Electronic article having interlayer adhesive layer with damping / shock absorbing function

Abstract

An electronic article having an interlayer adhesive layer having a temperature at the tan delta peak of less than 35 DEG C and a tan delta value at the peak of greater than 1.0, as measured by a dynamic mechanical analysis rheometer using a parallel plate measurement system at 1 Hz. In the electronic article of the present invention, the interlayer adhesive layer is arranged between two functional layers to bond or assemble the two functional layers and provides impact resistance to the electronic article as a damping / shock absorbing layer. Preferably, the electronic article of the invention is a display device.

Description

[0001] Cross - reference to related applications

[0002] None. Technical field

[0003] The present invention relates to an electronic article having an interlayer adhesive layer that bonds / assembles a functional layer having a damping / shock - absorbing function. Specifically, the present invention relates to an electronic article (including electronic devices, equipment, parts / modules, and units) having an interlayer adhesive layer that exhibits specific visco - elastic properties in its tanδ curve measurement and bonds / assembles a functional layer of the electronic article having a damping / shock - absorbing function. The electronic article can be used in display device applications having a structure in which a transparent display unit is directly bonded or assembled to other functional units through the interlayer adhesive layer, and the interlayer adhesive layer provides impact resistance to the electronic article as a damping / shock - absorbing layer. Preferably, the interlayer adhesive layer is a silicone - based pressure - sensitive adhesive layer. Background art

[0004] Recent electronic articles (including electronic devices, equipment, parts / modules, and units; typically, LED or OLED - type display devices and their modules) are composed of many functional layers and adopt a structure in which a film composed of multiple layers including an electrode layer and a display layer is sandwiched between substrates. To construct / assemble such electronic articles, an interlayer adhesive layer is arranged as an "assembly layer" between the functional layers to bond / assemble the functional layers in these electronic articles. Specifically, since a silicone - based pressure - sensitive adhesive (PSA) layer has excellent electrical insulation properties, heat resistance, cold resistance, and adhesiveness to various adherends compared to acrylic or rubber - based pressure - sensitive adhesive compositions. Utilizing the above - mentioned characteristics of polysiloxane pressure - sensitive adhesives and the characteristic that their required high transparency can be achieved, applications in advanced electronic materials and display elements such as the field of smart devices have been studied in recent years. In addition, although Patent Documents 1 to 4 disclose the properties of silicone - based PSA in its tanδ curve, there is no disclosure or suggestion of using a single silicone - based PSA layer as an interlayer assembly layer having a damping / shock - absorbing function in an electronic article such as a display device.

[0005] On the other hand, in order to improve mechanical and electrical reliability and provide shock resistance to the electronic article, in the conventional design of an electronic article (e.g., an LED or OLED type display device applied to an automotive display, a foldable display, etc.), a foam tape (e.g., PU foam, PE foam, or acrylic foam) or other interlayer damping or shock-absorbing layer is applied in a manner sandwiched between two adhesive layers to bond other functional layers (e.g., a display layer and an electrode layer) in the following manner: [display layer / 1st adhesive layer / damping or shock-absorbing layer / 2nd adhesive layer / electrode layer]. As these display electronic devices, specifically smartphones with OLED displays, become thinner and thinner, this interlayer damping or shock absorption becomes increasingly crucial to protect the screen from cracking during a drop test. For example, Patent Documents 5 and 6 propose using a foam sheet having a silicone-based PSA layer or a damping laminate using a silicone-based PSA layer, but there is a market demand for the damping or shock-absorbing layer to have better damping ability. Additionally, since the foam layer or other said damping or shock-absorbing layer requires adhesive layers on both sides to bond / assemble to other functional layers, multiple lamination processes are required to construct an electronic article (e.g., an LED or OLED type display device), and the electronic article tends to become thicker and heavier due to the internal multi-layer damping or shock-absorbing layer. Therefore, in order to achieve a thinner and lighter electronic article with better reliability, there is a market demand for better and improved assembly layers.

[0006] Related Technical Documents

[0007] Patent Document

[0008] [Patent Document 1] WO2018149720A1

[0009] [Patent Document 2] WO2018149718A1

[0010] [Patent Document 3] WO2018149717A1

[0011] [Patent Document 4] JP2003313515A

[0012] [Patent Document 5] JP2019167484A

[0013] [Patent Document 6] JPH04-214341A Summary of the Invention

[0014] Problems to be Solved

[0015] The present invention is made to solve the above problems, and an object thereof is to provide an electronic article having a thinner damping or shock-absorbing layer to improve mechanical and electrical reliability and provide impact resistance to the electronic article, wherein the functional layer is tightly adhered or assembled in the electronic article. In addition, an object of the present invention is to provide a simplified method for manufacturing an electronic article, in which multiple lamination processes are not required to construct its interlayer damping or shock-absorbing layer. In addition, an object of the present invention is to provide the use of an interlayer adhesive layer as a damping / shock-absorbing layer in an electronic article, wherein no additional foam layer or damping / shock-absorbing layer is provided in these electronic articles.

[0016] Ways to Solve the Problems

[0017] As a result of intensive research on the problems described above, the present inventors have completed the present invention. That is, an object of the present invention is achieved by an electronic article having an interlayer adhesive layer, and it is disclosed that the temperature at the tanδ peak of the interlayer adhesive layer is lower than 35°C, and the tanδ value at the peak is greater than 1.0. When measuring the tanδ curve of the interlayer adhesive layer, the width of the tanδ peak of the interlayer adhesive layer defined by the absolute value of the temperature range in which the tanδ value exceeds 0.5 is preferably narrower than 90°C. In the present invention, the interlayer adhesive layer is preferably a pressure-sensitive silicone adhesive layer obtained by curing a composition containing components (A) to (D) to form a silicone-based pressure-sensitive adhesive:

[0018] (A) A linear organopolysiloxane having an average of more than 1 alkenyl group per molecule;

[0019] (B) An organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 9 mol% or less relative to all silicon atoms in the molecule;

[0020] (C) An organohydrogenpolysiloxane having at least two Si-H bonds per molecule; and

[0021] (D) A hydrosilylation reaction catalyst.

[0022] The electronic article of the present invention includes the interlayer adhesive layer disposed between two functional layers to adhere or assemble the two functional layers and provide impact resistance to the electronic article as a damping / shock-absorbing layer. Preferably, the electronic article of the present invention is a display device.

[0023] The present invention also provides a method for manufacturing an electronic article of the present invention, the manufacturing method including the step of assembling or bonding at least two functional layers with an interlayer adhesive layer, the temperature at the tanδ peak of the interlayer adhesive layer being lower than 35 °C, and the tanδ value at the peak being greater than 1.0, as measured at 1 Hz using a parallel plate measurement system by a dynamic mechanical analysis rheometer.

[0024] The present invention also provides the use of an interlayer adhesive layer as a damping / shock-absorbing layer in an electronic article, wherein the temperature at the tanδ peak of the interlayer adhesive layer is lower than 35 °C, and the tanδ value at the peak is greater than 1.0, as measured at 1 Hz using a parallel plate measurement system by a dynamic mechanical analysis rheometer.

[0025] Effects of the Present Invention

[0026] Since the interlayer adhesive layer has an adhesiveness sufficient for actually bonding or assembling the functional layers in the electronic article of the present invention, and also provides shock resistance to the electronic article as a damping / shock-absorbing layer, the electronic article having a thinner and lighter laminated structure can be constructed without using a separate damping or shock-absorbing layer other than the interlayer adhesive layer of the present invention. The electronic article of the present invention exhibits better damping or shock-absorbing properties to improve mechanical and electrical reliability and provides shock resistance to the electronic article. Additionally, since the interlayer adhesive layer in the electronic article of the present invention can be a single coating having both the functions of an assembly / bonding layer and a damping / shock-absorbing layer, the manufacturing method of the electronic article of the present invention can be a simplified method that does not require a multi-step lamination / coating process to construct its interlayer damping or shock-absorbing layer. Description of the Drawings

[0027] Figure 1 The results of a falling ball test of a laminate using the interlayer adhesive layer obtained through Working Example 7 are shown, where no cracks were observed at the ball contact point.

[0028] Figure 2 The results of a falling ball test of a laminate using the interlayer adhesive layer obtained through Comparative Example 1 are shown, where no cracks were observed at the ball contact point. Detailed Description

[0029] [Definition of Viscoelastic Properties Related to the Measured tanδ Curve in the Adhesive Layer]

[0030] In this specification, the temperature at the tanδ peak of the interlayer adhesive layer, the temperature range (including its absolute value between the temperatures of two points in the measured tanδ curve), the tanδ value, and other viscoelastic properties related to the measured tanδ curve mean those measured at 1 Hz using a parallel plate measurement system by a dynamic mechanical analysis rheometer.

[0031] [Structure of the Electronic Article]

[0032] As described herein, the term "electronic article" may include electronic devices, electronic equipment, and electronic parts / modules / units. First, the structure of the electronic article according to the present invention will be described. The electronic article is characterized by having at least one interlayer adhesive layer, the temperature at the tanδ peak of the at least one interlayer adhesive layer being lower than 35 °C and the tanδ value at the peak being greater than 1.0. In the electronic article, the interlayer adhesive layer is disposed between two functional layers to bond or assemble the two functional layers. Preferably, the electronic article is an LED or OLED type display device and its modules composed of many functional layers, and has a structure in which a laminate layer composed of a plurality of functional layers including an electrode layer and a display layer is sandwiched between substrates, wherein the functional layers are bonded or assembled with the interlayer adhesive layer. In a preferred form of the electronic article of the present invention, the interlayer adhesive layer is disposed between two functional layers, at least one of the functional layers being substantially transparent. Further, since the interlayer adhesive layer has both an assembly / bonding layer function and a damping / vibration damping layer function, the electronic article of the present invention does not require an interlayer damping / vibration damping layer to be further disposed between the two functional layers. Due to this dual-functional characteristic of the interlayer adhesive layer, by the present invention, the electronic article can be constructed without using any additional interlayer damping / vibration damping layer other than the interlayer adhesive layer between the two functional layers.

[0033] Most preferably, the electronic article of the present invention is an LED or OLED type display device and its modules, which have a structure in which a display unit is directly bonded or assembled to other functional units with an interlayer adhesive layer, and the interlayer adhesive layer is a single adhesive / assembly layer sandwiched between the units in the display device. Since the display device of the present invention can be designed to have substantially no interlayer damping / vibration damping layer other than the interlayer adhesive layer (i.e., thick and multi-layered damping / vibration damping layers are omitted from these devices), the total thickness of the display can be thinner and lighter compared to conventional devices.

[0034] The surface shape of such display devices may be a curved shape or an arcuate shape instead of a flat surface, and examples thereof include curved displays or curved transmissive screens for automobiles (including electric vehicles), airplanes, etc., and various flat panel displays (FPDs). Further, these display devices can display on the screen or display notification indicators such as icons, emails, programs, etc. for executing functions or programs, and operation buttons for various devices such as car navigation devices, membranes of speakers, audio devices, and air conditioning devices, and have a touch panel function that enables input operations to be added by touching these icons, notification indicators, or operation buttons with a finger. Applications using CRT displays, liquid crystal displays, plasma displays, organic EL displays, inorganic EL displays, LED displays, surface electrolytic displays (SEDs), field emission displays (FEDs), and other display devices, or touch panels using these display devices are possible.

[0035] [Functions, Thickness and Viscoelastic Properties of the Interlayer Adhesive Layer]

[0036] In the electronic article of the present invention, as a single layer having a dual-functional feature, the interlayer adhesive layer has both an assembly / adhesion layer function and a damping / shock-absorbing layer function. That is, the interlayer adhesive layer has sufficient adhesive properties to bond or assemble two functional layers in the electronic article, and provides impact resistance to the electronic article as a damping / shock-absorbing layer to improve mechanical and electrical reliability. Although the thickness of the interlayer adhesive layer is not limited and can be optimized by those skilled in the art according to the requirements, structure, and size of the electronic article, the preferred thickness range of the interlayer adhesive layer is from 1 μm to 1000 μm, and more preferably from 10 μm to 500 μm, and most preferably from 50 μm to 300 μm. When the thickness is below the lower limit, the adhesive force and damping / shock absorption may be insufficient to achieve the object of the present invention. On the other hand, when the thickness exceeds the upper limit, a thinner and lighter electronic article cannot be achieved due to the thick interlayer adhesive layer.

[0037] To achieve the dual-functional feature in the interlayer adhesive layer for the electronic article of the present invention, the interlayer adhesive layer satisfies that the temperature at the tanδ peak is lower than 35 °C, lower than 30 °C, lower than 25 °C, lower than 20 °C or lower than 15 °C, and the tanδ value at the peak is greater than 1.0, greater than 1.2, greater than 1.5 or greater than 1.7. Preferably, the range of the tanδ value at the peak is from 1.00 to 4.00, from 1.00 to 2.00 or from 1.00 to 1.50, and the temperature at the tanδ peak is within -70 °C to 25 °C, -60 °C to 20 °C, -50 °C to 15 °C, -40 °C to 10 °C or -20 °C to 5 °C. In addition, to achieve better damping / vibration damping properties in the interlayer adhesive layer, the width of the tanδ peak in the interlayer adhesive layer defined by the absolute value of the temperature range in which the tanδ value exceeds 0.5 is narrower than 90 °C, 80 °C, 70 °C, 60 °C or 50 °C. For example, as measured by a dynamic mechanical analysis rheometer using a parallel plate measurement system at 1 Hz, when the tanδ value exceeds 0.5 in the temperature range of -60 °C to 25 °C and the tanδ peak is located between the temperature ranges, the width of the tanδ peak of the interlayer adhesive layer is defined as 85 °C as the absolute value of the temperature range. In a similar manner, when the tanδ value exceeds 0.5 in the temperature range of -50 °C to 15 °C and the tanδ peak is located between the temperature ranges, the width of the tanδ peak of the interlayer adhesive layer is defined as 65 °C as the absolute value of the temperature range. Preferably, the range of the width of the tanδ peak in the interlayer adhesive layer is from 50 °C to less than 90 °C to achieve better damping / vibration damping properties in the interlayer adhesive layer. On the other hand, when the width of the tanδ peak in the interlayer adhesive layer is 90 °C or greater, the shape of the tanδ peak is too wide to achieve sufficient damping / vibration damping properties and sufficient adhesion to bond / assemble the functional layers in the electronic article. Most preferably, in the present invention, the tanδ curve of the interlayer adhesive layer measured by a dynamic mechanical analysis rheometer using a parallel plate measurement system at 1 Hz satisfies the following conditions:

[0038] i) The temperature at the tanδ peak (preferably, the range of the tanδ value at the peak is from 1.00 to 2.50) is within -70 °C to 25 °C; and

[0039] ii) The width range of the tanδ peak defined by the absolute value of the temperature range in which the tanδ value exceeds 0.5 is from 50 °C to less than 90 °C.

[0040] In the present invention, there is no limitation on the material of the interlayer adhesive layer, and any type of adhesive material can be applied to the present invention as long as the interlayer adhesive layer satisfies the aforementioned viscoelastic properties in its tanδ curve measurement. For example, at least one selected from silicone-based pressure-sensitive adhesives (PSAs), acrylic or rubber-based adhesives, and polyurethane-based adhesives can be used as the interlayer adhesive layer in the electronic article of the present invention having both the functions of an assembly / adhesion layer and a damping / vibration damping layer. Since the silicone-based pressure-sensitive adhesive (PSA) layer has excellent electrical insulation properties, heat resistance, cold resistance, and adhesion to various adherends in this electronic article, the silicone-based PSA layer is preferably and exemplarily used as the interlayer adhesive layer in the electronic article of the present invention.

[0041] [Composition for Forming a Silicone-based PSA]

[0042] As an embodiment of the present invention, the interlayer adhesive layer applied to the electronic article of the present invention can be obtained by curing a composition based on a silicone-based pressure-sensitive adhesive. This composition cures rapidly through a curing reaction involving a hydrosilylation reaction to form a pressure-sensitive adhesive layer having sufficient adhesion for practical use and the aforementioned viscoelastic properties related to the measured tanδ curve of the adhesive layer. Hereinafter, the respective components in this composition, the range of the organopolysiloxane resin, the mass ratio of the organopolysiloxane resin to the linear organopolysiloxane, and the characteristics of the pressure-sensitive adhesive layer will be described.

[0043] As described above, the organopolysiloxane composition according to the present invention cures through a hydrosilylation reaction to form a pressure-sensitive adhesive layer (having a certain adhesive force). In this composition, an organopolysiloxane resin is used in which the total content of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9 mol% or less, and the blending range of the organopolysiloxane resin relative to the chain-like organopolysiloxane (having alkenyl groups) used as the main agent is within a specific range.

[0044] In an embodiment according to the present invention, the organopolysiloxane composition for obtaining the silicone-based PSA layer applied to the present invention comprises components (A) to (E):

[0045] (A) A linear organopolysiloxane having an average of more than 1 alkenyl group per molecule;

[0046] (B) An organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9 mol% or less;

[0047] (C) an organohydrogenpolysiloxane having at least two Si-H bonds in the molecule; and

[0048] (D) a hydrosilylation reaction catalyst.

[0049] In a further embodiment according to the invention, the composition for forming the silicone-based PSA may further comprise (A') a linear organopolysiloxane having no carbon-carbon double bond reactive groups in the molecule.

[0050] Furthermore, since the composition contains a hydrosilylation reaction catalyst, from the perspective of operability, the composition may further contain (E) a curing retarder and may further contain other additives in an amount not inconsistent with the object of the present invention. If necessary, at least one tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as an anchoring additive can be formulated to improve its adhesion without affecting its rheological / viscoelastic properties.

[0051] In the present invention, component (A) is a linear (i.e., in a chain form) organopolysiloxane having an average of more than 1 alkenyl group per molecule, wherein the preferred number of alkenyl groups per molecule is not less than 1.5, and the more preferred number of alkenyl groups per molecule is not less than 2.0. In some embodiments according to the invention, the number of alkenyl groups per molecule on average may range from 1.01 to 5.0, 1.01 to 4.0, 1.01 to 3.0, 1.01 to 2.0, 1.01 to 1.5, 1.5 to 5.0, 1.5 to 4.0, 1.5 to 3.0, 1.5 to 2.0, 2.0 to 5.0, 2.0 to 4.0, 2.0 to 3.0, 3.0 to 5.0, 3.0 to 4.0 or 4.0 to 5.0. Examples of the alkenyl groups of the organopolysiloxane of component (A) include alkenyl groups having 2 to 10 carbon atoms, such as vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group and heptenyl group, and specifically preferably vinyl group or hexenyl group. Examples of the bonding positions of these alkenyl groups of component (A) include the ends of the molecular chain and / or the side chains of the molecule. Note that component (A) may contain a single component or may be a mixture of two or more different components.

[0052] Examples of the silicon-bonded organic groups other than the alkenyl groups of the organopolysiloxane in component (A) include: alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group and heptyl group; aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as benzyl group and phenethyl group; and haloalkyl groups such as chloromethyl group, 3-chloropropyl group and 3,3,3-trifluoropropyl group, and specifically preferably methyl group and phenyl group.

[0053] In the present invention, component (A) is different from component (B) and has a linear organopolysiloxane molecular structure. For example, component (A) is preferably linear or partially branched linear, and may partially include a cyclic three-dimensional network. Preferably, the main chain of the organopolysiloxane consists of repeating diorganosiloxane units (i.e., -SiO 2 / 2 or D units), and is preferably a linear or branched diorganopolysiloxane terminated with triorganosilyloxy groups at both molecular ends. Note that the siloxane units providing the branched organopolysiloxane are T units or Q units described below.

[0054] The properties of component (A) at room temperature can be those of an oily or raw rubber-like substance. The viscosity of component (A) at 25 °C is not less than 50 mPa·s, and specifically preferably not less than 100 mPa·s. Specifically, when the linear organopolysiloxane composition according to the present invention is a solvent type, at least a part of component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of not less than 100,000 mPa·s at 25 °C or a plasticity value (read the thickness up to 1 / 100 mm when a 4.2 g spherical sample is applied with a 1 kgf load for 3 minutes at 25 °C and multiply the value by 100) measured by the method described in JIS K6249 in the range of 50 to 200, preferably 80 - 200, more preferably 100 - 200.

[0055] Note that in order to prevent contact failure, etc., it is preferable to reduce or eliminate volatile or low molecular weight siloxane oligomers (such as octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), etc.) in the alkenyl groups of the organopolysiloxane. The degree can be designed as needed, but must be less than 1% by mass of the total component (A), less than 0.1% by mass of each siloxane oligomer, and must be reduced to near the detection limit as needed.

[0056] Although the content of the alkenyl groups in component (A1) is not particularly limited, the content of the vinyl (CH2=CH) moiety in these alkenyl groups in component (A1) (hereinafter referred to as "vinyl content") can preferably be in the range of 0.005% by mass to 0.400% by mass, preferably in the range of 0.005% by mass to 0.300% by mass, and specifically preferably in the range of 0.005% by mass to 0.200% by mass.

[0057] In some embodiments according to the present invention, component (A) having a viscosity lower than that of component (A1) can also be used as component (A) of the present invention. Specifically, an organopolysiloxane (A2) containing an alkenyl group having a viscosity of less than 100,000 mPa·s at 25°C can be obtained. Here, examples other than the viscosity of component (A2) are the same as those of component (A1).

[0058] In the present invention, 50 mass% or more of component (A) is preferably an organopolysiloxane containing an alkenyl group having a high degree of polymerization, which is component (A1), and specifically preferably 75 mass% to 100 mass% thereof is component (A1). That is, when component (A1) (= an organopolysiloxane containing an alkenyl group having a relatively high degree of polymerization) and component (A2) (= an organopolysiloxane containing an alkenyl group having a relatively low degree of polymerization) are used in combination as component (A) of the present invention, the range of the mass ratio of component (A1) to component (A2) is 50:50 to 100:0, preferably 75:25 to 100:0, and more preferably 75:25 to 90:10.

[0059] In the present invention, the organopolysiloxane resin of component (B) is an adhesion-imparting component that imparts adhesiveness to the substrate, and an organopolysiloxane resin mixture having a constant ratio with component (A) is used to achieve a storage elastic modulus and a practical adhesiveness range at low temperatures. More specifically, component (B) is an organopolysiloxane resin having a small average molecular weight, in which the content of hydroxyl groups or hydrolyzable groups is suppressed, and in which the hydrolysis / polymerization reaction between components (B) tends not to occur, and the selective use of an organopolysiloxane resin having a small average molecular weight achieves a predetermined storage elastic modulus and a practical adhesiveness range in the pressure-sensitive adhesive layer as its cured product.

[0060] Specifically, component (B) is an organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 9 mol% or less, 8 mass% or less, 6 mass% or less relative to the number of all silicon atoms in the molecule. Regarding component (B) according to the present invention, the sum of the contents of hydroxyl groups and hydrolyzable groups in the organopolysiloxane resin molecule is in the range of 9 mol% or less, and preferably 7 mol% or less relative to all silicon atoms in the molecule. Note that in component (B), the contents of such hydroxyl groups and hydrolyzable groups can be expressed by converting all these functional groups into hydroxyl groups. In this case, when calculating the mass%, assuming that all these hydrolyzable groups other than these hydroxyl groups in the organopolysiloxane resin molecule are hydroxyl groups (OH), the sum of the contents of the above-mentioned hydroxyl groups and hydrolyzable groups can be expressed such that the content of these hydrolyzable groups converted into hydroxyl groups and the hydroxyl groups in the organopolysiloxane resin molecule is 2.0 mass% or less, 1.6 mass% or less, 1.5 mass% or less, 1.2 mass% or less. These hydroxyl groups or less or hydrolyzable groups are directly bonded to the silicon atoms in the T unit or Q unit, etc. of these siloxane units in the resin structure described below, and are groups obtained by hydrolyzing these silanes or silane derivatives. Therefore, the content of hydroxyl groups or hydrolyzable groups can be reduced in the organopolysiloxane resin synthesized by hydrolysis with a silylating agent such as trimethylsilane.

[0061] In component (B), when the amount of hydroxyl groups or hydrolyzable groups exceeds the above upper limit, the condensation reaction between these organopolysiloxane resin molecules proceeds, thereby promoting the formation of an organopolysiloxane resin structure with a large molecular weight in the cured product. Such an organopolysiloxane resin with a high molecular weight tends to impair the curability of the entire composition, the curability at low temperatures of this composition may be insufficient, and the resulting pressure-sensitive adhesive layer may not have a storage elastic modulus sufficient for practical use.

[0062] In the present invention, component (B) is an organopolysiloxane resin having a three-dimensional structure. Examples thereof include resins composed of R2SiO 2 / 2 units (D units) and RSiO 3 / 2 units (units) (wherein each R independently represents a monovalent organic group) and having a content of hydroxyl groups or hydrolyzable groups within the above range, resins composed only of T units and having a content of hydroxyl groups or hydrolyzable groups within the above range, and resins composed of R3SiO 1 / 2 units (M units) and SiO 4 / 2 units (Q units) and having a content of hydroxyl groups or hydrolyzable groups within the above range. Specifically, it is preferable to use R3SiO 1 / 2A resin (also known as MQ resin) composed of units (M units) and SiO 4 / 2 units (Q units), wherein the sum of the contents of hydroxyl groups and hydrolyzable groups is 0 mol% to 7 mol% with respect to all silicon atoms in the molecule (when all these functional groups are converted to hydroxyl groups, it is preferably in the range of 0.0 mass% to 1.6 mass%).

[0063] This monovalent organic group of R is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, and examples thereof include an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, a benzyl group, a phenethyl group, and a phenylpropyl group. Specifically, 90 mol% or more of R is preferably an alkyl group having 1 to 6 carbon atoms or a phenyl group, and 95 mol% to 100 mol% of R is specifically preferably a methyl group or a phenyl group.

[0064] Preferably, component (B) is an organopolysiloxane resin or a mixture thereof substantially composed of R3SiO 1 / 2 units and SiO 4 / 2 units, wherein R is a monovalent organic group and 90 mol% or more of R is an alkyl group having 1 to 6 carbon atoms or a phenyl group. When component (B) is a resin composed of R3SiO 1 / 2 units (M units) and SiO 4 / 2 units (Q units), the molar ratio of M units to Q units is preferably 0.5 to 2.0. This is because when the molar ratio is less than 0.5, the adhesion to the substrate may decrease, and when the molar ratio is greater than 2.0, the cohesive strength of the material constituting the adhesive layer decreases. In addition, D units and T units can also be included in component (B) to such an extent that the characteristics of the present invention are not impaired. Further, in order to prevent contact failure and the like, low molecular weight siloxane oligomers in these organopolysiloxane resins can be reduced or eliminated.

[0065] In the present invention, the weight average molecular weight (Mw) of the organopolysiloxane resin used as component (B) is not limited, and at least one organopolysiloxane resin having a specific Mw or a mixture of two or more organopolysiloxane resins having different Mws can be used as component (B). From a practical perspective, the range of Mw of component (B) measured by gel permeation chromatography (GPC) based on standard polystyrene is 500 to 20,000 (g / mol), preferably 1,000 to 17,500 (g / mol), and most preferably 2,000 to 16,500 (g / mol).

[0066] [Mass Ratio of Component (B) to Component (A)]

[0067] The organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention characteristically has a mass ratio of component (B) (which is an organopolysiloxane resin) to component (A) (which is a chain-reactive siloxane component) within a specific range. In combination with component (D) as an anchoring additive, the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, 0.5 to 2.5, 0.5 to 1.5, 0.5 to 0.75, 0.75 to 3.5, 0.75 to 3.0, 0.75 to 2.5, 0.75 to 1.5, 1.5 to 3.5, 1.5 to 2.5, or 2.5 to 3.5. Specifically, if (A') a linear organopolysiloxane that does not contain a reactive group having a carbon-carbon double bond in the molecule is optional, the mass ratio of component (B) to component (A) is in the range of 0.9 to 1.8, 0.9 to 1.6, 0.9 to 1.4, 0.9 to 1.2, 1.2 to 1.8, 1.2 to 1.6, 1.2 to 1.4, 1.4 to 1.8, 1.4 to 1.6, or 1.6 to 1.8. In contrast, if the composition contains component (A'), and the mass ratio of component (A) to component (A') is in the range of 95:5 to 60:40, 90:10 to 60:40, 80:20 to 60:40, 70:30 to 60:40, 90:10 to 70:30, or 80:20 to 70:30, the mass ratio of component (B) to component (A) is in the range of 0.9 to 2.4, 0.9 to 2.0, 0.9 to 1.6, or 0.9 to 1.2. In other words, if component (A) and (A') are used in the above mass ratio, even if the mass ratio of component (B) to component (A) is in the range greater than 1.8 to 2.4, the technical effects of the present invention can be achieved.

[0068] If component (A') is not an essential component in the composition according to the present invention, in order to achieve the desired adhesive strength and storage elastic modulus, the mass ratio of component (B) to the sum of component (A) and (A') is in the range of 0.9 to 1.8, and can be in the range of 1.0 to 1.77, 1.2 to 1.6, or 1.4 to 1.5. Note that in the case of the mass ratio of component (B) to component (A), the further use of component (A') is one of the preferred embodiments of the present invention without impairing the technical effects of the present invention.

[0069] In contrast, if component (A') is an essential component in the composition according to the present invention and the mass ratio of component (A) to component (A') is in the range of 95:5 to 40:60, the mass ratio of component (B) to the sum of component (A) and (A') is in the range of 0.9 to 2.4, 0.9 to 2.0, 0.9 to 1.6, or 0.9 to 1.2, and can be in the range of 0.9 to 2.3 or in the range of 1.0 to 2.3.

[0070] In the present invention, component (C) is an organohydrogenpolysiloxane having two or more Si-H bonds per molecule and is a crosslinking agent in the organopolysiloxane composition of the present invention. The molecular structure of component (C) is not particularly limited, examples thereof including linear, partially branched linear, branched, cyclic or organopolysiloxane resin structures, with linear, partially branched linear or organopolysiloxane resin structures being preferred. The bonding position of the silicon-bonded hydrogen atoms is not particularly limited, examples thereof including the molecular ends, side chains or both the molecular ends and side chains. The content of the silicon-bonded hydrogen atoms is from 0.1% by weight to 2.0% by weight, preferably from 0.5% by mass to 1.7% by mass, and more preferably from 0.8% by mass to 1.5% by mass.

[0071] Exemplary silicon-bonded organic groups in component (C) include: alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl and octyl groups; aryl groups, such as phenyl and tolyl groups; aralkyl groups, such as benzyl and phenethyl groups; and haloalkyl groups, such as 3-chloropropyl and 3,3,3-trifluoropropyl groups, with 50% mole or more of the total thereof preferably being an alkyl group having 1 to 8 carbon atoms or a phenyl group. From the viewpoint of ease of manufacture and compatibility with the preferred components (A) and (B) described above, other organic groups are preferably methyl or phenyl groups.

[0072] When component (C) of the present invention is an organohydrogenpolysiloxane as an organopolysiloxane resin, examples thereof include siloxane units represented by the general formula: R'3SiO 1 / 2 siloxane units represented by the general formula R'2HSiO 1 / 2 and an organopolysiloxane copolymer composed of siloxane units represented by the formula: SiO 4 / 2 ; an organopolysiloxane copolymer composed of siloxane units represented by the general formula: R'2HSiO 1 / 2 and siloxane units represented by the formula: SiO 4 / 2 ; an organopolysiloxane copolymer composed of siloxane units represented by the general formula: R'2HSiO 1 / 2 and siloxane units represented by the formula: R'SiO 3 / 2 ; an organopolysiloxane copolymer composed of siloxane units represented by the general formula: R'HSiO 2 / 2 siloxane units represented by the general formula: R'SiO 3 / 2 or siloxane units represented by the formula: HSiO 3 / 2An organopolysiloxane copolymer composed of the represented siloxane units; and a mixture of two or more types of these organopolysiloxanes. Note that in these formulas, R' is an alkyl group, an aryl group, an aralkyl group, or a haloalkyl group having 1 to 8 carbon atoms, and examples thereof are the same as those described above.

[0073] Specific examples of component (C) include tris(dimethylhydroxysilyloxy)methylsilane, tetrakis(dimethylhydroxysilyloxy)silane, methylhydrogenpolysiloxane capped with trimethylsilyloxy groups at both ends, dimethylsiloxane / methylhydrogensiloxane copolymer capped with trimethylsilyloxy groups at both ends, dimethylsiloxane / methylhydrogensiloxane copolymer capped with dimethylhydroxysilyloxy groups at both ends, cyclic methylhydrogen oligosiloxane, cyclic methylhydrogensiloxane / dimethylsiloxane copolymer, methylhydrogensiloxane / diphenylsiloxane copolymer capped with trimethylsilyloxy groups at both ends, methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer capped with trimethylsilyloxy groups at both ends, hydrolysis condensate of trimethylsilane, copolymer composed of (CH3)2HSiO 1 / 2 units and SiO 4 / 2 units, copolymer composed of (CH3)2HSiO 1 / 2 units, SiO 4 / 2 units and (C6H5)SiO 3 / 2 units, copolymer composed of (CH3)2HSiO 1 / 2 units and CH3SiO 3 / 2 units, and a mixture of two or more types of them.

[0074] In the case of a linear structure, specifically, the methylhydrogenpolysiloxane represented by the molecular structural formula: R T Me2SiO(Me2SiO) q (HMeSiO) r SiMe2R T is preferred. (Wherein, Me is a methyl group, R

[0075] is a methyl group or a hydrogen atom, and q and r are numbers satisfying 0.3 ≤ r / (q + r) ≤ 1 and 5 ≤ (q + r) ≤ 200). Note that two or more different types of component (C) can be used in combination. T is a methyl group or a hydrogen atom, and q and r are numbers satisfying 0.3 ≤ r / (q + r) ≤ 1 and 5 ≤ (q + r) ≤ 200). Note that two or more different types of component (C) can be used in combination.

[0076] Similarly, the following organosiloxanes can be given as examples. Note that in these formulas, Me and Ph represent a methyl group and a phenyl group, respectively, m is an integer from 1 to 100, n is an integer from 1 to 50, and b, c, d, and e are each positive numbers, and the sum of b, c, d, and e in one molecule is 1.

[0077] HMe2SiO(Ph2SiO) m SiMe2H

[0078] HMePhSiO(Ph2SiO) m SiMePhH

[0079] HMePhSiO(Ph2SiO) m (MePhSiO) n SiMePhH

[0080] HMePhSiO(Ph2SiO) m (Me2SiO) n SiMePhH

[0081] (HMe2SiO 1 / 2 ) b (PhSiO 3 / 2 ) c

[0082] (HMePhSiO 1 / 2 ) b (PhSiO 3 / 2 ) c

[0083] (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (PhSiO 3 / 2 ) d

[0084] (HMe2SiO 1 / 2 ) b (Ph2SiO 2 / 2 ) c (PhSiO 3 / 2 ) d

[0085] (HMePhSiO 1 / 2 ) b (Ph2SiO 2 / 2 ) c (PhSiO 3 / 2 ) d

[0086] (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (Ph2SiO 2 / 2 ) d (PhSiO3 / 2 ) e 。

[0087] [SiH / Vi Ratio]

[0088] The composition according to the present invention is curable by hydrosilylation reaction, and the amount of component (C) is not particularly limited as long as the composition can be sufficiently cured by hydrosilylation reaction. However, relative to the sum of the amounts (number of moles) of the alkenyl groups in component (A) and the alkenyl groups in component (B) in the composition, the amount of hydrogen atoms bonded to silicon atoms (SiH) in component (C), i.e., the molar ratio, is preferably in the range of 1.0 to 100, and can be in the range of 5.0 to 60, in the range of 10 to 50, or in the range of 20 to 50.

[0089] In contrast, in order to improve the adhesion to substrates such as glass, the number of SiH groups per molecule can be designed to be 3 or more and 5 or more, preferably more than 10, and more preferably 20 or more. For example, relative to the sum of the amounts (number of moles) of the alkenyl groups in component (A) and the alkenyl groups in component (B) in the composition, the amount of hydrogen atoms bonded to silicon atoms (SiH) in component (C) can be designed to be in the range of 10 to 60 and in the range of 10 to 50. When the amount of these SiH groups is below the above lower limit, the technical effect of improving the adhesion to the substrate may not be achieved. In contrast, when the amount of these SiH groups exceeds the above upper limit, the amount of unreacted residual curing agent becomes large, which may have an adverse effect on the cured physical properties such as the brittleness of the cured product, or may cause problems such as gas generation. However, even when the SiH / Vi ratio of the composition is outside the above range, a pressure-sensitive adhesive layer sufficient for practical use can be formed.

[0090] [Hydrosilylation Reaction Catalyst]: Component (D)

[0091] The organopolysiloxane composition of the present invention contains a hydrosilylation reaction catalyst. Examples of the hydrosilylation reaction catalyst include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts, among which platinum-based catalysts are preferred because they significantly promote the curing of the composition of the present invention. Examples of the platinum-based catalyst include platinum fine powder, chloroplatinic acid, an alcoholic solution of chloroplatinic acid, a platinum-vinylsiloxane complex, a platinum-olefin complex, and a platinum-carbonyl complex, among which the platinum-vinylsiloxane complex is specifically preferred. Examples of the vinylsiloxane include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and vinylsiloxanes in which some of the methyl groups of these vinylsiloxanes are replaced by groups selected from the group consisting of nitrile, amide, dioxolane, sulfolane, ethyl group, phenyl group, etc., and vinylsiloxanes in which these vinyl groups of these vinylsiloxanes are replaced by allyl groups, hexenyl groups, etc. Specifically, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because the platinum-vinylsiloxane complex has good stability. As the catalyst for promoting the hydrosilylation reaction, a non-platinum-based metal catalyst such as iron, ruthenium, iron / cobalt, etc. can be used.

[0092] Although the content of the hydrosilylation reaction catalyst in the present invention is not specifically limited herein, the amount of the platinum-based metal is in the range of 0.1 to 200 ppm, and can be in the range of 0.1 to 150 ppm, in the range of 0.1 to 100 ppm, or in the range of 0.1 to 60 ppm, relative to the total amount of solids in the composition. Here, the platinum-based metal is a Group VIII metal element composed of platinum, rhodium, palladium, ruthenium, and iridium; however, in actual use, the content of the platinum metal other than the ligand of the hydrosilylation catalyst is preferably within the range described above. Note that the solid content is the component that forms the cured layer (mainly the main agent, adhesion-imparting component, crosslinking agent, catalyst, and other non-volatile components) when the organopolysiloxane composition of the present invention undergoes a curing reaction, and does not include volatile components such as solvents that volatilize during thermal curing.

[0093] When the content of the platinum-based metal in the organopolysiloxane composition according to the present invention is 60 ppm or less, 50 ppm or less, 40 ppm or less, 30 ppm or less, 25 ppm or less, or 20 ppm or less, this can inhibit the discoloration or coloring of the transparent pressure-sensitive adhesive layer, specifically after curing or when heated or exposed to high-energy rays such as UV. At the same time, from the perspective of the curability of the organopolysiloxane composition, the content of the platinum-based metal is not less than 0.1 ppm because when the content is lower than the lower limit, this may cause curing defects.

[0094] In the present invention, component (E) is a curing retarder (= curing inhibitor), and is blended to inhibit the crosslinking reaction between the alkenyl groups in the composition and these SiH groups in component (C) in order to extend the service life at normal temperature and improve the storage stability. Therefore, in actual use, this component (E) can be added to the organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention.

[0095] Specific examples of component (E) include acetylenic compounds, ene-yne compounds, organic nitrogen compounds, organic phosphorus compounds, and oxime compounds. Specific examples include: acetylenic alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 1-ethynyl-1-cyclohexanol, phenylbutanol, etc.; ene-yne compounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-1-hexen-3-yne, etc.; methylvinylcyclosiloxanes such as 2-ethynyl-4-methyl-2-pentene, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, etc., and benzotriazoles.

[0096] From the perspective of the curing behavior of the composition, the organopolysiloxane composition for forming a pressure-sensitive adhesive layer of the present invention is preferably curable at 80°C to 200°C, and the viscosity increases within 1.5 times after 8 hours at room temperature after the composition is prepared. From the perspectives of workability, pot life, and properties after curing, it is important to inhibit thickening, and a large amount of component (C) is contained, where even if the content of the platinum-based metal is optionally low, the curability can be ensured by curing at a high temperature of at least a specific temperature (80°C to 200°C). Note that such a composition can be achieved by selecting a suitable combination and blending amount of the above-described respective components, the hydrosilylation catalyst, and component (E).

[0097] In addition to the preferred components (A) and (B) described above, the organopolysiloxane composition of the present invention may also contain an organic solvent as a solvent. The type and blending amount of the organic solvent can be adjusted in consideration of coating workability and the like. Exemplary organic solvents include: aromatic hydrocarbon-based solvents such as toluene, xylene, and benzene; aliphatic hydrocarbon-based solvents such as heptane, hexane, octane, and isoparaffin; ester-based solvents such as ethyl acetate and isobutyl acetate; ether-based solvents such as diisopropyl ether and 1,4-dioxane; chlorinated aliphatic hydrocarbon-based solvents such as trichloroethylene, perchloroethylene, and dichloromethane; and solvent volatile oils; among which two or more types can be combined according to the wettability of the sheet substrate and the like. The blending amount of the organic solvent is preferably an amount such that the mixture of components (A) to (C) can be uniformly applied to the surface of the sheet substrate. For example, the blending amount can be 5 to 3000 parts by mass per 100 parts by mass of the total amount of components (A), (B), and (C).

[0098] The organopolysiloxane composition of the present invention may optionally contain components other than those described above to such an extent that the technical effects of the present invention are not impaired. For example, the composition may contain: an adhesion promoter; non-reactive organopolysiloxanes such as polydimethylsiloxane or polydimethyldiphenylsiloxane; antioxidants such as phenolic, quinone-type, amine-type, phosphorus-type, phosphite-type, sulfur-type, or thioether-type antioxidants; flame retardants such as phosphate-type, halogen-type, phosphorus-type, antimony-type flame retardants; and one or more types of antistatic agents composed of cationic surfactants, anionic surfactants, nonionic surfactants, etc. Note that in addition to these components, pigments, dyes, inorganic fine particles (e.g., reinforcing fillers, dielectric fillers, conductive fillers, heat conductive fillers), etc. may also be optionally blended.

[0099] [Linear / Chain-like Organopolysiloxane in which (A') Molecule does not Contain Reactive Groups with Carbon-carbon Double Bonds]

[0100] The organopolysiloxane composition according to the present invention may contain a non-reactive organopolysiloxane that does not contain a reactive group having a carbon-carbon double bond, such as an alkenyl group, an acryloyl group, or a methacryloyl group, such as polydimethylsiloxane or polydimethyldiphenylsiloxane. As a result, the loss factor (tanδ), storage elastic modulus (G'), loss modulus (G''), and adhesiveness of the pressure-sensitive adhesive layer can be improved. For example, polydimethylsiloxane having a hydroxyl group at the terminal or polydimethylsiloxane or polydimethyldiphenylsiloxane having a trimethylsilyloxy group at the terminal can be used to increase the loss factor of the pressure-sensitive adhesive layer, and such compositions are included within the scope of the present invention.

[0101] Specifically, if the mass ratio of component (B) to the sum of components (A) and (A') is in the range of 0.9 to 2.4, the mass ratio of component (A) to component (A') must be in the range of 95:5 to 40:60, where the mass ratio of component (A) to component (A') is preferably in the range of 90:10 to 40:60.

[0102] [Optional Tetraalkoxysilane or Prepolymer of the Tetraalkoxysilane as an Anchoring Additive]

[0103] To increase or improve the adhesion, in the present invention, at least one tetraalkoxysilane or a prepolymer of the tetraalkoxysilane can be formulated as an anchoring additive for the silicone-based PSA composition. Although the rheological / viscoelastic properties in the cured silicone PSA layer are generally determined by its crosslinked polymer structure (including polymer chain length), resin structure (including silicone-resin units and Mw), and the molar ratio therein, resulting in a trade-off relationship between a lower Tg or modulus and a higher adhesion, by using a tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as an anchoring additive, only the adhesion can be increased without affecting the lower Tg or modulus properties in the cured silicone PSA layer.

[0104] In a preferred embodiment of the present invention, the adhesion of a pressure-sensitive adhesive layer with a thickness of 50 μm obtained by curing the composition and measured by the 180° peel test method according to JIS Z 0237 at a tensile speed of 300 mm / min on a glass substrate or the like is more than 20% greater, preferably 30% to 80% greater, than the adhesion of a pressure-sensitive adhesive layer obtained from the same composition but without a tetraalkoxysilane as an anchoring additive.

[0105] To achieve the said technical benefits, examples of the tetraalkoxysilane are tetramethoxysilane, tetraethoxysilane, or a mixture thereof. Using other silanes such as glycidoxypropyltrimethoxysilane or vinyltrimethoxysilane instead of the tetraalkoxysilane may not improve or enhance the adhesion without affecting its rheological / viscoelastic properties for the silicone-based pressure-sensitive adhesive layer. Further, to achieve a sufficient improvement in the adhesion, assuming the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, based on the total mass of components (A) to (C), the amount of the tetraalkoxysilane is in the range of 0.1% by mass to 9.0% by mass, preferably in the range of 0.2% by mass to 7.0% by mass, more preferably in the range of 0.5% by mass to 5.0% by mass. When the amount of the tetraalkoxysilane is below the above lower limit, the technical effect of improving the adhesion to the substrate may not be achieved sufficiently. In contrast, when the amount of the tetraalkoxysilane exceeds the above upper limit, the excessive tetraalkoxysilane or the prepolymer of the tetraalkoxysilane may have an adverse effect on the cured physical properties.

[0106] The method for preparing the composition for forming the silicone-based PSA is not particularly limited and is carried out by uniformly mixing the corresponding components. A solvent can be added as needed, and the composition can be prepared by mixing at a temperature of 0°C to 200°C using a known stirrer or kneader.

[0107] [Forming an Adhesive Layer using the Composition for Forming a Silicone-based PSA]

[0108] The aforementioned composition for forming the silicone-based PSA forms a cured adhesive layer when applied to a substrate and forms a cured product by heating under temperature conditions of 80°C to 200°C, preferably under temperature conditions of 90°C to 190°C. Examples of the application method include gravure coating, offset coating, offset gravure, roll coating, reverse roll coating, air knife coating, curtain coating, and comma coating.

[0109] This cured adhesive layer from the composition for forming the silicone-based PSA is disposed between these functional layers to bond / assemble these layers in the electronic article of the present invention.

[0110] [Properties Related to the Transparency, Hue or Coloring and Discoloration of the Pressure-sensitive Adhesive Layer]

[0111] The interlayer adhesive layer applied to the present invention, preferably the aforementioned silicone-based PSA layer, can be a transparent or opaque assembly layer. That is, in the interlayer adhesive layer of the present invention, the transparent property is an optional property and depends on the position of the interlayer adhesive layer in the electronic device. When the interlayer adhesive layer is disposed above the panel unit and close to its cover glass or other transparent cover unit, it should be a "transparent" interlayer adhesive layer. On the other hand, when the interlayer adhesive layer is located at the bottom of the panel unit, there is no requirement for the transparency property of the interlayer adhesive layer. Nevertheless, the interlayer adhesive layer of the present invention can be substantially transparent, translucent, or opaque, such that its transparency can be designed according to the application of the interlayer adhesive layer. For example, as the interlayer pressure-sensitive adhesive layer applied to the display device of the present invention, the film-shaped cured product with a thickness of 1 to 1000 μm obtained by curing the composition for forming the silicone-based PSA is preferably visually transparent and preferably does not contain coloring additives such as carbon black. Note that in the case of being visually transparent, or more objectively, when the value of air is 100%, the light transmittance of the pressure-sensitive adhesive layer for the display device formed by the cured layer with a thickness of 100 μm is 80% or higher at a wavelength of 450 nm, and suitably 90% or higher, and can be designed to be 95% or higher. In contrast, in the adhesion of electrical or electronic parts where light transmittance is not required, a translucent to opaque pressure-sensitive adhesive layer can be used, and filler components or additives that impair colorability or light transmittance can be used according to the required characteristics other than light transmittance.

[0112] The interlayer adhesive layer can be designed by optionally reducing the content of the platinum-based metal in the cured layer so that, in addition to the above transparency, the cured product is not colored. Specifically, after curing a cured layer with a thickness of 100 μm obtained by curing the organopolysiloxane composition of the present invention, the b* value measured immediately using the L*a*b* color system specified in JIS Z 8729 can be designed to be not greater than 0.15 and not greater than 0.10. Having such a b* value means that the cured layer is substantially transparent and not yellow.

[0113] Even when the cured layer of the present invention is exposed to high temperature or high energy beam such as UV rays for a long time, it can be designed so that its hue does not change significantly and specifically the problem of yellowing does not occur. Specifically, even when any of the following evaluations is carried out, after evaluating a cured layer with a thickness of 100 μm obtained by curing the organopolysiloxane composition of the present invention, the change (Δb*) in the b* value measured immediately using the L*a*b* color system specified in JIS Z 8729 can be designed to be not greater than 0.20 and preferably not greater than 0.15. Note that Δb* is the absolute value of the numerical change.

[0114] (1) Thermal aging evaluation: Aging the cured layer at 105 °C for 300 hours.

[0115] (2) High energy beam irradiation: Using a mercury lamp with an intensity of 12 mW / cm at 365 nm 2 and an intensity of 3.5 mW / cm at 254 nm 2 (e.g., optical module X manufactured by Ushio Electric Co., Ltd., etc.), irradiating a sample of the cured layer with UV light at room temperature for 75 hours.

[0116] [Used as an Interlayer Pressure-sensitive Adhesive Layer Applied to the Electronic Article]

[0117] To improve the adhesion to the adherend, surface treatment such as primer treatment, corona treatment, etching treatment, or plasma treatment can be carried out on the surface of the adhesive layer or the substrate. However, since the adhesive layer obtained by curing the composition for forming a silicone-based PSA has excellent adhesion to the substrate of a display device, etc., as described above, if necessary, these steps can be added to further improve the adhesion to the adherend, and higher production efficiency can be achieved by eliminating these steps.

[0118] The composition for forming a silicone-based PSA can be cured as follows: apply the composition to a release liner, heat it under the temperature conditions described above, and then, after peeling off the release liner and attaching the composition to a film substrate, a strip substrate, or a sheet substrate (hereinafter referred to as "film substrate"), or after applying it to a film substrate, cure it by heating under the temperature conditions described above, thereby forming a pressure-sensitive adhesive layer on the surface of the substrate. In the construction of electronic products and the use of laminated touchscreens or flat panel displays, a laminate provided with a cured layer (specifically, a film pressure-sensitive adhesive layer obtained by curing the composition for forming a silicone-based PSA on these film substrates) is used to bond or assemble functional layers. As described above, the adhesive layer is applied as a single coating having both the functions of an assembly / bonding layer and a damping / shock-absorbing layer, and the manufacturing method of the electronic product of the present invention can be a simplified method that does not require a multi-step lamination / coating process to construct its interlayer damping or shock-absorbing layer.

[0119] The coating amount of the composition for forming a silicone-based PSA can be designed to a desired thickness according to applications such as display devices. As an example, the thickness of the pressure-sensitive adhesive layer after curing can be 1 μm to 1000 μm, 5 μm to 900 μm, or 10 μm to 800 μm; however, it is not limited thereto.

[0120] According to the required properties, the pressure-sensitive adhesive layer according to the present invention can be a single layer or a multi-layer structure obtained by laminating two or more pressure-sensitive adhesive layers. A multi-layer pressure-sensitive adhesive layer can be formed by bonding pressure-sensitive adhesive films (which are formed film by film) thereto, or the steps of applying and curing the composition for forming a silicone-based PSA can be performed multiple times on a film substrate (including a release layer), etc.

[0121] In addition to the functions of bonding or adhesion between components and the damping / shock-absorbing layer function, the pressure-sensitive adhesive layer can also serve as other functional layers selected from dielectric layers, conductive layers, heat dissipation layers, insulating layers, reinforcing layers, etc.

[0122] In the case where the adhesive layer obtained by curing the composition forming the silicone-based PSA is a pressure-sensitive adhesive layer, specifically a pressure-sensitive adhesive layer, preferably the cured layer is treated as a laminated film that is peelably adhered to a film substrate provided with a release layer having release coating ability. The release layer may also be referred to as a release liner, separator, release layer, or release coating, and may preferably be a release layer having release coating ability, such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or a fluorosilicone-based release agent, or the release layer may be formed by forming physically fine irregularities on the surface of the substrate so as not to easily adhere to the substrate itself of the resin sheet for the pressure-sensitive adhesive layer of the present invention. Specifically, in the laminate according to the present invention, a release layer obtained by curing a fluorosilicone release agent is preferably used as the release layer.

[0123] Preferably, the interlayer adhesive layer, which is the aforementioned silicone-based PSA layer, has the aforementioned viscoelastic characteristic properties and the adhesive strength as described above in its tanδ curve measurement, such that it is useful as an elastic adhesive member as a component of various types of electronic devices or electrical apparatuses. Specifically, it is useful as a component for electronic materials, components for display devices, and components for transducers (including sensors, speakers, actuators, and generators), where suitable applications of the cured product are components for electronic parts or display devices. The cured product according to the present invention may be transparent or opaque. Specifically, a film-like cured product, specifically a substantially transparent pressure-sensitive adhesive film, is suitable as a component for a display panel or a display, and is particularly useful in the so-called touch panel application where the device, specifically an electronic device, can be operated by touching the screen with a fingertip or the like. In addition, the opaque elastic adhesive layer does not need to have transparency, which makes it particularly applicable to film-like or sheet-like components used in sensors, speakers, actuators, etc., which require the adhesive layer itself to have constant elasticity or flexibility.

[0124] Furthermore, the interlayer adhesive layer according to the present invention can achieve pressure-sensitive adhesive characteristics comparable to those of a conventional silicone pressure-sensitive adhesive layer, can improve the adhesion to substrates such as display devices, and also provides impact resistance to the electronic article as a damping / shock-absorbing layer in the electronic article of the present invention.

[0125] Examples

[0126] These examples are intended to illustrate the present invention to those skilled in the art and are not to be construed as limiting the scope of the present invention described in the claims. The materials in Table 1 are used in these examples. Note that the viscosity and plasticity values of the respective components in the present invention are measured at room temperature by the following methods.

[0127] (Viscosity)

[0128] The viscosity (mPa·s) is the value measured using a rotational viscometer in accordance with JIS K7117-1, while the kinematic viscosity (square millimeters per second) is the value measured using an Ubbelohde viscometer in accordance with JIS Z8803.

[0129] (Plasticity Value)

[0130] The plasticity value is expressed as the value measured according to the method specified in JIS K 6249 (when a 4.2 g spherical sample is subjected to a 1 kgf load for 3 minutes at 25°C, the thickness read to the nearest 1 / 100 mm is multiplied by 100).

[0131] Table 1. Components of the Composition for Forming a Silicone-based PSA

[0132]

[0133] [Preparation of Curable Organopolysiloxane Composition]

[0134] These curable organopolysiloxane compositions described in the respective examples and comparative examples were prepared using these components shown in Table 1. Additionally, the formulations of the working examples and comparative examples are summarized in Table 2.

[0135] [Measurement of Molecular Weight of Organopolysiloxane Component]

[0136] Using gel permeation chromatography (GPC) available from Waters Corporation, tetrahydrofuran (THF) was used as the solvent, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of organopolysiloxane components such as organopolysiloxane resins were determined relative to standard polystyrene.

[0137] [Viscoelasticity: Dynamic Mechanical Analysis: tanδ]

[0138] Each composition was applied to a release liner coated with a fluorosilicone release coating, with a thickness of approximately 120 μm after curing, and then cured at 70°C for 10 minutes and at 150°C for 10 minutes. Five or more of these pressure-sensitive adhesive films were laminated to obtain a film sample with a thickness of 500 μm - 1200 μm, with both of its surfaces sandwiched between release liners. The film was cut into circles with a diameter of 8 mm, and dynamic mechanical analysis was performed using a parallel plate measurement system with a TA model DHR-2 rheometer having a mechanical cooling system. The measurement conditions were in the range of -70°C to 200°C at a frequency of 1 Hz and a temperature ramp of 3°C per minute to provide the storage modulus G', loss modulus G'', and tanδ, from which the tanδ peak temperature (Tg), the tanδ value at this peak, and the temperature range where the tanδ value exceeds 0.5 were recorded.

[0139] Example 1

[0140] 21.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 3.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 53.5 parts by weight of MQ silicone resin B-3, 47.0 parts by weight of toluene, 0.44 parts by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, 0.05 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.12 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 0.97 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in components C-1 and C-2 to the amount of alkenyl groups in components A-1 and A-2 was 36.2, and the platinum metal content was 80.0 ppm relative to the solid content.

[0141] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0142] Example 2

[0143] 21.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 53.5 parts by weight of MQ silicone resin B-3, 40.0 parts by weight of toluene, 0.44 parts by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, and 0.10 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 0.92 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-1 to the amount of alkenyl groups in component A-1 was 33.1, and the platinum metal content was 80.1 ppm relative to the solid content.

[0144] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0145] Example 3

[0146] 21.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 71.5 parts by weight of MQ silicone resin B-3, 45.4 parts by weight of toluene, 0.44 parts by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, and 0.10 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Thereafter, 1.12 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-1 to the amount of alkenyl groups in component A-1 was 33.1, and the platinum metal content was 79.9 ppm relative to the solid content.

[0147] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0148] Example 4

[0149] 25.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 45.7 parts by weight of MQ silicone resin B-2, 2.4 parts by weight of MQ silicone resin B-3, 49.1 parts by weight of toluene, 0.28 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy at both ends, 0.01 parts by weight of curing inhibitor E-1, and 0.21 parts by weight of curing inhibitor E-2 were thoroughly mixed at room temperature. Thereafter, 0.91 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-2 to the amount of alkenyl groups in component A-2 was 40.2, and the platinum metal content was 81.7 ppm relative to the solid content.

[0150] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0151] Example 5

[0152] 27.4 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 45.7 parts by weight of MQ silicone resin B-2, 2.4 parts by weight of MQ silicone resin B-3, 54.7 parts by weight of toluene, 0.33 part by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, 0.02 part by weight of curing inhibitor E-1, and 0.21 part by weight of curing inhibitor E-2 were thoroughly mixed at room temperature. Thereafter, 0.95 part by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-2 to the amount of alkenyl groups in component A-2 was 43.3, and the platinum metal content was 81.5 ppm relative to the solid content.

[0153] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0154] Example 6

[0155] 16.3 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 7.0 parts by weight of non-functional (trimethylsilyl-capped) polydimethylsiloxane gum A', 45.0 parts by weight of MQ silicone resin B-3, 36.8 parts by weight of toluene, 0.40 part by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, and 0.20 part by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Thereafter, 0.36 part by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-1 to the amount of alkenyl groups in component A-1 was 38.7, and the platinum metal content was 33.6 ppm relative to the solid content.

[0156] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0157] Example 7

[0158] 14.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 9.3 parts by weight of non-functional (trimethylsilyl-terminated) polydimethylsiloxane gum A', 45.0 parts by weight of MQ silicone resin B-3, 36.8 parts by weight of toluene, 0.40 part by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, and 0.20 part by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 0.36 part by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-1 to the amount of alkenyl groups in component A-1 was 45.2, and the platinum metal content was 33.6 ppm relative to the solid content.

[0159] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0160] [Results of the Ball Drop Test of the Laminate using the Interlayer Adhesive Layer Obtained by Example 7, for Example]

[0161] A pressure-sensitive adhesive film with a thickness of 120 μm and dimensions of 149 mm × 69.5 mm was laminated between a stainless steel sheet with dimensions of 449 mm × 430 mm × 20 mm and a glass sheet with dimensions of 149 mm × 69.5 mm × 0.342 mm using a plastic manual roller. The laminate was placed horizontally with the stainless steel sheet at the bottom and the glass sheet at the top, and then a stainless steel ball with a diameter of 11.11 mm and a weight of 5.6 g was dropped from a height of 300 mm onto the glass surface. If the glass sheet broke or did not break, the impact resistance provided by the pressure-sensitive adhesive film to the laminate was observed. The results are shown in Figure 1 in.

[0162] Example 8

[0163] 11.7 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 11.7 parts by weight of non-functional (trimethylsilyl-terminated) polydimethylsiloxane gum A', 45.0 parts by weight of MQ silicone resin B-3, 36.8 parts by weight of toluene, 0.40 part by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, and 0.20 part by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 0.36 part by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-1 to the amount of alkenyl groups in component A-1 was 54.2, and the platinum metal content was 33.6 ppm relative to the solid content.

[0164] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0165] Comparative Example 1

[0166] 23.3 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 56.8 parts by weight of MQ silicone resin B-1, 2.9 parts by weight of MQ silicone resin B-3, 30.0 parts by weight of toluene, 0.25 part by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.15 part by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 1.08 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-2 to the amount of alkenyl groups in component A-1 was 35.6, and the platinum metal content was 78.7 ppm relative to the solid content.

[0167] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0168] [Results of the Ball Drop Test of the Laminate using the Interlayer Adhesive Layer Obtained by Comparative Example 1, for Example]

[0169] A pressure-sensitive adhesive film with a thickness of 120 μm and dimensions of 149 mm × 69.5 mm was laminated between a stainless steel sheet with dimensions of 449 mm × 430 mm × 20 mm and a glass sheet with dimensions of 149 mm × 69.5 mm × 0.342 mm using a plastic manual roller. The laminate was placed horizontally with the stainless steel sheet at the bottom and the glass sheet at the top, and then a stainless steel ball with a diameter of 11.11 mm and a weight of 5.6 g was dropped from a height of 300 mm onto the glass surface. If the glass sheet was broken or not broken, the impact resistance provided by the pressure-sensitive adhesive film to the laminate was observed. The results are shown in Figure 2 in.

[0170] Comparative Example 2

[0171] 23.3 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 6.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 56.8 parts by weight of MQ silicone resin B-1, 2.9 parts by weight of MQ silicone resin B-3, 44.0 parts by weight of toluene, 0.32 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.18 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 1.17 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the SiH groups in component C-2 to the alkenyl groups in components A-1 and A-2 was 36.8, and the platinum metal content was 78.6 ppm relative to the solid content.

[0172] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0173] Comparative Example 3

[0174] 23.3 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 13.5 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 56.8 parts by weight of MQ silicone resin B-1, 2.9 parts by weight of MQ silicone resin B-3, 61.4 parts by weight of toluene, 0.42 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.22 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 1.28 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the SiH groups in component C-2 to the alkenyl groups in components A-1 and A-2 was 39.0, and the platinum metal content was 78.5 ppm relative to the solid content.

[0175] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0176] Comparative Example 4

[0177] 23.3 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 19.5 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 56.8 parts by weight of MQ silicone resin B-1, 2.9 parts by weight of MQ silicone resin B-3, 75.4 parts by weight of toluene, 0.44 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.25 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 1.38 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-2 to the amount of alkenyl groups in components A-1 and A-2 was 35.4, and the platinum metal content was 78.5 ppm relative to the solid content.

[0178] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0179] Comparative Example 5

[0180] 21.0 parts by weight of vinyl-functional polydimethylsiloxane gum A-1, 91.5 parts by weight of MQ silicone resin B-3, 51.4 parts by weight of toluene, 0.44 parts by weight of dimethylsiloxane / methylhydrogensiloxane copolymer C-1 capped with trimethylsilyloxy groups at both ends, and 0.10 parts by weight of curing inhibitor E-1 were thoroughly mixed at room temperature. Then, 1.33 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-1 to the amount of alkenyl groups in component A-1 was 33.1, and the platinum metal content was 79.7 ppm relative to the solid content.

[0181] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0182] Comparative Example 6

[0183] 22.6 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 70.7 parts by weight of MQ silicone resin B-2, 2.4 parts by weight of MQ silicone resin B-3, 52.0 parts by weight of toluene, 0.23 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.21 parts by weight of curing inhibitor E-2 were thoroughly mixed at room temperature. Then, 1.13 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-2 to the amount of alkenyl groups in component A-2 was 36.5, and the platinum metal content was 81.2 ppm relative to the solid content.

[0184] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0185] Comparative Example 7

[0186] 22.6 parts by weight of vinyl-functional polydimethylsiloxane gum A-2, 55.7 parts by weight of MQ silicone resin B-2, 2.4 parts by weight of MQ silicone resin B-3, 46.9 parts by weight of toluene, 0.23 parts by weight of methylhydrogensiloxane polymer C-2 capped with trimethylsilyloxy groups at both ends, and 0.21 parts by weight of curing inhibitor E-2 were thoroughly mixed at room temperature. Then, 0.98 parts by weight of a platinum-based hydrosilylation reaction catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component C-2 to the amount of alkenyl groups in component A-2 was 36.5, and the platinum metal content was 81.6 ppm relative to the solid content.

[0187] The composition was cured by the above method, and then the viscoelasticity was measured by the above method, and the evaluation results are shown in Table 3.

[0188] Table 2.

[0189]

[0190]

[0191] Table 3.

[0192]

[0193]

[0194] As shown in Table 3, the compositions for forming the silicone-based PSA layer according to Examples 1 to 8 provide an interlayer adhesive layer, the temperature at the tanδ peak of which is lower than 35 °C, and the tanδ value at the peak is greater than 1.0. Electronic articles using the interlayer adhesive layer obtained from these compositions according to Examples 1 to 8 in their construction are expected to be sufficiently adhered / assembled between their functional layers to achieve better damping / vibration damping properties in the interlayer adhesive layer. Specifically, as in the case of performing the ball drop test on the laminate using Example 7 Figure 1 as shown, no cracks or damages were observed in the laminate having the interlayer adhesive layer related to the present invention.

[0195] In contrast, in Comparative Examples 1 to 8, an interlayer adhesive layer satisfying the properties required by the present invention was not obtained. Electronic articles using the interlayer adhesive layer obtained from these compositions according to Comparative Examples 1 to 7 in their construction are expected to have insufficient damping / vibration damping properties in the interlayer adhesive layer. As in the case of performing the ball drop test on the laminate using Comparative Example 1 Figure 2 as shown, the ball drop resulted in large and severe cracks being observed in the laminate.

Claims

1. An electronic article having an interlayer adhesive layer, wherein the temperature at the tanδ peak of the interlayer adhesive layer is lower than 35°C and the tanδ value at the peak is greater than 1.0, as measured at 1 Hz using a parallel plate measurement system by a dynamic mechanical analysis rheometer.

2. The electronic article according to claim 1, wherein the width of the tanδ peak of the interlayer adhesive layer, as defined by the absolute value of the temperature range in which the tanδ value exceeds 0.5, is narrower than 90°C.

3. The electronic article according to claim 1, wherein the tanδ curve of the interlayer adhesive layer, as measured at 1 Hz using a parallel plate measurement system by a dynamic mechanical analysis rheometer, satisfies the following conditions: i) the temperature at the tanδ peak is in the range of -50°C to 25°C; and ii) the width range of the tanδ peak, as defined by the absolute value of the temperature range in which the tanδ value exceeds 0.5, is from 50°C to less than 90°C.

4. The electronic article according to any one of claims 1 to 3, wherein the interlayer adhesive layer is a pressure-sensitive silicone adhesive layer obtained by curing a composition that forms a silicone-based pressure-sensitive adhesive, the composition comprising components (A) to (D): (A) a linear organopolysiloxane having an average of more than 1 alkenyl group per molecule; (B) an organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 9 mol% or less relative to all silicon atoms in the molecule; (C) an organohydrogenpolysiloxane having at least two Si-H bonds per molecule; and (D) a hydrosilylation reaction catalyst.

5. The electronic article according to claim 4, wherein at least a part of the component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25°C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249, and the content of the vinyl (CH2=CH-) moiety of the alkenyl group is in the range of 0.005 mass% to 0.400 mass%; Component (B) is an organopolysiloxane resin (B1) consisting essentially of R3SiO 1 / 2 units and SiO 4 / 2 units, or a mixture thereof, where R is a monovalent organic group and 90 mol% or more of the R is an alkyl group or a phenyl group having 1 to 6 carbon atoms; the component (C) is present in an amount such that the molar ratio of the amount of SiH groups in the component (C) to the total amount of alkenyl groups in the components (A) and (B) is from 1 to 100; and the component (D) is a platinum-based catalyst and is present in an amount such that the content of platinum-based metal in the solid content of the composition is in the range of 0.1 ppm to 200 ppm in the composition for forming the silicone-based pressure-sensitive adhesive without a solvent.

6. The electronic article according to claim 4, wherein the component (C) is present in an amount such that the molar ratio of the amount of SiH groups in the component (C) to the total amount of alkenyl groups in the components (A) and (B) is from 10 to 60.

7. The electronic article according to claim 4, wherein the composition for forming the silicone-based pressure-sensitive adhesive further comprises (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-reactive group in the molecule.

8. The electronic article according to any one of claims 1 to 3, wherein the interlayer adhesive layer is disposed between two functional layers to bond or assemble the two functional layers, and serves as a damping / shock-absorbing layer to provide shock resistance to the electronic article.

9. The electronic article according to any one of claims 1 to 3, wherein the interlayer adhesive layer is substantially transparent and is disposed between two functional layers to bond or assemble the two functional layers, and serves as a damping / shock-absorbing layer to provide shock resistance to the electronic article, wherein at least one of the functional layers is substantially transparent.

10. The electronic article according to any one of claims 1 to 3, wherein the electronic article is a display device having a structure in which a display unit is directly bonded or assembled to other functional units through the interlayer adhesive layer, and the interlayer adhesive layer serves as a damping / shock-absorbing layer to provide shock resistance to the electronic article.

11. The electronic article according to any one of claims 1 to 3, wherein the thickness of the interlayer adhesive layer ranges from 1 μm to 1000 μm, and the interlayer adhesive layer is disposed between two functional layers as a single adhesive layer to bond or assemble the two functional layers, and serves as a damping / shock-absorbing layer in the electronic article to provide shock resistance to the electronic article.

12. The electronic article according to any one of claims 1 to 3, wherein except for the interlayer adhesive layer, the electronic article is substantially free of any additional interlayer damping / shock-absorbing layer disposed between two functional layers, the temperature at the tanδ peak of the interlayer adhesive layer is lower than 35 °C, and the tanδ value at the peak is greater than 1.0, as measured by a dynamic mechanical analysis rheometer using a parallel plate measurement system at 1 Hz.

13. A method for manufacturing an electronic article according to any one of claims 1 to 12, the method comprising the step of assembling or bonding at least two functional layers with the interlayer adhesive layer, the temperature at the tanδ peak of the interlayer adhesive layer is lower than 35 °C, and the tanδ value at the peak is greater than 1.0, as measured by a dynamic mechanical analysis rheometer using a parallel plate measurement system at 1 Hz.

14. Use of an interlayer adhesive layer as a damping / shock-absorbing layer in an electronic article, wherein the temperature at the tanδ peak of the interlayer adhesive layer is lower than 35 °C, and the tanδ value at the peak is greater than 1.0, as measured by a dynamic mechanical analysis rheometer using a parallel plate measurement system at 1 Hz.

15. The use according to claim 14, wherein there is a single interlayer adhesive layer between two functional layers in the electronic article, without any additional interlayer foam layer or damping / shock-absorbing layer.

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