CN101367268B - Surface treatment method - Google Patents

Abstract

The invention relates to a surface treatment method, which is applied to plastics. The treatment method comprises the following steps of lowering a plastic melting temperature to a glass conversion temperature of the plastics, carrying out pressure maintaining treatment to the plastics at the glass conversion temperature, lowering the glass conversion temperature of the plastics to a quenching temperature, heating from the quenching temperature to a tempering temperature and then cooling from the tempering temperature to an indoor temperature, wherein the quenching temperature is about 5 to 50 DEG C lower than the indoor temperature. The treatment method can effectively improve the surface properties of plastic products, and effectively improves the surface brightness, smoothness and fracture toughness of the products.

Description

Surface treatment method

The application is that application number is dividing an application of 200510037359.7 patent applications.200510037359.7 the applying date of number patent application is on September 16th, 2005, name is called " surface treatment method ".

Technical field

The invention relates to a kind of surface treatment method, especially about a kind of surface treatment method that improves surface property.

Background technology

Along with development of science and technology, the market competition of consumption electronic products is also more and more fierce.In order to attract the consumer to buy electronic product, except the function of this product, the outward appearance of product has become one of this product key of success factor.

Consumption electronic products shell commonly used often adopts plastic material, and the surface was more coarse when this plastic cement was unprocessed, and intense darkness without light, thereby had influence on product appearance.Because of consumption electronic products often need be touched, so its wearability is also very important.In addition, product casing also need bear certain impulsive force, thereby can or not drop because of accidental shock product appearance is damaged.

For improving the surface property of plastic shell, need carry out specially treated to it.Traditional manufacturing process often adopts heat treated mode, as quenching, tempering etc.Yet, traditional technology because of its quench cooled to room temperature, wherein the crystal grain of product casing is thicker, not only influence the brightness and the smoothness of product surface, and toughness is lower, can not satisfy consumer's requirement.

Summary of the invention

In view of this, be necessary to provide a kind of surface treatment method that improves the product casing performance.

A kind of surface treatment method, it is applied to plastic cement, this processing method is reduced to the glass transition temperature of plastic cement from the plastic cement melt temperature, under this glass transition temperature, plastic cement is carried out pressurize and handle, reduce to hardening heat from the glass transition temperature of plastic cement again, be heated to temperature by hardening heat then, be cooled to indoor temperature by temperature at last, wherein this hardening heat is lower than about 5 ℃-20 ℃ of indoor temperature, and this temperature is 80-100 ℃, and described plastic cement is that ABS adds glass fibre.

Compare prior art, surface treatment method of the present invention effectively improves the product surface performance by rapid quenching technology and flash tempering process, has effectively improved product surface brightness, smoothness and fracture toughness.

Description of drawings

Fig. 1 is the curve map of preferred embodiment of the present invention plastic cement surface treatment method temperature to the time.

The specific embodiment

Surface treatment method of the present invention is applied to improve the outward appearance of the plastic shell of consumption electronic products.

This surface treatment method improving plastic cement surface brightness and smoothness, and improves its toughness by rapid quenching and flash tempering process, describes this surface treatment method below in conjunction with concrete diagram.

See also Fig. 1, this quenching and tempering temperature curve control is applied to the plastic shell ejection formation last stage.T₂Represent the plexiglas inversion temperature, T_RRepresent indoor temperature, T_qRepresent hardening heat, Ta represents temperature.This plastic material at first is written in the barrel of jet modling make-up machine with the particles submode, through being heated to plastic cement melting state, the melt plastic cement temperature is generally about 300 ℃, and this moment, plastic cement had sufficient flowability, melt plastic cement flows into runner from barrel, injects in the die cavity by runner again.After die cavity is full of melt plastic cement fully, reduce to the plexiglas inversion temperature by this plastic cement melting temperature again, this glass transition temperature is made as T₂, the glass transition temperature of plastic material about about 100 ℃, gives pressurize afterwards and handles greatly under this temperature, and the time is 10 seconds usually; After the pressurize, with plastic cement from this glass transition temperature T₂Drop to hardening heat T rapidly_q, this hardening heat T_qBe lower than indoor temperature T_RScope between 5 ℃-20 ℃, from plexiglas inversion temperature T₂Drop to hardening heat T_qFast speeds control is arranged, and its rate of temperature fall generally is controlled to be 5 ℃/second-100 ℃/second, preferably adopts 20 ℃/second-50 ℃/second scope.

Keep this hardening heat T again_qApproximately 10-20 is after second, with plastic cement from hardening heat T_qRapidly increase to temperature Ta, the scope of this temperature Ta is at 80-100 ℃, from hardening heat T_qBe raised to temperature T_aSpeed control is arranged, and its speed is controlled to be 5 ℃/second-80 ℃/second usually, and the speed that preferred tempering heats up is 10 ℃/second-40 ℃/second.Be incubated 20-60 second under this temperature Ta, afterwards, plastic cement will drop to indoor temperature T with 10 ℃/second-20 ℃/second speed_R, last, open die cavity, eject plastic shell and get final product.

This plastic shell adopts rapid quenching and prompt tempering, and very fast because of quenching velocity, and hardening heat is lower than indoor temperature T_R, the not free diffusion of plastic cement crystal grain increases, thereby can reduce the inner crystallite dimension of plastic cement, and then, can improve surface brightness, smoothness and the surface toughness of plastic shell.

Oxidized when the moulding for further preventing melt plastic cement, when rapid quenching and prompt tempering, can fill nitrogen (N by ventilation technology₂) or other inert gas, as one of argon (Ar), helium (He) or its combination etc., to prevent the oxidized or jaundice in plastic cement surface.

This plastic material can be a synthetic material, and it can be for ABS adds glass fibre, and this kind plastic cement can be applicable to mobile phone, notebook, desktop computer, DVD, LCD etc.

Adopt the rapid quenching of above-mentioned technology can greatly improve the fracture toughness of plastic shell.Usually the fracture toughness value of material is high more, and the plastic cement surface property is good more.This fracture strength and crystallite dimension square root are inversely proportional to, and it can be represented by following formula:

K_1c∝sy×(3.14159×c/d)^0.5

K wherein_1cThe expression critical stress intensity factors, sy represents yield strength, and c represents breaking length, and d represents crystallite dimension, and therefore, crystallite dimension is more little, and the value of this critical stress intensity factors is big more, so its fracture toughness is high more.When quenching under being lower than room temperature, crystallite dimension is less, so toughness is increased.

For further improving the apparent brightness of plastic shell, can add phosphorus or nano material in alloy.This kind luminescent material can be zinc sulphide ZnS, cadmium selenide CdSe, cadmium sulfide CdS, europium-zinc silica Eu-ZnSiOx, europium-three ytterbium oxide Eu-YBO₃And the one or more combination of europium-barium magnesium aluminium oxide Eu-BaMgAlOx.

Claims (8)

1. surface treatment method, it is applied to plastic cement, it is characterized in that: this processing method is reduced to the glass transition temperature of plastic cement from the plastic cement melt temperature, under this glass transition temperature, carry out pressurize and handle, reduce to hardening heat from the glass transition temperature of plastic cement again, be heated to temperature by hardening heat then, be cooled to indoor temperature by temperature at last, wherein this hardening heat is lower 5 ℃-20 ℃ than indoor temperature, and this temperature is 80-100 ℃, and described plastic cement is that ABS adds glass fibre.

2. surface treatment method as claimed in claim 1 is characterized in that: this is 5 ℃/second-100 ℃/second from the speed range that the plexiglas inversion temperature drops to hardening heat.

3. surface treatment method as claimed in claim 2 is characterized in that: the speed range of reducing to hardening heat from the plexiglas inversion temperature is 20 ℃/second-50 ℃/second.

4. surface treatment method as claimed in claim 1 is characterized in that: described glass transition temperature from plastic cement keeps this hardening heat 10-20 second after reducing to hardening heat.

5. surface treatment method as claimed in claim 1 is characterized in that: the speed range that rises to temperature from hardening heat is 5 ℃/second-80 ℃/second.

6. surface treatment method as claimed in claim 5 is characterized in that: the speed range that rises to temperature from hardening heat is 20 ℃/second-50 ℃/second.

7. surface treatment method as claimed in claim 1 is characterized in that: the described time of carrying out the pressurize processing under glass transition temperature is 10 seconds.

8. surface treatment method as claimed in claim 1 is characterized in that: this processing method is filled the composition gas of one of nitrogen, argon gas, helium or argon gas, helium by ventilation technology.

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