CN115230272A

CN115230272A - Double-sided extinction heat-resistant BOPP diaphragm and preparation method thereof

Info

Publication number: CN115230272A
Application number: CN202210812609.3A
Authority: CN
Inventors: 王辉煌; 项晓波
Original assignee: Ruian Dongwei Plastic Co ltd
Current assignee: Ruian Dongwei Plastic Co ltd
Priority date: 2022-07-11
Filing date: 2022-07-11
Publication date: 2022-10-25
Anticipated expiration: 2042-07-11
Also published as: CN115230272B

Abstract

The invention belongs to the technical field of thin films, and particularly relates to a double-sided extinction heat-resistant BOPP membrane and a preparation method thereof. The method comprises the following steps: 1) Preparing an outer surface layer material, an outer core layer material, an inner core layer material and an inner surface layer material in sequence, and respectively placing the prepared materials in different extruders for separate plasticization; 2) And 1) sequentially carrying out compounding, sheet casting, longitudinal drawing and transverse drawing on the melt obtained by plasticizing to obtain a mother film, and sequentially carrying out corona treatment and aging treatment on the mother film to obtain the double-sided extinction heat-resistant BOPP diaphragm of the target product. The BOPP diaphragm can realize effective heat resistance, and can effectively prevent products from being heated when electronic products, particularly special products containing lithium batteries and the like which need to be stored and transported in a heat insulation way are packaged.

Description

Double-sided extinction heat-resistant BOPP diaphragm and preparation method thereof

Technical Field

The invention belongs to the technical field of films, and particularly relates to a double-sided extinction heat-resistant BOPP diaphragm and a preparation method thereof.

Background

The biaxially oriented polypropylene film is called BOPP film for short, wherein the BOPP extinction film is the most common film material. The adhesive has excellent performances in printing, gluing and the like, and has good use effects when being used for producing electronic product packages, high-grade outer packages and the like. However, the anti-adhesion performance of the conventional double-sided matte BOPP separator is relatively limited, and meanwhile, in some specific situations, such as the packaging and transportation process of part of specific electronic products with lithium batteries, a certain degree of heat resistance needs to be ensured, while the conventional BOPP separator does not have good heat resistance, so that the development of the BOPP separator with a certain heat resistance is an important direction for the development of the conventional BOPP film.

Disclosure of Invention

The invention provides a double-sided photoresist-eliminating heat-type BOPP diaphragm and a preparation method thereof, aiming at solving the problems that the existing BOPP diaphragm does not have good heat resistance, even part of BOPP films have poor long-term heat-resistant stability due to overhigh PP-H component content, are easy to age and even damage and the like.

The invention aims to:

1. the heat resistance of the BOPP diaphragm is improved;

2. the long-term thermal stability of the BOPP diaphragm is improved;

3. the BOPP diaphragm is ensured to have better mechanical property.

In order to achieve the purpose, the invention adopts the following technical scheme.

A method for preparing a double-sided extinction heat-resistant BOPP diaphragm,

the method comprises the following steps:

1) Preparing an outer surface layer material, an outer core layer material, an inner core layer material and an inner surface layer material in sequence, respectively placing the prepared materials in different extruders for separate plasticization, controlling the extrusion temperature of the outer surface layer material, the inner core layer material and the inner surface layer material to be 230-245 ℃, controlling the extrusion temperature of the outer core layer material to be 165-185 ℃, and controlling the outer surface layer material to be filtered through a 100-150-mesh sieve in the extrusion process, the outer core layer material to be filtered through a 600-800-mesh sieve in the extrusion process, and the inner core layer material and the inner surface layer material to be filtered through a 300-325-mesh sieve;

2) And 1) sequentially carrying out compounding, sheet casting, longitudinal drawing and transverse drawing on the melt obtained by plasticizing to obtain a mother film, and sequentially carrying out corona treatment and aging treatment on the mother film to obtain the double-sided extinction heat-resistant BOPP diaphragm of the target product.

As a preference, the first and second liquid crystal compositions are,

the outer surface layer material in the step 1) comprises the following components in percentage by mass:

36-48 wt% of homopolymerized polypropylene, 6-8 wt% of binary random copolymerization polypropylene and the balance of high-density polyethylene;

the inner surface layer material in the step 1) comprises the following components in percentage by mass:

28-35 wt% of homopolymerized polypropylene, 5-7 wt% of binary random copolymer polypropylene, 4-7 wt% of ternary random copolymer polypropylene and the balance of high-density polyethylene;

the inner core layer material in the step 1) comprises the following components in percentage by mass:

0.5 to 1.8 weight percent of antistatic agent and the balance of homopolymerized polypropylene.

As a preference, the first and second liquid crystal compositions are,

the melt index of the homopolymerized polypropylene, the binary random copolymerization polypropylene and the ternary random copolymerization polypropylene is more than or equal to 2.6.

As a matter of preference,

the outer core layer material in the step 1) comprises the following components in percentage by mass:

15-25 wt% of mesoporous silica nano particles and the balance of liquid wax.

As a preference, the first and second liquid crystal compositions are,

the liquid wax comprises the following components in percentage by mass:

50-65 wt% of paraffin, 12-16 wt% of n-octanol and the balance of butyl stearate.

As a preference, the first and second liquid crystal compositions are,

the outer core material is prepared by the following method:

dispersing mesoporous silica nanoparticles into water at least 1 time of the mesoporous silica nanoparticles by mass, adding n-octanol, performing ultrasonic dispersion uniformly, heating to the temperature of more than or equal to 50 ℃, adding butyl stearate, performing ultrasonic dispersion uniformly again to obtain a liquid material, heating paraffin to be completely molten, slowly adding the liquid material, adding the liquid material at a rate of 1.1-1.5 wt% of the paraffin per minute according to the mass of the paraffin, stirring uniformly after completely adding the liquid material, and drying to remove water to obtain the outer core layer material.

As a preference, the first and second liquid crystal compositions are,

the paraffin wax has a melting point of 44 ℃ and/or 46 ℃.

As a matter of preference,

the processing temperature of the sheet casting process in the step 2) is 35-40 ℃;

the treatment temperature of the longitudinal drawing process in the step 2) is 128-134 ℃, and the longitudinal drawing process is preheated to 44-50 ℃ before being heated to the treatment temperature and is kept for at least 45min at a constant temperature;

the treatment temperature of the transverse drawing process in the step 2) is 160-168 ℃, and the transverse drawing process is preheated to 44-50 ℃ before being heated to the treatment temperature and is kept for at least 45min at constant temperature.

As a preference, the first and second liquid crystal compositions are,

step 2) the corona treatment control strength is 30-35 W.min.m ^-2 ；

The time of the aging treatment in the step 2) is more than or equal to 3d.

A double-sided extinction heat-resistant BOPP diaphragm,

the thickness of the BOPP diaphragm is 48-52 mu m;

the BOPP diaphragm comprises an outer surface layer, an outer core layer, an inner core layer and an inner surface layer, wherein the thicknesses of the layers are respectively as follows:

4-10% of outer surface layer, 13-18% of outer core layer, 2-6% of inner surface layer and the balance of inner core layer.

According to the technical scheme, the multilayer structure belongs to a conventional composite BOPP film structure, the conventional BOPP film is generally of a three-layer structure and comprises an outer surface layer, a core layer and an inner surface layer, and the three layers are prepared by taking homo-polypropylene (PP-H) as a main component and sequentially carrying out compounding, sheet casting, biaxial stretching, double-sided corona treatment and aging treatment.

In the technical scheme of the invention, the core is that an outer core layer is additionally formed. In the outer core layer, the mesoporous silica nano particles are matched with the liquid wax, and certain thermal buffering is realized through the liquid wax, so that the heat resistance is realized, the temperature rise of the whole BOPP diaphragm is avoided, the long-term thermal stability of the whole BOPP diaphragm is improved, the thermal ageing of the whole BOPP diaphragm is avoided, and the service life of the whole BOPP diaphragm is prolonged. Specifically, in the liquid wax, it has contained the paraffin of fixed melting point as phase transition protective material, it can effectively avoid external environment temperature to conduct through the BOPP diaphragm fast through the mode of constant temperature phase transition, the cooperation has n-octanol and butyl stearate simultaneously, can effectively ensure the mobility of liquid wax, simultaneously, although n-octanol and butyl stearate can reduce the phase transition temperature of outer sandwich layer to a certain extent, but paraffin alone also can ensure that it has good levelling nature under heating to higher condition, but can't ensure the homogeneity of mesoporous silica nanoparticle dispersion, the condition that can lead to the roughness of film is uneven takes place, and butyl stearate can effectively stabilize liquid wax, avoid the overflow of film in the outer sandwich layer in the use, mesoporous silica nanoparticle plays and improves film roughness, promote its anti-adhesion performance, also possess the effect of catching fixed outer sandwich layer, in order to ensure that outer sandwich layer can compound in the BOPP diaphragm more steadily.

The beneficial effects of the invention are:

1) The heat resistance of the BOPP diaphragm is greatly improved, the effective heat resistance at 33-45 ℃ can be realized in practical use, and when electronic products, especially special products containing lithium batteries and the like which need to be stored and transported in a heat insulation way are packaged, the products can be effectively prevented from being heated;

2) The heat-resistant aging resistance of the whole diaphragm is remarkably improved, the service life of the BOPP diaphragm can be prolonged, and the pulverization time of a heat aging box test can be prolonged by more than 15%;

3) The mechanical property is excellent, the surface roughness and uniformity is high, and both sides have good anti-adhesion performance.

Detailed Description

The present invention will be described in further detail with reference to specific examples. Those skilled in the art will be able to implement the invention based on these teachings. Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

Unless otherwise specified, all the raw materials used in the examples of the present invention are commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all those known to those skilled in the art.

Example 1

The outer core material is prepared by the following steps:

dispersing 1000g of commercially available SBA-15-4.2 mesoporous silica nanoparticles (average particle size is 5.0 mu m) in 1500g of deionized water, adding 800g of n-octanol, ultrasonically dispersing uniformly, heating to 50 ℃, adding 1200g of butyl stearate, ultrasonically dispersing uniformly again, keeping the temperature for 10min after the n-octanol is completely molten, adding the liquid material into the n-46 paraffin at the rate of 45g per minute until the liquid material is completely added, treating in a boiling water bath until the total mass of the liquid material is less than or equal to 5000g, wherein the total mass of the product obtained in the embodiment is 49. 6g, and thus obtaining the outer core layer material.

The outer core material produced in this example was labeled as material a. In material A: the content of the mesoporous silica nano particle (SBA-15-4.2) is 20wt%, the content of paraffin is 40wt%, the content of n-octanol is 16wt%, and the content of butyl stearate is 24wt%.

Example 2

On the basis of example 1, with only varying component contents, several samples of outer core material were prepared:

and (2) material B: the content of mesoporous silica nanoparticles (SBA-15-4.2) is 10wt%, the content of paraffin is 36wt%, the content of n-octanol is 13.5wt%, and the content of butyl stearate is 40.5wt%;

and (3) material C: the content of mesoporous silica nano particles (SBA-15-4.2) is 15wt%, the content of paraffin is 34wt%, the content of n-octanol is 12.75wt%, and the content of butyl stearate is 38.25wt%;

and (D) material: the content of mesoporous silica nanoparticles (SBA-15-4.2) is 25wt%, the content of paraffin is 37.5wt%, the content of n-octanol is 15wt%, and the content of butyl stearate is 22.5wt%;

material E: the content of the mesoporous silica nano particle (SBA-15-4.2) is 30wt%, the content of paraffin is 35wt%, the content of n-octanol is 14wt%, and the content of butyl stearate is 21wt%.

Comparative example 1

On the basis of example 1, only the preparation method was changed as follows:

dispersing 1000g of commercially available SBA-15-4.2 mesoporous silica nanoparticles into 800g of n-octanol, heating to 50 ℃ after uniform ultrasonic dispersion, adding 1200g of butyl stearate, performing ultrasonic dispersion again, and mixing uniformly to obtain a liquid material, heating 2000g of 46# paraffin to 50 ℃ until the paraffin is completely melted, keeping the constant temperature for 10min, adding the liquid material into the 46# paraffin at a rate of 45g per minute, and obtaining the outer core layer material with the total mass of 5000g after the liquid material is added.

The outer core material produced in this comparative example was labeled as material F. In the material F: the content of mesoporous silica nano particles (SBA-15-4.2) is 20wt%, the content of paraffin wax is 40wt%, the content of n-octanol is 16wt%, and the content of butyl stearate is 24wt%.

Example 3

A double-sided extinction heat-resistant BOPP diaphragm,

the preparation method comprises the following steps:

1) Preparing an outer surface layer material, an outer core layer material, an inner core layer material and an inner surface layer material in sequence, respectively placing the prepared materials in different extruders for separate plasticization, controlling the extrusion temperature of the outer surface layer material, the inner core layer material and the inner surface layer material to be 235 ℃, controlling the extrusion temperature of the outer core layer material to be 172 ℃, and controlling the outer surface layer material to be filtered by a 125-mesh sieve in the extrusion process, the outer core layer material to be filtered by a 600-mesh sieve in the extrusion process, and the inner core layer material and the inner surface layer material to be filtered by a 325-mesh sieve;

the outer surface layer material consists of 42wt% of homopolymerized polypropylene, 6.5wt% of ethylene-propylene binary random copolymer polypropylene and the balance of High Density Polyethylene (HDPE);

selecting a material A for the outer core layer;

the inner core layer material consists of 1.5wt% of polyethylene oxide and the balance of homo-polypropylene;

the inner surface layer material consists of 32wt% of homopolymerized polypropylene, 6wt% of ethylene-propylene binary random copolymer polypropylene, 5.5wt% of ternary random copolymer polypropylene and the balance of High Density Polyethylene (HDPE);

2) Step 1), plasticizing the obtained melt, and sequentially carrying out compounding, sheet casting, longitudinal drawing and transverse drawing treatment to obtain a mother film;

in particular, the method comprises the following steps of,

in the compounding process, the thickness of the outer surface layer accounts for 8 percent of the total thickness, the thickness of the outer core layer accounts for 16 percent of the total thickness, the thickness of the inner core layer accounts for 71 percent of the total thickness, and the thickness of the inner surface layer accounts for 5 percent of the total thickness;

controlling the treatment temperature to be 38 ℃ in the sheet casting process;

heating to 46 ℃ before longitudinal drawing, keeping the temperature for 45min, then heating to 132 ℃ for longitudinal drawing, wherein the longitudinal drawing multiplying power is 7 times; heating to 46 ℃ before transverse drawing, keeping the temperature for 50min, then heating to 162 ℃ for transverse drawing, wherein the transverse drawing multiplying power is 10 times; the obtained mother membrane sequentially passes through 32 W.min.m ^-2 And performing double-sided corona treatment and 3d aging treatment to obtain a target product, namely a double-sided extinction heat-resistant BOPP membrane, wherein the thickness of the obtained membrane is about 50 mu m.

The BOPP membrane produced in this example was designated as film W-A.

Example 4

Based on the preparation parameters and procedure of example 3, the preparation of the BOPP separator was carried out replacing only the outer core material:

replacing the material A with the material B, and marking the prepared BOPP membrane as a membrane W-B;

replacing the material A with the material C, and marking the prepared BOPP membrane as a membrane W-C;

replacing the material A with the material D, and marking the prepared BOPP membrane as a membrane W-D;

replacing the material A with the material E, and marking the prepared BOPP membrane as a membrane W-E;

and replacing the material A with the material F to obtain the BOPP membrane marked as a membrane W-F.

Wherein, the fracture rate in the longitudinal drawing and transverse drawing processes of the film W-F preparation process is relatively higher, so the thickness of the mother film is reduced in equal proportion, the longitudinal drawing multiplying factor is reduced by 5 times, the transverse drawing multiplying factor is 7 times, and the thickness ratio of the final obtained product is almost approximately maintained.

Testing and characterization

The performance of the double-sided photoresist-quenched heat-type BOPP membranes prepared in examples 3 to 4 was tested and characterized. The results of the tests and characterization of the basic physical property index are shown in the following table.

And (3) characterization: W-A to F respectively indicate the test results of the films W-A to W-F.

From the table above, it can be seen that the change of the outer core layer material has relatively small influence on the basic physical property index of the prepared BOPP membrane, W-A-W-D basically can keep relatively excellent mechanical properties, the mechanical properties of the membrane W-E are relatively obviously reduced, and the mechanical properties of the membrane W-F are significantly reduced, so that the technical personnel further research and characterize the membrane.

Since the thickness of the BOPP film is extremely small, only tens of micrometersThe large local variations in roughness result in a marked change in the mechanical properties, in particular in the tensile strength and elongation at break properties, since the variations in roughness indicate large changes in the microscopic thickness, which easily lead to a large reduction in the structural strength in the local stress concentrations, and the like, so that this example is characterized and calculated in a conventional manner by roughness

Then calculating the difference S of the maximum change rate of the roughness _R By the difference S of the maximum rate of change of roughness _R Carrying out analysis;

specifically, the roughness maximum change rate difference S _R The calculation is made by the following formula:

in the formula: s. the _R Maximum rate of change difference of roughness, sa _min To measure the resulting minimum roughness, sa _max In order to measure the maximum roughness obtained,

is the arithmetic mean roughness.

From the above characterization and calculation, S of the films W-A to W-D can be seen _R Are all less than or equal to 6%, and S of the films W-F _R The value of 41.3% indicates that the roughness change rate is extremely large and local strength is weak or local stress concentration is very likely to occur, so that the mechanical properties are actually reduced, which is also the cause of the reduction in the film W-F production process. The main problem is the poor dispersibility of the mesoporous silica nanoparticles in the outer core material through characterization. Through research, the dispersibility of the mesoporous silica nanoparticles in an alcohol system can be kept relatively excellent, but after paraffin is added, the dispersion difficulty is increased, under the condition that water exists, uniformly dispersed liquid drops can be formed in the dispersion process due to the insolubility of the paraffin and the water, a water-oil interface is formed on the surface of the liquid drops, and mesoporous dioxide is oxidizedThe surface hydrophilicity of the silicon nanoparticles can be very effectively dispersed in this case. After the water is removed, the mesoporous silica nanoparticles further have the effect of adsorbing and fixing paraffin.

And then, performing heat resistance performance characterization:

coating the prepared BOPP diaphragm on the surface of a temperature measuring probe, carrying out three-layer sealing coating on the temperature measuring probe, and vacuumizing to ensure that the film is tightly attached to the film and the temperature measuring probe are tightly attached to each other so as to simulate the transportation condition of the conventional three-layer composite BOPP diaphragm for encapsulating lithium battery products, wherein the reading of the temperature measuring probe under the initial condition is 26 ℃ of the ambient room temperature at that time;

then the temperature measuring probe is moved to the environment with the temperature of 33 ℃, 36 ℃, 39 ℃, 42 ℃ and 45 ℃ respectively, the reading is carried out after the temperature is kept and the standing is carried out for 8 hours at constant temperature, and the comparison is carried out by taking a BOPP membrane which is commercially available and has a three-layer structural formula (namely, has an outer surface layer, a core layer and an inner surface layer) with the same thickness (50 mu m thickness) as a blank control.

The test results are shown in the following table.

From the test results in the table above, it can be seen that the film W-A, the film W-C and the film W-D all have relatively excellent heat insulation performance, and can realize heat insulation and temperature reduction of about 7.5-8 ℃ under the environment temperature condition of 45 ℃. Under the test condition of 45 ℃, the film W-B can show that oil stains appear on the cutting edge of the film material, and the film W-B does not have good heat resistance any more when subjected to a 39 ℃ test subsequently, which shows that the components of the inner outer core layer are obviously lost, so that the mesoporous silica nanoparticles can generate an effective fixing effect on the effective components of the outer core layer only by adding the mesoporous silica nanoparticles to a certain content. The oil stains appear on the cut edges of the membrane material of the membranes W-F, but the oil stains are not uniformly distributed, and the oil stains are found only under the test condition of 42 ℃, which shows that the oil stains appear, and the oil stains are also generated due to the non-uniform distribution of the mesoporous silica nano-particles.

According to the current use requirement, the temperature of the transportation environment is mostly about 42-45 ℃ in hot weather, a certain potential safety hazard is generated partially under the temperature condition and the potential safety hazard is easy to cause aging, the encapsulation of the BOPP diaphragm can effectively realize heat resistance and temperature reduction, and 8h test shows that the encapsulation of the BOPP diaphragm also meets the maximum possible time period of the high-temperature environment with the day as the period, namely the encapsulation of the double-sided light-extinction heat-resistant BOPP diaphragm can be well protected in the transportation process, and the potential safety hazard and the aging problem caused by overheating are avoided.

In addition, a low-temperature long-term heat aging test was carried out. The commercially available BOPP diaphragm with the three-layer structure and the equal thickness (50 mu m thickness) is used as up>A blank control, the pulverization time in up>A rotary thermal ageing oven at the test temperature of 45 ℃ is recorded as up>A control index, and the pulverization time of the film W-A, the film W-C and the film W-D prepared by the method is respectively prolonged by about 16.2 percent, 15.4 percent and 16.3 percent compared with the control index, so that the long-term heat-resistant stability of the diaphragm is remarkably improved.

In summary, the double-sided anti-light-blocking heat-resistant BOPP membrane has standard and good mechanical properties, excellent heat-blocking performance suitable for packaging and transportation, long-term heat-resistant stability and excellent use effect.

Claims

1. A preparation method of a double-sided extinction heat-resistant BOPP diaphragm is characterized in that,

the method comprises the following steps:

2. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 1,

36 to 48 weight percent of homopolymerized polypropylene, 6 to 8 weight percent of binary random copolymer polypropylene and the balance of high-density polyethylene;

28-35 wt% of homo-polypropylene, 5-7 wt% of binary random copolymer polypropylene, 4-7 wt% of ternary random copolymer polypropylene and the balance of high-density polyethylene;

3. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 2,

4. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 1,

15-25 wt% of mesoporous silica nano particles and the balance of liquid wax.

5. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 4,

the liquid wax comprises the following components in percentage by mass:

6. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 5, characterized in that,

the outer core material is prepared by the following method:

7. The method for preparing the double-sided extinction heat-resistant BOPP membrane as claimed in claim 4, 5 or 6, wherein the melting point of the paraffin is 44 ℃ and/or 46 ℃.

8. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 1,

step 2) the processing temperature of the sheet casting process is 35-40 ℃;

the treatment temperature of the longitudinal drawing process in the step 2) is 128-134 ℃, and the longitudinal drawing process is preheated to 44-50 ℃ before being heated to the treatment temperature and is kept for at least 45min at constant temperature;

9. The method for preparing the double-sided extinction heat-resistant BOPP membrane according to claim 1,

step 2) the corona treatment control strength is 30-35 W.min.m ^-2 ；

And 2) the aging treatment time is more than or equal to 3d.

10. A double-sided extinction heat-resistant BOPP diaphragm is characterized in that,

the thickness of the BOPP diaphragm is 48-52 mu m;

the BOPP diaphragm comprises an outer surface layer, an outer core layer, an inner core layer and an inner surface layer, wherein the thickness of each layer is as follows: