Modified BOPP film and preparation method thereof

Abstract

The invention discloses a modified BOPP film and a preparation method thereof, and belongs to the technical field of BOPP films. The modified BOPP film sequentially comprises a high-temperature-resistant layer, a modified layer and a high-temperature-resistant layer from top to bottom, the high-temperature-resistant layer is prepared from the following raw materials in parts by mass: 90 to 94 parts of homo-polypropylene, 1 part of a thermal curing agent, 3 to 6 parts of trimeric TBC cyanurate and 2 to 3 parts of an anti-sticking agent; the modified layer is prepared from the following raw materials in parts by mass: 85 to 90 parts of homo-polypropylene and 10 to 15 parts of trimeric TBC cyanurate. The modified BOPP film not only can be used in a water-based environment and is suitable for being used as a water-based packaging material, but also can be used in a high-temperature environment and is suitable for being used as a high-temperature-resistant protective film material, and the modified BOPP film is good in dimensional stability and high in mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of BOPP films, and in particular 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 has very high requirements on the water resistance and high-temperature resistance of the film. The mass loss rate of the film in an aqueous environment within 30 days is required to be less than 0.5%, and the heat resistance temperature is required to be 170-180°C. At the same time, the film is required to 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 of 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 mass: 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-sticking agent;

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

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

[0010]

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

[0012]

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

[0014] Furthermore, the thermal curing agent is a homoaromatic acid 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, they are extruded together 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 to form a casting; 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 high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 165-175°C.

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

[0022]

[0023] Furthermore, the trimerized TBC cyanurate is prepared by transesterification reaction of melamine and tributyl citrate, and the synthesis route of trimerized TBC cyanurate is:

[0024]

[0025] The above-mentioned plasticizer is used as a modifier in the preparation of BOPP film.

[0026] Beneficial effects of the present invention:

[0027] The invention proposes a novel plasticizer trimer TBC cyanurate, and after using it to modify BOPP film, the prepared composite material can be used in an aqueous environment and is suitable for being a water-based packaging material, and can also be used in a high-temperature environment and is suitable for being a high-temperature resistant protective film material, and has good dimensional stability and high mechanical strength. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] In this embodiment, a new plasticizer, trimerized TBC cyanurate, is proposed;

[0031] Trimeric TBC cyanurate is prepared by transesterification reaction of melamine and tributyl citrate (TBC). The synthesis route of trimeric TBC cyanurate is:

[0032]

[0033] The structural formula of trimer TBC cyanurate is:

[0034]

[0035] In this embodiment, a preparation example of trimerized TBC cyanurate is proposed, which specifically includes:

[0036] Step 1: Place the reaction bottle filled with nitrogen atmosphere into a constant temperature electric heating jacket and continue drying at 300°C for half an hour to remove the residual water in the bottle;

[0037] 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 bottle, react at 90° C. for half an hour, and then stop introducing nitrogen;

[0038] Step 3: Distill the by-product butanol under vacuum operation of a vacuum pump until no more distilled substances are left, and the residual liquid is the obtained product, trimerized TBC cyanurate.

[0039] Experimental test:

[0040] According to the test purpose, the relevant parameters, composition and structure of the sample were measured, and a series of performance studies were conducted on BOPP films plasticized with 10 parts (1.2g) of trimerized TBC cyanurate, DOTP and DINCH, such as thermal stability, migration resistance and mechanical properties. The addition amount of BOPP film was 100 parts (12g).

[0041] 1) Thermal stability analysis: The thermal stability of three plasticizers and plasticized BOPP composites was studied using a thermogravimetric analyzer (TGA209F1, Netzsch, Germany). Test conditions: nitrogen flow rate was set to 50 mL / min, sample heating rate was set to 20 °C / min, and the test temperature range was set to 40 °C to 600 °C. Proteus analysis software was used to record the experimental thermal parameters of different samples.

[0042] 2) Analysis of migration resistance: Plasticizers need to have excellent migration resistance stability. Therefore, BOPP composite materials plasticized with different plasticizers are placed in deionized water for extraction resistance. By comparing the mass loss, the migration stability of plasticizers in aqueous environments, that is, safety, is analyzed. The extraction resistance performance of different plasticized BOPP material samples is tested with reference to the standard "ISO175-2011 Plastics - Test method for determination of immersion effects of liquid chemicals".

[0043] 3) Mechanical properties comparison: The plasticized BOPP composite material was subjected to longitudinal tensile strength tests using a universal testing machine to evaluate its mechanical properties, such as tensile ductility, tensile strength, elastic modulus, etc., and then the plasticizing effects of different plasticizers were compared. The mechanical properties test standard of the material was analyzed in accordance with GB / T 1040-2006 "Test Methods for Tensile Properties of Plastics".

[0044] Test Results

[0045] 1) Table 1 lists the thermogravimetric data of BOPP materials plasticized with different plasticizers:

[0046] Table 1 Thermogravimetric data of plasticizer plasticized BOPP materials

[0047]

[0048] According to the data in Table 1, the initial decomposition temperatures (T) of DOTP and trimer TBC cyanurate are basically close, 233.5℃ and 233.7℃ respectively, indicating that the thermal stability of BOPP materials plasticized by DOTP and trimer TBC cyanurate is better than that of the commercial plasticizer DINCH. However, in comparison, the plasticizer trimer TBC cyanurate is more suitable for use under higher temperature conditions of product working conditions. Therefore, the thermal stability ranking (sorted by initial decomposition temperature T): trimer TBC cyanurate ≈ DOTP>DINCH.

[0049] 2) Table 2 lists the water resistance and environmental migration data of BOPP materials plasticized with different plasticizers:

[0050] Table 2 Water resistance and environmental migration data of plasticizer plasticized BOPP materials

[0051]

[0052] It can be seen from Table 2 that in deionized water in an aqueous environment, the three plasticizers can maintain good migration stability within 30 days, among which the mass loss rate of the BOPP material plasticized with trimer TBC cyanurate is the lowest, and it basically does not migrate out of the BOPP matrix, indicating that the BOPP film with the addition of trimer TBC cyanurate can be used in aqueous environments and some packaging materials.

[0053] 3) Table 3 lists the longitudinal tensile properties of BOPP materials plasticized with different plasticizers:

[0054] Table 3 Comparison of longitudinal tensile properties of plasticizer-plasticized BOPP materials

[0055]

[0056] According to Table 3, the elongation at break of the trimer TBC cyanurate plasticized BOPP material is higher than that of other samples, reaching 468.5%, which shows that the flexibility of the trimer TBC cyanurate plasticized BOPP material is the best, which may be related to the role of multiple nitrogen atoms in the molecular structure. Multiple nitrogen atoms are beneficial to improve the softness of products in soft materials, so it has the potential to replace the commercial plasticizer DOTP. The maximum tensile strength of the trimer TBC cyanurate plasticized BOPP material is close to and higher than that of other samples, indicating that its limit of withstanding external forces is higher than that of the other samples, which may be determined by the uniform nitrogen-containing planar six-membered ring structure in the trimer TBC cyanurate molecular structure.

[0057] In summary, it can be seen from Table 1, Table 2, and Table 3 that the synthesized trimerized TBC cyanurate has good tensile properties and high elongation at break for BOPP film, has the potential to replace commercial plasticizers, and is easy to process. The thermal stability and migration stability of BOPP film in water environment are improved compared with commercial plasticizers DINCH and DOTP. This shows that the composite material can be used in water-based environment, suitable for water-based packaging materials, and can also be used in high temperature environment, suitable for high temperature resistant protective film materials, and has good application prospects.

[0058] The following examples are used to specifically illustrate the method of preparing a modified BOPP film using the new plasticizer trimer TBC cyanurate in Example 1;

[0059] Example 2

[0060] 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;

[0061] 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 anhydride, 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.

[0062] The raw materials of the modified layer are composed of the following components in weight percentage: 85% of homopolymer polypropylene and 15% of modifier; wherein the modifier is trimerized TBC cyanurate.

[0063] The degree of polymerization of the homopolymer polypropylene is 97%, and the melt index is 2.0 g / 10 min.

[0064] The preparation method of the modified BOPP film comprises the following steps:

[0065] 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.

[0066] S2, in the order of high temperature resistant layer melt, modified layer melt and high temperature resistant layer melt, they are extruded together at the die lip of a three-layer structure extruder to obtain a film; a high pressure air knife is used to attach the film to a chilled roller and rapidly cool it to form a casting sheet; the air knife pressure is maintained at 2.5 MPa.

[0067] S3, the cast sheet is longitudinally stretched into a sheet; the stretching speed is set to 250 mm / min.

[0068] S4, stretching the sheet transversely at high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 165°C.

[0069] The above preparation method also 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 rolling it up to obtain a finished product.

[0070] Example 3

[0071] 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;

[0072] 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 anhydride, 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.

[0073] The raw materials of the modified layer are composed of the following components in weight percentage: 87% homopolymer polypropylene and 13% modifier; wherein the modifier is trimerized TBC cyanurate.

[0074] The degree of polymerization of the homopolymer polypropylene is 97.5%, and the melt index is 2.5 g / 10 min.

[0075] The preparation method of the modified BOPP film comprises the following steps:

[0076] 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.

[0077] S2, in the order of high temperature resistant layer melt, modified layer melt and high temperature resistant layer melt, they are extruded together 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 to form a casting; the air knife pressure is maintained at 2.8 MPa.

[0078] S3, the cast sheet is longitudinally stretched into a sheet; the stretching speed is set to 265 mm / min.

[0079] S4, stretching the sheet transversely at high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 170°C.

[0080] The above preparation method also 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 rolling it up to obtain a finished product.

[0081] Example 4

[0082] 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;

[0083] 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 anhydride, 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.

[0084] The raw materials of the modified layer are composed of the following components in weight percentage: 90% homopolymer polypropylene and 10% modifier; wherein the modifier is trimerized TBC cyanurate.

[0085] The degree of polymerization of the homopolymer polypropylene is 98%, and the melt index is 3.0 g / 10 min.

[0086] The preparation method of the modified BOPP film comprises the following steps:

[0087] 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.

[0088] S2, in the order of high temperature resistant layer melt, modified layer melt and high temperature resistant layer melt, they are extruded together at the die lip of a three-layer structure extruder to obtain a film; a high pressure air knife is used to attach the film to a chilled roller and rapidly cool it to form a casting sheet; the air knife pressure is maintained at 3MPa.

[0089] S3, the cast sheet is longitudinally stretched into a sheet; the stretching speed is set to 275 mm / min.

[0090] S4, stretching the sheet transversely at high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 175°C.

[0091] The above preparation method also 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 rolling it up to obtain a finished product.

[0092] Comparative Example

[0093] This comparative example discloses a method for preparing a BOPP film, which differs from Example 2 only in that no modifier is added to the materials of the high temperature resistant layer and the modified layer, and the modifier component is replaced with homopolymer polypropylene; the other conditions and preparation process are the same as those of Example 2.

[0094] Experimental testing

[0095] The BOPP films prepared in the above Examples 2-4 and the comparative example were tested for water resistance and high temperature resistance. The test results are shown in Table 4.

[0096] Table 4 Performance test results of BOPP films prepared in Examples 1-3 and Comparative Examples

[0097]

[0098]

[0099] 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.

[0100] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0101] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

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 reaction of melamine and tributyl citrate. The synthesis route of trimerized TBC cyanurate is:

3. A modified BOPP film, characterized in that: From top to bottom, it includes: a high temperature resistant layer, a modified layer and a high temperature resistant layer; The high temperature resistant layer comprises the following raw materials in parts by mass: 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-sticking agent; The modified layer comprises the following raw materials in parts by weight: 85-90 parts of homopolymer polypropylene and 10-15 parts of trimerized TBC cyanurate.

4. A modified BOPP film according to claim 3, characterized in that: The trimerized TBC cyanurate is prepared by transesterification reaction of melamine and tributyl citrate. The synthesis route of trimerized TBC cyanurate is:

5. A modified BOPP film according to claim 3 or 4, characterized in that: The structural formula of the trimerized TBC cyanurate is:

6. The modified BOPP film according to claim 3, characterized in that: The anti-adhesive 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.

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

8. 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 two high temperature resistant layers is 10-20% of the thickness of the modified BOPP film.

9. The method for preparing a modified BOPP film according to any one of claims 3 to 8, 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 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 to form a casting; the air knife pressure is maintained at 2.5-3MPa; 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 high temperature and cooling it to obtain a modified BOPP film; wherein the transverse stretching temperature is 165-175°C.

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

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