Manufacturing method for curing film

Abstract

The invention relates to the technical field of natural rubber, and particularly provides a rubber sheet curing manufacturing method. The method comprises the following steps: (1) filtering fresh latex twice, diluting, mixing the diluted latex with a formic acid solution in a parallel flow manner, and curing to obtain clots; (2) pressing the clots to 5-6 cm, then pressing the clots into slices of 4-5 mm, and curing and rolling the slices; (3) granulating the product obtained in the step (2) to obtain colloidal particles; and (4) carrying out water dripping treatment on the colloidal particles, and then drying under the condition that the front end temperature is 115-120 DEG C and the rear end temperature is 102-108 DEG C to obtain the film. Compared with the prior art, the prepared film product has good tensile property and can meet the requirements of customers on high-quality products.

Description

Technical Field

[0001] The present invention relates to the technical field of natural rubber, and more particularly to a method for preparing a rubber aging process. Background Art

[0002] Natural rubber refers to rubber extracted from the latex of the rubber tree (Hevea brasiliensis). This latex is mainly composed of polymerized isoprene molecules. Natural rubber has excellent elasticity, can quickly recover to its original shape after stretching, and has good wear resistance, which is suitable for making products that require high elasticity and durability; natural rubber can be used to make rubber products such as tires, hoses, rubber shoes, rubber clothing, etc., and is also widely used in industrial seals, medical devices, cable insulation and other fields; in addition, rubber trees can continuously produce rubber latex, so natural rubber is a sustainable raw material that is conducive to environmental protection and sustainable development. Overall, natural rubber has important economic value and wide application worldwide due to its unique physical and chemical properties.

[0003] The output of natural rubber processing products accounts for about 85%-90% of the total output of natural rubber. Among them, more than 65% of natural raw rubber is used in the tire industry, and the rest is used to manufacture rubber products such as conveyor belts, hoses, rubber shoes, etc. Different primary products have different indicators. At present, the products used by domestic product factories all belong to universal indicators. Generally, the impurity content is less than 0.05%, the ash content is less than 0.5%, the nitrogen content is less than 0.6%, the volatile content is less than 0.8%, the initial plasticity value (P0) is not less than 30, the plasticity retention index (PRI) is not less than 60, the Mooney viscosity is about 83, the tensile strength is greater than 18MPa, the elongation at break is greater than 650%, and the tensile strength is greater than 200%, which is difficult to meet the needs of high-end customers. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for preparing film aging. The film product prepared by the present invention has good performance and can meet customer needs.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing film aging, comprising:

[0007] (1) mixing the pretreated latex and formic acid solution, and ripening the mixture after coagulation to obtain a clot;

[0008] (2) pressing the curd to 5-6 cm, and then using three creping machines to crepe the curd into 4-5 mm thin sheets, and curing and rolling the thin sheets;

[0009] (3) granulating the product obtained in step (2) to obtain granules;

[0010] (4) The rubber particles are subjected to a water dripping treatment and then dried at 115-120° C. at the front end and 102-108° C. at the rear end to obtain a film.

[0011] Preferably, the pretreatment is that the fresh latex is first filtered through a 40-50 mesh sieve, then filtered through a 1000r / min rotary filter, and finally diluted with water.

[0012] Preferably, the latex content after dilution with water is 21-23 wt %

[0013] Preferably, the mass concentration of the formic acid solution is 85%, the volume ratio of the pretreated latex to the formic acid solution is (340-360):1, and they are added into the long tank in parallel until the latex coagulates.

[0014] Preferably, the ripening time in step (1) is 48 to 55 hours.

[0015] Preferably, after the pretreated latex and formic acid solution are mixed, the pH is adjusted to 5.1 to 5.9.

[0016] Preferably, in step (2), the time for ripening and curling is 110 to 120 hours.

[0017] Preferably, the dry basis moisture content of the colloid particles after the water dripping treatment is controlled to be ≤32%.

[0018] Preferably, the drying time is 6 to 7 hours.

[0019] Preferably, the drying is carried out in a drying vehicle, and after the drying is completed, the product is taken out of the vehicle and the temperature is controlled within 50°C.

[0020] Preferably, the film aging production method involved in the present application produces high-performance film.

[0021] Compared with the prior art, the present invention has the following beneficial effects: verified by the test examples of the present invention, the film prepared in the embodiments of the present invention has an impurity content of less than 0.03%, an ash content of less than 0.4%, a nitrogen content of less than 0.5%, a volatile matter content of less than 0.7%, an initial plasticity value (P0) of not less than 43, a plasticity retention index (PRI) of not less than 84, a Mooney viscosity of not less than 86, a 140°C×40min vulcanized rubber tensile strength of not less than 25MPa, an elongation at break of not less than 851%, a 300% tensile stress of not less than 1.5MPa, and a 500% tensile stress of not less than 4.7MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the film aging production process in an embodiment of the present invention;

[0023] Figure 2 After the pellets are treated with dripping water, the front and rear drying temperatures are set. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In order to further illustrate the present invention, the following examples are used to explain it in detail. The raw materials used in the following examples and comparative examples of the present invention are all commercially available products.

[0026] 1. Implementation

[0027] The method for preparing rubber maturation in the embodiment of the present invention uses fresh latex collected from the normal rubber tapping of the Haikou Experimental Station of the Chinese Academy of Tropical Agricultural Sciences and sent to the rubber factory for processing, with a dry rubber content of 30.2% and an ammonia content of 0.08%. The process flow of this application is as follows: Figure 1 As shown, including the following:

[0028] Example 1

[0029] A method for preparing film aging, comprising:

[0030] (1) filtering fresh latex through a 40-mesh sieve, then filtering it through a rotary filter at 1000 r / min, and finally diluting it with water to a latex content of 21 wt %, thereby obtaining pretreated latex; adding the pretreated latex and a formic acid solution having a mass concentration of 85% in a volume ratio of 340:1 into a long tank for coagulation, adjusting the pH to 5.1, the latex flow rate: the formic acid solution flow rate = 10:1, and ripening the coagulated material at 28° C. for 48 hours to obtain a clot;

[0031] (2) the curd is pressed into a 5 cm thick sheet by a double roller press under a roller pressure of 1000 kgf, the water is removed, and then the curd is pressed into a 4 mm thin sheet by three creping machines, and the thin sheet is aged and rolled at a temperature of 33° C. for 110 hours;

[0032] (3) crushing and granulating the product obtained in step (2) by a granulator to obtain granules;

[0033] (4) The rubber particles are subjected to a water dripping treatment to make the dry basis moisture content of the rubber particles ≤32%, and then dried for 6 hours at 115°C at the front end and 102°C at the rear end to obtain a film; the film is cooled by exhaust air from a blower until the temperature of the film is controlled below 50°C, and then weighed and packaged; after grading, it is stored and transported.

[0034] Example 2

[0035] A method for preparing film aging, comprising:

[0036] (1) filtering fresh latex through a 40-mesh sieve, then filtering it through a rotary filter at 1500 r / min, and finally diluting it with water to a latex content of 23 wt %, thereby obtaining pretreated latex; adding the pretreated latex and a formic acid solution having a mass concentration of 85% in a volume ratio of 360:1 into a long tank for coagulation, adjusting the pH to 5.9, the latex flow rate: the formic acid solution flow rate = 10:1, and ripening the coagulated material at 28° C. for 55 h to obtain a clot;

[0037] (2) the curd is pressed into a 6 cm thick sheet by a double roller press under a roller pressure of 1000 kgf, the water is removed, and then the sheet is pressed into a 5 mm thin sheet by three creping machines, and the thin sheet is aged and rolled at a temperature of 38° C. for 120 hours;

[0038] (3) crushing and granulating the product obtained in step (2) by a granulator to obtain granules;

[0039] (4) The rubber particles are subjected to a water dripping treatment to make the dry basis moisture content of the rubber particles ≤32%, and then dried for 7 hours at 120°C at the front end and 108°C at the rear end to obtain a film; the film is cooled by exhaust air from a blower until the temperature of the film is controlled below 50°C, and then weighed and packaged; after grading, it is stored and transported.

[0040] Example 3

[0041] A method for preparing film aging, comprising:

[0042] (1) filtering fresh latex through a 40-mesh sieve, then filtering it through a rotary filter at 1200 r / min, and finally diluting it with water to a latex content of 22 wt %, thereby obtaining pretreated latex; adding the pretreated latex and a formic acid solution having a mass concentration of 85% in a volume ratio of 343:1 into a long tank for coagulation, adjusting the pH to 5.5, the latex flow rate: the formic acid solution flow rate = 10:1, and ripening the coagulated material at 28° C. for 50 h to obtain a clot;

[0043] (2) the curd is pressed into a 6 cm thick sheet by a double roller press under a roller pressure of 1000 kgf, the water is removed, and then the sheet is creped into a 5 mm sheet by three creping machines, and the sheet is aged and rolled at a temperature of 35° C. for 115 hours;

[0044] (3) crushing and granulating the product obtained in step (2) by a granulator to obtain granules;

[0045] (4) The rubber particles are subjected to a water dripping treatment to make the dry basis moisture content of the rubber particles ≤32%, and then dried for 7 hours at 116°C at the front end and 105°C at the rear end to obtain a film; the film is cooled by exhaust air from a blower until the temperature of the film is controlled below 50°C, and then weighed and packaged; after grading, it is stored and transported.

[0046] 2. Comparison

[0047] Comparative Example 1

[0048] This comparative example refers to the preparation method in Example 3, and the only difference from Example 3 is that in this comparative example, the latex flow rate: formic acid solution flow rate = 5:1; the remaining steps are carried out by referring to the method in Example 3.

[0049] Comparative Example 2

[0050] This comparative example refers to the preparation method in Example 3, and the only difference from Example 3 is that the aging and curling time in step (2) is adjusted to 130 hours in this comparative example; the remaining steps are carried out according to the method in Example 3.

[0051] Comparative Example 3

[0052] This comparative example refers to the preparation method in Example 3, and the only difference from Example 3 is that the drying time in step (4) is kept unchanged at 7 hours, and the drying temperature is adjusted to 125°C at the front end and 115°C at the rear end; the remaining steps are carried out according to the method in Example 3.

[0053] 3. Test Examples

[0054] In this test example, the performance of the films prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested. The test method was carried out in accordance with the standards in Table 1, wherein the tensile strength, tear productivity and tensile stress at break were tested under the conditions of 140°C × 40min. The test results are shown in Table 2.

[0055] Table 1

[0056] performance Test methods Impurity content, % (m / m), maximum value GB / T8086-2008 Ash content, % (m / m), maximum GB / T4498-1997 Nitrogen content, % (m / m), maximum GB / T8088-2008 Volatile matter content, % (m / m), maximum GB / T24131-2009 Initial plasticity value, minimum value GB / T3510-2006 Plasticity retention rate, minimum GB / T3517-2002 Mooney viscosity, ML / (1'+4')100℃ GB / T1232.1-2000 Tensile strength, MPa, minimum GB / T528-2009 Elongation at break, %, minimum GB / T528 300% tensile stress (MPa) GB / T3780.18-2007 500% modulus of tensile stress (MPa) GB / T3780.18-2007

[0057] Table 2

[0058]

[0059]

[0060] As shown in Table 2, compared with Comparative Examples 1 to 3, the films prepared by the methods used in Examples 1 to 3 of the present invention have less impurity content and higher mechanical properties, and can meet the requirements of high-performance tires. Comparison between Example 3 and Comparative Example 1 shows that the parallel flow rates of the latex flow rate and the formic acid solution flow rate before mixing affect the quality of the finished film. Controlling the flow rates of the two can ensure uniform mixing, which is beneficial to the subsequent aging process; Comparison between Example 3 and Comparative Example 2 shows that increasing the aging and rolling time will cause the film to be too hard and reduce elasticity, which is not conducive to subsequent processing and use. Comparison between Example 3 and Comparative Example 3 shows that increasing the temperature of the rubber particle treatment will cause the rubber molecular chain to break, reducing its strength and durability.

[0061] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing film aging, characterized in that: include: (1) mixing the pretreated latex and formic acid solution in parallel, adjusting the pH to 5.1 to 5.9, and ripening after coagulation to obtain a clot; (2) pressing the curd to 5-6 cm, and then pressing it into a thin sheet of 4-5 mm, and curing and rolling the thin sheet; (3) granulating the product obtained in step (2) to obtain granules; (4) The rubber particles are subjected to a water dripping treatment and then dried at 115-120° C. at the front end and 102-108° C. at the rear end to obtain a film.

2. The method for preparing film aging according to claim 1, characterized in that: The pretreatment is that the fresh latex is first filtered through a mesh sieve, then subjected to a rotary filtration at 1000-1500 r / min, and finally diluted with water.

3. The method for preparing film aging according to claim 2, characterized in that: After dilution with water, the latex content is 21-23 wt%.

4. The method for preparing film aging according to claim 1, characterized in that: The mass concentration of the formic acid solution is 85%, and the volume ratio of the pretreated latex to the formic acid solution is (340-360):

1.

5. The method for preparing film aging according to claim 1, characterized in that: The co-flow rate of the pre-treated latex and formic acid solution was latex:formic acid solution=10:

1.

6. The method for preparing film aging according to claim 1, characterized in that: The ripening time in step (1) is 48 to 55 hours.

7. The method for preparing film aging according to claim 1, characterized in that: In the step (2), the curing and curling time is 110 to 120 hours.

8. The method for preparing film aging according to claim 1, characterized in that: The dry basis moisture content of the colloid particles after the dripping treatment is controlled to be ≤32%.

9. The method for preparing film aging according to claim 1, characterized in that: The drying time is 6 to 7 hours.

10. Film produced by the film aging method according to any one of claims 1 to 9.

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