CN116198095A

CN116198095A - Photosensitive dry film protective film preparation method

Info

Publication number: CN116198095A
Application number: CN202310177170.6A
Authority: CN
Inventors: 关启锐; 方建权; 钟健常; 张逢辉
Original assignee: Ld Packaging Co ltd
Current assignee: Ld Packaging Co ltd
Priority date: 2023-02-28
Filing date: 2023-02-28
Publication date: 2023-06-02

Abstract

The invention provides a preparation method of a photosensitive dry film protective film, which comprises the steps of transferring LDPE particles with low crystal points to a feed end positioned at the outer side of a clean workshop with a thousand-level clean level; carrying out electrostatic dust removal on LDPE particles with low crystal points put into a feed inlet by using dust removal equipment containing a high-speed ion fan; processing and film-making the material by using high-precision co-extrusion film-blowing equipment positioned in a clean workshop with a thousand-level clean level; trimming and edge-separating the film body; using a high-speed camera to check surface defects of the film; and (3) applying an adhesive to the tube core to adhere the film body, and rolling the film body. According to the preparation method of the photosensitive dry film protective film, the prepared protective film has the advantages of few crystal points, few impurity particles, uniform thickness at each part, few folds, embossing and micropores and good rolling quality.

Description

Photosensitive dry film protective film preparation method

Technical Field

The invention relates to the field of photosensitive dry film protective film materials, in particular to a preparation method of a photosensitive dry film protective film.

Background

The process of the printed circuit board is that a photosensitive film is stuck on the circuit board, ultraviolet light with specific lines irradiates a specific position of the circuit board, the irradiated photosensitive film is subjected to polymerization reaction, then a cleaning solvent A is used for spraying the circuit board, the photosensitive film which is not irradiated by the ultraviolet light is washed off, then etching liquid is used for etching copper which is not covered by the photosensitive film, finally a cleaning solvent B is used for spraying the circuit board to wash off the photosensitive film on the circuit board, therefore, the condition of the photosensitive film is critical to the etching effect (the thickness of the photosensitive film at the position is changed due to the fact that the wrinkling or abrasion of the photosensitive film occurs, the degree of polymerization reaction after the photosensitive film is irradiated by the ultraviolet light is different from that of the other positions, and the subsequent protective effect on the copper material is different), so that the photosensitive film is prevented from being deformed and damaged in the moving process of production, transportation and the like, and the photosensitive dry film protection film is covered on the inner side and outer side of the photosensitive film.

The crystal point level and the clean level of the photosensitive dry film protective film can greatly influence the quality of the photosensitive dry film, when crystal points and impurities exist in the photosensitive dry film protective film, the bulges of the crystal points and the impurities can be embedded into the photosensitive film, so that the thickness of the photosensitive film is thinned or even lost. Chinese patent No. CN112888738A discloses a scheme of blending LDPE and LLDPE to form a protective film, in which the protective film is formed with a small number of micropores, but the internal structure of the protective film is prone to occurrence of unmelted crystal points due to uneven mixing of the blending materials; chinese patent No. CN109383044a discloses that the protective film is produced by using a casting method, and the number of crystal points of the produced protective film is small, but thickness accumulation (uneven thickness at different positions of the protective film) is easily caused in part of the protective film due to limited swing amplitude of the swing frame in the production process of the casting method. Therefore, there is a need for a method for preparing a photosensitive dry film protective film, which can prepare a protective film with few crystal points and few impurities, and can reduce the problems of thickness accumulation, wrinkles, embossing, micropores and the like of the protective film.

Disclosure of Invention

The invention aims to overcome the defects that the photosensitive dry film protective film prepared by the existing protective film preparation process has many crystal points and many impurity particles, and has the problems of thickness accumulation, wrinkles, embossing, micropores and the like, and provides a preparation method of the photosensitive dry film protective film.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

the preparation method of the photosensitive dry film protective film comprises the following steps:

transferring materials: transferring low-crystal-point LDPE particles to a feeding end positioned outside a clean workshop with a thousand-level clean level;

pretreatment of materials: carrying out electrostatic dust removal on LDPE particles with low crystal points put into a feed inlet by using dust removal equipment containing a high-speed ion fan;

and (3) film preparation: processing and film-making the material by using high-precision co-extrusion film-blowing equipment positioned in a clean workshop with a thousand-level clean level;

cutting: trimming and edge-separating the film body;

and (3) detection: using a high-speed camera to check surface defects of the film;

and (3) rolling: and (3) applying an adhesive to the tube core to adhere the film body, and rolling the film body.

Compared with the prior art, the preparation method of the photosensitive dry film protective film has the following beneficial effects:

(1) The photosensitive dry film protective film preparation method starts to improve the quality of the protective film in five aspects of raw material selection, raw material treatment, production equipment, processing technology and production environment, wherein the method comprises the steps of selecting low-crystal-point LDPE (low density) to reduce the probability of crystal points of the raw material in the processing process caused by self reasons, carrying out electrostatic dust removal on the materials, avoiding crystal points generated in subsequent processing caused by mixing impurities into the raw material, reducing the problems of thickness accumulation, wrinkles, imprinting, micropores and the like of a finished product of the protective film by using high-precision coextrusion film blowing equipment and matching with a specific processing technology, and meanwhile, producing the protective film in a clean workshop with thousands of clean levels, taking into consideration the extremely high requirement of the cleanliness of the protective film on the production environment, and avoiding the impurities in a production field from entering the materials;

(2) The PE resin with common grade is used, the areas with high molecular weight are more (the melting point of the areas with high molecular weight is higher), and unmelted crystal points are easy to appear after a film is produced by using a film blowing device;

(3) During transportation and production processes of low-crystal-point LDPE, friction exists between particles in materials and between the particles and production equipment, so that fine scraps, powder and floccules are generated and attached to the surfaces of the particles of the materials, if the fine scraps, the powder and the floccules enter a processing link together with the particles of the materials, the difference of melting speeds of different parts of the low-crystal-point LDPE in a molten state is caused, and the occurrence of unmelted crystal points or oxidized crystal points is easily caused; in addition, if external dust and foreign matters adhere to the surfaces of the material particles and enter a processing link along with the material particles, impurity crystal points can be formed in the low-crystal-point LDPE in a molten state; according to the invention, the low-crystal-point LDPE particles are subjected to electrostatic dust removal, so that fine scraps, powder, wadding strips, dust and foreign matters on the surfaces of the material particles are removed, the impurities are prevented from entering a link to be processed, and the occurrence probability of crystal points is reduced; the invention uses a high-speed ion fan in the electrostatic dust removal process of materials, and aims to eliminate static electricity on the surfaces of LDPE particles with low crystal points by utilizing the air flow output by the high-speed ion fan so that impurities cannot be adsorbed on the particles, and the impurities are blown away by the air flow to separate the impurities from the material particles, thereby improving the cleanliness of the materials.

Further, the LDPE particles with low crystal point contain an antioxidant, and the antioxidant content is 200-400ppm.

In order to facilitate processing, storage and use of the PE material, delay the aging speed of PE and reduce the occurrence of oxidation crystal points, an antioxidant is required to be added into the PE material, but because the photosensitive dry film has UV sensitivity, if the antioxidant content on the protective film is more than 500ppm, the antioxidant on the protective film can be attached to the photosensitive dry film, so that free radicals generated by the photosensitive dry film are captured, and the photosensitive dry film cannot be caused to react by using a preset ultraviolet irradiation amount in the process of a printed circuit board; the invention controls the antioxidant content of LDPE with low crystal point to 200-400ppm, thereby avoiding the oxidation crystal point and product oxidation of the protective film in the process of processing and producing, and simultaneously avoiding the influence of excessive antioxidants on the normal use of the photosensitive dry film.

Further, in the high-precision co-extrusion film blowing equipment, a feeding pipeline is arranged between the discharging lower end of the dust removing equipment containing the high-speed ion fan and the discharging hopper, and a Teflon coating is coated on the inner side of the feeding pipeline.

After the inner side of the feeding pipeline is coated with the Teflon coating, the smoothness of the feeding pipeline is improved, and the phenomenon that new fine scraps, powder, flocculation strips and the like are generated on the material particles due to the fact that the material particles are rubbed with the inner wall of the feeding pipeline rapidly in the material sucking process of the high-precision co-extrusion film blowing equipment can be reduced, so that the phenomenon that new impurities enter the high-precision co-extrusion film blowing equipment to cause crystal points on a protective film in the processing process is avoided.

Further, a connecting pipeline is arranged between the discharging hopper of the high-precision co-extrusion film blowing device and the extruder, nitrogen is introduced into the connecting pipeline to form a positive pressure environment, the flow rate of the nitrogen is 5-25NL/min, and the purity of the nitrogen is more than 99%.

The invention creatively arranges a connecting pipeline between a blanking hopper and an extrusion mechanism of the high-precision co-extrusion film blowing equipment, and introduces nitrogen into the connecting pipeline to form a positive pressure environment; in the process of manufacturing the protective film, high-purity nitrogen is used as protective gas, and a positive pressure environment is formed in a feeding area of the high-precision co-extrusion film blowing equipment, so that air in the feeding area is discharged and blocked outside the high-precision co-extrusion film blowing equipment, and oxygen is prevented from entering a processing area of the high-precision co-extrusion film blowing equipment along with material particles, so that oxidized crystal points are generated.

Further, an extruding mechanism of the high-precision co-extrusion film blowing equipment adopts a machine barrel with a groove at a feeding section, a screw rod of the extruder is a barrier screw rod, and a madok mixing head is arranged in the screw rod.

The setting mode has the following beneficial effects:

(1) The materials are heated and melted in the extrusion mechanism and extruded into finished products, so that the structure of the extrusion mechanism and the extrusion process involved in the structure have important influence on the quality of the protective film, the feeding section of the machine barrel with the grooves can be used for increasing the shearing heat of the extrusion mechanism, realizing the uniform melting of the materials at different positions, reducing the provision of additional heating outside the machine barrel, enabling the materials to be extruded at a lower heating temperature, reducing the generation of oxidized crystal points, and simultaneously improving the back pressure of the extrusion mechanism, and enabling the materials to be stably extruded (the extruded materials are stable in size);

(2) The barrier type screw rod is selected, compared with a common single screw rod, the barrier type screw rod not only can improve extrusion quantity, avoid material breakage and ensure stable extrusion of materials, but also can effectively separate unmelted solid materials from melted materials, avoid the melted materials to wrap unmelted material particles, and further reduce the generation of unmelted crystal points.

(3) The mixing head of Maddock is arranged in the screw rod, so that the melting plasticizing effect of the resin can be improved, and the generation of unmelted crystal points is further reduced.

Further, in the film making process, the processing temperatures of a feeding zone, a melting zone and a metering zone of the extrusion mechanism are 150-160 ℃, and the heating temperature of a die head is 155-165 ℃.

For LDPE with low crystal point, if the heating temperature of the extrusion mechanism is too high (the heating temperature of the LDPE is over 170 ℃ and is not over 210 ℃), the material is broken to generate free radicals, so that oxidized crystal points or cross-linked crystal points are formed; if the heating temperature of the extrusion mechanism is too low (lower than 150 ℃ C.) the LDPE is not completely melted, and the long-chain branches of the material are more, and the material is easily broken when stretched in a molten state, so that micropores are formed on the surface of the film.

Further, in the film making process, the materials are extruded and then subjected to bubble inflation, traction stretching and annealing treatment; in the annealing treatment process, the speed of an annealing unit of the annealing treatment is 0.1-1% faster than that of a traction roller for traction and stretching, and the annealing unit comprises at least 4 groups of heating and stretching rollers which are communicated with circulating hot water, and the heating temperature of the heating and stretching rollers is 60-80 ℃.

The film body is subjected to longitudinal and transverse stretching force in the process of melting and crystallizing (melt extrusion and cooling film blowing), residual stress exists after the film body is molded, the film body can shrink in the direction opposite to the stretching force along with the extension of the placing time, the specification of the film body changes, the film rolling is tighter, the rolling quality of the film body is reduced, and rolling defects are generated; therefore, the film body after blow molding is required to be pulled and stretched for release, and the annealing unit is used for heating and shaping the film body again, so that the internal stress is released, the winding defect is avoided, and the quality of a finished product is ensured; in addition, the speed of the annealing unit for annealing treatment is 0.1-1% faster than that of the traction roller for traction and stretching, so that the film body is slightly stretched (the stretching proportion is controlled within 2.0%) during annealing treatment, the overall flatness of the film body is improved, and wrinkles on the film body are reduced.

Further, the detecting process includes the steps of:

defining a color difference defect threshold at a central data processing facility to establish a baseline response value;

defining quality defect types in a central data processing mechanism, and setting light response difference values corresponding to crystal points, foreign matters, wrinkles, micropores and die orifice educts, wherein the light response difference values are difference values of light response values of a film body abnormal region and a film body normal region;

a plurality of high-speed cameras are arranged in a rectangular array to scan the surface of the film body, and the obtained image data is sent to a central data processing mechanism;

the central data processing mechanism judges whether a region triggering a reference response value exists on the image; if yes, judging the defect type according to the light response difference value;

the central data processing mechanism counts the data of different defect types.

After trimming the film body (before rolling), carrying out surface scanning by using a high-speed camera, marking the position of the color difference defect threshold exceeding a reference response value according to the color difference defect threshold (the difference between the color of the position of the film body with defects and the color of the position of the film body without anomalies in an image), carrying out optical response data analysis on the marked position on the image, judging the defect type (crystal point, foreign matter, fold, micropore and die opening precipitate, wherein each defect corresponds to one optical response difference, the die opening precipitate is a carbonization byproduct generated by a die opening of film blowing equipment because of the technical problem), and simultaneously counting the defect quantity of the crystal point, the foreign matter, the fold, the micropore, the die opening precipitate and the like, and monitoring and judging the quality level of the film body.

Further, in the winding process, the diameter of the used winding tube core is 5-7 inches, the axial elastic modulus is not less than 10GPa, and the circumferential elastic modulus is not less than 18GPa.

The thickness of the protective film is thinner (usually less than 20 mu m), the length of the protective film is longer (more than 15000 m), and the coiled tube core with the specification has the characteristics of high strength, extrusion resistance and deflection resistance, can resist the pressure of the film body towards the direction of the coiled tube core when the film is coiled, avoids the compression of the tube core to deformation of the film body in the coiling process, and avoids the bending of the coiled tube core caused by the gravity of the coiled film when the coiled film is suspended (in the resting process), thereby avoiding the unusable protective film caused by the bending deformation of the coiled tube core.

Further, in the winding process, the back pressure roller uses constant back pressure of 200-400N/m; the initial tension of the winding roller is 45-70N/m, the tension linearly decreases along with the increase of the meters of the output film body, and the tension is 70-90% of the initial tension when the winding is finished.

The setting mode has the following beneficial effects:

(1) In order to ensure good rolling quality, a proper rolling process is needed to roll the film body so as to ensure that the rolling mechanism can work at stable speed control, tension control and back pressure control; aiming at the protective film of the scheme, if the constant back pressure is more than 400N/m, the film is rolled too tightly, the pressure of the film on the rolling tube core is too high, and the rolling tube core can deform; if the constant back pressure is less than 200N/m, air is involved in the film rolling process due to insufficient back pressure, so that a longitudinal or transverse defect area is formed in the film rolling process;

(2) The thickness of the protective film aiming at the scheme is thinner (usually less than 20 mu m), so the initial tension of the winding roller is set to be 45-70N/m, and if the winding tension is too large (more than 75N/m), the film body is deformed, and the pressure of the winding tube core is too large to deform; if the tension is insufficient (less than 40N/m), the problem of loose rolled film can occur;

(3) In the known film body rolling process, the film body at the outermost layer only receives the tension of a rolling mechanism, the film body in the rolled film receives the pressure from the outer layer film body to the central direction of a rolling shaft and the tension of the film body adjacent to the rolling film in the circumferential direction, as rolling is carried out, the film body at the position close to the tube core receives the pressure from the outer layer film body to the central direction of the rolling shaft, and the tension of the film body is reduced, so that the film body at the bottom part of the rolling shaft needs to recover in the transverse length according to the poisson ratio of the material, and the end face of the rolled film presents a certain taper (the bottom part of the rolling shaft is wider than the surface part of the rolling shaft); the winding tension is set to be linearly decreased (gradient decrease), and the tension is linearly decreased along with the increase of meters, and the tension is 70-90% of the initial tension when the winding is finished, so that the phenomenon that the width of a film body at the bottom of the winding is increased by more than 5mm than the width of a film body at the surface of the winding (the taper of the winding film is overlarge) due to the insufficient decreasing proportion, the use of the protective film is influenced, and the winding defect of the winding part caused by the insufficient winding tension of the winding part due to the overlarge decreasing proportion is avoided;

(4) In the winding process, proper winding conditions are set and accurately controlled, so that the wound film does not have the defects of wrinkles, wavy wrinkles and the like.

Drawings

FIG. 1 is a schematic diagram of a high precision co-extrusion blown film apparatus.

Detailed Description

Embodiments of the present invention are described below with reference to the accompanying drawings:

the preparation method of the photosensitive dry film protective film of the embodiment comprises the following steps:

cutting: trimming and edge-separating the film body;

The low crystal point LDPE particles adopted by the invention have the characteristics that:

the melt index of LDPE particles with low crystal point is 2.0-5.5g/10min (190 ℃,2.16 kg), and the density is 0.920-0.935g/cm ³ 。

If the PE resin has a large molecular weight, the high molecular weight region is more refractory and is liable to generate unmelted crystal points (melt index >5.5g/10 min); if the molecular weight of the PE resin is small, the structural strength of the melt is low, and the stability of film blowing bubbles in the subsequent processing process is affected; the invention adopts the LDPE with low crystal point in the specification, can reduce the generation of unmelted crystal points, has higher elastic modulus, and can lead the finished product to have lower elastic deformation when resisting external tension.

The LDPE particles with low crystal points contain an antioxidant, and the antioxidant content is 200-400ppm; ppm is mass ratio, and the conversion relation of ppm and percentage is 10000 times of 1ppm of 1%; the LDPE particles with low crystal point belong to the application of the existing materials.

In order to facilitate processing, storage and use of PE materials, delay the aging speed of PE and reduce the occurrence of oxidation crystal points, an antioxidant is required to be added into the PE materials, but because the photosensitive dry film has UV sensitivity, if the antioxidant content on the protective film is more than 500ppm, the antioxidant on the protective film can be attached to the photosensitive dry film, so that free radicals generated by the photosensitive dry film are captured, and the photosensitive dry film cannot be caused to react by using a preset ultraviolet irradiation amount in the process of a printed circuit board; the invention controls the antioxidant content of LDPE with low crystal point to 200-400ppm, thereby avoiding the oxidation crystal point and product oxidation of the protective film in the process of processing and producing, and simultaneously avoiding the influence of excessive antioxidants on the normal use of the photosensitive dry film.

The LDPE particles with low crystal points are produced by a kettle type method.

The LDPE produced by the kettle method has the advantages that the structure of the LDPE contains longer branched chains, so that the form stability of the film bubble is better, the viscosity of a molecular melt is high, in addition, compared with the low-density polyethylene produced by the tubular method, the film produced by the kettle method has larger surface roughness, larger haze, lower surface glossiness and lower friction coefficient, and when the two films are contacted, the two films are tightly attached, and the gap between the two films is smaller, so that sliding can still be generated relatively easily when the two films are contacted during rolling, the gas coated between the films can be smoothly discharged, and the formation of bubbles in the rolling or rolling 'pimples' is avoided, so that the film is deformed.

The preparation method of the photosensitive dry film protective film comprises the following specific steps:

specifically, the upper end of the feeding end is open, the lower end of the feeding end is connected with a feeding port of the high-precision co-extrusion film blowing equipment, and a dust removing device containing a high-speed ion fan is connected with the feeding end and enables the air flow direction in the feeding end to flow from bottom to top; during feeding, the material is fed downwards from the upper part of the feeding end, impurities on the material are discharged upwards by the air flow, and heavier material particles fall into the feeding hole downwards under the action of gravity, so that the effect of separating dust, fine scraps, powder, wadding strips and the like from the material particles is achieved.

An air cleaning system is arranged in the cleaning workshop and is used for carrying out efficient filter treatment on air entering the workshop and keeping a dynamic thousand-level clean level. An air cleaning system belongs to the prior art equipment.

In the high-precision co-extrusion film blowing equipment, a feeding pipeline is arranged between the discharging lower end of the dust removing equipment containing the high-speed ion fan and the discharging hopper, and a Teflon coating is coated on the inner side of the feeding pipeline.

A connecting pipeline is arranged between a discharging hopper of the high-precision co-extrusion film blowing equipment and the extruder, nitrogen is introduced into the connecting pipeline to form a positive pressure environment, the nitrogen flow is 5-25NL/min, and the purity of the nitrogen is more than 99%.

The extrusion mechanism of the high-precision co-extrusion film blowing equipment selects a machine barrel with a groove at a feeding section, a screw rod of the extruder is a barrier screw rod, and a Marek mixing head is arranged in the screw rod; the Mardok mixing head is arranged at the tail end.

The setting mode has the following beneficial effects:

In the film making process, the processing temperature of a feeding area, a melting area and a metering area of the extruding mechanism is 150-160 ℃, and the heating temperature of a die head is 155-165 ℃.

In this embodiment, the number of the extrusion mechanisms is 3, and the protective film is formed by co-extrusion of three layers of LDPE films with low crystal points.

In the film making process, the materials are extruded and then subjected to bubble inflation, traction stretching and annealing treatment; in the annealing treatment process, the speed of an annealing unit of the annealing treatment is 0.1-1% faster than that of a traction roller for traction and stretching, and the annealing unit comprises at least 4 groups of heating and stretching rollers which are communicated with circulating hot water, and the heating temperature of the heating and stretching rollers is 60-80 ℃.

Specifically, the temperature of the first group of heating stretching rollers is 70-80 ℃, the temperature of the second group of heating stretching rollers is 65-75 ℃, the temperature of the third group of heating stretching rollers is 60-70 ℃, and the temperature of the fourth group of heating stretching rollers is 55-65 ℃.

The detection process comprises the following steps:

In the winding process, the diameter of the used winding tube core is 5-7 inches, the axial elastic modulus is not less than 10GPa, and the circumferential elastic modulus is not less than 18GPa.

In the winding process, the back pressure roller uses constant back pressure of 200-400N/m; the initial tension of the winding roller is 45-70N/m, the tension linearly decreases along with the increase of the meters of the output film body, and the tension is 70-90% of the initial tension when the winding is finished.

The setting mode has the following beneficial effects:

(3) In the known film body rolling process, the film body at the outermost layer only receives the tension of a rolling mechanism, the film body in the rolled film receives the pressure from the outer layer film body to the central direction of a rolling shaft and the tension of the film body adjacent to the rolling film in the circumferential direction, as rolling is carried out, the film body at the position close to the tube core receives the pressure from the outer layer film body to the central direction of the rolling shaft, and the tension of the film body is reduced, so that the film body at the bottom part of the rolling shaft needs to recover in the transverse length according to the poisson ratio of the material, and the end face of the rolled film presents a certain taper (the bottom part of the rolling shaft is wider than the surface part of the rolling shaft); the winding tension is set to be linearly decreased (gradient decrease), and is linearly decreased along with the increase of the meters according to the tension, and the tension is set to be 70-90% of the initial tension when the winding is finished, so that the phenomenon that the width of a film body at the bottom of the winding is increased by more than 5mm than the width of a film body at the surface of the winding (the taper of the winding film is overlarge) due to the insufficient decreasing proportion, the use of the protective film is influenced, and the winding defect of the surface part of the winding caused by the overlarge decreasing proportion is avoided;

Specifically, before the winding process, the winding tube core is coated with an aqueous adhesive to adhere the protective film.

The existing winding process is that before the winding film is changed, a BOPP pressure-sensitive adhesive tape (or double-sided adhesive) is adhered to a preset area on a winding tube core, so that the protective film can be smoothly wound on a new winding tube core during the winding, and as the BOPP pressure-sensitive adhesive tape (or double-sided adhesive) has a certain thickness (more than 30 mu m), after the protective film is wound on the winding tube core, the thickness of the protective film, corresponding to the preset area of the winding tube core, adhered with the BOPP pressure-sensitive adhesive tape is thicker than the thickness of the protective film, corresponding to the position of the winding tube core, where the adhesive tape is not wound, so as to form traces of the pressure-sensitive adhesive tape, deform the protective film and influence thousands of meters of films at the bottom of the winding tube; according to the invention, the water-based adhesive is coated on the winding tube core to adhere the protective film, so that the protective film is ensured to be uniformly adhered on the winding tube core, and meanwhile, the trace of the pressure-sensitive adhesive tape and the deformation of the protective film are avoided.

The product parameters of the protective film prepared by the photosensitive dry film protective film preparation method are as follows:

the thickness of the film is 15-30 micrometers;

number of crystal points with diameter larger than 0.9mm<0.002/m ² ；

The number of foreign matters was 0/m ^2；

The number of broken holes is 0/m ² ；

The number of the corrugations is 0/m ² ；

The width difference between the rolling surface and the rolling bottom is less than 5mm;

the dynamic friction coefficient and the static friction coefficient of the film are less than 0.5;

the haze of the film is in the range of 12-20%.

Fig. 1 shows a high-precision co-extrusion film blowing device adopted by the photosensitive dry film protective film preparation method, wherein the high-precision co-extrusion film blowing device is positioned in a clean workshop 1, materials enter the high-precision co-extrusion film blowing device from a feeding end 2, dust removal equipment removes dust from the materials input into the feeding end 2, and the materials reach a discharging hopper 5 through a feeding pipeline 4 for weighing; the nitrogen generating device 6 is used for introducing nitrogen into the high-precision co-extrusion film blowing equipment through the conveying pipe 7; the materials enter the extrusion mechanism 8 from the blanking hopper 5, the multi-layer materials are combined into a whole at the die head 9 to form a film bubble 10, the film bubble 10 enters the traction mechanism 11 and the annealing unit 12 to be processed, and finally, the film bubble is detected by the high-speed camera 13 and is wound by the winding mechanism 14.

Variations and modifications to the above would be obvious to persons skilled in the art to which the invention pertains from the foregoing description and teachings. Therefore, the invention is not limited to the specific embodiments disclosed and described above, but some modifications and changes of the invention should be also included in the scope of the claims of the invention. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.

Claims

1. The preparation method of the photosensitive dry film protective film is characterized by comprising the following steps:

cutting: trimming and edge-separating the film body;

2. The method for producing a photosensitive dry film protective film according to claim 1, wherein the low-crystalline point LDPE particles contain an antioxidant in an amount of 200 to 400ppm.

3. The method for preparing the photosensitive dry film protective film according to claim 1, wherein a feeding pipeline is arranged between the discharging lower end of the dust removing device containing the high-speed ion fan and the discharging hopper in the high-precision co-extrusion film blowing device, and a Teflon coating is coated on the inner side of the feeding pipeline.

4. The method for preparing the photosensitive dry film protective film according to claim 1, wherein a connecting pipeline is arranged between a discharging hopper of the high-precision co-extrusion film blowing device and the extruder, nitrogen is introduced into the connecting pipeline to form a positive pressure environment, the flow rate of the nitrogen is 5-25NL/min, and the purity of the nitrogen is more than 99%.

5. The method for preparing the photosensitive dry film protective film according to claim 1, wherein the extruding mechanism of the high-precision co-extrusion film blowing device is a barrel with a groove at a feeding section, a screw of the extruder is a barrier screw, and a madok mixing head is arranged in the screw.

6. The method for preparing a photosensitive dry film protective film according to claim 1, wherein in the film preparation process, the processing temperatures of a feeding zone, a melting zone and a metering zone of the extrusion mechanism are 150-160 ℃, and the heating temperature of a die head is 155-165 ℃.

7. The method for preparing a photosensitive dry film protective film according to claim 1, wherein in the film preparation process, the material is extruded and then subjected to bubble inflation, traction stretching and annealing treatment; in the annealing treatment process, the speed of an annealing unit of the annealing treatment is 0.1-1% faster than that of a traction roller for traction and stretching, and the annealing unit comprises at least 4 groups of heating and stretching rollers which are communicated with circulating hot water, and the heating temperature of the heating and stretching rollers is 60-80 ℃.

8. The method for preparing a photosensitive dry film protective film according to claim 1, wherein the step of detecting process comprises:

9. The method for producing a photosensitive dry film protective film according to claim 1, wherein a winding core having a diameter of 5 to 7 inches, an axial elastic modulus of not less than 10GPa, and a circumferential elastic modulus of not less than 18GPa is used in the winding process.

10. The method for preparing a photosensitive dry film protective film according to claim 1, wherein a constant back pressure of 200-500N/m is used for the back pressure roller during the rolling process; the initial tension of the winding roller is 45-70N/m, the tension linearly decreases along with the increase of the meters of the output film body, and the tension is 70-90% of the initial tension when the winding is finished.