CN101200524A - A kind of low surface tension polypropylene material and preparation method thereof - Google Patents

Abstract

The present invention relates to grafting modified polypropylene material and the preparation method, in particular to a recipe of low interfacial tension polypropylene material and the preparation method, pertaining to the art of polymer processing technology. The present invention mixes the polypropylene material with non-saturated double-bond fluorochemical monomer including low interfacial tension and co-grafting monomer, adopts the double-screw fusional grafting method to prepare the low interfacial tension waterproof polypropylene material or extrude the product. The obtained solid surface can be greatly decreased and the waterproof performance can be effectively improved. The present invention adopts the fusional grafting reaction to obtain the fluoric high polymer. Compared with the electric ion and optical radiation method, the present invention facilitates the grafting process, easily controls the process and reduces the process complexity, even avoids the possible radioactive damages caused by these grafting processes, protects the body health of operational staff and eliminates the radioactive pollution to the environment.

Description

A kind of low surface tension polypropylene material and preparation method thereof

technical field

The invention relates to a graft modified polypropylene material and a preparation method thereof, in particular to a low surface tension polypropylene material and a preparation method thereof, and belongs to the technical field of polymer processing.

Background technique

Polypropylene is one of the most widely used thermoplastic polymer materials today. Compared with other general-purpose polymer materials, it has the characteristics of low price, small specific gravity, excellent mechanical properties such as yield strength and tensile strength, and has been widely used. Used in various industrial fields.

Since the 20th century, with the development of polymer graft modification technology and the continuous improvement of people's living standards, people have continuously put forward higher requirements for the performance of polymer materials. Polymer materials themselves often have insufficient aging resistance, corrosion resistance, salt resistance, oil resistance, water resistance, weather resistance, and pollution resistance in harsh environments. The fluorine-containing compound attracts attention because of its excellent heat resistance, weather resistance, chemical resistance, chemical corrosion resistance, and excellent salt spray resistance and stain resistance. In recent years, the development of fluorine-containing compound preparation technology has provided the possibility for the modification technology of fluorine-containing compounds in polymers, especially the possibility of technical development and technical application in polymer modification.

Fluorine-containing compounds containing unsaturated double bonds, like the usual non-fluorine compounds with double bonds, have good homopolymerization and copolymerization with other monomers, and the resulting polymers have extremely low surface free energy, and some The surface free energy of the polymer is even lower than that of PTFE. Adding a small amount of such fluorine-containing monomers during the synthesis of polymers can greatly improve the surface properties of the polymers. In addition, the phase separation of side-chain fluorine-containing groups at the molecular level leads to an ordered "comb-like" structure of long-side-chain (meth)acrylate fluorine-containing esters, making it possible to become a class with excellent properties such as optical nonlinearity. side chain liquid crystal polymers. Due to the extremely low polarizability of the fluorine atoms and the outward orientation of the fluorine-containing side chains, it forms a "shielding protection" for the main chain and internal molecules, so that the copolymers and homopolymers of fluorine-containing compounds with double bonds have many other excellent properties. Features, such as extremely low refractive index, good chemical inertness, biocompatibility, weather resistance, stain resistance, water and oil resistance, UV resistance, etc. Therefore, fluorine-containing compounds containing double bonds will have good applications in the fields of fabric finishing, cultural relic protection, anti-corrosion and anti-fouling materials, plastic optical fibers, contact lenses, and anti-reflection materials.

The properties of fluorine-containing compounds containing unsaturated double bonds depend on the fluorine atoms in the molecule. The ability of fluorine atoms to combine electrons is strong, the polarizability is small, the refractive index is low, and the electronegativity is the highest among all elements, so fluoropolymers have excellent electrical and optical properties. In addition, because the fluorine atomic radius is very small, the C-F bond length is short and the bond energy is large. The heat resistance, oxidation resistance and chemical resistance of the fluorine-containing compound polymer containing double bonds are particularly excellent. At the same time, the intermolecular cohesion of fluoropolymer is low, the molecular force between air and polymer interface is small, and the surface free energy is low, so it is difficult to be infiltrated or adhered by other liquids or solids, which can make the surface friction coefficient of the material low. Fluorochemical modified polymer with double bonds has excellent water resistance, oil resistance and stain resistance.

At present, the application of fluorine-containing compounds containing double bonds in polymer modification is mainly in the surface coating of plastics and rubber products and the salt resistance treatment of other polymers. A Di Giamni etc. in UV-cured fluorinated coatings for plastics: effect of the photoinitiator and of the substrate filler on adhesion ([J]. International Journal of Adhension & Adhensives24 (2004): 513-518), disclosed that fluorinated acrylic The research results of forming a coating layer on polypropylene or polyethylene products under the irradiation of ultraviolet rays, the principle is that the matrix material undergoes a "hydrogen abstraction" reaction through the irradiation of UV ultraviolet rays, forming macromolecular free radicals, which in turn triggers acrylic acid containing Fluoroester grafts polypropylene or polyethylene. The research shows that when carbon black is not used as a filler material, acrylic fluorine-containing ester monomers can form a firm and dense network structure on the surface of olefin polymer materials, so that the matrix material has excellent properties, such as high thermal Stability, hydrophobicity and transparency etc. At the same time, it is pointed out that when carbon black is used as a filler, the grafting reaction cannot proceed because it hinders the generation of free radicals on the polyolefin substrate. In Barrier properties of plasma and chemically fluorinated polypropylene and polyethyleneterephthalat ([J].Surface and coating technology 74-75(1995): 910-918), J.F Friedrich et al. used plasma method and chemical deposition method to form on the surface of polypropylene and PET respectively. Fluorine-containing coatings are analyzed for their resistance to fuels and solvents.

The above-mentioned polypropylenes all form fluorine-containing coatings on the surface of polypropylene to prepare fluorine-containing polypropylene materials or products, which have not been reported so far.

Contents of the invention

In order to overcome the shortcomings of the prior art, the object of the present invention is to provide a modified polypropylene material with simple preparation method, energy saving, high monomer grafting rate and good water resistance and a preparation method thereof.

In order to achieve the above object of the invention, the technical solution adopted in the present invention is: a low surface tension polypropylene material, characterized in that: the following components are used to obtain the material through graft copolymerization, and the content of each component by weight It is: 100 parts of polypropylene, 1-15 parts of fluorine-containing graft monomer, 1-10 parts of graft co-monomer, 0.1-1.5 parts of initiator, 0.2-1.0 part of antioxidant; the fluorine-containing graft monomer The body is a fluorine-containing compound containing at least one unsaturated double bond in the molecule; the grafted comonomer is styrene; the initiator is an organic peroxy compound;

The branched chain of the low surface tension polypropylene material contains -C _x F _y or -C _x F _y - chemical structural group; in -C _x F _y , its x≥1, y≤2x+1 ; In -C _x F _y -, its x≥1, y≤2x.

In a further technical solution, the polypropylene material also includes reinforcing fibers, and the ratio of polypropylene to reinforcing fibers is 100:10-25 by weight.

In the above technical scheme, the organic peroxy compound is dicumyl peroxide or benzoyl peroxide.

In the above technical scheme, the antioxidant is selected from the group consisting of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, three (2,4-di-tert-butylphenyl) ) phosphite or dilauryl thiodipropionate.

The present invention also provides a method for preparing a low surface tension polypropylene material, comprising the following steps:

(1) Mix the fluorine-containing grafting monomer, initiator and co-grafting monomer, then add the mixed system into dry polypropylene, add the antioxidant, and mix evenly with a high-speed mixer; by weight , the ratio of polypropylene, fluorine-containing graft monomer, graft co-monomer, initiator and antioxidant is 100:1～15:1～10:0.1～1.5:0.2～1.0; the fluorine graft The graft monomer is a fluorine-containing compound containing at least one unsaturated double bond in the molecule; the graft comonomer is styrene; the initiator is an organic peroxy compound;

(2) Extrude the above-mentioned mixed materials through a twin-screw extruder, form or granulate them into low surface tension polypropylene new ecological pellets, or reshape the pellets to obtain low surface tension polypropylene materials.

In the above technical solution, the extrusion processing of the twin-screw extruder adopts multi-stage heating, the temperature of the first 2-3 stages is 170-180°C, and the temperature of the other stages is 185-200°C; the material is heated in the twin-screw extruder The total residence time in is 1 to 10 minutes.

The mechanism of the invention is: the initiator generates free radicals at a certain temperature, and the free radicals dehydrogenate the PP chain to generate macromolecular free radicals. In the absence of grafted comonomers, due to the low reactivity of fluorine-containing monomers, the methyl and methylene groups on the polypropylene chain tend to cross-link after dehydrogenation, while the methine dehydrogenates due to steric hindrance , tends to crack, therefore, the grafting reaction of PP is often accompanied by degradation. When there is styrene as a graft co-monomer, since the unsaturated double bond of styrene is more reactive to free radicals on the PP molecular chain than the unsaturated double bond of the fluorine-containing graft monomer, styrene is preferentially grafted To form a stable styrene-based macromolecular free radical on the PP molecular chain, coupled with the protection of antioxidants, so that the tendency of PP chain breakage is greatly suppressed, the macromolecular free radical and the unsaturated double of the fluorine-containing monomer The bond reaction effect is much greater than the reaction effect between the unsaturated double bond of the fluorine-containing monomer and PP, and finally the polypropylene can be modified to have the characteristics of partial fluoride.

The present invention uses fluorine-containing compounds with unsaturated double bonds to graft polypropylene. At the same time, in order to reduce the degradation of polypropylene and increase the grafting rate of monomers, the co-grafting monomers are introduced into the melt grafting of polypropylene. During the modification, a grafted monomer-modified polypropylene product with excellent performance is obtained.

Due to the use of the above-mentioned technical solutions, the present invention has the following significant advantages:

(1) Compared with pure polypropylene, the grafted polypropylene obtained in the present invention has significantly lower surface energy (expressed as solid critical surface tension or wettability to water) and significantly improved water resistance.

(2) In the present invention, the grafting monomer adopts the fluorine-containing compound containing unsaturated double bonds, which can make the modified polypropylene have the characteristics of fluoride, the monomer grafting rate of the product is improved, and the new application of the material has been developed.

(3) The present invention adopts melting grafting reaction to obtain fluorine-containing polymer, which is more convenient for grafting and processing than ionization and light radiation methods, and the processing process is also easy to control, reducing the complexity of the process; and eliminating the need for ionization 1. Radiation damage that may be caused by photoradiation grafting protects the health of operators and eliminates radiation pollution to the environment.

Description of drawings

Fig. 1 is the X-photoelectron energy spectrum full spectrogram of pure polypropylene before grafting;

Fig. 2 is the full spectrum diagram of the grafted polypropylene X-ray photoelectron energy spectrum that the embodiment of the present invention 1 prepares;

Fig. 3 is the infiltration state diagram of the water on the pure polypropylene surface before grafting;

Fig. 4 is a diagram showing the wetting state of water on the surface of the grafted polypropylene prepared in Example 1 of the present invention.

Detailed ways

Below in conjunction with embodiment and accompanying drawing, the present invention will be further described:

Example 1:

By weight, the proportions of the components for preparing the low surface tension polypropylene material are:

Polypropylene: 100 parts

Fluorinated graft monomer dodecafluoroheptyl methacrylate: 5 parts

Grafted comonomer styrene: 3 parts

Initiator dicumyl peroxide: 0.8 parts

Antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (1010): 0.4 parts

Antioxidant tris(2,4-di-tert-butylphenyl)phosphite (168): 0.4 parts

The preparation process is as follows:

Mix dodecafluoroheptyl methacrylate, styrene, dicumyl peroxide, antioxidant 1010, and antioxidant 168 according to the ratio of the above components, and then add the mixed system to 100 parts of dry polypropylene After adding conventional additives for conventional processing, use a high-speed mixer to mix evenly.

The above mixed material is extruded with a 9-stage heated twin-screw extruder, and the temperatures of each stage are: T ₁ = 170°C, T ₂ = 175°C, T ₃ = 180°C, T ₄ = 185°C , T ₅ =185°C, T ₆ =190°C, T ₇ =195°C, T ₈ =195°C, T ₉ =190°C, the total residence time in the screw is about t=2.0min, and the screw speed is r= Melt grafting is carried out at 72r·min ^-1 , and then the grafted product is extruded, cooled, and pelletized to obtain the product.

The granule prepared by the technical solution of this embodiment is dried, injected or pressed into a sample, and its performance is measured, and its water resistance and its surface tension are characterized by the method of the contact angle to water. Table 1 is the material (connected to Branch PP) and pure polypropylene products (pure PP) performance comparison.

Table 1

sample Contact angle to water θ(°) Increased contact angle (%) Tensile strength (Mpa)   Flexural modulus (Mpa) Pure PP 78.6 -- 33.46 1056.3 Graft PP 90.5 15.14 32.77 1028.5

Referring to accompanying drawings 1 and 2, Fig. 1 is the full spectrum of X-ray photoelectron spectrum of pure polypropylene before grafting; Fig. 2 is the full spectrum of X-ray photoelectron spectrum of grafted polypropylene prepared according to the technical scheme of Example 1 of the present invention. It can be seen from Figure 1 and Figure 2 that compared with the full spectrum of photoelectron spectrum of pure polypropylene, the full spectrum of X-ray photoelectron spectrum of grafted polypropylene has two more peaks, which are respectively is the characteristic peak of O element and F element, indicating that the grafted polypropylene contains O element and F element.

Referring to accompanying drawings 3 and 4, Fig. 3 is a diagram of the infiltration state of water on the surface of pure polypropylene before grafting; Fig. 4 is a diagram of the infiltration state of water on the surface of grafted polypropylene prepared by the technical solution of this embodiment. As can be seen from Figure 3 and Figure 4, compared with the grafted polypropylene sample provided by the technical solution of this embodiment, the water droplets formed on the surface of the pure polypropylene sample are much flatter than the water droplets on the surface of the grafted polypropylene, and the contact angle It is also relatively small, therefore, it shows that the surface force of pure polypropylene is much larger than that of grafted polypropylene. It can be seen that the grafted polypropylene prepared according to the technical solution of the present invention has relatively low surface force.

Example 2:

The ratio of each component to prepare the low surface tension polypropylene material of this embodiment is by weight:

Polypropylene: 100 parts

Fluorinated graft monomer dodecafluoroheptyl acrylate: 8 parts

Grafted comonomer styrene: 3 parts

Initiator dicumyl peroxide: 1.0 parts

Antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (1010): 0.2 parts

Dilauryl Thiodipropionate (DLTP): 0.4 parts

Each component of the above ratio is prepared according to the preparation method of Example 1 to obtain a pellet product. After drying, it is injected or pressed into a sample to measure its performance, and its water resistance and its water resistance are characterized by the method of contact angle to water. Surface tension, Table 2 is the comparison between the material (grafted PP) and pure polypropylene products (pure PP).

Table 2

sample Contact angle to water θ(°) Increased contact angle (%) Tensile strength (Mpa)   Flexural modulus (Mpa) Pure PP 78.6 -- 33.46 1056.3 Graft PP 93.5 18.96 31.18 1189.5

Example 3:

The ratio of each component to prepare the low surface tension polypropylene material of this embodiment is by weight:

Polypropylene: 100 parts

Fluorinated graft monomer dodecafluoroheptyl acrylate: 11 parts

Grafted comonomer styrene: 3 parts

Initiator benzoyl peroxide: 0.8 parts

Antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (1010): 0.5 parts

Antioxidant tris(2,4-di-tert-butylphenyl)phosphite (168): 0.3 parts

Each component of the above ratio is prepared according to the preparation method of Example 1 to obtain a pellet product. After drying, it is injected or pressed into a sample to measure its performance, and its water resistance and its water resistance are characterized by the method of contact angle to water. Surface tension, Table 3 is a comparison of the properties of the obtained material (grafted PP) and pure polypropylene products (pure PP).

table 3

sample Contact angle to water θ(°) Increased contact angle (%) Tensile strength (Mpa) Bending modulus (Mpa) Pure PP 78.6 -- 33.46 1056.3 grafted PP 96 22.14 29.95 986.8

Example 4:

The ratio of each component to prepare the low surface tension polypropylene material of this embodiment is by weight:

Polypropylene: 100 parts

Fluorinated graft monomer nonadecanyl acrylate: 14 parts

Grafted comonomer styrene: 4.5 parts

Initiator benzoyl peroxide: 0.6 parts

Antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (1010): 0.6 parts

Dilauryl Thiodipropionate (DLTP): 0.4 parts

Each component of the above ratio is prepared according to the preparation method of Example 1 to obtain a pellet product. After drying, it is injected or pressed into a sample to measure its performance, and its water resistance and its water resistance are characterized by the method of contact angle to water. Surface tension, Table 4 is a comparison of the properties of the obtained material (grafted PP) and pure polypropylene products (pure PP).

Table 4

sample Contact angle to water θ(°) Increased contact angle (%)   Tensile strength (Mpa) Bending modulus (Mpa) Pure PP 78.6 -- 33.46 1056.3 Graft PP 102 29.77 29.15 873.14

Example 5:

The ratio of each component to prepare the low surface tension polypropylene material of this embodiment is by weight:

Polypropylene: 100 parts

Fluorinated graft monomer dodecafluoroheptyl acrylate: 14 parts

Grafted comonomer styrene: 4.5 parts

Initiator dicumyl peroxide: 0.8 parts

Reinforced fiberglass (length 4mm): 12 parts

Antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (1010): 0.4 parts

Antioxidant tris(2,4-di-tert-butylphenyl)phosphite (168): 0.4 parts

Each component of the above ratio is prepared according to the preparation method of Example 1 to obtain a pellet product. After drying, it is injected or pressed into a sample to measure its performance, and its water resistance and its water resistance are characterized by the method of contact angle to water. Surface tension, Table 5 is the comparison of contact angle and mechanical properties between the obtained material (grafted PP) and pure polypropylene product (pure PP).

table 5

sample Contact angle to water θ(°) Water resistance improvement rate (%) Tensile strength (Mpa)   Flexural modulus (Mpa) Pure PP 78.6 --- 33.46 1056.3 Graft PP 99.3 26.3 33.72 1159.3

Claims (6)

1. polypropylene material with low surface tension, it is characterized in that: adopt following component to obtain described material by graft copolymerization, each components contents is by weight: 100 parts of polypropylene, 1～15 part of fluorine-containing grafted monomer, grafting is total to 1～10 part of monomer, 0.1～1.5 part of initiator, 0.2～1.0 part of antioxidant; Described fluorine-containing grafted monomer is the fluorochemicals that contains at least 1 unsaturated double-bond in the molecule; Described grafting monomer altogether is a vinylbenzene; Described initiator is the organic peroxy compound;

Contain in the side chain of described polypropylene material with low surface tension-C _xF _yOr-C _xF _y-the chemical structure group;-C _xF _yIn, its x 〉=1, y≤2x+1;-C _xF _y-in, its x 〉=1, y≤2x.

2. polypropylene material with low surface tension according to claim 1 is characterized in that: described polypropylene material also comprises fortifying fibre, and by weight, the ratio of polypropylene and fortifying fibre is 100: 10～25.

3. polypropylene material with low surface tension according to claim 1 is characterized in that: described organic peroxy compound is dicumyl peroxide or benzoyl peroxide.

4. polypropylene material with low surface tension according to claim 1, it is characterized in that: described oxidation inhibitor is selected from four [β-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic acid] pentaerythritol ester, three (2, the 4-di-tert-butyl-phenyl) phosphorous acid ester or Tyox B.

5. a method for preparing polypropylene material with low surface tension is characterized in that, comprises the following steps:

(1) fluorine-containing grafted monomer, initiator and cografting monomer are mixed, again this mixed system is joined in the exsiccant polypropylene, behind the adding oxidation inhibitor, mix with high-speed mixer; By weight, the ratio of polypropylene, fluorine-containing grafted monomer, grafting common monomer, initiator and oxidation inhibitor is 100: 1～15: 1～10: 0.1～1.5: 0.2～1.0; Described fluorine-containing grafted monomer is the fluorochemicals that contains at least 1 unsaturated double-bond in the molecule; Described grafting monomer altogether is a vinylbenzene; Described initiator is the organic peroxy compound;

(2) above-mentioned mixed material is extruded processing through twin screw extruder, moulding or be a granulated into low surface tension polypropylene nascent state pellet, or, obtain polypropylene material with low surface tension with the processing of pellet reshaping.

6. a kind of method for preparing polypropylene material with low surface tension according to claim 5, it is characterized in that: described twin screw extruder is extruded processing, adopts the multistage heating means, and preceding 2～3 sections temperature are 170～180 ℃, and other each section is 185～200 ℃; The total residence time of material in twin screw extruder is 1～10 minute.

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