JPS6237659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for injection of modifiers for base plastic materials.

Our pending application for grant of patent no.
No. 35035/77 describes a method and apparatus in which the coextrusion of plastic materials exhibiting different properties can be carried out using a single base plastic material extruder. In the specification of the above-mentioned application, a method is disclosed for the simultaneous production of a product or a series of products comprising different plastic materials from a single source of basic plastic materials. The method includes the steps of feeding a base plastic material through a screwextruder, dividing a homogeneous plastic material stream from the extruder into a plurality of separate streams, and supplying a liquid containing a modifier for the plastic material. injecting a predetermined amount of an additive into at least one separate stream of base plastic material; metering the various streams of plastic material; and injecting said modifier into each corresponding stream or streams of base plastic material; and dispersing the various plastic materials into an extrusion product stream.

A device for carrying out the above method has also been disclosed, which device comprises a screw-structure extruder for homogenizing the base plastic material and feeding said homogenized material to a manifold for obtaining a plurality of individual streams. an additive injection means for delivering a predetermined amount of a liquid modifier to the at least one stream of base plastic material to disperse the modifier, and an apparatus for forming a plastic material into an extrusion product. .

However, in some cases it has been found that there are difficulties in completely and effectively dispersing the modifier into the base plastic material.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method which is relatively simple to control and apply, is effective in implementation, and which eliminates or substantially eliminates the drawbacks of the prior art described above.

According to the present invention, a method is provided for injecting a liquid additive comprising a modifier for plastic materials into a stream of base plastic material, the method comprising: injecting a liquid additive comprising a modifier for plastic materials into a base plastic material stream; A method of injecting into a material stream, the method comprising dividing a flow of base plastic material at least partially in the material flow direction and injecting the modifier under pressure between the divided streams to inject the modifier into the base plastic material. initially dispersing and mixing the modifier in the form of a film, and then exposing the material with the modifier mixed in the initial dispersion to a shearing action in a homogenizer for further dispersing the modifier in the base plastic material; The method is characterized in that it includes.

Apparatus for carrying out the above method is an apparatus for injecting a liquid additive containing a modifier for plastic materials into a stream of basic plastic material, comprising:
a cylindrical element providing a plastic material flow path; a dividing means disposed transversely to the material flow for at least partially dividing the flow of said basic plastic material; a dispersing means for initially dispersing and mixing the modifier into the plastic material in the form of a film by injecting the modifier under pressure into the divided streams; Mention may be made of a device equipped with a dispersion mixing device for further dispersion into the plastic material.

Hereinafter, an example of the method of the present invention will be described with reference to the drawings, together with an example of an apparatus for implementing the method.

Injection means for dispersively mixing a homogenized base plastic material with a modifier that alters the physical properties of the plastic material will now be described. The explanation is given by way of example of the injection of colored pigments. However, the injection means can also be used to dispersely mix into the basic plastic material modifiers which can be used, for example, to change the chemical properties or the physical and chemical properties of the basic plastic material.

The injection means according to the invention shown in FIGS. 1, 2 and 3 preferably has a cylindrical shape with both ends open;
It also includes a cylindrical element or main body 10 having screws 11 on the outer surfaces of both ends. Thus, body 1
0 can be connected to a base plastic material supply line (not shown). Conveniently, the passage 12 through the body 10 has the same diameter as the internal diameter of the supply line to which it is to be connected.

Hollow needles 13 are provided around the periphery of the body 10 at 120° intervals and projecting inwardly between the ends of the body (see FIG. 2);
4 (see FIG. 1) is fixed to the main body 10 by screwing into a female screw carved into the wall of the main body 10. Preferably, a manifold 15 (shown in phantom in FIG. 2) or other means is provided externally of the body 10, to which three radially arranged needles 13 are connected. Means such as a pump (not shown) for directing colored pigment to needle 13 is connected to manifold 15 via supply line 16 . If desired, each needle can be supplied with pigment from a separate source, in which case a pump is provided for each needle.

As can be seen from FIG. 3, the needle 13 may be provided with a core 17 that controls the cross-sectional area of the needle bore. Core 17
The cross-sectional area of is selected such that the annular space formed as the colored pigment passage has the following size: That is, the size is such that the plastic material flowing through the passage 12 of the body 10 is substantially completely prevented from flowing into the annular space in the needle in a direction opposite to the flow direction of the colored pigment.

In use, the injection means is downstream of a homogenization device (e.g. a screwextruder) for the base plastic material and a homogenization device that ultimately mixes the base plastic material and the added modifier. (preferably a gear pump).

In use, the flow of base plastic material flowing along the supply line in the direction of arrow A is unified by a hollow needle 13 projecting inwardly from the inner wall of the body 10 towards the body axis as it passes through the cylindrical injection means. section is divided. The colored pigment is pumped, injected through the needle and distributed on the inner surface 18 formed in the base plastic material 19 in the region downstream of the needle 13. The colored pigments are thus dispersed and mixed into the base plastic material. The mixing is not only due to the pigment being pumped to the inner surface, but also because at least some of the modifier is present in the base plastic material 1.
9 and the inner wall of the body 10, the plastic material 19 tends to migrate at least in part 20 around the periphery.

The dispersively mixed material exits the injection means and enters the final mixing homogenization device along the line downstream thereof. Preferably, the equalization device is a gear pump as described above.

Although an example of an injector having needles 13 at 120° intervals on the inner peripheral surface of the injector main body has been described above, it is also possible to provide many modifications of the injector. For example, there may be more or less than three needles, and they may be spaced within the body at a spacing different than 120°. In its simplest form, a single needle is provided.

It is also possible to provide a higher degree of dispersive mixing than that achieved by the apparatus shown in FIGS. 1, 2 and 3. To achieve this, the main body 10
A dividing body is arranged in the axial direction within the shaft. One possible device is shown in FIGS. 5 and 6. Preferably, two divided bodies 21 are provided to form three separate passages 22 in the body 10 of the injector. A needle 13 is preferably located in each passageway 22. The needle is connected via a connection 23 to a manifold (not shown) or to a separate pump.
Of course, more than three passages 22 can be provided if desired. It will be appreciated that when multiple passages are provided, it is advantageous to provide a needle for each passage. Alternatively, some passageways may be left without needles. In a device of the type just mentioned, the modifier not only tends to flow to the inner surface created by the splitting of the basic plastic material by the presence of the needles, but also to the basic plastic material created by the splitting bodies 21 in the holes of the body. There is also a tendency to flow internally.

Figures 7 and 8 show the above situation. FIG. 7 shows the material situation that would occur if there was only one needle 13, and FIG. 8 shows the material situation that would occur if there was a needle in each passage.

The degree of dispersive mixing achieved will make it increasingly easier to further disperse the colored pigment into the base plastic material in the final mixing homogenizer.

It is also possible to provide an additive injection device to be associated with the dividing body. In that case they serve as a substitute for needles. In the case of such an injector, the modifier can be preferably injected from the downstream end of the split body or at a position intermediate between the ends. An apparatus capable of making additions between the ends of the split body is shown in FIGS. 9 and 10.

In this illustrated structure, a dispersion device is provided that has a two-part body. The two parts 24 and 25 are adapted to abut against each other in a plane transverse to the flow direction of the plastic material in each part, and the pair of divided bodies 26 and 27
When the parts 24, 25 are assembled, they provide three grooves 28 which extend in the axial direction of the body. The surface of one portion 25 is stepped as shown at 29 around the central groove 28, as shown in particular in FIG. Portion 25 includes a supply passage 30, one end of which is enlarged and equipped with a connector for an additive supply pipe (not shown). aisle 30
The other end is connected to the stepped portion 29. The size of the axial gap formed by the step 29 is such that the base plastic material is located at the step 2 opposite the direction of inflow of the colored pigment.
The selection is made in such a way that there is virtually no possibility that the water will flow into the water. As shown by dashed lines 31 in FIG. 10, the steps may be sized to surround three (or other number) grooves 28 formed in the device.

It is preferable that flanges are provided on the two parts constituting the main body, and the two parts are coupled with fixing bolts 32.

FIG. 11 shows the dispersive mixing condition achieved when the step surrounds only the central groove 28. FIG. 12 shows a dispersive mixing state where all grooves are surrounded by steps.

If the step surrounds all the grooves, the resistance to liquid additive flow is reduced.

To prevent needle or shoulder clogging due to back flow of the base plastic material into the additive supply path, thereby preventing modifier flow into the plastic material flowing through the injector. It should be noted that it is initially necessary to begin pumping the modifier into the device.

The plastics can be manufactured by tilting the needle in the direction of flow of the basic plastic material or by arranging the end of the needle parallel to the body axis, for example when there is a dividing body with grooves for the inflow of additives as described above. The risk of material flowing back into the needle can be somewhat prevented.

As described above, according to the present invention, a single flow of the base plastic material is divided into a plurality of streams, and the plastic material modifier is initially dispersed and mixed in a film between the divided streams, and as a result, the plastic material modifier is initially dispersed and mixed in the form of a film. The modifier is further dispersed around the plastic material stream and then both are further mixed together, which has the advantage of good dispersion and mixing of the modifier into the plastic material.

[Brief explanation of the drawing]

The drawings show an example of an apparatus for carrying out the method of the present invention, and FIG. 1 is a longitudinal cross-sectional side view of one embodiment of the dispersion means based on the present invention, with some parts omitted for clarity. Figure 2 is a sectional view taken along line - in Figure 1, showing the parts omitted in Figure 1, Figure 3 is an enlarged sectional view taken along line - in Figure 1, and Figure 4. is a cross-sectional view of the dispersed and mixed material exiting the dispersion means shown in FIGS. 1 to 3; FIG. 5 is a longitudinal side view similar to FIG. 1 of another embodiment of the dispersion means; FIG. FIGS. 7 and 8 are illustrations showing two possible modes of dispersive mixing obtained from the apparatus shown in FIGS. 5 and 6; FIGS. The figure is a longitudinal side view similar to FIG. 1 of yet another embodiment of the dispersion means;
Figure 10 is a view similar to Figure 2 of the apparatus shown in Figure 9; Figures 11 and 12 are similar to Figures 9 and 10;
8 is an illustration similar to FIGS. 7 and 8 showing the product obtained using the illustrated apparatus; FIG. 10... Main body, 13... Hollow needle (hollow needle device), 15... Manifold, 17... Core, 19
... Basic plastic material, 21 ... Divided body, 2
2...Divided passage, 24, 25...Parts constituting the main body 10, 26, 27...Pair of divided bodies, 2
8...Divided passageway, 29...Stepped section, 30...
Hole.

Claims (1)

[Scope of Claims] 1. A method for injecting a liquid additive containing a modifier for plastic materials into a flow of basic plastic material, the method comprising dividing the flow of basic plastic material at least partially in the direction of material flow. , the modifier is injected under pressure between the split streams to initially disperse and mix the modifier into the base plastic material in the form of a film, and then further disperse the modifier into the base plastic material. A method characterized in that the material in which the modifier has been mixed is subjected to shearing action in a homogenizing device for the purpose of dispersion of the modifier. 2 Partially dividing the flow of basic plastic material with a hollow needle inserted in a direction transverse to the flow, and passing the modifier through the hollow needle to divide the modifier. 2. A method according to claim 1, characterized in that the method comprises injecting into the stream. 3. Claim 2, characterized in that a plurality of the hollow needles are provided, and the modifier is pumped through a manifold common to at least two of the needles.
The method described in section. 4. Dividing the flow of the basic plastic material into at least two separate streams, at least partially dividing at least one of the separated streams by a hollow needle inserted in a direction transverse to the stream, and dividing the flow through the hollow needle. 2. The method of claim 1, further comprising injecting a modifier into said one separated stream and then recombining said separated streams. 5 splitting the flow of base plastic material into at least two separate streams, injecting the modifier into the plastic material at at least some of the locations where the plastic material is separated; The method according to claim 1, characterized in that the modifier is initially dispersed and mixed between the separated streams after recombination.