A low-VOC low-odor polypropylene resin composition and preparation method thereof

Abstract

The present invention relates to the field of plastics, and provides a low-VOC low-odor polypropylene resin composition and a preparation method thereof. The polypropylene resin composition comprises the following blended components: polypropylene, octavinyl silsesquioxane, an acid absorber and an antioxidant; relative to 100 parts by weight of the polypropylene, the octavinyl silsesquioxane is 0.04 to 1.8 parts by weight, the acid absorber is 0.05 to 1 part by weight, and the antioxidant is 0.05 to 1 part by weight. The total volatile organic compounds (TVOC) and odor of the polypropylene resin composition of the present invention can be significantly reduced, which well solves the shortcomings of the prior art, and the operation process is simple and reliable, the investment cost is low, and it is suitable for high-end automotive interior decoration parts, medical and food packaging materials and other fields with high environmental protection requirements.

Description

Technical Field

[0001] The invention belongs to the field of plastics, and more specifically, relates to a low-VOC low-odor polypropylene resin composition and a method for preparing the low-VOC low-odor polypropylene resin composition. Background Art

[0002] Polypropylene (PP) has been widely used in various fields of people's lives due to its excellent comprehensive performance, wide sources, high quality and low price. However, existing polypropylene materials and products have the problem of releasing volatile organic compounds (VOC) and odor to varying degrees, polluting the environment and endangering people's health. This has largely limited the application of polypropylene materials in high-end automotive interior parts, medical and food packaging materials, etc. with high environmental protection requirements. Therefore, the research and development of environmentally friendly low-VOC and low-odor polypropylene resins and materials can expand the application field of PP and meet the requirements of green and environmentally friendly materials.

[0003] At present, most of the reports on the research of low-VOC and low-odor polypropylene materials use chemical reactions, physical adsorption and melt devolatilization technology to improve the VOC emission problem in the original polypropylene materials. For example, CN101570612A reduces the VOC content by adding an inorganic photocatalyst to decompose organic small molecules, but the components are complex and the effect is limited. CN101255252A reduces the VOC of the material by adding an organic matter repellent (such as isopropanol / water), but this method has compatibility and durability problems. EP 1988122A1 uses metallocene polypropylene resin as a base resin to prepare low-VOC automotive interior materials; EP2154190A1 uses a specific light stabilizer (such as light stabilizer 119) to prepare a polypropylene composite material with a low VOC content; CN101691435A produces a low-VOC polypropylene composite material by using a specific hydrogen adjustment method to produce copolymerized polypropylene. The above inventions often only improve a certain factor that produces VOC, and cannot solve the problem of VOC produced by various factors at the same time.

[0004] Physical adsorption can adsorb all small molecules produced by PP, and adding physical adsorbents is a commonly used method. For example, CN1727389A and CN1727390A disclose the use of fine-porous silica gel and molecular sieves as adsorbents to reduce the odor of materials and the volatilization of organic compounds, and CN102276921A discloses the use of plant fibers as adsorbents to reduce the odor of polypropylene materials. Although the aforementioned method of using adsorbents can play a certain role in reducing polypropylene VOC, there is still the problem of adsorption equilibrium. At higher temperatures, the equilibrium moves in the direction of desorption, resulting in the hidden danger of VOC of polypropylene materials being released later. In addition, problems such as the adsorption efficiency of the adsorbent, its compatibility with polypropylene, and the dispersion of the adsorbent in the polypropylene matrix still exist. Therefore, it is still necessary to study new polypropylene resin compositions with low VOC content and low odor. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention is devoted to providing a low-VOC and low-odor polypropylene resin composition and a preparation method thereof.

[0006] The first aspect of the present invention provides a low-VOC low-odor polypropylene resin composition, which comprises the following components blended: polypropylene, octavinyl silsesquioxane, an acid scavenger and an antioxidant; relative to 100 parts by weight of the polypropylene, the octavinyl silsesquioxane is 0.04 to 1.8 parts by weight, the acid scavenger is 0.05 to 1 part by weight, and the antioxidant is 0.05 to 1 part by weight.

[0007] In the present invention, the polypropylene includes various types of polypropylene resins disclosed in the prior art, including homopolymer polypropylene resins and copolymer polypropylene resins.

[0008] In the present invention, the octavinyl silsesquioxane (octavinyl POSS) used is nanoscale and has the structure shown below.

[0009]

[0010] The inventors of the present invention have found that the use of nano-scale octavinyl silsesquioxane can effectively adsorb VOCs in polypropylene and chemically react with aldehyde and ketone VOCs to capture them. In addition, by fully utilizing the good assisting dispersion effect of octavinyl silsesquioxane on antioxidants in polypropylene, VOCs generated by degradation can be greatly inhibited, thereby significantly reducing the emission of VOCs in polypropylene.

[0011] The octavinyl silsesquioxane can be obtained commercially. Due to the limitation of the existing preparation method, the commercially available octavinyl silsesquioxane often contains other impurities, preferably selected from N 2Octavinyl silsesquioxane having an initial thermal degradation temperature of higher than 250° C. under atmospheric conditions, such as octavinyl silsesquioxane MS0822 from Hybridplastic Corporation of the United States.

[0012] In the low-VOC low-odor polypropylene resin composition of the present invention, the content of the octavinylsilsesquioxane is preferably 0.1 to 1.2 parts by weight, more preferably 0.2 to 0.8 parts by weight, based on 100 parts by weight of the polypropylene.

[0013] In order to improve the effect of suppressing VOC, the low-VOC low-odor polypropylene resin composition also contains an antioxidant. The antioxidant and octavinylsilsesquioxane have a good synergistic dispersion effect and can effectively reduce the VOC content in polypropylene. Relative to 100 parts by weight of the polypropylene, the antioxidant is preferably 0.1 to 0.8 parts by weight, more preferably 0.2 to 0.6 parts by weight. The antioxidant can be selected from various antioxidants commonly used in polypropylene in the prior art.

[0014] In one embodiment, the antioxidant may be selected from hindered phenol antioxidants and / or phosphate antioxidants. The hindered phenol antioxidant is preferably selected from at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester (antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl ester (antioxidant 1076), N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (antioxidant 1098) and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid (antioxidant 3114).

[0015] The phosphate antioxidant is preferably selected from tris(2,4-di-tert-butylphenol)phosphite (antioxidant 168) and / or bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite (antioxidant 626).

[0016] Preferably, the antioxidant is a mixture of a hindered phenol antioxidant and a phosphate antioxidant, and the weight ratio of the hindered phenol antioxidant to the phosphate antioxidant is 1:(1-8), preferably 1:(1-6), and more preferably 1:(1-4).

[0017] In the low-VOC low-odor polypropylene resin composition, the acid absorber can react with the dilute acid catalyst residues that may exist in the polypropylene, and play a role in reducing or inhibiting the generation of VOC due to the dilute acid-catalyzed degradation of polypropylene. The main property of the acid absorber is that it has alkalinity and can react with the acid catalyst residues to play a neutralizing role. The acid absorber required by the present invention should also be well dispersed in polypropylene. The acid absorber can be selected from at least one of metal oxides, lactates, benzoates, silicates and stearates containing Na, Ca or Zn, preferably stearates containing Na, Ca or Zn. Among them, the metal oxide is preferably selected from calcium oxide and / or zinc oxide; the silicate can be selected from natural or synthetic hydrotalcite; the stearate containing Na, Ca or Zn is preferably selected from at least one of calcium stearate, zinc stearate and sodium stearate.

[0018] The acid scavenger is preferably present in an amount of 0.08 to 0.8 parts by weight, more preferably 0.1 to 0.5 parts by weight, relative to 100 parts by weight of the polypropylene.

[0019] In addition, commonly used processing aids, such as lubricants, antistatic agents, dispersants, pigments, etc., can be added to the low-VOC, low-odor polypropylene resin composition of the present invention according to specific processing needs, and their amounts are conventional amounts or can be adjusted according to actual requirements.

[0020] The second aspect of the present invention provides a method for preparing the low-VOC low-odor polypropylene resin composition, which comprises: mixing the components including the polypropylene, octavinyl silsesquioxane, an acid scavenger and an antioxidant, and then melt blending to obtain the polypropylene resin composition.

[0021] According to a specific embodiment, the preparation method comprises the following steps:

[0022] (1) uniformly mixing the octavinyl silsesquioxane, the acid scavenger and the antioxidant to obtain a VOC inhibition mixture;

[0023] (2) uniformly mixing the VOC suppression mixture and the polypropylene to obtain a premix;

[0024] (3) melt-blending the premix to obtain the polypropylene resin composition.

[0025] According to the present invention, in step (2), the polypropylene is preferably dried polypropylene.

[0026] The mixing in steps (1) and (2) is dry mixing.

[0027] In order to better remove VOC, it is preferred that the vacuum degree of the equipment vacuum system be maintained above -0.05 MPa during the melt blending, and more preferably above -0.08 MPa.

[0028] In addition, during the processing, according to the needs of actual applications, various moldings can be performed after melt blending to shape the low-VOC, low-odor polypropylene resin composition into granules (such as by extrusion granulation), plates, etc.

[0029] In the preparation method of the present invention, the material melt blending temperature is the blending temperature usually used in polypropylene processing, which should be selected within a range that ensures that the matrix resin is completely melted without causing its decomposition, generally 180°C to 220°C, and the preferred processing temperature is 190 to 220°C; the screw speed of the melt blending equipment is 300 to 450rpm.

[0030] In the preparation method of the present invention, the mixing equipment for each material can adopt various mixing equipment used in the prior art, such as a stirrer, a kneader, etc.; the melt blending equipment used is a general blending equipment in the rubber and plastic processing industry, which can be a twin-screw extruder, a BUSS mixing unit, etc.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The octavinyl silsesquioxane used in the present invention has high thermal stability, does not generate additional VOCs during processing, use and storage, and the non-polar vinyl groups at the eight top ends of the cage structure have good compatibility with polypropylene, and the nano cage structure can also effectively adsorb small molecule hydrocarbon VOCs. At the same time, during melt processing, the vinyl groups in the octavinyl POSS can react with the carbonyl-containing aldehydes and ketones VOCs remaining in polypropylene to undergo free radical reactions, further eliminating such substances and reducing the odor intensity of polypropylene.

[0033] 2. The octavinyl silsesquioxane used in the present invention is partially cross-linked during melt processing to form a network structure covering the polypropylene matrix and surface, forming an effective protective layer, improving the equilibrium distribution coefficient of VOC on the polypropylene surface, and effectively slowing down VOC emission.

[0034] 3. The present invention uses an acid absorber to react with the dilute acid catalyst residues in the polypropylene, thereby reducing or inhibiting the generation of VOCs due to the degradation of polypropylene catalyzed by the dilute acid.

[0035] 4. The combination of octavinyl silsesquioxane, acid absorber and antioxidant can effectively improve the dispersion effect of the latter two in polypropylene resin, improve the efficiency of antioxidant and acid absorber, and significantly reduce the total amount of VOC in polypropylene.

[0036] 5. The total volatile organic compound (TVOC) and odor of the polypropylene resin composition of the present invention can be significantly reduced. Preferably, the TVOC can be lower than 50 μg·C / g, and the odor is below level 3.5, which well solves the shortcomings of the prior art. In addition, the operation process is simple and reliable, and the investment cost is low. It is suitable for high-end automotive interior parts, medical and food packaging materials and other fields with high environmental protection requirements.

[0037] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0038] Preferred embodiments of the present invention will be described in more detail below.

[0039] Examples 1-10

[0040] Examples 1-10 are used to illustrate the low VOC and low odor polypropylene resin composition and the preparation method thereof of the present invention.

[0041] The octavinyl silsesquioxane (MS0822, Hybridplastic, USA), the acid absorbent (calcium stearate, Tianjin Gangchang Chemical Co., Ltd.), the antioxidant (antioxidant 1010, a hindered phenol antioxidant, chemical name tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, and antioxidant 168, a phosphate antioxidant, chemical name tris(2,4-di-tert-butylphenol) phosphite, both from BASF, Germany) were placed in a high-speed mixer. The mixture was stirred at 300 rpm for 2 minutes to mix the components evenly to obtain the VOC inhibitor mixture; the VOC inhibitor mixture was then mixed evenly with copolymerized polypropylene (K9026, Sinopec Yanshan Branch), and then the mixture was passed through a BUSS mixer (MKD-30, BUSS, Switzerland) at 190°C to 220°C, and extruded and granulated under the condition of maintaining a vacuum degree of -0.08MPa to obtain a low-VOC, low-odor polypropylene resin composition. The specific formula is shown in Table 1, where the content of each component is in parts by weight.

[0042] The extruded pellets were dried in a constant temperature oven at 80°C for 2 hours, and the TVOC test was conducted according to the standard VDA277 of the German Association of the Automotive Industry, and the odor test was conducted according to the standard VDA270 of the German Association of the Automotive Industry. The specific performance results are shown in Table 1.

[0043] Comparative Examples 1-5

[0044] The copolymerized polypropylene, acid absorber (calcium stearate), adsorbent (RS378, Germany Daoxu Polymer Material Co., Ltd.), antioxidant and other raw materials from the same source as in Example 1-10 were weighed according to the specific proportions in Table 1, respectively placed in a high-speed mixer, and stirred at a speed of 300 rpm for 3 minutes to fully mix the components. Subsequently, the above-mentioned mixture was passed through a BUSS mixing unit in the range of 190°C to 220°C, and extruded and granulated under the condition of maintaining a vacuum degree of -0.08MPa to obtain a polypropylene composition. The specific formula is shown in Table 1, wherein the content of each component is measured in parts by weight.

[0045] The extruded pellets were dried in a constant temperature oven at 80°C for 2 hours, and the TVOC test was conducted according to the standard VDA277 of the German Association of the Automotive Industry, and the odor test was conducted according to the standard VDA270 of the German Association of the Automotive Industry. The specific performance results are shown in Table 1.

[0046] Table 1 Component ratios and performance test results of Examples 1-10 and Comparative Examples 1-5

[0047]

[0048]

[0049] From the data in Table 1, it can be seen that by adding octavinyl silsesquioxane compounded with an acid absorber and an antioxidant, the VOC content and odor of the polypropylene composition can be significantly reduced, and the total volatile organic compound (TVOC) of the polypropylene composition can be lower than 50 μg·C / g, and the odor can be reduced to below level 3.5.

[0050] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low VOC and low odor polypropylene resin composition, It is characterized in that The low-VOC low-odor polypropylene resin composition comprises the following blended components: polypropylene, octavinyl silsesquioxane, an acid scavenger and an antioxidant; relative to 100 parts by weight of the polypropylene, the octavinyl silsesquioxane is 0.2 to 0.8 parts by weight, the acid scavenger is 0.05 to 1 parts by weight, and the antioxidant is 0.05 to 1 parts by weight; the octavinyl silsesquioxane is nanometer-level and has the following structure:

2. The low VOC low odor polypropylene resin composition according to claim 1, in, The antioxidant is selected from hindered phenol antioxidants and / or phosphate antioxidants; The hindered phenol antioxidant is selected from at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid; The phosphate antioxidant is selected from tris(2,4-di-tert-butylphenol)phosphite and / or bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite.

3. The low VOC low odor polypropylene resin composition according to claim 2, in, The antioxidant is a mixture of a hindered phenol antioxidant and a phosphate antioxidant, and the weight ratio of the hindered phenol antioxidant to the phosphate antioxidant is 1:(1-8).

4. The low VOC and low odor polypropylene resin composition according to any one of claims 1 to 3, in, The antioxidant is present in an amount of 0.1 to 0.8 parts by weight relative to 100 parts by weight of the polypropylene.

5. The low VOC low odor polypropylene resin composition according to claim 4, in, The antioxidant is present in an amount of 0.2 to 0.6 parts by weight relative to 100 parts by weight of the polypropylene.

6. The low VOC low odor polypropylene resin composition according to claim 1, in, The acid absorber is selected from at least one of metal oxides, lactates, benzoates, silicates and stearates containing Na, Ca or Zn.

7. The low VOC and low odor polypropylene resin composition according to any one of claims 1 to 3 and 6, in, The acid scavenger is present in an amount of 0.08 to 0.8 parts by weight relative to 100 parts by weight of the polypropylene.

8. The low VOC low odor polypropylene resin composition according to claim 7, in, The acid scavenger is present in an amount of 0.1 to 0.5 parts by weight relative to 100 parts by weight of the polypropylene.

9. A method for preparing the low-VOC, low-odor polypropylene resin composition according to any one of claims 1 to 8, It is characterized in that The preparation method comprises: mixing components including the polypropylene, octavinyl silsesquioxane, an acid absorber and an antioxidant, and then melt-blending to obtain the polypropylene resin composition.

10. The preparation method according to claim 9, in, The preparation method comprises the following steps: (1) uniformly mixing the octavinyl silsesquioxane, the acid scavenger and the antioxidant to obtain a VOC inhibition mixture; (2) uniformly mixing the VOC suppression mixture and the polypropylene to obtain a premix; (3) melt-blending the premix to obtain the polypropylene resin composition.

11. The preparation method according to claim 9 or 10, in, During the melt blending, the vacuum degree of the equipment vacuum system is maintained above -0.05MPa.

Images