CN1065888C - Method for increasing reaction of polypropylene mixture by adding multifunctional monomer - Google Patents

Abstract

The invention relates to a reaction compatibilization method for polypropylene blends by adding multifunctional monomers. The method is to uniformly mix polypropylene, blending components, initiators and double bond additives in a certain proportion, and put the above mixture on a screw Perform melt blending reaction and extrusion in the extruder, the screw speed is 25-35 rpm, the temperature of the low-temperature section at both ends of the screw extruder is 160°C-180°C, and the middle high-temperature section is 200°C-230°C. Extruded as a solubilized polypropylene blend. The method can effectively inhibit the degradation of polypropylene, and obtain polypropylene blended alloy materials with good properties conveniently.

Description

Method for adding multifunctional monomer to reaction compatibilization of polypropylene blend

The invention relates to a method for adding multifunctional monomers to react and expand polypropylene blends, and belongs to the technical field of polymer chemistry.

In the past two or three decades, the alloying of polypropylene and other component polymers has been extensively studied. By blending, the excellent properties of polypropylene and other polymer materials can be combined to become an alloy material with better performance. However, in general, the compatibility between polypropylene and other polymers is poor, and alloys with good phase morphology and mechanical properties cannot be formed. For this reason, block or graft copolymers are usually added as compatibilizers. These copolymers are distributed on the phase interface and can effectively reduce the interfacial tension and increase the interfacial tension between components through chain "entanglement" or "bridge connection". compatibility. However, due to the variety of polypropylene alloy systems, it is very difficult to synthesize a corresponding block or graft copolymer as a compatibilizer for each system, and there are also great difficulties in molecular design and synthesis. Some compatibilizers even Cannot be synthesized. In order to make up for the above deficiencies, further improve efficiency and reduce costs, in recent years, reactive blending technology (Reactive Blending) has been extensively researched and developed, that is, when polymers are melt blended and extruded, through the reactivity of polymers Initiated by functional groups or adding small molecule initiators, chemical reactions occur between the blending components, and in situ (in situ) generate graft or block copolymers as compatibilizers to achieve in situ reactive compatibility (in situ Reactive Compatibility) of Polymer Blends). In terms of polypropylene blends, there are two methods of reactive blending compatibilization. One is the "two-step method", that is, first functionalize polypropylene or other blending components, and graft reactive groups on its main chain by solution grafting or melt grafting. Common methods such as grafting modified polypropylene with maleic anhydride or acrylic acid, and then reacting and blending with other polymer components containing amino groups, epoxy or oxazoline groups to form partial grafting or block copolymerization It can improve the compatibility and impact, tensile and other properties of the alloy. Another method is called "one-step method", that is, adding a catalyst-level small molecule initiator when polypropylene is blended to initiate a grafting reaction between components. The most commonly used small molecule initiators are organic peroxides. The peroxide molecules added to the blend decompose into small molecular free radicals during high-temperature extrusion, deprive the active hydrogen on the macromolecules, and generate macromolecular free radicals. When macromolecular free radicals of different components meet at the interface, a coupling termination reaction occurs to form a block or graft compatibilizer to improve the performance of the alloy. Compared with the two-step method, the one-step reaction blending method can further simplify the process and reduce the cost, and is a more popular method. It has been widely developed and applied in PE/PVC, PS/NR and other blending systems. However, during the one-step reaction blending of polypropylene blends, since the tertiary carbon macromolecular free radicals generated under the action of small molecular peroxides are very unstable, β-chain scission is prone to occur and the degradation is serious, so although it can play a role A certain reaction compatibilization effect, but can not guarantee the strength of the matrix. Therefore, in order to apply the one-step reaction blending and compatibilization method of adding small molecular peroxides to the polypropylene alloy system, only by finding a way to inhibit degradation and promote compatibilization can a polypropylene alloy with excellent performance be produced.

The purpose of the present invention is to provide a method for adding multifunctional monomers to the reaction compatibilization of polypropylene blends, which can inhibit the degradation of polypropylene in the one-step reaction blending of polypropylene blends and small molecule peroxides, and promote grafting. Branch expansion response.

The method for adding multifunctional monomers to react compatibilize polypropylene blends proposed by the present invention consists of the following steps:

(1) Evenly mix polypropylene (PP), blending components, such as acrylonitrile-styrene copolymer (AS), polystyrene (PS), initiator and double bond additive in a certain proportion, and the weight of the mixing ratio The score is:

Polypropylene + blending component 100 (where polypropylene: blending component = 1: 0.1 ~ 0.7)

Double bond additive 0.5～15

Initiator 0.05～1.5

The above-mentioned double bond additives are multifunctional monomers containing two or more double bonds in the molecule or are mixed together with other additive components. The molecular weight of the multifunctional monomer is 500-10,000, and the double bond content is 0.1-1mol/100g. The preferred range is: molecular weight 800-5,000, double bond content 0.3-1mol/100g. The double bond additives are triglyceride linoleate (GTL), hydrogenated styrene-butadiene block copolymer (SEBS), trimethylolpropane triacrylate (TMPTA), diethylene glycol diacrylate (DEGDA), tripropylene glycol diacrylate Acrylate (TPGDA), etc.

The above-mentioned initiators are thermally decomposed organic peroxide initiators, such as dicumyl peroxide and di-tert-butyl peroxide.

(2) Melt and blend the above mixture in a screw extruder and extrude it. The screw speed is 25-35 rpm. The temperature range is 200°C to 230°C, and it is a compatibilized polypropylene blend after extrusion.

The melt flow rate of the polypropylene component in the polypropylene blend compatibilized by the method of the present invention decreases with the increase of the double bond content, that is, the greater the double bond content, the better the effect of inhibiting degradation. The stronger the reactivity of the multifunctional monomer, the better the effect of promoting grafting and compatibilization. Therefore, the method can effectively inhibit the degradation of polypropylene, and conveniently obtain polypropylene blended alloy materials with good properties.

Introduce the embodiment of the present invention below:

Embodiment 1: take by weighing 350 grams of polypropylene 1300 (produced by Yanshan Petrochemical), 150 grams of acrylonitrile-styrene copolymer (AS) 40065 (produced by Hitachi, Japan), 1.25 grams of initiator dicumyl peroxide, 25 grams of double-bond additive triglyceride linoleate, after mixing evenly, extruded and granulated in a twin-screw extruder, the temperature at both ends was 170°C, the middle temperature was 215°C, and the screw speed was 30 rpm. The particle diameter of the obtained alloy dispersed phase is 4-5 microns. The PP phase was separated from the alloy and the measured melt flow rate was 23.7g/10min. Compared with no initiator and double bond additive, the particle size of alloy dispersed phase is 16-18 microns. Compared with only adding 1.25 grams of initiator without adding double bond additives, the melt flow rate of PP phase in the alloy is 83g/10min.

Example 2:

Weigh 350 grams of polypropylene 1300 (produced by Yanshan Petrochemical), 150 grams of acrylonitrile-styrene copolymer (AS) 40065 (produced by Hitachi Chemical Co., Ltd.), 1.25 grams of initiator dicumyl peroxide, 10 grams of dicumyl peroxide, The key additive, triglyceride linoleate, is mixed evenly, extruded and granulated in a twin-screw extruder, the temperature at both ends is 175°C, the temperature in the middle section is 210°C, and the screw speed is 30 rpm. The particle diameter of the obtained alloy dispersed phase is 3-4 microns. The melt flow rate of PP phase in the alloy is 33g/10min.

Example 3:

Take by weighing 350 grams of polypropylene 1300, 150 grams of acrylonitrile-styrene copolymer (AS) 40065, 2 grams of initiator dicumyl peroxide, 25 grams of double bond additive triglyceride linoleate, after mixing, in Extrude and granulate in a twin-screw extruder, the temperature at both ends is 170°C, the temperature in the middle section is 215°C, and the screw speed is 30 rpm. The particle diameter of the obtained alloy dispersed phase is 2-3 microns. The melt flow rate of PP phase in the alloy is 32.1g/10min.

Example 4:

Weigh 255 grams of polypropylene (PP) 1300, 58 grams of acrylonitrile-styrene copolymer (AS) 40065, 87 grams of cross-linked acrylate toughened acrylonitrile-styrene copolymer (AAS) 5000, 100 grams of double bond additive SEBS Kraton G 1652 (produced by Shell), 2 grams of initiator dicumyl peroxide, 25 grams of double bond additive triglyceride linoleate. After mixing evenly, extrude and granulate in a twin-screw extruder, the temperature at both ends is 178°C, the temperature in the middle section is 210°C, and the screw speed is 30 rpm. The cantilever beam impact strength of the obtained alloy is 162J/m, and the elongation at break is 530%. Compared with no initiator and double bond additive, the Izod impact strength of the alloy is 95.5J/m, and the elongation at break is 350%. Compared with only adding 1.25 grams of initiator without adding double bond additives, the alloy Izod impact strength is 65.4J/m, and the elongation at break is 100%.

Example 5:

Weigh 255 grams of polypropylene (PP) 1300, 158 grams of acrylonitrile-styrene copolymer (AS) 40065, 87 grams of cross-linked acrylate toughened acrylonitrile-styrene copolymer (AAS) 5000 (produced by Hitachi Chemical Co., Ltd. ), 100 gram double-bond additive SEBS, trade mark is Kraton G 1652 (Shell Company produces), 4 gram initiator di-tert-butyl peroxides, 50 gram double-bond additive triglyceride linoleate, after mixing, in twin-screw Extrude and granulate in the extruder, the temperature at both ends is 175°C, the temperature in the middle section is 210°C, and the screw speed is 30 rpm. The cantilever beam impact strength of the obtained alloy is 325J/m, and the elongation at break is 660%.

Embodiment 6:

When the PP/PS (70/30) blend was extruded, 2 parts of double bond additives GTL, DEGDA, TPGDA and TMPTA were added, and 3 parts of dicumyl peroxide DCP were added as the initiator. Extrude and granulate in a twin-screw extruder, the temperature at both ends is 175°C, the temperature in the middle section is 210°C, and the screw speed is 30 rpm. The particle size of the PS dispersed phase in the reaction product is only 2-3 microns. The calculation can obtain the double bond content ratio of the multifunctional monomer in the reaction blend system. Table 1 shows the corresponding relationship between the ratio of the double bond content of the four multifunctional monomers and the melt flow rate value of the polypropylene separated from the PP/PS reaction blend.

Table 1 multifunctional monomer GTL DEGDA TPGDA TMPTA double bond ratio 6.8 9.3 10.0 10.1 Melt flow rate (g/10min) 37.10 28.49 26.29 26.20

It can be seen from the table that the melt flow rate of the polypropylene component in the compatibilized blend decreases with the increase of the double bond content, that is, the higher the double bond content, the better the effect of inhibiting degradation. The stronger the reactivity of the multifunctional monomer, the better the effect of promoting grafting and compatibilization. The multifunctional monomers that meet the above two conditions are suitable additives for polypropylene reactive blending systems.

Claims (1)

1. A method for adding multifunctional monomers to react compatibilize polypropylene blends, characterized in that the method consists of the following steps: (1) Polypropylene, blending components, initiators and double bond additives are uniformly mixed in a certain proportion, and the weight fraction of the mixing ratio is: Polypropylene + blending component 100, where polypropylene: blending component = 1: 0.1 ~ 0.7 Double bond additive 0.5～15 Initiator 0.05～1.5 The above-mentioned blending component is acrylonitrile-styrene copolymer or polystyrene, The above-mentioned double bond additive is one or two kinds of triglyceride linoleate, hydrogenated butylbenzene block copolymer, trimethylolpropane triacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate a mixture of the above, Above-mentioned initiator is dicumyl peroxide or di-tert-butyl peroxide; (2) Melt and blend the above mixture in a screw extruder and extrude it. The screw speed is 25-35 rpm. The temperature range is 200°C to 230°C, and it is a compatibilized polypropylene blend after extrusion.