JP2005272806A - Rigid polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rigid polyurethane foam (I) excellent in an impact absorbing performance, when used as an impact absorbing material, and to obtain a rigid polyurethane foam (II) having buckling properties, excellent in a sound absorbing performance, and suitable as a sound shielding and absorbing material. <P>SOLUTION: The rigid polyurethane (I) foam is composed of three layers of a surface high-density layer (X1), an inner low-density layer (Y1), and a surface high-density layer (X2) and molded by pouring a sole foam molding composition containing a foaming agent consisting mainly of water into a mold in one stage, wherein the layers (X1) and (X2) each have a thickness of ≥0.5 mm. The impact absorbing material is formed out of the rigid polyuretahne foam (I). The rigid polyurethane foam (II) is composed of two layers of a low-density layer (Y) having a density of 10-70 kg/m<SP>3</SP>and a high-density layer (X), wherein the layer (X) has a thickness of ≥0.5 mm. The sound shielding and absorbing material is formed out of the rigid polyurethane foam (II). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to rigid polyurethane foam. More specifically, the present invention relates to a rigid polyurethane foam suitable for an impact absorbing material or a sound absorbing material.

Conventionally, a thermosetting rigid polyurethane foam is used as an impact absorbing material.
For example, Patent Document 1 is known as a polyurethane foam excellent in impact absorbing ability.
Conventionally, the sound-absorbing and sound-absorbing material is disposed around the driver's seat of an automobile, for example, in order to block sound from the engine unit, and a thermosetting flexible polyurethane foam is used. For example, Patent Document 2 is known as a flexible polyurethane foam excellent in sound insulation performance.
JP-A-5-331364 Japanese Patent Laid-Open No. 5-84858

However, the shock absorbing material made of rigid polyurethane foam has a drawback that the shock absorbing ability is not sufficient when a high stress is momentarily applied to the collision object.
In addition, sound-absorbing sound-absorbing materials made of flexible polyurethane foam have no buckling performance, and when automobiles cause accidents, they are subject to high stress on the impacted object, causing the driver to injure the foot. is there. Further, conventional rigid polyurethane foams cannot be used as sound-absorbing materials because they have no sound-absorbing performance.

The present inventors have intensively studied to solve these problems, and have reached the following invention.
That is, the present invention includes the following (I) to (IV).
(I) A single foam-forming composition comprising three layers of a surface high-density layer (X1), an internal low-density layer (Y1), and a surface high-density layer (X2) and containing a foaming agent mainly composed of water. A rigid polyurethane foam which is formed by being poured into a mold in one stage, and each of (X1) and (X2) has a thickness of 0.5 mm or more.
(II) A rigid polyurethane foam comprising two layers of a low density layer (Y) having a density of 10 to 70 kg / m ³ and a high density layer (X), wherein the thickness of (X) is 0.5 mm or more.
(III) An impact absorbing material comprising the rigid polyurethane foam of (I) above.
(IV) A sound absorbing material comprising the rigid polyurethane foam of (II) above.

  The rigid polyurethane foam of the first aspect of the present invention buckles without applying high stress to the impacted object, and is excellent in impact absorbing ability. Therefore, it is useful as a shock absorber for automobiles. Further, the rigid polyurethane foam of the second invention has both impact absorbing ability and sound absorbing performance, and is useful as a sound absorbing material for automobiles.

The rigid polyurethane foam of the first invention comprises three layers, a surface high-density layer (X1), an internal low-density layer (Y1), and a surface high-density layer (X2). If the foam is not a three-layer structure, the cell is randomly destroyed when a load is applied, and the cell does not have sufficient shock absorption capability.
The foam of the first invention is formed by pouring a single foam-forming composition containing a water-based foaming agent into a mold in one step. If the foam is not formed in a single stage, it is difficult to cope with complicated shapes such as vehicle members.
The thicknesses of (X1) and (X2) are each 0.5 mm or more. The lower limit of the thickness is preferably 0.8 mm, more preferably 1 mm, and the upper limit is preferably 10 mm. When the thickness of the high-density layer is less than 0.5 mm, when stress is applied to the foam, the cell is not uniformly stressed, and the cell is randomly broken and does not have sufficient shock absorbing ability.
Such a rigid polyurethane foam having a three-layer structure formed in one stage can be obtained by selecting the composition of the polyol component, as will be described later, for example.

The density of the surface high density layers (X1) and (X2) is preferably 100 to 300 kg / m ³ , and the density of the internal low density layer (Y1) is preferably 10 to 70 kg / m ³ . The lower limit of the density of (X1) and (X2) is more preferably 110 kg / m ³ , particularly preferably 120 kg / m ³ , and the upper limit is more preferably 290 kg / m ³ , particularly preferably 280 kg / m ³ , Most preferably, it is 200 kg / m ³ . The lower limit of the density of (Y1) is more preferably 15 kg / m ³ , particularly preferably 20 kg / m ³ , and the upper limit is more preferably 65 kg / m ³ , particularly preferably 60 kg / m ³ , most preferably 50 kg. / M ³ . When the density of (X1) and (X2) is 100 to 300 kg / m ³ , strength and weight reduction can be sufficiently achieved as a vehicle member, and the density of (Y1) is preferably 10 to 70 kg / m ^3. It has a strong shock absorption capability.

The thickness of the internal low density layer (Y1) is preferably 100 mm or less, more preferably the lower limit is 1 mm and the upper limit is 90 mm. The thickness of the entire foam is preferably 2 to 120 mm, more preferably the lower limit is 5 mm and the upper limit is 100 mm.
The thickness and density of each layer can be adjusted to the said range by adjusting the quantity of the foaming agent (D) and catalyst (E) which are mentioned later, for example.
For example, when it is desired to increase the thickness of the surface high-density layers (X1) and (X2), the amount of (D) is increased, the amount of (E) is decreased, the amount of injection into the mold is increased, etc. There is a way. In order to increase the density, there is a method of reducing the amount of (D).

The size of the rigid polyurethane foam of the first invention varies depending on the application used and is not particularly limited. For example, when used as an automobile impact absorber, the surface area of (X1) or (X2) is 5,000. About 30,000 cm < ² > is preferable.

Next, the rigid polyurethane foam of the second invention comprises two layers, a low density layer (Y) and a high density layer (X). If the foam is not such a two-layer structure, it cannot have both sufficient shock absorbing ability and sound absorbing performance.
When used as a sound-absorbing material, it is usually used with (Y) being the incident sound side.

The density of the low density layer (Y) is 10 to 70 kg / m ³ . The lower limit of the density of (Y) is preferably 15 kg / m ³ , more preferably 20 kg / m ³ , and the upper limit is preferably 65 kg / m ³ , more preferably 60 kg / m ³ , particularly preferably 50 kg / m ³ . ³ . When the density of (Y) is out of the range of 10 to 70 kg / m ³ , the impact absorbing ability is not suitable.
The density of the high-density layer (X) is preferably 100 to 300 kg / m ³ . The lower limit of the density of (X) is more preferably 110 kg / m ³ , particularly preferably 120 kg / m ³ , and the upper limit is more preferably 290 kg / m ³ , particularly preferably 280 kg / m ³ , most preferably 200 kg. / M ³ . When the density of (X) is 100 to 300 kg / m ³ , strength and weight reduction can be sufficiently achieved as a vehicle member.

The thickness of (X) is 0.5 mm or more. The lower limit of the thickness is preferably 0.8 mm, more preferably 1 mm, and the upper limit is preferably 10 mm. When the thickness of (X) is less than 0.5 mm, when stress is applied to the foam, the cell is not uniformly stressed, and the cell is randomly broken and does not have sufficient shock absorbing ability.
The thickness of (Y) is preferably 100 mm or less, more preferably the lower limit is 1 mm and the upper limit is 90 mm. The thickness of the entire foam is preferably 2 to 110 mm, more preferably the lower limit is 5 mm and the upper limit is 100 mm.
The thickness and density of each layer can be adjusted to the above range by adjusting the amount of the foaming agent (D) and the catalyst (E) described later in the same manner as in the first invention.

The size of the rigid polyurethane foam according to the second aspect of the invention varies depending on the application to be used and is not particularly limited. For example, when used as a sound absorbing material for undercarriage of a driver's seat of an automobile, the surface area of (X) is 5 About 3,000 to 30,000 cm ² is preferable.

The rigid polyurethane foam according to the second aspect of the present invention has two layers, a low-density layer (Y) having a density of 10 to 70 kg / m ³ and a high-density layer (X), which are separately prepared and adhered with an adhesive or the like. Although it may be laminated together, since the process does not become complicated, a single foam-forming composition containing a water-based foaming agent is poured into the mold in one step, and the surface has a high density. A rigid polyurethane foam (that is, the foam of the first aspect of the present invention) composed of three layers of a layer (X1), an internal low density layer (Y1), and a surface high density layer (X2) is used, and the layer (Y1) is divided into two. Or obtained by removing the layer (X2).
If the single foam-forming composition is formed by pouring into a mold in one step, it can easily cope with the complicated shape of the vehicle member.

The means for dividing the layer (Y1) into two is not particularly limited, and examples thereof include a method of cutting with a cutter knife. Further, the position to be divided into two is not particularly limited as long as it is cut so that the layer (Y1) remains on the entire inner surface of both (X1) and (X2), but the center of the thickness of (Y1) It is preferable to cut the vicinity so that (Y1) is substantially equally divided.
Examples of means for removing the layer (X2) include cutting with a cutter knife and scraping with a grinder.
Among these methods, the method of dividing into two by the layer (Y1) is preferable because it is efficient because two foams can be obtained at the same time.

The rigid polyurethane foam of the second invention preferably has a sound absorption coefficient of 45% or more in the entire region having a frequency of 1500 Hz to 4000 Hz. More preferably, it is 60% or more, and particularly preferably 70% or more. When the sound absorption coefficient is 45% or more in the entire region, sound absorption performance suitable as a vehicle member is obtained.
Moreover, it is preferable that the foam of this 2nd invention is 15% or more in the whole area | region whose frequency of absorption is 800 Hz or more and less than 1500 Hz. More preferably, it is 25% or more, and particularly preferably 30% or more. When the sound absorption coefficient is 15% or more in the entire region, sound absorption performance suitable as a vehicle member is obtained.

The rigid polyurethane foams of the first and second inventions preferably have no yield point in the stress compression strain curve. If the stress compression strain curve does not have a yield point, a high stress is not temporarily applied to the collision object, and it works suitably as an impact absorbing material or a sound absorbing material having an impact absorbing ability.
Further, the vertical direction [surface high density layer (X1) / internal low density layer (Y1) / surface high density layer (X2), or high density layer (X) / low density layer (Y) may be stacked vertically] It is preferable that the compressive stress is 550 ± 300 N in a range of 10 to 60% of the foam thickness with respect to the foam thickness. The stress range is preferably 550 ± 280N, more preferably 550 ± 250N. When the stress range is 550 ± 300 N, the impact applied to the collision object is reduced.
The method for measuring compressive stress in the present invention is as follows.
The sample is stacked in a high-density layer and a low-density layer in the height direction, and cut into 50 × 50 mm. Using the cut sample, an autograph “AG-I20kN” manufactured by Shimadzu Corporation is used to measure a stress with respect to a compression rate of 0 to 90% in the stacking direction.

The rigid polyurethane foam of the present invention has a composition as long as it has the above-mentioned surface high-density layer and internal low-density layer (first invention), or has the above-mentioned high-density layer and low-density layer (second invention). The molecular weight between cross-linking points is preferably 300 to 1200, more preferably 400 to 1000, although not particularly limited.
Specifically, for example, a polymer polyol (A) obtained by polymerizing a vinyl monomer (b) in a polyol (a) that serves as a dispersion medium for the polymer with the obtained polymer polyol and / or a polyol other than the polymer polyol ( A foam-forming composition comprising a polyol component consisting of B), a polyisocyanate component (C), a foaming agent (D) mainly composed of water, a catalyst (E), and if necessary a foam stabilizer (F). It can be obtained by reacting the component with (C).

The above polyols (a) and (B) are compounds containing at least 2 (preferably 2 to 8) hydroxyl groups [however, one hydroxyl group and 1 to 7 or more other activities. A small amount (preferably 10% or less) of a compound having a hydrogen-containing group (amino group, imino group, mercapto group, etc.) may be contained. ], For example, an active hydrogen-containing compound having 2 to 8 or more valences such as polyhydric alcohol, polyhydric phenol, amine, polycarboxylic acid, phosphoric acid, etc. A compound having a structure to which AO) is added [(poly) ether polyol] may be mentioned, and two or more of them may be used in combination.
In the above and below, “%” means “% by mass” unless otherwise specified.

  Examples of the polyhydric alcohol include dihydric alcohols having 2 to 20 carbon atoms (aliphatic diols such as ethylene glycol, propylene glycol, 1,3- and 1,4-butanediol, 1,6-hexanediol, neopentyl Alkylene glycols such as glycols; and alicyclic diols such as cycloalkylene glycols such as cyclohexanediol and cyclohexanedimethanol, trihydric alcohols having 3 to 20 carbon atoms (aliphatic triols such as glycerin, trimethylolpropane, Alkanetriols such as methylolethane and hexanetriol); 4 to 8 or more polyhydric alcohols having 5 to 20 carbon atoms (aliphatic polyols such as pentaerythritol, sorbitol, mannitol, sorbitan, jigs) Alkane polyols such as serine and dipentaerythritol, and intramolecular or intermolecular dehydrates of alkanetriol; and sugars and derivatives thereof such as sucrose, glucose, mannose, fructose, and methylglucoside), and two or more The combined use etc. are mentioned.

  Examples of the polyhydric phenol include monocyclic polyphenols such as pyrogallol, hydroquinone, and phloroglucin; bisphenols such as bisphenol A, bisphenol F, and bisphenolsulfone; Examples thereof include polyphenols described in US Pat. No. 3,265,641; and combinations of two or more thereof.

Examples of the amine include ammonia; an aliphatic amine, an alkanolamine having 2 to 20 carbon atoms (for example, monoethanolamine, diethanolamine, triethanolamine, and isopropanolamine), and an alkylamine having 1 to 20 carbon atoms (for example, n- Butylamine and octylamine), alkylene diamines having 2 to 6 carbon atoms (for example, ethylene diamine, propylene diamine and hexamethylene diamine), polyalkylene polyamines having 4 to 20 carbon atoms (dialkylene triamine having 2 to 6 carbon atoms in the alkylene group) -Hexaalkyleneheptamine, such as diethylenetriamine and triethylenetetramine).
C6-C20 aromatic mono- or polyamines (for example, aniline, phenylenediamine, tolylenediamine, xylylenediamine, diethyltoluenediamine, methylenedianiline, and diphenyletherdiamine); C4-C20 alicyclic Amines (for example, isophorone diamine, cyclohexylene diamine, and dicyclohexyl methane diamine); heterocyclic amines having 4 to 20 carbon atoms (for example, those described in piperazine, aminoethylpiperazine, and Japanese Patent Publication No. 55-21044), and these 2 The combined use of more than seeds is mentioned.

Examples of the polycarboxylic acid include aliphatic polycarboxylic acids having 4 to 18 carbon atoms such as succinic acid and adipic acid; aromatic polycarboxylic acids having 8 to 18 carbon atoms such as phthalic acid, terephthalic acid and trimellitic acid; Can be mentioned.
Two or more of these active hydrogen compounds may be used in combination. Of these, polyhydric alcohols are preferred.

  The AO having 2 to 8 or more carbon atoms includes ethylene oxide (hereinafter referred to as EO), propylene oxide (hereinafter referred to as PO), 1,2-, 1,3-, 1,4- and 2,3-butylene. Examples thereof include oxides, styrene oxides, and combinations of two or more of these (block and / or random addition).

  Moreover, you may use 1 or more types of polyols other than the above in a polyol component. Examples of the other polyol include polyester polyol (reaction product of the polyhydric alcohol and the polycarboxylic acid), the polyhydric alcohol, and the alkanolamine.

  The hydroxyl value of the above polyols (a) and (B) as a whole [component obtained by removing the polymer (b) from the polyol component] is preferably 100 to 1000 (mg KOH / g, the same applies to the following hydroxyl values). The lower limit is preferably 140 and the upper limit is preferably 800.

Among the polyol components, the polyol (B) preferably contains one or more alkanolamines (a1). When (a1) is contained, a foam having a three-layer structure of (X1) / (Y1) / (X2) can be easily obtained.
(A1) preferably has 2 to 9 carbon atoms, more preferably 2 to 6 carbon atoms. Specific examples include one or more selected from monoethanolamine, diethanolamine, and triethanolamine, with diethanolamine being preferred.

More preferably, the polyols (a) and / or (B) also contain the following (a2) and (a3).
(A2): Polyoxypropylene polyol having an average functional group number of 2 to 7 and a hydroxyl value of 200 to 600.
(A3): The average number of functional groups is 2 to 5, the hydroxyl value is 20 to 80, and the content of oxyethylene units (hereinafter referred to as EO units) is 0 to 70% (polyoxyethylene). Polyoxypropylene polyol.

Examples of the polyol (a2) include PO adducts of one or more active hydrogen-containing compounds, and two or more of them may be used in combination.
The average number of functional groups per molecule of (a2) is 2-7. The lower limit is preferably 2.5, more preferably 3, and the upper limit is preferably 6, more preferably 5.5. Even if the number of functional groups outside this range is included, the average functional group number may be 2 to 7 using an AO adduct of two or more active hydrogen-containing compounds (the following average functional group number) The same).
Here, the average functional group number is a theoretical value calculated from the average functional group number of the active hydrogen-containing compound as a raw material, and is regarded as the functional group number.
The hydroxyl value of (a2) is 200-600. The lower limit is preferably 250, more preferably 300, and the upper limit is preferably 550, more preferably 500.
When the average number of functional groups in (a2) is 2 or more, the compression set rate is improved, and when it is 7 or less, the elongation property is improved. When the hydroxyl value is 200 or more, the hardness of the foam is improved, and when it is 600 or less, the elongation property is improved.

Examples of the polyol (a3) include AO adducts of one or more active hydrogen-containing compounds, and two or more of them may be used in combination. The AO is PO alone or a combination of EO and PO. When EO and PO are used in combination, any of block addition, random addition, or a combination thereof may be used.
The average number of functional groups per molecule of (a3) is 2-5. The lower limit is preferably 2.2, more preferably 2.5, and the upper limit is preferably 4.5, more preferably 4. The hydroxyl value is 20-80. The lower limit is preferably 30, more preferably 40, and the upper limit is preferably 70, more preferably 65. The content of EO units is 70% or less. Preferably it is 1-69%, More preferably, it is 2-68%.
When the average number of functional groups in (a3) is 2 or more, the compression set rate is improved, and when it is 5 or less, the elongation property is improved. When the hydroxyl value is 20 or more, the hardness of the foam is improved, and when it is 80 or less, the elongation property is improved. When the content of EO units is 70% or less, a continuous foam is obtained, and a foam with good moldability is obtained.

The polymer polyol (A) in the present invention can be produced by polymerizing the vinyl monomer (b) in the polyol (a) by an ordinary method.
For example, in at least one polyol selected from the above (a2) and (a3), a vinyl monomer (b) is polymerized in the presence of a radical polymerization initiator to obtain a polyol in which the polymer is stably dispersed. Is mentioned. In view of good dispersion stability, a polymer obtained by polymerizing (b) in (a3) is preferred.
Specific examples of the polymerization method include those described in US Pat. No. 3,383,351, Japanese Examined Patent Publication No. 39-25737, and the like.

  As the radical polymerization initiator, those which generate free radicals and initiate polymerization can be used, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvalero). Nitrile), 2,2′-azobis (2-methylbutyronitrile) and the like; organic peroxides such as dibenzoyl peroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide and persuccinic acid; And inorganic peroxides such as persulfate and perborate. In addition, these can use 2 or more types together.

(B) includes aromatic vinyl monomer (b1), unsaturated nitriles (b2), (meth) acrylic acid ester (b3), other vinyl monomers (b4), and two or more of these Of the mixture.
Examples of (b1) include styrene, α-methylstyrene, hydroxystyrene, chlorostyrene, and the like.
Examples of (b2) include acrylonitrile and methacrylonitrile.
Examples of (b3) include those composed only of C, H, and O atoms, and include methyl (meth) acrylate, butyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, and dodecyl (meta). ) Acrylate, eicosyl (meth) acrylate, docosyl (meth) acrylate and other (meth) acrylate alkyl (1-30 carbon atoms) ester; hydroxypolyalkylene mono (meth) acrylate (for example, alkylene group having 2 to 4 carbon atoms, And the number average molecular weight of the polyoxyalkylene chain is 200 to 1000).
Other vinyl monomers (b4) include vinyl group-containing carboxylic acids and their derivatives [(meth) acrylic acid, (meth) acrylamide, etc.], aliphatic or alicyclic hydrocarbon monomers [ethylene, propylene, Norbornene, etc.], fluorine-containing vinyl monomers (perfluorooctylethyl methacrylate, perfluorooctylethyl acrylate, etc.), nitrogen-containing vinyl monomers other than the above (diaminoethyl methacrylate, morpholinoethyl methacrylate, etc.), vinyl-modified silicone, etc. Is mentioned.
Among these, (b1) and (b2) are preferable, and styrene and / or acrylonitrile are more preferable.

The mass ratio of (b) is not particularly limited, but an example is as follows.
(B1) and / or (b2) is preferably 5 to 100%, more preferably 10 to 100%. The mass ratio of (b1) and (b2) is not particularly limited, but is preferably 0/100 to 80/20. (B3) is preferably 0 to 50%, more preferably 0 to 20%. (B4) is preferably 0 to 10%, more preferably 0 to 5%.
By using a small amount (preferably 0.05 to 1%) of a polyfunctional (preferably 2 to 8 functional) vinyl group-containing monomer [divinylbenzene, ethylene di (meth) acrylate, etc.] in (b), The strength of the coalescence can be further improved.
The content of the polymer (b) in (A) is preferably 3 to 50%, more preferably 5 to 45%.

In the present invention, when the polyol component contains (a1), (a2), and (a3), each content based on the total mass of (a) and (B) is such that (a1) is 1 to 1 It is preferable that 10%, (a2) is 25 to 89%, and (a3) is 10 to 70%. The lower limit of (a1) is more preferably 2%, particularly preferably 3%, and the upper limit is more preferably 9%, particularly preferably 8%. The lower limit of (a2) is more preferably 30%, particularly preferably 35%, and the upper limit is more preferably 80%, particularly preferably 75%. The lower limit of (a3) is more preferably 13%, particularly preferably 20%, and the upper limit is more preferably 65%, particularly preferably 60%. Other polyols other than these are preferably 5% or less, more preferably 1% or less.
When (a1) is 1% or more, the compression set shows a good value, and when it is 10% or less, the elongation property shows a good value. When (a2) is 25% or more, the foam hardness shows a good value, and when it is 89% or less, the elongation property shows a good value. When (a3) is 10% or more, the curing property is improved, and when it is 70% or less, the foam hardness is improved.

  In the present invention, the polyol component preferably contains the polymer polyol (A). Further, the content of the polymer in the polyol component is preferably 25% or less. The upper limit is more preferably 23%, particularly preferably 20%, and the lower limit is more preferably 5%, particularly preferably 7%, most preferably 10%. When the content is 25% or less, a foam having an appropriate hardness is obtained. When the content is 5% or more, the stretched physical properties of the foam are good.

As the polyisocyanate component (C) in the present invention, those which can be usually used for polyurethane formation are used.
For example, an aromatic polyisocyanate having 6 to 20 carbon atoms (excluding the carbon number in the NCO group) and a crude product thereof [2,4- or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4 ′ -Or 4,4'-diphenylmethane diisocyanate (MDI), crude MDI (polymethylene polyphenylene polyisocyanate), polyaryl polyisocyanate (PAPI), etc.]; aliphatic polyisocyanate having 2 to 18 carbon atoms [hexamethylene diisocyanate, lysine isocyanate] C4-15 alicyclic polyisocyanate [isophorone diisocyanate, dicyclohexyl diisocyanate, etc.]; C8-15 araliphatic polyisocyanate [xylylene diisocyanate, etc.]; modified products of these polyisocyanates Urethane group, carbodiimide group, allophanate group, urea group, biuret group, uretdione group, uretonimine groups, isocyanurate groups or oxazolidone group-containing modified compounds, etc.] and use of two or more types of these can be cited.
Of these, preferred are TDI, MDI, crude MDI, PAPI, carbodiimide group-containing modified MDI, and combinations of two or more thereof. More preferred are MDI, crude MDI, PAPI, carbodiimide group-containing modified MDI, and combinations of two or more thereof.
The NCO group content of (C) is preferably 20 to 35%.

The foaming agent (D) in the present invention uses a foaming agent mainly composed of water.
It is preferable to use only water as (D), but other foaming agents may be used in combination within a range of 50% or less (more preferably 10% or less, particularly preferably 1% or less) in (D). .
As other foaming agents, those usually used for polyurethane are used. As examples, hydrofluorocarbons such as HFC-134a, HFC-152a, HFC-356mff, HFC-236ea, HFC-245ca, HFC-245fa, HFC- 365 mfc, HFC-227ea and the like, and examples of the low boiling point hydrocarbon include butane, pentane and cyclopentane.
The amount of (D) used is preferably 3 to 8 parts with respect to 100 parts by mass of the polyol component (hereinafter, “parts by mass” is simply abbreviated as “parts”). The lower limit is more preferably 4 parts, and the upper limit is more preferably 7 parts.

As the catalyst (E) in the present invention, all usual catalysts used for polyurethane formation can be used. Examples include triethylenediamine, bis (N, N-dimethylamino-2-ethyl) ether, N, N, N. Tertiary amines such as', N'-tetramethylhexamethylenediamine and carboxylates thereof; organometallic compounds such as potassium acetate, potassium octylate, stannous octoate, carboxylic acid metal salts such as dibutyltin dilaurate; It is done.
The amount of (E) used is preferably 0.05 to 10 parts, more preferably 0.1 to 8 parts, relative to 100 parts of the polyol component.

As the foam stabilizer (F) in the present invention, all those used in the production of ordinary polyurethane foams can be used. For example, a dimethylsiloxane foam stabilizer [for example, “SRX manufactured by Toledo Corning Silicone Co., Ltd.” -253 ", etc.], polyether-modified dimethylsiloxane foam stabilizers (for example," L-5309 "," SZ-1311 "manufactured by Nippon Unicar Co., Ltd.," SF-2972 "manufactured by Toray Dow Corning Silicone Co., Ltd.) ”,“ SF-2965 ”,“ SH-193 ”,“ SRX-274C ”, etc.].
The amount of (F) used is preferably 4 parts or less, more preferably 0.2 to 3 parts, and particularly preferably 0.5 to 2 parts with respect to 100 parts of the polyol component.

In the present invention, if necessary, other auxiliary components as described below may be used and reacted in the presence thereof.
For example, colorants (dyes, pigments), flame retardants (phosphate esters, halogenated phosphate esters, etc.), anti-aging agents (triazoles, benzophenones), antioxidants (hindered phenols, hindered amines, etc.) ) And the like.
With respect to the amount of these auxiliary components used relative to 100 parts of the polyol component, the colorant is preferably 1 part or less. The flame retardant is preferably 5 parts or less, more preferably 2 parts or less. The anti-aging agent is preferably 1 part or less, more preferably 0.5 part or less. The antioxidant is preferably 1 part or less, more preferably 0.01 to 0.5 part.

  In the present invention, the isocyanate index (INDEX) [(NCO group / active hydrogen atom-containing group) equivalent ratio × 100] in the production of polyurethane foam is preferably 65 to 130, more preferably 70 to 120, and particularly preferably. 90-110. When the isocyanate index is 65 or more, the compression set of the foam is good, and when it is 130 or less, the curing time of the foam can be shortened.

An example of a method for producing the rigid polyurethane foam of the first invention (which is also a raw material of the foam of the second invention) is as follows.
First, a predetermined amount of a polyol component, a foaming agent (D), a catalyst (E), and, if necessary, a foam stabilizer (F) and other auxiliary components are mixed. Subsequently, this mixture and polyisocyanate component (C) (each liquid temperature: 15-70 degreeC) are rapidly mixed using a polyurethane low pressure or high pressure injection foaming machine, or a stirrer. The obtained mixed solution (foaming stock solution) is poured into a sealed mold (made of metal or resin, mold temperature is 5 to 100 ° C.) with a skin material set as necessary, and a urethanization reaction is performed for a predetermined time ( (For example, 5 to 1800 seconds) After curing, demolding to obtain a polyurethane foam. As for the pack rate at the time of pouring into a closed mold, 100 to 200% is preferable.

  Examples of the skin material set in the mold before foaming include ethylene propylene diene monomer polymer (EPDM), polyolefin (olefin having 2 to 8 carbon atoms, for example, polyethylene, polypropylene), and polyvinyl chloride. The thickness of the skin material is preferably 0.5 to 10 mm, more preferably 1 to 5 mm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited by this.

The raw materials for polyurethane foam in the examples and comparative examples are as follows.
(1) Polyol a1-1: Diethanolamine (2) Polyol a2-1: A polyol having a hydroxyl value of 400 obtained by adding PO to pentaerythritol.
(3) Polyol a2-2: A polyol having a hydroxyl value of 450 obtained by adding PO to a mixture of sucrose and glycerin (average number of functional groups: 5).
(4) Polyol a3-1: A polyol having a hydroxyl value of 56 obtained by adding PO to glycerin and then adding EO as a block. EO unit content 20%.
(5) Polyol a3-2: A polyol having a hydroxyl value of 50 obtained by adding EO to glycerin and then randomly adding PO and EO (mass ratio 7/3). EO unit content 68%.
(6) Polymer polyol A-1: Acrylonitrile and styrene (mass ratio) in a polyol (a3-3) having a hydroxyl value of 56 and an EO unit content of 5% obtained by block addition of glycerin in the order of PO / EO / PO 2: 8) polymer polyol obtained by polymerizing (polymer content 42%).

(7) Catalyst E-1: Dipropylene glycol solution of triethylenediamine [TEDA-L33 manufactured by Tosoh Corporation]
(8) Catalyst E-2: Dipropylene glycol solution of bis (N, N-dimethylamino-2-ethyl) ether [TOYOCAT-ET manufactured by Tosoh Corporation]
(9) Catalyst E-3: Triethylenediamine / dimethylethanolamine = 80/20 (mass ratio) [R-8020 manufactured by Air Products Japan Co., Ltd.]
(10) Foam stabilizer F-1: polyether-modified dimethylsiloxane foam stabilizer [SH-193 manufactured by Toray Dow Corning Silicone Co., Ltd.]
(11) Polyisocyanate C-1: Polymethylene polyphenylene polyisocyanate [MR-200 manufactured by Nippon Polyurethane Co., Ltd.], NCO% = 31.0

Examples 1-2 and Comparative Examples 1-2 [Evaluation as foam for shock absorber]
Using a high pressure foaming machine (MiniRIM machine manufactured by PEC), the temperature of the mixture of components other than polyisocyanate (C-1) and (C-1) shown in Table 1 was adjusted to 25 ° C. The mixture was mixed, poured into a 300 × 300 × 20 mm closed mold whose temperature was adjusted to 60 ° C., and molded. The mold was removed after 3 minutes, and the physical properties of the obtained foam were measured.

Table 1 shows the measurement results of physical properties and the performance evaluation results of each foam.
The density was measured according to JIS K 6400 (1997 edition).
The method for measuring the presence or absence of compressive stress and yield point is as described above.
The shock absorption is measured by measuring the compression rate of the foam when a foam with a thickness of 20 mm is placed on a horizontal surface and a person with a weight of 50 kg jumps onto the foam from a height of 50 cm. A case where compression was 50% or more was evaluated as good, and a case where compression was less than 50% was evaluated as poor.

Examples 3 to 4 and Comparative Examples 3 to 4 [Evaluation as foam for sound insulating material]
Using a high pressure foaming machine (MiniRIM machine manufactured by PEC), the temperature of the mixture of components other than polyisocyanate (C-1) and (C-1) shown in Table 2 was adjusted to 25 ° C. The mixture was mixed, poured into a 300 × 300 × 40 mm closed mold whose temperature was adjusted to 60 ° C., and molded.
After 3 minutes, the mold was removed, and the resulting foam was laminated in the height direction with the surface high-density layer, internal low-density layer, and surface high-density layer, and was bisected in the middle of the internal low-density layer with a cutter knife. The cut sample was used as a physical property value measurement sample.

Table 2 shows the measurement results of physical property values and performance evaluation results of each foam.
The density was measured according to JIS K 6400 (1997 edition).
The method for measuring the presence or absence of compressive stress and yield point is as described above.
The method for measuring the shock absorption is as described above.
The method for measuring the sound absorption rate is as follows.
The sample was made into a state in which the low density layer (Y) / high density layer (X) were laminated in the height direction, cut into a cylindrical shape with a diameter of 3 cm, and (Y) as the incident sound side. The sound absorption coefficient with respect to the frequency is measured with a “normal incidence sound absorption coefficient measurement apparatus (2-microphone method)”.

  From the above results, the rigid polyurethane foams of Examples 1 to 4 of the present invention have a surface high-density layer having a thickness of 0.5 mm or more as compared with the foams of Comparative Examples 1 to 4, and the compression rate is 10 to 60%. It can be seen that it has a stress in a suitable range and is excellent in impact absorption, and the foams of Examples 3 to 4 are also excellent in sound absorption performance.

  The shock absorber made of the hard polyurethane foam of the first invention and, if necessary, a skin material (for example, it is preferable that the foam and the skin material are integrally formed by the above-described method) is very good compared to the conventional one. Since it has an impact absorbing ability, it can be widely used as an impact absorbing material for vehicles (particularly for automobile undercarriages) and building materials. Further, the sound absorbing material comprising the rigid polyurethane foam according to the second invention and, if necessary, a skin material (for example, it is preferable that the foam and the skin material are integrally formed by the above-mentioned method) has a good sound absorbing performance. Therefore, it can be widely used as a sound-absorbing material for vehicles (particularly for automobile suspensions) and building materials.

Claims (12)

A single foam-forming composition comprising a high-density surface layer (X1), an internal low-density layer (Y1), and a high-density surface layer (X2) and containing a water-based foaming agent is molded in one step. A rigid polyurethane foam that is formed by being poured into a film and has a thickness of (X1) and (X2) of 0.5 mm or more. (X1) and a density of 100 to 300 / m ³ of (X2), a rigid polyurethane foam of claim 1, wherein a density of 10 to 70 kg / m ³ of (Y1). A rigid polyurethane foam comprising two layers of a low density layer (Y) having a density of 10 to 70 kg / m ³ and a high density layer (X), wherein the thickness of (X) is 0.5 mm or more. The rigid polyurethane foam according to claim ³ , wherein the density of (X) is 100 to 300 kg / m ³ . A single foam-forming composition comprising a high-density surface layer (X1), an internal low-density layer (Y1), and a high-density surface layer (X2) and containing a water-based foaming agent is molded in one step. The rigid polyurethane foam (X1) and (X2) each having a thickness of 0.5 mm or more is obtained by dividing the layer (Y1) into two parts or removing the layer (X2). The rigid polyurethane foam according to claim 3 or 4, which has been obtained. The rigid polyurethane foam according to any one of claims 1 to 5, wherein the stress compression strain curve does not have a yield point, and the range of stress when the compressibility is in the range of 10 to 60% is 550 ± 300N. The foam-forming composition comprises the following polyol component, polyisocyanate component (C), a foaming agent (D) mainly composed of water, a catalyst (E), and, if necessary, a foam stabilizer (F). The rigid polyurethane foam according to any one of 2, 5, and 6.
Polyol component: a polyol comprising polymer polyol (A) and / or polyol (B) obtained by polymerizing vinyl monomer (b) in polyol (a) and containing alkanolamine (a1) in (B) component. The rigid polyurethane foam according to claim 7, further comprising the following (a2) and (a3) in (a) and / or (B).
(A2): Polyoxypropylene polyol having an average number of functional groups of 2 to 7 and a hydroxyl value of 200 to 600 mgKOH / g.
(A3): (Polyoxyethylene) polyoxypropylene polyol having an average number of functional groups of 2 to 5, a hydroxyl value of 20 to 80 mgKOH / g, and a content of oxyethylene units of 0 to 70% by mass. The impact-absorbing material which consists of the rigid polyurethane foam in any one of Claims 1, 2, and 6-8. The impact-absorbing material according to claim 9, which is formed integrally with a skin material. A sound absorbing material comprising the rigid polyurethane foam according to any one of claims 3 to 8. The sound-absorbing material according to claim 11, wherein the sound-absorbing material is integrally formed with the skin material.