JPH0367527B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a curable heat-resistant resin, and more particularly to a method for producing a polyisocyanurate-based heat-resistant resin using a high-speed curing molding method such as reaction injection molding. Reaction injection molding technology is highly developed in the field of polyurethane elastomers, and is applied in the automotive industry to mold bumpers, soft facias, etc. This molding method is said to be more economical than conventional injection molding of thermoplastic plastics in terms of mold costs and molding energy costs when molding large, thin-walled objects. Furthermore, this molding method has a much shorter molding cycle time than molding by casting or injection methods conventionally used in the polyurethane industry, and is advantageous in terms of productivity. Molding of structural members using hard polyurethane is also being carried out by taking advantage of the advantages of reaction injection molding as described above. These are specifically applied to furniture with complex shapes and housings for home appliances, but they have not found as many uses as polyurethane elastomers. The biggest possible reason for this is that the rigid polyurethane does not meet the physical property requirements for a structural member. Many rigid polyurethanes are
Because it undergoes thermal deformation and thermal deterioration at temperatures around 100℃, it cannot withstand the painting finishing process of structural members or the atmospheric conditions when used as equipment. Therefore, there is an urgent need to develop a liquid reaction system that satisfies the physical properties requirements for a structural member and can be subjected to reaction injection molding. Thermal deformation and thermal deterioration of rigid polyurethane originate from urethane bonds, and to improve these problems, it is necessary to replace these bonds with heat-resistant bonds. For this purpose, the most advantageous method is to utilize the isocyanate trimerization reaction to introduce isocyanurate ring structures and at the same time form a network structure. Polyisocyanurate resins are obtained by polymerizing polyisocyanate in the presence of a basic catalyst that causes an isocyanurate reaction, and the resins produced thereby generally exhibit a high heat distortion temperature. It is not necessarily stable at high temperatures. That is, some basic catalysts may cause cracks or bubbles in the resin at high temperatures. As a result of investigating the relationship between the basic catalyst composition for isocyanurate conversion and the cracking and foaming of polyisocyanurate resin at such high temperatures, we came to the following conclusion. 1) Tertiary nitrogen-containing compounds: Curing is slow and polyisocyanurate resins crack or foam at high temperatures. 2) Tertiary nitrogen-containing compound + epoxy compound:
Although the curing speed is moderate, polyisocyanurate resins do not crack or foam at high temperatures. 3) Basic alkali metal compound: Although it has a high curing speed, polyisocyanurate resin shows significant cracking and foaming at high temperatures. 4) Tertiary nitrogen-containing compound + basic alkali metal compound: Curing speed is high, and cracking and foaming are observed at high temperatures. That is, a polyisocyanurate resin that does not show cracking or foaming at high temperatures can be obtained by combining a tertiary nitrogen-containing compound and an epoxy compound. However, this catalyst composition does not provide rapid curing properties suitable for reaction injection molding. The present invention uses a polyisocyanurate resin that exhibits fast curing properties suitable for reaction injection molding, and also exhibits high thermal stability so that the resulting resin molded product does not crack or foam even at high temperatures. This was the result of intensive study on the structure method. That is, in the present invention, an epoxy compound, a tertiary nitrogen-containing compound, and a basic alkali metal compound are added to a polyisocyanate in such a way that the concentrations of the epoxy group, tertiary nitrogen, and alkali metal in the system are 0.1 to 1.5, respectively. Milliequivalent/g, 0.05-0.3 milliequivalent/
The present invention relates to a method for producing a fast-curing heat-resistant polyisocyanurate resin, which is characterized in that it is blended and cured in such a manner that the amount of the polyisocyanurate resin is 0.002 to 0.003 milliequivalent/g. As the polyisocyanate in the present invention,
A monomer having two or more isocyanate groups, such as fatty acid, alicyclic, aromatic-substituted aliphatic, aromatic, or heterocyclic polyisocyanates. Examples of these include tetramethylene-1,
4-diisocyanate, hexamethylene-1,6
-diisocyanate, octamethylene-1,8-
Diisocyanate, dodecamethylene-1,12-diisocyanate, 2,2,4- or 2,4,
4-trimethylhexamethylene-1,6-diisocyanate, 1-isocyanate-3,3,5-
Trimethyl-5-isocyanatomethylcyclohexane cis- or trans-cyclohexane-1,
4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, ω,ω'-diisocyanatomethyl-1,4- or -1,3-cyclohexane, 3,10-diisocyanatotricyclo[5,2, 1,0 ^2.6 ] Decane, 2,2-bis(4-
isocyanatocyclohexyl)propane, 6,8
-diisocyanatobicyclo[3,3,0]octene, tolylene-2,4- or -2,6-diisocyanate, diphenylmethane-2,4'- or -4,4'-diisocyanate, naphthylene-
1,5-diisocyanate, bitolylene diisocyanate, anisidine diisocyanate, diphenyl ether-4,4'-diisocyanate, triphenylmethane-4,4',4''-triisocyanate, tris(4-isocyanatophenyl)thiophosphate , undecane-1,6,10-triisocyanate, xylylene-1,3- or -1,
These include 4-diisocyanate, lysine diisocyanate methyl ester, N,N'-bis(ω-isocyanatopropyl)oxadiazinetrione, and the like. In addition, the polyisocyanates of the present invention include polyphenylpolymethylene polyisocyanates of the type obtained by condensing aniline with formalin and then phosgenation, and room temperature polyisocyanates having carbodiimide groups or uretonimine groups as described in German Patent No. 1092007. Liquid diphenylmethane diisocyanates, or modified polyisocyanates containing urethane bonds, allophanate bonds, isocyanurate ring structures, urea bonds, biuret bonds, uretidione ring structures, etc. can also be used. Further, as the polyisocyanate in the present invention, an isocyanate-based prepolymer obtained by reacting an excessive amount of the polyisocyanate with a polyol used in the urethane industry can also be used. Among these are commercially readily available polyisocyanates, such as tolylene-2,4- and tolylene-2,6-diisocyanates and all mixtures of these isomers, aniline condensed with formalin and then phosgenated. Polyphenylmethane-4,4'-diisocyanates and diphenylmethane-2,4'-diisocyanates of the type obtained and any mixtures of these isomers, liquefied didiphenylmethane diisocyanates, these polyisocyanates and polyester polyols, or Particularly suitable are isocyanate-terminated prepolymers obtained from polyether polyols. The epoxy compound used in the present invention is a mono- or polyepoxy compound, such as allyl glycidyl ether, butyl glycidyl ether,
Phenyl glycidyl ether, butylene oxide, propylene oxide, octylene oxide,
Monoepoxides such as styrene oxide, glycidol, glycidyl ester of versatectic acid, diglycidyl ether of bisphenol A,
Butadiene epoxide, 3,4-epoxycyclohexylmethyl-(3,4-epoxy)cyclohexanecarboxylate, bicyclohexene dioxide, 4,4'-di(1,2-epoxyethyl)
Diphenyl ether, 4,4'-di(1,2-epoxyethyl)biphenyl, 2,2-bis(3,4
-epoxycyclohexyl)propane, diglycidyl ether of resorcin, diglycidyl ether of methylphlologlycine, bis(2,3-epoxycyclopentyl)ether, 2-(3,4-
epoxy)cyclohexane-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane, bis-(3,4-epoxy-6-methylcyclohexyl)adipate, N,N'-m-phenylenebis(4,5 -Diepoxide such as epoxy-1,2-cyclohexanedicarboximide, triglycidyl ether of para-aminophenol, polyallyl glycidyl ether, 1,3,
5-(1,2-epoxyethyl)benzene-2,
2'-4,4'-tetraglycidoxybenzophenone, tetraglycidoxytetraphenylethane,
Epoxides having three or more functionalities are used, such as polyglycidyl ether of phenol-formaldehyde novolak, triglycidyl ether of glycerin, and triglycidyl ether of trimethylolpropane. The above epoxides may be used alone or as a mixture of two or more. Among these epoxides, liquid and low-viscosity mono- or diepoxides are preferred, and phenyl glycidyl ether, diglycidyl ether of bisphenol A, and the like are particularly preferred because they are easily available industrially. The tertiary nitrogen-containing compound used in the present invention is
For example, trialkylamines such as triethylamine and tributylamine, triethanolamine,
alkanolamines such as N-methyldiethanolamine and N,N'-dimethylethanolamine;
N-methylmorpholine, N-ethylmorpholine,
N,N'-dimethylpiperazine, 1,4-diazabicyclo[2,2,2]octane, 4,4'-dimethylmorpholinodiethyl ether, N,N',
N″-tris(dimethylaminopropyl)hexahydro-s-triazine, 2-methyldiazabicyclo[2,2,2]octane, 1-methyl-4-
Dimethylaminoethylenepiperazine, N-(2-
Cyanoethyl)piperidine, 1,8-diazabicyclo[5,4,0]undezene, cyclic amines such as pyridine, N,N-dimethylcyclohexylamine, dimethylbenzylamine, methyldicyclohexylamine, 2-dimethylaminomethylphenol, 2, 6- or 2,4-bis(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylbutanediamine, tetramethylhexamethylenediamine, tetramethylethylenediamine, pentamethyldiethylenetriamine, bis( 2-dimethylaminoethyl) ether, pentamethyldipropylenetriamine, bis(dimethylaminopropyl)methylamine, N,N-dimethylamineethoxypropionitrile, dimethyl-2,2-dicarboxyethylamine, 2,2,4- Tertiary amines such as trimethyl-2-silamorpholine, 1,3-diethylaminomethyl, tetramethyldisiloxane, 1,2-dimethylimidazole, 1-dianoethyl-2-phenylimidazole, 2-(1
-aziridinyl)ethyl methacrylate, 1-
Examples include imidazoles and aziridinyl compounds such as (2-hydroxyethyl)aziridine and trimethylolpropane tris (ω-aziridinylpropionate). The above tertiary nitrogen-containing compounds may be one or two types.
Can be used as a mixture of more than one species. The basic alkali metal compounds of the present invention include basic compounds of lithium, sodium, potassium, rubidium, cesium, and francium, which belong to Group Group of the Periodic Table. Particularly preferred are compounds. Examples of basic alkali metal compounds include sodium or potassium carboxylates having 2 to 8 carbon atoms such as acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, lactic acid, benzoic acid, and sodium or potassium palmitic acid. , carboxylates having 9 or more carbon atoms such as oleic acid and ricinoleic acid, salts of weak acids other than carboxylic acids such as sodium or potassium phenols, cresols and xylenol, sodium or potassium methoxides or hydroxides, salicylaldehyde and potassium. These include chelate compounds such as chelate. The above basic alkali metal compounds can be used alone or as a mixture of two or more. Among these, particularly preferred are potassium butyrate and potassium 2-ethylhexanoate, which have good compatibility with polyisocyanates. Since basic alkali metal compounds are generally crystalline solids, they are preferably used after being dissolved or dispersed in a liquid tertiary nitrogen-containing compound or epoxy compound. Further, each or a part of the basic alkali metal compound, tertiary nitrogen-containing compound and epoxy compound can be used by dissolving or dispersing them in the polyol. It is generally preferred to use the polyol within the limits of an NCO/OH molar ratio of 5 or more and a polyisocyanate/polyol weight ratio of 2 or more based on the polyisocyanate. This is because if more polyol is used, the heat resistance and high-speed curing properties of the cured resin will be impaired. The polyols used here are short-chain and long-chain polyols commonly used in the polyurethane industry. These include, for example, short chain polyols such as ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, pentanediol, 1,6-hexanediol, polyoxyethylene polyol, polyoxy Propylene polyol, oxyethylene/oxypropylene copolymer polyol, polyoxytetramethylene glycol, and other polyether long-chain polyols, poly(ethylene adipate), poly(diethylene adipate), poly(tetramethylene adipate), poly( neopentyl adipate), polyester-based long chain polyols such as poly(ε-caprolactone), and other long chain polyols such as polybutadiene polyols, polycarbonate polyols, and polymer polyols. These polyols may be used singly or as a mixture of two or more, but liquid polyols are preferred for handling purposes, and particularly preferred include dipropylene glycol, polyoxypropylene polyol, poly(diethylene glycol adipate) polyol, etc. However, since their use affects the mechanical properties, heat resistance, etc. of the resin, one should be selected that is suitable for the purpose of use. In reaction injection molding, a system liquid consisting of two or more components is metered and sent to a mixing chamber using a high-pressure liquid pump, and each component is ejected from a nozzle within the mixing chamber, forming a mixture from a discharge port through a runner and into a mold. Press fit and form. The mold is coated with a release agent in advance,
Make it easy to demold the molded product. The component liquid is heated to room temperature or, if necessary, to about 80°C before use. The mold is preheated to room temperature to about 120°C, and generally, a temperature of about 40 to 60°C is preferable in terms of demoldability and surface condition of the molded product. When molding is performed under such general reaction injection molding conditions, the time required for the molded cured product to be released from the mold (demolding) after each component is injected into the mold is determined by considering productivity. The time is preferably within 1 minute, more preferably within 30 seconds. In general, the faster the hardening and shorter demolding time, the less adhesion to the mold, the less deformation and damage during demolding, and the better the product yield. Thus, it is particularly desirable for molding cycle times in reaction injection molding to be within 5 minutes, preferably within 3 minutes. The molded product after demolding can be heated at 100 to 200℃ for 2 hours, depending on the heat resistance temperature required for the final use.
Post-cure treatment may be performed for ~4 hours. As with the compounding technique commonly used in reaction injection molding, each component liquid may contain moldability improvers such as colorants, fillers, reinforcing agents, stabilizers, blowing agents, and internal mold release agents. You can also do it. According to the present invention, a polyisocyanurate resin with good heat resistance can be molded extremely efficiently and economically, and this molded product can be used for example in televisions,
The main shells of VTRs, computers, or audio equipment, electrical parts such as switch covers, printed circuit boards, lamp covers, household items such as frying pan handles, iron handles, oven plates, lamp covers, and around heaters. Automotive parts such as structural members,
It is extremely useful and can be used for structural members such as nuclear equipment and solar thermal panels, constituent materials for sliding parts, resin molds, and roll parts. Next, the present invention will be explained in more detail with reference to Examples. Preparation of prepolymer (A) 5000 g of diphenylmethane-4,4'-diisocyanate melted at 60℃ was placed in a stainless steel 10 airtight container equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube, and nitrogen gas was added above the liquid level. After filling the space in the closed container with the mixture, start stirring. Next, polyoxypropylene glycol (molecular weight 700) 1512
g and continued stirring for 4 hours while keeping the internal temperature at 80 to 90℃, NCC content 23.0%, viscosity 550cP/
A prepolymer (A) at 25°C was obtained. Examples 1 to 4, Comparative Examples 1 to 6 The isocyanate component was placed in the A tank side of a two-component MC-102 type circulating impingement mixing reaction injection molding machine (manufactured by Polyurethane Engineering Co., Ltd.), and the polyol and catalyst components were placed in the B tank side. Fill the mixture, and while stirring, reduce the pressure to 1 mmHg at room temperature and keep it for 2 hours to degas, and select and set the nozzles for each component in the mixing chamber to maintain a discharge pressure of 110 to 140 Kg/ ^cm2 .
The discharge port was fitted into the runner of the mold. The cavity dimensions of the mold are 20cm x 30cm x 3mm thick and 20cm
There were two types, 30 cm x 4 mm thick, with the lower part fixed to a tie plate and the upper part opening and closing like a door.The temperature of the mold was controlled by running hot water through the upper and lower parts to keep the mold at about 50°C. Prior to molding, a mold release agent (Daifree MS-743: manufactured by Daikin Industries) was applied to the mold. The amount of liquid to be injected is 230 to 240 g/shot when the thickness is 3 mm, including the runner part, and when the thickness is 4 mm.
The appropriate amount was 290-305g/shot. The demolding time was defined as the time from when the liquid was injected to when the mold was opened and when the cured molded product was removed from the mold. The results are shown in Table 1. Examples 5 to 8, Comparative Examples 7 and 8 Using the same reaction vessel as in Example 1, the A tank side was filled with the isocyanate component, the B tank side was filled with the polyol and the catalyst component, and the other conditions were the same as in Example 1. The demoldability and physical properties of the molded product were investigated. The results are shown in Table 2. The formulations in the table are shown in parts by weight. Also,
The physical property values are as follows. (1) Density (g/cm ³ ): Indicates the density of each measurement sample. (2) Barcol hardening: Barcol hardness tester (GYZJ934
-1 type) at 25°C. (3) Bending strength and bending modulus (Kg/cm ² ):
Measured according to JISK7203. 3mm×
A test piece was prepared by cutting to 25 mm x 127 mm, and measurement was performed with a support width of 50 mm. (4) Heat distortion temperature (C): Measured according to JISK7207.
A test piece was prepared by cutting to a size of 4 mm x 10 mm x 110 mm, and was heated in a silicone bath under a load of 18.5 Kg/cm ² for measurement. (5) Heating test: Using the same test piece as the test piece for measuring heat distortion temperature, it was heated in a gear oven at a constant temperature for 2 hours, and changes in appearance were examined.

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Claims (1)

[Claims] 1. Concentrations of the epoxy compound, tertiary nitrogen-containing compound, and basic alkali metal compound in the polyisocyanate are 0.1 to 1.5 meq/g and 0.05, respectively, of the epoxy group, tertiary nitrogen, and alkali metal in the system. ~0.3 meq/g and 0.002~
A method for producing a fast-curing heat-resistant polyisocyanurate resin, which comprises blending and curing the resin at a concentration of 0.03 milliequivalent/g.