阅读说明：本技术 一种防静电硅橡胶的合成工艺 (Synthesis process of anti-static silicone rubber ) 是由 任兆军 于 2020-07-08 设计创作，主要内容包括：本发明公开了一种防静电硅橡胶的合成工艺,包括以下步骤,S1,混炼,硅橡胶生胶比较柔软,具有一定的可塑性,可不经塑炼而直接采用开炼机或密炼机进行混炼呈硅橡胶,同时在混炼过程中加入防静电填料；S2,压延,利用压延机进行压延作业形成硅胶片,用于压延的硅橡胶胶料必须正确控制其返炼程度,最好在混炼机上先不充分返炼,以期在压延过程中获得足够返炼,可避免胶料在压延过程中因返炼过度而粘辊。本发明本防静电硅橡胶基底采用PL薄膜,使硅橡胶的导热更快,更均匀,且材料防静电,不会出现静电残留和静电击穿的不良,表面涂覆丙烯酸胶粘剂与防静电处理层,配合中层防静电填料处理,提高硅橡胶的防静电性能。(The invention discloses a synthetic process of antistatic silicone rubber, which comprises the following steps of S1, mixing, wherein raw silicone rubber is softer and has certain plasticity, and can be directly mixed into silicone rubber by an open mill or an internal mixer without plastication, and simultaneously, antistatic filler is added in the mixing process; and S2, calendering, wherein the silicone rubber sheet is formed by calendering with a calender, the degree of remilling of the silicone rubber compound for calendering must be correctly controlled, and the silicone rubber compound for calendering is preferably not remilled sufficiently on a mixing roll, so that sufficient remilling is obtained in the calendering process, and the phenomenon that the rubber compound is stuck to a roll due to over remilling in the calendering process can be avoided. The antistatic silicone rubber substrate adopts the PL film, so that the heat conduction of the silicone rubber is faster and more uniform, the material is antistatic, the defects of electrostatic residue and electrostatic breakdown are avoided, the acrylic adhesive and the antistatic treatment layer are coated on the surface, and the antistatic performance of the silicone rubber is improved by matching with the antistatic filler treatment of the middle layer.)

1. The synthesis process of the antistatic silicone rubber is characterized by comprising the following steps:

s1: mixing: the raw silicon rubber is softer and has certain plasticity, and can be directly mixed by an open mill or an internal mixer without plastication to form the silicon rubber, and simultaneously, the antistatic filler is added in the mixing process;

s2: rolling: the silicone rubber sheet is formed by calendering operation by using a calender, the degree of remilling of the silicone rubber material for calendering must be correctly controlled, and the silicone rubber material is optimally remilled insufficiently on a mixing roll firstly so as to obtain enough remilling in the calendering process, thereby preventing the rubber material from being stuck to a roll due to over remilling in the calendering process;

s3: and (3) vulcanization: the silicone rubber vulcanization process is not completed once, but is carried out in two stages: primary vulcanization: adding partial vulcanizing agent into the pressed and rolled silica gel sheet under pressurization or normal pressure for heating and shaping; post-vulcanization: vulcanizing at high temperature in an oven to further stabilize various physical properties of vulcanized rubber;

s4: gluing a substrate: the bottom substrate for gluing the vulcanized silicone rubber is a PL film, and the PL film is subjected to heat setting, namely the PL film is subjected to heat treatment forming for a short time under certain drafting, then is subjected to surface adhesive treatment, and then is glued;

s5: surface gluing: coating an acrylic acid adhesive and an anti-static treatment layer on the surface of the silicon rubber, and then carrying out hot pressing to enable the cementing layer of the anti-static silicon rubber to be more compact;

s6: trimming detection: and (3) trimming the antistatic silicone rubber with the PL film substrate, removing the edges, checking and detecting the performance of the antistatic silicone rubber.

2. The process for synthesizing an antistatic silicone rubber as claimed in claim 1, wherein the mixing time in S1 is 20-40min through an open mill and 6-16min through an internal mixer.

3. The process of claim 1, wherein the antistatic filler in S1 is at least one of carbon black, carbon fiber, carbon nanotube, graphene, metal particle, and their composite, and surfactant.

4. The process for synthesizing antistatic silicone rubber according to claim 1, wherein the vulcanizing agent in S3 is any one of DBPMH, BP and TBPB and DCBP.

5. The process as claimed in claim 1, wherein the temperature of the first vulcanization in the vulcanization process in S3 is 120-130 ℃, and the temperature of the post vulcanization is 230-235 ℃.

6. The process for synthesizing an antistatic silicone rubber as claimed in claim 1, wherein said surface adhesive in S4 is a mixed solution consisting of alkoxysilane, borate, vulcanizing agent and ethyl acetate or ethanol.

7. The process of claim 1, wherein the antistatic layer in S5 is prepared by blow molding low density polyethylene, linear low density polyethylene, antistatic masterbatch, color masterbatch and stabilizer.

Technical Field

The invention relates to the technical field of silicone rubber production, in particular to a synthesis process of antistatic silicone rubber.

Background

With the increasing application fields of antistatic requirements, especially the expansion of the application of electronic computers, the probability of static electricity generation is correspondingly increased, and the prevention meaning of people on static electricity is also increased, and the measures for static electricity resistance in many countries are increasingly standardized.

The antistatic silica gel product has the advantages that various antistatic devices are developed finally, so that the antistatic silica gel product can be seen from people and widely applied to various industries, the antistatic silica gel plays a role in removing static electricity and can prevent click accidents caused by leakage of low-voltage lines, antistatic liquid with the same property as the silica gel can be added or wiped on the surface in the production process if conditions exist (the antistatic time is longer), an antistatic agent can be added in the production process, the effect is better, if a produced finished product is produced, the antistatic liquid can be wiped on the surface of a sucker, and the time can be maintained for about half a year and can be declined.

The existing silicone rubber is only simply added with filler to change the antistatic effect, the durability and the electrostatic treatment on the integral electrostatic aggregation surface are not enhanced, so that the deterioration is aggravated, and the integral silicone rubber quality is influenced.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a synthesis process of antistatic silicone rubber.

The invention provides a synthesis process of antistatic silicone rubber, which comprises the following steps:

s1: mixing: the raw silicon rubber is softer and has certain plasticity, and can be directly mixed by an open mill or an internal mixer without plastication to form the silicon rubber, and simultaneously, the antistatic filler is added in the mixing process;

s2: rolling: the silicone rubber sheet is formed by calendering operation by using a calender, the degree of remilling of the silicone rubber material for calendering must be correctly controlled, and the silicone rubber material is optimally remilled insufficiently on a mixing roll firstly so as to obtain enough remilling in the calendering process, thereby preventing the rubber material from being stuck to a roll due to over remilling in the calendering process;

s3: and (3) vulcanization: the silicone rubber vulcanization process is not completed once, but is carried out in two stages: primary vulcanization: adding partial vulcanizing agent into the pressed and rolled silica gel sheet under pressurization or normal pressure for heating and shaping; post-vulcanization: vulcanizing at high temperature in an oven to further stabilize various physical properties of vulcanized rubber;

s4: gluing a substrate: the bottom substrate for gluing the vulcanized silicone rubber is a PL film, and the PL film is subjected to heat setting, namely the PL film is subjected to heat treatment forming for a short time under certain drafting, then is subjected to surface adhesive treatment, and then is glued;

s5: surface gluing: coating an acrylic acid adhesive and an anti-static treatment layer on the surface of the silicon rubber, and then carrying out hot pressing to enable the cementing layer of the anti-static silicon rubber to be more compact;

s6: trimming detection: and (3) trimming the antistatic silicone rubber with the PL film substrate, removing the edges, checking and detecting the performance of the antistatic silicone rubber.

Preferably, the mixing time of the S1 through an open mill is 20-40min, and the mixing time through an internal mixer is 6-16min.

Preferably, the antistatic filler in S1 is at least one of carbon black, carbon fiber, carbon nanotube, graphene, metal particle and their composite, and surfactant.

Preferably, the vulcanizing agent in S3 is any one of DBPMH, BP and TBPB and DCBP.

Preferably, in the vulcanization process in S3, the temperature of the primary vulcanization is 120-130 ℃, and the temperature of the post vulcanization is 230-235 ℃.

Preferably, the surface adhesive in S4 is a mixed solution composed of alkoxysilane, borate, vulcanizing agent, and ethyl acetate or ethanol.

Preferably, the antistatic treatment layer in S5 is formed by blow molding of low density polyethylene, linear low density polyethylene, antistatic master batch, color master batch and stabilizer mixture.

The beneficial effects of the invention are as follows:

1. the antistatic silicon rubber substrate adopts the PL film, so that the heat conduction of the silicon rubber is faster and more uniform, the material is antistatic, and the defects of electrostatic residue and electrostatic breakdown are avoided; the pressing times are 60-80 times, the time for feeding and discharging is reduced, the productivity is increased, no silicone oil is separated out, and the UV adhesive edge sealing in some applications is not influenced;

2. wherein the total amount of the added antistatic filler is controlled, 5-7% of the total mass is added in summer to make the volume resistance of the antistatic filler less than 109 omega-cm, 6-8% of the total mass is added in winter to make the volume resistance of the antistatic filler less than 109 omega-cm, and carbon black, carbon fiber, carbon nano tube, graphene, metal particles, composites of the carbon black, the carbon nano tube and the graphene, and various surfactants are used in a matching way;

3. the surface is coated with an acrylic adhesive and an anti-static treatment layer, so that both sides of the surface have good anti-static treatment, and the anti-static filler treatment of the middle layer is matched, so that the anti-static performance of the whole silicon rubber is improved.

Drawings

Fig. 1 is a process flow diagram of a synthesis process of an antistatic silicone rubber provided by the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1, the synthesis process of the antistatic silicone rubber comprises the following steps:

s1: mixing: the raw silicon rubber is softer and has certain plasticity, and can be directly mixed by an open mill or an internal mixer without plastication to form the silicon rubber, and simultaneously, the antistatic filler is added in the mixing process;

s2: rolling: the silicone rubber sheet is formed by calendering operation by using a calender, the degree of remilling of the silicone rubber material for calendering must be correctly controlled, and the silicone rubber material is optimally remilled insufficiently on a mixing roll firstly so as to obtain enough remilling in the calendering process, thereby preventing the rubber material from being stuck to a roll due to over remilling in the calendering process;

s3: and (3) vulcanization: the silicone rubber vulcanization process is not completed once, but is carried out in two stages: primary vulcanization: adding partial vulcanizing agent into the pressed and rolled silica gel sheet under pressurization or normal pressure for heating and shaping; post-vulcanization: vulcanizing at high temperature in an oven to further stabilize various physical properties of vulcanized rubber;

s4: gluing a substrate: the bottom substrate for gluing the vulcanized silicone rubber is a PL film, and the PL film is subjected to heat setting, namely the PL film is subjected to heat treatment forming for a short time under certain drafting, then is subjected to surface adhesive treatment, and then is glued;

s5: surface gluing: coating an acrylic acid adhesive and an anti-static treatment layer on the surface of the silicon rubber, and then carrying out hot pressing to enable the cementing layer of the anti-static silicon rubber to be more compact;

s6: trimming detection: and (3) trimming the antistatic silicone rubber with the PL film substrate, removing the edges, checking and detecting the performance of the antistatic silicone rubber.

In the invention, the expansion of part of contents is specifically as follows:

1. mixing in open mill

The roller speed ratio of the two-roller open mill is (1.2-1.4): 1, fast roll after, higher speed ratio results in faster mixing, and low speed ratio results in smooth film. The roller must be filled with cooling water, and the mixing temperature is preferably below 40 ℃ to prevent scorching or volatilization loss of vulcanizing agent. The roll gap is small (1-5 mm) at the beginning of mixing, and then gradually increased.

The feeding and operation sequence is as follows: raw rubber (wrapping roll), reinforcing filler, structure control agent, heat-resistant assistant, coloring agent, thinly passing for 5 times, blanking, oven heat treatment, remixing, vulcanizing agent, thinly passing, standing overnight, remixing and sheet discharging.

The sizing material can also be subjected to heat treatment without an oven, after the heat-resistant auxiliary agent is added, the vulcanizing agent is added and then the sizing material is passed through thinly, placed overnight for remilling, and then placed for several days for remilling and sheet discharging for use. The mixing time is 20-40min.

When the silicone rubber is added into a rubber mixing mill, a slow roller (front roller) is coated, when the silicone rubber is mixed, a fast roller (back roller) is coated, and when the silicone rubber is mixed, the silicone rubber must be capable of being operated on two sides. Because the silicon rubber material is softer, the silicon rubber material can be operated by a common putty knife during mixing, and the thin sheet can not be pulled down like common rubber but scraped by a steel, nylon or wear-resistant plastic scraper.

In order to facilitate cleaning and prevent lubricating oil from leaking into the glue, a movable rubber plate is adopted. The fumed silica is easy to fly and harmful to human body, and corresponding protective measures should be taken. If the powder peroxide is used directly in the mixing, measures for preventing explosion are necessary, and it is preferable to use the paste peroxide.

2. Mixing in a Banbury mixer

When the mixture is mixed by a laboratory 2L internal mixer, the mixing time is 6-16min. When the charging factor is 0.74, the mixing can be normally carried out by using a mill mixer with a diameter of 160 mm. The discharge temperature is related to the type of the reinforcing filler, and when the weak reinforcing filler and the precipitated silica are adopted, the discharge temperature is below 50 ℃; when the fumed silica is used, the binder removal temperature is about 70 ℃.

Placing and back-smelting the rubber material: after the silicon rubber and the rubber are mixed, the standing time is not less than 24 hours, so that various compounding agents (particularly structure control agents) can fully act with the raw rubber. After standing, the rubber becomes hard, the plasticity value is reduced, and the rubber must be remilled before use. The back-mixing adopts an open mill, the roller spacing is larger (3-5 mm) at the beginning, the rubber material is harder at the moment, the surface is in a wrinkle shape, and the rubber material is wrapped on a front roller. The rubber material gradually becomes soft along with the prolonging of the back-refining time; the roll gap (0.25-0.5 mm) is slowly reduced, and the sizing material is quickly wrapped on the back roll. And discharging the sheets after the sizing material is softened and the surface is smooth and flat. The back refining is insufficient, and the surface of the film has wrinkles; when the back-refining is excessive, the rubber becomes sticky and sticks to the roll. The remill temperature is generally controlled at room temperature.

Extruding: silicone rubbers are generally softer, have better extrusion results, are easy to handle, and can be extruded into various products of different shapes and sizes, and the processing equipment and tools thereof are basically similar to those of ordinary rubbers.

The machine is discharged by a single-thread screw with the diameter of 30 mm or 65mm, and the length-diameter ratio is (10-12): 1 the effect is better. The temperature is kept as low as possible during extrusion, preferably not higher than 40 ℃, so that cooling water is required to be introduced into both the cylinder and the screw. A80-140 mesh filter screen can be additionally arranged near the head part of a product with higher quality requirement to remove impurities in the rubber material and improve the extrusion quality.

The silicone rubber extrusion preforms are soft and easily deformable, and must therefore be immediately vulcanized. The most common method is hot air continuous vulcanization; the wire and cable industry typically uses high pressure steam continuous vulcanization. If continuous vulcanization is not possible after extrusion, in order to prevent deformation, a disc, a drum or a conveyer belt is used for taking immediately after extrusion, and talcum powder is used for isolating so as to prevent mutual adhesion. If the compound is found to be too soft for extrusion, 3 to 5 parts fumed silica may be further blended into the compound.

The dosage of the vulcanizing agent of the rubber compound formula for extrusion is properly increased compared with that of a molded product, the extrusion speed of the silicon rubber is lower than that of other rubbers, and when the same extrusion speed as that of other rubbers is required, the higher screw rotation speed is adopted.

Rolling: the calender generally adopts a vertical three-roller calender. When the intermediate roller is used for producing films, the intermediate roller is fixed, the rotating speed of the intermediate roller is faster than that of the upper roller, and the speed ratio is (1.1-1.4): 1, the rotating speed of the lower roller is the same as that of the middle roller. When the calender is started, the upper roller is at 50 deg.C, the middle roller is kept at room temperature, and the lower roller is cooled by cooling water. The rolling speed is generally 60-7500px min-1, which is not suitable for too fast, the roll spacing (middle and lower rolls) is firstly adjusted at low speed to ensure a certain rolling thickness, and then the rolling speed is increased to normal speed for continuous operation.

When the three-roll calender is used for adhering and wiping silicon rubber, the PL film replaces a cloth liner (polyester film) to pass between the middle roll and the lower roll. The three-roller calender is only suitable for single-side glue coating, and a four-roller calender is adopted in long-term production.

The rubber material used for calendering must be accurately controlled in the degree of back-refining, and the rubber material is preferably not fully back-refined on a rubber refining machine in order to obtain enough back-refining in the calendering process, so that the roller sticking of the rubber material due to over back-refining in the calendering process can be avoided. The formula of the sizing material also has certain influence on calendering, and the sizing material adopting the reinforcing filler has better calendering process performance.

After the PL film is pretreated, the surface of the PL film is treated by a surface adhesive, and then the PL film can be coated with glue. The adhesive is a solution composed of alkoxysilane, borate, a vulcanizing agent and a solvent (ethyl acetate or ethanol).

The PL film is treated with adhesive, and the adhesive is painted homogeneously onto the PL film in a gumming machine, and then dried and vulcanized.

The vulcanization is generally carried out in two stages, one at 120-130 ℃ and the other at 230 ℃. The thickness of the coating can be controlled by changing the viscosity of the glue solution or adjusting the speed of the PL film passing through the glue coating slot.

And (3) vulcanizing the molded product: press vulcanization, transfer molding vulcanization and injection molding vulcanization can be employed.

When the silicon rubber product is vulcanized by flat plate, a release agent is not generally used, and the silicon rubber product is rapidly charged, matched with a mold and pressurized, otherwise the silicon rubber product is easy to scorch, and particularly the silicon rubber product contains rubber compounds containing vulcanizing agents BP and DCBP.

Transfer molding vulcanization is a widely used process for processing silicone rubber compounds, and compared with plate vulcanization with a single hole per mold, the transfer molding vulcanization has the advantages of short processing period and capability of vulcanizing complicated rubber parts, particularly rubber parts with inserts and pins. Compared with injection vulcanization, the equipment cost is lower. The injection-molded vulcanized product can improve the labor productivity and reduce the labor intensity, and simultaneously can reduce the consumption of peroxide, improve the tear resistance and the compression permanent deformation of the product, but has larger shrinkage rate.

Vulcanization of the extruded article. The method can adopt steam pressure vulcanization, hot air continuous vulcanization, liquid vulcanization tank continuous vulcanization, drum vulcanization, radiation vulcanization and the like. The first 3 methods are more commonly used.

Two stage vulcanization

After the silicone rubber product is subjected to one-stage vulcanization, some low molecular substances exist in the vulcanized rubber to influence the product performance, for example, a compound using a general-purpose vulcanizing agent (such as a vulcanizing agent BP or DCBP) is subjected to one-stage vulcanization, and the acidic substance amount decomposed by the vulcanizing agent increases the porosity of the sponge pores and reduces the density.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.