CN1923489A

CN1923489A - Method for enabling polypropylene homopolymer to form lamella microconfiguration

Info

Publication number: CN1923489A
Application number: CN 200610116245
Authority: CN
Inventors: 余木火; 樊振兴; 敖婷婷; 焦明立; 滕翠青; 韩克清; 袁象恺
Original assignee: Donghua University
Current assignee: Donghua University
Priority date: 2006-09-20
Filing date: 2006-09-20
Publication date: 2007-03-07

Abstract

The invention relates to a method for inducing the polypropylene at low temperature with pressure into laminated micro structure. Wherein, it comprises preparing said polypropylene into blank; inducing it at low temperature with pressure into laminated structure. The inventive product has high physical property and high impact strength. And it has simple process and low energy consumption.

Description

A kind of method that makes polypropylene homopolymer form lamella microconfiguration

Technical field

The invention belongs to the high-molecular organic material field, relate in particular to a kind of induce to flow by the low temperature downforce make polypropylene homopolymer form the method for the special microstructure of lamella.

Background technology

Polypropylene (PP) plastics are owing to its low-density, cheap, easy-formation machining characteristics are widely used, but then use less owing to its actual strength (especially impact strength) is low at engineering material and structural material field.From polymer morphology, the macro property of goods is by the form decision of polymer, and the form of moulding processing method and fabrication process condition energy impact polymer.Traditional processing method generally (generally is higher than 200 ℃) and carries out under higher temperature, this makes polymer and degraded additives phenomenon serious, and in the polymeric material that obtains of traditional processing method, strand is a kind of random winding, folding and twisted state, and this makes the high strength of chemical bond itself not be converted into the intensity of goods itself on macroscopic view.

Injection mo(u)lding is the processing method of extensive use, in recent years the injection mo(u)lding Study on Self-reinforcement is emerged in an endless stream.Bayer R K, et al.Polymer Engineering and Science 1989,29,186 has reported the elongational flow injection moulding method, realized the self-reinforcing of PE on common injection machine, has made the sample that hot strength reaches 150MPa.Wang Huimin, benefit Xiao Su. the research of Self-reinforced Polyethylene material structure and performance. polymer material science and engineering, 1991,7,49 and beneficial Xiao Su. the injection moulding self-reinforcing process research of high-density polyethylene material. polymer material science and engineering, 1990,6,56～60 adopt the normal injection equipment, make intensity and elastic modelling quantity after homemade HDPE (7100F) self-reinforcing improve 6 times and 4 times respectively.Its most key technological parameter is injection pressure and injection temperature, and elongational flow inducing molecule chain-unfolding orientation and crystallization under the process conditions of the best in the injection mold filling process generate thermodynamically stable crystalline phase-shish-kebab.

In addition, roll-forming also is a kind of effectively processing method.D.C.Sun, E.M.Bergand J.H.Magill.Polym.Eng.Sci., 1990,30,635 have reported the roll-forming of PP, HDPE, PVDF and PE-PP block copolymer, the mechanical strength of finding the sample behind all roll-formings all has raising on three axial directions, and has disclosed the relation of structure and performance.But do not report all that wherein work in-process forms " laminar structured " pattern.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of method that makes polypropylene homopolymer form lamella microconfiguration, to address the deficiencies of the prior art.

Principle of the present invention is: with the section of PP homopolymers is raw material, injection mo(u)lding is a blank, then this blank is positioned in the mould, under temperature that is lower than the PP fusing point and certain pressure effect, in mould, produce and flow, because the crystalline region in the polypropylene microstructure has different mobile variation performances at low temperatures with amorphous area, thereby has produced " layer structure " in moulding material, the generation of these structures has improved the mechanical property of polymeric material.Then the polypropylene specimen after the moulding is heat-treated, in order to eliminate the residual stress in the process.

Method concrete steps of the present invention are:

1. polypropylene homopolymer blank preparation

The polypropylene homopolymer section is prepared into the polypropylene blank by injection molding forming method (this method is a conventional method), and injection temperature is 180 ℃～250 ℃, and injection pressure is 60bar～160bar;

2. the pressure inducement flowing shaping of polypropylene homopolymer blank

Blank is put into mould, and under 10 ℃～140 ℃ temperature conditions, pressure is 1MPa～2GPa, and compacting 1min-100min realizes the polypropylene homopolymer low-temperature pressure induction flow forming.

Because the crystalline region in the polypropylene microstructure has different mobile variation performances at low temperatures with amorphous area, thereby has produced " layer structure " in moulding material.This forming process can adopt equipment such as forcing press, hydraulic press or vulcanizer, and best result has certain range and precision, and range is 25 meganewtons, and precision is 0.1 meganewton.

Wherein the 1. middle best injection temperature of step is 190～230 ℃; Best injection pressure is 80～120bar;

The step 2. optimum temperature of middle pressure inducement flowing shaping is 20～100 ℃, and pressure limit the best is 0.3～1.2GPa, and the press time is preferably 3～15min.

This method also comprises heat-treats the polypropylene specimen after the moulding, and heat treated temperature is 50～160 ℃, and heat treatment time is 1min～240min, to eliminate residualinternal stress in the sample.

Wherein Zui Jia heat treatment temperature is 100～140 ℃, and heat treatment time is 10～120min.

The characteristics of processing method that the invention provides the special microstructure of polypropylene homopolymer are:

1. this method has formed the high polymer batten of typical " laminar structured " microstructure, and discovery " laminar structured " has improved the impact property of material biglyyer.

2. the polypropylene batten of this method moulding after different Technologies for Heating Processing, finds that its mechanical property further improves, and comes from the elimination that low temperature moulding causes the residual stress of material internal.

3. adopt the mobile method of low-temperature pressure induction, temperature is lower in the process, has reduced the energy consumption of copolymer in machine-shaping, has improved the performance of goods.

4. owing to be low temperature moulding, but work in-process has reduced the interpolation of multiple auxiliary agent, provides cost savings and has reduced the environmental pollution in the circulation.

This method has characteristics such as moulding process is simple, energy consumption is low.

Low-temperature pressure induction flow forming is because its moulding at low temperatures, thereby avoided the use of high temperature additive (particularly antioxidant), and can induce by high pressure and change polymer external morphology structure and improve performance (particularly impact strength).Therefore, for polypropylene material, the research of low-temperature pressure induction flow forming has great significance.

Description of drawings

Fig. 1. injection mo(u)lding PP cross section pattern (500 *)

Fig. 2. injection mo(u)lding PP cross section pattern (2000 *)

Fig. 3. the pressure inducement flowing shaping schematic diagram

Fig. 4. at 50 ℃, 1200MPa current downflow moulding PP cross section pattern (500 *)

Fig. 5. at 50 ℃, 1200MPa current downflow moulding PP cross section pattern (2000 *)

Fig. 6. at 20 ℃, 1200MPa current downflow moulding PP cross section pattern (500 *)

Fig. 7. at 20 ℃, 1200MPa current downflow moulding PP cross section pattern (2000 *)

Fig. 8. at 80 ℃, 1200MPa current downflow moulding PP cross section pattern (500 *)

Fig. 9. at 80 ℃, 1200MPa current downflow moulding PP cross section pattern (2000 *)

The specific embodiment

To help to understand the present invention by following examples, but not limit content of the present invention.

Embodiment 1:

Adopt injection molding forming method to prepare polypropylene blank (its cross section pattern such as Fig. 1 and Fig. 2 show), wherein injecting machine material tube is respectively distinguished temperature and is set at 200 ℃-205 ℃-195 ℃-190 ℃, and injection pressure is 100bar.The blank of preparation is put into homemade mould pressure flowing forming (showing as Fig. 3), under the pressure of 50 ℃ and 1.2GPa, suppressed 5 minutes, form special " laminar structured " (its cross section pattern such as Fig. 4 and Fig. 5 show).At last the sample after the moulding was heat-treated under 100 ℃ 30 minutes.

Embodiment 2:

Press embodiment 1 described method, with polypropylene homopolymer blank at room temperature (20 ℃), different pressure conditions is implemented 5 minutes (cross section pattern such as Fig. 6 and Fig. 7 show) of pressure inducement flowing shaping down, and the mechanical property without the heat treatment batten after the moulding is as follows:

20 ℃ in table 1., pressurize 5min; Mechanical property under the different briquetting pressures

Briquetting pressure	Impact strength (KJ/m2)	Hot strength (MPa)
Briquetting pressure	Impact strength (KJ/m2)	Hot strength (MPa)	PP PP-300MPa PP-600MPa PP-900MPa PP-1200MPa	1.72 1.51 2.64 4.9 8.29	33 33.3 33.9 33.5 33.1

Embodiment 3:

Pressing embodiment 1 described method, is 50 ℃ with the polypropylene homopolymer blank in temperature, and different pressure conditions was implemented pressure inducement flowing shaping 5 minutes down, and the mechanical property without the heat treatment batten after the moulding is as follows:

50 ℃ in table 2., pressurize 5min; Mechanical property under the different briquetting pressures

Briquetting pressure	Impact strength (KJ/m2)	Hot strength (MPa)
Briquetting pressure	Impact strength (KJ/m2)	Hot strength (MPa)	PP PP-300MPa PP-600MPa PP-900MPa PP-1200MPa	1.72 2.08 8.86 14.56 17.34	33 34 35.6 37.1 37.5

Embodiment 4:

Pressing embodiment 1 described method, is 80 ℃ with the polypropylene homopolymer blank in temperature, and different pressure conditions is implemented pressure inducement flowing shaping (its cross section pattern such as Fig. 8 and Fig. 9 show) 5 minutes down, and the mechanical property without the heat treatment batten after the moulding is as follows:

80 ℃ in table 3., pressurize 5min; Mechanical property under the different briquetting pressures

Briquetting pressure	Impact strength (KJ/m2)	Hot strength (MPa)
Briquetting pressure	Impact strength (KJ/m2)	Hot strength (MPa)	PP (injection moulding) PP-300MPa PP-600MPa PP-900MPa PP-1200MPa	1.7 5.1 15.41 24.9 29.8	33 39 46 46.9 46.9

Embodiment 5:

Press example 1 described method, at 100 ℃ of following heat treatment different times.The variation of sample impact property is listed as follows after the heat treatment:

Under 100 ℃ in the table 4., the polyacrylic impact strength of different heat treatment under the time

Briquetting pressure	Impact strength (KJ/m2)
Briquetting pressure	Impact strength (KJ/m2)	PP (not heat treatment) PP-10min PP-20min PP-30min PP-60min PP-120min	17.3 23.1 28.3 30.0 29.0 29.8

Embodiment 6:

Press example 1 described method, at 140 ℃ of following heat treatment different times.The variation of sample impact property is listed as follows after the heat treatment:

Under 140 ℃ in the table 4., the polyacrylic impact strength of different heat treatment under the time

Briquetting pressure	Impact strength (KJ/m2)
Briquetting pressure	Impact strength (KJ/m2)	PP (not heat treatment) PP-10min PP-20min PP-30min PP-60min PP-120min	17.3 43.2 42.9 45.6 45.1 47.1

Claims

1. method that makes polypropylene homopolymer form lamella microconfiguration is characterized in that the concrete steps of this method are:

1. polypropylene homopolymer blank preparation

The polypropylene homopolymer section is prepared into the polypropylene blank by injection molding forming method, and injection temperature is 180 ℃～250 ℃, and injection pressure is 60bar～160bar;

2. the pressure inducement flowing shaping of polypropylene homopolymer blank

2. method according to claim 1 is characterized in that the 1. middle injection temperature of step is 190～230 ℃; Injection pressure is 80～120bar.

3. method according to claim 1 is characterized in that the temperature of pressure inducement flowing shaping was 20～100 ℃ during step 2., and pressure is 0.3～1.2GPa, and the press time is 3～15min.

4. according to each described method of claim 1-3, it is characterized in that this method comprises that also the polypropylene specimen after the moulding heat-treats, heat treated temperature is 50～160 ℃, heat treatment time is 1～240min.

5. method according to claim 4 is characterized in that described heat treatment temperature is 100～140 ℃, and heat treatment time is 10～120min.