JPH08336837A - Resin molding using recyclable material and manufacture thereof - Google Patents

Abstract

PURPOSE: To improve the utilization rate of a recyclable material while moldability and physical properties of a molding is kept at the same level as those of conventional one by forming a part which does not give bad influence on the physical properties as a product with a material contg. a larger content of the recyclable material than the other parts. CONSTITUTION: The first mixed material consisting of a recycled material and a new material mixed in a mixer 3 is injected into a mold 6 in a molten state from an injection molding machine 4 and is put into a cavity 60 and a runner gate 61. Then, before the molten resin in the mold 6 is solidified by cooling, the recyclable material and the new material are fed into a mixer 3 from hoppers 1 and 2 and in this time, the mixing ratio is in such a way that the recyclable material is more than before. Then, this second mixed material is injected furthermore into the mold 6 in a molten state and dwelling process is then performed. In the mold 6, the first mixed material in the runner gate 61 is pushed into the cavity 60 in which the pressure is decreased caused by shrinkage by cooling and the second mixed material is fed in the runner gate 61 instead of it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product using a recycled material such as an automobile bumper and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, resin molded products have been recycled for the purpose of effectively utilizing earth's resources. Not only thermoplastic resins such as Styrofoam trays and PET bottles, but also thermosetting resins such as polyurethane foam are recycled.

For example, as bumpers for automobiles, those made of a thermoplastic resin and those made of a thermosetting resin are known, and they are respectively recycled. A material made of a thermoplastic resin is used as it is as a recycle material after removing impurities, and a urethane bumper made of a thermosetting resin is decomposed into a polyol by chemical decomposition (decomposition of ethylene glycol) to be a recycled material.

However, in the case of a thermoplastic resin bumper, if the recycling is repeated a plurality of times, the molecular weight of the recycled material gradually decreases and the tensile elongation characteristic deteriorates. Further, in the case of a urethane bumper made of a thermosetting resin, it is difficult to completely decompose the original polyol by chemical decomposition, and the recycled material has a higher molecular weight than the original polyol. Therefore, the viscosity is higher than the original polyol,
There is a problem that moldability (fluidity) is reduced.

Since the recycled material has such a problem, there is a method in which the recycled material is not used as a molding material as it is but mixed with a new resin raw material and used. For example, in the case of a polypropylene (PP) bumper which is a thermoplastic resin, as shown in FIG. 5, the recycled PP in the hopper 100 and the new PP material in the hopper 101 are mixed in a predetermined ratio by the mixer 102. Mix. The mixed materials are supplied to the injection molding machine 104 via the hopper 103, and the bumper body 105 and the runner / gate portion 106 are molded. The runner / gate portion 106 is cut off after the molded body is solidified, and only the bumper body 105 is made into a product.

Further, in the case of a urethane bumper which is a thermosetting resin, as shown in FIG. 6, a recycled liquid (polyol) contained in the container 200 and a new liquid (new polyol) contained in the container 201 are used. The mixture is mixed in a predetermined ratio by the mixer 202, sent to the blend tank 203, collided and mixed with the isocyanate 205 supplied from the container 205 by the injection head 204, and injected into the mold, and the bumper body 206 and the runner / gate section. 207 is formed. The runner / gate portion 207 is cut off after the molded body is solidified, and only the bumper body 206 is made into a product.

[0007]

As described above, in the case where the recycled material is not used as a molding material as it is, but the recycled material is mixed with a new resin raw material, the recycled material is mixed in consideration of moldability and physical properties of the molded product. The amount was naturally decided, and the utilization rate of recycled materials was limited. The present invention has been made in view of such circumstances, and an object thereof is to maintain the moldability and the physical properties of a molded product at the same level as the conventional one, and to improve the utilization rate (addition amount) of the recycled material.

[0008]

A resin molded article using the recycled material of the present invention which solves the above-mentioned problems has a portion of the molded article which does not adversely affect the physical properties of the product as compared with other portions. It is characterized by being formed from many materials. Further, a method for producing a resin molded article using the recycled material of the present invention most suitable for producing this resin molded article is
In a resin molding method in which a resin is injected into a cavity through a runner and a gate of a molding die, after a predetermined amount of product resin is injected into the cavity, at least the runner and the gate include a recycled material as compared to the product resin. It is characterized by injecting a large amount of external resin for the product.

[0009]

The resin molded product using the recycled material of the present invention is characterized in that the part of the molded product that does not adversely affect the physical properties of the product is formed of a material having a large amount of recycled material compared to other parts. The physical properties of a product include mechanical properties such as tensile strength, compression strength, bending strength, wear resistance, and hardness, and surface design characteristics such as smoothness, paintability, and gloss, which are essential for the product. It refers to physical properties.

The part of the molded product which does not adversely affect the physical properties of the product is, for example, a rib which is formed inside the solid molded product and which is not exposed in the hollow molded product.
Alternatively, it refers to a part molded by a runner or a gate that is cut off after molding. Even if the physical properties such as strength and design of such a part are inferior to those of other parts, the physical properties of the product are not affected. Therefore, if such a part is made of a material that contains more recycled material than other parts,
The moldability and physical properties of the product part can be maintained at the same level as before, and the utilization rate of recycled materials can be improved as compared to the past.

Further, in the method for manufacturing a resin molded product using the recycled material of the present invention, a predetermined amount of product resin is injected into the cavity through the runner and the gate. After injecting the product resin, at least the runner of the runner and the gate is infused with the resin for external use of the product having a higher content of recycled material than the resin for product. For example, in injection molding, a high pressure is applied from a molding machine in a state where the cavity, gate and runner are filled with resin to press the resin filled in the runner, gate and cavity to prevent shrinkage of the molded product. The process is carried out, but at this time, a resin for external use of the product containing a large amount of recycled material is used. Then, the product resin filled in the runner and gate is pushed into the cavity,
At least the runner can be filled with the external resin for the product.

After the resin molded product is solidified, it is released from the mold and the unnecessary parts formed by the runner and the gate are cut off to obtain a product formed only from the product resin. In the past, since the unnecessary parts formed by the runner and the gate were also formed from the resin for products, the utilization rate of the recycled material was low, but the present invention improves the utilization rate of the recycled material. Further, since the product is formed only from the resin for the product, it has the necessary physical properties as in the past.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples. (Embodiment 1) FIG. 1 shows a manufacturing process drawing of the PP bumper of this embodiment. The hopper 1 is filled with recycled material from which impurities such as paint films and pigments have been removed from the waste PP bumper, and the hopper 2 is filled with new material made of new PP.

First, the valve 10 is controlled by a controller (not shown).
The valve 20 is opened for a predetermined time, and the recycled material and the new material are supplied from the hopper 1 and the hopper 2 to the mixer 3 in a predetermined amount. At this time, the recycled material and the new material are configured so that the molded bumper contains the recycled material within a range that does not impair the physical properties of the bumper. At this time, it goes without saying that the valve 1 may be closed and only the new material may be supplied.

The first mixed material of the recycled material and the new material mixed in the mixer 3 is supplied to the injection molding machine 4 and injected into the mold 6 in a molten state. In the mold 6, the molten resin fills the cavity 60 and the runner gate 61. Next, before the molten resin in the mold 6 is cooled and solidified, a valve (10) and a valve (20) are opened for a predetermined time by a controller (not shown), and a predetermined amount of recycled material and new material from the hopper 1 and the hopper 2 are mixed by a predetermined amount. Is supplied to. At this time, the ratio of the recycled material to the new material is such that the recycled material is more than in the previous molding.

The second mixed material of the recycled material and the new material mixed in the mixer 3 is supplied to the injection molding machine 4, and is further injected into the mold 6 in a molten state to carry out the pressure holding step. Mold 6
In the inside, the first mixed material that had filled the runner gate 61 is pushed into the cavity 60 whose pressure is reduced due to contraction due to cooling, and the runner gate 61 is filled with the second mixed material instead. .

After the first mixed material and the second mixed material are cooled and solidified, the holding pressure is released and the resin molded product of this embodiment is released by opening the mold. After that, the portion formed by the runner gate 61 is cut off to obtain a PP bumper. The obtained PP bumper has predetermined physical properties because it is formed of the first mixed material, which contains less recycled material than 30% by weight. On the other hand, the part formed by the excised runner gate 61 has a second material of 30% by weight or more of recycled material.
Since it is made of mixed materials, it contains many recycled materials and the recycled materials are highly utilized. Further, since it is an unnecessary part for the bumper, it does not matter that the physical properties are low. Therefore, according to the manufacturing method of the present embodiment and the obtained molded product, it has the same physical properties as the conventional one and the utilization rate of the recycled material is improved. (Embodiment 2) FIG. 2 shows a manufacturing process diagram of the urethane bumper of this embodiment. The container 7 contains isocyanate, and the container 8 contains recycled liquid (polyol) obtained by chemically decomposing waste urethane bumpers to remove impurities.
Contains a new liquid consisting of new polyol.

First, the valve 80 is controlled by a controller (not shown).
Is closed and the valve 90 is opened, so that 100 parts by weight of new liquid is supplied from the container 9 to the mixing head 30. At the same time, 40 parts by weight of isocyanate is supplied from the container 7 to the mixing head 30. At this time, the recycle liquid can be mixed by opening the valve 80 within a range that does not impair the physical properties and moldability (fluidity) of the bumper as a product. By doing so, the utilization rate of the recycled liquid is further improved.

In the mixing head 30, the new liquid and the isocyanate collide with each other and are mixed, and then injected into the mold 6. The product resin injected into the mold 6 fills the cavity 60 and the runner gate 61. Next, the valve 80 is “opened” before the filled product resin reacts and solidifies, and the recycled liquid is supplied to the mixing head 30. As a result, in the mixing head 30, 7 parts by weight of the recycle liquid and 40 parts by weight of the isocyanate collide and are mixed with 93 parts by weight of the new liquid to form the resin for external use of the product, which is injected into the mold 6. If the viscosity is sufficient to inject only the recycled liquid, the valve 90 can be closed at this time to supply only the recycled liquid and the isocyanate. By doing so, the utilization rate of the recycled liquid is further improved.

As a result, the product resin filling the runner gate 61 is pushed into the cavity 60, and the runner gate 61 is filled with the product external resin. After the product resin and the product external resin are solidified by reaction, the resin molded product is released by opening the mold. Then runner gate 61
The portion formed by is cut off to obtain a urethane bumper.

The urethane bumper thus obtained has predetermined physical properties because it is formed only from the resin for products. On the other hand, since the part formed by the excised runner gate 61 is formed of the resin for external use of the product, it contains a large amount of recycled liquid and the utilization ratio of the recycled liquid is high. Further, since it is an unnecessary part for the bumper, it does not matter that the physical properties are low. Therefore, according to the manufacturing method of the present embodiment and the obtained urethane bumper, it has the same physical properties as the conventional one and the utilization rate of the recycled material is improved. (Embodiment 3) FIG. 4 shows a state where a urethane bumper according to a third embodiment of the present invention is molded in a mold. In this urethane bumper, the inner layer 62 is made of a product external resin containing a recycled liquid, and the outer layer 63 is made of a product resin not containing a recycled liquid.

In order to manufacture this urethane bumper, first, a lower mold 64 and a first upper mold 65 as shown in FIG. 3 are used, and a resin for external use of the product containing the same recycle liquid as in Example 2 is injected to form the inner layer 62. To mold. After the inner layer 62 has reacted and solidified, the first upper mold 65 is exchanged with the second upper mold 66 as shown in FIG. The outer layer 63 is formed on the surface of the inner layer 62 by injecting a product resin that is not present.

In the obtained urethane bumper, since the inner layer 62 is made of the product external resin containing the recycle liquid, the utilization rate of the recycle material is extremely high. The resin for external use of the product has a high viscosity because it contains a recycled liquid, and there are cases in which there is a problem in the smoothness and the coatability of the surface of the formed inner layer 62. However, when installed in a vehicle,
Since the inner layer 62 is not exposed to the outside and is not normally coated on the inner layer 62, its physical properties such as smoothness and paintability do not affect the physical properties of the urethane bumper. Since the outer layer 63, which is the designed surface, contains no recycled material, the same smooth surface as the conventional one can be obtained and the coatability is excellent, and the same physical properties as the urethane bumper formed only from the new liquid can be obtained. To be

[0024]

That is, according to the resin molded product using the recycled material of the present invention, the recycled material is contained in a portion that does not adversely affect the physical properties of the product as compared with other portions. The utilization rate of timber is improved.
Also, there is almost no deterioration in the physical properties of the product or moldability,
It can be maintained at the same level as conventional molded products.

Further, according to the method for producing a resin molded product using the recycled material of the present invention, the resin for external use of the product having a large content of the recycled material is injected into at least the runner of the gate and the runner. There is no adverse effect.
Even if the moldability is lowered, the volume of the runner is smaller than that of the cavity, so that the influence on the molding time can be small. In the past, the runner was also formed of the same resin as the cavity, so at least the recycled material contained in the resin for external use of the product of the runner increased the utilization rate of the recycled material.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of a PP bumper according to an embodiment of the present invention.

FIG. 2 is an explanatory drawing of the manufacturing process of the urethane bumper in the second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a mold showing a state where an inner layer of a urethane bumper is being molded in a third embodiment of the present invention.

FIG. 4 is a sectional view of a mold showing a state in which an outer layer of a urethane bumper is being molded in a third embodiment of the present invention.

FIG. 5 is an explanatory view of a manufacturing process of a conventional PP bumper.

FIG. 6 is an explanatory view of a manufacturing process of a conventional urethane bumper.

[Explanation of symbols]

1: Hopper (input of recycled material) 2: Hopper (input of new material) 3: Mixer 4: Injection molding machine 60: Cavity 61: Runner gate 62: Inner layer 63: Outer layer

Claims (2)

[Claims] 1. A resin molded product using a recycled material, characterized in that the molded product part that does not adversely affect the physical properties of the product is formed of a material that is more recycled than other parts. 2. A resin molding method for injecting a resin into a cavity through a runner and a gate of a molding die, wherein after injecting a predetermined amount of product resin into the cavity, the resin is injected into at least the runner of the runner and the gate. A method for producing a resin molded product using a recycled material, which comprises injecting a resin for external use of the product, which has a higher content of recycled material than the resin for the product.