Fluorescent natural rubber composite material and preparation method thereof

Abstract

The application discloses a fluorescent natural rubber composite material, which is prepared by mixing natural rubber, stearic acid, zinc oxide, accelerator M, sulfur and organic luminescent crystals on an open mill, uniformly mixing the rubber and the filler, calendering out a sheet, and vulcanizing at 120 DEG C to 150 DEG C to obtain the fluorescent natural rubber composite material. After the organic luminescent crystals are mixed with the natural rubber matrix, the natural rubber is endowed with the fluorescent property, and meanwhile, the organic luminescent crystals can interact with the natural rubber, so that the tensile strength, the breaking property and the wear resistance of the natural rubber are further improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rubber, and particularly relates to a fluorescent natural rubber composite material and a preparation method thereof. BACKGROUND

[0002] The natural rubber composite material with fluorescent properties combines the excellent elasticity of rubber and the unique optical properties of fluorescent substances. This new type of material has broad application potential in the fields of safety marking, environmental monitoring, biological sensing, and artistic decoration.

[0003] In the preparation of fluorescent natural rubber composite materials, the selection of light-emitting units is crucial. Existing light-emitting units for constructing natural rubber are basically selected from common light-emitting additives, inorganic fluorescent powders, and carbon-based nanomaterials. These units are prepared using methods such as solvent blending, in-situ polymerization, surface grafting, and nanoparticle doping. However, regardless of the type of light-emitting unit or the preparation method used, the added light-emitting unit only imparts fluorescent properties to the material and does not participate in the adjustment or modification of the rubber material's performance, nor does it improve the performance of the natural rubber composite material. For example, Chinese Patent Application No. CN201910683682.3 discloses a luminescent tire and its processing technology. The raw materials include isoprene rubber, natural rubber, butadiene rubber, ethylene-propylene-diene rubber, white carbon black, rubber operating oil, zinc oxide, stearic acid, activator, protective wax, antioxidant, fluorescent powder, accelerator, and sulfur. The tire prepared from the above-mentioned raw materials not only emits light at night but also maintains the original good wear resistance of the tire. As disclosed in the scientific literature "Synthetic Rubber Industry, 2005-11-15, 28(6):432-434", the preparation and properties of fluorescent rubber are described. In the "2.1.4 Influence of Fluorescent Powder on Fluorescent Properties" section, it is explicitly stated that "the amount of fluorescent powder has little effect on the mechanical properties of fluorescent rubber, but as the amount of fluorescent powder increases, the fluorescent effect of fluorescent rubber is enhanced". SUMMARY

[0004] Therefore, the purpose of the present application is to provide a fluorescent natural rubber composite material to solve the problem of the added light-emitting unit only imparting fluorescent properties to the composite material, not participating in the adjustment or modification of the rubber material's performance, and not improving the performance of the natural rubber composite material.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A fluorescent natural rubber composite material comprises the following raw materials in parts by weight: natural rubber 100 parts, stearic acid 0.1-1 part, zinc oxide 2-7 parts, accelerator M 0.3-1.2 parts, sulfur 1-6 parts, and organic luminescent crystals 0.1-2 parts.

[0007] In an alternative embodiment, the organic luminescent crystals are organic luminescent crystals A or organic luminescent crystals B.

[0008] In an alternative embodiment, the preparation process of the organic luminescent crystals A comprises the following steps: dissolving 2,5-dimethoxy acyl-1,4-cyclohexanedione in methanol to obtain a suspension, adding n-pentylamine to the suspension, stirring to obtain a mixture, and cooling, suction filtering and concentrating the mixture to obtain a red powder, dissolving the red powder in a solvent, and culturing the organic luminescent crystals A by solvent diffusion method, wherein the organic luminescent crystals A are dimethyl 2,5-di(pentylamine) terephthalate.

[0009] In an alternative embodiment, the preparation process of the organic luminescent crystals B comprises the following steps: dissolving 2,5-dimethoxy acyl-1,4-cyclohexanedione in methanol to obtain a suspension, adding 3-amino-1-propanol to the suspension, stirring to obtain a mixture, and cooling, suction filtering and concentrating the mixture to obtain a red powder, dissolving the red powder in an organic solvent, and culturing the organic luminescent crystals B by solvent diffusion method, wherein the organic luminescent crystals B are dimethyl 2,5-di(3-hydroxypropyl) terephthalate.

[0010] In an alternative embodiment, the mass ratio of 2,5-dimethoxy acyl-1,4-cyclohexanedione to n-pentylamine is 1:3-4.

[0011] In an alternative embodiment, the mass ratio of 2,5-dimethoxy acyl-1,4-cyclohexanedione to 3-amino-1-propanol is 1:3-4.

[0012] In an alternative embodiment, the organic solvent is a mixed solvent of dichloromethane and petroleum ether.

[0013] In an alternative embodiment, the organic solvent is a mixed solvent of methanol and cyclohexane.

[0014] The application also provides a preparation method of the fluorescent natural rubber composite material, which comprises the following steps: mixing natural rubber, stearic acid, zinc oxide, accelerator M, sulfur and organic luminescent crystals on an open mill to uniformly mix the rubber and fillers, calendering out a sheet, and vulcanizing at 120-150 DEG C to obtain the fluorescent natural rubber composite material.

[0015] Compared with the prior art, the technical scheme of the application has the following advantages:

[0016] 1. The present invention mixes organic light-emitting crystals with a natural rubber matrix, which not only imparts fluorescent properties to the natural rubber, but also interacts with the natural rubber to further improve its tensile strength, fracture properties and wear resistance.

[0017] 2. The organic light-emitting crystal of the present invention has low raw material cost, is green and environmentally friendly, and can be synthesized by simple one-step reaction and crystal engineering, making it suitable for large-scale application. Moreover, the organic light-emitting crystal has good dispersibility, modifiability and biocompatibility in natural rubber matrix, which can improve the composite effect with rubber matrix. It can also be vulcanized with natural rubber without adding processing steps and costs. Attached Figure Description

[0018] Figure 1 The fluorescence spectra of organic light-emitting crystal A and fluorescent natural rubber composite material (organic light-emitting crystal A) are shown in the embodiments of the present invention.

[0019] Figure 2 This is a comparison diagram of the tensile strength of natural rubber composite material and fluorescent natural rubber composite material (organic light-emitting crystal is organic light-emitting crystal A) in the embodiments of the present invention;

[0020] Figure 3 This is a comparison diagram of the fracture energy of natural rubber composite material and fluorescent natural rubber composite material (organic light-emitting crystal is organic light-emitting crystal A) in the embodiments of the present invention;

[0021] Figure 4 This is a comparison chart of the wear resistance of natural rubber composite material and fluorescent natural rubber composite material (organic light-emitting crystal is organic light-emitting crystal A) in the embodiments of the present invention;

[0022] Figure 5 This is a hardness comparison diagram of the natural rubber composite material and the fluorescent natural rubber composite material (organic light-emitting crystal is organic light-emitting crystal B) in the embodiments of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0024] Example 1

[0025] (1) Preparation of organic light-emitting crystal A

[0026] The method comprises the following steps: 1.2 g of 2,5-dimethoxyacyl-1,4-cyclohexanedione and 30 mL of methanol are added into a 100 mL double-port round-bottom flask, 3.7 g of n-pentylamine is added into the suspension, the round-bottom flask is equipped with a rubber plug and a spherical condenser, and the round-bottom flask is fixed, a mixture is obtained after stirring at 60°C and under normal pressure open air for 10 h, the mixture is cooled to room temperature, is poured into a Buchner funnel for suction filtration, and a filter cake is collected; after the filter cake is washed with petroleum ether, the filter liquor is concentrated to obtain 1.60 g (4.39 mmol, 88%) of a red powder; and dimethyl 2,5-di(pentylamine) terephthalate is obtained by using a solvent diffusion method with dichloromethane and petroleum ether (1:2 in volume ratio) as solvents.

[0027] The chemical reaction formula is as follows:

[0028]

[0029] (2) Preparation of a fluorescent natural rubber composite material

[0030] The method comprises the following steps: 100 g of raw rubber is plasticized on an open mill for 10 min, after uniform plasticization, 0.5 g of stearic acid, 5 g of zinc oxide, 0.7 g of accelerator M (2-mercaptobenzothiazole), 3 g of sulfur and 0.2 g of the organic luminescent crystal A are weighed, mixing is performed on the open mill, the rubber and the fillers are uniformly mixed, a sheet is extruded, and vulcanization is performed at 145°C to obtain a fluorescent natural rubber composite material (hereinafter referred to as NR-DMPAP-0.2).

[0031] Example 2

[0032] The preparation method of the fluorescent natural rubber composite material in the example is the same as that in the above-described example 1, except that the addition amount of the organic luminescent crystal A is different; and the addition amount of the organic luminescent crystal A in the fluorescent natural rubber composite material in the example is 0.6 g.

[0033] The method comprises the following steps: 100 g of raw rubber is plasticized on an open mill for 10 min, after uniform plasticization, 0.5 g of stearic acid, 5 g of zinc oxide, 0.7 g of accelerator M (2-mercaptobenzothiazole), 3 g of sulfur and 0.6 g of the organic luminescent crystal A are weighed, mixing is performed on the open mill, the rubber and the fillers are uniformly mixed, a sheet is extruded, and vulcanization is performed at 145°C to obtain a fluorescent natural rubber composite material (hereinafter referred to as NR-DMPAP-0.6).

[0034] Example 3

[0035] The preparation method of the fluorescent natural rubber composite material of the present example is the same as that of the above Example 1, except that the addition amount of the organic luminescent crystal A. The addition amount of the organic luminescent crystal A of the fluorescent natural rubber composite material of the present example is 1 g.

[0036] The preparation method of the fluorescent natural rubber composite material of the present example is the same as that of the above Example 1, except that the addition amount of the organic luminescent crystal A. The addition amount of the organic luminescent crystal A of the fluorescent natural rubber composite material of the present example is 1 g.

[0037] Example 4

[0038] The preparation method of the fluorescent natural rubber composite material of the present example is the same as that of the above Example 1, except that the addition amount of the organic luminescent crystal A. The addition amount of the organic luminescent crystal A of the fluorescent natural rubber composite material of the present example is 2 g.

[0039] The preparation method of the fluorescent natural rubber composite material of the present example is the same as that of the above Example 1, except that the addition amount of the organic luminescent crystal A. The addition amount of the organic luminescent crystal A of the fluorescent natural rubber composite material of the present example is 2 g.

[0040] Example 5

[0041] (1) Preparation of organic luminescent crystal B

[0042] The preparation method of the fluorescent natural rubber composite material of the present example is the same as that of the above Example 1, except that the addition amount of the organic luminescent crystal A. The addition amount of the organic luminescent crystal A of the fluorescent natural rubber composite material of the present example is 2 g.

[0043] The chemical reaction formula is as follows:

[0044]

[0045] (2) Preparation of fluorescent natural rubber composite material

[0046] The preparation method of the fluorescent natural rubber composite material of the example comprises the following steps: 100 g of raw rubber is plasticized on an open mill for 10 min, after uniform plasticization, 0.5 g of stearic acid, 5 g of zinc oxide, 0.7 g of accelerator M (2-mercaptobenzothiazole), 3 g of sulfur, and 0.2 g of organic luminescent crystal B are weighed, mixing is performed on the open mill to uniformly mix the rubber and the fillers, a sheet is calendared, and vulcanization is performed at 145 DEG C to obtain the fluorescent natural rubber composite material (hereinafter referred to as NR-AMPRL-0.2).

[0047] Example 6

[0048] The preparation method of the fluorescent natural rubber composite material of the example is the same as that of the above example 5, except that the addition amount of the organic luminescent crystal B, and the addition amount of the organic luminescent crystal B of the fluorescent natural rubber composite material of the example is 0.6 g.

[0049] The preparation method of the fluorescent natural rubber composite material of the example comprises the following steps: 100 g of raw rubber is plasticized on an open mill for 10 min, after uniform plasticization, 0.5 g of stearic acid, 5 g of zinc oxide, 0.7 g of accelerator M (2-mercaptobenzothiazole), 3 g of sulfur, and 0.6 g of organic luminescent crystal A are weighed, mixing is performed on the open mill to uniformly mix the rubber and the fillers, a sheet is calendared, and vulcanization is performed at 145 DEG C to obtain the fluorescent natural rubber composite material (hereinafter referred to as NR-AMPRL-0.6).

[0050] Example 7

[0051] The preparation method of the fluorescent natural rubber composite material of the example is the same as that of the above example 5, except that the addition amount of the organic luminescent crystal B, and the addition amount of the organic luminescent crystal B of the fluorescent natural rubber composite material of the example is 1 g.

[0052] The preparation method of the fluorescent natural rubber composite material of the example comprises the following steps: 100 g of raw rubber is plasticized on an open mill for 10 min, after uniform plasticization, 0.5 g of stearic acid, 5 g of zinc oxide, 0.7 g of accelerator M (2-mercaptobenzothiazole), 3 g of sulfur, and 1 g of organic luminescent crystal B are weighed, mixing is performed on the open mill to uniformly mix the rubber and the fillers, a sheet is calendared, and vulcanization is performed at 145 DEG C to obtain the fluorescent natural rubber composite material (hereinafter referred to as NR-AMPRL-1).

[0053] Example 8

[0054] The preparation method of the fluorescent natural rubber composite material of the example is the same as that of the above example 5, except that the addition amount of the organic luminescent crystal B, and the addition amount of the organic luminescent crystal B of the fluorescent natural rubber composite material of the example is 2 g.

[0055] The process includes the following steps: Plasticizing 100g of raw rubber on a two-roll mill for 10 minutes until it is uniformly plasticized, then weighing out 0.5g of stearic acid, 5g of zinc oxide, 0.7g of accelerator M (2-mercaptobenzothiazole), 3g of sulfur, and 2g of organic luminescent crystal B, and mixing them on a two-roll mill to ensure uniform mixing of the rubber compound and filler, calendering the compound into sheets, and vulcanizing at 145℃ to obtain a fluorescent natural rubber composite material (hereinafter referred to as NR-AMPRL-2).

[0056] Comparative Example 1

[0057] A natural rubber composite material, compared with Example 1, does not contain organic light-emitting crystal A in this comparative example. The preparation method includes the following steps: 100g of raw rubber is plasticized on a two-roll mill for 10 minutes. After plasticizing evenly, 0.5g of stearic acid, 5g of zinc oxide, 0.7g of accelerator M (2-mercaptobenzothiazole), and 3g of sulfur are weighed out and mixed on a two-roll mill to make the rubber compound and filler evenly mixed. The mixture is then calendered and vulcanized at 145°C to obtain the natural rubber composite material (hereinafter referred to as NR).

[0058] Comparative Example 2

[0059] A fluorescent natural rubber composite material, compared with Example 1, differs in the amount of organic light-emitting crystal A added, which is 5g.

[0060] The process includes the following steps: Plasticizing 100g of raw rubber on a two-roll mill for 10 minutes until it is uniformly plasticized, then weighing out 0.5g of stearic acid, 5g of zinc oxide, 0.7g of accelerator M (2-mercaptobenzothiazole), 3g of sulfur, and 5g of organic luminescent crystal A, and mixing them on a two-roll mill to ensure uniform mixing of the rubber compound and filler, calendering the compound into sheets, and vulcanizing at 145℃ to obtain a fluorescent natural rubber composite material (hereinafter referred to as NR-DMPAP-5).

[0061] Performance testing

[0062] (I) Fluorescence performance detection

[0063] The DMPAP, NR-DMPAP-0.2, NR-DMPAP-0.6, NR-DMPAP-1, and NR-DMPAP-2 prepared in Examples 1-4 were subjected to fluorescence spectroscopy and fluorescence quantum efficiency tests at different positions (the experimental results are not affected by position). The results are as follows: Figure 1 As shown, from Figure 1 It can be seen that the amount of DMPAP added has no effect on the fluorescence properties of NR, indicating that DMPAP can endow NR with fluorescence properties, and the amount added has little effect on the fluorescence intensity.

[0064] (II) Tensile Strength Test

[0065] The NR-DMPAP-0.2, NR-DMPAP-0.6, NR-DMPAP-1, and NR-DMPAP-2 prepared in Examples 1-4, the NR prepared in Comparative Example 1, and the NR-DMPAP-5 prepared in Comparative Example 2 were tested using a universal tensile testing machine. The rubber was cut into dumbbell-shaped specimens with a center dimension of 25mm × 6mm × 1mm along the calendering direction. Stress-strain curves were tested at room temperature with a tensile rate of 500mm / min, referring to the standard GB / T528-2009. The results are as follows. Figure 2 As shown in Figure (a), Figure 2 Figure (a) shows the stress-strain curve. The tensile strength test results are obtained by testing the stress-strain curve, and the results are as follows: Figure 2 As shown in Figure (b) of the document.

[0066] Depend on Figure 2 As shown in Figure (b), the original tensile strength of NR without any luminescent material is 17.57 MPa. When different amounts of DMPAP are added to NR, the overall tensile strength of NR first increases and then decreases with the increase of DMPAP addition. When 0.6 phr of DMPAP is added to NR, the tensile strength reaches the maximum value of 22.65 MPa. When 5 phr of DMPAP is added to NR, the tensile strength decreases to 14.58 MPa. This indicates that the amount of DMPAP added must be within an appropriate range. Exceeding this range will lead to a decrease in the tensile strength of NR.

[0067] (III) Fracture Energy Test

[0068] The NR-DMPAP-0.2, NR-DMPAP-0.6, NR-DMPAP-1, and NR-DMPAP-2 prepared in Examples 1-4, the NR prepared in Comparative Example 1, and the NR-DMPAP-5 prepared in Comparative Example 2 were subjected to fracture energy tests using a universal tensile tester. The fracture tests were conducted at room temperature with a tensile rate of 6 mm / min. The samples were rectangular specimens of 20 mm × 4 mm × 1 mm. Before the test, a 1 mm long edge notch was pre-set in the middle of the specimen. The fracture energy (Gc) was calculated using the following formula:

[0069]

[0070] The results are as follows Figure 3 As shown, by Figure 3 As shown in Figure (a), the original fracture energy of NR without any luminescent material is 31.0 KJ / m. 2When different amounts of DMPAP are added to the NR, the elongation at break of the NR shows a trend of first increasing and then decreasing with the increase of the amount of DMPAP added, indicating that the NR after adding DMPAP has good toughness, and when 0.6 phr of DMPAP is added to the NR, the breaking energy is 36.2 KJ / m 2 , indicating that only when a certain amount of DMPAP is added can the breaking energy of the NR be improved, and when the amount exceeds this amount, the breaking energy of the NR will decrease. As can be seen from the (b) graph in Figure 3 , when different amounts of DMPAP are added to the NR, the average molecular weight of the NR shows a trend of first decreasing and then increasing with the increase of the amount of DMPAP added, indicating that the crosslinking density of the NR first increases and then decreases with the increase of the amount of DMPAP added, that is, the breaking energy first increases to a certain extent and then decreases with the increase of the amount of DMPAP added.

[0071] (Four) Wear Resistance Test

[0072] The NR-DMPAP-0.2, NR-DMPAP-0.6, NR-DMPAP-1, NR-DMPAP-2 prepared in Examples 1-4, the NR prepared in Comparative Example 1, and the NR-DMPAP-5 prepared in Comparative Example 2 were respectively tested by using an Akron Abrasion Machine JZ-6041, the rubber wheel shaft rotation speed was 76 r / min, the grinding wheel shaft rotation speed was 35 r / min, the density was determined according to GB / T 1689-2014, and the abrasion volume was calculated. The friction coefficient was measured by using a UMT series multifunctional material mechanics testing system, the applied force was 0.3 N, the test time was 1800 s, and the number of laps was 100 laps. The friction coefficient is shown in the (a) graph of Figure 4 , and the abrasion volume is shown in the (b) graph of Figure 4 .

[0073] As can be seen from the (a) graph in Figure 4 , the friction coefficient of the NR without any luminescent substance is lower than that of the NR added with the luminescent substance DMPAP, indicating that the addition of DMPAP to the NR can improve the hardness of the NR, thereby improving the wear resistance of the NR.

[0074] As can be seen from the (b) graph in Figure 4 , when different amounts of DMPAP are added to the NR, the abrasion volume of the NR shows a trend of first decreasing and then increasing with the increase of the amount of DMPAP added, and the original abrasion volume of the NR without any luminescent substance is 1.7 cm 3Adding DMPAP to non-woven fabrics (NRs) improves their overall wear resistance, resulting in excellent abrasion resistance. Specifically, adding 1 phr of DMPAP reduces the wear rate to only 0.4 cm. 3 It has the lowest wear rate among all the added amounts.

[0075] (V) Hardness Test

[0076] The NR-AMPRL-0.2, NR-AMPRL-0.6, NR-AMPRL-1, and NR-AMPRL-2 prepared in Examples 5-8, and the NR prepared in Comparative Example 1, were tested for hardness using a Shore A hardness tester. The test standard was GB / T 531 "Test Method for Shore A Hardness of Vulcanized Rubber". The measuring force was 0.55 N. An indenter with a preset load was pressed into the sample surface within a specified time. The maximum force during the measurement process was taken as the hardness value. The results are as follows: Figure 5 As shown.

[0077] Depend on Figure 5 It can be seen that the hardness of NR without any luminescent material is 47 Shore A. However, after adding the luminescent material AMPRL, the overall hardness of NR is significantly improved. Furthermore, the hardness gradually increases with the increase of AMPRL addition, indicating that the addition of AMPRL can improve the overall hardness of NR, giving NR good wear resistance.

[0078] Although the present invention has been described using the above preferred embodiments, it is not intended to limit the scope of protection of the present invention. Any changes and modifications made by those skilled in the art to the above embodiments without departing from the spirit and scope of the present invention shall still fall within the scope of protection of the present invention.

Claims

1. A fluorescent natural rubber composite material, characterized by, The raw materials include the following parts by weight: natural rubber 100 parts, stearic acid 0.1-1 part, zinc oxide 2-7 parts, accelerator M 0.3-1.2 parts, sulfur 1-6 parts, and organic luminescent crystal 0.1-2 parts; the organic luminescent crystal is organic luminescent crystal A or organic luminescent crystal B; The preparation process of the organic luminescent crystal A includes the following steps: 2,5-dimethoxy acyl-1,4-cyclohexanedione is dissolved in methanol to obtain a suspension, n-pentylamine is added to the suspension, and stirring is performed to obtain a mixed solution; the mixed solution is cooled, filtered, and concentrated to obtain a red powder; the red powder is dissolved in a solvent, and the solvent diffusion method is used to culture the organic luminescent crystal A, which is 2,5-di(pentylamine)-1,4-terephthalic acid dimethyl ester; The preparation process of the organic luminescent crystal B includes the following steps: 2,5-dimethoxy acyl-1,4-cyclohexanedione is dissolved in methanol to obtain a suspension, 3-amino-1-propanol is added to the suspension, and stirring is performed to obtain a mixed solution; the mixed solution is cooled, filtered, and concentrated to obtain a red powder; the red powder is dissolved in an organic solvent, and the solvent diffusion method is used to culture the organic luminescent crystal B, which is 2,5-dipropylamine-1,4-terephthalic acid dimethyl ester.

2. The fluorescent natural rubber composite material according to claim 1, characterized by, The mass ratio of the 2,5-dimethoxy acyl-1,4-cyclohexanedione to the n-pentylamine is 1:3-4.

3. The fluorescent natural rubber composite material according to claim 1, characterized by, The mass ratio of the 2,5-dimethoxy acyl-1,4-cyclohexanedione to the 3-amino-1-propanol is 1:3-4.

4. The fluorescent natural rubber composite material according to claim 1, characterized by, The organic solvent is a mixed solvent of dichloromethane and petroleum ether.

5. The fluorescent natural rubber composite material according to claim 1, characterized by, The organic solvent is a mixed solvent of methanol and cyclohexane.

6. The method for preparing the fluorescent natural rubber composite material according to claim 1, characterized in that, The method includes the following steps: The natural rubber, stearic acid, zinc oxide, accelerator M, sulfur, and organic luminescent crystal are mixed on an open mill to uniformly mix the rubber and fillers, and the mixture is calendered into a sheet, which is vulcanized at 120-150 DEG C to obtain a fluorescent natural rubber composite material.

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