JP4759375B2 - Aqueous binder for inorganic fiber and heat insulating sound absorbing material for inorganic fiber - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an aqueous binder for inorganic fibers that does not contain formaldehyde and an inorganic fiber heat insulating sound absorbing material using the same, which can be suitably used for heat insulating sound absorbing materials made of inorganic fibers such as glass wool or rock wool.

  Conventionally, in heat-absorbing sound-absorbing materials made of inorganic fibers such as glass wool or rock wool, phenolic resin-based binders mainly composed of phenol / formaldehyde resin (or resol type phenolic resin) are widely used as binders for bonding fibers together. in use. These phenolic resin-based binders are heat-cured in a relatively short time and a strong cured product is obtained, so that the inorganic fiber heat-absorbing sound-absorbing material using this is shape-retaining, thickness-restorability after opening the compressed package, Excellent bending resistance.

  However, when a phenolic resin binder is used, formaldehyde is released during the manufacturing process, particularly when the binder is cured. Therefore, the treatment and response of the released formaldehyde has become a problem. Particularly in recent years, due to the reduction of environmental load, the regulation of formaldehyde emission has been demanded by laws and regulations, etc., and binders for inorganic fiber heat-absorbing sound-absorbing materials with low environmental load are desired, and many proposals have been made. ing.

  For example, Patent Document 1 listed below includes (a) a polyacid containing at least two carboxylic acid groups, acid anhydride groups, or salts thereof, (b) a polyol containing at least two hydroxyl groups, and (C) containing a phosphorus-containing accelerator, and the equivalent ratio of the carboxylic acid group, acid anhydride group, or salt thereof: the hydroxyl group is about 1 / 0.01 to about 1 A curable aqueous composition is disclosed wherein the carboxylic acid group, acid anhydride group, or salt thereof is neutralized with a non-volatile base to the extent of about 35% or less.

  Patent Document 2 listed below is a water-soluble composition containing a polycarboxylic acid polymer having a number average molecular weight of less than 5,000 and a polyol, and has a pH adjusted to less than 3.5. A binder is disclosed.

  In Patent Document 3 below, A) 5 to 100% by mass is obtained by radical polymerization comprising an ethylenically unsaturated acid anhydride or an ethylenically unsaturated dicarboxylic acid capable of forming an anhydride group. B) a formaldehyde-free aqueous binder containing alkanolamines having at least two hydroxyl groups.

Furthermore, many binders for inorganic fibers based on the above polycarboxylic acid have been proposed.
JP-A-6-184285 US Pat. No. 6,331,350 Special Table 2000-508000

  The above-mentioned polycarboxylic acid resin binder such as an acrylic resin has a low reactivity between the carboxyl group in the polycarboxylic acid resin and the hydroxyl group in the polyol under a weakly acidic to weakly basic region, and thus the esterification reaction is slow. It is hard to progress sufficiently. Therefore, the crosslinking reaction of the binder is difficult to complete, and when the binder is adjusted to be weakly acidic to weakly basic, various physical properties of the inorganic fiber heat-absorbing sound-absorbing material, for example, reduction in resilience due to binder deterioration under high humidity, Flexibility is easy to deteriorate. For this reason, acrylic resin binders are not suitable for use under weakly acidic to weakly basic conditions. Usually, the binder pH is adjusted to a strongly acidic region of about 3 to accelerate the crosslinking reaction. Let me use it. However, in such a case, there is a problem that corrosion is likely to occur in manufacturing equipment such as an acid binder supply pipe, a spray device, and a mesh conveyor for depositing inorganic fibers, and there is a problem that the maintenance cost and the device cost of the device are increased. In addition, a strongly acidic waste liquid is discharged, and there is a problem in that a waste liquid treatment cost is required.

  In addition, the crosslinking of the acrylic resin binder is formed by an ester bond, but in the case of inorganic fibers, particularly glass fibers, the alkali metal components in the glass are eluted as alkali ions due to moisture in the air. Also, there is a problem that the ester bond of the binder cross-linking portion is hydrolyzed, and the binding force between the fibers of the binder is impaired.

  Therefore, the object of the present invention is to contain no formaldehyde, have excellent strength, suitable for use under weakly acidic to weakly basic conditions, and the obtained cured binder is excellent even in use over time. An object of the present invention is to provide a water-based binder for inorganic fibers having strength, and an inorganic fiber heat insulating sound absorbing material using the same.

  In achieving the above object, the aqueous binder for inorganic fibers of the present invention comprises an acrylic resin having an acid value of 350 to 850 mgKOH / g, a crosslinking agent containing at least one dialkanolamine, a curing accelerator, The total number of moles of hydroxyl groups and imino groups in the crosslinking agent is 0.8 to 1.5 in terms of mole ratio relative to the number of moles of carboxyl groups in the acrylic resin. The pH is adjusted to 6.0 to 8.0 with a volatile basic compound.

  The aqueous binder for inorganic fibers of the present invention is made of an acrylic resin and is a formaldehyde-free binder, so that it can be cured without releasing formaldehyde at the time of heat curing, reducing the environmental load in exhaust gas and the like. be able to. And, by combining an acrylic resin having an acid value of 350 to 850 mg KOH / g and dialkanolamine, the heat curing can be carried out relatively quickly even under weakly acidic to weakly basic conditions of pH 6.0 to 8.0. Further, the crosslinking reaction by imidization and esterification reaction can be sufficiently improved, so that the crosslinking can be made dense. Furthermore, by containing an ammonia salt of an inorganic acid, ammonium ions are volatilized as ammonia by heating in the binder curing step and remain in the binder as an acid, so that the alkali component eluted from the inorganic fibers can be removed. In addition, hydrolysis of the crosslinked part in the binder can be suppressed, and various physical properties of the inorganic fiber heat-absorbing sound absorbing material can be maintained for a long period of time. Furthermore, with respect to the number of moles of the carboxyl group in the acrylic resin, the total number of moles of the hydroxyl group and the imino group in the cross-linking agent is adjusted to 0.8 to 1.5 in terms of a mole ratio. The resin and the crosslinking agent can be reacted without excess or deficiency, a strong binder cured product is obtained, and various physical properties of the inorganic fiber heat insulating sound absorbing material are not impaired. And since it is suitable for use under weakly acidic to weakly basic conditions, there is no corrosion of production equipment due to acid as seen in the above prior art, reducing maintenance costs, equipment costs, wastewater treatment costs, etc. it can.

  In the aqueous binder for inorganic fibers of the present invention, the acrylic resin has an acrylic resin (A) having a weight average molecular weight of 1,000 to 15,000 or a weight average molecular weight of 1,000 to 4,000. And a mixture of the acrylic resin (B) having a weight average molecular weight of 8000 to 20,000.

  If the weight average molecular weight of the acrylic resin is 1,000 to 15,000, the increase in the viscosity of the binder can be suppressed, and the fluidity of the binder before spraying or before the start of the curing reaction can be improved. It becomes dense and the strength of the obtained binder cured product is improved, and the binding (adhesive force) between fibers becomes strong.

  The acrylic resin is a mixture of an acrylic resin (A) having a weight average molecular weight of 1,000 to 4,000 and an acrylic resin (B) having a weight average molecular weight of 8000 to 20,000. If there is, it becomes easy to control the fluidity of the binder, so that the fluidity of the binder on the surface of the inorganic fiber described above and the surface of the inorganic fiber at the time of collecting in the manufacturing process of the inorganic fiber heat-absorbing sound absorbing material. This makes it easy to optimize the binder removal and to suppress the bias of binder adhesion due to fluidization, and to improve the homogeneity in the physical properties of the inorganic fiber heat-absorbing sound-absorbing material.

  In the aqueous binder for inorganic fibers of the present invention, the ammonium salt of the inorganic acid is preferably ammonium sulfate. Ammonium sulfate does not delay the crosslinking reaction when the binder is cured, and the neutralization of the alkali component eluted from the inorganic fibers proceeds promptly, thereby suppressing hydrolysis of the cured binder by alkali.

  Further, in the aqueous binder for inorganic fibers of the present invention, one aqueous dispersion selected from waxes or a mixture of waxes and heavy oils is used in a total of 100 masses of the acrylic resin and the crosslinking agent. It is preferable to contain 0.1-5 mass parts in conversion of solid content with respect to a part. The above-mentioned waxes, or a mixture of waxes and heavy oils, acts as a release agent, dustproof agent, or water repellent agent that suppresses adhesion to production equipment during the production of an inorganic fiber heat-absorbing sound absorbing material. In particular, acrylic resin binders have better adhesion to metals compared to phenolic resin binders, so that they tend to adhere to metal conveyors and the like during curing of the binder, impairing productivity. In some cases, by using the above waxes, or a mixture of waxes and heavy oils, it is possible to impart releasability to the binder and prevent the above problems.

  Moreover, in the aqueous | water-based binder for inorganic fibers of this invention, it is preferable to contain 0.1-2.0 mass parts of silane coupling agents with respect to a total of 100 mass parts of the said acrylic resin and the said crosslinking agent. . According to this, the silane coupling agent can improve the adhesiveness in the interface of an inorganic fiber and a binder, and can improve each physical property of the inorganic fiber heat insulating sound-absorbing material obtained.

  On the other hand, an inorganic fiber heat-absorbing sound-absorbing material of the present invention is characterized in that the inorganic fiber-based aqueous binder of the present invention is applied to inorganic fibers and heat-cured and molded. According to this, since the formaldehyde which does not have an unfavorable influence on the environment is not released at the time of production, an inorganic fiber heat insulating sound absorbing material which has little environmental load and does not impair the conventional physical properties can be obtained.

  The aqueous binder for inorganic fibers of the present invention is made of an acrylic resin and is a formaldehyde-free binder, so that it can be cured without releasing formaldehyde at the time of heat curing, reducing the environmental load in exhaust gas and the like. be able to. And, by combining an acrylic resin having an acid value of 350 to 850 mg KOH / g and dialkanolamine, the heat curing can be carried out relatively quickly even under weakly acidic to weakly basic conditions of pH 6.0 to 8.0. Further, the crosslinking reaction by imidization and esterification reaction can be sufficiently improved, so that the crosslinking can be made dense. Furthermore, when ammonium salt of inorganic acid is heated in the binder curing step, ammonium ions are volatilized out as ammonia and remain in the binder as acid. Hydrolysis of the cross-linked portion inside can be suppressed, and various physical properties of the inorganic fiber heat-absorbing sound-absorbing material can be maintained for a long time. Furthermore, with respect to the number of moles of the carboxyl group in the acrylic resin, the total number of moles of the hydroxyl group and the imino group in the cross-linking agent is adjusted to 0.8 to 1.5 in terms of a mole ratio. The resin and the crosslinking agent can be reacted without excess or deficiency, a strong binder cured product is obtained, and various physical properties of the inorganic fiber heat insulating sound absorbing material are not impaired. And since it is suitable for use under weakly acidic to weakly basic conditions, there is no corrosion of production equipment due to acid as seen in the above prior art, reducing maintenance costs, equipment costs, wastewater treatment costs, etc. it can.

  And the inorganic fiber heat insulation sound-absorbing material obtained by using the aqueous binder for inorganic fiber of the present invention is the thickness dimension of the heat insulation material related to the heat insulation sound-absorbing performance depending on the environmental conditions, for example, temperature or humidity, and the self-supporting property at the time of construction. It has the same physical properties as those using conventional phenolic binders, and is suitable as a core material for heat insulation, sound absorbing materials, or vacuum heat insulating materials for houses, buildings, etc. Can be used for

  The aqueous binder for inorganic fibers of the present invention comprises an acrylic resin having an acid value of 350 to 850 mg KOH / g, a crosslinking agent containing at least one dialkanolamine, a curing accelerator, and an ammonium salt of an inorganic acid. It is a water-soluble composition containing.

  The acrylic resin used in the aqueous binder for inorganic fibers of the present invention is obtained by polymerizing one or more monomers selected from ethylenically unsaturated carboxylic acid monomers.

  Examples of the ethylenically unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, 2-methylmaleic acid, itaconic acid, 2-methylitaconic acid, α-β-methyleneglutaric acid. , Monoalkyl maleate, monoalkyl fumarate, maleic anhydride, acrylic anhydride, β- (meth) acryloyloxyethylene hydrodiene phthalate, β- (meth) acryloyloxyethylene hydromaleate, β- (meth) acryloyl Examples thereof include oxyethylene hydrogen succinate. Considering the ease of control of the molecular weight of the acrylic resin, it is preferable to use acrylic acid. Moreover, when adjusting the acid value of acrylic resin to the high area | region of 700 mgKOH / g or more, it is preferable to use maleic acid or fumaric acid.

  Moreover, when adjusting the acid value of acrylic resin, the ethylenically unsaturated monomer which does not contain a carboxyl group can also be used together with the said ethylenically unsaturated carboxylic acid.

  Examples of the ethylenically unsaturated monomer containing no carboxyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cetyl (meth) acrylate, n-stearyl (meth) acrylate, diethylene glycol ethoxy (meth) acrylate, methyl-3-methoxy (meth) acrylate, ethyl-3-methoxy (meth) acrylate, butyl -3-Methoxy (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, tetrahydrofurfuryl acrylate, 2-hydroxyethyl acrylate, 2- Droxypropyl acrylate, 4-hydroxybutyl acrylate, mono (meth) acrylate of trivalent or higher polyol, aminoalkyl (meth) acrylate, N-alkylaminoalkyl (meth) acrylate, N, N-dialkylaminoalkyl (meth) Acrylic monomers such as acrylates; Vinyl-based compounds such as vinyl alkyl ethers, N-alkyl vinyl amines, N, N-dialkyl vinyl amines, N-vinyl pyridines, N-vinyl imidazoles, N- (alkyl) aminoalkyl vinyl amines Monomer; (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, N, N-dialkylaminoalkyl (meth) acrylamide, diacetone (meth) acrylamide, N-vinylform Amide monomers such as amide, N-vinylacetamide and N-vinylpyrrolidone; Aliphatic unsaturated hydrocarbons such as ethylene, propylene, isobutylene, isoprene and butadiene; styrene, α-methylstyrene, p-methoxystyrene, vinyl Styrene monomers such as toluene, p-hydroxystyrene, p-acetoxystyrene; vinyl ester monomers such as vinyl acetate and vinyl propionate; acrylonitrile, glycidyl (meth) acrylate and the like. These can use together 1 type (s) or 2 or more types. However, when N-methylol (meth) acrylamide and methyl-N-methylol (meth) acrylamide are heated, they cause a crosslinking reaction and release formaldehyde, so that they are not used in the acrylic resin of the present invention.

  The acid value of the acrylic resin needs to be 350 to 850 mgKOH / g, preferably 450 to 750 mgKOH / g, and more preferably 550 to 750 mgKOH / g. When the acid value of the acrylic resin is less than 350 mgKOH / g, the crosslinked structure of the cured product obtained by heat-curing the aqueous binder becomes rough, and the strength and rigidity of the binder cured product tend to decrease. The thickness of the inorganic fiber insulation sound-absorbing sound-absorbing material after being opened in a compressed package (hereinafter referred to as “restoration”) and the rigidity of the board are reduced, and the insulation, sound-absorbing property, or self-supporting property, ie during construction Workability may be impaired. In addition, when the acid value of the acrylic resin exceeds 850 mgKOH / g, the crosslinked structure after curing the binder tends to become too dense and brittle, and when used as a binder for an inorganic fiber heat-insulating sound absorbing material, the desired performance is obtained. In the case where the unreacted carboxyl group remains in the cured product even after curing, the resulting inorganic fiber heat-absorbing sound-absorbing material absorbs moisture under high humidity, for example, and the binding force between the fiber and the fiber by the binder There may be a problem such as lowering of the image quality. The acid value of the acrylic resin in the present invention is expressed in milligrams of potassium hydroxide required to neutralize 1 g of the acrylic resin.

  In the present invention, the acrylic resin has 1) a weight average molecular weight of 1,000 to 15,000, or 2) a weight average molecular weight of the acrylic resin (A) having a weight average molecular weight of 1,000 to 4,000. A mixture with an acrylic resin (B) having a molecular weight of 8,000 to 20,000 is preferred.

  In the case of 1) above, that is, when the weight average molecular weight is 1,000 to 15,000, the weight average molecular weight of the acrylic resin is more preferably 2,000 to 10,000, and 2,000 to 4, 000 is particularly preferred. When the weight-average molecular weight of the acrylic resin exceeds 15,000, the viscosity of the binder after the evaporation of water from the binder application is remarkably increased, and the flowability after application to the inorganic fiber or after application is likely to be inferior. On the other hand, it tends to be difficult to uniformly apply the binder. Further, the adhesiveness of the binder attached to the inorganic fibers tends to increase. If the adhesiveness of the binder attached to the inorganic fiber is high, the fiber to which the binder is attached becomes easy to adhere to the production equipment, and dirt on the production line and the fibers on the surface of the inorganic fiber heat-absorbing sound agglomerate become a lump. There are cases where problems such as partial adhesion of the appearance and thickness of the resulting product may occur. On the other hand, when the weight average molecular weight of the acrylic resin is less than 1,000, the binder component is easily volatilized as fume by heating at the time of curing, and the amount of binder attached to the inorganic fibers is likely to be reduced. Therefore, when it is an inorganic fiber heat-absorbing sound-absorbing material, various physical properties are reduced, or it is necessary to suppress the degree of polymerization at the time of polymerization of the acrylic resin, so that the ethylenically unsaturated monomer tends to remain, Odor may be generated and a new environmental load may be generated. If the weight average molecular weight of the acrylic resin is within the above range, the viscosity of the aqueous binder for inorganic fibers can be easily adjusted, and the flowability after application to the inorganic fibers or after application can be improved. Variation in the amount of binder adhering to can be suppressed. In the production of an inorganic fiber heat-absorbing sound-absorbing material, the step of applying the binder to the fiber is often performed in a high-temperature atmosphere of about 200 to 350 ° C. immediately after being fiberized by a centrifugal method or the like. Evaporation of moisture can be improved.

  In addition, the weight average molecular weight of the acrylic resin is related not only to the fluidity of the binder but also to the crosslink density after curing. Even if the acrylic resin has the same acid value, if the molecular weight is different, the strength of the cured binder Fluctuates, and the physical properties of the resulting inorganic fiber heat-absorbing sound-absorbing material also change. For example, as the weight average molecular weight of the acrylic resin decreases, the cured binder tends to become brittle, and the desired physical properties may not be obtained. However, if the weight average molecular weight of the acrylic resin is within the above range, It is possible to optimize the fluidity of the binder and various physical properties of the obtained inorganic fiber heat-absorbing sound-absorbing material.

  When the acrylic resin is the above 2), that is, the acrylic resin has an acrylic resin (A) having a weight average molecular weight of 1,000 to 4,000, and a weight average molecular weight of 8,000 to 20. , 000, the ratio of the acrylic resin (A) to the acrylic resin (B) is a mass ratio, and the acrylic resin (A): acrylic. It is preferable that it is system resin (B) = 60: 40-90: 10, and it is more preferable that it is acrylic resin (A): acrylic resin (B) = 75: 25-90: 10.

  By restricting the molecular weight of the acrylic resin, the fluidity of the binder is improved. However, the binder on the surface of the inorganic fiber can be improved by using a suction device for depositing the fiber in the fiber collection process after fiberization and binder application of the inorganic fiber. The binder just before curing flows due to the phenomenon that the binder adhesion amount is biased to the lower surface side of the inorganic fiber heat-absorbing sound absorbing material due to the ease of flow or the influence of hot air in the curing oven, and the binder flows to the upper surface or the lower surface side. May be biased. An optimization method such as relatively increasing the average weight molecular weight with one kind of acrylic resin is also conceivable, but increasing the weight average molecular weight of the acrylic resin tends to slow down the curing rate of the binder. Therefore, it is necessary to lengthen the time for the curing step of the binder or raise the curing temperature as a countermeasure, so that productivity may be impaired or a load may be applied in terms of economy.

  By using together two types of acrylic resins having different weight average molecular weights, that is, the above acrylic resin (A) and the above acrylic resin (B), the cotton collecting step and thereafter can be performed without reducing the curing rate of the binder. The dispersion | variation in the amount of binder adhesion in the inorganic fiber heat-absorbing sound-absorbing material due to the flow of the binder generated in the step can be suppressed.

  The crosslinking agent used for the aqueous binder for inorganic fibers of the present invention is a crosslinking agent containing at least one dialkanolamine.

  Under strong acidity, the reaction between the hydroxyl group and the carboxyl group proceeds sufficiently fast, so that there are no particular limitations as long as it is a polyol, and a wide variety of compounds can be used. The reaction between the group and the hydroxyl group becomes slow, and the crosslinking reaction is difficult. For this reason, carboxyl groups, hydroxyl groups and the like tend to remain in the binder cured product, and various physical properties tend to be inferior when used as an inorganic fiber heat-absorbing sound-absorbing material.

  On the other hand, dialkanolamine is a polyol having one imino group and two primary hydroxyl groups, and the imino group reacts faster than the hydroxyl group when the reactivity of the imino group and the hydroxyl group to the carboxyl group is compared. There is a tendency.

  Therefore, by using dialkanolamine as a crosslinking agent, the reactivity with the carboxyl group can be improved, and the reactivity with the carboxyl group under weakly acidic to weakly basic conditions should be optimized. Can do.

  Examples of dialkanolamine that can be used in the present invention include diethanolamine, diisopropanolamine, and the like, and diethanolamine is particularly preferable from the viewpoint of economy.

  The aqueous binder for inorganic fibers of the present invention may further use a polyol other than dialkanolamine as a crosslinking agent.

  The polyol is not particularly limited, but is preferably a water-soluble polyol. Specifically, 1,2-ethanediol (ethylene glycol) and its dimer or trimer, 1,2- Propanediol (propylene glycol) and its dimer or trimer, 1,3-propanediol, 2,2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol 1,3-butanediol, 1,4-butanediol, 2-methyl-2,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2 4-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 2-ethyl-1,3-hexanediol, 2-hydroxymethyl-2-me Ru-1,3-propanediol, 2-ethyl-2-hydroxymethyl-2-methyl-1,3-propanediol, 1,2,6-hexanetriol, 2,2-bis (hydroxymethyl) -2 Aliphatic polyols such as 3-propanediol; trialkanolamines such as triethanolamine and triisopropanolamine; sugars such as glucose, fructose, mannitol, sorbitol, maltitol, and the above polyols, phthalic acid, and adipic acid And polyester polyols such as azelaic acid, polyethylene glycol, polypropylene glycol, and acrylic resin-based polyol. These can use together 1 type (s) or 2 or more types. Of these, trialkanolamines are preferable because they have a high boiling point and are difficult to sublimate.

  When dialkanolamine and a polyol are used in combination as a crosslinking agent, the content of the polyol in the crosslinking agent is not particularly limited, and can be appropriately adjusted depending on the pH of the aqueous binder for inorganic fibers to be used. On the other hand, the amount is preferably less than 200 parts by weight, and more preferably less than 100 parts by weight. If the content of polyol in the crosslinking agent is less than 200 parts by mass with respect to 100 parts by mass of dialkanolamines, the crosslinking reaction of the binder is sufficient even under weakly acidic to weakly basic conditions.

  And in the aqueous | water-based binder for inorganic fibers of this invention, the total number of moles of the hydroxyl group and imino group in the said crosslinking agent is 0.8 molar ratio with respect to the number of moles of the carboxyl group in the said acrylic resin. It is necessary to contain an acrylic resin and a cross-linking agent so as to be -1.5, preferably 0.9-1.2, and preferably 0.95-1.1. It is more preferable to make it contain. When the molar ratio is less than 0.8, the carboxyl group of the acrylic resin remains after the binder is cured, and when it exceeds 1.5, the dialkanolamine in the crosslinking agent remains after the binder is cured. As a result, the physical properties of the resulting inorganic fiber heat-absorbing and sound-absorbing material are lowered due to environmental factors such as moisture resistance, and excess acrylic resins or dialkanolamines are easily generated, resulting in poor economic efficiency.

  If the total number of moles of hydroxyl groups and imino groups in the crosslinking agent with respect to the number of moles of the carboxyl group of the acrylic resin is within the above range, both the acrylic resin and the crosslinking agent can be crosslinked at the time of curing the binder without excess or deficiency. Therefore, the strength of the binder cured product becomes strong, and various properties of the obtained inorganic fiber heat-absorbing sound-absorbing material can be optimized.

  Examples of the curing accelerator used in the aqueous binder for inorganic fibers of the present invention include those that accelerate the imidization reaction or esterification reaction between the carboxyl group of the acrylic resin and the imino group or the hydroxyl group of the dialkanolamine. And water-soluble ones are preferred.

  Examples of such curing accelerators include hypophosphites such as sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, magnesium hypophosphite; and organic phosphorus such as tris (3-hydroxypropyl) phosphine. Compounds; quaternary phosphonium salts such as tetraethylphosphonium salt, triethylbenzylphosphonium salt, tetra n-butylphosphonium salt, tri n-butylmethylphosphonium salt; boron trifluoride amine complex, zinc chloride, aluminum chloride, magnesium chloride, etc. Lewis acid compounds; water-soluble organometallic compounds such as titanium lactate, titanium triethanolamate, and zirconyl acetate. These can use together 1 type (s) or 2 or more types. Among them, calcium hypophosphite and tris (3-hydroxypropyl) phosphine have a high curing acceleration effect even in a small amount, and even if they remain in the binder cured product, they hardly impair the moisture resistance of the binder cured product. preferable.

  The content of the curing accelerator is preferably 0.1 to 10 parts by mass and more preferably 0.5 to 5 parts by mass in terms of solid content with respect to 100 parts by mass in total of the acrylic resin and the crosslinking agent.

  The ammonium salt of the inorganic acid used in the aqueous binder for inorganic fibers of the present invention neutralizes the alkaline component eluted from the inorganic fibers with moisture in the air.

  The aqueous binder for inorganic fibers of the present invention forms an imide bond or an ester bond by cross-linking acrylic resin and dialkanolamine, but the above bond is hydrolyzed by an alkaline component eluted from the inorganic fiber. Therefore, in the use of the inorganic fiber heat-absorbing sound absorbing material over time, the binding force between the inorganic fibers of the binder may be reduced.

  The ammonium salt of the inorganic acid is evaporated in the binder curing step, and the ammonium ions are volatilized out as ammonia and remain in the binder as an acid. Therefore, the alkali salt eluted from the inorganic fiber by containing the ammonium salt of the inorganic acid. Since the components can be neutralized and, as a result, hydrolysis of the crosslinked portion in the binder can be suppressed, various physical properties of the inorganic fiber heat-absorbing sound absorbing material can be maintained for a long period of time.

  As the ammonium salt of inorganic acid used in the present invention, ammonium sulfate, ammonium nitrate, ammonium sulfite, ammonium phosphate, ammonium phosphite, ammonium hypophosphite, ammonium polyphosphate, ammonium chloride, diammonium hydrogen phosphate, phosphoric acid Ammonium dihydrogen, ammonium hydrogen carbonate, ammonium thiosulfate, ammonium hyposulfite, ammonium chlorate, peroxodisulfuric acid diammonium, ammonium aluminum sulfate, etc. Ammonium sulfate is preferred because the hydrolysis of the binder can be suppressed by the amount.

  The content of the inorganic acid ammonium salt is preferably 0.1 to 5 parts by mass and more preferably 1 to 3 parts by mass with respect to a total of 100 parts by mass of the acrylic resin and the crosslinking agent. If it is less than 0.1 parts by mass, it is insufficient to neutralize the eluted alkaline component, and if it exceeds 5 parts by mass, it is excessive to neutralize the eluted alkaline component, and conversely Since water resistance may be impaired, it is not preferable.

  In the aqueous binder for inorganic fibers of the present invention, it is preferable to use at least one aqueous dispersion selected from waxes or a mixture of waxes and heavy oils.

  In general, acrylic resins have better adhesion to metals than phenol / formaldehyde resins, so binders easily adhere to equipment such as conveyors in the curing process of binders applied to inorganic fibers, and at the same time inorganic fibers May adhere to the manufacturing equipment. As a result, it is easy to cause irregularities on the surface of the resulting inorganic fiber product, which tends to impair the appearance of the product, and to remove the lump of inorganic fibers adhered to the manufacturing equipment, so that complicated work at high temperatures However, by blending the above waxes or a mixture of waxes and heavy oils into a binder, these components can be used as an inorganic fiber heat-absorbing sound absorbing material. It acts as a mold release agent during production and can solve these problems. At the same time, the waxes or the mixture of waxes and heavy oils can remain in the binder cured product to improve the water repellency of the inorganic fiber heat-absorbing sound-absorbing material.

  The above waxes are not strictly defined, but are solids at room temperature, but when heated to about 40 ° C. or higher, they become liquids with relatively high fluidity, specifically, beeswax, Animal waxes such as lanolin wax and shellac wax, plant waxes such as carnauba wax, wax wax, rice wax and candelilla wax, mineral waxes such as montan wax and ozokerite, petroleum waxes such as paraffin wax and microcrystalline wax. And synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, polycarbonate wax, palm oil fatty acid ester, beef tallow fatty acid ester, stearamide, dipeptadecyl ketone and hardened castor oil. These can use together 1 type (s) or 2 or more types. Of these, paraffin wax, polyethylene wax, and polypropylene wax are preferred from the viewpoint of economy.

  As heavy oils, those composed of paraffin or naphthene, which are aliphatic hydrocarbons having approximately 15 to 120 carbon atoms, are used. Heavy oils have a chemical structure relatively similar to waxes and have high fluidity, and therefore act as plasticizers for waxes. Therefore, when heating to cure the aqueous binder, the fluidity of the waxes can be increased, the wax and heavy oil can be applied evenly on the inorganic fibers, and the inorganic fiber heat insulating sound absorbing material can be separated. Variations in moldability and water repellency can be reduced.

Classification of heavy oils is carried out by the viscosity, VG (Viscosity Grade) which in the region of 320mm ² / s~680mm ² / s at that, can be preferably used in the present invention. In heavy oils having a relatively low viscosity, for example, VG of less than 320 mm ² / s, components having a carbon number of 30 or less, in particular, a carbon number of 20 or less tend to increase. When it becomes easy to volatilize and the viscosity is high, for example, VG exceeds 680 mm ² / s, it takes time to mix with the dispersant when emulsifying, which may impair productivity.

  When the waxes and the heavy oils are used in combination, the mass ratio of the waxes and the heavy oils is not particularly limited, but waxes: heavy oils = 40: 60 to 95: 5. It is preferable. When the ratio of heavy oils exceeds 60% by mass, the water repellency of the water repellent increases at room temperature, resulting in a decrease in the water repellency of the resulting inorganic fiber heat-absorbing and sound-absorbing material for a long period of time. There is. On the other hand, when the ratio of heavy oils is less than 5% by mass, when using high melting point waxes, the plasticizing effect of the waxes is reduced, and the water repellency of the resulting inorganic fiber heat insulating sound absorbing material varies. May occur. Therefore, it is more preferable that the use ratio of the heavy oils is appropriately adjusted in accordance with the melting point of the waxes used or the desired water repellency.

  Generally, since waxes and heavy oils are hydrophobic materials, when adding waxes or a mixture of waxes and heavy oils to a binder, It is preferably used after being dispersed or emulsified in water.

  There are no particular restrictions on the above-mentioned waxes and dispersants for heavy oils in water, and various surfactants, water-soluble resins, etc. may be mentioned, and the type and amount of the dispersant should be set as appropriate. Is preferred.

  And the content of the mixture of waxes or waxes and heavy oils is 0.1 to 5 parts by mass in terms of solid content with respect to 100 parts by mass in total of the acrylic resin and the crosslinking agent. Preferably, 0.5 to 3 parts by mass is more preferable, and 0.5 to 2 parts by mass is particularly preferable. When the content is less than 0.1 parts by mass, improvement in releasability and water repellency is hardly observed, and even when the content exceeds 5.0 parts by mass, the water repellency is not improved in proportion to the increase in content. It is not preferable because it is uneconomical.

  Moreover, it is preferable to use a silane coupling agent in the aqueous binder for inorganic fibers of the present invention. The silane coupling agent acts at the interface between the inorganic fiber and the binder, and can improve the adhesion of the binder to the inorganic fiber.

  Examples of the silane coupling agent used in the present invention include aminosilanes such as γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, and γ- (2-aminoethyl) aminopropylmethyldimethoxysilane. Examples of the coupling agent include epoxy silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldimethoxysilane. These can use together 1 type (s) or 2 or more types.

  And as for content of a silane coupling agent, 0.1-2.0 mass parts is preferable in conversion of solid content with respect to a total of 100 mass parts of acrylic resin and a crosslinking agent.

  Moreover, in the aqueous | water-based binder for inorganic fibers of this invention, you may further add a dustproof agent, a coloring agent, etc. as needed.

  The aqueous binder for inorganic fibers of the present invention is one kind selected from the acrylic resin, a crosslinking agent, a curing accelerator, and, if necessary, waxes or a mixture of waxes and heavy oils. An aqueous dispersion, a silane coupling agent, and the like can be prepared by mixing using a tank equipped with a stirrer such as a dissolver.

  Examples of the form of the aqueous binder include emulsions, colloidal dispersions, and water-soluble compositions. However, emulsions and colloidal dispersions have poor miscibility between the dispersed resin component and water, and are water as a medium. When volatilizes, it has the characteristic that it is easy to form a film. If the resin composition in the binder forms a film before curing, the fluidity of the binder on the fiber surface is liable to be impaired, and not only an inorganic heat-insulating sound-absorbing material with a uniform amount of binder can be obtained, but also fibers. In some cases, there are many portions that are not bonded by the binder, and it is difficult to maintain the shape of the product. In addition, in colloidal dispersions and emulsions, once the medium water is volatilized and a film is formed, it is difficult to return to the aqueous material again. Tend to occur.

  On the other hand, when the aqueous binder is a water-soluble composition, since there is no film formation due to volatilization of water, the above problems do not occur. Therefore, it is preferable to prepare the aqueous binder for inorganic fibers of the present invention as a water-soluble composition.

  Here, the emulsion refers to an emulsion emulsified with an emulsifier different from the resin component, for example, a surfactant, and the colloidal dispersion refers to a material dispersed in water by a functional group in the resin component. Both are milky white in appearance. On the other hand, a water-soluble composition refers to a resin component that is completely dissolved in water, and has an appearance that is transparent or nearly transparent.

  Moreover, it is necessary to adjust using the volatile basic compound so that pH of the aqueous | water-based binder for inorganic fibers may be set to 6.0-8.0, 6.0-7.0 are preferable and 6.0 are preferable. -6.5 is more preferred. If the pH is less than 6.0, the production equipment may be corroded due to long-term use, and wastewater treatment costs are required. If the pH exceeds 8.0, the crosslinking reaction in the binder is slow. Therefore, curing is not completed, or heating for a long time is required to complete the curing, and it is easy to impair the productivity. Is easily damaged. If the pH of the aqueous binder for inorganic fibers is within the above range, the corrosion of the production equipment can be suppressed, and the wastewater treatment can be facilitated, so that the maintenance cost can be reduced.

  And as a volatile basic compound used for adjustment of pH, ammonia water or amines is mentioned, When considering the odor etc. which generate | occur | produce at the time of hardening, it is preferable to use ammonia water.

  Moreover, 5-40 mass% is preferable and, as for the solid content of the aqueous | water-based binder for inorganic fibers, 10-30 mass% is more preferable. If the solid content is less than 5% by mass, the amount of water increases, and it may take time in the curing process, which may impair the productivity. If it exceeds 40% by mass, the viscosity increases and the fluidity of the binder decreases. .

  Next, the inorganic fiber heat insulating sound absorbing material of the present invention will be described.

  The inorganic fiber heat-absorbing sound-absorbing material of the present invention is obtained by forming the above-mentioned aqueous binder for inorganic fibers on inorganic fibers and heating and curing the binder.

  The inorganic fiber heat insulating sound-absorbing material of the present invention can be produced, for example, as follows. That is, first, the molten inorganic raw material is fiberized with a fiberizing apparatus, and immediately after that, the above-mentioned aqueous binder for inorganic fibers is applied to the inorganic fibers. Next, the inorganic fiber to which the aqueous binder for inorganic fibers is applied is deposited on the perforated conveyor to form a bulky inorganic fiber heat-absorbing sound-absorbing material intermediate (cotton collecting step) so that the desired thickness is obtained. It feeds into a pair of upper and lower perforated conveyors provided with an interval, and heats while narrowing pressure to cure the inorganic fiber aqueous binder to form an inorganic fiber heat insulating sound absorbing material (curing step). And a skin material etc. are coat | covered as needed, and a product is obtained by cut | disconnecting the inorganic fiber heat insulation sound-absorbing material to the desired width | variety and length.

  Hereinafter, each step will be described in more detail.

It does not specifically limit as an inorganic fiber used for the inorganic fiber heat insulation sound-absorbing material of this invention, The glass wool, the rock wool, etc. which are used for the normal heat insulation sound absorption material can be used. Various methods such as a flame method, a blow-off method, and a centrifugal method (also referred to as a rotary method) can be used as a method for forming inorganic fibers. In particular, when the inorganic fiber is glass wool, it is preferable to use a centrifugal method. In addition, the density of the target inorganic fiber heat-insulating material may be a density used in ordinary heat-insulating materials and sound-absorbing materials, and is preferably in the range of 5 to 300 kg / m ³ .

  In order to impart the binder to the inorganic fibers, it is applied and sprayed using a spray device or the like. The amount of the binder applied can be adjusted by the same method as that for a conventional binder not containing a water repellent. The amount of the binder to be applied varies depending on the density and use of the inorganic fiber heat-absorbing sound absorbing material. Preferably, the range of 0.5-9 mass% is more preferable.

  The timing of applying the binder to the inorganic fiber sound-absorbing heat insulating material may be any time after fiberization, but in order to efficiently apply the binder, it is preferable to apply it immediately after fiberization.

  The inorganic fiber to which the binder has been applied by the above process is deposited on a perforated conveyor and becomes a bulky inorganic fiber intermediate. Here, when depositing on the perforated conveyor, it is more preferable to suck by the suction device from the opposite side of the perforated conveyor on which the inorganic fibers are deposited.

  After that, the inorganic fiber intermediate that continuously moves on the perforated conveyor is sent to a pair of upper and lower perforated conveyors and the like that are spaced so as to have a desired thickness, and at the same time, the binder is removed by heated hot air. After curing and forming the inorganic fiber heat-absorbing sound-absorbing material into a mat shape, it is cut into a desired width and length.

  Although the heat curing temperature of a binder is not specifically limited, 200-350 degreeC is preferable. Further, the heat curing time is appropriately adjusted between 30 seconds and 10 minutes depending on the density and thickness of the inorganic fiber heat-absorbing sound-absorbing material.

  The inorganic fiber heat-absorbing sound-absorbing material of the present invention may be used as it is, or may be used after being covered with a skin material. As the skin material, paper, synthetic resin film, metal foil film, non-woven fabric, woven fabric, or a combination thereof can be used.

  The inorganic fiber heat-insulating and sound-absorbing material of the present invention thus obtained does not release formaldehyde during the heat curing of the binder, and therefore has less environmental impact than conventional phenol-formaldehyde binders. is there.

  Hereinafter, the present invention will be described in more detail by way of examples. In the following description, “part” and “%” are based on mass unless otherwise specified.

Example 1
A resin solution (solid content 45%) in which an acrylic resin (acid value 690 mgKOH / g, weight average molecular weight 2,000) composed of acrylic acid and methyl acrylate is dissolved in water is cross-linked with 100 parts in terms of solid content. 52.7 parts of diethanolamine as an agent and 6.0 parts of sodium hypophosphite as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.05) to obtain a water-soluble composition adjusted to pH 6.5 with 25% aqueous ammonia, and 0.3 parts of γ-aminopropyltriethoxysilane and 2.0 parts of ammonium sulfate as a silane coupling agent After stirring and diluting with water to a solid content of 15%, paraffin wax aqueous dispersion with a solid content of 40% was added to 5.0 parts. It was obtained inorganic fibers aqueous binder.

(Example 2)
100 parts of a resin solution (solid content 35%) obtained by dissolving an acrylic resin (acid value 710 mg KOH / g, weight average molecular weight 14,000) composed of styrene and maleic acid with water in terms of solid content, and diethanolamine as a crosslinking agent Was mixed with 49.9 parts of calcium hypophosphite as an oxidation accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.0). A water-soluble composition adjusted to pH 6.0 with 25% aqueous ammonia was obtained, and 0.3 parts of γ-aminopropyltriethoxysilane and 3.0 parts of ammonium sulfate were further added and stirred as a silane coupling agent. Then, it diluted with water so that solid content might be set to 15%, and the aqueous | water-based binder for inorganic fiber of Example 2 was obtained.

(Example 3)
A resin solution (solid content 45%) in which an acrylic resin (acid value 380 mgKOH / g, weight average molecular weight 7,800) made of acrylic acid, styrene and methyl acrylate is dissolved in water is 100 parts in terms of solid content, 28.5 parts of diisopropanolamine as a crosslinking agent and 4.0 parts of tris (3-hydroxypropyl) phosphine as a curing accelerator were mixed (total molar amount of imino group and hydroxyl group of the crosslinking agent / acrylic resin And a water-soluble composition adjusted to pH 6.0 with 25% aqueous ammonia, and γ- (2-aminoethyl) aminopropyltrimethoxy as a silane coupling agent. After adding and stirring 0.2 parts of silane and 1.5 parts of ammonium sulfate, it was diluted with water so that the solid content was 15%, and the solid content was 40%. Paraffin wax aqueous dispersion 4.0 parts were added, to obtain an inorganic fibrous aqueous binder of Example 3.

Example 4
A resin solution (solid content 30%) in which an acrylic resin (acid value 560 mg KOH / g, weight average molecular weight 17,500) composed of acrylic acid, styrene and methyl acrylate is dissolved in water is 100 parts in terms of solid content, Mixing 38.4 parts of diethanolamine as a crosslinking agent and 6.0 parts of calcium hypophosphite as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1) 10) and a water-soluble composition adjusted to pH 6.5 with 25% aqueous ammonia, and further 0.3 parts of γ-aminopropyltriethoxysilane and 2.0 parts of ammonium sulfate as a silane coupling agent. After adding and stirring, it diluted with water so that solid content might be 12%, and the aqueous binder for inorganic fibers of Example 4 was obtained.

(Example 5)
100 parts of a resin solution (45% solid content) in which an acrylic resin (acid value 690 mgKOH / g, weight average molecular weight 1,500) made of acrylic acid and methyl acrylate is dissolved in water, in terms of solid content, and a crosslinking agent 30 parts of triethanolamine and 25.5 parts of diethanolamine and 6.0 parts of sodium hypophosphite as a curing accelerator (total molar amount of imino group and hydroxyl group of the crosslinking agent / acrylic resin) The water-soluble composition was adjusted to pH 6.0 with 25% aqueous ammonia, and γ- (2-aminoethyl) aminopropyltrimethyl was added as a silane coupling agent. After adding 0.3 parts of methoxysilane and 3.0 parts of ammonium metaphosphate and stirring, it was diluted with water so that the solid content was 15%, and the solid content was 40%. Olefin wax: the viscosity grade 320 mm 2 / ^s of the heavy oil = 1: with the addition of one of the water dispersion 5.0 parts, to obtain an inorganic fibrous aqueous binder of Example 5.

(Example 6)
A resin solution (solid content 40%) in which an acrylic resin (acid value 380 mgKOH / g, weight average molecular weight 7,800) composed of acrylic acid, styrene and methyl acrylate is dissolved in water is 100 parts in terms of solid content, Mixing 35.5 parts of diethanolamine as a crosslinking agent and 4.0 parts of tris (3-hydroxypropyl) phosphine as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / carboxyl of acrylic resin) The water-soluble composition was adjusted to pH 6.0 with 25% aqueous ammonia, and γ- (2-aminoethyl) aminopropyltrimethoxysilane was further used as a silane coupling agent. After adding 0.2 part and 2.0 parts of ammonium sulfate and stirring, it was diluted with water so that the solid content was 15%, and the solid content was 40%. The Inwakkusu aqueous dispersion 4.0 parts were added, to obtain an inorganic fibrous aqueous binder of Example 6.

(Example 7)
Acrylic resin composed of acrylic acid and methyl acrylate (acid value 640 mg KOH / g, weight average molecular weight 2,200) 80%, and acrylic resin composed of styrene and maleic acid (acid value 710 mg KOH / g, weight average molecular weight 17) , 500) A resin solution (solid content 40%) in which a 20% mixture is dissolved in water, 100 parts in terms of solid content, 40.8 parts diethanolamine as a crosslinking agent, and calcium hypophosphite as a hardening accelerator 6.0 parts mixed (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.0) and adjusted to pH 6.5 with 25% aqueous ammonia In addition, 0.2 parts of γ- (2-aminoethyl) aminopropyltrimethoxysilane as a silane coupling agent and ammonium sulfate After adding 2.0 parts of nickel and stirring, it was diluted with water so that the solid content was 15%, and 4.0 parts of a paraffin wax aqueous dispersion with a solid content of 40% was added. An aqueous binder for inorganic fibers was obtained.

(Comparative Example 1)
100 parts of a resin solution (solid content 40%) in which an acrylic resin (acid value 690 mgKOH / g, weight average molecular weight 1,500) made of acrylic acid and methyl acrylate is dissolved in water, in terms of solid content, and a crosslinking agent As a curing accelerator, 74.8 parts of triethanolamine and 6.0 parts of calcium hypophosphite are mixed as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.05), and a water-soluble composition adjusted to pH 6.5 with 25% aqueous ammonia was obtained. Further, 0.3 part of γ-aminopropyltriethoxysilane was added as a silane coupling agent and stirred. Then, diluted with water so that the solid content is 15%, 5.0 parts of a 40% solid content paraffin wax aqueous dispersion is added, and the aqueous binder for inorganic fibers of Comparative Example 1 is added. It was.

(Comparative Example 2)
100 parts of a resin solution (solid content 40%) in which an acrylic resin (acid value 690 mgKOH / g, weight average molecular weight 1,500) made of acrylic acid and methyl acrylate is dissolved in water, in terms of solid content, and a crosslinking agent As a curing accelerator, 74.8 parts of triethanolamine and 6.0 parts of calcium hypophosphite are mixed as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.05) to obtain a water-soluble composition adjusted to pH 6.5 with 25% aqueous ammonia, and 0.3 parts of γ-aminopropyltriethoxysilane and 2.0 parts of ammonium sulfate as a silane coupling agent Was added and stirred, diluted with water so that the solid content was 15%, and 5.0 parts of an aqueous paraffin wax dispersion with a solid content of 40% was added. It was obtained inorganic fibers aqueous binder.

(Comparative Example 3)
A resin solution (solid content 35%) obtained by dissolving an acrylic resin (acid value 710 mg KOH / g, weight average molecular weight 14,000) composed of styrene and maleic acid with water is 100 parts in terms of solid content, and penta as a crosslinking agent. 49.1 parts of erythritol and 6.0 parts of calcium hypophosphite as a curing accelerator were mixed (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.0). To obtain a water-soluble composition adjusted to pH 6.0 with 25% aqueous ammonia, and 0.3 parts of γ-aminopropyltriethoxysilane and 2.0 parts of ammonium sulfate were added as silane coupling agents. After stirring, the mixture was diluted with water so that the solid content was 15% to obtain an aqueous binder for inorganic fibers of Comparative Example 3.

(Comparative Example 4)
A resin solution (solid content 40%) in which an acrylic resin (acid value 380 mgKOH / g, weight average molecular weight 7,800) composed of acrylic acid, styrene and methyl acrylate is dissolved in water is 100 parts in terms of solid content, Mixing 47.3 parts of diethanolamine as a crosslinking agent and 4.0 parts of tris (3-hydroxypropyl) phosphine as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / carboxyl of acrylic resin) Molar amount of the group = 2.0) to obtain a water-soluble composition adjusted to pH 6.0 with 25% aqueous ammonia, and γ- (2-aminoethyl) aminopropyltrimethoxysilane as a silane coupling agent After adding 0.2 part and 2.0 parts of ammonium sulfate and stirring, it was diluted with water so that the solid content was 15%, and the solid content was 40%. The Inwakkusu aqueous dispersion 4.0 parts were added, to obtain an inorganic fibrous aqueous binder of Comparative Example 4.

(Comparative Example 5)
A resin solution (solid content 45%) in which an acrylic resin (acid value 690 mgKOH / g, weight average molecular weight 2,000) composed of acrylic acid and methyl acrylate is dissolved in water is cross-linked with 100 parts in terms of solid content. 52.7 parts of diethanolamine as an agent and 6.0 parts of sodium hypophosphite as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.05), and a water-soluble composition adjusted to pH 6.5 with 25% aqueous ammonia was obtained. Further, 0.3 part of γ-aminopropyltriethoxysilane was added as a silane coupling agent and stirred. Then, dilute with water so that the solid content is 15%, and add 5.0 parts of a 40% solid content paraffin wax aqueous dispersion to obtain an aqueous binder for inorganic fibers of Comparative Example 5. .

(Comparative Example 6)
100 parts of a resin solution (solid content 30%) obtained by dissolving an acrylic resin (acid value 280 mgKOH / g, weight average molecular weight 35,000) made of acrylic acid, styrene and methyl acrylate with water, Mixing 19.2 parts of diethanolamine as a crosslinking agent and 6.0 parts of calcium hypophosphite as a curing accelerator (total molar amount of imino group and hydroxyl group of crosslinking agent / molar amount of carboxyl group of acrylic resin = 1.10) to obtain a water-soluble composition adjusted to pH 6.5 with 25% aqueous ammonia, and further, 0.3 parts of γ-aminopropyltriethoxysilane as a silane coupling agent was added and stirred. And it diluted with water so that solid content might be 10%, and the aqueous binder for inorganic fiber of the comparative example 6 was obtained.

(Comparative Example 7)
A colloidal dispersion (solid content 28%) obtained by neutralizing acrylic resin (acid value 80 mgKOH / g, weight average molecular weight 240,000) consisting of acrylic acid, styrene and methyl acrylate with 25% aqueous ammonia. 100 parts by mass in terms of solid content, 5.5 parts of diethanolamine as a crosslinking agent, and 3.0 parts of calcium hypophosphite as a curing accelerator (total molar amount of imino group and hydroxyl group of the crosslinking agent / acrylic system) After adding 0.3 parts of γ-aminopropyltriethoxysilane as a silane coupling agent and stirring, water was added so that the solid content would be 10%. The aqueous binder for inorganic fibers of Comparative Example 7 was obtained.

(Comparative Example 8)
100 parts of a resol-type phenol resin precursor having a monomer content of 10% or less, a dimer of 80% or more, and a free phenol of 1% or less, dispersed in water, and γ- (2 as a silane coupling agent -Aminoethyl) 0.2 parts of aminopropyltrimethoxysilane, 2.0 parts of ammonium sulfate as a neutralizing agent for the alkali component from the curing accelerator and inorganic fibers, and 450 parts of water were provided with a dissolver. The mixture was prepared in an open tank and diluted with water so that the solid content was 15% while stirring to obtain an aqueous binder for inorganic fibers of Comparative Example 6.

  About the inorganic fiber heat insulation sound-absorbing material using the aqueous | water-based binder for inorganic fibers of Examples 1-7 and Comparative Examples 1-8, the formaldehyde discharge | release amount and the tear load were evaluated by the following method. The results are summarized in Table 1.

[Evaluation of formaldehyde emission]
After applying the aqueous fiber binders of Examples 1 to 7 and Comparative Examples 1 to 8 to the glass fibers that have been fiberized by the centrifugal method so as to have a predetermined adhesion amount, they are present while sucking with a suction device. It was deposited on a hole conveyor to form an intermediate of an inorganic fiber heat-absorbing sound absorbing material. The intermediate is heated in hot air at 260 ° C. for 3 minutes to cure the binder, thereby obtaining an inorganic fiber heat-absorbing sound absorbing material (glass wool) having a density of 16 kg / m ³ , a thickness of 100 mm, and a binder adhesion of 3.0%. It was.
The gas generated during the curing of the glass wool binder was collected in a 4-liter odor bag, and the amount of formaldehyde released was measured using a gas detector.

  When the glass wool obtained using the phenolic binder of Comparative Example 8 was cured, 40 ppm of formaldehyde was detected, but obtained using the binder containing the acrylic resins of Examples 1 to 7 and Comparative Examples 1 to 7. Formaldehyde was not detected when the glass wool was cured.

[Evaluation of tearing load]
After applying the aqueous fiber binders of Examples 1 to 7 and Comparative Examples 1 to 8 to the glass fibers that have been fiberized by the centrifugal method so as to have a predetermined adhesion amount, they are present while sucking with a suction device. It was deposited on a hole conveyor to form an intermediate of an inorganic fiber heat-absorbing sound absorbing material. The intermediate is heated in hot air at 260 ° C. for 5 minutes to cure the binder, and the inorganic fiber heat insulating sound absorbing material has a density of 32 kg / m 3, a length of 1350 mm, a width of 430 mm, a thickness of 50 mm and a binder adhesion of 6.0%. (Glass wool board) was obtained. Then, the end face portion of the obtained 32 kg / m ³ glass wool board was sandwiched with a chuck of a universal testing machine in the thickness direction, and the tear load was measured at a speed of 1 m / min.
Moreover, after leaving still the inorganic fiber heat insulation sound-absorbing material shape | molded with the aqueous | water-based binder for inorganic fibers of Examples 1-7 and Comparative Examples 1-8 for 4 weeks on 40 degreeC and humidity 95% conditions, Was evaluated.
In the glass wool board using the binder of Comparative Example 6, many stains due to adhesiveness of the binder and adhesion of inorganic fibers were observed on the perforated conveyor forming the intermediate of the inorganic fiber heat-absorbing sound absorbing material. Moreover, in the glass wool board using the binder of the comparative example 7, adhesion of the thin inorganic fiber layer was observed on the conveyor at the time of hardening.

  From the above results, in the inorganic fiber heat-absorbing sound-absorbing material using the aqueous binder for inorganic fibers of Comparative Examples 1 and 2, the adhesion between the fiber and the fiber by the binder was deteriorated over time. In Comparative Example 2, the binder contains an ammonium salt of an inorganic acid for neutralizing the alkali component eluted from the inorganic fiber, but the evaluation after aging under high temperature and high humidity is inferior. In the binder of Comparative Example 2, it is considered that curing is not completely completed.

  Since the inorganic fiber heat-absorbing and sound-absorbing material using the aqueous binder for inorganic fibers of Comparative Example 3 uses pentaerythritol having four hydroxyl groups that do not contain an imino group as a cross-linking agent, the conditions are weakly acidic to weakly basic. Below, the reaction between the carboxyl group and the hydroxyl group becomes gradual and the crosslinking reaction is difficult. Therefore, the tearing load is inferior, and furthermore, as the number of days under high temperature and high humidity passes, the adhesion between the fiber and the fiber by the binder is lost over time.

  The inorganic fiber heat insulating sound absorbing material using the inorganic fiber aqueous binder of Comparative Example 4 has an adverse effect on the hygroscopicity of the inorganic fiber heat insulating sound absorbing material due to the excess crosslinking component, and the tear load compared to Examples 1-7. Further, as the number of days under high temperature and high humidity passed, the adhesion between the fibers and the fibers by the binder was deteriorated over time.

  The inorganic fiber heat-absorbing and sound-absorbing material using the inorganic fiber aqueous binder of Comparative Example 5 is the same binder as in Example 1, but does not contain an ammonium salt of an inorganic acid, and the number of days under high temperature and high humidity. The tear load tended to decrease as time passed.

  Since the acid value of the acrylic resin is out of the acid value region of the present invention, the inorganic fiber heat-absorbing sound-absorbing material using the inorganic fiber aqueous binder of Comparative Example 6 is insufficient because the crosslinking density of the binder is insufficient. The strength was not obtained, and as the number of days under high temperature and high humidity passed as compared with Examples 1 to 7, the adhesion between the fibers and the fibers by the binder was deteriorated with time, and the tear load was inferior.

  The inorganic fiber heat-absorbing and sound-absorbing material using the inorganic fiber aqueous binder of Comparative Example 7 has a film-forming property, which is the property of colloidal dispersion, since the binder and the inorganic fiber are bonded to the curing conveyor at the time of manufacture. It was speculated that it was acting, and the tearing load was extremely inferior.

  On the other hand, the inorganic fiber heat insulating sound absorbing material using the aqueous binder for inorganic fibers of Examples 1 to 7 does not release formaldehyde when the binder is cured, and the inorganic fiber heat insulating sound absorbing sound of Comparative Example 8 using a phenol resin binder is used. The tear load was equal to or greater than that of the material.

  Since the water-based binder for inorganic fibers of the present invention does not contain formaldehyde at all, it can be used as an inorganic fiber heat-absorbing and sound-absorbing material that has a low environmental load and can be suitably used as a heat-insulating material or sound-absorbing material for houses and buildings.

Claims (7)

  A carboxyl group in the acrylic resin comprising an acrylic resin having an acid value of 350 to 850 mg KOH / g, a crosslinking agent containing at least one dialkanolamine, a curing accelerator, and an ammonium salt of an inorganic acid. The total number of moles of the hydroxyl group and imino group in the crosslinking agent is 0.8 to 1.5 in terms of mole ratio, and the pH is 6.0 to 8.8 depending on the volatile basic compound. An aqueous binder for inorganic fibers, which is adjusted to 0.   The aqueous binder for inorganic fibers according to claim 1, wherein the acrylic resin has a weight average molecular weight of 1,000 to 15,000.   The acrylic resin is a mixture of an acrylic resin (A) having a weight average molecular weight of 1,000 to 4,000 and an acrylic resin (B) having a weight average molecular weight of 8000 to 20,000. Item 12. An aqueous binder for inorganic fibers according to Item 1.   The aqueous binder for inorganic fibers according to claim 1, wherein the ammonium salt of the inorganic acid is ammonium sulfate.   One aqueous dispersion selected from waxes or a mixture of waxes and heavy oils is 0.1 in terms of solid content with respect to 100 parts by mass in total of the acrylic resin and the crosslinking agent. The aqueous binder for inorganic fibers according to claim 1, which contains ˜5 parts by mass.   Inorganic fiber as described in any one of Claims 1-5 which contains 0.1-2.0 mass parts of silane coupling agents with respect to a total of 100 mass parts of the said acrylic resin and the said crosslinking agent. Water-based binder.   An inorganic fiber heat-absorbing sound-absorbing material obtained by applying the aqueous fiber binder for inorganic fibers according to any one of claims 1 to 6 to an inorganic fiber, followed by heat curing.