Film is mainly made of polyvinyl chloride, polyethylene, polypropylene and other resins, with flexibility, ductility, good processing performance and printing performance, has been widely used in food, medicine, chemical and other fields, but due to the high cost of resin production, the environmental impact is large, usually need to add filler to reduce costs. Due to the performance problems of ordinary fillers, it will have an impact on the transparency of the film. Nano calcium carbonate as a new type of filler, particle size is small, the specific surface area is large, can increase the strength of plastic film, with small specific gravity, low manufacturing cost and other advantages.
Through the experimental study of the factors affecting the performance of nano calcium carbonate such as the crystal form control agent, the amount of barium sulfate, and the formula of the surface modifier, and the application test was carried out for the preparation of PE film, which provided ideas for the preparation of nano calcium carbonate with small specific gravity, good dispersibility and low oil absorption value.
First, the influence of the amount of crystal shape control agent on the performance of the film
In the process of preparing nano calcium carbonate, 0.3%, 0.6%, 1.2%, and 2% (according to the dry base content of nano calcium carbonate) sorbitol was added, respectively, and the effects of different sorbitol dosages on the properties of nano calcium carbonate and film were investigated (2). It can be seen from the table: the blank sample of sorbitol without the crystalline control agent is smaller than the surface area and the transparency is poor; with the increase of sorbitol, the particles become smaller, the specific surface area increases, which is conducive to light diffraction and the transparency rate increases; but the specific surface area reaches a certain extent, the oil absorption value increases, the processing resistance increases, and the force between the particles is strong, resulting in a decrease in dispersion. Considering all, it was determined that the amount of sorbitol was 0.6% of nano calcium carbonate.
Effect of pattern control agent dosage on film performance
Second, the effect of the amount of balsium sulfate on the performance of the membrane
Nano calcium carbonate was coated with different amounts of barium sulfate such as 0%, 5%, 10%, 15% (according to the dry basis of nano calcium carbonate) to investigate the effect of barium sulfate dosage on film performance. The form of nano calcium carbonate is a cube, and the main purpose of adding barium sulfate to coat nano calcium carbonate is to form a sedimentary layer with a sponge structure, which produces a certain void rate, improves dispersion, improves light transmittance, and then improves transparency. It can be seen from the table: with the increase in the amount of barium sulfate, the nano calcium carbonate is coated by barium sulfate, the dispersion and light transmittance become better, when the dosage reaches more than 10%, the light transmittance does not change much, and the cost factor is considered comprehensively, and the amount of barium sulfate is determined to be 10% of the dry base of the nano calcium carbonate.
Effect of the amount of barium sulfate coated on membrane properties
Third, the impact of surface treatment formula on membrane performance
5% to 6% of different surface treatment agents were added for testing to investigate their effects on the properties of nano calcium carbonate and thin films. As can be seen from the following table, in Test 1: the hydrophilic coo- group in stearic acid soap is combined with ca2+ to form calcium stearate, and the coating on the surface of the nano calcium carbonate forms an overlay layer, which can improve dispersion and reduce the oil absorption value. In Test 2: Phosphate ester is a coupling agent with alkoxy group as the center of phosphorus, composed of multiple oleophilic long carbon chain groups, uniformly dispersed in stearic acid soap solution, and coated with stearic acid soap on the surface of nano calcium carbonate, which can reduce the oil absorption value, improve dispersion and light transmittance. Test 3: Tributyl citrate is a good plasticizer, with pe masterbatch has good compatibility, high plasticization efficiency, strong weather resistance, tributyl citrate dissolved in stearic acid soap, adsorbed to the surface of nano calcium carbonate, improve the compatibility of nano calcium carbonate and pe, improve dispersion and light transmittance. Test 4: Dissolve phosphate ester and tributyl citrate by stearic acid soap, coated to the surface of nano calcium carbonate, stearic acid soap can improve dispersion, phosphate coupling agent has a enhancing effect, tributyl citrate increases compatibility, can reduce oil absorption value, improve dispersion and improve light transmittance. Taken together, the Test 4 formula has a low oil absorption value, good dispersion and visible light transmittance.
Effect of surface treatment formulations on membrane properties
Fourth, nano calcium carbonate performance
Comparison of nano calcium carbonate prepared in this test with nano calcium carbonate index for rubber plastics in gb/t 19590-2011. As can be seen from the table, the nano calcium carbonate of this test reaches the i-type standard, and the average particle size from Figure 1 electron microscopy is 40 nm, and the laser particle size test d50 is 0.43 μm, and the d97 is 6.6 μm, which has good dispersion.
The nano-calcium carbonate of this test was compared with the indicators of gb/t 19590-2011
V. Comparison of performance of alternative nano barium sulfate
Using the Formula of Table 1, the nano-calcium carbonate (a) prepared by this test and the nano-barium sulfate (b) were mixed with the same number of parts, the masterbatch was prepared by granulation, the film was prepared by blowing the film, and its transparency and dispersion were detected (Table 6). As can be seen from Table 6, the nano calcium carbonate made of this test, the prepared film in the dispersibility and light transmittance and other properties to achieve the nano barium sulfate index, and the proportion of the masterbatch 2.15g / cm3 compared with the proportion of nano barium sulfate masterbatch is more than 50%, the same amount of masterbatch blown film area is large, can reduce the production cost of the masterbatch, has a good market prospects.
Comparison of nano-calcium carbonate(a) and nano-barium sulfate(b).
conclusion
The amount of sorbitol of the crystalline control agent is 0.6% of the nano calcium carbonate, 10% of the amount of nano calcium carbonate barium sulfate as an inorganic surface agent, the use of 4% stearic acid soap, 1% ester coupling agent and 1% citrate as the organic surface treatment agent, the specific surface area of the nano calcium carbonate prepared is 30.6m2/g, the oil absorption value is 19.2 gdop/100g, the average particle size of the electron microscopy test is 40nm, the laser pelletizer test d50 is 0.43μm, and the prepared pe film, It has good dispersibility and light transmittance of up to 88.9%.
Nano calcium carbonate has a smaller specific gravity than nano barium sulfate, compared with the proportion of nano barium sulfate masterbatch is more than 50%, the same weight of masterbatch can blow the film area is larger, can reduce the production cost of masterbatch.