JPH0464495B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reaction injection molding screw used for injection molding of multi-component reactive resins.

[Prior Art] The design of screws for the purpose of high kneading has been studied in various fields, and various designs have been developed. Among these, those using a single-shaft screw can be broadly divided into: (1) A method in which a dynamic mixing section is provided in a part of the screw.

(2) A method in which a section is provided in a part of the screw to increase flow resistance and increase energy conversion.

(3) A wave method in which the depth of the screw groove is raised in a liquid state and the unmolten resin is repeatedly compressed and stretched.

There are three methods.

As the dynamic mixing section of the above method (1), known methods include a dalmage type in which a plurality of protrusions are formed around a screw shaft in parallel or at an angle, and a pin type in which a plurality of pins are protruded around the shaft. .

Further, as an energy conversion means of method (2), a dam ring type in which a barrier flight with a larger lead angle than the flight is provided around the axis between the screw flights and an annular barrier ring is provided around the variable axis; Known types include a cylindrical gap type in which a choke is provided with the width of the barrier ring expanded, and a fluted barrier type in which a large number of grooves are arranged in parallel in a large diameter portion formed around the shaft.

Furthermore, as described in Japanese Patent Publication No. 58-2056, there is also a metering zone constructed by combining the above methods.

[Problems to be Solved by the Invention] However, since the above-mentioned method is aimed at melting and kneading pellet-like resin materials, it is possible to melt and knead resin materials in the form of pellets. , kneading and measuring urethane rubber, polyethylene resin, etc. and liquid curing agent,
When RIM (Reaction Injection Molding) is used for kneading and measuring polyol liquids and isocyanate liquids, an inconvenient situation arises and there is a problem in that sufficient kneading cannot be carried out.

This is because the liquid material used for LIM and RIM is low in clay and is supplied into the injection device under pressure by a pail pump, supply plunger, etc., so it is equipped with a dynamic mixing section. Even if it is, the material passes through without being sufficiently kneaded and is filled into the cavity in that state, resulting in uneven curing reaction. This kind of thing occurs regardless of whether the channel resistance is provided or the groove depth is changed to a liquid state, and the resulting product is inferior in strength.

Furthermore, in Japanese Patent Publication No. 58-2056, the outflow can be suppressed by the resistance of the flow path, and the mixing can be performed before the outflow, resulting in higher mixing than the above method, but since the mixing is done at high pressure, the injection tube The reaction progresses inside the injection tube, which adversely affects the molding quality, and in some cases causes hardening inside the injection cylinder.In addition, the laminar flow is only stretched out in front of the mixing section, and then Because of the stirring, there was a problem that the kneading was not sufficient.

This invention was devised to solve the above problems, and its purpose is to be able to sufficiently knead a liquid material and a liquid curing agent with a simple structure, and to be extremely effective in performing reaction injection molding. The aim is to provide a new configuration of scrolls.

[Means for Solving the Problems] The invention according to the above object includes a barrier section for increasing the flow path resistance at the starting part of the metering zone of the injection screw, and a mixing section for stirring the material when the screw rotates at the end part of the feed zone. The barrier section is of a dam ring type, cylindrical gap type, barrier flight type, fluted barrier type, etc., and the mixing section is of one or more of a dalmage type, a pin type, etc., or a combination thereof. Consists of combinations.

[Function] In the reaction injection molding screw described above, the liquefied material and liquid curing agent supplied to the feed zone are stretched in the feed zone, and then stirred and distributed by the mixing section and diffused, resulting in compression. The material is sent to the metering zone, further stretched, diffused again in the barrier section, enters the metering zone, stretched again in the metering zone, homogenized, and transferred to the front section of the screw.

[Embodiment] In the figure, reference numeral 1 denotes an injection screw, which is provided in the injection cylinder 2 so as to be rotatable and movable forward and backward. The rear part of the screw 1 is provided with a U-packing 3 provided at a position that does not interfere with the supply port 4 at the rear of the injection tube 2 when the screw is fully advanced.
This prevents resin leakage.

In addition, the portion of the injection screw 1 having the flights 5 has a feed zone A with a smaller valley diameter than the rear side located at the supply port 4, a compression zone B where the valley diameter gradually increases, and a metering zone with a large valley diameter. Divided into 3 zones of C, Flight 5
is provided in a spiral around the screw shaft for each zone.

At the end of the feed zone A, there is a mixing section 6 that stirs the material when the screw rotates.
It is formed with a smaller opening area than the feed zone A, and the metering zone starting portion is formed in a barrier section 7 that increases flow resistance.

The mixing section 6 shown in FIG.
Alternately shift the positions of each piece at the required intervals 2
It consists of two Dalmage molds arranged around the shaft in a row, but there are also Dalmage molds in which a plurality of protrusions 62 are formed parallel or inclined around the screw shaft (see Figs. 7 to 9), and a shaft. Multiple pins 6 around
It is formed with a pin type (see FIG. 10 and FIG. 11) in which multiple numbers of 3 are protruded from each other alternately.

Furthermore, the barrier part 7 in FIG.
It consists of a cylindrical gap type in which flight 1 is protruded around the shaft, but if the lead angle is larger than flight 5, there is also a barrier flight type in which flight 72 is installed around the shaft (see Fig. 4), and a damming ring with ring 73. It is formed by a mold (see FIG. 5), a fluted barrier type (see FIG. 6), etc. in which a large number of grooves 74 are arranged in parallel in a large diameter portion formed around the shaft.

In the figure, reference numeral 8 denotes a supply block provided at the supply port 4, which has a liquid material path 9 and a liquid curing agent path 10.

Materials such as polyol liquid and isocyanate liquid are supplied from the supply path 4 to the injection cylinder 2 in which the injection screw 1 is installed, and the injection screw 1 is rotated by ordinary means to perform kneading and metering while controlling the back pressure. Since the opening area of the mixing part 6 and the barrier part 7 is small and the flow resistance is large, even if the material has a low viscosity, it will not easily pass through, and the material will not easily pass through the screw groove formed between the flights 5. stay.

The material supplied to the feed zone A is stretched and kneaded while being sent forward by the supply pressure and the transfer force by the flight 5, and is then agitated and distributed in the mixing section 6, and is sent to the compression zone B after being dispersed.

In compression zone B, the material is transferred forward and subjected to stretching and kneading action again.
Furthermore, since there is a barrier section 7 in front, the amount transferred to the metering zone C is limited. This restriction increases the material pressure in the compression zone B and stores the energy required for sufficient mixing and transfer across the barrier section 7 to the metering zone C.

In the metering zone C, diffusion is first performed in the barrier section 7, and the material is further transferred to the front while being stretched and kneaded to reduce its weight. At this time, since the flight 5 exists in the front part of the barrier part 7,
This ensures uniform temperature and stable measurement.

[Effects of the Invention] As described above, the present invention includes a barrier section 7 that increases the flow path resistance at the beginning of the metering zone C of the injection screw 1, and a mixing section 6 that stirs the material when the screw rotates. Since it is provided at the end of feed zone A, multiple types of liquid materials are not kneaded under unnecessary pressure, and the material stays for a long time so that it is sufficiently kneaded and weighed while moving through each zone. As a result, the curing reaction after injection is uniform, and a reaction injection molded product with excellent strength can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the reaction injection screw according to the present invention, in which FIG. 1 is a partially vertical front view of the reaction injection screw installed inside the injection tube, FIG. 2 is a cross-sectional view taken along the line of FIG. The figure is a cross-sectional view taken along the - line, FIGS. 4 to 6 are explanatory diagrams of other embodiments of the barrier section, and FIGS. 7 to 11 are explanatory diagrams of other embodiments of the mixing section. 1... Injection screw, 2... Injection tube, 4... Supply port, 5... Flight, 6... Mixing section, 7
...Barrier section.

Claims (1)

[Scope of Claims] 1. A barrier part for increasing flow path resistance is provided at the starting part of the metering zone of the injection screw, and a mixing part for stirring the material when the screw rotates is provided at the end part of the feed zone. A screw for reaction injection molding. 2. In the screw for reaction injection molding according to item 1, the barrier part is of a dam ring type, cylindrical gap type, barrier flight type, fluted barrier type, etc., and the mixing part is one of a damage type, a pin type, etc. 1. A screw for reaction injection molding, characterized in that it consists of a plurality of or a combination thereof.