CN107553777B

CN107553777B - Method for separating double-color injection molding parts

Info

Publication number: CN107553777B
Application number: CN201710890700.6A
Authority: CN
Inventors: 万勇
Original assignee: Tonly Electronics Holdings Ltd
Current assignee: Tonly Electronics Holdings Ltd
Priority date: 2017-09-27
Filing date: 2017-09-27
Publication date: 2020-04-10
Anticipated expiration: 2037-09-27
Also published as: CN107553777A

Abstract

The invention discloses a method for separating a two-color injection molding part, which comprises the following steps: immersing a double-color injection molding piece into trichloromethane, and standing for 8-20 hours, wherein the double-color injection molding piece is made of PC and TPU; cleaning the two-color injection molding piece treated by the trichloromethane; separating the washed two-color injection molded part to obtain plastic blocks with different colors. According to the technical scheme provided by the invention, according to the physical characteristics of the PC and TPU double-color injection molding parts, the chloroform is used for carrying out surface treatment on the double-color injection molding parts, and gaps appear at the bonding positions of the treated PC and TPU, so that plastic blocks with different colors can be obtained through separation.

Description

Method for separating double-color injection molding parts

Technical Field

The invention relates to the technical field of injection molding, in particular to a method for separating a double-color injection molding piece.

Background

The double-color injection molding part is a plastic part obtained by injecting two kinds of plastics with different colors into the same mold for molding. The double-color injection molding piece can present regular patterns or irregular colors, has higher practicability and aesthetic property, and is widely applied. However, the materials with different colors used by the two-color injection molding part must be bonded and compatible, so that the two-color injection molding part is not easy to recycle.

Disclosure of Invention

The invention mainly aims to provide a separation method of a two-color injection molding part, and aims to solve the technical problem that the two-color injection molding part is not easy to recycle.

In order to achieve the purpose, the method for separating the two-color injection molding part comprises the following steps:

immersing a double-color injection molding piece into trichloromethane, and standing for 8-20 hours, wherein the double-color injection molding piece is made of PC and TPU;

cleaning the two-color injection molding piece treated by the trichloromethane;

separating the washed two-color injection molded part to obtain plastic blocks with different colors.

Preferably, the step of immersing the two-color injection molded part in chloroform and standing for 8-20 hours further comprises the following steps:

and cleaning the surface of the two-color injection molding piece.

Preferably, the step of cleaning the surface of the two-shot molded part comprises:

immersing the double-color injection molding piece into clear water and standing for 1-5 hours;

and cleaning sundries on the surface of the double-color injection molding piece.

Preferably, the two-color injection molded part is immersed in clear water and left to stand for 2 hours.

Preferably, the step of immersing the two-color injection molded part in chloroform and standing for 8-20 hours comprises:

drying the cleaned two-color injection molding piece;

and (3) immersing the dried two-color injection molding piece into chloroform, and standing for 8-20 hours.

and (3) immersing the double-color injection molding piece into a closed container containing trichloromethane, and standing for 8-20 hours.

Preferably, the two-color injection molded article is immersed in chloroform and left to stand for 10 hours.

Preferably, the step of cleaning the chloroform-treated two-color injection molded part comprises the following steps:

and (3) placing the double-color injection molding treated by the trichloromethane into clear water and standing for 1-5 hours.

Preferably, the time for placing the trichloromethane treated double-color injection molding into clear water for standing is 2 hours.

Preferably, the step of immersing the two-color injection molded part in chloroform and standing for 8-20 hours comprises the following steps:

and performing color development test on the two-color injection molding piece to determine that the two-color injection molding piece is made of PC and TPU.

According to the technical scheme provided by the invention, according to the physical characteristics of the PC and TPU double-color injection molding parts, the chloroform is used for carrying out surface treatment on the double-color injection molding parts, and gaps appear at the joint of the treated PC and TPU, so that plastic blocks with different colors can be obtained through separation.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic flow chart of a first embodiment of a two-shot injection molding separation method of the present invention;

FIG. 2 is a schematic flow chart of a second embodiment of the method for separating a two-color injection molded part according to the present invention;

FIG. 3 is a detailed flowchart of the cleaning process for the surface of the two-shot molding according to the third embodiment of the separation method of the two-shot molding of the present invention;

fig. 4 is a schematic flow chart of a method for separating a two-color injection molded part according to a fourth embodiment of the invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a first embodiment of a two-shot molding separation method according to the present invention, which includes:

and S100, immersing the two-color injection molding piece into trichloromethane, and standing for 8-20 hours, wherein the two-color injection molding piece is made of PC and TPU.

In particular, tpu (thermoplastic polyurethanes) is known under the name thermoplastic polyurethane elastomers. The wear-resistant polyester film is mainly divided into polyester type and polyether type, HAs wide hardness range (60HA-85HD), wear resistance, oil resistance, transparency and good elasticity, and is widely applied to the fields of daily necessities, sports goods, toys, decorative materials and the like.

PC (polycarbonate) is named as polycarbonate, is amorphous thermoplastic resin with excellent comprehensive performance, and has excellent electrical insulation, extensibility, dimensional stability, chemical corrosion resistance, higher strength, heat resistance and cold resistance; it also has the advantages of self-extinguishing, flame-retarding, non-toxic and colourable.

The TPU soft rubber and the PC hard rubber are combined together by a double-color injection molding method, can be used for producing products such as mobile phone shells, and the like, generally wraps the soft rubber on the surface to play a role in damping and improving hand feeling, and also wraps the soft rubber on the inner layer to play a damping role. It should be noted that the mating material for two-color injection molding must satisfy the following two basic compatibility conditions: the adhesion compatibility and the injection molding processing process are compatible, just because the TPU and the PC are adhesion compatible, the two-color injection molding piece manufactured by the TPU and the PC is not easy to recycle, thereby causing the waste of resources. It has been found that chloroform can break the adhesive force between the TPU and the PC, allowing a gap to form between the joint of the TPU and the PC, thereby allowing the TPU and the PC to be separated. It should be noted that chloroform can also separate two-color injection molding of other materials, and is not limited to TPU and PC.

In actual operation, the double-color injection molding piece is immersed in a closed container containing trichloromethane to reduce volatilization of the trichloromethane, and the trichloromethane is a toxic substance, so that the poisoning of operators can be avoided. In addition, trichloromethane reacts with oxygen in the air under irradiation, and is gradually decomposed to generate highly toxic phosgene (carbonyl chloride) and hydrogen chloride, so that a container containing the trichloromethane needs to be protected from light.

Preferably, the two-color injection molded article is immersed in chloroform and left to stand for 10 hours. The standing time of the two-color injection molded parts in chloroform needs to be moderate. Since the trichloromethane is a strong solvent, the polycarbonate can be dissolved into viscous liquid, the standing time is not suitable to be too long, and a gap is formed between the polycarbonate and the thermoplastic polyurethane elastomer on the basis of insolubilization of the polycarbonate. It will be appreciated that the time of rest should not be too short, otherwise there will not be sufficient space between the polycarbonate and the thermoplastic polyurethane elastomer, resulting in incomplete separation of the differently colored plastic pieces.

Preferably, the two-color injection molding is immersed in chloroform and stands still, and the chloroform is heated to 40-60 ℃, so that the separation between TPU and PC can be accelerated, and the separation time can be shortened.

It should be noted that the step of immersing the two-color injection molded part in chloroform and standing for 8-20 hours includes:

Specifically, a few milligrams of a sample is dissolved or suspended in 2ml of hot acetic anhydride, 3 drops of 50% sulfuric acid are added after cooling, the color reaction is observed, and if lemon yellow is always displayed and the color changes from brown to green fluorescence when the temperature is increased to 100 ℃, the plastic corresponding to the sample is TPU. Heating 0.1-0.2g sample in a test tube, placing the thermal decomposition product on a small cotton plug, dripping methanol solution of p-xylylbenzene with concentration of 14% on the cotton, and dripping a drop of concentrated hydrochloric acid (PC) to show dark blue.

Of course, the material of the two-shot molded part can also be detected in other ways. Such as chemical component analysis, combustion test identification, density identification, pyrolysis test identification, solvent treatment identification, heating identification, and the like, wherein the chemical component analysis includes nuclear magnetic resonance, GC-MS (gas chromatography and mass spectrometry), infrared spectroscopy, Raman spectroscopy, ultraviolet absorption spectroscopy, and the like. According to the actual situation, a proper method is selected for detecting the material of the double-color injection molding part.

Step S200, cleaning the two-color injection molding piece after the chloroform treatment;

and S300, separating the cleaned double-color injection molding piece to obtain plastic blocks with different colors.

Specifically, after the two-color injection molding is taken out of the chloroform, the two-color injection molding needs to be cleaned to remove the residual chloroform on the two-color injection molding, and after the two-color injection molding is cleaned, the TPU and the PC can be obtained through simple physical separation.

Further, referring to fig. 2, in a second embodiment of the method for separating a two-shot injection molded part according to the present invention, on the basis of the first embodiment, step S100 includes immersing the two-shot injection molded part in chloroform, and the method further includes, before standing for 8 to 20 hours:

and step S400, cleaning the surface of the two-color injection molding piece.

In the embodiment, the surface of the double-color injection molding piece is cleaned, so that on one hand, pollutants can be prevented from being brought into trichloromethane, and the cyclic utilization of the trichloromethane is influenced; on the other hand, the influence of the chloroform on the effect of the joint of the TPU and the PC caused by the surface impurities of the double-color injection molding part can be avoided, so that the separation of the TPU and the PC is influenced. In addition, it should be noted that there may be some loss of surface physical properties of the TPUs and PCs treated with chloroform, and therefore, it is not desirable to perform intensive cleaning work on the separated TPUs and PCs. In combination with the above, cleaning of the two-shot parts is preferably accomplished prior to the immersion in chloroform.

drying the cleaned two-color injection molding piece;

The cleaned double-color injection molding piece is generally attached with water, and the double-color injection molding piece is dried and then is immersed in trichloromethane, so that the trichloromethane can be conveniently recycled. Moreover, when water is attached to the double-color injection molding part, the water slowly floats to the surface of the trichloromethane due to the fact that the density of the water is small compared with that of the trichloromethane, the process can affect the effect of the trichloromethane on the joint of the TPU and the PC, and therefore the separation effect of the TPU and the PC is affected.

Further, referring to fig. 3, in a third embodiment of the method for separating a two-shot injection molded part according to the present invention, in the second embodiment, the step S400 of cleaning the surface of the two-shot injection molded part includes:

step S401, immersing the double-color injection molding piece into clear water and standing for 1-5 hours;

and S402, cleaning sundries on the surface of the double-color injection molding piece.

In this embodiment, immerse the double-colored injection molding in clear water earlier and stew for a period of time, be favorable to weakening the adhesive force between the debris on double-colored working of plastics surface and the double-colored working of plastics, be convenient for follow-up get rid of the debris on double-colored working of plastics surface. Preferably, the two-color injection molded part is immersed in clear water and left to stand for 2 hours. Generally, the longer the two-color injection molding is immersed in clean water, the easier the impurities on the surface can be cleaned, but if the two-color injection molding is immersed in clean water for a long time, the longer the whole recovery time is, and the recovery efficiency is affected.

Further, referring to fig. 4, a fourth embodiment of the method for separating a two-color injection molded article according to the present invention is a method for cleaning a two-color injection molded article after chloroform treatment in step S200, which is based on any one of the first to third embodiments, comprising:

and S201, placing the double-color injection molding piece treated by the trichloromethane into clear water and standing for 1-5 hours.

In this embodiment, after the two-color injection molding is taken out of chloroform, the two-color injection molding is placed in clear water and kept stand for a period of time, so that residual chloroform on the two-color injection molding can be removed, and the physical properties of the surfaces of TPU and PC can be stabilized. Preferably, the time for placing the trichloromethane treated double-color injection molding into clear water for standing is 2 hours. The proper standing time does not affect the recovery efficiency, and can completely remove the trichloromethane.

In the technical scheme provided by the invention, trichloromethane is adopted to treat the two-color injection molding piece made of TPU and PC materials, so that TPU and PC are completely separated. The TPU and the PC are separated by a chemical separation method, so that the cost is low, and the problem that a double-color injection molding piece cannot be recycled is solved.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A method for separating a two-color injection molding part is characterized by comprising the following steps:

cleaning the two-color injection molding piece treated by the trichloromethane;

2. The method for separating a two-color injection molded part according to claim 1, wherein the step of immersing the two-color injection molded part in chloroform for 8 to 20 hours further comprises:

and cleaning the surface of the two-color injection molding piece.

3. The method of separating a two-shot molding according to claim 2, wherein the step of cleaning the surface of the two-shot molding comprises:

4. The method of separating a two-color injection molded part according to claim 3, wherein the time for immersing the two-color injection molded part in clear water to stand is 2 hours.

5. The method for separating a two-color injection molded part according to claim 2, wherein the step of immersing the two-color injection molded part in chloroform for 8 to 20 hours comprises:

drying the cleaned two-color injection molding piece;

6. The method for separating a two-shot molding according to any one of claims 1 to 5, wherein the step of immersing the two-shot molding in chloroform for 8 to 20 hours comprises:

7. The method for separating a two-color injection molded article according to any one of claims 1 to 5, wherein the time for which the two-color injection molded article is immersed in chloroform is 10 hours.

8. The method for separating a two-color injection molded part according to any one of claims 1 to 5, wherein the step of washing the two-color injection molded part after the chloroform treatment comprises:

9. The method for separating a two-color injection molded article according to claim 8, wherein the time for which the two-color injection molded article is left standing in clear water after the chloroform treatment is 2 hours.

10. The method of separating a two-shot molding according to any of claims 1 to 5, wherein the step of immersing the two-shot molding in chloroform for 8 to 20 hours comprises, before the step of: