Reinforced heat-resistant flame-retardant ABS (Acrylonitrile Butadiene Styrene) high polymer material

Abstract

The invention relates to a reinforced heat-resistant flame-retardant ABS high polymer material and a preparation method thereof. According to the material, an innovative modification technology is adopted, ABS resin reacts with a nitrogen-based compound, a stable cross-linked network structure is formed, and therefore the heat resistance and flame retardance of the material are remarkably improved. 1, 3, 5-triphenylbenzene which is a novel small organic molecule is also introduced, so that the high-temperature stability and the flame-retardant effect of the material are further enhanced. By adopting the preparation method, the obtained material shows excellent stability in a high-temperature environment, is good in flame retardant property and can effectively inhibit flame spreading. In addition, the material also has good mechanical properties and ultraviolet stability, is suitable for industrial application of high temperature and high fire risk, and has good environmental protection property and long-term stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, in particular to a reinforced heat-resistant and flame-retardant ABS high molecular material and a preparation method thereof. BACKGROUND

[0002] ABS is a widely used engineering plastic, which is often used to manufacture automobile parts, electronic device housings, household appliance housings, etc. due to its excellent mechanical properties, good processability and low cost. However, the traditional ABS material performs poorly in high temperature and fire environment, and its heat resistance and flame retardancy are far from meeting the requirements of high temperature or fire scene. When a fire occurs, ABS material is easy to burn and produce a large amount of toxic smoke, which not only increases the risk of fire, but also poses a threat to the environment and human health.

[0003] In order to solve the heat resistance and flame retardancy problems of ABS material, the existing technology usually improves its performance by adding flame retardants or modifying treatment. Common flame retardants such as halogen-based, phosphorus-based flame retardants, inorganic salts, etc. can decompose and generate protective film at high temperature, reducing flame spread. However, these traditional flame retardants often bring some problems. For example, halogen-based flame retardants may release toxic gases during combustion, which has adverse effects on the environment and human health; while phosphorus-based flame retardants may affect the mechanical properties of the material during long-term use, leading to a decline in its overall performance. In addition, the method of modifying ABS resin mainly depends on surface modification or adding inorganic fillers, but these methods cannot effectively improve the overall heat resistance and flame retardancy.

[0004] Although there are various technical solutions to improve the performance of ABS, they often only make progress in one aspect, such as only improving its heat resistance or flame retardancy, but it is difficult to balance the performance of both. The traditional modification method often uses common flame retardants or additives, which is difficult to completely solve the contradiction between flame retardant effect and environmental impact, and may affect the mechanical properties and stability of ABS during long-term use. Therefore, a new technical solution is urgently needed, which can improve the heat resistance and flame retardancy of ABS material at the same time through innovative modification method, while having good environmental friendliness and long-term stability. SUMMARY

[0005] In order to overcome the problems in the above background art, the purpose of the present application is to provide a kind of reinforced heat-resistant flame-retardant ABS polymer material and its preparation method, aiming at significantly improving the heat resistance and flame retardance of ABS material by innovative modification technology, while maintaining good mechanical properties and environmental adaptability.The present application adopts the reaction of ABS resin and nitrogen-based compound to form a stable cross-linked network structure, thereby enhancing its thermal stability and flame retardant performance.The present application also introduces 1,3,5-triphenylbenzene and other new organic small molecules to further improve the high temperature stability and flame retardant effect of the material.The present application uses this innovative modification technology, which can effectively improve the heat resistance and flame retardance of ABS, and avoid the negative impact of traditional flame retardants on the environment, with high environmental friendliness and long-term stability.The material is widely used in high-temperature and high-fire-risk industrial fields, and has significant application prospect.

[0006] The purpose of the present application can be realized by the following technical solutions: A kind of reinforced heat-resistant flame-retardant ABS polymer material, the polymer material comprises the following raw materials by weight: modified ABS base material 80-120 parts;1,3,5-triphenylbenzene 5-15 parts;Phosphoric acid triphenyl ester 3-7 parts;Siloxane modifier 2-5 parts;Ultraviolet absorber 0.5-2 parts;Light stabilizer 0.3-1 part;Wherein the modified ABS base material is by the reaction of ABS resin and 2,4,6-trichloro-1,3,5-triazine in solvent, nitrogen-based compound and styrene unit in ABS molecule occur covalent binding, form stable cross-linked network structure, thereby significantly improving its thermal stability and flame retardant performance.

[0007] Optionally, the modified ABS base material comprises the following raw materials by weight: ABS resin 80-120 parts;2,4,6-trichloro-1,3,5-triazine 5-15 parts;Ethyl acetate 20-30 parts;Antioxidant 1-3 parts;Stabilizer 0.5-2 parts;Toughening agent 3-5 parts;Rheological aid 0.5-2 parts;Wherein the antioxidant is mixed by diphenyl phosphonate and cycloalkene compound according to the mass ratio of 1:2;The stabilizer is mixed by nitride compound and ester compound according to the mass ratio of 1:1.5;The toughening agent is mixed by polyether compound and polyester compound according to the mass ratio of 1:3;The rheological aid is mixed by fluoride compound and organosilicon compound according to the mass ratio of 1:2.

[0008] Optionally, the preparation method of the modified ABS base material comprises the following steps: (1) ABS resin, 2,4,6-trichloro-1,3,5-triazine and ethyl acetate are added to the reactor, stirred uniformly, and reacted until nitrogen-based compound and styrene unit in ABS molecule occur covalent binding to form a modified film layer; (2) After the reaction of the modified film layer, cool to room temperature, add antioxidant, stabilizer, toughening agent and rheological aid, continue to stir evenly, get the final modified ABS base material.

[0009] Optionally, the reaction condition of step (1) is temperature 60-80℃, reaction time 2-4 hours.

[0010] Optionally, the siloxane modifier is mixed by silane compound and polyether alcohol according to the mass ratio of 1:2; the ultraviolet absorber is mixed by benzophenone compound and acrylate compound according to the mass ratio of 1:1.5; the light stabilizer is mixed by nitride light stabilizer and anti-ultraviolet compound according to the mass ratio of 1:2.

[0011] Optionally, a preparation method of a reinforced heat-resistant and flame-retardant ABS polymer material comprises the following steps: S1, the modified ABS base material, 1, 3, 5-triphenylbenzene, triphenyl phosphate, siloxane modifier, ultraviolet absorber and light stabilizer are added into the reactor according to the proportion, stirred evenly, reacted until all components are fully mixed and reacted to form a mixture; S2, cool the mixture after reaction to room temperature to obtain a reinforced heat-resistant and flame-retardant ABS polymer material.

[0012] Optionally, the reaction condition of step S1 is temperature 80-100℃, reaction time 2-4 hours.

[0013] The beneficial effects of the present application are: The cross-linked network structure formed by the reaction of nitrogen-based compounds and ABS resin significantly improves the heat resistance and flame retardant properties of ABS material, especially in high temperature and fire environment. At the same time, the introduction of 1, 3, 5-triphenylbenzene, a new organic small molecule, further enhances the high temperature stability of the material, avoids the environmental pollution problem that may be caused by traditional flame retardants, and improves the comprehensive performance and environmental protection of the material. The technology makes the material not only has excellent flame retardant effect, but also can maintain good mechanical properties in high temperature and fire conditions, and adapts to more demanding industrial application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0014] The present application will be further described below with reference to the accompanying drawings.

[0015] Figure 1 The preparation flow chart of the reinforced heat-resistant and flame-retardant ABS polymer material is shown in the figure. Figure 2 The performance test results of different proportion samples are compared in the figure. DETAILED DESCRIPTION

[0016] The application will be further described in connection with specific embodiments, but the application is not limited to the following embodiments, equivalent adjustments made without departing from the spirit and essence of the application should also be considered to fall within the scope of the application.

[0017] Example 1

[0018] The purpose of this example is to verify the performance of the prepared enhanced heat-resistant and flame-retardant ABS polymer material when using the upper limit value of the components, especially the improvement in heat resistance and flame retardancy.

[0019] Formulation: modified ABS base material 120 parts; 1,3,5-triphenylbenzene 15 parts; triphenyl phosphate 7 parts; siloxane modifier 5 parts; ultraviolet absorber 2 parts; light stabilizer 1 part; Steps: S1, preparation method of modified ABS base material: 120 parts of ABS resin, 15 parts of 2,4,6-trichloro-1,3,5-triazine and 30 parts of ethyl acetate were added to the reactor, stirred uniformly, and reacted until the nitrogen-containing compound and the styrene unit in the ABS molecule were covalently combined to form a modified film layer. The reaction conditions are temperature 80-100℃, reaction time 2-4 hours; S2, the modified film layer after reaction is cooled to room temperature, antioxidant, stabilizer, toughening agent and rheological aid are added, and continue to stir uniformly to obtain the final modified ABS base material; S3, the modified ABS base material, 15 parts of 1,3,5-triphenylbenzene, 7 parts of triphenyl phosphate, 5 parts of siloxane modifier, 2 parts of ultraviolet absorber and 1 part of light stabilizer are added to the reactor according to the ratio, stirred uniformly, and reacted until all components are fully mixed and reacted to form a uniform mixture. The reaction conditions are temperature 80-100℃, reaction time 2-4 hours; S4, the mixture after reaction is cooled to room temperature to obtain the enhanced heat-resistant and flame-retardant ABS polymer material; as Figure 1 shown.

[0020] Example 2

[0021] The purpose of this example is to verify the comprehensive performance of the prepared enhanced heat-resistant and flame-retardant ABS polymer material when using the intermediate value of the components, focusing on testing the flame-retardant effect and high-temperature stability of the material.

[0022] Formulation: modified ABS base material 100 parts; 1,3,5-triphenylbenzene 10 parts; triphenyl phosphate 5 parts; siloxane modifier 3 parts; ultraviolet absorber 1 part; light stabilizer 0.5 part; Steps: S1, preparation method of modified ABS base material: 100 parts of ABS resin, 10 parts of 2,4,6-trichloro-1,3,5-triazine and 25 parts of ethyl acetate are added into a reactor, stirred uniformly, and reacted until the nitrogen-based compound is covalently combined with the styrene units in the ABS molecules to form a modified film layer, the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S2, the modified film layer after reaction is cooled to room temperature, and antioxidants, stabilizers, toughening agents and rheological aids are added and stirred uniformly to obtain the final modified ABS base material; S3, the modified ABS base material, 10 parts of 1,3,5-triphenylbenzene, 5 parts of triphenyl phosphate, 3 parts of siloxane modifier, 1 part of ultraviolet absorber and 0.5 part of light stabilizer are added into a reactor according to the proportion, stirred uniformly, and reacted until all components are fully mixed and reacted to form a uniform mixture, the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S4, the mixture after reaction is cooled to room temperature to obtain the enhanced heat-resistant and flame-retardant ABS high polymer material.

[0023] Example 3

[0024] The purpose of this example is to verify the performance of the enhanced heat-resistant and flame-retardant ABS high polymer material prepared using the lower limit value of the components, especially in terms of material heat resistance and flame retardancy.

[0025] Formulation: modified ABS base material 80 parts; 1,3,5-triphenylbenzene 5 parts; triphenyl phosphate 3 parts; siloxane modifier 2 parts; ultraviolet absorber 0.5 parts; light stabilizer 0.3 parts; Steps: S1, the preparation method of the modified ABS base material: 80 parts of ABS resin, 5 parts of 2,4,6-trichloro-1,3,5-triazine and 20 parts of ethyl acetate are added into a reactor, stirred uniformly, and reacted until the nitrogen-based compound is covalently combined with the styrene units in the ABS molecules to form a modified film layer, the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S2, the modified film layer after reaction is cooled to room temperature, and antioxidants, stabilizers, toughening agents and rheological aids are added and stirred uniformly to obtain the final modified ABS base material; S3, the modified ABS base material, 5 parts of 1,3,5-triphenylbenzene, 3 parts of triphenyl phosphate, 2 parts of siloxane modifier, 0.5 parts of ultraviolet absorber and 0.3 parts of light stabilizer are added into a reactor according to the proportion, stirred uniformly, and reacted until all components are fully mixed and reacted to form a uniform mixture, the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S4, the mixture after reaction is cooled to room temperature to obtain the enhanced heat-resistant and flame-retardant ABS high polymer material.

[0026] Comparative Example 1: Purpose of the present comparative example 1: The present comparative example aims to verify the performance of the prepared heat-resistant and flame-retardant ABS polymer material without adding 1,3,5-triphenylbenzene, focusing on the difference in performance in terms of flame retardancy and high temperature resistance.

[0027] Formulation: 100 parts of modified ABS base material; 5 parts of triphenyl phosphate; 3 parts of siloxane modifier; 1 part of ultraviolet absorber; 0.5 parts of light stabilizer.

[0028] Steps: S1, preparation method of modified ABS base material: Add 100 parts of ABS resin, 10 parts of 2,4,6-trichloro-1,3,5-triazine and 25 parts of ethyl acetate into the reactor, stir uniformly, and react until the nitrogen-based compound covalently bonds with the styrene unit in the ABS molecule to form a modified film layer. The reaction conditions are temperature 80-100℃ and reaction time 2-4 hours; S2, cool the modified film layer after reaction to room temperature, add antioxidants, stabilizers, toughening agents and rheological aids, continue to stir uniformly, and obtain the final modified ABS base material; S3, add the modified ABS base material, 5 parts of triphenyl phosphate, 3 parts of siloxane modifier, 1 part of ultraviolet absorber and 0.5 parts of light stabilizer into the reactor according to the ratio, stir uniformly, and react until all components are fully mixed and form a uniform mixture. The reaction conditions are temperature 80-100℃ and reaction time 2-4 hours; S4, cool the mixture after reaction to room temperature to obtain the heat-resistant and flame-retardant ABS polymer material.

[0029] Comparative Example 2: Purpose of the present comparative example 2: The present comparative example aims to verify the performance of the prepared heat-resistant and flame-retardant ABS polymer material without adding triphenyl phosphate, focusing on the change in flame retardancy.

[0030] Formulation: 100 parts of modified ABS base material; 10 parts of 1,3,5-triphenylbenzene; 3 parts of siloxane modifier; 1 part of ultraviolet absorber; 0.5 parts of light stabilizer.

[0031] Steps: S1, preparation method of modified ABS base material: Add 100 parts of ABS resin, 10 parts of 2,4,6-trichloro-1,3,5-triazine and 25 parts of ethyl acetate into the reactor, stir uniformly, and react until the nitrogen-based compound covalently bonds with the styrene unit in the ABS molecule to form a modified film layer. The reaction conditions are temperature 80-100℃ and reaction time 2-4 hours; S2, cooling the modified film layer after reaction to room temperature, adding antioxidants, stabilizers, toughening agents and rheological aids, and continuing to stir uniformly to obtain the final modified ABS substrate; S3, adding the modified ABS substrate, 10 parts of 1,3,5-triphenylbenzene, 3 parts of siloxane modifier, 1 part of ultraviolet absorber and 0.5 parts of light stabilizer into the reactor in a proportioning manner, stirring uniformly, and reacting until all components are fully mixed and reacted to form a uniform mixture, with the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S4, cooling the mixture after reaction to room temperature to obtain the reinforced heat-resistant and flame-retardant ABS high polymer material.

[0032] Comparative Example 3: The purpose of this comparative example 3 is to verify the performance of the reinforced heat-resistant and flame-retardant ABS high polymer material prepared without adding 1,3,5-triphenylbenzene and triphenyl phosphate, with a focus on testing its heat resistance and flame retardancy.

[0033] Formulation: modified ABS substrate 100 parts; siloxane modifier 3 parts; ultraviolet absorber 1 part; light stabilizer 0.5 parts.

[0034] Steps: S1, preparation method of modified ABS substrate: adding 100 parts of ABS resin, 10 parts of 2,4,6-trichloro-1,3,5-triazine and 25 parts of ethyl acetate into the reactor, stirring uniformly, and reacting until the nitrogen-containing compound covalently bonds with the styrene units in the ABS molecules to form a modified film layer, with the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S2, cooling the modified film layer after reaction to room temperature, adding antioxidants, stabilizers, toughening agents and rheological aids, and continuing to stir uniformly to obtain the final modified ABS substrate; S3, adding the modified ABS substrate, 3 parts of siloxane modifier, 1 part of ultraviolet absorber and 0.5 parts of light stabilizer into the reactor in a proportioning manner, stirring uniformly, and reacting until all components are fully mixed and reacted to form a uniform mixture, with the reaction conditions being a temperature of 80-100℃ and a reaction time of 2-4 hours; S4, cooling the mixture after reaction to room temperature to obtain the reinforced heat-resistant and flame-retardant ABS high polymer material.

[0035] Performance test: 1. Heat resistance test To evaluate the heat resistance of the prepared reinforced heat-resistant flame-retardant ABS polymer material, the test sample was placed in an oven at a temperature of 150°C and continuously heated for 24 hours. After the test, the appearance change, mechanical property change and thermal stability of the sample were recorded. According to the performance change of the sample in high temperature environment, the heat resistance performance of the material was evaluated.

[0036] 2. Flame Retardant Performance Test The prepared material was tested according to the standard flame test method. During the test, the sample was placed under a standard flame, and the burning time, flame spread speed and residual carbonized part of the sample after burning were recorded. By evaluating the flame retardant effect of the material under the influence of the flame, the pros and cons of its flame retardant performance were judged. The self-extinguishing property and low smoke property of the material are important indicators to judge its flame retardant effect.

[0037] 3. Ultraviolet Stability Test To test the ultraviolet stability of the reinforced heat-resistant flame-retardant ABS polymer material, the sample was exposed to ultraviolet radiation environment, and artificial accelerated aging test was used, with an irradiation period of 200 hours. During the test, the appearance, color change and mechanical property changes of the material, such as tensile strength and elongation at break, were regularly detected. According to the ultraviolet aging resistance performance of the sample, its stability in long-term outdoor application was evaluated.

[0038] 4. Mechanical Property Test The mechanical properties of the prepared material were evaluated by tensile test and bending test. Under the standard sample size, tensile test was carried out using a universal material testing machine, and the tensile strength, elongation at break and elastic modulus of the sample were recorded. At the same time, three-point bending test was carried out to test the bending strength and bending modulus of the sample. Through these tests, it was evaluated whether the mechanical properties of the material met the requirements of industrial application.

[0039] Table 1 Performance Test Results Examples / Comparative Examples Heat resistance (%) Flame spread rate (cm / min) UV stability (%) Tensile strength (MPa) Example 1 95 4.2 97 45 Example 2 100 3.5 99 48 Example 3 92 4.0 95 42 Comparative Example 1 88 6.0 85 35 Comparative Example 2 85 6.5 82 30 Comparative Example 3 80 7.0 75 28 According to Table 1 and Figure 2 , Example 2 showed the best performance in all test items. Specifically, the heat resistance of Example 2 reached 100%, and after 24 hours in an environment of 150°C, the appearance of the material did not change, and the tensile strength remained unchanged, showing excellent high temperature stability. In the flame spread speed test, the flame spread speed of Example 2 was 3.5 cm / min, which was the slowest among all examples and comparative examples, indicating that it had excellent flame retardant performance. In the ultraviolet stability test, Example 2 did not change in appearance after 200 hours of ultraviolet irradiation, and the tensile strength only decreased by 1%, showing very excellent stability. In terms of mechanical properties, the tensile strength of Example 2 was 48 MPa, which was the highest among all examples and comparative examples, showing its superior mechanical properties.

[0040] Compared with Example 2, Example 1 shows better heat resistance and UV stability, but slightly worse heat resistance, with a 5% decrease in tensile strength. Example 3 performs poorly in all tests, especially in flame spread rate and tensile strength, which are significantly lower than Example 2 and Example 1, indicating deficiencies in flame retardancy and mechanical properties.

[0041] For Comparative Examples 1, 2 and 3, they all perform worse than Example 2 in various properties, especially in heat resistance, flame retardancy and mechanical properties. Comparative Example 1 has a heat resistance of 88%, a flame spread rate of 6.0 cm / min, a UV stability of 85%, and a tensile strength of 35 MPa, showing a significant performance decline. Comparative Examples 2 and 3 further decline in performance, with heat resistance, flame spread rate, UV stability and mechanical properties all inferior to the examples, especially Comparative Example 3, whose tensile strength drops to 28 MPa, far lower than the examples and Comparative Examples 1 and 2.

[0042] Example 2's reinforced heat-resistant and flame-retardant ABS polymer material performs best in overall performance. Especially in heat resistance, flame retardancy, UV stability and mechanical properties, it is significantly better than other examples and comparative examples. Example 2 not only has good stability in high temperature and UV environment, but also has excellent flame retardant effect and strong mechanical properties, meeting the high standard requirements of industrial applications for materials, thus having wide application prospects, especially suitable for high temperature and high fire risk scenarios.

Claims

1. A reinforced heat-resistant and flame-retardant ABS polymer material, characterized in that, The polymer material comprises the following raw materials in parts by weight: 80-120 parts of modified ABS substrate; 5-15 parts of 1,3,5-triphenylbenzene; 3-7 parts of triphenyl phosphate; 2-5 parts of siloxane modifier; 0.5-2 parts of ultraviolet absorber; and 0.3-1 parts of light stabilizer. The modified ABS substrate is formed by reacting ABS resin with 2,4,6-trichloro-1,3,5-triazine in a solvent, causing the nitrogen-based compound to covalently bond with the styrene units in the ABS molecule, forming a cross-linked network structure.

2. The enhanced heat-resistant and flame-retardant ABS polymer material according to claim 1, characterized in that, The modified ABS substrate comprises the following raw materials in parts by weight: 80-120 parts of ABS resin; 5-15 parts of 2,4,6-trichloro-1,3,5-triazine; 20-30 parts of ethyl acetate; 1-3 parts of antioxidant; 0.5-2 parts of stabilizer; 3-5 parts of toughening agent; and 0.5-2 parts of rheology modifier.

3. The enhanced heat-resistant and flame-retardant ABS polymer material according to claim 2, characterized in that, The antioxidant is a mixture of diphenylphosphonate and cyclic olefin compounds in a mass ratio of 1:2; the stabilizer is a mixture of nitride compounds and ester compounds in a mass ratio of 1:1.5; the toughening agent is a mixture of polyether compounds and polyester compounds in a mass ratio of 1:3; and the rheology modifier is a mixture of fluoride compounds and organosilicon compounds in a mass ratio of 1:

2.

4. A reinforced heat-resistant and flame-retardant ABS polymer material according to any one of claims 1-3, characterized in that, The method for preparing the modified ABS substrate includes the following steps: (1) Add ABS resin, 2,4,6-trichloro-1,3,5-triazine and ethyl acetate to the reactor, stir evenly, and react until the nitrogen compound covalently bonds with the styrene unit in the ABS molecule to form a modified film layer; (2) Cool the modified film layer after the reaction to room temperature, add antioxidant, stabilizer, toughening agent and rheology modifier, and continue to stir evenly to obtain the final modified ABS substrate.

5. The enhanced heat-resistant and flame-retardant ABS polymer material according to claim 4, characterized in that, The reaction conditions for step (1) are a temperature of 60-80°C and a reaction time of 2-4 hours.

6. The enhanced heat-resistant and flame-retardant ABS polymer material according to claim 1, characterized in that, The siloxane modifier is composed of a silane compound and a polyether alcohol in a mass ratio of 1:2; the ultraviolet absorber is composed of a benzophenone compound and an acrylate compound in a mass ratio of 1:1.5; and the light stabilizer is composed of a nitride light stabilizer and an anti-ultraviolet compound in a mass ratio of 1:

2.

7. A method for preparing a heat-resistant and flame-retardant ABS polymer material, wherein the heat-resistant and flame-retardant ABS polymer material is as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1, add the modified ABS substrate, 1,3,5-triphenylbenzene, triphenyl phosphate, siloxane modifier, ultraviolet absorber and light stabilizer into the reactor according to the ratio, stir evenly, and react until all components are fully mixed and react to form a mixture; S2, after the reaction mixture is cooled to room temperature, an enhanced heat-resistant and flame-retardant ABS polymer material is obtained.

8. The method for preparing an enhanced heat-resistant and flame-retardant ABS polymer material according to claim 1, characterized in that, The reaction conditions for step S1 are a temperature of 80–100°C and a reaction time of 2–4 hours.

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