Plastic profile products are mostly used: window frames, stair handrails, wiring troughs, wall foot boards, special-shaped pipes, etc. The raw materials are mainly hard PVC, and a few are semi-hard PVC, soft PVC, polyurethane low foaming and other materials.
Market prospects
Due to the huge market demand and broad development prospects, plastic profile products have developed rapidly in China in recent years. Due to the fierce market competition, all plastic machinery manufacturers have considered a problem, how to improve plastics while ensuring product quality. Profile product productivity and qualification rate, exert the maximum capacity of the equipment, thereby reducing the production cost of the product.
Competition in the plastic profile industry is intensifying, and mergers and acquisitions and integration and capital operations among large plastic profile companies are becoming more and more frequent. Excellent domestic plastic profile manufacturers are paying more and more attention to the research on the industry market, especially the changes in the development environment of the enterprise and the trend of customer demand. In-depth research. Because of this, a large number of excellent domestic plastic profile brands have risen rapidly and have gradually become leaders in the plastic profile industry!
Plastic profiles are mostly used: window frames, stair handrails, wiring troughs, wall foot panels, special-shaped pipes, furniture, building materials and other accessories. The raw materials are mainly hard PVC, and a few are semi-hard PVC, soft PVC, polyurethane low foaming and other materials.
For hard PVC plastic profiles, there are disadvantages of poor impact resistance. They are often modified by adding ACR, CPE, EVA, MBS, etc. to improve the impact resistance strength. CPE (chlorinated polyethylene), EVA (ethylene-vinyl acetate copolymer), ACR (acrylic fat), MBS ( methyl methacrylate -butadiene-styrene grafted interpolymer) is generally added to 6%~10 %. MBS is mainly used in transparent plastic profile products. EVA is best not to be shared with lead stabilizers. When used, the molding processability is poor and it is easy to have powder spots. CPE is best not to be shared with zinc stabilizers, and the low temperature of CPE is not Too good.
When producing plastic profile products, process conditions control such as temperature, screw speed, traction speed, etc.
Introduction to additives
Plastic profiles are listed as one of the key building materials developed in my country for their excellent thermal insulation and insulation properties. In the production process of plastic profiles, what issues need to be paid attention to to ensure the quality and process of the profile. Let’s learn about what plastic profile additives are there?
Impact modifier
If there is no impact modifier added in the production of plastic profiles, the plastic profile will be very brittle and hard, and it will easily break if it is slightly impacted. The commonly used impact agent modifiers in the production of plastic profiles are mainly composed of the following three categories: chlorinated polyethylene, polyacrylate, and ethylene-vinyl acetate copolymer.
Thermal stabilizer
Plastic profiles are thermally sensitive plastics, so thermal stabilizers are indispensable in the production and processing of plastic profiles. The metal salts in the heat stabilizer can absorb the HCL decomposed by PVC, so they can delay the decomposition speed of plastics and extend the decomposition time. The most commonly used composite lead salts in the production of plastic profiles are the most commonly used, which have high thermal stability efficiency and low price.
Lubricant
The main function of lubricant is to reduce the mutual friction between the polymer and the processing equipment and between the molecules inside the polymer, prevent the resin degradation caused by excessive friction heat, and improve the efficiency of the heat stabilizer.
Processing aids
Processing additives are mainly a type of improved additives developed to improve plastic molding processing properties. The processing temperature of plastic profiles is relatively close to the decomposition temperature, has poor fluidity, and is easy to stick to the equipment to coke. Therefore, a certain amount of processing aids is required to overcome the defects of the plastic profile itself in the production of plastic profiles.
Photostabilizer
Light stabilizers can inhibit the photooxidation and degradation reaction of polymers by shielding and absorbing ultraviolet rays, quenching excitation energy and capturing free radicals, thereby imparting good light stabilization effects to the products and extending their service life.
Filler
A filler is a solid additive that is different in composition and structure from plastics, also known as a filler. It has obvious effect and economic value in improving the physical and mechanical properties of plastics and reducing the cost of plastics. Adding filler to the plastic profile production formula can reduce the change rate of the size of the plastic profile after heating, increase impact strength, increase rigidity, and reduce production costs.
Reasons for unqualified products
In the production process of plastic profiles, due to improper formulation or unreasonable plastic processing technology, the plastic profiles become brittle. The main characteristics are: collapse and cold burst during cutting. Below, Qingdao Plastic Machinery provides you with the reasons for the poor physical and mechanical properties of plastic profiles.
Reason for brittle plastic profiles: Unreasonable formula and process during production of plastic profiles
Too much filler
As the prices of plastic profiles are lowered and the prices of raw materials are rising, many manufacturers reduce the cost while also reducing the quality of plastic profile products. Due to the formula components, the most direct and effective method is to increase fillers, which are commonly used in the production of PVC-U plastic profiles. The filler is calcium carbonate. With the development of technology, most ultra-fine light activated calcium carbonate, or even nano-scale calcium carbonate, not only plays a role in increasing rigidity and filling, but also has the effect of modification, but its filling amount is not unlimited. The proportion of the degree should be controlled. Nowadays, some manufacturers add calcium carbonate to 20-50 parts by mass to reduce costs, which greatly reduces the physical and mechanical properties of the profile and causes the plastic profile to become brittle.
Add type and quantity
Impact modifier is a polymer that can increase the total energy of polyvinyl chloride cracking under stress. The main types of impact modifiers for rigid polyvinyl chloride are CPE, ACR, MBS, ABS, EVA, etc. The molecular structure of CPE, EVA, and ACR modifiers do not contain double bonds, have good weather resistance, and are suitable for making. Outdoor building materials, which are blended with PVC, can effectively improve the impact resistance, processability, weather resistance of rigid polyvinyl chloride and improve the welding corner strength within a certain range. Experimental demonstration shows that the impact resistance of ACR is about 30% higher than that of CPE. Therefore, PVC/ACR blending system should be used as much as possible in the formula, and when modified with CPE and the amount used is less than 8 parts by mass, the plastic profile will often become brittle.
Too much stabilizer
The amount of stabilizer varies depending on the type of plastic profile, but in general, excessive amounts will delay the plasticization time of the material, which will make the material not plasticized when exporting to mold, and the molecules in its formula system are not completely dissolved. The intact molecular structure is caused by insolidity. If the dosage is used too little, it will cause the degradation or decomposition of relatively low molecules in the formula system (also known as overplasticization), which will damage the stability of the molecular structure of each component. Therefore, the amount of stabilizer will also affect the impact strength of the plastic profile. Too much or too little will cause the strength of the profile to decrease and cause the plastic profile to become brittle.
Too much use
The external lubricant has low compatibility with the resin, which can promote sliding between resin particles, thereby reducing frictional heat and delaying the melting process. This effect of lubricant is the greatest in the early stages of the processing process. External lubricants are divided into pre-lubricating and post-lubricating. Materials with excessive lubricating performance have poor appearance under various conditions. If the amount of lubricant is inappropriate, it may cause flow marks, low yield, turbidity, poor impact, and rough surface., adhesion, poor plasticization, etc. Especially when the amount is used too much, it will cause poor compactness and plasticization of the plastic profile, resulting in poor impact performance and causing brittle plastic profiles.
Use and Maintenance
The plastic profile extrusion mold is the core part of extrusion production. The technical status of the plastic profile extrusion mold is directly related to the stability of extrusion production, the quality of the extrusion products, the extrusion production efficiency and the service life of the mold itself. Therefore, the correct use and maintenance of plastic profile extrusion molds is very important.
1. Unboxing inspection after the plastic profile extrusion mold arrives
Unboxing inspection, the packaging is intact: after unboxing, take out the packing list, instruction manual and other technical documents, and form a complete mold, accessories, special tools, etc. according to the content of the packing list.
2. Half of the technical requirements and status of plastic profile extrusion mold
Especially when the extrusion material of plastic profile extrusion mold is modified polyvinyl chloride, its molded parts generally use corrosion-resistant materials such as stainless steel, and are tempered to above HRC24 to ensure a certain service life.
The working surfaces of the mouth molds, shaping molds and their parts should be smooth and should not have defects such as bumps, scratches, burrs, attachments and rust.
The die head runner system should be smooth in the direction of melt flow, so as to avoid sudden changes in cross-section and material stagnation areas.
Each template should have reliable positioning, and the loading and unloading repeatability error in the corresponding positions of each template between the mold should not be greater than 0.03mm; the joint surfaces and splicing of the die head of the plastic profile extrusion mold should be closely integrated, and the local gap shall not be greater than 0.02mm.
The cooling system and vacuum system of the fixed mold should be unobstructed and not leaked. Generally, the water and gas systems should not collude with each other. The water pipe joints and vacuum pipe joints of plastic profile extrusion molding molds should have obvious signs and should not affect the connection of the pipeline.
The molding die of plastic profile extrusion mold should be flexible in the closing, and the molding dies and the molds in the water tank should be guaranteed to have a certain degree of coaxiality.
Current development status
In recent years, China’s plastic profile industry has accelerated the pace of research and development and promotion and application, and its production and sales volume has firmly ranked first in the world. Among them, plastic pipes, plastic sheets and other products have entered a period of stable and mature growth, and are the most mature varieties of plastic profiles.
The main products of the plastic profile industry include: plastic doors and windows, plastic pipes, plastic sheets, plastic waterproof rolls and plastic profiles. Among them, plastic profiles, plastic pipes, plastic sheets and other products have formed a huge chemical building materials industry chain in China. Plastic profiles alone have an annual production capacity of 2.8 million tons, and China has entered the ranks of a major plastic country.
Nowadays, plastic building materials and other products have begun to develop from interior decoration parts to structural parts and functional parts. Sales of plastic floors and wall interior decoration parts have maintained steady growth, and polymer building formwork, waterproof materials, exterior wall support parts, exterior wall insulation boards, plastic reinforced bricks, etc. have been increasingly used, and their growth rate has exceeded that of Plastic pipes.
It is expected that in the next 5-15 years, under the guidance of various national building energy-saving policies, the plastic building materials market is expected to develop more rapidly. By 2015, the average market share of various building plastic pipes and plastic doors and windows in China will reach 50% and 30% respectively. In terms of demand, the total demand for various building plastic pipes and plastic doors and windows, plus polymer waterproofing materials, decorative and decoration materials, thermal insulation materials and other building plastic products is expected to reach 10 million tons.
The rapid development of the industry and the continuous expansion of production capacity have intensified competition among plastic profile companies. In addition, the domestic market is gradually becoming saturated, and many profile companies have begun to look for development opportunities in the international market. In the future, the competition among plastic profile companies will depend more on the mastery of core technologies between companies. In addition to continuously improving the comprehensive level of products, companies must also adapt to industry standards in different countries and obtain relevant international certifications or access permits.
