Urethane foam

Abstract

To provide urethane foam having excellent performance.SOLUTION: A urethane foam is provided, at least one surface of which has a surface voidage of 1% or more and less than 60% and an average surface cell diameter of 250 μm or less.SELECTED DRAWING: None

Claims

1. A urethane foam having a surface porosity of 1% or more and 45% or less on at least one surface, and an average surface cell diameter of 250 μm or less. The aforementioned urethane foam is obtained by foaming and curing a foam composition containing a urethane prepolymer and a foaming agent. The urethane prepolymer has an ethylene oxide content of 20.0 to 55.0% by mass per molecule of the urethane prepolymer. The urethane prepolymer has an NCO% of 4.0 to 10.0% by mass. A polyurethane foam characterized by the following features.

2. A urethane foam having a surface porosity of 1% or more and 45% or less on at least one surface, and an average surface cell diameter of 250 μm or less. A polyurethane foam characterized in that the water absorption per unit weight of the polyurethane foam, as measured by the following method, is 12 g / g or more. (Measurement method) Diluting 8.4 g of sodium chloride and 0.4 g of potassium chloride with distilled water to make a 1 L solution was used as the evaluation solution. A 50mm x 50mm piece of urethane foam will be used as the test specimen. Measure the weight A of the dry test specimen. The test specimen is immersed in an evaluation solution 40 times its weight A at 37°C for 30 minutes. After immersing the test specimen in the evaluation solution for 30 minutes, remove it from the solution, hang it for 20 seconds, and then measure the weight B of the test specimen. The amount of water absorbed can be calculated using the following formula. Water absorption amount = (weight B - weight A) / weight A

3. A urethane foam having a surface porosity of 1% or more and 45% or less on at least one surface, and an average surface cell diameter of 250 μm or less. A polyurethane foam characterized by having a water retention rate of over 60%, as measured by the following method. (Measurement method) Diluting 8.4 g of sodium chloride and 0.4 g of potassium chloride with distilled water to make a 1 L solution was used as the evaluation solution. A 50mm x 50mm piece of urethane foam will be used as the test specimen. Measure the weight A of the dry test specimen. The test specimen is immersed in an evaluation solution 40 times its weight A at 37°C for 30 minutes. After immersing the test specimen in the evaluation solution for 30 minutes, remove it from the solution, hang it for 20 seconds, and then measure the weight B of the test specimen. After suspending the test specimen for 20 seconds, apply a load to achieve a pressure of 40 mmHg. The weight C of the test specimen is measured two minutes after the load is applied. The water retention rate can be calculated using the following formula. Water retention rate = (weight C - weight A) / (weight B - weight A) x 100

4. A urethane foam having a surface porosity of 1% or more and 45% or less on at least one surface, and an average surface cell diameter of 250 μm or less. A urethane foam characterized by having a water absorption rate of 3 seconds or less, as measured by the following method. (Measurement method) Diluting 8.4 g of sodium chloride and 0.4 g of potassium chloride with distilled water to make a 1 L solution was used as the evaluation solution. At an ambient temperature of 25°C, 0.2 cc of a 37°C evaluation liquid is dropped onto a urethane foam from a height of 1 cm. The time from when the evaluation liquid is dropped until it is completely absorbed into the foam is defined as the water absorption rate.

5. A urethane foam having a surface porosity of 1% or more and 45% or less on at least one surface, and an average surface cell diameter of 250 μm or less. The aforementioned urethane foam contains polyurethane, which is a reaction product of polyisocyanate and polyol. The polyisocyanate comprises an aliphatic isocyanate, A polyurethane foam characterized in that its saturated swelling rate, as measured by the following method, is 300% or less. (Measurement method) Diluting 8.4 g of sodium chloride and 0.4 g of potassium chloride with distilled water to make a 1 L solution was used as the evaluation solution. Measure the dimensions of the test specimen when dry and calculate the volume A. The test specimen is immersed in an evaluation solution 40 times its weight at 37°C for 30 minutes. After immersing the test specimen in the evaluation solution for 30 minutes, remove it from the solution, measure its dimensions, and calculate its volume B. The swelling rate can be calculated using the following formula. Swelling rate = Volume B / Volume A × 100

6. The urethane foam according to any one of claims 1 to 4, characterized in that the saturated swelling rate measured by the following method is 300% or less. (Measurement method) Diluting 8.4 g of sodium chloride and 0.4 g of potassium chloride with distilled water to make a 1 L solution was used as the evaluation solution. Measure the dimensions of the test specimen when dry and calculate the volume A. The test specimen is immersed in an evaluation solution 40 times its weight at 37°C for 30 minutes. After immersing the test specimen in the evaluation solution for 30 minutes, remove it from the solution, measure its dimensions, and calculate its volume B. The swelling rate can be calculated using the following formula. Swelling rate = Volume B / Volume A × 100

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