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I. Process points
1. Surface treatment of base film
Other additives, especially emulsifiers, on the surface of the protective film with the performance of the adhesive will also have a significant impact. Domestic experts with semi-continuous pre-emulsified seed emulsion poly method, the synthesis of protective film with emulsion type sensitive adhesive, and the study of the amount of emulsifier in the bottom phase seed emulsion and the amount of multifunctional aziridine type cross-linking agent, the effect of emulsion type sensitive adhesive performance, the results show that: with the increase in the amount of emulsifier in the seed emulsion, the particle size of the emulsion particles decreased, the emulsion viscosity, surface tension and contact angle increased; increase The amount of cross-linking agent can significantly improve the aging resistance of emulsion-type pressure-sensitive adhesives. Compared with temperature, the influence of humidity on the aging resistance of emulsion pressure-sensitive adhesives is more significant. The polarity and finish of the surface of the protected material also have a significant effect on the aging resistance of pressure-sensitive adhesives.
Domestic experts prepared acrylate emulsions of pressure-sensitive adhesives using the pre-emulsification method and explored the effects of different emulsifier systems on the physical properties of pressure-sensitive adhesives. Infrared spectroscopy tests showed that reactive emulsifiers were involved in the reaction, while transmission electron microscopy tests showed that the emulsions obtained from reactive emulsifier systems had small particle size and uniform distribution. The experimental results showed that when w(compound emulsifier) = 3%,m(ANPE010):m(DNS-458):m(DNS-501) = 1.5:1.1:0.4, the mass fraction of solid fraction of the resulting emulsion was 48.03%, the monomer conversion rate reached 97.66%, the emulsion viscosity was 38.8s, the average particle size was 238nm, the initial viscosity of the pressure-sensitive adhesive The initial adhesive force of pressure-sensitive adhesive can absorb No.8 steel ball, and the adhesion is more than 24h; the peeling strength of 180¡ã reaches 0.304N/mm. The protective film attached to the surface of stainless steel, after baking at 80¡æ for 24h, there is no residual adhesive and fog shadow on the surface of stainless steel. Domestic experts to ethyl acetate as the solvent, azo diisobutyronitrile as the initiator, using a solution polymerization process, the development of surface protection film with acrylate pressure-sensitive adhesive, and the study of the internal crosslinker TC, external crosslinker aziridine (SaC-100) and water-based polyiso (Bayhydur3100) on the adhesive peel strength and heat resistance. The results showed that by introducing internal and external cross-linking agents, the cohesive force of the adhesive could be significantly increased and the effect of eliminating residual adhesive was obvious.
The external cross-linking agent SaC-100,was more effective than Bayhydur3100 in improving the heat resistance of the colloid and reducing the peel strength; the surface protection film made by using the internal cross-linking agent TC with 0.80% of the monomer amount and the external cross-linking agent SaC-100 with 1.0% of the colloid amount had better performance, and in the heat resistance test of high gloss stainless steel plate, there was no residual glue and "dark shadow". When using polyethylene, polypropylene film and other non-polar films as the base film of the surface protection film, due to the low surface tension of such films, it is not easy for the pressure-sensitive adhesive solution (or emulsion) wetting, after coating pressure-sensitive adhesive, the adhesion between the substrate and pressure-sensitive adhesive (sticky base force) is also low, usually the surface treatment must be applied to the adhesive surface of the substrate, so that its surface tension is more than 38N / m. The surface treatment of the substrate film can theoretically be done by chemical treatment, corona treatment, ozone exposure treatment, UV irradiation treatment, flame treatment, plasma treatment, etc. However, the practical industrial application is generally the corona treatment method which is easy to implement, inexpensive and effective. When the base film is treated by corona, the oxidation reaction can give the polar groups on the surface of the base film and stratify the surface, which can obviously increase the surface tension and improve the sticky base force.
2. Primer application
Apply the primer refers to the coating adhesive before, first in the substrate glue surface, pre-coating a layer to improve the surface protection film pressure-sensitive adhesive layer and the adhesion between the substrate coating (primer layer). Commonly used primers are: chlorinated polypropylene, oxidized polyethylene, cellulose derivatives, epoxy resins, polyamide resins, water-soluble melamine resins, organic titanium compounds, etc. The role of similar to a bridge between the substrate and the strand adhesive, through this bridge, the substrate and adhesive firmly connected.
3. Stabilization of peeling force
If the surface protection film is not stabilized by peel force, after it is applied to the surface of the protected material, the peel force often increases with time, and the surface protection film cannot be removed smoothly when the film is needed for a long time.
After the stabilization of peel force, the peel force of the surface protection film will not increase with the growth of the laminating time (or the peel force will be controlled within a certain range), so that the surface protection film can be easily peeled off from the surface of the protected object during use, and the surface will be kept clean and free of residual pressure sensitive adhesive after the film is peeled off from the surface of the protected object. Examples of stabilization methods for peeling force are as follows.
(1) Stretching treatment of surface protection film
It is said that in the manufacture of surface protection film, after the substrate is coated and dried, a two-way stretching process is carried out before winding, so that the resulting protective film has a 30% shrinkage rate in the longitudinal and transverse directions when heated at 100¡ãC for 10 min. The internal stress that exists when the protective film is thermally shrunk can offset the increase in peel force caused by factors such as temperature and time after the surface protection film is applied to the surface of the protected object, thus improving the stability of the peel force of the surface protection film. The stability of the peeling force of the protective film.
(2) Addition of surfactant
Adding surfactants can help improve the stability of peeling force of surface protection film, such as adding appropriate amount of phosphate ester and its derivatives of surfactants, amine surfactants, silicone compounds [such as silicone (polysiloxane) oil, vinyl silane] to the adhesive. However, it should be noted that when the surface protection film is used at higher temperature, the above additives have the tendency to migrate from the adhesive to the surface and precipitate out, so it should be considered to use perfluoroalkyl surfactants, such as perfluoroalkyl carboxylate, perfluoroalkyl phosphate, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl trimethyl ammonium ethylene lactone, etc. The mechanism of action is that a low-energy layer is formed at the interface between the protected material and the protective film adhesive layer, which inhibits the growth of peeling force. Polyalkyl glycol fatty acid esters, such as polyethylene glycol stearate, polyethylene glycol oleate, etc., can also be added. Their effect is to form a continuous or discontinuous non-adhesive film between the adhesive and the protected material; thus preventing the rise of the peeling force, and the area of the film gradually increases with the increase of placement time until it reaches a constant value.
(3) Moderate cross-linking of pressure-sensitive adhesives
Cross-linking agent is added to the pressure-sensitive adhesive before coating or in the process of making adhesive to improve the cohesive strength by moderate cross-linking between molecules and suppress the increase of peeling force with time.
Nanjing Sumino Precision Machinery Co., Ltd. has professional cast film production lines. Our main cast film manufacturing lines are: TPU hot melt adhesive film production line, CPP/CPE cast film production line, EVA solar encapsulation adhesive film production line, PE sanitary breathable film production line, PVDF cast film production line, PP three-dimensional film production line, medical blood purification film production line, multi-layer co-extrusion barrier film production line, LLDPE winding film production line, etc.
1. Surface treatment of base film
Other additives, especially emulsifiers, on the surface of the protective film with the performance of the adhesive will also have a significant impact. Domestic experts with semi-continuous pre-emulsified seed emulsion poly method, the synthesis of protective film with emulsion type sensitive adhesive, and the study of the amount of emulsifier in the bottom phase seed emulsion and the amount of multifunctional aziridine type cross-linking agent, the effect of emulsion type sensitive adhesive performance, the results show that: with the increase in the amount of emulsifier in the seed emulsion, the particle size of the emulsion particles decreased, the emulsion viscosity, surface tension and contact angle increased; increase The amount of cross-linking agent can significantly improve the aging resistance of emulsion-type pressure-sensitive adhesives. Compared with temperature, the influence of humidity on the aging resistance of emulsion pressure-sensitive adhesives is more significant. The polarity and finish of the surface of the protected material also have a significant effect on the aging resistance of pressure-sensitive adhesives.
Domestic experts prepared acrylate emulsions of pressure-sensitive adhesives using the pre-emulsification method and explored the effects of different emulsifier systems on the physical properties of pressure-sensitive adhesives. Infrared spectroscopy tests showed that reactive emulsifiers were involved in the reaction, while transmission electron microscopy tests showed that the emulsions obtained from reactive emulsifier systems had small particle size and uniform distribution. The experimental results showed that when w(compound emulsifier) = 3%,m(ANPE010):m(DNS-458):m(DNS-501) = 1.5:1.1:0.4, the mass fraction of solid fraction of the resulting emulsion was 48.03%, the monomer conversion rate reached 97.66%, the emulsion viscosity was 38.8s, the average particle size was 238nm, the initial viscosity of the pressure-sensitive adhesive The initial adhesive force of pressure-sensitive adhesive can absorb No.8 steel ball, and the adhesion is more than 24h; the peeling strength of 180¡ã reaches 0.304N/mm. The protective film attached to the surface of stainless steel, after baking at 80¡æ for 24h, there is no residual adhesive and fog shadow on the surface of stainless steel. Domestic experts to ethyl acetate as the solvent, azo diisobutyronitrile as the initiator, using a solution polymerization process, the development of surface protection film with acrylate pressure-sensitive adhesive, and the study of the internal crosslinker TC, external crosslinker aziridine (SaC-100) and water-based polyiso (Bayhydur3100) on the adhesive peel strength and heat resistance. The results showed that by introducing internal and external cross-linking agents, the cohesive force of the adhesive could be significantly increased and the effect of eliminating residual adhesive was obvious.
The external cross-linking agent SaC-100,was more effective than Bayhydur3100 in improving the heat resistance of the colloid and reducing the peel strength; the surface protection film made by using the internal cross-linking agent TC with 0.80% of the monomer amount and the external cross-linking agent SaC-100 with 1.0% of the colloid amount had better performance, and in the heat resistance test of high gloss stainless steel plate, there was no residual glue and "dark shadow". When using polyethylene, polypropylene film and other non-polar films as the base film of the surface protection film, due to the low surface tension of such films, it is not easy for the pressure-sensitive adhesive solution (or emulsion) wetting, after coating pressure-sensitive adhesive, the adhesion between the substrate and pressure-sensitive adhesive (sticky base force) is also low, usually the surface treatment must be applied to the adhesive surface of the substrate, so that its surface tension is more than 38N / m. The surface treatment of the substrate film can theoretically be done by chemical treatment, corona treatment, ozone exposure treatment, UV irradiation treatment, flame treatment, plasma treatment, etc. However, the practical industrial application is generally the corona treatment method which is easy to implement, inexpensive and effective. When the base film is treated by corona, the oxidation reaction can give the polar groups on the surface of the base film and stratify the surface, which can obviously increase the surface tension and improve the sticky base force.
2. Primer application
Apply the primer refers to the coating adhesive before, first in the substrate glue surface, pre-coating a layer to improve the surface protection film pressure-sensitive adhesive layer and the adhesion between the substrate coating (primer layer). Commonly used primers are: chlorinated polypropylene, oxidized polyethylene, cellulose derivatives, epoxy resins, polyamide resins, water-soluble melamine resins, organic titanium compounds, etc. The role of similar to a bridge between the substrate and the strand adhesive, through this bridge, the substrate and adhesive firmly connected.
3. Stabilization of peeling force
If the surface protection film is not stabilized by peel force, after it is applied to the surface of the protected material, the peel force often increases with time, and the surface protection film cannot be removed smoothly when the film is needed for a long time.
After the stabilization of peel force, the peel force of the surface protection film will not increase with the growth of the laminating time (or the peel force will be controlled within a certain range), so that the surface protection film can be easily peeled off from the surface of the protected object during use, and the surface will be kept clean and free of residual pressure sensitive adhesive after the film is peeled off from the surface of the protected object. Examples of stabilization methods for peeling force are as follows.
(1) Stretching treatment of surface protection film
It is said that in the manufacture of surface protection film, after the substrate is coated and dried, a two-way stretching process is carried out before winding, so that the resulting protective film has a 30% shrinkage rate in the longitudinal and transverse directions when heated at 100¡ãC for 10 min. The internal stress that exists when the protective film is thermally shrunk can offset the increase in peel force caused by factors such as temperature and time after the surface protection film is applied to the surface of the protected object, thus improving the stability of the peel force of the surface protection film. The stability of the peeling force of the protective film.
(2) Addition of surfactant
Adding surfactants can help improve the stability of peeling force of surface protection film, such as adding appropriate amount of phosphate ester and its derivatives of surfactants, amine surfactants, silicone compounds [such as silicone (polysiloxane) oil, vinyl silane] to the adhesive. However, it should be noted that when the surface protection film is used at higher temperature, the above additives have the tendency to migrate from the adhesive to the surface and precipitate out, so it should be considered to use perfluoroalkyl surfactants, such as perfluoroalkyl carboxylate, perfluoroalkyl phosphate, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl trimethyl ammonium ethylene lactone, etc. The mechanism of action is that a low-energy layer is formed at the interface between the protected material and the protective film adhesive layer, which inhibits the growth of peeling force. Polyalkyl glycol fatty acid esters, such as polyethylene glycol stearate, polyethylene glycol oleate, etc., can also be added. Their effect is to form a continuous or discontinuous non-adhesive film between the adhesive and the protected material; thus preventing the rise of the peeling force, and the area of the film gradually increases with the increase of placement time until it reaches a constant value.
(3) Moderate cross-linking of pressure-sensitive adhesives
Cross-linking agent is added to the pressure-sensitive adhesive before coating or in the process of making adhesive to improve the cohesive strength by moderate cross-linking between molecules and suppress the increase of peeling force with time.
Nanjing Sumino Precision Machinery Co., Ltd. has professional cast film production lines. Our main cast film manufacturing lines are: TPU hot melt adhesive film production line, CPP/CPE cast film production line, EVA solar encapsulation adhesive film production line, PE sanitary breathable film production line, PVDF cast film production line, PP three-dimensional film production line, medical blood purification film production line, multi-layer co-extrusion barrier film production line, LLDPE winding film production line, etc.