JPH0535199B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a light bulb cap adhesive for bonding a cap to a glass bulb of a light bulb. Construction of conventional examples and their problems Phenol-based resin is often used as the adhesive for bonding the glass bulb and cap of the light bulb. This phenolic resin is generally a thermoplastic resin, which is a resin obtained by condensing phenol and formalin with an acid, and is called a novolak type resin. Further, a resin condensed with an alkali is called a resol type and is a thermosetting resin. Light bulb cap adhesives are mixed with epoxy resins, silicone resins, silicone resins, etc., and are accelerated in curing by hexamethylenetetramine (urotropin). The properties required for a light bulb cap adhesive are roughly as follows. (1) Excellent adhesive strength between glass and metal materials (aluminum or copper-zinc alloy used for base material, etc.). (2) The adhesive strength will not deteriorate due to the heat generated during use of the light bulb until the end of its life. (3) The adhesive product is easy to manufacture and the light bulb manufacturing process has excellent workability. Conventional light bulb base adhesives mostly satisfy the required characteristics, but recently, light bulb manufacturing equipment has been automated, and adhesives that can be operated at high speeds are becoming more compatible with high-speed automatic machines. It must have very demanding quality characteristics. OBJECTS OF THE INVENTION The present invention provides a light bulb cap adhesive that is suitable for increasing the speed of light bulb manufacturing equipment and has sufficient adhesive strength to withstand heat during use of the light bulb. Structure of the Invention The bulb base adhesive of the present invention contains 2 to 7% by weight of phenolic novolak resin and 8% by weight of resol resin.
~10% by weight, ~0.3 hexamethylenetetramine
0.5% by weight and filler, and the filler has a viscosity of 175 to 200 mesh. Description of Examples Conditions that are compatible with high-speed automatic machines are as follows: (1) The above-mentioned phenolic novolac resin (hereinafter abbreviated as novolac resin) and resol resin:
The method of curing is different; novolak resin is thermoplastic, so a hardening agent must be used to bond the lamp base to the glass bulb. The cap adhesive that fixes the bulb cap and the glass bulb is indexed at a high speed of 1 second or more, for example, and the time the light bulb is inserted into the cap adhesive for the cap adhesive is for a short time of 50 seconds or less. However, it is necessary to finish gluing during this time. However, it is not possible to shorten the curing time to 50 seconds or less simply by adding a curing agent to the novolak resin, so curing must be accelerated by heating. In this way, the composition and conditions of the cap adhesive must be determined by clarifying the need for curing in a short time using a high-speed machine and the relationship between the amount of curing agent added and heating temperature relative to the curing time. . (2) However, if the heating temperature is raised, curing will be accelerated and the adhesion will be completed within a short period of time. This causes a decrease in machine accuracy and limits the heating temperature. In addition, in order to prevent deformation due to mechanical strain, the heating temperature must not rise above 210°C, and it must be cured at a temperature of 210°C within a short time as described above. (3) In order to apply adhesive to the cap using an automatic machine, a certain degree of tightness is required. Due to the nature of the adhesive, it is sticky and adheres to mechanical parts, so the workability when taking out the amount required for one nozzle from a large lump of adhesive becomes an issue, and the ability to separate each nozzle becomes difficult. There must be. At the same time, if the adhesive is fluid at room temperature, the adhesive applied to the base will move from the applied area, but it must not shift from its initial position or generate a large amount of gas during curing. (4) It must be able to withstand the temperature during use of the light bulb and the torque applied to the base due to the installation and removal of the light bulb from the socket during storage and use. Since the novolac resin is a thermoplastic, it was mentioned above that a hardening agent is added when it is used as an adhesive for bonding a base to a glass bulb of a light bulb. However, novolak resin exists in a solid state, and is used by dissolving it in alcohol to form a viscous paste such as an adhesive. Therefore, this alcohol is effective in controlling the viscosity of the resin, but
Because it evaporates easily, it causes viscosity changes, making the condition settings in high-speed automatic machines unstable and unstable. For this reason,
When used in combination with a phenolic novolak resin that exists as a viscous liquid, a resin with relatively little change in viscosity can be obtained. However, resol resin is a thermosetting type, and although curing is sufficiently accelerated in 50 seconds at a temperature of 210°C on the automatic cap bonding machine mentioned above, a large amount of gas is generated during the curing reaction, and it is hard to cure on the automatic cap bonding machine. When soldering the lead wire to the base at the same time, there is a drawback that good soldering cannot be achieved due to the gas ejected from the molten solder during the curing reaction of the adhesive. However, since it is a high-speed machine, it is not possible to wait until the gas generation stops, so the gas generation itself must be reduced to an amount that does not interfere with soldering. For these reasons, resol resin alone is not suitable for high-speed machines, and it is easy to imagine that by mixing it with novolak resin, which generates a small amount of gas during curing, the amount of gas generated will be relatively small. Because the curing accelerator required for resin curing accelerates the curing of resol resin at low temperatures, the viscosity changes significantly and cannot withstand storage for 24 hours at room temperature of 30°C. As mentioned above, no matter which adhesive is used, there are elements that make it incompatible with high-speed automatic machines, and the adhesive is extremely complex and diverse. As a result, phenolic resin itself could not be used as an adhesive for light bulb caps, and it was feared that they would be unable to supply a cheap adhesive. However, after conducting numerous composition experiments, they were able to find a solution that used phenolic resin as the main component. I found an adhesive that does. Next, an experimental example will be described. Various curing agents for curing novolac molds are commercially available. A typical example is hexamethylenetetramine (urotropin). The type and amount of this curing agent also have an important influence on the workability and performance of the adhesive. Therefore, in order to study the compositions of novolac resin, resol resin, epoxy resin, and urotropin in advance, the following experiments were conducted to determine their quality. a. Curing performance of adhesive within a short time A torque of 5 Nm was applied between the base of the light bulb and the glass bulb immediately after it was prototyped using a high-speed automatic machine.
Check to see if the cap has come loose. b Storage performance of adhesives Adhesives naturally harden due to the presence of urotropin, so to examine their storage performance, the room temperature at the light bulb manufacturing site easily rises to 35°C, so the adhesive should be stored tightly in a constant temperature room at 35°C, and its viscosity We investigated changes over time. Viscosity is expressed as the speed at which a needle-shaped stainless steel rod (weight 150g diameter 5.8) settles into the adhesive. If it takes more than 7 seconds for the needle to settle 5 cm, the viscosity is so hard that it cannot be used, so it is determined by this number of seconds. did. c High-speed filling performance of adhesive (splitting performance) To fill adhesive between the cap and the glass bulb, first fill the cap with adhesive. At this time, the ability to quickly separate the lumps of adhesive into individual caps was required, and to determine this characteristic, we actually used a high-speed automatic machine and investigated whether it could keep up with the machine speed. d Heat resistance performance of adhesive To test the heat resistance of adhesive, a light bulb prototyped using a high-speed automatic machine was placed in an electric furnace at 210℃, taken out every 100 hours, and a light bulb was placed between the base and the glass bulb.
I applied a torque of 3Nm and checked to see if the cap would come off. 210 for adhesives with excellent heat resistance
Even if the elapsed time at ℃ is long, it can withstand a torque of 3Nm, so the heat resistance test was conducted by heating at 210℃ for 1000 hours, applying a torque of 3Nm, and judging whether it could withstand it. Experiment 1 In Experiment 1, we conducted a test focusing on the workability of the adhesive. The workability of the adhesive is predicted to be determined by the mixing ratio of resol resin and novolak resin, resin content, amount of curing agent added, and particle size of filler (calcium carbonate). I decided to do a test. However, since an experiment covering all of these mixing ratio experiments would be extremely complicated, we decided to narrow down the factors and conduct tests one by one. First, tests were conducted on the mixing ratio of resol resin and novolac resin and the resin content. The amount of curing agent and the particle size of the filler were fixed, 0.5% by weight of curing agent or less (% means % by weight), and the particle size of the filler was 200 mesh. Further, the viscosity of the adhesive was kept constant by varying the amount of alcohol added so that the viscosity was 5 seconds. The experimental results were as shown in Table 1.

【table】

[Table] In the above table, ○ mark indicates good quality and × mark indicates poor quality.
When workability was taken as a factor in the judgment, good results were obtained when novolak resin or resol resin was used alone. In addition, in the mixed resin of novolak type and resol resin, the resol resin is 15% by weight (hereinafter %
It has been found that when the amount exceeds 100% by weight, the splitting property becomes poor and the amount of gas generated also becomes a problem. Experiment 2 In Experiment 2, the amount of resin and the mixing ratio of novolac resin and resol resin that obtained good results in Experiment 1 was changed by changing the amount of curing agent to improve the curing properties, storage stability, and
Experiments were conducted on heat resistance, splitability, and gas generation. 3% by weight of novolac resin (hereinafter, % represents weight%), 10% of resol resin, 5% of novolac resin, and 10% of resol resin were good, so we added 8% of novolac resin. ,
At the same time, we conducted an experiment to find an approximate upper limit for the amount of novolac resin. The results are shown in Table 2.

【table】

[Table] Considering heat resistance, novolac resin was concentrated at 5% or 10%, and the composition of the three components of novolac resin, resol resin, and curing agent became almost clear. In order to find the best composition,
The following experiment was conducted to obtain a more detailed composition. Experiment 3

【table】

[Table] From the results shown in Table 3, novolak resins 2 to 7
% and 8-10% resol resin was found to be well mixed. Next, Experiment 4 was conducted to determine the appropriate amount of curing agent. Experiment 4

[Table] From the results shown in Table 4, it was found that when the novolak resin is 2%, there is no problem with 0.2% curing agent, but when the novolak resin is 7%, the curing performance is poor at 0.2%. Therefore, novolak resin 2~
It was found that the optimum amount of curing agent for a mixed resin of 7% resol resin and 8-10% resol resin is 0.3-0.5%. Next, in Experiment 1, it was found that the particle size of the filler was related to the dividing performance, so an experiment was conducted with the filler having a particle size of 200 mesh used in the above-mentioned experimental example, and with the particle size further changed. Experiment 5

[Table] In Table 5, filler particle size refers to the particle size that, when passed through a sieve, will pass through entirely, but when a finer sieve is used, about 10% will remain on the sieve. . For example, a particle size of 150 mesh will pass through a 150 mesh sieve, and a 175 mesh sieve will pass approximately 10
% refers to what remains on the sieve. As can be seen from the results shown in Table 5, when the filler particle size was 150 mesh, some fillers had poor heat resistance, and when the filler particle size was 250 mesh, some had poor divisibility. Therefore, the particle size of the filler is 175~
By using 200 mesh, it is possible to obtain a cap adhesive suitable for high-speed automatic light bulb manufacturing machines, and it is possible to provide inexpensive light bulbs. Effects of the Invention As explained above, according to the present invention, it is possible to provide a light bulb cap adhesive that is suitable for increasing the speed of light bulb manufacturing equipment and has adhesive strength sufficient to withstand heat during use of the light bulb. It is possible.

Claims (1)

[Claims] 1 A light bulb cap adhesive for bonding the cap to the glass bulb of a light bulb, containing 2 to 7% by weight of phenolic novolac resin and 8 to 10% of resol resin.
1. A light bulb base adhesive, comprising 0.3 to 0.5 weight % hexamethylenetetramine and a filler, the filler having a particle size of 175 to 200 mesh.