JPH03245453A - Adhesive for base of bulb - Google Patents

Abstract

PURPOSE:To improve the adhesive strength of an adhesive for silicon resin base by using silicon resin for the adhesive component, and specifying, concerning the average diameter, the minimum blending factor of an inorganic filler. CONSTITUTION:The blending factor y(weight%) of the inorganic fillers 31 to be blended in silicon resin 3 is specified as y>=138.443/(x+0.347)+64.100, to the average grain diameter x(mu) of the fillers 31. If the fillers large in grain diameters are blended to meet this relation, fellow grains of the fillers 31 intertwine with each other, whereby the adhesive force is reinforced, and even if it is approximately the same heating time as the case where a phenol adhesive is used, the shortage of the strength by the insufficiency of hardening of the silicon resin itself is supplemented. Accordingly, even if it is used for a phenol resin base adhesive charger or a base bonder as it is, enough strength can be gotten.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention utilizes the manufacturing equipment and production line for manufacturing tubes using a phenolic resin cap adhesive, and This invention relates to a silicone resin cap adhesive that can be used to produce tubes.

(Prior Art) Conventionally, phenolic resin adhesives have been used to bond caps of bulbs such as general light bulbs and fluorescent lamps.

In recent years, there has been a trend toward smaller size and higher output in these general light bulbs and fluorescent lamps, and with this trend, silicone resin adhesives with excellent heat resistance and ultraviolet resistance have attracted attention.

(Problems to be Solved by the Invention) In general, the adhesive strength of an adhesive tends to be stronger as the adhesive component increases, but a large amount of adhesive component increases expansion and contraction of the adhesive, which is not preferable. In other words, in the case of tubes, glass bulbs that are thinner and thermally processed are more susceptible to mechanical and thermal shock than caps made of metal or synthetic resin, and the glass bulb itself or the gap between the cap and the glass bulb is filled. Thermal expansion and contraction of the adhesive puts stress on the glass and can damage the bulb, so as a countermeasure, an inorganic filler that has higher heat resistance and a lower coefficient of thermal expansion than this component and is inexpensive is mixed into the adhesive component. ing.

When trying to use a conventional silicone resin adhesive to bond the glass bulb and cap of a tube, phenolic resin adhesives are used because they cure slowly at the same curing temperature as phenolic resin adhesives. It was not possible to use a normal cap bonding machine based on this premise, and it was necessary to organize a separate production line just for the cap bonding process.

In addition, conventional silicone resin adhesives have high viscosity, and when filling the nozzle with adhesive, a stringy phenomenon similar to that seen in starch syrup occurs, and when conventional cement filling machines are used, the adhesive Not only is it difficult to inject a fixed amount, but the adhesive continues to string even after injection has finished, contaminating the nozzle and work environment. The agent filling process had to be specially organized using a specially made filling machine.

In this way, in the past, dedicated manufacturing equipment or special production lines were used to use silicone resin-based cap adhesives, so it was difficult to organize assembly-line work and lower production efficiency was avoided. I can't.

Furthermore, it cannot be ignored that silicone resin itself is expensive.

Therefore, the problem of the present invention is to make it possible to use the conventional filling machine for phenolic resin adhesive as it is and to exhibit good workability.
This silicone resin also cures in the same heating time as conventional phenolic resin adhesives, and as a result, existing manufacturing equipment and production lines that are designed to use conventional phenolic resin adhesives can be used as is. The purpose of the present invention is to provide a base adhesive.

[Structure of the invention]

(Means for Solving the Problems) The present invention uses a silicone resin as an adhesive component, and preferably contains an appropriate amount of an inorganic filler with an average particle size of 10μ or more. The heating time is such that substantial adhesive strength can be obtained to the extent that it does not interfere with the work from the next process onward, and the filling work can be performed satisfactorily using the conventional filling machine for phenolic resin-based nozzle adhesive. It is designed to be used as is on the production line.

(Function) The present inventor focused on the fact that when an inorganic filler with a large particle size is blended into an adhesive, the particles of the filler become intertwined with each other to strengthen the adhesive force. By appropriately selecting the average particle size and blending ratio of the filler, even with the same heating time as when using conventional phenolic resin adhesives, there is no lack of strength due to insufficient curing of the silicone resin itself. Supplemented by the reinforcing effect of the inorganic filler, adhesive strength was obtained to the extent that it did not interfere with the work of adhering the cap, and furthermore, by curing over time, the adhesive strength exceeded the specified value.

Furthermore, the present inventor noticed that increasing the blending ratio of inorganic fillers can improve the stringiness phenomenon of silicone resin,
By adjusting the blending ratio appropriately, it can be used as is in conventional phenolic resin-based cap adhesive filling machines, making it possible to incorporate it into the same production line, and eliminating the risk of contaminating the cap or working environment. Furthermore, we have also discovered that if the blending ratio of the inorganic filler is increased to a range that improves workability, the adhesive strength can be maintained at the required level as described above, and the product can be supplied at a lower cost.

(Example) The details of the present invention will be explained with reference to the following examples.

Example 1 In this example, calcium carbonate powder was used as an inorganic filler, and its material composition was as follows.

Silicone resin (TSE series manufactured by Toshiba Silicone) 20
Weight % Calcium carbonate powder (made by Maruo Calcium ■, average particle size 80 μm specification, 80 weight %) These two components are kneaded with a solvent such as xylene equivalent to 7 weight % of the total to prepare a paste adhesive. This was filled into the tank of a gold cement filling machine made by Onishi Kikai, which was manufactured for use with phenolic resin cap adhesives, and normal air pressure was applied, and a light bulb cap was attached to the injection port.
The injection valve of the filling machine was opened and a predetermined amount of adhesive was injected to adhere to the opening of the mouthpiece as specified. At this time, the adhesive had the same level of adhesion and breakage characteristics as phenolic resin nozzle adhesive, and almost no stringing phenomenon was observed, indicating that the filling machine was manufactured for use with phenolic resin nozzle adhesive. Despite this, it is possible to inject a fixed amount, there is little variation in the amount of coating, and there is little chance of contaminating the nozzle or work area.
There were almost no changes in working conditions or workability.

Next, the silicone resin-based cap adhesive was attached to a light bulb, held in the head of a regular light bulb cap adhesive, and heated for 1 minute at 220°C under normal heating conditions. and baked the adhesive.

The bulb with the cap attached in this way is removed and then pressed and hit to a degree that rarely occurs in the subsequent process.

When tested by applying an external force such as torsion to the cap, no abnormalities such as misalignment, bending, twisting, or peeling were observed in the cap, and the product could be incorporated into a conventional light bulb production line without any problems. There were no problems. In addition, when completed as a product, all products showed adhesive strength that exceeded regulations, and in a 2000-hour life test, the base adhesive strength exceeded the Japanese Industrial Standard (JIS C7501) for general lighting bulbs. There was no problem at all at 5N*m or more. Furthermore, since the product of this example contains calcium carbonate powder, it can be manufactured at low cost.

Therefore, in order to examine the reason why the base adhesive of this example has high adhesive strength, the part where the base of the light bulb was bonded was cut out and its cross section was investigated. The results are schematically shown in FIG. That is, (1) is a glass bulb, (2) is a base, and (3) is a base adhesive of this example, and the base adhesive (3) is a hardened silicone resin (31).
) has a structure in which the inorganic filler (32) is mixed. Thus, the feature of the present invention is that the particles of the inorganic filler (32) engage with the particles of other inorganic filler (32) through the protruding corners and support each other. In this figure, the particle shape of the inorganic filler (32) is simulated as a pentagon, but in reality, it has an irregular shape, and most of the particles have sharp protruding corners.

Example 2 This example uses silica powder as an inorganic filler, and its material composition is as follows.

Silicone resin (same as Example 1) 15% by weight silica powder (Tatsumori ■Sei Crystallite) (average particle size 100μ)
85% by weight This material was also formed into a base adhesive in the same manner as in Example 1, and similarly filled in a Rokin cement filling machine manufactured by Onishi Kikai ■ and adhered to the base of a light bulb. When using conventional phenolic resin base adhesive, it can be used under the same conditions as when using adhesives, can be injected in the same quantity, has little variation in the amount of coverage, and hardly stains the base or work area. There was almost no difference compared to

Furthermore, when the cap coated with the adhesive of Example 2 was adhered to a light bulb using a cap bonding machine in the same manner as described above, various problems in the subsequent manufacturing process were confirmed under normal heating conditions, that is, baking at 220°C for 1 minute. It exhibited adhesive strength that did not interfere with work, and was able to be incorporated into conventional light bulb production lines as is. Furthermore, the product of Example 2 could also be manufactured at low cost.

Next, in the materials of both of the above-mentioned examples, the average particle diameter of the inorganic filler and its blending ratio were varied, and the materials were baked at 220° C. for 1 minute, and the adhesive strength thereof was investigated.

The measurement method for this test is based on the Japanese Industrial Standards for general lighting bulbs (
According to the method specified in JIS C7501). The results are shown in FIG. In the figure, the horizontal axis shows the blending ratio of the inorganic filler in weight percent, and the vertical axis shows the adhesive strength in Newton meters (N-m).The English symbols attached to each curve are The inorganic filler in C is calcium carbonate, the symbol S is silica, and the number following the English symbol is the average particle size of the filler (μ
) are shown respectively. (Example C150: Calcium carbonate whose inorganic filler has an average particle size of 150 μm) From this figure 2, if the blending ratio of the inorganic filler is 97% by weight or less, it exceeds the service limit of 3 N m specified by JIS. It has become clear that it can be used in the same way as phenolic resin base adhesive.

However, as is clear from Figure 2, the adhesive strength does not change much even if the blending ratio of the inorganic filler changes; The lower the value, the more noticeable the stringing phenomenon is when applying the adhesive to the nozzle, and the present inventors focused on this point and tested the relationship between the average particle diameter and blending ratio of the inorganic filler and workability. In this test, the filler was calcium carbonate, and the adhesive was made using Onishi Kikai's Rokin cement filling machine for light bulbs manufactured by Onishi Machinery Co., Ltd., which was manufactured for use with the above-mentioned phenolic resin cap adhesive. A predetermined amount of adhesive was applied to the cap, and the degree of stringiness was visually evaluated.The results are shown in Table 1.

Table 1 This table shows the stringy phenomenon based on sensory evaluation.
In the table, the ○ mark indicates that there is no stringing problem, the Δ mark is a little difficult to work with, but there is no problem in practical use, and the × mark indicates that there is stringing. It has been found that this phenomenon can be prevented from occurring.

Therefore, based on the evaluation in Table 1 above, we determined the relationship between the average particle size of the inorganic filler and the distribution ratio at the limit at which the stringing phenomenon does not occur.
This is shown in the figure by a correlation line (indicated by △ in the table). If we convert this into a mathematical formula, y≧138.443 /(x+0.347) +64.
110 (where y is the minimum blending ratio (wt%) of the inorganic filler
), X is the average particle diameter (μ)). In other words, if it is above the limit line (shaded side) in Figure 3, the stringing phenomenon can be avoided, and the conventional phenolic resin base adhesive can be replaced without any hindrance to work, and the conventional production line can be used as is. Ta.

In the present invention, the preferred average particle size of the inorganic filler blended into the silicone resin base adhesive is 10 to 300μ, and 10 to 300μ.
If it is less than μ, the fluidity will be too high, and if it exceeds 300 μ, the fluidity will be poor, resulting in the disadvantage that the adhesive will not adhere uniformly around the opening of the mouthpiece when it is applied to the mouthpiece.

Further, the blending ratio of the inorganic filler to the silicone resin may be within the range corresponding to each average particle size shown in FIG.
Relatively speaking, if the content of the inorganic filler is low and the adhesive component is large, a stringing phenomenon will occur and workability will be lowered, while if the content of the filler is too large, the adhesive strength will decrease, which is undesirable.

In addition, in the present invention, the inorganic filler in the above embodiments is not limited to calcium carbonate or silica, but may also be magnesia, stone powder, etc., or a mixture thereof.

Furthermore, since inorganic fillers are generally significantly cheaper than silicone resins, they also have the added effect of lowering the price of adhesives.

Furthermore, the average particle size of the present invention was measured by the aeration method.

Furthermore, the cap adhesive of the present invention can be applied not only to general light bulbs but also to other bulb caps, and is particularly suitable for applications that require heat resistance and ultraviolet resistance, such as fluorescent lamps, germicidal lamps, discharge lamps, and large Suitable for output light bulbs, etc.

〔Effect of the invention〕

As described above, the tube cap adhesive of the present invention uses silicone resin as an adhesive component, and the average particle size of the inorganic filler added to this adhesive component and the blending ratio to the particle size are regulated.
It can now be used as is in a conventional phenolic resin cap adhesive filling machine, and even if it is used as is in a cap bonding machine that performs cap baking using a conventional phenolic resin cap adhesive and baked under the same conditions, the As the adhesive strength is strong enough to not interfere with the work, it can now be used as is in conventional production lines.

[Brief explanation of drawings]

FIG. 1 is a schematic enlarged sectional view showing the adhesion state of an example of the tube cap adhesive of the present invention, and FIG. 2 is a graph showing the relationship between the blending ratio (wt%) of the inorganic filler and the adhesive strength in the present invention. The graph showing the relationship, Figure 3, shows the minimum blending ratio of inorganic fillers (wt%).
) and the average particle diameter (μ). (1)...Glass bulb, (2)...Cap. (3)...cap adhesive, (31)...silicon resin. (32)...Inorganic filler.

Claims (3)

[Claims] (1) A tube cap adhesive characterized in that the adhesive component is silicone resin and an inorganic filler is blended therein so as to satisfy the following formula. y≧138.443/(x+0.347)+64.11
0 (where y is the minimum blending ratio of inorganic filler (wt%), x is the average particle size (μ)) (2) The tube cap adhesive according to claim 1, wherein the inorganic filler comprises calcium carbonate and/or silica. (3) The tube cap adhesive according to claim 1, wherein the inorganic filler has an average particle size of 10 μ to 300 μ.