JPH0126608B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing high hardness and soft urethane foam for use in automobiles, furniture, bedding, and daily necessities. (Prior Art) Soft polyurethane foams have so far been produced with apparent densities in the range of 10 to 50 kg/m ³ , of which foams with apparent densities of 14 to 25 kg/m ³ are the mainstream. For foams in this apparent density range, there is generally a proportional relationship between apparent density and hardness, and the higher the apparent density, the greater the hardness.
Usually commercially available ones have a JIS hardness of 5.5 to 13.5 kg.
The form ranges from . Recently, there has been a strong demand for weight reduction in various application fields including the automobile field, and research has begun from various angles on technology that can stably produce foams with increased hardness without increasing apparent density. . As strategies for this, methods such as the combination of polyols having four or more functional functions, high isocyanate index, increasing the amount of water blended, and combination of polymer polyols are being considered. However, method (2) has the disadvantage that the strength and elongation properties and compression set properties decrease, and method (2) generates significant heat during the reaction, which tends to cause scorch inside the foam, and in some cases, there is a risk of ignition. There were some difficulties involved. Further, the other methods have disadvantages in that the obtained foam has poor heat resistance and tends to cause scorch, and none of the methods has reached the point where it can be used as a decisive factor. On the other hand, as a polyol for polyurethane, 2,
The technology using a propylene oxide adduct of 2-bis(4-hydroxyphenyl)propane (hereinafter abbreviated as bisphenol A-PO adduct) was disclosed in JP-A-Sho.
Although it is known from No. 59-47223, the bisphenol A-alkylene oxide adduct has poor compatibility with polyols for flexible urethane foams and has a high viscosity, which has the drawback of significantly reducing the strength and elongation properties of the obtained foam. Because of this, it was only used for hard urethane foam. (Problems to be Solved by the Invention) The present invention overcomes the various drawbacks of the prior art as described above, and solves the problem of high viscosity bisphenol A-PO which has poor compatibility with polyols for flexible foams, especially trifunctional polyols. Adducts and ethylene oxide adducts of bisphenol A (hereinafter abbreviated as EO adducts)
It facilitates the mixing of alkylene oxide adducts of bisphenol A (hereinafter referred to as bisphenol A-RO adducts), while maintaining the strength and elongation properties of the obtained foam without increasing the foam density. The object of the present invention is to provide a method for manufacturing a soft urethane foam that can stably improve hardness. (Structure of the Invention) There are no particular restrictions on the polyol for general-purpose flexible urethane foam used in the present application, and all known polyether polyols and polyester polyols can be used. Polyoxyalkylene ether polyols are preferred. Bisphenol A-RO adduct is obtained by reacting 2,2-bis(4-hydroxyphenyl)propane, that is, 1 mole of bisphenol A, with 2 or more moles of alkylene oxide, but the alkylene oxide is ethylene oxide or propylene oxide. is commonly used. This bisphenol A-RO adduct may be commercially available as BISOL-2P manufactured by Toho Chiba Chemical, or Newpol BP or Newpol BPE manufactured by Sanyo Chemical Industries. The amount of the bisphenol A-RO adduct added must be in the range of 0.5 to 5 parts by weight, preferably 1 to 4.5 parts by weight, based on 80 to 99.5 parts by weight of the general-purpose polyol for flexible urethane foam. If the amount added is less than 0.5 parts by weight, there is no hardness increasing effect, and if it is more than 5 parts by weight, the hardness increasing effect becomes large, but closed cells tend to form and the strength and elongation properties decrease significantly. However, this is because only the so-called "deep" form can be obtained.
This bisphenol A-RO adduct has poor compatibility with polyols for flexible urethane foams, especially trifunctional polypropylene glycol, and even if the two components or the three components with the diol are mixed and stirred at 25°C or lower, it does not easily form a uniform layer. It won't be. This is not simply due to the high viscosity of the bisphenol A-RO adduct, but is an essential compatibility issue. However, polyol for soft urethane foam
A uniform mixed layer can be easily obtained by heating to 25°C or higher. However, if the heating temperature of the polyol for flexible urethane foam is too high, the reaction with the polyisocyanate will progress too quickly, and if a low boiling point blowing agent such as Freon is used, the volatilization loss will be significant. It is necessary to keep the temperature range below ℃. In the present invention, it is necessary to add a diol as described above, but the diol has a molecular weight of 106 to
2000, and the amount added is preferably in the range of 2 to 15 parts by weight per 80 to 99.5 parts by weight of the polyol for flexible urethane foam. If the amount of diol added is less than 2 parts by weight, the effect of improving strength and elongation properties will be poor, and if it is added in excess of 15 parts by weight, the resilience of the foam against compression will decrease, so it should be avoided for use in cushions. Diols to be added range from low molecular weight ones such as diethylene glycol 1,6-hexane diol to polyoxypropylene glycol with a molecular weight of 2000, and among known diols, those with a molecular weight in the range of 106 to 2000 can be used as ether, All can be used regardless of ester. Note that a single diol may be used, but a combination of a short chain diol and a long chain diol, for example diethylene glycol with a molecular weight of 106 and a diol with a molecular weight of 2000, can also be used in combination. However, when using a short chain diol having an OH value of 400 or more, the foam tends to shrink unless the total amount with the bisphenol A-RO adduct is less than 7 parts by weight, preferably 5 parts by weight or less. All known catalysts, foam stabilizers, blowing agents, polyisocyanates, etc. used in this application can be used for flexible urethane foam, and known flame retardants, fillers, colorants, etc. may also be appropriately blended as necessary. can do. (Example) Example A soft foam was foamed in the following procedure using three times the amount of each of the formulations shown in Table 1. First, take PPG3000 in a beaker, warm it to 28℃ in a water bath, add BISOL-2P, and heat it for 30 minutes.
Stir and mix for seconds. Next, add diol, T-9, DABCO and water and stir for 10 seconds, then add TDI and add 6
The mixture was stirred for seconds and allowed to foam freely in a metal container measuring 30 x 30 x 30 cm. After heating the obtained foam at 100℃ for 10 minutes
After leaving at room temperature for 24 hours, the apparent density was determined by the method of ASTM D1564-64T, the hardness was determined by the method of JIS K6401, and the tensile strength, elongation rate, and elongation were determined by the method of JIS K6301.
The results of measuring tear strength are shown in Table 2. still,
Experiment Nos. 1 to 2 and 6 in the table are reference examples.
Nos. 3 to 5 and 7 to 8 are examples. Comparative Example A foam was prepared and its physical properties were measured in the same manner as in the example except that only the general-purpose polyether triol PPG3000 was used as the polyol component. The results are also listed in Tables 1 and 2.

【table】

[Table] * Due to significant closed cells, shrinkage made it impossible to measure physical properties (Effects of the invention) (1) Experiment No. 1 even when just 0.5 part of BISOL-2P was added
As can be seen, the effect of improving hardness is recognized. If the amount of BISOL-2P blended is increased, the hardness will increase in proportion to the amount blended, but as seen in Experiment No. 2, there was a tendency for the strength and elongation properties, especially elongation, to decrease, resulting in the so-called "drilling". It becomes a form. Furthermore, in Experiment No. 6, in which the amount of BISOL-2P was increased to 5.5 parts, even if 11 parts of DIOL1000 were used together, closed cells would result, making it impractical, so the amount is limited to 5 parts or less in practice. This is because hard segments having two benzene nuclei, such as bisphenol A, are effective in improving hardness, but if the ratio of hard segments becomes too large, flexibility is adversely affected. (2) To prevent the deterioration of strength and elongation properties due to the addition of BISOL-2P, it is effective to use linear diols as shown in Experiment Nos. 3 to 5, but adding 10 parts or more of diols is effective. As a result, the closed cell content of the obtained foam increases and shrinkage occurs below the foam block, making it impossible to obtain a good foam. Experiment No. 6 is an example in which physical property measurements could not be carried out due to significant foam shrinkage. (3) When using diols together, it is desirable to use short chain diols such as diethylene glycol (molecular weight 106.2) and long chain diols with a molecular weight of 1000 or more, as seen in Experiments No. 7 and 8. If the total amount of both is less than 15 parts, shrinkage can be prevented without impairing the effect of improving hardness and strength/elongation properties. However, even in this case, care must be taken because if the total amount is increased to 15 parts or more, not only will the anti-shrinkage effect decrease, but the compression set characteristics of the foam will also deteriorate. As is clear from the above explanation, by adding 0.5 to 5 parts by weight of bisphenol A-RO adduct and 2 to 15 parts by weight of diol to a general-purpose polyol, the JIS hardness can be increased by 1% without increasing the foam density. Since the weight can be increased by ~3 kg, it can be said to be an extremely useful technology industrially.

Claims (1)

[Claims] 1 2 to 15 parts by weight of an alkylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane is added to 80 to 99.5 parts by weight of a general-purpose polyol for flexible urethane foam heated to 25 to 35°C. A method for producing a highly hard and flexible urethane foam, which comprises mixing and foaming a catalyst, a foam stabilizer, a blowing agent, a polyisocyanate, etc. in the presence of a diol.