Method for preparing aqueous binder for inorganic fiber adiabatic sound-absorbing material

Abstract

To provide a method for producing an aqueous binder for an inorganic fiber heat-insulating and sound-absorbing material, which reduces the amount of ammonia gas emitted during production of the inorganic fiber heat-insulating and sound-absorbing material.SOLUTION: A method for producing an aqueous binder for an inorganic fiber thermal-insulating sound-absorbing material, comprising: an acid addition step of adding an acid to a phenol-formaldehyde resin composition comprising a resol-type phenol-formaldehyde resin and an amine compound; and a water addition step of adding water after the acid addition step to adjust the solid content concentration, wherein the aqueous binder for an inorganic fiber thermal-insulating sound-absorbing material has a pH of 8.1 to 9.4.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing an aqueous binder for an inorganic fiber heat-insulating and sound-absorbing material. [Background technology]

[0002] Inorganic fiber thermal insulation and sound-absorbing materials such as glass wool and rock wool are generally produced by attaching a binder to inorganic fibers and then curing the binder. Binders containing phenol-formaldehyde resins obtained by reacting phenols with formaldehydes as the main component (hereinafter also referred to as "phenolic resin binders") are widely used because they are relatively inexpensive and produce inorganic fiber thermal insulation and sound-absorbing materials with excellent performance, such as mechanical strength. However, when a phenolic resin binder is used, there are problems such as formaldehyde volatilization during the manufacturing process of the inorganic fiber heat-insulating sound-absorbing material and formaldehyde emission from the obtained inorganic fiber heat-insulating sound-absorbing material product. Formaldehyde is a substance that has adverse effects on the human body. For example, aldehyde emitted from building materials is considered to be one of the substances that cause sick building syndrome.

[0003] One of the countermeasures for the problem of formaldehyde volatilization during the manufacturing process of inorganic fiber thermal and acoustic insulation materials (such as the binder application process) is to modify phenol-formaldehyde resin with urea. In this case, the urea introduced into the phenol-formaldehyde resin captures the free formaldehyde in the phenol-formaldehyde resin, reducing the amount of formaldehyde volatilization during the manufacturing process and improving the working environment. To address the issue of formaldehyde emissions from inorganic fiber heat and sound absorbing materials, a formaldehyde scavenger such as adipic acid dihydrazide is applied to the product. The formaldehyde scavenger reacts with and fixes the generated formaldehyde, thereby reducing the amount of formaldehyde emitted. However, it is difficult to produce inorganic fiber products with low formaldehyde emissions and good performance at low cost using the above-mentioned conventional methods.

[0004] For example, while the method of modifying phenol-formaldehyde resin with urea is effective in reducing the amount of formaldehyde emitted during the manufacturing process, it tends to actually increase the amount of formaldehyde emitted from the resulting inorganic fiber thermal and acoustic insulation material product. This is thought to be because the formaldehyde source is fixed in the product, remains as latent formaldehyde, and is re-released through hydrolysis, etc. In addition, binders using phenol-formaldehyde resin modified with urea have the problem that the performance of the resulting inorganic fiber thermal and acoustic insulation material product, such as water resistance, is lower than when non-urea-modified phenol-formaldehyde resin is used. Although the use of formaldehyde scavengers is effective in reducing formaldehyde emissions, they can sometimes cause quality problems such as discoloration and stickiness. Furthermore, because formaldehyde scavengers are more expensive than phenol-formaldehyde resins, using large amounts of them reduces the cost benefits of phenolic resin binders. Furthermore, because formaldehyde scavengers are typically added after the binder has cured, this can also complicate the process.

[0005] Under these circumstances, a method for reducing the amount of free formaldehyde has been proposed in which formaldehyde and phenol are reacted in the presence of a base catalyst to synthesize a resol-type phenol-formaldehyde resin, and then an amine is added at 50 to 65°C to cause the unreacted formaldehyde and phenol to react with the amine to form a condensate (see Patent Document 1).Furthermore, in order to prevent a decrease in the water dilutability of the binder due to the formation of a condensate of the unreacted formaldehyde and phenol with the amine, a method has been proposed in which a monoamine is added at a temperature below 50°C after synthesizing a resol-type phenol-formaldehyde resin to suppress the formation of the condensate while reducing the amount of formaldehyde emitted (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5450070 [Patent Document 2] Patent No. 7082893 [Patent Document 3] Patent No. 3784067 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the amine added by the above method decomposes and generates ammonia gas when it comes into contact with high-temperature inorganic fibers or when it is exposed to heat from the immediately preceding fiberization step during the binder application step in the manufacturing process of inorganic fiber thermal and acoustical insulation materials. Since discharging a large amount of ammonia gas into the atmosphere is an environmental problem, an ammonia removal step such as acid washing of the exhaust gas is required, which increases costs. As a method for reducing the amount of ammonia gas released from the binder, for example, a method of neutralizing the ammonia in a phenol-formaldehyde resin formulation by adding a sugar compound has been proposed (see Patent Document 3), but the addition of the sugar compound may cause undesirable discoloration of the product.

[0008] Therefore, an object of the present invention is to provide a method for producing an aqueous binder for an inorganic fiber thermal insulation sound-absorbing material, which reduces the amount of ammonia gas emitted during the production of the inorganic fiber thermal insulation sound-absorbing material. [Means for solving the problem]

[0009] That is, the present invention is as follows. [1] A method for producing an aqueous binder for inorganic fiber thermal and acoustic insulation materials, an acid addition step of adding an acid to a phenol-formaldehyde resin composition containing a resol-type phenol-formaldehyde resin and an amine compound; a water addition step of adding water to adjust the solid content concentration after the acid addition step; Including, The pH of the aqueous binder for inorganic fiber heat and sound absorbing materials is 8.1 to 9.4. A method for producing an aqueous binder for an inorganic fiber heat and sound absorbing material, comprising: [2] [1] The method for producing an aqueous binder for an inorganic fiber thermal insulating and acoustical material according to [1], wherein the resol-type phenol-formaldehyde resin is a resol-type phenol-formaldehyde resin synthesized by reacting a phenol with a formaldehyde using a catalyst containing triethylamine. [3] The method for producing an aqueous binder for a thermal insulating and acoustical inorganic fiber material according to [1] or [2], wherein the amine compound contains an amine compound other than the amine compound contained in the catalyst used in synthesizing the resol-type phenol-formaldehyde resin. [4] The method for producing an aqueous binder for a thermal insulating and acoustical inorganic fiber material according to [3], wherein the amine compound other than the amine compound contained in the catalyst is monoethanolamine. [5] The method for producing an aqueous binder for a thermal and acoustical inorganic fiber material according to any one of [1] to [4], wherein the acid is sulfuric acid. [6] The method for producing an aqueous binder for an inorganic fiber thermal and acoustical insulating material according to any one of [1] to [5], further comprising a urea addition step of adding urea after the acid addition step and before the water addition step. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing an aqueous binder for an insulating and acoustic inorganic fiber material, which reduces the amount of ammonia gas emitted during the production of the insulating and acoustic inorganic fiber material. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist thereof.

[0012] [Method for manufacturing aqueous binder for inorganic fiber heat and sound absorbing material] The method for producing the aqueous binder for an inorganic fiber thermal insulating and acoustical material (hereinafter also simply referred to as "aqueous binder") of this embodiment is characterized by including an acid addition step of adding an acid to a phenol-formaldehyde resin composition containing a resol-type phenol-formaldehyde resin and an amine compound, and a water addition step of adding water after the acid addition step to adjust the solids concentration. The method for producing the aqueous binder of the present embodiment may include, in addition to the acid addition step and the water addition step, other steps such as a resin synthesis step, an amine compound addition step, and another component addition step (such as a urea addition step), as necessary. The aqueous binder in this specification refers to a composition that includes a phenol-formaldehyde resin composition containing an amine compound, an acid, and water for adjusting the concentration, and optionally includes other components such as urea, a curing accelerator, a silane coupling agent, a dust inhibitor, a rust inhibitor, a water repellent, and a colorant, within the scope of not impairing the effects of the present invention.

[0013] (Phenol formaldehyde resin composition) The phenol-formaldehyde resin composition to which acid is added in the acid addition step is not particularly limited as long as it contains a resole-type phenol-formaldehyde resin and an amine compound, and may be an industrially available commercially available product, or an industrially available commercially available resole-type phenol-formaldehyde resin to which an amine compound has been added, or, as will be described later, a synthesized resole-type phenol-formaldehyde resin to which an amine compound has been added, or a resole-type phenol-formaldehyde resin containing an amine compound obtained by synthesizing a resole-type phenol-formaldehyde resin using a catalyst containing an amine compound.

[0014] ((Resol-type phenol formaldehyde resin)) The resol-type phenol-formaldehyde resin contained in the phenol-formaldehyde resin composition may be one type alone or a combination of two or more types. The weight-average molecular weight of the resol-type phenol-formaldehyde resin is preferably from 150 to 800, more preferably from 150 to 600, and even more preferably from 150 to 400. When the weight-average molecular weight of the resol-type phenol-formaldehyde resin is at least the lower limit of the above range, there is a tendency for the yield and strength of the aqueous binder in the inorganic fiber heat insulating acoustic material to decrease, while when it is at most the upper limit of the above range, there is a tendency for the water dilution property and stability over time of the aqueous binder to improve. In this specification, the weight average molecular weight of the resol-type phenol formaldehyde resin is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance. In this specification, the water dilutability of an aqueous binder can be evaluated by its miscibility with water (mass%) measured for an aqueous binder with a solid content concentration of 40 mass% in accordance with the provisions of JIS K6910:2007, Section 5.5. If the miscibility of the aqueous binder with water is 600 mass% or more, the water dilutability is good, and it is possible to prevent the aqueous binder from precipitating in the binder liquid delivery pipe, for example.

[0015] ((amine compounds)) As described above, the amine compound contained in the phenol-formaldehyde resin composition may be the catalyst used in synthesizing the resol-type phenol-formaldehyde resin, or may be one added after the synthesis of the resol-type phenol-formaldehyde resin, or may be both.

[0016] When the amine compound is a catalyst used in synthesizing a resol-type phenol-formaldehyde resin, examples of the amine compound include tertiary amines such as triethylamine, trimethylamine, and triethanolamine, and cyclic amines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene).

[0017] Furthermore, when the amine compound is added later to the resole type phenol formaldehyde resin, the amine compound is not particularly limited, and examples thereof include aliphatic amines, alicyclic amines, aromatic amines, and amine derivatives. Examples of aliphatic amines include alkanolamines and alkylamines. Examples of alkanolamines include (mono-, di-, or tri-)ethanolamine, (mono-, di-, or tri-)isopropanolamine, N-methylethanolamine, and N-methyldiethanolamine. Examples of alkylamines include (mono-, di-, or tri-)methylamine, (mono-, di-, or tri-)ethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, tetramethylethylenediamine, hexaethyleneheptamine, heptaethyleneoctamine, N-(3-aminopropyl)butane-1,4-diamine, N,N-di(3-aminopropyl)butane-1,4-diamine, and bishexamethylenetriamine. Examples of the alicyclic amine include piperidine, piperazine, pyrrolidine, morpholine, pyrrole, pyridine, pyrazole, imidazole, and oxazole. Examples of aromatic amines include aniline, aminophenol, and toluidine. Examples of the amine derivatives include ether amines and amino acids. Examples of the amino acids include glycine, glutamine, and glutamic acid. Among these, monoamines are preferred, aliphatic monoamines are more preferred, primary or secondary aliphatic monoamines are even more preferred, and monoethanolamine is particularly preferred, as they are more likely to have the effect of reducing the amount of formaldehyde emitted from the aqueous binder.

[0018] The amine compound may be used alone or in combination of two or more kinds.

[0019] The molecular weight of the amine compound is preferably 300 or less, more preferably 200 or less, and even more preferably 150 or less, from the viewpoint of reducing formaldehyde emission from the aqueous binder and suppressing a decrease in water dilutability.

[0020] The content of the amine compound in the phenol-formaldehyde resin composition is preferably 0.5 to 40 parts by mass, more preferably 5 to 25 parts by mass, per 100 parts by mass of the solids content of the resole-type phenol-formaldehyde resin. When the content of the amine compound is equal to or greater than the lower limit of the above range, the content of free formaldehyde in the resole-type phenol-formaldehyde resin tends to be reduced, and the amount of formaldehyde emitted from the aqueous binder tends to be sufficiently reduced. On the other hand, when the content of the amine compound is equal to or less than the upper limit of the above range, an aqueous binder tends to be obtained that is excellent in water dilutability and has a further reduced amount of ammonia emission. In this specification, the term "solid content" refers to the non-volatile content excluding volatile substances (water, organic solvents, etc.). The solid content concentration of the resol-type phenol-formaldehyde resin can be measured in accordance with the provisions of JIS K6910, 5.6. In this specification, free formaldehyde refers to unreacted formaldehyde measured in accordance with the provisions of JIS K6910, 5.17.

[0021] The method for producing an aqueous binder according to the present embodiment may further include a resin synthesis step of synthesizing a phenol-formaldehyde resin when the phenol-formaldehyde resin composition to be subjected to the acid addition step is a synthesized phenol-formaldehyde resin to which an amine compound has been added, or a phenol-formaldehyde resin containing an amine compound obtained by synthesizing a phenol-formaldehyde resin using a catalyst containing an amine compound.

[0022] [Resin synthesis step] In the resin synthesis step, a phenol and an aldehyde are reacted in the presence of an alkaline catalyst to synthesize a resol-type phenol-formaldehyde resin.

[0023] [[Synthesis of resol-type phenol-formaldehyde resin]] The method for synthesizing a resol-type phenol-formaldehyde resin by reacting a phenol with an aldehyde in the presence of an alkali catalyst is not particularly limited, and any known method can be used. For example, a method can be used in which a phenol, an aldehyde, an alkali catalyst, water, etc. are charged into a reaction vessel equipped with a stirrer, a reflux condenser, and a temperature control mechanism, and the reaction is maintained at a desired reaction temperature for a desired reaction time. After the start of the reaction, additional alkali catalyst and optional additives, etc., can be added as necessary.

[0024] Phenols are compounds having an aromatic ring and a hydroxyl group bonded to the aromatic ring. Examples of phenols include phenol, alkylphenols (o-, m-, and p-cresols, o-, m-, and p-ethylphenols, and xylenol isomers), polycyclic phenols (α- and β-naphthols, and the like), and polyhydric phenols (bisphenol A, bisphenol F, bisphenol S, pyrogallol, resorcinol, catechol, hydroquinone, and the like). Of these, the most practical compounds are phenol, o-, m-, and p-cresols, xylenol isomers, resorcinol, and catechol. The phenols may be used alone or in combination of two or more.

[0025] The aldehyde is at least one compound selected from the group consisting of compounds having a formyl group and polymers thereof. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, salicylaldehyde, glyoxal, etc. Among these, formaldehyde and paraformaldehyde are the most practical. The aldehydes may be used alone or in combination of two or more.

[0026] The molar ratio of aldehydes to phenols (aldehydes / phenols) is preferably 1.0 to 4.0, more preferably 1.5 to 2.5. When the molar ratio of aldehydes to phenols is equal to or greater than the lower limit of the above range, odor generation or a decrease in yield due to volatilization of unreacted phenols is easily suppressed. Furthermore, when the molar ratio of aldehydes to phenols is equal to or less than the upper limit of the above range, the residual amount of unreacted aldehydes is suppressed, and the risk of formaldehyde volatilizing in the working environment during the production process, which could harm the health of workers, is reduced. Furthermore, the amount of aldehydes emitted from the resulting inorganic fiber thermal and acoustical insulation material tends to be smaller.

[0027] The alkaline catalyst is not particularly limited as long as it can promote the reaction between phenols and aldehydes, and various alkaline substances can be used. Specific examples include inorganic alkaline substances such as hydroxides of alkali metals such as sodium and potassium (e.g., sodium hydroxide, potassium hydroxide), hydroxides of alkaline earth metals such as calcium, magnesium, and barium (e.g., calcium hydroxide, magnesium hydroxide, barium hydroxide), sodium carbonate, and ammonia; and organic alkaline substances such as tertiary amines such as triethylamine, trimethylamine, and triethanolamine, and cyclic amines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene). Generally, the use of alkaline earth metals results in lower water dilution and stability over time of the resin compared to the use of alkali metals, but improved water resistance. This is because alkaline earth metals and their salts have lower solubility in water than alkali metals. The alkali catalyst may be used alone or in combination of two or more kinds.

[0028] The amount of alkali catalyst used is preferably 1 to 30 parts by mass per 100 parts by mass of the phenols. When the amount of alkali catalyst used is equal to or greater than the lower limit of the above range, the reaction tends to proceed sufficiently, and when it is equal to or less than the upper limit of the above range, the reaction tends to be easily controlled.

[0029] The reaction temperature for the reaction between phenols and aldehydes is preferably 50 to 90° C., more preferably 60 to 80° C. When the reaction temperature is equal to or higher than the lower limit of the above range, a sufficient reaction rate tends to be obtained, and when the reaction temperature is equal to or lower than the upper limit of the above range, the reaction tends to be easily controlled. The reaction time can be set to, for example, 2 to 8 hours, since this makes it easier to control the molecular weight.

[0030] When a synthesized resol-type phenol-formaldehyde resin to which an amine compound has been added or a commercially available resol-type phenol-formaldehyde resin to which an amine compound has been added is used as the phenol-formaldehyde resin composition to be subjected to the acid addition step, the method for producing an aqueous binder of the present embodiment may further include an amine compound addition step of adding an amine compound to the resol-type phenol-formaldehyde resin.

[0031] [Amine compound addition step] In the amine compound addition step, an amine compound is added to the resole phenol formaldehyde resin. Examples of the amine compound include those described above in ((Amine Compound)).

[0032] When an amine compound is added after synthesizing the resol-type phenol-formaldehyde resin in the above-mentioned [Resin Synthesis Step], it is preferable to add the amine compound after lowering the temperature of the resol-type phenol-formaldehyde resin to less than 50° C. Adding the amine compound at a temperature less than 50° C. can prevent the free phenols and free aldehydes contained in the resol-type phenol-formaldehyde resin from reacting with the amine compound to form a condensation product, thereby making it possible to obtain an aqueous binder with excellent water-dilutability. In this specification, the free phenols and free aldehydes refer to unreacted phenols and aldehydes measured in accordance with the provisions of JIS K6910, 5.16 and 5.17, respectively.

[0033] The temperature of the resole phenol-formaldehyde resin when the amine compound is added is preferably less than 50° C., more preferably from 10 to 40° C., and even more preferably from 20 to 35° C. If the temperature of the resole phenol-formaldehyde resin when the amine compound is added is equal to or lower than the upper limit of the above range, an aqueous binder with excellent water dilutability tends to be obtained, whereas if the temperature is equal to or higher than the lower limit of the above range, the amine compound tends to be easily soluble in the resole phenol-formaldehyde resin, which reduces the heat of dissolution when the amine compound is added and makes temperature control easier.

[0034] The amount of the amine compound added is preferably 0.5 to 40 parts by mass, more preferably 5 to 25 parts by mass, per 100 parts by mass of the solids content of the resole phenol-formaldehyde resin. When the amount of the amine compound added is equal to or greater than the lower limit of the above range, the content of free formaldehyde in the resole phenol-formaldehyde resin tends to be reduced, and the amount of formaldehyde emitted from the aqueous binder tends to be sufficiently reduced. Furthermore, when the content of the amine compound is equal to or less than the upper limit of the above range, an aqueous binder that is excellent in water dilutability and has a further reduced amount of ammonia emitted tends to be obtained.

[0035] [Acid addition step] In the method for producing an aqueous binder according to this embodiment, an acid is added to a phenol-formaldehyde resin composition containing an amine compound in the acid addition step. This reduces the amount of ammonia gas emitted during the binder application process of producing an inorganic fiber thermal insulation sound-absorbing material, which is generated when the amine compound in the aqueous binder decomposes due to contact with high-temperature inorganic fibers or exposure to heat from the immediately preceding fiberization process. Furthermore, because an acid is used, discoloration (browning) of the inorganic fiber thermal insulation sound-absorbing material is almost nonexistent, compared to when a sugar compound is added to suppress the release of ammonia gas, and an inorganic fiber thermal insulation sound-absorbing material with a good hue can be obtained. Regarding the amount of acid added, if the amount is too large, the water dilutability of the resulting aqueous binder will decrease, resulting in the formation of precipitates, which may cause blockage of the binder delivery pipes or corrosion of the equipment, so the acid is added in such a range that the pH of the phenol-formaldehyde resin composition becomes 8.1 to 9.4 (the pH of the phenol-formaldehyde resin composition before the addition of the acid is about 9.7).The pH of the phenol-formaldehyde resin composition after the addition of the acid is preferably 8.3 to 9.2, more preferably 8.5 to 9.0, in order to more effectively reduce the amount of ammonia gas emitted. In the method for producing an aqueous binder according to the present embodiment, the pH of the phenol formaldehyde resin composition immediately after the addition of the acid in the acid addition step is approximately the same as the pH of the aqueous binder finally obtained.

[0036] The timing of the acid addition step is preferably immediately before using the binder, since adding an acid reduces the stability of the resol-type phenol-formaldehyde resin (binder) and shortens its pot life. Specifically, the acid addition step is preferably performed within 48 hours, more preferably within 24 hours, and even more preferably within 12 hours before using the binder. The acid is preferably added while stirring the phenol-formaldehyde resin composition in order to prevent a decrease in the water dilutability of the resin due to local over-neutralization. The temperature of the phenol formaldehyde resin composition when the acid is added is preferably less than 50°C, more preferably from 10 to 40°C, and even more preferably from 15 to 35°C.

[0037] (acid) The acid added in the acid addition step is not particularly limited as long as it does not impair the properties of the aqueous binder for use as an inorganic fiber thermal and acoustical insulation material, and examples thereof include inorganic acids such as sulfuric acid, boric acid, hydrochloric acid, nitric acid, phosphoric acid, and sulfamic acid, and organic acids such as formic acid, oxalic acid, acetic acid, citric acid, lactic acid, sulfanilic acid, benzoic acid, phenolsulfonic acid, paratoluenesulfonic acid, methanesulfonic acid, and lauric acid. From the viewpoints of cost and ease of use, sulfuric acid, phosphoric acid, citric acid, and lactic acid are preferred, and sulfuric acid is particularly preferred. The acids may be used alone or in combination of two or more.

[0038] [Water addition step] In the method for producing an aqueous binder according to the present embodiment, in the water addition step, water is added to the phenol formaldehyde resin composition to adjust the solid content concentration. Examples of water to be added in the water addition step include well water, tap water, distilled water, deionized water (ion-exchanged water), RO water, etc., and it is preferable that the water does not contain solids. From the viewpoints of cost and ease of use, well water, tap water, and distilled water are particularly preferred. The solids concentration after adding water to the phenol-formaldehyde resin composition, i.e., the solids concentration of the aqueous binder, is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and even more preferably 5 to 40% by mass. When the solids concentration of the aqueous binder is equal to or greater than the lower limit of the above range, the water content is appropriate, so the curing process does not take too long, and good productivity tends to be maintained. Furthermore, when the solids concentration of the aqueous binder is equal to or less than the upper limit of the above range, a decrease in the fluidity of the aqueous binder tends to be prevented. The solid content concentration of the aqueous binder (phenol formaldehyde resin composition) can be measured in accordance with the provisions of JIS K6910, 5.6.

[0039] [Addition of other ingredients] The method for producing an aqueous binder of this embodiment may further include an other component addition step of adding other components other than the resol-type phenol-formaldehyde resin and the amine compound, as long as the effects of the present invention are not impaired. The order of the other component addition step in the method for producing an aqueous binder of this embodiment is preferably after the acid addition step. For example, it may be after the acid addition step and before the water addition step, or it may be after the water addition step. The other components are added within a range that does not significantly change the pH adjusted in the acid addition step. The temperature of the phenol formaldehyde resin composition when other components are added is preferably less than 50°C, more preferably from 10 to 40°C, and even more preferably from 15 to 35°C.

[0040] The other components may be known components that are generally known to be blended into aqueous binders for inorganic fiber heat insulating and sound absorbing materials, such as curing accelerators, silane coupling agents, urea, known formaldehyde scavengers, water repellents (silicone-based water repellents, fluorine-based water repellents, etc.), dust suppressants (heavy oil water dispersions, etc.), rust inhibitors, colorants, and neutralizers for neutralizing alkaline components eluted from inorganic fibers such as glass. The other components may be one type alone or a combination of two or more types.

[0041] Examples of the hardening accelerator include ammonium salts such as ammonium sulfate, ammonium chloride, and ammonium phosphate. The amount of the curing accelerator added is preferably 0 to 10 parts by mass, and more preferably 3 to 6 parts by mass, per 100 parts by mass of the solid content of the resol type phenol formaldehyde resin.

[0042] The silane coupling agent is not particularly limited, and examples thereof include aminosilane coupling agents such as γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-(2-aminoethyl)aminopropylmethyldimethoxysilane; and epoxy silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldimethoxysilane. The amount of the silane coupling agent added is preferably 0 to 2 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of the solid content of the resol type phenol formaldehyde resin.

[0043] In the production of inorganic fiber heat-insulating and sound-absorbing materials, there is a problem of formaldehyde volatilizing from the aqueous binder during the process of applying the aqueous binder to the inorganic fibers, but by adding urea or a known formaldehyde scavenger, the free formaldehyde in the phenolic resin is captured by the urea, reducing the amount of free formaldehyde. This reduces the amount of formaldehyde volatilized during the production process, thereby improving the working environment. Known formaldehyde scavengers include, for example, the formaldehyde scavengers described in JP-A No. 2001-178805. In the following, the urea addition step of adding urea will be particularly described. A known formaldehyde scavenger can also be added in the same manner as in the urea addition step, and the preferred range of the amount to be added may be the same as the preferred range of the amount to be added of urea.

[0044] [[Urea addition step]] The urea addition step of adding urea to the phenol-formaldehyde resin composition is preferably carried out after the acid addition step and before the water addition step, from the viewpoint of efficiently neutralizing the acid of the amine compound in the phenol-formaldehyde resin composition and efficiently reacting the urea with free formaldehyde.

[0045] The amount of urea added is preferably 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, and even more preferably 20 to 70 parts by mass, per 100 parts by mass of the solids content of the resol-type phenol-formaldehyde resin. When the amount of urea added is at or above the lower limit of the above range, the content of free formaldehyde in the resol-type phenol-formaldehyde resin tends to be effectively reduced, and the amount of formaldehyde emitted from the aqueous binder tends to be effectively reduced. When the amount of urea added is at or below the upper limit of the above range, the aqueous binder tends to have excellent water dilutability, and the pH of the phenol-formaldehyde resin composition does not change significantly (outside the pH range of 8.1 to 9.4) (the pH of urea is approximately 9.0). Therefore, the pH of the phenol-formaldehyde resin composition immediately after adjusting the pH in the acid addition step is approximately the same as the pH of the final aqueous binder, and the amount of ammonia gas emitted from the aqueous binder tends to be effectively reduced.

[0046] [Water-based binder for inorganic fiber heat and sound absorbing materials] The aqueous binder for a thermal insulating sound-absorbing inorganic fiber material of this embodiment is an aqueous binder produced by the above-described method for producing an aqueous binder for a thermal insulating sound-absorbing inorganic fiber material of this embodiment. The aqueous binder of this embodiment is used to bind inorganic fibers such as glass wool, rock wool, and ceramic fibers in inorganic fiber products. The aqueous binder of the present embodiment contains a phenol-formaldehyde resin composition containing the above-described amine compound, an acid, and water for adjusting the concentration. If necessary, the aqueous binder may further contain other components such as urea, a curing accelerator, a silane coupling agent, a dust inhibitor, a rust inhibitor, a water repellent, or a colorant within a range that does not impair the effects of the present invention.

[0047] The pH of the aqueous binder is 8.1 to 9.4, preferably 8.3 to 9.2, and more preferably 8.5 to 9.0. When the pH of the aqueous binder is in the above range, the amount of ammonia gas emitted is effectively reduced, and the risk of clogging of binder delivery piping due to the formation of precipitates caused by a decrease in water dilution and acid corrosion of equipment is reduced. The pH of the aqueous binder is approximately the same as the pH of the phenol formaldehyde resin composition immediately after the acid is added in the acid addition step.

[0048] As described in the above-mentioned [Water Addition Step], the solids concentration of the aqueous binder is preferably 1 to 50% by mass, more preferably 5 to 45% by mass, and even more preferably 10 to 40% by mass. When the solids concentration of the aqueous binder is equal to or greater than the lower limit of the above range, the water content is appropriate, so the curing step does not take too long, and good productivity tends to be maintained. Furthermore, when the solids concentration of the aqueous binder is equal to or less than the upper limit of the above range, a decrease in the fluidity of the aqueous binder tends to be prevented.

[0049] The temperature of the aqueous binder before use is preferably less than 50°C, more preferably from 10 to 40°C, and even more preferably from 20 to 35°C.

[0050] [Manufacturing method for inorganic fiber heat and sound absorbing material] The thermal insulating sound absorbing inorganic fiber material of this embodiment can be obtained by applying the aqueous binder of this embodiment to inorganic fibers, and then heating and curing the aqueous binder to form the material. More specifically, for example, molten inorganic raw materials are fiberized in a fiberizing device, and immediately thereafter, an aqueous binder is applied to the inorganic fibers. The inorganic fibers with the aqueous binder applied are then piled (collected) on a perforated conveyor to form a bulky intermediate for an inorganic fiber thermal insulation sound-absorbing material. The intermediate is then fed to a pair of upper and lower perforated conveyors spaced apart to achieve the desired thickness, where it is heated under pressure to harden the aqueous binder and form the inorganic fiber thermal insulation sound-absorbing material. If necessary, a skin or other material is applied, and the resulting material is cut to the desired width and length to obtain the inorganic fiber thermal insulation sound-absorbing material.

[0051] Methods for applying an aqueous binder to inorganic fibers include coating or spraying using a spray device or the like. The timing for applying the aqueous binder to inorganic fibers may be after fiberization, and from the viewpoint of efficiently applying the aqueous binder, it is preferable to apply it immediately after fiberization. The amount of aqueous binder applied varies depending on the density and application of the inorganic fiber thermal insulation sound-absorbing material, but is preferably 0.5 to 30 mass% and more preferably 0.5 to 20 mass% in terms of solid content based on the mass of the inorganic fiber thermal insulation sound-absorbing material to which the aqueous binder has been applied.

[0052] An example of a method for heating inorganic fibers to which an aqueous binder has been applied is heating in a hot air oven. The heating temperature in the hot air oven can be, for example, 200 to 350°C. When the heating temperature is equal to or higher than the lower limit of the above range, the curing of the aqueous binder tends to proceed sufficiently, and the amount of formaldehyde emitted tends to be sufficiently reduced. When the heating temperature is equal to or lower than the upper limit of the above range, the aqueous binder tends to be less likely to decompose, and a decrease in yield and a decrease in mechanical strength tend to be suppressed. The heat curing time can be appropriately adjusted between 30 seconds and 10 minutes depending on the density and thickness of the inorganic fiber heat-insulating acoustic absorber.

[0053] [Inorganic fiber heat and sound absorbing material] The thermal insulating inorganic fiber sound-absorbing material of this embodiment includes inorganic fibers and a cured product of the aqueous binder for the thermal insulating inorganic fiber sound-absorbing material of this embodiment, which fixes (holds) the inorganic fibers. That is, the thermal insulating inorganic fiber sound-absorbing material can be obtained by applying the aqueous binder to inorganic fibers and then heating and curing the aqueous binder to form it. The inorganic fiber is not particularly limited, and glass wool, rock wool, etc., which are used in ordinary heat-insulating sound-absorbing materials, can be used. The inorganic fiber can be made into a fiber by various methods, such as the flame method, the blowing method, and the centrifugal method (rotary method). When the inorganic fiber is glass wool, it is preferable to use the centrifugal method. The thermal insulating sound absorbing inorganic fiber material may be used as it is, or may be covered with a skin material such as paper, synthetic resin film, metal foil film, nonwoven fabric, woven fabric, or a combination thereof. The density of the inorganic fiber heat insulating and sound absorbing material may be the density used for ordinary heat insulating and sound absorbing materials, and is preferably 5 to 300 kg / m 3 is. [Example]

[0054] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples as long as it does not depart from the gist of the present invention.

[0055] The measurement and evaluation methods used are as follows:

[0056] [Ammonia emission rate] (1) Laboratory evaluation 10 g of aqueous binder (solid content: 40% by mass) was placed in a 20 mL glass bottle and placed in a 250 mL plastic container without a lid. Next, 10 mL of 20 mmol / L methanesulfonic acid solution was placed in another 20 mL glass bottle and placed in the plastic container without a lid. The plastic container was closed and heated at 80°C for 10 minutes to dissolve the ammonia generated from the aqueous binder in the methanesulfonic acid solution. After the heating was completed, the glass bottle containing the aqueous methanesulfonic acid solution was removed from the plastic container and the lid was immediately closed. The amount of ammonia dissolved in the methanesulfonic acid aqueous solution was determined by ion chromatography under the following measurement conditions. The measurement was performed twice, and the average value was used as the measured value. In Table 1, the measurement results are shown as relative values, with the measurement value of Comparative Example 1 taken as 100. -Measurement conditions- Apparatus: Dionex Aquion (Thermo Fisher Scientific) Column: Dionex IonPac CS12A (Thermo Fisher Scientific) Eluent: 20mmol / L methanesulfonic acid aqueous solution Detector: Electrical conductivity detector Flow rate: 1.0mL / min Injection volume: 25μL Standard solution for calibration curve: 1000 mg / L ammonium ion standard solution (Kanto Chemical Co., Ltd.) (2) Actual machine evaluation Density 64kg / m 3 A glass wool heat insulating sound absorbing material with an aqueous binder deposition rate of 6.0 mass% was manufactured, and the concentration (ppm by volume) of ammonia gas emitted from the aqueous binder during the aqueous binder application process was measured using an ammonia detector tube under the following measurement conditions. The measurement was carried out by using the detector tube to suck in the exhaust gas generated during the aqueous binder application process from inside a duct that sends the gas from the binder application process to the exhaust gas treatment equipment. The measurement was carried out three times, and the average value was used as the measured value. In Table 2, the measurement results are shown as relative values, with the measurement value of Comparative Example 1 taken as 100. -Measurement conditions- Detector tube: Ammonia No. 3La (manufactured by Gastec Corporation) Suction volume: 100mL

[0057] [pH] The pH of the phenol formaldehyde resin composition and the aqueous binder was measured using a pH meter "F-74" (manufactured by Horiba, Ltd.) in accordance with the provisions of 5.4 of JIS K6910:2007.

[0058] [Example 1] As a phenol-formaldehyde resin composition containing an amine compound, "PL-7740" (manufactured by Gunei Chemical Industry Co., Ltd.) was used, in which triethylamine was used as the amine catalyst during resin synthesis and monoethanolamine was added as an amine compound other than the catalyst. Sulfuric acid was added to a phenol formaldehyde resin composition (23° C.) and stirred to adjust the pH to 9.3. Next, urea, ammonium sulfate, and aminosilane were added and mixed in this order so that the ratios of urea, ammonium sulfate, and aminosilane to 60 parts by mass of the solid content of the phenol-formaldehyde resin composition (23°C) were 40 parts by mass, 3.5 parts by mass, and 0.2 parts by mass of aminosilane, and then distilled water was added to adjust the concentration so that the solid content concentration was 40% by mass, thereby obtaining an aqueous binder. Table 1 shows the ammonia emission amount (laboratory evaluation) and pH measurement results for the obtained aqueous binder.

[0059] [Examples 2 to 10] Aqueous binders were obtained in the same manner as in Example 1, except that the type and amount of acid and the amount of each component added were changed as shown in Table 1. Table 1 shows the measurement results of the pH and ammonia emission amount (laboratory evaluation) of the obtained aqueous binder.

[0060] [Comparative Example 1] An aqueous binder was obtained in the same manner as in Example 1, except that sulfuric acid was not added. Table 1 shows the measurement results of the pH and ammonia emission amount (laboratory evaluation) of the obtained aqueous binder.

[0061] [Examples 11 and 12] Aqueous binders were obtained in the same manner as in Example 1, except that the amount of acid added was changed as shown in Table 2 and well water was used instead of distilled water. Table 2 shows the measurement results of the pH and ammonia emission amount (evaluated using an actual machine) of the obtained aqueous binder.

[0062] Comparative Example 2 An aqueous binder was obtained in the same manner as in Comparative Example 1, except that well water was used instead of distilled water. Table 2 shows the measurement results of the pH and ammonia emission amount (evaluated using an actual machine) of the obtained aqueous binder.

[0063] [Table 1]

[0064] [Table 2] [Industrial Applicability]

[0065] According to the method for producing an aqueous binder for an inorganic fiber thermal insulating sound-absorbing material of the present invention, it is possible to obtain an aqueous binder that effectively reduces the amount of ammonia gas emitted during the production of an inorganic fiber thermal insulating sound-absorbing material, and the aqueous binder can be suitably used for the production of an inorganic fiber thermal insulating sound-absorbing material.

Claims

1. A method for producing an aqueous binder for inorganic fiber thermal and acoustic insulation materials, an acid addition step of adding an acid to a phenol-formaldehyde resin composition containing a resol-type phenol-formaldehyde resin and an amine compound; a water addition step of adding water to adjust the solid content concentration after the acid addition step; Including, The aqueous binder for inorganic fiber heat and sound absorbing material has a pH of 8.1 to 9.

4. A method for producing an aqueous binder for an inorganic fiber heat and sound absorbing material, comprising:

2. 2. The method for producing an aqueous binder for a thermal insulating and acoustical inorganic fiber material according to claim 1, wherein the resol-type phenol-formaldehyde resin is a resol-type phenol-formaldehyde resin synthesized by reacting a phenol with a formaldehyde using a catalyst containing triethylamine.

3. 2. The method for producing an aqueous binder for a thermal insulating and acoustical inorganic fiber material according to claim 1, wherein the amine compound contains an amine compound other than an amine compound contained in a catalyst used in synthesizing the resol-type phenol-formaldehyde resin.

4. The method for producing an aqueous binder for a thermal and acoustical inorganic fiber material according to claim 3, wherein the amine compound other than the amine compound contained in the catalyst is monoethanolamine.

5. The method for producing an aqueous binder for a thermal and acoustical inorganic fiber material according to claim 1, wherein the acid is sulfuric acid.

6. The method for producing an aqueous binder for an inorganic fiber thermal and acoustical absorbing material according to claim 1, further comprising a urea addition step of adding urea after the acid addition step and before the water addition step.

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