CN103819949B - Surface modification method for inorganic powder - Google Patents

Abstract

The invention discloses a method for surface modification of inorganic powder. 100 parts of inorganic powder, 1-6 parts of ethylene-vinyl alcohol copolymer of 20-100 mesh and 5-30 parts of glycerin are activated at 165-200 ° C. 10-30? min to obtain surface-modified inorganic powders. The invention effectively improves the compatibility and dispersion of inorganic powders in the polymer matrix. and social benefits.

Description

A kind of surface modification method of inorganic powder

technical field

The invention belongs to the technical field of surface modification of inorganic powder, and relates to a preparation method of inorganic powder surface-modified by ethylene-vinyl alcohol copolymer. Specifically, it is a method of modifying inorganic powder with ethylene-vinyl alcohol copolymer to change the surface from hydrophilic to lipophilic.

Background technique

Inorganic powders such as calcium carbonate, calcium oxide, calcium hydroxide, aluminum hydroxide, aluminum oxide, magnesium hydroxide, magnesium carbonate, magnesium oxide, brucite, dolomite, calcite, basic magnesium carbonate, basic sodium carbonate Aluminum, wollastonite, kaolin, clay, mica, talc, silica, titanium dioxide, glass beads, marble, chalk, limestone, barium sulfate, nepheline, potassium feldspar, albite, graphite, carbon black, Minerals such as zinc oxide and zinc carbonate are widely used in polymer materials industries such as plastics, rubber, synthetic fibers, coatings, and adhesives. They can reduce the cost of polymer materials and products, endow polymer materials with functionality, and develop polymer materials. The role of new uses for materials. Therefore, the application of inorganic powders in polymer materials has been paid more and more attention by researchers and manufacturers of polymer materials. Especially after 2003, with the sharp rise in the price of petroleum, the raw material for the production of synthetic resins, and the increasing concern about environmental pollution caused by polymer materials, the Inorganic powders, which can reduce the amount of polymer materials used, have been paid more and more attention by people.

The surface properties of inorganic powders are generally hydrophilic, which is quite different from the matrix of organic polymer materials. When organic polymer materials are added to unmodified inorganic powders, the mechanical properties and processing properties of the materials are often reduced. Therefore, it is necessary to modify the surface of the inorganic powder to change the original hydrophilic surface property to the modified lipophilicity, so as to improve the mechanical and processing properties of the filling material.

Common surface modification methods for inorganic powders include:

1. Surface treatment of inorganic powders with surfactants and coupling agents. Small molecule treatment agents have problems such as precipitation and migration during use.

2. Use maleic anhydride, acrylic acid, acrylate, glycidyl methacrylate grafted polymers to prepare macromolecular modifiers for modified polymer/inorganic powder filling systems. However, the grafting rate of this type of graft polymer is low, generally only 0.4% to 2%, so to achieve the purpose of treatment, a large amount of graft polymer such as maleic anhydride is required.

3. With the help of special equipment that can generate radiation, plasma, ultrasonic waves, etc., or firstly with the help of compounds that can introduce initiator groups on the surface of inorganic fillers, and then initiate polymerization of monomers on the surface of inorganic powders to form polymer grafts "Shell-core" structure on the surface of inorganic powder. The specific published results are: Wang Yong published "Inorganic Fillers Simultaneously Toughen and Enhance the Interfacial Interaction of HDPE System" in "Chemical Journal of Chinese Universities" (1994, 15 (8): 1253-1255). In this study, CaCO ₃ was irradiated, and the free radicals generated on the surface of CaCO ₃ initiated the polymerization of acrylamide, and grafted polyacrylamide on the surface of CaCO ₃ to achieve the purpose of modification. There are also similar reports: Wang Huaifa and others published "Radiation Modification of Inorganic Particle Materials" in "China Powder Technology" (2000, (6): 235-238); Gao Xiaoling et al. published "Insulation Materials" (2003, ( 3): 13-15) published "Study on the Dispersion Morphology of Irradiation Grafted Modified Nano-CaCO3 in POM";"Graft polymerization modification of nano _-SiO2 surface and its mechanical properties of polypropylene-based composite materials"; Jiang Bo published "Radiation Grafting of Magnesium Oxide Surface" in "Applied Chemistry" (1997, 14(1): 95-97) Research on the Mechanism of Polymerization"; Wen Guian and Zhang Wengong published "Low Temperature Plasma Surface Modification of Inorganic Powder" in "Powder Technology" (1997, 3(2): 27-32); Fan Shimin and others published "China Powder Technology"Technology" (2002, 31(2): 5-8) published "Plasma Surface Modification of Calcium Carbonate"; Lu Shouci and others published in "China Powder Technology" (1999, 5(1): 33-37) published "Theory and Practice of Mechanochemical Modification of Mineral Pigments and Fillers"; Yang Huaming and others published "Research Progress in Ultrafine Pulverization Mechanochemistry" in "China Powder Technology" (2002, 8(2): 31-36) ; Xu Xi published "Polymer Material Science Research Trends and Development Prospects" in "New Materials Industry" (2003, (3): 12-17); Qian Jiasheng published "Anhui Chemical Industry" (2000, (6): 13 -14) Published "Research on Grafting Modification of Nano-SiO ₂ Surface Polymer"; Wu Wei published "Polymerization The surface condition and formation mechanism of superfine silica modified by grafting.

4. Fix the polymer on the surface of the inorganic filler in a certain way. The specific published results include: patented a method for preparing inorganic powder with a "core-shell" structure through surface modification (ZL 200710144038.6). Sheng Yu published "Surface Properties of Aluminum Hydroxide Treated by Macromolecular Bonding and Its Interface Properties with Commonly Used Polymers" in "China Plastics" (1999, 13(1): 80-84). Zhu Deqin published "Preparation and Properties of Al(OH) ₃ /PVC Composite Materials Modified by Surface In-Situ Chemical Combination" in "China Plastics" (2006, 20(9): 23-27). Tang Longxiang published "Research on in-situ synthesis of TPU toughened PP on the surface of talcum powder" in "China Plastics" (2000, 14(11): 71-75).

Methods 3 and 4 have the disadvantages of complex modification process and difficult industrial promotion. Therefore, it is more common in academic research and rare in practical application.

Due to the wide application of inorganic powder in the polymer material industry, the development of simple, hygienic, safe, durable and reliable inorganic powder surface modification technology has always been the pursuit of industry and science and technology.

Ethylene-vinyl alcohol copolymer (EVOH) is a crystalline polymer that combines the good processability of polyethylene and the extremely high gas barrier properties of polyvinyl alcohol. It is combined with polyvinylidene chloride (PVDC) and polyamide (PA ) and known as the three major barrier resins, its gas barrier properties are dozens of times higher than PVDC, a commonly used high barrier material, 100 times higher than PA, and 10,000 times higher than PE and PP. Therefore, currently ethylene-vinyl alcohol copolymers are mainly used in the field of packaging and the preparation of automobile fuel tanks. After researching and analyzing the structure of ethylene-vinyl alcohol copolymer (EVOH), we found that the structural unit of vinyl alcohol in EVOH up to 30-70% molar fraction can generate hydrogen bonds with the chemically bound water on the surface of inorganic powder, and also It can generate electrostatic interaction with the polar group of inorganic powder, which naturally makes it have good compatibility with inorganic powder; while the ethylene structural unit with a molar content of up to 30-70% in EVOH is compatible with most of the matrix polymer It has good affinity and can produce macromolecular chain entanglement between the two. Therefore, ethylene-vinyl alcohol copolymer can be used as an inorganic powder surface agent to improve the compatibility between the inorganic powder and the polymer matrix, and endow the polymer-filled composite system with good mechanical properties.

Searching a large number of patent documents and published related research papers, this modification method using EVOH for inorganic powders has no relevant literature and patent reports at present. It was only found that Zhang Yujun and others published "Preparation and Structural Characterization of EVOH/Montmorillonite Intercalation Composite Materials" in "Journal of Natural Sciences of Heilongjiang University" (2006, 23 (1 ): 124-127). Pyrrolidone-modified montmorillonite (MMT) is the inorganic phase, and ethylene-vinyl alcohol copolymer is used as the matrix resin. EVOH/montmorillonite composites are prepared by melt intercalation, which reduces the hygroscopicity of the composites and improves the cost performance. Tang Zhongzhu and others published "Preparation and Properties of Thermoplastic Starch/Ethylene-Vinyl Alcohol Copolymer Composite Materials" in "Journal of Functional Polymers" (2005, 18 (3): 368-372). The study used ethylene-vinyl alcohol The copolymer and thermoplastic starch are blended to prepare starch-based biodegradable materials. The degradation performance of the composite system is controlled by controlling the ratio of ethylene-vinyl alcohol copolymer and thermoplastic starch in the composite system. The amount of ethylene-vinyl alcohol copolymer added is 10 Between -40%. Similar studies include "Preparation and Performance Research of TPS/EVOH Blends" published by Zhang Meijie et al. in "Plastic Industry" (2003, 31(1): 27-29). The above-mentioned papers only use ethylene-vinyl alcohol copolymer as a blending raw material with thermoplastic starch to improve the degradation performance of starch/ethylene-vinyl alcohol copolymer composite materials, and do not clearly point out that ethylene-vinyl alcohol copolymer is used as thermoplastic starch. surface modifiers. At the same time, 1 authorized patent (ZL 201110189511.9) related to ethylene-vinyl alcohol copolymer-based composite materials was retrieved. This patent provides a method for manufacturing ethylene-vinyl alcohol copolymer-based composite materials using calcium sulfate and corn starch and its preparation process. Its purpose is to reduce the cost of ethylene-vinyl alcohol copolymer-based composite materials and endow the composite materials with certain degradability. In this patent, calcium sulfate is surface activated and modified by adding stearic acid to improve the compatibility of calcium sulfate, corn starch and ethylene-vinyl alcohol copolymer, while improving the fluidity of the melt and the surface smoothness of the composite material. It can be seen that the patentee did not recognize the compatibility effect of ethylene-vinyl alcohol copolymer on calcium sulfate and corn starch. The present invention directly uses ethylene-vinyl alcohol copolymer to improve the dispersion and compatibility of inorganic powder in the polymer matrix. This modification principle and modification method are proposed by the applicant for the first time.

Contents of the invention

Aiming at the deficiencies of the existing inorganic powder treatment methods, the present invention provides a method for surface modification of inorganic powder by using ethylene-vinyl alcohol copolymer as a modifier, so as to improve the contact between inorganic powder and organic powder. Compatibility between polymer materials, improve its dispersion.

To achieve the above object, the present invention adopts the following technical solutions:

The raw material formula in parts by weight is: 100 parts of inorganic powder, 1-6 parts of ethylene-vinyl alcohol copolymer, and 5-30 parts of glycerin.

The ethylene molar content of the ethylene-vinyl alcohol copolymer is 30-70%.

The inorganic powder is calcium carbonate, calcium oxide, calcium hydroxide, aluminum hydroxide, aluminum oxide, magnesium hydroxide, magnesium carbonate, magnesium oxide, brucite, dolomite, calcite, basic magnesium carbonate, alkali Sodium aluminum carbonate, wollastonite, kaolin, clay, mica, talc, silicon dioxide, titanium dioxide, glass beads, marble, chalk, limestone, barium sulfate, nepheline, potassium feldspar, albite, graphite, One or more of ultrafine inorganic powder or nano inorganic powder of carbon black, zinc oxide or zinc carbonate.

The surface modification method of the inorganic powder comprises the following steps:

(1) Crush ethylene-vinyl alcohol copolymer into 20-100 mesh powder, dry at 90-92°C for 8 hours, and set aside;

(2) Dry the inorganic powder at 90-120°C for 1-3 hours;

(3) Mix the dried ethylene-vinyl alcohol copolymer powder with glycerin evenly, and activate the dried inorganic powder at 165-200°C for 10-30 minutes to obtain surface-modified inorganic powder .

The beneficial effects of the present invention are: (1) The vinyl alcohol structural unit and the ethylene structural unit in the ethylene-vinyl alcohol copolymer can produce good interfacial bonding with the inorganic powder and the polymer matrix respectively, without additional interfacial compatibilizer. If this technology is popularized and applied on a large scale, it can replace the currently commonly used modification method, thereby reducing the environmental pollution caused by the production of conventional compatibilizers. Because commercial ethylene-vinyl alcohol copolymers are produced by modern large-scale chemical companies with strict environmental protection measures, compared with the production of maleic anhydride graft polymers in general plastic processing plants, the environmental pollution is small and it is convenient for centralized management. (2) There are many kinds of ethylene-vinyl alcohol copolymers, the molar content of vinyl alcohol is 30-70%, and there is a large choice of modifiers. The proportion of ethylene and vinyl alcohol structural units in the molecular structure of ethylene-vinyl alcohol copolymer can be adjusted, which provides a wide range of options for the preparation of a wide variety of polymer-based inorganic powder composites with different filling amounts. (3) It can directly process inorganic powder, with convenient operation, simple process, high production efficiency and low product production cost. (4) The ethylene-vinyl alcohol copolymer itself is non-toxic, and the resulting product has no pollution to the environment. Ethylene-vinyl alcohol copolymer is a macromolecular modifier, and there are no pollution and failure problems such as precipitation and migration during the use of the product.

Detailed ways

Example 1

Formula: 100 parts of inorganic powder, 1 part of ethylene-vinyl alcohol copolymer (the molar content of ethylene is 70%), and 5 parts of glycerin. The inorganic powder is nanometer calcium carbonate.

The surface modification method of inorganic powder comprises the following steps:

(1) Crush ethylene-vinyl alcohol copolymer into 20-mesh powder, dry at 90°C for 8 hours, and set aside;

(2) Dry the inorganic powder at 90°C for 1 hour;

(3) After mixing the dried ethylene-vinyl alcohol copolymer powder and glycerin evenly, the dried inorganic powder was activated at 165°C for 10 min to obtain the surface-modified inorganic powder.

Example 2

Formula: 100 parts of inorganic powder, 6 parts of ethylene-vinyl alcohol copolymer (30% ethylene molar content), 30 parts of glycerin. The inorganic powder is a superfine inorganic powder mixture of marble, potassium feldspar, albite and carbon black (mass ratio is 1:1:1:1).

The surface modification method of inorganic powder comprises the following steps:

(1) Crush ethylene-vinyl alcohol copolymer into 100-mesh powder, dry at 92°C for 8 hours, and set aside;

(2) Dry the inorganic powder at 120°C for 3 h;

(3) After the dried ethylene-vinyl alcohol copolymer powder and glycerin were evenly mixed, the dried inorganic powder was activated at 200°C for 30 min to obtain the surface-modified inorganic powder.

Example 3

Formula: 100 parts of inorganic powder, 3 parts of ethylene-vinyl alcohol copolymer (the molar content of ethylene is 44%), and 15 parts of glycerin.

The inorganic powder is superfine inorganic powder of calcium oxide, calcium hydroxide, kaolin, talcum powder and glass microspheres (mass ratio is 1:1:1:1:1).

The surface modification method of inorganic powder comprises the following steps:

(1) Crush ethylene-vinyl alcohol copolymer into 60-mesh powder, dry at 91°C for 8 hours, and set aside;

(2) Dry the inorganic powder at 105°C for 2 h;

(3) After uniformly mixing the dried ethylene-vinyl alcohol copolymer powder with glycerin, the dried inorganic powder was activated at 175°C for 20 minutes to obtain a surface-modified inorganic powder.

The interfacial tension (mJ/m ² ) between the inorganic powder and polypropylene treated by the method of the present invention is as follows:

Add 40 parts of the modified inorganic powder to 100 parts of polypropylene for the production of composite panels, and use a universal material testing machine to test the mechanical and processing properties of the obtained composite materials as follows:

The above results show that this method can effectively reduce the polarity of the inorganic powder, improve the compatibility with the polymer matrix, and improve the mechanical properties and processing properties of the composite material.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (2)

1. a surface modifying method for inorganic powder, is characterized in that: filling a prescription is made up of the raw material of following parts by weight: inorganic powder 100 parts, ethylene-vinyl alcohol copolymer 1-6 part, glycerine 5-30 part; The ethylene molar content of described ethylene-vinyl alcohol copolymer is 30-70%;

Method of modifying comprises the following steps:

(1) ethylene-vinyl alcohol copolymer is ground into 20-100 order powder, 90-92 DEG C of drying 8 h, for subsequent use;

(2) inorganic powder is in 90-120 DEG C of dry 1-3 h;

(3), after dried ethylene-vinyl alcohol copolymer powder being mixed with glycerine, at 165-200 DEG C, activation treatment 10-30 min is carried out to dried inorganic powder, obtain the inorganic powder of surface modification.

2. the surface modifying method of inorganic powder according to claim 1, it is characterized in that: described inorganic powder is calcium carbonate, calcium oxide, calcium hydroxide, aluminium hydroxide, aluminum oxide, magnesium hydroxide, magnesiumcarbonate, magnesium oxide, brucite, rhombspar, calcite, slag magnesiumcarbonate, Sodium Aluminium Carbonate Basic, wollastonite, clay, mica, talcum powder, silicon-dioxide, titanium dioxide, glass microballon, marble, Wingdale, barium sulfate, nepheline, potassium felspar sand, albite, graphite, carbon black, one or more in the ultrafine inorganic powder of zinc oxide or zinc carbonate or nano inorganic powder.