CN116973376A - Evaluation method of LDPE optical protective film resin - Google Patents

Evaluation method of LDPE optical protective film resin Download PDF

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Publication number
CN116973376A
CN116973376A CN202210436204.4A CN202210436204A CN116973376A CN 116973376 A CN116973376 A CN 116973376A CN 202210436204 A CN202210436204 A CN 202210436204A CN 116973376 A CN116973376 A CN 116973376A
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ldpe
protective film
film
crystal
optical protective
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许惠芳
魏福庆
邸麟婷
叶鹏博
李广全
赵东波
李晓艳
李朋朋
谢昕
孙建敏
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Petrochina Co Ltd
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Petrochina Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/18—Performing tests at high or low temperatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N2021/0106—General arrangement of respective parts
    • G01N2021/0112—Apparatus in one mechanical, optical or electronic block
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G01N2021/8854—Grading and classifying of flaws
    • G01N2021/8858—Flaw counting

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
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  • Signal Processing (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

The application relates to an evaluation method of LDPE optical protective film resin, which can rapidly judge whether raw materials are qualified or not by controlling a processing method of a test sample and a crystal point test condition and establishing a relation between the crystal point and the melt strength of a resin blown film. The method is suitable for rapid evaluation of LDPE optical protective film resin.

Description

Evaluation method of LDPE optical protective film resin
Technical Field
The application relates to the field of polymer resin evaluation, in particular to an evaluation method of LDPE optical protective film resin.
Background
In recent years, with the rapid development of the electronic industry, there has been an increasing demand for optical protective films, which are widely used for producing and transporting optical films such as polarizing plates, retardation plates, lens films for displays, antireflection films, transparent conductive films for touch panels, and optical products such as displays using the same, in order to prevent surface contamination, scratches, and the like, which may be caused in subsequent steps. The optical protective film produced at present mainly comprises polyethylene and polypropylene, and LDPE has good softness, extensibility, electrical insulation, transparency, easy processing and certain air permeability. The optical protective film has good chemical stability and excellent alkali resistance, general organic solvent resistance and the like, and is widely applied to the field of optical protective films. In 2020, the requirement of the optical protective film Low Density Polyethylene (LDPE) in China reaches 5 ten thousand tons and is completely dependent on import. There are companies trying to develop such products in China, but the development in the field is limited due to the problem of more crystal points, the requirement of the optical protection film on the crystal points is very high, and the surface of the protected object is possibly scratched due to the high crystal points, so that the crystal points of the film are the main reasons for the quality of the optical protection film not reaching standards. The reasons for the crystallization point caused by the prior literature mainly include large molecular weight, impurities, long-chain branches and crosslinking, and the crystallization point is correspondingly controlled by adjusting corresponding process conditions. But currently, an evaluation method for the crystal point of the protective film is lacking.
The existing evaluation method for the crystal points of the film is as follows:
CN105922689a discloses a high-viscosity self-adhesive surface protective film and a manufacturing method thereof, wherein the surface protective film comprises a self-adhesive layer, an intermediate layer and a release layer: the self-adhesive layer comprises ultra-low density polyethylene and soft polypropylene; the middle layer comprises one or two mixtures of ethylene-propylene copolymer and polyethylene with low crystal points, and the anti-sticking layer adopts block copolymerized polypropylene. The application also discloses a manufacturing method of the high-transparency self-adhesive surface protection film, which is sequentially prepared by raw material dust removal, automatic weighing and metering of raw materials, heating extrusion, efficient filtration, co-extrusion film forming, cooling shaping, automatic thickness control, defect detection, trimming and rolling, aging treatment and slitting and packaging, and the quality of the product is controlled by the number of crystal points of the film.
From the table above, it can be seen that the crystal points below 0.2mm have no statistics, but the crystal points have a great influence on the quality of the optical protective film, and the size range cannot meet the quality requirement of the LDPE raw material of the optical protective film.
JB/T10437-2004 "crosslinkable polyethylene insulation Material for electric wire and Cable" discloses a method for detecting impurity content of YJ-35 and YJG-35 crosslinkable polyethylene insulation materials. Under the irradiation of the light beam, the sample belt has light shielding property, a constant, continuous and adjustable light source is adopted, the light transmitting and shielding light beam of the sample belt is received by the electronic camera, and the particle size and the particle number are detected by the impurity particle detector. The resolution of the impurity particle detector is better than 100um, the sample is a strip sheet material, the thickness (0.5-0.8) mm, the width (50+ -3) mm and the weight about 1000g, the sample is prepared by adopting a small extruder, and the surface of the strip sheet material is flat, smooth and free from pollution by a guide wheel and a calender wheel. The number of (0.175-0.250) mm impurity particles on a 1kg sample belt should not exceed 5, and the number of impurity particles larger than 0.250mm should be zero. The crystal points below 0.175mm of the method have no statistics, the crystal points have great influence on the quality of the optical protection film, and the dimensional accuracy can not meet the quality requirement of LDPE raw materials of the optical protection film.
CN112710669a discloses a method for rapidly evaluating the crystal point of a hard elastic diaphragm of a homo-polypropylene lithium battery, in particular to a method for evaluating the crystal point of the hard elastic diaphragm of the homo-polypropylene lithium battery. The method comprises the following steps: extruding and casting the special material for the lithium battery diaphragm through a casting roller by utilizing a double-screw extruder; before the hard elastic film is rolled, an online flaw detector is arranged at a position after extrusion processing is finished in advance; before traction and winding, stretching and flattening the casting film between the last two groups of casting rollers after multilayer winding and extension to form a hard elastic film, detecting crystal points of the hard elastic diaphragm of the lithium battery by an online flaw detector, collecting crystal point data, and estimating the product quality according to the classified collection quantity of the crystal points. According to the application, the relation between the crystal point of the product and ash content, the rebound rate and the permeability of the filter screen is obtained through the online flaw detector, so that the product evaluation time is shortened, the performance of the special material for the lithium battery film can be primarily judged in the process of preparing the hard elastic film of the lithium battery, and the evaluation efficiency is greatly improved. The flaw determination criteria are classified as follows:
high-grade product: the total number of flaws is less than 600/100 m 2 And the total number of small crystal points and small black points is less than or equal to 300;
qualified products: grade 1 qualified product: the total number is 600 to be less than or equal to 1000/100m 2 And 300/100m 2 Less than small crystal points and less than or equal to 500 small black points/100 m 2 The method comprises the steps of carrying out a first treatment on the surface of the Grade 2 qualified product: 1000 is more than or equal to 2000/100 m 2 And 500/100m 2 Less than small crystal points and less than or equal to 1000 small black points/100 m 2 The method comprises the steps of carrying out a first treatment on the surface of the Grade 3 qualified product: 2000 < total less than or equal to 3000/100 m 2 And 1000/100m 2 Less than small crystal points and less than or equal to 1500/100 m of small black points 2 The method comprises the steps of carrying out a first treatment on the surface of the Reject: total > 3000/100 m 2 And the total number of small crystal dots and small black dots is more than 1500/100 m 2 。
It can be seen that this method includes the number of black spots, which is not allowed in the optical protective film, and there is no specific crystal spot size, only the number is required, and the requirement of the optical protective film cannot be satisfied.
In the method for judging the appearance of the LDPE film material by GB/T11115-2009, only fish eyes and stripes are provided, wherein the fish eyes are spherical blocks formed by transparent or semitransparent resin in a film, the size range is 0.3mm-2mm, and the precision of a magnifying glass is 0.1mm; the stripes are linear and round hammer-shaped tiny protrusions and continuous fish eyes which appear in the film, are called stripes, the size range is more than or equal to 1.0cm, the ruler precision is 1.0cm, different raw materials have quantity indexes, and the exceeding standard is unqualified.
It can be seen that the existing crystal point evaluation can treat unqualified products in time, but the size range and the precision can not meet the quality requirement of LDPE raw materials of the optical protective film.
Hitherto, with respect to an optical protective film, the prior art disclosed and reported mainly focuses on improvement of a raw material production process, gluing and formulation of the protective film, and in the testing process, although the content of a thin film crystal point size range is involved, the precision of the tested crystal point cannot meet the requirement of the optical protective film on the raw material, and only meets the crystal point index, and there may be insufficient melt strength, so that the film forming stability of the thin film is affected in the film blowing process. At present, the optical protection film raw materials produced by a raw material production factory can clearly meet the requirements of the optical protection film only through downstream factory application, so that the evaluation result period is long, and if the use effect is poor, great losses are brought to the production factory and downstream users. Therefore, there is a need for a simple and rapid method for evaluating LDPE optical protective film resin, which is convenient for production units to evaluate the quality of the resin.
Disclosure of Invention
The application aims to provide an evaluation method of LDPE optical protective film resin, which can accurately, quickly and conveniently evaluate the quality of the optical protective film resin.
In order to achieve the above object, the present application provides a method for evaluating an LDPE optical protective film resin, comprising the steps of:
(1) Blowing LDPE resin into a film with the thickness of 0.01-0.08 mm;
(2) Under the irradiation of light beams generated by a constant, continuous and adjustable light source, the light-transmitting and shading light beams are received by an optical camera, and the crystal point particle detector detects that the crystal point size is larger than or equal to 20um under the condition that the resolution ratio is larger than or equal to 20umSize and number of crystal point particles equal to 0.02 mm; the diameter of the grain with the crystal point is more than or equal to 0.8mm, or the number of the crystal point>4/m 2 When the raw material is an unqualified product; otherwise, the product is a preliminary qualified product;
(3) Calculating the number of crystal points of the obtained primary qualified product and the melt strength of the LDPE resin raw material, wherein the relation between the number of crystal points and the melt strength of the LDPE resin raw material satisfies the following conditions that the crystal points and the melt strength of the LDPE resin raw material can be used as the raw material of the optical protective film:
y≤43.97286x-52.76556x 2 -0.97315
wherein x is melt strength, and the numerical range of x is 0.04-0.15 calculated by taking Newton as a unit when tested at 190 ℃;
y is the number of crystal points, and is calculated according to the number of all crystal points in the film per square meter.
The evaluation method of the LDPE optical protective film resin provided by the application has the melt strength value of 0.06-0.14.
The melt strength adopts a direct measurement method in the field, the method is common knowledge in the field, wu Chunshuang is characterized by long-chain branch rheology of a special material for P E-R T pipes (Shanghai plastics, 2017,177 (1): 31-36) and a polyethylene melt strength test method and influencing factors thereof (Shanghai plastics, 2015 (3): 55-60), CN201180013377.5: direct measurement of the melt strength of polyethylene is described in the process for preparing polyethylene having high melt strength. The melt strength detection conditions recommended by the application are as follows: the test is carried out by using a Goettfert company RT-2000 melt extensional rheometer at 190 ℃ and the length-diameter ratio of the capillary orifice film is any one of 20/2, 10/1, 20/1 and 30/1, preferably 20/2, and the shearing rate is 45s -1 The distance between the traction rollers is 0.4 mm-1 mm, preferably 0.5 mm-0.7 mm, and the traction acceleration is 6mm/s 2 。
In the step (2) 'the film is irradiated by a constant, continuous and adjustable light source, the light-transmitting and shading light beam is received by an optical camera, the crystal point particle detector detects the size and the quantity of crystal point particles with the crystal point size being more than or equal to 0.02mm under the condition that the resolution is more than 20 um', the means is the known technology in the field, for example, the detection of the impurity content of YJ-35 and YJG-35 type crosslinkable polyethylene insulating materials is adopted by a method specified in JB/T1043-2004 'crosslinkable polyethylene insulating materials for wires and cables', namely, the process described by an annex B impurity content detection method is only needed, the method counts crystal points on the sheet, and an online system for counting the crystal points of the film is also provided, for example, the SMASH coil system of Germany ISRA company is a powerful tool for searching defects on a uniform and continuous coil product, and the application meets the requirements of sample preparation to reach the thickness of the step (1) and the resolution of the step (2).
The evaluation method of the LDPE optical protective film resin provided by the application has the film thickness of 0.02-0.06 mm.
According to the evaluation method of the LDPE optical protective film resin, the number of crystal points in the step (3) is an average value of 3-5 times of parallel testing on the same film. The use of the average value can effectively eliminate errors.
According to the evaluation method of the LDPE optical protective film resin, the LDPE resin raw material is granular material without powder, black particles and/or yellow particles in appearance. Before being blown into a film, the appearance of the LDPE raw material particles is preferably visually inspected, and the LDPE raw material particles are free of powder, black particles and/or yellow particles, so that film blowing and subsequent testing can be performed; the appearance of the LDPE raw material is powder, black particles and/or yellow particles, namely the LDPE raw material is judged to be a disqualified raw material.
According to the evaluation method of the LDPE optical protective film resin, in the step (2), the number of crystal points with the size range of 0.02-0.1 mm, 0.1-0.2 mm, 0.2-0.3 mm, 0.3-0.4 mm, 0.4-0.5 mm, 0.5-0.6 mm, 0.6-0.7 mm, 0.7-0.8 mm and more than or equal to 0.8mm is counted respectively. Since the optical protective film has high requirements on the appearance of the film, the fewer crystal points are required to be, the better the crystal points are, and the lower the crystal point size is, the smaller the better the influence on the protected object is under the condition that the crystal point number is the same.
The application relates to an evaluation method of LDPE optical protective film resin, which comprises the step of blowing an LDPE film by using a film blowing machine, wherein the film blowing machine comprises an extrusion main machine and a traction auxiliary machine, the processing temperature of the extrusion main machine is 140-180 ℃, the rotating speed is 20-50 rpm, and the traction rotating speed of the traction auxiliary machine is 8-50 m/min.
According to the evaluation method of the LDPE optical protective film resin, the rotating speed of the extrusion main machine is 20-40 rpm, and the traction rotating speed of the traction auxiliary machine is 10-40 m/min.
According to the evaluation method of the LDPE optical protective film resin, the extrusion host is a single-screw extruder or a double-screw extruder.
According to the evaluation method of the LDPE optical protective film resin, the film blowing machine is matched with a winding device. The winding device ensures that blown films can be pulled apart without wrinkles and can not be stretched and deformed, and the results of crystal point testing are inaccurate due to stretching deformation and wrinkles. This technical approach is common knowledge in the art and is called effective synergy. Specifically, the process of blowing into a film is to plasticize and extrude LDPE resin raw material to form a ring pipe for inflation molding, and then cool, draw and roll up the LDPE resin raw material to blow into a film with the thickness of 0.01-0.08 mm. More specifically, the film blowing machine comprises an extrusion host machine, a traction auxiliary machine, an air ring, a die head, an air compressor, a distribution box blower and a winding device, wherein the film blowing process is a flat extrusion upward blowing method, namely, the discharging direction of the extrusion host machine head is vertical to the extrusion host machine, the extrusion ring pipe is upward, the extrusion ring pipe is clamped by a lambdoidal plate after being pulled to a certain distance by the traction auxiliary machine, the extrusion ring pipe is blown into a bubble pipe by compressed air introduced from the bottom, the transverse size of the bubble pipe is controlled by the amount of compressed air, the longitudinal size of the bubble pipe is controlled by the traction speed, and the blown film can be obtained by cooling and shaping the bubble pipe. The process of traction and inflation is closer to the processing technology of the using process of a user, and the raw materials are evaluated more accurately.
The light source, the optical camera and the crystal point particle detector for crystal point detection form a crystal point testing device, and the crystal point testing device can be a commercially available device or can be assembled by itself. The device is only required to be arranged behind the film blowing machine for testing the film, and is preferably arranged between the film blowing device and the winding device.
The application has the beneficial effects that:
according to the evaluation method of the LDPE optical protective film resin, disclosed by the application, by controlling the processing method of a test sample and the crystal point test condition and establishing the relation between the crystal point and the melt strength of the resin blown film, whether the raw materials are qualified or not can be accurately and rapidly judged, and compared with the prior art, the evaluation method of the LDPE optical protective film resin can be more rapid and more accurate than the existing post test. The method is suitable for rapid evaluation of LDPE optical protective film resin.
Detailed Description
The present application will be specifically described below by way of examples. It is noted herein that the following examples are given solely for the purpose of illustration and are not to be construed as limiting the scope of the application, as many insubstantial modifications and variations of the application will become apparent to those skilled in the art in light of the above disclosure.
The raw material sources are as follows: the imported LDPE optical protective film special material is a commercial product. Optical protective film resin of a certain company of petroleum, test production sample 1, test production sample 2, test production sample 3, test production sample 4, test production sample 5, test production sample 6 and test production sample 7.
The analysis method comprises the following steps:
the melt strength was measured using a Goettfert RT-2000 melt extensional rheometer at 190 ℃.
Film blowing machine: E45P film blowing machine from COLLIN Corp.
Crystal point: the detection was performed using a SMASH type crystal point detector from ISRA, germany.
Example 1
For sample 1, films were blown at 150℃at a blowing machine head temperature, a blowing ratio of 2.0, a rotational speed of 30rpm, a drawing speed of 9.0m/min, and a film thickness of 30. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the sample was measured 4 times in parallel, and the average value was obtained, and the results are shown in Table 1.
TABLE 1
Test sample 1 melt strength test results were 0.10N, according to the formula 43.97286x-52.76556x 2 The calculated result of 0.97315 is 2.90, and the crystal point test result is 2.78, namely y is less than or equal to 43.97286x-52.76556x 2 0.97315, which is judged to be a qualified product, is applied to optical protection film manufacturers, and the result shows that the use requirement of the optical protection film can be met.
Example 2
For sample 2, a film was blown at a die temperature of 170℃in a film blowing machine, a blowing ratio of 2.0, a rotational speed of 28rpm, a drawing speed of 8.8m/min, and a film thickness of 20. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the sample was measured 4 times in parallel, and the average value was obtained, and the results are shown in Table 2.
TABLE 2
Test sample 2 melt strength test results were 0.045N, according to the formula 43.97286x-52.76556x 2 0.97315 has a calculated result of 0.90 and a crystal point test result of 0.81, i.e. meets the requirement that y is less than or equal to 43.97286x-52.76556x 2 0.97315, which is judged to be a qualified product, is applied to optical protection film manufacturers, and the result shows that the use requirement of the optical protection film can be met.
Example 3
For sample 3, films were blown at a die temperature of 160℃in a film blowing machine, a blowing ratio of 2.0, a rotational speed of 30rpm, a drawing speed of 9.6m/min, and a film thickness of 30. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the coupon was tested 4 times in parallel and the results are shown in Table 3.
TABLE 3 Table 3
Test sample 3 had a melt strength of 0.065N and was prepared according to equation 43.97286x-52.76556x 2 0.97315 results are 1.66, and the crystal point test result is 1.12, namely y is equal to or less than 43.97286x-52.76556x 2 0.97315, which is judged to be a qualified product, is applied to optical protection film manufacturers, and the result shows that the use requirement of the optical protection film can be met.
Example 4
For sample 4, films were blown at a die temperature of 160℃in a film blowing machine, a blowing ratio of 2.5, a rotational speed of 38rpm, a drawing speed of 21m/min and a film thickness of 20. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the sample was measured 4 times in parallel, and the average value was obtained, and the results are shown in Table 4.
TABLE 4 Table 4
Test sample 4 melt strength test results were 0.051N, according to the formula 43.97286x-52.76556x 2 The calculated result of 0.97315 is 1.13, and the crystal point test result is 0.97, namely, the crystal point test result accords with y less than or equal to 43.97286x-52.76556x 2 0.97315, judging as a qualified product, and applying the product to an optical protection film application manufacturer shows that the application requirement of the optical protection film can be met.
Example 5
For sample 5, a film was blown at 180℃at the head temperature of the film blowing machine, with a blowing ratio of 2.5, a rotational speed of 38rpm, a drawing speed of 18m/min and a film thickness of 30. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the coupon was tested 4 times in parallel and the results are shown in Table 5.
TABLE 5
Test sample 5 melt strength test results were 0.14N, according to the formula 43.97286x-52.76556x 2 The calculated result of 0.97315 is 4.15, and the crystal point test result is 3.9, namely y is equal to or less than 43.97286x-52.76556x 2 0.97315, judging as a qualified product, and irradiating with lightThe application of the optical protection film manufacturer shows that the optical protection film can meet the use requirement of the optical protection film.
Example 6
The special material for the imported LDPE optical protective film is blown into a film at 160 ℃ at the head temperature of a film blowing machine, the blowing ratio is 2.0, the rotating speed is 30rpm, the traction speed is 9.5m/min, and the film thickness is 30um. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the coupon was tested 4 times in parallel and the results are shown in Table 6.
TABLE 6
The melt strength test result of the optical protective film raw material is 0.075N, according to the formula 43.97286x-52.76556x 2 The calculated result of 0.97315 is 2.03, and the crystal point test result is 1.92, namely y is less than or equal to 43.97286x-52.76556x 2 0.97315, which is judged to be a qualified product, is applied to optical protection film manufacturers, and the result shows that the use requirement of the optical protection film can be met.
Example 7
For sample 6, films were blown at a die temperature of 155℃in a film blowing machine, a blowing ratio of 2.0, a rotational speed of 25rpm, a drawing speed of 15.1m/min, and a film thickness of 15. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the coupon was tested 4 times in parallel and the results are shown in Table 7.
TABLE 7
Test sample 6 melt Strength test result was 0.070N, according to the formula 43.97286x-52.76556x 2 The calculated result of-0.97315 is 1.85, and the crystal point test result is 1.56, namely, the crystal point test result accords with y less than or equal to 43.97286x-52.76556x 2 0.97315, which is judged to be a qualified product, is applied to optical protection film manufacturers, and the result shows that the use requirement of the optical protection film can be met.
Example 8
For sample 7, films were blown at a die temperature of 175℃in a film blowing machine, a blowing ratio of 1.5, a rotational speed of 30rpm, a drawing speed of 9.7m/min, and a film thickness of 30. Mu.m. The crystal point detector detects 200m under the condition that the resolution ratio is 20um 2 The number of spots on the coupon was tested 4 times in parallel and the results are shown in Table 8.
TABLE 8
Test sample 7 melt strength test results were 0.12N, according to the formula 43.97286x-52.76556x 2 The calculated result of-0.97315 is 3.54, the crystal point test result is 3.87, and y is not less than or equal to 43.97286x-52.76556x 2 0.97315, judging as an unqualified product, and applying the unqualified product in an optical protection film manufacturer, wherein the result shows that the crystal points are more and less in time, the fluctuation is larger, and the use requirement of the optical protection film cannot be met.
Comparative example 1
For sample 7, films were blown at a die temperature of 175℃in a film blowing machine, a blowing ratio of 1.5, a rotational speed of 30rpm, a drawing speed of 9.7m/min, and a film thickness of 30. Mu.m. According to the range of CN105922689A crystal points, the crystal point detector detects 200m under the condition that the resolution is 20um 2 The number of spots on the sample was measured 4 times in parallel, and the average value was obtained, and the results are shown in Table 9.
TABLE 9
Diameter of crystal point Index (I) 1 st time 2 nd time 3 rd time Fourth time Test value, m 2
>2mm Without any means for 0 0 0 0 0
(0.8-2)mm Without any means for 0 0 0 0 0
(0.6-0.8)mm ≤1 0.13 0.09 0.1 0.06 0.095
(0.2-0.6)mm ≤5 0.73 0.44 0.38 0.49 0.51
According to the test range, the index requirement is satisfied, but as can be seen from example 8, the manufacturer's use requirement cannot be satisfied because many small crystal points below 0.2mm are omitted.
Comparative example 2
For sample 7, films were blown at a die temperature of 175℃in a film blowing machine, a blowing ratio of 1.5, a rotational speed of 30rpm, a drawing speed of 9.7m/min, and a film thickness of 30. Mu.m. The crystal point detector detects under the condition that the resolution is 20um, counts according to a CN112710669A crystal point grading method, tests for 4 times in parallel, and takes the average value, and the result is shown in Table 10.
Table 10
It can be seen from example 8 that the requirements of the manufacturer cannot be satisfied because the crystal point requirements are relatively low, and the requirements of the optical protective film cannot be satisfied.
Of course, the present application is capable of other various embodiments and its several details are capable of modification and variation in light of the present application by one skilled in the art without departing from the spirit and scope of the application as defined in the appended claims.

Claims (10)

1. An evaluation method of LDPE optical protective film resin is characterized by comprising the following steps:
(1) Blowing LDPE resin into a film with the thickness of 0.01-0.08 mm;
(2) Under the irradiation of light beams generated by a constant, continuous and adjustable light source, the light-transmitting and shading light beams are received by an optical camera, and the size and the number of crystal point particles with the crystal point size being more than or equal to 0.02mm are detected by a crystal point particle detector under the condition that the resolution ratio is more than or equal to 20 um; the diameter of the grain with the crystal point is more than or equal to 0.8mm, or the number of the crystal point>4/m 2 In the time-course of which the first and second contact surfaces,the raw material is an unqualified product; otherwise, the product is a preliminary qualified product;
(3) Calculating the number of crystal points of the obtained primary qualified product and the melt strength of the LDPE resin raw material, wherein the relation between the number of crystal points and the melt strength of the LDPE resin raw material satisfies the following conditions that the crystal points and the melt strength of the LDPE resin raw material can be used as the raw material of the optical protective film:
y≤43.97286x-52.76556x 2 -0.97315
wherein x is melt strength, and the numerical range of x is 0.04-0.15 calculated by taking Newton as a unit when tested at 190 ℃;
y is the number of crystal points, and is calculated according to the number of all crystal points in the film per square meter.
2. The method for evaluating an LDPE optical protective film resin according to claim 1, wherein the melt strength value is 0.06 to 0.14.
3. The method for evaluating an LDPE optical protective film resin according to claim 1, wherein the film thickness is 0.02 to 0.06 mm.
4. The method for evaluating an LDPE optical protective film resin according to claim 1, wherein the number of crystal points in the step (3) is an average value of 3 to 5 times of parallel tests on the same film.
5. The method for evaluating an LDPE optical protective film resin according to claim 1, wherein the LDPE resin raw material is a pellet having no powder, black particles and/or yellow particles in appearance.
6. The method for evaluating an LDPE optical protective film resin according to claim 1, wherein in the step (2), the number of crystal points having a crystal point size ranging from 0.02 to 0.1mm, from 0.1 to 0.2mm, from 0.2 to 0.3mm, from 0.3 to 0.4mm, from 0.4 to 0.5mm, from 0.5 to 0.6mm, from 0.6 to 0.7mm, from 0.7 to 0.8mm, and not less than 0.8mm is counted, respectively.
7. The method for evaluating an LDPE optical protective film resin according to claim 1, wherein the LDPE film is blown by a film blowing machine, the film blowing machine comprises an extrusion main machine and a traction auxiliary machine, the processing temperature of the extrusion main machine is 140-180 ℃, the rotating speed is 20-50 rpm, and the traction rotating speed of the traction auxiliary machine is 8-50 m/min.
8. The method for evaluating an LDPE optical protective film resin according to claim 7, wherein the rotation speed of the extrusion main machine is 20-40 rpm, and the traction rotation speed of the traction auxiliary machine is 10-40 m/min.
9. The method for evaluating an LDPE optical protective film resin according to claim 7, wherein the extrusion host is a single screw extruder or a twin screw extruder.
10. The method for evaluating an LDPE optical protective film resin according to claim 7, wherein the film blowing machine is provided with a winding device.
CN202210436204.4A 2022-04-22 2022-04-22 Evaluation method of LDPE optical protective film resin Pending CN116973376A (en)

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