WO2013139282A1

WO2013139282A1 - Method for attaching an in-mold label

Info

Publication number: WO2013139282A1
Application number: PCT/CN2013/072971
Authority: WO
Inventors: 张伟; 侯志强; 刘珏
Original assignee: 华为终端有限公司
Priority date: 2012-03-21
Filing date: 2013-03-21
Publication date: 2013-09-26
Also published as: CN102615771A; CN102615771B

Abstract

The invention relates to the field of in-mold decoration. Provided is a method for attaching an in-mold label (IML), used for solving problems in methods for IML attachment of poor finished product smoothness after injection molding and attachment, and high product defect rates, and comprising: forming an ultraviolet (UV) radiation-hardened layer on a film substrate; printing said UV layer with ink, forming an ink layer; shaping said film substrate having said ink layer and forming same into a film; placing said film into the front mold of a mold and clamping the front mold to the rear mold; injecting plastic into said mold, so as to attach said film to said plastic and shape same; the plastic and the film substrate are of identical material.

Description

The invention relates to a Chinese patent application filed on March 21, 2012 by the Chinese Patent Office, the application number is 201210076393.5, and the invention name is "an in-mold insert injection molding method" Priority is hereby incorporated by reference in its entirety. Technical field

The invention relates to the field of in-mold decoration, in particular to an in-mold insert injection molding method. Background technique

The IML (In Molding Label) process covers printing, high pressure forming, punching, and injection molding, and is used in communication products such as decorative processing of molded mobile phone case covers.

The traditional IML process forms a die by cutting the substrate substrate, printing the flat surface, printing the ink, fixing the ink, positioning the hole, thermoforming, applying a protective film, cutting the peripheral shape, and then attaching the die to the injection molding material. Synthetic type, to achieve the decoration of the phone case. In the existing process, PET (Polyethylene Terephthalate, polyethylene terephthalate) is widely used as a die substrate because of its high hardness, and the injection molding material is used for polymethyl Methacrylate. Ethyl decyl acrylate). However, due to the different parameters such as shrinkage, fluidity and melt index of the two materials, the flatness of the finished product after the bonding of the die and the injection molding material is poor, and the flatness reflects the deviation of the concave and convex height of the product after macroscopic molding from the ideal plane. Therefore, the product produced by the existing process has a high defect rate. Summary of the invention

The embodiment of the present invention provides an IML bonding method, which solves the problem of flatness of the finished product and the defect rate of the product after the injection molding in the IML bonding method by using the same injection molding material as that of the die substrate. High problem.

In order to achieve the above object, embodiments of the present invention use the following technical solutions:

The invention provides an in-mold insert injection molding IML bonding method, comprising:

Forming a radiation cured UV layer on the die substrate;

Printing ink on the UV layer to form an ink layer; Forming the die substrate on which the ink layer is formed to form a die;

Putting the mold into a front mold of the mold, and performing mold clamping of the front mold and the rear mold of the mold; injecting a plastic material into the mold, so that the mold sheet is adhered to the plastic material Forming, the material of the plastic material is the same as the material of the die substrate.

The embodiment of the invention provides an in-mold insert injection molding method, which uses the same injection molding material as the material of the die substrate, so that the die and the injection molding material are closely attached, which is not easy to fall off, and the IML sticker is solved. In the method, the problem of flatness difference and high defect rate of the finished product after injection molding is improved, and the yield of the product is improved. 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 embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any creative work.

FIG. 1 is a flowchart of a method according to an embodiment of the present invention. detailed description

BRIEF DESCRIPTION OF THE DRAWINGS The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without the creative work are all within the scope of the present invention. Embodiments of the present invention provide a method of an in-mold insert injection molding method. As described in FIG. 1, the method includes the following steps:

S101, forming a radiation-cured UV (ultraviolet, ultraviolet radiation) layer on the die substrate. The UV layer is a chemical layer formed by the chemical reaction of the chemical substance of the polymer material after being irradiated by the ultraviolet light source, and the chemical layer makes the die substrate have a certain hardness and wear resistance. The specific process of the UV layer is: spraying a chemical substance containing a photoinitiator and a polymer material on the die substrate, the chemical substance of the polymer material is stimulated by the ultraviolet light source, and the liquid chemical substance light The initiator is stimulated to become a free radical or cation, which is triggered in a short period of time (less than 1 second) The polymer material (resin) is polymerized into a solid coating film to form a UV layer, so this process is also called UV hardening.

5102. Printing ink on the UV layer to form an ink layer. In the embodiment of the present invention, the formation of the ink layer mainly includes the following steps:

First, a layer of metallic ink is printed on the UV layer by silk screen to form a metallic ink layer; then, a layer of white ink is printed on the metallic ink layer by silk screen to form a white ink layer.

Among them, metal ink is also called mirror ink, which is composed of high-brightness paste and connecting material. The main component of the highlight paste is aluminum (AL) particles, which are joined by a joining material to increase the surface tension of the metallic ink. It should be noted that, in the embodiment of the present invention, the metal ink is taken as an example for explanation, but it is not limited thereto in practical applications, and may also be an ink containing an organic component, and the ink of the organic component is mainly composed of a transparent oil. Add color paste and solvent composition.

5103. Forming the die substrate on which the ink layer is formed to form a die. In the embodiment of the present invention, the die piece is an insert, which is placed in the front mold of the mold during the injection molding, and the mold piece is bonded to the plastic material through an injection molding process. The mold is divided into a front mold and a rear mold by a parting surface, and the front mold is not movable. Therefore, it is also called a fixed mold, and the rear mold is movable, and therefore, is also called a movable mold.

Illustratively, during the molding process of the TP (Touch Panel) screen of the mobile phone and the casing of the mobile phone, the TP screen is a die, which is placed in the front mold of the mold, and the TP screen and the plastic material are processed through an injection molding process. Fitted, eventually forming a mobile phone case with a TP screen. Specifically, the molding method for molding the die substrate on which the ink layer is formed includes: high pressure molding, or thermoforming, or hydroforming.

Since in the IML bonding method, the required die is not necessarily planar, it may also be a three-dimensional structure having a certain curve and curvature. Therefore, the die after the UV hardening process and the printing ink layer is also required. The substrate is subjected to a molding process.

Wherein, high pressure molding refers to molding or laminating a die substrate by using a pressure of more than 14 kg/cm 2 and a pressure of about 1.4 x 106 Pa, so that the die substrate is under pressure and has a shape The bend is deformed to produce the desired curve or curvature to produce a die. Thermoforming refers to heating a die substrate to soften the die substrate under the condition that the heating temperature does not exceed the melting point of the die substrate, and then the shape of the die substrate is bent under the action of mechanical force. Deformation, by precisely controlling the temperature and curvature during the forming process, to produce the desired curve or curvature, thereby producing a die. Hydroforming refers to the use of a liquid as a force transmitting medium or a mold to bend a shape of a die substrate to produce a desired curve or curvature, thereby producing a die.

S104, placing the die into a front mold of the mold, and performing mold clamping of the front mold and the rear mold of the mold.

The mold includes a front mold and a rear mold. In the front mold of the mold, a groove conforming to the shape of the die is provided for placing the die. Since the front mold of the mold is fixed, the rear mold is movable. When the mold is placed in the groove, the rear mold and the front mold pair of the mold are combined and fixed to complete the mold clamping.

S105, injecting a plastic material into the mold, so that the mold sheet and the plastic material are pasted into a composite material, and the material of the plastic material is the same as the material of the mold substrate. In an embodiment of the invention, the die substrate is PMMA, or PC (Polycarbonate, polycarbonate), or ABS (Acrylonitrile Butadiene Styrene plastic, acrylonitrile-styrene-butadiene copolymer). Before injecting the same plastic material as the material of the die substrate into the mold, the parameters in the injection molding process are set according to the property parameters of the different injection molding materials. The following is an example in which the die substrate is PMMA. After injecting the same plastic material as the material of the die substrate into the mold, before performing the injection molding process, the method further comprises: setting the front mold temperature of the mold to 35 ° C -55 ° C, and setting the mold temperature of the mold Set to 90 °C -95 °C. Since the die is placed in the front mold of the mold, the front mold temperature is set to 35 °C - 55 °C: in order to deform the mold without being affected by high temperature during the injection molding process. In order to ensure that the plastic material is quickly injected into the mold in a molten state and bonded to the mold, the mold back mold temperature is set to 90 ° C - 95 ° C. In order to make the die and the injected plastic material fit well without damaging the die, the injection molding is performed. In the process, according to the temperature of the injected plastic material, different holding pressures are set, as shown in Table 1, Table 1 shows the relationship between plastic temperature and dwell time:

Table 1. Relationship between plastic temperature and holding time. The plastic temperature indicates the temperature of the plastic material contained in the barrel; the holding pressure refers to the pressure applied to the mold after the plastic material is injected, so that the mold and the plastic material It fits snugly and is not easy to fall off. Further, in the case of injection molding, it is also necessary to inject a plastic material which is the same as the material of the die substrate in the mold at a pressure of 129 Pa (pa), and the injection pressure refers to the pressure at which the injection molding apparatus emits the plastic material.

In addition, the holding time of the injection molding type is 5 seconds, and the holding time refers to the length of time during which the pressure is applied to the mold after the plastic material is injected.

Further, after the injection molding and the synthetic type, it is also required to cool the molded and molded plastic sheets in the air chamber for 15 seconds. The air chamber is a module that is installed in the injection molding machine for cooling the mold and the plastic material after the injection molding. It should be noted that, in the embodiment of the present invention, the die substrate may be polydecyl methacrylate (PMMA), or polycarbonate (PC), or acrylonitrile-styrene-butadiene copolymer (ABS). In the prior art, the die material is made of PET material. Although the PET material has the advantages of good hardness, etc., in the process of injection molding, the injection molded plastic material is usually made of PMMA material, due to two kinds of The difference in parameters such as shrinkage, fluidity and melt index of the material leads to poor flatness of the finished product after the die and the injection molding material are bonded. The flatness of the IHJ convex height of the product after macroscopic forming is deviated from the ideal plane. The product produced by the existing process has a high defect rate. In the embodiment of the present invention, the die substrate and the plastic material are the same material, and the formed die and the plastic material have the same shrinkage rate, fluidity and melt index, wherein the shrinkage rate refers to the plastic part at the molding temperature. The percentage of the difference between the size and the size after removal from the mold to room temperature, which reflects the degree of shrinkage of the plastic part after it is removed from the mold; the fluidity refers to the flowability of the plastic material in the molten state; The index is used to determine the melt mass flow rate or melt volume flow rate in the molten state. Therefore, the die can be brought into close contact with the injection molded plastic material, so that the flatness is reduced and the defective rate of the product is reduced. Exemplary If PMMA material is used as the die substrate and injection molding material at the same time, when the PMMA material is used as the die substrate, the hardness and wear resistance can be achieved after the UV hardening treatment. Further, Since the PMMA material has higher light transmittance and injection rate than the PET material, the PMMA material can be used for the die substrate to improve the permeability of the product after injection molding. The injection molding method of the in-mold insert provided by the embodiment of the invention adopts the same plastic material as the material of the die substrate, and adjusts the parameters of the injection molding process, so that the die piece and the injection molding material are closely attached. It is not easy to fall off, and solves the problem of poor flatness and high defect rate of the finished product after injection molding and bonding in the IML bonding method, and improves the yield of the product.

The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the appended claims.

Claims

Rights request

1. An in-mold insert injection molding IML bonding method, characterized in that it comprises:

Forming a radiation cured UV layer on the die substrate;

Printing ink on the UV layer to form an ink layer;

Forming the die substrate on which the ink layer is formed to form a die;

2. The method according to claim 1, wherein the die substrate is polydecyl methacrylate (PMMA), or polycarbonate (PC), or acrylonitrile-styrene-butadiene. Copolymer (ABS).

3. The method according to claim 1, wherein the printing the ink on the UV layer comprises:

A layer of metallic ink is printed on the UV layer by silk screen to form a metallic ink layer; a white ink is printed on the metallic ink layer by silk screen to form a white ink layer.

4. The method according to claim 1, wherein the molding method of molding the die substrate on which the ink layer is formed comprises: high pressure molding, or thermoforming, or hydroforming.

5. The method according to claim 1, wherein the die is placed in a front mold of the mold, and after the mold of the front mold and the rear mold of the mold is clamped, the mold is injected into the mold. Before plastics, it also includes:

The mold temperature of the mold was set to 35 ° C - 55 ° C, and the mold temperature of the mold was set to 90 ° C - 95 ° C.

The method according to claim 1, wherein injecting the plastic material into the mold comprises: injecting a plastic material of the same material as the mold substrate into the mold at a pressure of 129 Pa.

7. The method according to claim 1, wherein the mold sheet and the plastic material are bonded to each other for a holding time of 5 seconds.

8. The method according to claim 1, wherein the die and the plastic material are composited, and further comprising:

The bonded sheet and the injection molded plastic were cooled in a wind chamber for 15 seconds.