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PVC wood plastic formulations of raw materials technology
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Createtime: 2017/02/22 |
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PVC wood plastic material is mainly PVC resin powder, PVC recycled material, wood flour, stone powder and some modifiers. PVC wood products can be divided into vacuum forming, cold push and three roller suppression three methods. PVC wood plastic products light weight, good toughness, moderate hardness, wide range of uses. PVC wood products are mainly used for interior decoration materials, such as doors, flooring, door sets and so on. Wood plastic features do not do too much application, into the title! The
Composition and Performance of PVC Wood Plastic
(Wood
powder, calcium carbonate), lubricants, stabilizers, foaming agents,
foaming agents, toners and other related additives (plasticizers,
toughening agents, coupling Agent) and other components.
Resin
Resin do not do too much introduction, you can Baidu small knowledge,
wood-based domestic main SG-7-based resin, SG-7 resin is good for good
foam.
filling
Filled
with basic fiber wood powder (generally with 80-120 head of wood powder
and more poplar powder), calcium carbonate according to different
quality requirements, the production process is different, you can use
2.4 body light calcium carbonate or 400-1250 Head of calcium, part of the wood plastic floor using coarse powder and heavy calcium processing.
Additives detail PVC wood plastic
As
the wood powder has a strong water absorption, and the polarity is very
strong, and most of the thermoplastic non-polar, with hydrophobic, so
the compatibility between the poor, the interface of the adhesion is
very small, It
is often necessary to use the appropriate additives to modify the
surface of the polymer and wood flour to enhance the interface affinity
between the wood powder and the resin. Moreover,
the high filling amount of wood powder in the molten thermoplastic
dispersion effect is poor, often in the form of a certain state of
aggregation, making the melt flow is poor, extrusion molding difficult,
need to join the surface treatment agent to improve the mobility to
facilitate Extrusion. At
the same time, the plastic matrix also need to add a variety of
additives to improve its processing performance and the use of finished
products, improve the wood powder and the adhesion between the polymer
and composite mechanical properties. Commonly used additives include the following categories:
stabilizer
For
the production of PVC stabilizer with a combination of lead salt
stabilizer, organic tin, calcium and zinc stabilizer and other domestic
general for the wood plastic stabilizer is a composite lead salt
stabilizer, which has the advantage of cheap, good thermal stability The The disadvantage is that toxic is not environmentally friendly. But the proportion of composite lead salt stabilizer lubricant is
about 50%, if it is added to the lubricant is low melting point of the
lubricant will affect the performance of the product.
Plasticizer
For
some glass transition temperature and melt flow viscosity higher resin
such as hardness PVC, and wood powder compound processing difficulties,
often need to add plasticizer to improve its processing performance. The
molecular structure of the plasticizer contains both polar and
non-polar genes. Under high temperature shear, it can enter the polymer
molecular chain and form a uniform and stable system through the polar
genes. The insertion of polar molecules weakens the mutual attraction of polymer molecules, making processing easy. In the wood-plastic composite materials often have to join the plasticizer dibutyl phthalate (DOS) and so on. Such
as PVC wood powder composite material, adding plasticizer DOP can
reduce the processing temperature, reduce the decomposition and smoke of
wood flour, with the increase in the amount of DOP content, the tensile
strength of the composite decreased and elongation at break The
For PVC ecological wood plasticizer commonly used DOP and epoxy soybean oil. DOP
can reduce the force between the resin molecules to improve mobility, a
certain degree of lubrication conducive to production and processing. But it can reduce the product of Vicat, one kilogram of DOP can reduce Vicat 3 degrees. Soybean oil its plasticizing effect is not as good as DOP and has a
certain thermal stability, will also reduce the product of Vicat.
Lubricant
Wood-plastic
composites often require the addition of lubricants to improve the melt
flow and the surface quality of the extruded article, which is divided
into internal lubricants and external lubricants. The
choice of internal lubricant is related to the matrix resin used. It
must have good compatibility with the resin at high temperature and
produce some plasticizing effect, reduce the cohesive energy between the
molecules within the resin, weaken the intermolecular mutual Friction to achieve the purpose of reducing the melt viscosity of the resin and improving the melt flowability.
External
lubricants in the plastic molding process in fact the role of resin and
filler between the role of lubrication, its main function is to promote
the sliding resin particles. Usually a lubricant often has both internal and external lubrication performance. Lubricant
on the mold, barrel, screw life, the extruder's production capacity,
the production process of energy consumption, surface finish and profile
of the low-temperature impact properties have a certain impact. Commonly used lubricants are: zinc dichenate, ethylene bis-fatty acid
amide, polyester wax, stearic acid, lead stearate, polyethylene wax,
paraffin wax, polyethylene wax and so on.
Generally
with stearic acid, paraffin, PE wax, calcium stearate with the
proportion required to form a wood-plastic lubricant system. Stearic
acid, paraffin cheap cheap lubrication performance, the drawback is
that the melting point is too low (50 degrees), low melting point of the
lubricant to give lubrication at the same time also play the role of
plasticizer, which affect the product rigidity, Of
the Vicat and heat distortion temperature is low so that the product is
easily deformed with temperature, and easy to precipitate affect the
production. PE
wax if the new PE material to produce and is 100% pure, the melting
point can reach 80 degrees or more is not to reduce the product of
Vicat. If PE wax manufacturers in order to reduce the cost of recycling PE
material and add a certain percentage of stearic acid and paraffin wax
is not true PE wax will also affect the use of the product performance.
Colorant
In
the use of wood-plastic composite materials, wood powder in the solvent
material easy to migrate to the product surface, the product
decolorization, and eventually become gray, different products in a
certain use of the environment, but also produce dark spots or rust. Therefore, the colorants in the wood-plastic composite materials also has a more extensive application. It can make the product has a uniform and stable color, and decolorization slow.
Applicable to the ecological wood of the toner is generally yellow, red, black, titanium dioxide and so on. Yellow and red two kinds of toner are inorganic and organic two. The
advantage of inorganic powder is excellent in weatherability and
resistance to migration, etc. It is superior to organic toner. It is a
large amount of additive, which is not suitable for bright colors, but
it is cheap. Organic toner instead. Ecological wood is generally used with organic and inorganic toner. Titanium dioxide with R titanium and anatase two. R titanium hiding power and weatherability is better than anatase, so
the ecological wood is generally used titanium titanium dioxide
titanium.
Blowing agent
Wood-plastic
composite material has many advantages, but because of the combination
of resin and wood powder, so that the ductility and impact resistance
decreased, the material brittle, density than traditional wood products
nearly 2 times, limiting its wide use. The
foamed wood-plastic composites can passivate the crack tip and
effectively prevent the expansion of the crack due to the existence of a
good cell structure, which significantly improves the impact resistance
and ductility of the material and greatly reduces the density of the
product The There
are two kinds of foaming agents. There are two kinds of foaming agents
(such as sodium bicarbonate NaHCO3) and exothermic foaming agent
(azodicarbonamide AC). The thermal decomposition behavior is different. The viscoelasticity and foaming morphology of the melt have different
effects, and the appropriate blowing agent is selected according to the
requirements of the product.
Generally
use AC foaming agent and baking soda with the use, but also useful with
AC blowing agent and sodium bicarbonate to match. AC
blowing agent is the advantage of large amount of gas, the amount of
small, the disadvantage is not fully decomposed in a small part of the
product, so the use of the process will be affected to the product
apparent, the expansion of the foam to the surface of the product The weather resistance of the product accelerates the aging of the product.
UV stabilizer and others
The
application of UV stabilizer also with the people on the quality of
wood-plastic composite materials and improve the requirements of the
rapid development. It can make the polymer in the composite material does not degrade or mechanical properties decline. Commonly used hindered amine light stabilizers and UV absorbers. In
addition, in order to make the composite material can maintain a good
appearance and perfect performance, often need to add anti-bacterial
agent, the choice of antimicrobial agents to consider the type of wood
flour, the amount of composite materials used in the environment of
fungi, Water and other factors. Such as zinc borate can be anti-corrosion but not anti-algae.
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