JPS60192722A - Semi-rigid polyurethane foam - Google Patents

Abstract

PURPOSE:A semi-rigid polyurethane foam having an isocyanurate structure and being moldable by a thermocompression molding process and suitable as a door pad or the like, obtained by reacting a polyether-polyol of specified properties with an excess of a polyisocyanate. CONSTITUTION:The purpose semi-rigid polyurethane foam is obtained by mixing an active hydrogen-containing polyether-polyol having a functionality >=2 and an average OH value of 10-120mg KOH/g (e.g., a reaction product between glycerin and propylene oxide) with a polyisocyanate (e.g., 2,4-tolylene diisocyanate or phenylene diisocyanate) at an equivalent ratio of 1:1.5 or larger, and reacting the mixture by heating. The obtained polyurethane foam has a foam density of 20-100kg/cm<3> and a 25%-compression hardness of 0.1-0.5kg/cm<2>, and can be suitably used in applications where some elasticity and rigidity are necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heat compression moldable semi-rigid polyurethane foams.

Conventionally, hot compression molding of urethane foam is known for soft urethane foam, but not for semi-rigid polyurethane foam.

Automobile door pads, various sports equipment such as elbow pads, knee pads, sun visor pads, etc. require a certain degree of rigidity and elasticity of stone. Semi-rigid polyurethane foam is used for these applications, but conventional semi-rigid polyurethane foam cannot be heat compression molded from polyurethane foam sheets, etc., so it is necessary to form the desired shape directly from a mold, which increases manufacturing costs. was increasing.

The present inventors produced a polyurethane foam having an isocyanurate structure using a polyether polyol having a relatively large molecular weight, that is, a small average hydroxyl value.
As a result, it was possible to obtain a semi-rigid polyurethane foam that can be molded by heat compression molding, and it was found that this foam did not exhibit excellent resilience that cannot be obtained with conventional semi-rigid polyurethane foams. The isocyanurate structure does not provide heat resistance or flame retardancy to rigid polyurethane foams, so it is adopted in rigid polyurethane foams used for such purposes. Because it is hard and brittle, it is not used in flexible or semi-rigid polyurethane foam.

The present invention is a thermocompression method having an isocyanurate structure obtained by reacting a polyether polyol with a functional group number of 2 or more and viscous hydrogen and an average hydroxyl value of 10 to 120 and a polyisocyanate at an equivalent ratio of 1:1.5 or more. Molding phase 0
Provides flexible semi-rigid polyurethane foam.

The polyether polyol used in the present invention has two
As mentioned above, it preferably has 2 to 6 active hydrogen atoms, particularly preferably 2 to 4 active hydrogen atoms, and has an average hydroxyl value of 10 to 12.
0, more preferably 20 to 80. When the hydroxyl value exceeds 120, the foam becomes hard and hot compression molding becomes difficult. Typical hard urethane foams often have a hydroxyl value of 300 or more.

Examples of polyether polyols include glycol,
Examples include, but are not limited to, those made by reacting glycerin, trimethylolpropane, pentaerythritol, sorbitol, ethylenediamine, etc. with alkylene oxides such as ethylene oxide and/or propylene oxide, and ordinary urethane foams. Any polyether polyol can be used as long as it has a hydroxyl value within the above range. Particularly preferably, a polyol such as glycerin is reacted with propylene oxide and/or ethylene oxide and has a hydroxyl value of 20 to 80IIIuK.
OHlo polyether polyol.

The polyisocyanate used in the present invention may be any polyisocyanate that is commonly used in urethane foams. The number of isocyanate groups in one molecule is 2-3
is appropriate. Further, any of aromatic polyisocyanates and aliphatic polyisocyanates i to i can be used.

Examples of typical polyisocyanates are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Trimethylene polyphenylisocyanate (obtained by phosgenating a condensate of aniline and formaldehyde,
Examples include so-called crude MDI), phenylene diisocyanate, diphenylmethane diisocyanate, cyclohexane diisocyanate-1-, and isophorone diisocyanate. These may be used as a mixture, or may be a prepolymer with a polyether polyol having a residual amount of isocyanate groups of 20% or more.

The equivalent ratio of polyether polyol and polyisocyanate is 1:1.5 or more, more preferably 1:1.5 to 1:6.
, more preferably at a ratio of 1:1.5 to 3.5. When the reaction ratio is lower than this, the isocyanure-I structure will not be formed or the eel will be extremely raw.
It is no longer possible to obtain a semi-rigid polyurethane foam that can be heat compression molded to meet the objectives of the present invention.

Suitable catalysts for introducing isocyanurate structures into polyurethane foams include, for example, potassium acetate,
Potassium propionate, potassium hexanoate, potassium 2-methylpropionate, potassium 2-methyl-hexanoate, potassium 2-ethylhexanoate, etc., 1.3.5-
Examples include triazine compounds such as 1-lis[3-(dimethylamino)propyl]hexahydro-8-triazine. Additionally, common catalysts for polyurethane formation, such as tertiary amines, may be used in combination with these catalysts.

In producing the semi-rigid polyurethane foam of the present invention,
Foaming agents, foam stabilizers, flame retardants, colorants, stabilizers, fillers, etc. that have been commonly used in the production of polyurethane foams are added as appropriate.

Examples of blowing agents include low-boiling halogenated hydrocarbons,
Specifically, monofluorotrichloromethane, methylene chloride, etc. may be used.

As the foam stabilizer, a general silicone foam stabilizer for producing urethane foam, etc. can be used.

As the salmon flame retardant, those used in general flame-retardant polyurethane foams, such as a combination of antimony oxide and halogen-containing synthetic resin, ammonium phosphate, aluminum hydroxide, and halogen-containing organic phosphate ester, may be used as appropriate.

In the present invention, it is preferable to use a small amount of water during the reaction of polyol and polyisocyanate. The amount of water used is, for example, - for 100 parts by weight of polyisocyanate.
It is preferable to use 1 to 10 parts by weight of C. The use of water partially forms urea bonds and hardens the polyurethane foam.

Although the semi-rigid polyurethane foam obtained by the present invention is a semi-rigid foam, unlike conventional semi-rigid polyurethane foam, it can be heat compression molded, and once compression molded, it returns to its original size even under harsh conditions. Because it does not restore or deform, it can be used in applications that require a certain degree of elasticity and rigidity, such as sun visor pads, door pads, crash pads, knee pads, and elbow pads. In addition, the polyurethane foam sheet can be easily molded by placing it in a desired mold and heating and compressing it, so production efficiency is high and it can be supplied at low cost. Furthermore, since the semi-rigid polyurethane foam of the present invention is heat-settable, it can be easily used in molding processes that require heat-setting.

The present invention will be explained below with reference to Examples.

LLLL (Manufacture of semi-rigid polyurethane foam) A polyether polyol base was manufactured by WA using the following formulation.

Polyether poly LIL All-based polyether polyol I 100 Water 2 Monoflu A loturicol methane 30 Antimony trioxide 10 Polyvinyl chloride resin (fine powder) 30 Potassium acetate 1 Silicone foam stabilizer 1 Metallic soap 2 Propylene oxide in 1 glycerin and ethylene oxide (=J
Added poly-earth - Terboryl A-le (Water M base value 45 m o
KOH/(+> The above polyether polyol base was mixed well, and tolylene diisocyanate (62 parts by weight) and crude MDI were added to the mixture.
(N00%: 31) Add 62 double openings, carefully stir and mix.
equivalent ratio of active hydrogen to active hydrogen (1:2.5 times). Put this mixture in a box (inner size 20c+nx 20CIIIX 20CI
I+> and foamed.

Next, this box was placed in an oven at 100° C. and left for 5 minutes, and then left at room temperature overnight. The physical properties of the obtained polyurethane foam (LJIS K6401) were as follows.

25% compression hardness II: 0.25ko/cra2 (J
IS K6382) Foam density: 35kq/m3 (JIS K6401) Repulsion elasticity: 35% (JIS K6401) Tensile strength: 1, 1 kg/cn+2 (J
ISK6401) Elongation ゛ 30% (JIS K6401) Flammability (MVSS): Pass The obtained polyurethane foam was found to have an absorption peak of 14100 m-1 indicating isocyanurate lIi& by IR analysis. Ta.

(Production of semi-rigid polyurethane foam without isocyanurate structure) A semi-rigid polyurethane foam was produced using the following recipe.

Prescription 12 Polyol A 2' 100 Polyol B 3' 100 Tris dichloro U propyl 5 15 NoA sphaetomonoph[][]triclo 3 0 Methane water 3.0 3.0 1-lyethylenediamine 0.2 0.5 Silicone world 101 activity Agent 1.5 1.5 Isocyanes 1-A 4
66 (1oo) Isocyanate B 5 79 (110) Polyether polyol with a 2-average hydroxyl value of 110.

A prepolymer of polyether polyol (hydroxyl value 400) obtained by adding propylene oxide and ethylene oxide to polyether polyol-4 glycerin having an average hydroxyl value of 230 and tolylene diisocyanate (contains 1 to 30% by weight of isocyanate).

5 tolylene diisocyanate and crude MD'1 (N00%:
31) mixture.

Figures in ) indicate the ratio of water and active hydrogen to chemical equivalents (isocyanate index).

The physical properties of the obtained semi-rigid polyurethane foam having substantially no isocyanurate bonds are shown below (the measurement method is the same as in Example 1).

2" Nini [Precious-12 25% compression hard melon 0.10.25 (k(1/cin2) ItI (kMm3) 50 35 Repulsion elasticity (%) 35 22 Tensile strength (ko/cm2) 1.8 1. 2 elongation (
%) 100 35 = f ] 2 and Car side 3 and 4 The polyurethane foam obtained in Example 1 and Comparative Examples 1 and 2 was sliced into 2 x 10 x 15 cm3, and the hot plate heated air was adjusted to 180°C. The thermoformed product was compressed to a thickness of 1 cm in a compressor and left for a certain period of time, and then the thermoformed product was taken out and left to stand day and night, and then its thickness was measured. After leaving it in a constant temperature bath roughly adjusted to 80℃ for 24 hours, take it out and measure the thickness (S), and calculate the recovery rate (%) using the following formula: lc0 recovery*<%) = ((S-1 )/1)X1001
The results are shown in Table 1 below.

Table-1

Claims (1)

[Claims] 1. A polyether polyol having an active hydrogen functional group number of 2 or more and having an average hydroxyl value of 10 to 1201110KOH/() is reacted with a polyisocyanate in an equivalent ratio of 1:1.5 or more. 2. The polyurethane foam according to item 1, wherein the polyether polyol has a functional group number of 2 to 6. 3. The average hydroxyl value is 20 to 6. b. The polyureta foam according to item 1. 4. The polyureta foam according to item 1, wherein the equivalent ratio of poly1-delpolyol to polyisocyanate is 1=1.5 to 1:3.5. 5. Polyether polyol. The polyurethane foam according to item 1, wherein the semi-rigid urethane foam has a polyoxyalkylene glycol chain. 6. The semi-rigid urethane foam has a foam density of 20 to 10.
0kg/m3J5 and 25% compression hardness 0.1~0.5k
(The polyurethane foam according to item 1, which is 11012.