JP6532798B2 - Adhesive composition and watch using the same - Google Patents

Description

  The present invention relates to an adhesive composition and a watch using the same.

  Watches are widely used all over the world as a tool to know the time. In particular, wristwatches are conveniently used because they can be easily carried by attaching them to the arms. In recent years, watches characterized by various aspects such as color, weight, and environmental performance have been sold.

  The watch is formed by attaching a band to a drive unit called a movement, covering the drive unit with an exterior consisting of exterior parts, that is, an exterior consisting of a bezel and a glass, a case and a back cover, and called a head. . The head protects the movement with a solid exterior that protects the interior.

Conventionally, in order to manufacture the exterior of a watch, the bezel and the glass are fixed by a commercially available adhesive such as a UV-curable adhesive.
In addition, as an adhesive agent which can be used for a wristwatch, specifically as an adhesive agent for fixing a plant on a dial plate base, for example, a precision component consisting of an epoxy resin as a main agent, an amine curing agent and ultrafine particle silica There is an adhesive composition for the purpose (Japanese Patent Application Laid-Open No. H10-118118).

JP 2004-99886 A

  However, when a certain amount of force is applied to the watch, that is, the head, the exterior is flexed, the adhesive for fixing the exterior parts is cracked, and as a result, the glass is separated from the main body or the waterproofness can not be maintained. It may occur.

  Also, when designing a watch that is thin, the removable back cover may not be desirable because it requires structural thickness, and when manufacturing the watch, the pressure-resistant plate can not be attached to the case. May be formed by pasting. In such a thin wristwatch, when the head is subjected to a certain force, the exterior is more likely to be flexed, so the above problem is likely to occur, and it is difficult to bond exterior parts with a conventional ultraviolet curing adhesive.

  Also, in a thin design watch, if the case and the glass are bonded using the adhesive composition for precision parts described in JP-A-2001-101501, if a certain pressure is applied, the glass can not endure deflection as well. Happens to be separated from the body.

  Therefore, an object of the present invention is to provide an adhesive composition capable of maintaining waterproofness even under pressure when fixing exterior parts of a watch. In other words, it is an object of the present invention to provide an adhesive composition having excellent adhesion without causing cracking of the adhesive even under pressure and separation of the exterior parts. Another object of the present invention is to provide a watch having excellent adhesion using the above adhesive composition.

  The solution-like adhesive composition according to the present invention is characterized by containing a bisphenol-type epoxy resin (A), a dimer acid-modified bisphenol A-type epoxy resin (B), and an imidazole-based curing agent (C). .

  By fixing the exterior parts of a watch with the adhesive composition of the present invention, waterproofness can be maintained even under pressure. In other words, the adhesive does not crack even under pressure, and the exterior parts do not separate, and excellent adhesion can be maintained. Even in the case of a thin watch, the adhesive does not crack even under pressure, and the bezel and the glass or the case and the pressure plate do not separate, and excellent adhesion can be maintained. Further, the wristwatch of the present invention is excellent in adhesion because it uses the above adhesive composition. In particular, even with a thin watch, the adhesive composition is used, so that the adhesion is excellent.

  Furthermore, when fixing the exterior parts of a wristwatch with the adhesive composition of the present invention, the adhesive composition can be removed by appropriately heating and immersing in a solvent, for example, when the adhesive composition protrudes. The adhesive composition of the present invention is also excellent in such repairability.

FIG. 1 is a view for explaining a thin watch of the present invention. FIG. 2 is a view for explaining a thin watch of the present invention.

<Adhesive composition>
The adhesive composition of the present invention comprises a bisphenol-type epoxy resin (A), a dimer acid-modified bisphenol A-type epoxy resin (B), and an imidazole-based curing agent (C). That is, it contains a main agent composed of a bisphenol-type epoxy resin (A) and a dimer acid-modified bisphenol A-type epoxy resin (B), and a curing agent composed of an imidazole-based curing agent (C). In the present specification, the bisphenol-type epoxy resin (A), the dimer acid-modified bisphenol A-type epoxy resin (B) and the imidazole-based curing agent (C) are respectively component (A), component (B) and component (C) It is also called.

  The adhesive composition of the present invention is also in the form of a solution. The solution state means that, for example, after the adhesive composition is blended, it can be discharged by a dispenser with a needle of 0.5 mm diameter at 25 ° C. for at least 4 hours. When bonding exterior parts of a watch, such an adhesive composition can be uniformly attached to the narrow gap between the parts, so that the parts can be fixed with high adhesion. On the other hand, in the case of an adhesive composition containing a powdery component (for example, a curing agent or the like), there is a problem that the components can not be fixed firmly because they can not be bled and uniformly attached to narrow gaps between components.

  The bisphenol-type epoxy resin (A) is a diglycidyl ether obtained by reacting bisphenol and epichlorohydrin. The bisphenol-type epoxy resin cures to a resin of high hardness. This is because the phenyl ring in the partial structure of bisphenol brings out heat resistance and hardness. Further, oxygen atoms in the structure have an effect of enhancing the adhesion between the parts, which is suitable for firmly bonding the parts.

  As a bisphenol-type epoxy resin (A), a bisphenol A-type epoxy resin and a bisphenol F-type epoxy resin are mentioned. Specifically, jER 825, jER 806, jER 807 (trade name, manufactured by Mitsubishi Chemical Corporation), EPICLON EXA 850 CRP (trade name, manufactured by DIC Corporation), EP-4400, EP-4520 S, EP-4530, EP-4901 (trade name). As mentioned above, trade name, manufactured by ADEKA Co., Ltd., YDF-170 (trade name, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) can be mentioned. The component (A) may be used alone or in combination of two or more.

  Among these, bisphenol F-type epoxy resin is more preferably used. The bisphenol F-type epoxy resin is often lower in viscosity than the bisphenol A-type epoxy resin, and is suitable for mixing the constituent adhesive components.

  The bisphenol type epoxy resin (A) is usually liquid at 25 ° C., and the viscosity at 25 ° C. is preferably 10 or more and 70 or less, more preferably 35 poise or more and 45 poise or less. Here, the viscosity is a value determined by a rotational viscometer. When the viscosity of the component (A) is in this range, an adhesive composition suitable for adhesion of exterior parts can be prepared.

The bisphenol equivalent epoxy resin (A) preferably has an epoxy equivalent of 160 or more and 200 or less, and more preferably 160 or more and 175 or less.
The dimer acid-modified bisphenol A epoxy resin (B) is a reaction product (ester) of a bisphenol A epoxy resin, which is a condensation product of bisphenol A type and epichlorohydrin, and a dimer acid. In other words, it has a bisphenol A type epoxy resin unit, and a dimer acid unit (a unit in which one carboxyl group of dimer acid to an OH group is removed or a unit in which OH groups are separated from both of two carboxy groups of a dimer acid). In the dimer acid-modified bisphenol A epoxy resin (B), since the dimer acid structure is introduced into the epoxy resin, the reaction sites in the molecule are separated. For this reason, the cured product of the adhesive composition containing the component (B) has desirable flexibility.

  Examples of the dimer acid-modified bisphenol A type epoxy resin (B) include jER 872 (trade name, manufactured by Mitsubishi Chemical Corporation), YD-172 (trade name, manufactured by Nippon Steel Sumikin Chemical Co., Ltd.). The component (B) may be used alone or in combination of two or more.

  The dimer acid-modified bisphenol A epoxy resin (B) is preferably liquid at 25 ° C. However, even if it is semi-solid or solid, such component (B) may be used if it becomes a solution when mixed with component (A). The viscosity at 25 ° C of a 75 wt% xylene solution of a dimer acid-modified bisphenol A epoxy resin (B) (a solution in which the dimer acid-modified bisphenol A epoxy resin (B) is dissolved in xylene to a concentration of 75 wt%) is preferred Is more than 15 poise and less than 25 poise. Here, the viscosity is a value determined by a rotational viscometer. When the viscosity of the component (B) is in this range, an adhesive composition suitable for adhesion of exterior parts can be prepared.

The dimer acid-modified bisphenol A epoxy resin (B) preferably has an epoxy equivalent of 600 or more and 700 or less.
When the imidazole curing agent (C) is blended in a certain amount in the adhesive composition, the reaction proceeds in a chained manner at the time of curing. Moreover, when an imidazole series hardening | curing agent (C) is used, it is easy to adjust the viscosity and hardening speed of adhesive composition.

  As the imidazole based curing agent (C), 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2- Examples include methylimidazole and 1-cyanoethyl-2-ethyl-4-methylimidazole. Further, a hydroxyl group is selected from the group consisting of an imidazole compound, phosphorous acid, phosphorous monoester and phosphorous diester described in JP-A-2010-168516 as an imidazole-based curing agent (C) A curing agent composition may be used which contains, as an essential component, one or more kinds of phosphorous acid compounds having one or more. Specifically, Fujicure 7000 and Fujicure 7001 (trade names, manufactured by T & K TOKA CO., LTD.) Can be mentioned. The component (C) may be used alone or in combination of two or more.

  The imidazole curing agent (C) is preferably liquid at 25 ° C. However, even if it is semi-solid or solid, such component (C) may be used if it becomes a solution when mixed with components (A) and (B). The viscosity at 25 ° C. of the imidazole-based curing agent (C) is preferably 10 poise to 35 poise. Here, the viscosity is a value determined by a rotational viscometer. When the viscosity of the component (C) is in this range, an adhesive composition suitable for adhesion of exterior parts can be prepared.

  The adhesive composition of the present invention comprises the above-mentioned bisphenol-type epoxy resin (A), dimer acid-modified bisphenol A-type epoxy resin (B) and an imidazole-based curing agent (C). When only the component (A) is used as the main component, the composition is liable to run off when the parts to which the adhesive composition is attached are heated and cured. For this reason, in the case of applying an appropriate amount of adhesive, it is necessary to repeat application and curing of adhesive several times. In addition, even when the glass is adhered to the case component by applying it a plurality of times, when a certain pressure is applied, the hardened adhesive is too hard and the adhesive is easily cracked and the glass is easily peeled off from the case. On the other hand, when the component (A) and the component (B) are used in combination as the main agent as in the present invention, the viscosity of the adhesive composition becomes high, and the adhesive composition can be suitably applied. . In addition, the adhesive after curing becomes appropriately flexible while maintaining high adhesion, and can maintain waterproofness even when pressure is applied. Specifically, the adhesive does not crack, and the occurrence of the above-mentioned failure can be suppressed. Thus, when the component (A) and the component (B) are combined as the main component, the handling as the adhesive composition is also improved, and the adhesion after curing of the composition is also improved.

  In addition, although a thin watch has a larger deflection when pressure is applied, the composition can maintain waterproofness since it has appropriate flexibility after curing. Specifically, even if pressure is applied and the head is largely bent, the adhesive does not crack, the bezel and the glass, or the case and the pressure plate do not separate, and high adhesion can be maintained.

  The imidazole curing agent (C) is a compound compatible with the main agent. Industrially, long-term stable curing agents include, for example, powdered curing agents. Such a powdery curing agent can be dispersed in the main agent to stabilize it, but in a watch that requires the adhesive to be poured into a slight gap between the case and the glass, solids do not easily enter the gap. For this reason, the imidazole curing agent is required to be compatible with the main agent. In other words, as in the adhesive composition of the present invention, component (C) preferably forms a solution with component (A) and component (B). In addition, when the imidazole-based curing agent (C) is used, there is also an advantage that the dimer acid-modified bisphenol A epoxy resin (B) can be made into a cured product having appropriate flexibility.

  Furthermore, the watch is a precision instrument and fashion is also important. Therefore, if the adhesive is exposed, it becomes a defective product and can not be shipped as a product. On the other hand, since the watch parts are precision machined parts, they are expensive and it is difficult to think about discarding in production and sales. For this reason, it is preferable to be able to reuse the part in which the adhesion failure occurred. The adhesive composition of the present invention is also excellent in repairability. That is, even if the adhesive overflows, etc., the adhesive can be removed cleanly by performing a certain treatment.

  Specifically, the exterior component to which the cured adhesive composition of the present invention is attached is heated on a hot plate at 120 ° C. for 10 minutes, and for example, pressure is applied to peel off the component. Then, by immersing the part in a solvent such as methyl ethyl ketone, methyl isobutyl ketone, ethanol or the like for 24 hours, the adhered adhesive can be removed by a tool (for example, bamboo basket) softer than the part.

  The adhesive composition of the present invention preferably comprises 40 parts by weight of bisphenol type epoxy resin (A) based on 100 parts by weight of the total of bisphenol type epoxy resin (A) and dimer acid-modified bisphenol A type epoxy resin (B). The dimer acid-modified bisphenol A epoxy resin (B) is preferably 5 parts by weight or more and 60 parts by weight or less, more preferably 20 parts by weight in an amount of at least 95 parts by weight and more preferably at least 60 parts by weight and at most 80 parts by weight. It is desirable to include in an amount of 40 parts by weight or less. From the viewpoint of the balance between the handling of the adhesive composition and the flexibility of the cured adhesive, it is preferable to use the components (A) and (B) in the above amounts. That is, the viscosity of the adhesive composition becomes appropriate, and an appropriate amount of the composition can be applied onto the part. In addition, the adhesive after curing also becomes appropriately flexible while maintaining high adhesion. If the amount of the component (B) is more than the above amount, the viscosity becomes too high, which may make it impossible to apply an appropriate amount of adhesive onto the component. In addition, the adhesive after curing becomes too soft, and the adhesive strength may be lowered, and the glass may not be fixed.

  Further, the adhesive composition of the present invention comprises 5 parts by weight of the imidazole curing agent (C) with respect to 100 parts by weight in total of the bisphenol type epoxy resin (A) and the dimer acid-modified bisphenol A type epoxy resin (B). It is desirable that the content be 40 parts by weight or less, more preferably 25 parts by weight or more and 35 parts by weight or less. It is preferable to use component (C) in the above amount from the viewpoint of the balance between the curing speed of the adhesive composition and the storage property of the adhesive composition. If the amount of the component (C) is more than the above amount, the curing speed may be increased and industrial productivity may be improved, but the storage stability of the adhesive may be reduced. In the case of using a curing agent composition containing an imidazole compound as described above as the imidazole curing agent (C) and a phosphorus-containing compound such as a phosphorous acid compound, it is preferable to use the curing agent composition in the above amount .

  The method for preparing the adhesive composition of the present invention is not particularly limited as long as a solution-like adhesive composition can be prepared. For example, first, using an oven, bisphenol type epoxy resin (A) and dimer acid modified bisphenol A type epoxy resin Each of (B) is heated to 60 to 90 ° C. to soften the component (B) and improve the handleability. Subsequently, appropriate amounts of the component (A) and the component (B) are weighed and further stirred and mixed at 60 to 90 ° C. After mixing the component (A) and the component (B), the mixture is cooled to room temperature (for example, 25 ° C.), and the imidazole curing agent (C) is further added and stirred to obtain an adhesive composition. In the mixing of the component (A) and the component (B), the component (B) is heated to 60 to 90 ° C. while keeping the component (A) at room temperature to soften the component (B) and improve the handling property Then, the components (A) and (B) may be metered appropriately and further mixed at 60 to 90 ° C. with stirring.

  When storing the obtained adhesive composition, it is preferable to store it in a frozen state (for example, -18 ° C or less, preferably -40 ° C or less). This allows, for example, storage for at least several months without deterioration.

  When the adhesive composition of the present invention is used, it can be used usually for bonding of exterior parts after returning to 0 to 30 ° C. However, the composition is usually returned to room temperature (eg 25 ° C.) and then 4 The exterior parts can be adhered well for a time or more, preferably 8 hours or more, more preferably 16 hours or more, and the workability is also excellent.

  The adhesive composition of the present invention may consist only of the component (A), the component (B) and the component (C) described above, and includes other components as long as the object of the present invention is not impaired. It may be. Other components include, for example, components which become a solution when mixed with the components (A) and (B), specifically, solvents, inactive colorants, antioxidants, UV absorbers, light stabilizers ( HALS).

  More specific examples of the solvent include volatile solvents having a boiling point of 150 ° C. or less such as xylene, toluene, acetone and the like. The solvents may be used alone or in combination of two or more. When a solvent is used, the solvent is, for example, in an amount of more than 0 parts by weight and 10 parts by weight or less based on 100 parts by weight in total of bisphenol type epoxy resin (A) and dimer acid-modified bisphenol A type epoxy resin (B). It is desirable to include.

  The above-mentioned other components other than the solvent are, for example, more than 0 parts by weight and 5 parts by weight or less with respect to 100 parts by weight in total of the bisphenol type epoxy resin (A) and the dimer acid-modified bisphenol A type epoxy resin (B). It is desirable to include in amount.

  The method for preparing the adhesive composition in the case of including other components is not particularly limited as long as a solution-like adhesive composition can be prepared, but, for example, the other components are first added to the mixture of component (A) and component (B) Then, component (C) is added, or the other components are added to component (C), and then a mixture of component (A) and component (B) is added to obtain an adhesive composition.

  The adhesive composition of the present invention is suitably used as an adhesive composition for fixing exterior parts constituting a watch head. In this case, the wristwatch has, for example, a bezel, a glass, a case and a pressure plate as the exterior component, and the bezel and the glass are fixed by the adhesive composition, or the case and the pressure plate And are fixed. The specific configuration and bonding method of the watch will be described in detail in the description of the watch and the method of manufacturing the watch.

<Clock and its manufacturing method>
The wristwatch according to the present invention, that is, a thin wristwatch, has a bezel 12, a glass 14, a case 16, and a pressure resistant plate 18 as exterior parts constituting the head 10, as shown in FIG. Here, FIG. 1 shows one side of the cross section of the head. The pressure-resistant plate 18 is a plate having the same function as a removable back cover used for a head having a normal thickness, but attached to a case so as not to be removable and formed of a brittle material having a high Young's modulus. .

As described above, in the thin wrist watch head 10, the thickness of the exterior parts is also thin, and the exterior constituted by the exterior parts has a special structure in order to stably hold the movement 20. That is, it has a two-body structure of a portion formed of the bezel 12 and the glass 14 and a portion formed of the case 16 and the pressure resistant plate 18. Also, these two parts are fixed by screws 22.
In addition to the movement 20, the dial 10 and the like are provided in the head 10, and a space is formed between the dial 24 and the glass 14.

  As mentioned above, the watch of the present invention has a thin head. Specifically, the thickness of the head is a direction perpendicular to the dial 24 as shown in FIG. 1, and is the distance from the surface of the glass 14 to the surface of the pressure-resistant plate 18 and is the largest distance. As a general watch, the range of plus 2 mm minus 2 mm is standard based on the thickness of the head of 10 mm, and when it exceeds 12 mm, it is a thick watch and less than 8 mm is a watch that emphasizes thinness. In the watch of the invention, the thickness of the head is usually less than 4 mm, preferably less than 3 mm.

  The glass 14 bonded and fixed to the bezel 12 and covered with the dial 24 is preferably made of mineral glass, crystal glass, quartz glass or sapphire glass from the viewpoint of maintaining the strength even in a thin watch.

The thickness of the glass 14 is preferably 450 μm or more and 550 μm or less, more preferably 500 μm or more and 550 μm or less from the viewpoint of the balance between strength and thinness.
It is preferable that the bezel 12 and the case 16 corresponding to the relatively thick outer peripheral part in thin watch parts be made of stainless steel (for example, SUS316L), titanium such as pure titanium, or a cermet. Thereby, the strength can be maintained even in a thin watch.

The case 16 corresponding to the back side has a structure in which the central portion is removed, and the strength is maintained by adhesively fixing the pressure resistant plate 18 to this. The pressure plate 18 is preferably made of a brittle material having a Young's modulus of 200 GPa or more. The Young's modulus of the brittle material forming the pressure resistant plate 18 is more preferably 350 GPa or more, still more preferably 400 GPa or more. Thereby, the strength can be maintained even in a thin watch. Specifically, materials of sapphire (Young's modulus: about 470 GPa), cermet (Young's modulus: about 440 GPa), tungsten (Young's modulus: about 411 GPa), alumina (Young's modulus: about 360 GPa), and zirconia (Young's modulus: about 200 GPa) can be used.
The thickness of the pressure resistant plate 18 is preferably 300 μm or more and 500 μm or less from the viewpoint of balance between strength and thinness.

  In the watch of the present invention, the bezel 12 and the glass 14 are fixed or the case 16 and the pressure-resistant plate 18 are fixed by the solution adhesive composition described above. Preferably, both the bezel 12 and the glass 14 and the case 16 and the pressure plate 18 are fixed by the solution-like adhesive composition described above.

  In the thin watch having the above-described two-body structure, the exterior component is easily deformed when it receives pressure. If the watch is to be sold waterproof at 3 bar, it is necessary to withstand this pressure. However, when bonding the exterior parts of a thin watch, if a conventional adhesive, that is, a strong adhesive that becomes hard after curing, is used, a crack is generated during deformation and the waterproof can not be maintained. On the other hand, if a flexible adhesive that can follow deformation is used, it is too soft, the adhesive strength is lowered, and parts can not be taken, for example. Therefore, in bonding to a thin wristwatch exterior part, the adhesive composition of the present invention which is excellent in the balance between the adhesive strength after curing and the flexibility is preferably used. In other words, the adhesive composition of the present invention is preferably used which has a high adhesive strength after curing and is moderately flexible and can maintain waterproofness even when pressure is applied.

  In bonding of a specific exterior component, for example, the adhesive composition of the present invention is applied to the bezel 12 and then the glass 14 is fitted. Also, for example, after applying the adhesive composition of the present invention to the case 16, the pressure resistant plate 18 is fitted. More specifically, for example, the adhesive composition is annularly discharged by a dispenser and applied to a glass mounting portion (for example, an L-shaped corner) formed in the bezel 12 with a cross section, Fit in When the glass 14 is inserted, the adhesive composition spreads in an L-shape along the mounting portion and adheres to the portion shown in black in FIG. 1 between the bezel 12 and the glass 14. Similarly, an adhesive composition is annularly discharged by a dispenser and applied to a pressure-resistant plate mounting portion (for example, an L-shaped corner) having an L-shaped cross section formed on the back side of the case 16. Insert 18 When the pressure-resistant plate 18 is fitted, the adhesive composition spreads in an L shape along the mounting portion, and adheres to the portion shown in black in FIG. 1 between the case 16 and the pressure-resistant plate 18. The adhesive composition of the present invention may be applied to the glass 14 or the pressure resistant plate 18 and then fitted into the bezel 12 or the case 16 respectively. The adhesive composition of the present invention, which is liquid, can be uniformly applied to narrow gaps between parts, so that parts can be fixed with high adhesion.

  After adhering the adhesive composition between the exterior parts as described above, the composition is cured usually at 80 to 120 ° C. for 1 to 3 hours to bond the exterior parts. Next, the part consisting of the bezel 12 and the glass 14 and the part consisting of the case 16 and the pressure-resistant plate 18 are fixed by means of the screws 22 to produce the watch of the present invention. The assembly of other parts inside the head such as the movement and the attachment of the band can be appropriately performed by a known method.

  The wristwatch of the present invention thus obtained has a waterproof performance of usually 3 atmospheres, since it is adhered by the above-mentioned adhesive composition. In addition, preferably, the fixing force is 20 kgf or more.

  Furthermore, the watch of the present invention is excellent in repairability. That is, even when the adhesive composition described above has run out, etc., the adhesive can be removed cleanly by performing a certain treatment. The specific treatment is the same as that described in the description of the adhesive composition.

The watch of the present invention may be a thin watch having a head 40 as shown in FIG. Here, FIG. 2 shows one side of the cross section of the head. The head 40 has a two-piece structure of a portion constituted by the bezel 42 and the glass 44 and a portion constituted by the case 46, and is provided with a movement 48 and a crown 50. That is, the head 40 does not have a pressure-resistant plate. These two parts are fixed by screws. The bezel 42 and the glass 44 are fixed by the solution adhesive composition described above. Specifically, the bezel 42 and the glass 44 are fixed by adhering the solution adhesive composition described above to the portion shown black in FIG. 2 and curing it. Also in this case, since the adhesive composition of the present invention, which is excellent in the balance between the adhesive strength after curing and the flexibility, is used, the exterior component is firmly adhered, and the waterproofness can be maintained.
In the head 40, a dial 52 and the like are provided, and a space is formed between the dial 52 and the glass 44.

  In addition, as another aspect of the watch of the present invention, a watch having a thinning head having a thickness of 4 mm or more and less than 8 mm, a normal head having a thickness of 8 mm or more and 12 mm or less, or a thicker head having a thickness of more than 12 mm can be mentioned. . Also in these cases, since the adhesive composition of the present invention, which is excellent in the balance between the adhesive strength after curing and the flexibility, is used, the exterior component is firmly adhered, and the waterproofness can be maintained.

  Another example of the watch of the present invention is a watch having a pattern on glass. If there is a pattern on the glass, the conventional UV-curable adhesive used for bonding the exterior parts of a wristwatch has a problem that the curing of the adhesive by ultraviolet light does not proceed, and the glass and the bezel can not be bonded. However, since the adhesive composition of the present invention is cured by heating, the glass and the bezel can be firmly bonded.

As mentioned above, the present invention relates to the following.
[1] A solution-like adhesive composition comprising a bisphenol-type epoxy resin (A), a dimer acid-modified bisphenol A-type epoxy resin (B), and an imidazole-based curing agent (C).
According to the above adhesive composition, the exterior parts of the wristwatch can be firmly adhered. In addition, the obtained watch can maintain waterproofness even under pressure.

  [2] Based on 100 parts by weight of the total of bisphenol type epoxy resin (A) and dimer acid-modified bisphenol A type epoxy resin (B), an amount of 60 parts by weight or more and 95 parts by weight or less of bisphenol type epoxy resin (A) Characterized in that the dimer acid-modified bisphenol A epoxy resin (B) is contained in an amount of 5 to 40 parts by weight, and the imidazole curing agent (C) is contained in an amount of 5 to 35 parts by weight. The solution-like adhesive composition as described in said [1].

  The components (A) and (B) are preferably used in the above amounts from the viewpoint of the balance between the handling of the adhesive composition and the flexibility of the cured adhesive. Component (C) is preferably used in the above amount in view of the balance between the curing speed of the adhesive composition and the storage stability of the adhesive composition.

[3] The solution-like adhesive composition according to the above [1] or [2], wherein the bisphenol-type epoxy resin (A) is a bisphenol F-type epoxy resin.
The bisphenol F-type epoxy resin has a preferable viscosity for mixing the adhesive components to be constituted.

[4] Viscosity at 25 ° C of bisphenol type epoxy resin (A) is 35 to 45 poise, and viscosity at 25 ° C of a 75 wt% xylene solution of dimer acid-modified bisphenol A type epoxy resin (B) is 15 poise or more It is 25 poises or less, and the viscosity at 25 ° C. of the imidazole-based curing agent (C) is 10 poises or more and 35 poises or less. The solution-like adhesion according to any one of the above [1] to [3] Agent composition.
When the viscosity of components (A) to (C) is in this range, an adhesive composition preferable for adhesion of exterior parts can be prepared.

[5] The adhesive composition is an adhesive composition for fixing an exterior part constituting a watch head, and the wristwatch has a bezel, a glass, a case and a pressure resistant plate as the exterior part, The solution according to any one of the above [1] to [4], wherein the bezel and the glass are fixed or the case and the pressure-resistant plate are fixed by the adhesive composition. Adhesive composition.
According to the above adhesive composition, the exterior parts of the wristwatch can be firmly adhered. In addition, the obtained watch can maintain waterproofness even under pressure.

[6] A watch having a bezel, glass, a case, and a pressure-resistant plate as exterior parts constituting a head, wherein the solution-like adhesive composition according to any one of the above [1] to [4] And a glass is fixed, or the case and the pressure-resistant plate are fixed.
In the wristwatch of the present invention, since the exterior component is fixed by the above adhesive composition, it is excellent in waterproofness and adhesiveness.

  [7] The solution-like adhesive composition as described in the above [5] or the wristwatch as described in the above [6], wherein the glass is made of mineral glass, crystal glass, quartz glass or sapphire glass.

  [8] The solution-like adhesive composition as described in the above [5] or the wristwatch as described in the above [6], wherein the pressure resistant plate is made of a brittle material having a Young's modulus of 200 GPa or more.

  [9] The adhesive composition in solution form according to the above [8] or the wristwatch according to the above [8], wherein the brittle material is sapphire, cermet, tungsten, alumina or zirconia.

[10] The adhesive composition in the form of a solution according to the above [5] or the watch according to the above [6], wherein the bezel and the case are respectively made of stainless steel, titanium or cermet.
When the glass, the pressure plate, the bezel and the case are made of the above materials, even a thin watch can maintain its strength.

[11] The watch according to the above [6], wherein the thickness of the head is less than 4 mm.
As described above, even if the head is thin, the exterior part is fixed by the above-mentioned adhesive composition in the wristwatch of the present invention, so the waterproofness and the adhesiveness are excellent.

  [12] The watch according to the above [6], wherein the thickness of the glass is 450 μm or more and 550 μm or less.

[13] The wristwatch according to the above-mentioned [6], wherein the thickness of the pressure resistant plate is 300 μm or more and 500 μm or less.
When the thickness of the glass and pressure resistant plate is in the above range, the balance between strength and thinness is excellent.

[14] A manufacturing method of a wristwatch having a bezel, a glass, a case, and a pressure-resistant plate as exterior parts constituting a head, which comprises the solution adhesive composition according to any one of the above [1] to [4]. A method of manufacturing a watch, comprising: fixing the bezel and the glass; or fixing the case and the pressure-resistant plate.
In the wristwatch thus obtained, since the exterior part is fixed by the adhesive composition, the waterproofness and the adhesiveness are excellent.

[15] The method for manufacturing a watch according to the above [14], wherein the thickness of the head is less than 4 mm.
Thus, even if the head is thin, the exterior part is fixed by the adhesive composition in the obtained wristwatch, and therefore, the waterproofness and the adhesiveness are excellent.

  [16] The method for manufacturing a wristwatch according to the above [14], wherein the thickness of the glass is 450 μm or more and 550 μm or less.

[17] The method for manufacturing a wristwatch according to the above [14], wherein the thickness of the pressure plate is 300 μm to 500 μm.
When the thickness of the glass and the pressure-resistant plate is in the above range, the obtained watch has an excellent balance of strength and thinness.

[Example]
Hereinafter, the present invention will be more specifically described based on examples, but the present invention is not limited to these examples.

<Evaluation method>
[Workability (workable duration)]
The adhesive composition stored at −40 ° C. after preparation was returned to the room temperature of 25 ° C., and after 4 hours, 8 hours and 16 hours, it was evaluated whether the adhesive composition could be precision applied. For precision application, the adhesive composition is made with a dispenser in which a needle with a diameter of 5 mm is provided at the tip of the syringe in a glass attachment part (specifically, the L-shaped corner) formed in a bezel (made of SUS316L). The material was discharged in a ring shape. That is, air pressure was sent to the syringe through the tube, and the adhesive composition contained in the syringe was discharged. The discharge pressure was changeable from 0 to 0.2 MPa. In the evaluation criteria described below, the case where accurate application could not be performed even when the pressure was increased to 0.2 MPa was considered as a case where accurate application was not possible.
Evaluation criteria A1: After 4 hours, 8 hours and 16 hours, the adhesive composition was able to be discharged continuously and precisely applied.
A2: After 4 hours and 8 hours, the adhesive composition could be discharged continuously and precisely applied. However, after 16 hours, it was not possible to discharge continuously, and precise coating could not be performed.
A3: After 4 hours, the adhesive composition was discharged continuously and could be precisely applied. However, after 8 hours, the ink could not be discharged continuously and precision coating could not be performed.
B: After 4 hours, it was not possible to discharge continuously continuously, so precision coating could not be performed.

[Curable]
With respect to a sample consisting of a bezel and glass heated after application of the adhesive composition, it was evaluated whether the adhesive composition was cured. Whether cured, using a commercially available hand press and push-pull gauge, apply an external pressure of 5 kgf in the direction to peel off the part, then apply an external pressure of 10 kgf, and then apply an external pressure of 20 kgf, the part does not peel off It was judged by or. Here, in FIG. 1, pressure was applied to the glass from the side provided with the dial.
Evaluation criteria A1: The samples heated for 1.5 hours, the samples heated for 2 hours, and the samples heated for 5 hours did not peel even when applied over 20 kgf.
A2: The sample heated for 1.5 hours did not peel off even when 10 kgf was applied, but peeled off when 20 kgf was applied. The sample heated for 2 hours and the sample heated for 5 hours did not peel even when applied over 20 kgf.
A3: The sample heated for 1.5 hours and the sample heated for 2 hours did not peel off even when applied over 10 kgf, but peeled off when applied over 20 kgf. The sample heated for 5 hours did not peel even if it applied 20 kgf.
A4: The samples heated for 1.5 hours, the samples heated for 2 hours, and the samples heated for 5 hours did not peel off even when 5 kgf was applied, but they peeled when 10 kgf was applied.

Example 1-1
As the bisphenol type epoxy resin (A), jER 807 (trade name, manufactured by Mitsubishi Chemical Corporation), which is bisphenol F type epoxy resin, and as the dimer acid-modified bisphenol A type epoxy resin (B), jER 872 (trade name, Mitsubishi Chemical Corporation) Fujicure 7001 (trade name, manufactured by T & K TOKA CO., LTD.) Was used as the imidazole-based curing agent (C).

  The component (A) and the component (B) were previously heated to 80 ° C. using an oven to soften the component (B) and improve the handleability. 90 parts by weight of the component (A) and 10 parts by weight of the component (B) were weighed and stirred and mixed while being heated to 80 ° C. The resulting mixture was cooled to room temperature (25 ° C.), 5 parts by weight of component (C) was added and stirred to obtain an adhesive composition. The resulting adhesive composition was stored at -40 ° C. Here, the above-mentioned workability was evaluated.

  Subsequently, it returned to room temperature (25 degreeC) with the dispenser which has a 5 mm diameter needle with respect to the glass mounting part (specifically L-shaped corner) of the cross-sectional L-shape formed in the bezel (made of SUS316L) The adhesive composition was applied by annular discharge, and then fitted with sapphire glass (about 30.5 mm in diameter and 500 mm in thickness). Here, the application was performed specifically as described in the method of evaluating the workability. Thus, the adhesive composition was adhered between the bezel and the glass (the portion shown black in FIG. 1). Three such samples were prepared. The three samples were then heated in an oven at 80 ° C. for 1.5 hours, 2 hours and 5 hours, respectively, to obtain a bezel and a glass sample. Here, the above-mentioned curability was evaluated.

[Example 1-2]
An adhesive composition and a sample consisting of a bezel and a glass were obtained in the same manner as in Example 1-1 except that 10 parts by weight of the component (C) was added. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-3]
A sample consisting of an adhesive composition and a bezel and glass was obtained in the same manner as in Example 1-1 except that 20 parts by weight of the component (C) was added. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

Example 1-4
A sample consisting of an adhesive composition and a bezel and glass was obtained in the same manner as in Example 1-1 except that 25 parts by weight of the component (C) was added. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-5]
A sample consisting of an adhesive composition and a bezel and glass was obtained in the same manner as in Example 1-1 except that 30 parts by weight of the component (C) was added. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-6]
A sample consisting of an adhesive composition and a bezel and glass was obtained in the same manner as in Example 1-1 except that 35 parts by weight of the component (C) was added. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-7]
A sample consisting of an adhesive composition and a bezel and glass was obtained in the same manner as in Example 1-1 except that 40 parts by weight of the component (C) was added. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-8]
An adhesive composition, a bezel and a glass in the same manner as in Example 1-1 except that 30 parts by weight of component (A), 70 parts by weight of component (B) and 30 parts by weight of component (C) were used Sample was obtained. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-9]
A sample consisting of an adhesive composition and a bezel and glass was obtained in the same manner as in Example 1-8, except that 20 parts by weight of component (A) and 80 parts by weight of component (B) were used. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.

[Example 1-10]
A sample consisting of an adhesive composition, a bezel and a glass was obtained in the same manner as in Example 1-8, except that 10 parts by weight of component (A) and 90 parts by weight of component (B) were used. The above-described workability and curability were also evaluated in the same manner as in Example 1-1.
The evaluation results of the above-described workability and curability are shown in Table 1 for Examples 1-1 to 1-10.

<Evaluation method>
[Waterproof]
The watch may be watery to use. Therefore, it is important to provide waterproofness. In the waterproof test, a simulated head is set in a pressure-applied kettle, water is injected and a predetermined pressure is applied, and then the head is removed from the kettle and the adhesive is cracked, etc. I checked if there was any intrusion.

  For the simulated head, first, a waterproofing test at 2 atm was performed, and then a fixing strength test was also performed on the head taken out of the pot. Next, the above-mentioned head was again subjected to a waterproofing test at 2 atm, and a waterproofing test at 3 atm and a waterproofing test at 5 atm were continuously performed.

  In the fixing force test, the screw (corresponding to the screw 22 in FIG. 1) was removed, and the screw was disassembled into a portion consisting of the bezel and the glass and a portion consisting of the case and the pressure-resistant plate. For both, using a commercially available hand press and push-pull gauge, an external pressure of 20 kgf was applied in the direction of peeling the parts, and it was judged whether the parts did not peel. Here, in the case of the portion consisting of the bezel and the glass, pressure is applied to the glass from the side provided with the dial plate in FIG. 1, and in the case of the portion consisting of the case and the pressure-resistant plate, the movement in FIG. Pressure was applied to the pressure plate from the side where it was installed. In addition, after the fixing force test, the part consisting of the bezel and the glass and the part consisting of the case and the pressure-resistant plate were screwed again to perform a waterproofing test as a state of the head.

In addition, when this series of tests pass, for example, it can be sold as a product having a waterproof performance of 3 atmospheres.
Evaluation criteria A: In the first two-pressure waterproofing test, no water entered the inside of the head. The parts did not peel off even under an external pressure of 20 kgf in a fixing force test carried out after a waterproof test at 2 atm. Further, in the waterproofing test conducted at 2 atm, the waterproofing test at 3 atm, and the waterproofing test at 5 atm, water did not enter the inside of the head.
B: Water infiltrated into the inside of the head in the first 2 atm waterproof test. For this reason, subsequent evaluations could not be performed.

Repairability
The simulated head was unscrewed, disassembled into a portion consisting of a bezel and a glass, and a portion consisting of a case and a pressure plate, and heated on a hot plate at 120 ° C. for 10 minutes. With respect to the portion consisting of the bezel and the glass, the glass was brought into contact with the hot plate, and with respect to the portion consisting of the case and the pressure resistant plate, the pressure resistant plate was heated so as to be in contact with the hot plate. Then, pressure was applied to each of the two parts to peel off the bezel, the glass, the case, and the pressure plate. Then, these parts were immersed in ethanol for 24 hours, and then the adhering adhesive was removed with a bamboo basket softer than the parts. It was visually evaluated whether the adhesive could be removed cleanly. For the head where the adhesive could not be removed cleanly, it was further immersed in ethanol for 24 hours, and then the adhering adhesive was removed with a bamboo basket softer than the part. It was visually evaluated whether the adhesive could be removed cleanly.
Evaluation criteria A1: After the first immersion in ethanol, all the adhesive was removed cleanly.
A2: After the first immersion in ethanol, a part of the adhesive remained. However, after the second immersion in ethanol, all the adhesive was removed cleanly.

Example 2-1
An adhesive composition was obtained in the same manner as in Example 1-1 except that 30 parts by weight of the component (C) was added.
First, at room temperature (25 ° C), a dispenser with a 5 mm diameter needle is used for bonding to a glass mounting portion (specifically, the L-shaped corner) formed in a bezel (made of SUS316L) at a room temperature (25 ° C) The agent composition was discharged in a ring form and applied, and then sapphire glass (about 30.5 mm in diameter and 500 mm in thickness) was fitted. Thus, the adhesive composition was adhered between the bezel and the glass (the portion shown black in FIG. 1). In addition, it has a needle with a diameter of 5 mm against the pressure-resistant plate mounting portion (specifically, the L-shaped corner) of the L-shaped cross section formed on the back side of the case (SUS316L, diameter: about 38.5 mm) The adhesive composition was annularly discharged by a dispenser and applied, and then a pressure resistant plate (made of cermet, 30.0 mm in diameter, 400 mm in thickness) was fitted. In this way, the above adhesive composition was attached between the bezel and the glass and between the case and the pressure plate (the portion shown black in FIG. 1). The application was carried out as described in the method of evaluating the workability.

  Next, the adhesive composition was cured in an oven at 80 ° C. for 1.5 hours to bond the parts together for the portion consisting of the bezel and the glass and the portion consisting of the case and the pressure plate. Subsequently, the part which consists of a bezel and glass, and the part which consists of a case and a pressure | voltage resistant board was fixed with a screw, and the thickness obtained the simulated head less than 3.0 mm. The above waterproofness and repairability were evaluated for the obtained head.

[Example 2-2]
An adhesive composition and a simulated head were obtained in the same manner as in Example 2-1 except that 80 parts by weight of component (A) and 20 parts by weight of component (B) were used. The above waterproofness and repairability were also evaluated in the same manner as in Example 2-1.

Embodiment 2-3
An adhesive composition and a simulated head were obtained in the same manner as in Example 2-1 except that 70 parts by weight of component (A) and 30 parts by weight of component (B) were used. The above waterproofness and repairability were also evaluated in the same manner as in Example 2-1.

Example 2-4
An adhesive composition and a simulated head were obtained in the same manner as in Example 2-1 except that 60 parts by weight of component (A) and 40 parts by weight of component (B) were used. The above waterproofness and repairability were also evaluated in the same manner as in Example 2-1.

[Example 2-5]
An adhesive composition and a simulated head were obtained in the same manner as in Example 2-1 except that 50 parts by weight of component (A) and 50 parts by weight of component (B) were used. The above waterproofness and repairability were also evaluated in the same manner as in Example 2-1.

Example 2-6
An adhesive composition and a simulated head were obtained in the same manner as in Example 2-1 except that 40 parts by weight of component (A) and 60 parts by weight of component (B) were used. The above waterproofness and repairability were also evaluated in the same manner as in Example 2-1.

Comparative Example 2-1
An adhesive composition and a simulated head were obtained in the same manner as in Example 2-1 except that 100 parts by weight of component (A) and component (B) were not used. The above waterproofness and repairability were also evaluated in the same manner as in Example 2-1.
The evaluation results of the above waterproofness and repairability are shown in Table 2 for Examples 2-1 to 2-6 and Comparative Example 2-1.

  In the above embodiment, when mineral glass, crystal glass or quartz glass is used as the glass instead of sapphire glass, a pressure resistant plate is used when glass of about 32.0 mm in diameter is used instead of glass of about 30.5 mm in diameter. The above evaluations were made similarly in the case where cermet, tungsten, alumina or zirconia was used instead of sapphire, and titanium or a cermet was used instead of SUS316L as the case and bezel. The evaluation results were the same as in the above example.

10: head 12: bezel 14: glass 16: case 18: pressure plate 20: movement 22: screw 24: dial plate 40: head 42: bezel 44: glass 46: case 48: movement 50: crown 52: dial plate

Claims (21)

An adhesive composition for fixing a watch exterior part, comprising:
A solution-like adhesive composition for a wristwatch, comprising a bisphenol-type epoxy resin (A), a dimer acid-modified bisphenol A-type epoxy resin (B), and an imidazole-based curing agent (C).   When the total of bisphenol-type epoxy resin (A) and dimer acid-modified bisphenol A-type epoxy resin (B) is 100 parts by weight, the amount of dimer is 60 parts by weight or more and 95 parts by weight or less of bisphenol-type epoxy resin (A) The acid-modified bisphenol A epoxy resin (B) is contained in an amount of 5 to 40 parts by weight, and the imidazole-based curing agent (C) is contained in an amount of 5 to 35 parts by weight. The solution adhesive composition for wristwatches as described in 1.   The adhesive composition for a wristwatch according to claim 1 or 2, wherein the bisphenol epoxy resin (A) is a bisphenol F epoxy resin.   The viscosity of the bisphenol type epoxy resin (A) at 25 ° C. is 35 to 45 poise, and 25 of the solution in which the dimer acid-modified bisphenol A type epoxy resin (B) is dissolved in a solvent to a concentration of 75 wt% The viscosity in 15 ° C to 25 poises in ° C, and the viscosity at 25 ° C of the imidazole-based curing agent (C) is 10 poises to 35 poises. The solution adhesive composition for wristwatches of description. The adhesive composition is an adhesive composition for fixing an exterior part constituting a watch head,
The watch has a bezel, a glass, a case and a pressure plate as the exterior part,
5. The solution according to any one of claims 1 to 4, wherein the bezel and the glass are fixed or the case and the pressure-resistant plate are fixed by the adhesive composition. Adhesive composition for watches. The solution-like adhesive composition for watch according to claim 5, wherein the glass is made of mineral glass, crystal glass, quartz glass or sapphire glass . The adhesive composition for a wristwatch according to claim 5, wherein the pressure-resistant plate is made of a brittle material having a Young's modulus of 200 GPa or more . The solution-like adhesive composition for a wristwatch according to claim 7 , wherein the brittle material is sapphire, cermet, tungsten, alumina or zirconia . The solution-like adhesive composition for watch according to claim 5, wherein the bezel and the case are made of stainless steel, titanium or cermet, respectively . A wristwatch having a bezel, a glass, a case and a pressure-resistant plate as exterior parts constituting a head, wherein the bezel and the glass are formed by the adhesive composition for a wristwatch according to any one of claims 1 to 4. The watch is characterized in that the case is fixed or the case and the pressure plate are fixed. The watch according to claim 10, wherein the glass is made of mineral glass, crystal glass, quartz glass or sapphire glass. The watch according to claim 10, wherein the pressure-resistant plate is made of a brittle material having a Young's modulus of 200 GPa or more. The watch according to claim 12, wherein the brittle material is sapphire, cermet, tungsten, alumina or zirconia. The watch according to claim 10, wherein the bezel and the case are made of stainless steel, titanium or cermet, respectively. 11. The watch according to claim 10 , wherein the thickness of the head is less than 4 mm. The watch according to claim 10 , wherein the thickness of the glass is 450 μm or more and 550 μm or less. The watch according to claim 10 , wherein a thickness of the pressure-resistant plate is 300 μm to 500 μm.   It is a manufacturing method of a wristwatch which has a bezel, glass, a case, and a pressure-resistant plate as an exterior component which comprises a head, Comprising: The adhesive composition for wristwatches of the solution form of any one of Claims 1-4 said A method of manufacturing a watch, comprising fixing a bezel and a glass or fixing the case and a pressure-resistant plate. The method for manufacturing a watch according to claim 18 , wherein the thickness of the head is less than 4 mm. The method for manufacturing a wristwatch according to claim 18 , wherein the thickness of the glass is 450 μm or more and 550 μm or less. The method for manufacturing a wristwatch according to claim 18 , wherein the thickness of the pressure resistant plate is 300 μm or more and 500 μm or less.

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