JPH0138130B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyurethane foam, and more specifically, to a method for producing polyurethane foam, which has little odor, enables uniform low-density curing foaming, and shortens molding time without causing burns even when used in combination with other catalysts. The present invention relates to a method for producing polyurethane foams using specific catalysts that enable the production of polyurethane foams. Catalysts are widely used in the production of polyurethane foams by reaction with polyisocyanates, polyols, and possibly other components; It is necessary to maintain balance and act competitively. One of the reactions that occur in the polyurethane manufacturing process is the reaction of polyisocyanates and polyols, which produces polyurethane, which results in chain extension and increased viscosity. Another reaction is the reaction of polyisocyanates with amines to create urea linkages and chain extension. Still other reactions involve reactions between polyisocyanates and urethane or urea groups, which produce allophanate or biuret bonds and increase the crosslink density of the polymer. Yet another reaction is the reaction of polyisocyanate with water, which generates foam with the evolution of carbon dioxide. This reaction of polyisocyanate with water is not necessarily essential when other blowing agents are used. In order to obtain an excellent form structure through these reactions, each reaction must be balanced.
If form generation is too fast compared to chain elongation, the form will collapse; conversely, if chain elongation is too fast compared to form generation, form generation will be restricted.
Control of these reactions depends on the selection of reaction conditions, but the selection of catalyst is most important. Many catalysts have been known for use in producing polyurethane foams, and they are selected depending on the physical properties required to exhibit various physical properties. Due to its ease of molding, polyurethane is currently being used in an extremely wide range of applications, including automobile parts, furniture, and footwear, and polyurethane is now required to have harsh properties. In other words, the molding time is short, the fluidity during foaming is good, the resulting polyurethane foam has low density, good low-temperature dimensional stability, low brittleness, and when integrally molded, Required properties include easy adhesion to objects, no staining or cracking in the resulting polyurethane, and low odor, but it has been impossible to satisfy all of these requirements.
For example, if a large amount of catalyst is added to shorten the molding time, the fluidity during foaming resin will be lost and the filling properties will be poor, and the resulting polyurethane foam will be prone to discoloration and cracks. It is not possible to achieve these required performances at the same time using . Furthermore, tertiary amines, which are conventionally widely used catalysts, are indispensable in the production of polyurethane foam using water as a blowing agent; It has significantly reduced its value. Therefore, the present inventors have made extensive research efforts to develop a catalyst that does not have such drawbacks and can exhibit the above-mentioned performances at the same time, and as a result, it has been discovered that a certain tertiary amine exhibits satisfactory performance. They discovered this and completed the present invention. That is, the present invention provides a method for producing polyurethane foam from a compound having at least two active hydrogen atoms and having a molecular weight of 400 to 10,000, a polyisocyanate, water and/or a blowing agent, and which includes the following general formula: (In the formula, n represents an integer of 6 to 10.) A method for producing a polyurethane foam is provided, which is characterized by using a catalyst represented by the following formula. Compounds of formula [ ] according to the present invention can be produced by a number of methods using known synthetic techniques. The compound of formula [] according to the present invention is an alkyldimethylamine, and the alkyl group thereof has 6 to 10 carbon atoms, and is preferably a straight chain, but may be a branched one, or a mixture of both. It doesn't matter what you did. The reason why the number of carbon atoms is so narrowly limited is that if the number of carbon atoms in the alkyl group exceeds 10, the activity as a catalyst decreases, making it impossible to achieve the purpose of shortening the molding time.
Furthermore, if the number of carbon atoms in the alkyl group is less than 6, the odor will be significant. When the compound of formula [] according to the present invention is used, the produced polyurethane foam has no amine odor, and it is possible to shorten the molding time. In addition, it has excellent fluidity when forming into a foam molded resin, and the resulting polyurethane foam has good dimensional stability, low brittleness, no burning or cracking, and the polyurethane foam can be made uniform with high foaming (low density). can. In addition, when integrally molded, a polyurethane foam can be obtained that exhibits good adhesion to adherends when molding sandwich panels, boxes, etc. The compound of formula [] according to the present invention is used in a catalyst in combination with a tertiary amine such as triethylenediamine, N,N,N',N'-tetramethylalkylenediamine or polyN-methylpolyalkylenepolyamine. You can also do that. When used in combination, the ratio of the compound of formula [] to these amines is from 100:1 to 1:100. In the production of high-density urethane, especially hard high-density urethane, attempts to shorten the molding time by using triethylene diamine, tetramethylalkylene diamine, or polyN-methylpolyalkylene polyamine as a catalyst will cause discoloration and cracking, but the formula according to the present invention When the compound [] is used in combination, the molding time can be shortened without causing any burns or cracks. Further, the compound of formula [] according to the present invention can be used in combination with a tin-based catalyst. In order to shorten the molding time, if a tin-based catalyst that promotes the resin formation reaction is used, the curing speed will be increased, but the fluidity will be poor and the mold filling performance will be poor. Therefore, tin-based catalysts such as triethylenediamine and N, N, N′, N″, N″-
Pentamethyldiethylenetriamine has also been used in combination, but there are disadvantages such as poor filling properties, high brittleness, and peeling from the adherend when demolding. However, when the compound of the formula [] according to the present invention is used in combination with a tin-based catalyst, it promotes the resin formation reaction, has good fluidity, has excellent filling properties, has low brittleness, has good adhesion, and It will not peel off from the body. Known tin compounds that can be used in combination include:

[Formula] (In the formula, R ₁ is an alkyl group, an aryl group, or an alkylaryl group having 1 to 17 carbon atoms.)

[Formula] (In the formula, R ₂ is an alkyl group having 1 to 8 carbon atoms, R ₃ is an alkyl group having 1 to 17 carbon atoms, or an aryl group, or an alkylaryl group, or -CH=COOR ₄ , and R ₄ is a carbon number 1-18 alkyl group)

[Formula] (wherein R ₅ is an alkyl group having 1 to 8 carbon atoms, and R ₆ is an alkyl group having 2 to 18 carbon atoms). Among these, preferred are dibutyltin diacetate, dibrutin dilaurate, dibutyltin bis(monolauryl malate), and dibutyltin dimercaptolaurate. These tin compounds are used in an amount of 0.01 to 100% by weight, preferably 0.1 to 10% by weight of the compound of general formula []. In producing polyurethane foam according to the present invention, it is of course necessary to use a substance that forms bubbles, but as is well known, such a substance reacts with polyisocyanate to generate carbon dioxide. A blowing agent that does not take part in the polyurethane production reaction is used. Any known blowing agent can be used, and preferably low-boiling halogenated hydrocarbons, which are liquid at room temperature and vaporize during the polyurethane production reaction, are used. Although the water and the blowing agent may be used alone, it is preferable to use both in combination. In addition, in the present invention, if necessary, molecular weight 32
It is of course possible to use a polyfunctional compound of up to 400 as a conventional chain extender, and the properties of the resulting polyurethane foam can be adjusted as appropriate by using this chain extender. In the present invention, it is preferable to use a surfactant during the production of polyurethane foam to improve cell uniformity and cell retention. As such surfactants, silicon-based surfactants are mainly used, and fluorine-based and ionic-based surfactants are used in combination as appropriate. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts in the examples are based on weight. Example 1 100 parts polyether polyol with hydroxyl number 450, N%, 1.4, viscosity 8000 centipoise at 25°C obtained by addition reaction of polypropylene oxide with a mixture of sucrose, ethanolamine and water, 1.5 parts water, silicone-based Surfactant [Toray Silicon SH-193, Toray Silicon Co., Ltd.] 1.5 parts,
Each part of the catalyst shown in Table 1 and 40 parts of monofluorotrichloromethane [Freon 11B, Mitsui Fluorochemical Co., Ltd.] were mixed. This mixture and crude 4,4'-diisocyanate diphenylmethane [Sumidyur 44V-
20, NCO content 30.7%, Sumitomo Bayer urethane
Ltd.] were mixed under the same conditions in a rotor-stirring urethane foaming machine (mixer rotation speed 4000 rpm) at a ratio such that the isocyanate index (isocyanate equivalent/active hydrogen equivalent that can react with isocyanate) = 1.05. Injected into the mold. Cream time, gel time, tack free time, rise time, free foam density, surface brittleness after foam hardening, odor during foaming and foam,
15cm x 15cm for evaluating adhesion to adherends
120g was injected from the above foaming machine into an upper oven wooden mold with a 0.03mm polyethylene film pasted on the inside of x30cm (height) and 0.5mm thick stainless steel plates degreased on two sides perpendicular to the polyethylene wall set inside. did. mold temperature,
The temperature of the aluminum plate, the temperature of the stock solution in the foaming machine, and the air temperature were all 25°C. 40cm (width) x 60 for measuring foam filling properties (flowability) and low-temperature dimensional stability of foams
280 g of the mixture was poured from the foaming machine into a sealable aluminum mold measuring cm (height) x 3.5 cm (thickness) with a 0.03 mm polyethylene film attached to the inside. The mold temperature, the temperature of the stock solution in the foaming machine, and the air temperature were all 25°C. Table 1 shows the results of measurements using the reaction system in which the catalyst of the present invention and the known catalyst were added in the same amount and gel time, and in the same molar concentration of N,N-dimethylalkylamine. In addition, in the catalyst name abbreviations in the table, TEDA is triethylenediamine, DMCA is N,N-dimethylcyclohexylamine, DMEA is N,N-dimethylethanolamine, DMBA is N,N-dimethylbenzylamine, C ₄ , C ₆ , C ₈ , C ₁₂ , C ₁₄ , C ₁₆
is a general formula

[Formula], each n=4, 6, Showing 8, 10, 12, 14, 16.

【table】

【table】

[Table] Example 2 Using the same raw materials as in Example 1, the blending ratio was 100 parts of polyether polyol, 0.4 parts of water, 1.0 parts of silicone surfactant, 24 parts of monofluorotrichloromethane,
Each part of the catalyst shown in Table 2 was mixed. This mixture and crude 4,4'-diisocyanate diphenylmethane were mixed in a ratio of 20% to give an isocyanate index of 1.05.
Pour 14Kg into a plastic bucket, stir for 15 seconds with a Kikusui auto mixer [MK-120 type 1100r.pm blade diameter approx. 12cm, Kikusui Chemical Co., Ltd.], and then mix the 13.5Kg into a 90cm x 90
Injected into a wooden mold measuring 30cm x 30cm (height) with 0.03mm polyethylene film pasted on the inside, clamped with an electric press (manufactured by Hanamiko Seisakusho, mold clamping area 1m x 2m), and after 60 minutes and 90 minutes. It was demolded. The dimensions of the molded product after demolding and the center of the molded product are 90cm x
It was cut to 45cm x 30cm and the internal condition was observed. In addition, a 0.03 mm polyethylene film was pasted inside the same mold, and a 0.5 mm thick degreased stainless steel plate was set on the polyethylene wall, and 10 kg of the above mixed solution was poured into the oven above the mold to produce cream time, gel time, and tack-free molding. Time, rise time, free foam density, surface brittleness after foam hardening, and adhesion to a stainless steel plate were measured. The mold temperature, raw material liquid temperature, and air temperature were all 20°C. Table 2 shows the results of measurements of the catalyst system of the present invention and the known catalyst system in reaction systems with the same tack free time. In addition, in the catalyst name abbreviations in the table, TEDA is triethylenediamine, TMHD is N,N,N',N'-tetramethylhexamethylenediamine, _C8 is N,
N-dimethyloctylamine, Sn indicates dibutyltin dimercaptolaurate.

【table】

【table】

Claims (1)

[Claims] 1. A method for producing polyurethane foam from a compound having at least two active hydrogen atoms and having a molecular weight of 400 to 10,000, polyisocyanate, water and/or a blowing agent, which comprises the following general formula: (In the formula, n represents an integer of 6 to 10.) A method for producing polyurethane foam, characterized by using a catalyst represented by the following formula.