JPS6211013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for polymerizing cast nylon material having a thickness of 2 mm to 20 mm at high speed.

Cast nylon material has excellent wear resistance, self-lubricating properties, and mechanical strength, and is widely used in industrial applications as a material for sliding parts.

Conventionally, such cast nylon materials are made of aluminum,
A mold made of iron, etc. is heated in a hot air oven until it reaches a specified temperature, then the mold is taken out of the furnace, a rapidly polymerizing lactam liquid is poured into it, and the lactam solution is poured into it, and the lactam is heated adiabatically by placing it back in the hot air oven. A method of conducting a polymerization reaction was used. Polymerization reaction time is anionic polymerization catalyst,
It is known that by appropriately selecting the cocatalyst, the amount thereof added, and the polymerization temperature, it is possible to control the polymerization over a wide range, and for example, it is possible to complete the polymerization within a few minutes. However, in the conventional production method described above, the polymerization system is placed under adiabatic conditions, so the blending and
No matter how quickly the temperature is selected to complete the polymerization, the peeling time until the crystallization of nylon is almost complete;
That is, it is extremely difficult to significantly shorten the time required to take out the product, which usually takes about 30 minutes to one hour, and there has been a desire in the industry to develop a method that can perform molding at even higher speeds.

In addition, when lactam is polymerized very rapidly in the conventional manufacturing method, large and small air bubbles made of air mixed in during casting gel without completely floating, and the air bubbles adhere to the mold wall in particular. Since the product was molded in the same state, the appearance of the product surface was impaired.

Furthermore, in conventional manufacturing methods, when a preheated mold is taken out of the furnace and cast, the mold comes into contact with the outside air, causing uneven heating, making it difficult to stably manufacture high-quality products.

Furthermore, when the mold is removed from the furnace and the product is released after polymerization is completed, the mold temperature drops by about 50℃ because the mold is exposed to the outside air, and the mold temperature drops by about 50℃ before the next casting. It was necessary to sufficiently heat the mold in a hot air oven until it reached the desired casting temperature, and a large amount of mold preheating time was required each time the mold was released.

In view of these facts, the inventor of the present invention conducted intensive research into a method for efficiently manufacturing high-quality nylon material with a thickness of 2 mm to 20 mm at high speed.
A polymerizable lactam solution is poured into a mold that is forcibly maintained at a temperature in the range of 170℃ to 170℃, and while the polymerizable lactam liquid is in a liquid state, the mold is vibrated and poured. Even after molding, the temperature ranges from 130℃ to 170℃ depending on the heating medium.
When lactam polymerization is carried out in a non-adiabatic manner in a mold that is forcibly maintained at an arbitrary temperature in the range of °C, it is surprising that a nylon molded product with a thickness of 2 mm to 20 mm can be formed from the mold surface in a few minutes. They discovered that it peeled off quickly and completely on its own, and that it could be easily removed without having to open the mold.

Moreover, since the mold is always maintained at a constant temperature, there is no heat unevenness in the mold during pouring, making it possible to manufacture high-quality products with good reproducibility, and also to maintain a constant temperature even when taking out the product. We have also discovered the advantage that the next casting can be carried out immediately because the upper mold temperature does not drop.

Furthermore, it has been unexpectedly discovered that air bubbles mixed into the polymerizable lactam liquid can be completely removed by lightly vibrating the mold while the polymerizable lactam liquid in the mold is in a liquid state.

According to the method of the present invention, it is possible to take out the product in a very short period of time after casting. As shown by the comparison with the temperature history, in the method of the present invention, the heating medium in the mold moderately absorbs the heat of polymerization and accelerates the onset of crystallization of nylon, and the heating medium in the mold also absorbs the heat of crystallization moderately. This is because the growth of nylon spherulites is accelerated, and peeling from the mold due to crystal shrinkage occurs extremely early.

Next, the mold will be explained. The mold used in the present invention is shown in FIGS. 1 and 2 as a typical example, but is not limited thereto. First, the mold shown in FIG. 1 includes a cavity 3 formed from a pair of opposing iron plates 1, 1 and a spacer 2 interposed around them, and an oil jar provided on the surfaces of the iron plates 1, 1. Butt 4
and an air hammer pedestal 5. Several steps 6 are provided inside the oil jacket 4,
A heat medium such as oil injected from the inlet 7 is uniformly dispersed within the oil jacket 4 to keep the iron plates 1, 1 at a constant temperature, and is then discharged from the outlet 8.

Furthermore, the mold shown in FIG. 2 has a cavity 11 formed from a pair of iron plates 9, 9 facing each other and a spacer 10 interposed around the cavities 11, which communicate with the insides of the iron plates 9, 9. An air hammer pedestal 13 is provided on the surface of the iron plate 9.
is provided.

The pedestals 5 and 13 become parts that apply vibration to the mold using an air hammer or the like.

Appropriate materials for the mold used in the present invention include metals with good heat transfer efficiency, such as aluminum and iron, which are normally used in manufacturing cast nylon. However, since copper (alloy) interferes with the anionic polymerization of lactam, it should not be used in areas that come into contact with lactam.

It should be noted that it is appropriate to use heat medium oil or steam as a heat medium to control the temperature of the mold, and the structure of the heat medium circulation path of the mold cannot be specified in particular. Designed with consideration to thermal efficiency, economy, and stability. Usually, a heat insulating cover is installed on the outside to maintain uniformity of mold temperature.

In addition, there is no need to specifically coat the inner surface of the mold with a mold release agent, but in order to improve the ease of removal and to mold the product surface smoothly, it is necessary to finish it as smooth as possible and to perform plating treatment. is preferred.

Nylon plates are manufactured at a mold temperature of 130℃ to 170℃, but if the mold temperature is lower than this, unreacted lactam will adhere to the product surface and it will be difficult to obtain a good finished product. When carried out at high temperatures, the time required for demolding increases, which is unexpectedly disadvantageous for the purpose of high-speed molding.

Furthermore, even when casting with the mold temperature controlled within the range of 130°C to 170°C, care must be taken to hold the mold vertically. If you cast the mold with the mold tilted, the air bubbles caught during casting will adhere to the upper hot plate wall, and even if you apply vibrations during casting, the air bubbles may not float up completely and remain, causing the product surface to deteriorate. This is because it spoils the appearance of the product.

In addition, vibration during casting can be effective by using a large-scale device that vibrates the entire mold, as is done when casting castings, but air bubbles in the low-viscosity polymerizable lactam liquid, especially on the inner wall of the mold, are effective. Since the purpose is to remove air bubbles attached to the mold, it is sufficient to apply slight, intermittent vibrations in the vertical direction to the bottom surface of the mold using an air hammer or the like. Of course, vibration is only effective when the polymerization system is in a liquid state.
It is preferable to perform this within 30 seconds from the start of casting. Normally, when casting at mold temperatures between 130°C and 150°C, vibration will ensure a bubble-free product, while at temperatures above 150°C, such vibration will ensure a bubble-free product. Vibration is indispensable, especially when highly filled with short glass fibers, wollastonite, short carbon fibers, etc., as the viscosity is relatively high and a large amount of air bubbles are mixed in.

Next, the polymerizable lactam liquid to be cast will be described. The polymerizable lactam liquid referred to here is a lactam liquid to which an anionic polymerizable catalyst and co-catalyst of ω-lactam are added, and the lactam used in the present invention is substantially It is an anhydrous ε-caprolactam or a mixed lactam of ε-caprolactam and ω-lauryllactam, and all conventionally known ω-lactam anionic catalysts can be used as the anionic polymerization catalyst used in the present invention. Examples are alkali metals,
Alkaline earth metals and their oxides, hydrides, or Grignard reagents, and their ω-
The co-catalysts used in the present invention include compounds that react with N-acyl lactams and ω-lactams to produce N-acyl lactams, as well as other co-catalysts known as ω-lactam anionic polymerization co-catalysts. Any catalyst can be used. Examples include N-acetyl-ω-caprolactam, isocyanates, diisocyanates, urea derivatives, urethanes, and isocyanurate derivatives.

The method of the present invention uses 0.1 mol% of each of the above anionic polymerization catalyst and cocatalyst based on the ω-lactam.
Although it can be carried out by using the polymer in a range of 10 to 10 mol %, the high-speed productivity of the present invention can be best exhibited if the formulation is selected so that the polymerization is completed in one to several minutes. However, if too much co-catalyst is used, nylon with a sufficient high molecular weight cannot be obtained.
This gives it brittle properties. The polymerizable lactam liquid can be prepared by adding the above-mentioned catalyst to the ω-lactam, reacting and dissolving it, and then adding and mixing the above-mentioned co-catalyst before, during or after casting, or with the ω-lactam liquid containing the above-mentioned catalyst. It is prepared by mixing the cocatalyst-containing ω-lactam liquid before, during, or after casting.

The temperature of the polymerizable lactam liquid can range from 70°C to 200°C, but is most preferably 130°C to 170°C.

In addition, when carrying out the method of the present invention, dyes that do not substantially interfere with polymerization are added to the polymerizable lactam solution.
Or pigments, powder fillers such as carbon black, graphite, titanium white, calcium carbonate, glass powder, aluminum powder, reinforcing agents such as short carbon fibers, short glass fibers, wollastonite, or oils, waxes, etc. It is also possible to carry out the polymerization in the presence of an appropriate lubricant such as zinc (calcium) stearate. Conventionally, lactam liquid is 1 to 10 cps
Since it is a liquid with extremely low viscosity, fillers, reinforcing agents, and
Although it has been difficult to uniformly disperse lubricants, the method of the present invention polymerizes extremely rapidly, making it possible to disperse them relatively uniformly.

Examples will be shown below, but the method of the present invention is not limited thereto.

Example 1 A mold (shown in Figure 1) with cavity dimensions of 11 mm x 630 mm x 700 mm, consisting of 10 mm thick iron plates 1, 1, and 2 equipped with an oil jacket 4 and an 11 mm thick spacer 2, was used. , Heat medium oil whose temperature is constantly controlled to 150°C is circulated through the oil jacket 4 of this mold at a flow rate of 30°C per minute, and the temperature inside the mold is kept at 135°C to 145°C.
was held at

Substantially anhydrous ε-caprolactam was heated to 100°C and 2.5 kg each was collected into two flasks in Step 3.
In one flask, add sodium hydride (oil-based, 63
%) was added and reacted and dissolved. 22.0 g of 4.4'-diphenylmethane diisocyanate was added to the other flask, and 2 kg of milled glass fiber P-117B1/16'' from Owens-Corning Fiberglass Co., which had been heated to 100°C, was added and mixed. After heating the two liquids to 140°C, they were mixed and poured into the above mold, and immediately after casting, vibration was applied through the pedestal 5 for 10 seconds with an air hammer, and during casting, heat medium oil whose temperature was constantly controlled at 150°C was circulated. , The lactam solution gels and loses fluidity in 1 minute after casting, begins to whiten due to crystallization in 2 minutes, peels off in 5 minutes, completely peels off in 6 minutes, and opens the mold. 10mm easily without
I was able to extract a high quality reinforced nylon plate material measuring 600mm x 600mm. Immediately after releasing the mold, the same casting operation as above was performed for the second time, and as a result, a reinforced nylon plate free of defects such as air bubbles could be easily taken out without opening the mold 6 minutes after casting.

The resulting reinforced iron has a specific gravity of 1359 and a tensile strength of 1110.
Kg/cm ² , elongation rate 3.1%, bending strength 2360Kg/cm ² , flexural modulus 65.3×10Kg/cm ² , notched isot impact strength 5.8Kgcm/cm 2 , compressive strength 1800Kg/cm ² High rigidity. The physical properties were shown.

Example 2 A mold ( Steam at 150°C was passed through the oil groove 12 (shown in Figure 2) to maintain the inner surface of the mold at 140°C.

5 kg of substantially anhydrous ε-caprolactam was taken into two 2.5 kg flasks and melted by heating to 100°C. 16.1 g of sodium hydride (oil-based, 63%) was added to one flask and reacted and melted.
Add 31.6g of N,N′,N″-trisphenylisocyanurate to the other flask, and add 2Kg of
Owens-Corning Fiberglass Milled Glass Fiber P-117B1 heated to 100°C
16" was added and mixed well. After heating the above two liquids to 140℃, mixing them, and casting them into the mold heated to 140℃, 150℃ steam was passed through the oil groove of the mold. , it gels in 1 minute after casting and begins to whiten in 2 minutes,
Completely peels off in 6 minutes, easily without opening the mold
We were able to extract a 10mm x 600mm x 600mm high-rigidity glass fiber-reinforced nylon plate material with no defects such as bubbles. Immediately after taking out the product, the same casting operation as above was performed again, and a high quality nylon plate could be easily taken out in 6 minutes without opening the mold.

Comparative Example 1 Cavity dimensions consisting of two 3mm thick iron plates with reinforcing bars on the outside and a 11mm thick spacer.
A mold measuring 11 mm x 630 mm x 700 mm was heated to 140°C in a hot air oven.

Substantially anhydrous ε-caprolactam was heated to 100°C, and 2.5 kg each was divided into two flasks.
In one flask, add sodium hydride (oil-based, 63
%) was added and reacted and dissolved. 22.0 g of 4.4'-diphenylmethane diisocyanate was added to the other flask, and 2 kg of milled glass fiber P-117B1/16'' from Owens-Corning Fiberglass Co., which had been heated to 100°C, was added and mixed. The two liquids were heated to 140°C and then mixed to prepare a polymerizable lactam liquid with the same components as in Example 1,
It was immediately cast into the above mold. After heating in a hot air circulation oven at 140°C for 5 minutes, the mold was taken out of the oven, but the polymerization system had just begun to crystallize, and the outer periphery in contact with the mold wall was seen to be cloudy. Immediately, the mold was returned to the hot air oven at 140℃ and left to stand. After 25 minutes, the nylon plate peeled off from the mold, but some of it was still attached to the mold and the product could not be removed, so the mold was removed. I was able to disassemble it and get the product out. There were parts of the product with a large amount of unreacted monomer adhering to the surface due to the uneven heat of the mold, and many bubble defects were scattered on the surface and inside. Heat the mold to 200℃ for the second casting.
Although the mold was preheated in a hot air oven, it took two hours for the mold to reach the desired temperature.

As described above, according to the method of the present invention, a mold of 130
By forcibly maintaining the temperature in a specific range of ℃ to 170℃ and injecting a polymerizable lactam liquid into the mold, the nylon molded body polymerizes extremely rapidly, and the molded body becomes gold. Because it is quickly and completely peeled off from the mold, it can be easily taken out without having to disassemble the mold, and since the mold temperature is maintained at a constant temperature, the next molding can be carried out immediately. This is a method by which a nylon material can be obtained at an extremely high speed, and the physical properties of the nylon material obtained in this way are as good as those of the conventional method.

Since vibration is applied during or after casting, the air bubbles present in the polymerizable lactam liquid are removed, ensuring a product with no air bubbles mixed in on the surface or inside. Conventionally, the air bubbles mixed in during casting are highly viscous. This method makes it possible to manufacture high-rigidity cast-molded nylon reinforced with high fillers of glass fiber, etc., without any defects on the outside or inside, and at high speed. .

[Brief explanation of the drawing]

1 and 2 are partial longitudinal sectional views of a mold used in the method of the present invention, and FIG. 3 is a graph showing the relationship between the time after nylon casting and the temperature of the polymerization system during nylon polymerization. 1, 9... Iron plate, 2, 10... Spacer, 3,
11...Cavity, 4...Oil jacket,
12... Oil groove, 13... Air hammer pedestal.

Claims (1)

[Claims] 1. In a method for producing cast nylon material with a thickness of 2 mm to 20 mm at high speed, the mold is heated to 130°C to 170°C.
Injecting a polymerizable lactam liquid into the mold while forcibly maintaining the temperature at an arbitrary temperature within the range, and while the polymerizable lactam liquid is in a liquid state, vibrating the mold and polymerizing; A method for high-speed production of a cast nylon material, characterized in that the obtained nylon molded product is rapidly and spontaneously peeled off from the surface of the mold.