JP6857839B2 - Portable information terminal - Google Patents

Description

The present invention relates to a portable information terminal end. For more information, about the smart phone, mobile phone, car navigation system, a digital camera, a notebook computer, a tablet computer, a head-mounted display, a wristwatch-type terminal, an electronic organizer, a portable information terminal at the end of such as an electronic dictionary.

As a portable information terminal, one provided with a housing in which a display panel is housed and a cover panel for protecting the display panel has been proposed. Then, the housing and the cover panel are adhered to each other by using double-sided tape (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2010-157957

However, due to the miniaturization of the housing and the narrowing of the frame of the cover panel, the area where the housing and the cover panel adhere to each other has become smaller, making it difficult to place the double-sided tape on the adhesive surface, and the housing and the cover adhere to each other. There was a problem that it became difficult.

The present invention has been made in view of the above, it is an object to provide a portable information terminal end of the adhesive of the housing and the cover panel can be easily.

The portable information terminal according to the present invention is
The housing that houses the display panel and
A cover panel that protects the display panel and
A portable information terminal including an adhesive portion for adhering the housing and the cover panel.
The adhesive portion is a cured product of an adhesive that is liquid immediately after irradiation with ultraviolet rays and cures after a lapse of a predetermined time.

According to the present invention, even if the area where the housing and the cover panel are adhered is small, the adhesive is a liquid, so that it can be easily supplied, and the housing and the cover panel can be easily adhered.

FIG. 1 shows a portable information terminal according to an embodiment of the present invention, and is a cross-sectional view taken along the line YY in FIG. FIG. 2 is a front view of the same. FIG. 3 is an enlarged cross-sectional view of the X portion in FIG. 1 of the same. FIG. 4 is an enlarged cross-sectional view showing another embodiment of the same. FIG. 5 is an enlarged cross-sectional view showing another embodiment of the same. FIG. 6A is a plan view showing an example of the same housing. FIG. 6A is an enlarged cross-sectional view showing a part of the same housing. FIG. 6C is an enlarged cross-sectional view showing a state in which a part of the adhesive of the same housing is supplied. FIG. 7 is a cross-sectional view showing an example of the irradiation process described above. FIG. 8 is a cross-sectional view showing an example of the same bonding process. FIG. 9A is a cross-sectional view showing an example of the adhesive arranging step of the same. FIG. 9B is a cross-sectional view showing a state in which the above-mentioned adhesive is arranged. FIG. 10A is a plan view showing an example of the housing according to the third embodiment. FIG. 10A is an enlarged cross-sectional view showing a part of the housing according to the third embodiment of the same. FIG. 10C is an enlarged cross-sectional view showing a state in which a part of the adhesive of the housing according to the third embodiment is supplied. FIG. 11 is an atomic force microscope photograph of the adhesive surface of the housing according to the first embodiment. FIG. 12 is an atomic force microscope photograph of the adhesive surface of the housing in Example 2 of the above.

Hereinafter, modes for carrying out the present invention will be described.

(Explanation of portable information terminal)
1 and 2 show the portable information terminal 100 of the present embodiment. The portable information terminal 100 is a portable electronic device such as a smartphone. Examples of other electronic devices include those shown in the above technical fields such as portable game machines and mobile phones. In such a portable information terminal 100, there is always a demand for smaller size, lighter weight, and lower price. In order to reduce the total weight as much as possible, the number of adhesive members is smaller, and the adhesive area is reduced due to the miniaturization. Adhesion is required. Furthermore, it is very important to reduce the production cost for lowering the price. An adhesive composed of a photocationic polymerization composition described later satisfies these demands.

The portable information terminal 100 has a display panel 6, a housing (frame) 10, a cover panel 20, an adhesive portion 5, and the like. The housing 10 and the cover panel 20 are assembled by being bonded by an adhesive portion 5. In addition to these, the portable information terminal 100 may include, for example, a battery 71, a circuit board 72, and the like.

The display panel (display unit) 6 is a liquid crystal panel or the like, and is a device for displaying characters and images. The display panel 6 is not limited to the liquid crystal panel, and may be an organic EL display panel. In this case, the backlight is unnecessary and the light is not always lit, which saves power, and the light emission is self-luminous by the organic EL, so that the total amount of light emitted is reduced, and the dye contained in the adhesive portion 5 required for shading. It is possible to reduce the amount of light and pigment, and there is an advantage that the amount of ultraviolet rays for curing and the degree of freedom in coating shape are increased.

The housing 10 is made of plastic or metal, and has a rectangular plate-shaped bottom portion 11 and a side wall portion 12 that rises from the peripheral end portion of the bottom portion 11 toward the front side. The space surrounded by the bottom portion 11 and the side wall portion 12 is formed as the accommodating portion 8. The housing 10 has an opening on the opposite side of the bottom 11.

The cover panel 20 has a panel main body 22 and a decorative printing unit 21. The panel body 22 is made of resin (plastic) or glass, and is formed in a rectangular plate shape. The panel body 22 has transparency to the extent that it does not pose a problem in practical use of the portable information terminal 100. The panel main body 22 is exemplified by a glass plate, but the present invention is not limited to this, and a resin plate such as highly translucent polycarbonate, acrylic, PMMA, or polyolefin, or a resin plate obtained by laminating or combining these resin plates may be used. If a resin plate is used, it can be configured as a curved display or an unbreakable display. When the panel body 22 is not a glass plate, it is common to apply an ultraviolet absorbing material from the viewpoint of weather resistance in addition to applying a hard coat so that it is not easily scratched, and the ultraviolet transmittance of the panel body 22 itself is high. Although it may almost disappear, even in this case, if it is a delayed curing type adhesive described later, it is possible to perform bonding. In addition, since the adhesive remains liquid in the uncured state, it can be adhered even if it is a curved surface, and if it has shape retention in consideration of viscosity and tincture, the thickness and width of the adhesive can be stabilized. It becomes possible to control and is preferable.

The panel main body 22 has a decorative printing portion 21 over the entire length of the peripheral end portion on the back surface thereof. The decorative printing unit 21 has a light-shielding property, and is for preventing the portion inside (the housing 10 side) from the decorative printing unit 21 from being seen through the peripheral end portion of the panel main body 22. Therefore, the decorative printing unit 21 makes it difficult to see the adhesive portion 5 and the like, and improves the design of the product. The decorative printing unit 21 is, for example, a printing film (ink film) formed by screen printing acrylic or urethane ink. In addition, the cover panel 20 is increasingly coated with a coating having high ultraviolet absorption to improve weather resistance, and when it is almost impossible to transmit light on the back side (housing 10 side) of the decorative printing portion 21. There is also.

A component 7 such as a battery 71 and a circuit board 72 is accommodated in the accommodating portion 8. Further, a display panel 6 is provided on the back surface of the cover panel 20 (the surface on the side of the accommodating portion 8) by adhesion or the like. The display panel 6 is also housed in the housing portion 8 on the front side of the component 7.

The adhesive portion 5 is interposed between the housing 10 and the cover panel 20 to bond the housing 10 and the cover panel 20. As shown in FIG. 3, the adhesive portion 5 is adhered to the housing 10 at the position of the recess 13 formed in the front side end portion (opening edge portion of the accommodating portion 8) of the side wall portion 12. The recess 13 is formed over the entire circumference of the side wall portion 12 so as to surround the opening of the accommodating portion 8. The adhesive portion 5 is provided over the entire length of the recess 13 in the circumferential direction. The adhesive portion 5 is adhered to the cover panel 20 at the position of the decorative printing portion 21. That is, the adhesive surface 10a of the housing 10 which is the bottom surface of the recess 13 and the adhesive surface 20a which is the back surface of the decorative printing portion 21 of the cover panel 20 are arranged to face each other, and are located between the adhesive surface 10a and the adhesive surface 20a. An adhesive portion 5 is provided.

Here, the dimension (thickness) T of the adhesive portion 5 in the direction opposite to the adhesive surface 20a of the cover panel 20 and the adhesive surface 10a of the housing 10 is preferably 30 to 200 μm, more preferably 50 to 150 μm. preferable. As a result, when the portable information terminal 100 is dropped, the impact applied to the adhesive interface between the housing and the cover panel can be easily absorbed by the adhesive portion 5, and the interface between the display panel 6 or the adhesive surface 10a and the adhesive portion 5 can be easily absorbed. You can reduce the damage to.

As shown in FIG. 4, it is preferable that one or both of the adhesive surface 20a of the cover panel 20 and the adhesive surface 10a of the housing 10 is an uneven surface. As a result, the adhesive area between the adhesive surfaces 10a and 20a and the adhesive portion 5 becomes larger than when the adhesive surfaces 10a and 20a are flat, and the adhesive strength between the cover panel 20 and the housing 10 can be increased. The roughness of the uneven surface may be at the nano level. Further, the uneven surface can be formed by providing a large number of protrusions on a flat surface. In this case, the convex can be formed into a hemisphere having a height of 50 nm and a diameter of 50 nm. When the adhesive surfaces 10a and 20a are made uneven, it is preferable that the dimension T of the adhesive portion 5 is larger than the height difference of the unevenness of the uneven surface. In order to make the adhesive surfaces 10a and 20a uneven, plasma cleaning treatment is performed after the housing 10 and the decorative printing layer 21 are formed.

Further, once the cover panel 20 and the housing 10 are peeled off, it becomes difficult to properly bond them again due to the uneven surface, which is effective as a countermeasure against imitation products. As shown in FIGS. 5, 6A and 6B, it is preferable that the protrusion 15 is formed on the adhesive surface 10a of the housing 10. One or a plurality of protrusions 15 may be provided. The plurality of protrusions 15 can be randomly provided on the housing 10, and can be provided at asymmetrical positions with the opening of the housing 10 interposed therebetween, for example. As shown in FIG. 6C, when the adhesive 3 is supplied to the adhesive surfaces 10a and 20a, the protrusion 15 is covered with the adhesive 3.

By providing such a protrusion 15 on the adhesive surface 10a of the housing 10, it becomes easy to prevent the appearance of a counterfeit product that is a copy of the structure of the housing 10. Specifically, when a genuine product having protrusions 15 is obtained, a mold is made from the housing 10, and a copy is made, the protrusions 15 abut with double-sided tape or the like and cannot be arranged on the adhesive surface 10a. Further, when the protrusions 15 are asymmetrically added, it becomes difficult to horizontally attach the cover panel 20 and the display panel 6. Therefore, unless an adhesive or the like having the same viscosity and chixiness used for the genuine product and having high shape retention is obtained, the protrusion 15 is exposed and the housing 10 and the cover panel 20 cannot be bonded together. In this way, it is possible to identify genuine products, modify them without permission, and take measures against counterfeit products.

Further, it is preferable that the adhesive portion 5 contains a coloring material. As the coloring material, one or both of the dye and the pigment can be used. For example, by incorporating a coloring material such as carbon black into the adhesive portion 5, the adhesive portion 5 can be made black. By adding black color to the adhesive portion 5 and bonding the housing 10 and the cover panel 20, it becomes difficult to visually recognize even if the adhesive portion 5 protrudes from the gap between the housing 10 and the cover panel 20. The design can be improved. Further, by coloring to a transmittance that does not allow light in the visible light region to pass through, it is possible to reduce or prevent light from leaking through the adhesive portion 5 when the user operates the portable information terminal 100 in a dark place. ..

Further, the adhesive portion 5 may contain a light absorbing material that absorbs a specific wavelength. This can be adjusted so as to intensively absorb the wavelength corresponding to the emission wavelength of the white LED of the backlight used for the liquid crystal panel or the like. Specifically, a white LED is used as the backlight, and in this case, it is visually recognized as white by combining the light of the light emitting sources of 450 nm, 540 nm, and 640 nm. Therefore, light can be efficiently absorbed by using a light absorbing material corresponding to 450 nm, 540 nm, and 640 nm, respectively. Further, since the light absorbing material absorbs only a specific wavelength and does not absorb much light in other wavelength bands, it does not absorb the wavelength of 365 nm, which is an active energy ray, and the adhesive 3 by ultraviolet rays while blocking visible light. Can be efficiently cured. As these materials, a material that absorbs a desired wavelength, such as a copper porphyrin complex, a cobalt porphyrin complex, iron oxide, copper oxide, metallic phthalocyanine, and an azo dye, may be appropriately combined and used.

In the above, it was decided to include a light absorbing material that absorbs a specific wavelength according to the emission wavelength of the backlight, but the present invention is not limited to this, and the housing 10 has a light emitting light source and is emitted from the light emitting light source. By containing a light absorbing material corresponding to the wavelength of light, it is possible to prevent the light emitted from the light source inside the housing 10 from leaking to the outside through the adhesive portion 5. For example, in a portable information terminal utilizing a head-mounted display, a wavelength of 635 nm may be used as the light source of the display unit. In this case, if Fe-phthalocyanine or the like is contained in the adhesive portion 5 as a light absorbing material in an appropriate amount. Good.

The content of the dye, pigment, or light absorbing material is preferably 0.005 to 1 wt% with respect to the total weight of the adhesive portion 5, but the type of coloring material and light absorbing material, the type of adhesive, and necessary It can be set as appropriate according to the light-shielding performance and the like.

(Explanation of adhesive)
In the portable information terminal 100, the housing 10 and the cover panel 20 are adhered to each other with an adhesive 3.

As the adhesive 3, an adhesive that is liquid immediately after irradiation with active energy rays such as ultraviolet rays and cures after a lapse of a predetermined time is used. A photocationic polymerization composition is used as such an adhesive 3.

The adhesive 3 which is a photocationic polymerization composition includes (A) a polyfunctional epoxy compound having two or more epoxy groups in one molecule (hereinafter, may be referred to as a component (A)) and (B) one molecule. It contains a monofunctional epoxy compound having one epoxy group (hereinafter, may be referred to as (B) component) and (C) a photocation generator (hereinafter, may be referred to as (C) component). ing. Further, in addition to the component (A), the component (B), and the component (C), the (D) oxetane compound (hereinafter, may be referred to as the component (D)) may be contained. Further, in addition to the component (A), the component (B), the component (C), and the component (D), an elastomer (hereinafter, may be referred to as a component (E)) may be contained. Such a photocationic polymerization composition has a delayed curing property and can be used as a delayed curing type adhesive. The photocationic polymerization composition of the present embodiment may contain any components such as various resins and additives, if necessary, as long as the delayed curability is not impaired.

The polyfunctional epoxy compound having two or more epoxy groups in one molecule as the component (A) is a compound having two or more functional groups in one molecule.

The component (A) contains at least one of a polyfunctional epoxy compound (A1) having a polyether skeleton in one molecule and a polyfunctional epoxy compound (A2) having no polyether skeleton in one molecule.

The polyfunctional epoxy compound (A1) is polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether and the like. The polyfunctional epoxy compound (A1) can be used alone or in combination of two or more of the above.

The polyfunctional epoxy compound (A2) is a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a hydrogenated bisphenol A type epoxy resin, a hydrogenated bisphenol F type epoxy resin, or a biphenyl type epoxy having a biphenyl skeleton. Resin, naphthalene ring-containing epoxy resin, anthracene ring-containing epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin having a dicyclopentadiene skeleton, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy Resins, brom-containing epoxy resins, aliphatic epoxy resins, aliphatic polyether epoxy resins, triglycidyl isocyanurate, and the like. The polyfunctional epoxy compound (A2) can be used alone or in combination of two or more of the above.

As used herein, the term "polyester skeleton" means the following chemical structural formula (1).

(In the chemical structural formula (1), R represents a hydrocarbon group having 1 to 30 carbon atoms, and m is an integer of 2 to 60.)
In particular, a polyether skeleton in which R is a hydrocarbon group having 1 to 10 carbon atoms is suitable because it has a remarkable effect of prolonging the delay time of the photocationic polymerization composition of the present embodiment.

The monofunctional epoxy compound having one epoxy group in one molecule which is a component (B) is a compound having one functional group epoxy group in one molecule.

The component (B) contains at least one of a monofunctional epoxy compound (B1) having a polyether skeleton in one molecule and a monofunctional epoxy compound (B2) having no polyether skeleton in one molecule.

The monofunctional epoxy compound (B1) is polyethylene glycol monoglycidyl ether, polypropylene glycol monoglycidyl ether, polytetramethylene glycol monoglycidyl ether and the like. The monofunctional epoxy compound (B1) can be used alone or in combination of two or more of the above.

The monofunctional epoxy compound (B2) is an alkyl glycidyl ether, a phenyl glycidyl ether, a paratarsial butyl phenyl glycidyl ether, a cresyl glycidyl ether, a biphenyl glycidyl ether, a glycol glycidyl ether, an alkylphenol glycidyl ether, a cyclohexene oxide, a fatty acid glycidyl ester, etc. is there. The monofunctional epoxy compound (B2) can be used alone or in combination of two or more of the above.

The photocation generator (photocationic polymerization initiator), which is the component (C), generates a strongly acidic chemical species when irradiated with active energy rays such as ultraviolet rays and visible light, and has an epoxy group (and, in some cases, an epoxy group). , Oxetane group) is an initiator for ring-opening self-polymerization. Such a photocation generator is not particularly limited, and may be, for example, an ionic photoacid generator or a nonionic photoacid generator. As the photocation generator, an ionic photoacid generator or a nonionic photoacid generator can be used alone, or an ionic photoacid generator and a nonionic photoacid generator can be used in combination.

The ionic photoacid generator includes onium salts such as aromatic diazonium salt, aromatic halonium salt and aromatic sulfonium salt, and organic metal complexes such as iron-allene complex, titanosen complex and arylsilanol-aluminum complex. One of the above-mentioned ionic photoacid generators can be used alone, or two or more of them can be used in combination.

Nonionic photoacid generators include nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimide phosphonate and the like. One of the above nonionic photoacid generators can be used alone, or two or more of them can be used in combination.

The oxetane compound as the component (D) is a curing accelerator that improves the curing steepness of the photocationic polymerization composition. Curing steepness refers to the property that the curing rate (viscosity increase per unit time) of the photocationic polymerization composition rapidly increases in a short time, and the time until curing is completed becomes faster. Such oxetane compounds include 3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, xylylenebis oxetane, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane and the like. Is. One of the above oxetane compounds can be used alone, or two or more of them can be used in combination.

The elastomer as the component (E) changes the physical properties and chemical properties of the cured product of the photocationic polymerization composition. That is, the cured product of the photocationic polymerization composition containing an elastomer has physical properties such as an increase in strength, a decrease in elastic modulus, and an improvement in elongation as compared with a cured product of a photocationic polymerization composition containing no elastomer. Changes in properties occur. Further, the cured product of the photocationic polymerization composition containing an elastomer has a polar group in the elastomer as an adherend (the first member 1 described later) as compared with the cured product of the photocationic polymerization composition containing no elastomer. And the change in chemical properties such as strengthening the chemical interaction with the second member 2) and the formation of a chemical bond with the adherend by the cationically polymerizable substituent in the elastomer. When such a change in chemical properties occurs, the adhesion (adhesive strength) between the cured product of the photocationic polymerization composition and the adherend may be improved.

The elastomer is formed of various polymer substances such as polyolefin-based, polystyrene-based, polyester-based, polyurethane-based, and silicone-based. Further, these elastomers are modified with highly polar substituents such as carboxyl groups, hydroxyl groups, cyano groups, thiol groups and amino groups, and are modified with cationically polymerizable substituents such as epoxy groups and oxetane groups. Then, it is more preferable. This is because the modified elastomer may have improved physical and chemical properties as compared with the case where it is not modified. One type of elastomer can be used alone, or two or more types can be used in combination.

The form of the elastomer in the photocationic polymerization composition is not particularly limited, and may be particles, may be in a state of being dissolved in the component (A) or (B), or may be in a state of being dissolved in the particles. Both forms may coexist.

The photocationic polymerization composition is prepared by containing the component (A), the component (B), the component (C), and the component (D). Further, the photocationic polymerization composition of the present embodiment is prepared by containing the component (A), the component (B), the component (C) and the component (D), if necessary, the component (E). .. Further, the photocationic polymerization composition of the present embodiment contains one or both of the polyfunctional epoxy compound (A1) and the monofunctional epoxy compound (B1).

The mixing ratio of the component (A) and the component (B) when preparing the photocationic polymerization composition is in the range of (A) component: (B) component = 90: 10 to 30:70 in terms of mass ratio. .. The delay time for curing the photocationic polymerization composition varies depending on the blending amount and type of each component, but in general, the smaller the component (B), the shorter the delay time, and conversely, the larger the component (B). The curing delay time is long.

The "delay time" refers to the time during which the photocationic polymerization composition remains liquid after being irradiated with active energy rays. In this case, "liquid" means that the viscosity of the photocationic polymerization composition is 50,000 Pa · s or less. Further, "curing" is a state in which the viscosity of the photocationic polymerization composition is larger than 50,000 Pa · s. If the delay time is long, it becomes possible to apply the photocationic polymerization composition and bond the members with the photocationic polymerization composition, and it can be said that the photocationic polymerization composition has a long pot life and is excellent in handleability.

If the amount of the monofunctional epoxy compound of the component (B) is less than the range of the above ratio, it is difficult to secure the delay time required for bonding and the like, it is difficult to obtain a sufficient pot life, and the handleability may be deteriorated. .. If the amount of the monofunctional epoxy compound of the component (B) is larger than the above ratio range, sufficient three-dimensional cross-linking is unlikely to occur in the cured product of the photocationic polymerization composition, so that the strength of the cured product of the photocationic polymerization composition is lowered. However, for example, it may be difficult to obtain sufficient adhesive strength.

A more preferable range of the ratio of the component (A) to the component (B) is the mass ratio in the range of component (A): component (B) = 85: 15-40: 60. A more preferable range of the blending ratio of the component (A) and the component (B) is the mass ratio in the range of (A) component: (B) component = 80:20 to 50:50.

Further, the total amount of the epoxy compounds having a polyether skeleton in one molecule contained in both or one of the components (A) and (B) (that is, the polyfunctional epoxy compound (A1) and the monofunctional epoxy compound (B1). ) Is preferably in the range of 0.01 to 90% by mass with respect to the total amount of the epoxy compounds of the component (A) and the component (B). More preferably, the total amount of the epoxy compounds having a polyether skeleton in one molecule contained in both or one of the components (A) and (B) is the epoxy compounds of the components (A) and (B). It is preferably in the range of 0.1 to 30% by mass with respect to the total amount of.

The blending amount of the component (C) is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the total mass of the component (A) and the component (B). If the proportion of the amount of the photocation generator compounded is less than 0.01 parts by mass with respect to the total mass of 100 parts by mass of the components (A) and (B), the photocationic polymerization composition is not sufficiently polymerized. Uncured parts may remain. When the proportion of the amount of the photocation generator compounded is more than 10 parts by mass with respect to the total mass of 100 parts by mass of the components (A) and (B), the curing reaction of the photocation polymerization composition becomes too fast and is delayed. Curability may be lost or deep curability may deteriorate (a non-uniform cured product).

The blending amount of the component (D) is preferably in the range of 0.01 to 30% by mass with respect to the total amount of the component (A) and the component (B). As a result, the viscosity increasing behavior of the photocationic polymerization composition during curing tends to be steeper. Therefore, when the photocationic polymerization composition is used as an adhesive, the curing time at room temperature after bonding can be shortened, which leads to shortening of the tact time and prevents misalignment at an early stage after bonding. , The work of the next process can be started immediately, and the production efficiency can be greatly improved. When the blending amount of the component (D) is 0.01% by mass or less, the above effect is small, and when it is 30% by mass or more, the curing is too fast and it becomes difficult to secure the delay time required for bonding.

When the photocationic polymerization composition contains the component (E), the blending amount of the component (E) is in the range of 0.1 to 50% by mass with respect to the total amount of the components (A) and (B). It is preferable to have. When the blending amount of the component (E) is within this range, the physical properties and chemical properties of the cured product of the photocationic polymerization composition can be easily changed. That is, if the blending amount of the component (E) deviates from the above range, it becomes difficult to change the physical properties and chemical properties of the cured product of the photocationic polymerization composition.

In the method for preparing the photocationic polymerization composition, for example, the component (A), the component (B), the component (C), the component (D), and, if necessary, the component (E) are blended in a predetermined mass ratio. Then, after adjusting the temperature to 20 to 100 ° C., the mixture is stirred with a homodisper or the like until it becomes uniform. As a result, a substantially transparent liquid photocationic polymerization composition can be obtained.

The photocationic polymerization composition of the present embodiment exhibits a delayed curability that remains liquid immediately after irradiation with active energy rays and cures after a lapse of a certain period of time. If such a photocationic polymerization composition is an adhesive, a delayed curing type adhesive can be obtained. The delayed-curing adhesive referred to here is an adhesive (that is, usable) that has a time grace to bond the members together by keeping the liquid for a certain period of time after applying the energy required to start the curing reaction. It is an adhesive that takes a long time), and the curing reaction proceeds sufficiently without applying additional energy such as light or heat after bonding, and the curing is completed. Further, the delayed curing type adhesive is activated only when it is irradiated with active energy rays, and the curing reaction is started. Therefore, it hardly cures unless it is irradiated with active energy rays, and is different from adhesives that spontaneously cure in a normal environment, such as solvent-type adhesives and cyanoacrylate-based instant adhesives.

In the photocationic polymerization composition of the present embodiment, the delay time varies depending on the composition of the photocationic polymerization composition, the irradiation intensity of active energy rays, the temperature of the photocationic polymerization composition, and the like. Assuming an actual bonding step using the photocationic polymerization composition of the present embodiment as an adhesive, active energy rays having a wavelength of 365 nm are irradiated at an irradiation amount of ^{50 mJ / cm 2 or more in an atmosphere at a temperature of 25 ° C.} After that, it is preferable that the liquid is liquid for 5 seconds or more and 60 minutes or less, and then cured within 12 hours. It is preferable to adjust the composition of the photocationic polymerization composition and the like so as to have such properties.

If the photocationic polymerization composition of the present embodiment remains in a liquid state after irradiation with active energy rays for less than 5 seconds, there is little grace for bonding and it is not realistic. If the liquid state is maintained for more than 60 minutes, there is a high possibility that the members will be misaligned and the time required to complete the curing will be long. Further, from the viewpoint of productivity, it is considered appropriate that the time from the completion of curing to the exertion of sufficient strength is within 12 hours. Of course, the shorter it is, the better. Further, it is appropriate that the irradiation amount of the active energy ray is 50 mJ / cm ^{2 or more.} If the irradiation amount is less than this, the amount of cation species generated by irradiation with active energy rays is too small, and the polymerization reaction may be stopped in the middle, resulting in poor curing. Further, if the irradiation amount of the active energy rays is large, the polymerization reaction becomes faster, so that the delay time and the curing completion time become shorter. There is also the effect of temperature. In the cationic polymerization of epoxy compounds, the amount of cation species generated has a positive correlation with the amount of irradiation with active energy rays, but basically light is not involved in the polymerization reaction and is affected by temperature. Therefore, the polymerization reaction becomes slow at a low temperature, and the polymerization reaction becomes fast at a high temperature. By applying this, the delay time can be lengthened by irradiating the active energy rays at a low temperature before bonding. It is also possible to shorten the curing time by heating after bonding.

The mechanism by which the photocationic polymerization composition of the present embodiment exhibits delayed curability is as follows. When the photocation generator absorbs the active energy ray, a cation is generated, and this cation initiates cation polymerization of the monofunctional epoxy compound of the component (B) contained in a large amount in the photocation polymerization composition. These monofunctional epoxy compounds are cationically polymerized with each other to increase the molecular weight, but since the molecule has only one epoxy group, the molecule does not crosslink three-dimensionally and the molecule grows linearly. Therefore, at the initial stage of the reaction, the viscosity hardly increases and remains liquid. In reality, the polymerization reaction is proceeding, but the viscosity does not increase and remains liquid, so it seems that there is almost no change from before irradiation with active energy rays. After that, as the polymerization further progresses and the molecular weight increases, the molecular chains of the polymer of the monofunctional epoxy compound are entangled with each other, and the viscosity increases. Further, a polyfunctional epoxy compound having two or more epoxy groups in one molecule of the component (A) also reacts to form a three-dimensional crosslinked structure, and finally curing is completed. In this mechanism, the active energy rays are only used to generate cations from the photocation generator to initiate the polymerization reaction, and after that, the polymerization reaction proceeds spontaneously even if the irradiation of the active energy rays is stopped. I will go. As a result, it exhibits a delayed curing behavior in which the liquid remains liquid for a certain period of time after irradiation with the active energy rays, and then curing is completed without irradiation or heating with the active energy rays.

Similar to the photocationic polymerization composition of the present embodiment, the photocurable resin composition exhibiting the behavior of a delayed-curing adhesive that remains liquid for a certain period of time after being irradiated with active energy rays and then completes curing. It has been known so far (see Reference 1). This is a technique in which the added polyether-based or thioether-based delayed curing agent traps the cation species generated from the photocation generator during light irradiation and delays the start of the cation polymerization reaction. The photocationic polymerization composition of the present embodiment is different from the technique of Patent Document 1 in that the next polymerization reaction (growth reaction) is controlled instead of the starting reaction. Further, since the technique of Patent Document 1 and the photocationic polymerization composition of the present embodiment are not contradictory techniques, it is presumed that more effective delayed curing is exhibited by combining them.

Further, in the photocationic polymerization composition of the present embodiment, at least one of the component (A) and the component (B) is simple with an epoxy compound having a polyether skeleton in one molecule (that is, a polyfunctional epoxy compound (A1)). Since it contains a functional epoxy compound (B1)), when an epoxy compound having a polyether skeleton and a cation are present in one molecule, the polyether skeleton according to the change in the concentration of the liberated cation according to the principle of Le Chatelier. And cations are associated and released. That is, when a large number of cations are present in the photocationic polymerization composition, the equilibrium is tilted toward the association side, and the number of free cations in the photocationic polymerization composition is reduced. On the other hand, when the number of free cations decreases, the equilibrium is inclined to the free side, and the free cations can be supplied into the photocationic polymerization composition.

In general, a photocation generator generates a cation when it absorbs active energy rays, and this cation acts on an epoxy compound to initiate cation polymerization. At this time, if the amount of cation generated is large, the polymerization reaction is fast, and if it is small, the polymerization reaction is slow.

In the delayed curing type photocationic polymerization composition of the present embodiment containing an epoxy compound and a photocation generator as essential components, a large amount of cations are generated from the photocation generator immediately after irradiation with active energy rays. Some of the generated cations polymerize the epoxy compound by reacting with the epoxy compound, while the remaining cations associate with the polyether skeleton so that the epoxy compound is not polymerized. After that, when the cation that polymerizes the epoxy compound is deactivated by the termination reaction, the amount of cation in the photocationic polymerization composition decreases, so that the equilibrium between the release / association of the polyether skeleton and the cation is inclined to the free side, and photocationic polymerization A new cation is supplied to the composition, and the polymerization reaction of the epoxy compound is continued.

The liberation and association of the polyether skeleton and the cation proceeds independently of the irradiation with active energy rays. Therefore, even after the irradiation of the active energy rays is completed, the cations are supplied as the cation concentration decreases due to deactivation, so that the polymerization reaction of the epoxy compound proceeds. As a result, the photocationic polymerization composition of the present embodiment has a delayed curability behavior in which the photocationic polymerization composition remains liquid for a certain period of time after being irradiated with the active energy rays, and then the curing is completed without irradiation or heating with the active energy rays. Is shown. In the photocationic polymerization composition of the present embodiment, the viscosity increase immediately after the start of the reaction (immediately after irradiation with active energy rays) becomes gentle, and the delay time becomes long. As a result, it is possible to take a long time (potential time) for adhering the members, and the handleability is excellent.

Further, in the photocationic polymerization composition of the present embodiment, since the polyether skeleton is incorporated in the molecule of the epoxy compound which is the component (A) or the component (B), it is poly even after the photocationic polymerization composition is cured. It is possible to reduce the bleed-out (exudation or embossment of the photocationic polymerization composition onto the surface of the cured product) of the ether skeleton portion. If a compound having a polyether skeleton instead of an epoxy compound is blended in the photocationic polymerization composition, it becomes difficult for the compound having a polyether skeleton to be incorporated into the cured product of the photocationic polymerization composition, and the cured product 3 Compounds having a polyether skeleton are easily separated from the dimensional network structure. Therefore, bleed-out of a compound having a polyether skeleton is likely to occur.

In the photocationic polymerization composition of the present embodiment, the mechanism of change in curing behavior due to the addition of the oxetane compound is presumed as follows. When the molecular weight of an epoxy compound or oxetane compound increases due to a growth reaction, the cation species existing at the end of the molecular chain move to the inside of the molecular chain due to chain transfer, so that the polymerization may be substantially stopped. .. It is known that such chain transfer is likely to occur in the case of epoxy compounds and relatively unlikely in the case of oxetane compounds (Toagosei Research Annual Report TREND 1999 No. 2 "Application of oxetane compounds to photocationic curing systems". "reference). Therefore, when the photocationic polymerization composition does not contain the oxetane compound, the thickening of the photocationic polymerization composition becomes slow due to the effect of the polymerization termination of the epoxy compound due to the chain transfer, whereas the photocationic polymerization composition When the substance contains an oxetane compound, polymerization termination due to chain transfer is unlikely to occur. Therefore, it is considered that the photocationic polymerization composition steadily increases the molecular weight and exhibits a steep increase in viscosity. That is, by containing the polyether skeleton and the oxetane compound, the initial viscosity increase is moderated, the viscosity is kept liquid for a certain period of time after irradiation with active energy, and then the effect of the oxetane compound causes a sharp increase in viscosity after a certain period of time. As a result, while ensuring a certain period of time for bonding, sufficient adhesive strength that can be used is generated in the subsequent process.

(Explanation of manufacturing method of portable information terminal)
In manufacturing the portable information terminal 100, an adhesive arranging step, an irradiation step, a bonding step, and a curing step are sequentially performed.

In the adhesive arranging step, the uncured adhesive 3 is provided on at least one of the housing 10 and the cover panel 20. In FIG. 7, the uncured adhesive 3 is provided on the adhesive surface 10a of the housing 10, but the present invention is not limited to this, and the uncured adhesive 3 may be provided on the adhesive surface 20 of the cover panel 20. The uncured adhesive 3 may be provided on both the adhesive surface 10a and the adhesive surface 20a. Any method such as coating or printing is adopted as the means for providing the uncured adhesive 3. The uncured adhesive 3 is provided, for example, in an amount of ^{5 to 50 mg / cm 2.}

In the irradiation step, the uncured adhesive 3 is irradiated with the active energy rays 4 after the adhesive placement step. The active energy ray 4 is ultraviolet light. Curing of the uncured adhesive 3 is started by irradiation with the active energy rays 4. Further, by this irradiation step, the amount of active energy rays 4 required for the uncured adhesive 3 to be cured to the adhesive portion 5 is irradiated. For the irradiation of the active energy ray 4, for example, an ultraviolet lamp or the like is used. The irradiation amount of the active energy ray 4 can be, for example, 50 to 3000 mJ / cm ² . In particular, when the adhesive 3 is colored, the transmittance tends to be low, and it is desirable to set the transmittance to 1000 to 3000 mJ / cm ^{2 in} order to obtain sufficient curing to the deep part of the applied adhesive 3.

In the bonding step, after the irradiation step, the housing 10 and the cover panel 20 are bonded via the uncured adhesive 3. In this case, as shown in FIG. 8, the cover panel 20 provided with the display panel 6 is brought closer from the front side of the housing 10. Then, the cover panel 20 is fitted (fitted) into the opening of the housing 10, and the uncured adhesive 3 is interposed between the adhesive surface 10a and the adhesive surface 20a.

In the curing step, the adhesive 3 is cured after the bonding step, and the housing 10 and the cover panel 20 are bonded with the cured adhesive 3 (adhesive portion 5). Curing of the adhesive 3 in the curing step is performed by the active energy rays 4 irradiated in the irradiation step. Therefore, in the curing step, it is almost unnecessary to irradiate the active energy ray 4. Further, even when the housing 10 and the decorative printing unit 21 do not allow the active energy rays 4 to pass through (for example, when the transmittance of ultraviolet rays is 5% or less), the adhesive 3 is cured.

The adhesive 3 used in the manufacturing method of the portable information terminal 100 as described above starts curing by the active energy ray 4, is liquid from the adhesive arranging step to the bonding process, and is formed by the active energy ray 4. It is a delayed curing type adhesive that cures in the curing process. By using the photocationic polymerization composition as described above as a delayed curing type adhesive, fine wire coating (for example, 0.2 to 2.0 mm fine wire coating) is possible, and the desired adhesive strength (for example, 1 MPa or more) is possible. (Adhesive strength) is ensured, and the tact time can be shortened (for example, the tact time can be shortened by several minutes to several hours).

In the above adhesive arranging step, as shown in FIG. 9A, the adhesive 3 can be linearly applied to the adhesive surfaces 10a and 20a from the nozzle 200 and supplied. In this case, as shown in FIG. 9B. In addition, in the cross section in the direction orthogonal to the longitudinal direction of the adhesive 3, the dimension H in the direction protruding from the adhesive surfaces 10a and 20a of the adhesive 3 is ½ or more of the dimension W in the direction orthogonal to the protruding direction. Is preferable. That is, when the adhesive width is 1 mm or less, the height dimension H of the adhesive 3 from the adhesive surfaces 10a and 20a is ½ or more (H ≧ 1 / 2W) of the width dimension W of the adhesive 3. Is preferable. More preferably, it is a case where the relationship of H ≧ 3/4 W is satisfied. By setting the cross-sectional shape of the adhesive 3 supplied to the adhesive surfaces 10a and 20a in this way, the adhesive 3 can easily spread to a uniform thickness in the bonding process between the housing 10 and the cover panel 20, and the adhesive portion The adhesive width of 5 (the width of the portion in contact with the adhesive surfaces 10a and 20a) can be stably secured. In the case of bonding with a width of 1 mm or less, securing a stable bonding width is to stably secure a originally small bonding area, and the bonding thickness has a very important meaning for shock absorption. Therefore, the adhesive strength between the housing 10 and the cover panel 20 is increased. The viscosity and thixophilicity of the adhesive 3, the coating speed of the adhesive 3, the discharge pressure (discharge air pressure), and the like can be adjusted so that the adhesive 3 has a predetermined cross-sectional shape as described above. In adjusting the viscosity and thixophilicity of the adhesive 3, for example, fumed silica can be blended in an appropriate amount. When the protrusion 15 is formed on the adhesive surface 10a, the protrusion 15 is covered with the adhesive 3. As a result, even if the protrusions 15 are formed, the adhesive 3 can be sufficiently brought into contact with the adhesive surfaces 10a and 20a to be cured, and the adhesive strength between the housing 10 and the cover panel 20 is enhanced.

Further, the adhesive 3 is preferably applied linearly over the entire length of the adhesive surface 10a of the housing 10. In this case, the adhesive 3 can be used to form a frame that surrounds the opening of the housing 10. Further, it is preferable that the adhesive 3 is continuously applied without a seam as in a single stroke. In this case, when the adhesive has a waterproof function due to hydrophobicity or the like, the housing 10 and the cover panel 20 are bonded to each other with almost no gap by forming a frame-shaped adhesive portion 5 that surrounds the opening of the housing 10. It is possible to improve the waterproofness of the portable information terminal 100. In order to improve the waterproofness of the portable information terminal 100, it is conceivable to provide a packing between the housing 10 and the cover panel 20 without forming the adhesive portion 5, but the portable information terminal 100 is made smaller. If it becomes, it is necessary to make the packing small, and it may not be possible to secure sufficient waterproofness.

In order to secure the adhesive strength and waterproofness of the housing 10 and the cover panel 20, and further to secure the curability of the adhesive 3, the width dimension W of the adhesive 3 is preferably 0.2 to 1 mm.

In supplying the adhesive 3 into the predetermined shape as described above, the adhesive 3 preferably has a viscosity of 30 to 800 Pa · s and a thixo index of 1.5 to 15.0.

Hereinafter, the present invention will be specifically described with reference to Examples. It should be noted that the material used in the examples is an example, and a material configured by using another material based on the material having the characteristics shown in the present specification is included in the present invention.

(Example 1)
As the adhesive, a delayed curing type adhesive was used, which remained in a liquid state immediately after irradiation with active energy rays and cured after a certain period of time. As this adhesive, XV7811A2 manufactured by Panasonic Corporation was used, and the viscosity was adjusted to 100 Pa · s and the Chixo index was 4.0.

XV7811A2 is a bisphenol A type bifunctional epoxy resin jER828 (manufactured by Mitsubishi Chemical Corporation, trade name) 50 parts by mass, an aromatic monofunctional epoxy resin mp-CGE (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., trade name) 30 parts by mass, and a polyether. Frame-containing monofunctional epoxy resin EX145 (manufactured by Nagase ChemteX Corporation, trade name) 20 parts by mass, aromatic sulfonium salt-based photocation generator SP170 (manufactured by ADEKA, trade name) 3 parts by mass, carboxyl group-containing nitrile butadiene rubber XER32C It is composed of 5 parts by mass (manufactured by JSR, trade name) and 2 parts by mass of epoxy group-containing silicone elastomer powder EP2601 (manufactured by Toray Dow Corning, trade name).

^{This delayed-curing adhesive is activated by irradiating 100 mJ / cm 2} of ultraviolet rays from an LED UV light source (LC-L5 manufactured by Hamamatsu Photonics) with a center wavelength of 365 nm, and is 300 Pa · s or less within 5 minutes. After 30 minutes, the viscosity becomes 50,000 Pa · s or more and is cured to form an adhesive portion. The bonded portion exhibits a shear bond strength of 1 MPa or more.

The housing was molded for mobile phones using polycarbonate (Teijin Panlite). The cover panel uses a tempered glass plate that is durable against scratches as the panel body, and a decorative printing layer is applied to the panel body so that the adhesive portion cannot be seen. A display panel (liquid crystal panel) was attached to the cover panel so as to exclude the decorative printing part. Due to the decorative printing layer, the inside cannot be seen through the peripheral edge of the cover panel, and the adhesive state cannot be seen, so the user does not see the adhesive part, and it is possible to supply products with excellent design and design. .. On the other hand, the transmittance in the ultraviolet to visible light region of the adhesive surface of the cover panel is remarkably lowered to 0 to 5%. The light transmittance of the decorative printing layer of Example 1 was 0%. Further, the adhesive surface of the housing is formed to have a width of 0.5 mm by making the adhesive width as narrow as possible in order to secure an effective area for the display panel.

Next, using the above-mentioned adhesive, housing and cover panel (with display panel), the adhesive placement step, the irradiation step, the bonding step and the curing step were sequentially performed.

The adhesive was applied to the adhesive surface (surface roughness Ra of 2 nm) of the housing by a coating device. As a coating device, a dispense robot (SM-200DS manufactured by Musashi Engineering Co., Ltd.) and a pulse air type dispenser (ML-5000X2 manufactured by Musashi Engineering Co., Ltd.) were used. At this time, by adjusting the discharge air pressure and the coating speed, the adhesive was applied with a height dimension H of 0.25 mm and a width dimension W of 0.4 mm. The adhesive was applied in a frame shape so as to surround the opening of the housing over the entire circumference.

Next, the entire applied adhesive was irradiated with ultraviolet rays as active energy rays. At this time, LC-L5 (straight type 365 nm UV-LED light source) manufactured by Hamamatsu Photonics Co., Ltd. was used as the light source of ultraviolet rays, and the irradiation amount was 100 mW / cm ² × 1 second = 100 mJ / cm ² .

Then, the cover panels were attached within 1 minute after the irradiation with ultraviolet rays. After bonding, the mixture was allowed to stand for 30 minutes to cure the adhesive to form an adhesive portion. After that, it was confirmed that when a force of 100 N was applied as a force to peel the housing and the cover panel in a direction perpendicular to the adhesive surface, the housing and the cover panel were not peeled off. When a force of up to 120 N was applied, the housing and the cover panel could be peeled off.

The adhesive contains a polyfunctional epoxy compound having two or more epoxy groups in one molecule and a monofunctional epoxy compound having one epoxy group in one molecule, and has a polyfunctional skeleton having a polyether skeleton. Alternatively, it has delayed curability by containing a monofunctional epoxy resin. Further, since the adhesive contains an oxetane compound, a sharp increase in viscosity occurs after bonding, and the adhesive can be cured in a short time of 30 minutes. By using such a delayed curing type and ultraviolet curing type adhesive, it was possible to bond the cover panel and the housing, which do not easily transmit light to the adhesive surface. Further, since the adhesive has a viscosity of 100 Pa · s and a thixo index of 4.0, the shape after application is not easily deformed, and the adhesive width (area) can be stably secured.

When the obtained portable information terminal was immersed in water at a depth of 1 m, no water intrusion was observed inside the housing, and the inside of the housing could be waterproofed. After this test, when the cover panel was peeled off with a large force, an adhesive portion was formed with a height of 0.2 mm and a width of 0.5 mm, and the adhesive surface could be adhered uniformly over the entire circumference. In addition, even after the adhesive is crushed by bonding, the shape retention of the adhesive is good, the adhesive does not invade other electronic parts inside, and a very good adhesive state can be realized. The thickness of the adhesive was also uniformly formed over the entire circumference of the housing.

(Example 2)
In Example 1, the adhesive surface of the housing and the adhesive surface of the cover panel were subjected to plasma cleaning treatment to add a fine uneven structure to the surface of the adhesive surface. A portable information terminal was manufactured in the same manner as in Example 1 in other configurations. A plasma cleaner PDC200 manufactured by Yamato Scientific Co., Ltd. was used for the plasma cleaning treatment, Ar gas was introduced, and the treatment was performed at 200 W for 2 minutes. After the housing and the cover panel were bonded together, the mixture was allowed to stand for 30 minutes to cure the adhesive to form an adhesive portion. After that, even if a force of 150 N was applied as a force to peel off the housing and the cover panel in the direction perpendicular to the adhesive surface, the housing and the cover panel could not be peeled off. By making the adhesive surface an uneven surface by plasma cleaning treatment, the housing and the cover panel could be firmly adhered.

When the obtained portable information terminal was immersed in water at a depth of 1 m, no water intrusion was observed inside the housing, and the inside of the housing could be waterproofed. Even if an uneven structure with a surface roughness Ra of 60 nm and an uneven height difference of 100 nm or less is formed on the adhesive surface, waterproofing can be ensured because the adhesive adheres along the shape, and the adhesive strength is also flat. I was able to make it dramatically larger than that.

Note that FIG. 11 shows an atomic force microscope photograph of the adhesive surface of the housing in Example 1. Further, FIG. 12 shows an atomic force microscope photograph of the adhesive surface of the housing in Example 2. In Example 2, the height difference of the unevenness of the adhesive surface is larger than that in Example 1 due to the plasma cleaning treatment (Example 3).
In Example 2, as shown in FIGS. 10A and 10B, a protrusion 15 having a height h of 0.1 to 0.15 mm and a width w of 0.1 to 0.2 mm was added to the adhesive surface 10a of the housing 10. .. The protrusions 15 were formed at the same time as the housing 10 was molded. As shown in FIG. 10C, the adhesive 3 was applied so that the height dimension H was 0.3 mm and the width dimension W was 0.4 mm. A portable information terminal was manufactured in the same manner as in Example 2 in other configurations. After that, even if 150 N was applied as a force to peel the housing and the cover panel in the direction perpendicular to the adhesive surface, the housing and the cover panel were not peeled off.

When the obtained portable information terminal was immersed in water at a depth of 1 m, no water intrusion was observed inside the housing, and the inside of the housing could be waterproofed. Even if there are protrusions on the adhesive surface, by applying an adhesive with high shape retention at the width height or width of the protrusions, it is possible to wrap both the protrusions and the uneven structure with the adhesive, ensuring waterproofness. I was able to. Further, by providing this protrusion, it is possible to prevent the appearance of a counterfeit product that is a copy of the structure of the housing.

(Example 4)
The adhesive used in Example 1 contained a black dye. In the adhesive containing no dye, the transmittance of visible light is about 40% on the long wavelength side, but the transmittance decreases as the wavelength becomes shorter, and decreases to 10% at 400 nm. The ultraviolet light irradiated in the irradiation step was 365 nm, and the dye-free adhesive at that wavelength had a transmittance of 8%. To adjust the dye content, after applying the dye-containing adhesive to the adhesive surface, the transmittance of ultraviolet rays with a wavelength of 365 nm in the thickness direction (from the top to the bottom) of the adhesive is about 1%. did. When the portable information terminal was manufactured in the same manner as in the first embodiment, the housing and the cover panel could be bonded to each other in the same manner as in the first embodiment.

By adding a black color to the adhesive and sticking the housing and the cover panel together, it becomes difficult to see even if the adhesive part protrudes from the gap between the cover panel and the housing, improving the design. I was able to do it. Further, the adhesive has high shape retention, and even if the adhesive is crushed and adhered, the housing and the cover panel can be adhered with an adhesive portion having a uniform width of 0.5 mm. Therefore, the thickness of the adhesive portion in the direction perpendicular to the adhesive surface makes it difficult for visible light to pass through in the horizontal direction, so that the backlight of the liquid crystal panel or the like tends to leak from the gap between the cover panel and the housing. It has become possible to block light. This makes it possible to reduce or prevent light from leaking through the adhesive portion when the user operates the portable information terminal (mobile phone) in a dark place.

When the content of the dye with respect to the total weight of the adhesive is 0.005 wt% or more, the adhesive can be visually recognized as black, and when the dye is less than 1 wt%, the adhesive transmits ultraviolet light and blocks visible light. Was done. Further, with 1 wt% of the dye, it was difficult to transmit ultraviolet rays to the lower part of the adhesive even if the height dimension of the adhesive was 0.05 mm. From this, the range of the dye content is preferably 0.005 to 1 wt%. Further, when the transmittance of visible light (400 to 680 nm) of the bonded portion was set to 5% or less, the leakage of light from the backlight was greatly reduced, and the light could be almost blocked. However, when less than 1% of ultraviolet rays having a wavelength of 365 nm can reach the bottom surface (interface with the adhesive surface) of the adhesive, the adhesive on the bottom surface may be uncured and may not be sufficiently bonded. Therefore, it is preferable that the transmittance of ultraviolet rays having a wavelength of 365 nm to the bottom surface of the adhesive applied to the adhesive surface is 1% or more.

(Example 5)
Instead of the black dye used in Example 4, a light absorbing material that absorbs a specific wavelength was used. This light absorbing material was adjusted so as to intensively absorb the wavelength corresponding to the emission wavelength of the white LED of the backlight used for the liquid crystal panel or the like. Specifically, a white LED is used as the backlight LED, but it is visually recognized as white by combining the light of a light emitting source of 450 nm, 540 nm, and 640 nm. Therefore, the light of 450 nm, which is the emission wavelength of the LED, is absorbed by Yamada Chemical Co., Ltd. FDB-004, the light of 540 nm is absorbed by the company FDG-003, and the wavelength near 640 nm is manufactured by Sanyo Dye Co., Ltd. Three kinds of light absorbing materials were blended so as to be absorbed by using O-270. FDB-004 can efficiently absorb light of 450 ± 50 nm, FDG-003 can absorb light of 540 nm ± 40 nm, and O-270 can efficiently absorb light of ± 40 nm. That is, it is possible to efficiently absorb the emission wavelength of the LED, and it is possible to perform coloring in which absorption does not occur so much at the wavelength of the active energy ray of 365 nm.

The above three types of light absorbing materials are contained in the adhesive in an amount of 0.003 wt% each, and light in the visible light region can be efficiently absorbed by the adhesive portion, and the transmittance of visible light can be suppressed to 5% or less. It was. The adhesive portion at this time was visually recognized as black. Further, since these light absorbing materials absorb only a specific wavelength and do not absorb much light in other wavelength bands, they do not absorb light having a wavelength of 365 nm, which is an active energy ray. Therefore, it is possible to efficiently cure the adhesive by ultraviolet rays while blocking visible light, and even if the height dimension H of the adhesive applied to the adhesive surface is 0.25 mm, the adhesive can be cured. Light of 5% or more and 365 nm could be transmitted to the lower surface, and the transmittance of visible light could be suppressed to 5% or less.

(Example 6)
An oxetane compound (OXMA manufactured by Ube Kosan Co., Ltd.) was added to the delayed-curing UV adhesive used in Example 1 in an amount of 20% by mass based on the total amount of the epoxy compounds to prepare an adhesive. Then, in the same manner as in Example 1, the cover panel was attached to the housing within 1 minute after the irradiation with ultraviolet rays. Almost no increase in viscosity was observed in the adhesive after irradiation, and when the adhesive was cured by allowing it to stand for 20 minutes after bonding, the force to peel off the housing and cover panel in the direction perpendicular to the bonding surface was 100 N. In addition, it was confirmed that the housing and the cover panel did not come off. It is considered that this is because the addition of the oxetane compound to the adhesive caused steeper curing and achieved adhesion exceeding 100 N in a short time. The same effect could be obtained when OXT-221, 121, 212, 101 manufactured by Toagosei Co., Ltd. was used as the oxetane compound.

(Comparative Example 1)
A portable information terminal was manufactured in the same manner as in Example 1 using an ultraviolet curable resin 8833 manufactured by Kyoritsu Chemical Co., Ltd. as an adhesive.

Since the adhesive has a low viscosity of 26 Pa · s, the height dimension of the shape when applied is non-uniform at 0.1 mm or less, and the adhesive is wet and spread on the adhesive surface of the housing. When the surface was hardened by directly irradiating ultraviolet rays after applying the adhesive, the cover panel could not be adhered well. Further, when the cover panel was fitted to the housing and then irradiated with ultraviolet rays, the ultraviolet rays did not pass through the cover panel and the adhesive could not be cured. In addition, since the adhesive has a low viscosity and spreads, it may flow into a light guide plate or the like of a liquid crystal member, and the commercial value may be significantly reduced. The irradiation amount of ultraviolet rays having a wavelength of 365 nm irradiated from the cover panel side for curing was 500 mW / cm ² × 12 seconds = 60,000 mJ / cm ² .

(Comparative Example 2)
A portable information terminal was manufactured in the same manner as in Example 2 using an ultraviolet curable resin 8833 manufactured by Kyoritsu Chemical Co., Ltd. as an adhesive.

(Comparative Example 3)
A portable information terminal was manufactured in the same manner as in Example 3 using an ultraviolet curable resin 8833 manufactured by Kyoritsu Chemical Co., Ltd. as an adhesive.

(Comparative Example 4)
A double-sided adhesive tape (No. 57115B manufactured by Nitto Denko KK) was used instead of the adhesive to manufacture a portable information terminal in the same manner as in Example 1.

No. 57115B is a double-sided adhesive tape in which acrylic adhesive layers are formed on both sides of a polyolefin-based foam film, and is widely used for assembling mobile phones.

It could not be cut out with a width of 0.5 mm to fit the width of the adhesive surface of the housing. Since it was cut out with a width of 1 mm, it was possible to bond by widening the adhesive portion between the adhesive surface of the housing and the adhesive surface of the cover panel.

(Comparative Example 5)
A double-sided adhesive tape (No. 57115B manufactured by Nitto Denko KK) was used instead of the adhesive to manufacture a portable information terminal in the same manner as in Example 2.

In this case, since the adhesive surface is subjected to plasma cleaning treatment to form an uneven surface, the double-sided adhesive tape cannot be adhered to the adhesive surface, and when the portable information terminal is immersed in water, it is inside the housing. It was confirmed that water had infiltrated, and it was not possible to maintain waterproofness.

(Comparative Example 6)
A double-sided adhesive tape (No. 57115B manufactured by Nitto Denko KK) was used instead of the adhesive to manufacture a portable information terminal in the same manner as in Example 3.

In this case, since there is a protrusion on the adhesive surface, a gap is created between the double-sided adhesive tape and the adhesive surface at the protrusion, the cover panel is tilted, and the housing and the cover panel can be accurately bonded to each other. There wasn't.

(Evaluation)
The adhesiveness, drop impact resistance, and waterproofness of Examples 1 to 3 and Comparative Examples 1 to 6 were evaluated.

The adhesiveness is marked with a circle when the housing and the cover panel are bonded at the correct position, and marked with a cross when the housing and the cover panel are not bonded at the correct position.

As for the drop impact resistance, when the portable information terminal was dropped 100 times from a height of 70 cm, it was confirmed whether the adhesive part between the housing and the cover panel was peeled off, and if it was not peeled off, ○, peeling was observed. The thing was set as x.

The waterproof property is marked with a circle when the portable information terminal is immersed in water at a depth of 1 m and no water intrusion is observed inside the housing, and a cross when there is water intrusion.

In the above embodiment, an adhesive having a viscosity of 100 Pa · s was used, but the viscosity may be further increased in order to further increase the shape retention. For example, silica powder # 100 manufactured by Maruto Co., Ltd. may be added to increase the viscosity of the adhesive so that it exceeds 500 Pa · s. In this case, the shape after application hardly changes, but since the application pressure of the pulse air type dispenser becomes very high, it is desirable to appropriately adjust it according to the capacity of the adhesive application device. However, if the viscosity exceeds 800 Pa · s, it becomes difficult to apply with an air-type dispenser that is usually used, and a special dispenser device such as a MONO-type pump is required.

Further, in the above embodiment, a delayed curing type adhesive that cures at an ultraviolet wavelength of 365 nm was used, but the present invention is not limited to this, and a delayed curing type adhesive that cures at other wavelengths such as 350 nm and 320 nm. You may.

Further, in the above embodiment, the plasma cleaning treatment was set to 2 minutes to form an uneven surface having a surface roughness Ra of 100 nm or less, but even if the plasma cleaning treatment time is appropriately changed and the treatment is performed for 5 seconds to 5 minutes. good. If the treatment time is less than 5 seconds, the uneven structure is unlikely to be formed on the adhesive surface, and the effect is likely to occur from 5 seconds or more. By lengthening the plasma cleaning treatment time, the uneven structure tends to have a surface roughness Ra of 10 to 300 nm, and if the treatment time is 5 minutes or more, the unevenness may stick to each other and become large. The influence of heat and the like also increases, and the resin cover panel may cause great damage.

100 Portable information terminal 3 Adhesive 5 Adhesive part 6 Display panel 10 Housing 10a Adhesive surface 15 Protrusion 20 Cover panel 20a Adhesive surface

Claims (6)

The housing that houses the display panel and
A cover panel that protects the display panel and
A portable information terminal including an adhesive portion for adhering the housing and the cover panel.
The housing has protrusions on its adhesive surface and has protrusions.
The protrusions are provided at asymmetrical positions across the opening of the housing.
The adhesive portion is a portable information terminal formed by covering the protrusion. In claim 1,
At least one of the adhesive surface of the cover panel and the adhesive surface of the housing is an uneven surface.
A portable information terminal in which the size of the adhesive portion in a direction facing the adhesive surface of the cover panel and the adhesive surface of the housing is 30 to 200 μm. In claim 2,
The uneven surface is a portable information terminal having a height difference of 100 nm or less. In any one of claims 1 to 3,
The adhesive portion is a portable information terminal containing at least one of a dye or a pigment. In any one of claims 1 to 4,
The adhesive portion is a portable information terminal containing a light absorbing material that absorbs light having a specific wavelength corresponding to the emission wavelength of the display panel. In any one of claims 1 to 5,
The adhesive portion is a cured product of the photocationic polymerization composition.
The photocationic polymerization composition contains (A) a polyfunctional epoxy compound having two or more epoxy groups in one molecule, and (B) a monofunctional epoxy compound having one epoxy group in one molecule. And
A portable information terminal in which at least one of the component (A) and the component (B) has a polyether skeleton in the molecule.

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