Polyurethane foam, vehicle components, and sound-absorbing materials

Abstract

To provide a polyurethane foam that holds superior properties and offers superior sound absorbing performance.SOLUTION: A polyurethane foam 10 is obtained from a composition that includes polyols and polyisocyanate. The polyols include polyether polyols with the content of ethylene oxide units being 25 mass% or more. The content of the polyether polyols is 10 pts.mass or more and 50 pts.mass or less when the total content of the polyols is 100 pts.mass. The average number of functional groups of the total polyols is 3.8 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to polyurethane foam, vehicle components, and sound-absorbing materials. [Background technology]

[0002] Patent Document 1 discloses a rigid polyurethane foam consisting of two layers: a low-density layer and a high-density layer. The foam-forming composition of this rigid polyurethane foam is described to contain an alkanolamine as a polyol component. Furthermore, in Examples 2 and 4 of the rigid polyurethane foam, it is shown that the composition contains 5.0 parts by mass of polyol a3-1 with an ethylene oxide unit content of 68% per 110 parts by mass of total polyol.

[0003] Patent Document 2 discloses a sound-absorbing and shock-absorbing material made of rigid polyisocyanurate foam that has excellent sound absorption and shock absorption capabilities. As an example of rigid polyisocyanurate foam, a formulation is shown in which 100 parts of a hydroxyl-terminated prepolymer with a hydroxyl value of 31 mg KOH / g, consisting of a polyether polyol with an average molecular weight of 3600, 3 functional groups, and a polyoxyethylene content of 80%, and toluene diisocyanate, and 30 parts of a polyol with a polyoxyethylene content of 0% and a hydroxyl value of 56 mg KOH / g are combined. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-272806 [Patent Document 2] Japanese Patent Publication No. 2013-047338 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] There is a need for technology to improve the sound absorption performance of polyurethane foam. However, while a skin layer such as the high-density layer described in Patent Document 1 contributes to improving the strength of rigid polyurethane foam, there are concerns that it may also worsen the sound absorption performance. In the field of rigid polyurethane foam, secondary processing is currently performed to expose a low-density layer on the surface in order to obtain excellent sound absorption performance. Furthermore, rigid polyisocyanurate foam generally has poor moldability and presents challenges such as poor fluidity during mold molding. The purpose of this disclosure is to provide a polyurethane foam that maintains good physical properties and has excellent sound absorption performance even without secondary processing. This disclosure can be implemented in the following forms: [Means for solving the problem]

[0006] A polyurethane foam obtained from a composition containing a polyol and a polyisocyanate, The polyol includes a polyether polyol having an ethylene oxide unit content of 25% by mass or more. The content of the polyether polyol is 15 parts by mass or more and 50 parts by mass or less when the total amount of the polyol is 100 parts by mass. A polyurethane foam having an average number of functional groups of 3.8 or more in the entire polyol. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a polyurethane foam that maintains good physical properties and has excellent sound absorption performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a cross-section of polyurethane foam. [Modes for carrying out the invention]

[0009] Herein lies a preferred example of this disclosure. · Polyurethane foam with a density of 30 kg / m or more. · A vehicle member including the above polyurethane foam. · A sound absorbing material including the above polyurethane foam.

[0010] Hereinafter, the present disclosure will be described in detail. In this specification, for a description using "-" for a numerical range, unless otherwise specified, the lower limit value and the upper limit value are included. For example, in the description of "10 - 20", both the lower limit value "10" and the upper limit value "20" are included. That is, "10 - 20" has the same meaning as "10 or more and 20 or less".

[0011] 1. Polyurethane foam 10 The polyurethane foam 10 is a polyurethane foam obtained from a composition containing a polyol and a polyisocyanate. The polyol includes a polyether polyol having an ethylene oxide unit content of 25% by mass or more. When the total amount of the polyol is 100 parts by mass, the content of the polyether polyol is 15 parts by mass or more and 50 parts by mass or less. The average functionality of the total polyol is 3.8 or more.

[0012] The composition contains a polyol and an isocyanate. The composition may optionally contain at least one selected from a foaming agent, a catalyst, and a foam stabilizer as an optional component. Each component of the composition will be described.

[0013] (1) Polyol The polyol includes a polyether polyol (a) having an ethylene oxide unit content of 25% by mass or more. Only one kind of the polyether polyol (a) may be used, or two or more kinds may be used in combination. In the polyol of the present disclosure, the content of the ethylene oxide unit is expressed as the content of the ethylene oxide unit when the total amount of the alkylene oxide units is 100% by mass. Examples of other alkylene oxide units excluding the ethylene oxide unit include a propylene oxide unit, a butylene oxide unit, and the like.

[0014] Furthermore, the polyol includes other polyols besides polyether polyol (a). The other polyols are not particularly limited as long as they have an ethylene oxide unit content of less than 25% by mass (they do not need to contain ethylene oxide units). Examples of other polyols that can be used include polyether polyols with an ethylene oxide unit content of less than 25% by mass, polymer polyols with an ethylene oxide unit content of less than 25% by mass, polyester polyols, etc. From the viewpoint of various physical properties such as shock absorption, the other polyol is preferably a polyether polyol with an ethylene oxide unit content of less than 25% by mass. Only one type of other polyol may be used, or two or more types may be used in combination. After describing polyether polyol (a), polyether polyol (b) and polyether polyol (c) will be described as polyether polyols with an ethylene oxide unit content of less than 25% by mass.

[0015] (1.1) Polyether polyol (a) Examples of polyether polyols (a) include polyether polyols obtained by adding one or more of the following initiators (compounds) to one or more of the following: ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, epichlorohydrin, styrene oxide, etc.

[0016] (1.1.1) Initiator (1.1.1.1) Polyhydric alcohols and alkylene oxide adducts of polyhydric alcohols Examples of polyhydric alcohols: [Difunctional alcohols] Ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, trimethylene glycol [Trifunctional alcohols] Glycerin, Trimethylolpropane [4-functional alcohol] Pentaerythritol [6-functional alcohol] Sorbitol [8. Functional alcohols] Sucrose (1.1.1.2) Alkylene oxide adducts of polyhydric phenols Examples of alkylene oxide adducts of polyhydric phenols: Alkylene oxide adduct of bisphenol A (1.1.1.3) Polyhydric hydroxy compounds Examples of polyhydric hydroxy compounds: phosphate, benzenephosphate, polyphosphate (e.g., tripolyphosphate and tetrapolyphosphate), etc. (1.1.1.4) Phenol-aniline-formaldehyde ternary condensation product (1.1.1.5) Aniline-formaldehyde condensation product (1.1.1.6) Polyamines Examples of polyamines: ethylenediamine, diethylenetriamine, triethylenetetramine, methylenebisorthochloraniline, 4,4- and 2,4'-diphenylmethanediamine, 2,4-tolylenediamine, 2,6-tolylenediamine, etc. (1.1.1.7) Alkanolamines Examples of alkanolamines: triethanolamine, diethanolamine, etc.

[0017] The polyether polyol (a) is preferably an adduct of ethylene oxide and propylene oxide, and more preferably a random copolymer of propylene oxide and ethylene oxide.

[0018] From the viewpoint of improving sound absorption, the content of ethylene oxide units in polyether polyol (a) is 25% by mass or more, preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. From the viewpoint of moldability, the content of ethylene oxide units is 100% by mass or less, preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. From these viewpoints, the content of ethylene oxide units is 25% by mass or more and 100% by mass or less, preferably 40% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 85% by mass or less, and even more preferably 70% by mass or more and 80% by mass or less.

[0019] The number-average molecular weight of polyether polyol (a) is not particularly limited. The number-average molecular weight of polyether polyol (a) is preferably 20,000 or less, more preferably 15,000 or less, even more preferably 10,000 or less, even more preferably 7,000 or less, and even more preferably 5,000 or less. The lower limit of the number-average molecular weight of polyether polyol (a) is usually 1,000 or more, but may be 2,000 or more, or 2,500 or more. The number-average molecular weight of polyether polyol (a) can be measured by gel permeation chromatography (GPC). If polyether polyol (a) is a commercially available product, the catalog value may be used as the number-average molecular weight of polyether polyol (a). The same method can be used to specify the number-average molecular weight of other polyols, as described later.

[0020] The number of functional groups in polyether polyol (a) is not particularly limited, as long as it satisfies the requirement of the average number of functional groups in the polyol as described below. The number of functional groups in polyether polyol (a) is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3. The number of functional groups in polyether polyol (a) is usually 2 or more, preferably 2.5 or more. The number of functional groups in polyether polyol (a) refers to the average number of active hydrogen groups present in each component of polyether polyol (a). If polyether polyol (a) is a commercially available product, the catalog value may be used as the number of functional groups in polyether polyol (a). The same definition can be applied to other polyols, as described later.

[0021] From the viewpoint of sound absorption, the content of polyether polyol (a) is 10 parts by mass or more, preferably 15 parts by mass or more, more preferably 18 parts by mass or more, and even more preferably 20 parts by mass or more, when the total polyol is 100 parts by mass. From the viewpoint of moldability, the content of polyether polyol (a) is 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less. From these viewpoints, the content of polyether polyol (a) is 10 parts by mass or more and 50 parts by mass or less, preferably 15 parts by mass or more and 40 parts by mass or less, more preferably 18 parts by mass or more and 35 parts by mass or less, and even more preferably 20 parts by mass or more and 30 parts by mass or less.

[0022] (1.2) Polyether polyol (b) Examples of polyether polyol (b) include polyether polyols obtained by adding one or more of the above-mentioned initiators (compounds) to one or more of the following: ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, epichlorohydrin, styrene oxide, etc. Polyether polyol (b) is preferably an adduct of ethylene oxide and propylene oxide, and more preferably a propylene oxide-ethylene oxide copolymer obtained by addition polymerization of propylene oxide and then addition polymerization of ethylene oxide.

[0023] The ethylene oxide unit content of polyether polyol (b) is not particularly limited. For example, the ethylene oxide unit content of polyether polyol (b) is preferably more than 0% by mass, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit of the ethylene oxide unit content of polyether polyol (b) is not particularly limited and may be less than 25% by mass, for example, 23% by mass or less, or 20% by mass or less.

[0024] The number-average molecular weight of polyether polyol (b) is not particularly limited. The number-average molecular weight of polyether polyol (b) is preferably 20,000 or less, more preferably 15,000 or less, even more preferably 10,000 or less, even more preferably 7,000 or less, and even more preferably 5,000 or less. The lower limit of the number-average molecular weight of polyether polyol (b) is usually 1,000 or more, but may be 2,000 or more, or 2,500 or more.

[0025] The number of functional groups in polyether polyol (b) is not particularly limited, as long as it satisfies the requirement of the average number of functional groups in the polyol as described below. The number of functional groups in polyether polyol (b) is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3. The number of functional groups in polyether polyol (b) is usually 2 or more, preferably 2.5 or more.

[0026] The content of polyether polyol (b) is not particularly limited. From the viewpoint of shock absorption, the content of polyether polyol (b) is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, when the total polyol is 100 parts by mass. From the viewpoint of ensuring sound absorption by ensuring a sufficient amount of polyether polyol (a), the content of polyether polyol (b) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less. From these viewpoints, the content of polyether polyol (b) is preferably 15 parts by mass or more and 70 parts by mass or less, more preferably 20 parts by mass or more and 60 parts by mass or less, and even more preferably 25 parts by mass or more and 55 parts by mass or less.

[0027] (1.3) Polyether polyol (c) Examples of polyether polyols (c) include polyether polyols obtained by adding one or more of the above-mentioned initiators (compounds) to one or more of the following: ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, epichlorohydrin, styrene oxide, etc. From the viewpoint of ensuring the average number of functional groups in the entire polyol, polyether polyol (c) preferably contains a polyether polyol using an initiator with 5 or more functionalities, and preferably contains a polyether polyol using sucrose.

[0028] The ethylene oxide unit content of the polyether polyol (c) is not particularly limited, as long as it is less than 25% by mass. The number-average molecular weight of polyether polyol(c) is not particularly limited. Preferably, the number-average molecular weight of polyether polyol(c) is 2000 or less, more preferably 1500 or less, even more preferably 1000 or less, and particularly preferably 800 or less. The lower limit of the number-average molecular weight of polyether polyol(c) is not particularly limited and may be 400 or more, or 500 or more.

[0029] The number of functional groups in polyether polyol (c) is not particularly limited, as long as it satisfies the requirement of the average number of functional groups in the polyol as described below. The number of functional groups in polyether polyol (c) is preferably 4 or more, more preferably 4.5 or more, and even more preferably 5 or more. The number of functional groups in polyether polyol (c) is usually 8 or less, and may be, for example, 7 or less, or 6 or less.

[0030] The content of polyether polyol (c) is not particularly limited. From the viewpoint of obtaining shock absorption, the content of polyether polyol (c) is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more, when the total polyol is 100 parts by mass. From the viewpoint of ensuring sound absorption by ensuring a sufficient amount of polyether polyol (a), the content of polyether polyol (b) is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less. From these viewpoints, the content of polyether polyol (c) is preferably 20 parts by mass or more and 50 parts by mass or less, more preferably 25 parts by mass or more and 45 parts by mass or less, and even more preferably 30 parts by mass or more and 40 parts by mass or less.

[0031] (1.4) Other polyols The polyol may include other polyols as long as they do not impair the effects of the invention. Examples of other polyols include polyhydric alcohols such as glycerin, ethylene glycol, propylene glycol, butanediol, butylene glycol, trimethylolpropane, etc. One or more of these other polyols may be used.

[0032] (1.5) Average number of functional groups in the entire polyol The average functionality of the entire polyol is 3.8 or more, preferably 4.0 or more, and more preferably 4.5 or more, from the viewpoint of maintaining various physical properties such as shock absorbency. The upper limit of the average functionality of the entire polyol is not particularly limited. The average functionality of the entire polyol is usually 8.0 or less, and may be, for example, 7.0 or less, 6.0 or less, or 5.0 or less. The average functionality of the entire polyol is calculated from the functionality of each polyol contained in the entire polyol and the molar fraction of each polyol. For example, when three types of polyols, polyol (a), polyol (b), and polyol (c), are used as the polyol, the average functionality of the entire polyol can be determined by the following formula.

Equation

[0033] (1.5) Content of ethylene oxide units in the entire polyol The content of ethylene oxide units in the entire polyol contained in the composition is not particularly limited. The content of ethylene oxide units in the entire polyol is preferably 10% by mass or more and 45% by mass or less, more preferably 15% by mass or more and 35% by mass or less, and still more preferably 20% by mass or more and 30% by mass or less.

[0034] (1.6) Ratio of polyether polyol (a) to polyether polyol (b) When the polyol contains polyether polyol (a) and polyether polyol (b), the ratio (mass ratio) of polyether polyol (a) to polyether polyol (b) is not particularly limited. From the viewpoint of sound absorption and shock absorption, the ratio of polyether polyol (a) to polyether polyol (b) is preferably 60:40-20:80 (mass ratio), more preferably 50:50-25:75 (mass ratio), and even more preferably 40:60-30:70 (mass ratio).

[0035] (2) Foaming agent The composition may contain a blowing agent. The blowing agent is not particularly limited. Examples of blowing agents include water, hydrohaloolefins such as hydrofluoroolefins (HFOs), alkylene chlorides such as methylene chloride and ethylene chloride, and C4-C8 alkanes such as isopentane. Among these, water is preferred because it preferably forms cells that communicate with the skin layer and improves sound absorption. These may be used alone or in mixtures of two or more. The content of the blowing agent is not particularly limited. From the viewpoint of ensuring sound absorption and various physical properties, the content of the blowing agent is preferably 1 to 10 parts by mass, more preferably 3 to 8 parts by mass, per 100 parts by mass of polyol.

[0036] (3) Catalyst The composition may contain a catalyst. The catalyst is not particularly limited. Various catalysts may be used individually or in combination of two or more. Examples of catalysts include foaming catalysts, resinification catalysts, catalysts that can promote both foaming and resinification (balanced catalysts), and trimerization catalysts that promote the trimerization reaction of isocyanate groups.

[0037] Examples of foaming catalysts include tertiary amines or their organic salts such as bis(2-dimethylaminoethyl) ether, N,N-dimethylaminoethoxyethanol, and N,N,N',N',N''-pentamethyldiethylenetriamine, as well as morpholine compounds and piperazine compounds. One or more of these can be used. Examples of resinification catalysts include N,N-dimethylaminohexanol, tertiary amines or their organic acid salts, organometallic compounds, etc., and one or more of these can be used. Examples of balanced catalysts include aliphatic amines such as methyldicyclohexylamine, and one or more of these can be used. Examples of trimerization catalysts include tertiary amines such as 1,3,5-tris(dimethylaminopropyl)hexahydro-s-triazine, quaternary ammonium salts such as triethylmethylammonium 2-ethylhexanoate, metal oxides, alkoxides, organometallic salts, nitrogen-containing heterocyclic compounds, etc., and one or more of these can be used. Among these, the use of N,N-dimethylaminoethoxyethanol is preferred from the viewpoint of VOC reduction, and the combination of N,N-dimethylaminoethoxyethanol with bis(2-dimethylaminoethyl) ether or N,N,N',N',N''-pentamethyldiethylenetriamine is more preferred. Commercially available catalysts may be used. Examples of commercially available catalysts include Luplagen N301 (foaming catalyst), Luplagen N206 (foaming catalyst), Luplagen N107 (foaming catalyst), Kaolizer No. 25 (resin-forming catalyst), Polycat 12 (balancing catalyst), Polycat 55 (balancing catalyst), Luplagen N600 (trimerization catalyst), Ucat 18X (trimerization catalyst), TOYOCAT TR20 (trimerization catalyst), and TOYOCAT TRX (trimerization catalyst). The catalyst content is preferably 0.1 parts by mass or more and 15 parts by mass or less per 100 parts by mass of polyol, and more preferably 0.5 parts by mass or more and 10 parts by mass or less.

[0038] (4) Foam stabilizer The composition may contain a foam stabilizer. The foam stabilizer is not particularly limited. Examples of foam stabilizers include silicone-based foam stabilizers and fluorine-containing compound-based foam stabilizers. Examples of silicone-based foam stabilizers include polyether-modified silicones such as copolymers of dimethylpolysiloxane and polyether. The foam stabilizer may be used alone or in combination of two or more types.

[0039] The foam stabilizer preferably contains one or more selected from "foam stabilizers for flexible polyurethane foam" and "foam stabilizers for HR (High Resilience) molded foam." Compared to "foam stabilizers for rigid polyurethane foam," "foam stabilizers for flexible polyurethane foam" and "foam stabilizers for HR molded foam" have superior cell openness (foam breaking properties). Therefore, it is presumed that by using them in combination with the polyol (a) described above, openings such as cells communicating with the skin layer of the polyurethane foam 10 are formed, contributing to improved sound absorption. From the viewpoint of improving sound absorption in the high-frequency range (for example, frequencies of 2000 Hz or higher), it is more preferable that the foam stabilizer be a combination of one or more "foam stabilizers for flexible polyurethane foam" and one or more "foam stabilizers for HR molded foam." Examples of "foam stabilizers for flexible polyurethane foam" include polyether-modified silicones modified with polyethers containing propylene oxide units, and polyether-modified silicones in which the ends of modified polyethers are capped with alkoxy groups, etc. Examples of commercially available "foam stabilizers for flexible polyurethane foam" include VORASURF SF1280A and VORASURF SZ1136 from Toray Dow Corning, and Niax Silicone L895, Niax Silicone L858, Niax Silicone L838, and Niax Silicone L3636LF from Momentive. Polyether-modified silicones with relatively small molecular weights are widely used as "foam stabilizers for HR mold foam." The kinematic viscosity (in accordance with JIS Z8803:2011) of the "foam stabilizer for HR mold foam" used in the polyurethane foam of this disclosure is preferably 1000 mm². 2 / s (25℃) or less, more preferably 500mm 2 The temperature is 25°C or less, and more preferably 300 mm 2 The kinematic viscosity of the above-mentioned "Foam stabilizer for HR mold foam" is typically 10 mm². 2 The temperature is 25°C or higher. Examples of commercially available "HR mold foam stabilizers" include VORASURF SF2962A, SF2965, SF2973, SF2961, SRX253, TF1348, and TF1365 from Toray Dow Corning.

[0040] The foam stabilizer content is preferably 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polyol, and more preferably 0.5 parts by mass or more and 8 parts by mass or less. When the "Foam stabilizer for flexible polyurethane foam" and the "Foam stabilizer for HR molded foam" are used in combination, the mass ratio of the "Foam stabilizer for flexible polyurethane foam" to the "Foam stabilizer for HR molded foam" is not particularly limited. From the viewpoint of sound absorption and shock absorption, the mass ratio of the "Foam stabilizer for flexible polyurethane foam" to the "Foam stabilizer for HR molded foam" is preferably 20:80-40:60, and more preferably 25:75-35:65.

[0041] (5) Isocyanates The isocyanate is not particularly limited. Aromatic isocyanates, aliphatic isocyanates, mixtures thereof, and modified polyisocyanates obtained by modifying them can be used. Examples of aromatic isocyanates include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, xylylene diisocyanate, and polymeric MDI. Examples of aliphatic polyisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexamethane diisocyanate. Other prepolymers can also be used.

[0042] Polymeric MDI is preferred as the isocyanate. Polymeric MDI is polyphenylene polymethylene polyisocyanate, and is, for example, a mixture of dinuclear MDI and polynuclear MDI with three or more nuclei. Polymeric MDI may be untreated crude MDI obtained by an MDI synthesis reaction, or it may be prepared by separating a desired amount of monomeric MDI from the above crude MDI by vacuum distillation or the like to adjust the composition.

[0043] From the viewpoint of moldability, the isocyanate index (INDEX) is preferably 80-140, and more preferably 90-120. The isocyanate index is calculated by dividing the number of moles of isocyanate groups in the isocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups in the polyol and water as a blowing agent, and multiplying the result by 100, and is calculated as [NCO equivalent of isocyanate / active hydrogen equivalent × 100].

[0044] (6) Other ingredients The composition may contain other components in addition to those listed above. Other components that can be added include, for example, flame retardants, plasticizers, colorants, antioxidants, UV absorbers, antibacterial agents, tackifiers, compatibilizers, and other known additives. Examples of flame retardants include phosphate ester compounds such as tris(chloropropyl) phosphate, triethyl phosphate, and tricresyl phosphate; phosphorus compounds such as red phosphorus and ammonium polyphosphate; melamine compounds; metal hydrates; and antimony compounds. The amount of flame retardant is preferably 1 to 20 parts by mass, and more preferably 5 to 15 parts by mass, per 100 parts by mass of polyol.

[0045] 2. Method for manufacturing polyurethane foam 10 Polyurethane foam 10 can be manufactured using methods such as the prepolymer method or the one-shot method. The prepolymer method involves pre-reacting a polyol with an isocyanate to obtain a urethane prepolymer having isocyanate or hydroxyl groups at its ends, and then using this urethane prepolymer to obtain the polyurethane foam 10. The one-shot method involves charging a polyol and an isocyanate all at once and reacting them.

[0046] For the manufacture of polyurethane foam 10, known methods in the molding process, which involves molding in a mold, can be applied. Specifically, the composition (foaming base liquid) is injected into a sealed mold, a urethane reaction is carried out, and after curing, the foam is demolded to obtain polyurethane foam.

[0047] 3. Physical properties of polyurethane foam 10 The polyurethane foam 10 may be rigid polyurethane foam, semi-rigid polyurethane foam, or flexible polyurethane foam. From the viewpoint of shock absorption, the polyurethane foam 10 is preferably rigid polyurethane foam or semi-rigid polyurethane foam.

[0048] The apparent total density of polyurethane foam 10 (according to JIS K7222:2005) is 30 kg / m³. 3 The above is preferable, and 40 kg / m 3 The above is more preferable: 50 kg / m 3 The above is even more preferable. The upper limit of the apparent overall density of the polyurethane foam 10 is not particularly limited, for example, 500 kg / m³ 3 The following is possible, and from the viewpoint of sound absorption and weight reduction, 300 kg / m 3 Below 200kg / m 3 Below 100kg / m 3 Below 80kg / m 3 Below 65kg / m 3 The following may also be used. Note that, separate from the examples described later, a density of 250 kg / m³ is used. 3 We have confirmed that the desired sound absorption performance can be obtained even with polyurethane foam.

[0049] The polyurethane foam 10 preferably has a sound absorption coefficient of 0.10 or higher, measured in accordance with JIS A1405-2:2007 at a test specimen thickness of 15 mm and a frequency of 500 Hz. The polyurethane foam 10 preferably has a sound absorption coefficient of 0.35 or higher, measured in accordance with JIS A1405-2:2007 at a test specimen thickness of 15 mm and a frequency of 1000 Hz. The polyurethane foam 10 preferably has a sound absorption coefficient of 0.78 or higher, measured in accordance with JIS A1405-2:2007 at a test specimen thickness of 15 mm and a frequency of 2000 Hz. The polyurethane foam 10 preferably has a sound absorption coefficient of 0.84 or higher, measured in accordance with JIS A1405-2:2007 at a test specimen thickness of 15 mm and a frequency of 2500 Hz. The polyurethane foam 10 preferably has a sound absorption coefficient of 0.76 or higher, measured in accordance with JIS A1405-2:2007 at a test specimen thickness of 15 mm and a frequency of 3150 Hz. The polyurethane foam 10 is more preferably satisfied with two or more of the requirements for preferred sound absorption coefficients at the above frequencies of 500Hz, 1000Hz, 2000Hz, 2500Hz, and 3150Hz, even more preferably with three or more of the requirements, four or more of the requirements, and particularly preferably with five of the requirements. The sound absorption coefficient is measured using a test specimen with a skin layer, with the surface of the skin layer used as the reference plane. The upper limit of the sound absorption coefficient at each of the above frequencies is not particularly limited, but is 1 or less. The satisfaction of each requirement for a desirable sound absorption coefficient can be controlled by changing the blending ratio of each polyol, the type and amount of catalyst, the type and amount of foam stabilizer, the isocyanate index, etc.

[0050] According to measurements in accordance with JIS K7220:2006, the maximum force (maximum load) at which the polyurethane foam 10 reaches a deformation rate of 10% or less is preferably between 120N and 400N, and more preferably between 180N and 300N, from the viewpoint of shock absorption. The maximum load of the polyurethane foam 10 was measured using a 50mm x 50mm x 30mm thick test piece cut from the core of the polyurethane foam 10. The maximum load of the polyurethane foam 10 can be controlled by changing the blending ratio of each polyol, the type and amount of catalyst, the type and amount of foam stabilizer, the isocyanate index, etc.

[0051] 4. Operation and Effects of this Embodiment The polyurethane foam 10 of this embodiment maintains good physical properties and has excellent sound absorption performance. Examples of these physical properties include shock absorption, low VOC value, and low odor.

[0052] The reason why the polyurethane foam 10 of this embodiment maintains good physical properties and has excellent sound absorption performance is not clear, but it is presumed to be as follows. This disclosure is not intended to be limited by this presumption. Figure 1 is a schematic diagram of a cross-section of polyurethane foam 10. Since polyurethane foam 10 contains a predetermined amount or more of polyether polyol (a) with an ethylene oxide unit content of 25% by mass or more, openings such as cells communicating with the skin layer are easily formed. For this reason, it is presumed that external sound can easily enter the interior of polyurethane foam 10 through the openings compared to polyurethane foam without openings of cells communicating with the skin layer, thus improving sound absorption. In Figure 1, the arrows schematically represent how external sound enters the interior of the polyurethane foam and is absorbed. Furthermore, since the polyurethane foam 10 has an average number of functional groups of 3.8 or more in the entire polyol, it is presumed to have adequate strength and ensure various physical properties such as shock absorption.

[0053] The articles in which the polyurethane foam 10 is used are not particularly limited. Polyurethane foam 10 is suitable as a vehicle component because it maintains good physical properties and has excellent sound absorption performance. Examples of vehicle components include ceiling base materials, interior materials such as instrument panels, and various sound-absorbing materials placed in the vehicle's undercarriage. Polyurethane foam 10 is particularly suitable as a vehicle component if it has excellent shock absorption properties. Furthermore, polyurethane foam 10 is particularly suitable as a vehicle component if it has a low VOC value or low odor. Furthermore, since polyurethane foam 10 maintains good physical properties and has excellent sound absorption performance, it is suitable as a sound-absorbing material. Examples of sound-absorbing materials include sound-absorbing materials for vehicles such as cars, aircraft, and ships, sound-absorbing materials for building materials, and sound-absorbing materials for electronic components. When polyurethane foam 10 has excellent shock absorption properties, it is particularly suitable as a shock-absorbing sound-absorbing material. The polyurethane foam 10 constituting the sound-absorbing material does not necessarily have to have some or all of its skin layer removed. If the skin layer is not removed, the cost of secondary processing related to skin layer removal can be reduced, and the hardness of the material can be increased compared to when the skin layer is removed. [Examples]

[0054] Next, the above embodiments will be described in more detail with reference to examples and comparative examples. 1. Manufacturing of polyurethane foam First, the raw material components of the compositions used for the polyurethane foam in each example and comparative example are shown below. Polyol (a1): A random copolymer of propylene oxide and ethylene oxide with a hydroxyl value of 52 mg KOH / g, a number average molecular weight of 3300, and 3 functional groups (manufactured by Mitsui Chemicals, Inc., EP505S), containing 72% by mass of ethylene oxide units, corresponding to polyether polyol (a) described in the embodiment. Polyol (b): A propylene oxide-ethylene oxide copolymer with a hydroxyl value of 56 mgKOH / g, a number average molecular weight of 3000, and 3 functional groups (manufactured by Sanyo Chemical Industries, Ltd., GL3000), containing 20% ​​by mass of ethylene oxide units, corresponding to polyether polyol (b) described in the embodiment. Polyol (c): A polyether polyol (BASF, VP9346) with a hydroxyl value of 450 mgKOH / g, a number average molecular weight of 650, and 5.2 functional groups, containing 0% by mass of ethylene oxide units, corresponding to the polyether polyol (c) described in the embodiment. Polyol (d): Hydroxyl value 1828 mgKOH / g, number average molecular weight 92.07, polyol with 3 functional groups (manufactured by Kao Corporation, glycerin), ethylene oxide unit content 0% by mass Polyol (a2): A polyol (BASF, Lupranol 2048 / 2) with a hydroxyl value of 42 mgKOH / g, a number average molecular weight of 3600, and 2.7 functional groups, containing 30% by mass of ethylene oxide units, corresponding to polyether polyol (a) described in the embodiment. Additive: Tris(1-chloro-2-propyl) phosphate (manufactured by Daihachi Chemical Co., Ltd., TCPP) Foam stabilizer 1: Foam stabilizer for flexible polyurethane foam, manufactured by Toray Dow Corning, VORASURF SF1280A Foam stabilizer 2: Foam stabilizer for HR mold foam, manufactured by Toray Dow Corning, VORASURF SF2962A Foam stabilizer 3: Foam stabilizer for flexible polyurethane foam, manufactured by Toray Dow Corning, VORASURF SZ1136 Catalyst 1: N,N,N',N',N''-pentamethyldiethylenetriamine, manufactured by BASF; Luplagen N301 (foaming catalyst) Catalyst 2: 1,3,5-Tris(dimethylaminopropyl)hexahydro-s-triazine, manufactured by BASF; Luplagen N600 (trimerization catalyst) Catalyst 3: Triethylmethylammonium 2-ethylhexanoate, manufactured by Sunapro Co., Ltd. Ucat18X (trimerization catalyst) Catalyst 4: Bis(2-dimethylaminoethyl) ether, manufactured by BASF; Luplagen N206 (foaming catalyst) Catalyst 5: Methyldicyclohexylamine, Polycat12 (balanced catalyst) manufactured by EVONIK. Catalyst 6: Aliphatic amine, EVONIK Polycat55 (balanced catalyst) Catalyst 7: N,N-dimethylaminohexanol, manufactured by BASF, Luplagen N107 (foaming catalyst) Catalyst 8: quaternary ammonium salt, manufactured by Tosoh Corporation: TOYOCAT TR20 (trimerization catalyst) Catalyst 9: quaternary ammonium salt, manufactured by Tosoh Corporation: TOYOCAT TRX (trimerization catalyst) Catalyst 10: Dimethylaminohexanol, Kao Corporation Kaolizer No. 25 (resin-based catalyst) Foaming agent: Water Isocyanate: Polymeric MDI, 31.0% NCO (BASF product, part number LUPRANATE M-20S)

[0055] The above components were mixed in the proportions shown in Table 1-4 below to obtain the polyurethane foams of each example and comparative example. In Table 1-4, a blank space indicates that the proportion of that component is 0 parts by mass.

[0056] [Table 1] [Table 2] [Table 3] [Table 4]

[0057] 2. Evaluation of polyurethane foam The obtained polyurethane foam was evaluated using the following evaluation method. The results are shown in each column of Table 1-4. [density] In accordance with JIS K7222:2005, apparent total density (kg / m³) 3 ) was measured. [Sound absorption performance] In accordance with JIS A1405-2:2007, the sound absorption coefficient was measured at a specimen thickness of 15 mm and frequencies of 500 Hz, 1000 Hz, 2000 Hz, 2500 Hz, and 3150 Hz. The sound absorption coefficient was measured using specimens with a skin layer, with the surface of the skin layer used as the reference plane. The sound absorption coefficient measured at each frequency was evaluated according to the following evaluation criteria. 500Hz: The sound absorption coefficient is 0.10 or higher. 1000Hz: The sound absorption coefficient is 0.35 or higher. 2000Hz: The sound absorption coefficient is 0.78 or higher. 2500Hz: The sound absorption coefficient is 0.84 or higher. 3150Hz: The sound absorption coefficient is 0.76 or higher. In Table 1-4, "OK" is indicated in the column for the measurement frequency if the evaluation criteria are met at each frequency. One point is awarded for meeting the conditions at each frequency, and the total points (1-5 points) for the frequencies of 500Hz, 1000Hz, 2000Hz, 2500Hz, and 3150Hz are used to determine the sound absorption performance score of the test specimen. A higher score indicates better sound absorption performance. [Strength] In accordance with JIS K7220:2006, the maximum force (maximum load) at which the deformation rate of polyurethane foam reached within 10% was measured. The maximum load of the polyurethane foam was measured using a 50mm x 50mm x 30mm thick test piece cut from the core of each polyurethane foam. The measured maximum load (N) was evaluated and scored according to the following evaluation criteria. A higher score indicates better shock absorption. 3. The compressive strength is between 180N and 300N. Two points: The compressive strength is 120N or more but less than 180N, or greater than 300N and 400N or less. 1 point: Compressive strength is less than 120N or greater than 400N. [VOC] Tests were conducted on formaldehyde, acetaldehyde, acrolein, benzene, toluene, xylene, ethylbenzene, styrene, tetradecane, dibutyl phthalate (DBP), and bis[2-ethylhexyl] phthalate (DEHP) under the assumption that they would be used as automotive interior materials, and scores were assigned according to the following criteria. A score of 1 indicates a reduction in VOCs compared to a score of 0. 1 point: For all 11 items listed above, the VOC values ​​are below the standard value. 0 points: Of the 11 items listed above, some do not meet the standard VOC values. [Odor] A sensory evaluation was conducted assuming use as an automotive interior material, and the odor intensity was evaluated according to the following evaluation criteria. Odor intensity 5: Strong smell 4: Strong odor 3: Easily detectable odors 2: A smell that you can identify. 1: Finally, a smell that can be detected 0: Odorless Odor levels were scored according to the following criteria. A score of 1 indicates a reduction in odor compared to a score of 0. 1 point: The odor intensity is either 0, 1, or 2. 0 points: Odor intensity is 3, 4, or 5.

[0058] The total score for sound absorption, strength, VOCs, and odor was calculated as the sum of the scores for physical properties. The overall evaluation was based on the total score for physical properties and evaluated according to the following criteria. A: The total score for physical properties is between 7 and 10 points. B: The total score for physical properties is between 4 and 6 points. C: The total score for physical properties is 3 points or less.

[0059] 3.Results Examples 1-10 and 12-23 satisfy the following requirement ac. Requirement a: The polyol includes a polyether polyol (a) having an ethylene oxide unit content of 25% by mass or more. Requirement b: The content of polyether polyol (a) is 10 parts by mass or more and 50 parts by mass or less, when the total polyol is 100 parts by mass. Requirement c: The average number of functional groups in the entire polyol is 3.8 or higher. In contrast, the comparative example does not satisfy requirement c. Examples 1-10 and 12-23 received higher overall ratings compared to the comparative examples. It was found that Examples 1-10 and 12-23 maintained good physical properties and possessed excellent sound absorption performance.

[0060] Examples 1-5 are polyurethane foams obtained by changing the blending ratio of polyol (a) and polyol (b). A higher blending ratio of polyol (a) tended to result in higher strength, while a higher blending ratio of polyol (b) tended to result in higher sound absorption coefficients in the 1000Hz-2500Hz range. These results suggest that sound absorption and shock absorption properties can be suitably controlled by adjusting the blending ratio of polyol (a) and polyol (b).

[0061] Examples 6-8 and 18-21 are polyurethane foams obtained by changing the type and amount of foam stabilizer. Example 6, which used both foam stabilizer 1 (for flexible polyurethane foam) and foam stabilizer 2 (for HR molded foam), scored higher in sound absorption performance than Examples 7-8, which used only foam stabilizer 3 (for flexible polyurethane foam). This result suggests that sound absorption can be improved by using a foam stabilizer for HR molded foam. Furthermore, in Examples 18-21, the higher the amount of foam stabilizer 1 (foam stabilizer for flexible polyurethane foam) and foam stabilizer 2 (foam stabilizer for HR mold foam), the higher the scores for sound absorption performance and strength. This result suggests that sound absorption and shock absorption can be controlled by adjusting the amount of foam stabilizer used.

[0062] Examples 9 and 10 are polyurethane foams obtained by changing the isocyanate index (INDEX). Example 9, with an isocyanate index of 100, had a lower compressive strength than Example 10, with an isocyanate index of 120. This result suggests that shock absorption can be controlled by adjusting the isocyanate index.

[0063] Examples 12-17 are polyurethane foams obtained by changing the type and amount of catalyst used. For example, in Example 12, which used catalyst 4 (bis(2-dimethylaminoethyl) ether, a foaming catalyst), good sound absorption was observed above 2000 Hz. In Example 15, which used catalyst 7 (N,N-dimethylaminohexanol, a foaming catalyst), good sound absorption was observed below 2000 Hz. Furthermore, in each example using other catalysts, it was found that the frequency and sound absorption characteristics changed depending on the type and amount of catalyst used. These results suggest that sound absorption performance can be controlled by adjusting the type of catalyst.

[0064] Example 22 showed a higher overall score in physical properties compared to the comparative example and other examples. Example 22 suggests that the combined use of foam stabilizer 1 (for flexible polyurethane foam) and foam stabilizer 2 (for HR mold foam) can suitably improve sound absorption and shock absorption performance. Furthermore, Example 22 suggests that the combined use of catalyst 4 (bis(2-dimethylaminoethyl) ether, foaming catalyst) and catalyst 7 (N,N-dimethylaminohexanol, foaming catalyst) can suitably improve sound absorption and shock absorption performance while reducing VOCs and odor.

[0065] 4. Effects of the Examples The polyurethane foams in the above examples maintained good physical properties and possessed excellent sound absorption performance.

[0066] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of the claims set forth herein. [Explanation of symbols]

[0067] 10: Polyurethane foam 10A: Surface 11: Core 12: Skin layer

Claims

1. A polyurethane foam obtained from a composition containing a polyol and a polyisocyanate, The polyol includes a polyether polyol having an ethylene oxide unit content of 25% by mass or more. The number-average molecular weight of the aforementioned polyether polyol is 1000 or more. The content of the polyether polyol is 10 parts by mass or more and 50 parts by mass or less when the total amount of the polyol is 100 parts by mass. A polyurethane foam having an average number of functional groups of 3.8 or more in the entire polyol.

2. A polyurethane foam obtained from a composition containing a polyol and a polyisocyanate, The polyol includes a polyether polyol having an ethylene oxide unit content of 25% by mass or more. The content of the polyether polyol is more than 15 parts by mass and 50 parts by mass or less, when the total polyol is 100 parts by mass. A polyurethane foam having an average number of functional groups of 3.8 or more in the entire polyol.

3. Density of 30 kg / m³ ３ The polyurethane foam according to claim 1 or claim 2.

4. A vehicle component comprising the polyurethane foam described in claim 1 or claim 2.

5. A sound-absorbing material comprising the polyurethane foam described in claim 1 or claim 2.

Images