JPH06184263A - Low-density polyurethane foam having impact resistance and its production - Google Patents

Abstract

PURPOSE:To obtain the subject foam suitable for interior automotive trim, etc., having lightness, excellent dimensional stability and moldability by subjecting a polyisocyanate component, a specific polyol, a specific chain extender, a catalyst, a blowing agent, a foam stabilizer and a filler to reaction injection molding. CONSTITUTION:(A) A polyisocyanate component, (B) two kinds of polyols of (i) a polyether polyol having 2-5 functionality and 1,000-8,000 molecular weight and (ii) a tertiary amine nitrogen-containing polyol having 2-5 functionality and 200-800 molecular weight as essential components as polyols using 10-70wt.% component (ii) based on the polyol components (except filler), (C) a hydroxyl group-containing compound not containing hydrogen atom of an aliphatic amine as a chain extender, (D) a foamable amine catalyst containing even methylene grouW betwee%ne nitrogen atoms or between-an-amine trogen atom and an oxygen atom, (E) a blowing agent, (F) a foam stabilizer and (G) a filler are subjected to reaction injection molding to give the objective foam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low density impact resistant polyurethane foam which is preferably used as a base material for automobile interior materials such as door trims, instrument panels, console boxes and pillars, and a method for producing the same.

[0002]

2. Description of the Related Art As a base material for interior materials for automobiles,
Low density, light weight, and moderate mechanical properties (flexural rigidity,
Characteristics such as impact resistance) and dimensional stability are required. In order to satisfy such required characteristics, for example, as a base material for a door trim, a wood fiber hardened with a phenol resin has hitherto been widely used because the material is inexpensive. However, when the wood fiber is used, in addition to the problems of complicated manufacturing process, lack of design freedom, poor working environment, and the like, there are also problems in terms of weight reduction. In view of such circumstances, recently, as an alternative material thereof, for example, polypropylene (PP),
Acrylonitrile-butadiene-styrene copolymer (A
Thermoplastic resin such as BS) and structural reaction injection molding (SR)
IM) Urethane foam (hard urethane foam reinforced with a glass mat) and the like are being studied or used.

[0003]

However, in any of the above alternative materials, material cost, moldability,
There are considerable merits and demerits in characteristics such as weight reduction, and improvement of defects is desired. Under these circumstances, all the required properties of the interior material as a base material are satisfied,
And as a material with excellent design flexibility and moldability,
Recently, attention has focused on fiber reinforced (RRIM) polyurethane foam molded by the reaction injection molding (RIM) process. However, in the case of molding such a polyurethane foam, when a conventionally known hard urethane foam-based raw material system which uses a lot of polyether polyol having a molecular weight of less than 1000 is used, the moldability (the raw material There is a problem that filling properties, void and cell roughness, skin peeling property, demolding property, curing time, etc.) and mechanical properties (bending rigidity, impact resistance, etc.) cannot be sufficiently satisfied.

In the field of semi-rigid or rigid polyurethane foam, a method for increasing the expansion ratio by increasing the amount of water used as a foaming agent is known as a technique for reducing the density. There is a problem of moldability such as roughness. On the other hand, in JP-A-55-135128,
Three specific types (a primary hydroxyl group-containing polyol and two types of 2
By adding a filler having a specific particle size to the polyol component of the mixture of primary hydroxyl group-containing polyol) and reacting it with a polyfunctional isocyanate, a semi-rigid polyurethane foam with excellent impact absorption capacity without voids and cell roughness is obtained. Is disclosed.

The present invention has been invented in view of the above circumstances, and has been solved for the above-mentioned conventional problems (low density, light weight, mechanical characteristics, dimensional stability, moldability and cost) for automobiles. It is an object of the present invention to provide a polyurethane foam which has a low density (about 0.2 to 0.7 g / cm ³ ) and is excellent in impact resistance, which is preferably used as a base material for interior materials, and a method for producing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above-mentioned circumstances, and as a result, by combining a specific chain mixture with a specific chain extender and a foaming catalyst, the present invention Find that the purpose of can be achieved easily,
The present invention has been completed. That is, the gist of the present invention is a polyurethane foam obtained by reacting a polyisocyanate component with a polyol component containing a chain extender, a foaming agent, a foam stabilizer, a catalyst, and a filler as an optional component. ) As a polyol, a polyether polyol (1-A) having a functionality of 2 to 5 and a molecular weight of 1000 to 8000, and a functionality of 2 to 5 and a molecular weight of 200
-800 tertiary amine nitrogen-containing polyol (1-B)
2 kinds of polyols as the essential components are used, and the polyol (1-B) is used in an amount of 10 to 70% by weight with respect to the polyol component (excluding the filler), (2)
As a chain extender, a hydroxyl group-containing compound (2-A) not containing an aliphatic amine hydrogen atom, an aromatic amine-containing compound (2-B) containing an aromatic amine hydrogen atom, and an aliphatic group-containing aliphatic amine group. Any of amine-containing compounds (2-C) is used, and (3) as a foaming catalyst, a foaming property having a molecular structure having an even number of methylene groups between amine nitrogen atoms or between amine nitrogen atoms and oxygen atoms. A low-density impact-resistant polyurethane foam characterized by using an amine catalyst and a method for producing the same.

The present invention will be described in detail below. The polyol used in the present invention has a functionality of 2 to 5,
It is a mixture containing two types of polyether polyol (1-A) having a molecular weight of 1000 to 8000 and a tertiary amine nitrogen-containing polyol (1-B) having a functionality of 2 to 5 and a molecular weight of 200 to 800 as essential components.

The above polyether polyol (1-A) is, for example, polyhydroxyl such as water, ethylene glycol, diethylene glycol, trimethylene glycol, 1,4-butanediol, glycerin, hexanetriol, trimethylolpropane, pentaerythritol. The polyether polyol obtained by adding 1 type or 2 types or more of alkylene oxides, such as ethylene oxide, propylene oxide, and butylene oxide, to a compound is mentioned. When the functional number of the polyether polyol is smaller than the above range, mechanical properties such as impact resistance are deteriorated, and when it is larger than the above range, the filling property of the raw material into the molding die is deteriorated, and voids and cell roughness are caused. Since the moldability tends to be deteriorated, such as the occurrence of, there is usually used 2-5, preferably 2-4. Regarding the molecular weight, from the viewpoint of moldability such as impact resistance and cure characteristics,
Usually 1000 to 8000, preferably 3000 to 60
No. 00 is used.

The tertiary amine nitrogen-containing polyol (1-B) used in the present invention has one or more terminal hydroxypoly (oxyalkylene) or alkanol groups attached to the tertiary amine nitrogen atom. , A tertiary amine compound having a functionality of 2 to 5 and a molecular weight of 200 to 800, such as triethanolamine, alkyldiethanolamine, alkyldi (isopropanol) amine, tri (isopropanol) amine, or alkylenediamine, N-hydroxy. Examples thereof include reaction products of dialkyl alkylene diamines or amine-terminated polyethers with alkylene oxides.

A preferred example of the above polyol (1-B) is a reaction product of alkylenediamine and alkyleneoxide. Examples of the alkylenediamine include linear or branched alkylene groups having 1 to 30 carbon atoms, preferably 2 to 5 carbon atoms, and examples thereof include ethylenediamine, diethylenediamine and triethylenediamine. As the alkylene oxide, one kind or two or more kinds of ethylene oxide, propylene oxide, butylene oxide and the like are used.

The functionality of the polyol (1-B) is usually 2-5, preferably 2-4, from the viewpoint of impact resistance and cure characteristics. The molecular weight is usually 200 to 800, preferably 250 to 700, from the viewpoint of the filling property of the raw material and the curing property.

In the present invention, the above-mentioned polyol (1-
The proportion of B) used is important and is usually 10 to 70% by weight based on the polyol component (excluding the filler). When the usage ratio is less than the above range, mechanical properties such as rigidity are deteriorated, and when it is more than the above range, the curing property and the impact resistance tend to be deteriorated. Therefore, the more preferable usage ratio thereof is 20 to 60% by weight.

Polyisocyanate used in the present invention
Examples of the solvent include aromatic polyisocyanate, aliphatic polyisocyanate, and a mixture thereof. Specifically, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude products thereof, p-phenylene diisocyanate, naphthalene diisocyanate, and mixtures thereof. Or the like, a polyisocyanate having two or more NCO groups per molecule, or a modified polyisocyanate obtained by modifying these by means of urethanization, carbodiimidation, amidation or the like, and further, such polyisocyanate and 2 Examples thereof include prepolymers obtained from the compounds having active hydrogen atoms described above. The NCO content of such polyisocyanate is usually 20 to 35% by weight.

The chain extender used in the present invention is a compound containing a hydroxyl group (2-
Any of A), an aromatic amine-containing compound (2-B) containing an aromatic amine hydrogen atom, and an aliphatic amine-containing compound (2-C) containing a primary amine group is used. The amount used is usually 1 to 30% by weight, preferably 5 to 20% by weight, based on the polyol component (excluding the filler).
Is.

Hydroxyl group-containing compound (2-
Examples of A) include a functional number of 2 to 4, a hydroxyl group equivalent of 30 to 120, which does not include an aliphatic amine hydrogen atom, and for example,
Low in ethylene glycol, propylene glycol, trimethylolpropane, 1,4-butanediol, diethylene glycol, dipropylene glycol, bisphenols, hydroquinone, catechol, resorcinol, triethylene glycol, tetraethylene glycol, dicyclopentadiene diethanol, glycerin, glycerin Examples thereof include molecular weight ethylene and / or propylene oxide derivatives. Of these, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and 1,4-butanediol are particularly preferable in the present invention.

The aromatic amine-containing compound (2-B) as a chain extender contains no aliphatic amine hydrogen atom,
And containing at least two aromatic amine hydrogen atoms,
For example, a polyphenyl-polyamine with a functionality of 2-5,
1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 3,5,3 ′, 5′-tetraethyl-4,
4′-diaminodiphenylmethane, phenylenediamine and mixtures thereof and the like.

The aliphatic amine-containing compound (2-C) as a chain extender includes at least one primary amine group and 2 to 16 aliphatic amine hydrogen functionalities, 50 to 5
An aliphatic amine-containing compound having an aliphatic amine hydrogen equivalent weight of 00 is used. Examples thereof include ethylenediamine, diaminopropane, diaminobutane, diethylenetriamine, ethanolamine, hexamethylenediamine, polyoxyalkyleneamines and mixtures thereof.

The foaming catalyst used in the present invention has a structure having a structure having an even number of methylene groups between amine nitrogen atoms, at least one of which is a tertiary amine nitrogen, or between a tertiary amine nitrogen atom and an oxygen atom. Is an amine catalyst,
Examples thereof include tertiary amine nitrogen-containing aliphatic amine compounds such as tetramethyl-n-hexyldiamine, pentamethyl-diethylenetriamine, and bis (dimethylaminoethyl ether). The preferred foamable amine catalyst in the present invention is pentamethyl-diethylenetriamine or bis (dimethylaminoethyl ether).

The proportion of the foamable amine catalyst used is 0.1 to 5% by weight based on the polyol component (excluding the filler). When the usage ratio is less than the above range, the filling property of the raw material into the molding die is deteriorated, and when it is more than the above range, cell roughness is likely to occur. This tendency is particularly remarkable when a raw material system containing a filler (reinforcing material) such as glass fiber is used. Therefore, in consideration of this point, the preferable usage rate is 0.5 to 3% by weight.

As the foaming agent used in the present invention,
Known materials are used, but water or a material containing water as a main component is preferable. The amount of water used is usually 0.1 to 5% by weight, preferably 0.5 to 3% by weight, based on the polyol component (excluding the filler).

In the present invention, a foam stabilizer, a reaction catalyst, a filler as an optional component, a stabilizer and the like are used as the polyol component. A known organosilicon compound or the like is used as the foam stabilizer. As the reaction catalyst (resinization catalyst), a known amine-based catalyst, organic tin-based catalyst, or the like is used. The filler is used in an appropriate amount in order to improve mechanical properties such as flexural rigidity and dimensional stability. Examples thereof include glass fiber, whiskers, mineral fibers and the like.

In the present invention, the polyisocyanate N
The isocyanate (NCO) index, which indicates the equivalent ratio of the CO group and the OH group of the polyol, is 80 to 130, preferably 95 to 115.

In the polyurethane foam of the present invention, the isocyanate component and the polyol component are closed-molded (for example, 50 to 80 ° C.) using a known reaction injection molding machine.
Predetermined injection pressure (for example, 100-180kg)
/ cm ² ) and inject for a predetermined time (for example, 30 to 150 seconds)
After curing, the reaction product is produced by demolding from the mold.

As a method for producing interior materials for automobiles such as door trims, instrument panels, etc., which is the object of the present invention, a foam is formed in advance, and then a soft polyvinyl chloride, leather, fabric or other skin is used. Can be used, or a method in which the above-mentioned skin is attached to the inner surface of the molding die and the urethane raw material is injected into the skin to integrally mold the same.

[0025]

EFFECTS OF THE INVENTION According to the present invention, the reaction mixture is produced by the reaction injection molding method using a polyol component containing a specific chain extender and a foaming catalyst in a specific polyol mixture. In addition, it is possible to efficiently produce a polyurethane foam having excellent curing property and free from voids, cell roughness, skin peeling, and mold-deformation. Moreover, since the polyurethane foam obtained according to the present invention has a low density and is excellent in mechanical properties such as impact resistance and bending strength, it is used for automobile interiors such as door trims, instrument panels, console boxes and pillars. It is preferably used as a base material for materials.

[0026]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist. The reaction components used in the following examples are as follows. (1) Polyisocyanate N: Polymeric MDI (NCO content: 31% by weight) (2) Polyol Polyol 1-A1: Molecular weight 2000 obtained by adding propylene oxide and ethylene oxide to propylene glycol at a ratio of 80:20. Polyether polyol 1-A2: Polyether polyol having a molecular weight of 5000 obtained by adding propylene oxide and ethylene oxide to glycerin in a ratio of 85:15 Polyol 1-A3: Propylene oxide is added to a mixture of glycerin and sucrose. Polyether polyol having a functionality of 4.5 and a molecular weight of 7200, which was obtained in this way Polyol 1-B1: Functionality 4, obtained by adding propylene oxide to ethylenediamine, molecular weight 2
80 polyol Polyol 1-B2: Functionality 4, molecular weight 3, obtained by adding propylene oxide to ethylenediamine
Polyol of 50 Polyol 1-B3: Functionality 4, molecular weight 7 obtained by adding propylene oxide to ethylenediamine
00 polyol Polyol C: polyether polyol having a functionality of 4.5 and a molecular weight of 566 obtained by adding propylene oxide to a mixture of glycerin and sucrose Polyol D1: obtained by adding propylene oxide to ethylenediamine , Functionality 4, molecular weight 150
Polyol D2: Functionality 4, molecular weight 100, obtained by adding propylene oxide to ethylenediamine
Polyol of 0 (3) Chain extender ethylene glycol (EG): hydroxyl group equivalent 31 diethylene glycol (DEG): hydroxyl group equivalent 53 diethyltoluenediamine (DETDA) aminated polyoxypropylene glycol (D-40)
0): Amine hydrogen equivalent 100 (4) Foaming amine catalyst Foaming catalyst 1: Pentamethyl-diethylenetriamine (Amine compound having two methylene groups between tertiary amine nitrogen atoms) Foaming catalyst 2: Bis (dimethyleneaminoethyl) ether)
(Amine Compound Having Two Methylene Groups Between Tertiary Amine Nitrogen Atoms and Oxygen Atoms) Foaming Catalyst 3: Tris (dimethylaminopropyl) amine (Amine Having Three Methylene Groups Between Tertiary Amine Nitrogen Atoms Compound) (5) Reaction catalyst: 20% by weight dimethylethanolamine solution of triethylenediamine (6) Foam stabilizer: Organosilicon compound (L-5420: manufactured by Nippon Unicar) (7) Foaming agent: Water (8) Filler: Glass fiber (diameter 20 microns, length 200 microns, MFT-10: Asahi Fiber Glass Co., Ltd.)

Examples 1-19 and Comparative Examples 1-8 Polyurethane foams were produced in the following manner according to the formulations shown in Table 1, Table 2, Table 3, Table 4 and Table 5.
A polyol component obtained by mixing a foaming agent, a foam stabilizer, a catalyst and a filler with a polyol is mixed with a polyisocyanate component using a reaction injection molding machine, and an aluminum mold (400x800x3 mm) temperature-controlled at 55 ° C is mixed. Injection pressure 150kg / c
The raw material mixture was injected at m ² and cured for a predetermined time. Then, the obtained foam was demolded. The obtained foam was stored for 2 days according to JIS standard, and then various physical properties were measured. In each table, the maximum bending load and impact resistance at a foam density of 0.5 g / cm ³ are shown as the molded product characteristics. Also, as foam formability, the state of void / cell roughness (good: ○, bad: ×), the state of skin peeling (good: ○, bad: ×), the state of deformability due to mold release (good without deformation) : ◯, defective with deformation: ×) and curing time are also shown. In addition, the maximum bending load test
(0x200x3 mm) was supported at two points with a span of 150 mm, and the load at maximum bending was measured when a load was applied to the center at a load speed of 50 mm / min. The impact resistance is measured by measuring the maximum height of a test piece (with a 2 mm thick vinyl chloride skin) without dropping cracks when a weight of 500 g is dropped from a predetermined height in an atmosphere of -30 ° C. It was shown by the impact energy of.

[0028]

[Table 1] Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Polyol 1-A1---31 -Polyol 1-A2--31--Polyol 1-A3----31 Polyol 1-B2-50 50 50 50 Polyol C 96 31---Water 1.5 1.5 1.5 1.5 1.5 EG-14 14 14 14 L-5420 1 1 1 1 1 Foaming catalyst 1-1-1 1 Reaction catalyst 1.5 1.5 1.5 1.5 1.5 Glass fiber 41.2 53.5 49 48.5 48 Isocyanate N 132 204 176 173 172 NCO Index 105 105 105 105 105 (Mold formability) Void / cell roughness ○ ○ × ○ ○ Skin peeling ○ ○ ○ ○ ○ Demolding deformability ○ ○ ○ ○ ○ Cure time (sec) 200 45 45 45 45 (molded product characteristics) Density (g / cm ³ ) 0.5 0.5 0.5 0.5 0.5 Maximum bending load (N) 67 70 50 45 55 Impact resistance (Nm) 1.1 1.2 3.4 3.0 3.4

[0029]

[Table 2] Comparative Example 4 Example 3 Example 4 Example 5 Example 6 Polyol 1-A2 76 71 61 51 31 Polyol 1-B2 5 10 20 30 50 Water 1.5 1.5 1.5 1.5 1.5 EG 14 14 14 14 14 L-5420 1 1 1 1 1 Foaming catalyst 1 1 1 1 1 1 Reaction catalyst 1.5 1.5 1.5 1.5 1.5 Glass fiber 35.7 37 39.9 42.5 48 Isocyanate N 102 110 125 141 172 NCO index 105 105 105 105 105 (Mold formability) Void / cell roughness ○ ○ ○ ○ ○ Skin peeling ○ ○ ○ ○ ○ Demolding deformability × ○ ○ ○ ○ Cure time (sec) 250 150 100 90 45 (Molded product characteristics) Density (g / cm ³ ) 0.5 0.5 0.5 0.5 0.5 Maximum bending load (N) 27 34 42 50 60 Impact resistance (Nm) 3.2 3.2 3.4 3.4 3.4

[0030]

[Table 3] Example 7 Comparative Example 5 Comparative Example 6 Example 8 Example 9 Comparative Example 7 Polyol 1-A2 11 1 31 31 31 31 Polyol 1-B1---50--Polyol 1-B2 70 80----Polyol 1 -B3----50-Polyol D1--50---Polyol D2-----50 Water 1.5 1.5 1.5 1.5 1.5 1.5 EG 14 14 14 14 14 14 L-5420 1 1 1 1 1 1 Foaming catalyst 1 1 1 1 1 1 1 Reaction catalyst 1.5 1.5 1.5 1.5 1.5 1.5 Glass fiber 53 56 67 51.5 40.7 38.7 Isocyanate N 202 217 279 192 131 119 NCO index 105 105 105 105 105 105 (Molding) Void / cell roughness ○ ○ × ○ ○ ○ Skin peeling ○ × × ○ ○ ○ Demolding deformability ○ ○ ○ ○ ○ × Cure time 45 120 120 45 45 150 (molded product characteristics) Density (g / cm ³ ) 0.5 0.5 0.5 0.5 0.5 0.5 Maximum bending load (N) 65 68 75 65 50 45 Impact resistance (Nm) 3.4 3.4 3.3 3.4 3.4 3.3

[0031]

[Table 4] Example 10 Example 11 Example 12 Example 13 Comparative Example 8 Polyol 1-A2 31 31 31 31 31 Polyol 1-B2 50 50 50 50 50 Water 1.5 1.5 1.5 1.5 1.5 EG 14.5 13 12 14 14 L-5420 1 1 1 1 1 Foaming catalyst 1 0.5 2 3--Foaming catalyst 2---1-Foaming catalyst 3----1 Reaction catalyst 1.5 1.5 1.5 1.5 1.5 Glass fiber 48 48 48 48 48 Isocyanate N 172 172 172 172 172 172 NCO index 105 105 105 105 105 (Mold formability) Void / cell roughness ○ ○ ○ ○ × Skin peeling ○ ○ ○ ○ ○ Demolding deformability ○ ○ ○ ○ ○ Cure time 45 45 45 45 30 (Molded product characteristics) Density (g / cm ³ ) 0.5 0.5 0.5 0.5 0.5 Maximum bending load (N) 60 61 60 59 60 Impact resistance (Nm) 3.4 3.4 3.4 3.3 3.4

[0032]

[Table 5] Example 14 Example 15 Example 16 Example 17 Example 18 Example 18 Polyol 1-A2 35 30 25 31 31 31 Polyol 1-B2 55 45 50 50 50 50 Water 1.5 1.5 1.5 1.5 1.5 1.5 EG 5 20-12 12 12 DEG--20---DETDA---2-1 D-400----2 1 L-5420 1 1 1 1 1 1 1 Foaming catalyst 1 1 1 1 1 1 1 1 Reaction catalyst 1.5 1.5 1.5 1.5 1.5 1.5 Glass fiber 42.3 51.5 46 47 46.5 46.7 Isocyanate N 139 190 160 165 164 165 NCO index 105 105 105 105 105 105 (Molding) Void / cell roughness ○ ○ ○ ○ ○ ○ Skin peeling ○ ○ ○ ○ ○ ○ Demolding deformability ○ ○ ○ ○ ○ ○ Cure time (seconds) 45 120 50 45 45 45 (molded product characteristics) Density ( g / cm ³ ) 0.5 0.5 0.5 0.5 0.5 0.5 Maximum bending load (N) 47 55 60 60 59 58 Impact resistance (Nm) 3.3 3.4 3.4 3.3 3.4 3.3

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08G 101: 00) C08L 75:04

Claims (9)

[Claims] 1. A polyisocyanate component, a chain extender,
In a polyurethane foam obtained by reacting a polyol component containing a foaming agent, a foam stabilizer, a catalyst, and a filler as an optional component, (1) The polyol has a functionality of 2 to 5 and a molecular weight of 1
000-8000 polyether polyol (1-A)
And a polyol (1-B) having a functionality of 2 to 5 and a molecular weight of 200 to 800 and a tertiary amine nitrogen-containing polyol (1-B) as essential components, the polyol (1-
10) B) to the polyol component (excluding filler)
Used as a chain extender, a hydroxyl group-containing compound (2-A) not containing an aliphatic amine hydrogen atom, an aromatic amine-containing compound (2-B) containing an aromatic amine hydrogen atom, Any of the aliphatic amine-containing compounds (2-C) containing a primary amine group is used, and (3) As a foaming catalyst, an even number of amine nitrogen atoms or amine nitrogen atoms and oxygen atoms are used. A low density impact resistant polyurethane foam characterized by using a foamable amine catalyst having a molecular structure having a methylene group. 2. The low-density impact-resistant polyurethane foam according to claim 1, wherein the proportion of the polyol (1-B) used is 20 to 60% by weight based on the polyol component (excluding the filler). 3. The low-density impact-resistant polyurethane foam according to claim 1, wherein the polyol (1-B) is a reaction product of alkylenediamine and alkylene oxide. 4. The low-density impact-resistant polyurethane foam according to claim 1, wherein the proportion of the foamable amine catalyst used is 0.5 to 3% by weight based on the polyol component (excluding the filler). 5. The low density impact resistant polyurethane foam according to claim 1, wherein the foamable amine catalyst is pentamethyl-diethylenetriamine or bis (dimethylaminoethyl ether). 6. A hydroxyl group-containing compound (2 as a chain extender
The low-density impact-resistant polyurethane foam according to claim 1, wherein -A) is a hydroxyl group-containing compound having a functionality of 2 to 4 and a hydroxyl equivalent of 30 to 120. 7. A hydroxyl group-containing compound (2 as a chain extender
-A) is ethylene glycol, diethylene glycol,
The low-density impact-resistant polyurethane foam according to claim 6, which is propylene glycol, dipropylene glycol or 1,4-butanediol. 8. The low density impact resistant polyurethane foam according to claim 1, wherein the foaming agent is water. 9. A polyisocyanate component, a chain extender,
In a method for producing a polyurethane foam by reaction injection molding a polyol component containing a foaming agent, a foam stabilizer, a catalyst and a filler as an optional component, (1) The polyol has a functionality of 2 to 5 and a molecular weight of 1
000-8000 polyether polyol (1-A)
And a polyol (1-B) having a functionality of 2 to 5 and a molecular weight of 200 to 800 and a tertiary amine nitrogen-containing polyol (1-B) as essential components, the polyol (1-
10) B) to the polyol component (excluding filler)
Used as a chain extender, a hydroxyl group-containing compound (2-A) not containing an aliphatic amine hydrogen atom, an aromatic amine-containing compound (2-B) containing an aromatic amine hydrogen atom, Any of the aliphatic amine-containing compounds (2-C) containing a primary amine group is used, and (3) As a foaming catalyst, an even number of amine nitrogen atoms or amine nitrogen atoms and oxygen atoms are used. A method for producing a low-density impact-resistant polyurethane foam, which comprises using an expandable amine catalyst having a molecular structure having a methylene group.