A preparation method of ester-soluble chlorinated polypropylene

Abstract

This invention relates to the field of organic polymer compounds, particularly to the field of IPC C08F110, and more specifically, to a method for preparing ester-soluble chlorinated polypropylene. By selecting specific polypropylene raw materials to prepare chlorinated polypropylene, and then using maleic anhydride and styrene as grafting agents, the prepared ester-soluble chlorinated polypropylene exhibits high polarity, good ester solubility, and compatibility with various polymers without affecting its performance in heat sealing and casting lamination. The prepared ester-soluble chlorinated polypropylene can be applied in the coatings and inks industry, especially in the food packaging ink industry, and can be formulated into more environmentally friendly water-based emulsions with the help of emulsifiers. Furthermore, its raw materials are healthy and environmentally friendly, making it suitable for mass production.

Description

Technical Field

[0001] This invention relates to the field of organic polymers, particularly to the field of IPC C08F110, and more specifically, to a method for preparing ester-soluble chlorinated polypropylene. Background Art

[0002] Chlorinated polypropylene is mainly used as a resin in the coatings and inks industry. The coatings and inks industry is developing in a more environmentally friendly and healthier direction. Benzene solvents in inks and coatings will be gradually phased out and replaced by organic solvents such as esters and alcohols. Therefore, it is necessary to develop chlorinated polypropylene that can be dissolved in ester or alcohol solvents.

[0003] In the prior art, patent application document with authorization announcement number CN104311711B discloses ester-soluble chlorinated polypropylene and its preparation method. By mixing polypropylene, chloroform, azobisisobutyronitrile and chlorine, ester-soluble chlorinated polypropylene is obtained, but its solubility is limited.

[0004] Patent application document with authorization announcement number CN103923262B discloses a method for grafting maleic anhydride to modify chlorinated polypropylene. By grafting maleic anhydride to modify chlorinated polypropylene, the ester solubility of chlorinated polypropylene is improved. However, maleic anhydride monomer alone cannot meet the performance requirements of chlorinated polypropylene in the coatings and inks industry.

[0005] Currently, the common process route in China is to increase the chlorine content of chlorinated polypropylene to increase the molecular polarity of chlorinated polypropylene and thus obtain ester solubility. However, increasing the chlorine content will correspondingly increase the softening point of chlorinated polypropylene, which will affect the performance of the resin in heat sealing and casting lamination. Therefore, increasing the chlorine content is not the best process route. Summary of the Invention

[0006] To address the aforementioned problems, the first aspect of this invention provides a method for preparing ester-soluble chlorinated polypropylene, comprising the steps of preparing chlorinated polypropylene and grafting modification of chlorinated polypropylene.

[0007] The preparation steps of the chlorinated polypropylene are as follows: add polypropylene and dispersant to solvent, stir at 80-100℃ until completely dissolved, add first initiator, and pass chlorine gas through. Maintain the temperature at 80-130℃ for 6-10 hours, then cool to 50-70℃ and discharge to dry to obtain chlorinated polypropylene.

[0008] Preferably, the polypropylene is one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; more preferably, it is random copolymer polypropylene.

[0009] Preferably, the random copolymer polypropylene has a melt flow rate of 3.0-10.0 g / 10 min at 230°C and a thermal property of DTUL@66psi at 60-80°C; more preferably, the random copolymer polypropylene has a melt flow rate of 7.3 g / 10 min at 230°C and a thermal property of DTUL@66psi at 72.1°C.

[0010] The melt flow rate was tested according to ASTM D1238; the thermal performance DTUL@66psi was tested according to ASTM D648.

[0011] In some preferred embodiments, the random copolymer polypropylene is purchased from ExxonMobil™ PP9513 manufactured by ExxonMobil Chemical Company.

[0012] Preferably, the dispersant is one or more of silicon dioxide, water glass, sodium tripolyphosphate, and sodium hexametaphosphate; more preferably, it is silicon dioxide.

[0013] Preferably, the weight of the dispersant is 10-20% of the polypropylene; more preferably, it is 15%.

[0014] The applicant discovered that using random copolymer polypropylene with a melt flow rate of 3.0-10.0 g / 10 min at 230℃ and a thermal performance of DTUL@66psi at 60-80℃ as raw material to prepare chlorinated polypropylene can reduce the content of insoluble matter in ester or alcohol solvents. However, the problem of uneven chlorination along the polypropylene chain still exists. The applicant unexpectedly discovered that using 10-20% silica by weight of polypropylene as a dispersant can improve the ester solubility of the prepared chlorinated polypropylene while also overcoming the agglomeration phenomenon during the chlorination process, thus obtaining chlorinated polypropylene with a more uniform chlorine distribution.

[0015] Preferably, the solvent is one or more of chloroform, carbon tetrachloride, and xylene; more preferably, it is chloroform.

[0016] Preferably, the weight ratio of polypropylene to solvent is 1:(10-20); more preferably, it is 1:15.

[0017] Preferably, the weight of the chlorine gas introduced is 2-5 times that of the polypropylene.

[0018] Preferably, the first initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide; more preferably, it is benzoyl peroxide.

[0019] Preferably, the mass concentration of the first initiator in the system is 0.1-1%; more preferably, it is 0.5%.

[0020] The applicant unexpectedly discovered that using benzoyl peroxide at a mass concentration of 0.1-1% as the first initiator could form a highly ester-soluble chlorinated polypropylene while maintaining a low chlorine content. This is likely because increasing the concentration of benzoyl peroxide triggers more free radicals, thereby increasing the concentration of graftable free radicals and resulting in chlorinated polypropylene with an unstable crystalline structure. However, excessive addition of benzoyl peroxide can increase the chlorine content, affecting the physical properties of the prepared chlorinated polypropylene, and can also lead to increased side reactions, affecting the ester solubility of the chlorinated polypropylene.

[0021] The grafting modification step of the chlorinated polypropylene is as follows: chlorinated polypropylene, graft material and second initiator are mixed in a high-speed mixer for 5-10 minutes, and then extruded and granulated to obtain the final product.

[0022] Preferably, the grafting material is one or more of maleic acid monomers, acrylic acid monomers, and styrene; more preferably, it is maleic acid monomers and styrene.

[0023] Preferably, the maleic acid monomer is one or more of maleic acid, maleic anhydride, diethyl maleic anhydride, and dibutyl maleic anhydride; more preferably, it is maleic anhydride.

[0024] Preferably, the weight ratio of maleic anhydride to styrene is (1-2):(3-8); more preferably, it is 1:5.

[0025] Preferably, the grafted material comprises 5-15% of chlorinated polypropylene by weight; more preferably, it comprises 10%.

[0026] In some preferred embodiments, maleic anhydride is used as a grafting agent to modify chlorinated polypropylene, which can improve its polarity and thus increase its solubility in ester or alcohol solvents. Applying chlorinated polypropylene grafted with maleic anhydride to resin materials can also improve its compatibility with the resin without affecting its performance in heat sealing and casting composites.

[0027] This may be because maleic anhydride contains a variety of active functional groups, and its double bonds are easily grafted onto chlorinated polypropylene under the action of an initiator. Chlorinated polypropylene grafted with maleic anhydride has high polarity and reactivity, which not only improves its ester solubility but also its compatibility with other polymer functional groups. However, if maleic anhydride is added in excess, its collision frequency with free radicals becomes too high, leading to shielding effects and the generation of side reactions. This can cause β-degradation of the chlorinated polypropylene molecular chain, resulting in a decrease in the grafting rate and affecting product performance.

[0028] The applicant unexpectedly discovered that adding a certain amount of styrene as a second monomer could maintain solubility without reducing the physical properties of chlorinated polypropylene. This is likely because the addition of styrene can inhibit the β-degradation of the polypropylene molecular chain, increasing the grafting rate. The benzene ring on the styrene molecule also has a conjugated stabilizing effect, preferentially reacting with chlorinated polypropylene free radicals, which helps inhibit the degradation of chlorinated polypropylene and also contributes to increasing the grafting rate, thus ensuring solubility without compromising the excellent physical properties of polypropylene. However, excessive styrene addition can negatively impact the grafting rate of maleic anhydride.

[0029] Through numerous experiments, the applicant discovered that when the weight ratio of maleic anhydride to styrene is (1-2):(3-8), and the weight of the grafted material is 5-15% of the chlorinated polypropylene, the prepared ester-soluble chlorinated polypropylene has high polarity, good ester solubility, and certain compatibility with various polymers, and will not affect its performance in heat sealing and casting composites.

[0030] The second initiator is one or more of azobisisobutyronitrile, dicumyl peroxide, azobisisoheptanenitrile, and benzoyl peroxide; more preferably, it is dicumyl peroxide.

[0031] The second initiator comprises 0.01-0.5% of chlorinated polypropylene by weight; more preferably, it comprises 0.2%.

[0032] Preferably, the specific implementation of the extrusion granulation is as follows: the mixed material is added to a twin-screw extruder and reacted in four temperature-controlled zones to obtain the final product.

[0033] Preferably, the temperatures of the four temperature control zones, from the inlet to the outlet, are: 60-80℃, 150-170℃, 170-190℃, and 190-210℃, respectively.

[0034] Preferably, the rotational speed of the twin-screw extruder is 90-110 r / min.

[0035] The second aspect of this application provides a method for preparing ester-soluble chlorinated polypropylene.

[0036] Beneficial effects:

[0037] 1. This invention uses random copolymer polypropylene with a melt flow rate of 3.0-10.0 g / 10 min at 230℃ and a thermal performance of DTUL@66psi at 60-80℃ as raw material to prepare chlorinated polypropylene, which can reduce the content of insoluble matter in ester or alcohol solvents.

[0038] 2. By using 10-20% silica by weight of polypropylene as a dispersant, the ester solubility of the prepared chlorinated polypropylene can be improved, while also overcoming the agglomeration of materials during the chlorination process, thus obtaining chlorinated polypropylene with uniform chlorine distribution as much as possible.

[0039] 3. By using benzoyl peroxide with a mass concentration of 0.1-1% as the first initiator, a chlorinated polypropylene with high ester solubility can be formed while maintaining a low chlorine content.

[0040] 4. By using maleic anhydride as a grafting agent to modify chlorinated polypropylene, its polarity can be improved, thereby increasing its solubility in ester or alcohol solvents. Applying chlorinated polypropylene grafted with maleic anhydride to resin materials can also improve its compatibility with resins without affecting its performance in heat sealing and casting composites.

[0041] 5. By adding a certain amount of styrene as a second monomer, this invention can ensure solubility without reducing the physical properties of chlorinated polypropylene.

[0042] 6. When maleic anhydride and styrene are selected in a weight ratio of (1-2):(3-8) as grafts, and the weight of the grafts is 5-15% of the chlorinated polypropylene, the prepared ester-soluble chlorinated polypropylene has high polarity, good ester solubility, and certain compatibility with various polymers, and will not affect its performance in heat sealing and casting composites.

[0043] 7. The chlorinated polypropylene prepared by this invention has low pollution, the raw materials are healthy and environmentally friendly, and it is suitable for mass production. It can be applied to the coating and ink industry, especially to the food packaging ink industry. Furthermore, it can be made into a more environmentally friendly water-based emulsion under the action of emulsifiers. Its raw materials are healthy and environmentally friendly and suitable for mass production. Detailed Implementation

[0044] Example

[0045] Example 1

[0046] Example 1 provides a method for preparing ester-soluble chlorinated polypropylene, the steps of which include the preparation of chlorinated polypropylene and the grafting modification of chlorinated polypropylene.

[0047] The preparation steps of the chlorinated polypropylene are as follows: polypropylene and dispersant are added to a solvent, stirred at 90°C until completely dissolved, then the first initiator is added and chlorine gas is introduced. The temperature is maintained at 110°C for 8 hours, and then cooled to 60°C to discharge and dry to obtain chlorinated polypropylene.

[0048] The polypropylene is random copolymer polypropylene.

[0049] The random copolymer polypropylene has a melt flow rate of 7.3 g / 10 min at 230 °C and a thermal property of 72.1 °C at DTUL@66 psi.

[0050] The melt flow rate was tested according to ASTM D1238; the thermal performance DTUL@66psi was tested according to ASTM D648.

[0051] The random copolymer polypropylene was purchased from ExxonMobil Chemical Company. TM PP9513.

[0052] The dispersant is silicon dioxide.

[0053] The dispersant is 15% of the weight of polypropylene.

[0054] The solvent is trichloromethane.

[0055] The weight ratio of polypropylene to solvent is 1:15.

[0056] The weight of the chlorine gas introduced is three times that of the polypropylene.

[0057] The first initiator is benzoyl peroxide.

[0058] The mass concentration of the first initiator in the system is 0.5%.

[0059] The grafting modification step of the chlorinated polypropylene is as follows: chlorinated polypropylene, graft material and second initiator are mixed in a high-speed mixer for 6 minutes, and then extruded and granulated to obtain the final product.

[0060] The grafting material is maleic acid monomer and styrene.

[0061] The maleic acid monomer is maleic anhydride.

[0062] The weight ratio of maleic anhydride to styrene is 1:5.

[0063] The grafted material is 10% of the weight of chlorinated polypropylene.

[0064] The second initiator is dicumyl peroxide.

[0065] The weight of the second initiator is 0.2% of the chlorinated polypropylene.

[0066] The specific implementation method of the extrusion granulation is as follows: the mixed material is added to a twin-screw extruder and reacted in four temperature-controlled zones to obtain the final product.

[0067] The temperatures of the four temperature control zones, from the inlet to the outlet, are 72℃, 160℃, 180℃, and 210℃, respectively.

[0068] The twin-screw extruder operates at a speed of 95 r / min.

[0069] The second aspect of this application provides a method for preparing ester-soluble chlorinated polypropylene.

[0070] Example 2

[0071] Example 2 provides a method for preparing ester-soluble chlorinated polypropylene, with the specific implementation method being the same as in Example 1. The difference is that the random copolymer polypropylene has a melt flow rate of 2.1 g / 10 min at 230°C and a thermal property of DTUL@66psi of 81.6°C.

[0072] The random copolymer polypropylene was purchased from ExxonMobil Chemical Company. TM PP9122.

[0073] Example 3

[0074] Example 3 provides a method for preparing ester-soluble chlorinated polypropylene, with the specific implementation method being the same as in Example 1. The difference is that the mass concentration of the first initiator in the system is 1.5%.

[0075] Example 4

[0076] Example 4 provides a method for preparing ester-soluble chlorinated polypropylene, with the specific implementation method being the same as in Example 1. The difference is that the grafting material is a maleic acid-based monomer.

[0077] The maleic acid monomer is maleic anhydride.

[0078] Example 5

[0079] Example 5 provides a method for preparing ester-soluble chlorinated polypropylene, with the same specific implementation as in Example 1. The difference is that the weight ratio of maleic anhydride to styrene is 1:1.

[0080] Performance testing methods

[0081] 1. Solubility test

[0082] The ester-soluble chlorinated polypropylene prepared in Examples 1-5 was mixed with a mixed solution of toluene, n-propyl ester, n-propyl ester and methylcyclohexane (volume ratio of 1:1) at a mass ratio of 20:80, and its solubility was observed. The results are recorded in Table 1.

[0083] 2. Chlorine content test

[0084] The chlorine content of the ester-soluble chlorinated polypropylene prepared in Examples 1-5 was determined according to GB / T 9872-1998, and the results are recorded in Table 1.

[0085] 3. Viscosity test

[0086] The viscosity of the ester-soluble chlorinated polypropylene prepared in Examples 1-5 was measured according to GB / T 2794-2013, and the results are recorded in Table 1.

[0087] Table 1

[0088]

Claims

1. A method for preparing ester-soluble chlorinated polypropylene, characterized in that, The steps include the preparation of chlorinated polypropylene and the grafting modification of chlorinated polypropylene. The preparation steps of the chlorinated polypropylene are as follows: polypropylene and dispersant are added to a solvent, stirred at 80-100℃ until completely dissolved, then a first initiator is added, and chlorine gas is introduced. The temperature is maintained at 80-130℃ for 6-10 hours, and then cooled to 50-70℃ for discharge and drying to obtain chlorinated polypropylene; the polypropylene is random copolymer polypropylene; the melt flow rate of the random copolymer polypropylene at 230℃ is 7.3-10.0 g / 10 min, and the thermal properties DTUL@66psi are 60-80℃; The weight of the dispersant is 10-20% of the polypropylene; the dispersant is silicon dioxide. The grafting modification step of the chlorinated polypropylene is as follows: chlorinated polypropylene, graft material and second initiator are mixed in a high-speed mixer for 5-10 minutes, and then extruded and granulated to obtain the product. The grafting material is maleic anhydride and styrene, and the weight ratio of maleic anhydride to styrene is 1:(3-8). The mass concentration of the first initiator in the system is 0.1-1%; The weight of the graft is 5-15% of chlorinated polypropylene.

2. An ester-soluble chlorinated polypropylene prepared by the method for preparing ester-soluble chlorinated polypropylene according to claim 1.

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