JPH111666A - Curing method for adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the curing time of a thermosetting adhesive in bonding a lighttransmitting object to a desired place by incorporating a cabron black into the adhesive and by irradiating it with infrared rays through the light- transmitting object after it is used for bonding. SOLUTION: The temp. rise rate of an adhesive contg. a carbon black in accelerating the cure of the adhesive with heat energy is higher than that of the object to be bonded. Pref., 0.1-10 pts.wt. carbon black is incorporated into 100 pts.wt. adhesive. Pref., near-infrared rays (having wavelengths of 0.75-1.5 μm) are used for the curing. An infrared ray generation apparatus (e.g. a near- infrared ray radiation lamp) is installed so that infrared rays are radiated selectively to the adhesive and not to the whole of a lens. a lamp, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for curing an adhesive for bonding a light-transmitting adherend using a thermosetting adhesive.

[0002]

2. Description of the Related Art A vehicle such as an automobile is provided with a plurality of lamps such as a head lamp, a fog lamp and a tail lamp, and these lamps are formed by fixing a lens to a lamp housing. Hot melt adhesives have been used to secure the lens to the lamp housing. That is, the fixing portion of the lamp housing to which the lens is fixed is formed in a U-shape, and a high-temperature hot melt adhesive is poured into the U-shaped groove, and then the fixing portion of the lens (fitted into the U-shaped groove). Part) is pressed into the U-shaped groove to fix the lens.

[0003]

When a hot-melt adhesive is used to fix the lens as described above, the hot-melt adhesive is poured into the U-shaped groove of the lamp housing, and the lens is pressed into this groove. Since the lens can be fixed simply by performing the bonding, the productivity is excellent. However, regarding the adhesiveness, it is better to perform the bonding using a structural adhesive, that is, a thermosetting adhesive such as an epoxy-based adhesive. For this reason, the lens may be bonded using a thermosetting adhesive, but the thermosetting adhesive is excellent in adhesiveness, but takes time to cure. As a means for accelerating the curing of the adhesive, there is a means for increasing the temperature of the adhesive by thermal energy, and for example, there are heating means such as hot air, far infrared rays, induction, and dielectric heating. However, in the case of using hot air, for example, hot air is applied to the entirety of the lamp housing with the lens attached thereto, and the temperature of the entire adhesive is increased by raising the temperature of the entire body. As a result, for example, if the lamp housing or the like is formed of a resin or the like having poor heat resistance, the resin, that is, the lamp housing or the like may be deformed. For example, the heat resistance temperature of acrylic resin and polycarbonate is about 8 each.
0 ° C., about 100 ° C. Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an adhesive having excellent productivity by improving the curing time of the adhesive when bonding using a thermosetting adhesive. It is to provide a curing method.

[0004]

In order to achieve the above object, a method for curing an adhesive according to the present invention comprises the steps of: Carbon black is added to the curable adhesive, and the adherend is adhered to a desired location using the carbon black-added adhesive, and then the adhesive is irradiated with infrared rays through the adherend. When the addition amount of the carbon black is 0.1
It is preferably from 10 to 10 parts by weight. Preferably, the infrared light is a near infrared light.

As described above, by adding carbon black to a thermosetting adhesive, when the temperature of the adhesive is increased by thermal energy to accelerate the curing of the adhesive, the temperature of the adherend is increased. In comparison, the temperature rise of the adhesive is promoted. In addition, infrared rays are irradiated to promote the curing of the adhesive by the heat energy. The infrared rays penetrate the adherend having light transmittance and irradiate the adhesive, that is, mainly irradiate the adhesive part. Therefore, the temperature rise of the adhesive can be further promoted. Therefore, it is possible to improve the curing time when the thermosetting adhesive is used.

[0006]

Embodiments of the present invention will be described below in detail. The thermosetting adhesive used in the present invention is used for lamps of vehicles such as automobiles, for example, headlamps, fog lamps, tail lamps and the like. Specifically, it is used when bonding the lens to the lamp housing, and may be any type as long as the lens and the lamp housing can be bonded, for example, an epoxy-based adhesive, a urethane-based adhesive, and a silicone-based adhesive. An adhesive and the like can be mentioned. Carbon black is added to this thermosetting adhesive, so that when the temperature of the thermosetting adhesive is raised by thermal energy, the temperature rise can be promoted as compared with the case where carbon black is not added. The addition amount of carbon black is 0.1 to 10 with respect to 100 parts by weight of the thermosetting adhesive.
If it is less than 0.1 part by weight, the desired curing time will not be sufficiently improved, and if it exceeds 10 parts by weight, there will be no further effect and it will be difficult to knead the adhesive.

The temperature rise due to the thermal energy of the thermosetting adhesive is performed by irradiating infrared rays. The infrared rays may be of any wavelength as long as the temperature can be raised.
Preferably, near infrared rays (wavelength 0.75 to 1.5 μm) are desirable. The device that generates infrared rays may be any device that generates infrared rays, particularly near infrared rays, such as a near-infrared irradiation lamp. Irradiation method is
The infrared ray is irradiated on the adhesive by transmitting the light through a lens as an adherend so that the adhesive to be cured is irradiated with the infrared ray. That is, an infrared ray generating device, for example, a near-infrared ray irradiation lamp is provided so that the adhesive is selectively irradiated with infrared rays instead of irradiating the entire lens or lamp housing with infrared rays.

Next, a case where the lens is fixed to the lamp housing will be described. The lens is a light-transmitting adherend, and is formed into a predetermined shape using glass, acrylic resin, polycarbonate resin, or the like. This lens is bonded to a desired portion of the lamp housing, that is, a fixing portion (U-shaped groove) to which the lens of the lamp housing is fixed. For this bonding, a predetermined amount of carbon black (0.1
-10 parts by weight) added thermosetting adhesive (carbon black added adhesive) is used. This adhesive is applied to the lamp housing or the like. There are three methods for applying the adhesive only to the fixing portion of the lamp housing, applying the adhesive to both the lens and the lamp housing, and applying the adhesive only to the fixing portion of the lens. Yes, it can be arbitrarily selected according to the shape of the fixing portion of the lens or the lamp housing.
For example, when applying an adhesive only to the fixing portion of the lamp housing, a carbon black-added adhesive is applied to the fixing portion, and then the fixing portion of the lens is crimped to the fixing portion. Then, a near-infrared irradiation lamp is provided so that the near-infrared ray passes through the lens having light transmittance and is irradiated on the adhesive, and the near-infrared ray is irradiated on the lens from the lamp. As a result, near infrared rays are transmitted through the lens and are selectively irradiated on the adhesive, and the temperature of the adhesive increases. As a result, the adhesive is cured, and the lens is bonded (fixed) to the lamp housing.

As described above, since the carbon black is added to the thermosetting adhesive for bonding the lens and the lamp housing, the curing of the adhesive is promoted.
When the temperature of the adhesive is increased by the heat energy, the temperature of the adhesive is increased more than the temperature of the lens or the lamp housing. That is, in order to accelerate the curing of the adhesive, for example, by irradiating near-infrared rays to the entire lens or lamp housing and raising the temperature of the entire lens, the bonding becomes higher than that of the lens or lamp housing. The temperature rise of the agent is faster. In addition, near-infrared rays are irradiated to accelerate the curing of the adhesive. At this time, since the near-infrared rays are selectively irradiated to the adhesive via a lamp, the temperature rise of the adhesive can be further promoted. .

Therefore, the lens is fixed to the lamp housing by using a thermosetting adhesive to which a predetermined amount of carbon black has been added, and by irradiating the adhesive with near infrared rays selectively through the lens. The curing time of the adhesive can be improved without deformation of the lens, the lamp housing, and the like, and the productivity is improved. In addition, when irradiating near-infrared rays to accelerate the curing of the adhesive, the adhesive is selectively irradiated with near-infrared rays through a lens. Can be applied, and the productivity is further improved. In other words, when near-infrared light is applied to the entire lens, lamp housing, etc., the size of the device increases to raise the temperature of the whole, making it difficult to lay it on existing production lines. In the case of irradiating the adhesive, it is only necessary to irradiate the adhesive with near-infrared light, so that the size is smaller than that of a device that raises the temperature of the whole, and it is easy to lay it on an existing production line. Further, by using the near infrared ray for raising the temperature of the adhesive, the temperature rise of the adhesive can be promoted in a shorter time as compared with the far infrared ray or the like.

Next, the case where carbon black is added to the thermosetting adhesive will be specifically described. Two acrylic plates (50 × 50) having a thickness of 3 mm were overlaid as shown in FIG. The carbon black-added thermosetting adhesive 2 was positioned in the gap between the acrylic plates 1 and 1 (that is, two acrylic plates were bonded with the adhesive), and the gap t between the acrylic plates was 0.5 mm. . The thermosetting adhesive 2 is Epototo YD-128 (epoxy resin, Toto Kasei Co., Ltd.)
100 parts by weight), 100 parts by weight of Goodmide G624 (aminopolyamide resin, manufactured by Toto Kasei Co., Ltd.), and 50 parts by weight of Gerton 50 (calcium carbonate, manufactured by Shiraishi Industry Co., Ltd.). 100,
Mitsubishi Chemical Industry Co., Ltd.) (0.3, 1.0, 2.
0) 1 g adjusted by adding parts by weight was used. Then, a near-infrared ray irradiation lamp was provided at a position 10 cm away from the acrylic plate, and near-infrared rays were emitted from the lamp at right angles to the acrylic plate. The relationship between irradiation time and temperature is shown in FIG. For comparison, a case where only the acrylic plate (AC plate) was used (●) and a case where an adhesive containing no carbon black was used (○) were also examined. In FIG. 2, ▲ indicates the case where 0.3 parts by weight of carbon black was added, □ indicates the case where 1.0 parts by weight of carbon black was added, and ■ indicates the case where 2.0 parts by weight of carbon black was added. Further, when the thickness of the acrylic plate was different, the relationship between the irradiation time and the temperature was examined in the same manner as described above, and the results are shown in FIG. In FIG. 3, ● indicates a case where only the acrylic plate having a thickness of 15 mm is used, ▲ indicates a case where only an acrylic plate having a thickness of 10 mm is used,
Indicates that only an acrylic plate having a thickness of 7 mm is used.
When 1 part by weight of carbon black is added to a 5 mm acrylic plate, Δ indicates when 1 part by weight of carbon black is added to an acrylic plate having a thickness of 10 mm, and □ indicates 1 part by weight of carbon black is applied to an acrylic plate having a thickness of 7 mm. The case of adding the respective components is shown. As is clear from the results of FIGS. 2 and 3, by adding carbon black to the thermosetting adhesive, the temperature of only the adhesive portion can be higher than that of the acrylic plate, and the temperature of the adhesive increases. Can be promoted.

[0012]

In summary, according to the present invention, a thermosetting adhesive to which a specified amount of carbon black is added is used for fixing an adherend and infrared rays are selectively transmitted through the adherend. Since the adhesive is irradiated, the curing time of the adhesive can be improved without deforming the adherend or the like, and the productivity is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of irradiating an acrylic plate having a thermosetting adhesive with near infrared rays.

FIG. 2 is a graph showing a relationship between irradiation time and temperature.

FIG. 3 is a graph showing a relationship between irradiation time and temperature.

Claims (3)

[Claims] When bonding an adherend having optical transparency using a thermosetting adhesive, carbon black is added to the thermosetting adhesive, and the thermosetting adhesive is adhered using the carbon black-added adhesive. A method of curing an adhesive, comprising bonding a body to a desired location, transmitting the adherend, and irradiating the adhesive with infrared rays. 2. The amount of carbon black added is 0.1.
The method according to claim 1, wherein the amount is from 10 to 10 parts by weight. 3. The method according to claim 1, wherein the infrared light is near infrared light.