JPS6131726B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a urethane-modified rigid isocyanurate foam, and more specifically, a urethane-modified rigid isocyanurate foam having a homogeneous fine cell structure with low brittleness and excellent heat resistance and flame retardance. Relating to a manufacturing method. It is already known to trimerize polyisocyanates in the presence of catalysts to produce rigid isocyanurate foams containing isocyanurate rings. Since this hard foam has isocyanurate rings, it is generally superior to urethane foam in terms of heat resistance and flame retardancy. On the other hand, conventional hard isocyanurate foams are not only highly brittle but also difficult to control reactions during manufacturing.
Since the foam-forming reaction occurs non-uniformly, it does not have a homogeneous fine cell structure and is hardly of practical use. In order to improve the above-mentioned drawbacks, when trimerizing polyisocyanate, by coexisting a polyol containing hydroxyl groups less than the equivalent of the isocyanate group, urethane bonds are introduced into the polymer chain, and urethane-modified hard isocyanate It has been proposed to produce nurate foams. but,
Even with this manufacturing method, the brittleness of the hard foam obtained is not sufficiently improved, and furthermore, it is difficult to control the reactivity during manufacturing, and in particular, the hardening of the foam surface is difficult compared to the hardening of the inside of the foam. Because of the slow curing, a foam with a homogeneous and fine cell structure could not be obtained. Attempts have been made to improve these drawbacks by using a large amount of polyol, but this results in a problem of reduced heat resistance and flame retardancy. The present invention was made to solve the above-mentioned problems, and has low brittleness, heat resistance,
A urethane-modified hard isocyanate that can obtain a hard foam with a homogeneous fine cell structure with excellent flame retardancy, and also allows the reactivity of the curing reaction to be adjusted depending on the use of the hard foam. An object of the present invention is to provide a method for manufacturing Nurate foam. The present invention provides at least one organic polyisocyanate selected from the group consisting of polyphenylene polymethylene polyisocyanate and diphenylmethane diisocyanate, at least one glycol selected from the group consisting of ethylene glycol and diethylene glycol, and trimethylol. A polyether triol with a hydroxyl value of 200 to 1000 mgKOH/g obtained by adding ethylene oxide to propane is used, and the hydroxyl equivalent of the glycol and the hydroxyl equivalent of the polyether triol are each 0.05 to 1,000 to 1 equivalent of the isocyanate group of the organic polyisocyanate. 0.8, and the reaction is carried out in the presence of a catalyst consisting of triethylenediamine and an epoxy compound, a blowing agent, and a foam stabilizer such that the total value of both does not exceed 1. The organic polyisocyanate used in the present invention is polyphenylene polymethylene polyisocyanate, diphenylmethane diisocyanate, and mixtures thereof, preferably polyphenylene polymethylene polyisocyanate. Here, polyphenylene polymethylene polyisocyanate is also called crude MDI (C-MDI), and is a mixture of polynuclear polyisocyanates represented by the following formula, and the average value of n is usually:
It is 0.1-1.3. In addition, prepolymers obtained by reacting these organic polyisocyanates described above with various active hydrogen compounds, preferably polyols described below, in a state with an excess of isocyanate groups, partial allophanatization, trimerization, etc. of these organic polyisocyanates, Carbodiimidized modified isocyanates are also preferably used. Isocyanates other than the organic polyisocyanates specified above are not suitable for producing rigid foams with excellent physical properties according to the present invention. The polyol used in the present invention has a hydroxyl value of 200 to 1000 mgKO obtained by adding ethylene oxide to at least one glycol selected from the group consisting of ethylene glycol and diethylene glycol, and trimethylolpropane.
H/g, particularly preferably 300 to 500 mgKOH/g, and these polyols contain 0.05 to 0.8 equivalents, preferably 0.1 to 0.5 equivalents of the above glycol per equivalent of isocyanate group. , the above polyether triol is
0.05 to 0.8 equivalents, preferably 0.1 to 0.5 equivalents, and the amount does not exceed 1 equivalent in total, preferably 0.1 to 0.5 equivalents.
0.85 equivalents are used, particularly preferably 0.2 to 0.7 equivalents. Alkylene glycols, polyalkylene glycols such as propylene glycol, dipropylene glycol, polypropylene glycol, etc.
Polyester polyols have poor reactivity, require a large amount of catalyst when reacting with organic polyisocyanates, and do not form a rigid foam having a homogeneous and fine cell structure. In addition, the hydroxyl value
A polyether polyol of 200 mgKOH/g or less also requires a large amount of polyether polyol or catalyst to obtain the reactivity necessary for foam formation, which reduces the heat resistance and flame retardance of the resulting hard foam. Not suitable for use in In the present invention, the blending ratio of the above-specified polyol to the organic polyisocyanate is appropriately selected within the above-mentioned range depending on the use of the rigid foam. On the other hand, the use of diethylene glycol speeds up the foam-forming reaction, so by appropriately combining the two, it is useful to adjust the reactivity of the reaction system over a wide range according to the purpose without impairing the physical properties of the foam. Ethylene oxide adducts to trimethylolpropane also help improve the hardenability of the foam surface. Generally, in the formation reaction of a cured isocyanurate foam, the reaction on the surface is slower than that inside the foam, and if a gradual reaction is attempted to form the foam, the surface of the foam will be insufficiently hardened and the surface will not be homogeneous. I can't get the form. Also, the resulting foam is brittle. On the other hand, if a foam is formed by rapid reaction, it becomes difficult to inject the resin liquid into the mold and the foaming pressure increases, making it difficult to apply to cast molding. According to the present invention, the hardenability of the foam surface can be improved by adding an ethylene oxide adduct to trimethylolpropane, and at the same time, the reactivity of the reaction system can be adjusted by using ethylene glycol and diethylene glycol. Accordingly, a homogeneous rigid foam can be manufactured while ensuring appropriate reactivity. Next, the trimerization catalyst used in the present invention is a catalyst consisting of a combination of an epoxy compound and triethylenediamine. The epoxy compound used is not particularly limited. Specific examples include glycidyl ethers of alcohols such as n-butyl glycidyl ether, allyl glycidyl ether, and glycerin triglycidyl ether; glycidyl ethers of phenols such as phenyl glycidyl ether, resolming glycidyl ether, and diglycidyl ether of bisphenol A; Examples include glycidyl ether of carboxylic acids such as glycidyl methacrylate, vinylcyclohexene diepoxide, butadiene epoxide, epoxidized soybean oil, styrene oxide, etc., but particularly preferred are phenyl glycidyl ether and/or dicrycidyl of bisphenol A. It is ether. In such a catalyst, the epoxy compound is preferably used in an amount of 0.005 to 0.1 equivalent per equivalent of isocyanate group,
Further, triethylenediamine is used in an amount of 0.01 to 2 parts by weight per 100 parts by weight of the organic polyisocyanate. This epoxy compound-triethylenediamine catalyst imparts relatively mild reactivity to the reaction system. If necessary, an alkali metal salt and/or alkaline earth metal salt of carboxylic acid is used in combination with the epoxy compound-triethylenediamine catalyst. Examples of carboxylic acids include acetic acid, propionic acid,
Examples include, but are not limited to, aliphatic mono- and dicarboxylic acids such as 2-ethylhexanoic acid and adipic acid, and aromatic mono- and dicarboxylic acids such as benzoic acid and phthalic acid. Preferable examples of the alkali metals to form the carboxylic acid salt include sodium and potassium, and preferable examples of the alkaline earth metal include calcium, but of course the metals are not limited to these. but,
In the present invention, the carboxylic acid salt particularly preferably used is potassium acetate. The carboxylate catalyst as described above has, per equivalent of isocyanate group,
Preferably, 0.03 equivalent or less is used. In addition, in the case of dicarboxylic acid, it may be either a neutral salt or an acidic salt. When used in combination with an epoxy compound-triethylenediamine catalyst, the carboxylate catalyst has the effect of accelerating the curing of the reaction system, improving the curing of the foam surface, and further reducing the amount of triethylenediamine used. Further, if desired, in the present invention, a known trimerization catalyst or urethanization catalyst may be used in combination with the above catalyst. Foaming agents and foam stabilizers that have been commonly used in the past can be used as appropriate, and are not particularly limited. As the blowing agent, for example, inert low-boiling halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, and methylene chloride are used. Water is also used. Examples of the foam stabilizer include various silicone surfactants used in the production of urethane foam. Additives such as flame retardants and fillers are also used as necessary. As the flame retardant, phosphorus-based flame retardants, halogen-based flame retardants, and other known flame retardants are usually used to make urethane foam flame retardant. Examples of the filler include synthetic resin powder, glass powder, silica, alumina, aluminum hydroxide, calcium carbonate, ammonium phosphate, antimony oxide powder, foamed glass particles, foamed perlite, etc.
Various materials such as inorganic granular foams such as expanded vermiculite and shirasu balloons, and fibrous materials such as glass fibers, carbon fibers, synthetic fibers, and cellulose fibers can be used as appropriate depending on the purpose of the rigid foam. In producing the urethane-modified rigid isocyanurate foam according to the present invention, each component is mixed by conventionally known methods and equipment,
Although it can be formed into a foam, it is convenient to prepare a mixture of mutually inert components in advance and use a double mixture when forming the foam. For example, a mixture consisting of an organic polyisocyanate, an epoxy compound and a portion of the required amount of a blowing agent, and triethylenediamine, a carboxylic acid salt,
A mixture consisting of the polyol, the remainder of the blowing agent, and the foam stabilizer is prepared separately, and these two mixtures are mixed during foam molding. Preparing mixtures of each component individually in this manner is advantageous in that the individual mixtures usually have a storage stability of two weeks or more. The present invention will be explained in more detail with reference to Examples below. The method of the present invention allows the reaction in foam molding to be controlled by reacting a specific organic polyisocyanate and a specific polyol in the presence of a specific catalyst. At the same time, it has improved the hardenability of the foam surface, making it possible to produce a urethane-modified rigid isocyanurate foam that is less brittle and has a homogeneous fine cell structure with a high closed cell ratio. Furthermore, the rigid foam obtained by the method of the present invention retains the excellent heat resistance and flame retardancy possessed by isocyanurate foam. Examples Polyphenylene polymethylene polyisocyanate (trade name "Takenate RL-15P", Takeda Pharmaceutical Company Limited) and diglycidyl ether of bisphenol A (trade name "Prominate YD-128", Takeda Pharmaceutical Company Limited) ) at a weight ratio of 100:5 (hereinafter referred to as P solution) was prepared.
Separately, prepare a mixed solution (hereinafter referred to as R
It's called liquid. ) was prepared. This P liquid and R liquid are combined with Freon in the amounts shown in the table below.
After stirring and mixing for 10 seconds, the mixture was immediately poured into a 25 cm cubic cake box and allowed to freely foam at room temperature to produce a urethane-modified rigid isocyanurate foam. The equivalent ratio of isocyanate groups to hydroxyl values in this case is also shown in the table. The physical properties of the hard foam obtained as described above are summarized in a table. As is clear from comparison with the hard foam obtained in the comparative example described below, the hard foam obtained by the present invention has a particularly large impact value,
In addition to significantly improved brittleness, the surface hardening properties were excellent, and the cell state was homogeneous and fine. Furthermore, it is clear from a comparison of Examples 2 and 3 with Example 1 that the carboxylic acid salt as a catalyst increases the reactivity. Incidentally, the impact value was measured using a DuPont impact tester. A cylindrical striking core with a diameter of 2.5 cm is placed on a foam sample with a thickness of 5 cm, and 500 g is placed on top of the foam sample from a height of 50 cm.
The depth of the hole formed in the foam sample (1 cm) was measured by dropping a weight, and the impact value was determined using the following formula. Impact value = 55.2/l (lb・in/in) Comparative example In exactly the same manner as in the example, R liquid having the composition shown in the table was stirred and mixed with Freon together with P liquid, and then
Immediate free expansion was carried out to produce a rigid foam.
The physical properties are shown in the table. 【table】

Claims (1)

[Scope of Claims] 1. At least one organic polyisocyanate selected from the group consisting of polyphenylene polymethylene polyisocyanate and diphenylmethane diisocyanate, and at least one glycol selected from the group consisting of ethylene glycol and diethylene glycol. , a polyether triol with a hydroxyl value of 200 to 1000 mgKOH/g obtained by adding ethylene oxide to trimethylolpropane, and the hydroxyl equivalent of the glycol and the hydroxyl equivalent of the polyether triol based on 1 equivalent of isocyanate group of the organic polyisocyanate. is 0.05 to 0.8, respectively, and the total of both does not exceed 1. The reaction is carried out in the presence of a catalyst containing triethylenediamine and an epoxy compound as main components, a blowing agent, and a foam stabilizer. A method for producing urethane-modified rigid isocyanurate foam. 2. A patent claim characterized in that 0.01 to 2 parts by weight of triethylene diamine is used with respect to 100 parts by weight of organic polyisocyanate, and 0.005 to 0.1 equivalent of an epoxy compound is used with respect to 1 equivalent of isocyanate group of the organic polyisocyanate. A method for producing a urethane-modified rigid isocyanurate foam according to Item 1. 3. The method for producing a urethane-modified rigid isocyanurate foam according to claim 1 or 2, wherein the epoxy compound is diglycidyl ether of bisphenol A. 4. The urethane-modified hard isocyanurate according to any one of claims 1 to 3, wherein the catalyst comprises triethylenediamine, an epoxy compound, and an alkali metal salt or alkaline earth metal salt of a carboxylic acid. Method of manufacturing foam. 5. The method for producing a urethane-modified rigid isocyanurate foam according to claim 4, characterized in that 0.03 equivalent or less of the carboxylic acid metal salt is used per equivalent of the isocyanate group of the organic polyisocyanate. 6. The method for producing a urethane-modified rigid isocyanurate foam according to any one of claims 4 to 6, wherein the carboxylic acid metal salt is potassium acetate.