JPH11322875A - Urethane foam and its manufacturing method - Google Patents

Abstract

(57) [Problem] To provide a urethane foam capable of reducing a deflection difference in a load deflection curve and lowering a resonance frequency as compared with a conventional cold-cured polyurethane foam. SOLUTION: A raw material of a cold cure urethane foam mainly composed of a polyol and an isocyanate component is used as a foam stabilizer and has a perfluoroalkyl group structure.
The surface tension of the aqueous solution when 1% is added is 13 to 40 (dyne)
/ Cm25 ° C), and the cell obtained by adding a fluorine-based surfactant having a surface tension of 25 (dyne / cm25 ° C) or less at the time of addition of 0.1% of the toluene solution and foaming the resulting mixture is coarse and irregular. It is urethane foam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a urethane foam suitable for a pad material such as a vehicle seat cushion and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a seat cushion, a combination of a metal spring and a pad material made of polyurethane foam has been frequently used. The sheet using both the metal spring and the polyurethane foam had a relatively large difference in deflection due to the linear load deflection characteristic of the metal spring, and was a sheet having a stroke without bottom feeling.

However, recently, due to demands for cost reduction and weight reduction, a so-called full-form type automobile seat, in which a metal spring is eliminated by giving a polyurethane foam itself a spring property, tends to be adopted. Cold-cured polyurethane foams formed by mold foaming are also called HR foams because of their softness and high resilience (High Resiliency), and have been widely used as pad materials for automobile seat cushions and the like.

[0004] Since the cold-cure polyurethane foam used for the full-form type pad material is thicker than a polyurethane foam used in combination with a conventional metal spring, the performance of the polyurethane foam itself is reduced by the performance of the seat cushion. Will be greatly affected.

[0005]

The urethane foam is:
The cell structure makes the load deflection curve non-linear.
When a person actually sits on the seat provided with the urethane foam pad material, the urethane foam is compressed and the position of the flexure, buttocks and the like sinks to a specific height. As a substitute numerical value representing the sink, JISE7104 as shown in FIG.
The deflection value when a 500N load (N: Newton) is given by a pressure plate P conforming to the above may be used. The pressing plate P has a major axis A: 300 mm and a minor axis B: 2
It is an oval with a thickness of 50 mm and a thickness C of 35 mm or more, and is called a so-called iron plate.

In the sheet having the full-form structure described above, the load deflection characteristics are greatly affected by the polyurethane foam itself, and when the load deflection when pressed from above by the pressure plate P is measured, it is found that the pressure side is 500N to 900N.
The sheet has a relatively small deflection difference.

[0007] Since the seat having a small difference in deflection has a feeling of bottoming, the evaluation of ride comfort is poor. Therefore, in the case of a full-form type sheet, the thickness of the foam has to be increased in order to increase the difference in deflection. In addition, in order to increase the difference in deflection with the same hardness in the cold cure urethane foam, it is necessary to increase the density. In this case, problems such as an increase in cost and an increase in the weight of the sheet occur.

Accordingly, it is an object of the present invention to provide a feeling of bottoming without increasing the density as compared with the conventional cold cure urethane foam, a large difference in deflection in a load deflection curve, and a reduction in resonance frequency. It is to provide a possible urethane foam.

[0009]

According to the present invention, there is provided a cold-cure polyurethane foam in mold foaming, wherein the urethane foam according to claim 1 has a large deflection difference in a load deflection curve. I will provide a. That is, the flexible / high-elastic urethane foam of the present invention has a perfluoroalkyl group structure as a foam stabilizer and a surface tension of an aqueous solution of 0.1% when added to a raw material mainly composed of a polyol and an isocyanate component. 40 (dyne / cm25 ° C.), the surface tension of the toluene solution at the time of addition of 0.1% is 25 (dyne / cm2).
(5 ° C.) or less. The intended purpose of the present invention cannot be achieved with a foam stabilizer that deviates from this surface tension range.

[0010] In the production method of the present invention, the cell is prepared by adding the above-mentioned fluorine-containing surfactant as a foam stabilizer to a raw material of a cold cure urethane foam mainly composed of a polyol and an isocyanate, and stirring and foaming. It is characterized by obtaining a urethane foam which is coarse, has an irregular cell shape and size, and leaves many cell films.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyol used as a raw material of the cold cured urethane foam (HR foam) of the present invention comprises:
Any type used in the production of ordinary polyurethane foams may be used. For example, a polymer polyol, a polyether polyol, a polyester polyol, or the like is used, and these may be mixed. The polyol has a hydroxyl value of 20 to 150 (mgKOH / g),
Preferably, a range of 20 to 60 (mgKOH / g) is recommended.

As the polyisocyanate component used in the present invention, any polyisocyanate having at least bifunctionality can be used, and aromatic polyisocyanates are particularly preferable.
6-tolylene diisocyanate (TDI), 4,4'-
Diphenylmethane diisocyanate (MDI) or the like can be used alone or in combination.

[0013] The cross-linking agents are those generally used so far (the number of functional groups is 2 to 6, the hydroxyl value is 500 to 2).
000 (mg KOH / g)).
As a catalyst, a general amine catalyst or a metal catalyst may be used in some cases, and water is usually added (1 to 6 parts).
Can be used with

According to the present invention, a fluorine-based surfactant having a perfluoroalkyl group structure is used as a foam stabilizer in an amount of 0.000 to 0.000.
It is characterized by using 1 to 5 parts. This foam stabilizer has an aqueous solution (at the time of 0.1% addition) having a surface tension of 13 to 40 (dy).
ne / cm 25 ° C.) and the surface tension of the toluene solution (at the time of adding 0.1%) is specified to be in a range of 25 (dyne / cm 25 ° C.) or less.

Incidentally, a foam stabilizer for cold cure urethane foam which is usually used may be used in combination. If necessary, a cell opener for cold cure urethane foam which is usually used may be used.

In the present invention, by adding the above-mentioned fluorine-based surfactant (surfactant having a perfluoroalkyl group) to the raw material of cold-cure urethane foam, it can be compared with a conventional general cold-cure urethane foam. As a result, it was possible to produce a urethane foam in which the cells were coarse, the cell shape and cell size were irregular, and many cell films remained.

In FIG. 1, the load deflection curve shown by a solid line shows the characteristics of a cold cure polyurethane foam obtained by the present invention, and the load deflection curve shown by a broken line shows the characteristics of a conventional general cold cure polyurethane foam. The product of the present invention has such a characteristic that the center portion of the load deflection curve falls slightly in the horizontal direction as compared with the conventional product, and the difference in deflection could be increased.

When a vehicle seat receives an impact from a road surface during traveling, urethane foam as a pad material becomes
Vibrates up and down from a position compressed to some extent by sitting. In this case, a pad material using a urethane foam having a small spring constant (inclination of load deflection curve) at 500 N as in the case of the present invention becomes a sheet having a large stroke without a feeling of bottoming. In other words, it is possible to reduce the thickness of the pad material while maintaining the same cushioning performance as the conventional pad material.

Reducing the dynamic spring constant when vibration is applied leads to a reduction in resonance frequency. The resonance frequency of an automobile seat is usually in the range of 3 to 4.5 Hz, and lowering the resonance frequency leads to a reduction in the vibration of 4 to 8 Hz, which is a built-in resonance point of the human body, thereby improving ride comfort. . Table 1 shows Examples 1 and 2 of the present invention.
And Formulations of Comparative Examples 1 and 2 (conventional general-purpose cold cure polyurethane foam).

[0020]

[Table 1]

The foaming conditions of Examples 1 and 2 and Comparative Examples 1 and 2 are as follows. Mixing method: Hand mixing Stirring blade rotation speed: 5,800 rotations / minute Liquid temperature: 25 ± 1 ° C. Die: 500 × 500 × 100 mm aluminum test piece Box type, Mold temperature: 60 ± 2 ° C. Cure time: 6 minutes Foaming In the method, after premixing components other than the isocyanate, the isocyanate was added, stirred for 5 seconds, and injected into a mold.

The polyols (XOP-2849, XNP-4297) used in Examples 1 and 2 and the polyols (EP-3033, POP-31 / 28) used in Comparative Examples 1 and 2 have trade names of each other. Different but substantially nearly equivalent polyols. The amine catalysts (A-107, A-1) have substantially different but different product numbers. The additives (EP-505s, DOA, SF-2969) were used to improve the moldability and air permeability of Examples 1 and 2, but the physical properties (foam with a large difference in deflection) according to the object of the present invention were obtained. Above is not mandatory. The foam stabilizer (L-5309) added to Comparative Examples 1 and 2 may be added to Examples 1 and 2.

Examples 1 and 2 in which the specific foam stabilizer (N-98) was added were Comparative Examples 1 and 2 in which this foam stabilizer was not added.
As compared with No. 2, a significant effect was obtained in increasing the deflection difference in the load deflection curve as described later, and a significant effect was also observed in improving the vibration characteristics.

The foams were actually foamed according to the formulas and foaming methods of Examples 1 and 2 and Comparative Examples 1 and 2, and the physical properties, static load, damping properties and vibration characteristics of the foams were measured and evaluated.
Shown in

[0025]

[Table 2]

In the measurement results of Table 2, the thickness was 100 mm.
Comparing the foams of Example 1 (Example 1 and Comparative Example 1), the deflection amount at 500 to 900 N on the pressure side of Example 1 was 28.2 m.
m was 22.9 mm in Comparative Example 1, which was about 25% larger in Example 1. With respect to the density, Example 1 was slightly smaller than Comparative Example 1. Regarding the vibration characteristics, the transmissivity at 6 Hz in Example 1 was 0.5
7, the transmission rate at 6 Hz of Comparative Example 1 was 0.77, and
It was found that the transmission rate of 6 Hz near the built-in resonance point of the human body was smaller, and that the riding comfort could be improved.

When compared with the foam having a thickness of 80 mm (Example 2 and Comparative Example 2), the pressure side of Example 2 is 500 to 900.
The deflection amount at the time of N was 21.1 mm, whereas that of Comparative Example 2 was 17.2 mm, which was about 25% larger in Example 2. As for the density, Example 2 was slightly smaller than Comparative Example 2. Regarding the vibration characteristics, the transmissivity at 6 Hz in Example 2 was 0.70, the transmissivity at 6 Hz in Comparative Example 2 was 1.02, and the transmissivity at 6 Hz in Example 2 was closer to the built-in resonance point. It is getting smaller.

When comparing Example 2 with Comparative Example 1, Example 2 has a slightly lower deflection on the press side at 500 N than that of Comparative Example 1; Were almost the same. Both were almost equivalent in density. Example 2 is slightly inferior to Comparative Example 1 with respect to the deflection difference of 500 to 900 N on the pressure side,
In terms of vibration characteristics, Example 2 is better than Comparative Example 1. In other words, the product of the present invention has a foam thickness of 20 mm compared to a conventional general-purpose foam (thickness of 100 mm).
Even when the distance was reduced to 80 mm, performance almost equivalent to that of the conventional product could be maintained.

[0029]

According to the present invention, when compared with a conventional general-purpose cold cure urethane foam (soft high-elasticity foam), when the thickness is reduced, there is no sense of bottoming even if the density is not increased, and the load deflection diagram. Can be made large, and the stroke can be made large. Therefore, it is possible to reduce the thickness while maintaining the same cushioning performance as the conventional general-purpose urethane foam. Moreover, since the dynamic spring constant with respect to vibration is reduced and the resonance frequency is lowered, for example, when applied to a vehicle seat, the vibration of 4 to 8 Hz, which is a resonance point built in the human body, can be reduced, and the riding comfort is improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing load deflection curves of a urethane foam of the present invention and a conventional product.

FIG. 2 is a perspective view of a pressure plate for measuring a difference in deflection according to JISE7104.

Claims (2)

[Claims] 1. A raw material of a cold cure urethane foam mainly composed of a polyol and an isocyanate component, which is used as a foam stabilizer and has a perfluoroalkyl group structure of 0.1%.
% When the surface tension of the aqueous solution is 13 to 40 (dyne /
A urethane foam to which a fluorine-based surfactant having a surface tension of 25% or less (dyne / cm25 ° C) of a toluene solution at the time of addition of 0.1% is added. 2. A raw material for a cold cure urethane foam mainly composed of a polyol and an isocyanate component, which is used as a foam stabilizer and has a perfluoroalkyl group structure of 0.1%.
% When the surface tension of the aqueous solution is 13 to 40 (dyne /
A method for producing a urethane foam, comprising adding a fluorine-based surfactant having a surface tension of 25 (dyne / cm25 ° C.) or less of a toluene solution at the time of addition of 0.1%, stirring, and foaming. .