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  Lead-free glass material for use in sealing and, sealed article and method for sealing using the sameUSPTO Application #: 20070191203Title: Lead-free glass material for use in sealing and, sealed article and method for sealing using the same Abstract: Provided with a glass composition including a network-former oxide composed of any one of or both of B2O3 and V2O5 of 20-80% by weight, ZnO of 0-60% by weight and BaO of 0-80% by weight, wherein at least one of ZnO and BaO is included as an essential ingredient. The present invention is a glass material for use in sealing, which is of lead-free series, can be used for sealing at a low processing temperature and within a wide temperature range, has a low thermal expansion coefficient, superior adhesion, superior sealing processability, superior adherence, superior chemical stability, superior strength and the like and comprises sufficient practical performance to substitute for lead glass. (end of abstract) Agent: Schweitzer Cornman Gross & Bondell LLP - New York, NY, US Inventors: Masahiro Yoshida, Yasuo Hatate, Tsugumitsu Sarata, Yoshimitsu Uemura, Tomoyuki Honda, Hiroyuki Fukunaga, Masahiro Iwashita USPTO Applicaton #: 20070191203 - Class: 501015000 (USPTO) Related Patent Categories: Compositions: Ceramic, Ceramic Compositions, Glass Compositions, Compositions Containing Glass Other Than Those Wherein Glass Is A Bonding Agent, Or Glass Batch Forming Compositions, Enamels, Glazes, Or Fusion Seals (e.g., Raw, Fritted, Or Calcined Ingredients), Fusion Seals (frit Plus Material Other Than Glass) The Patent Description & Claims data below is from USPTO Patent Application 20070191203. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a lead-free glass material for use in sealing, which is used for sealing of an opening or a joint in various kinds of electronic components or electronic products such as an electron tube, a fluorescent display panel, a plasma display panel and a semi conductor package, and to a sealed matter and a sealing method using the lead-free glass material. BACKGROUND ART [0002] As a general trend, a glass material for use in sealing is used for sealing of various kinds of electronic products which are used with the inside thereof being kept in a high vacuum and for sealing of electronic component packages for preventing entering of corrosive gas or moisture in order to ensure the operation stability. This glass material for use in sealing is made of low-melting glass powder, and a glass continuous layer having glass powder fused thereon is formed by pasting the powder with organic binder solution, coating a sealed portion of an article to be sealed with the pasted powder and burning the article in an electric furnace or the like to strip a vehicle ingredient. [0003] Conventionally, mainly lead glass powder of PbO--B.sub.2O.sub.3 series is widely used as such a glass material for use in sealing. That is, lead glass having a low melting point and ease of melting of PbO can be used for sealing at a low processing temperature and within a wide temperature range, and lead glass having low thermal expansion, superior adhesion, superior adherence, superior chemical stability and the like provides advantages of high sealing property, high sealing strength and high durability. [0004] However, since lead is a toxic substance, there is an occupational safety and health problem in a manufacturing step of lead glass, and there is a concern about how to deal with disposal of electronic components or electronic products, since disposal of untreated electronic components or electronic products at the end of life usefulness for which lead glass was used for sealing could cause soil contamination or groundwater contamination due to lead being eluted by acid rain or the like and disposal by landfill or the like is prohibited under recent strict environmental regulations while limited application due to inclusion of lead makes recycling difficult. [0005] Suggested measures for such problems are: to use low-leaded glass including Pb of 10-23% for a stem mount or the like for sealing a glass valve (Japanese Unexamined Patent Publication No. 8-180837); and to provide a groove for preventing entry of etchant at a front plate and a back plate of a plasma display panel on the inner side of a marginal lead glass sealing portion, dip the plasma display panel at the end of life usefulness into etchant to remove lead glass of a sealing material selectively and repair a deteriorated portion for recycling (Japanese Unexamined Patent Publication No. 2000-113820). However, fundamental measures cannot be obtained since toxic lead is still included in the waste product even though the amount of lead can be decreased by using low-leaded glass as in the former method. Moreover, with the latter method of removing the lead glass sealing portion by etching, the amount of labor and costs required for the removing process causes a decrease in the advantage of recycling, and the method also has a cost disadvantage in a manufacturing stage due to formation of the groove. [0006] Against this background, development of a glass material for use in sealing of lead-free series which can substitute a conventional general-purpose lead glass series has been strongly demanded. However, although TiO.sub.2 series, P.sub.2O.sub.5 series and the like have been reported as lead-free low-melting glass, none of them, even having a low melting point, offers performance comparable to lead glass in terms of sealing processability, thermal expansion coefficient, adhesion, adherence, chemical stability, strength and the like, and therefore they are a long way off from practical use and have not progressed past basic research at the present stage. [0007] With a view toward the above situation, an object of the present invention is to provide a glass material for use in sealing, which is lead-free, can be used for sealing at a low processing temperature and within a wide temperature range, has a low thermal expansion coefficient, superior adhesion, superior sealing processability, superior adherence, superior chemical stability, superior strength and the like and comprises sufficient practical performance to substitute lead glass. DISCLOSURE OF THE INVENTION [0008] In order to achieve the above object, the present inventors focused attention on the fact that the constituents of glass (amorphous) are divided into three kinds of a network-former oxide (Network former: NWF) which forms a three-dimensional network structure that is the basic skeleton of glass, a network-modifier oxide (Network modifier: NWM) which cannot form glass by itself but gets into the three-dimensional network structure and affects the glass property and an intermediate oxide (Intermediate) which cannot form glass by itself but may be involved in network formation instead of a part of the network-former oxide or may serve as the network-modifier oxide, and first selected B.sub.2O.sub.3 and V.sub.2O.sub.5 as the network-former oxide, selected ZnO, which exhibits behavior similar to that of PbO in the glass structure, has glass forming ability depending on single-bond strength with oxygen close to that of PbO and has the same dissociation energy per mol and coordination number as those of PbO, as an alternative ingredient for PbO of a conventional lead glass for use in sealing, from an extremely large number of oxides which function as intermediate oxides or network-modifier oxides and further selected BaO as a network-modifier oxide. [0009] Then, in order to check the suitability of a lead-free glass including these oxides as the basis ingredient, i.e. glass of B.sub.2O.sub.3 and/or V.sub.2O.sub.5--ZnO--BaO series, as a glass material for use in sealing, the inventors set a variety of combinations of the respective ingredients and the compounding ratio to evaluate various kinds of physico-chemical characteristics by close experimental work and continued discussions from a variety of angles and, as a result, found a composition comprising sufficient practicality as a lead-free glass material for use in sealing, sought out a composition further having superior sealing processability and a higher practical value which can be obtained by adding other specific ingredients to the basic ingredient, and thus made the present invention. [0010] That is, a lead-free glass material for use in sealing according to Claim 1 of the present invention has a glass composition including a network-former oxide composed of any one of or both of B.sub.2O.sub.3 and V.sub.2O.sub.5 of 20-80% by weight, ZnO of 0-60% by weight and BaO of 0-80% by weight, wherein at least one of ZnO and BaO is included as an essential ingredient. [0011] The invention of Claim 1 provides a glass material for use in sealing, which has a lead-free glass composition, can be used for sealing at a low temperature and within a wide temperature range, offers preferable adhesion and adherence with respect to a sealed portion, rarely causes generation of flaking or a crack at a sealing portion and offers superior chemical stability and strength of a sealing glass layer and preferable durability of the sealing portion. [0012] Moreover, the invention of Claim 2 is the lead-free glass material for use in sealing of the above Claim 1, which has a glass composition composed of B.sub.2O.sub.3 of 20-80% by weight, ZnO of 0-50% by weight and BaO of 0-60% by weight. [0013] The invention of Claim 2 provides the above lead-free glass material for use in sealing of, in particular, B.sub.2O.sub.3--ZnO--BaO series, which offers a preferable glass state and a high glass recovery percentage. [0014] The invention of Claim 3 has a glass composition composed of B.sub.2O.sub.3 of 20-40% by weight, ZnO of 0-50% by weight and BaO of 10-60% by weight. [0015] The invention of Claim 3 provides the above lead-free glass material for use in sealing of B.sub.2O.sub.3--ZnO--BaO series, which has a low glass transition point, can be used for sealing at a lower temperature, can reduce the thermal effect on an article to be sealed and can reduce the thermal energy consumption. [0016] The invention of Claim 4 is constructed to have a glass composition composed of B.sub.2O.sub.3 of 20-35% by weight, ZnO of 10-35% by weight and BaO of 40-60% by weight, respectively. [0017] The invention of Claim 4 provides the above lead-free glass material for use in sealing of B.sub.2O.sub.3--ZnO--BaO series, which has an especially low glass transition point, offers superior thermal stability as glass and comprises high suitability as a sealing material. [0018] Furthermore, a lead-free glass material for use in sealing according to the invention of Claim 5 has a glass composition including any one of or both of TeO.sub.2 and Bi.sub.2O.sub.3 of 50-500 part by weight compounded for an oxide having the glass composition according to any one of the above Claim 2 to Claim 4 of the total amount of 100 part by weight. [0019] The invention of Claim 5 provides the above lead-free glass material for use in sealing of B.sub.2O.sub.3--ZnO--BaO series, which includes at least one of TeO.sub.2 and Bi.sub.2O.sub.3 as the fourth ingredient compounded at a specific range, so that the fluidity in a molten state and the thermal stability as glass are enhanced drastically and the glass transition point and the softening point further lower and, therefore, extremely superior sealing processability is obtained and ideal performance as a glass material for use in sealing can be offered. [0020] On the other hand, the invention of Claim 6 is lead-free glass material for use in sealing of the above Claim 1, which has a glass composition composed of V.sub.2O.sub.5 of 30-80% by weight, ZnO of 0-50% by weight and BaO of 10-60% by weight. [0021] The invention of Claim 6 provides a lead-free glass material for use in sealing of, in particular, V.sub.2O.sub.5--ZnO--BaO series which has a low glass transition point and offers a preferable glass state and a high glass recovery percentage. Moreover, since the glass itself is of greenish black, there is the advantage that coloring, which is required for a conventional lead glass material, can be omitted. Continue reading... Full patent description for Lead-free glass material for use in sealing and, sealed article and method for sealing using the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Lead-free glass material for use in sealing and, sealed article and method for sealing using the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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