Low-density polyurethane foam composition as sound absorbing material, method for producing polyurethane foam and polyurethane foam produced therefrom

Abstract

The present application discloses a low-density polyurethane foam composition as a sound-absorbing material, a method for manufacturing a polyurethane foam, and a polyurethane foam manufactured therefrom. Specifically, a composition comprising a polyol mixture including a polyol and an additive and an isocyanate, and the manufacture of a low-density polyurethane foam for a sound-absorbing material are disclosed, and the sound-absorbing material is endowed with improved appearance formability, reduced odor, and enhanced sound-absorbing performance by controlling the content of the composition and the conditions for foaming the composition.

Description

Technical Field

[0001] The present disclosure relates to a polyurethane foam composition for a sound absorbing material, a method for manufacturing a polyurethane foam, and a polyurethane foam manufactured using the method. More specifically, the present disclosure relates to a composition comprising a polyol mixture containing a polyol and an additive and an isocyanate, and the manufacture of a low-density polyurethane foam for a sound absorbing material, which imparts improved appearance formability, reduced odor, and enhanced sound absorbing performance by controlling the content of the composition and the composition foaming conditions. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] To reduce the weight of automobiles, the physical properties of lightweight alternative materials should be comparable to or better than those of conventional materials.

[0004] Specifically, physical fluidity related to the viscosity of the raw material (crude) solution and chemical fluidity related to the foaming reaction behavior are very important for the molding of instrument panel insulation (iso) pads, because these factors may cause defects such as unmolded end parts during foam molding. When the feed weight is increased to solve this molding problem, the weight of the product increases, making it difficult to achieve weight reduction.

[0005] Generally, the cell structure of polyurethane foams for increased sound absorption should be designed to have more open cells (continuous foam) than closed cells (individual foam), and higher density is advantageous.

[0006] At the same time, automotive interior materials are advantageous when they are light within the range of maintaining performance. As the weight of interior materials including dashboard insulation pads increases, the weight of the vehicle body also increases, which has an adverse effect on fuel economy. Therefore, there is still a need to develop a high-foaming polyurethane foam that satisfies formability despite the increase in manufacturing cost due to its weight.

[0007] For this reason, methods of reducing the weight of interior materials have been studied, but for polyurethane foam used for instrument panel insulation pads, simply increasing the content of the blowing agent to reduce the density may reduce the moldability and fail to satisfy the appearance, and result in reduced sound absorption performance and physical properties such as tensile strength and tear strength.

[0008] Meanwhile, fillers such as carbon nanotubes, calcium carbonate, graphite, and magnesium hydroxide are generally used in polyurethane foam compositions in order to improve sound absorption properties, but such fillers may cause problems such as precipitation formation or layer separation in the polyurethane foam compositions.

[0009] The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0010] The present disclosure is directed to solving the above-mentioned problems associated with the prior art.

[0011] The present disclosure provides a polyurethane foam having low density, satisfactory mold formability, and improved sound absorbing properties compared to conventional polyurethane foams.

[0012] The present disclosure provides a method for improving sound absorption without using fillers such as carbon nanotubes, calcium carbonate, graphite, and magnesium hydroxide that are commonly used to improve sound absorption performance.

[0013] The present disclosure provides polyurethane foams with reduced odor.

[0014] The present disclosure is not limited to those described above. The present disclosure will be clearly understood from the following description, and can be implemented by the means defined in the present invention and combinations thereof.

[0015] In one aspect, the present disclosure provides a low-density polyurethane foam composition for a sound absorbing material, comprising a polyol mixture including a polyol and at least one additive selected from the group consisting of a catalyst, a cell opener, a chain extender, a cross-linking agent, a blowing agent, a surfactant, a reducing agent, and a combination thereof, and isocyanate, wherein the catalyst comprises a gelling catalyst and a blowing catalyst.

[0016] The polyol may include a first polyol having a molecular weight of 5,500 to 6,500 and a hydroxyl (OH) value of 26 to 30 and containing 14 to 16% of ethylene oxide (EO), and a second polyol having a molecular weight of 500 to 1,500 and a hydroxyl value of 110 to 114.

[0017] The catalyst may include a gelling catalyst comprising at least one of a primary alcohol and a secondary alcohol and a blowing catalyst comprising at least one of a primary alcohol and a secondary alcohol.

[0018] The gelling catalyst may include at least one of 1,4-diazabicyclo[2,2,2]octane-2-methanol, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine or N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, and the foaming catalyst may include at least one of N,N,N'-trimethyl-N'-hydroxyethyl-bis(aminoethyl) ether or N,N-dimethylethanolamine.

[0019] The cell opener may have a molecular weight of 3,800 to 4,600 and a hydroxyl value of 37 to 43, and include 65 to 75 wt % of ethylene oxide (EO).

[0020] The cell opener may include at least one of propoxylated glycerin, ethoxylated glycerin, or a propoxylated-ethoxylated glycerin copolymer.

[0021] The chain extender may have a molecular weight of 350-450 and a hydroxyl value of 270-290.

[0022] The cross-linking agent may have a molecular weight of 100 to 110 and a hydroxyl value of 1,600 to 1,650.

[0023] The blowing agent may have a molecular weight of 10 to 30 and a hydroxyl value of 6,230 to 6,235.

[0024] The polyol mixture may include 19.8 to 24.0 parts by weight of the additive based on 100 parts by weight of the polyol.

[0025] The polyol mixture may include 4.4 to 6.4 parts by weight of a cell opener, 3.3 to 4.3 parts by weight of a catalyst, 1.0 to 1.4 parts by weight of a chain extender, 0.55 to 0.65 parts by weight of a crosslinking agent, 4.85 to 4.95 parts by weight of a blowing agent, 3.4 to 4.4 parts by weight of a surfactant, and 2.3 to 2.5 parts by weight of a reducing agent based on 100 parts by weight of the polyol.

[0026] The polyol mixture may include 3.0 to 3.8 parts by weight of a gelling catalyst and 0.3 to 0.5 parts by weight of a blowing catalyst, based on 100 parts by weight of the polyol.

[0027] The polyol may include 92 to 94 wt % of the first polyol and 6 to 8 wt % of the second polyol.

[0028] The polyurethane foam composition may include 40 to 60 parts by weight of the isocyanate based on 100 parts by weight of the polyol mixture.

[0029] In another aspect, the present disclosure also provides a method for producing a low-density polyurethane foam for a sound absorbing material, the method comprising adding an additive to a polyol to prepare a polyol mixture, adding an isocyanate to the polyol mixture to prepare a polyurethane foam composition, and foaming the polyurethane foam composition, wherein the catalyst comprises a gelling catalyst and a foaming catalyst.

[0030] After the additives are added to the polyol, the polyol mixture may be stirred at 1,500 to 1,800 rpm for 30 to 60 minutes, and after the isocyanate is added to the polyol mixture, the polyurethane foam composition may be stirred at 6,000 to 8,000 rpm.

[0031] The polyurethane foam composition may be foamed in a mold, the foaming pressure may be 120 to 160 bar, the temperature of the polyurethane foam composition may be 18 to 28°C, and the temperature of the mold may be 50 to 70°C.

[0032] In another aspect, the present invention provides a low-density polyurethane foam for sound absorbing material manufactured by the method, which has a density of less than 75 kg / m 3 density.

[0033] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order that the present disclosure may be more fully understood, its various forms will now be described by way of example and with reference to the accompanying drawings, in which:

[0035] Figure 1 The appearance and cross-sectional views of polyurethane foams produced using the polyurethane foam compositions of Example 1 and Comparative Examples 1 to 4 are shown;

[0036] Figure 2 shows the appearance of a polyurethane foam produced in the form of an instrument panel insulation pad using the polyurethane foam composition of Comparative Example 1; and

[0037] Figure 3 The appearance of a polyurethane foam produced in the form of an instrument panel insulation pad using the polyurethane foam composition of Example 2 is shown.

[0038] The drawings herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION

[0039] The following description is essentially only exemplary and is not intended to limit the present disclosure, application or use. It should be understood that throughout the accompanying drawings, corresponding reference numerals represent identical or corresponding parts and features. In the accompanying drawings, for the sake of clarity, the size of the structure will be exaggerated. It should be understood that, although the terms "first", "second" etc. can be used to describe each element in this article, these elements should not be interpreted as being limited to these terms, which are only used to distinguish one element from other elements. For example, within the scope of the present disclosure definition, the "first" element can be referred to as the "second" element, and similarly, the "second" element can be referred to as the "first" element. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form.

[0040] It should be further understood that when used in this specification, the terms "comprising" and / or "having" specify the presence of the stated features, integers, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. In addition, it should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element, or there can be intermediate elements. It should also be understood that when an element such as a layer, film, region, or substrate is referred to as being "under" another element, it can be directly under the other element, or there can be intermediate elements.

[0041] Unless otherwise clearly stated in the context, all numbers, graphics and / or expressions representing the amount of ingredients, reaction conditions, polymer compositions and mixtures in this specification are approximate values ​​reflecting the various measurement uncertainties inherent in obtaining these graphics, etc. For this reason, it should be understood that in all cases, the term "about" should be understood to modify all numbers, graphics and / or expressions. In addition, when a numerical range is disclosed in the specification, unless otherwise defined, these ranges are continuous and include all numbers from the minimum to the maximum, including the maximum value in each range. In addition, when a range is an integer, unless otherwise defined, it includes all integers from the minimum to the maximum, including the maximum value in the range.

[0042] It should be understood that in this specification, when a range is mentioned about a parameter, the parameter covers all numbers including the endpoints disclosed in the range. For example, the range "5 to 10" includes the numbers of 5, 6, 7, 8, 9 and 10, and any sub-ranges, such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, and any numbers between suitable integers in the range, such as 5.5, 6.5, 7.5, 5.5 to 8.5 and 6.5 to 9. In addition, for example, the range of "10% to 30%" covers all integers, including numbers such as 10%, 11%, 12% and 13% and 30%, and any sub-ranges of 10% to 15%, 12% to 18% or 20% to 30%, and any numbers between suitable integers in the range, such as 10.5%, 15.5% and 25.5%.

[0043] The present disclosure relates to a low-density polyurethane foam composition for a sound absorbing material having excellent appearance formability, reduced odor, and enhanced sound absorbing performance, a method for manufacturing the polyurethane foam, and the polyurethane foam manufactured by the method.

[0044] The low-density polyurethane foam composition according to the present invention comprises a polyol mixture including polyol and at least one additive selected from the group consisting of catalysts, cell openers, chain extenders, crosslinking agents, blowing agents, surfactants, reducing agents and combinations thereof, and isocyanate.

[0045] The polyol of the present disclosure is an organic compound having two or more hydroxyl groups (—OH) at the terminal thereof, and is a main component for achieving the properties of the polyurethane foam of the present disclosure.

[0046] The polyol includes a first polyol having a molecular weight of 5,500 to 6,500 and a hydroxyl (OH) value of 26 to 30 and containing 14 to 16% of ethylene oxide (EO) and a second polyol having a molecular weight of 500 to 1,500 and a hydroxyl value of 110 to 114.

[0047] The first polyol preferably has trifunctional groups, and the second polyol preferably has difunctional groups.

[0048] The polyol of the present disclosure includes 92 to 94 wt % of a first polyol and 6 to 8 wt % of a second polyol.

[0049] The catalysts disclosed herein include gelling catalysts and blowing catalysts.

[0050] The gelling catalyst includes at least one of a primary alcohol or a secondary alcohol, and the blowing catalyst includes at least one of a primary alcohol or a secondary alcohol.

[0051] More specifically, the gelling catalyst is a catalyst for promoting a reaction (gelling reaction) between a polyol and an isocyanate, and preferably includes at least one of 1,4-diazabicyclo[2,2,2]octane-2-methanol, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine or N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine.

[0052] The blowing catalyst is a catalyst for promoting the reaction (saturation reaction) of isocyanate with water, and preferably includes at least one of N,N,N'-trimethyl-N'-hydroxyethyl-bis(aminoethyl) ether or N,N-dimethylethanolamine.

[0053] In the present disclosure, the gelling catalyst is present in an amount of 3.0 to 3.8 parts by weight, preferably 3.0 to 3.5 parts by weight, and more preferably 3.0 to 3.2 parts by weight, based on 100 parts by weight of the polyol of the present disclosure. When the content of the gelling catalyst is less than 3.0 parts by weight, there is a problem of curability due to insufficient gelling reaction of the polyurethane foam of the present disclosure, and when the content of the gelling catalyst is greater than 3.8 parts by weight, the gelling reaction is accelerated, the flowability is deteriorated, the density is increased, and the effect of the catalyst in reducing odor and the economic efficiency are thereby deteriorated.

[0054] Based on 100 parts by weight of polyol, the foaming catalyst is present in an amount of 0.3 to 0.5 parts by weight. When the content of the foaming catalyst is less than 0.3 parts by weight, the foaming efficiency is reduced due to the delayed saturation reactivity of the polyurethane foam, and the foam collapses internally due to insufficient partial curing, which may cause defects during molding, such as poor appearance or molding failure caused by the cracking of the part due to the aggregation of cells and interference. When the foaming catalyst is present in an amount greater than 0.5 parts by weight, the shape of the cells is elongated in the foaming direction due to the excessive saturation (gelation) of the polyurethane foam, thereby increasing the generation of holes (voids) and accelerating the internal reaction of the polyurethane foam to increase the number of closed cells. This may cause the sound absorption performance to deteriorate due to shrinkage and openness decline.

[0055] The cell opener of the present disclosure functions to partially and finely open cells formed inside the foam, and has a molecular weight of 3,800 to 4,600, a trifunctional group, and a hydroxyl value of 37 to 43, and contains ethylene oxide (EO) in an amount of 65 to 75 wt %.

[0056] For example, the cell opener of the present disclosure may include at least one of propoxylated glycerin, ethoxylated glycerin, or a propoxylated-ethoxylated glycerin copolymer, and preferably includes a propoxylated-ethoxylated glycerin copolymer.

[0057] The cell opener is present in an amount of 4.4 to 6.4 parts by weight based on 100 parts by weight of the polyol of the present disclosure. When the cell opener is present in an amount of less than 4.4 parts by weight, the polyurethane foam shrinks due to an increase in the number of closed cells, and when the content of the blowing agent of the present invention satisfies 4.85 parts by weight or more based on 100 parts by weight of the polyol, the polyurethane foam cannot withstand excessive gas (CO) during foaming. 2 ) and its interior collapses, and 5% or more of the polyurethane foam will settle after foaming, resulting in poor overall foaming efficiency, increased foam density and decreased sound absorption performance. In addition, when the polyol cell opener exceeds 6.4 parts by weight based on 100 parts by weight and the content of the foaming agent satisfies 4.85 parts by weight or more, as the content of the cell opener increases, the number of irregular open cells increases, and the cell size increases due to the generation of a large amount of gas during the foaming reaction, resulting in the formation of more voids, and due to excessive open cells, the sedimentation ratio after foaming is 5% or more, and the foaming efficiency is reduced. Therefore, compared with the fine and uniform cell opening state, the sound absorption path may be relatively short, and the sound absorption performance may be reduced.

[0058] The chain extender is a substance that extends the polymer main chain and is used in the present disclosure to impart chemical fluidity and cell stability. The chain extender of the present disclosure preferably has a molecular weight of 350 to 450, a bifunctional group, and a hydroxyl value of 270 to 290.

[0059] The chain extender is present in the polyol mixture of the present disclosure in an amount of 0.5 to 1 wt%.

[0060] The chain extender disclosed in the present invention can be used in the technical field of polyurethane foam, and can be used without particular limitation as long as the chain extender conditions are met.

[0061] A crosslinking agent is a substance used to form a polymer chain in the form of a branched or reticular (mesh) structure. In the present disclosure, the crosslinking agent is used to impart firmness and cell stability to the polyurethane foam. The crosslinking agent of the present disclosure preferably has a molecular weight of 100 to 110, a trifunctional group, and a hydroxyl value of 1,600 to 1,605.

[0062] In the polyol mixture of the present disclosure, the crosslinking agent is present in an amount of 0.5 to 1 wt%.

[0063] As long as the cross-linking agent conditions are met, the cross-linking agent of the present disclosure can be used in the field of polyurethane foam without particular limitation.

[0064] The blowing agent of the present disclosure is a substance for making foam, which has a molecular weight of 10 to 30, a bifunctional group, and a hydroxyl value of 6,230 to 6,235.

[0065] The blowing agent is present in the polyol mixture of the present disclosure in an amount of 2 to 5 wt%.

[0066] As long as the blowing agent conditions are met, the blowing agent disclosed herein can be used in the field of polyurethane foam without particular limitation.

[0067] The surfactant of the present invention affects the cell structure in the foam due to the surface active effect, and affects the mixing performance, stability, foam generation, foam stability, etc. of the raw materials.

[0068] The surfactant is a siloxane-based stabilizer, and serves to suppress cell collapse, increase structural stability and impart elasticity, and also serves to provide cell opening, and make the cells dense and uniform, thereby imparting cell stability.

[0069] The surfactant of the present disclosure is sufficient to be a siloxane surfactant generally used in the technical field of polyurethane foam. For example, it is sufficient to include at least one of an organic polysiloxane or an organic modified polysiloxane, and there is no particular limitation in the present disclosure.

[0070] The surfactant of the present invention can be used in the field of polyurethane foam technology, and can be used without particular limitation as long as the surfactant conditions are met.

[0071] The base surfactant is present in an amount of 3.4 to 4.4 parts by weight based on 100 parts by weight of the polyol of the present disclosure.

[0072] The reducing agent disclosed in the present invention is an adsorbent for removing formaldehyde (HCHO) generated during the polyurethane foaming process, and has a moisture content of 25 to 30%. Carbon with partial negative charge and oxygen with partial positive charge in the carbonyl group contained in aldehydes such as formaldehyde contact with the hydroxyl group (-OH) of the reducing agent through electrostatic attraction and form hydrogen bonds, resulting in chemical adsorption through form conversion and recombination. Therefore, there is no secondary problem such as desorption or re-decomposition.

[0073] The reducing agent is present in an amount of 2.3 to 2.5 parts by weight based on 100 parts by weight of the polyol of the present disclosure. Any reducing agent may be used without particular limitation as long as it can be used in the technical field of polyurethane foam and satisfies the conditions of the reducing agent.

[0074] The isocyanate of the present disclosure has an NCO content of 34.5 to 35.5% and an NCO index of 0.5 to 0.9.

[0075] The isocyanate is present in an amount of 40 to 60 parts by weight, based on 100 parts by weight of the polyol mixture in the polyurethane foam composition of the present disclosure.

[0076] The polyol mixture of the present disclosure includes 4.4 to 6.4 parts by weight of a cell opener, 3.3 to 4.3 parts by weight of a catalyst, 1.0 to 1.4 parts by weight of a chain extender, 0.55 to 0.65 parts by weight of a cross-linking agent, 4.85 to 4.95 parts by weight of a blowing agent, 3.4 to 4.4 parts by weight of a surfactant, and 2.3 to 2.5 parts by weight of a reducing agent, based on 100 parts by weight of the polyol mixture including the first polyol and the second polyol, and the polyurethane foam composition of the present disclosure includes 40 to 60 parts by weight of isocyanate, based on 100 parts by weight of the polyol mixture.

[0077] The polyurethane foam manufacturing method according to the present disclosure includes: adding an additive to a polyol to prepare a polyol mixture, adding an isocyanate to the polyol mixture to prepare a polyurethane foam composition, and foaming the polyurethane foam composition.

[0078] In the step of adding the additive to the polyol, the polyol mixture is preferably stirred at 1,500 to 1,800 rpm for 30 to 60 minutes.

[0079] In the step of adding the isocyanate, the polyurethane foam composition is preferably stirred at 6,000 to 8,000 rpm.

[0080] In the step of foaming the polyurethane foam composition, the polyurethane foam composition may be foamed in a mold, the foaming pressure is preferably 120 to 160 bar, the temperature of the polyurethane foam composition is preferably 18 to 28°C, and the temperature of the mold is preferably 50 to 70°C.

[0081] According to the present disclosure, low-density polyurethane foam can be produced as a sound-absorbing material using the aforementioned production method. In this case, under the condition that the foam thickness is 10 to 50 mm, the sound absorption rate (vertical sound absorption rate in the frequency band of 0.4 to 5 kHz) is 0.70 or higher, and the density is less than 75 kg / m 3 Preferably, the polyurethane foam for automobile instrument panel insulation pad is manufactured by the above manufacturing method.

[0082] Hereinafter, the present disclosure will be described in more detail with reference to specific examples. However, the following examples are only provided for a better understanding of the present disclosure and should not be construed as limiting the scope of the present disclosure.

[0083] Example 1

[0084] A polyol was prepared which included 93 wt % of a first polyol including polypropylene glycol having a molecular weight of 6,000, a hydroxyl value of 28 and an ethylene oxide content of 15%, and 7 % of a second polyol including polypropylene glycol having a molecular weight of 1,000 and a hydroxyl value of 112, and an additive was prepared which included 3.1 parts by weight of a gelling catalyst including 1,4-diazabicyclo[2,2,2]octane-2-methanol, 0.6 parts by weight of a cross-linking agent including diethanolamine having a molecular weight of 105, 1.2 parts by weight of a chain extender including ethylene glycol having a molecular weight of 400, 4.9 parts by weight of a blowing agent including water, 3.4 parts by weight of a surfactant including L-3002 (Momentive Corp.), and 2.4 parts by weight of a reducing agent (TS-NVS), based on 100 parts by weight of the polyol. Based on 100 parts by weight of the polyol, a cell opener (propoxylated-ethoxylated glycerol copolymer) having a molecular weight of 42,00, a hydroxyl value of 40 and an EO content of 60% and a foaming catalyst comprising N,N,N′-trimethyl-N′-hydroxyethyl-bis(aminoethyl) ether were prepared in 5.4 parts by weight and 0.4 parts by weight, respectively, and further added to the additives to prepare a polyol mixture, the polyol mixture was stirred at 1,600 rpm for 30 minutes, and then 47 parts by weight of isocyanate (NCO content: about 35%, NCO index: 0.78) was mixed with 100 parts by weight of the polyol mixture and then stirred at 6,000 rpm to prepare a polyurethane foam composition, and the polyurethane foam composition was maintained at a temperature of 20° C. and foamed at a pressure of 130 bar in a mold at a temperature of 55° C. to produce a polyurethane foam (200 mm×200 mm×20 mm).

[0085] Examples 2 to 7

[0086] A polyurethane foam was produced in the same manner as in Example 1, except that the content of the cell opener was adjusted as shown in Table 1 (based on 100 parts by weight of the polyol).

[0087] Table 1

[0088]

[0089] Comparative Examples 1 and 2

[0090] Polyurethane foams were prepared in the same manner as in Example 1, except that the contents of the cell opener were adjusted to 4 parts by weight and 7 parts by weight, respectively, based on 100 parts by weight of the polyol.

[0091] Comparative Examples 3 and 4

[0092] Polyurethane foams were prepared in the same manner as in Example 1, except that the contents of the foaming catalysts were adjusted to 0.2 parts by weight and 0.6 parts by weight, respectively, based on 100 parts by weight of the polyol.

[0093] Comparative Example 5

[0094] Polyurethane foam was prepared in the same manner as in Example 1, except that based on 100 parts by weight of the polyol, the content of the cell opener was adjusted to 3.0 parts by weight, the content of the foaming catalyst was adjusted to 0.1 parts by weight, and the content of the foaming agent was adjusted to 4.0 parts by weight.

[0095] Comparative Examples 6 and 7

[0096] Polyurethane foams were prepared in the same manner as in Example 1, except that the contents of the foaming catalysts were adjusted to 2.8 parts by weight and 4.0 parts by weight, respectively, based on 100 parts by weight of the polyol.

[0097] Experimental Example 1

[0098] The polyurethane foam compositions prepared in Example 1 and Comparative Examples 1-4 were maintained at a temperature of 20° C. and then foamed in a cup-shaped molding mold at a pressure of 130 bar to produce polyurethane foams. The cross-section of the produced polyurethane foam was cut to examine the internal state of the polyurethane foam ( Figure 1 A = Example 1, Figure 1 B = Comparative Example 1, Figure 1 C = Comparative Example 2, Figure 1 D = Comparative Example 3, Figure 1 E = Comparative Example 4).

[0099] Depend on Figure 1 As can be seen from A, the foam has a good appearance and the internal cells are uniformly formed, and Figure 1 B It can be seen that, overall, the foam shrinks and has an internal structure consisting of large and round cavities due to the confinement of the generated gas and the collapse of the cells. Figure 1 C shows that the overall appearance is good, but the foam shrinks irregularly. Figure 1 D shows that the polyurethane foam is not fully foamed and not sufficiently cured, resulting in the collapse of the internal structure and frequent aggregation and rupture of the cells. Figure 1 E It can be seen that the polyurethane foam is over-foamed, resulting in more internal voids.

[0100] Experimental Example 2

[0101] The density, tensile strength, elongation, tear strength and normal incidence sound absorption coefficient of the polyurethane foams prepared in Examples 1 to 7 were measured and are shown in the following Table 2. At this time, according to the MS341-18 standard, the tensile strength, elongation and tear strength were measured using a dumbbell type No. 1, and the sound absorption performance was evaluated as the arithmetic mean of the measurements within the 0.4-5 KHz frequency band by the impedance tube method (29Ψ).

[0102] Table 2

[0103]

[0104] It can be seen from the results in Table 2 that all polyurethane foams have a strength of 76 kg / m 3 Or lower low density, and therefore has low density characteristics and excellent sound absorption performance, and all meet the evaluation standards of tensile strength and tear strength.

[0105] Experimental Example 3

[0106] Under the conditions of the following Table 3 (mold temperature, polyurethane foam composition temperature (=mother solution temperature) and foaming pressure), polyurethane foam was prepared from the polyurethane foam composition produced in Example 1 and the absorption coefficient (Alpha Cabin (ISO 345)) of the polyurethane foam was evaluated (B is the same as the polyurethane foam of Example 1).

[0107] Table 3

[0108]

[0109] It can be seen from Table 3 above that compared with the conventional manufacturing conditions of Example 1 (stock solution temperature: 20°C, mold temperature: 55°C, foam pressure: 130 bar), when the mold temperature is increased and the foaming pressure is increased (stock solution temperature: 20°C, mold temperature: 65°C, foaming pressure: 150 bar), the cell coalescence is minimized, resulting in excellent sound absorption performance.

[0110] Experimental Example 4

[0111] The sound absorption properties of the polyurethane foams of Examples 1 and 4 and Comparative Example 5 were measured and are shown in the following Table 4. Here, the frequency band is 0.4-10 kHz.

[0112] Table 4

[0113]

[0114] As can be seen from the results in Table 4, the polyurethane foams produced in Examples 1 and 4 showed almost the same sound absorbing performance as that of Comparative Example 5, while the foam density was reduced by about 11%.

[0115] Experimental Example 5

[0116] The polyurethane foam compositions of Comparative Example 5 and Example 2 were used to produce polyurethane foams in the form of instrument panel insulation pads to evaluate the appearance formability quality of the parts of the polyurethane foams, and the results are shown in Figure 1 (Comparative Example 5) and Figure 2 (Example 1). Considering that Comparative Example 5 has 85kg / m 3 and 1500g / m 2 The density characteristics of Example 2 are 72 kg / m 3 and 1270g / m 2 The fact that the foam has different density characteristics, but the appearance is the same.

[0117] Experimental Example 6

[0118] In order to evaluate the odor of the polyurethane foam, the polyurethane foams of Examples 1 and 4 and Comparative Examples 5-7 were subjected to sensory evaluation by five evaluators, and the results are shown in the following Table 5. Dimensions, according to the evaluation standard MS300-34, the foam size was 40 mm×50 mm×20 mm.

[0119] Table 5

[0120]

[0121] As can be seen from Table 5, the polyurethane foams of Examples 1 and 4 have higher odor evaluation levels than those of Comparative Examples 5-7.

[0122] Experimental Example 7

[0123] The polyurethane foams of Examples 1 and 4 and Comparative Example 5 were used to measure the volatile organic matter of the polyurethane foam. The polyurethane foam was cut into a size of 100 mm×100 mm, sealed in a Tedlar bag, and heated in a drying oven set at 65° C. for 2 hours in the presence of 3 L of high-purity nitrogen, and then adsorbed on a DNPH box and extracted. The results of the HPLC equipment analysis of the formaldehyde emission are shown in Table 6 below.

[0124] Table 6

[0125] Comparative Example 5 Example 1 Example 4 <![CDATA[141μg / m 3 ]]> <![CDATA[97μg / m 3 ]]> <![CDATA[102μg / m 3 ]]>

[0126] As shown in Table 6, unlike Comparative Example 5, less formaldehyde was released from the polyurethane foams produced using the polyurethane foam compositions of Examples 1 and 4.

[0127] As is apparent from the above, according to the present disclosure, a polyurethane foam having low density, satisfactory moldability, and improved sound absorption can be provided compared to the prior art.

[0128] According to the present disclosure, it is possible to suppress the deterioration of the quality uniformity of the polyurethane foam composition due to the formation of precipitates of fillers such as carbon nanotubes, calcium carbonate, graphite, and magnesium hydroxide and the phenomenon of layer separation.

[0129] According to the present disclosure, a polyurethane foam having reduced odor can be provided.

[0130] The effects of the present disclosure are not limited to those described above. It should be understood that the effects of the present disclosure include all effects that can be inferred from the description of the present disclosure.

[0131] The present disclosure has been described in detail with reference to its variations. However, it should be appreciated by those skilled in the art that changes can be made in these forms without departing from the principles or spirit of the present disclosure, and the scope of the present disclosure is defined in the appended claims and their equivalents.

Claims

1. A low-density polyurethane foam composition for a sound-absorbing material, comprising: A polyol mixture comprising a polyol and an additive, wherein the additive comprises, based on 100 parts by weight of the polyol, 3.3 to 4.3 parts by weight of a catalyst, 4.4 to 6.4 parts by weight of a cell opener, 1.0 to 1.4 parts by weight of a chain extender, 0.55 to 0.65 parts by weight of a crosslinking agent, 4.85 to 4.95 parts by weight of a blowing agent, 3.4 to 4.4 parts by weight of a surfactant, and 2.3 to 2.5 parts by weight of a reducing agent; and Isocyanates, The catalyst includes a gelling catalyst and a foaming catalyst, Wherein, based on 100 parts by weight of the polyol, the polyol mixture comprises 3.0 to 3.8 parts by weight of the gelling catalyst and 0.3 to 0.5 parts by weight of the blowing catalyst.

2. The low-density polyurethane foam composition according to claim 1, wherein The polyols include: a first polyol having a molecular weight of 5,500 to 6,500 and a hydroxyl value of 26 to 30 and containing 14 to 16% ethylene oxide; and The second polyol has a molecular weight of 500 to 1,500 and a hydroxyl value of 110 to 114.

3. The low-density polyurethane foam composition according to claim 1, wherein The catalyst comprises a gelling catalyst including at least one of a primary alcohol or a secondary alcohol; and A blowing catalyst comprising at least one of a primary alcohol or a secondary alcohol.

4. The low-density polyurethane foam composition according to claim 1, wherein The gelling catalyst comprises at least one of 1,4-diazabicyclo[2,2,2]octane-2-methanol, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine or N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, and The foaming catalyst includes at least one of N,N,N′-trimethyl-N′-hydroxyethyl-bis(aminoethyl) ether and N,N-dimethylethanolamine.

5. The low-density polyurethane foam composition according to claim 1, wherein The cell opener has a molecular weight of 3,800 to 4,600 and a hydroxyl value of 37 to 43, and contains 65 to 75 wt % of ethylene oxide.

6. The low-density polyurethane foam composition according to claim 1, wherein The cell opener comprises at least one of propoxylated glycerol, ethoxylated glycerol or a propoxylated-ethoxylated glycerol copolymer.

7. The low-density polyurethane foam composition according to claim 1, wherein The chain extender has a molecular weight of 350 to 450 and a hydroxyl value of 270 to 290.

8. The low-density polyurethane foam composition according to claim 1, wherein The crosslinking agent has a molecular weight of 100 to 110 and a hydroxyl value of 1,600 to 1,650.

9. The low-density polyurethane foam composition according to claim 1, wherein The foaming agent has a molecular weight of 10 to 30 and a hydroxyl value of 6,230 to 6,235.

10. The low-density polyurethane foam composition according to claim 1, wherein The polyol mixture includes 19.8 to 24.0 parts by weight of the additive based on 100 parts by weight of the polyol.

11. The low-density polyurethane foam composition according to claim 2, wherein: The polyol includes 92 to 94 wt % of the first polyol and 6 to 8 wt % of the second polyol.

12. The low-density polyurethane foam composition according to claim 1, wherein The polyurethane foam composition includes the isocyanate in an amount of 40 to 60 parts by weight, based on 100 parts by weight of the polyol mixture.

13. A method for producing a low-density polyurethane foam for a sound-absorbing material, comprising: adding an additive to a polyol to prepare a polyol mixture, wherein the additive comprises, based on 100 parts by weight of the polyol, 3.3 to 4.3 parts by weight of a catalyst, 4.4 to 6.4 parts by weight of a cell opener, 1.0 to 1.4 parts by weight of a chain extender, 0.55 to 0.65 parts by weight of a crosslinking agent, 4.85 to 4.95 parts by weight of a blowing agent, 3.4 to 4.4 parts by weight of a surfactant, and 2.3 to 2.5 parts by weight of a reducing agent; adding an isocyanate to the polyol mixture to prepare a polyurethane foam composition; and foaming the polyurethane foam composition, The catalyst includes a gelling catalyst and a foaming catalyst, and the polyol mixture comprises 3.0 to 3.8 parts by weight of the gelling catalyst and 0.3 to 0.5 parts by weight of the foaming catalyst based on 100 parts by weight of the polyol.

14. The method according to claim 13, wherein: After adding the additive to the polyol, stirring the polyol mixture at 1,500 to 1,800 rpm for 30 to 60 minutes, and After adding the isocyanate to the polyol mixture, the polyurethane foam composition was stirred at 6,000 to 8,000 rpm.

15. The method according to claim 13, wherein: The polyurethane foam composition is foamed in a mold, The foaming pressure is 120 to 160 bar. The temperature of the polyurethane foam composition is 18 to 28°C, and The temperature of the mold is 50 to 70°C.

16. The low-density polyurethane foam for sound absorbing material manufactured by the method according to claim 13, having a density of less than 75 kg / m 3 density.

Images