A pearlescent masterbatch material, its preparation method and application

Abstract

The present invention discloses a pearlescent masterbatch material, a preparation method thereof and an application. The pearlescent masterbatch material comprises the following components in parts by weight: 18-38 parts of homopolypropylene; 1-5 parts of low-melting-point polypropylene; 60-75 parts of calcium carbonate; 1-5 parts of a surface activator; and the surface active agent is one or more of long-chain fatty acids, long-chain esters or phosphoric acid esters. The pearlescent masterbatch material provided by the present invention is used in a film, and not only has a good pearlescent effect, but also does not affect the density or mechanical properties such as stretching of the film.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to a pearlescent masterbatch material and a preparation method and application thereof. Background Art

[0002] White BOPP pearlescent film has excellent characteristics such as soft and pleasing pearl luster, low density, and excellent flatness. It is widely used in food packaging, gift packaging, facial masks and other products. The general BOPP film has a structure of more than three layers. The pearlescent masterbatch and the main material of polypropylene are blended and extruded and then cast and biaxially stretched to form a film to obtain the BOPP film. The pearlescent effect is mainly due to the fact that the functional fillers and polypropylene form countless tiny holes in the core layer of the film during the stretching process. When light enters these holes, the pearlescent effect is formed due to the reflection and interference of light. The addition of functional fillers also improves the covering performance of the film and greatly reduces the production cost of the film.

[0003] As domestic BOPP production capacity continues to increase, the problem of overcapacity has become more and more prominent, and the competition for BOPP film has also entered a fierce stage. Therefore, many manufacturers are also looking for a more cost-effective system in order to produce cheap and high-quality film products. Nowadays, manufacturers are pursuing the premise that the thickness and density of the produced film remain unchanged, and the content of pearlescent masterbatch added can be as much as possible, because in the BOPP pearlescent film system, the higher the proportion of pearlescent masterbatch added, the better the pearlescent effect and light-shielding performance become, and the cost is lower. But at the same time, the more pearlescent masterbatch is added, the more defects such as low film density and insufficient mechanical strength will appear. Therefore, how to increase the amount of pearlescent masterbatch added without affecting the film density and other properties is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention proposes a pearlescent masterbatch material and its preparation method and application. The pearlescent masterbatch material provided by the present invention can be used in a biaxially stretched film. As the addition ratio of the pearlescent masterbatch of the present invention increases, the pearlescent effect and light-shielding performance of the film become more excellent, but it will not affect the density or tensile mechanical properties of the film.

[0005] This is achieved specifically through the following technical solutions:

[0006] A pearlescent masterbatch material, comprising the following components by weight:

[0007]

[0008] The surfactant is one or more of long-chain fatty acids, long-chain esters or phosphates.

[0009] Preferably, by weight parts, it comprises the following components:

[0010]

[0011] Further, the surfactant is a fatty acid with a carbon chain length of more than 18. Preferably, the surfactant is one or more of stearic acid, arachidic acid or behenic acid.

[0012] The compatibility between homopolypropylene and calcium carbonate is related to the crystallization performance of homopolypropylene. Introducing low-melting-point polypropylene, polypropylene can achieve a low melting point because of more amorphous regions. Increasing the content of amorphous regions in the system reduces the foaming efficiency; calcium carbonate is incompatible with polypropylene itself, and this incompatibility will cause the voids in the material to become larger after the stretching process. However, for the calcium carbonate modified by the above-mentioned surface activator, long carbon chains are formed on the surface, improving the compatibility between calcium carbonate and polypropylene. With the improvement of compatibility, there are fewer voids at the film interface and the foaming efficiency is reduced. Therefore, the addition amount of pearlescent masterbatch in BOPP film can be increased. With the increase of the addition amount of pearlescent masterbatch, the covering performance of the film is better, the pearlescent effect is more delicate, and at the same time, the material cost is reduced.

[0013] Further, the number-average molecular weight of the low-melting-point polypropylene is 40,000 - 130,000, and the melting point is lower than 120 °C.

[0014] Preferably, the number-average molecular weight of the low-melting-point polypropylene is 45,000 - 75,000, and the melting point is 80 - 90 °C. When the number-average molecular weight of the low-melting-point polypropylene is between 45,000 - 75,000, it helps to reduce the foaming efficiency. If the number-average molecular weight of the low-melting-point polypropylene is too high, it will affect the dispersion of calcium carbonate and make the dispersion of calcium carbonate poor.

[0015] Further, the D50 particle size of the calcium carbonate is 0.5 - 2 μm, preferably 1 - 1.4 μm. D50 is the particle size at which the cumulative particle size distribution is 50%, and D50 is also called the average particle size or median diameter. On the one hand, the particle size of calcium carbonate is related to the foaming efficiency. The smaller the particle size, the lower the foaming efficiency; on the other hand, the smaller the particle size of calcium carbonate, the worse its dispersion performance, and the material will break during stretching.

[0016] Further, the melt index of the homopolypropylene is 1 - 30 g / 10 min at 230 °C / 2.16 kg, preferably 3 g / 10 min.

[0017] Further, it also comprises 0.1 - 0.3 parts of processing aids. The processing aids are one or more of antioxidants.

[0018] Further, the antioxidant is selected from one or more of antioxidant 1010 (pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]), antioxidant 168 (tris (2,4-di-tert-butylphenyl) phosphite), antioxidant 1790 (1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione) or antioxidant 412S (pentaerythritol tetrakis (3-laurylthiopropionate)).

[0019] The present invention also provides a method for preparing the above pearlescent masterbatch material, comprising the following steps:

[0020] S1: Weigh each component according to the ratio. First, mix calcium carbonate and a surface activator, and then add the remaining components and continue to mix to obtain a premix;

[0021] S2: Feed the premix obtained in step S1 into an extruder, carry out melt blending and extrusion granulation to obtain the pearlescent masterbatch material.

[0022] Further, the extruder is a twin-screw extruder. The length-diameter ratio of the screw of the twin-screw extruder is (44 - 56):1. The barrel temperature of the twin-screw extruder is 210 - 240 °C, and the screw speed of the twin-screw extruder is 300 - 800 r / min.

[0023] The present invention also provides the application of the above pearlescent masterbatch material in the preparation of packaging materials, such as food packaging, etc.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The present invention discloses a pearlescent masterbatch material. By activating and modifying calcium carbonate with a specific surfactant, the compatibility between calcium carbonate and polypropylene is greatly improved, thereby greatly reducing the foaming efficiency of the pearlescent masterbatch material. The reduction of the foaming efficiency can greatly increase the addition amount of the pearlescent masterbatch material in the BOPP pearlescent film, improve the covering performance of the film, and at the same time reduce the cost of the material, but without affecting the density and mechanical properties of the material. Specific Embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Through research, it is found that the compatibility between homopolypropylene and calcium carbonate is related to the crystallization properties of homopolypropylene. Introducing low-melting-point polypropylene and increasing the amorphous region content will reduce the foaming efficiency. By using a high-mixing process to pre-coat the calcium carbonate surface with a surfactant containing a long carbon chain in a relatively large amount, calcium carbonate with a long carbon chain on the surface is formed, enabling better compatibility between calcium carbonate and polypropylene resin, greatly reducing the pore formation caused by incompatibility during stretching, and reducing the foaming degree.

[0028] <Preparation of Examples and Comparative Examples>

[0029] The raw materials used in the examples and comparative examples of the present invention are all commercially available, but are not limited to these materials:

[0030] Homopolymer PP resin A, with a melt index of 3 g / 10 min at 230 °C / 2.16 kg, grade PP T30S, purchased from China National Petroleum and Chemical Corporation;

[0031] Homopolymer PP resin B, with a melt index of 10 g / 10 min at 230 °C / 2.16 kg, grade PP HP500N, purchased from China National Petroleum and Chemical Corporation;

[0032] Low-melting-point PP resin A, with a number-average molecular weight of 45,000 and a melting point of 82 °C, grade S400, purchased from Idemitsu Kosan Co., Ltd.;

[0033] Low-melting-point PP resin B, with a number-average molecular weight of 75,000 and a melting point of 84 °C, grade S600, purchased from Idemitsu Kosan Co., Ltd.;

[0034] Low-melting-point PP resin C, with a number-average molecular weight of 130,000 and a melting point of 90 °C, grade S901, purchased from Idemitsu Kosan Co., Ltd.;

[0035] Calcium carbonate A, D50 = 0.5 μm, grade Carbital S, purchased from Imerys;

[0036] Calcium carbonate B, D50 = 1.0 μm, grade XL6000, purchased from Guangdong Xianglong Technology Co., Ltd.;

[0037] Calcium carbonate C, D50 = 1.4 μm, grade XL2800, purchased from Guangdong Xianglong Technology Co., Ltd.;

[0038] Calcium carbonate D, D50 = 2.0 μm, grade XL2500, purchased from Guangdong Xianglong Technology Co., Ltd.;

[0039] Calcium carbonate E, D50 = 0.2 μm, grade XL10000, purchased from Guangdong Xianglong Technology Co., Ltd.;

[0040] Calcium carbonate F, D50 = 3.0 μm, grade XL1500, purchased from Guangdong Xianglong Technology Co., Ltd.;

[0041] Surface activator A, stearic acid, grade stearic acid 1865, purchased from Ticona Co., Ltd.;

[0042] Surface activator B, octadecyl monoglyceride, purchased from Aladdin Reagent Co., Ltd.;

[0043] Surface activator C, octadecyl phosphate, purchased from Wuhan Pulov Bio-Technology Co., Ltd.;

[0044] Surface activator D, behenic acid, purchased from Aladdin Reagent Co., Ltd.;

[0045] Surface activator E, dodecylbenzenesulfonic acid, purchased from Wuhan Kemic Biopharmaceutical Technology Co., Ltd.;

[0046] Antioxidant, a compound of antioxidant 1010 and antioxidant 168 (1:1), commercially available, and the same commercially available antioxidant product is used for parallel experiments;

[0047] Anti-aging agent, commercially available.

[0048] The preparation methods of the examples and comparative examples of the present invention are as follows:

[0049] S1: Weigh each component according to the ratios in Table 1 and Table 3. First, place the calcium carbonate in a heatable high-speed mixer. The temperature of the high-speed mixer is controlled at 80 - 150 °C through a heating device. Then pour the surface activator into the high-speed mixer. The rotation speed of the high-speed mixer needs to be greater than 600 rpm, and the blending time is greater than 5 min. After the temperature of the calcium carbonate and the surface activator is mixed to above 100 °C, if there are processing aids in the formula, add processing aids such as antioxidants and mix for another 3 min; the homopolymer PP resin and the low-melting-point PP resin are added through a feeding scale to obtain a premix;

[0050] S2: Put the premix from step S1 into a twin-screw extruder for melt blending and pelletizing to obtain the pearlescent masterbatch material.

[0051] The length-diameter ratio of the screws of the twin-screw extruder is 44:1, the barrel temperature of the twin-screw extruder is 240 °C, and the screw rotation speed of the twin-screw extruder is 400 r / min.

[0052] Regarding "parts" in this specification, unless otherwise specified, it means "parts by weight".

[0053] <Test standard>

[0054] The performance test methods of the examples and comparative examples of the present invention are as follows:

[0055] Using a three-layer casting machine, the surface layer material is all homopolymer PP with a melt index of 3 g / 10 min, and the pearlescent masterbatch material in the present invention is added as a core layer additive and mixed with homopolymer PP. In order to compare the foaming effects of different pearlescent masterbatches, all pearlescent masterbatches are added at 30%. The processing temperature of each layer of the three-layer casting machine is 210 - 250 °C. After the film is formed, it is longitudinally stretched. The temperature of the stretching roller is set at 130 - 135 °C, and the film stretching ratio is 5 times. Adjust the rotation speed so that the thickness of the stretched film is about 50 μm. Use this film sample to test its density through weight and thickness.

[0056] Table 1. Formulations of Examples 1 - 13

[0057]

[0058] Table 2. Performance test results of Examples 1 - 13

[0059]

[0060] Classification of production situation levels:

[0061] During the production process, if the film breaks, it is recorded as unqualified; if the film does not break during the production of 1000 meters, it is qualified; if the film does not break during the production of 3000 meters, it is medium; if the film does not break during the production of 5000 meters, it is good.

[0062] Table 3. Formulations of Comparative Examples 1 - 5

[0063]

[0064] Table 4. Performance test results of Comparative Examples 1 - 5

[0065]

[0066] Generally required, the density of the stretched film should be greater than 0.75, and the production process is stable for qualified. More preferably, the density range is 0.8 - 0.87 g / cm 3 And the production process without film breakage is good. Among them, under the condition of ensuring stable production, the higher the density, the better the effect.

[0067] It can be seen from the data of the examples that by activating and modifying calcium carbonate with a specific surfactant, the compatibility between calcium carbonate and polypropylene can be greatly improved, thereby greatly reducing the foaming efficiency of the pearlescent masterbatch material. The reduction of the foaming efficiency greatly increases the addition amount of the pearlescent masterbatch material in the BOPP pearlescent film. In the present invention, the addition amount of the pearlescent masterbatch can reach 30%, improving the covering performance of the film and at the same time reducing the material cost. However, it will not cause problems such as a decrease in the film density and tensile strength due to the large addition of the pearlescent masterbatch.

[0068] Comparing Comparative Example 1 with Example 1, since no surfactant was used in Comparative Example 1, the density of the film prepared with Comparative Example 1 decreased, and the film was prone to breakage during the stretching process, and the tensile strength was poor; comparing Comparative Example 2 with Example 1, since a surfactant other than the one specified in the present invention was used, the density also decreased, and the film was prone to breakage during the stretching process; comparing Comparative Example 3 with Example 1, no low-melting-point polypropylene was added. Although the production process was stable, the density decreased; comparing Comparative Example 4 with Example 1, the particle size of calcium carbonate was too small, resulting in poor dispersion performance. When stretched, the material would break, and the density of the material after stretching would also decrease. Comparing Comparative Example 5 with Example 1, the too small particle size of calcium carbonate led to a serious decrease in the density of the film.

[0069] Example 14

[0070] Using a three-layer casting machine, the surface materials were all homopolymer PP with a melt index of 3 g / 10 min. The pearlescent masterbatch material of Example 1 in the present invention was added as a core layer additive and mixed with homopolymer PP. The pearlescent masterbatch was added at 30 wt%. The processing temperature of each layer of the three-layer casting machine was 210 - 250 °C. After the film was formed, it was longitudinally stretched. The temperature of the stretching roller was set at 130 - 135 °C. The film stretching ratio was 5 times. The rotation speed was adjusted so that the thickness of the film after stretching was about 50 μm. The density of the film sample was measured by weight and thickness. It was measured that: the density was 0.820, the production situation was stable, and no tensile fracture phenomenon occurred. Thus, it can be seen that the pearlescent masterbatch material provided by the present invention can be applied to the preparation of packaging materials with high requirements for pearlescent effect, density, and mechanical properties such as stretching.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pearlescent masterbatch material, characterized in that, By weight, it comprises the following components: Homopolypropylene 18 - 38 parts Low melting point polypropylene 1 - 5 parts Calcium carbonate 60 - 75 parts Surfactant 1 - 5 parts The surfactant is one or more of long carbon chain fatty acids, long carbon chain esters or phosphate esters; The number average molecular weight of the low melting point polypropylene is 40,000 - 130,000, and the melting point is lower than 120 °C; The D50 particle size of the calcium carbonate is 0.5 - 2 μm.

2. The pearlescent masterbatch material according to claim 1, characterized in that, By weight, it comprises the following components: Homopolypropylene 22 - 26 parts Low melting point polypropylene 2 - 3 parts Calcium carbonate 65 - 70 parts Surfactant 2 - 4 parts The surfactant is a fatty acid with a carbon chain length above 18.

3. The pearlescent masterbatch material according to claim 1, wherein, The molecular weight of the low melting point polypropylene is 45,000 - 75,000, and the melting point is 80 - 90 °C.

4. The pearlescent masterbatch material according to claim 1 or 2, characterized in that, The D50 particle size of the calcium carbonate is 1 - 1.4 μm.

5. The pearlescent masterbatch material according to claim 1 or 2, characterized in that, The melt index of the homopolypropylene is 1 - 30 g / 10 min at 230 °C / 2.16 kg.

6. The pearlescent masterbatch material according to claim 1 or 2, characterized in that, The melt index of the homopolypropylene is 2 - 5 g / 10 min at 230 °C / 2.16 kg.

7. The pearlescent masterbatch material according to claim 1 or 2, characterized in that It also includes 0.1 - 0.3 parts of processing aids.

8. The pearlescent masterbatch material according to claim 7, characterized in that, The processing aids are one or more of antioxidants or anti - aging agents.

9. A method for preparing the pearlescent masterbatch material according to any one of claims 1-8, characterized in that, It includes the following steps: S1: Weigh each component according to the ratio. First, mix calcium carbonate and surfactant, and then add the remaining components to continue mixing to obtain a premix; S2: Put the premix of step S1 into an extruder, carry out melt blending and extrusion granulation to obtain the pearlescent masterbatch material.

10. The application of the pearlescent masterbatch material according to any one of claims 1 - 8 in the preparation of packaging materials.

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