Method for preparing polypropylene with high melt strength by using bifunctional acrylate monomer

Abstract

The invention discloses a method for preparing high-melt-strength polypropylene by using a bifunctional acrylate monomer, and relates to a method for preparing the high-melt-strength polypropylene by using bifunctional acrylate as a monomer long-chain branched modified polypropylene. The invention aims to solve the problem that the application capability of polypropylene is influenced due to low strength of polypropylene melt. The method comprises the following steps: 1, adding polypropylene particles, a bifunctional acrylate monomer, an interface agent, a co-monomer, an initiator and deionized water into a reactor, and heating for swelling; 2, heating the reaction system, and carrying out a grafting reaction; and 3, washing, extracting and drying the grafted product to obtain the bifunctional acrylate modified high-melt-strength polypropylene. The grafting effect of the high-melt-strength polypropylene is regulated and controlled by regulating and controlling the preparation process, so that the melt strength of the polypropylene is improved, and the application performance of the polypropylene is further improved. The method is applied to the technical field of polymer materials.

Description

Technical Field

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

[0002] Polypropylene is one of the most widely used and fastest growing resins in the world. Compared with other common thermoplastic resins (polyethylene, polyvinyl chloride and polystyrene), it has the characteristics of low density, high melting point, wide source, low price, excellent mechanical properties and good chemical stability. In recent years, polypropylene has developed into one of the indispensable basic raw materials for packaging, light industry, construction, electronics, electrical appliances, automobiles and other industries.

[0003] However, due to the linear structure of polypropylene itself, the softening point of the polymer is very close to the melting point, and the melting range is short. In the thermoforming process, when the temperature is higher than the melting point, the melt viscosity drops sharply, and strain hardening cannot occur when stretched in the molten state, which leads to poor anti-sag of the polymer, uneven wall thickness of the thermoformed product, edge curling and shrinkage during extrusion coating and calendering, and cell collapse during extrusion foaming. This shortcoming greatly limits the application of polypropylene in thermoforming, foaming, extrusion coating, blow molding, etc.

[0004] High melt strength polypropylene (HMSPP) is a new type of polypropylene material developed for the low melt strength of polypropylene. It can be obtained by increasing the relative molecular mass of polypropylene, broadening the molecular weight distribution, and introducing long-chain branching structure. Introducing long-chain modified polypropylene is an effective method. At present, the methods of long-chain modified polypropylene are generally divided into two categories, one is the post-modification method, that is, modifying commercial polypropylene, and the other is the catalytic polymerization method, that is, introducing long-chain branching structure into the polypropylene molecular chain through catalytic polymerization. The post-modification method is mainly divided into melt grafting method, solution grafting method, suspension grafting method, solid phase grafting method and radiation grafting method. The suspension grafting method 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 reaction materials, easy product post-processing and green environmental protection, and has a strong application prospect. Therefore, it is very valuable to develop a method for preparing high melt strength polypropylene by suspension grafting. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the polypropylene has low melt strength, which affects its application ability, and thus invents a method for preparing high melt strength polypropylene using a bifunctional acrylate monomer.

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

[0007] 1. Adding polypropylene, bifunctional acrylate monomer, interface agent, comonomer, deionized water, antioxidant and initiator into a reactor, swelling at 40-80°C for 20min-5h, and then carrying out grafting reaction at 80-95°C to obtain bifunctional acrylate grafted polypropylene particles; wherein the mass ratio of polypropylene, bifunctional acrylate monomer, interface agent, comonomer, deionized water, antioxidant and initiator 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. Purify the bifunctional acrylate grafted polypropylene particles, wash them with deionized water and anhydrous ethanol respectively, extract them with acetone, and then dry them to obtain high melt strength polypropylene.

[0009] Beneficial effects of the present invention:

[0010] 1. The present invention uses a simple, environmentally friendly, low-cost aqueous suspension method to modify polypropylene, and grafts a bifunctional acrylate monomer onto the polypropylene molecular chain.

[0011] Second, using bifunctional acrylate to graft polypropylene can produce a long-chain branched structure on the one hand, and a cross-linked structure on the other hand, so that the polypropylene molecular chains are entangled and cross-linked, and the free volume is also reduced, thereby improving the melt strength of polypropylene and its molding and processing capabilities.

[0012] The invention adopts a water phase suspension method to prepare high melt strength polypropylene. After a certain amount of polypropylene, a bifunctional acrylate monomer, an interface agent, a comonomer, deionized water, an antioxidant and an initiator are swollen at a certain temperature, the grafting effect of the high melt strength polypropylene is regulated by regulating the preparation process, so as to improve the melt strength of the polypropylene and further improve its application performance.

[0013] The high melt strength polypropylene prepared by the invention is mainly used in the fields of packaging, light industry, construction, electronics, electrical appliances, automobiles, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FT-IR image of the comparative example;

[0015] Figure 2 XRD pattern of comparative example;

[0016] Figure 3 DMA image of the comparative example;

[0017] Figure 4is the FT-IR image of Example 1;

[0018] Figure 5 is the XRD pattern of Example 1;

[0019] Figure 6 is the DMA image of Example 1;

[0020] Figure 7 is the FT-IR image of Example 2;

[0021] Figure 8 is the XRD pattern of Example 2;

[0022] Fig. 9 It is the DMA image of Example 2;

[0023] Fig.10 is the FT-IR image of Example 3;

[0024] Fig.11 is the XRD pattern of Example 3;

[0025] Fig.12 It is the DMA image of Example 3;

[0026] Fig.13 is the FT-IR image of Example 4;

[0027] Fig.14 is the XRD pattern of Example 4;

[0028] Fig.15 This is the DMA image of Example 4. DETAILED DESCRIPTION

[0029] Specific implementation method 1: This implementation method uses a bifunctional acrylate monomer to prepare a high melt strength polypropylene, which is carried out according to the following steps:

[0030] 1. Adding polypropylene, bifunctional acrylate monomer, interface agent, comonomer, deionized water, antioxidant and initiator into a reactor, swelling at 40-80°C for 20min-5h, and then carrying out grafting reaction at 80-95°C to obtain bifunctional acrylate grafted polypropylene particles; wherein the mass ratio of polypropylene, bifunctional acrylate monomer, interface agent, comonomer, deionized water, antioxidant and initiator 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. Purify the bifunctional acrylate grafted polypropylene particles, wash them with deionized water and anhydrous ethanol respectively, extract them with acetone, and then dry them to obtain high melt strength polypropylene.

[0032] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the bifunctional acrylate monomer is one or more of 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) mixed in any ratio. The rest is the same as the specific embodiment 1.

[0033] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: in step 1, the interface agent is one or more of benzene, toluene, xylene and cyclohexane mixed in any ratio. The rest is the same as specific implementation method 1 or 2.

[0034] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the comonomer is one or two of styrene and acrylic acid mixed in any ratio. The rest is the same as specific embodiments 1 to 3.

[0035] Specific embodiment 5: This embodiment is different from specific embodiments 1 to 4 in that: in step 1, the antioxidant type is one or more of 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 bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite (antioxidant 626) mixed in any ratio. Others are the same as specific embodiments 1 to 4.

[0036] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that: in step 1, the initiator type is one or more of dicumyl peroxide (DCP), dibenzoyl peroxide (BPO), azobisisobutyronitrile (AIBN), tert-butyl perbenzoate (TPB), bis(2-phenylethoxy) peroxydicarbonate (BPPD), dicyclopentadiene (DCPD) and ammonium persulfate (APS) mixed in any ratio. Others are the same as specific embodiments 1 to 5.

[0037] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the grafting reaction time in step 1 is 0.5-8 hours. The rest is the same as specific embodiments 1 to 6.

[0038] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that: in step 2, deionized water and anhydrous ethanol are used for washing 2-4 times. The rest is the same as specific embodiments 1 to 7.

[0039] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the acetone extraction time in step 2 is 2-24 hours. The rest is the same as specific embodiments 1 to 8.

[0040] Specific embodiment 10: This embodiment is different from specific embodiments 1 to 9 in that the drying temperature in step 2 is 35-70° C. The rest is the same as specific embodiments 1 to 9.

[0041] The content of the present invention is not limited to the content of the above-mentioned embodiments. The combination of one or several specific embodiments can also achieve the purpose of the invention.

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

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

[0044] Second, the grafted product was purified by first washing it with deionized water and anhydrous ethanol for three times, then extracting it with acetone for 12 hours, and finally drying it at 45°C to obtain high melt strength polypropylene.

[0045] Example 2: A method for preparing high melt strength polypropylene using a bifunctional acrylate monomer 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 into the reactor, first swell at 60°C for 2 hours, and then carry out grafting reaction at 90°C for 6 hours;

[0047] 2. The grafted product was purified by first washing it with deionized water and anhydrous ethanol for 4 times, then extracting it with acetone for 6 hours, and finally drying it at 60°C to obtain high melt strength polypropylene.

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

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

[0050] 2. Purify the grafted product by first washing it twice with deionized water and anhydrous ethanol, then extracting it with acetone for 8 hours, and finally drying it at 45°C to obtain high melt strength polypropylene.

[0051] Example 4: A method for preparing high melt strength polypropylene using a bifunctional acrylate monomer 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 into the reactor, first swell at 70°C for 2 hours, and then carry out grafting reaction at 90°C for 8 hours;

[0053] 2. Purify the product by first washing it with deionized water and anhydrous ethanol for 3 times, then extracting it with acetone for 24 hours, and finally drying it at 60°C to obtain high melt strength polypropylene.

[0054] Original polypropylene was used as a comparative example. Figures 1 to 15 From the test data, it can be seen that the FT-IR images of the long-chain branched modified polypropylene using difunctional acrylate as monomer in Examples 1-4 show that different difunctional acrylates are successfully grafted onto the polypropylene molecular chain by different processes, and different characteristic peak sizes represent different grafting rates of different difunctional acrylates. The XRD images of the long-chain branched modified polypropylene show that the crystallization of the modified polypropylene by different processes is ideal, and the DMA images of the long-chain branched modified polypropylene show that the mechanical properties of the long-chain branched modified polypropylene by different processes at 30-150°C are greatly improved, and high melt strength polypropylene with ideal performance is prepared.

Claims

1. A method for preparing high melt strength polypropylene using a bifunctional acrylate monomer, characterized in that The method is carried out according to the following steps:

1. Adding polypropylene, bifunctional acrylate monomer, interface agent, comonomer, deionized water, antioxidant and initiator into a reactor, swelling at 40-80°C for 20min-5h, and then carrying out grafting reaction at 80-95°C to obtain bifunctional acrylate grafted polypropylene particles; wherein the mass ratio of polypropylene, bifunctional acrylate monomer, interface agent, comonomer, deionized water, antioxidant and initiator is 1:(0.02-0.8):(0.05-0.4):(0.05-0.4):(1-6):(0.001-0.01):(0.001-0.01); 2. Purify the bifunctional acrylate grafted polypropylene particles, wash them with deionized water and anhydrous ethanol respectively, extract them with acetone, and then dry them to obtain high melt strength polypropylene.

2. A method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that 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 ratio.

3. A method for preparing high melt strength polypropylene using a bifunctional acrylate monomer according to claim 1, characterized in that In step 1, the interface agent is one or more of benzene, toluene, xylene and cyclohexane mixed in any ratio.

4. The method for preparing high melt strength polypropylene using bifunctional acrylate monomers according to claim 1, characterized in that The comonomer is one of styrene and acrylic acid or a mixture of the two in any ratio.

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

6. A method for preparing high melt strength polypropylene using bifunctional acrylate monomers according to claim 1, characterized in that In step 1, the initiator type is one or more of diisopropylbenzene peroxide, dibenzoyl peroxide, azobisisobutyronitrile, tert-butyl perbenzoate, bis(2-phenylethoxy) peroxydicarbonate, dicyclopentadiene and ammonium persulfate mixed in any ratio.

7. A method for preparing high melt strength polypropylene using bifunctional acrylate monomers according to claim 1, characterized in that The grafting reaction time in step 1 is 0.5-8h.

8. The method for preparing high melt strength polypropylene using bifunctional acrylate monomers according to claim 1, characterized in that In step 2, the sample is washed 2-4 times with deionized water and anhydrous ethanol.

9. The method for preparing high melt strength polypropylene using bifunctional acrylate monomers according to claim 1, characterized in that The acetone extraction time in step 2 is 2-24h.

10. The method for preparing high melt strength polypropylene using bifunctional acrylate monomers according to claim 1, characterized in that The drying temperature in step 2 is 35-70°C.

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