Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J105/00—Adhesives based on polysaccharides or on their derivatives, not provided for in groups C09J101/00 or C09J103/00
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/05—Alcohols; Metal alcoholates
  • C08K5/053—Polyhydroxylic alcohols

Definitions

• the present invention relates to an aqueous adhesive, and a molded body produced by using the aqueous adhesive.
• Phenol resin compositions have been used, as a composition to be used for producing molded bodies such as insulating materials, soundproofing materials, and wood board products comprising inorganic fibers such as glass wool, rock wool, and ceramic fibers, since they are excellent in performances such as mechanical strength and are low-cost.
• the inorganic fibers are coated with a composition, and the inorganic fibers coated with the composition are molded (formed or shaped) into a shape of an objective molded body, and then the composition is cured by heating so as to obtain the objective molded body.
• formaldehyde-containing phenol resin compositions have widely been used as such a composition.
• the environmental standard has become stricter than ever in recent years, thus a composition containing no formaldehyde (or formaldehyde-free composition) is required.
• Patent Literatures 1 to 2 disclose, as the composition containing no formaldehyde, compositions comprising a saccharide as a main component and an ammonium salt of a polycarboxylic acid or an inorganic acid ammonium salt and so on.
• Patent Literature 1 discloses a method for producing an insulating or soundproofing fiber glass product, which method comprises a step of spraying an aqueous binder solution containing no formaldehyde on a fiber mat.
• the aqueous binder solution comprises a Maillard reactant, and the Maillard reactant is selected from (i) an amine reactant composed of a polycarboxylic acid ammonium salt etc. and (ii) one or more carbohydrate reactants containing one or more reducing sugars and so on (see Patent Literature 1, claims 1 to 5, etc.).
• Patent Literature 2 discloses a thermosetting binder comprising a glucide, an ammonium salt, a surfactant, a silane coupling agent, and a water repellent (see Patent Literature 2, claim 1).
• Patent Literature 2 further discloses, as an embodiment of the thermosetting binder, a composition of a binder further comprising a curing modifier such as ethylene glycol in Examples (see Patent Literature 2, claim 13, [0063], Tables 22-24 of [0091] to [0093]).
• the obtainable molded body may be inferior in strength and elastic modulus after thermosetting, compared to that produced from a conventional formaldehyde-containing phenol resin composition.
• compositions of Patent Literatures 1 to 2 contain no formaldehyde and are therefore environmentally preferable. However, it is difficult for the compositions to sufficiently improve mechanical properties (for example, tensile elastic modulus and tensile strength) of an inorganic fiber molded material and a woody molded material. Since the compositions of Patent Literatures 1 to 2 have low curing rate, they may reduce production efficiency of the molded material. It may be difficult to apply the compositions due to quick increase in viscosity. Thus physical properties (shear strength, tensile strength) of the molded material may be degraded. Furthermore, the molded material thus produced may easily absorb moisture in air, and water resistance of the molded material may degrade.
• mechanical properties for example, tensile elastic modulus and tensile strength
• the present invention has been made and an object thereof is to provide an aqueous adhesive containing no formaldehyde which can contribute to an improvement in mechanical properties such as strength and elastic modulus of a molded material to be produced, even compared to a formaldehyde-containing phenol resin composition, and the molded material obtainable by using the aqueous adhesive.
• an aqueous adhesive comprising a specific polyalcohol inhibits increase in viscosity, increases cuing rate, and is useful for producing a molded material efficiently, thus enabling not only further improvement in mechanical properties of the molded material, but also improvement in water resistance of the molded material to a higher level, thus the present invention has been completed.
• the present invention provides, in an aspect, an aqueous adhesive comprising a saccharide and a polyalcohol having a boiling point of 200 to 285°C, wherein the polyalcohol is comprised in an amount of 5.0 to 30.0 parts by weight (in terms of solid content) based on 100 parts by weight (in terms of solid content) of the total weight of the saccharide and the polyalcohol.
• the present invention provides, in an embodiment, the above-mentioned aqueous adhesive, wherein the polyalcohol comprises at least one selected from diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol.
• the present invention provides, in another embodiment, the above-mentioned aqueous adhesive, further comprising an inorganic acid salt.
• the present invention provides, in a preferred embodiment, the above-mentioned aqueous adhesive, wherein the inorganic acid salt comprises an inorganic acid ammonium salt.
• the present invention provides, in another aspect, a molded material (molded body or molded article) comprising a cured material of the above-mentioned aqueous adhesive.
• An aqueous adhesive according to an embodiment of the present invention comprises a saccharide and a polyalcohol having a boiling point of 200 to 285°C, the polyalcohol being comprised in an amount of 5.0 to 30.0 parts by weight (in terms of solid content) based on 100 parts by weight (in terms of solid content) of the total weight of the saccharide and the polyalcohol, so that curing rate is improved while increase in viscosity being inhibited, and thus the aqueous adhesive can contribute to produce an applied or sprayed material efficiently. Since inhibition of increase in viscosity and improvement in curing rate are conflicting properties, the aqueous adhesive according to the embodiment of the present invention are excellent in both these conflicting properties.
• aqueous adhesive according to the embodiment of the present invention When increase in viscosity of the aqueous adhesive according to the embodiment of the present invention is inhibited, it becomes possible to uniformly apply or spray the aqueous adhesive on a base material of a molded material.
• uniform application or spraying of the aqueous adhesive according to the embodiment of the present invention shear strength, tensile strength and tensile elastic modulus of an obtainable molded material (molded body or molded article) are improved and water resistance of the molded material is improved, and the molded material hardly absorb moisture in air.
• the aqueous adhesive according to the embodiment of the present invention is useful for producing various molded materials, and is eminently suitable for producing a molded material comprising inorganic fibers and a molded material comprising a woody material.
• An aqueous adhesive according to an embodiment of the present invention comprises a saccharide.
• the saccharide as used herein comprises at least one selected from (a) a common saccharide (unmodified sugar) and a below-mentioned (A) modified sugar, and is not particularly limited as long as the objective aqueous adhesive of the present invention is obtainable.
• the “common saccharide (unmodified sugar) (a)” is not particularly limited as long as it is generally called a saccharide and the objective aqueous adhesive of the present invention is obtainable.
• the saccharide (a) include monosaccharide, disaccharide, trisaccharide, tetrasaccharide, polysaccharide, and other oligosaccharides.
• hexoses such as glucose, psicose, fructose, sorbose, tagatose, allose, altrose, mannose, gulose, idose, galactose, talose, fucose, fuculose, and rhamnose
• trioses such as ketotriose (dihydroxyacetone) and aldotriose (glyceraldehyde)
• tetroses such as erythrulose, erythrose, and threose
• pentoses such as ribulose, xylulose, ribose, arabinose, xylose, lixose, and deoxyribose.
• Example of the “disaccharide” include sucrose, lactose, maltose, trehalose, turanose, and cellobiose.
• Examples of the “trisaccharide” includes raffinose, melezitose, maltotriose, and 1-kestose (GF2).
• Examples of the “tetrasaccharide” include acarbose, stachyose, and nystose (GF3).
• polysaccharide examples include glycogen, starch (amylose, amylopectin, etc.), cellulose, dextrin, glucan, N-acetylglucosamine, chitin, and inulin (including fructofuranosylnystose: GF4).
• other oligosaccharides include fructooligosaccharide, galactooligosaccharide, and mannan oligosaccharide. These “saccharides” can be used alone or in combination.
• the “saccharide (a)” preferably includes a structure derived from sucrose.
• the sucrose is a sugar in which glucose and fructose are bonded together, and when the sugar is hydrolyzed, glucose and fructose are produced.
• the “saccharide (a)” can further comprise an isomerized sugar.
• the isomerized sugar comprises fructose and glucose as main components, and is prepared by isomerizing a corn syrup consisting of mainly glucose with an enzyme or an alkali. Since the main components of the isomerized sugar are fructose and glucose, the isomerized sugar is not substantially different from a common saccharide.
• the saccharide (a) can further comprise, for example, a sugar syrup.
• a sugar syrup refers to a syrup prepared by removing dietary fibers and impurities from sugar raw materials such as sugarcane, sugar beet, sugar maple, and Palmyra palm, or refers to a viscous liquid (a molasses) obtainable when sugar is purified from raw materials, which viscous liquid also comprises components other than sugar.
• sugar syrup examples include waste molasses, ice molasses (or high grade molasses), white honey, caramel, crude saccharide, sugar solution, and juices of sugar raw materials (sugarcane, sugar beet, sugar maple, Palmyra palm and so on).
• the sugar syrup preferably comprises at least one selected from the waste molasses, the ice molasses (or high grade molasses) and the crude saccharide.
• the modified sugar (A) refers to a product (a compound) which is obtainable by changing a chemical structure of the above-mentioned common saccharide (unmodified sugar) (a) with a radical initiator (b) (if necessary, in an aqueous medium).
• the saccharide (a) can show two structures, i.e., an open chain structure having a hydroxyl group and a carbonyl group (aldehyde or ketone) and a ring structure of a cyclic acetal (or ketal) involving its own hydroxyl group.
• the modified sugar (A) comprises a compound which is obtainable by decomposition and/or boding and polymerization of a carboxyl group and/or a furan structure produced by oxidization of the cyclic acetal structure of the saccharide (a) with a radical initiator (b).
• aqueous adhesive when the modified sugar (A) comprises a carboxyl group and/or a furan structure, curing rate of the adhesive can increase, thus mechanical properties such as tensile strength and tensile elastic modulus of a molded material can be improved.
• the radical initiator (b) refers to a compound which generates a radical under a mild reaction condition in order to allow a radical reaction to proceed.
• the radical refers to atoms, molecules, or ions having an unpaired electron.
• the radical is generally called a free radical.
• the radical initiator is not particularly limited as long as it does not interfere with the object of the present invention, and examples thereof include an azo compound, a peroxide and so on.
• specific examples thereof include 2,2’-azobisbutyronitrile (AIBN).
• AIBN 2,2’-azobisbutyronitrile
• the peroxide is roughly classified into an organic peroxide, an inorganic peroxide, and hydrogen peroxide.
• the organic peroxide includes a peroxide structure (-O-O-) and is typically, for example, benzoyl peroxide.
• the inorganic peroxide includes peroxide ions (O 2 2- ) and specific examples thereof include ammonium persulfate, sodium persulfate, potassium persulfate and the like.
• Hydrogen peroxide is represented by chemical formula H 2 O 2 .
• the radical initiator (b) preferably comprises a peroxide in the present invention.
• the modified sugar (A) can be produced by reacting the saccharide (a) with the radical initiator (b) in the presence of amines (c).
• the amines (c) is a general term including ammonia and an amine.
• the ammonia is an inorganic compound whose molecular formula is represented by NH 3 and is colorless gas at a normal temperature under a normal pressure.
• the amine is a general term of a compound in which hydrogen atoms of the ammonia are substituted with a substituent(s) such as a hydrocarbon group and an aromatic group, and is a primary amine when the number of hydrogen atoms substituted is 1, a secondary amine when the number of hydrogen atoms substituted is 2, or a tertiary amine when the number of hydrogen atoms substituted is 3. Moreover, the substituent is bonded to the tertiary amine to form quaternary ammonium cations.
• the amine is roughly classified into an aliphatic amine, an aromatic amine, and a heterocyclic amine.
• Examples of the aliphatic amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, triethanolamine, hexamethylenediamine and the like.
• Examples of the aromatic amine include aniline, phenethylamine, toluidine, catecholamine and the like.
• heterocyclic amine examples include pyrrolidine, piperazine, piperidine, morpholine, pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, oxazole, thiazole and the like.
• the amines (c) preferably comprise ammonia.
• the amines (c) comprises ammonia, mechanical properties (tensile strength, tensile elastic modulus and the like) of a molded material comprising a cured material of the aqueous adhesive are improved.
• the aqueous adhesive according to the embodiment of the present invention comprises a polyalcohol (B) having a boiling point of 200 to 285°C.
• the boiling point refers to a temperature at which a liquid boils at 1 atm.
• the polyalcohol (B) having a boiling point of 200 to 285°C is not particularly limited as long as it is an alcohol which has two or more hydroxyl groups and has a boiling point of 200 to 285°, and the objective aqueous adhesive of the present invention is obtainable.
• Examples of the polyalcohol (B) having a boiling point of 200 to 285°C can include diethylene glycol, dipropylene glycol, triethylene glycol and tripropylene glycol. These polyalcohols may be used alone, or a plurality of polyalcohols may be used, and it is most desirable to comprise diethylene glycol and/or dipropylene glycol.
• the boiling point of the polyalcohol (B) is 200°C to 285°C, preferably 200 to 280°C, and most preferably 220 to 260°C.
• the aqueous adhesive according to the embodiment of the present invention comprises the polyalcohol (B), curing rate increases while increase in viscosity is inhibited when the adhesive is applied. Since it is possible to inhibit increase in viscosity of the aqueous adhesive when the adhesive is applied, the aqueous adhesive can be applied more uniformly and it is possible to improve physical properties (particularly, shear strength) of a molded material.
• the aqueous adhesive according to the embodiment of the present invention comprises the polyalcohol (B) in an amount of 5.0 to 30.0 parts by weight, particularly preferably 5.0 to 20.0 parts by weight, and most preferably 5.0 to 10.0 parts by weight, based on 100 parts by weight (in terms of solid content) of the total weight of the saccharide and the polyalcohol (B).
• the content of the polyalcohol (B) is 5.0 parts by weight or more, it is possible to further inhibit increase in viscosity of the aqueous adhesive and to further improve physical properties (particularly, shear strength) of the molded material.
• the content of the polyalcohol (B) is 30.0 parts by weight or less, it is possible to further maintain the curing rate of the aqueous adhesive and to maintain most of physical properties of the molded material.
• An aqueous adhesive according to an embodiment of the present invention preferably comprises an inorganic acid salt (C).
• the curing rate of the aqueous adhesive according to the embodiment of the present invention is increased when the adhesive comprises the inorganic acid salt (C), thus mechanical properties such as tensile strength and tensile elastic modulus of a molded material can be improved.
• the inorganic acid salt (C) is not particularly limited as long as it does not interfere with the object of the present invention, and it is preferable to comprise at least one selected from ammonium salts, potassium salts, calcium salts, sodium salts and magnesium salts, and it is particularly preferable to comprise an inorganic acid ammonium salt.
• the aqueous adhesive according to the embodiment of the present invention is more excellent in curing rate when the adhesive comprises the inorganic acid ammonium salt, thus mechanical properties such as tensile strength and tensile elastic modulus of the molded material can be improved.
• the inorganic acid ammonium salt is generally called an ammonium salt of an inorganic acid and is not particularly limited as long as the objective aqueous adhesive of the present invention is obtainable.
• the “inorganic acid ammonium salt” can include ammonium sulfate, ammonium hydrogen sulfate, ammonium halide salt (for example, ammonium chloride, ammonium fluoride, ammonium bromide and ammonium iodide), ammonium phosphate, ammonium hydrogen phosphate, and ammonium dihydrogen phosphate.
• the “inorganic acid ammonium salt” is preferably at least one selected from ammonium sulfate, ammonium chloride, ammonium hydrogen phosphate, and ammonium dihydrogen phosphate.
• the “inorganic acid ammonium salt (C)” is at least one selected from ammonium sulfate, ammonium chloride, ammonium hydrogen phosphate, and ammonium dihydrogen phosphate
• the aqueous adhesive according to the embodiment of the present invention has more excellent curability, and can further improve physical properties (mechanical properties such as tensile strength and tensile elastic modulus) of the molded material.
• the inorganic acid ammonium salt can be used alone or in combination. It is possible to use commercially available products as the “inorganic acid ammonium salt”.
• the inorganic acid salt (C) can comprise, in addition to the “inorganic acid ammonium salt”, an inorganic acid metal salt, and can comprise at least one selected from potassium salts, calcium salts, sodium salts, and magnesium salts.
• Examples of the “inorganic acid metal salt” include: potassium salts such as potassium sulfate, potassium hydrogen sulfate, potassium halide (for example, potassium fluoride, potassium chloride, potassium bromide, and potassium iodide), potassium phosphate, potassium hydrogen phosphate, and potassium dihydrogen phosphate; calcium salts such as calcium sulfate, potassium hydrogen sulfate, calcium halide (for example, calcium fluoride, calcium chloride, calcium bromide, and calcium iodide), calcium phosphate, calcium hydrogen phosphate, and calcium dihydrogen phosphate; sodium salts such as sodium sulfate, sodium hydrogen sulfate, sodium halide (for example, sodium fluoride, sodium chloride, sodium bromide, and sodium iodide), sodium phosphate, sodium hydrogen phosphate, and sodium dihydrogen phosphate; and magnesium salts such as magnesium sulfate, magnesium hydrogen sulfate, magnesium halide (for example, magnesium flu
• the “inorganic acid metal salt” particularly preferably comprises at least one selected from potassium sulfate, potassium chloride, calcium sulfate, calcium chloride, sodium sulfate, sodium chloride, magnesium sulfate, and magnesium chloride.
• the molded material produced by using the aqueous adhesive according to the embodiment of the present invention can have more improved tensile strength and tensile elastic modulus by curing with heating and pressurizing at a lower temperature for a shorter time.
• the “inorganic acid metal salt” most preferably comprises magnesium chloride.
• the molded material according to the embodiment of the present invention can have much more improved tensile strength and tensile elastic modulus by curing with heating and pressurizing at a lower temperature for a shorter time when the adhesive comprises magnesium chloride.
• an amount of the inorganic acid salt (C) is preferably 1.5 to 15.0 parts by weight, particularly preferably 1.5 to 10.0 parts by weight, and particularly preferably 3.0 to 10.0 parts by weight, based on 100 parts by weight (in terms of solid content) of the total weight of the saccharide and the polyalcohol (B).
• the aqueous adhesive according to the embodiment of the present invention is excellent in balance between inhibition of increase in viscosity and curing rate, and is also excellent in water resistance.
• the molded material according to the embodiment of the present invention has improved shear strength, tensile strength and tensile elastic modulus, and also improved water resistance, so that the molded material hardly absorb moisture in air.
• the aqueous adhesive according to the embodiment of the present invention is in a form (a form of a solution, a suspension, or a dispersion) in which the above-mentioned saccharide and polyalcohol (B), if necessary, the inorganic acid salt (C), and other components are dissolved or dispersed in water, and the aqueous adhesive is applied on various materials (for example, inorganic fibers, woody material), a base material, an adherend and the like, followed by molding (shaping or forming) and curing.
• water as used herein is generally called “water” and is not particularly limited as long as the objective aqueous adhesive of the present invention is obtainable. Examples thereof can include distilled water, deionized water, pure water, tap water, and industrial water.
• An amount of the water contained in the aqueous adhesive according to the embodiment of the present invention is not particularly limited and is appropriately selected according to the saccharide, the components (B), (C) and optional components to be used and additives as long as the objective aqueous bonding composition of the present invention is obtainable.
• the aqueous adhesive according to the embodiment of the present invention is in a form of an aqueous solution, a suspension, or an aqueous dispersion, so that it is easy to apply or spray on various materials (for example, inorganic fibers, woody material), a base material, an adherend and the like. Furthermore, the aqueous adhesive according to the embodiment of the present invention is excellent in protection of the earth environment, and protection of the work environment of workers since an organic solvent is not preferably used.
• the aqueous adhesive according to the embodiment of the present invention can comprise other components.
• the components can include a storage stabilizer, a mechanical property modifier, a thickener, a preservative, a mildew-proofing agent, a rust preventive, and a dispersion stabilizer.
• Examples of the storage stabilizer can include polycarboxylic acids such as citric acid, malic acid, tartaric acid, succinic acid, and erythorbic acid.
• Examples of the mechanical property modifier include vinyl-based polymerizable monomers having reactivity in the side chain, such as (meth)acrylic acid, maleic acid, (meth)acrylic acid amide ((meth)acrylamide), acrylonitrile, hydroxyethyl (meth)acrylate, furfuryl alcohol, and glycidyl (meth)acrylate.
• the thickener is used so as to prevent viscosity of the adhesive from decreasing in case of pressurizing and heating the adhesive, and is not particularly limited as long as the objective aqueous adhesive of the present invention is obtainable.
• the thickener is classified, for example, into an organic thickener and an inorganic thickener.
• examples of the inorganic thickener can include clay, talc, silica and so on.
• organic thickener can include natural type thickeners such as vegetable flours such as wheat flour, cornstarch, top-grade rice flour, walnut flour and coconut flour, carboxymethyl cellulose, and synthetic type thickeners such as polyvinyl alcohol and polyvinylpyrrolidone. These thickeners can be used alone or in combination.
• natural type thickeners such as vegetable flours such as wheat flour, cornstarch, top-grade rice flour, walnut flour and coconut flour, carboxymethyl cellulose
• synthetic type thickeners such as polyvinyl alcohol and polyvinylpyrrolidone. These thickeners can be used alone or in combination.
• An aqueous adhesive according to an embodiment of the present invention can be produced by mixing an above-mentioned saccharide, a component (B), water, if necessary, a component (C) and optional other components, followed by stirring.
• the order of mixing the saccharide, the component (B), the component (C), the water, and the other components, the mixing method, and the stirring method are not particularly limited as long as the objective aqueous adhesive of the present invention is obtainable.
• the present invention provides a method for producing an aqueous adhesive, which method comprises mixing a saccharide, a component (B), and water.
• the method for producing an aqueous adhesive comprises: a step (i) of reacting a saccharide (unmodified) (a) and a radical initiator (b) to produce a modified sugar (A).
• the method for producing an aqueous adhesive comprises, in place of the above-mentioned step (i), a step (ii) of reacting a saccharide (unmodified) (a) and a radical initiator (b) in the presence of amines (c) to produce a modified sugar (A).
• the present invention provides a method for producing an aqueous adhesive, which comprises: a step (i), and mixing a modified sugar (A), a component (B), and water.
• the present invention provides a method for producing an aqueous adhesive, which comprises: a step (i), and a step (iii) of mixing the modified sugar (A), a component (B), a component (C), and water.
• the method for producing the aqueous adhesive according to the embodiment of the present invention comprises the step (iii), increase in viscosity of the aqueous adhesive is inhibited and also curing rate of the adhesive increases, thus shear strength, tensile strength, and tensile elastic modulus of a molded material can be improved.
• Examples of the material obtainable by using the aqueous adhesive according to the embodiment of the present invention include molded materials (molded articles or molded bodies) in which materials such as inorganic fibers, calcium silicate, plaster, rock wool, concrete, cement, mortar, and slate are obtainable in various forms (plate, block, etc.).
• the inorganic fibers include, but are not limited to, rock wool, stone wool, mineral wool, glass wool, mineral glass wool and the like.
• an inorganic fiber molded material is preferably produced by using any one of these inorganic fibers alone, or using two or more inorganic fibers in combination. It is preferable to use, as the inorganic fibers, glass wool or rock wool from the viewpoint of versatility, insulating properties, soundproofing properties and the like.
• the present invention it is possible to provide, in addition to the inorganic fiber molded material, molded materials such as woody materials and molds by molding woods (wood chips, wood fibers, etc.), molding sand (or casting sand) and the like using the aqueous adhesive according to the embodiment of the present invention.
• the woody material according to the present invention may be a mixture comprising an aqueous adhesive according to an embodiment of the present invention and a woody element (raw material) (for example, fibers of woody or herbaceous plants, small pieces and veneers, etc.).
• aqueous adhesive is applied or sprayed on a woody element, the woody element is heated, bonded (attached or adhered), molded (formed or shaped) to produce the woody material.
• woody element examples include such as sawn boards, veneers, woody strands, woody chips, woody fibers and vegetable fibers and the like obtainable, for example, by grinding woods.
• woody material examples include laminated woods, plywoods, particle boards, fiber boards, medium density fiberboard (MDF) and the like obtainable, for example, by bonding the woody element using an adhesive.
• MDF medium density fiberboard
• the aqueous adhesive according to the embodiment of the present invention can be used to bond various adherends (for example, inorganic fibers, papers, woody fibers, plywoods, and the like).
• adherends for example, inorganic fibers, papers, woody fibers, plywoods, and the like.
• the coating method of the aqueous adhesive is preferably a method of impregnating inorganic fibers with the aqueous adhesive, a method of spraying the aqueous adhesive on inorganic fibers or woody element using a sprayer, or a method of applying the aqueous adhesive using a roll and so on.
• the molding pressure is preferably 0.5 to 6.0 MPa. If the molding pressure is 6.0 MPa or less, the molded material is scarcely degraded since too large pressure is not applied. If the molding pressure is 0.5 MPa or more, it is possible to satisfactorily bond the element of the molded material.
• the molding temperature is preferably 140 to 230°C, more preferably 140 to 200°C, and particularly preferably 140 to 180°C. If the molding temperature is 230°C or lower, low energy consumption is achieved because of non-excessive temperature, and also the molded material is scarcely degraded. If the molding temperature is 140°C or higher, the bonding can proceed within an appropriate time.
• the molding time is preferably 3 to 10 minutes, more preferably 3 to 9 minutes, and particularly preferably 3 to 7 minutes. If the molding time is 10 minutes or less, low energy consumption is achieved because of non-excessive time, and also the molded material is scarcely degraded. If the molding time is 3 minutes or more, an appropriate bonding time is secured, thus making it possible to secure appropriate bonding.
• the molded material thus obtained in the above-mentioned manner can be used for various applications, for example, building materials, furniture, etc., like a conventional molded material.
• B Polyalcohol having a boiling point of 200 to 285°C
• B-1 Diethylene glycol (Boiling point: 245°C) (manufactured by Wako Pure Chemical Industries, Ltd.)
• B-2) Dipropylene glycol (Boiling point: 232°C) (manufactured by Wako Pure Chemical Industries, Ltd.)
• B-3 Triethylene glycol (Boiling point: 285°C) (manufactured by Wako Pure Chemical Industries, Ltd.)
• B-4 Tripropylene glycol (Boiling point: 270°C) (manufactured by Wako Pure Chemical Industries, Ltd.)
• B’-5 Glycerol (Boiling point: 290°C) (manufactured by Wako Pure Chemical Industries, Ltd.)
• B’-7 Ethylene glycol (Boiling point: 198°C) (manufactured by Wako Pure Chemical Industries, Ltd.)
• C Inorganic acid ammonium salt (C-1) Ammonium sulfate (Wako Pure Chemical Industries, Ltd.)) (C-2) Diammonium hydrogen phosphate (Wako Pure Chemical Industries, Ltd.)) (C-3) Ammonium dihydrogen phosphate (Wako Pure Chemical Industries, Ltd.))
• the radical initiator solution was added dropwise to the sucrose solution from the dropping funnel over 4 hours. After completion of the dropwise addition, the solution thus prepared in the reaction vessel was aged with stirring at 90°C or higher for additional 1 hour and then cooled to 40°C or lower to obtain a modified sugar-containing solution.
• the solution of the modified sugar included the radical initiator and a solid component concentration thereof was 68.0% by weight. The solid component concentration is calculated from the total amount of the modified sugar (A-1) and ammonium persulfate (b-1) dissolved in the aqueous solution.
• Example 1 Glucose (a-2), diethylene glycol (B-1) and ammonium sulfate (C-1) were added to distilled water in each proportion shown in Table 2 and dissolved with stirring at a normal temperature, and then the pH was adjusted to 6.0 to 9.0 with ammonia water to obtain an aqueous adhesive of Example 1.
• Each proportion of the components (a-2), (B-1), and (C-1) and distilled water is as shown in Table 2.
• Each proportion shown in Table 2 is part by weight, and the number of parts by weight of the component (a-2) is a value in terms of solid content.
• Examples 2 to 19 and Comparative Examples 1 to 9 Production of Aqueous Adhesives
• Each composition of aqueous adhesives of Examples 2 to 19 and Comparative Examples 1 to 9 is shown in Tables 2 to 4.
• a saccharide, components (B) and (C), and water were used in amounts shown in Tables 2 to 4 according to the composition and the formulation shown in Tables 2 to 4, each of aqueous adhesives of Examples 2 to 19 and Comparative Examples 1 to 19 was produced.
• ⁇ Curing Rate Measurement of Gelling Time>
• the gelling time at 160°C and the gelling time at 180°C were measured. Evaluation criteria are shown below. On a hot plate heated to 160°C and 180°C, 0.2 ml of a sample solution was dropped, and the measurement was performed while stirring the sample solution with a spoon. With respect to evaluation criteria of the gelling time, the time when stringing of a resin does not occur due to curing was recorded as the gelling time.
• Evaluation criteria of adhesion are as shown below. Evaluation criteria of adhesion (time until viscosity of an aqueous adhesive increases (second)) A: 40 seconds B: 30 seconds C: 20 seconds D: 10 seconds
• ⁇ Water Resistance: Dissolution Rate Test> On about 0.05 g of a glass fiber filter (manufactured by Whatman, product name of GF/A) cut into a 30 mm ⁇ 30 mm square, 0.5 ml of a sample solution was uniformly applied. The sample solution applied on the glass fiber filter was dried at 105°C for 30 minutes and then left to stand in an oven at 190°C for 15 minutes to obtain a test piece. The test piece was immersed in 50 ml of water at a normal temperature for 24 hours and then dried at 130°C for 1 hour. An amount of the adhesive dissolved in the water from the test piece was determined and a dissolution rate to water was determined by the following formula, and then the water resistance was evaluated.
• Evaluation criteria of water resistance based on dissolution rate are shown below. Evaluation criteria of dissolution rate A: less than 2.0% B: 2.0% or more and less than 4.5% C: 4.5% or more and less than 6.0% D: 6.0% or more
• Model 5585 manufactured by Instron as a tensile tester, the tensile strength and the tensile elastic modulus were measured at a tensile speed of 25.4 mm/min. The tensile strength was recorded as the braking strength (maximum strength) value.
• Evaluation criteria of tensile strength (23°C, humidity of 50%) are as shown below. Evaluation criteria of tensile strength A: Strength is 15 MPa or more B: Strength is 14 MPa or more and less than 15 MPa C: Strength is 12 MPa or more and less than 14 MPa D: Strength is less than 12 MPa
• the tensile elastic modulus was determined from a gradient of a strain amount of 0.1%, excluding waviness of a test piece. Evaluation criteria of tensile elastic modulus (23°C, humidity of 50%) are as shown below. Evaluation criteria of tensile elastic modulus A: Elastic modulus is 1,100 MPa or more B: Elastic modulus is 1,000 MPa or more and less than 1,100 MPa C: Elastic modulus is 900 MPa or more and less than 1,000 MPa D: Elastic modulus is less than 900 MPa
• a shear strength test was carried out in accordance with JIS K 6850. On the hot plate heated to 160°C used in the measurement of the gelling time, 0.2 ml of a sample solution was dropped. After 20 seconds, the sample solution was scooped up with a spoon and then applied on a glass plate (thickness: width: 25 mm, length: 100 mm). After 1 minute, this glass plate were laid on another glass plate through the sample solution interposed therebetween. The laminated glass plate was heated in an electric furnace at 190°C for 15 minutes heating to cure the sample solution, and then glass plates were laminated together to obtain a test piece.
• Evaluation criteria of shear strength are as shown below. Evaluation criteria of shear strength A: Strength is 0.6 MPa or more B: Strength is 0.5 MPa or more and less than 0.6 MPa C: Strength is 0.4 MPa or more and less than 0.5 MPa D: Strength is less than 0.4 MPa
• the aqueous adhesives of Examples 1 to 19 comprise a polyalcohol (B) having a boiling point of 200°C or more, and comprise the component (B) in an amount of 5.0 to 30.0 parts by weight (in terms of solid content) based on 100 parts by weight (in terms of solid content) of the total weight of the saccharide and the component (B), so that the aqueous adhesives exhibit high curing rates and inhibit increase in viscosity and are excellent in adhesion to an adherend. It was demonstrated that the respective physical properties (dissolution rate (water resistance), tensile strength, tensile elastic modulus, shear strength) of the molded materials of Examples 1 to 19 are improved.
• the aqueous adhesives of Examples 7 to 19 comprise a modified sugar (A) as the saccharide and therefore exhibit higher curing rates. Furthermore, the molded materials of Examples 7 to 19 are satisfactory in all of the water resistance, the tensile strength, and the tensile elastic modulus.
• the aqueous adhesives of Comparative Examples 1 to 9 exhibit very low curing rates and inferior adhesion to an adherend because of insufficient inhibition of increase in viscosity, compared to those of Examples.
• the molded materials of Comparative Examples 1 to 9 exhibit very poor shear strength and are inferior in balance among the tensile strength, the tensile elastic modulus, and the water resistance (dissolution rate), compared to those of Examples.
• the present invention provides an aqueous adhesive.
• the aqueous adhesive according to an embodiment of the present invention can be used in case of molding inorganic fibers such as glass fibers, and woody elements.

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• 2018
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