CN-122011652-A - High melt strength polypropylene blend and preparation method thereof

Abstract

The invention relates to the technical field of high polymer material modification, and discloses a polypropylene blend with high melt strength and a preparation method thereof, which aim to solve the problems that the melt strength of common polypropylene is low and a uniform and stable foaming structure is difficult to form, the grafting modified polypropylene constructs intramolecular and intermolecular branching connection to form a quasi-three-dimensional network structure with synergistic physical entanglement and chemical crosslinking, so that the melt strength and the melt elasticity of the blend are improved.

Inventors

• LI ZHIGUANG
• YU BO
• LI YAJUN
• LIU HONGWEI
• WANG GEN
• LEI XIGEN
• CUI SHOUZHI
• WANG GENG
• ZHAO ZUOCHEN
• SONG ZHANGUO
• WANG TAO

Assignees

• 国能包头煤化工有限责任公司

Dates

Publication Date

20260512

Application Date

20260210

Claims (10)

1. 1. A high melt strength polypropylene blend comprising a long chain branched polypropylene, a graft modified polypropylene, a free radical initiator and other additives, wherein the graft modified polypropylene is prepared by grafting a polyfunctional monomer onto a linear polypropylene matrix, the long chain branched polypropylene and the graft modified polypropylene interact in a melt blending process to form a quasi-three-dimensional network structure comprising physical entanglement and chemical crosslinking, and the quasi-three-dimensional network structure is used for improving the melt strength and stress hardening effect of the blend.
2. 2. The high melt strength polypropylene blend of claim 1, comprising, by weight, 20% to 50% long chain branched polypropylene, 30% to 60% graft modified polypropylene, 0.01% to 0.5% free radical initiator, and 0% to 5% other additives.
3. 3. The high melt strength polypropylene blend according to claim 1 or 2, wherein the long chain branched polypropylene has a melt index of 0.5 to 5 g/10min, the linear polypropylene matrix has a melt index of 1 to 50 g/10min, and the graft ratio of the graft modified polypropylene is 0.5% to 2.5%.
4. 4. The high melt strength polypropylene blend according to any one of claims 1 to 3, wherein said long chain branched polypropylene is a homo-or random co-polymer type long chain branched polypropylene having an isotacticity of at least 96% and an ethylene content of 3 to 5 wt%.
5. 5. A high melt strength polypropylene blend according to claim 1, wherein the polyfunctional monomer is a monomer having at least two unsaturated bonds capable of participating in a free radical reaction.
6. 6. The high melt strength polypropylene blend according to claim 6, wherein said polyfunctional monomer is selected from at least one of trimethylolpropane triacrylate, pentaerythritol triacrylate, and divinylbenzene.
7. 7. The high melt strength polypropylene blend according to claim 1, wherein the polyfunctional monomer is an unsaturated monomer having a hydroxyl group, an amide group, a carboxyl group, a sulfonic acid group or a dialdehyde group.
8. 8. The high melt strength polypropylene blend according to claim 1, wherein the polyfunctional monomer is at least one member selected from the group consisting of acrylamide, hydroxyethyl acrylate, acrylic acid, methacrylic acid, sodium styrenesulfonate, furanyl-or maleimide-based monomers.
9. 9. A high melt strength polypropylene blend according to claim 1 wherein the free radical initiator is an organic peroxide selected from the group consisting of dicumyl peroxide and 1, 3-bis (t-butylperoxyisopropyl) benzene.
10. 10. A process for preparing a high melt strength polypropylene blend, for preparing a polypropylene blend according to any one of claims 1 to 9, comprising the steps of: S1, premixing a linear polypropylene matrix, a multifunctional monomer, a free radical initiator and an antioxidant to obtain a premix; s2, carrying out melt reaction extrusion, granulation and drying on the premix to obtain grafted modified polypropylene master batches; s3, mixing the grafted modified polypropylene master batch, the long-chain branched polypropylene and other auxiliary agents to obtain a blending material; And S4, carrying out melt blending, extrusion granulation on the blending material to obtain the high melt strength polypropylene blend.

Description

High melt strength polypropylene blend and preparation method thereof Technical Field The invention relates to the technical field of high polymer material modification, in particular to a high melt strength polypropylene blend and a preparation method thereof. Background The polypropylene (PP) foaming material has wide application in the fields of packaging, automobiles, building heat insulation and the like due to the advantages of light weight, heat resistance, impact resistance, recyclability and the like, however, the common linear polypropylene has low melt strength and poor melt elasticity, the cell wall is easy to break in the foaming process, a uniform and fine blast hole structure is difficult to form, and the application of the polypropylene material in the high-end foaming field is severely limited. In order to improve the melt strength of polypropylene in the prior art, a synthesis method, an irradiation method or a blending method is mainly adopted, for example, a high melt strength propylene polymer with the publication number of CN118184846A and a preparation method thereof are adopted, in the polymerization process, propylene is polymerized by a polymerization catalyst and hydrogen to obtain a polypropylene-I component, and then a hydrogenation catalyst is added to generate an ultrahigh molecular weight polypropylene component; the preparation method of the high-strength polypropylene foaming bead with low irradiation intensity disclosed in the publication No. CN110483829A comprises the steps of compounding and granulating the copolymerized polypropylene, glycidyl methacrylate and a stabilizer, adding a chain extender containing carboxyl/hydroxyl/amino and a functional auxiliary agent for secondary extrusion granulation after high-energy ray irradiation, and preparing the foaming bead by a physical foaming agent batch kettle type method, wherein the melt intensity of the polypropylene can be effectively improved, but peculiar smell and degradation can be generated by the method, so that the stability of a product is influenced. Disclosure of Invention The invention aims to solve the technical problems of developing a polypropylene blend which is simple in process, low in cost and capable of effectively improving melt strength and a matched modification method thereof, and provides a polypropylene blend with high melt strength and a preparation method thereof. In order to achieve the aim, the application adopts the following technical scheme that the high melt strength polypropylene blend consists of long-chain branched polypropylene, grafted modified polypropylene, a free radical initiator and other auxiliary agents, wherein the grafted modified polypropylene is prepared by grafting a polyfunctional monomer onto a linear polypropylene matrix, the long-chain branched polypropylene and the grafted modified polypropylene interact in the melt blending process to form a quasi-three-dimensional network structure comprising physical entanglement and chemical crosslinking, and the quasi-three-dimensional network structure is used for improving the melt strength and strain hardening effect of the blend. Preferably, the modified polypropylene comprises 20-50% of long-chain branched polypropylene, 30-60% of grafted modified polypropylene, 0.01-0.5% of free radical initiator and 0-5% of other auxiliary agents by weight percent. Preferably, the melt index of the long-chain branched polypropylene is 0.5-5 g/10min, the melt index of the linear polypropylene matrix is 1-50 g/10min, and the grafting rate of the grafted modified polypropylene is 0.5-2.5%. Preferably, the long-chain branched polypropylene is homo-type long-chain branched polypropylene or random copolymerization type long-chain branched polypropylene, the isotacticity of the homo-type long-chain branched polypropylene is more than or equal to 96%, and the ethylene content in the random copolymerization type long-chain branched polypropylene is 3-5 wt%. Preferably, the multifunctional monomer is a monomer containing at least two unsaturated bonds capable of participating in a radical reaction. Preferably, the multifunctional monomer is at least one selected from trimethylolpropane triacrylate, pentaerythritol triacrylate and divinylbenzene. Preferably, the multifunctional monomer is an unsaturated monomer containing a hydroxyl group, an amide group, a carboxyl group, a sulfonic acid group or a dialdehyde group. Preferably, the multifunctional monomer is at least one selected from acrylamide, hydroxyethyl acrylate, acrylic acid, methacrylic acid, sodium styrenesulfonate, monomers containing furyl or maleimide groups. Preferably, the free radical initiator is an organic peroxide selected from dicumyl peroxide or 1, 3-bis (t-butylperoxyisopropyl) benzene. A preparation method of a high-melt-strength polypropylene blend comprises the following steps of S1, premixing a linear polypropylene matrix, a multifunctional monomer, a free radical initiator