Modified resin and preparation method therefor, stiffening masterbatch, and BOPP thin film and preparation method therefor

Abstract

The present application relates to the technical field of polymer materials, and discloses a modified resin and a preparation method therefor, a stiffening masterbatch, and a BOPP thin film and a preparation method therefor. The modified resin disclosed in the present application is obtained by grafting and modifying a hydrogenated petroleum resin with a bio-based carboxylic acid monomer. The modified resin has a softening point of 120-165°C, a yellowness index of less than or equal to 15, a volatile organic compound content of less than or equal to 500 ppm, and an acid value of 0.1-25 mgKOH / kg. The raw materials thereof are widely available, and the volatile organic compound content of the modified resin is low. The modified resin is suitable for preparing a BOPP thin film with good optical performance, mechanical properties, and thermodynamic properties.

Description

Modified resin and preparation method thereof, rigidity-enhancing masterbatch, BOPP film and preparation method thereof

[0001] This application claims priority to Chinese patent application No. 202311718418.1, filed on December 13, 2023. This application incorporates the entire text of the aforementioned Chinese patent application. Technical Field

[0002] The present application relates to the technical field of polymer materials, and in particular to a modified resin and a preparation method thereof, a rigidity-enhancing masterbatch, a BOPP film and a preparation method thereof. Background Art

[0003] Polypropylene (PP) is a thermoplastic polymer formed from the polymerization of propylene monomers. It boasts excellent properties, including heat resistance, chemical resistance, UV resistance, and high mechanical strength, and has been widely used in a variety of fields. Biaxially oriented polypropylene film (BOPP film) is widely used in packaging for food, candy, cigarettes, tea, juice, milk, and textiles due to its lightweight, non-toxic, odorless, moisture-resistant, and mechanical properties. However, BOPP film's relatively poor rigidity and thermal stability limit its application.

[0004] Currently, nucleation modification is commonly used to improve the rigidity of polypropylene materials. For example, researchers have found that adding cage-type silsesquioxane-loaded substituted aromatic heterocyclic phosphates or salt nucleating agents to polypropylene materials can increase rigidity and transmittance, but according to test results, its transmittance-enhancing effect is limited.

[0005] In addition, polypropylene materials prepared by existing modification methods often have excessively high volatile organic compound content, which is not environmentally friendly.

[0006] Therefore, there is an urgent need to provide a polypropylene material with good rigidity, thermal stability, and transparency, as well as a more environmentally friendly preparation method, so as to expand the application field of BOPP film.

[0007] Summary of the Invention

[0008] The main purpose of this application is to provide a modified resin and its preparation method, a rigidity-enhancing masterbatch, a BOPP film and its preparation method, so as to solve the problems of insufficient rigidity, thermal stability, and transparency of BOPP film in the prior art and excessively high content of volatile organic compounds.

[0009] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a modified resin is provided, which is obtained by grafting and modifying hydrogenated petroleum resin with bio-based carboxylic acid monomers, and has a softening point of 120-165°C, a yellowness index ≤15, a volatile organic compound content ≤500ppm, and an acid value of 0.1-25mgKOH / g.

[0010] Furthermore, the softening point of the hydrogenated petroleum resin is 125-145°C, the yellowness index is ≤7, and the aromaticity is 0.01%-15%; and / or the bio-based carboxylic acid monomer is at least one of 3-hydroxypropionic acid, 2,5-furandicarboxylic acid, abietic acid, dehydroabietic acid, dehydroabietic acid, 2,2-dimethylsuccinic anhydride, 2-dimethylsuccinic anhydride, butylsuccinic anhydride, 2-octenylsuccinic anhydride, ricinoleic acid, dehydrated ricinoleic acid, itaconic acid, and hexylitaconic acid.

[0011] According to the second aspect of the present application, there is provided a method for preparing the above-mentioned modified resin, comprising the following steps:

[0012] S1, adding hydrogenated petroleum resin, bio-based carboxylic acid monomer and antioxidant to a first solvent to obtain a mixed solution;

[0013] S2, then adding an initiator to the mixed solution to react and obtain a reaction product;

[0014] S3, removing the first solvent from the reaction product, then eluting unreacted bio-based carboxylic acid monomer with a second solvent, and drying to obtain a modified resin.

[0015] Furthermore, the first solvent is a mixed solution of xylene and N,N-dimethylformamide (DMF); and / or

[0016] The second solvent is at least one of ether, phenethyl ether, ethanol, methanol, isopropanol, isobutanol, acetone, methyl acetone, butanone, ethyl acetate, and methyl acetate; and / or

[0017] The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant; and / or

[0018] The initiator is at least one of dicumyl peroxide (DCP), dibenzoyl peroxide (BPO), bis(tert-butylperoxyisopropyl)benzene, 2-methyl ethyl ketone peroxide, azobisisobutyronitrile (AIBN), and azobisisoheptanenitrile; and / or

[0019] The mass ratio of the hydrogenated petroleum resin to the bio-based carboxylic acid monomer is (49.5-69.5): (0.1-15), the mass ratio of the hydrogenated petroleum resin to the antioxidant is (49.5-69.5): (0.1-0.5), the mass ratio of the hydrogenated petroleum resin to the first solvent is (49.5-69.5): (30-50), and the mass ratio of the hydrogenated petroleum resin to the initiator is (49.5-69.5): (0.05-2); and / or

[0020] In the above S2, the reaction temperature is 70-200°C and the reaction time is 0.25-3h; and / or

[0021] In the above S3, the first solvent is removed under the conditions of a pressure of 5-15 kPa and a temperature of 70-115° C.; and / or

[0022] In the above S3, drying is performed under a vacuum environment at 50-90°C.

[0023] Furthermore, in the first solvent, the mass ratio of xylene to N,N-dimethylformamide is 1:(0.3-2); and / or

[0024] The amount of the second solvent added is 0.5% to 50% of the mass of the reaction product after removing the first solvent; and / or

[0025] The hindered phenol antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 330, and antioxidant 3114; and / or

[0026] The phosphite antioxidant is at least one of antioxidant 168 and antioxidant 626.

[0027] According to the third aspect of the present application, a stiffening masterbatch is also disclosed. The stiffening masterbatch comprises the modified resin and a first polypropylene resin, wherein the mass ratio of the modified resin to the first polypropylene resin is 1:(0.8-1.2).

[0028] According to a fourth aspect of the present application, a BOPP film is disclosed, comprising a first layer, an intermediate layer, and a second layer connected in sequence; wherein the material of the intermediate layer comprises the above-mentioned stiffening masterbatch and the second polypropylene resin, and the mass ratio of the second polypropylene resin to the stiffening masterbatch in the intermediate layer is 1:(0.2-0.4); the mass ratio of the total mass of the first layer and the second layer to the mass of the intermediate layer is 1:(0.2-0.6), and the mass ratio of the first layer to the second layer is 1:(0.75-1.25); the material of the first layer and the second layer comprises the second polypropylene resin.

[0029] Furthermore, the first polypropylene resin and the second polypropylene resin in the above-mentioned rigid masterbatch are homopolymer polypropylene resins, and the melt flow rates of the first polypropylene resin and the second polypropylene resin measured at 230°C and 2.16kg are each independently 2-4g / 10min; the tensile yield strength of the first polypropylene resin is ≥25MPa, the tensile stress at break is ≥15MPa, the isotactic index is ≥90%, the Vicat softening point is ≥150°C, and the ash content is ≤0.03%; the tensile yield strength of the second polypropylene resin is ≥25MPa, the tensile stress at break is ≥15MPa, the isotactic index is ≥90%, the Vicat softening point is ≥150°C, and the ash content is ≤0.03%; and / or

[0030] When the thickness of the BOPP film is 30 μm, the longitudinal elastic modulus of the BOPP film is ≥1700 MPa, the longitudinal heat shrinkage rate is 3%-12%, the transverse heat shrinkage rate is 3%-12%, the haze is ≤2%, and the heat sealing strength measured at 135°C for 0.3s is ≥2.4 N / 15mm.

[0031] According to a fifth aspect of the present application, a method for preparing a BOPP film is disclosed, comprising the following steps:

[0032] S1, adding the modified resin and the first polypropylene resin into a screw extruder for extrusion and granulation to obtain a stiffening masterbatch;

[0033] S2, adding the stiffening masterbatch into the screw extruder, adding the raw materials of the first layer and the second layer into their respective auxiliary extruders, the three layers of material converge at the die head and flow out, cool, and are stretched by a film biaxial stretching instrument to obtain a BOPP film.

[0034] Furthermore, in the above S1, the temperature of the screw extruder is 160-240°C, and the screw speed is 150-300 r / min; and / or

[0035] In the above S2, stretching is divided into longitudinal stretching and transverse stretching. The longitudinal stretching conditions are: preheating temperature 220-280°C, stretching temperature 120-150°C, and stretching ratio 4.0-6.0. The transverse stretching conditions are: preheating temperature 220-280°C, stretching temperature 150-180°C, setting temperature 25-50°C, and stretching ratio 8.0-10.0.

[0036] By applying the technical solution of the present application, the hydrogenated petroleum resin modified by grafting of bio-based carboxylic acid monomers provided by the present application is used as a rigidity-enhancing raw material. After being blended with a polypropylene material, the polypropylene material can be induced to nucleate and crystallize in the α-crystal form, so that it forms smaller and more uniform spherulites, thereby facilitating the improvement of the rigidity, optical properties and thermodynamic properties of BOPP film products. In addition, the BOPP film prepared using the above-mentioned modified resin has a lower content of volatile organic compounds and better environmental performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a Fourier transform infrared spectra of the modified resin and hydrogenated petroleum resin in Example 1;

[0038] Figure 2 is the modified resin and hydrogenated petroleum resin in Example 1 1 H-NMR spectrum; DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the embodiments.

[0040] As described in the background of this application, existing BOPP films suffer from relatively low stiffness, insufficient transparency, and insufficient thermal stability. To address these issues, a typical embodiment of this application provides a modified resin obtained by grafting a hydrogenated petroleum resin with a bio-based carboxylic acid monomer. The modified resin has a softening point of 120-165°C, a yellowness index of ≤15, a volatile organic compound content of ≤500 ppm, and an acid value of 0.1-25 mgKOH / g.

[0041] The hydrogenated petroleum resin grafted with bio-based carboxylic acid monomers has a relatively low content of volatile organic compounds. Blending the modified resin with polypropylene resin can induce polypropylene to crystallize in the α-crystal form to form finer grains, which helps to improve the mechanical, optical and thermodynamic properties of BOPP film.

[0042] As a preferred embodiment of the present application, the softening point of the hydrogenated petroleum resin is 125-145°C, the yellowness index is ≤7, and the aromaticity is 0.01%-15%; and / or the bio-based carboxylic acid monomer is at least one of 3-hydroxypropionic acid, 2,5-furandicarboxylic acid, abietic acid, dehydroabietic acid, dehydroabietic acid, 2,2-dimethylsuccinic anhydride, 2-dimethylsuccinic anhydride, butylsuccinic anhydride, 2-octenylsuccinic anhydride, ricinoleic acid, dehydrated ricinoleic acid, itaconic acid, and hexylitaconic acid.

[0043] The aforementioned performance restrictions on hydrogenated petroleum resins are intended to achieve a balance between rigidity and transparency in BOPP film, ensuring excellent rigidity, transparency, and thermal stability while also maintaining a certain level of heat-seal strength. Modifying hydrogenated petroleum resins with the aforementioned bio-based carboxylic acid monomers can lower their softening point, contributing to a reduction in the volatile organic compound content of BOPP film and minimizing environmental pollution.

[0044] In another typical embodiment of the present application, a method for preparing a modified resin is provided, comprising the following steps:

[0045] S1, adding hydrogenated petroleum resin, bio-based carboxylic acid monomer and antioxidant to a first solvent to obtain a mixed solution;

[0046] S2, then adding an initiator to the mixed solution to react and obtain a reaction product;

[0047] S3, removing the first solvent from the reaction product, then eluting unreacted bio-based carboxylic acid monomer with a second solvent, and drying to obtain a modified resin.

[0048] The above preparation method is simple. By preparing the modified resin under the above conditions, the carboxylic acid monomer can be quickly grafted onto the hydrogenated petroleum resin, and it helps to inhibit color degradation, prepare a modified resin with a lower yellowness index, and improve the optical properties of the prepared BOPP film.

[0049] As a preferred embodiment of the present application, the first solvent is a mixed solution of xylene and N,N-dimethylformamide; and / or

[0050] The second solvent is at least one of ether, phenethyl ether, ethanol, methanol, isopropanol, isobutanol, acetone, methyl acetone, butanone, ethyl acetate, and methyl acetate; and / or

[0051] The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant; and / or

[0052] The initiator is at least one of dicumyl peroxide, dibenzoyl peroxide, bis(tert-butylperoxyisopropyl)benzene, 2-methyl ethyl ketone peroxide, azobisisobutyronitrile and azobisisoheptanenitrile; and / or

[0053] The mass ratio of the hydrogenated petroleum resin to the bio-based carboxylic acid monomer is (49.5-69.5): (0.1-15), the mass ratio of the hydrogenated petroleum resin to the antioxidant is (49.5-69.5): (0.1-0.5), the mass ratio of the hydrogenated petroleum resin to the first solvent is (49.5-69.5): (30-50), and the mass ratio of the hydrogenated petroleum resin to the initiator is (49.5-69.5): (0.05-2); and / or

[0054] In the above S2, the reaction temperature is 70-200°C and the reaction time is 0.25-3h; and / or

[0055] In the above S3, the first solvent is removed under the conditions of a pressure of 5-15 kPa and a temperature of 70-115° C.; and / or

[0056] In the above S3, drying is performed under a vacuum environment at 50-90°C.

[0057] The type of first solvent affects the grafting rate of the modified resin. Using a combination of xylene and N,N-dimethylformamide can achieve a relatively high grafting rate, thereby improving the rigidity of polypropylene materials while also exhibiting a low yellowness index, making it suitable for a variety of applications. Using at least one of these components as the second solvent can effectively elute unreacted bio-based carboxylic acid monomers, reducing the product's volatile organic compound content and improving the mechanical, optical, and environmental performance of BOPP film. Initiating the reaction under these conditions allows for efficient grafting modification of hydrogenated petroleum resins with minimal initiator, while simultaneously suppressing color degradation.

[0058] As a preferred embodiment of the present application, in the first solvent, the mass ratio of xylene to N,N-dimethylformamide is 1:(0.3-2).

[0059] The above-mentioned limitation on the mass ratio of the two components in the first solvent can make the modified resin have a higher grafting rate, while the yellowness index of the modified resin will not change significantly, and it is more suitable for improving the comprehensive properties of BOPP film.

[0060] As a preferred embodiment of the present application, the amount of the second solvent added is 0.5%-50% of the mass of the reaction product after removing the first solvent.

[0061] The above-mentioned limitation on the amount of the second solvent is intended to effectively remove unreacted bio-based carboxylic acid monomers.

[0062] Typically, but not limiting, the hindered phenol antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 330, and antioxidant 3114; the phosphite antioxidant is at least one of antioxidant 168 and antioxidant 626.

[0063] In a typical embodiment of the present application, a stiffening masterbatch is also disclosed. The stiffening masterbatch comprises the modified resin and a first polypropylene resin, wherein the mass ratio of the modified resin to the first polypropylene resin is 1:(0.8-1.2).

[0064] Using the above-mentioned ingredients as a rigidity-enhancing masterbatch can induce polypropylene to form an excellent nucleation crystal form, thereby simultaneously improving its rigidity and toughness without reducing its impact strength, improving its heat deformation resistance, and reducing its thermal shrinkage. The prepared BOPP film has high transparency and low volatile organic compound content.

[0065] In a typical embodiment of the present application, a BOPP film is disclosed, which includes a first layer, an intermediate layer, and a second layer connected in sequence; wherein the material of the intermediate layer includes the above-mentioned stiffening masterbatch and the second polypropylene resin, and the mass ratio of the second polypropylene resin to the stiffening masterbatch in the intermediate layer is 1:(0.2-0.4); the mass ratio of the total mass of the first layer and the second layer to the mass of the intermediate layer is 1:(0.2-0.6), and the mass ratio of the first layer to the second layer is 1:(0.75-1.25); the material of the first layer and the second layer includes the second polypropylene resin.

[0066] The above-mentioned limitations on the structure and composition of BOPP film are intended to effectively enhance its rigidity and expand its scope of application without affecting its ductility.

[0067] As a preferred embodiment of the present application, the first polypropylene resin and the second polypropylene resin are homopolymer polypropylene resins, and the melt flow rates measured at 230°C and 2.16 kg are each independently 2-4 g / 10 min; the tensile yield strength of the first polypropylene resin is ≥25 MPa, the tensile stress at break is ≥15 MPa, the isotactic index is ≥90%, the Vicat softening point is ≥150°C, and the ash content is ≤0.03%; the tensile yield strength of the second polypropylene resin is ≥25 MPa, the tensile stress at break is ≥15 MPa, the isotactic index is ≥90%, the Vicat softening point is ≥150°C, and the ash content is ≤0.03%.

[0068] When the first and second polypropylene resins are used to prepare a BOPP film having a thickness of 30 μm, the film can exhibit a longitudinal elastic modulus ≥ 1700 MPa, a longitudinal heat shrinkage of 3%-12%, a transverse heat shrinkage of 3%-12%, a haze ≤ 2%, and a heat seal strength ≥ 2.4 N / 15 mm (measured at 135°C for 0.3 seconds). This BOPP film has excellent overall performance and is suitable for a wide range of applications.

[0069] In a typical embodiment of the present application, a method for preparing a BOPP film is provided, comprising the following steps:

[0070] S1, adding the modified resin and the first polypropylene resin into a screw extruder for extrusion and granulation to obtain a stiffening masterbatch;

[0071] S2, adding the stiffening masterbatch into the screw extruder, adding the raw materials of the first layer and the second layer into their respective auxiliary extruders, the three layers of material converge at the die head and flow out, cool, and are stretched by a film biaxial stretching instrument to obtain a BOPP film.

[0072] As a preferred embodiment of the present application, in the above S1, the temperature of the screw extruder is 160-240°C, and the screw speed is 150-300r / min; and / or

[0073] In the above S2, stretching is divided into longitudinal stretching and transverse stretching. The longitudinal stretching conditions are: preheating temperature 220-280°C, stretching temperature 120-150°C, and stretching ratio 4.0-6.0. The transverse stretching conditions are: preheating temperature 220-280°C, stretching temperature 150-180°C, setting temperature 25-50°C, and stretching ratio 8.0-10.0.

[0074] The BOPP film prepared under the above conditions can have good physical and mechanical properties and a low content of volatile organic compounds.

[0075] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0076] The main test methods for resin and film products involved in this application are as follows:

[0077] Softening point: GB / T 2294-2019 "Determination of softening point of coking solid products";

[0078] Yellowness index: HG / T 3862-2006 Test method for yellowness index of plastics;

[0079] Aromaticity (H Spectrum): JY / T 0578-2020 "General Rules for Test Methods of Superconducting Pulse Fourier Transform Nuclear Magnetic Resonance Spectroscopy";

[0080] Acid value: ASTM D974-21 "Standard Test Method for pH by Color Indicator Titration";

[0081] Volatile organic compounds: US EPA 5021A-2014, analyzed by HS-GC-MS;

[0082] Elastic modulus: DIN 53457-Z "Plastics testing - Determination of elastic modulus";

[0083] Thermal shrinkage (vertical / transverse): BMSTT02 measures the dimensional stability of the film, i.e. the longitudinal / transverse thermal shrinkage;

[0084] Haze: ASTM D1003-13 "Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics";

[0085] Heat seal strength: QB / T 2358-1998 "Test method for heat seal strength of plastic film packaging bags".

[0086] The materials used in the examples and comparative examples are as follows:

[0087] Hydrogenated petroleum resin A: softening point 135.0°C, yellowness index YI 3.0, aromaticity 3.5%, hydrogenated petroleum resin HM-1300, Henghe Materials Technology Co., Ltd.

[0088] Hydrogenated petroleum resin B: softening point 140.0°C, yellowness index YI 1.0, aromaticity 1%, C5 hydrogenated petroleum resin H5-1400W, Henghe Materials Technology Co., Ltd.

[0089] Hydrogenated petroleum resin C: softening point 140.0°C, yellowness index YI 1.0, aromaticity 5%, hydrogenated petroleum resin HM-1400, Henghe Materials Technology Co., Ltd.

[0090] Hydrogenated petroleum resin D: softening point 140.0°C, yellowness index YI 1.0, aromaticity 10%, high aromatic hydrogenated resin HA-140, Henghe Materials Technology Co., Ltd.

[0091] Hydrogenated petroleum resin E: softening point 140.0°C, yellowness index YI 1.0, aromaticity 15%, high aromatic hydrogenated resin HR-140, Henghe Materials Technology Co., Ltd.

[0092] Hydrogenated petroleum resin F: softening point 140.0°C, yellowness index YI 1.0, aromaticity 0.01%, fully hydrogenated petroleum resin HP-140, Henghe Materials Technology Co., Ltd.

[0093] Abietic acid: industrial grade, purity ≥75%;

[0094] Dehydroabietic acid: industrial grade, purity ≥98.0%;

[0095] 2-Octenylsuccinic anhydride: pharmaceutical grade, purity ≥99.0%;

[0096] Itaconic acid: industrial grade, purity ≥98.0%.

[0097] The first polypropylene resin and the second polypropylene resin A: the melt flow rate measured at 230°C and 2.16 kg is 3 g / 10 min, the tensile yield strength is 32 MPa, the tensile breaking stress is 16 MPa, the isotactic index is 95%, the Vicat softening point is 150°C, the ash content is 0.030%, Shanghai Petrochemical Sanren F280.

[0098] Second polypropylene resin B: melt flow rate measured at 230°C and 2.16kg is 3.2g / 10min, tensile yield strength is 35MPa, tensile stress at break is 22MPa, isotactic index is 97%, Vicat softening point is 156°C, ash content is 0.016%, PPH-03T from Sinopec Zhenhai Refining and Chemical Company.

[0099] Second polypropylene resin C: melt flow rate measured at 230°C and 2.16kg is 2.8g / 10min, tensile yield strength is 47MPa, tensile stress at break is 18MPa, isotactic index is 93%, Vicat softening point is 165°C, ash content is 0.010%, Singapore Polyolefins Co., Ltd. FS3011E3.

[0100] Example 1

[0101] The embodiment of the modified resin of the present application, the preparation method of the modified resin is as follows:

[0102] S1, pre-charging 40 parts of a first solvent into a stirred autoclave, and then adding 55 parts of hydrogenated petroleum resin A, 4.5 parts of rosin acid and 0.5 parts of an antioxidant to obtain a mixed solution;

[0103] S2, then adding 0.5 parts of dibenzoyl peroxide as an initiator to the above mixed solution, heating to 125° C., reacting for 0.75 h to obtain a reaction product;

[0104] S3, removing the first solvent from the reaction product at 110° C. and 15 kPa, then adding a second solvent accounting for 5% of the mass of the reaction product after removing the first solvent to elute unreacted bio-based carboxylic acid monomer, eluting for 15 minutes, and then drying in a vacuum oven at 68° C. for 30 minutes to obtain a modified resin.

[0105] The first solvent is a mixture of xylene and DMF in a mass ratio of 1:0.5;

[0106] The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1;

[0107] The second solvent is acetone.

[0108] Figure 1 is a Fourier transform infrared spectrum of the modified resin and hydrogenated petroleum resin in Example 1. The characteristic peak comparison shows that the terminal group of the modified resin molecule has a -C=O- structure. This result shows that the bio-based carboxylic acid monomer has been successfully grafted. Figure 2 is a Fourier transform infrared spectrum of the modified resin and hydrogenated petroleum resin in Example 1. 1 H-NMR spectrum shows that olefinic groups are introduced into the modified resin molecules, further indicating that the grafting of bio-based carboxylic acid monomers is successful.

[0109] Examples 2-6

[0110] Examples 2-6 are modified resins. The only difference between Examples 2-6 and Example 1 is that the types of hydrogenated petroleum resins are different.

[0111] The hydrogenated petroleum resins used in Examples 2 to 6 are hydrogenated petroleum resin B, hydrogenated petroleum resin C, hydrogenated petroleum resin D, hydrogenated petroleum resin E, and hydrogenated petroleum resin F, respectively.

[0112] Effect Examples 1-6

[0113] Effect Examples 1-6 are BOPP films prepared from Examples 1-6, wherein the preparation method of Effect Example 1 is as follows:

[0114] S1, adding the modified resin and the first polypropylene resin in a mass ratio of 1:1 into a screw extruder, and extruding and granulating at 220°C and 200 r / min to obtain a rigidity-enhancing masterbatch;

[0115] In step S2, a mixture of the second polypropylene resin A and the stiffening masterbatch at a mass ratio of 1:0.4 was added to a screw extruder as the raw material for the intermediate layer. The second polypropylene resin A was then added to the respective auxiliary extruders as the raw material for the first and second layers. The three layers converged at the die and exited. The extruder temperature was 240°C, and the screw speed was 200 rpm. The longitudinal stretching process had a preheat temperature of 220°C, a stretching temperature of 120°C, and a stretch ratio of 5.0. The transverse stretching process had a preheat temperature of 220°C, a stretching temperature of 150°C, a setting temperature of 40°C, and a stretch ratio of 9.0. After biaxial stretching, a 30 μm thick BOPP film was obtained. The mass ratio of the first layer:second layer:intermediate layer was 1:1:0.8.

[0116] The difference between the preparation methods of Effect Example 2-6 and Effect Example 1 is that the type of the second polypropylene resin is different, and the second polypropylene resin A is replaced by the second polypropylene resin B.

[0117] The performance of Examples 1-6 and Effect Examples 1-6 were tested, and the test results are shown in Table 1-2.

[0118] Table 1

[0119] Table 2

[0120] As shown in Table 1 above, under the same reaction conditions, as the aromaticity of the hydrogenated petroleum resin increases, the softening point and acid value of the modified resin product will increase significantly. This indicates that the aromatic groups in the molecular structure of the raw resin facilitate the grafting reaction of rosin acid, but will worsen the color of the modified resin. At the same time, with the increase in softening point, the volatile organic compound content of the modified resin decreases significantly. This shows that within a certain performance range, high-softening-point modified resins are more suitable for BOPP film applications that require small molecule precipitation performance than low-softening-point modified resins.

[0121] As shown in Table 2, the above-mentioned BOPP films all exhibit excellent mechanical, optical, and thermodynamic properties. Furthermore, as the softening point and acid value of the modified resin increase, the elastic modulus and heat seal strength of the resulting BOPP films significantly improve, indicating an increase in the film's overall stiffness. However, when the acid value of the modified resin is ≥8.0 mgKOH / g, the increase in heat seal strength slows. Properly increasing the softening point of the modified resin helps reduce the thermal shrinkage of BOPP film products and improves the stability of biaxial stretching. Modified resins with high acid values ​​significantly increase the haze of BOPP films. Therefore, controlling the softening point and acid value of the stiffening modified resin within appropriate ranges is key to achieving optimal results. By controlling the softening point of the hydrogenated petroleum resin to 125-145°C, a yellowness index ≤7, and an aromaticity of 0.01%-15%, the modified resin can meet these requirements, resulting in the production of BOPP films with excellent stiffness, thermodynamic stability, and optical properties. Furthermore, when the softening point of the hydrogenated petroleum resin is 125-145° C., the yellowness index is ≤7, and the aromaticity is 1%-15%, it has better comprehensive performance.

[0122] Examples 7-9

[0123] Examples 7-9 are examples of the modified resin of the present application. The difference between Examples 7-9 and Example 1 is that the types of bio-based carboxylic acid monomers are different. The bio-based carboxylic acid monomer used in Example 7 is dehydroabietic acid, the bio-based carboxylic acid monomer used in Example 8 is 2-octenylsuccinic anhydride, and the bio-based carboxylic acid monomer used in Example 9 is itaconic acid.

[0124] Effect Examples 7-9

[0125] Effect Example 7-9 is a BOPP film prepared by Example 7-9, and its preparation method is the same as that of Effect Example 1.

[0126] Performance tests were performed on Example 7-9 and Effect Example 7-9, and the test results are shown in Table 3-4.

[0127] Table 3

[0128] Table 4

[0129] Tables 3-4 show that BOPP films prepared by modifying hydrogenated petroleum resins with the aforementioned bio-based carboxylic acid monomers exhibit excellent overall performance. Specifically, when itaconic acid and 2-octenylsuccinic anhydride are used, the BOPP films exhibit reduced haze and improved transparency, but also exhibit a slight increase in heat shrinkage. Furthermore, mechanical properties are somewhat reduced due to the influence of the aliphatic side chains in the structure. Dehydroabietic acid and abietic acid, by introducing their rigid fused ring structures into the modified resins, significantly improve the mechanical properties of the BOPP films, with haze levels remaining below 1%, resulting in superior overall performance.

[0130] Examples 10-14

[0131] Examples 10-14 are examples of the modified resin of the present application. The only difference between Examples 10-14 and Example 1 is that the type and amount of the initiator are different, as shown in Table 5.

[0132] Table 5 Note: The conversion of initiator molar concentration is based on the average density of the first solvent (DMF: xylene = 1:1) of 0.904 g / cm 3 calculate.

[0133] Effect Examples 10-14

[0134] Effect Example 10-14 is a BOPP film prepared by Example 10-14. The difference between the preparation method and Effect Example 1 is that the second polypropylene resin C is used instead of the second polypropylene resin A.

[0135] Examples 10-14 and Effects The performance test results of Examples 10-14 are shown in Tables 6-7.

[0136] Table 6

[0137] Table 7

[0138] Table 6 shows that the above-mentioned commonly used initiators can all produce carboxylic acid-modified resins under the operating conditions of this application. Under the same concentration conditions, the modified resin initiated by DCP has a higher softening point and acid value, a higher grafting efficiency for bio-based carboxylic acid monomers, and is more conducive to the preparation of high-rigidity BOPP film. In addition, high concentrations of DCP and AIBN cause more obvious color degradation of the modified resin than high concentrations of BPO. The volatile organic compound content of the modified resin is positively correlated with the amount of initiator used.

[0139] As shown in Table 7, all of Examples 10-14 exhibit good rigidity, thermal stability, transparency, and a certain degree of heat-seal strength. The BOPP film prepared using AIBN as the initiator exhibits low haze and better transparency, but slightly inferior mechanical properties. The BOPP film prepared using DCP as the initiator exhibits higher mechanical properties and heat-seal strength.

[0140] Examples 15-21

[0141] The examples of the modified resin of the present application, Examples 15-21, differ from Example 1 only in the type of the first solvent, as shown in Table 8.

[0142] Table 8

[0143] Effect Examples 15-21

[0144] Effect Example 15-21 is a BOPP film prepared from the modified resin of Example 15-21, and its preparation method is the same as that of Effect Example 1.

[0145] Performance tests were performed on Examples 15-21 and Effect Examples 15-21, and the test results are shown in Tables 9-10.

[0146] Table 9

[0147] Table 10

[0148] It can be seen from Tables 9-10 above that as the proportion of DMF in the compound solvent increases, the softening point, yellowness index and acid value all decrease to a certain extent, which helps to improve the mechanical properties of the modified BOPP film; but at the same time, a higher DMF content in the solvent will increase the VOC of the modified resin, which in turn affects the anti-precipitation performance of the BOPP film and deteriorates its optical properties; therefore, the preferred ratio of xylene to DMF in this application is 1: (0.3-2.0).

[0149] Examples 22-23

[0150] The preparation method of the modified resin in the embodiment of the present application differs from that in Example 1 only in the type of the second solvent. In Example 22, the second solvent is diethyl ether, while in Example 23, the second solvent is ethyl acetate.

[0151] Comparative Example 1

[0152] A modified resin is prepared in a method different from that of Example 1 in that no second solvent is used for elution.

[0153] Effect Examples 22-23 and Effect Comparative Example 1

[0154] The preparation methods of Effect Examples 22-23 and Effect Comparative Example 1 are the same as that of Effect Example 1.

[0155] Performance tests were performed on Examples 22-23, Comparative Example 1, and Effect Examples 22-23 and Effect Comparative Example 1. The test results are shown in Tables 11-12.

[0156] Table 11

[0157] Table 12

[0158] Tables 11-12 show that without elution treatment, the modified resin exhibits poor color quality, significantly increases VOC content, and degrades performance. BOPP film made with this resin exhibits a significant increase in haze, increasing its opacity and severely impacting its performance. Furthermore, a comparative analysis reveals that ethyl acetate is more effective in removing VOCs and offers the best elution results.

[0159] Effect Comparative Example 2

[0160] The BOPP film prepared from the hydrogenated petroleum resin in Example 1 was not grafted with a bio-based carboxylic acid monomer. The preparation method of the BOPP film was the same as that of Example 1.

[0161] Performance testing of Comparative Example 2 revealed a longitudinal elastic modulus of 1450 MPa, thermal shrinkage (longitudinal / transverse) of 7.9% / 7.0%, haze of 1%, and heat seal strength of 1.8 N / 15 mm. These test results demonstrate that without modification of hydrogenated petroleum resin, significant improvements in the rigidity and thermodynamic properties of polypropylene cannot be achieved.

[0162] It can be seen from the above test results that the BOPP films prepared with the modified resin of the present application have good mechanical properties, optical properties and thermodynamic properties, and are suitable for application in multiple fields.

[0163] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A modified resin, characterized in that, The modified resin is obtained by graft modification of a hydrogenated petroleum resin with a bio-based carboxylic acid monomer. The softening point of the modified resin is 120 - 165°C, the yellowness index ≤ 15, the content of volatile organic compounds ≤ 500 ppm, and the acid value is 0.1 - 25 mgKOH / g.

2. The modified resin according to claim 1, characterized in that, The softening point of the hydrogenated petroleum resin is 125 - 145°C, the yellowness index ≤ 7, and the aromaticity is 0.01% - 15%; and / or, the bio-based carboxylic acid monomer is at least one of 3-hydroxypropionic acid, 2,5-furandicarboxylic acid, rosin acid, dehydroabietic acid, dehydroabietic acid, 2,2-dimethyl succinic anhydride, 2-dimethyl succinic anhydride, butyl succinic anhydride, 2-octenyl succinic anhydride, ricinoleic acid, dehydrated ricinoleic acid, itaconic acid, hexyl itaconic acid.

3. A method for preparing the modified resin according to claim 1 or 2, characterized in that, It includes the following steps: S1, adding the hydrogenated petroleum resin, the bio-based carboxylic acid monomer, and an antioxidant into a first solvent to obtain a mixed solution; S2, then adding an initiator to the mixed solution for reaction to obtain a reaction product; S3, removing the first solvent from the reaction product, then eluting the unreacted bio-based carboxylic acid monomer with a second solvent, and drying to obtain the modified resin.

4. The preparation method according to claim 3, characterized in that, The first solvent is a mixed solution of xylene and N,N-dimethylformamide; and / or The second solvent is at least one of ether, phenetole, ethanol, methanol, isopropanol, isobutanol, acetone, methyl acetone, butanone, ethyl acetate, methyl acetate; and / or The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant; and / or The initiator is at least one of dicumyl peroxide, benzoyl peroxide, bis(tert-butylperoxyisopropyl)benzene, 2-butanone peroxide, azobisisobutyronitrile, azobisisoheptonitrile; and / or The mass ratio of the hydrogenated petroleum resin to the bio-based carboxylic acid monomer is (49.5 - 69.5)∶(0.1 - 15), the mass ratio of the hydrogenated petroleum resin to the antioxidant is (49.5 - 69.5)∶(0.1 - 0.5), the mass ratio of the hydrogenated petroleum resin to the first solvent is (49.5 - 69.5)∶(30 - 50), and the mass ratio of the hydrogenated petroleum resin to the initiator is (49.5 - 69.5)∶(0.05 - 2); and / or In S2, the reaction temperature is 70 - 200°C, and the reaction time is 0.25 - 3 h; and / or In S3, the first solvent is removed under the conditions of a pressure of 5 - 15 kPa and a temperature of 70 - 115°C; and / or In S3, drying is performed in a vacuum environment at 50 - 90°C.

5. The preparation method according to claim 4, characterized in that, In the first solvent, the mass ratio of xylene to N,N-dimethylformamide is 1∶(0.3 - 2); and / or The addition amount of the second solvent is 0.5% - 50% of the mass of the reaction product after removing the first solvent; and / or The hindered phenol antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 330, antioxidant 3114; and / or The phosphite antioxidant is at least one of antioxidant 168 and antioxidant 626.

6. A rigidifying masterbatch, characterized in that, It contains a modified resin and a first polypropylene resin. The modified resin is the modified resin as described in Claim 1 or 2, or the modified resin prepared by the preparation method as described in any one of Claims 3 to 5. The mass ratio of the modified resin to the first polypropylene resin is 1∶(0.8 - 1.2).

7. A BOPP film, characterized in that, It includes a first layer, an intermediate layer and a second layer connected in sequence. The material of the intermediate layer contains the rigidifying masterbatch as described in Claim 6 and a second polypropylene resin. The mass ratio of the second polypropylene resin to the rigidifying masterbatch in the intermediate layer is 1∶(0.2 - 0.4). The mass ratio of the total mass of the first layer and the second layer to the mass of the intermediate layer is 1∶(0.2 - 0.6), and the mass ratio of the first layer to the second layer is 1∶(0.75 - 1.25). The materials of the first layer and the second layer contain the second polypropylene resin.

8. The BOPP film according to claim 7, characterized in that, The first polypropylene resin and the second polypropylene resin in the rigidifying masterbatch are homopolypropylene resins. The melt flow rate measured under the conditions of 230℃ and 2.16 kg of the first polypropylene resin and the second polypropylene resin is independently 2 - 4 g / 10 min. The tensile yield strength of the first polypropylene resin ≥ 25 MPa, the tensile fracture stress ≥ 15 MPa, the isotactic index ≥ 90%, the Vicat softening point ≥ 150℃, and the ash content ≤ 0.03%. The tensile yield strength of the second polypropylene resin ≥ 25 MPa, the tensile fracture stress ≥ 15 MPa, the isotactic index ≥ 90%, the Vicat softening point ≥ 150℃, and the ash content ≤ 0.03%; and / or When the thickness of the BOPP film is 30 μm, the longitudinal elastic modulus of the BOPP film ≥ 1700 MPa, the longitudinal thermal shrinkage rate is 3% - 12%, the transverse thermal shrinkage rate is 3% - 12%, the haze ≤ 2%, and the heat seal strength measured by heat sealing for 0.3 s at 135℃ ≥ 2.4 N / 15 mm.

9. A method for preparing the BOPP film according to claim 7 or 8, characterized in that, It includes the following steps: S1. Add the modified resin and the first polypropylene resin into a screw extruder for extrusion granulation to obtain a rigidifying masterbatch. S2. Add the rigidifying masterbatch into a screw extruder, add the raw materials of the first layer and the second layer into their respective auxiliary extruders. The three-layer materials converge at the die head and then flow out, are cooled, and are stretched by a film biaxial stretcher to obtain the BOPP film.

10. The preparation method according to claim 9, characterized in that, In S1, the temperature of the screw extruder is 160 - 240℃, and the screw speed is 150 - 300 r / min; and / or In S2, the stretching is divided into longitudinal stretching and transverse stretching. The longitudinal stretching conditions are: preheating temperature 220 - 280℃, stretching temperature 120 - 150℃, stretching ratio 4.0 - 6.

0. The transverse stretching conditions are: preheating temperature 220 - 280℃, stretching temperature 150 - 180℃, setting temperature 25 - 50℃, stretching ratio 8.0 - 10.0.

Images