A polypropylene resin composition for a high-temperature-resistant hot-fill bottle and a method for preparing the same

Abstract

The application discloses a kind of polypropylene resin composition for high-temperature hot filling bottle and preparation method thereof, the polypropylene resin composition for high-temperature hot filling bottle includes: polypropylene resin, antioxidant, nucleating agent and acid remover;The mass ratio of polypropylene resin, antioxidant, nucleating agent, acid remover is 100:(0.06-0.15):(0.02-0.06):(0.02-0.10).The polypropylene resin composition of the application has good rigidity and heat resistance, its flexural modulus and heat distortion temperature are significantly improved, and at the same time, it also has good toughness and transparency, meets the requirements of hot filling bottle produced by injection stretch blow molding process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyolefin resin, and particularly relates to a polypropylene resin composition for high-temperature hot-filling bottles and a preparation method thereof. BACKGROUND

[0002] Canning is generally divided into cold canning and hot canning. Most common filling machines are cold canning, and hot canning is relatively special. Hot canning is better when the canned materials (tea, fruit and vegetable juice, sports drinks and health drinks, etc.) are solid or have high viscosity after cooling. During hot canning, the materials are first subjected to instantaneous ultra-high temperature or short-time high-temperature sterilization, and then are filled at a temperature of 80-90 DEG C. After sealing, the inner wall of the packaging container and the bottle cap are sterilized by using the temperature of the materials themselves.

[0003] Polyethylene terephthalate (PET) is the main hot canning container material for fruit juice beverages and tea beverages on the market at present. The hot deformation temperature of PET is generally not higher than 60 DEG C, and it is not resistant to high temperature. The chemical reagents used in sterilization also pose a threat to the safety and health of food, so there is a trend of being gradually replaced by PP plastic bottles with higher safety and health performance. The hot canning temperature that can be withstood by a PP bottle is as high as 96 DEG C, so the PP bottle has more advantages in the field of hot canning.

[0004] Due to the poor transparency and poor toughness of homopolypropylene (PP) products, the application of the homopolypropylene in the fields of packaging, medical treatment, food, etc. is limited. Through random copolymerization of propylene and ethylene or other alpha-olefins, the melting point and crystallinity of the polypropylene material can be reduced, and the transparency and toughness, etc. of the polypropylene material can be improved, thereby widening the application field of the PP. The most widely used is ethylene-propylene random copolymer PP. When a traditional Z-N catalyst is used, the reactivity of ethylene is much higher than that of propylene, so that the ethylene content of the low molecular weight part of the copolymer is high, resulting in a high n-hexane extract of the product, which cannot meet the packaging requirements of food and medical supplies with high hygiene requirements. The propylene-butane random copolymer PP has the advantages of less xylene solubility, less n-hexane extract, good rigidity-toughness balance, good transparency, etc., and has a good application prospect in the fields of medical treatment or food packaging.

[0005] Chinese patent CN201811246954.5 discloses a polypropylene resin for hot canning bottles. The polypropylene resin for hot canning bottles is prepared by melt mixing, granulating, and the like of a polypropylene resin base material, an antioxidant, a nucleating agent, and an acid neutralizer. The obtained polypropylene resin has better crystallization ability, higher heat resistance and rigidity, a hot deformation temperature of 80-90 DEG C, and a flexural elastic modulus of 1200-1400 MPa. However, the additives used in the product developed by the technology are organic phosphate nucleating agents and calcium stearate or hydrogenated talc acid neutralizers. The rigidity and hot deformation temperature of the obtained product are not high, and the product cannot meet the requirements of hot canning bottles with higher processing requirements.

[0006] Chinese patent CN201811246982.7 discloses a kind of low extraction injection blow bottle with polypropylene resin, the low extraction injection blow bottle with polypropylene resin is made of polypropylene resin base material, antioxidant, nucleating agent and acid neutralizer by melt mixing granulation, the obtained polypropylene resin has strong crystallization ability, the reduction of n-hexane extract is more than 50%, suitable for injection blow molding, meet the food hygiene and safety requirements of hot canning bottle;But the effect of the product developed by this technology is biased towards the test of n-hexane extract, and the mechanical, thermal and optical properties of the product as a hot canning bottle material are not investigated.

[0007] The review article "Research and Application Progress of Bicyclo [2.2.1] / [2.2.2] Heptane Dicarboxylate Nucleating Agent" published by Shi Jianhong et al. discloses that bicyclo [2.2.1] heptane dicarboxylate and [2.2.2] heptane dicarboxylate are a dispersed polypropylene reinforcing and modifying nucleating agent that can increase the crystallization temperature of polypropylene and modify the isotropy of PP shrinkage;But this technology focuses on the excellent properties of organic carboxylate nucleating agent itself, and does not apply it to polypropylene products for hot canning bottles. SUMMARY

[0008] The purpose of the present application is to provide a kind of polypropylene resin composition for high temperature hot filling bottle and its preparation method, the resin composition has good rigidity and heat resistance, its flexural modulus and heat distortion temperature are significantly improved, at the same time, it also has good toughness and transparency, meets the requirements of hot canning bottle produced by injection blow process.

[0009] To achieve the above purpose, the present application provides a kind of polypropylene resin composition for high temperature hot filling bottle, its composition includes: polypropylene resin, antioxidant, nucleating agent and acid removing agent;The mass ratio of polypropylene resin, antioxidant, nucleating agent and acid removing agent is 100:(0.06-0.15):(0.02-0.06):(0.02-0.10);

[0010] Among them, the polypropylene resin is propylene / 1-butene random copolymer polypropylene;The antioxidant is a complex mixture formed by hindered phenolic antioxidant and phosphite antioxidant;The nucleating agent is a complex nucleating agent, which is a mixture of organic carboxylate HPN-68L and sodium benzoate, and the mass ratio of organic carboxylate HPN-68L to sodium benzoate is 1:0.5-1:4.

[0011] The polypropylene resin composition for high temperature hot filling bottle of the present application, the butene content in the propylene / 1-butene random copolymer polypropylene is 3.0-6.0wt%.

[0012] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a melt flow rate of 10-14 g / 10 min for the propylene / 1-butene random copolymer polypropylene.

[0013] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a mass ratio of 1:0.5-1:2 for 1010 and CA in the hindered phenolic antioxidant.

[0014] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a mass ratio of 1:0.5-1:2 for 1010 and CA in the hindered phenolic antioxidant.

[0015] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a mass ratio of 1:0.5-1:2 for 1010 and CA in the hindered phenolic antioxidant.

[0016] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a mass ratio of 1:0.5-1:2 for 1010 and CA in the hindered phenolic antioxidant.

[0017] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a mass ratio of 1:0.5-1:2 for 1010 and CA in the hindered phenolic antioxidant.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application has a mass ratio of 1:0.5-1:2 for 1010 and CA in the hindered phenolic antioxidant.

[0020] The polypropylene resin composition for high-temperature-resistant hot-filling bottles of the present application adds a compounded antioxidant formed by a mixture of a hindered phenolic antioxidant and a phosphite antioxidant to a propylene / 1-butene random copolymer polypropylene base; further, the hindered phenolic antioxidant is preferably a mixture of 1010 and CA, and the phosphite antioxidant is preferably 168, the ternary compounded antioxidant 1010, CA and 168 of the present application, utilizing the synergistic effect of multi-antioxidants, further enhances the heat resistance of the copolymer. DETAILED DESCRIPTION

[0021] The present application will be described in detail below by way of examples. It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content of the present application.

[0022] Evaluation and analysis method:

[0023] The melt flow rate is tested according to GB / T 3682-2000;

[0024] The ethylene and butene contents are measured by infrared spectroscopy: the ethylene content is obtained from the ethylene characteristic peak at a wave number of 700-750 cm -1 , and the butene content is obtained from the butene characteristic peak at 767 cm -1 ;

[0025] The tensile yield stress is tested according to GB / T 1040.2-2006;

[0026] The flexural modulus is tested according to GB / T 9341-2008;

[0027] The Charpy notched impact strength (at room temperature 23℃) is tested according to GB / T 1043.1-2008;

[0028] The heat distortion temperature is tested according to GB / T 1634.1-2019;

[0029] The haze is tested according to GB / T 2410-2008;

[0030] The crystallization temperature is measured by differential scanning calorimetry (DSC): under nitrogen protection, a small amount of polypropylene pellets is heated to 200℃ at a rate of 10℃ / min, kept at constant temperature for 5 min, then cooled to room temperature at a rate of 10℃ / min, and the melting and crystallization curves are recorded to obtain the melting point and crystallization temperature.

[0031] Examples 1-19

[0032] The polypropylene resin used in the examples has the characteristics shown in Table 1. The nucleating agent is a mixture of organic carboxylate HPN-68L and sodium benzoate. The antioxidant is a mixture of hindered phenol antioxidant, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane and phosphite antioxidant, tris[2,4-di-tert-butylphenyl]phosphite. The acid scavenger is a mixture of synthetic hydrotalcite powder and zinc oxide.

[0033] The polypropylene resin composition was prepared according to the following preparation method:

[0034] The polypropylene resin, antioxidant, nucleating agent and acid scavenger were added in the proportions shown in Table 2, and stirred in a high-speed mixer for 3 minutes. The mixture was then fed into a twin-screw extruder for granulation. The granules were tested for tensile and bending strength on an injection molding machine. The granulation process conditions were: 1st stage 150°C, 2nd stage 150°C, 3rd stage 160°C, 4th stage 180°C, 5th stage 200°C, 6th stage 190°C, 7th stage 170°C, 8th stage 160°C, 9th stage 160°C, and the feeding speed was 16 r / min, the screw rotation speed was 120 r / min, the melt temperature was 210°C, and the machine current was 13 A. The injection molding process conditions were: extrusion temperature 210°C, mold temperature 40°C, injection pressure 30 MPa, injection time 15 s, holding pressure 30 MPa, holding time 20 s, and cooling time 20 s. -1 -1

[0035] Comparative Examples 1-6

[0036] The polypropylene resin used in Comparative Examples 1-6 has the characteristics shown in Table 1.

[0037] The polypropylene resin composition was prepared according to the following preparation method:

[0038] The materials and proportions shown in Table 2 were added, and the other steps were the same as in Example 1.

[0039] Comparative Example 7

[0040] The polypropylene resin composition used in Comparative Example 7 has the characteristics shown in Table 1. The nucleating agent in the resin composition was only organic carboxylate nucleating agent HPN-68L. The other materials and proportions are shown in Table 2, and the other steps were the same as in Example 1.

[0041] Comparative Example 8

[0042] The polypropylene resin composition used in Comparative Example 8 has the characteristics shown in Table 1. The nucleating agent in the resin composition was organic phosphate nucleating agent, sodium 2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate. The other materials and proportions are shown in Table 2, and the other steps were the same as in Example 1.​​

[0043] The physical mechanical property test results of the polypropylene resin compositions of the examples and comparative examples are shown in Table 3.

[0044] Table 1. Characteristics of the polypropylene resins of the examples and comparative examples

[0045]

[0046]

[0047] Table 2. Composition and proportion of the antioxidants, nucleating agents and acid scavengers

[0048]

[0049]

[0050]

[0051] Table 3. Performance test results of the polypropylene resin compositions of the examples and comparative examples

[0052]

[0053]

[0054] As can be seen from Table 3, the homopolymer polypropylene has a higher flexural modulus and heat distortion temperature, but a poor impact strength and a high haze; the ethylene-propylene copolymer polypropylene has a higher impact strength and a lower haze, but a lower flexural modulus and heat distortion temperature. After the antioxidants, nucleating agents and acid scavengers are added to the propylene / 1-butene random copolymer polypropylene resin in certain composition and proportion, the impact strength, flexural modulus and heat distortion temperature are relatively high, and the haze is relatively low. In combination with the requirements in actual processing and production, the physical properties of the hot tank charge should simultaneously meet the requirements of heat distortion temperature > 90°C, flexural modulus > 1500 MPa, impact strength > 3.6 KJ / m 2 , and haze < 12%, so as to meet the requirements of most processing requirements of the hot tank charge. The polypropylene resin composition prepared by the present application can simultaneously meet the above requirements, has excellent comprehensive performance, and can meet the requirements in actual production.

[0055] From the flexural modulus and heat distortion temperature of the polypropylene resin composition without the nucleating agent, the test data are obviously lower, and therefore, the selection and use of the nucleating agent has a great influence on the present application. The present application improves the rigidity, toughness, heat resistance and transparency by adding the complex nucleating agent organic carboxylate HPN-68L and sodium benzoate and adjusting the mass ratio thereof to 1:0.5-1:4.

[0056] Of course, the present application can have other various embodiments and variations, and those skilled in the art can make various corresponding changes and variations according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and variations should all belong to the protection scope of the claims of the present application.

Claims

1. A polypropylene resin composition for high-temperature resistant hot-fill bottles, characterized in that, include: Polypropylene resin, antioxidant, nucleating agent and deacidifying agent; the mass ratio of polypropylene resin, antioxidant, nucleating agent and deacidifying agent is 100:(0.06~0.15):(0.02~0.06):(0.02~0.10); The polypropylene resin is a random copolymer of propylene / 1-butene polypropylene. The antioxidant is a compound mixture of hindered phenolic antioxidants and phosphite antioxidants; The nucleating agent is a compound nucleating agent, which is a mixture of organic carboxylate HPN-68L and sodium benzoate, wherein the mass ratio of organic carboxylate HPN-68L to sodium benzoate is 1:0.5 to 1:

4. The deacidifying agent is a compound deacidifying agent, which is a mixture of synthetic hydrotalcite powder and zinc oxide, and the mass ratio of synthetic hydrotalcite powder to zinc oxide is 1:0.5 to 1:

3.

2. The polypropylene resin composition according to claim 1, characterized in that, In the propylene / 1-butene random copolymer polypropylene, the butene content is 3.0 to 6.0 wt%.

3. The polypropylene resin composition according to claim 1, characterized in that, The melt flow rate of the propylene / 1-butene random copolymer polypropylene is 10-14 g / 10 min.

4. The polypropylene resin composition according to claim 1, characterized in that, The hindered phenolic antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, wherein the mass ratio of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane is 1:0.5 to 1:2; the phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

5. The polypropylene resin composition according to claim 1, characterized in that, The mass ratio of the hindered phenolic antioxidant to the phosphite antioxidant is 1:0.8 to 1:

4.

6. The polypropylene resin composition according to claim 1, characterized in that, The mass ratio of the organic carboxylic acid salt HPN-68L to sodium benzoate is 1:1 to 1:

3.

7. A method for preparing a high-temperature resistant hot-fill bottle polypropylene resin composition according to any one of claims 1-6, characterized in that, Includes the following steps: Polypropylene resin, antioxidant, nucleating agent and deacidifying agent are mixed at high speed in a high-speed mixer and discharged. The mixture is then added to a twin-screw extruder for granulation to obtain a polypropylene resin composition for high-temperature hot-fill bottles.

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