20 Key Points of Plastic Modification Formula

1.masterbatch nucleus:

The amount of masterbatch nucleus in the masterbatch is generally above 20%.

2.Dispersant:

Its function is to make the filler and carrier resin have good compatibility, and the melting point and melt viscosity should be lower than the carrier resin. Common dispersants include stearic acid and its salts, erucic acid amide, solid paraffin, liquid paraffin, polyethylene wax (i.e. relative molecular weight polyethylene), oxidized PE α- Methylstyrene, etc. The melting point of dispersants is relatively low, and they can quickly melt when the temperature rises. They are coated on the surface of inorganic fillers treated with coupling agents and crosslinking agents, making the surface tension of the masterbatch closer to the main resin. This greatly improves the dispersibility of inorganic fillers and can reduce the viscosity and increase the flowability of composite materials. The general dosage is about 5%.

3.Carrier resin:

The key to whether the filler masterbatch can be uniformly dispersed in the main resin is the choice of carrier resin. Random polypropylene has a low soft point and good encapsulation effect on particles such as calcium carbonate. The melt flow rate of the filler masterbatch is high, and the dispersion of the masterbatch in the main resin is good. However, it has a significant impact on the mechanical properties of the product and cannot meet the better requirements of the product. Due to the fact that filler masterbatch is mainly used for the processing of polyolefin plastic products such as polyethylene or polypropylene, the available carrier resins include LDPE, PS, EVA, CPE, etc. However, HDPE, PP, and PS are used as filler masterbatches for the production of carrier resins alone, which have brittle bars and are not easy to cut (particles are fragile). LLDPE has a low melt flow rate and the resulting masterbatch is not easily dispersed.

4. ABS plastic for PVC:

ABS plastic can significantly enhance the impact strength of PVC, but its effect on reducing tensile strength is not significant. Some varieties also have the function of processing aids, with a general dosage of 5-15 parts. Due to differences in composition and relative molecular weight, the modification effect of ABS often varies.

5. ABS plastic and MBS plastic:

ABS plastic and MBS plastic are both effective impact modifiers for PVC, with the main difference being that the former is mainly used for extruding pipes, profiles, rolling, and blow molding bottles. It should be noted that these modified polymers have poor weather resistance when blended with PVC due to the unsaturated double bond structure of butadiene in their components. Therefore, a light stabilizer should be added to the formula. Both have low toxicity and can be used in situations where they come into contact with food.

6. CPE:

CPE generally has a chlorine content of 20% to 50%, and varieties with a chlorine content greater than 25% have non flammability. The biggest feature of CPE modified PVC is its good weather resistance. It is generally believed that varieties with a chlorine content of 36% have the best modification effect in hard PVC, which can achieve good processability, dispersibility, and impact resistance; And it can be used as a compatibilizer for PVC and PE blends, such as adding CPE15%~25% to PVC/PE/PP blend system (30:28:42), which can achieve good blending results. Varieties with chlorine content below 25% have poor compatibility with PVCD. The main drawbacks of CPE are poor transparency, low tensile strength, and lower surface gloss compared to pure PVC products. In addition, the pores of CPE particles are higher than those of PVC, and there is more gas inclusion. During the processing, special attention should be paid to exhaust, and it is best to use an exhaust extruder during extrusion molding.

7.PVC:

Due to differences in the composition and number of layers of the shell and core, PVC has a wide variety of varieties. For hard PVC products, it is the most successful transparent (processing or impact) modifier developed after MBS.

ACR has the following effects on the modification of PVC:

a. Improving the impact strength of rigid PVC materials. As the amount of ACR added increases, the impact strength of rigid PVC gradually increases, especially in the range of 5-10 parts, the impact strength changes the fastest, and reaches its peak at 10 parts. After that, increasing the amount of ACR added has no significant effect.

b. As the amount of ACR added to the blend increases, the melt plasticization time shortens. ACR can promote the gel and plasticization of PVC resin. PVC with added ACR exhibits a significant increase in extrusion expansion compared to PVC without ACR. The general dosage of ACR201 is 1-3 portions.

8.EVA plastic raw material modified PVC plastic:

The varieties of EVA modified plastic PVC are mostly ternary EVA copolymers, such as ethylene vinyl acetate carbon oxide (E-VA-CO). The compatibility of the two blends is very good, and they act as polymer plasticizers. Due to their excellent durability, they are applied in industries such as building materials, automobiles, and footwear.

9.PVC plastic and nitrile rubber (NBR):

PVC plastic and nitrile rubber (NBR) have good compatibility, but their compatibility is extremely affected by the presence of acrylonitrile (AN) in NBR. When the AN content in NBR is about 20%, the impact strength of PVC blend is the highest.

10. Blending of PA plastic and PP plastic:

The blending of PA plastic and PP plastic improves the mechanical properties of the blend with the increase of compatibilizer, indicating that a higher amount of graft copolymer is added within a certain range, and the chemical reactions generated at the two interfaces also increase accordingly. The compatibility between PA and PP is also better. However, when the graft copolymer exceeds 6.25%, the performance actually decreases.

11.Blending of natural rubber and PE:

In the blend system of natural rubber and PE, the mechanical properties are poor due to the interpenetration between the amorphous part of PE and the amorphous natural rubber interface. If 6% of the two block copolymers (NR-b-PE) are added, the compatibility between the two is improved, and the interfacial tension is reduced, resulting in a decrease in the dispersion size of PE.

12.Compatibilizer:

The amount of compatibilizer should be as small as possible, with a commonly used amount of less than 20%, while fully saturating the entire interface of the blend.

13.Reactive Compatibilizer:

Reactive compatibilizers often contain acid based, epoxy based, isocyanate based, and vinyl based types, among others. These compatibilizers form new chemical bonds with the polymer components of the blend, also known as chemical compatibilizers. Especially suitable for blending polymers with poor compatibility and reactive functional groups. There are mainly carboxylated PE, carboxylated PP, carboxylated PS, etc., which are designed to promote the compatibility between non-polar polymers (PE, PP, PS, etc.) and polar polymer polyamide (PA).

14.Classification of flame retardant grades for plastics

The flame retardant grade of plastics increases gradually from HB, V-2, V-1 to V-0: the lowest flame retardant grade in HB: UL94 and CSA C22.2 No.0.17 standards. Require a combustion rate of less than 40 millimeters per minute for samples 3 to 13 millimeters thick; Samples less than 3 millimeters thick have a combustion rate of less than 70 millimeters per minute; Or turn off before the 100mm mark.

V-2: After two 10 second combustion tests on the sample, the flame extinguishes within 60 seconds. Burning materials can fall off.

V-1: After two 10 second combustion tests on the sample, the flame extinguishes within 60 seconds. No combustibles should fall.

V-0: After two 10 second combustion tests on the sample, the flame extinguishes within 30 seconds. No combustibles should fall.

15. Routine precautions for dyeing modified plastics:

(1) PS coloring formula PS is a colorless transparent plastic, and its coloring is mainly to fully utilize its excellent coloring performance to produce various beautiful colored parts. Emphasis should be placed on the brightness, transparency, and heat resistance of the coloring agent. Due to the migration of general colors in the middle of PS, Gu has a wide range of choices for colorants.

(2) There are several factors that affect the coloring of PVC in the PVC coloring formula: firstly, PVC is thermally decomposed and releases HCL, so a heat stabilizer should be added to the formula. Secondly, in order to reduce costs, fillers are often added, and the types and amounts of these additives have a significant impact on color changes; Once again, soft and hard products, especially the former with plasticizers, can also cause significant color changes, which should be fully understood and valued.

16. Shortcomings of using titanate coupling agents

(1) The cost is relatively high.

(2) Titanium esters, due to their own oxidation or interaction with certain antioxidants in polyolefins, are prone to form darker colored compounds, which affect the whiteness of calcium carbonate and result in graying of the masterbatch.

(3) Calcium carbonate treated with titanate coupling agent is prone to hydrolysis or alcoholysis of the oleophilic end of titanate molecules during storage or processing, resulting in loss of function. The optimal amount of titanate is determined through experiments based on the properties of the filler and the purpose of the product. Generally, it is recommended to use 0.5% -3% of the filler.

17. Aluminum ester coupling agent:

It can improve the dispersibility of various fillers and pigments, as well as the freshness of pigments. Moreover, it has a lighter color and can increase the organic film of fillers such as calcium carbonate. The thermal stability is superior to that of titanium esters, as it can act chemically on the surface of the filler and generate adhesion and cross-linking at the interface. The dosage of titanate coupling agent is generally 0.5%~2.5% of the filler. For fillers with high specific surface area or high activity surfaces such as carbon black and alumina, the dosage can be increased to 1.5%~2.5%. Aluminum ester coupling agents can be used in combination with titanium ester coupling agents to produce synergistic effects, improve performance, and reduce costs.

18.Titanate:

The amount of titanate is calculated based on the percentage of filler. The optimal amount in the process of modifying plastics should be determined through experiments based on the properties of the filler and the purpose of the product. Generally, it is recommended to use 0.5% to 3%.

19.Aluminum ester:

The general dosage of aluminate ester is 0.25-0.5 parts, which can be used in combination with tribasic lead sulfate and dibasic lead phosphite to have a synergistic stabilizing effect. It also has a certain lubricating effect on PVC and improves the surface smoothness of the product. Aluminum ester coupling agents are inexpensive and can reduce formulation costs. They can also be used in formulations such as PE, PP, PU, and PS.

20. MBS modified plastic PVC:

When modifying PVC with MBS, the amount of MBS is usually maintained at 10% to 15%. And MBS modified PVC is generally a transparent product.