Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-06-22
2004-04-13
Short, Patricia A. (Department: 1712)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C525S920000, C524S505000
Reexamination Certificate
active
06719872
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a hot melt composition suitably used for sealing a part where sealing is required, for which reactive curing sealing materials, such as a silicone, polyurethane, and polysulfide sealants; a butyl rubber sealant; a molded packing made from natural rubber or synthetic rubber; and the like are conventionally used, and to a method of assembling members using the hot melt composition.
BACKGROUND OF THE INVENTION
Conventionally, in each industrial field, such as an electrical, automobile, and construction industries, various kinds of sealing materials have been used to seal various parts for the purpose of dust control and waterproofing.
Recently, such sealing for dust control and waterproofing is required in more and more fields. In recent houses, for example, it is desired that airtightness and adiathermancy should be improved to enhance heat efficiency, and for this purpose, housing members used to build a house are also required to be highly airtight. In order to comply with such requirements, for the time being, a sealing part, where sealing is required, is treated by means of a cartridge filled with a reactive curing sealing material, such as a silicone, polyurethane, butyl rubber, and polysulfide sealants, or the like. In this case, the filling of the cartridge and application of the sealing material to the sealing part are performed within a factory or at a construction site at the time of or after the assembling work for members. Instead of such sealing by means of a cartridge, attachment of a molded packing made from natural rubber or synthetic rubber to the sealing part may be performed, also within a factory or at a construction site at the time two or more members are assembled. Otherwise, a butyl or styrene rubber hot melt adhesive may be applied to the sealing part within a factory.
However, there are some problems with such conventional sealing materials. In order to obtain a desired performance of the reactive curing sealing material applied with the cartridge or the like, it is necessary for the sealing material to be kept still for a long time until it has been reactively solidified, which is nonproductive. Also, the reactive curing sealing material has a problem with its peelability. For, once it is applied and solidified, it is no easy to peel it off. Consequently, the members once assembled with the reactive curing sealing material are difficult to be disassembled after use or at the time any inconvenience arises.
Furthermore, it is impossible for the reactive curing sealing material to be applied beforehand, and it must be applied at the time of or after the assembling work for the members.
As to the molded packing made from natural or synthetic rubber, there is no problem with its peelability or detachability. However, the molded packing has other problems. For example, in order to mold each packing, expensive dies having a shape conforming to the shape of each packing are required. Also, the molded packing has a high compression set if used at a temperature between 60° C. and 80° C., and it is thus difficult to maintain good airtightness for a long period of time with such a molded packing. Furthermore, the automated attachment of the molded packing is difficult and, therefore, each packing is usually attached by hand, which is very burdensome and nonproductive.
A hot melt adhesive made from a thermoplastic rubber, such as butyl or styrene rubber, can be used as an adhesive seal for joining various kinds of airtight members. In this case, the airtight members can be processed or assembled within a short period of time after the hot melt adhesive, which can be applied directly to those members, is cooled, which results in high productivity. Nevertheless, such a hot melt adhesive also has defects. For example, the hot melt adhesive is not easy to peel off, and once two or more members are assembled with the hot melt adhesive, it is difficult to disassemble them. Also, the hot melt adhesive has a high compression set at a high temperature, as with the molded packing as mentioned above.
SUMMARY OF THE INVENTION
The present invention provides a hot melt composition having a compression set of 90% or less at a temperature between 60° C. and 80° C., which temperature is disadvantageous to conventional hot melt-type sealing materials, when measured by a measuring method in accordance with provisions of JISK6262, the hot melt composition being capable of maintaining its sealing property as well as being easily detachable after use or at the time any inconvenience arises. The present invention also provides a method of assembling members using the hot melt composition, in which the hot melt composition is previously applied to a member, thereby skipping such an application work at the time of or after the assembling work of the members, which results in streamlining of work processes and shortening of work periods.
When a conventional styrene block copolymer having a number average molecular weight (Mn) of less than 100,000 was employed as a base ingredient to compound a hot melt composition, a tackifying resin with a high softening point was blended such that the hot melt composition was provided with heat resistance. Also, the amount of a softener, which provides flexibility, was reduced.
However, the hot melt composition produced in this manner was poor in flexibility at a low temperature, while it was deformed or cracked because of a stress applied to a sealed portion and, therefore, not capable of maintaining its sealing property at a high temperature.
Also, when a styrene block copolymer having a number average molecular weight (Mn) of 100,000 or more was employed as a base ingredient to compound a hot melt composition, a desired heat resistance to the temperature of 80° C. for 5 days was not achieved, unless a polyphenylene ether resin or a modified polyphenylene ether resin was added thereto.
Furthermore, if an increased amount of softener was blended to enhance flexibility at a low temperature, the compression set of the composition became high, especially, at a temperature between 60° C. and 80° C., and once the hot melt composition was exposed to such a high temperature, it was never recovered and the sealing property thereof was thus lost.
In view of these facts, one object of the present invention is to provide a hot melt composition of which the compression set, as a measurement of compression recovery after exposed to a high temperature between 60° C. and 80° C., is kept to be 90% or less, if measured by a measuring method in accordance with provisions of JISK6262. Such a hot melt composition should not reduce its flexibility at a low temperature. Also, such a hot melt composition should be capable of maintaining its sealing property and able to be peeled off without difficulty. The other object of the present invention is to provide a method of assembling members using the hot melt composition.
In order to attain these objects, there is provided a hot melt composition comprising, as essential ingredients, a high-molecular weight styrene block copolymer having a number average molecular weight (Mn) of 100,000 or more, either of a polyphenylene ether resin and a modified polyphenylene ether resin, and a viscosity adjuster. Also, there is provided a method of assembling members using the hot melt composition, the method characterized in that the molten matter of the hot melt composition is previously applied directly to a member which requires sealing.
For the high-molecular weight styrene block copolymer as an essential ingredient of the invention, a styrene-isoprene-styrene (SIS) block copolymer; a styrene-butadiene-styrene (SBS) block copolymer; a styrene-ethylene-1-butene-styrene (SEBS) block copolymer; a styrene-ethylene-propylene-styrene (SEPS) block copolymer; poly(alpha-methyl-styrene)-polybutadiene-poly(alpha-methyl-styrene), poly(alpha-methyl-styrene)-polyisoprene-poly(alpha-methyl-styrene), and their hydrogenated modifications, such as poly(alpha-methyl-styrene)-poly(ethylene-1-butene)-po
Iwatsuka Yuji
Tomita Atsushi
Aica Kogyo Co., Ltd.
Davis & Bujold PLLC
Short Patricia A.
LandOfFree
Hot melt composition and method of assembling members using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hot melt composition and method of assembling members using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hot melt composition and method of assembling members using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3239569