MMA monomer mold outer surface decoration injection mold and injection molding method thereof

Abstract

The invention provides an MMA single mold outer surface decoration injection mold and an injection molding method thereof.The MMA single mold outer surface decoration injection mold comprises a mold structure and a feeding structure, a nozzle is arranged at the discharging end of the feeding structure, and the mold structure comprises a front mold assembly, a rear mold assembly, a constant-temperature assembly, a vacuum assembly and an adsorption assembly; an injection molding channel communicated with the nozzle is formed in the front mold assembly, and the front mold assembly covers the rear mold assembly to form a decorative molding cavity communicated with the injection molding channel; the vacuum assembly communicates with the decoration forming cavity, the heating end of the constant temperature assembly is connected to the front mold assembly and the rear mold assembly, and the adsorption assembly is installed on the rear mold assembly and adsorbs the injection molding base material. Monomer injection molding liquid with low viscosity is obtained through material mixing of the feeding structure and is subjected to self-polymerization in the vacuum decorative forming cavity, and therefore an ultrathin injection molding layer is formed on the surface of the curved surface injection molding base material. The adsorption assembly tightly sucks the side, away from the decoration forming cavity, of the injection molding base material, and deformation of the surface of the injection molding base material in the decoration forming cavity is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of surface decoration, and in particular to an MMA single-body mold outer surface decoration injection mold and an injection molding method thereof. Background Art

[0002] In the traditional material surface decoration process, the coating-based solution has the problem of large VOC emissions and is inconsistent with the requirements of existing environmental policies. In addition, traditional surface treatment can only achieve rich color expression, but cannot achieve different requirements such as three-dimensional structure color, bionic structure color and gradient color.

[0003] The process of outer surface decoration by injection molding adopts the coating-free technology IMD to decorate the outer surface of the mold with injection polyurethane PUR for reaction injection molding. However, polyurethane PUR is sensitive to temperature, and the component ratio requirements and pressure are extremely stringent. The product batch is unstable and has high requirements for the injection molding and mixing system. It is impossible to form an ultra-thin injection layer (0.1mm-0.3mm) on the surface of the curved injection molding substrate, and the consistency of the ultra-thin injection layer formed by the surface decoration of the injection molding substrate is poor.

[0004] For example, the reference document CN200480001910.6 discloses a method and device for manufacturing a structural component with a dense polyurethane (PUR) sealing layer, wherein the structural component is placed in a mold, wherein in a closed state, there is a cavity between the surface of the structural component to be coated and the inner wall of the mold facing the surface, wherein the dense PUR component polyol and isocyanate, with additives if necessary, are injected into the mold containing the structural component through a mixing head and a pouring channel. This solution manufactures a transparent PUR sealing layer by mixing the PUR component polyol and isocyanate to fill the cavity, but this solution is sensitive to temperature, has extremely stringent requirements on component ratio and pressure, and is cumbersome in multi-component mixing, and cannot form an ultra-thin injection molding layer on the surface of a curved injection molding substrate.

[0005] Another example is a polymethyl methacrylate product and its preparation method disclosed in the reference document CN201110036358.6. The polymethyl methacrylate product is prepared by mixing a base material or a combination of a base material and a filler with an auxiliary agent and then adding an initiator for polymerization reaction. The raw materials also include a polymer material soluble in MMA. In this solution, a polymer material is added to the base material or a combination of a base material and a filler, and then an initiator is added to the mixture. After mixing evenly, the mixture is allowed to stand, and a semi-cured product is obtained after the polymer material is fully swollen and dissolved. However, in this solution, the semi-cured product is cured and molded to obtain a product, and MMA monomer is not used for injection molding, so an ultra-thin injection molding layer cannot be formed on the surface of the curved injection molding substrate. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an MMA single mold outer surface decorative injection mold and an injection molding method thereof, which has simple injection molding mixing, can form an ultra-thin injection molding layer on the surface of a curved injection molding substrate, and has a good consistency of the injection molding layer.

[0007] The purpose of this disclosure is achieved through the following technical solutions:

[0008] An MMA single mold outer surface decoration injection mold comprises a mold structure and a feeding structure, wherein the feeding structure comprises a mixing kettle, a feeding pipe and a pump push assembly, wherein the feeding end of the feeding pipe is connected to the mixing kettle, the pump push assembly is installed on the feeding pipe, and the discharge end of the feeding pipe is provided with a nozzle.

[0009] The mold structure includes a front mold component, a rear mold component, a constant temperature component, a vacuum component and an adsorption component. The front mold component is provided with an injection channel, the nozzle is connected to the injection channel, the rear mold component is provided with a fixing groove for installing an injection molding substrate, the front mold component is provided with an accommodating cavity, the front mold component is covered on the rear mold component so that the injection molding substrate is fixed in the fixing groove, a decorative molding cavity is formed between the injection molding substrate and the cavity wall of the accommodating cavity, and the decorative molding cavity is connected to the injection channel;

[0010] The vacuum component is connected to the decorative molding cavity, and the vacuum component is used to extract the air from the decorative molding cavity. The heating end of the constant temperature component is respectively connected to the front mold component and the rear mold component. The adsorption component is installed in the rear mold component, and the adsorption component is used to adsorb the side of the injection molding substrate away from the decorative molding cavity.

[0011] In one embodiment, the thickness of the decorative molding cavity is 0.1 mm-0.3 mm.

[0012] In one of the embodiments, the feeding structure further includes a heating component, the heating component is installed in the mixing kettle, the heating end of the heating component is arranged in the mixing kettle, and the heating component is used to heat the material in the mixing kettle.

[0013] In one embodiment, the mold structure also includes a heat insulating member, the discharge end of the feed pipe is installed in the front mold assembly, the heat insulating member is sleeved on the discharge end of the feed pipe, and the heat insulating member is used to isolate the discharge end of the feed pipe from contact with the front mold assembly.

[0014] In one embodiment, the adsorption component includes an adsorption mounting platform, an adsorption pipe and an adsorption pump. The adsorption mounting platform is provided with interconnected adsorption holes and a negative pressure chamber. The adsorption hole is connected to the fixed groove, the negative pressure chamber is connected to the adsorption pipe, and the adsorption pipe is connected to the adsorption pump.

[0015] An injection molding method for MMA single mold outer surface decoration is prepared by using the mold for MMA single mold outer surface decoration injection molding described in any of the above embodiments. The injection molding method for MMA single mold outer surface decoration comprises the following steps:

[0016] Adding MMA monomer resin, peroxide and MMA high-functional resin into the mixing kettle for mixing to obtain monomer injection liquid;

[0017] The injection molding substrate is installed in the injection molding fixing groove, and the vacuum component evacuates the decoration molding cavity to form a negative pressure environment in the decoration molding cavity and the connected injection molding channel;

[0018] The front mold assembly and the rear mold assembly are heated to a constant temperature by the constant temperature assembly so that the constant temperature of the decoration molding cavity is 60° C.-100° C.;

[0019] The monomer injection liquid is injected into the injection channel at low pressure through the nozzle, the pressure of the low pressure injection is 0.1Mpa-0.5Mpa, and the monomer injection liquid enters the decoration molding cavity after passing through the injection channel;

[0020] The monomer injection molding liquid is continuously injected into the injection molding channel through the nozzle to maintain the pressure of the monomer injection molding liquid in the decoration molding cavity, and the monomer injection molding liquid in the decoration molding cavity is heated to produce a self-polymerization reaction, so that a decoration molding injection molding layer is formed on the surface of the injection molding substrate to obtain an ultra-thin decoration layer injection molded part;

[0021] The ultra-thin decorative layer injection-molded part is taken out.

[0022] In one embodiment, the viscosity of the monomer injection liquid is 200 Pa·s-500 Pa·s.

[0023] In one embodiment, the vacuum pressure of the negative pressure environment of the decoration molding cavity is -1.2Mpa to -0.8Mpa.

[0024] In one embodiment, the holding time is 40s-60s.

[0025] In one of the embodiments, the holding pressure of the monomer injection liquid in the decoration molding cavity is 0.1Mpa-0.5Mpa.

[0026] Compared with the prior art, the present invention has at least the following advantages:

[0027] The above-mentioned MMA monomer mold outer surface decoration injection mold and injection molding method thereof, by mixing MMA monomer resin, peroxide and MMA high-functional resin without self-polymerization, makes the mixing simple, the obtained monomer injection molding liquid has low viscosity and good fluidity, so that the monomer injection molding liquid can be injected into the surface of the curved injection molding substrate to form an ultra-thin injection molding layer; the vacuum component evacuates the decoration molding cavity, so that the monomer injection molding liquid can quickly fill the decoration molding cavity; the constant temperature component heats the decoration molding cavity to a constant temperature, so that the temperature of the decoration molding cavity is constant, and the temperature control of the front mold component and the rear mold component is simple; the monomer injection molding liquid is injected into the injection molding channel at low pressure, so that the decoration molding injection molding layer formed by the monomer injection molding liquid on the surface of the injection molding substrate is uniform, and the obtained ultra-thin decoration layer injection molding parts have good consistency; the injection molding method of the MMA monomer mold outer surface decoration is used for injection molding, the temperature of the decoration molding cavity and the injection pressure of the monomer injection molding liquid are low, so that the injection molding conditions are milder and less dependent on the mold and the feeding system, so that the obtained ultra-thin decoration layer injection molding parts have good consistency and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of an MMA single mold outer surface decoration injection mold according to an embodiment;

[0030] Figure 2 for Figure 1 The schematic diagram of the partial structure of the MMA single mold outer surface decoration injection mold shown;

[0031] Figure 3 FIG. 1 is a flow chart of the steps of an injection molding method for decorating the outer surface of an MMA single mold according to an embodiment. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0033] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0035] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0036] like Figure 1 and Figure 2 As shown, it is an MMA single-body mold outer surface decoration injection mold 10 of an embodiment of the present disclosure, including a mold structure 100 and a feeding structure 200, wherein the feeding structure 200 includes a mixing kettle 210, a feeding pipe 220 and a pump push assembly 230, wherein the feeding end of the feeding pipe 220 is connected to the mixing kettle 210, and the pump push assembly 230 is installed on the feeding pipe 220, and the pump push assembly 230 is used to control the discharge of the feeding pipe 220, and the discharge end of the feeding pipe 220 is provided with a nozzle 221.

[0037] Furthermore, the mold structure 100 includes a front mold component 110, a rear mold component 120, a constant temperature component 130, a vacuum component 140 and an adsorption component 150. The front mold component 110 is also provided with an injection channel 1103, the nozzle 221 is connected to the injection channel 1103, the rear mold component 120 is provided with a fixing groove 1201 for installing an injection molding substrate, the front mold component 110 is provided with a receiving cavity, the front mold component 110 is covered on the rear mold component 120, so that the injection molding substrate is fixed in the fixing groove 1201, and a decorative molding cavity 1101 is formed between the injection molding substrate and the cavity wall of the receiving cavity 1101. 102, the decorative molding cavity 1102 is connected to the injection molding channel 1103; the vacuum component 140 is connected to the decorative molding cavity 1102, and the vacuum component 140 is used to extract the air of the decorative molding cavity 1102. The heating ends of the constant temperature component 130 are respectively connected to the front mold component 110 and the rear mold component 120, and the constant temperature component 130 is used to heat the front mold component 110 and the rear mold component 120. The adsorption component 150 is installed in the rear mold component 120, and the adsorption component 150 is used to adsorb the side of the injection molding substrate away from the decorative molding cavity 1102.

[0038] In this embodiment, MMA monomer, peroxide initiator and high-functional MMA are first mixed through a mixing kettle 210 to obtain an MMA monomer injection molding liquid with low viscosity, and the injection molding substrate is installed in a fixed groove 1201 and pressed tightly. The front mold component 110 and the rear mold component 120 are kept at a constant temperature through the constant temperature component 130, and then the decorative molding cavity 1102 is evacuated through the vacuum component 140, and the adsorption component 150 sucks the inner wall of the injection molding substrate tightly. The mixed MMA monomer injection molding liquid is transported to the discharge end of the feed pipe 220 through the pump push component 230, and the MMA monomer injection molding liquid enters the decorative molding cavity 1102 through the injection channel 1103. The temperature of the front mold component 110 and the rear mold component 120 causes the MMA monomer injection molding liquid to undergo a self-polymerization reaction on the surface of the injection molding substrate. Due to the increase in the glass transition temperature of PMMA, PMMA forms a solid surface decorative layer on the surface of the injection molding substrate, and the injection molding substrate with the outer surface decoration of the mold is taken out after the mold is opened.

[0039] The above-mentioned MMA monomer mold outer surface decoration injection mold 10 obtains MMA monomer injection liquid with low viscosity by mixing through the mixing kettle 210. After the vacuum component 140 evacuates the decoration molding cavity 1102, the MMA monomer injection liquid is transported to the decoration molding cavity 1102 through the pump push component 230 for self-polymerization, so that the monomer injection liquid can form an ultra-thin injection layer on the surface of the curved injection molding substrate; the adsorption component 150 sucks the side of the injection molding substrate away from the decoration molding cavity 1102, thereby reducing the deformation of the surface of the injection molding substrate in the vacuum decoration molding cavity 1102, thereby making the quality and consistency of the ultra-thin injection layer formed on the surface of the injection molding substrate better.

[0040] like Figure 1 As shown, in one embodiment, the thickness of the decorative molding cavity 1102 is 0.1mm-0.3mm. In this embodiment, the mixing kettle 210 contains MMA monomer, peroxide initiator and high-functionality MMA monomer injection liquid. The MMA monomer does not undergo self-polymerization reaction in the mixing kettle 210 and the feeding pipe 220, so that the viscosity of the MMA monomer injection liquid is low and has good fluidity. When the MMA monomer injection liquid enters the negative pressure injection channel 1103 and the decorative molding cavity 1102, the MMA monomer injection liquid can quickly fill the decorative molding cavity 1102, thereby forming an ultra-thin decorative molding layer with a thickness of 0.1mm-0.3mm.

[0041] like Figure 1 As shown, in one embodiment, the feeding structure 200 further includes a heating component 240, the heating component 240 is installed in the mixing kettle 210, the heating end of the heating component 240 is arranged in the mixing kettle 210, and the heating component 240 is used to heat the material in the mixing kettle 210. In this embodiment, the MMA monomer injection molding liquid in the mixing kettle 210 is heated by the heating component 240, so that the viscosity of the MMA monomer injection molding liquid is reduced, and the MMA monomer injection molding liquid is easier to level, so that the MMA monomer injection molding liquid is easier to fill the decorative molding cavity 1102, and then the decorative molding layer formed on the surface of the injection molded substrate is smoother.

[0042] like Figure 1As shown, in one embodiment, the thermostatic component 130 includes a first thermostatic heating element 131 and a second thermostatic heating element 132, a plurality of first mounting grooves 1104 are provided in the front mold component 110, a plurality of second mounting grooves 1202 are provided in the rear mold component 120, each of the second thermostatic heating elements 132 is installed in the corresponding first mounting groove 1104, and each of the second thermostatic heating elements 132 is installed in the corresponding second mounting groove 1202. In this embodiment, the front mold component 110 is heated by the first thermostatic heating element 131, so that the temperature of each position of the front mold component 110 is uniform, and the rear mold component 120 is heated by the second thermostatic heating element 132, so that the temperature of each position of the rear mold component 120 is uniform, so that the MMA monomer injection molding liquid in the decoration molding cavity 1102 is heated evenly, and the stress and shrinkage of the decoration molding layer formed by the MMA monomer injection molding liquid are reduced.

[0043] like Figure 1 As shown, in one embodiment, each of the first constant temperature heating elements 131 and the corresponding second constant temperature heating elements 132 have the same height in the horizontal direction. In this embodiment, each of the first constant temperature heating elements 131 and the corresponding second constant temperature heating elements 132 have the same height in the horizontal direction, so that the front mold assembly 110 and the rear mold assembly 120 have the same heating or cooling effect at the same position, thereby avoiding mold deformation and defects in the decorative molding layer caused by uneven heating.

[0044] like Figure 1 As shown, in one embodiment, the injection channel 1103 is located above the decoration molding cavity 1102. In this embodiment, when the MMA monomer injection liquid is injected into the decoration molding cavity 1102, it naturally flows downward due to the effect of gravity until the decoration molding cavity 1102 is completely filled, thereby reducing bubbles and voids during the injection molding process and improving the quality and consistency of the formed decoration molding layer.

[0045] like Figure 1 As shown, in one embodiment, the mold structure 100 further includes a heat insulating member 160, the nozzle 221 is installed in the front mold assembly 110, the heat insulating member 160 is sleeved on the nozzle 221, and the heat insulating member 160 is used to isolate the nozzle 221 from contacting the front mold assembly 110. In this embodiment, the MMA monomer injection liquid is a polymerization reaction of the MMA monomer initiated by temperature, and the heat insulating member 160 can be made of a heat insulating material or the heat insulating member 160 is a hollow structural member to avoid contact between the front mold assembly 110 and the nozzle 221, to prevent the MMA monomer from prematurely producing a polymerization reaction and entering the injection channel 1103 and the decorative molding cavity 1102, and to avoid the MMA polymerization reaction blocking the injection channel 1103 and the decorative molding cavity 1102.

[0046] like Figure 2 As shown, in one embodiment, the adsorption assembly 150 includes an adsorption mounting platform 151, an adsorption pipe 152 and an adsorption pump. The adsorption mounting platform 151 is provided with a connected adsorption hole 1501 and a negative pressure cavity 1502. The adsorption hole 1501 is connected to the fixing groove 1201, the negative pressure cavity 1502 is connected to the adsorption pipe 152, and the adsorption pipe 152 is connected to the adsorption pump. In this embodiment, the adsorption pump generates suction force, so that negative pressure is generated in the negative pressure cavity 1502, and the adsorption hole 1501 sucks the side of the injection molding substrate away from the decorative molding cavity 1102, so that the injection molding substrate is attached to the adsorption mounting platform 151, thereby reducing the deformation of the decorative molding cavity 1102, and further making the decorative molding layer formed on the surface of the injection molding substrate smoother.

[0047] In one embodiment, the number of the adsorption holes 1501 is multiple, and the multiple adsorption holes 1501 are spaced apart on the adsorption mounting platform 151. In this embodiment, the multiple adsorption holes 1501 tightly adsorb the side of the injection molded substrate away from the decorative molding cavity 1102, so that the injection molded substrate is more evenly attached to the adsorption mounting platform 151, further reducing the deformation of the decorative molding cavity 1102, so that the quality and consistency of the decorative layer formed on the surface of the injection molded substrate are higher.

[0048] like Figure 2 As shown, in one embodiment, the vacuum assembly 140 includes a solenoid valve 141, a vacuum tube 142 and a vacuum pump 143, the front film assembly is provided with a vacuum installation hole 1105, the vacuum tube 142 is installed in the vacuum installation hole 1105, the vacuum tube 142 is connected to the end of the decoration molding cavity 1102 away from the injection channel, the solenoid valve 141 is installed at the end of the vacuum tube 142 adjacent to the decoration molding cavity 1102, and the vacuum pump 143 is connected to the vacuum tube 142. In this embodiment, the solenoid valve 141 is used to control the connection between the decoration molding cavity 1102 and the vacuum tube 142, and the vacuum pump 143 is opened to exhaust air so that a negative pressure vacuum environment is formed in the decoration molding cavity 1102. A pressure display gauge is also provided on the vacuum tube 142 to control the vacuum degree of the decoration molding cavity 1102, and the connection between the decoration molding cavity 1102 and the vacuum tube 142 is closed by the solenoid valve 141, so as to prevent the MMA monomer injection liquid from entering the vacuum tube 142.

[0049] In one of the embodiments, the closing accuracy of the front mold assembly 110 and the rear mold assembly 120 is less than 0.005 mm. In this embodiment, during the injection molding process, the front mold assembly 110 and the rear mold assembly 120 are closed to form a complete cavity for accommodating molten injection liquid. The closing accuracy of the front mold assembly 110 and the rear mold assembly 120 is less than 0.005 mm, so that the gap or misalignment during closing is small, avoiding leakage of injection liquid and deformation of the mold, thereby improving the stability and accuracy of the injection molding process and ensuring the consistency and quality of the product.

[0050] like Figure 3 As shown, it is an injection molding method for MMA single mold outer surface decoration according to an embodiment of the present disclosure, which is prepared by using the mold for MMA single mold outer surface decoration injection molding described in any of the above embodiments. The injection molding method for MMA single mold outer surface decoration comprises the following steps:

[0051] S101: Add MMA monomer resin, peroxide and MMA high-functional resin to the mixing kettle for mixing to obtain monomer injection molding liquid. In this embodiment, the peroxide can be dibenzoyl peroxide as an initiator, which is decomposed into free radicals by the action of heat, and then initiates the cross-linking of methyl methacrylate MMA monomer resin to produce free radical polymerization reaction, thereby obtaining a decorative molding injection molding layer of polymethyl methacrylate PMMA, and the MMA high-functional resin can improve the glass transition temperature and bonding performance of polymethyl methacrylate PMMA; when the MMA monomer resin, peroxide and MMA high-functional resin are mixed in the mixing kettle, no free radical polymerization reaction is generated, so the mixing between the MMA monomer resin, peroxide and MMA high-functional resin is simple, and the obtained monomer injection molding liquid has a low viscosity and good fluidity, and the monomer injection molding liquid can flow into the decorative molding cavity with a thickness between 0.1mm-0.3mm, so that the monomer injection molding liquid can be injected into an ultra-thin injection molding layer on the surface of the curved injection molding substrate.

[0052] S10: Install the injection molding substrate in the injection molding fixing groove, and the vacuum component evacuates the decoration molding cavity on the surface of the injection molding substrate, so that the decoration molding cavity and the connected injection molding channel form a negative pressure environment. In this embodiment, the decoration molding cavity is used to form a decoration molding injection layer, and the decoration molding cavity and the connected injection molding channel are evacuated to form a negative pressure environment. The monomer injection molding liquid is more attracted during the process of passing through the injection molding channel and the decoration molding cavity, so that the monomer injection molding liquid fully and quickly fills the decoration molding cavity, and the decoration molding cavity is kept in a flowing state during the process of the monomer injection molding liquid entering, so that the formed decoration molding injection layer has fewer bubbles, thereby improving the quality of the formed decoration molding injection layer.

[0053] S105: The front mold assembly and the rear mold assembly are heated to a constant temperature by the constant temperature assembly, so that the constant temperature of the decoration molding cavity is 60°C-100°C. In the present embodiment, the front mold assembly and the rear mold assembly are heated by a constant temperature component, so as to keep the decoration molding cavity constant at 60°C-100°C, and the monomer injection molding liquid is heated in the decoration molding cavity to induce a self-polymerization reaction, and the monomer injection molding liquid is polymerized to form polymethyl methacrylate PMMA, and the polymethyl methacrylate PMMA forms a decoration molding injection molding layer. The glass transition temperature of polymethyl methacrylate PMMA is generally above 105°C, and the constant temperature of the decoration molding cavity is 60°C-100°C. The glass transition temperature of polymethyl methacrylate PMMA is higher than the constant temperature, so that the decoration molding injection molding layer is in a solidified state. Therefore, the front mold assembly and the rear mold assembly do not need a cooling assembly to cool the decoration molding injection molding layer, thereby reducing the generation of internal stress. The front mold assembly and the rear mold assembly only need to maintain a constant temperature, and the temperature of the decoration molding injection molding layer formed in the decoration molding cavity is fixed, so that the decoration molding injection molding layer formed on the surface of the injection molding substrate has high consistency.

[0054] S107 injects the monomer injection liquid into the injection channel at low pressure through the nozzle, and the pressure of the low pressure injection is 0.1Mpa-0.5Mpa. The monomer injection liquid enters the decorative molding cavity after passing through the injection channel. In this embodiment, the decorative molding injection layer formed is between 0.1mm-0.3mm, and its thickness is relatively thin. The viscosity of the monomer injection liquid is relatively low, so that the monomer injection liquid has good fluidity. Therefore, the injection pressure of 0.1Mpa-0.5Mpa is relatively low, and the monomer injection liquid with good fluidity can smoothly fill the decorative molding cavity, and the impact of the monomer injection liquid on the injection substrate is relatively small. The monomer injection liquid can quickly cover the injection substrate, so that the decorative molding layer formed in the decorative molding cavity is uniform;

[0055] It is understandable that when the pressure of the low-pressure injection of the monomer injection liquid is less than 0.1Mpa, the monomer injection liquid is insufficient to fill the decorative molding cavity, so that the decorative molding layer formed by the decorative molding cavity forms a cavity and white fine sand lines, stripes, shrinkage and extrusion marks appear on the surface, affecting the surface integrity and structural strength of the injection molded substrate. When the low-pressure injection pressure of the monomer injection liquid is greater than 0.5Mpa, the injection molding of the decorative molding layer is prone to internal stress, causing the injection molded substrate to deform and crack during use. However, when the injection molding is performed under low pressure conditions, the impact on the injection molded substrate is also small when the pressure is greater than 0.5Mpa; the low-pressure injection pressure is 0.1Mpa-0.5Mpa, so that the decorative molding cavity is fully filled with the monomer injection liquid, and the stress of the decorative molding injection layer formed after the monomer injection liquid self-polymerizes is less.

[0056] S109: continuously injecting the monomer injection liquid into the injection channel through the nozzle to maintain the pressure of the monomer injection liquid in the decorative molding cavity. The monomer injection liquid in the decorative molding cavity is heated to produce a self-polymerization reaction, so that a decorative molding injection layer is formed on the surface of the injection substrate to obtain an ultra-thin decorative layer injection molded part. In this embodiment, the monomer injection liquid shrinks when it is heated to produce a self-polymerization reaction to form polymethyl methacrylate PMMA. The monomer injection liquid is continuously injected into the injection channel through the nozzle to maintain the pressure, so that the decorative molding cavity is filled, thereby reducing the shrinkage of the decorative molding injection layer, and further improving the quality of the obtained ultra-thin decorative layer injection molded part.

[0057] S109: taking out the ultra-thin decorative layer injection molded part. In this embodiment, the ultra-thin decorative layer injection molded part is solidified in the decorative molding cavity. Due to the low injection pressure, the ultra-thin decorative layer injection molded part is prevented from being too tightly attached to the front mold assembly. The temperature of the front mold assembly and the rear mold assembly is low, which prevents the ultra-thin decorative layer injection molded part from adhering to the front mold assembly. Moreover, the front mold assembly and the rear mold assembly are not cooled, and the front mold assembly and the rear mold assembly are in a hot mold state, so that the ultra-thin decorative layer injection molded part can be demolded quickly, thereby obtaining an ultra-thin decorative layer injection molded part with good surface quality.

[0058] The above-mentioned injection molding method for MMA monomer mold outer surface decoration does not self-polymerize when mixing MMA monomer resin, peroxide and MMA high-functional resin, so that the mixing is simple, the obtained monomer injection molding liquid has low viscosity and good fluidity, so that the monomer injection molding liquid can be injected into the surface of the curved injection molding substrate to form an ultra-thin injection molding layer; the vacuum component evacuates the decoration molding cavity, so that the monomer injection molding liquid can quickly fill the decoration molding cavity; the constant temperature component heats the decoration molding cavity to a constant temperature, so that the temperature of the decoration molding cavity is constant, and the temperature control of the front mold component and the rear mold component is simple; the monomer injection molding liquid is injected into the injection molding channel at low pressure, so that the decoration molding injection molding layer formed by the monomer injection molding liquid on the surface of the injection molding substrate is uniform, and the obtained ultra-thin decoration layer injection molding parts have good consistency; the injection molding method for MMA monomer mold outer surface decoration is used for injection molding, and the temperature of the decoration molding cavity and the injection pressure of the monomer injection molding liquid are low, so that the injection molding conditions are milder and less dependent on the mold and the feeding system, so that the obtained ultra-thin decoration layer injection molding parts have good consistency and quality.

[0059] In one embodiment, the vacuum pressure of the vacuum assembly is -1.2Mpa to -0.8Mpa. In this embodiment, the injection channel and the decorative molding cavity are vacuumed by the vacuum assembly to form a vacuum environment, which is conducive to the monomer injection liquid flowing smoothly and quickly into the injection channel and the decorative molding cavity, and the monomer injection liquid fills the decorative molding cavity, so that the formed decorative molding injection layer is evenly covered on the surface of the injection molding substrate, avoiding the appearance of cavities in the decorative molding injection layer and defects such as white fine sand lines, stripes, shrinkage and extrusion marks on the surface.

[0060] Furthermore, in one embodiment, before the injection molding substrate is installed in the injection molding fixing groove, the vacuum component evacuates the decoration molding cavity to form a negative pressure environment in the decoration molding cavity and the connected injection molding channel, after the MMA monomer resin, peroxide and MMA high-functional resin are added to the mixing kettle for mixing, and after the monomer injection molding liquid is obtained, the following steps are also included:

[0061] The side of the injection molding substrate facing away from the decorative molding cavity is adsorbed by an adsorption component.

[0062] In this embodiment, when the injection molding substrate is relatively thin, the vacuum component evacuates the decorative molding cavity, and the thin-walled portion of the injection molding substrate is prone to slight deformation. Therefore, the adsorption component is used to adsorb the side of the injection molding substrate away from the decorative molding cavity, and the injection molding substrate is tightly attached to the rear mold assembly. The shape of the decorative molding cavity between the injection molding substrate and the front mold assembly is fixed, so that the shape of the decorative molding injection layer formed by the decorative molding cavity is fixed, thereby making the obtained ultra-thin decorative layer injection molded parts have better consistency.

[0063] Furthermore, in one of the embodiments, when the monomer injection molding liquid is injected into the injection molding channel at low pressure, the injection amount of the nozzle is metered and controlled, and the metering error is less than 5%, and the injection amount control error is less than 10%. In this embodiment, the amount of glue is calculated according to production requirements, or a meter is set at the end of the nozzle, and a weighing device is used to indirectly measure the injection amount, and the injection amount of the nozzle is adjusted to less than 10%, thereby quantitatively controlling the injection amount of the nozzle, so that the injection amount error of the monomer injection molding liquid sprayed out by the nozzle each time is small, so that the amount of monomer injection molding liquid entering the decorative molding cavity is consistent, and then the consistency of the decorative molding injection molding layer is better.

[0064] Furthermore, in one of the embodiments, the thermostatic component heats the front mold component and the rear mold component to a constant temperature, and the constant temperature needs to be controlled at 3°C-5°C. In this embodiment, the first thermostatic heating element and the second thermostatic heating element of the thermostatic component are respectively passed through the front mold component and the rear mold component through heating pipes, so that the front mold component and the rear mold component are heated to a constant temperature, and the constant temperature is controlled to be less than 5°C, so that when the set temperature is 100°C, the temperature in the decorative molding cavity is always less than the glass transition temperature of polymethyl methacrylate PMMA 105°C; the constant temperature needs to be controlled to be less than 3°C, and a large number of heating pipes are required through the first thermostatic heating element and the second thermostatic heating element of the thermostatic component, and the control requirements of the heating pipes are high, which increases the production cost.

[0065] In one embodiment, the viscosity of the monomer injection liquid is 200Pa·s-500Pa·s. In this embodiment, when the viscosity of the monomer injection liquid is less than 500Pa·s, the monomer injection liquid has good fluidity, so that the monomer injection liquid can flow smoothly into the decorative molding cavity. When the viscosity of the monomer injection liquid is less than 200Pa·s, the viscosity of the monomer injection liquid is low. When the monomer injection liquid enters the nozzle from the feed pipe, the injection speed of the monomer injection liquid is too fast, which easily causes bubbles to be generated in the monomer injection liquid, thereby affecting the quality of the decorative molding injection layer formed in the decorative molding cavity.

[0066] Furthermore, in one embodiment, the monomer injection liquid in which the MMA monomer resin, peroxide and MMA high-functional resin are added to the mixing kettle includes the following mass components:

[0067] MMA monomer resin: 88-94 parts;

[0068] Peroxide: 1-2 parts;

[0069] MMA high-functional resin: 5-10 parts.

[0070] In this embodiment, the heat deformation temperature of polymethyl methacrylate (PMMA) formed by self-polymerization of MMA monomer resin is about 95°C, but since the heat deformation temperature of polymethyl methacrylate (PMMA) is lower than the glass transition temperature, polymethyl methacrylate (PMMA) formed by polymerization of MMA monomer resin is prone to deformation when the heat deformation temperature is lower than the constant temperature. With MMA monomer resin as the main body, the monomer injection liquid has good fluidity, peroxide can induce polymerization reaction of MMA monomer resin, and MMA high-functional resin makes polymethyl methacrylate (PMMA) formed by MMA monomer resin have higher glass transition temperature and heat deformation temperature.

[0071] Furthermore, before the MMA monomer resin, peroxide and MMA high-functional resin are added to the mixing kettle, the following steps are included:

[0072] Performing a premix production operation on the pre-proportioned MMA monomer resin, peroxide and MMA high-functional resin to obtain a pre-production test polymethyl methacrylate PMMA;

[0073] Check whether the heat deformation temperature of polymethyl methacrylate (PMMA) in pre-production test is less than the preset deformation temperature;

[0074] When the heat deformation temperature of the pre-production test polymethyl methacrylate PMMA is less than the preset deformation temperature, specifically, the preset deformation temperature is 95°C-100°C, the monomer injection liquid ratio increases 0.58%-1.28% of the high-grade resin mass component, and reduces 0.58%-1.28% of the MMA monomer resin mass component, so that the heat deformation temperature of the decorative molding injection layer is increased;

[0075] When the heat deformation temperature of the pre-production test polymethyl methacrylate PMMA is greater than the preset deformation temperature, for example, when the heat deformation temperature of the pre-production test polymethyl methacrylate PMMA is detected to be 100-110°C, the mass components of the monomer injection liquid ratio remain unchanged. In this embodiment, MMA high-ranking resin is added to increase the cross-linking and copolymerization of MMA monomer resin and MMA high-ranking resin, thereby increasing the cross-linking degree of polymethyl methacrylate PMMA, so that the glass transition temperature and heat deformation temperature of polymethyl methacrylate PMMA are increased at the same time. Specifically, a premix production operation is first performed by pre-proportioning MMA monomer resin, peroxide and MMA high-ranking resin in a small batch, and the heat deformation temperature of polymethyl methacrylate PMMA is verified, so as to adjust the monomer injection liquid ratio so that the glass transition temperature of the obtained polymethyl methacrylate PMMA is greater than 110°C and the heat deformation temperature is greater than 100°C, so that the decorative molding injection layer formed by polymethyl methacrylate PMMA has a higher degree of curing, and the decorative molding injection layer is not easy to deform and is more stable.

[0076] Furthermore, in one of the embodiments, after adding the MMA high-ranking resin, the viscosity of the obtained monomer injection molding liquid increases, which affects the fluidity. The viscosity of the monomer injection molding liquid obtained by adding different amounts of MMA high-ranking resin is different, and the viscosity of the monomer injection molding liquid needs to be adjusted for different proportions of MMA high-ranking resin. When the viscosity of the monomer injection molding liquid is low, its fluidity is good, the flow rate of the pump-push component conveying the monomer injection molding liquid is fast, and the monomer injection molding liquid is easily generated when it is injected into the injection molding channel, and then bubbles are generated, so that the formation of the decorative molding injection molding layer has defects; when the viscosity of the monomer injection molding liquid is high, its fluidity is poor, the flow rate of the pump-push component conveying the monomer injection molding liquid is slow, and the monomer injection molding liquid is easily insufficiently filled when it is injected into the injection molding channel, so that the formation of the decorative molding injection molding layer has defects. Therefore, after adding the MMA monomer, peroxide and MMA high-ranking resin into the mixing kettle for mixing, and obtaining the monomer injection molding liquid, the injection molding substrate is installed in the injection molding fixing groove, and before the decorative molding cavity is vacuumed, the following steps are also included:

[0077] Controlling the viscosity of the monomer injection molding liquid, heating the monomer injection molding liquid in the mixing kettle by the heating component, the temperature of the monomer injection molding liquid is between 30° C. and 50° C., and testing the viscosity of the monomer injection molding liquid;

[0078] If the viscosity of the monomer injection molding liquid is less than 200Pa·s, the heating component reduces the output power and simultaneously reduces the pressure through the pump-push component, and the delivery pressure of the pump-push component is reduced by 0.1Mpa-0.4Mpa to reduce the temperature of the monomer injection molding liquid by 1°C-10°C; it can be understood that when the viscosity of the monomer injection molding liquid is less than 200Pa·s, the flow rate of the monomer injection molding liquid is faster, and the heating component reduces the output power, so that the temperature of the monomer injection molding liquid is reduced and the viscosity is increased, thereby reducing the flow rate of the monomer injection molding liquid. The reduction in the delivery pressure of the pump-push component further reduces the flow rate of the monomer injection molding liquid, so that the monomer injection molding liquid is injected into the injection channel at a suitable flow rate.

[0079] If the viscosity of the monomer injection molding liquid is greater than 500Pa·s, the output power of the heating component is increased and pressurized through the pump-push component at the same time, the delivery pressure of the pump-push component is increased by 0.1Mpa-0.4Mpa, so that the temperature of the monomer injection molding liquid is increased by 1°C-10°C; it can be understood that when the viscosity of the monomer injection molding liquid is greater than 200Pa·s, the flow rate of the monomer injection molding liquid is slow, and the heating component reduces and increases the power, so that the temperature of the monomer injection molding liquid increases and the viscosity decreases, thereby increasing the flow rate of the monomer injection molding liquid. The increase in the delivery pressure of the pump-push component further increases the flow rate of the monomer injection molding liquid, so that the monomer injection molding liquid is injected into the injection channel at a suitable flow rate.

[0080] If the viscosity of the monomer injection liquid is 200Pa·s-500Pa·s, the heating component maintains the output power and the pump push component maintains the delivery pressure.

[0081] In this embodiment, the monomer injection molding liquid contains MMA high-functional resin, which increases the viscosity of the monomer injection molding liquid. The viscosity of the monomer injection molding liquid is reduced by heating, so that the viscosity of the monomer injection molding liquid is controlled at 200Pa·s-500Pa·s, so that the monomer injection molding liquid can be smoothly injected into the injection channel; the monomer injection molding liquid is prone to self-polymerization when the temperature is greater than 60°C, thereby polymerizing in the mixing kettle to form polymethyl methacrylate PMMA in advance, resulting in production stoppage, so the temperature is set below 50°C, so that the monomer injection molding liquid is produced at a safe temperature, and the temperature is set above 30°C, so that the temperature is higher than room temperature, which facilitates the heating component to control the temperature rise.

[0082] Furthermore, in one embodiment, when the MMA monomer resin, peroxide and MMA high-functional resin are mixed in the mixing kettle and a large number of bubbles are generated, the bubbles will affect the fluid properties and reduce the transmission quality. Therefore, after adding the MMA monomer, peroxide and MMA high-functional resin into the mixing kettle for mixing to obtain the monomer injection liquid, the injection molding substrate is installed in the injection molding fixing groove, and before the decorative molding cavity is vacuumed, the following steps are also included:

[0083] The monomer injection molding liquid in the mixing kettle is subjected to negative pressure degassing, and the mixing kettle is evacuated so that the negative pressure range in the mixing kettle is -0.1Mpa to -0.3Mpa. In this embodiment, the mixing kettle is evacuated by a vacuum pump or other negative pressure equipment to form a negative pressure environment in the mixing kettle, and the bubbles in the monomer injection molding liquid are separated due to the negative pressure, thereby reducing the bubbles in the monomer injection molding liquid. Since the viscosity of the monomer injection molding liquid is relatively low, the degassing effect of the monomer injection molding liquid is better by a relatively low negative pressure, so that the transmission quality of the monomer injection molding liquid is relatively high, and the monomer injection molding liquid is smoothly transported into the injection channel through the pump push component.

[0084] Furthermore, in one of the embodiments, after the ultra-thin decorative layer injection molded part is taken out, the ultra-thin decorative layer injection molded part is also subjected to hot air blowing. In this embodiment, after the decorative molding injection molded layer is formed on the surface of the injection molding substrate, the decorative molding injection molded layer still has residual internal stress, which may cause the decorative molding injection molded layer to deform during the natural cooling process. By blowing hot air on the ultra-thin decorative layer injection molded part, the internal stress in the injection molding substrate and the decorative molding injection molded layer is eliminated, so that the obtained ultra-thin decorative layer injection molded part has better quality. The hot air blowing temperature is 70℃-80℃, and the temperature of the hot air is lower than the thermal deformation temperature of polymethyl methacrylate PMMA. At the same time, the difference between the hot air temperature and the constant temperature is small, which avoids the stress problem caused by the rapid cooling and shrinkage of the decorative molding injection molded layer.

[0085] In one of the embodiments, the holding time is 40s-60s. In this embodiment, the monomer injection liquid undergoes a self-polymerization reaction in the decoration molding cavity to form a decoration molding injection layer, and the reaction is fast at a constant temperature between 60°C and 100°C, and the holding time is 40s-60s, so that the decoration molding injection layer is fully solidified and the injection molding process is faster, thereby improving the production quality and production speed of ultra-thin decoration layer injection molded parts.

[0086] In one embodiment, the nozzle continuously injects the monomer injection liquid to maintain the pressure of the decorative molding cavity, and the pressure maintenance pressure is 0.1Mpa-0.5Mpa. In this embodiment, the pressure maintenance pressure is the same as the pressure of the nozzle initially injected into the injection channel, so that the pressure of the monomer injection liquid in the injection channel and the decorative molding cavity is consistent, and the pressure control of the nozzle is simple, so that the decorative molding injection layer formed in the decorative molding cavity is uniform, and the ultra-thin decorative layer injection molded parts obtained are of better quality.

[0087] Compared with the prior art, the present invention has at least the following advantages:

[0088] The above-mentioned injection molding method for MMA monomer mold outer surface decoration does not self-polymerize when mixing MMA monomer resin, peroxide and MMA high-functional resin, so that the mixing is simple, the obtained monomer injection molding liquid has low viscosity and good fluidity, so that the monomer injection molding liquid can be injected into the surface of the curved injection molding substrate to form an ultra-thin injection molding layer; the vacuum component evacuates the decoration molding cavity, so that the monomer injection molding liquid can quickly fill the decoration molding cavity; the constant temperature component heats the decoration molding cavity to a constant temperature, so that the temperature of the decoration molding cavity is constant, and the temperature control of the front mold component and the rear mold component is simple; the monomer injection molding liquid is injected into the injection molding channel at low pressure, so that the decoration molding injection molding layer formed by the monomer injection molding liquid on the surface of the injection molding substrate is uniform, and the obtained ultra-thin decoration layer injection molding parts have good consistency; the injection molding method for MMA monomer mold outer surface decoration is used for injection molding, and the temperature of the decoration molding cavity and the injection pressure of the monomer injection molding liquid are low, so that the injection molding conditions are milder and less dependent on the mold and the feeding system, so that the obtained ultra-thin decoration layer injection molding parts have good consistency and quality.

[0089] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. An MMA single mold outer surface decoration injection mold, comprising a mold structure and a feeding structure, wherein the feeding structure comprises a mixing kettle, a feeding pipe and a pump push assembly, wherein the feeding end of the feeding pipe is connected to the mixing kettle, the pump push assembly is installed on the feeding pipe, and the discharge end of the feeding pipe is provided with a nozzle, characterized in that: The mold structure includes a front mold component, a rear mold component, a constant temperature component, a vacuum component and an adsorption component. The front mold component is provided with an injection channel, the nozzle is connected to the injection channel, the rear mold component is provided with a fixing groove for installing an injection molding substrate, the front mold component is provided with an accommodating cavity, the front mold component is covered on the rear mold component so that the injection molding substrate is fixed in the fixing groove, a decorative molding cavity is formed between the injection molding substrate and the cavity wall of the accommodating cavity, and the decorative molding cavity is connected to the injection channel; The vacuum component is connected to the decorative molding cavity, and the vacuum component is used to extract the air from the decorative molding cavity. The heating end of the constant temperature component is respectively connected to the front mold component and the rear mold component. The adsorption component is installed in the rear mold component, and the adsorption component is used to adsorb the side of the injection molding substrate away from the decorative molding cavity.

2. The MMA single mold outer surface decoration injection mold according to claim 1, characterized in that: The inner thickness of the decorative molding cavity is 0.1 mm-0.3 mm.

3. The MMA single mold outer surface decoration injection mold according to claim 1, characterized in that: The feeding structure further comprises a heating component, wherein the heating component is mounted on the mixing kettle, a heating end of the heating component is arranged in the mixing kettle, and the heating component is used to heat the material in the mixing kettle.

4. The MMA single mold outer surface decoration injection mold according to claim 1, characterized in that: The mold structure also includes a heat insulating member, the discharge end of the feed pipe is installed in the front mold assembly, the heat insulating member is sleeved on the discharge end of the feed pipe, and the heat insulating member is used to isolate the discharge end of the feed pipe from contact with the front mold assembly.

5. The MMA single mold outer surface decoration injection mold according to claim 1, characterized in that: The adsorption assembly includes an adsorption mounting platform, an adsorption pipeline and an adsorption pump. The adsorption mounting platform is provided with interconnected adsorption holes and a negative pressure chamber. The adsorption holes are connected to the fixed groove, the negative pressure chamber is connected to the adsorption pipeline, and the adsorption pipeline is connected to the adsorption pump.

6. An injection molding method for decorating the outer surface of an MMA single mold, characterized in that: The mold for the outer surface decoration injection molding of the MMA single mold described in claims 1 to 5 is used for preparation, and the injection molding method for the outer surface decoration of the MMA single mold comprises the following steps: Adding MMA monomer resin, peroxide and MMA high-functional resin into the mixing kettle for mixing to obtain monomer injection liquid; The injection molding substrate is installed in the injection molding fixing groove, and the vacuum component evacuates the decoration molding cavity to form a negative pressure environment in the decoration molding cavity and the connected injection molding channel; The front mold assembly and the rear mold assembly are heated to a constant temperature by the constant temperature assembly so that the constant temperature of the decoration molding cavity is 60° C.-100° C.; The monomer injection liquid is injected into the injection channel at low pressure through the nozzle, the pressure of the low pressure injection is 0.1Mpa-0.5Mpa, and the monomer injection liquid enters the decoration molding cavity after passing through the injection channel; The monomer injection molding liquid is continuously injected into the injection molding channel through the nozzle to maintain the pressure of the monomer injection molding liquid in the decoration molding cavity, and the monomer injection molding liquid in the decoration molding cavity is heated to produce a self-polymerization reaction, so that a decoration molding injection molding layer is formed on the surface of the injection molding substrate to obtain an ultra-thin decoration layer injection molded part; The ultra-thin decorative layer injection-molded part is taken out.

7. The injection molding method for decorating the outer surface of a MMA single mold according to claim 6, characterized in that: The viscosity of the monomer injection liquid is 200 Pa·s-500 Pa·s.

8. The injection molding method for decorating the outer surface of a MMA single mold according to claim 6, characterized in that: The vacuum pressure of the negative pressure environment of the decoration molding cavity is -1.2Mpa to -0.8Mpa.

9. The injection molding method for decorating the outer surface of a MMA single mold according to claim 6, characterized in that: The holding time is 40s-60s.

10. The injection molding method for decorating the outer surface of a MMA single mold according to claim 6, characterized in that: The holding pressure of the monomer injection liquid in the decoration molding cavity is 0.1Mpa-0.5Mpa.

Images