disclosed here is processed into a shape (outer shape) as a joining member that fixes the display unit or display unit protection member (hereinafter also referred to as “part to be fixed”) of the portable electronic device to the housing. It can also be grasped as an adhesive sheet.

  The fixing member disclosed here is typically in the form of a double-sided pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet with a foam base material) having pressure-sensitive adhesive layers on both sides of the foam base material, that is, in the form of a double-sided pressure-sensitive adhesive fixing member. Is preferably implemented. Such a double-sided adhesive fixing member is advantageous from the viewpoints of, for example, simplicity of the joining operation between the part to be fixed and the housing, improvement of joining quality, and quality stability. The fixing member disclosed herein has a pressure-sensitive adhesive layer only on one surface of the foam base material, and the form of a single-sided pressure-sensitive adhesive sheet in which only the one surface is an adhesive surface (adhesive surface) That is, you may be comprised as a single-sided adhesive fixing member. When fixing a component to be fixed to a housing using a single-sided adhesive fixing member, the surface on the side having no adhesive layer is a method other than adhesion (for example, a method using an adhesive, a method of heat-sealing, etc.) Can be fixed to the adherend.

  The fixing member disclosed herein may have a shape having a narrow width part with a width of less than 2.0 mm at least in part. That is, it may be a shape consisting only of a portion having a width of less than 2.0 mm (that is, a shape corresponding to the entire narrow portion), and a portion having a width of less than 2.0 mm and a portion having a width of 2.0 mm or more (non-thin). (Width portion). The shape of the narrow portion is typically linear. Here, the term “linear” is a concept including a linear shape, a curved shape, a bent line shape (for example, an L shape), a ring shape such as a frame shape or a circular shape, or a composite or intermediate shape thereof. . The width of the narrow portion may be constant or may vary depending on the location.

The fixing member disclosed herein has an average width W [[] of the narrow portion in relation to the 100% modulus M [N / mm ² substrate] of the fixing member and the thickness Hs [mm] of the foam substrate. mm] is 0.4 / (M × Hs) or more. By comprising in this way, a fixation object component and a housing | casing can be joined reliably. For example, a joint having good impact resistance can be formed even in the narrow portion. 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). According to the fixing member, better performance (for example, performance capable of forming a joint portion that is not easily impaired in waterproofness or dustproofness even when subjected to a drop impact) can be realized.

  Here, the average width W [mm] of the narrow portion of the fixed member is obtained by dividing the total area of the narrow portions included in the fixed member by the total length. When the width of the narrow portion is constant, the width of the narrow portion coincides with the average width. The average width W of the narrow portion in the fixing member disclosed herein is always less than 2.0 mm from the definition of the narrow portion. The fixing member disclosed herein is preferably in an embodiment in which the average width W of the narrow portion is less than 1.5 mm (more preferably 1.0 mm or less, typically less than 1.0 mm, for example, less than 0.8 mm). Can be implemented. In the fixing member of such an aspect, it is particularly meaningful to apply the technique disclosed herein to appropriately achieve both narrowing and bonding reliability (for example, durability against drop impact). The lower limit of the average width W of the narrow portion is not particularly limited, but usually 0.1 mm or more is appropriate, and 0.2 mm or more is preferable. The average width W of the narrow portion may be 0.3 mm or more.

The fixing member 100% modulus M [N / mm ² base material] is typically an adhesive sheet that is the original material of the fixing member (that is, before being processed into the shape of the fixing member by cutting or punching). It is measured using an adhesive sheet.
Specifically, a sample to be measured (adhesive sheet) is cut into a size having a width of 10 mm and a length of 40 mm to produce a test piece. At this time, the length direction of the test piece is made to coincide with the flow direction (MD) of the sample. This test piece is set vertically in a tensile tester with a test length (length between chucks) of 10 mm in a measurement environment at a temperature of 23 ° C. and 50% RH, and stretched in the vertical direction at a tensile speed of 50 mm / min. The value [N / mm ² substrate] obtained by converting the strength when the rate of change of the test length is 100% (when the test length is extended to 20 mm) per cross-sectional area of the foam substrate is the MD of the sample. 100% modulus (hereinafter also referred to as “MD modulus”).
In addition, the 100% modulus [N / mm ² bases] of the TD of the sample is the same as the measurement of the MD 100% modulus except that the length direction of the test piece is the width direction (TD) orthogonal to the MD of the sample. Material] (hereinafter also referred to as “TD modulus”).
By averaging the MD modulus and the TD modulus, the 100% modulus M [N / mm ² substrate] of the sample is obtained.
In addition, when the fixing member has a sufficient size, instead of producing a test piece from the pressure-sensitive adhesive sheet that is the original material of the fixing member, the fixing member is cut to a size of 10 mm in width and 40 mm in length for testing. Pieces may be made.

From the viewpoint of reducing the direction dependency of impact resistance, it is preferable that the MD modulus and the TD modulus are not extremely different. Although not particularly limited, the ratio of the MD modulus [N / mm ² substrate] to the TD modulus [N / mm ² substrate] can be set to, for example, 0.3 to 3, and usually 0.5. It is preferably in the range of ˜2, more preferably in the range of 0.6 to 1.5.

Although not particularly limited, the 100% modulus M of the fixing member disclosed herein can be, for example, 2.0 N / mm ² substrate or more (typically 3.0 N / mm ² substrate or more). . The 100% modulus M is usually preferably higher than 4.0 N / mm ² substrate, more preferably 4.5 N / mm ² substrate or more, and even more preferably 5.0 N / mm ² substrate or more (typical). thereof include 5.0 N / mm ² substrate than, for example, 5.5 N / mm ² group or material). When the 100% modulus M is high, good bonding reliability tends to be obtained even with a narrow width. Further, damage to the fixing member due to external force such as impact (for example, damage to the foam base material) tends to be better prevented. The fixing member according to a preferred embodiment may have a 100% modulus M of 6.0 N / mm ² or more. Further, from the viewpoint of flexibility, the 100% modulus M of the fixing member is usually suitably less 12.0 N / mm ² base material, preferably not more than 10.0 N / mm ² base material, more preferably 8 0.0 N / mm ² Base material or less. The 100% modulus M of the fixing member can be controlled by, for example, the degree of crosslinking and density (apparent density) of the foam base material, the size and shape of the bubbles, and the like.
The reason why the 100% modulus M of a fixing member having a foam base material and an adhesive layer is expressed as a numerical value per cross-sectional area of the foam base material (/ mm ² base material) is the fixing member disclosed herein. Since the contribution of the pressure-sensitive adhesive layer to the 100% stretch strength is usually very small, including the cross-sectional area of the pressure-sensitive adhesive layer when converting the stretch strength per cross-sectional area, the characteristics of the fixing member suitable for the purpose of the present application This is because it is difficult to grasp.

  The fixing member disclosed herein may be composed of a single member (typically one sheet, ie, a series of sheets), and two or more members (sub-fixing members, typically two). Or more than one sheet). From the viewpoint of shape accuracy and pasting workability, a fixing member composed of a single sheet (typically, a fixing member having an integrally formed foam base material) can be preferably employed. From the viewpoint of waterproofness and dustproofness, a seamless annular fixing member made of a single sheet is preferable. On the other hand, a fixing member having two or more sub-fixing members can be advantageous in terms of productivity and cost because a raw material (for example, a foam base material) can be efficiently used in manufacturing the fixing member.

  The number of narrow portions included in one fixing member (which may be a fixing member composed of two or more sub-fixing members; the same applies hereinafter) is not particularly limited. Here, the number of narrow portions refers to the number of continuous portions with a width of less than 2.0 mm. One fixing member has a plurality of narrow widths separated by a portion not corresponding to the narrow width portion (hereinafter also referred to as “non-thin width portion” or “land portion”) or separated by a physical gap. Parts may be included. Alternatively, the fixing member may include only a single (one continuous) narrow portion. As an example of such a fixing member, there is a fixing member that is entirely composed of a narrow portion.

  In the fixing member according to a preferred embodiment, the length of at least one narrow portion is 1 cm or more (typically 3 cm or more, more preferably 5 cm or more, for example, 7 cm or more, further 10 cm or more). The technique disclosed here is preferably applied to the fixing member having such a shape, and it is possible to suitably achieve both narrowing and bonding reliability. The upper limit of the length of the narrow portion is not particularly limited, but is usually 150 cm or less, and typically 100 cm or less (for example, 50 cm or less, and further 35 cm or less).

A window portion defined by the inner edge of the fixing member is typically formed at the central portion in the planar shape of the fixing member disclosed herein. Although it does not specifically limit, the area Ao of the said window part may be 3 times or more of the area Af of the said fixing member, for example. In the fixing member according to a preferred aspect, the area Ao of the window portion is not less than five times the area Af of the fixing member. That is, Ao / Af is 5 or more. In such a fixing member for a display unit or the like having a large window area relative to the area of the fixing member, the display unit or the display unit protection member having a relatively large area is fixed to the housing with a relatively small bonding area. Therefore, it is particularly meaningful to apply the technology disclosed herein. The technique disclosed herein can also be preferably implemented in an embodiment in which Ao / Af is 10 or more (more preferably 20 or more, for example, 30 or more, and even 50 or more). The upper limit of Ao / Af is not particularly limited, but is usually 100 or less. The area Af of the fixing member means the area of the substantial part in the planar shape of the fixing member, and does not include the area Ao of the window portion. The area Ao of the window part is not particularly limited. The technique disclosed here can be implemented, for example, in the form of a fixing member in which the area Ao of the window portion is 20 cm ² or more (typically 20 to 2000 cm ² , preferably 40 to 1000 cm ² ). In such an aspect having a wide window portion, it is significant to apply the technique disclosed herein.

  The thickness Hf [mm] of the fixing member disclosed here is not particularly limited. Usually, it is appropriate to be 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 0.12 mm or more). .15 mm or more. The thickness Hf of the fixing member is usually 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). It 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 thickness Hf of the fixing member to be equal to or less than the above-described upper limit value, it can be advantageous in terms of reducing the thickness of the product, reducing the size, reducing the weight, and saving resources. Further, by making the thickness Hf of the fixing member equal to or more than the lower limit value described above, excellent impact resistance, waterproofness, dustproofness, and the like can be exhibited. Here, Hf is a numerical part when the thickness of the fixing member is expressed in the unit of mm, and Hf itself is a dimensionless number (the same applies to Hf in other formulas described in this specification). ). In one embodiment, the thickness Hf of the fixing member may be in the range of about 0.07 mm to 0.80 mm (eg, about 0.08 mm to 0.50 mm), and is 0.09 mm to 0.40 mm (typically 0.10 mm to 0.35 mm, for example, about 0.12 mm to 0.30 mm, and further about 0.12 mm to 0.25 mm, or about 0.15 mm to 0.35 mm. There may be.

  In the fixing member disclosed herein, the average width W [mm] of the narrow portion is preferably 1.0 times or more the thickness Hf [mm]. That is, W / Hf is preferably 1.0 or more. The fixing member having such a configuration tends to exhibit better durability against impact (especially impact from the width direction of the narrow width portion), and the formability of the fixing member including the narrow width portion (for example, This is also advantageous from the viewpoint of the punchability from the pressure-sensitive adhesive sheet. W / Hf is more preferably 1.2 or more, and further preferably 1.5 or more (for example, 2.0 or more). The upper limit of W / Hf is not particularly limited. Usually, from the viewpoint of impact absorption and the like, W / Hf is suitably 20 or less, and preferably 15 or less (for example, 10 or less).

  The fixing member disclosed herein typically has an annular planar shape. Here, the term “annular” refers to an annular shape that is partly or entirely formed in a straight line, such as a shape along the outer periphery of a quadrangle (frame shape) or a shape along the outer periphery of a fan shape, in addition to a curved line. It is a concept that includes That is, the ring shape of the annular fixing member is not particularly limited, and may be, for example, a rectangle (frame shape), a circle, a polygon other than a rectangle (for example, a triangle), and other irregular shapes. Further, in the above-described annular concept, a single sheet or a plurality of sheets are overlapped with each other in addition to a completely closed annular shape (that is, a seamless annular shape). The shape that can form a closed ring, the end of one sheet or a plurality of sheets are arranged close to each other, and the close places are closed by sealing as necessary. Shapes that can form a ring may be included. In addition, proximity | contact is a concept including contact | abutting (state where distance is zero) here, for example, a mutual distance is 0-10 mm (typically 0.1-10 mm), Preferably it is 0-5 mm (Typically 0.1 to 5 mm), more preferably 0 to 2 mm (typically 0.1 to 2 mm), still more preferably 0 to 1 mm (typically 0.1 to 1 mm). Say. As a method for sealing the overlapped portion or the close (for example, abutted) portion, a method of sealing with a sealing material such as an adhesive, a method of welding ends (for example, heat welding), or the like is employed. be able to.

  Although not particularly limited, the fixing member disclosed herein has an annular planar shape, and the length of the narrow portion (that is, the portion having a width of less than 2.0 mm) of the length of the ring. It can be carried out in a form in which the proportion occupied by is 20% or more. According to the fixing member in which the proportion of the length of the narrow width portion is 30% or more (preferably 40% or more, more preferably 50% or more, still more preferably 60% or more, for example 70% or more), it is disclosed here. The applicability of the applied technology can be better demonstrated.

  One preferred form of the fixing member disclosed herein is a frame-like (rectangular ring) form. Such a shape is highly versatile and useful. As used herein, the frame-shaped fixing member has a rectangular outer peripheral shape (that is, a rectangular frame-shaped fixing member) and a rectangular outer peripheral shape (that is, a square-frame-shaped fixing member). And are included.

  In such a frame-shaped fixing member, the ratio between the vertical length and the horizontal length is not particularly limited, and is appropriately set according to the fixing target part fixed using the fixing member and the shape of the housing. Can do. Here, the “vertical length” and “lateral length” of the fixing member refer to the lengths of the long side and the short side of the smallest rectangle (which may be a square) circumscribing the fixing member. When the minimum rectangle is a square, the vertical length and the horizontal length of the fixing member coincide with each other. The ratio of the vertical length to the horizontal length of the fixing member can be, for example, 1: 1 to 1: 5 (typically 1: 1 to 1: 3). In the fixing member having such a length ratio, the value of Ao / Af described above tends to increase, and therefore, the significance of applying the technique disclosed herein is significant.

  Although it does not specifically limit, the fixing member disclosed here may be a frame shape whose length of the long side is 3 cm or more. The fixing member according to a preferred embodiment may have a frame shape in which the length of the long side is 5 cm or more (more preferably 7 cm or more, and further preferably 10 cm or more). In such a fixing member having a long side, the significance of applying the technique disclosed herein is significant. The upper limit of the length of the long side is not particularly limited. The length of the long side is usually 50 cm or less, typically 30 cm or less, for example 20 cm or less.

  The fixing member disclosed herein has a rectangular frame shape, and at least one (preferably both) of the long sides is 25% or more of the length of the long side as the narrow portion. The fixing member according to a preferred embodiment has a rectangular frame shape, and at least one (preferably both) of the long sides has a length of the narrow portion of the length of the long sides of 50% or more (more preferably). Occupy 60% or more, more preferably 70%, for example 80% or more). The upper limit of the proportion of the length of the narrow side in the length of the long side is not particularly limited, but is typically 98% or less, usually 95% or less, for example 90% or less.

  The fixing member according to a preferred embodiment has a rectangular frame shape, and a length of 3 cm or more (more preferably 5 cm or more, for example, 7 cm or more) of at least one (preferably both) long sides as the narrow portion. Is formed. The upper limit of the length of the narrow portion of the long side is not particularly limited, and is not more than the length of the long side (typically 99% or less of the length of the long side, for example, 95% or less). Good. In the fixing member having such a shape, the effect of applying the technique disclosed herein tends to be preferably exhibited.

  The fixing member according to another preferred embodiment is in the shape of a rectangular frame and has a length of 50% or more (more preferably 60% or more, for example, 70% or more) of the length of the narrow portion of the fixing member. Is arranged on the long side of the fixing member. In the fixing member having such a shape, the effect of applying the technique disclosed herein tends to be preferably exhibited. 85% or more of the narrow portion may be disposed on the long side, and the fixing member has a shape in which the narrow portion is disposed only on the long side (that is, a shape in which the entire short side is a non-narrow portion). There may be.

  The fixing member disclosed herein has a frame shape, and at least one of the four corners in the frame shape preferably has a round outer edge. The outer edges of at least two (more preferably three) corners are preferably rounded, and it is particularly preferred that all four corners are rounded. The fixing member having such a shape is suitable for an application in which a display unit or a display unit protection member in which corresponding corners are rounded is joined to a casing. Forming round corners in this way is preferable from the viewpoint of making it easier to hold a portable electronic device by hand, and making the corners less susceptible to damage due to impact or the like. In addition, forming the corners of the fixing member round may be advantageous from the viewpoint of moldability (for example, punchability) of the fixing member.

  The fixing member disclosed herein may include at least one non-narrow width portion (land portion) formed subsequent to the narrow width portion. According to such a configuration, it is possible to reduce the load applied to the narrow width portion by using the strength of the relatively wide land portion, so that it is possible to improve the joining reliability as the entire fixing member. The land portion can be disposed at one end or both ends of the narrow width portion. For example, a configuration in which land portions are disposed at both ends of the narrow width portion (that is, a configuration in which both ends of the narrow width portion are connected to the land portions) can be employed. As an example of a preferable shape from the viewpoint of a large screen, a shape in which a land portion is arranged at a corner portion or a bent portion in an annular fixing member (for example, a shape in which a land portion is arranged at an opposite corner portion of a frame-shaped fixing member) Is mentioned. As an example of a preferable shape from the viewpoint of improving the bonding reliability, a shape in which a land portion is arranged at the center of any side of the frame-shaped fixing member can be given.

  Hereinafter, some specific structural examples of the fixing member according to the technique disclosed herein will be described with reference to the drawings.

(First embodiment)
The fixing member 100 shown in FIG. 1 has a seamless frame shape (rectangular closed ring) formed from a single sheet. The central part of each side (long side and short side) of the fixing member 100 is a narrow width part 102a, 102b, 102c, 102d having a width of less than 2.0 mm. Land portions 104a, 104b, 104c, and 104d having a width of 2.0 mm or more are formed at the four corners of the frame shape. In other words, the fixing member 100 shown in FIG. 1 has four narrow portions 102a to 102d separated by land portions 104a to 104d arranged at four corners. The four corners are all formed so that the outer edges are rounded. Specifically, at the four corners, the outer edge of the fixing member 100 is configured by a smooth curve that is located on the inner side of the intersection of the long-side extension line and the short-side extension line and bulges outward. ing. The length L1 of the narrow portions 102a and 102b and the length L2 of the narrow portions 102c and 102d are both 3 cm or more. An average width W obtained by dividing the total length of the narrow portions 102a to 102d by the total area is less than 1.0 mm. A window portion 110 is formed inside the inner edge 100 a of the fixing member 100. The area Ao of the window part 110 is 10 times or more the area Af of the fixing member 100.

  As shown in FIG. 2, the fixing member 100 includes a foam base material 122 and a first pressure-sensitive adhesive layer 124 and a second pressure-sensitive adhesive layer 126 formed on the first surface and the second surface, respectively. The thickness Hs of the foam substrate 122 can be, for example, about 0.15 mm. The thickness Hf of the fixing member 100 including the first pressure-sensitive adhesive layer 124 and the second pressure-sensitive adhesive layer can be, for example, about 0.25 mm. The fixing member 100 is configured such that the average width W is 1.0 times or more the thickness Hf of the fixing member. A fixing member 100 is suitably formed by processing (punching, cutting, etc.) a continuous sheet-like foam substrate double-sided pressure-sensitive adhesive sheet (pressure-sensitive adhesive sheet) having such a cross-sectional structure into the planar shape shown in FIG. can do.

  For example, as shown in FIG. 3, the fixing member 100 includes a lens 10 (a light-transmitting display protection member such as a cover panel such as a cover glass) 10 of the portable electronic device 1 (for example, a mobile phone) and a housing 20. Used in between. More specifically, the surface (first adhesive surface) 124A of the first adhesive layer 124 of the fixing member 100 is pressure-bonded to the lens 10, and the surface (second adhesive surface) 126A of the second adhesive layer 126 is attached to the housing 20. By being pressure-bonded, the seal portion 30 is configured to join the lens 10 and the housing 20 of the portable electronic device 1 in a liquid-tight manner (typically in a water-tight manner, that is, not to allow water to pass through). In FIG. 3, reference numeral 22 denotes a liquid crystal module unit, reference numeral 24 denotes a spacer that separates the lens 10 and the liquid crystal module unit 22, and reference numeral 26 denotes a backlight unit. In addition, the portable electronic device 1 may include general portable electronic device components such as a circuit board and a battery unit (not shown) as necessary.

(Second Embodiment)
The fixing member 200 shown in FIG. 4 has a seamless shape formed from a single sheet, and is configured in a frame shape having an opening 206 at the end of one of the two short sides facing each other. ing. The fixing member 200 has land portions 204a and 204b having a width of 2.0 mm or more at the center of each short side, and the other portions are narrow portions 202a, 202b and 202c having a width of less than 2.0 mm. . A window portion 210 is formed inside the inner edge 200 a of the fixing member 200. The cross-sectional structure of the fixing member 200 may be the same as the cross-sectional structure of the fixing member 100 shown in FIG.

  As shown in FIG. 5, the fixing member 200 having such a shape can be formed into a closed ring shape by closing (sealing) the opening 206 with an appropriate sealing material 230. As a result, a sealing portion is formed which is composed of the fixing member 200 and the sealing material 230 and which joins the lens and the casing in a liquid-tight manner. The operation of closing the opening 206 with the sealing material 230 is typically performed after the fixing member 200 is attached to the lens and the housing, but only one surface of the fixing member 200 is attached to the adherend. It may be done later. As the sealing material 230, a known adhesive, pressure-sensitive adhesive, sealing material, or the like can be used. Alternatively, an adhesive sheet separate from the fixing member 200 may be used as the sealing material 230.

(Third embodiment)
The fixing member disclosed here may include a plurality of sub-fixing members. For example, in the case of a frame-shaped fixing member, it may be divided into two sub-fixing members each formed in a shape (L-shaped) consisting of two adjacent sides. Other forms of dividing the frame-shaped fixing member include a form in which each frame is divided into two at each central part of a pair of long sides or each central part of a pair of short sides, three adjacent sides and the remaining one side And a mode in which each side is divided into four so that each side becomes one sub-fixing member. A frame-shaped fixing member can be formed by disposing the end portions of the sub fixing members close to each other. The locations arranged close to each other may be sealed by the placement or welding of the sealing material as described above.

  FIG. 6 shows the ends of the sub-fixing members 300A and 300B in the frame-shaped fixing member 300 formed of two sub-fixing members 300A and 300B each formed in a shape (L-shaped) having two adjacent sides. It is a top view which shows the location arrange | positioned in contact with each other. In a preferred embodiment, the sub-fixing members 300A and 300B are arranged such that, for example, the end surface of the other sub-fixing member is in contact with the side surface of one of the sub-fixing members, thereby configuring the closed annular fixing member 300. can do. By pressing the fixing member 300 to the lens and the casing, a sealing portion is formed which is composed of the fixing member 300 (sub-fixing members 300A and 300B) and which joins the lens and the casing in a liquid-tight manner. In order to further improve the sealing performance, the joint 300e of the sub fixing members 300A and 300B may be welded (for example, heat welding), or a sealing material such as an adhesive may be disposed on the joint 300e.

As a modification of the form shown in FIG. 6, as shown in FIG. 7, one end of the sub-fixing member 300A is slightly extended in the direction along the adjacent side, and the extended portion is extended to the outer periphery of the end of the sub-fixing member 300B. You may arrange | position so that it may wrap around. By arranging the end portions of the sub-fixing members 300A and 300B so as to overlap in the radial direction in this way, better sealing performance can be realized. Also in this case, the joint 300e of the sub fixing members 300A and 300B may be sealed by welding or a sealing material.
<Foam substrate>
The foam base material constituting the fixing member disclosed herein is a base material having a portion having a bubble (bubble structure), and typically has at least one layered foam (foam layer). A substrate containing layers. The foam base material may be a base material composed of one or two or more foam layers. The foam base material may be a base material substantially constituted by only one or two or more foam layers, for example. Although it does not specifically limit, The foam base material which consists of a single layer (one layer) foam layer as a suitable example of the foam base material in the technique disclosed here is mentioned.

  The thickness Hs [mm] of the foam substrate is not particularly limited, and can be appropriately set according to the strength and flexibility of the fixing member, the purpose of use, and the like. From the viewpoint of thinning 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. In the technique disclosed herein, the thickness Hs of the foam base material is 0.20 mm or less (typically 0.18 mm or less, for example, 0, for example, from the viewpoint of workability when the fixing member is processed into a narrow width. .16 mm or less). In addition, from the viewpoint of impact resistance of the joint portion by the fixing member, the thickness Hs of the foam base material is suitably 0.05 mm or more, preferably 0.06 mm or more, more preferably 0.08 mm or more. preferable. The technique disclosed here is preferable in an embodiment in which the thickness Hs of the foam substrate is 0.10 mm or more (typically more than 0.10 mm, more preferably 0.12 mm or more, for example, 0.13 mm or more). Can be implemented. In addition, the impact resistance of a junction part can be evaluated by the drop durability test mentioned later, for example.

  In the fixing member disclosed herein, the ratio of the thickness Hs [mm] of the foam base material to the thickness Hf [mm] of the fixing member is not particularly limited. From the viewpoint of effectively balancing impact resistance and adhesive performance, it is usually appropriate to set Hs / Hf to about 20 to 80%, about 30 to 70% (for example, about 40 to 60%). It is preferable that

Although not particularly limited, the fixing member disclosed herein includes a 100% modulus M [N / mm ² base material] of the fixing member and a thickness Hs [of the foam base material constituting the fixing member]. mm] preferably satisfies 0.50 ≦ M × Hs. Such a fixing member tends to exhibit good impact resistance (for example, durability against a drop impact) even in the narrow portion. Although it is not necessary to clarify the reason, for example, it is considered as follows. That is, a fixing member having a large value of M × Hs generally exhibits high resistance to tensile deformation. Here, when the fixing member is deformed by a tensile stress, generally, the contact area (adhesion area) between the adhesive layer of the fixing member and the adherend decreases. Since the adhesive area is small from the beginning in the narrow width part, the influence of the decrease in the adhesive area due to tensile deformation on the adhesive performance tends to be particularly large. The fixing member having M × Hs of 0.5 or more is unlikely to cause a decrease in the adhesion area due to the tensile stress, which is considered to contribute to an improvement in impact resistance in the narrow portion.

  Although not particularly limited, from the viewpoint of further improving the impact resistance of the narrow portion, the value of M × Hs is preferably 0.60 or more, more preferably 0.70 or more, and 0.80. More preferably (for example, 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, usually 10.0 or less is appropriate, 3.0 or less is preferable, and 2.0 or less (for example, 1.5 or less). More preferred.

The density D of the foam base material (referring to the apparent density; hereinafter the same unless otherwise specified) is not particularly limited, and 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, and preferably 0.7 g / cm ³ or less (for example, 0.6 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, and 0.2 g / cm ³ or more (for example, 0.2 g / cm ³ or more). 3 g / cm ³ or more) is more preferable. In addition, the density D (apparent density) of a foam base material can be measured based on JISK6767.

In the fixing member disclosed herein, the relationship between the 100% modulus M [N / mm ² base material] and the density D [g / cm ³ ] of the foam base material satisfies 9.0 ≦ (M / D). It is preferable. According to such a fixing member, there is a tendency that better impact resistance (for example, durability of the joint portion against drop impact) is exhibited in the narrow width portion. This is because a fixing member having a large M / D tends to exhibit a high resistance to the density of the foam base material with respect to tensile deformation, and therefore, the adhesive area is less likely to be reduced at the time of impact even in a narrow portion. Conceivable. In a preferred embodiment, the value of M / D may be 9.5 or more, may be more than 10.0, or may be more than 10.5 (for example, 11.0 or more). The upper limit of M / D is not particularly limited, but is usually 50 or less, preferably 40 or less, and more preferably 30 or less (for example, 25 or less) from the viewpoint of ease of production or availability of the material. In a preferred embodiment, M / D may be 20 or less, or 15 or less.

  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 even more preferably 150 μm or less, from the viewpoints of waterproof reliability and dustproof reliability in the narrow width portion. From the viewpoint of exhibiting higher performance waterproofness and dustproofness, the average cell diameter of the foam base material is preferably 120 μm or less, and is typically 100 μm or less (typically 90 μm or less, such as 80 μm or less, 70 μm or less) is more preferable. In the technology disclosed herein, by reducing the average cell diameter of the foam base material, waterproofness and dustproofness tend to be easily maintained even when subjected to impact (for example, drop impact) in a narrow width. In addition, it is preferable to reduce the average bubble diameter because it can be effective as one method for increasing the M / D value described above. The lower limit of the average cell diameter is not particularly limited, but from the viewpoint of impact resistance, it is usually suitably 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and further preferably 40 μm or more (for example, 50 μm or more). In one embodiment, the average cell diameter may be 55 μm or more, and may be 60 μm or more. In addition, the average bubble diameter here refers to the average bubble diameter in terms of a true sphere obtained by observing the cross section of the foam substrate with an electron microscope.

It is preferable that the bubbles contained in the foam base material 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 flow direction (hereinafter also referred to as “MD”) and the average cell size in the width direction (hereinafter also referred to as “CD”) of the foam substrate are not too different. The degree of separation of the bubble shape from the circular shape is the ratio of the average bubble diameter (MD average bubble diameter) for MD to the average bubble diameter (CD average bubble diameter) for CD of the foam substrate, that is, The “aspect ratio (MD / CD)” expressed by the equation can be grasped as an index. If this aspect ratio (MD / CD) is closer to 1, it can be said that the shape of the bubbles contained in the foam substrate in plan view is closer to a circle.
Aspect ratio (MD / CD) = MD average bubble diameter / CD average bubble diameter

  In one embodiment of the technology disclosed herein, the aspect ratio (MD / CD) of the bubbles contained in the foam substrate is preferably 0.7 or more, more preferably 0.75 or more, and even more preferably 0.8. For example, it may be 0.85 or more. In one embodiment, the aspect ratio may be 0.9 or greater, and may be 0.95 or greater (eg, approximately 1.0 or greater). The aspect ratio (MD / CD) is preferably 1.3 or less, more preferably 1.25 or less, still more preferably 1.2 or less, and may be 1.15 or less, for example. When the aspect ratio (MD / CD) is not less than 1, the handleability of the pressure-sensitive adhesive sheet and the fixing member using the foam base material can be improved. Moreover, when the aspect ratio (MD / CD) is not too larger than 1, waterproofness (for example, waterproof after dropping described later) and dustproofness of the fixing member using the foam base material can be improved. As will be described later, the aspect ratio (MD / CD) is particularly close to 1 in the foam base material constituting the fixing member having a narrow width portion (particularly, the shape of an annular member having a narrow width portion). Meaningful.

  Here, MD of a foam base material refers to the extrusion direction in the manufacturing process of this foam base material. Although it does not specifically limit, MD in long foam base materials, such as tape shape, corresponds normally to the elongate direction. Moreover, CD of a foam base material points out the direction orthogonal to 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 substrate is a direction orthogonal to both the MD and the CD.

The MD average cell diameter of the foam substrate is measured as follows.
That is, the foam base material is cut along a plane parallel to MD and VD (that is, a plane in which the direction of the perpendicular coincides with CD) at a substantially central portion of the CD, and the central portion of the cut surface. Are photographed with a scanning electron microscope (SEM). The photographed image is printed on A4 size paper, and a straight line with a length of 60 mm parallel to the MD is drawn on the image. At this time, the magnification of the SEM is adjusted so that about 10 to 20 bubbles exist on a straight line of 60 mm. The number of bubbles present on the straight line is visually counted, and the MD average bubble diameter is calculated by the following formula.
MD average bubble diameter (μm) = 60 (mm) × 10 ³ / (number of bubbles (pieces) × magnification)

The CD average cell diameter of the foam substrate is measured as follows.
That is, the foam base material is cut along a plane parallel to the CD and VD (that is, a plane in which the direction of the perpendicular coincides with MD), and the central portion of the cut surface is photographed with an SEM. The photographed image is printed on A4 size paper, and a straight line with a length of 60 mm parallel to the CD is drawn on the image. At this time, the magnification of the SEM is adjusted so that about 10 to 20 bubbles exist on a straight line of 60 mm. The number of bubbles present on the straight line is visually counted, and the CD average bubble diameter is calculated by the following formula.
CD average bubble diameter (μm) = 60 (mm) × 10 ³ / (number of bubbles (pieces) × magnification)

  When drawing a straight line, the straight line should be penetrated as much as possible without making point contact with the bubbles. When some of the bubbles are in point contact with a straight line, the bubbles are counted as one. Further, when the both ends of the straight line are located in the bubble without penetrating the bubble, the number of bubbles is counted as 0.5.

  The average cell diameter in each direction of the foam base material is controlled, for example, by adjusting the composition of the foam base material (amount of foaming agent used) and manufacturing conditions (conditions in the foaming process, stretching process, etc.). be able to.

The fixing member according to a preferred embodiment includes a 100% modulus M [N / mm ² base material], a density D [g / cm ³ ] of the foam base material, and an average cell diameter P [μm] of the foam base material. Satisfies the following formula: 70 ≦ (M / D) / (P × 10 ⁻³ ); A fixing member satisfying the above formula can be excellent in performance to maintain waterproofness and dustproofness even when subjected to impact in a narrow width, such as waterproofing after dropping described later. 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, further 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, and 500 or less is appropriate from the viewpoint of availability of materials or ease of manufacture. Typically, it is 300 or less, and may be 250 or less. Note that P in the above formula is a numerical part when the above-described average bubble diameter in terms of sphere is expressed in units of [μm], and P itself is a dimensionless number (described in this specification). The same applies to P in the other formulas).

As a foam base material in the technology disclosed herein, the relationship between 10% compressive strength C ₁₀ [kPa] and 30% compressive strength C ₃₀ [kPa] is represented by the following formula: (C ₃₀ / C ₁₀ ) ≦ 5. Those satisfying 0; can be preferably employed. Here, the 10% compressive strength of the foam base material is obtained by sandwiching a measurement sample in which the foam base material is cut into a 30 mm square shape and having a thickness of about 2 mm between a pair of flat plates. The load when compressed by a thickness corresponding to 10% of the thickness (load at a compression rate of 10%). That is, it means a load when the measurement sample is compressed to a thickness corresponding to 90% of the initial thickness. Similarly, with respect to 30% compressive strength C ₃₀ [kPa] and 25% compressive strength C ₂₅ [kPa], which will be described later, the measurement sample is compressed by a thickness corresponding to 30% or 25% of the original thickness. Refers to the load.
The compressive strength at an arbitrary compression rate of the foam base material is measured in accordance with JIS K 6767. As a specific measurement procedure, the measurement sample is set at the center of the pair of flat plates, and the interval between the flat plates is narrowed to continuously compress to an arbitrary compression rate, and then the flat plate is stopped for 10 seconds. Measure the load after elapse. The compressive strength of the foam substrate can be controlled by, for example, the degree of crosslinking and density of the material constituting the foam substrate, the size and shape of the bubbles, and the like.

A small compressive strength ratio (C ₃₀ / C ₁₀ ) means that the influence of the degree of compression on the compressive strength is small. For example, when the joint surface disclosed by the fixing member has irregularities such as steps or scratches, when the width of the fixing member is partially different, or part of the joint portion by the fixing member is more than the other part. For example, when a large stress is applied, a part of the fixing member may be compressed more than the other part. If the difference in the compression strength due to the difference in the degree of compression is too large, the strain concentrates on the part where the degree of compression changes, and this part may become the starting point of peeling of the fixing member or damage to the foam substrate. . Since the fixing member using the foam base material having a small (C ₃₀ / C ₁₀ ) has a small difference in compressive strength due to the difference in the degree of compression, the peeling and the foam base material are less likely to occur. . This can be 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 even more preferably 4.0 or less. (C ₃₀ / C ₁₀ ) may be 3.5 or less. The lower limit of (C ₃₀ / C ₁₀ ) is not particularly limited, but is suitably 2.5 or more, for example, and may be 3.0 or more.

The 25% compressive strength C ₂₅ of the foam substrate is not particularly limited, and may be, for example, 20 kPa or more (typically 40 kPa or more). C ₂₅ is usually suitably 250 kPa or more, preferably 300 kPa or more (for example, 400 kPa or more). Even if the fixing member having such a foam base material is narrow, it can exhibit good durability against impacts such as dropping. For example, tearing of the fixing member due to impact can be better prevented. The upper limit of C ₂₅ is not particularly limited, but is usually 1300 kPa or less (eg, 1200 kPa or less). In one aspect, C ₂₅ may be 1000 kPa or less, may be 800 kPa, and may be 600 kPa or less (for example, 500 kPa or less). The relationship between C ₂₅ [kPa] and the apparent density D [g / cm ³ ] is the following formula: 150 ≦ C ₂₅ × D ≦ 400 (for example, 200 ≦ C ₂₅ × D ≦ 350, preferably 240 ≦ C ₂₅ × D ≦ 300); better results can be achieved with a fixing member comprising a foam substrate.

In another preferable embodiment, C ₂₅ of the foam substrate can be a 20KPa～200kPa (typically 30kPa~150kPa, for example 40kPa~120kPa). Since the fixing member provided with such a foam base material has a low compressive strength relative to the density, it can be excellent in cushioning properties even in the narrow width portion. For example, when the foam base material absorbs the drop impact, peeling of the fixing member can be better prevented. The relationship between C ₂₅ [kPa] and the apparent density D [g / cm ³ ] is the following formula: 100 ≦ C ₂₅ / D ≦ 400 (for example, 150 ≦ C ₂₅ / D ≦ 350, preferably 200 ≦ C ₂₅ / D ≦ 300); better results can be achieved with a fixing member comprising a foam substrate.

In the fixing member according to a preferred embodiment, the relationship between the 100% modulus M [N / mm ² substrate] and the C ₂₅ [kPa] of the foam substrate is expressed by the following formula: 35 ≦ M / (C ₂₅ × 10 ^-3 ); Since such a fixing member exhibits a good cushioning property against compressive stress and a strong resistance against elongation, it can have good impact resistance even in a narrow portion. According to the fixing member having M / (C ₂₅ × 10 ⁻³ ) of 40 or more (more preferably 45 or more, further preferably 50 or more, for example 55 or more), a better result can be realized. The upper limit of M / (C ₂₅ × 10 ⁻³ ) is not particularly limited, and may be, for example, 300 or less (preferably 200 or less, more preferably 150 or less, typically 100 or less).

A fixing member according to another preferred embodiment includes a 100% modulus M [N / mm ² base material], a foam base material C ₂₅ [kPa], and a foam base material density D [g / cm ³ ]. The relationship satisfies the following formula: 10 ≦ (M × D) / (C ₂₅ × 10 ⁻³ ). Such a fixing member has a high 100% modulus M for compressive strength and density, and therefore tends to exhibit good cushioning properties against compressive stress and strong resistance to elongation. Therefore, even in the narrow portion, the impact resistance can be improved. According to the fixing member in which (M × D) / (C ₂₅ × 10 ⁻³ ) is 15 or more (for example, 18 or more), better results can be realized. The upper limit of (M × D) / (C ₂₅ × 10 ⁻³ ) is not particularly limited, and may be, for example, 50 or less (preferably 40 or less, typically 30 or less).

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

  The tensile strength (tensile strength) of the foam substrate is not particularly limited. For example, a foam base material having a tensile strength in the flow direction (MD) of 5 MPa to 35 MPa (preferably 10 MPa to 30 MPa) can be suitably used. Further, a foam base material having a tensile strength in the width direction (TD) of 1 MPa to 25 MPa (more preferably 5 MPa to 20 MPa) is preferable. The tensile strength of the foam base material is 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 (foaming ratio), and the like.

  The material of the foam base material is not particularly limited. Usually, a foam base material including a foam layer formed of a foam of plastic material (plastic foam) is preferable. The plastic material for forming the plastic foam (meaning including rubber material) is not particularly limited, and can be appropriately selected from known plastic materials. One plastic material can be used alone, or two or more plastic materials can be used in appropriate combination.

  Specific examples of plastic foams include polyolefin resin foams such as polyethylene foams and polypropylene foams; polyesters such as polyethylene terephthalate foams, polyethylene naphthalate foams, and polybutylene terephthalate foams. Foam made of resin; Foam made of polyvinyl chloride resin such as foam made of polyvinyl chloride; Foam made of vinyl acetate resin; Foam made of polyphenylene sulfide resin; Foam made of aliphatic polyamide (nylon) resin, wholly aromatic Amide resin foams such as aromatic polyamide (aramid) resin foams; Polyimide resin foams; Polyetheretherketone (PEEK) foams; Polystyrene ether foams such as polystyrene foams; Polyurethanes Examples include urethane resin foams such as resin foams; . Moreover, you may use rubber-type resin-made foams, such as a polychloroprene rubber foam, as a plastic foam.

  Examples of preferred foams include polyolefin resin foams (hereinafter also referred to as “polyolefin foams”). As the plastic material (that is, polyolefin resin) constituting the polyolefin foam, various known or commonly used polyolefin resins can be used without any particular limitation. Examples thereof include 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, and the like. Examples of LLDPE include Ziegler-Natta catalyst linear low density polyethylene, metallocene catalyst linear low density polyethylene, and the like. Such polyolefin resin can be used individually by 1 type or in combination of 2 or more types as appropriate.

  As a suitable example of the foam base material in the technology disclosed herein, a polyethylene foam base material substantially composed of a polyethylene resin foam from the viewpoint of impact resistance, water resistance, dust resistance, and the like And a polyolefin-based foam substrate such as a polypropylene-based foam substrate substantially composed of a polypropylene-based resin foam. Here, the polyethylene-based resin refers to a resin having ethylene as a main monomer (that is, a main component in the monomer). In addition to HDPE, LDPE, LLDPE, etc., an ethylene copolymer having a copolymerization ratio of ethylene exceeding 50% by weight. A propylene copolymer, an ethylene-vinyl acetate copolymer, etc. may be included. Similarly, a polypropylene resin refers to a resin having propylene as a main monomer. As the foam substrate in the technology disclosed herein, a polyethylene-based foam substrate can be preferably employed.

The manufacturing method of the said plastic foam (typically polyolefin-type foam) is not specifically limited, Well-known various methods can be employ | adopted suitably. For example, it can be produced by a method including a molding step, a crosslinking step and a foaming step of the plastic material or the plastic foam. Moreover, an extending | stretching process may be included as needed.
Examples of the method of crosslinking the plastic foam include a chemical crosslinking method using an organic peroxide or the like, or an ionizing radiation crosslinking method of irradiating ionizing radiation. These methods can be used in combination. Examples of the ionizing radiation include electron beams, α rays, β rays, and γ rays. The dose of ionizing radiation is not particularly limited, and can be set to an appropriate irradiation dose in consideration of the target physical properties (for example, the degree of crosslinking) of the foam substrate.

  For the foam base material, if necessary, a filler (inorganic filler, organic filler, etc.), an anti-aging agent, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a plasticizer, a flame retardant, Various additives such as a surfactant may be blended.

  The foam base material in the technology disclosed herein is colored in order to develop desired design properties and optical characteristics (for example, light shielding property, light reflectivity, etc.) in a fixing member including the foam base material. May be. For this coloring, a known organic or inorganic coloring agent can be used singly or in appropriate combination of two or more.

  For example, when the fixing member disclosed herein is used for light shielding, the visible light transmittance of the foam base material is not particularly limited, but is 0% to 15%, similarly to the visible light transmittance of the fixing member described later. And more preferably 0% to 10%. Moreover, when using the fixing member disclosed here for light reflection applications, the visible light reflectance of the foam base material is preferably 20% to 100%, more preferably the same as the visible light reflectance of the fixing member. 25% to 100%.

  The visible light transmittance of the foam base material is measured using one of the foam base materials at a wavelength of 550 nm using a spectrophotometer (for example, spectrophotometer manufactured by Hitachi High-Technologies Corporation, model “U-4100”). It can be determined by measuring the intensity of light irradiated from the surface side and transmitted to the other surface side. The visible light reflectance of the foam base material can be determined by measuring the intensity of light reflected and irradiated on one surface of the foam base material at a wavelength of 550 nm using the spectrophotometer. The visible light transmittance and the visible light reflectance of the fixing member can also be obtained by the same method.

  When the fixing member disclosed here is used for light shielding, the foam base material is preferably colored black. As black, L * (lightness) defined by the L * a * b * color system is preferably 35 or less (for example, 0 to 35), more preferably 30 or less (for example, 0 to 30). . Note that a * and b * defined in the L * a * b * color system can be appropriately selected according to the value of L *. Although it does not specifically limit as a * and b *, It is preferable that both are the range of -10-10 (more preferably -5-5, still more preferably -2.5-2.5). For example, it is preferable that both a * and b * are 0 or substantially 0.

  In this specification, L *, a *, and b * defined in the L * a * b * color system are color difference meters (for example, color difference meters manufactured by Minolta, trade name “CR-200”). It is calculated | required by measuring using "). The L * a * b * color system is a color space recommended by the International Commission on Illumination (CIE) in 1976, and is a color space called the CIE 1976 (L * a * b *) color system. It means that. The L * a * b * color system is defined in JIS Z 8729 in the Japanese Industrial Standard.

  Examples of the black colorant used for coloring the foam base material black include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline. Black, perylene black, titanium black, cyanine black, activated carbon, ferrite (nonmagnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxide black pigment, anthraquinone organic black A pigment | dye etc. can be used. Carbon black is exemplified as a preferable black colorant from the viewpoint of cost and availability. The amount of the black colorant used is not particularly limited, and can be an amount adjusted appropriately so as to impart desired optical characteristics.

  When the fixing member disclosed here is used for light reflection, the foam base material is preferably colored white. As white, L * (brightness) defined by the L * a * b * color system is preferably 87 or more (for example, 87 to 100), more preferably 90 or more (for example, 90 to 100). . Each of a * and b * defined by the L * a * b * color system can be appropriately selected according to the value of L *. For example, both a * and b * are preferably in the range of −10 to 10 (more preferably −5 to 5, more preferably −2.5 to 2.5). For example, it is preferable that both a * and b * are 0 or substantially 0.

  Examples of the white colorant used for coloring the foam base material white include titanium oxide (titanium dioxide such as rutile titanium dioxide and anatase 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, zinc hydroxide, 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 -Inorganic white colorants such as bon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, hydrous halloysite, acrylic resin particles, polystyrene resin particles, polyurethane resin particles, amide resin particles, polycarbonate resin particles, silicone Organic white colorants such as resin-based resin particles, urea-formalin-based resin particles, and melamine-based resin particles. The amount of the white colorant used is not particularly limited, and can be an amount appropriately adjusted so that desired optical properties can be imparted.

  The surface of the foam substrate may be subjected to an appropriate surface treatment as necessary. This surface treatment can be, for example, a chemical or physical treatment for enhancing adhesion to an adjacent material (for example, an adhesive layer). Examples of such surface treatment include corona discharge treatment, chromic acid treatment, ozone exposure, flame exposure, ultraviolet irradiation treatment, plasma treatment, and application of a primer (primer).

<Adhesive>
The fixing member disclosed here has an adhesive layer on at least one surface of the foam substrate. The kind of adhesive which comprises an adhesive layer is not specifically limited. The pressure-sensitive adhesive is, for example, one or more selected from various polymers (adhesive polymers) such as acrylic, polyester, urethane, polyether, rubber, silicone, polyamide, and fluorine. Can be a pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing as a base polymer (a main component of the polymer component, that is, a component occupying 50% by weight or more).

  As a method for forming the pressure-sensitive adhesive layer on the foam substrate, various conventionally known methods can be applied. For example, a method of directly applying a pressure-sensitive adhesive composition to a foam substrate (direct method), a pressure-sensitive adhesive composition is applied on a suitable release surface, and a pressure-sensitive adhesive layer is formed on the release surface. Examples thereof include a method (transfer method) in which a layer is bonded to a foam substrate and transferred. You may use combining these methods. Moreover, you may employ | adopt a different method with a 1st adhesive layer and a 2nd adhesive layer. The pressure-sensitive adhesive composition can be applied using a known or conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. In the case of using a pressure-sensitive adhesive composition containing a solvent, it is preferable to dry the pressure-sensitive adhesive composition under heating from the viewpoints of promoting a crosslinking reaction and improving production efficiency.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited, and can be set in consideration of the balance with the thickness Hf of the fixing member and the thickness Hs of the foam base material. For example, the thickness of the pressure-sensitive adhesive layer can be about 5 μm to 150 μm. The thickness of the pressure-sensitive adhesive layer is usually 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) from the viewpoint of balancing the thinning of the fixing member and the adhesive performance at a high level. ), And 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 pressure-sensitive adhesive layer can be, for example, about 10 μm to 100 μm (preferably about 15 μm to 90 μm, more preferably about 20 μm to 80 μm). From the viewpoint of reducing the thickness of the fixing member, the thickness of the pressure-sensitive adhesive layer may be about 50 μm or less, and further about 40 μm or less (for example, about 35 μm or less).

  The fixing member disclosed herein is a layer other than the foam base material and the pressure-sensitive adhesive layer (intermediate layer, undercoat layer, etc .; hereinafter also referred to as “other layer”) within a range that does not significantly impair the effects of the present invention. Further, it may be included. For example, the other layer may be provided between the foam substrate and the surface of the pressure-sensitive adhesive layer (pressure-sensitive adhesive surface).

  The technology disclosed herein can be preferably implemented in a form in which the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive. Here, the “acrylic adhesive” refers to an adhesive having an acrylic polymer as a base polymer. “Acrylic polymer” means a monomer having at least one (meth) acryloyl group in one molecule (hereinafter sometimes referred to as “acrylic monomer”) as a main constituent monomer component (main monomer component). Component, that is, a polymer that constitutes 50% by weight or more of the total amount of monomers constituting the acrylic polymer). In the present specification, the term “(meth) acryloyl group” means an acryloyl group and a methacryloyl group comprehensively. Similarly, “(meth) acrylate” is a generic term for acrylate and methacrylate.

The acrylic polymer is typically a polymer containing alkyl (meth) acrylate as a main constituent monomer component. As said alkyl (meth) acrylate, 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. Since an adhesive having excellent adhesive properties is easily obtained, R ² is an alkyl group having 2 to 14 carbon atoms (hereinafter, such a range of carbon atoms may be represented as C _2-14 ). Certain alkyl (meth) acrylates are preferred. Specific examples of the C _2-14 alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group and isoamyl group. , Neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, n-decyl group, isodecyl group, n-undecyl group, n- A dodecyl group, n-tridecyl group, n-tetradecyl group, etc. are mentioned.

In a preferred embodiment, the total amount of monomers used for the synthesis of the acrylic polymer is about 50% by weight (typically 50 to 99.9% by weight), more preferably 70% by weight (typically 70 to 99.9% by weight), for example, about 85% by weight or more (typically 85 to 99.9% by weight), R ² in the above formula (1) is a C _2-14 alkyl (meth) acrylate ( More preferably, it is occupied by one or more selected from C _4-10 alkyl (meth) acrylates, particularly preferably one or both of n-butyl acrylate and 2-ethylhexyl acrylate. An acrylic polymer obtained from such a monomer composition is preferable because a pressure-sensitive adhesive exhibiting good adhesive properties is easily formed.

  Although it does not specifically limit, As an acrylic polymer, what copolymerized the acrylic monomer (hydroxyl group containing acrylic monomer) which has a hydroxyl group (-OH) can be used preferably. An acrylic polymer having such a copolymer composition is preferable because an adhesive having an excellent balance between adhesive force and cohesive force and excellent removability can be easily obtained.

  A hydroxyl-containing acrylic monomer can be used individually by 1 type or in combination of 2 or more types. Specific examples of the hydroxyl group-containing acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxy Butyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meta ) Hydroxyalkyl (meth) acrylates such as acrylate. Furthermore, (4-hydroxymethylcyclohexyl) methyl acrylate, polypropylene glycol mono (meth) acrylate, N-hydroxyethyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide and the like are exemplified. Of these, hydroxyalkyl (meth) acrylate is preferable, and hydroxyalkyl (meth) acrylate in which the alkyl group in the hydroxyalkyl group is a straight chain having 2 to 4 carbon atoms is particularly preferable.

  The hydroxyl group-containing acrylic monomer is preferably used in the range of about 0.001 to 10% by weight in the total amount of monomers used for the synthesis of the acrylic polymer. As a result, a fixing member that balances the adhesive force and the cohesive force at a higher level can be realized. By setting the amount of the hydroxyl group-containing acrylic monomer to be about 0.01 to 5% by weight (for example, 0.05 to 2% by weight), 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.

  Monomers (other monomers) other than those described above may be copolymerized in the acrylic polymer in the technology disclosed herein within a range that does not significantly impair the effects of the present invention. Such a monomer can be used, for example, for the purpose of adjusting the glass transition temperature of the acrylic polymer, adjusting the adhesive performance (for example, peelability), and the like. Examples of monomers that can improve the cohesive strength and heat resistance of the pressure-sensitive adhesive include sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl esters, and aromatic vinyl compounds. In addition, as a monomer that can introduce a functional group that can serve as a crosslinking base point into an acrylic polymer or contribute to an improvement in adhesion, a carboxyl group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, Examples include imide group-containing monomers, epoxy group-containing monomers, (meth) acryloylmorpholine, and vinyl ethers. For example, an acrylic polymer obtained by copolymerizing a carboxyl group-containing monomer as the other monomer is preferable.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxy. Examples thereof include naphthalene sulfonic acid and sodium vinyl sulfonate.
Examples of the phosphoric acid group-containing monomer include 2-hydroxyethyl acryloyl phosphate.
Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.
Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl laurate, and the like.
Examples of the aromatic vinyl compound include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrene.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.
Examples of the acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, and acid anhydride bodies of the above carboxyl group-containing monomers.
Examples of amide group-containing monomers include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, Examples thereof include N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, diacetone acrylamide and the like.
Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like.
Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.
Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.
Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether and the like.

  Such “other monomers” may be used singly or in combination of two or more, but the total amount of the other monomers is the total amount of monomers used for the synthesis of the acrylic polymer. Of these, about 40% by weight or less (typically 0.001 to 40% by weight) is preferable, and about 30% by weight or less (typically 0.01 to 30% by weight, for example, 0.1 to 10%). % By weight) is more preferable. When a carboxyl group-containing monomer is used as the other monomer, the content thereof can be, for example, 0.1 to 10% by weight of the total monomer amount, and is usually 0.2 to 8% by weight, for example, 0.5%. It is appropriate to set it to ˜5% by weight. Moreover, when using vinyl ester (for example, vinyl acetate) as said other monomer, the content can be made into 0.1-20 weight% among the said monomer total amount, for example, and 0.5-10 weight normally. % Is appropriate.

  The copolymer composition of the acrylic polymer is suitably designed so that the glass transition temperature (Tg) of the acrylic polymer is −15 ° C. or lower (typically −70 ° C. to −15 ° C.). Yes, preferably −25 ° C. or lower (eg −60 ° C. to −25 ° C.), more preferably −40 ° C. or lower (eg −60 ° C. to −40 ° C.). Setting the Tg of the acrylic polymer to be equal to or lower than the above-described upper limit is preferable from the viewpoint of impact resistance of the fixing member. The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the type and amount ratio of monomers used for the synthesis of the polymer).

Here, Tg of a polymer in this specification means Tg calculated | required by the formula of Fox based on the copolymerization composition of this polymer. The formula of Fox is a relational expression between Tg of a copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1 / Tg = Σ (Wi / Tgi)
In the above Fox equation, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer.

As the glass transition temperature of the homopolymer used for the calculation of Tg, the values described in known materials are used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomer.
2-Ethylhexyl acrylate -70 ° C
n-Butyl acrylate -55 ° C
Ethyl acrylate -22 ° C
Methyl acrylate 8 ℃
Methyl methacrylate 105 ° C
2-hydroxyethyl acrylate -15 ° C
Vinyl acetate 32 ° C
Acrylic acid 106 ℃
Methacrylic acid 228 ° C

  Regarding the glass transition temperature of homopolymers of monomers other than those exemplified above, the values described in “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989) are used. The highest value is adopted for the monomer whose values are described in this document.

  For monomers for which the glass transition temperature of the homopolymer is not described in the above document, the value obtained by the following measurement method is used (see JP 2007-51271 A). Specifically, a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser is charged with 100 parts by weight of monomer, 0.2 part by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent. Stir for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Next, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid concentration of 33% by weight. This homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to a shear strain at a frequency of 1 Hz using a viscoelasticity testing apparatus (ARES, manufactured by TA Instruments Inc.). Viscoelasticity is measured by shear mode at a temperature increase rate of −70 to 150 ° C. and 5 ° C./min, and the peak top temperature of tan δ (loss tangent) is defined as the glass transition temperature.

  Although not particularly limited, the acrylic polymer is such that the proportion of the monomer having a glass transition temperature of -45 ° C or lower of the homopolymer is 50% by weight or more in the total amount of monomers used for the synthesis of the acrylic polymer. (More preferably 70% by weight or more, for example 85% by weight or more). The acrylic polymer having such a copolymer composition tends to improve impact resistance. The upper limit of the ratio is not particularly limited, and may be 100% by weight of the total monomer amount. From the viewpoint of cohesiveness of the pressure-sensitive adhesive, it is usually appropriate that the proportion of the homopolymer having a glass transition temperature of −45 ° C. or less in the total monomer amount is 99% by weight or less, and 97% by weight or less. It is preferable that

  In the technology disclosed herein, the method for obtaining an acrylic polymer is not particularly limited, and is known as a method for synthesizing an acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method. Various polymerization methods can be appropriately employed. For example, a solution polymerization method can be preferably used. As a monomer supply method when performing solution polymerization, a batch charging method, a continuous supply (dropping) method, a divided supply (dropping) method, or the like that supplies all monomer raw materials at once can be appropriately employed. The polymerization temperature can be appropriately selected according to the type of monomer and solvent to be used, the type of polymerization initiator, and the like, for example, about 20 ° C. to 170 ° C. (typically 40 ° C. to 140 ° C.). it can.

  The initiator used for the polymerization can be appropriately selected from known or commonly used polymerization initiators according to the type of polymerization method. For example, azo polymerization such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (2-amidinopropane) dihydrochloride Initiators may be preferably used. Other examples of polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; phenyl-substituted ethane And substituted ethane-based initiators; aromatic carbonyl compounds; Still another example of the polymerization initiator includes a redox initiator based on a combination of a peroxide and a reducing agent. Examples of such redox initiators include a combination of peroxide such as hydrogen peroxide and ascorbic acid, a combination of peroxide such as hydrogen peroxide and iron (II) salt, persulfate and sulfurous acid. A combination with sodium hydride and the like can be mentioned. A polymerization initiator can be used individually by 1 type or in combination of 2 or more types. The amount of the polymerization initiator used may be a normal amount, for example, about 0.005 to 1 part by weight (typically 0.01 to 1 part by weight) with respect to 100 parts by weight of all monomer components. You can choose from a range.

  The solvent (polymerization solvent) used in the solution polymerization can be appropriately selected from known or common organic solvents. For example, aromatic compounds (typically aromatic hydrocarbons) such as toluene and xylene; aliphatic or alicyclic hydrocarbons such as ethyl acetate, hexane, cyclohexane, methylcyclohexane; 1,2-dichloroethane, etc. Halogenated alkanes: lower alcohols such as isopropyl alcohol, 1-butanol, sec-butanol, tert-butanol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether Any one solvent selected from ketones such as methyl ethyl ketone and acetylacetone, and the like, or a mixed solvent of two or more may be used. 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 solution polymerization, a polymerization reaction liquid in a form in which an acrylic polymer is dissolved in an organic solvent is obtained. The pressure-sensitive adhesive layer in the technology disclosed herein may be formed from a pressure-sensitive adhesive composition containing the polymerization reaction solution or an acrylic polymer solution obtained by subjecting the reaction solution to a suitable post-treatment. As 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 solution prepared by synthesizing an acrylic polymer by a polymerization method other than solution polymerization (for example, emulsion polymerization, photopolymerization, bulk polymerization, etc.) and dissolving the acrylic polymer in an organic solvent may be used. Good.

The weight average molecular weight of the acrylic polymer (Mw) is not particularly limited, it may be in the range, for example ^{10 × 10 4 ~500 × 10 4} . 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 , because it is easy to balance the adhesive properties. A range of × 10 ⁴ to 75 × 10 ⁴ is more preferable. In addition, Mw of acrylic polymer is calculated | required as a value of standard polystyrene conversion by performing GPC (gel permeation chromatography) about the solvent soluble part (for example, tetrahydrofuran soluble part) of this acrylic polymer.

  The pressure-sensitive adhesive composition (for example, an acrylic pressure-sensitive adhesive composition) in the technology disclosed herein may contain a tackifier resin. The tackifying resin is not particularly limited, and various types of tackifying resins such as rosin-based, terpene-based, hydrocarbon-based, epoxy-based, polyamide-based, elastomer-based, phenol-based, and ketone-based resins can be used alone. Alternatively, two or more kinds can be used in combination.

  Specific examples of rosin-based tackifying resins include unmodified rosins (raw rosins) such as gum rosin, wood rosin, tall oil rosin; modified rosins modified by hydrogenation, disproportionation, polymerization, etc. Hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosins, etc.); various other rosin derivatives; Examples of the rosin derivatives include those obtained by esterifying unmodified rosin with alcohols (ie, rosin esterified products) and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) with alcohols. Rosin esters such as modified rosin esterified products (ie, unmodified rosins and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) modified with unsaturated fatty acids. Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; Unmodified rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid-modified rosin or unsaturated fatty acid Rosin alcohols obtained by reducing carboxyl groups in modified rosin esters; unmodified rosin, modified rosin Metal salts of rosins (particularly rosin esters) such as various rosin derivatives; rosin phenol obtained by adding phenol to an rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermal polymerization Resin; and the like.

  Examples of terpene-based tackifier resins include terpene resins such as α-pinene polymers, β-pinene polymers, and dipentene polymers; modification of these terpene resins (phenol modification, aromatic modification, hydrogenation modification, hydrocarbons) Modified terpene resin) and the like. Examples of the modified terpene resin include terpene phenol resin, styrene modified terpene resin, aromatic modified terpene resin, hydrogenated terpene resin and the like.

  Examples of hydrocarbon tackifying resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc. ), Various hydrocarbon resins such as aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, coumarone indene resins, and the like. 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. Examples of the olefin include 1-butene, isobutylene, 1-pentene and the like. Examples of the diene include butadiene, 1,3-pentadiene, isoprene and the like. Examples of aromatic hydrocarbon resins include polymers of vinyl group-containing aromatic hydrocarbons having about 8 to 10 carbon atoms (styrene, vinyl toluene, α-methylstyrene, indene, methylindene, etc.). It is done. Examples of the aliphatic cyclic hydrocarbon resin include an alicyclic hydrocarbon resin obtained by cyclizing and dimerizing a so-called “C4 petroleum fraction” or “C5 petroleum fraction”; a cyclic diene compound ( Cyclopentadiene, dicyclopentadiene, ethylidene norbornene, dipentene, etc.) polymer or hydrogenated product thereof; aromatic hydrocarbon resin or alicyclic hydrocarbon system in which aromatic ring of aliphatic / aromatic petroleum resin is hydrogenated Resin; and the like.

  In the technique disclosed herein, a resin 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 as the tackifying resin. According to the pressure-sensitive adhesive containing the tackifying resin having the softening point equal to or higher than the lower limit described above, a fixing member having more excellent repulsion resistance can be realized. Of the tackifying resins exemplified above, a terpene tackifying resin having such a softening point (for example, a terpene phenol resin), a rosin tackifying resin (for example, an esterified product of polymerized rosin), or the like can be preferably used. . The tackifier resin can be preferably used in an embodiment containing, for example, a terpene phenol resin having a softening point of 135 ° C. or higher. In addition, according to the pressure-sensitive adhesive containing a tackifying resin having a softening point of 140 ° C. or higher, particularly excellent repulsion resistance can be realized. 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 tackifying resin is not particularly limited, and can be, for example, about 200 ° C. or lower (typically about 180 ° C. or lower). In addition, the softening point of tackifying resin can be measured based on the softening point test method (ring ball method) prescribed | regulated to JISK2207.

  The amount of the tackifying resin used is not particularly limited, and can be appropriately set according to the target tack performance (adhesive strength, etc.). For example, the tackifier resin is used at a ratio of about 10 to 100 parts by weight (more preferably 15 to 80 parts by weight, still more preferably 20 to 60 parts by weight) with respect to 100 parts by weight of the acrylic polymer based on the solid content. It is preferable to do.

  As an example of a suitable composition of the acrylic pressure-sensitive adhesive disclosed herein, a composition containing 20 to 60 parts by weight of a tackifying resin having a softening point of 120 ° C. or higher with respect to 100 parts by weight of the acrylic polymer, the acrylic polymer Examples thereof include a composition containing 10 to 50 parts by weight of a tackifying resin having a softening point of 135 ° C. or higher with respect to 100 parts by weight. According to the acrylic pressure-sensitive adhesive having such a composition, the repulsion resistance and the flexibility tend to be preferably compatible.

  A crosslinking agent may be used in the pressure-sensitive adhesive composition as necessary. The type of the crosslinking agent is not particularly limited, and is a known or conventional crosslinking agent (for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a melamine crosslinking agent, a peroxide crosslinking agent). , Urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, carbodiimide crosslinking agents, amine crosslinking agents, etc.). A crosslinking agent can be used individually by 1 type or in combination of 2 or more types. The amount of the crosslinking agent used is not particularly limited, and is, for example, 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) with respect to 100 parts by weight of the acrylic polymer. You can choose from a range of

  The pressure-sensitive adhesive composition comprises a leveling agent, a crosslinking aid, a plasticizer, a softener, a filler, a colorant (pigment, dye, etc.), an antistatic agent, an anti-aging agent, an ultraviolet absorber, and an antioxidant as necessary. It may contain various additives generally used in the field of pressure-sensitive adhesive compositions, such as an agent and a light stabilizer. About such various additives, conventionally well-known things can be used by a conventional method, and since it does not characterize this invention in particular, detailed description is abbreviate | omitted.

  The fixing member disclosed herein may have desired optical characteristics (transmittance, reflectance, etc.). For example, it is preferable that the fixing member used for light shielding has a visible light transmittance of 0% to 15% (more preferably 0% to 10%). Moreover, it is preferable that the fixing member used for a light reflection application has a visible light reflectance of 20% to 100% (more preferably 25% to 100%). The optical characteristics of the fixing member can be adjusted, for example, by coloring the foam base material as described above.

  The fixing member disclosed herein is preferably halogen-free from the viewpoint of preventing corrosion of the metal. This is preferable from the viewpoint of reducing the environmental load because generation of halogen-containing gas during combustion of the fixed member can be suppressed. Halogen-free fixing members do not intentionally use a halogen compound as a foam base material or pressure-sensitive adhesive material, use a foam base material that does not intentionally contain a halogen compound, and use an additive when a halogen is used. It can be obtained by adopting means such as not using an additive derived from a compound singly or in appropriate combination.

<Manufacture and use of fixing members>
The manufacturing method of the fixing member disclosed here is not particularly limited. As a preferred example, there is a method of preparing an adhesive sheet original fabric having an adhesive layer on a sheet-shaped foam substrate, and processing the adhesive sheet original fabric into the shape of a fixing member. Although not particularly limited, the pressure-sensitive adhesive sheet is typically a continuous sheet having no holes penetrating in the thickness direction, and has a width of, for example, 20 cm or more (typically 50 cm or more) and a length. Can be, for example, 1 m or more (typically 5 m or more). Various known cutting means can be applied as means for processing the pressure-sensitive adhesive sheet material into the shape of the fixing member. Non-limiting examples of such cutting means include punching (such as punching with a Thomson blade), cutting, laser cutting, water jet cutting, thermal cutting, and the like. These can be implemented individually by 1 type or in combination of 2 or more types. Each cutting means may be performed twice or more.

  The material to be fixed (display unit or display unit protection member) and the casing to be joined using the fixing member disclosed herein is not particularly limited, and for example, a metal material such as stainless steel (SUS) or aluminum; Inorganic materials such as glass and ceramics; polycarbonate (PC), polymethyl methacrylate (PMMA), polypropylene, polyethylene terephthalate (PET), acrylonitrile butadiene styrene copolymer resin (ABS), high impact polystyrene (HIPS), PC-ABS It can be selected from resin materials such as blend resin and PC-HIPS blend resin; rubber materials such as natural rubber and butyl rubber; and composite materials thereof.

The shape of the part to be fixed to be joined using the fixing member disclosed herein is not particularly limited. A plate shape is mentioned as a typical shape of the component to be fixed. The plate-like concept includes a flat plate shape, a curved plate shape, and a composite shape thereof. In a typical embodiment, the shape of the part to be fixed may be a rectangular or square flat plate (rectangular plate). In the component to be fixed having such a shape, the ratio of the length of the long side to the length of the short side may be, for example, 1: 1 to 1: 5 (typically 1: 1 to 1: 3). The length of the long side (in the case of a square, the length of one side) is, for example, 3.5 cm or more (preferably 5.5 cm or more, more preferably 7.5 cm or more, and further preferably 10.5 cm or more). It can be. The technology disclosed herein can be preferably applied to, for example, a portable electronic device in which the area of the component to be fixed is 25 cm ² or more (typically 25 to 5000 cm ² , preferably 50 to 3000 cm ² ).

  When the fixing member disclosed herein is in the form of a double-sided adhesive fixing member, the fixing member is carried in the form of a fixing member with a release liner in which at least one (preferably both) adhesive surfaces are protected by a release liner. It is preferably used for assembling electronic equipment. Such a fixing member with a release liner is advantageous from the viewpoint of handleability in production, distribution, storage, pasting and the like. A conventional release paper or the like can be used as the release liner, and is not particularly limited. For example, a release liner having a release treatment layer on the surface of a liner substrate such as a plastic film or paper; from a low adhesive material such as a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) A release liner can be used. The release treatment layer may be formed, for example, by surface-treating the liner base material with a release treatment agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

  In the fixing member with a release liner in which both adhesive surfaces of the double-sided adhesive fixing member are protected by two release liners, the release liner that protects at least one of the adhesive surfaces is a light-transmitting release liner. It is preferable. For example, as shown in FIG. 8, the fixing member disclosed herein is a release liner in a form in which the first adhesive surface 124 </ b> A and the second adhesive surface 126 </ b> A of the fixing member 100 are protected by light-transmitting release liners 151 and 152, respectively. It is preferable to be used for assembling a portable electronic device in the form of the attachment member 50. Thereby, it becomes easy to affix the fixing member 100 with high precision, and it can contribute to the stable production of a portable electronic device with high joining reliability. As the light-transmitting release liners 151 and 152, transparent resin films having at least surfaces (peeling surfaces) 151A and 152A having peelability on the surface of the fixing member 100 can be preferably used.

  Preferable examples of the resin film used for such a light-transmitting release liner include a polypropylene (PP) film, a polyethylene terephthalate (PET) film, a polyimide film, and a polyethylene film. PP resin and PET film are mentioned as a preferable resin film from a viewpoint of shape maintenance property and dimensional stability. The thickness of the light-transmitting release liner is not particularly limited, but is usually 25 to 500 μm, preferably 50 to 300 μm (for example, 50 to 150 μm).

Note that the matters disclosed by this specification include the following.
(1) A fixing member (fixing member for a display unit or the like) for fixing a display unit or display unit protection member of a portable electronic device to a housing, the foam base material, and at least one of the foam base material And an adhesive layer disposed on the surface of
The fixing member has a narrow portion having a width of less than 2.0 mm,
The fixing member includes an average width W [mm] of the narrow width portion, a 100% modulus M [N / mm ² base material] of the fixing member, and a thickness Hs [mm] of the foam base material. A fixing member whose relationship satisfies the following formula: 0.4 / (M × Hs) ≦ W;
(2) The fixing member according to (1), which is configured as a double-sided adhesive fixing member having an adhesive layer on one surface and the other surface of the foam substrate.
(3) The fixing member according to (1) or (2), wherein the area Ao of the window section defined by the inner edge of the fixing member is five times or more the area Af of the fixing member.
(4) The fixing member according to any one of (1) to (3), including the narrow part and a non-narrow part having a width of 2.0 mm or more.
(5) The fixing member according to any one of (1) to (4), wherein an average width W of the narrow portion is less than 1.0 mm.
(6) The fixing member according to any one of (1) to (5), which is formed in a frame shape.
(7) The fixing member according to any one of (1) to (6), which has a frame shape and has a long side length of 5 cm or more.
(8) A rectangular frame shape, wherein at least one (preferably both) long side occupies 50% or more of the length of the long side of the long side, (1) The fixing member according to any one of to (7).
(9) The fixing member according to any one of (1) to (8), wherein the fixing member has a frame shape, and at least one of the four corners has a round outer edge.
(10) The fixing member according to any one of (1) to (9), wherein the fixing member is formed in a seamless annular shape.
(11) Any of (1) to (10) above, wherein an average width W [mm] of the narrow portion is 1.0 times or more of a thickness Hf [mm] of the fixing member in the narrow portion. A fixing member according to any one of the above.
(12) The fixing member according to any one of (1) to (11), wherein a thickness Hf of the fixing member is 0.10 to 0.30 mm.
(13) The above (1) to (12), wherein the relationship between the 100% modulus M [N / mm ² substrate] and the foam substrate thickness Hs [mm] satisfies 0.50 ≦ M × Hs. The fixing member according to any one of the above.
(14) The fixing member according to any one of (1) to (13), wherein the visible light transmittance of the fixing member is 0% to 15%.
(15) The fixing member according to any one of (1) to (14), wherein the foam base material is colored black.
(16) The fixing member according to any one of (1) to (15), wherein the foam base material is a polyolefin-based foam base material.
(17) The fixing member according to any one of (1) to (16), wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having an acrylic polymer as a base polymer.
(18) The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having an acrylic polymer as a base polymer,
70% by weight or more (preferably 85% by weight or more) of the total amount of monomers used for the synthesis of the acrylic polymer is a monomer having a Tg of the homopolymer of −45 ° C. or less, (1) to (17) The fixing member according to any one of the above.
(19) The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having an acrylic polymer as a base polymer,
The fixing member according to any one of (1) to (18), wherein 0.2 to 8% by weight of the total amount of monomers used for the synthesis of the acrylic polymer is a carboxyl group-containing monomer.
(20) The fixing member according to any one of (1) to (19), wherein the pressure-sensitive adhesive layer includes 20 to 80 parts by weight of a tackifier resin with respect to 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer. .
(21) A fixing member (fixing member for a display unit or the like) for fixing the display unit or the display unit protection member of the portable electronic device to the housing,
It is configured as a double-sided adhesive fixing member having an adhesive layer on one side and the other side of the foam substrate,
The area Ao of the window section defined by the inner edge of the fixing member is not less than 5 times the area Af of the fixing member,
The fixing member has a seamless rectangular frame shape and has a narrow width portion having a width of less than 2.0 mm and a non-thin width portion having a width of 2.0 mm or more, and at least one length of the rectangular frame shape. 50% or more of the side of the long side is the narrow portion,
The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having an acrylic polymer as a base polymer, and 70% by weight or more of the total amount of monomers used for the synthesis of the acrylic polymer has a Tg of the homopolymer of −45 ° C. or lower. Monomer,
The fixing member includes an average width W [mm] of the narrow width portion, a 100% modulus M [N / mm ² base material] of the fixing member, and a thickness Hs [mm] of the foam base material. A fixing member whose relationship satisfies the following formula: 0.4 / (M × Hs) ≦ W;
(22) a display unit or a display unit protection member;
A housing to which the display unit or the display unit protection member is fixed;
A portable electronic device including a fixing member interposed between the display unit and the casing or between a display unit protection member and the casing,
The fixing member includes a foam base material, and an adhesive layer disposed on at least one surface of the foam base material,
The fixing member has a narrow portion having a width of less than 2.0 mm, and the fixing member includes a width W [mm] of the narrow portion and a 100% modulus M [N / mm ^{2 of the} fixing member. Material] and the thickness Hs [mm] of the foam base material satisfy the following formula: 0.4 / (M × Hs) ≦ W;
The display unit and the casing, or the display unit protection member and the casing are portable electronic devices joined in a liquid-tight manner by a seal portion including the fixing member.
(23) The portable electronic device according to (22), wherein the fixing member is the fixing member according to any one of (1) to (21).

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

<Production of double-sided PSA sheet>
(Example 1)
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping device and nitrogen introduction tube, 2.9 parts of acrylic acid, 5 parts of vinyl acetate, 92 parts of n-butyl acrylate, 0.1 part of 2-hydroxyethyl acrylate In addition, 30 parts of ethyl acetate and 120 parts of toluene were added as polymerization solvents, and the mixture was stirred for 2 hours while introducing nitrogen gas.
After removing oxygen in the polymerization system in this way, 0.2 part of 2,2′-azobisisobutyronitrile (AIBN) was added, the temperature was raised to 60 ° C., and a polymerization reaction was performed for 6 hours. A polymer solution containing the polymer was obtained. The solid content of this polymer solution was 40.0%, and the polymer Mw was 50 × 10 ⁴ .
To 100 parts of the polymer solution, 10 parts of the trade name “Pencel D-125” (rosin-based tackifier resin, solid content 100%) manufactured by Arakawa Chemical Industries, Ltd., Arakawa Chemical Industries Trade name “Superester A-100” (Rosin tackifier resin, solid content 100%) 10 parts, manufactured by Eastman Chemical Co., Ltd. “Forarin 8020F” (Rosin tackifier resin, solid content 100) %) And 15 parts of a trade name “Tamanol 803L” (terpene phenol resin, solid content: 100%) manufactured by Arakawa Chemical Industries, Ltd. were added and stirred sufficiently until dissolved. Furthermore, aromatic polyisocyanate as a crosslinking agent (trade name “Coronate L”, manufactured by Nippon Polyurethane Industry Co., Ltd., solid content: 75%) at a ratio of 2.0 parts with respect to 100 parts of polymer in the polymer solution. Was added and sufficiently stirred to obtain a solvent-type pressure-sensitive adhesive composition.
Two commercially available release liners (trade name “SLB-80W3D”, manufactured by Sumika Kogyo Co., Ltd.) were prepared. The above-mentioned pressure-sensitive adhesive composition is applied to one surface (peeling surface) of each of these release liners so that the thickness after drying is 50 μm and dried at 100 ° C. for 2 minutes, whereby the two sheets are peeled off. An adhesive layer was formed on each release surface of the liner. These pressure-sensitive adhesive layers were formed on a polyethylene foam sheet (thickness 0.15 mm, density 0.56 g / cm ³ , 10% compressive strength (C ₁₀ ) 167 kPa, 25% compressive strength). (C ₂₅ ) 468 kPa, 30% compressive strength (C ₃₀ ) 627 kPa, average bubble diameter 55 μm; hereinafter referred to as “base material 1A”). The release liner was left on the pressure-sensitive adhesive layer as it was and used for protecting the surface (pressure-sensitive surface) of the pressure-sensitive adhesive layer. The obtained structure was passed once through a laminator (0.3 MPa, speed 0.5 m / min) at 80 ° C., and then cured in an oven at 50 ° C. for 1 day. Thus, the double-sided pressure-sensitive adhesive sheet according to Example 1 was obtained.

(Example 2)
Instead of the substrate 1A, a polyethylene foam sheet (thickness 0.15 mm, density 0.56 g / cm ³ , 10% compressive strength (C ₁₀ ) 100 kPa, 25% compressive strength, which has been subjected to corona discharge treatment on both sides. (C ₂₅ ) 365 kPa, 30% compressive strength (C ₃₀ ) 515 kPa, average cell diameter 155 μm; hereinafter referred to as “base material 1B”)). Obtained.

(Example 3)
Instead of the base material 1A, a polyethylene foam sheet (thickness 0.15 mm, density 0.37 g / cm ³ , 10% compressive strength (C ₁₀ ) 34 kPa, 25% compressive strength, which has been subjected to corona discharge treatment on both sides. (C ₂₅ ) 92 kPa, 30% compressive strength (C ₃₀ ) 117 kPa, average cell diameter 90 μm; hereinafter referred to as “base material 2A”). Obtained.

(Example 4)
In place of the substrate 1A, a polyethylene foam sheet (thickness 0.20 mm, density 0.20 g / cm ³ , 10% compressive strength (C ₁₀ ) 19 kPa, 25% compressive strength, which has been subjected to corona discharge treatment on both sides. (C ₂₅ ) 47 kPa, 30% compressive strength (C ₃₀ ) 59 kPa, average cell diameter 90 μm; hereinafter referred to as “base material 3A”). Obtained.

About the double-sided adhesive sheet (adhesive sheet raw material for fixing member preparation) which concerns on each example, MD modulus and TD modulus are measured by the method mentioned above, 100% modulus M [N / mm ² group of the adhesive sheet which concerns on each example Material] and M × Hs were calculated. As a result, in Example 1, 100% modulus M is 6.4 N / mm ² substrate (MD modulus is 6.5 N / mm ² substrate, TD modulus is 6.2 N / mm ² substrate), and M × Hs is 0. 96 N / mm, in Example 2, 100% modulus M is 5.0 N / mm ² substrate (MD modulus is 5.6 N / mm ² substrate, TD modulus is 4.5 N / mm ² substrate), M × Hs Is 0.75 N / mm, in Example 3, 100% modulus M is 5.5 N / mm ² substrate (MD modulus is 4.5 N / mm ² substrate, TD modulus is 6.5 N / mm ² substrate), M XHs is 0.83 N / mm, and in Example 4, 100% modulus M is 4.6 N / mm ² substrate (MD modulus is 6.1 N / mm ² substrate, TD modulus is 3.1 N / mm ² substrate) , M × Hs was 0.92.

<Drop durability test>
The double-sided PSA sheet prepared above 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 FIGS. A fixing member (double-sided adhesive fixing member) having a width W of 1.0 mm was produced. Using this fixing member, a polycarbonate plate (width 70 mm, length 130 mm, thickness 2 mm) and a glass plate (width 59 mm, length 113 mm, thickness 0.5 mm) are bonded together by pressing for 10 seconds under a load of 50 N. Thus, a sample for evaluation was obtained.
FIGS. 9A and 9B are schematic views of the sample for evaluation, where FIG. 9A is a top view and FIG. 9B is a cross-sectional view along BB ′ thereof. Reference numeral 400 denotes a fixing member, reference numeral 401 denotes a polycarbonate plate, and reference numeral 402 denotes a glass plate.
A 160 g weight was attached to the back surface (the surface opposite to the surface bonded to the glass plate) of the polycarbonate plate of the evaluation sample. About the sample for evaluation with the said weight, the drop test which makes it fall freely to a concrete board 60 times from the height of 1.2 m in normal temperature (about 23 degreeC) was done. At this time, the direction of the fall was adjusted so that the six surfaces of the sample for evaluation became sequentially lower. That is, 10 cycles of one drop pattern were performed for each of the six surfaces. Each time it is dropped, it is visually checked whether the polycarbonate plate and the glass plate are joined, and the number of drops until the polycarbonate plate and the glass plate are peeled (separated) is dropped at room temperature. The durability was evaluated. When peeling was not recognized even after dropping 60 times, it was evaluated as “over 60”.

An evaluation sample was prepared in the same manner as described above except that the width (average width W) of the fixing member was changed to 0.7 mm, 0.5 mm, and 0.3 mm, and a drop durability test was performed in the same manner.
Table 1 shows the evaluation results for the fixing members of each average width W.

  As shown in Table 1, when the pressure-sensitive adhesive sheet of Example 1 is processed into a fixing member having a shape satisfying 0.4 / (M × Hs) ≦ W (here, the average width W is 0.5 mm or more) ) Showed excellent impact resistance with a drop durability of more than 60 times. The pressure-sensitive adhesive sheet of Example 2 also has a drop durability of 60 when processed into a fixing member having a shape satisfying 0.4 / (M × Hs) ≦ W (here, the average width W is 0.7 mm or more). Excellent impact resistance of more than times.

  In addition, waterproofness was evaluated based on the IPX7 standard (JIS C 0920 / IEC 60529) for the evaluation sample after the drop durability test (after dropping 60 times) (specifically, 23 ° C., 50% RH). In this example, the pressure sensitive adhesive sheet was submerged in a 1 m water tank for 30 minutes, and the presence or absence of water immersion inside was confirmed. However, in the pressure-sensitive adhesive sheet of Example 1, no water immersion was observed at an average width of 0.5 mm or more. Waterproofness was maintained. In the pressure-sensitive adhesive sheet of Example 2, water immersion was observed at an average width W of 0.7 mm, but water immersion was not observed at an average width W of 1.0 mm, and good waterproofness was maintained even after a drop impact.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

1 portable electronic device 10 lens (protecting member for display unit)
20 Housing 22 Liquid crystal module unit 24 Spacer 26 Backlight unit 30 Sealing part 50 Fixing member with release liner 100, 200, 300 Fixing member 100a, 200a Inner edge 102a, 102b, 102c, 102d Narrow width part 104a, 104b, 104c, 104d Land part 110, 210 Window part 122 Foam base material 124 First adhesive layer 124A First adhesive surface 126 Second adhesive layer 126A Second adhesive surface 151, 152 Release liner 151A, 152A Release surface 202a, 202b, 202c Fine Width part 204a, 204b Land part 206 Opening part 230 Sealing material 300A, 300B Sub fixing member 300e Seam 400 Fixing member 401 Polycarbonate plate 402 Glass plate

Claims (11)

A fixing member for fixing the display unit or display unit protection member of the portable electronic device to the housing,
A foam base material, and an adhesive layer disposed on at least one surface of the foam base material,
The fixing member has a narrow portion having a width of less than 2.0 mm,
The area Ao of the window section defined by the inner edge of the fixing member is not less than 5 times the area Af of the fixing member,
100% modulus M of the fixing member is 4.0 N / mm ² or more base material,
The relationship between the 100% modulus M [N / mm ² base material] and the thickness Hs [mm] of the foam base material satisfies 0.50 ≦ M × Hs, and the fixing member includes the narrow portion. average width W [mm], the 100% modulus M [N / mm ² base material, the relationship between the thickness Hs [mm] of the foam substrate following formula: 0.4 / (M × A fixing member that satisfies Hs) ≦ W;   The fixing member according to claim 1, wherein an area Ao of the window portion is 20 times or more an area Af of the fixing member.   The fixing member according to claim 1 or 2, wherein an average width W [mm] of the narrow portion is 1.0 or more times a thickness Hf [mm] of the fixing member in the narrow portion. The relationship between the 100% modulus M [N / mm ² substrate] and the thickness Hs [mm] of the foam substrate satisfies 0.80 ≦ M × Hs. The fixing member as described in.   The fixing member according to claim 1, wherein the fixing member is formed in a seamless annular shape.   The fixing member as described in any one of Claim 1 to 5 comprised as a double-sided adhesive fixing member which has an adhesive layer in the one surface and the other surface of the said foam base material.   The fixing member according to claim 1, wherein the foam base material is a polyolefin-based foam base material.   The fixing member according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having an acrylic polymer as a base polymer.   The fixing member according to any one of claims 1 to 8, wherein a thickness Hs of the foam base material is 0.05 mm or more and 0.30 mm or less.   The fixing member according to claim 1, wherein an average width W [mm] of the narrow portion is less than 1.0 mm. A display unit or a display unit protection member;
A housing to which the display unit or the display unit protection member is fixed;
A portable electronic device including a fixing member interposed between the display unit and the casing or between a display unit protection member and the casing,
The fixing member is a fixing member according to any one of claims 1 to 10,
The display unit and the casing, or the display unit protection member and the casing are portable electronic devices joined in a liquid-tight manner by a seal portion including the fixing member.

Images