Must be engaged in disaster prevention and control personnel: analysis and prevention of landslides!
Landslide accident 1: At about 6 o'clock on June 24, 2017, a high mountain collapse occurred in Xinmo Village, Diexi Town, Mao County, Aba Prefecture, Sichuan Province, causing more than 40 farm houses and more than 100 people to be buried. The river channel was blocked for 2 kilometers.
Landslide Accident 3: At 10 o'clock on the evening of June 24, 2017, a large area of ​​landslides and mudslides suddenly occurred in a place called “Water Hole†in Sanhe Village, Persimmon Town, Yanjin County, Zhaotong City. The Difeng Feng Road was buried. A section of nearly 200 meters long caused a two-way interruption of traffic on the road.
Landslide accident three: At 10:40 am on August 28, 2017, a geological disaster of landslide occurred in Zhangjiawan Town, Nayong County, Bijie City, Guizhou Province. Up to now, the accident has caused 2 deaths, 4 people were injured, 25 people lost contact, and the loss of joint personnel is being searched and rescued.
The landslide accident is shocking. People are concerned about the casualties and losses caused by landslides. At the same time, they may pay more attention to why there are many landslides. Is it a natural disaster or a man-made disaster? How to prevent such accidents from happening again?
Xiaotang has compiled some information about landslides. The purpose is to introduce some domestic and foreign research results and practical experience to engineers and technicians engaged in the prevention and control of landslide hazards, so as to draw lessons from future work. At the same time, I hope to attract geoscientists. Pay attention to and discuss and jointly promote the development of our national defense disaster reduction and disaster reduction cause.
1
Introduction to landslide hazards
Section 1 Geological Hazards and Slope Disasters
I. Geological disasters
Geological disasters are geological phenomena in which the geological body deforms, destroys, and moves under the influence of many factors, causing damage to human living environment and loss of life and property. Such as earthquakes caused by deep crustal movement, volcanic eruptions, ground fissures, landslides (collapse) formed by the movement of slope blocks, landslides, patchwork, dumping, collapse and deep creep of rock masses; debris flows and debris formed by surface water Flow, soil erosion; karst collapse caused by groundwater, land subsidence, collapsibility, water inrush, etc.; desertification, salinization, weathering, spalling, expansion, shrinkage, etc. caused by epigenetic geological processes. Here we mainly discuss the various types of slope block motion.
Second, slope disaster
Regarding the deformation and type of movement of the slope, the Americans Varnes proposed the types of collapse, dumping, landslide, lateral expansion, and flow in 1978, as shown in Table 1-1. Early China is also referred to as their "collapse", "collapse landslide", "collapse mud flow", rail and highway departments called: "roadbed disease." Later, as the research progressed, they gradually distinguished them from the deformation mechanism and prevention. According to the depth (scale), motion characteristics and material categories of deformation, we divided it into slope deformation, slope deformation and slope deformation, as shown in Table 1-2.
Figure 1-1 Schematic diagram of the main types of slope block motion
a. landslide (collapse); b. landslide; c. staggered; d. dumping; e. collapse; f. deep creep of rock mass
Table 1-2 Classification of slope deformation
Table 1-3 Examples of major landslide disasters in the world
Section 2 Definitions, elements and terminology of landslides
First, the definition of landslide
Part of the soil or rock mass on the slope slides down along a certain surface or belt.
Second, the elements and terminology of the landslide
Table 1-6 Comprehensive classification of landslides
Section III Types and Characteristics of Landslides
First, the type of landslide
Table 1-5 Classification of single indicators of landslides
Table 1-6 Comprehensive classification of landslides
Second, the characteristics of the landslide
(1) Plane features
Figure 1-5 Plane shape of the landslide
1. 簸箕 shape; 2. tongue shape; 3. elliptical shape; 4. bench shape; 5. inverted pear shape; 6. horn shape; 7. parallelogram; 8. diamond shape; 9. leaf shape; Shape; 11. composite shape
(ii) Profile characteristics
Figure 1-6 Schematic diagram of a typical landslide profile
a. arc shape; b. plane shape; c. line shape; e. soft rock extrusion
Figure 1-7 Composite profile shape
Morphology of the back and front of the landslide
Figure 1-8 The depression in the back of the landslide
a. crack dense zone; b. depression depression; c. trailing edge cracking groove
Figure 1-9 Characteristics of the front of the landslide
a. braided shear outlet; b. drum dome and bulging crack; c. landslide flexion
Figure 1-10 Cross-sectional characteristics of the landslide
The conditions and causes of the fourth section of landslide
First, the topographical geological conditions
(1) Terrain conditions
(2) Geological conditions
Stratum, lithology
Slope structure and slip zone
Geological structure
Hydrogeological conditions
Table 1-7 Summary of China's Easy Landslide Formation
Table 1-8 Types of slope structure and failure mode of landslide
Figure 1-11 Slope structure and failure mode of landslide
a. cohesive soil arc-shaped rotary sliding; b. loess arc-shaped rotary sliding; c. filling soil arc-shaped sliding; d. soil layer-by-layer sliding; e. semi-diagenetic stratum layer-by-layer sliding; f. rock layer bedding-cutting Sliding; g. soft rock extrusion type (staggered type) sliding; h. extrusion type translational sliding; I. accumulation layer smoothing sliding; j. rock layer bedding plane sliding; k. rock layer sliding along the surface; Tidal layer bedding layer-slice layer sliding; m. anti-dip rock layer cutting layer sliding; n. anti-dip rock layer dumping-sliding layer sliding; o. fractured rock layer rotating sliding; p. broken rock layer sliding along structural plane; q. The rock mass slides along the structural plane (like the plane); r. the structural core slides along the structural fracture zone
Second, the role of landslide
The landslide is the result of the combination of various factors in the slope with sliding conditions, but there is always one or two factors controlling the occurrence of landslide for a particular landslide. We call it the main control factor, which should be used in the prevention and control of landslides. Efforts should be made to find out the mechanism and range of changes of the main control factor and its effects, and take major engineering measures to eliminate or control its role to stabilize the landslide. For other factors, take general measures to achieve the purpose of comprehensive management, such as those caused by groundwater The underground interception and drainage project is the main one, and those who are weakened by the supporting force of the slope are mainly responsible for the restoration and strengthening of the supporting works.
The factors affecting the landslide are summarized in Table 1-10, which can be divided into natural factors and human factors, and can also be divided into long-term action factors, short-term action factors and periodic action factors, but in terms of their effects on the formation of landslides, It is a factor that changes the stress state of the slope, increases the stress of the slope and the shear stress (ie, the sliding force) of the slip zone soil, such as the factors of changing the slope shape such as river erosion, excavation slope, and slope loading; The properties of the slip zone soil reduce the factors of anti-sliding resistance, such as surface underwater seepage, groundwater level change, reservoir water level rise and fall, irrigation water and production domestic water infiltration, sloping erosion and dissolution, etc. The third is the factors that increase the sliding force and reduce the anti-sliding force and even cause the structural damage of the slip zone (such as liquefaction), such as earthquake and blasting vibration. In short, its role is not only mechanical, but also physical and chemical, as well as the time course of action, comprehensive dynamic analysis is necessary.
Section 5 Research Contents of Landslide Prevention
First, the basic properties of landslide
Second, landslide prevention and control technology research
2
Landslide mechanism
Plane stress field of the first section of landslide
Figure 2-1 Landslide plane stress field
Section should stand
Figure 2-2 Three-stage sliding mode and its stress field
1. traction section; 2. main sliding section; 3. anti-slip section
The development process and stage of the second section of landslide
First, the creep properties of the soil
Second, the development stage of the landslide
Locally unstable creep compression stage (K>1)
Uniform sliding stage of overall instability (K=1)
Sliding sharply to the destruction stage (K<1)
Post-slip consolidation compaction stage (K>1)
Figure 2-4 Schematic diagram of landslide development
Section 3 Deformation and Failure Law of Slide Soil
I. Factors affecting the shear strength of soil
Stress state and stress path
2. Strain
3. Pore water pressure
4. Loading rate and stress time
5. Soil inhomogeneity and anisotropy
Second, the stress and strain characteristics of the slip zone soil
in conclusion:
The residual strength of the viscous slip zone soil decreases with the increase of clay content in the soil;
The residual strength is independent of the original stress state and the original density of the soil; therefore, the residual strength can be obtained by remolding the soil;
Determination of the difference in residual strength at home and abroad;
The difference in residual strength measured by different instruments and methods;
The effect of coarse particle content on residual strength.
The fourth section of the landslide mechanism
First, the basic theory
1. The change of pore water pressure in the slip zone soil;
2. Change of slope stress state
3. Progressive destruction
4. Residual strength
5. Shock liquefaction
Second, from the analysis of geological conditions
1. Rotational sliding of homogeneous soil
2. Sliding layer
3. Slice sliding
4.Bedding layer - slice sliding
5. Soft rock extrusion sliding
Third, analysis from the main factors
1. Sliding caused by heavy rain
2. Sliding caused by vibration
3. Sliding caused by the rise and fall of the reservoir water level
4. Sliding caused by goaf collapse
5. Irrigation caused by irrigation
6. Sliding caused by excavation
7. Sliding caused by stacking
Section 5 Movement Characteristics of Landslides
First, the type of sliding
Slow creep type
2. Uniform sliding type
3. Intermittent sliding type
4. High speed sliding type
Figure 2-6 Schematic diagram of the sliding type
1- slow creep type; 2- uniform sliding type; 3-intermittent sliding; 4-high speed sliding type
Second, the formation conditions of high-speed landslide
1. Has a considerable height difference (>100m)
2. Has a considerable volume (> 1 million m3)
3. Has a steep slope (>200)
4. Has a large difference in peak residual strength (ratio greater than 2)
5. Has a high landslide cut exit
6. Open terrain in front of the landslide
7. Landslide prevention and control technology
The first section of the landslide prevention principles and planning
First, the principle of prevention and control of landslides
(1) Correct understanding of the principle of landslide
(2) Principles of prevention
(3) The principle of not eradicating the problem
(4) Principles for comprehensive planning of phased governance
(5) Principles of comprehensive governance
(6) The principle of treating early treatment
(7) The principle of technical feasibility and economic rationality
(8) Principles of scientific construction
(9) Principles of dynamic design and dynamic construction
(10) Strengthening the principle of maintenance and repair of anti-skid engineering
Second, the prevention and control planning of landslides
(1) Investigation stage
(2) Design stage
(3) Construction stage
(4) Operation stage
The second section of landslide prevention
1. Avoid existing old and new landslides
Second, to prevent the resurrection of ancient landslides
1. Do not fill the top of the landslide, do not cut the support force in the anti-slide section
2. Do not set up water-permeable buildings on the landslide body
3. Strict management of production and domestic water does not allow it to penetrate into the sliding body
4. Set the necessary anti-slip measures
5. Change the paddy field to dry field when conditions permit
Third, to prevent the deformation of the landslide caused by large sliding
1. Stop construction, strengthen monitoring, prevent disasters
2. Strengthen surface drainage and fill ground cracks
3. Upper weight reduction, leading edge back pressure and drainage of groundwater are often effective measures
Fourth, to prevent landslides in landslides
1. Survey and analysis of high slope geological data;
(1) lithology of the formation, slope structure;
(2) Easy landslide stratum and its distribution location and traits;
(3) Groundwater distribution and exposure location.
2. Analysis of possible types and laws of deformation;
3. Reasonable slope shape, slope rate, slope height and reinforcement measures design;
4. Scientific construction methods and sequences.
Section III Engineering Measures for Landslide Prevention
Table 3-1 Classification of landslide control projects in the United States
Figure 3-1 Classification of Landslide Control Engineering of the Japanese Landslide Society
Table 3-2 Summary of landslide control measures of the International Geotechnical Society
Table 3-3 Summary of China's landslide control measures
Figure 3-2 Schematic diagram of the ground drain
Figure 3-7 Schematic diagram of hole-hole joint drainage
The difference between the anti-slip retaining wall and the general retaining wall is as follows:
(1) It is not subject to general earth pressure, but landslide thrust, which is much larger than the former.
(2) The chest slope is slow, the center of gravity is low, and the chest slope is 1:0.4~1:1.
(3) The foundation depth is large, 0.5~1.0m in the bedrock, 1.5~2.0m or more in the soil layer, and it must be placed in the stable stratum below the slip surface.
(4) Try to use the backfill weight of the wall.
(5) The longitudinal blind ditch behind the wall is required to be high.
(6) In addition to anti-sliding, anti-overturning and section strength check, the wall stability check should also check the possibility of sliding from the bottom of the wall and sliding out from the top of the wall to determine the depth and wall height of the wall.
(7) The position of the thrust point is generally not at the height of one third of the wall, but at the height of one-half or two-fifth of the wall.
(8) The construction must be excavated in sections and pushed from the sides to the middle to avoid the sliding of the landslide caused by the digging.
Section 4 Landslide thrust calculation
The landslide thrust calculation is a necessary work content for the anti-skid engineering design. The technicians who are involved in the landslide prevention work often find it difficult to grasp.
The calculation of landslide thrust mainly involves the following:
The calculation range of the landslide thrust;
The choice of calculation formula;
Selection of the strength index (c, φ) of each segment of the sliding belt;
Additional strength considerations and determinations;
Determination of the safety factor;
Calculate the check of the thrust.
First, the determination of the calculation range of landslide thrust
1. First, divide each sliding block from the geological analysis, and calculate each one separately.
2. Whether the same landslide is graded and the relationship between the front and rear stages. Generally, only one level of the through crack is calculated, and if it is stable in the front, it will naturally be stable.
3. The multi-layer sliding surface should be layered to calculate its landslide thrust.
Second, the choice of calculation formula
There are many calculation methods, which should be selected according to different sliding conditions. Generally, the block thrust transfer coefficient method is used.
The remaining sliding force of the i-th block is: Ei = KWisinαi - Wi cosαitgφi – CiLi+Ei-1Φi
Where: K - safety factor, generally take K = 1.10 ~ 1.25;
Wi — the weight of the i-th block, KN;
Αi — the slip angle of the sliding surface of the i-th block;
Ci — the cohesion of the slip zone of the i-th block, Kpa;
Φi — the internal friction angle of the slip zone of the i-th block;
Li — the length of the slip surface of the i-th block slide, m;
Ei-1—the remaining sliding force of the sliding block of the I-1 block to the sliding block of the i-th block;
Φi - transfer coefficient.
Φi = cos(αi –αi-1 )– sin(αi –αi-1 )tgφi
Third, the selection of the shear strength index (c, φ) of each section of the sliding belt
1. Due to the great difference between geological conditions and soil properties, the values ​​of c and φ of different landslides are quite different. The sampling test results in numerical dispersion due to sampling representativeness and test methods. Therefore, the reference test values ​​are combined with the empirical values ​​at home and abroad, and the inverse sliding section c and φ values ​​are obtained by the inverse algorithm.
2. Test method. It is necessary to make the undisturbed soil, and it is necessary to reshape the peak strength and residual strength of the natural water content (natural, plastic, soft plastic state) under the different water content of the sliding belt.
3. Comparison of empirical data refers to the analogy of the same type of landslide slip zone soil under the same geological conditions. The change of lithology and the change of c and φ values ​​of the traction section and the anti-slide section are small and can be selected according to experience.
4, the inverse algorithm, mainly to inversely calculate the main slip segment c, φ value.
(1) First determine the current stability of the landslide, such as 1.0, 0.98, 1.02, etc.;
(2) An equilibrium section equation is used to find an index. Two equilibrium section equations are combined to obtain two values ​​of c and φ, which can also be obtained by graphic method.
(3) When conditionally restoring the limit equilibrium state before sliding, use the limit equilibrium section to reverse; if the original section cannot be restored (such as the ancient landslide), only the existing stable section can be reversed.
Fourth, the consideration of additional strength
1. Consideration of seismic forces (consideration of seismic zones above 7 degrees);
2. Consideration of static and dynamic water pressure;
3. Consideration of the buoyancy of the sliding body into the water;
4. Other additional strength considerations.
V. Determination of safety factor
1. The degree of understanding of the nature of the landslide is clear to those who are small and unclear;
2, the importance of protecting objects, important people take large values;
3, the landslide's harmfulness, the big ones take a large value;
4. The temporary project takes a large value, and the permanent project takes a large plant.
Sixth, calculate the thrust check
1. Determine the lower limit of the strength of the damaged building in the local area;
2. Defining the lower limit of landslide thrust (such as passive earth pressure) from the local landslide shear outlet and the anti-slip segment slide thickness;
3. Compare the thrust value of the landslide from the nature and scale of the landslide.
It can slow down the reaction, maintain chemical balance, reduce surface tension, prevent light, thermal decomposition or oxidative decomposition. it mainly includes lead salts, metal soaps, organic tin, organic antimony, organic rare earths, pure organic compounds. Thermal stabilizers commonly used in industry mainly include lead salts, metal soaps, organic tin, organic antimony, organic rare earths, pure organic compounds, etc.
1.1 Organotin
(1) Excellent transparency The biggest advantage of organotin stabilizers is that they have excellent transparency. The use of organotin stabilizers in PVC formulations can produce crystalline products. Because of this, organic tin can be used in bottles, containers, corrugated boards, various types of rigid packaging containers, hoses, profiles, films, etc.
(2) Extraordinary thermal stability In terms of thermal stability, there is no other type of thermal stabilizer that can surpass it. Therefore, it is the preferred stabilizer for rigid PVC, and some varieties have better performance in soft products. Suitable for all PVC homopolymers, such as emulsion, suspension and bulk PVC, as well as vinyl chloride copolymers, graft polymers and polymer blends.
(3) The product is non-toxic. Most organotin stabilizers are non-toxic, and the migration of organotin stabilizers in rigid PVC is minimal. Therefore, organotin stabilizers are the preferred heat stabilizers for PVC for food contact.
(4) Good compatibility. Organotin stabilizers have good compatibility with PVC, so there is generally no precipitation on the metal surface, such as lead salt stabilizers and metal soap stabilizer systems.
(5) Poor lubricity Sulfur-containing tin stabilizers have poor self-lubricity. Therefore, many commercially available sulfur-containing organotins are equipped with lubricants to prevent hot melt from adhering to processing equipment during processing.
(6) High cost Compared with other types of stabilizers, the overall performance of organotin stabilizers is closer to the ideal stabilizer. However, all organotin stabilizers, regardless of their structure, have the main disadvantage that their manufacturing cost is much higher than that of lead stabilizers or metal soap compounds. In recent years, by adopting new synthetic technology, or reducing its usage in formulas, its formula cost has been reduced. In the 1970s, foreign countries developed low-priced tin products, which reduced the tin content, which also reduced the price to a certain extent.
1.2 Lead salt
(1) l Excellent stability experiments proved that among the commonly used basic lead salts, the heat resistance of sulfite is better than that of sulfate, and the heat resistance of sulfate is better than that of phosphite. The tribasic lead sulfate, which is widely used in the PVC industry, has a higher effective lead content and shows better thermal stability than other products.
(2) Excellent insulation. Because lead salt is non-ionic and non-conductive, it is inert, which makes lead salt stabilizers widely used in wire and cable industries.
(3) Excellent weather resistance. Many salt compounds can act as white pigments and can show strong covering power, so they have strong weather resistance.
(4) Poor transparency Transparency is a problem related to weather resistance. When used in wires, cables and record materials, there is no need to care about transparency, because most of these products are white or very dark black.
(5) Inexpensive lead salt stabilizer is the lowest price among all stabilizers. Therefore, despite the continuous introduction of new stabilizers, lead salt stabilizers still dominate the stabilizer market after half a century. The composite lead salt introduced to solve the dust and dispersion problem has increased in price, but still maintains a competitive advantage with other types of stabilizers.
(6) The toxicity of the toxic lead salt stabilizer limits its application in many occasions with strict hygiene requirements. For example, many countries have revised the lead content standards in drinking water, and it is no longer possible to use lead salt in PVC water pipes.
(7) Poor dispersibility The dispersibility of salt lead is poor, but the newly launched one-package product is equipped with lubricants, which solves the dispersibility problem to a certain extent. Because of the above characteristics of lead salt stabilizers, they are especially suitable for high-temperature processing. They are widely used in various opaque hard and soft products and cable materials, such as various pipes, plates, indoor and outdoor profiles, foam plastics, artificial leather, and wires. Cables, records, welding rods, etc. The most important lead salt stabilizers are tribasic lead sulfate, dibasic lead phosphite, and dibasic lead stearate.
1.3 Organic antimony
(1) Better stability. The organic antimony stabilizer has basically the same color stability and lower melt viscosity as organotin at the same temperature. In the twin-screw extrusion process, the effect is particularly outstanding when used in combination with calcium stearate. .
(2) The price of organic antimony stabilizer is much lower than that of methyl tin or butyl tin. In addition, the amount of organic antimony used is relatively low, so the use of organic antimony can achieve a better performance/price balance.
(3) The product is non-toxic. In the United States, when a twin-screw extruder is used to manufacture PVC pipes, the PVC water supply pipe manufactured with a formula composed of antimony stabilizers, calcium stearate and other lubricants conforms to the U.S. NSF (National Sanitation Foundation) )Regulation.
(4) Poor transparency and light stability. The transparency of organic antimony compounds is not as good as organotin stabilizers, and it is also lower than the barium/fu and calcium/zinc metal soap system. It is close to lead salts and has poor light stability, so antimony is stable. The agent is mostly used for indoor products without color requirements. The antimony stabilizer itself is also required to be stored in an opaque container.
(5) Poor lubricity. Antimony stabilizers have poor lubricity. Therefore, its use must be combined with a large amount of lubricant without exception.
1.4 Metal soap
(1) The tin soap stabilizer Fu soap is the best type of metal soap. Its advantages are also reflected in the absence of initial coloring, and can produce colorless and transparent products; excellent light stability; it has the effect of preventing precipitation and adhesion. . However, because tin salt is toxic, there are strict regulations on its manufacture and use in the Labor Safety and Health Law. In recent years, the use of Fuzao has shown a downward trend.
(2) Zinc soap stabilizerThe thermal stability of zinc-based stabilizer to PVC is extremely poor. The sample with zinc soap suddenly turns black when heated, that is, the so-called "Zine burning" phenomenon occurs, but it has the following advantages: The initial coloring is excellent; the effect of preventing fouling is good; it can improve the weather resistance; many zinc soaps are recognized as non-toxic stabilizers, so they can be used in non-toxic formulations with calcium soaps.
(3) Barium soap stabilizer Barium compounds have good thermal stability and good lubricity, but the red initial coloration occurs during processing, and it is easy to cause sticking to the roller.
(4) The stability of calcium soap stabilizer is poor, but it is recognized as a non-toxic additive in the world and has excellent lubricity.
(5) Other metal soap stabilizers used in the industry include magnesium stearate, file stearate, aluminum stearate, potassium stearate, etc., among which magnesium stearate is similar to calcium stearate and can be used Materials that are in contact with food; aluminum stearate is similar to zinc stearate, and is approved by the U.S. FDA and the Japanese Vinyl Chloride Food Hygiene Association for food packaging; Stearic Acid files and potassium stearate are also non-toxic products and belong to lead salts , Tin soap and barium soap substitute.
(6) The performance requirements of the composite metal soap stabilizer processing industry for stabilizers are various, and a single metal soap often cannot meet the use requirements, so the use of composite stabilizers has become a trend. A single metal soap compound is rarely used in the PVC industry, and it is usually a compound of several metal soaps. This compound is not a simple addition of properties, but takes advantage of the synergy between the components. The composite metal soap stabilizer generally includes the stabilizer main body (i.e. metal soap), solvent (organic solvent, plasticizer, liquid non-metal stabilizer, etc.), functional additives (auxiliary stabilizer, transparency modifier, light stabilizer, Lubricants, etc.). According to the form, it is divided into solid compound and liquid compound. According to the main component, it can be divided into calcium/zinc compound stabilizer, barium/fu compound stabilizer, barium/zinc compound stabilizer, etc. Among them, the calcium/zinc composite stabilizer has a pivotal role in replacing toxic metals because it is non-toxic.
1.5 Rare earth stabilizer
(1) Excellent thermal stability The thermal stability of rare earth stabilizers is better than traditional lead salt series and barium/zinc, barium/ho/zinc stabilizers. In some applications, rare earth stabilizers can partially or completely replace organotin.
(2) Good transparency. The refractive index of rare earth stabilizers is very close to that of PVC Resin, which can replace traditional organotin and be used in the field of products with higher transparency requirements.
(3) Excellent weather resistance. Rare earth elements can absorb 230-320nm ultraviolet light. Therefore, rare earth stabilizers have anti-photoaging effects and are suitable for outdoor products such as PVC corrugated boards and window materials.
(4) Excellent electrical insulation properties. Some rare earth multifunctional stabilizers can be used to replace lead salt stabilizers in cable material formulations, and their electrical insulation properties are comparable to lead salts.
(5) Non-toxic, safe and hygienic. Rare earth elements are low-toxic elements and have no toxic hazards to the human body in their production, processing, transportation and storage. Rare earth stabilizers are non-toxic products and can be used in food packaging and medical packaging products.
(6) The processing performance is slightly worse. In the case of a large amount of rare earth stabilizer, the roll release of the material is not ideal, and there is a tendency to press out. Generally, better results can be achieved by using stearic acid or calcium stearate in combination.
In summary, rare earth stabilizers can be used for water pipes, injection pipe fittings, window frame profiles, door panels, wire ducts, foam products, artificial leather, cable materials, soft and hard transparent products, food packaging materials, etc.
1.6 Auxiliary stabilizers Auxiliary stabilizers include phosphite, epoxy soybean oil, hindered phenols, etc., which mainly rely on the synergistic effect between metal stabilizers to improve the stabilizing effect, and are generally called co-stabilizers. In addition to compounds such as mesaminocrotonic acid ester, 2-phenyl saccharin, vein derivatives, and diketone can be used in combination with metal stabilizers to improve the effect of metal stabilizers, they also have a certain stabilizing effect. Such compounds are usually called pure organic stabilizers. With the development of PVC stabilizers today, the progress of metal stabilizers is relatively slow, and the research and development of auxiliary stabilizers are unprecedentedly active, which has constituted a major trend in the field of PvC stabilizers. Auxiliary stabilizers are rarely used alone, and are often used in conjunction with primary stabilizers to improve initial coloration or improve long-term stability.
Lead Salt Stabilizer, Compound Stabilizer,Pvc Stabilizer,Titanium Dioxide Anatase
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