JPS6149328B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a heat-resistant thermosetting resin using a reaction between polymethylene polyphenyl isocyanate and melamine and/or guanamine. BACKGROUND ART Conventionally, it has been known that an organic polyisocyanate undergoes addition polymerization with a compound having two or more active hydrogens, and is widely used in the production of polymer compounds. That is, for example, organic polyisocyanate reacts with polyhydric alcohols to produce polyurethane, and reacts with polyamine to produce polyurea, and the reactions of these two types of compounds are combined in various ways and are included in the general term polyurethane. Forms a group of useful polymeric substances. Furthermore, although rare, amide bonds produced by the reaction between organic polyisocyanates and polyvalent organic compounds are sometimes used to modify the polyurethanes mentioned above. On the other hand, aminotriazines are also compounds having an active hydrogen in a free amino group, but there have been few examples of producing polymeric substances by reacting organic polyisocyanates with aminotriazines. The inventors of the present invention have repeatedly conducted research to provide a new method for producing heat-resistant thermosetting resins against the background of the above-mentioned circumstances. The present invention was completed based on the knowledge that an extremely hard, insoluble and infusible condensate can be produced by solidifying and further heating and curing the condensate. This method is characterized by reacting enyl isocyanate with melamine and/or guanamine under heating. Next, the present invention will be explained in detail. First, polymethylene polyphenyl isocyanate and melamine and/or guanamine are thoroughly mixed at room temperature. This mixing uses a suitable mixing/dispersing machine such as a ball mill, sand mill, homogenizer, etc.
It is necessary to disperse melamine and/or guanamine as fine particles as uniformly as possible in the polymethylene polyphenyl isocyanate. The ratio of the two during mixing can vary within a wide range; melamine and/or
Alternatively, guanamine can be selected in the range of 0.5 to 5 gram equivalents of free amino groups, and if the equivalent ratio index of free amino groups to isocyanate groups is γ, then γ = 0.5 to 5, and when γ < 0.5, it is obtained. The yield of the heat-resistant thermosetting resin is too low, and when γ>5, the strength of the resin decreases. Aminotriazines may be used alone or in a mixture of two or more. The resulting dispersion mixture is quite stable at room temperature; for example, a mixture of sufficiently finely dispersed melamine in polymethylene polyphenyl isocyanate remains in the form of a slurry without solid-liquid separation for several weeks, and hardly reacts at room temperature. do not. Also, a dispersion mixture of polymethylene polyphenyl isocyanate and substituted aminotriazine is stable for several days to several weeks, whereas a dispersion mixture of polymethylene polyphenyl isocyanate and benzoguanamine remains liquid for several days, but gradually increases in viscosity. However, it becomes extremely viscous after two weeks. Next, the slurry-like dispersion mixture is heated and reacted, but depending on the heating temperature and its mode,
The resulting resins exhibit slightly different properties. That is, when the slurry-like mixture is poured into a suitable mold and heated in a heater, the viscosity of the mixture decreases as the temperature rises, but when it reaches a certain temperature, the viscosity rapidly increases and hardens to obtain a resin. The temperature at which this curing occurs depends on the type of components of the dispersion mixture. For example, a mixture of polymethylene polyphenyl isocyanate and melamine
The temperature is 125°C to 135°C, and the viscosity of the mixture of polymethylene polyphenyl isocyanate and benzoguanamine gradually increases from 40°C to 50°C, and it hardens at 80°C, but even at lower temperatures, the heating time is You can harden it by making it longer. The resin obtained at the above temperature was brown in color, and no aminotriazine crystals were observed under the microscope. Therefore, it seems to be a low-molecular polymer of polyphenyl isocyanate and melamine and/or benzoguanamine, and the surface was coated with a metal object. It has a hardness that does not cause scratches even when rubbed vigorously, and a heat resistance that does not soften or melt even when exposed to direct flame. Note that when this resin is rapidly cooled, it takes on the form of a very brittle wax, but unlike ordinary wax, it does not melt when heated. Alternatively, the heat-resistant thermosetting resin obtained as described above may be cured at a temperature of 180°C to 250°C for several minutes to several tens of hours, or the slurry mixture may be cured directly.
Extremely hard resins can be obtained by heating to temperatures between 180°C and 250°C, and the resins thus obtained are very thermally stable and do not survive in air.
At temperatures of 200°C to 250°C, a thin carbonized film is formed on the resin layer, but no substantial thermal decomposition is observed over several tens of hours, and even if it comes into direct contact with flame, it has no ignitability and does not burn. Furthermore, when the resin obtained at the above temperature is heated to 300°C or higher, or when the slurry mixture is heated to this temperature, it softens slightly and foams slightly while releasing gas that is thought to be mainly water. When cured, a resin that exhibits a yellow color and excellent heat resistance is obtained. As shown in Figure 2, the resin treated at 350°C for 2 hours has a temperature range of 300°C to 350°C.
It shows almost no weight loss in thermogravimetric analysis at a heating rate of 5°C per minute up to 350°C. Therefore, the resin obtained by the present invention is insoluble in all solvents at any heating temperature, and can be said to be a typical thermosetting resin.
It can be poured into a mold of a desired shape, poured into a closed mold through a heating device, and solidified, or solidified into a continuous plate.The heating process can be performed under normal pressure or under pressure. Although this may be carried out, it is easier to obtain a dense structure if carried out under pressure. Additionally, this resin may be supplemented with fibrous reinforcing materials such as glass fiber and asbestos, inorganic fillers such as titanium oxide, calcium carbonate, clay, talc, and silica powder, polyfluorinated carbon resin powder, amino resin condensate powder, wood flour, etc. By adding an organic filler, its properties can be changed to favorable ones. However, it is desirable that these reinforcing materials have a heat resistance of at least 150°C or higher. Furthermore, by adding a foaming agent to a mixture of polymethylene polyphenyl isocyanate and melamine and/or benzoguanamine and heating the mixture, a foamed body using the resin can also be produced. For example, by adding a foaming agent such as azobisisobutylonitrile, dinitrosopentamethylenetetramine, or sodium bicarbonate to the mixture, heating and foaming the mixture, and then heat-curing this, a nearly non-flammable foam can be obtained. It's like it's being done. Alternatively, the organic polyisocyanate may be foamed by mixing water in an amount equal to or less than the reaction equivalent, and then heating and curing the resultant mixture. It is flame retardant or non-combustible, and produces almost no smoke even if it comes in direct contact with flame. The heat-resistant thermosetting resin obtained in this way is extremely useful as a hard heat-resistant and flame-resistant material, and by utilizing this excellent property, it can be used as a heat-resistant and flame-retardant building material and insulation material. It can also be used as a friction material for brake linings, clutch facings, etc. It is also suitable for use as a binder for silica sand for shell mode, and for manufacturing particle board by mixing with wood flakes. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 Polymethylene polyphenyl isocyanate 1120
(8 grams equivalent) and 340 grams (8 grams equivalent) of melamine were placed in a porcelain pot mill.
The mixture was pulverized and dispersed for 18 hours with 2000 grams of porcelain balls to obtain a brown slurry mixture 1. The viscosity is
It was 680cps. When a small amount of this slurry mixture 1 is dropped onto a smooth mold kept at 165°C, it becomes a wax-like solid after 30 seconds, and after 120 seconds it has hardened to the extent that it will not cause scratches even if the surface is rubbed strongly with a metal spatula. However, even when this material was exposed to the flame of a burner, no phenomenon of softening and melting was observed. Example 2 Polymethylene polyphenyl isocyanate 1120
(8 grams equivalent) and 605 grams (14.2 grams equivalent) of melamine were placed in a porcelain pot mill and ground and dispersed together with 2200 grams of porcelain balls for 18 hours to obtain brown slurry mixture 2. The viscosity is
It was 1500cps. When a small amount of this slurry mixture 2 is dropped onto a smooth mold kept at 165°C, it becomes a wax-like solid after 20 seconds, and after 60 seconds it has hardened to the extent that it will not cause scratches even if the surface is rubbed strongly with a metal spatula. However, even when this material was exposed to the flame of a burner, no phenomenon of softening and melting was observed. Example 3 Polymethylene polyphenyl isocyanate 1120
g (8 gram equivalent) and 748 g of benzoguanamine
(equivalent to 8 grams) in a porcelain pot mill,
The mixture was pulverized and dispersed for 18 hours with 2000 g of porcelain balls to obtain a brown slurry mixture 3. Viscosity is 800cps
It was hot. When a small amount of this slurry mixture 3 is dropped onto a smooth mold kept at 165°C, it becomes a wax-like solid after 60 seconds, and after 180 seconds it has hardened to the extent that it will not cause scratches even if the surface is rubbed strongly with a metal spatula. However, even when this material was exposed to the flame of a burner, no phenomenon of softening and melting was observed. Example 4 Polymethylene polyphenyl isocyanate 1120
(8 gram equivalent), 170 g (4 gram equivalent) of melamine, and 374 g (4 gram equivalent) of benzoguanamine were placed in a porcelain pot mill.
A brown slurry mixture 4 was obtained by pulverizing and dispersing it together with 2000 g for 18 hours. The viscosity was 720 cps.
When a small amount of this slurry mixture 4 is dropped onto a smooth mold kept at 165°C, it becomes a wax-like solid after 50 seconds, and after 180 seconds it has hardened to the extent that it will not cause scratches even if the surface is rubbed strongly with a metal spatula. However, even when this material was exposed to the flame of a burner, no phenomenon of softening and melting was observed. The changes in viscosity when slurry mixtures 1 and 2 in Examples 1 and 2 were placed at temperatures of 20°C and 40°C are shown in FIG. Example 5 Slurry mixtures 1, 2, 3, and 4 in Examples 1, 2, 3, and 4 were poured into a mold that had been preheated in a dryer whose temperature was adjusted to 165°C, and at the same time the lid was closed. Then, heating was continued for 1 hour in a dryer to obtain a plate-shaped molded product. The physical properties of this product are shown in Table 1.
As shown.

[Table] Example 6 Slurry mixtures 1, 2, 3, and 4 from Examples 1, 2, 3, and 4 were poured into a mold, covered, and then heated in a dryer at 165°C. After heating for an hour, the temperature of the dryer was raised to 200°C and heated for 18 hours to obtain a plate-shaped molded product. The physical properties of this product were as shown in Table 2.

[Table] Example 7 Slurry mixtures 1, 2, 3, and 4 in Examples 1, 2, 3, and 4 were poured into a mold, covered, and then heated in a dryer at 165°C. Heat for an hour,
Next, the temperature of the dryer was raised to 200°C and heated for 18 hours, and the temperature of the dryer was further raised to 350°C and heated for 2 hours to obtain a plate-shaped molded product. This thing has a yellow color,
It was slightly foaming. The physical properties are shown in Table 3, and the results of thermogravimetric analysis when the temperature was increased by 5° C. per minute are shown in FIG.

【table】

[Table] Example 8 Six sheets of continuous long fiber glass mat cut to the same size were stacked and filled into a mold preheated to 165°C.
Slurry mixture 2 was poured into the mold, and an upper mold was immediately fitted and pressurized using a press. After 10 minutes, the mold was opened to obtain a plate-shaped molded product. The physical properties of this product were as shown in Table 4.

[Table] Furthermore, when the above molded product was cured at 200°C for 18 hours, it exhibited the physical properties shown in Table 5.

[Table] Example 9 Slurry mixture 1 and various inorganic materials were mixed, placed in a mold, and pressed at 165° C. and a pressure of 100 Kg/cm ² for 10 minutes to obtain a plate-shaped molded product. The physical properties of this product were as shown in Table 6.

【table】

[Table] Example 10 65 grams of slurry mixture 1, 1.3 cc of silicone surfactant, and 10 grams of sodium hydrogen carbonate as a blowing agent were placed in a stainless steel beaker with a capacity of 300 cc, and the mixture was thoroughly stirred and mixed on a mantle heater. The mixture was heated to 110°C. Next, this was poured into a mold with internal dimensions of 200 mm x 200 mm x 25 mm that had been preheated to 165°C, the lid was closed, and the mold was heated for 10 minutes in a dryer at 165°C. The mold was opened to obtain a closed-cell rigid foam having dimensions of 200 mm x 200 mm x 25 mm. Furthermore, this foam was cured in a dryer at 200℃ for 2 hours.
A brown foam was obtained. The materials of these foams were as shown in Table 7.

【table】 [Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the temperature and viscosity increase of slurry mixtures 1 and 2, and FIG. 2 is a graph showing the results of thermal mass spectrometry of an example of the resin obtained by the present invention.

Claims (1)

[Claims] 1. A method for producing a heat-resistant thermosetting resin, which comprises reacting polymethylene polyphenyl isocyanate with melamine and/or guanamine under heating. 2 Polymethylene polyphenyl isocyanate and melamine and/or guanamine at 60℃ or higher and 200℃
The method for producing a heat-resistant curable resin according to claim 1, characterized in that the reaction is carried out by heating to the following temperature. 3 Polymethylene polyphenyl isocyanate and melamine and/or guanamine at 60°C to 200°C
2. The method for producing a heat-resistant thermosetting resin according to claim 1, wherein the resin is heated to 200° C. to 250° C. for reaction. 4 Polymethylene polyphenyl isocyanate and melamine and/or guanamine at 60°C to 200°C
, then heated to 200℃ to 250℃, and then
The method for producing a heat-resistant thermosetting resin according to claim 1, characterized in that the reaction is carried out by heating to 300° C. or higher. 5. The method for producing a heat-resistant thermosetting resin according to claim 1, which comprises reacting polymethylene polyphenyl isocyanate with melamine and/or guanamine under heating in the presence of an appropriate blowing agent.