Organic binders, compositions for manufacturing inorganic material molded articles, green bodies, degreased bodies, inorganic material molded articles, and methods for manufacturing inorganic material molded articles.

Abstract

This invention provides an adhesive that provides green bodies with improved brittleness and reduced breakage. One aspect of this invention provides an organic adhesive for enabling the molding of sinterable inorganic powders, the organic adhesive containing polyethylene glycol as an adhesive component.

Description

Technical Field

[0001] This invention relates to an organic binder, a composition for manufacturing inorganic material molded articles, a green body, a degreased body, an inorganic material molded article, and a method for manufacturing an inorganic material molded article. Background Technology

[0002] A method is known in the past for using a composition comprising inorganic material powder and an adhesive for binding the inorganic material powder to perform metal injection molding, and then firing the mixture to form a sintered body to obtain a metal molded body.

[0003] For example, Patent Document 1 discloses a molded body obtained by molding a molding composition, the molding composition comprising: a powder mainly composed of inorganic materials; and a binder containing a resin that can be decomposed by the action of an alkaline gas.

[0004] Furthermore, Patent Document 2 discloses a method for obtaining a metal molded article, which uses a metal powder composition in which a lactic acid polymer as an organic binder is incorporated into metal powder. After heating a green molded body formed by molding the metal powder composition to remove the lactic acid polymer, the body is then fired to obtain the metal molded article.

[0005] Furthermore, Patent Document 3 discloses a method for obtaining a sintered body, which uses a composition containing a biodegradable resin as an organic binder component to form a molded body, maintains the molded body in water containing a degrading enzyme that performs the function of decomposing the biodegradable resin, obtains a degreased body, and heats the degreased body to obtain a sintered body.

[0006] Furthermore, Patent Document 4 discloses a method for forming a three-dimensional object, which involves extruding a raw material containing an adhesive system and a powder material dispersed in the adhesive system to form a three-dimensional object.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2008-222535

[0010] Patent Document 2: Japanese Patent Application Publication No. 8-311504

[0011] Patent Document 3: Japanese Patent Application Publication No. 2000-38604

[0012] Patent Document 4: Japanese Patent Publication No. 2020-501941 Summary of the Invention

[0013] The technical problem that the invention aims to solve

[0014] From the perspective of shape or dimensional accuracy of the sintered body, the amount of binder relative to the inorganic material powder is small and suppressed to about 1%. Therefore, the green body is brittle and sometimes disintegrates or breaks during debinding and / or sintering, making it impossible to obtain the desired shape. Furthermore, the brittleness can be improved by using polymers with high inherent flexibility as binders. However, such polymers have high flowability, making it difficult to obtain green bodies with shapes such as monofilaments.

[0015] Therefore, the present invention was made in view of the above-mentioned technical problems, and its object is to provide an adhesive that provides a green body with improved brittleness and less brittleness.

[0016] Technical solution

[0017] To address the aforementioned technical problems, one embodiment of the present invention provides an organic binder characterized in that it is used to shape inorganic powders that enable sintering, the organic binder comprising: polyglycolic acid as a binder component; and a decomposition catalyst for polyglycolic acid or a precursor thereof.

[0018] Beneficial effects

[0019] According to one aspect of the invention, an organic adhesive can be provided that provides a green body that is not easily damaged. Detailed Implementation

[0020] The embodiments of the present invention will now be described in detail.

[0021] [Organic adhesives]

[0022] Organic binders are used in metal injection molding and other processes to form green bodies, which are precursors to the molded body, during the manufacture of molded bodies from inorganic powders. They contain organic substances such as resins as binder components. The binder is removed (degreased) from the molded green body to obtain a degreased body, which is then sintered to obtain the final inorganic material molded body in the form of a sintered body. In this embodiment, the organic binder contains polyglycolic acid as a binder component.

[0023] In this specification, "polyglycolic acid" is intended to include not only homopolymers having only structural units derived from glycolic acid, but also copolymers having structural units derived from glycolic acid and one or more other structural units. Examples of other structural units include structural units derived from carboxylic acid compounds and structural units derived from alcohol compounds.

[0024] Examples of carboxylic acid compounds include: oxalic acid, phenyl dicarboxylic acid, methane dicarboxylic acid, phenylmethane dicarboxylic acid, ethane dicarboxylic acid, phenylethane dicarboxylic acid, propane dicarboxylic acid, phenylpropane dicarboxylic acid, butane dicarboxylic acid, phenylbutane dicarboxylic acid, pentane dicarboxylic acid, phenylpentane dicarboxylic acid, hexane dicarboxylic acid, phenylhexane dicarboxylic acid, heptane dicarboxylic acid, phenylheptane dicarboxylic acid, octane dicarboxylic acid, phenylnonane dicarboxylic acid, decane dicarboxylic acid, phenyldecane dicarboxylic acid, dodecane dicarboxylic acid, phenyldodecane dicarboxylic acid, undecane dicarboxylic acid, phenylundecane dicarboxylic acid, ethylene dicarboxylic acid, phenylethylene dicarboxylic acid, propylene dicarboxylic acid, phenylpropylene dicarboxylic acid, butene dicarboxylic acid, phenylbutene dicarboxylic acid, pentene dicarboxylic acid, phenylpentene dicarboxylic acid, hexene dicarboxylic acid, phenylhexene dicarboxylic acid, and heptane dicarboxylic acid. Enyl dicarboxylic acid, phenylheptene dicarboxylic acid, octene dicarboxylic acid, phenyloctene dicarboxylic acid, nonene dicarboxylic acid, phenylnonene dicarboxylic acid, decene dicarboxylic acid, phenyldecene dicarboxylic acid, dodecene dicarboxylic acid, phenyldodecene dicarboxylic acid, undecene dicarboxylic acid, phenylundecene dicarboxylic acid, acetylene dicarboxylic acid, phenylacetylene dicarboxylic acid, propyne dicarboxylic acid, phenylpropyne dicarboxylic acid, butyne dicarboxylic acid, phenylbutyne dicarboxylic acid, pentyne dicarboxylic acid, phenylpentyne dicarboxylic acid, hexyne dicarboxylic acid, phenylhexyne dicarboxylic acid, heptyne dicarboxylic acid, phenylheptylene dicarboxylic acid, octyne dicarboxylic acid, phenyloctyne dicarboxylic acid, nonyne dicarboxylic acid, phenylnonyne dicarboxylic acid, decyne dicarboxylic acid, phenyldecyne dicarboxylic acid, dodecyne dicarboxylic acid, phenyldodecyne dicarboxylic acid, undecyne dicarboxylic acid, phenylundecyne dicarboxylic acid, hydroxybenzoic acid, phenyllactic acid (phenyl) hydroxyethanecarboxylicacid), hydroxypropionic acid, phenylhydroxypropionic acid, hydroxybutyric acid, phenylhydroxybutyric acid, hydroxyvalerate, phenylhydroxyvalerate, hydroxyhexanoic acid, phenylhydroxyhexanoic acid, hydroxyheptanoic acid, phenylhydroxyheptanoic acid, hydroxyoctanoic acid, phenylhydroxyoctanoic acid, hydroxynonanoic acid, phenylhydroxynonanoic acid, hydroxydecanoic acid, phenylhydroxydecanoic acid, hydroxydodecanic acid, phenylhydroxydodecanic acid, hydroxyundecanoic acid, phenylhydroxyundecanoic acid, hydroxyacrylic acid, phenylhydroxyacrylic acid, hydroxybutenoic acid, phenylhydroxybutenoic acid, hydroxypentenoic acid, phenylhydroxypentenoic acid, hydroxyhexenoic acid, phenylhydroxyhexenoic acid, hydroxyheptenoic acid, phenylhydroxyheptenoic acid Hydroxyoctenic acid, phenylhydroxyoctenic acid, hydroxynonenoic acid, phenylhydroxynonenoic acid, hydroxydecenoic acid, phenylhydroxydecenoic acid, hydroxydodecanenoic acid, phenylhydroxydodecanenoic acid, hydroxyundecenoic acid, phenylhydroxyundecenoic acid, hydroxypropynic acid, phenylhydroxypropynic acid, hydroxybutynic acid, phenylhydroxybutynic acid, hydroxypentynic acid, phenylhydroxypentynic acid, hydroxyhexynic acid, phenylhydroxyhexynic acid, hydroxyheptynic acid, phenylhydroxyheptynic acid, hydroxyocynic acid, phenylhydroxyocynic acid, hydroxynonynic acid, phenylhydroxynonynic acid, hydroxydecynic acid, phenylhydroxydecynic acid, hydroxydodecanynic acid, phenylhydroxydodecanynic acid, hydroxyundecynic acid or phenylhydroxyundecynic acid.

[0025] Examples of alcohol compounds include: benzene glycol, methanediol, phenylmethanediol, ethylene glycol, phenylethylene glycol, propylene glycol, phenylpropylene glycol, butanediol, phenylbutanediol, pentanediol, phenylpentanediol, hexanediol, phenylhexanediol, heptanediol, phenylheptanediol, octanediol, phenyloctanediol, nonanediol, phenylnonanediol, decanediol, phenyldecanediol, undecanediol, phenylundecanediol, dodecanediol, phenyldodecanediol, ethylene glycol, phenylethylenediol, propylene glycol, phenylpropylenediol, butenediol, phenylbutenediol, pentenediol, phenylpentenediol, hexenediol, phenylhexenediol, heptenediol, phenylheptanediol, etc. Enylene glycol, octened glycol, phenyl octened glycol, nonened glycol, phenyl nonened glycol, decened glycol, phenyl decened glycol, undecylene glycol, phenyl undecylene glycol, dodecylene glycol, phenyl dodecylene glycol, acetylened glycol, phenyl acetylened glycol, propylened glycol, phenyl propylened glycol, butylened glycol, phenyl butylened glycol, pentylened glycol, phenyl pentylened glycol, hexylened glycol, phenyl hexylened glycol, heptylened glycol, phenyl heptylened glycol, octylened glycol, phenyl octylened glycol, nonylened glycol, phenyl nonylened glycol, decylened glycol, phenyl decantylened glycol, undecylened glycol, phenyl undecylened glycol, dodecylened glycol, phenyl dodecylened glycol, glycerol or pentaerythritol.

[0026] From the perspective of high strength, polyglycolic acid is preferably a glycolic acid homopolymer. Furthermore, from the viewpoint of obtaining mechanical strength that is beneficial to the shape maintenance of the green body, the preferred weight-average molecular weight of polyglycolic acid is 1,000 or more and 1,000,000 or less, more preferably 10,000 or more and 500,000 or less, and even more preferably 20,000 or more and 300,000 or less.

[0027] Commercially available polyglycolic acid, such as Kuredux 100R90 (manufactured by KUREHA Co., Ltd.), can be used as an organic adhesive in this embodiment.

[0028] To the extent that it does not impair the effects of the present invention, the organic adhesive may contain one or more other resins in addition to polyglycolic acid as an adhesive component. Other resins that can be included as organic adhesives include: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polylactic acid, and polycaprolactone; acrylic resins such as polymethacrylate and polybutylene methacrylate; polyethers such as polymethylene glycol, polyethylene glycol, and polypropylene glycol; polyamides such as nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 6T, nylon 6I, nylon 9T, and nylon M5T; vinyl resins such as polyvinyl chloride, polyvinyl acetate, and polyvinyl alcohol; polyoxazolines such as poly-2-methyl-2-oxazoline, poly-2-ethyl-2-oxazoline, and poly-2-propyl-2-oxazoline; polycarbonate resins; polyetherimide resins; polysaccharides such as cellulose, methylcellulose, sucrose, and sucralose, or copolymers thereof; and Empower Materials Inc. Commercially available pyrolytic adhesive polymers such as QPAC (registered trademark) 25, QPAC (registered trademark) 40, QPAC (registered trademark) 100, QPAC (registered trademark) 130, and QPAC (registered trademark) PBC.

[0029] Organic adhesives may contain one or more additives, such as plasticizers and antioxidants, depending on the purpose of imparting elasticity, rigidity, toughness, and plasticity.

[0030] The amount of polyglycolic acid in the organic binder is preferably 0.1% to 100% by weight. As will be described later, in the case of the organic binder in this embodiment, the binder component is polyglycolic acid, thereby facilitating degreasing under mild conditions. Therefore, from the viewpoint of easy removal of the binder component from the green body, the amount of polyglycolic acid in the organic binder is more preferably 20% to 100% by weight, and even more preferably 50% to 100% by weight.

[0031] Furthermore, by using an organic adhesive whose binder component is polyglycolic acid, it is possible to obtain green bodies with improved brittleness and that are less prone to breakage.

[0032] Furthermore, the binder component is polyglycolic acid (PGA), thus, during debinding achieved through heat treatment, PGA can be decomposed through a depolymerization reaction and removed from the green body. Unlike pyrolysis, where the decomposition of polymer chains occurs randomly, depolymerization is a controlled decomposition that occurs from the ends of the polymer chains. In pyrolysis, decomposition occurs randomly, so a portion of the polymer chain may remain in the debinded body. If a portion of the polymer chain remains in the debinded body, it will remain in the sintered body as carbon during firing in the presence of oxygen. In contrast, the depolymerization reaction prevents a portion of the polymer chain from remaining in the debinded body. Therefore, it prevents the sintered body from remaining as carbon during firing in the presence of oxygen. Furthermore, the depolymerization reaction of PGA occurs at a lower temperature than the pyrolysis reaction. Therefore, debinding can be performed at a lower temperature compared to pyrolysis.

[0033] (First option for organic adhesives)

[0034] In the first embodiment of the organic adhesive, the organic adhesive contains a decomposition catalyst for polyglycolic acid or a precursor thereof.

[0035] In this specification, "decomposition catalyst for polyglycolic acid" refers to a substance that catalyzes reactions that reduce the molecular weight of polyglycolic acid, specifically a substance that catalyzes hydrolysis or transesterification reactions. Specifically, the decomposition catalyst is a salt containing metal ions, an organic acid, or a base. The salt or organic acid containing metal ions promotes the hydrolysis or transesterification reaction by acting on the carbonyl oxygen group of polyglycolic acid as a Lewis acid catalyst. Conversely, the base promotes the hydrolysis or transesterification reaction by acting on the terminal functional groups of polyglycolic acid as a Lewis base catalyst.

[0036] In this specification, "low molecular weight" means decomposition to a lower molecular weight compared to the original polyglycolic acid, and also includes changes to monomers, dimers or oligomers.

[0037] As a type of salt containing metal ions that functions as a decomposition catalyst, specifically, examples include organic or inorganic salts containing metal ions, such as lithium ions, beryllium ions, sodium ions, magnesium ions, aluminum ions, potassium ions, calcium ions, scandium ions, titanium ions, vanadium ions, chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, gallium ions, germanium ions, rubidium ions, strontium ions, yttrium ions, zirconium ions, niobium ions, molybdenum ions, technetium ions, ruthenium ions, rhodium ions, palladium ions, silver ions, cadmium ions, indium ions, tin ions, cesium ions, barium ions, lanthanum ions, hafnium ions, tantalum ions, tungsten ions, rhenium ions, osmium ions, iridium ions, gold ions, mercury ions, thallium ions, or lead ions, etc. Among them, organic or inorganic salts containing titanium ions, germanium ions, zirconium ions, tin ions or lanthanide ions are preferred, and titanium ethoxide, titanium propoxide, titanium butoxide, titanium chloride, titanium sulfate, titanium hydroxide, titanium oxide, tetramethylgermanium, tetraethylgermanium, tetraphenylgermanium, germanium chloride, germanium sulfate, zirconium hydroxide, germanium oxide, zirconium ethoxide, zirconium propoxide, zirconium butoxide, zirconium chloride, zirconium sulfate, zirconium oxide, tin butyrate, tin valerate, tin hexanoate, tin heptanoate, tin octanoate, tin nonanoate, tin decanoate, tin chloride, tin sulfate, tin hydroxide and tin oxide are preferred.

[0038] Organic acids that function as decomposition catalysts include, specifically, organic carboxylic acid compounds, organoboronic acid compounds, organophosphate compounds, and organosulfonic acid compounds. Among these, organic carboxylic acid compounds, organophosphate compounds, or organosulfonic acid compounds are preferred, and organic carboxylic acid compounds are more preferred. Organic carboxylic acid compounds specifically include, formic acid, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, phthalic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, pyromellitic acid, ethyl phosphate, diethyl phosphate, propyl phosphate, dipropyl phosphate, butyl phosphate, dibutyl phosphate, propyl phosphate, dipropyl phosphate, hexyl phosphate, dihexyl phosphate, heptyl phosphate, diheptyl phosphate, octyl phosphate, dioctyl phosphate, p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, or trifluoromethanesulfonic acid, etc.

[0039] As bases that function as decomposition catalysts, examples include nitrogen-containing organic amine compounds or heterocyclic compounds. Specifically, examples include: pyrrole, indole, pyridine, aminopyridine, dimethylaminopyridine, quinoline, diazabicyclononene, or diazabicycloundecene, etc.

[0040] In this specification, "precursor to a decomposition catalyst" refers to a substance that does not function as a decomposition catalyst itself, but undergoes a structural change through some action, thus becoming a decomposition catalyst. When the decomposition catalyst is an organic acid, esters formed from the organic acid and alcohols or phenols, or anhydrides of organic acids, are equivalent to precursors to the decomposition catalyst. Specifically, examples include: methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, hexyl formate, heptyl formate, octyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, hexyl acetate, heptyl acetate, octyl acetate, oxalic anhydride, succinic anhydride, malonic anhydride, glutaric anhydride, adipic anhydride, phthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripropyl phosphate, trihexyl phosphate, triheptyl phosphate, and trioctyl phosphate. Methyl p-toluenesulfonate, ethyl p-toluenesulfonate, propyl p-toluenesulfonate, butyl p-toluenesulfonate, pentyl p-toluenesulfonate, hexyl p-toluenesulfonate, heptyl p-toluenesulfonate, octyl p-toluenesulfonate, methyl benzenesulfonate, ethyl benzenesulfonate, propyl benzenesulfonate, butyl benzenesulfonate, pentyl benzenesulfonate, hexyl benzenesulfonate, heptyl benzenesulfonate, octyl benzenesulfonate, methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, butyl methanesulfonate, pentyl methanesulfonate, heptyl methanesulfonate, octyl methanesulfonate, methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate, propyl trifluoromethanesulfonate, butyl trifluoromethanesulfonate, pentyl trifluoromethanesulfonate, hexyl trifluoromethanesulfonate, heptyl trifluoromethanesulfonate, or octyl trifluoromethanesulfonate, etc. When the decomposition catalyst is a base, amide compounds, imine compounds, nitrile compounds, or isocyanate compounds are equivalent to precursors of the decomposition catalyst. Specifically, examples include: formamide, acetamide, benzamide, N,N-dimethylformamide, acetanilide, glyoxal bis(2-hydroxyaniline), N-salicylaniline, benzophenone imine, benzylaniline, benzyl-2-naphthylamine, N,N'-dibenzomidine, naphthalene-1,2-dionitrile, 3,3'-imine dipropionitrile, butyl isocyanate, pentyl isocyanate, hexyl isocyanate, octyl isocyanate, phenyl isocyanate, methoxyphenyl isocyanate, naphthyl isocyanate, adamantane isocyanate, m-phenylenedimethyl isocyanate, or m-phenylenedimethyl diisocyanate, etc.

[0041] The amount of the decomposition catalyst or its precursor in the organic binder is preferably 0.001% to 50% by weight, more preferably 0.001% to 40% by weight, and even more preferably 0.005% to 30% by weight, relative to the total amount of the organic binder, which also includes the decomposition catalyst or its precursor.

[0042] Depending on the compound, the decomposition catalyst or its precursor can also be a synthetic catalyst used in the manufacture of polyglycolic acid. When such a compound is used as a decomposition catalyst or its precursor, it can also be added during the manufacture of polyglycolic acid to serve as a synthetic catalyst, and the compound remaining in the polyglycolic acid can be used as a decomposition catalyst or its precursor contained in the organic binder. Furthermore, even when a compound that can be used as a decomposition catalyst or its precursor is used as a synthetic catalyst during the manufacture of polyglycolic acid, the same or different decomposition catalysts or precursors can be added separately to the organic binder.

[0043] Decomposition catalysts and precursors can be used in single or combined combinations of two or more.

[0044] By incorporating a decomposition catalyst or its precursor into the organic binder itself, the removal of binder components can be promoted during degreasing without adding catalysts to the green body or the processing solution. Furthermore, since a processing solution containing a decomposition catalyst is unnecessary, immersion of the green body in the processing solution is eliminated, and the decomposition-promoting effect generated by the catalyst can be achieved even in degreasing achieved through heat treatment.

[0045] (Second option for organic adhesives)

[0046] In the second embodiment of the organic adhesive, polyglycolic acid is used as the resin molded body obtained by molding the polyglycolic acid itself, which satisfies the following condition (A).

[0047] (A) The weight loss rate in water at 80°C for 7 days is more than 50%.

[0048] Specifically, condition (A) refers to the conditions when the resin molding body is a filament with a monofilament diameter of 20µm. Furthermore, the weight loss rate in water at 80°C for 7 days was determined by the following method: 1g of the molding body was added to a tubular bottle, along with 50ml of deionized water. The bottle was then placed in a thermostat at 80°C for 7 days. The contents of the bottle were then gravity-filtered using filter paper to dry the decomposition residue remaining on the filter paper. The weight after drying was measured, and the weight loss rate (%) compared to the initial weight was calculated. It should be noted that the drying conditions were achieved by standing for 24 hours at 23°C and a dew point of -40°C.

[0049] Furthermore, the polyglycolic acid in this scheme is more preferably a polyglycolic acid whose resin molding meets the following condition (A'), and even more preferably a polyglycolic acid that meets the following condition (A'').

[0050] (A') The weight loss rate in water at 80°C for 7 days is more than 70%.

[0051] (A'') The weight loss rate in water at 80°C for 7 days is over 90%.

[0052] Even when present in the green body as a binder component, this polyglycolic acid exhibits excellent decomposition in water. As a result, by using an organic binder that utilizes this polyglycolic acid, the removal rate of the binder component can be improved when the green body is immersed in water and degreased.

[0053] It should be noted that the desired weight loss rate in the molded article can be achieved by adjusting the crystallinity of polyglycolic acid. For example, by rapidly cooling after heating and melting, polyglycolic acid with low crystallinity can be obtained, which can improve the weight loss rate in water at 80°C for 7 days. Furthermore, by using copolymers of glycolic acid with other monomer species, crystallinity can also be reduced, resulting in an increased weight loss rate in water at 80°C for 7 days. Other monomer species include carboxylic acid compounds and alcohol compounds, which serve as structural units for the aforementioned copolymers.

[0054] Furthermore, by including hydrophilic chemical structures in the polymer chain of polyglycolic acid, a large amount of water required for hydrolysis can be incorporated into the polymer, further accelerating the decomposition of the adhesive components in water. For example, by including structural units with hydrophilic chemical structures as one of the structural units constituting polyglycolic acid, the hydrophilic chemical structures can be incorporated into the polymer chain of polyglycolic acid.

[0055] As structural units with hydrophilic chemical structures, examples include those with polar chemical structures, such as structural units containing ether or ester functional groups. Specifically, structural units derived from hydroxycarboxylic acids, diols, or dicarboxylic acids other than glycolic acid are preferred. Examples of structural units derived from substances such as: hydroxybenzoic acid, phenyllactic acid, hydroxypropionic acid, phenylhydroxypropionic acid, hydroxybutyric acid, phenylhydroxybutyric acid, hydroxyvalerate, phenylhydroxyvalerate, hydroxyhexanoic acid, phenylhydroxyhexanoic acid, methanediol, phenylmethanediol, ethylene glycol, phenylethylene glycol, propylene glycol, phenylpropylene glycol, butanediol, phenylbutanediol, pentanediol, phenylpentanediol, hexanediol, phenylhexanediol, glycerol, oxalic acid, phenyl dicarboxylic acid, methanedicarboxylic acid, phenylmethanedicarboxylic acid, ethanedicarboxylic acid, phenylethanedicarboxylic acid, propanedicarboxylic acid, phenylpropanedicarboxylic acid, butanedicarboxylic acid, phenylbutanedicarboxylic acid, pentanedicarboxylic acid, phenylpentanedicarboxylic acid, hexanedicarboxylic acid, or phenylhexanedicarboxylic acid.

[0056] It should be noted that the decomposition catalyst or its precursor described in the first scheme can also be added to the organic binder in the second scheme.

[0057] [Composition for manufacturing inorganic material molded articles]

[0058] The composition for manufacturing inorganic material molded articles in this embodiment includes: sinterable inorganic powder; and the organic binder of this embodiment.

[0059] In this specification, "sinterable inorganic powder" refers to a powder that, when heated to a temperature below its melting point and producing a partial liquid phase, can be sintered to form a solid. Specific examples of sinterable inorganic powders include: metal powders, metal oxide powders, metal carbide powders, metal nitride powders, or metal boride powders. More specifically, metal powders include: powders of iron, aluminum, copper, titanium, molybdenum, zirconium, cobalt, nickel, or chromium; and alloy powders such as stainless steel powder, high-speed powder, superalloy powder, and magnetic material powder, which are mainly composed of these metals. Metal oxide powders include: powders of alumina, silicon oxide, zirconium oxide, titanium oxide, mullite, cordierite, beryllium oxide, or thorium oxide. Metal carbide powders include: powders of silicon carbide, boron carbide, zirconium carbide, titanium carbide, zirconium carbide, or tungsten carbide. Examples of metal nitride powders include: silicon nitride, aluminum nitride, boron nitride, titanium nitride, zirconium nitride, vanadium nitride, and niobium nitride. Examples of metal boride powders include: chromium boride and zirconium boride.

[0060] In one embodiment, with regard to the ratio of inorganic powder to organic binder in the composition for manufacturing inorganic material molded articles, the organic binder is preferably 1 to 30 parts by weight relative to 100 parts by weight of inorganic powder, more preferably 1 to 20 parts by weight, and even more preferably 1 to 10 parts by weight.

[0061] In addition to inorganic powder and organic binder, the composition for manufacturing inorganic material molded articles may also contain additives. Examples of additives include dispersants (lubricants), plasticizers, or antioxidants. One additive or two or more additives may be used. When additives are included in the composition for manufacturing inorganic material molded articles, the content of the additives in the composition is preferably 1% to 20% by weight, more preferably 1% to 10% by weight, and even more preferably 1% to 5% by weight.

[0062] The components of the composition for manufacturing inorganic material molded articles can be mixed using various mixing machines, such as pressure or twin-arm kneading mixers, roller mixers, Banbury mixers, single-screw or twin-screw extruders. Polyglycolic acid is easily hydrolyzed, so it is ideal to mix them in an atmosphere with the lowest possible dew point.

[0063] (Manufacturing method of inorganic material molded body)

[0064] The following describes a method for manufacturing inorganic material molded articles using the inorganic material molding composition of this embodiment.

[0065] [Forming of the green body]

[0066] First, a green body, i.e., a preform, is obtained by molding the inorganic material molding composition into a specified shape. The green body can be formed using various molding methods, such as injection molding, extrusion molding, compression molding, and calendering. Among these, injection molding and extrusion molding are used in the process, with injection molding being particularly preferred. Polyglycolic acid is easily hydrolyzed; therefore, it is ideal to mold it in an atmosphere with the lowest possible dew point.

[0067] The composition for manufacturing inorganic material molded articles can use the compound itself or the granules obtained by granulation of the compound.

[0068] [Manufacturing of defatted bodies]

[0069] By subjecting the obtained green body to a degreasing process, a degreased body is obtained after the binder components have been removed from the green body. Various degreasing methods are known; in this embodiment, a method utilizing water treatment or heat treatment to decompose and remove the binder components is preferred.

[0070] The conditions for degreasing in water treatment can be appropriately set according to the size and shape of the green body, the composition of the organic binder used, and the composition of the inorganic material molding composition used.

[0071] For example, the water temperature is 80℃~160℃, preferably 80℃~150℃, and more preferably 80℃~120℃.

[0072] In addition, the processing time can be, for example, 1 hour to 10 days, 1 hour to 7 days, or 1 hour to 3 days.

[0073] Water treatment can be carried out by immersing the green body in water and letting it stand.

[0074] The conditions for degreasing during heat treatment can be appropriately set according to the size and shape of the green body, the composition of the organic binder used, and the composition of the inorganic material molding composition used.

[0075] For example, heat treatment can be carried out in an oxidizing, reducing, or inert gas atmosphere. Furthermore, heat treatment can be carried out under reduced pressure, at atmospheric pressure, or under pressure.

[0076] As described above, the degreasing in the heat treatment of this embodiment is not a random pyrolysis reaction caused by the decomposition of polymer chains, but rather a decomposition of polyglycolic acid from the ends of the polymer chains by a depolymerization reaction. Therefore, the heat treatment temperature only needs to be the temperature at which the depolymerization reaction of polyglycolic acid occurs, typically 200°C or higher, preferably 210°C or higher, and more preferably 220°C or higher. Furthermore, the heat treatment temperature is preferably a temperature that can suppress the pyrolysis reaction, typically 300°C or lower, preferably 280°C or lower, and more preferably 250°C or lower. The heating rate can be, for example, 0.1°C / min to 100°C / min. The holding time after heating is, for example, 1 hour to 50 hours. The heat treatment environment can be pressurized, atmospheric pressure, or depressurized, but depressurization is preferred. The heat treatment atmosphere can be air, hydrogen, or an inert gas such as nitrogen, but an inert gas is preferred.

[0077] [Manufacturing of Inorganic Material Molded Articles]

[0078] By sintering the obtained degreased body, the inorganic powder in the degreased body is sintered to obtain an inorganic material molded body as a sintered body. The sintering conditions can be appropriately set according to the size and shape of the degreased body and the composition of the inorganic material molded body manufacturing composition used. Firing can generally be carried out in an oxidizing, reducing, or inert gas atmosphere. In addition, it can be carried out under reduced pressure, normal pressure, or pressurized pressure. The sintering temperature can be, for example, 150°C to 2000°C. The heating rate can be 0.1°C / min to 100°C / min. The holding time after heating is, for example, 10 minutes to 50 hours. The sintering environment can be pressurized, atmospheric pressure, or reduced pressure, but atmospheric pressure is preferred. The sintering atmosphere can be air, hydrogen, or an inert gas such as nitrogen, but an inert gas is preferred.

[0079] (Summarize)

[0080] One aspect of the present invention provides an organic binder for enabling the molding of sinterable inorganic powders, the organic binder comprising: polyglycolic acid as a binder component; and a decomposition catalyst for polyglycolic acid or a precursor thereof.

[0081] Furthermore, one embodiment of the present invention comprises an organic adhesive containing the aforementioned polyglycolic acid decomposition catalyst or a precursor thereof.

[0082] Furthermore, in one embodiment of the organic adhesive of the present invention, the polyglycolic acid is a resin molded body obtained by molding the polyglycolic acid that satisfies the following condition (A).

[0083] (A) The weight loss rate in water at 80°C for 7 days is more than 50%.

[0084] One aspect of the present invention provides a composition for manufacturing an inorganic material molded body comprising: 100 parts by weight of sinterable inorganic powder; and 1 to 30 parts by weight of the aforementioned organic binder.

[0085] In one aspect of the present invention, the green blank is a green blank formed by molding the above-mentioned inorganic material molding composition.

[0086] One embodiment of the present invention is a degreased body obtained by removing the polyglycolic acid from the above-mentioned green body.

[0087] One embodiment of the present invention is an inorganic material molded body formed by firing the above-mentioned degreased body.

[0088] One aspect of the present invention provides a method for manufacturing an inorganic material molded body, comprising the following steps: a step of molding the above-mentioned inorganic material molded body manufacturing composition to obtain a green body; a step of removing the above-mentioned polyglycolic acid contained in the green body by depolymerizing the above-mentioned polyglycolic acid to obtain a degreased body; and a step of firing the above-mentioned degreased body to obtain an inorganic material molded body.

[0089] One aspect of the present invention provides a method for manufacturing an inorganic material molded body, comprising the following steps: a step of molding the above-mentioned inorganic material molded body manufacturing composition to manufacture a green body; a step of decomposing and removing the above-mentioned polyglycolic acid contained in the green body by contacting the green body with water at 80°C to 160°C to obtain a degreased body; and a step of firing the above-mentioned degreased body to obtain an inorganic material molded body.

[0090] The following embodiments are provided to further illustrate the implementation of the present invention. It is self-evident that the present invention is not limited to the following embodiments, and various solutions may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the disclosed technical means are also included within the technical scope of the present invention. In addition, all documents described in this specification are incorporated herein by reference.

[0091] Example

[0092] (Measurement Method)

[0093] The methods and / or conditions for measuring various physical properties in the following examples are described below.

[0094] [Weight-average molecular weight]

[0095] Approximately 10 mg of the sample was dissolved in 0.5 mL of dimethyl sulfate (DMSO) at 150 °C and cooled to room temperature. This solution was then diluted to 10 mL with 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and analyzed. The analysis conditions are shown below.

[0096] Apparatus: shodex GPC-104 (detector: RI, column: HFIP-606M×2).

[0097] Solvent: 5 mM CF3COONa in HFIP.

[0098] The weight-average molecular weight was calculated using polymethyl methacrylate (PMMA) as a standard.

[0099] [Thermogravimetric determination]

[0100] Approximately 10 mg of sample was accurately weighed and placed in a ceramic dish, and the determination was performed under a nitrogen atmosphere. The determination conditions are shown below.

[0101] Device: TGA / DSC3+.

[0102] Temperature: 25℃ - (10℃ / min) - 235℃ (hold for 10 min).

[0103] Flexural modulus

[0104] Device: AUTOGRAPH AG-2000E manufactured by Shimadzu Corporation.

[0105] Test piece shape: 13mm width, 3mm thickness, 128mm length.

[0106] Distance between lower support points: 48mm.

[0107] Test speed: 1 mm / min.

[0108] Temperature: 23℃.

[0109] [Tensile Strength]

[0110] Device: AUTOGRAPH AG-2000E manufactured by Shimadzu Corporation.

[0111] Test piece shape: ASTM D638 Type-I.

[0112] Distance between fixtures: 115mm.

[0113] Test speed: 50 mm / min.

[0114] Temperature: 23℃.

[0115] (Example 1) Decomposition Action in Water Treatment 1

[0116] [Preparation Example 1]

[0117] In a dry chamber controlled to a dew point below -40°C, glycolide (manufactured by KUREHA, free acid concentration 2 eq / t) added to a beaker was heated to 100°C until completely melted. Dodecanol (manufactured by Pure Chemical Industries) at 0.18 mol% relative to glycolide and stannous chloride dihydrate (manufactured by Kanto Chemical Industries) at 5 ppm relative to glycolide were added to the molten glycolide and stirred for another 5 minutes after homogenization. The molten liquid was then rapidly transferred to a glass test tube and polymerized at 170°C for 7 hours. Afterward, it was cooled to room temperature and pulverized using a pulverizer to obtain polyglycolic acid (PGA) pulverized material. The PGA pulverized material was melt-blended using a twin-screw extruder (manufactured by Toyo Seiki, 2D25S) to obtain PGA granules. The obtained PGA had a weight-average molecular weight of 220,000. In this PGA, the stannous chloride dihydrate added during polymerization was carried in as is and functioned as a decomposition catalyst.

[0118] Using a spinning machine "C0115" manufactured by Fiber Extrusion Technology, filaments with a monofilament diameter of 20µm and a draw ratio of 2 were spun from the obtained PGA particles, resulting in experimental filaments for water treatment (filament A1).

[0119] [Preparation Example 2]

[0120] The PGA particles obtained in Preparation Example 1 were mixed with poly-L-lactic acid (PLLA; manufactured by Nature Works, 4032D) at a weight ratio of 50:50, and stannous chloride dihydrate was further added in such a way that the final amount of stannous chloride dihydrate was 5 ppm, thereby obtaining a mixture of PGA, PLLA and stannous chloride dihydrate.

[0121] The mixture was used instead of PGA particles, and otherwise, the test filament (filament B1) was obtained in the same manner as in Preparation Example 1.

[0122] [Preparation Example 3]

[0123] By adding 5 ppm of stannous chloride dihydrate to PLLA (manufactured by Nature Works, 4032D), a mixture of PLLA and stannous chloride dihydrate was obtained. Using this mixture instead of PGA particles, experimental filaments (filament a1) were otherwise obtained in the same manner as in Preparation Example 1.

[0124] [Evaluation of the decomposition]

[0125] 1 g of test filament was measured into a tubular flask, and 50 ml of deionized water was added. The flask and flask were then placed in a thermostat at 80°C. After standing for 7 days, the contents of the flask were filtered using pre-weighed filter paper and a funnel, and the separated decomposition residue was dried along with the filter paper. As drying conditions, the flask was placed at 23°C and a humidity level of -40°C for 24 hours. The weight of the residue was then obtained by measuring the weight of the residue and the filter paper and subtracting the initial weight of the filter paper. The weight loss rate (wt.%) was calculated by dividing the difference between the weight of the residue and the initial weight of the test filament by the initial weight of the test filament. The results are shown in Table 1.

[0126] [Table 1]

[0127]

[0128] (Example 2) Decomposition Action 2 in Water Treatment

[0129] [Preparation Example 4]

[0130] Similar to Preparation Example 1 of Example 1, a test filament (filament A2) for water treatment was obtained.

[0131] [Preparation Example 5]

[0132] 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA) was added at a concentration of 9% by weight relative to the PGA obtained in Preparation Example 1, thereby obtaining a mixture of PGA and BTDA. Using this mixture instead of PGA particles, experimental filaments (filament A3) were otherwise obtained in the same manner as in Preparation Example 1.

[0133] [Preparation Example 6]

[0134] The amount of BTDA added was set to 23% by weight. Otherwise, the experimental filament (filament A4) was obtained in the same manner as in Preparation Example 5.

[0135] [Preparation Example 7]

[0136] The experimental filament (filament a2) was obtained in the same manner as in Preparation Example 3 of Example 1.

[0137] [Evaluation of the decomposition]

[0138] The period of resting in a thermostat at 80°C was changed to 3 days, and the weight loss rate (wt.%) was calculated in the same manner as in Example 1. The results are shown in Table 2.

[0139] [Table 2]

[0140]

[0141] (Example 3) Decomposition during heat treatment

[0142] [Synthesis of PGA]

[0143] 1.3 kg of a 70% by mass aqueous solution of glycolic acid (Chemours, high purity grade) was added to a 1 L separable flask. The solution was then heated from room temperature to 215 °C under atmospheric pressure with stirring, allowing water to be distilled off while the polycondensation reaction proceeded. The pressure was then slowly reduced from atmospheric pressure to 3 kPa, and the flask was heated at 215 °C for 3 hours, distilling off unreacted raw materials and other low-boiling fractions to obtain polyglycolic acid (PGA) with a weight average molecular weight of 20,000.

[0144] [Evaluation of depolymerization speed]

[0145] Ferrous chloride or titanium tetrabutoxide, acting as a decomposition catalyst, was added to HFIP to prepare solutions containing ferrous chloride and titanium tetrabutoxide, respectively. The solutions containing ferrous chloride or titanium tetrabutoxide were then added to PGA to dissolve the PGA in each solution. Subsequently, HFIP was removed by vacuum drying, thereby obtaining PGA containing 1 mol% of the decomposition catalyst.

[0146] Sample A was designated as the sample containing ferrous chloride solution, sample B as the sample containing titanium tetrabutoxide solution, and sample C as the sample containing PGA without a decomposition catalyst. Thermogravimetric analysis (TGA) was performed on each sample. The weight loss rate (wt.% / h) was calculated by dividing the rate of decrease in TGA after 10 minutes at 235°C by the time (10 minutes). The results are shown in Table 3.

[0147] [Table 3]

[0148]

[0149] [Evaluation of residual organic adhesives after heat treatment]

[0150] Approximately 0.2 mg of PGA obtained in Preparation Example 1 and PLLA obtained in Preparation Example 3 were weighed and subjected to gas chromatography for mass analysis. The amount of depolymerization material (lactide, glycolide) produced per 0.1 mg of resin was determined at 235 °C for 10 minutes. The results are shown in Table 4.

[0151] [Table 4]

[0152]

[0153] It can be assumed that PGA produces more depolymerized substances compared to PLLA, and a portion of the polymer chain is less likely to remain in the depolymerized body.

[0154] (Example 4) Physical property determination

[0155] Tensile and flexural test pieces of PGA and PLLA were produced by injection molding using a Toshiba Machine Co., Ltd. IS75E injection molding machine. The PGA used was the PGA obtained in Preparation Example 1. The PLLA used was the same as that used in Examples 1 and 2 (Nature Works, 4032D). After annealing each test piece in a nitrogen atmosphere at 120°C for 1 hour, the tensile strength and flexural modulus were evaluated. The results are shown in Table 5.

[0156] [Table 5]

[0157]

[0158] Both PGA and PLLA are hydrolyzable polymers, but compared with PLLA, PGA has a higher flexural modulus and tensile strength. Therefore, it can be said that when using PGA as a binder component, a green body with small deformation under external forces and not easily damaged can be obtained.

[0159] Industrial availability

[0160] This invention can be used to manufacture inorganic material molded articles.

Claims

1. An organic adhesive, characterized in that, Inorganic powder molding that enables sintering The organic adhesive contains: Polyglycolic acid as an adhesive component; and The decomposition catalyst or precursor of the polyglycolic acid. The polyglycolic acid has a weight-average molecular weight of 1,000 or more and 1,000,000 or less. The decomposition catalyst is a substance that catalyzes the transesterification reaction. The polyglycolic acid is a resin molded body obtained by molding the polyglycolic acid that satisfies the following condition (A): (A) The weight loss rate in water at 80°C for 7 days is more than 50%.

2. A composition for manufacturing an inorganic material molded body, the composition comprising: 100 parts by weight of sinterable inorganic powder; and 1 to 30 parts by weight of the organic binder according to claim 1.

3. A green blank, said green blank being formed by molding the composition for manufacturing inorganic material molded articles according to claim 2.

4. A method for manufacturing an inorganic material molded body, the method comprising the following steps: The process of molding the composition for manufacturing inorganic material molded articles according to claim 2 to obtain a green body; The process of removing polyglycolic acid from the green body by depolymerizing the polyglycolic acid contained therein to obtain a degreased body; and The process of firing the degreased body to obtain a molded body of inorganic material. The degreasing process is carried out at a temperature above 200℃ and below 300℃.

Images