JPH04183798A - Detergent for molding machine - Google Patents

Abstract

PURPOSE:To obtain the title detergent giving high detergency even on high- temperature molding materials, with little residual glass fiber, also capable of markedly cutting washing time and the amount of washing resin, by incorporating a thermoplastic resin of specific physical properties with a specified amount of glass fiber. CONSTITUTION:The objective detergent can be obtained by incorporating (A) a thermoplastic resin consisting of pref. a styrene/acrylonitrile copolymer, 0.5-30g/10min (220 deg.C, 10kg) in melt flow rate with (B) 30-50wt.% of glass fiber with a mean fiber length of ca.0.1-10 mm and mean fiber diameter of ca.1-40mum. For the component B, it is preferable that the coupling agent content be set at 2000-3000ppm through increasing the agent by 200-300wt.% compared to the case with glass fibers commonly commercially available intended for use in plastics.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to a thermoplastic resin (hereinafter simply referred to as "resin") molding machine that, when a predetermined operation is completed, removes the resin itself and the molding material remaining in the molding machine. This invention relates to a cleaning agent for removing additives such as dyes and pigments contained in

[Prior Art] Generally, molding machines (extrusion/injection) are used for the purpose of coloring, mixing, molding, etc. of resin, but when a predetermined work is completed,
The resin itself and additives such as dyes and pigments contained in the molding material remain in the molding machine. This residue is mixed into the molded product during the next molding using a different type of resin or a different color resin, causing a poor appearance of the product.

Conventionally, in order to remove the above-mentioned residue from inside the molding machine, there have been methods such as manually disassembling and cleaning the molding machine, and filling the molding machine with the molding material to be used next without stopping the molding machine. Methods of gradual replacement and methods using commercially available cleaning agents have been implemented.

In particular, the following are known as the above-mentioned commercially available cleaning agents.

(1) Ultra high molecular weight acrylic resin containing a blowing agent, kaolin and calcium carbonate (semi-molten type).

(2) A resin containing a surfactant (completely melted type).

(3) Metal soap containing foaming agent (blend type).

On the other hand, it is also known to use a resin composition prepared by adding 1 to 20 parts by weight of glass fiber per 100 parts by weight of resin to the same type of resin used after cleaning (Japanese Patent Publication No. 53
-41711).

[Problems to be Solved by the Invention] However, manual disassembly and cleaning requires a large number of people and a long time, which is a major cause of reduced productivity.

Furthermore, there is also the problem that residue remains on parts of the molding machine that cannot be easily disassembled due to its structure, such as on the inner wall of the cylinder.

In the method of replacing the molding material with the molding material to be used next, the molding material intended for molding is not designed to be suitable for cleaning, so the cleaning effect is low, and a large amount of molding material is wasted. , cleaning takes a long time. In addition, depending on the type of residue, such as heat-degraded rubber products, it may not be possible to remove them.

Methods using commercially available cleaning agents have not been widely used since all cleaning agents have the following fatal drawbacks as cleaning agents.

(1) Semi-molten cleaning agents tend to remain in the molding machine, and are likely to mix into the next molding material, causing foreign matter problems.

(2) Completely melted cleaning agents have low cleaning effects and tend to remain in the molding machine (and it takes time and effort to completely drain them).

(3) Blend-type cleaning agents have low cleaning effects and require preliminary boiling of the resin, making them time-consuming to use.

Furthermore, when 1 to 20 parts by weight of glass fiber is added to 100 parts by weight of the same type of resin as the molding material to be used next, the cleaning effect is still insufficient, especially when cleaning high-temperature molding materials. big. Furthermore, when using various resins at the same molding site, it is necessary to prepare glass fiber additives for each type of resin, which is complicated.

[Means for Solving the Problems] The present invention has been made with a focus on such conventionally unsolved problems, and uses a resin having a melt flow rate within a specific range as a cleaning agent for residue in a resin molding machine. This product was completed after discovering that a combination of a large amount of glass fiber and a large amount of glass fiber has a high cleaning effect even when cleaning high-temperature molding materials, and that there is little residual glass fiber, significantly reducing cleaning time and cleaning resin. It is what was done.

That is, in the present invention, the melt flow rate is 0.5 to 30 g.
/10 minutes (220° C., 10 kg), the resin contains more than 30% by weight and less than 50% by weight of glass fiber.

The resin used in the present invention has a melt flow rate of 0.
．． 5 to 30 g/10 minutes (must be 220°C-1C-1O. Melt flow rate is 0.5g/1
For less than 0 minutes, standard molding conditions, e.g. molding temperature 20
It cannot be used at a temperature of 0 to 280°C, and if it exceeds 30 g/10 minutes, not only is it difficult to obtain a sufficient cleaning effect, but glass fibers tend to remain.

As the resin used in the present invention, a wide variety of general resins used for injection molding, extrusion molding, etc. can be used as long as the melt flow rate is within the above range. Specific examples include polyethylene, polypropylene, polystyrene,
ASfM resin, ABS resin, polymethyl methacrylate,
Examples include polyvinyl chloride, polyamide resin, polycarbonate, and polybutene. Further, these resins may be used alone or in combination of two or more.

In the present invention, as described above, a wide range of resins can be used, but it is preferable that the type of resin has the same composition as the resin used for molding after cleaning. A styrene-acrylonitrile copolymer (AS resin) is preferable because it provides a high cleaning effect regardless of the type of cleaning agent, and various resins can be cleaned with a single cleaning agent.

The AS resin preferably has an acrylonitrile content of 5 to 50% by weight. If the acrylonitrile content is less than 5% by weight, the cleaning power may decrease depending on the type of resin to be cleaned. Moreover, if it exceeds 50% by weight, the cleaning agent tends to remain in the molding machine to some extent, and the amount of molding material used for discharging the cleaning agent after cleaning and the time required to do so increase somewhat.

The glass fiber used in the present invention contains a coupling agent in an increased amount of 200 to 300% by weight compared to glass fibers commercially available for plastics.
Preferably, the content is 0 to 3000 ppm. Moreover, the length and diameter are similar to those commercially available for plastics, and the average length is about 0.1 to 10 mm, and the average diameter is about 1 to 40 μm.

In the present invention, the above resin containing glass fiber is used as a cleaning agent.

The content of glass fiber in this cleaning agent is more than 30% by weight and less than 50% by weight. Glass fiber content is 30
If the amount is less than % by weight, the detergency is low (especially when the molding temperature is 280℃)
In the above-described high-temperature molding, the detergency is significantly reduced due to the reduction in melt viscosity of the resin part. Furthermore, it is technically difficult to contain more than 50% by weight.

In the present invention, containing glass fiber in the resin means
In a state that does not easily separate at room temperature.

Supporting glass fibers on a resin means, for example, uniformly kneading glass fibers into a resin and finishing it in the form of pellets that firmly support glass fibers.

Therefore, the present invention excludes, for example, a mere mixture of granular or powdered resin and glass fiber. In the case of a simple mixture, the glass fibers are separated from the resin, or the resin particles or powder are simply attached to the surface of the glass fibers.
When the molding machine is loaded, glass fibers adhere to the hopper of the molding machine and the inner wall directly under the hopper, and these glass fibers mix with the resin to be used next, causing molding defects.

On the other hand, if the glass fiber is firmly supported by the resin,
After being put into the molding machine, it is reliably sent deep into the molding machine together with the resin and is cleaned, so that it does not remain in the hopper of the molding machine or directly under the hopper.

As mentioned above, the inclusion of glass fiber is carried out, for example, by kneading the glass fiber into the resin, but to knead the glass fiber into the resin, for example, by mixing the glass fiber with a mixed medium such as blended oil, and adding it to the resin. The glass fiber may be mixed with the resin and then introduced from the hopper of the extruder, or the glass fiber alone may be injected into the extruder from the vent hole of the extruder and kneaded with the resin.

This cleaning agent exerts its cleaning effect by putting it into a molding machine and operating the molding machine normally. In this case, if the present cleaning agent has a relatively large glass fiber content, other resins may be mixed therein as long as the glass fiber content does not become less than 30% by weight.

As other resins used in combination with the present cleaning agent, general resins used in injection molding, extrusion molding, etc. can be widely used, but like the resin used in the present cleaning agent,
Melt flow rate is 0.5-30g/10min (220
℃・10kg) is preferable. Further, it is preferable that the resin has the same composition as the resin used in the present cleaning agent or the resin used next, and moreover, two or more types of resins can be used at the same time.

This cleaning agent is usually used to facilitate feeding into the molding machine.
It is formed into granules similar to general molding materials.
The above-mentioned main cleaning agent and other resin can be mixed by appropriately mixing the other resin to be mixed with the other resin in a similar granular form.

It is preferable to use this detergent with the addition of an alkali metal salt, particularly a metal stearate such as magnesium stearate, as a lubricant. Addition of this alkali metal salt makes it more difficult for the cleaning agent to remain, and even if it remains, it becomes easier to remove. It is preferable that the alkali metal salt is added so that the alkali metal salt content of the cleaning agent is 0.1 to 5% by weight.

The above alkali metal salts may be added and mixed in advance to the resin constituting this cleaning agent or other resins mixed with this cleaning agent, or may be added separately when using this cleaning agent. It is preferable to knead it together with glass fiber into the constituent resin because the effect of its addition is large.

The method of kneading the alkali metal salt into the resin constituting the cleaning agent is as follows: 1. For example, after mixing glass fiber with a mixed medium such as blended oil, the alkali metal salt is mixed therein, and then the resin is introduced into the vent of an extruder. This can be done by injecting a predetermined amount of this mixture into an extruder and kneading it with the resin.

It is preferable to use this cleaning agent with the addition of a foaming agent because the cleaning effect will be improved. The blowing agent may be an inorganic blowing agent such as sodium bicarbonate or ammonium carbonate, or an organic blowing agent such as azodicarponamide or azobisisobutyronitrile. The foaming agent is preferably added so that the foaming agent content of the cleaning agent is 0.1 to 2% by weight. Moreover, it is preferable to add it together with the alkali metal salt.

The foaming agent may be added and mixed in advance to the resin that makes up this cleaning agent or other resin that is mixed with this cleaning agent, or it may be added separately when using this cleaning agent, but It is preferable to knead it into the resin together with glass fiber because the effect of its addition is large. However, if the melt flow rate of the resin that makes up this cleaning agent is small, it will foam during mixing, making it difficult to mix it in. In such cases, this cleaning agent should be mixed with other resins. It is preferable to select a resin with a relatively large melt flow rate as the other resin and knead a blowing agent into it. Of course, at this time, an alkali metal salt may also be mixed in together with the blowing agent.

Further, it is preferable that the cleaning agent contains water. This moisture turns into steam inside the molding machine and effectively works to peel off the residue.

When adding moisture, for example, the resin that makes up this cleaning agent can be adsorbed using its hygroscopic properties, or the resin that makes up this cleaning agent can be made porous to confine water inside, so that when the cleaning agent is added, the water can be absorbed. It is necessary to prevent it from leaving outside. For example, if the cleaning agent is simply sprinkled with water and adhered to it, the water released from the molding machine may adhere to or collect in the hopper of the molding machine or directly under the hopper when it is loaded, and may wet the molding material that will be loaded next. , which will have a negative effect on the subsequent molding.

When using this cleaning agent in combination with another resin, moisture can be contained in the other resin. In some cases, the water content is 0.2
It is preferably 5% by weight. Moisture content during use is 0
．． If it is less than 2% by weight, it is difficult to obtain a sufficient effect of moisture content, and if it exceeds 5% by weight, the cleaning operation becomes mechanically difficult.

This cleaning agent has a cleaning effect by putting it into a molding machine and allowing the machine to operate almost normally, and is particularly useful for injection molding machines and extrusion molding machines, but it is similar to these. Any device having a part of a cylinder that heats and melts resin and kneads it can be widely applied.

When using this cleaning agent on a molding machine with a vent,
Favorable results are obtained when ~lO wt % is added via ventro.

When using this cleaning agent, it is preferable to set the operating conditions of the molding machine to such a condition that the internal pressure of the cylinder increases, since the effect will be more pronounced. That is, it is preferable to perform operations such as lowering the cylinder temperature within a range that allows for discharge, applying back pressure, and injecting at high speed. - [Function] As the resin and glass fibers themselves move within the molding machine, they play the role of peeling off the residue inside the molding machine from the attachment position and carrying it out.

Incidentally, in cleaning after high-temperature molding at a molding temperature of 280° C. or higher, it is necessary to perform the cleaning at a temperature similar to the molding temperature. In this case, since the viscosity of the resin constituting the cleaning agent decreases, it is thought that the residue removal effect of this resin decreases. Therefore, as before,
1 to 100 parts by weight of resin with the same composition as the resin to be used next
In the case where 20 parts by weight of glass fiber is added, the decrease in the residue removal effect due to the decrease in the viscosity of the resin directly manifests as a decrease in the cleaning power, resulting in a significant decrease in the cleaning effect.

In the present invention, the melt flow rate is 0.5 to 30 g/
The reason why the resin is used for 10 minutes (220° C., 10 kg) is to prevent the peeling effect of the residue from significantly decreasing even during high temperature molding. In addition, glass fibers containing more than 30% by weight and less than 50% by weight are
Even if the viscosity of the resin decreases to some extent, the large amount of glass fiber contained maintains a high level of residue removal effect.

On the other hand, when a large amount of glass fiber is contained as in the present invention, there is a concern that the glass fiber may remain in the molding machine. However, as confirmed by the present inventor, almost no adverse effects are observed due to the residual glass fibers. The reason is,
If a resin with a melt flow rate within the above range is used as a base, glass fibers will not remain as much as previously thought, and even if the residual amount increases to a certain extent, it will not have strong adhesion under high temperature molding conditions. It is conceivable that it will be easily discharged during the next replacement operation with the molding material.

Particularly when used with the addition of alkali metal salts or blowing agents, these not only have a beneficial effect on the removal of residues (
It also has a beneficial effect on preventing glass fibers from remaining.

[Example] Next, the present invention will be explained with reference to Examples and Comparative Examples.

The molding machines, molding conditions, and measurement conditions used in Examples and Comparative Examples are as follows.

Molding machine: Injection molding machine (in-line screw type), Toshiba l5125 (mold clamping force: 125 tons, capacity: 10 ounces) Molding temperature: Shown in Table 1 for each example and comparative example.

Melt flow rate: Measured according to JIS-7210.

Acrylonitrile content (AN%) was measured using an infrared spectrophotometer.

Example 1 A black colored molding material of polyphenylene oxide (PPO) was filled into a molding machine and then completely discharged to empty the inside of the molding machine.

Next, the melt flow rate is 2 g/10 min (22
Glass M fibers (average diameter 20 μ, length 3 mm, coupling agent 2
1.5 kg of the cleaning agent of the present invention containing 40 wt. In addition, after the cleaning agent is discharged, the injection operation is performed using PPO colorless molding material for general molding, and the time it takes to confirm that there is no effect of residue (defects in appearance due to black stains and residual glass fibers). and the amount of colorless molding material used was measured.

The results are shown in Table 1.

Comparative Example 1 Immediately after discharging the PPO black colored molding material, the injection operation was carried out using a PPO colorless molding material for general molding as a cleaning agent until it was confirmed that there was no influence of the residue (black stains). The measurement was carried out in the same manner as in Example 1 except that the measurement was carried out in the same manner as in Example 1.

The results are shown in Table 1.

Example 2 The same procedure as Example 1 was carried out, except that the object to be cleaned was a black colored molding material of polycarbonate ('PC), and after the injection operation of the cleaning agent of the present invention, the injection operation was performed with a colorless molding material of PC for general molding. Measurements were carried out in the same manner.

Comparative Example 2 The base resin of the cleaning agent has a melt flow rate of 35g/1
0 minutes (220° C.-10 kg) (7) Measurement was performed in the same manner as in Example 2 except that AS resin was used.

The results are shown in Table 1.

Example 3 Magnesium stearate was used as an alkali metal salt at 0.0%.
Measurements were carried out in the same manner as in Example 2, except that the base of the cleaning agent was a mixture of 3% by weight and 0.3% by weight of azodicarposamide as an organic blowing agent.

The results are shown in Table 1.

Comparative Example 3 Example 2 except that the glass fiber content was 20% by weight
Measurements were carried out in the same manner.

The results are shown in Table 1.

(The following is a blank space) [Effects of the Invention] The present invention is as explained above, and in particular, even under high temperature molding conditions, a high cleaning effect can be obtained with a short time cleaning using a small amount of cleaning agent, and a high cleaning effect can be obtained after that. Since it is possible to reduce the consumption of the next molding material in the replacement operation and shorten the operation time, it is possible to significantly reduce the cost and work load for cleaning during high temperature molding.

Claims (1)

[Claims] (1) Melt flow rate is 0.5-30g/10min (
A cleaning agent for a molding machine, characterized in that a thermoplastic resin (220° C./10 kg) contains glass fiber in an amount of more than 30% by weight and less than 50% by weight.