JPS63147609A - Kneading method - Google Patents

Abstract

PURPOSE:To blend silicone in high concentration with base resin by a method wherein 1-30wt% of beads having the mean particle diameter of 0.2-0.8mm and 99-70wt% of base resin pellets are used in combination with silicone. CONSTITUTION:In a mixer-agitator, 99-90wt% of spherical, cylindrical or prismatic pellets 1a, each of which is made of polystyrene resin, acrylonitrile- butadiene-styrene resin, acrylonitrile-styrene resin or the like and the diameter or one side of which is 2-5mm, and 1-30wt% beads 1b of mean particle diameter are mixed with each other and, after that, extruded with a kneader-extruder 3. As for mixing, one mixture is firstly made by mixing the pellets with silicone and the other is also made by mixing the beads with silicone, and then they may be mixed with each other. Since the silicone is held by the pellets and by the beads, the effects due to the lubricity and viscosity of silicone are suppressed and lumps are prevented from developing, resulting in allowing to stably maintain the supply of the resin and the silicone.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of kneading a base resin and an additive, and in particular, a method for kneading a base resin and an additive, particularly when the base resin is a polystyrene resin (hereinafter referred to as PS resin) and the additive is silicone. The present invention relates to a kneading method in which

[Prior Art] Conventionally, when kneading additives such as reinforcing agents into a base resin, the base resin pellets and the additives are first put into a mixing agitator (for example, Hengeno C mixer), mixed and agitated, and then taken out 2.
Then, it is melted by a kneading extruder (for example, single-screw or two-wheeled),
Kneading and extrusion are common. 1. The processing amount, particularly the discharge amount, by a normal kneading extruder depends on the fluidity of the base resin.

The higher the fluidity, the greater the discharge amount.

However, when the additive is silicone (for example, Utility Model Application No. 59-46356), the amount discharged by the kneading extruder depends more on the amount of silicone added than on the fluidity of the base resin, and the amount added becomes large. As the temperature increases, the discharge amount decreases rapidly (see Figure 9 below).

The reason for this is due to the properties of silicone itself, namely lubricity and volatility.

First, due to the lubricity of silicone, the base resin pellet slips against the kneading screw, reducing the amount of heat generated by shearing and preventing the plasticization of the base resin pellet from proceeding, thereby reducing the discharge amount.

Such a situation occurs regardless of the high or low viscosity of the silicone. In addition, when adding silicone with a viscosity of about 10,000 aS or less, if it is added in excess of 5 wt%, the silicone that does not adhere to the base resin pellet will accumulate at the bottom of the kneader hopper.
The base resin pellets and the screw feeder slip, making it impossible for the pellets to move, resulting in unstable supply.

Second, the volatility of silicone (i.e., above about 200°C,
generating volatile oxidation products such as formalin)
However, if the melting temperature is increased, the amount of volatile matter increases and there is a quality problem, so promoting plasticization only by increasing the melting temperature is regulated. Also, the viscosity increases (
For example, at around 30,000 cs), the base resin pellets with silicone attached will stick together and form large lumps, making movement with the screw unstable, and in the worst case, a situation that cannot be transported with the kneading screw. will occur.

For the above reasons, conventionally, when a large amount of silicone is added and kneaded, productivity decreases and the price increases. That is, it has been impossible to obtain a silicone compound with high productivity by mixing and purifying a conventional pellet-shaped resin and silicone.

[Problems to be Solved] ゛An object of the present invention is to provide a method for kneading base resin and silicone that can stably maintain high processing speed using a kneading extruder even when silicone is blended at a high concentration. be.

[Means for solving the problem] Here, if silicone is added to the resin consisting only of beads,
Due to the viscosity of the silicone, it sticks together and forms lumps, which causes a bridging phenomenon under the feed hopper of the kneader, making it impossible to feed. Therefore, the situation was such that complicated measures such as those described in Japanese Patent Publication No. 40162/1980 had to be taken.

Therefore, the inventors of the present invention solved the above problem in view of the actual situation (as a result of intensive research, the base resin was made into a bead shape together with the pellet),9 and the two were present in a predetermined ratio to be mixed with silicone. As a result, we have found that it is possible to stably maintain an extremely high discharge rate compared to the case where a pellet is used alone, and this is what we propose here.

That is, 1. The method of kneading base resin and silicone according to the present invention is to mix the base resin with 99 to 70 wt% of pellets and 1 to 70 wt% of beads.
30 wt%, and the average particle size of the beads was 0.
．． 2-0, 811Im.

[Function] In the present invention having such characteristics, J! Base resin beads may exist along with silicone on the outer periphery of the material resin pellets, and the influence of the slipperiness of silicone can be suppressed.

The large surface area of the beads increases the amount of silicone deposited on the bead surfaces, and thus the overall base resin surface, and reduces the amount of silicone that accumulates at the bottom of the kneader hopper.

Beads may also exist between the pellets, and these intervening beads weaken the adhesion between the pellets, maintaining a so-called pellet separation body in which only the beads and silicone adhere to the outer periphery of the pellets. Generation of lumps can be suppressed.

The sizes and positions of the base resin pellets, beads, and silicone are schematically shown in FIGS. 1 and 2. FIG. 1 shows the conventional one, and FIG. 2 shows the one of the present invention. In each figure, 1 is the base resin.

2 represents silicone, and 1a represents base resin pellets,
lb indicates the base resin beads.

[Preferred Embodiment] As a preferred example, PS resins including PS resin, ABS resin, AS resin, etc. will be explained.

PS resins include CP type, HI type, Ml type, etc., and these can be used alone or in combination. When used together, one of the pellets or beads is type II and the other is type G.
It is preferable to use P type.

2 normal pellets can be used, and the diameter or side is 2.
11III to 5■, and may be two spherical, one cylindrical, or prismatic.

The amount of beads is preferably 1 to 30 wt%. This is because if it is less than 1 wL%, no effect will be exhibited, and if it exceeds 30 wt%, beads will stick together due to the viscosity of the silicone, forming lumps. The average particle diameter of the beads is determined taking into consideration the size of the pellet, but is preferably 0.2 to 0.8
When the range is set to am, the desired effect is obtained.

Silicone is a general term for organopolysiloxanes, and is added for the purpose of imparting surface smoothness, water repellency, etc. In particular, those having a dimethylpolysiloxane structure are often added, but more than one type may be added.

Even when added at a high concentration of 3 wt% or more, a stable treatment amount can be maintained. Its viscosity ranges from 3.000 to 100. Goo as
(25°C) 1 Usually 5.000 to 60.000 cs can be blended.

The method of mixing these base resin pellets, beads, and silicone may be either batch mixing or two-stage mixing. For example, the pellets, beads, and silicone may be mixed simultaneously, or the pellets and silicone may be mixed while the beads and silicone are mixed, and then the mixtures thereof may be mixed.

Additives other than silicone are added to the base resin for various purposes, such as light-shielding substances (carbon black, calcium carbonate, metal powder, metal fibers), lubricants, antioxidants, antistatic agents, other thermoplastic resins, There is no problem in adding silica or the like.

As the kneading extruder, various types such as a single screw or two-wheel type can be used. An apparatus for carrying out the method of the present invention will be briefly explained based on FIGS. 3 to 5. In each figure, 3
is a twin-screw kneading extruder (for example, CPM-30 manufactured by Yusho Tekko)
), 4 is a cooling tank, 5 is a cutting machine, about the kneading extruder 3, 6 is a hopper into which the mixture taken out from the mixer (not shown) is charged, 7 is a screw feeder, 7a
... is its protrusion, 8 is the chute, 9 is two kneading screws arranged in parallel, 9a... is its protrusion, 10
1 is a drive motor that rotates the kneading screw 9; 11 is a cylinder; 12 is a band heater provided on the outer periphery of the cylinder; 13 is an extrusion nozzle; Shows bendro eliminating mixture. In such devices, conventionally, the mixture is passed through a kneading screw 9 at the bottom of the feeder 7 or chute 8.
A lump may form between the
Furthermore, a bridging phenomenon occurs at the hopper 6 or chute 8 portion.

This made it difficult or impossible to move the processed materials.1
In the method of the present invention, the processed material does not become lumps, but enters between adjacent protrusions 7a, 7a or protrusions 9a, 9a at the screw feeder 7 or kneading screw 9 site,
This allows for stable movement.

In this apparatus, the kneaded material discharged from the extrusion nozzle 18 and turned into strands is cooled in the cooling tank 4, cut into pieces by the cutter 5, and pelletized again.

The compound obtained by the kneading method of the present invention has various uses 1.
For example, the body member of a film cartridge (Fig. 61)
It is used for such things.

[Example].

The present invention will be described below based on two examples.

Example 1 (Conditions) The following materials were used, the blending ratio of silicone was fixed at 1 Owt%, and the change in discharge amount was measured by changing the ratio of pellets to beads in the base resin. In this case, the test temperature was set at 240°C.

Two-stage mixing was adopted. Please note that the discharge amount is measured.

This was done by measuring the weight of the kneaded product that was finally pelletized.

(a) PS resin (manufactured by Nippon Polystyrene ■) HI type containing butadiene rubber (sample ■) or homogeneous GP type (
Two types of sample (■) were used, and the average particle size of the beads was 0.4.
n+m, the diameter of the pellet is 3 an, and the length is 4 am.

(b) Silicone (K F 96H manufactured by Shin-Etsu Chemical Co., Ltd.) has a viscosity of 30.000 cs.

(Results) Shown in Figure 7. For HI type, pellets: beads■
When the ratio is 6:3, the discharge amount is about the same as that of pellets only, and the ratio is 8:3.
: When it is 1, it becomes about 1.3 times. In the case of the GP type, when the ratio of pellets to beads is 7:2, the discharge amount is the same as that of pellets only, and when the ratio is 8:1, the discharge amount is about 1.7 times. Note that when the ratio of beads was increased, a bridging phenomenon occurred under the supply hopper, making it impossible to supply the beads, so kneading was discontinued.

Example 2 (Conditions) Changes in the discharge amount were determined under the same conditions as in Example 1 except that the types of PS resin were different between pellets and beads as described below.

Pellet Bead sample ■: HI type (500A) CP type (2
M) Sample ■: GP type (2M) Hl type (
500A) Sample ■: H■ Type (500A) G
P 9 Eve (2x) + GP type (214) The pellets of sample 5 used half of the Hl type and half of the GP type.

(Results) As is clear from FIG. 8, almost the same tendency as in Example 1 (FIG. 7) was shown, and the highest discharge amount was obtained when pellets: beads -8=1.

In the above examples 1 and 2, PS resin was used as the PS resin.

Similar results were confirmed when ABS resin or AS resin was used instead of PS resin.

For reference, Figure 9 shows the general relationship between the amount of silicone added and the discharge rate of the extruder according to the conventional method, that is, the relationship in which the discharge rate rapidly decreases as the amount of silicone added increases. It is shown below.

Note that the test conditions are almost the same as in the examples and are as follows.

・Kneading machine: Oil odor CRM30 ・Temperature = 220°C ・PS resin cylinder Figure 9 is also shown ◆Silicone: KF96H (manufactured by Shin-Etsu Chemical) [Effects of the invention] According to the present invention, various effects such as the following 9 are achieved. play.

(1) Since the effects of silicone's lubricity and viscosity can be suppressed to prevent the generation of lumps as much as possible, its supply can be maintained stably. This improves the productivity of kneading and also contributes to reducing manufacturing and product costs.

(2) Since the surface area of the base resin as a whole increases, 7
! The amount of silicone adhering to the material resin increases, for example, the amount of silicone that accumulates at the bottom of the hopper decreases), and in conjunction with (1) above, 1. It is possible to increase the blending ratio of silicone while maintaining stable kneading, thereby increasing kneading efficiency and production efficiency.

(3) Since the beads can be used for kneading as they are, there is no need to pelletize the beads, contributing to improved production efficiency and cost reduction.

(4) Since the shape of the kneaded material is specified as a means of solving the problem, conventional equipment (e.g. kneading machine) can be used as is, and addition of inorganic substances etc. is not necessarily required, so the shape of the kneaded material can be improved. There is no risk of adversely affecting quality.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing the state of the mixture; FIG. 1 is a conventional mixture, and FIG. 2 is a mixture according to the present invention. Figures 3 to 5 are diagrams showing an example of an apparatus capable of carrying out the method of the present invention, in which Figure 3 is a schematic diagram showing the kneading extruder as a whole, and Figure 4 is a diagram showing the kneading extruder as a whole. The schematic sectional view shown and FIG. 5 are a sectional view taken along the line V-■ in FIG. 4. FIG. 6 is a perspective exploded view showing the use of the kneaded product obtained by the method of the present invention. FIG. 7 and FIG. 8 are graphs showing the results of the examples, in which FIG. 7 is for Example 1, FIG. 8 is for Example 2, and FIG. 9 is for silicone. 1 is a graph showing a general relationship between the amount of addition of and the discharge amount of a kneading extruder. represents. 1...Base resin 1a...Pellet 1b...
・Bead 2... Silicone Figure 1 Figure 2 tel (IJ Figure 3 Figure 5 Figure 6 rIA Figure 9/Silicone, υ0 maximum (wt%) Figure 7 Figure 8

Claims (3)

[Claims] (1) 99 to 70 wt% base resin pellets and beads 1
A method for kneading a base resin and silicone, characterized in that the beads are prepared at ~30 wt% and the average particle size of the beads is 0.2 to 0.8 mm. (2) The kneading method according to claim 1, wherein the base resin is a polystyrene resin. (3) The viscosity of the silicone is 3,000 to 100,0
The kneading method according to claim 1, wherein the kneading temperature is 00cs (25°C).