Wen/Lian Rongbing 1 Zhang Weiqin 1 Huang Rui 1 Fu Wenjing 1 Ma Lan 1 Ye Shengjing 2 (1. School of Polymer Science and Engineering, Sichuan University, Chengdu, 610065; 2. Fujian Institute of Light Industry, 350001) (DCP), Tantal acid, nitrile rubber (NBR), cell regulator, etc., one-step molding of soft PVC sole foaming material.
The effects of AC, DCP, citric acid, NBR and cell regulator on the density and mechanical properties of soft PVC foams were investigated. The results showed that in the case of AC4.O, DCPO.2 parts, O.2 parts of citric acid, 40.0 parts of NBR and 11.1 parts of cell regulator, the foaming material has excellent performance, and its density and mechanical properties satisfy softness. PVC sole foaming material requirements.
Polyvinyl chloride (PVC) foaming materials have excellent mechanical properties, convenient processing and low cost, and still occupy a large proportion in the market of medium and low-grade sole materials. At present, most of the soft PVC foaming materials are produced by molding secondary foaming. This test adopts one-step molding, and based on the preliminary test work, the cross-linking agent dicumyl peroxide (DCP) and lemon 朦 are added. The acid (hereinafter referred to as L), the cell regulator (hereinafter referred to as A) components, the foaming agent azodicarbonamide (AC), DCP, L, nitrile rubber (NBR), A amount The effect of density and mechanical properties of soft PVC foaming materials was selected to meet the formula of density and mechanical properties to meet the PVC sole foaming materials.
Commercially available; dioctyl phthalate (DOP), DCP, chemically pure, all commercially available; heat stabilizer, nucleating agent, industrial grade, commercially available; A, Wenzhou Tiansheng Plastics Additive Co., Ltd.; powder NBR , Petrochemical Research Institute of Lanzhou Petrochemical Company.
Haijiao Machinery Factory; flat vulcanizing machine, XLB type, Qingdao Third Rubber Machinery Factory; tensile testing machine, XL-250, Guangzhou Experimental Instrument Factory; rubber hardness tester, LX-C type, Shanghai Liuling Instrument Factory; Instrument, CH-10-AT type, Shanghai Liuling Instrument Factory; electric blast drying oven, type 101, Shanghai Experimental Instrument Factory; differential scanning calorimeter (DSC), DSC-2C type, American PE company; Scanning microscope, SM-5900LV, 曰本曰立.
Test; tensile strength and elongation at break are tested according to GB/T6344-1996; tear strength is tested according to GB/T10808-1989; indentation hardness is tested according to GBl0807-1989; expansion ratio is foaming sample volume and mold type The ratio of the volume of the cavity. Physical properties of PVC sole foaming material: density is 0.22~0.40g/cm3, hardness is 22~40N, tensile strength is not less than 2.06MPa, tear strength is not less than 15N/mm, and elongation at break is not less than 130% 60.0 parts, 6.2 parts of heat stabilizer, 1.0 part of nucleating agent, AC; DCP, L, NBR, A variable.
Basic process conditions: 1 accurately weigh according to the formula, mix PVC, DOP, heat stabilizer, etc., put it into the drying oven of 100~110 °C for pre-plasticization, and stir once every 5mm, stir a total of 4~5 Secondly, the DOP is completely absorbed by the PVC resin; 2 double-roll mastication, the pre-plasticized PVC mixture is added to the double-roller plasticizer (roller temperature is 110-120 ° C), after melting, NBR is added, and then sequentially added Human DCP, AC, after 8 minutes of mixing, the film was released; 3 pressed foaming, temperature 165C, pressure 10MPa, pressing time was 9min, cold pressing for 6min immediately after the die was released, and the foaming material was pressed for 24h to test the performance.
2.1 The effect of AC dosage on the performance of foaming materials The decomposition products are non-toxic, odorless and non-polluting. They are the most widely used chemical foaming agents in domestic applications. It is the AC solution temperature. The heat stabilizer of rvI can be activated to initiate the decomposition of AC so that its decomposition temperature is consistent with the PVC press foaming temperature. Therefore, a heat stabilizer of PVC can be selected as the AC activation initiator.
The effect of the amount of AC on the properties of the foamed material is shown in Table 1. It can be seen from Table 1 that the density of the color of the foamed material in Table 1AC with the performance of the paired foamed material decreases first and then increases with the increase of the amount of AC. This is because, as the amount of AC increases, the amount of gas released is increased, and the number of cells generated increases, so the material density decreases. However, when the AC is added too much, more gas is generated, and the gas is easily removed from the body. In the middle, the density of the material becomes larger. When the amount of AC used was 4.0 parts, the foamed material had a small density and excellent mechanical properties, so the amount of AC was set to 4.0 parts.
The effect of the amount of DCP on the properties of the foamed material is because the melt viscosity of PVC is low and the stability is poor at high temperature, and the cells are easily broken. Therefore, it is difficult to prepare a non-crosslinked PVC foam plastic by a one-step molding method at a high temperature. For the above reasons, the cross-linking agent DCP was added to the test, and a soft PVC foaming material was prepared by a one-step chemical cross-linking molding method. To obtain a closed-cell foam with low density, the cross-linking rate of the system must be strictly matched with the foaming rate. P. Table 2 shows the effect of the amount of DCP on the properties of the foamed material when the amount of AC is 4.0 parts. It can be seen from Table 2 that when the DCP is used for the DCP with the paired foamed material screen, the foaming material has the largest expansion ratio and the most foaming. It is reported that when the density of the foamed material is small, the mechanical properties are good, and the expansion ratio is large, it indicates that the crosslinking rate and the foaming rate are matched. Therefore, it is preferred to use 0.2 part of DCP.
The effect of the amount of L on the properties of the foamed material L can not only cause acid-base neutralization reaction with the alkaline substance in the AC decomposition product, but also promote the rapid decomposition of the AC, and also advance the secondary endothermic reaction during AC decomposition, partially offsetting the AC. The amount of heat released by the primary reaction during decomposition. This is because AC pyrolysis is divided into two reactions, the primary reaction is an exothermic reaction, the secondary reaction is an endothermic reaction, and the primary reaction is followed by a secondary reaction. It is also possible to see the two reactions at the time of AC decomposition. The reaction equation for the decomposition of AC at high temperature is: where (1) is the main reaction and (2) is the secondary reaction.
AC, DCP dosage is 4.0, 0.2 parts respectively. The effect of L dosage on the properties of foaming materials is shown in Table 3. Table 3L uses the density of the foaming material for color L density/dong/mass (gcm-3) Tensile strength / MPa tear strength Elongation at break, as can be seen from Table 3, when the amount of L is 0.2 parts, the density of the foamed material is small, and when the amount thereof is increased, the density of the foamed material is gradually increased. This may be due to the fact that when the amount of L is large, the decomposition speed of AC is accelerated, the amount of gas is increased, and the gas in the melt is easily lost, resulting in an increase in the density of the foamed material.
When the amount of L is 0.2 parts, the foamed material has excellent mechanical properties, especially the material strength, which is better than when L is not added. This is because L reduces the amount of heat released during AC decomposition, which is beneficial to improve the cell structure and improve the mechanical properties of the foamed material. Considering the density and mechanical properties of the foamed material, the amount of L is set to 0.2 parts.
The effect of the amount of NBR on the properties of the foamed material is good. The viscosity of the melt is good. When foaming, it is easy to obtain a foamed plastic product with a lower density and better cells. In addition, powder NBR has good compatibility with low molecular plasticizers, and blending with PVC can improve the durability of plasticizers for PVC products. Table 4 shows the effect of the amount of NBR on the properties of the foamed material.
NBR uses density/stretching strong tearing degree/breaking hardness/amount/part of mass (gcm3).
Note: When A(', DCP, L is 40.0 parts, the material density is small. When the NBR dosage continues to increase, the density of the foaming material will rise back. This is because the viscosity of the system is too large when the NBR is added too much. It is difficult to form bubbles, so the density becomes large. When the amount of NBR is 40.0 parts, the elongation at break and the tear strength of the foamed material are also good. Therefore, it is preferred to take 40.0 parts of NBR.
Effect of A dosage on material properties The main function of cell regulator is to promote plasticization and melting of PVC, improve the strength and elongation of foamed melt, and make the foaming process stable and controllable, thus facilitating the formation of uniform, fine and stable foam. Hole structure. In order to improve the cell structure and reduce the material density, A. is the effect of the amount of A on the expansion ratio of the foamed material.
At the time of dispensing, the material has the highest foaming rate and the most complete foaming.
When the amount of A is 11.0 parts, the density of the foamed material is the smallest, the tearing strength of the foamed material is large, and the hardness is small, but the tensile strength and elongation at break of the material are reduced, but the soft PVC is basically satisfied. Sole foaming material requirements.
When the amount of AC is 4.0 parts and the amount of DCP is 0.2 parts, the crosslinking rate and foaming rate of the foaming system are matched, and the density of the foaming material is small and the mechanical properties are good.
L can reduce the heat released during AC decomposition and improve the mechanical properties of the foamed material. When the amount of L is 0.2 parts, the foamed material is excellent in overall performance.
A can improve the cell structure of the foamed material, reduce the density of the foamed material, and increase the expansion ratio of the material. When the amount of A is 11.0 parts, the foamed material has the lowest density, uniform cell distribution, and excellent mechanical properties.
When the content of L and 11.0 parts, the density of the foamed material reaches 0.359 g/cm3, the tearing strength of the foamed material is large and the hardness is small, but the tensile strength and elongation at break are reduced, but the softness is basically satisfied. PVC sole foaming material requirements.
Electron micrograph of the cell distribution of the foam material in the mass ratio l00.0/40.0/11.0. It can be seen that the cell ratio of (b) is more uniform than that of (a) cell, and there are fewer holes, parallel holes and large holes. It can be seen that A improves the cell structure of the foamed material. (Finish)
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