JPH0326695B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a flexible polyurethane foam used in automobiles, furniture, bedding, or daily necessities. (Prior Art) Conventionally, flexible polyurethane foams have a problem in that they are susceptible to scorch phenomenon during summer production. This is because the room temperature is as high as 35-45℃ in summer, so the heat dissipation effect is low, and the internal temperature of the foam is 150-45℃.
It lasts for 3 to 4 hours at 160℃. This causes a scorch phenomenon in which the inside of the foam turns reddish-brown in color. Countermeasures against this scorch include adding scorch inhibitors, lowering the isocyanate index, and reducing the amount of water added, but these methods reduce reactivity, hardness, and increase cost.
Method (2) has disadvantages such as a decrease in hardness, and method (2) decreases urea bonds, resulting in a decrease in hardness and becoming rubber-like. In addition, the hardness of soft polyurethane foam decreases especially in the summer. Methods to improve the hardness include increasing the density and using polyfunctional, for example, tetrafunctional polyether polyols.
Method (2) has disadvantages such as low air permeability, no scorch countermeasure, and increased cost, and method (2) decreases elongation, tensile strength, and tear strength. (Problems to be Solved by the Invention) The purpose of the present invention is to improve hardness without increasing apparent density, maintain or improve elongation, tensile strength, and tear strength, and at the same time create a highly hard and flexible polyurethane that does not cause the scorch phenomenon. The goal is to provide a form. (Means for Solving the Problems) The present invention involves reacting a polyol component having at least a difunctional hydroxyl group and an at least difunctional polyisocyanate component in the presence of a blowing agent, a catalyst, and a foam stabilizer. In the flexible polyurethane foam obtained by using a polyol component, a mixed polyol consisting of a trifunctional polyol for flexible foam and an aromatic amine-based polyoxyalkylene polyol is used, and the proportion of the aromatic amine-based polyol in the total polyol component is 0.5 to 5. % by weight. As the trifunctional polyol for soft foam used in the present invention, all known polyester polyols and polyether polyols having a hydroxyl value (hereinafter referred to as OH value) in the range of 35 to 65 can be used, but in particular, polyester polyols and polyether polyols having an OH value of 56 to 65 can be used. Polyoxypropylene ether polyols or polyoxyethylene propylene ether polyols are preferred. Further, as the aromatic amine-based polyoxyalkylene polyol, which is another component of the mixed polyol used in the present invention, at least difunctional OH
It has a valence of 200 to 700, and is prepared by known methods such as aromatic monoamines such as aniline or 2,4- and 2,6-tolylene diamine (TDA) and so-called crude TDA, 4,4'-diaminodiphenylmethane. and one or more aromatic diamines and aromatic polyamines such as polymethylene polyphenylene polyamine, ortho-, meta- or para-phenylene diamine, meta- or para-xylylene diamine obtained by condensation of aniline and formalin, and propylene oxide. It is an at least bifunctional polyol obtained by adding one or more alkylene oxides such as ethylene oxide and ethylene oxide, and has substantially no free primary or secondary amines. GR-30 manufactured by Yakuhin Kogyo falls under this category. In addition, in order to reduce the viscosity of the aromatic amine-based polyol itself and improve processability, the following aliphatic glycols, amines, etc. may be used as co-initiators in addition to aromatic amines at the synthesis stage. can. For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane,
Examples include polyfunctional aliphatic glycols such as glucose, sorbitol, and sucrose, aliphatic amines and aliphatic alkanolamines such as ethanolamine, diethanolamine, triethanolamine, and ethylenediamine. It is preferable to use it in an equimolar amount or less. In the present invention, the ratio of the trifunctional polyol for soft foam and the aromatic amine-based polyol is preferably 95 to 99.5 parts (by weight, the same applies hereinafter) of the former to 0.5 to 5 parts of the latter. In the present invention, the benzene ring of the aromatic group of the aromatic amine-based polyol contributes to improving the hardness of the resulting soft urethane foam. If a slight decrease in elongation, tensile strength, or tear strength is observed in the foam made from these mixed polyols, it is preferable to use a diol having a molecular weight (MW) of 1000 to 2000 in combination with the above mixed polyol. Examples of diols include polyoxypropylene glycol of MW1000, MW2000
All known diols can be used, regardless of whether they are ethers or esters, up to polyoxypropylene glycol. In this case, it is preferable to use 85 to 98.5 parts of trifunctional polyol, 0.5 to 5 parts of aromatic amine-based polyol, and 1 to 10 parts of diol. As the polyisocyanate component used in the present invention, all known at least difunctional polyisocyanates can be used, but aromatic polyisocyanates are particularly preferred, such as 2, 4
- and 2,6-tolylene diisocyanate (TDI), orthotoluidine diisocyanate (TODI), naphthylene diisocyanate (NDI),
Xylylene diisocyanate (XDI), 4,4'-
Diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI (for example, Nippon Polyurethane Co., Ltd. MTL), polymethylene polyphenyl isocyanate (PAPI), polymeric polyisocyanate (for example, Sumitomo Bayer Urethane 44V), etc. can be used alone or in combination. can. In the present invention, when producing urethane foam by reacting polyols with isocyanates, etc., the isocyanate index is preferably 103 to 130, but can be increased or decreased as appropriate based on desired physical properties. Furthermore, the present invention can be applied not only to soft slab forms but also to mold forms. Furthermore, in the present invention, in order to produce a flexible polyurethane foam, a catalyst, a blowing agent, and a foam stabilizer are used.
Further, flame retardants, pigments, fillers, etc. may be used as necessary, but there are no particular restrictions on these, and all known ones can be used. (Example) Hereinafter, a detailed explanation will be given based on an example. Examples 1 to 9 Soft foams were foamed according to the following procedure using three times the amount of each of the formulations shown in Table 1. First, PPG3000 was placed in a beaker, heated to 28°C in a water bath, and GR-30 was added and mixed with stirring for 30 seconds. Next, diol, T-9, DABCO and water were added and stirred for 10 seconds, then TDI was added and stirred for 6 seconds to allow free foaming 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 measured using the ASTM D1564-64T method, the tensile strength, elongation, and tear strength were measured using the JIS K6301 method, and the 25% hardness was measured using the JIS K6401 method. Shown in the table. Comparative Examples 1 to 2 Foams were fabricated in the same manner as in the examples except for the case where only general-purpose PPG3000 was used as the polyol component (Comparative Example 1) and the case where a large amount of 11 parts of diol was used (Comparative Example 2). The sex was measured. The results are also listed in Table 1. In addition, in the table *1 Polypropylene polyol manufactured by Mitsui Nisso (trifunctional, MW3000, OH value 56) *2 Aromatic amine-based polyol manufactured by Takeda Pharmaceutical Company Limited (OH value 400) *3 Diol 2000 manufactured by Asahi Denka (MW2000, OH value
56) *4 Tin catalyst manufactured by Yoshitomi Pharmaceutical *5 Amine catalyst manufactured by Foodry *6 TDI-80 manufactured by Mitsui Nisso

[Table] (Effects of the invention) (1) Even by adding just 0.5 part of GR-30, the effect of improving hardness is observed as seen in Example 1.
If the blended amount of GR-30 is increased, the hardness increases in proportion to the blended amount, but as seen in Examples 2 and 3, a tendency for the strength and elongation properties, particularly elongation, to decrease is observed. (2) In order to prevent the deterioration of strength and elongation properties due to the addition of GR-30, it is effective to use linear diols as shown in Examples 4 to 9. When added, the closed cell content of the resulting foam increases and shrinkage occurs at the bottom of the foam block, making it impossible to obtain a good foam.

Claims (1)

[Scope of Claims] 1. A flexible polyurethane foam obtained by reacting a polyol component having at least difunctional hydroxyl groups and an at least difunctional polyisocyanate component in the presence of a blowing agent, a catalyst, and a foam stabilizer. In this method, a mixed polyol consisting of a trifunctional polyol for flexible foam and an aromatic amine-based polyoxyalkylene polyol is used as the polyol component, and the proportion of the aromatic amine-based polyol in the total polyol component is 0.5 to 5% by weight. High hardness and soft polyurethane foam. 2 As a polyol component, the molecular weight is 1000~
The polyurethane foam according to claim 1, in which a diol of 2000 is used in combination.