A recycled polypropylene composite material, a preparation method and application thereof

Abstract

This invention discloses a recycled polypropylene composite material, comprising the following components: 90-97 parts recycled polypropylene; 0.3-0.8 parts nanoporous silicate; 3-8 parts toughening / transparent agent; and 0.05-0.2 parts anti-exudation agent; wherein the anti-exudation agent is selected from bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate. This invention, by adding nanoporous silicate with specific parameters, can effectively adsorb the odor of recycled polypropylene and reduce leachates without significantly reducing transparency; simultaneously, the anti-exudation agent can improve the formation of impurities during processing and the precipitation of impurities to the surface, thereby significantly reducing haze and improving light transmittance; furthermore, by selecting a toughening / transparent agent, not only is the toughness improved, but the transparency of the recycled polypropylene composite material is also improved, and compared with other types of toughening agents, xylene leachates are further reduced. Therefore, the recycled polypropylene composite material of this invention has the advantages of passing leachate detection, high transparency, low odor, and good toughness.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a recycled polypropylene composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of the Internet of Things (IoT), the efficiency of commodity circulation is constantly improving. Massive amounts of product packaging flow with goods worldwide, placing severe pressure on the environment and ecological protection. Plastics, with their advantages of low density, high light transmittance, low exudation, and ease of molding, are an indispensable material for logistics packaging and are experiencing rapid growth alongside the logistics industry. Against this market backdrop, many scholars and experts have proposed the concept of a circular economy to address environmental damage. This new environmental concept aims to reuse resources based on existing resource consumption patterns, thereby increasing product added value, reducing energy consumption, and minimizing environmental pollution.

[0003] To effectively recycle food-grade packaging materials, specific plans and control methods for challenge testing of recycled materials are proposed. Recycled materials that pass the challenge test can be used for food packaging in certain situations. They must meet the requirements of low odor, transparency, and controlled leachate content (tested according to FDA 21CFR 177.1520 standards) in the food, pharmaceutical, and tableware sectors.

[0004] Meanwhile, recycled polypropylene has poor toughness, so toughening agents need to be added. However, the addition of toughening agents affects transparency and leachate content. Therefore, obtaining a recycled polypropylene composite material that simultaneously possesses good toughness, high transparency, low odor, and meets leachate content control requirements presents a significant challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a recycled polypropylene composite material with high transparency, low odor, meeting the requirements for leachate content control, and good toughness, as well as its preparation method and application.

[0006] This invention is achieved through the following technical solution:

[0007] A recycled polypropylene composite material, by weight, comprises the following components:

[0008] 90-97 parts of recycled polypropylene;

[0009] 0.3-0.8 parts of nanoporous silicate;

[0010] Toughening / Transparency Agent 3-8 parts;

[0011] Anti-precipitation agent 0.05-0.2 parts;

[0012] The specific surface area of ​​nanoporous silicates is 1000-10000 m².2 / g, D50 particle size is 10-50 nanometers;

[0013] The anti-precipitation agent is selected from bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate.

[0014] Compared with traditional porous inorganic silicates, the nanoporous silicates that can achieve the purpose of this invention have a larger specific surface area, which gives them stronger adsorption performance and smaller particle size. They can effectively adsorb small molecules and act as good nucleating agents, refine the size of polypropylene crystals and improve transparency.

[0015] The toughening / transparency agent is selected from at least one of ethylene-octene copolymer (POE), olefin block copolymer (INFUSE), and styrene-ethylene-butene-styrene block copolymer (SEBS); preferably, the toughening / transparency agent is selected from styrene-ethylene-butene-styrene block copolymer.

[0016] Optionally, the commercially available ethylene-octene copolymer is designated as POE 8842, Dow Chemical.

[0017] Optionally, commercially available olefin block copolymers are designated as follows: POE LC168, LG Chem; POE ENGAGE 7467, Dow Chemical.

[0018] Optionally, commercially available styrene-ethylene-butene-styrene block copolymers are available under the following designations: SEBS 7551 (Li Changrong) or Y-501T (Baling Petrochemical).

[0019] The specific surface area of ​​nanoporous silicates is tested by inert gas adsorption; the D50 particle size is tested by laser particle size analyzer.

[0020] Depending on the actual situation, it may be optional to add 0-2 parts of processing aids, wherein the processing aids are selected from at least one of antioxidants, lubricants, ultraviolet absorbers, and pigments.

[0021] Antioxidants can be: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; 2,5-di-tert-butyl-4-hydroxybenzyl dimethylamine; diethyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphate; stearyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphate; 3,5-di-tert-butyl-4-hydroxyphenyl-3,5-distearate-thiotriazolylamine; 2,6-di-tert-butyl-4-hydroxymethylphenol; 2,4-di-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylglycerol allyl ether)-1,3,5-triazine; N,N'-hexamethylene di( 3,5-Di-tert-butyl-4-hydroxy-hydrogenated cinnamamide; N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine; octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; pentaerythritol-tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; triethylene glycol-bis[3-(3,5-dimethyl-4-hydroxyphenyl)propionate]; triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]; 2,2'-thiodiethyl-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, etc.

[0022] The lubricant may be at least one of the following: stearate lubricant, fatty acid lubricant, and stearate ester lubricant; wherein the stearate lubricant is selected from at least one of calcium stearate, magnesium stearate, and zinc stearate; wherein the fatty acid lubricant is selected from at least one of fatty acids, fatty acid derivatives, and fatty acid esters; and wherein the stearate ester lubricant is selected from at least one of pentaerythritol stearate.

[0023] The light transmittance (2mm) of the recycled polypropylene raw material used in this invention is >70%.

[0024] The recycled polypropylene composite material of this invention was tested for particles in accordance with the non-cooking standards in FDA 21CFR 177.1520. The maximum hexane leaching content was <4.0%, the maximum xylene leaching content was <23%, the volatile matter content was <0.1%, the light transmittance was >70% (2mm), and the haze was <50% (2mm). It can meet the requirements for use as food packaging, pharmaceutical packaging, and tableware.

[0025] The method for testing light transmittance is as follows: the transmittance of a light source in a 2mm thick square plate is tested using a visible light spectrometer.

[0026] The method for preparing the recycled polypropylene composite material of the present invention includes the following steps: mixing the components evenly according to the formula, granulating by extrusion through a twin-screw extruder, wherein the screw temperature range is 180-230℃, to obtain the recycled polypropylene composite material.

[0027] The recycled polypropylene composite material of the present invention is used to prepare food packaging, pharmaceutical packaging, and tableware.

[0028] The present invention has the following beneficial effects:

[0029] This invention utilizes nanoporous silicates with specific parameters to effectively adsorb the odor of recycled polypropylene and reduce leachates without significantly reducing transparency. Simultaneously, an anti-exudation agent improves the formation of impurities during processing and their precipitation on the surface, significantly reducing haze and increasing light transmittance. Furthermore, the selection of toughening / transparent agents not only enhances toughness but also improves the transparency of the recycled polypropylene composite material, and compared to other types of toughening agents, it further reduces xylene leachates. This results in a recycled polypropylene composite material with advantages such as passing leachate testing, high transparency, low odor, and good toughness. Detailed Implementation

[0030] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0031] Recycled Polypropylene 1: Recycled from transparent bottle caps, the raw material is obtained after sorting, crushing, friction cleaning, drying, color separation and quality separation. It is random polypropylene with a light transmittance of 72%, a maximum hexane leaching of 2.5%, a maximum xylene leaching of 12%, and a volatile matter content of 0.2%. Ganzhou Runshengke Environmental Protection Materials Co., Ltd.

[0032] Recycled Polypropylene 2: Recycled from transparent chip boxes, the raw material is obtained after sorting, crushing, friction cleaning, drying, color separation and quality separation. It is random polypropylene with a light transmittance of 75%, a maximum hexane leaching of 3.5%, a maximum xylene leaching of 9.8%, and a volatile matter content of 0.23%. Anhui Lianxin New Materials Co., Ltd.

[0033] Recycled Polypropylene 3: Recycled from transparent lunch boxes, the raw material is obtained after sorting, crushing, friction cleaning, drying, color separation and quality separation. It is homopolymer polypropylene with a light transmittance of 70%, a maximum hexane leaching of 0.98%, a maximum xylene leaching of 15%, and a volatile matter content of 0.36%. Hunan Xinjiyuan New Materials Co., Ltd.

[0034] Nanoporous silicate 1: Specific surface area of ​​1200 m² 2 / g, D50 particle size is 32 nanometers, JH-200A, Ningbo Jiahe New Material Technology Co., Ltd.;

[0035] Nanoporous silicate 2: Specific surface area is 4050 m² 2 / g, D50 particle size is 15.3 nm, JH-200B is obtained by grinding JH-200A;

[0036] Porous inorganic silicate with a specific surface area of ​​65 m² 2 / g, D50 particle size is 3.4 micrometers, Shanghai Chonghe Dou;

[0037] Diatomaceous earth: Grade 512, specific surface area is 25m³ 2 / g, D50 particle size is 11.1 micrometers, purchased from Shanghai Chonghedou New Materials;

[0038] Zeolite: 4A zeolite powder, D50 particle size is 4 micrometers, specific surface area is 83 m². 2 Ningbo Jiahe New Material Technology Co., Ltd.

[0039] Toughening / Transparency Agent 1: Ethylene-Octene Copolymer, POE ENAGE 7467, DowDuPont;

[0040] Toughening / Transparent Agent 2: SEBS, Y-501T, Baling Petrochemical;

[0041] Toughening / Transparent Agent 3: Olefin Block Copolymer, POE LC168, LG Chem;

[0042] Toughening / Transparency Agent 4: LLDPE EXCEED 3518PA ExxonMobil

[0043] Anti-precipitation agent: PEP-36, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate, Idico;

[0044] Antioxidant: RIANOX 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) and RIANOX 168 (tris(2,4-di-tert-butylphenyl) phosphite) in a weight ratio of 1:2, Rianon;

[0045] Commercially available auxiliary antioxidant: P-EPQ (tetra-(2,4-di-tert-butylphenyl)-4,4'-biphenyl bisphosphite), Clariant, Switzerland.

[0046] Preparation method of recycled polypropylene composite material in the examples and comparative examples: According to the formula, the components are mixed evenly and extruded and granulated by a twin-screw extruder. The screw temperature range is 180-230℃ to obtain recycled polypropylene composite material.

[0047] Test methods:

[0048] (1) Migrating substance test: FDA 21CFR 177.1520, using composite material particles for testing.

[0049] (2) Volatile matter test: According to GB / T 2918-2018 standard, bake at 105℃ for 5 minutes and test the volatile matter content using infrared spectroscopy.

[0050] (3) Odor test: According to PV3900 standard, bake at 80℃ for 4 hours, cool to 60℃, open the lid and smell the odor. A total of 10 odor judges scored and the average score was taken. It is divided into 1-6 levels, namely: 1. No odor; 2. Slight odor; 3. Odor but not irritating; 4. Irritating odor; 5. Strong irritating odor; 6. Unbearable.

[0051] (4) Transmittance / Haze: The light transmittance and haze were measured by injection molding into square plates with a thickness of 2mm.

[0052] (5) Notched impact strength: The notched impact strength of the injection molded notched impact specimens according to ISO 180:2000 standard was tested after being adjusted for 16 hours at 23℃ and 50% relative humidity.

[0053] Table 1: Components (parts by weight) and test results of recycled polypropylene composite materials in the examples

[0054] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Recycled polypropylene 1 95 95 95 95 Recycled polypropylene 2 90 Recycled polypropylene 3 97 Nanoporous silicate 1 0.5 0.3 0.8 0.5 0.5 Nanoporous silicate 2 0.5 Toughening / Transparency Agent 1 4 3 4 Toughening / Transparency Agent 2 8 4 Toughening / Transparency Agent 3 4 Anti-precipitation agent 0.1 0.05 0.2 0.1 0.1 0.1 antioxidants 0.3 0.2 0.3 0.3 0.3 hexane extract content % 3.2 3.5 2.8 3.8 3.5 3.9 Xylene leachate content % 9.8 21.3 8.7 8.6 13.3 11.3 Volatile matter test 0.03 0.04 0.01 0.02 0.01 0.03 Odor test 3.2 3.5 3.0 3.8 3.6 3.8 Light transmittance, % 73 78 71 76 81 73 Haze 42 45 41 46 38 43 <![CDATA[Notched impact strength, kJ / m 2 > 4.2 5.2 3.8 4.3 5.8 4.8

[0055] As can be seen from Examples 1 / 5 / 6, when SEBS is preferred as the toughening agent, it has better toughness, higher transparency, and the lowest volatile content, while the dissolution and odor also meet the standards.

[0056] Table 2: Components (parts by weight) and test results of recycled polypropylene composites in Comparative Examples 1-6

[0057] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Recycled polypropylene 1 95 95 95 95 95 95 Nanoporous silicate 1 0.1 1 0.5 Porous inorganic silicates 0.5 diatomite 0.5 zeolite 0.5 Toughening / Transparency Agent 1 4 4 4 4 4 4 Anti-precipitation agent 0.1 0.1 0.1 0.1 0.1 0 antioxidants 0.3 0.3 0.3 0.3 0.3 0.4 hexane extract content % 4.1 4.4 4.1 4.6 3.5 4.0 Xylene leachate content % 13.6 10.5 12.2 14.9 8.8 10.2 Volatile matter test 0.16 0.32 0.34 0.17 0.05 0.12 Odor test 4.3 4.3 4.5 4.1 2.8 3.2 Light transmittance, % 51 48 43 70 58 56 Haze 67 72 74 63 70 86 <![CDATA[Izod impact strength, kJ / m 2 > 4.2 4.1 3.6 4.3 3.3 4.3

[0058] As can be seen from the examples and comparative examples, the addition of nanoporous silicates and anti-exudation agents can not only effectively reduce the odor, volatility and solubility of the material, but also improve the light transmittance and reduce the haze, thus providing a good solution for the development of transparent recycled polypropylene materials.

[0059] Specifically, as shown in Comparative Examples 1-3, the traditional porous structures of inorganic silicates, diatomaceous earth, and zeolite have insufficient adsorption capacity and severely reduce transparency.

[0060] As shown in Comparative Example 4, if the content of nanoporous silicate is too low, the adsorption capacity is insufficient, and too many small molecule impurities also lead to an increase in haze.

[0061] As shown in Comparative Example 5, if the content of nanoporous silicate is too high, the transparency will be significantly reduced.

[0062] As can be seen from Comparative Example 6, without the anti-exudation agent of the present invention, the volatile matter of the recycled polypropylene composite material cannot be effectively suppressed, and the haze is very high, which seriously affects the transparency.

[0063] Table 3: Components (parts by weight) and test results of recycled polypropylene composites in Comparative Examples 7-9

[0064] Comparative Example 7 Comparative Example 8 Comparative Example 9 Recycled polypropylene 1 95 95 Recycled polypropylene 2 90 Nanoporous silicate 1 0.3 0.5 0.5 Toughening / Transparency Agent 1 4 10 Toughening / Transparency Agent 4 8 Anti-precipitation agent 0.05 0.1 Commercially available antioxidant supplements 0.1 antioxidants 0.2 0.3 0.3 hexane extract content % 4.3 4.5 5.6 Xylene leachate content % 27.6 12.3 31.8 Volatile matter test 0.16 0.21 0.12 Odor test 3.9 4.2 4.3 Light transmittance, % 46 49 46 Haze 58 56 68 <![CDATA[Izod impact strength, kJ / m 2 > 3.4 3.8 6.5

[0065] As shown in Comparative Example 7, the commonly used transparent toughening agent LLDPE in polypropylene has insufficient toughening effect and also significantly affects transparency.

[0066] As can be seen from Comparative Example 8, other commercially available auxiliary antioxidants, even if their molecular formulas are similar to the anti-exudation agent of the present invention, cannot improve transparency, and their odor and volatile content are also too high.

[0067] As shown in Comparative Example 9, if the toughening / transparenting agent content is too high, it will significantly increase the amount of leachate and significantly reduce the transparency, thus failing to meet the requirements.

Claims

1. A recycled polypropylene composite material, characterized in that, By weight, it includes the following components: 90-97 parts of recycled polypropylene; 0.3-0.8 parts of nanoporous silicate; Toughening / Transparency Agent 3-8 parts; Anti-precipitation agent 0.05-0.2 parts; The specific surface area of ​​nanoporous silicates is 1000-10000 m². 2 / g, D50 particle size is 10-50 nanometers; The anti-exudate agent is selected from bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate; the toughening / transparent agent is selected from at least one of ethylene-octene copolymer, olefin block copolymer, and styrene-ethylene-butene-styrene block copolymer.

2. The recycled polypropylene composite material according to claim 1, characterized in that, The toughening / transparent agent is selected from styrene-ethylene-butene-styrene block copolymer.

3. The recycled polypropylene composite material according to claim 1, characterized in that, The product also includes 0-2 parts by weight of processing aids, wherein the processing aids are selected from at least one of antioxidants, lubricants, ultraviolet absorbers, and pigments.

4. The recycled polypropylene composite material according to claim 1, characterized in that, The recycled polypropylene is random copolymerized recycled polypropylene with a light transmittance of >70% at 2mm.

5. The recycled polypropylene composite material according to claim 1, characterized in that, The recycled polypropylene composite material was tested according to the non-cooking standards in FDA 21CFR 177.1520, with maximum hexane leaching <4%, maximum xylene leaching <23%, volatile matter <0.1%, light transmittance >70% and haze <50% for a 2mm thick square plate.

6. A method for preparing the recycled polypropylene composite material according to any one of claims 1-5, characterized in that, The process includes the following steps: mixing the components evenly according to the formula, granulating the mixture by extrusion through a twin-screw extruder, with the screw temperature range being 180-230℃, to obtain a recycled polypropylene composite material.

7. The application of the recycled polypropylene composite material according to any one of claims 1-5, characterized in that, Used in the preparation of food packaging, pharmaceutical packaging, and tableware.