The preparation method of surface modification of quartz sand by silane coupling agent is introduced in this paper. In the field of
quartz sand processing and
sand washing plant, quartz sand modification is an important aspect of quartz sand deep processing.
Slab quartz sand
The silica content in
slab sand for artificial quartz stone slab is high (SiO2 (>99%), whiteness is high (>88%), particle size is – 20 to +40 mesh, - 40 to +60 mesh, - 60 to +120 mesh, - 120 to +200 mesh. After special sand processing, the shape and structure are angular, chemical properties are stable, acid and alkali resistance and ultraviolet resistance. The chemical composition of quartz sand for artificial quartz stone slab is: SiO2:> 99%; A12O3:= 0.2%; Fe2O3 < 0.1%; PH: 6.5-7.0.
Quartz sand plays an important role in artificial quartz slab industry. The addition of quartz sand can not only reduce the production cost of its products, but also improve the functionality of artificial quartz stone products and give them some special physical and chemical properties. However, due to the different interfacial properties and poor compatibility between quartz sand and organic macromolecule resin, it is difficult to disperse uniformly in quartz sand, and some physical and chemical properties of the products will be reduced. Therefore, in order to increase the amount of quartz sand added in its products and achieve its due functional effect, it is necessary to modify the surface of quartz sand to improve its physical and chemical properties, enhance its compatibility with resin, improve the dispersibility of products in the process of production and ingredient, and enhance its combination with organic molecular resin. Functional and mechanical properties.
Modified quartz sand used in artificial quartz slab is mainly made of quartz as raw material, silane coupling agent as surface modifier, using special surface modification equipment of quartz sand to prepare high quality surface modified quartz sand. The molecular end of surface modifier is polar group, which can be connected with the surface of quartz sand by physical adsorption or chemical reaction. The lipophilic group at the other end forms physical entanglement or chemical reaction with the matrix. As a result, the surface modifier builds a "molecular bridge" between quartz sand and organic macromolecule resin, which makes the polarity different and phase. Two substances with poor solubility are coupled, which strengthens the interaction between matrix and
quartz sand, and improves the physical and chemical properties of products.
γ-silane coupling agent and its dosage
Silane coupling agent is one of the most widely used and rapidly developed surface modifiers for non-metallic materials. It has many varieties and complex types. Typical silane coupling agents are organic compounds containing silicon atoms, whose molecular structure is centered on silicon atoms, and the two groups are connected with the central atoms respectively. There are many kinds of silane coupling agents and they are widely used. In addition to the modification effect of silane coupling agent itself, the selection of silane coupling agent should also consider the comprehensive factors such as resin polymer system, industrial application and economic cost of surface modification products, and easy operation.
Silane coupling agent was used to modify the surface of quartz sand. The surface of quartz sand was modified by winding and crosslinking through the reaction of silane coupling agent group and
quartz sand. The surface of quartz sand was closely bonded. The compatibility between quartz sand and organic macromolecule resin materials is enhanced by chemical bonding, physical adsorption, chain connection between silane coupling agents and gradual polarity transition treatment layer.
Through comparison and research, Sinonine uses gamma-silane coupling agent and determines the amount of hydrolyzed Sinonine. The percentage of silane coupling agent in weight of quartz sand is -20-+40 mesh quartz sand is 0.2%-0.5%, -40-+60 mesh quartz sand is 0.3-0.6%, -60-+120 mesh quartz is 0.4-0.7% after hydrolysis, and - 120-+200 mesh quartz is 0.7% after hydrolysis. 6-0.9%
Surface Modification of Quartz Sand with Silane Coupling Agent
The process of surface modification of quartz sand for slab with silane coupling agent is as follows.
1.The diluent solution for preparing silane coupling agent consists of ethanol (95%) and water. The volume ratio of the diluent is as follows:
Ethanol (95%): Water = 9:1-6:1
Acetic acid was used to regulate the pH value of the diluent to 3-4.
2.Take a certain proportion of silane coupling agent, add a certain proportion of diluent solution prepared by adding lambda, fully stirring, so that the hydrolysis is complete, to be used.
3.When the
slab quartz sand is added to the special high-speed heating mixer for dynamic heating, dispersing and heating to l00 degree, the hydrolyzed silane coupling agent added by atomization method should keep a certain reaction time during the reaction between the silane coupling agent and the
quartz sand, because the effect of surface modification is different in different reaction time. This heating reaction is a process of dehydration, condensation and curing, so that the silane coupling agent and
quartz sand form a stable and firm covalent bond.
The production process has the characteristics of good dispersion of modifier and uniform coating of powder surface. The activation rate of modified quartz sand products (-20-40 mesh) is (>96%), (-40-60 mesh) is (>96.5%) and (-120-200 mesh) is (>97.0%).
