A method for preparing high melt strength polypropylene using a bifunctional acrylate monomer

Abstract

The application relates to a method for preparing high-melt-strength polypropylene by using bifunctional acrylate monomers to modify long-chain branched polypropylene. The application aims to solve the problem of low melt strength of polypropylene and the problem of affecting the application capability. The method comprises the following steps: 1, adding polypropylene particles, bifunctional acrylate monomers, an interface agent, a comonomer, an initiator and deionized water into a reactor and heating to swell; 2, heating the reaction system to carry out grafting reaction; 3, washing, extracting and drying the grafting product to obtain bifunctional acrylate modified high-melt-strength polypropylene. The application adjusts the preparation process to control the grafting effect of the high-melt-strength polypropylene, so as to improve the melt strength of the polypropylene and improve the application performance. The application is applied to the technical field of high polymer materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, and specifically relates to a method for preparing high melt strength polypropylene using bifunctional acrylate monomers. Background Technology

[0002] Polypropylene is one of the most widely used and fastest-growing resins in the world. Compared with other general-purpose thermoplastic resins (polyethylene, polyvinyl chloride, and polystyrene), it has the advantages of low density, high melting point, wide availability, low price, superior mechanical properties, and good chemical stability. In recent years, polypropylene has become an indispensable basic raw material for industries such as packaging, light industry, construction, electronics, electrical appliances, and automobiles.

[0003] However, due to the linear structure of polypropylene, its softening point and melting point are very close, resulting in a short melting range. In thermoforming, this manifests as a sharp drop in melt viscosity above the melting point, and the inability to exhibit strain hardening during stretching in the molten state. This leads to poor resistance to sag, uneven wall thickness in thermoformed products, edge curling and shrinkage during extrusion coating and calendering, and cell collapse during extrusion foaming. This drawback significantly limits the application of polypropylene in thermoforming, foaming, extrusion coating, and blow molding.

[0004] High melt strength polypropylene (HMSPP) is a novel polypropylene material developed to address the low melt strength of polypropylene. It can be obtained by increasing the relative molecular mass of polypropylene, broadening its molecular weight distribution, and introducing long-chain branched structures. Introducing long-chain modified polypropylene is an effective method. Currently, methods for long-chain modified polypropylene are generally divided into two categories: post-modification methods, which modify commercial polypropylene, and catalytic polymerization methods, which introduce long-chain branched structures into the polypropylene molecular chain through catalytic polymerization. Post-modification methods mainly include melt grafting, solution grafting, suspension grafting, solid-phase grafting, and radiation grafting. Suspension grafting has attracted widespread attention in recent years due to its advantages such as simple synthesis process, mild reaction conditions, low system viscosity, uniform mixing of reactants, easy product post-processing, and environmental friendliness, showing strong application prospects. Therefore, developing a suspension grafting method for preparing high melt strength polypropylene is highly valuable. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that the low melt strength of polypropylene affects its application capability, and thus a method for preparing high melt strength polypropylene using bifunctional acrylate monomers is invented.

[0006] This invention discloses a method for preparing high melt strength polypropylene using bifunctional acrylate monomers, which is carried out according to the following steps:

[0007] I. Polypropylene, difunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators are added to a reactor and swelled at 40-80℃ for 20 min-5 h. Then, a grafting reaction is carried out at 80-95℃ to obtain polypropylene particles grafted with difunctional acrylate. The mass ratio of polypropylene, difunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators is 1:(0.02-0.8):(0.05-0.4):(0.05-0.4):(1-6):(0.001-0.01):(0.001-0.01).

[0008] 2. The polypropylene particles grafted with bifunctional acrylate were purified by washing with deionized water and anhydrous ethanol, then extracted with acetone, and finally dried to obtain high melt strength polypropylene.

[0009] The beneficial effects of this invention are:

[0010] I. This invention uses a simple, environmentally friendly, and low-cost aqueous suspension method to modify polypropylene by grafting bifunctional acrylate monomers onto the polypropylene molecular chain.

[0011] Second, grafting polypropylene with bifunctional acrylates can produce both long-chain branched structures and cross-linked structures, causing the polypropylene molecular chains to become entangled and cross-linked, reducing the free volume, improving the melt strength of polypropylene, and enhancing its molding and processing capabilities.

[0012] This invention employs an aqueous suspension method to prepare high melt strength polypropylene. A certain amount of polypropylene, bifunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators are swollen at a certain temperature. By controlling the preparation process, the grafting effect of high melt strength polypropylene is controlled to improve the melt strength of polypropylene and thus enhance its application performance.

[0013] The high melt strength polypropylene obtained by this invention is mainly used in packaging, light industry, construction, electronics, electrical appliances, automobiles and other fields. Attached Figure Description

[0014] Figure 1 Here are the FT-IR images for comparison;

[0015] Figure 2 The XRD images are for comparison.

[0016] Figure 3 This is a comparative DMA image;

[0017] Figure 4The image is an FT-IR image from Example 1;

[0018] Figure 5 The XRD image is from Example 1;

[0019] Figure 6 The DMA image is from Example 1;

[0020] Figure 7 The FT-IR image is from Example 2;

[0021] Figure 8 The XRD image is from Example 2;

[0022] Figure 9 This is a DMA image from Example 2;

[0023] Figure 10 The image is an FT-IR image from Example 3;

[0024] Figure 11 The XRD image is from Example 3;

[0025] Figure 12 The DMA image is from Example 3;

[0026] Figure 13 The FT-IR image is from Example 4;

[0027] Figure 14 The XRD image is from Example 4;

[0028] Figure 15 This is the DMA image for Example 4. Detailed Implementation

[0029] Specific Implementation Method 1: This implementation method describes a method for preparing high melt strength polypropylene using a bifunctional acrylate monomer, which is carried out according to the following steps:

[0030] I. Polypropylene, difunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators are added to a reactor and swelled at 40-80℃ for 20 min-5 h. Then, a grafting reaction is carried out at 80-95℃ to obtain polypropylene particles grafted with difunctional acrylate. The mass ratio of polypropylene, difunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators is 1:(0.02-0.8):(0.05-0.4):(0.05-0.4):(1-6):(0.001-0.01):(0.001-0.01).

[0031] 2. The polypropylene particles grafted with bifunctional acrylate were purified by washing with deionized water and anhydrous ethanol, then extracted with acetone, and finally dried to obtain high melt strength polypropylene.

[0032] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the bifunctional acrylate monomers are one or more of the following, mixed in any proportion: dipropylene glycol diacrylate (DPGDA), 1,4-butanediol diacrylate (BDDA), 1,6-hexanediol diacrylate (HDDA), polyethylene glycol (200) diacrylate (PEG200DA), polyethylene glycol (400) diacrylate (PEG400DA), polyethylene glycol (600) diacrylate (PEG600DA), and polyethylene glycol (1000) diacrylate (PEG1000DA). Everything else is the same as in Specific Implementation Method One.

[0033] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the interface agent in step one is one or more of benzene, toluene, xylene, and cyclohexane mixed in any proportion. Everything else is the same as in Specific Implementation Method One or Two.

[0034] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the comonomer is one or both of styrene and acrylic acid mixed in any ratio. Everything else is the same as in Specific Implementation Methods One to Three.

[0035] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the antioxidant in step one is one or more of the following, mixed in any proportion: tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168), 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (antioxidant 2246), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane (antioxidant CA), and pentaerythritol diphosphite (2,4-di-tert-butylphenol) bis(2,4-di-tert-butylphenol). Everything else is the same as in Specific Implementation Methods One to Four.

[0036] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the initiator in step one is one or more of the following: dicumyl peroxide (DCP), benzoyl peroxide (BPO), azobisisobutyronitrile (AIBN), tert-butyl peroxide (TPB), bis(2-phenylethoxy) percarbonate (BPPD), dicyclopentadiene (DCPD), and ammonium persulfate (APS), mixed in any proportion. Everything else is the same as in Specific Implementation Methods One to Five.

[0037] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the grafting reaction time in step one is 0.5-8 hours. Everything else is the same as in Specific Implementation Methods One to Six.

[0038] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step two, the washing is performed 2-4 times with deionized water and anhydrous ethanol. Everything else is the same as in Specific Implementation Methods One to Seven.

[0039] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the acetone extraction time in step two is 2-24 hours. Everything else is the same as in Specific Implementation Methods One to Eight.

[0040] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the drying temperature in step two is 35-70℃. Everything else is the same as in Specific Implementation Methods One to Nine.

[0041] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0042] Example 1: A method for preparing high melt strength polypropylene using bifunctional acrylate monomers is carried out according to the following steps:

[0043] 1. Add 10g of polypropylene, 0.25g of 1,6-hexanediol diacrylate monomer, 2g of toluene, 4g of acrylic acid, 25g of deionized water, 0.02g of antioxidant 168 and 0.04g of DCPD to the reactor, first swell at 60℃ for 1 hour, and then carry out the grafting reaction at 90℃ for 4 hours.

[0044] 2. Purification of the grafted product: First, wash three times with deionized water and anhydrous ethanol, then extract with acetone for 12 hours, and finally dry at 45°C to obtain high melt strength polypropylene.

[0045] Example 2: A method for preparing high melt strength polypropylene using bifunctional acrylate monomers is carried out according to the following steps:

[0046] 1. Add 10g polypropylene, 0.5g polyethylene glycol (1000) diacrylate monomer, 2g toluene, 3g acrylic acid, 25g deionized water, 0.02g antioxidant 168 and 0.02g AIBN to the reactor, first swell at 60℃ for 2 hours, and then carry out the grafting reaction at 90℃ for 6 hours.

[0047] 2. Purification of the grafted product: First, wash with deionized water and anhydrous ethanol four times, then extract with acetone for 6 hours, and finally dry at 60°C to obtain high melt strength polypropylene.

[0048] Example 3: A method for preparing high melt strength polypropylene using bifunctional acrylate monomers is carried out according to the following steps:

[0049] 1. Add 10g of polypropylene, 1g of 1,6-hexanediol diacrylate monomer, 2g of cyclohexane, 4g of acrylic acid, 20g of deionized water, 0.02g of antioxidant 2246 and 0.04g of AIBN to the reactor, first swell at 60℃ for 1.5 hours, and then carry out the grafting reaction at 90℃ for 4 hours.

[0050] 2. Purification of the grafted product: First, wash twice with deionized water and anhydrous ethanol, then extract with acetone for 8 hours, and finally dry at 45°C to obtain high melt strength polypropylene.

[0051] Example 4: A method for preparing high melt strength polypropylene using bifunctional acrylate monomers is carried out according to the following steps:

[0052] 1. Add 10g polypropylene, 2g polyethylene glycol (1000) diacrylate monomer, 4g cyclohexane, 2g acrylic acid, 40g deionized water, 0.04g antioxidant 2246 and 0.08g DCPD to the reactor, first swell at 70℃ for 2 hours, and then carry out the grafting reaction at 90℃ for 8 hours.

[0053] 2. The product was purified by washing it three times with deionized water and anhydrous ethanol, then extracting it with acetone for 24 hours, and finally drying it at 60°C to obtain high melt strength polypropylene.

[0054] Raw polypropylene was used as a comparative example. (See attached...) Figures 1-15 The test data show that the FT-IR images of long-chain branched polypropylene modified with bifunctional acrylates as monomers in Examples 1-4 demonstrate that different processes successfully grafted different bifunctional acrylates onto the polypropylene molecular chain, and the different characteristic peak sizes represent different grafting rates of the different bifunctional acrylates. The XRD images of the long-chain branched polypropylene show ideal crystallinity of the polypropylene modified by different processes, and the DMA images of the long-chain branched polypropylene show that the mechanical properties of the long-chain branched polypropylene modified by different processes were greatly improved at 30-150℃, resulting in the preparation of high melt strength polypropylene with ideal performance.

Claims

1. A method for preparing high melt strength polypropylene using bifunctional acrylate monomers, characterized in that... The method is performed according to the following steps: I. Polypropylene, difunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators are added to a reactor and swelled at 40-80℃ for 20 min-5 h. Then, a grafting reaction is carried out at 80-95℃ for 0.5-8 h to obtain difunctional acrylate-grafted polypropylene particles. The mass ratio of polypropylene, difunctional acrylate monomers, interface agents, comonomers, deionized water, antioxidants, and initiators is 1:(0.02-0.8):(0.05-0.4):(0.05-0.4):(1-6). : (0.001-0.01): (0.001-0.01); The bifunctional acrylate monomer is one or more of dipropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate and polyethylene glycol (1000) diacrylate mixed in any proportion; the interface agent is one or more of benzene, toluene, xylene and cyclohexane mixed in any proportion; the comonomer is one or two of styrene and acrylic acid mixed in any proportion; 2. The polypropylene particles grafted with bifunctional acrylate were purified by washing with deionized water and anhydrous ethanol, then extracted with acetone, and finally dried to obtain high melt strength polypropylene.

2. The method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that... The antioxidants in step one are pentaerythritol tetrakis[B-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). 1.1.3 One or more of tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane and bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite are mixed in any proportion.

3. The method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that... In step one, the initiator is one or more of the following: dicumyl peroxide, benzoyl peroxide, azobisisobutyronitrile, tert-butyl peroxide, bis(2-phenylethoxy) peroxydicarbonate, dicyclopentadiene, and ammonium persulfate, mixed in any proportion.

4. The method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that... In step two, wash with deionized water and anhydrous ethanol 2-4 times.

5. The method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that... In step two, the acetone extraction time is 2-24 hours.

6. The method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that... The drying temperature in step two is 35-70℃.

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