A modified BOPP film and its preparation method

Abstract

The present invention discloses a modified BOPP film and a preparation method thereof, belonging to the technical field of BOPP films. The modified BOPP film comprises, from top to bottom, a high-temperature resistant layer, a modified layer, and a high-temperature resistant layer. The high-temperature resistant layer comprises the following raw materials by weight: 90-94 parts homopolypropylene, 1 part thermosetting agent, 3-6 parts trimeric TBC cyanurate, and 2-3 parts anti-sticking agent; the modified layer comprises the following raw materials by weight: 85-90 parts homopolypropylene and 10-15 parts trimeric TBC cyanurate. The modified BOPP film can be used in aqueous environments, making it suitable for use as a water-based packaging material, and can also be used in high-temperature environments, making it suitable for use as a high-temperature protective film material. It also has good dimensional stability and high mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of BOPP films, and particularly relates to a modified BOPP film and a preparation method thereof. Background Art

[0002] There are many types of BOPP packaging films, but BOPP films that can be used in both aqueous and high-temperature environments are rare. This product places very high demands on the film's water resistance and high-temperature resistance. The film's mass loss rate within 30 days in an aqueous environment must be less than 0.5%, and its heat-resistant temperature must be between 170-180°C. At the same time, the film must have good dimensional stability during lamination.

[0003] However, under existing technical conditions, the mass loss rate of BOPP film in an aqueous environment within 30 days is greater than 1%, and the heat resistance temperature is lower than 150°C. These shortcomings will limit the application scope of the film. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a modified BOPP film and a preparation method thereof, which solves the problems in the prior art.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A modified BOPP film, comprising, from top to bottom, a high-temperature resistant layer, a modified layer and a high-temperature resistant layer;

[0007] The high temperature resistant layer comprises the following raw materials in parts by weight: 90-94 parts of homopolypropylene, 1 part of a thermal curing agent, 3-6 parts of trimerized TBC cyanurate, and 2-3 parts of an anti-blocking agent;

[0008] The modified layer comprises the following raw materials in parts by mass: 85-90 parts of homopolymer polypropylene and 10-15 parts of trimerized TBC cyanurate.

[0009] Furthermore, the trimerized TBC cyanurate is prepared by transesterification of melamine and tributyl citrate. The synthesis route of trimerized TBC cyanurate is as follows:

[0010]

[0011] Furthermore, the structural formula of the trimerized TBC cyanurate is:

[0012]

[0013] Furthermore, the anti-blocking agent comprises glass microspheres and homopolymer polypropylene, and the mass ratio of the glass microspheres to the homopolymer polypropylene is: (30-50): (50-70); the homopolymer polypropylene has a polymerization degree of 97-98% and a melt index of 2.0-3.0 g / 10 min.

[0014] Furthermore, the thermal curing agent is a homoaromatic anhydride.

[0015] Furthermore, the thickness of the modified BOPP film is 25-35 μm; preferably, the total thickness of the two high-temperature resistant layers is 10-20% of the thickness of the modified BOPP film.

[0016] The above-mentioned method for preparing a modified BOPP film comprises the following steps:

[0017] S1, adding the raw materials of the modified layer into the main extruder for melt extrusion, and then filtering through a filter to obtain a modified layer melt; adding the raw materials of the high-temperature resistant layer into the auxiliary extruder for melt extrusion, and then filtering through a filter to obtain a high-temperature resistant layer melt; wherein the melt extrusion temperature is 160-170°C.

[0018] S2, in the order of high temperature resistant layer melt, modified layer melt, and high temperature resistant layer melt, the melt is extruded at the die lip of the three-layer structure extruder to obtain a film; the film is attached to a chilled roller by a high-pressure air knife and rapidly cooled to form a cast sheet; the air knife pressure is maintained at 2.5-3MPa.

[0019] S3, longitudinally stretching the cast sheet into a sheet; the stretching speed is set to 250-275 mm / min.

[0020] S4, stretching the sheet transversely at a high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 165-175°C.

[0021] A plasticizer, wherein the plasticizer is trimerized TBC cyanurate, and its structural formula is:

[0022]

[0023] The above-mentioned plasticizer is used as a modifier in the preparation of BOPP film.

[0024] Beneficial effects of the present invention:

[0025] The present invention proposes a new plasticizer, trimer TBC cyanurate, and uses it to modify BOPP film. The prepared composite material can be used in an aqueous environment and is suitable for use as a water-based packaging material. It can also be used in a high-temperature environment and is suitable for use as a high-temperature resistant protective film material. It has good dimensional stability and high mechanical strength. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1

[0028] In this embodiment, a new plasticizer, trimerized TBC cyanurate, is proposed;

[0029] Trimeric TBC cyanurate is prepared by transesterification of melamine and tributyl citrate (TBC). The synthesis route of trimeric TBC cyanurate is as follows:

[0030]

[0031] The structural formula of trimer TBC cyanurate is:

[0032]

[0033] In this embodiment, an example of preparing trimerized TBC cyanurate is proposed, which specifically includes:

[0034] Step 1: Place the reaction bottle filled with nitrogen atmosphere into a constant temperature electric heating mantle and dry it at 300℃ for half an hour to remove the residual water in the bottle;

[0035] Step 2: After cooling, add 108 g of tributyl citrate, 13.2 g of melamine, and 3.5 g of diethyl zinc into the reaction flask, react at 90° C. for half an hour, and then stop introducing nitrogen;

[0036] Step 3: Distill the by-product butanol under vacuum operation of a vacuum pump until no more distilled material is left. The residual liquid is the obtained product, trimerized TBC cyanurate.

[0037] Experimental test:

[0038] The relevant parameters, composition, and structure of the sample were determined based on the test objectives. A series of performance studies, such as thermal stability, migration resistance, and mechanical properties, were conducted on BOPP films plasticized with 10 parts (1.2g) of trimerized TBC cyanurate, DOTP, and DINCH, respectively. The BOPP film addition level was 100 parts (12g).

[0039] 1) Thermal Stability Analysis: The thermal stability of three plasticizers and the plasticized BOPP composite was studied using a thermogravimetric analyzer (TGA209F1, Netzsch, Germany). Test conditions included a nitrogen flow rate of 50 mL / min, a sample heating rate of 20°C / min, and a test temperature range of 40°C to 600°C. Proteus analysis software was used to record the experimental thermal parameters of the different samples.

[0040] 2) Migration Resistance Analysis: Plasticizers must exhibit excellent migration stability. Therefore, BOPP composites plasticized with different plasticizers were placed in deionized water for extraction resistance. By comparing mass loss, the migration stability, and therefore safety, of the plasticizer in an aqueous environment was analyzed. Extraction resistance testing of the various plasticized BOPP material samples was conducted in accordance with the standard "ISO 175-2011 Plastics — Test method for determination of the effects of immersion by liquid chemicals."

[0041] 3) Mechanical Property Comparison: Plasticized BOPP composites were subjected to longitudinal tensile strength tests using a universal testing machine to evaluate mechanical properties such as tensile ductility, tensile strength, and elastic modulus. This allowed for a comparison of the plasticizing effects of different plasticizers. The mechanical properties of the materials were analyzed in accordance with GB / T 1040-2006, "Test Methods for Tensile Properties of Plastics."

[0042] Test results

[0043] 1) Table 1 lists the thermogravimetric data of BOPP materials plasticized with different plasticizers:

[0044] Table 1 Thermogravimetric data of plasticizer plasticized BOPP materials

[0045]

[0046] According to the data in Table 1, the initial decomposition temperatures (T) of DOTP and trimer TBC cyanurate are similar, at 233.5°C and 233.7°C, respectively. This indicates that the thermal stability of BOPP plasticized with DOTP and trimer TBC cyanurate is superior to that of the commercial plasticizer DINCH. However, trimer TBC cyanurate is more suitable for use in product operating conditions at higher temperatures. Therefore, the thermal stability ranking (by initial decomposition temperature T) is: trimer TBC cyanurate ≈ DOTP > DINCH.

[0047] 2) Table 2 lists the water resistance and environmental migration data of BOPP materials plasticized with different plasticizers:

[0048] Table 2 Water resistance and environmental migration data of plasticizer-plasticized BOPP materials

[0049]

[0050] Table 2 shows that in aqueous deionized water, all three plasticizers maintain good migration stability over a 30-day period. The mass loss rate of BOPP plasticized with trimer TBC cyanurate is the lowest, with virtually no migration from the BOPP matrix. This indicates that BOPP films containing trimer TBC cyanurate are suitable for use in aqueous environments and in some packaging materials.

[0051] 3) Table 3 lists the longitudinal tensile properties of BOPP materials plasticized with different plasticizers:

[0052] Table 3 Comparison of longitudinal tensile properties of plasticizer-plasticized BOPP materials

[0053]

[0054] Table 3 shows that the elongation at break of the BOPP material plasticized with trimer TBC cyanurate is higher than that of the other samples, reaching 468.5%. This indicates that the trimer TBC cyanurate-plasticized BOPP material exhibits the greatest flexibility, likely due to the presence of multiple nitrogen atoms in its molecular structure. These nitrogen atoms contribute to the softness of products in soft materials, making it a potential alternative to the commercial plasticizer DOTP. The maximum tensile strength of the trimer TBC cyanurate-plasticized BOPP material is similar to and higher than that of the other samples, indicating that its ability to withstand external forces is higher than that of the other samples. This is likely due to the uniform nitrogen-containing planar six-membered ring structure within the trimer TBC cyanurate molecular structure.

[0055] In summary, Tables 1, 2, and 3 show that the synthesized trimerized TBC cyanurate exhibits excellent tensile properties and high elongation at break when used in BOPP film, showing potential as a replacement for commercial plasticizers. It is also easy to process. The thermal stability and migration stability of BOPP film in aqueous environments are both improved compared to those of commercial plasticizers DINCH and DOTP. This demonstrates that this composite material can be used in both aqueous environments, making it suitable for water-based packaging materials, and in high-temperature environments, making it suitable for use as a heat-resistant protective film material, demonstrating its promising application prospects.

[0056] The following examples are used to illustrate the method of preparing a modified BOPP film using the new plasticizer trimer TBC cyanurate in Example 1;

[0057] Example 2

[0058] A modified BOPP film, comprising, from top to bottom, a high-temperature resistant layer, a modified layer, and a high-temperature resistant layer, wherein the film thickness is 25 μm, and the total thickness of the two high-temperature resistant layers is 10% of the thickness of the modified BOPP film;

[0059] Among them, the raw materials of the high-temperature resistant layer are composed of the following components in weight percentage: 90% homopolypropylene, 1% thermal curing agent, 6% modifier and 3% anti-blocking agent; the thermal curing agent is pyromellitic dianhydride, the modifier is trimer TBC cyanurate, and the anti-blocking agent is composed of 30wt% glass microspheres and 70wt% homopolypropylene, and the particle size of the glass microspheres is 2μm.

[0060] The raw materials of the modified layer are composed of the following components in weight percentage: 85% of homopolypropylene and 15% of a modifier; wherein the modifier is trimerized TBC cyanurate.

[0061] The degree of polymerization of the homopolypropylene is 97%, and the melt index is 2.0 g / 10 min.

[0062] The preparation method of the modified BOPP film comprises the following steps:

[0063] S1, adding the raw materials of each component of the modified layer into the main extruder for melt extrusion, and then filtering through a filter to obtain a modified layer melt; adding the raw materials of each component of the high-temperature resistant layer into the auxiliary extruder for melt extrusion, and then filtering through a filter to obtain a high-temperature resistant layer melt; wherein the melt extrusion temperature is 160°C.

[0064] S2, in the order of high temperature resistant layer melt, modified layer melt, and high temperature resistant layer melt, the melt is extruded at the die lip of the three-layer structure extruder to obtain a film; the film is attached to a chilled roller by a high-pressure air knife and rapidly cooled to form a casting sheet; the air knife pressure is maintained at 2.5 MPa.

[0065] S3, the cast sheet is longitudinally stretched into a sheet; the stretching speed is set to 250 mm / min.

[0066] S4, stretching the sheet transversely at a high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 165°C.

[0067] The above preparation method further includes introducing the prepared modified BOPP film into a traction system to flatten it, measuring the thickness with a β-ray thickness gauge, and then winding it to obtain a finished product.

[0068] Example 3

[0069] A modified BOPP film, comprising, from top to bottom, a high-temperature resistant layer, a modified layer, and a high-temperature resistant layer, wherein the film thickness is 30 μm, and the total thickness of the two high-temperature resistant layers is 15% of the thickness of the modified BOPP film;

[0070] Among them, the raw materials of the high-temperature resistant layer are composed of the following components in weight percentage: 92% homopolypropylene, 1% thermal curing agent, 5% modifier and 2% anti-blocking agent; the thermal curing agent is pyromellitic dianhydride, the modifier is trimer TBC cyanurate, and the anti-blocking agent is composed of 40wt% glass microspheres and 60wt% homopolypropylene, and the particle size of the glass microspheres is 3μm.

[0071] The raw materials of the modified layer are composed of the following components in percentage by weight: 87% homopolypropylene and 13% modifier; wherein the modifier is trimerized TBC cyanurate.

[0072] The degree of polymerization of the homopolypropylene is 97.5%, and the melt index is 2.5 g / 10 min.

[0073] The preparation method of the modified BOPP film comprises the following steps:

[0074] S1, adding the raw materials of each component of the modified layer into the main extruder for melt extrusion, and then filtering through a filter to obtain a modified layer melt; adding the raw materials of each component of the high-temperature resistant layer into the auxiliary extruder for melt extrusion, and then filtering through a filter to obtain a high-temperature resistant layer melt; wherein the melt extrusion temperature is 165°C.

[0075] S2, in the order of high temperature resistant layer melt, modified layer melt, and high temperature resistant layer melt, the melt is extruded at the die lip of the three-layer structure extruder to obtain a film; the film is attached to a chilled roller by a high-pressure air knife and rapidly cooled to form a casting sheet; the air knife pressure is maintained at 2.8 MPa.

[0076] S3, the cast sheet is longitudinally stretched into a sheet; the stretching speed is set to 265 mm / min.

[0077] S4, stretching the sheet transversely at a high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 170°C.

[0078] The above preparation method further includes introducing the prepared modified BOPP film into a traction system to flatten it, measuring the thickness with a β-ray thickness gauge, and then winding it to obtain a finished product.

[0079] Example 4

[0080] A modified BOPP film, comprising, from top to bottom, a high-temperature resistant layer, a modified layer, and a high-temperature resistant layer, wherein the film thickness is 35 μm, and the total thickness of the two high-temperature resistant layers is 20% of the thickness of the modified BOPP film;

[0081] Among them, the raw materials of the high-temperature resistant layer are composed of the following components in weight percentage: 94% homopolypropylene, 1% thermal curing agent, 3% modifier and 2% anti-blocking agent; the thermal curing agent is pyromellitic dianhydride, the modifier is trimer TBC cyanurate, and the anti-blocking agent is composed of 50wt% glass microspheres and 50wt% homopolypropylene, and the particle size of the glass microspheres is 3μm.

[0082] The raw materials of the modified layer are composed of the following components in percentage by weight: 90% homopolypropylene and 10% modifier; wherein the modifier is trimerized TBC cyanurate.

[0083] The degree of polymerization of the homopolypropylene is 98%, and the melt index is 3.0 g / 10 min.

[0084] The preparation method of the modified BOPP film comprises the following steps:

[0085] S1, adding the raw materials of each component of the modified layer into the main extruder for melt extrusion, and then filtering through a filter to obtain a modified layer melt; adding the raw materials of each component of the high-temperature resistant layer into the auxiliary extruder for melt extrusion, and then filtering through a filter to obtain a high-temperature resistant layer melt; wherein the melt extrusion temperature is 170°C.

[0086] S2, in the order of high temperature resistant layer melt, modified layer melt, and high temperature resistant layer melt, the melt is extruded at the die lip of the three-layer structure extruder to obtain a film; the film is attached to a chilled roller by a high-pressure air knife and rapidly cooled to form a casting sheet; the air knife pressure is maintained at 3MPa.

[0087] S3, the cast sheet is longitudinally stretched into a sheet; the stretching speed is set to 275 mm / min.

[0088] S4, stretching the sheet transversely at a high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 175°C.

[0089] The above preparation method further includes introducing the prepared modified BOPP film into a traction system to flatten it, measuring the thickness with a β-ray thickness gauge, and then winding it to obtain a finished product.

[0090] Comparative Example

[0091] This comparative example discloses a method for preparing a BOPP film. The only difference between this method and Example 2 is that no modifier is added to the materials of the high-temperature resistant layer and the modified layer; instead, the modifier component is replaced with homopolypropylene. All other conditions and preparation processes are the same as those in Example 2.

[0092] Experimental testing

[0093] The BOPP films prepared in Examples 2-4 and the comparative example were tested for water resistance and high temperature resistance. The test results are shown in Table 4.

[0094] Table 4 Performance test results of BOPP films prepared in Examples 1-3 and Comparative Examples

[0095]

[0096] As can be seen from Table 4, the BOPP films prepared in Examples 2-4 of the present invention have lower aqueous environmental mass loss rates, higher melting points, and lower thermal shrinkage rates compared to the comparative examples.

[0097] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0098] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A plasticizer, characterized in that The plasticizer is trimerized TBC cyanurate, and its structural formula is:

2. A plasticizer according to claim 1, characterized in that The trimerized TBC cyanurate is prepared by transesterification of melamine and tributyl citrate. The synthesis route of trimerized TBC cyanurate is as follows:

3. A modified BOPP film, characterized in that: From top to bottom, it includes: high temperature resistant layer, modified layer and high temperature resistant layer; The high temperature resistant layer comprises the following raw materials in parts by weight: 90-94 parts of homopolypropylene, 1 part of a thermal curing agent, 3-6 parts of trimerized TBC cyanurate, and 2-3 parts of an anti-blocking agent; The modified layer comprises the following raw materials in parts by mass: 85-90 parts of homopolymer polypropylene and 10-15 parts of trimerized TBC cyanurate; The structural formula of the trimerized TBC cyanurate is:

4. The modified BOPP film according to claim 3, characterized in that: The anti-blocking agent comprises glass microspheres and homopolymer polypropylene, wherein the mass ratio of the glass microspheres to the homopolymer polypropylene is (30-50): (50-70); the polymerization degree of the homopolymer polypropylene is 97-98%, and the melt index is 2.0-3.0 g / 10 min.

5. The modified BOPP film according to claim 3, characterized in that: The thermal curing agent is a homoaromatic acid anhydride.

6. The modified BOPP film according to claim 3, characterized in that: The thickness of the modified BOPP film is 25-35 μm; the total thickness of the high-temperature resistant layer is 10-20% of the thickness of the modified BOPP film.

7. The method for preparing a modified BOPP film according to any one of claims 3 to 6, characterized in that: The following steps are involved: S1, adding the raw materials of the modified layer into the main extruder for melt extrusion, and then filtering through a filter to obtain a modified layer melt; adding the raw materials of the high-temperature resistant layer into the auxiliary extruder for melt extrusion, and then filtering through a filter to obtain a high-temperature resistant layer melt; wherein the melt extrusion temperature is 160-170°C; S2, in the order of the high temperature resistant layer melt, the modified layer melt, and the high temperature resistant layer melt, the film is extruded at the die lip of the three-layer structure extruder; the film is attached to a chilled roller using a high pressure air knife to form a cast sheet; the air knife pressure is maintained at 2.5-3 MPa; S3, longitudinally stretching the cast sheet into a sheet; the stretching speed is set to 250-275 mm / min; S4, stretching the sheet transversely at a high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 165-175°C.

8. Use of the plasticizer according to claim 1 or 2 as a modifier in the preparation of BOPP film.

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