Low voc rubber sealant and method of making same

Abstract

The application discloses a low-VOC rubber sealing strip and a preparation method thereof in the technical field of rubber sealing materials; the rubber sealing strip comprises the following raw materials according to weight parts: EPDM raw rubber 100 parts, VOC collector 6.2-9.5 parts, toughening agent 12-15 parts, reinforcing agent 36-44 parts, vulcanizing agent 1.7-2.2 parts, accelerator 1.1-1.4 parts, active agent 3.5-4.5 parts and anti-aging agent 0.7-0.9 parts; the VOC collector is formed through substitution reaction of chloro-n-alkyl alcohol and diallylamine, ring-opening and ring-closing reaction of epichlorohydrin, end-epoxy modification, and finally ring-opening grafting of intermediate 2 and beta cyclodextrin; the VOC collector is co-vulcanized with the EPDM matrix, and forms induced-adsorption-bonding collection effect in the vulcanization network, thereby effectively inhibiting the release of VOC.

Description

Technical Field

[0001] This invention relates to the field of rubber sealing materials technology, and in particular to a rubber sealing strip and its preparation method. Background Technology

[0002] Rubber sealing strips are widely used in automotive doors and windows, building curtain walls, and home appliances, with their core functions being to provide airtightness, watertightness, and sound insulation. However, traditional rubber materials continuously release volatile organic compounds (VOCs) during production and use, mainly including benzene compounds (toluene, xylene), aldehydes (formaldehyde, acetaldehyde), sulfur-containing compounds (CS2), and small molecule alkanes. These substances mainly originate from rubber materials and processing aids and cannot be completely avoided, but they are harmful to human health.

[0003] Existing technologies primarily reduce VOC release through the following methods: 1. Pre-treatment of rubber raw materials, such as negative pressure or baking, to volatilize and remove VOC components as much as possible; or chemical modification techniques, such as hydrogenation to remove volatile substances from additives. However, these methods are costly and have limitations. 2. Blending adsorption technology, introducing adsorbents such as activated carbon or nano-carbon materials into the rubber material to inhibit VOC release. This method is relatively effective, but these adsorbents reduce the elasticity and toughness of the rubber material, exacerbate permanent deformation, and deteriorate sealing performance. The limitations of existing technologies severely restrict the development of low-VOC rubber sealing materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a low-VOC rubber sealing strip and its preparation method, thus solving the problems in the background technology.

[0005] The objective of this invention is achieved as follows: a low-VOC rubber sealing strip, comprising the following raw materials in parts by weight:

[0006] 100 parts EPDM raw rubber, 6.2-9.5 parts VOC collector, 12-15 parts toughening agent, 36-44 parts reinforcing agent, 1.7-2.2 parts vulcanizing agent, 1.1-1.4 parts accelerator, 3.5-4.5 parts activator and 0.7-0.9 parts antioxidant.

[0007] The VOC collector is prepared by the following method:

[0008] Step A1: Mix diallylamine, chloroalkyl alcohol and tetrahydrofuran, heat to 50-65℃, add triethylamine and stir for 4.5-5.5h. After the reaction is complete, filter while hot to remove salt, and remove tetrahydrofuran by rotary evaporation to obtain intermediate 1.

[0009] Preferably, the chloroalkyl alcohol is one of 6-chloro-1-hexanol and 10-chloro-1-decanol. With this carbon chain length modification, it matches the solubility parameter of EPDM, which is conducive to uniform dispersion. The alkyl chain of this length has a good intervening effect, reduces the steric hindrance of the terminal double bond in the VOC collector, and maintains good end reactivity.

[0010] Furthermore, the ratio of diallylamine, chloroalkyl alcohol, triethylamine, and tetrahydrofuran is 0.1 mol: 0.1 mol: 8-11 mL: 120-180 mL, and the chloroalkyl alcohol reacts with diallylamine for substitution.

[0011] Step A2: Mix intermediate 1, epichlorohydrin, pyridine and dioxane, heat to 40-50℃ and stir for 1.2-1.6 h. Then add sodium hydroxide and heat to 80-100℃ and continue the reaction for 2.5-3 h. After the reaction is complete, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0012] Furthermore, the ratio of intermediate 1, epichlorohydrin, pyridine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 6-8 mL: 12-15 g: 150-200 mL. Epichlorohydrin ring-opens with the terminal alcohol hydroxyl group of intermediate 1, and then closes the ring under the action of strongly alkaline sodium hydroxide to form epoxy end-capping.

[0013] Step A3: Premix β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide, then add intermediate 2 and mix. Heat to 110-120℃ and stir for 6-8 hours. After the reaction is complete, remove dimethyl sulfoxide by rotary evaporation under reduced pressure to obtain VOC collector.

[0014] Furthermore, the ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide, and dimethyl sulfoxide is 10g:55-70mmol:15-20mg:90-100mL, and intermediate 2 is ring-opening grafted with the hydroxyl groups in the β-cyclodextrin molecule.

[0015] Preferably, the toughening agent is hydrogenated paraffin oil, which is refined to reduce the VOC content in the raw material.

[0016] Preferably, the vulcanizing agent is a combination of sulfur and dicumyl peroxide, which facilitates the full vulcanization of the VOC collector with the rubber matrix.

[0017] A method for preparing a low-VOC rubber sealing strip is as follows: EPDM raw rubber and toughening agent are added and mixed once, then raw materials other than vulcanizing agent are added and mixed a second time, after the rubber is discharged, vulcanizing agent is added, thin sheet is formed, molded and then demolded and vulcanized to obtain a low-VOC rubber sealing strip.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention discloses an organic-based VOC collector that effectively reduces VOC release through blending with rubber materials. The VOC collector is prepared by a substitution reaction of a chloroalkyl alcohol with diallylamine to form intermediate 1. Then, epichlorohydrin and intermediate 1 undergo ring-opening and ring-closing reactions to form terminal epoxy modification, resulting in intermediate 2. Finally, intermediate 2 is prepared by ring-opening grafting with β-cyclodextrin. The VOC collector has a multi-branched alkyl chain structure on its molecular periphery, which highly matches the solubility parameters of the EPDM matrix, facilitating molecular-level dispersion. During vulcanization, its terminal double bonds crosslink with the EPDM matrix, forming a stable anchored dispersion, minimizing its impact on the vulcanization network stability of the EPDM matrix and compensating for the introduction of heterogeneous components. This process eliminates permanent deformation defects and maintains the stable sealing performance of the sealing strip. During the synthesis of the VOC collector, after β-cyclodextrin and intermediate 2 undergo ring opening, a ring of hydroxyl groups is oriented towards the outer end of the ring molecule for modification. The inner ring is a hydrocarbon structure, which in turn forms a bicyclic structure. Since the double bond of the tertiary amine end group of the VOC collector participates in the sulfur crosslinking network, a low-energy barrier β-cyclodextrin cavity channel is formed between the crosslinking points, inducing VOC molecules to migrate directionally into the cavity. During this process, polar molecules are trapped in the hydrogen bond network of the outer ring hydroxyl group, forming a stable coordination. After nonpolar molecules are absorbed into the inner cavity, they are locked by CH-π action and steric hindrance, thus forming an induction-adsorption-binding collection effect on VOC molecules, effectively inhibiting the release of VOCs. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: Preparation of a low-VOC rubber sealing strip, as detailed below:

[0022] (1) Preparation of VOC collectors

[0023] Step A1: Diallylamine, 6-chloro-1-hexanol, and tetrahydrofuran were mixed and heated to 50°C. Triethylamine was added and the mixture was stirred for 5.5 hours. The ratio of diallylamine, 6-chloro-1-hexanol, triethylamine, and tetrahydrofuran was 0.1 mol: 0.1 mol: 8 mL: 120 mL. After the reaction was completed, the mixture was filtered while hot to remove the salt, and the tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0024] Step A2: Mix intermediate 1, epichlorohydrin, pyridine, and dioxane, heat to 40°C and stir for 1.6 h. Then add sodium hydroxide and heat to 80°C to continue the reaction for 3 h. The ratio of intermediate 1, epichlorohydrin, pyridine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 6 mL: 12 g: 150 mL. After the reaction is complete, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0025] Step A3: Take β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide premixed, then add intermediate 2 and mix. Heat to 110℃ and stir for 8 hours. The ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10g:55mmol:15mg:90mL. After the reaction is complete, remove dimethyl sulfoxide by rotary evaporation under reduced pressure to obtain VOC collector.

[0026] (2) Preparation of rubber sealing strip

[0027] The raw materials were prepared according to the following weight ratios: 100 parts EPDM raw rubber, using 1703P type raw rubber; 6.2 parts VOC collector, prepared in this embodiment; 15 parts toughening agent, using 6110 type hydrogenated paraffin oil; 44 parts reinforcing agent, using 800 mesh carbon black; 1.7 parts vulcanizing agent, using sulfur and dicumyl peroxide in a weight ratio of 5:1; 1.3 parts accelerator, using TMTD accelerator; 3.5 parts activator, using zinc oxide and stearic acid in a weight ratio of 1:1; and 0.7 parts antioxidant, using RD antioxidant.

[0028] EPDM raw rubber and toughening agent are added and mixed at 80°C for the first time. Then, the temperature is raised to 120°C, and raw materials other than vulcanizing agent are added for the second mixing. After the mixing is completed, the rubber is discharged, vulcanizing agent is added and sheeted out. The mixed rubber is then molded, demolded, and sent to a vulcanizing kettle. It is vulcanized at 180°C for 25 minutes to obtain a low VOC rubber sealing strip.

[0029] Example 2: Preparation of a low-VOC rubber sealing strip, as detailed below:

[0030] (1) Preparation of VOC collectors

[0031] Step A1: Diallylamine, 6-chloro-1-hexanol, and tetrahydrofuran were mixed and heated to 55°C. Triethylamine was added and the mixture was stirred for 5.2 hours. The ratio of diallylamine, 6-chloro-1-hexanol, triethylamine, and tetrahydrofuran was 0.1 mol: 0.1 mol: 9 mL: 130 mL. After the reaction was completed, the mixture was filtered while hot to remove the salt, and the tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0032] Step A2: Mix intermediate 1, epichlorohydrin, pyridine, and dioxane, heat to 40°C and stir for 1.5 h. Then add sodium hydroxide and heat to 85°C to continue the reaction for 3 h. The ratio of intermediate 1, epichlorohydrin, pyridine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 6 mL: 15 g: 170 mL. After the reaction is complete, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0033] Step A3: Take β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide premixed, then add intermediate 2 and mix. Heat to 110℃ and stir for 7.5h. The ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10g:60mmol:17mg:90mL. After the reaction is complete, remove dimethyl sulfoxide by rotary evaporation under reduced pressure to obtain VOC collector.

[0034] (2) Preparation of rubber sealing strip

[0035] The raw materials were prepared according to the following weight ratios: 100 parts EPDM raw rubber, using 1703P type raw rubber; 7.5 parts VOC collector, prepared in this embodiment; 14 parts toughening agent, using 6110 type hydrogenated paraffin oil; 40 parts reinforcing agent, using 800 mesh carbon black; 1.9 parts vulcanizing agent, using sulfur and dicumyl peroxide in a weight ratio of 5:1; 1.4 parts accelerator, using TMTD accelerator; 3.8 parts activator, using zinc oxide and stearic acid in a weight ratio of 1:1; and 0.7 parts antioxidant, using RD antioxidant.

[0036] EPDM raw rubber and toughening agent are added and mixed at 80°C for the first time. Then, the temperature is raised to 120°C, and raw materials other than vulcanizing agent are added for the second mixing. After the mixing is completed, the rubber is discharged, vulcanizing agent is added and sheeted out. The mixed rubber is then molded, demolded, and sent to a vulcanizing kettle. It is vulcanized at 180°C for 25 minutes to obtain a low VOC rubber sealing strip.

[0037] Example 3: Preparation of a low-VOC rubber sealing strip, as detailed below:

[0038] (1) Preparation of VOC collectors

[0039] Step A1: Diallylamine, 10-chloro-1-decyl alcohol and tetrahydrofuran were mixed and heated to 65°C. Triethylamine was added and the mixture was stirred for 4.5 h. The ratio of diallylamine, 10-chloro-1-decyl alcohol, triethylamine and tetrahydrofuran was 0.1 mol: 0.1 mol: 11 mL: 180 mL. After the reaction was completed, the mixture was filtered while hot to remove the salt and the tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0040] Step A2: Mix intermediate 1, epichlorohydrin, pyridine, and dioxane, heat to 50°C and stir for 1.2 h. Then add sodium hydroxide and heat to 100°C to continue the reaction for 2.5 h. The ratio of intermediate 1, epichlorohydrin, pyridine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 8 mL: 15 g: 200 mL. After the reaction is complete, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0041] Step A3: Take β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide premixed, then add intermediate 2 and mix. Heat to 120℃ and stir for 6-8 hours. The ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10g:70mmol:20mg:100mL. After the reaction is complete, remove dimethyl sulfoxide by rotary evaporation under reduced pressure to obtain VOC collector.

[0042] (2) Preparation of rubber sealing strip

[0043] The raw materials were prepared according to the following weight ratios: 100 parts EPDM raw rubber, using 1703P type raw rubber; 8.5 parts VOC collector, prepared in this embodiment; 12 parts toughening agent, using 6110 type hydrogenated paraffin oil; 38 parts reinforcing agent, using 800 mesh carbon black; 2 parts vulcanizing agent, using sulfur and dicumyl peroxide in a weight ratio of 5:1; 1.1 parts accelerator, using TMTD accelerator; 4.2 parts activator, using zinc oxide and stearic acid in a weight ratio of 1:1; and 0.8 parts antioxidant, using RD antioxidant.

[0044] EPDM raw rubber and toughening agent are added and mixed at 80°C for the first time. Then, the temperature is raised to 120°C, and raw materials other than vulcanizing agent are added for the second mixing. After the mixing is completed, the rubber is discharged, vulcanizing agent is added and sheeted out. The mixed rubber is then molded, demolded, and sent to a vulcanizing kettle. It is vulcanized at 180°C for 30 minutes to obtain a low VOC rubber sealing strip.

[0045] Example 4: Preparation of a low-VOC rubber sealing strip, as detailed below:

[0046] (1) Preparation of VOC collectors

[0047] Step A1: Diallylamine, 10-chloro-1-decyl alcohol and tetrahydrofuran were mixed and heated to 60°C. Triethylamine was added and the mixture was stirred for 5 hours. The ratio of diallylamine, 10-chloro-1-decyl alcohol, triethylamine and tetrahydrofuran was 0.1 mol: 0.1 mol: 10 mL: 160 mL. After the reaction was completed, the mixture was filtered while hot to remove the salt and the tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0048] Step A2: Mix intermediate 1, epichlorohydrin, pyridine, and dioxane, heat to 50°C and stir for 1.5 h. Then add sodium hydroxide and heat to 90°C to continue the reaction for 3 h. The ratio of intermediate 1, epichlorohydrin, pyridine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 7 mL: 14 g: 180 mL. After the reaction is complete, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0049] Step A3: Take β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide premixed, then add intermediate 2 and mix. Heat to 120℃ and stir for 6.5h. The ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10g:65mmol:20mg:100mL. After the reaction is complete, remove dimethyl sulfoxide by rotary evaporation under reduced pressure to obtain VOC collector.

[0050] (2) Preparation of rubber sealing strip

[0051] The raw materials were prepared according to the following weight ratios: 100 parts EPDM raw rubber, using 1703P type raw rubber; 9.5 parts VOC collector, prepared in this embodiment; 13 parts toughening agent, using 6110 type hydrogenated paraffin oil; 36 parts reinforcing agent, using 800 mesh carbon black; 2.2 parts vulcanizing agent, using sulfur and dicumyl peroxide in a weight ratio of 5:1; 1.2 parts accelerator, using TMTD accelerator; 4.5 parts activator, using zinc oxide and stearic acid in a weight ratio of 1:1; and 0.9 parts antioxidant, using RD antioxidant.

[0052] EPDM raw rubber and toughening agent are added and mixed at 80°C for the first time. Then, the temperature is raised to 120°C, and raw materials other than vulcanizing agent are added for the second mixing. After the mixing is completed, the rubber is discharged, vulcanizing agent is added and sheeted out. The mixed rubber is then molded, demolded, and sent to a vulcanizing kettle. It is vulcanized at 180°C for 30 minutes to obtain a low VOC rubber sealing strip.

[0053] Comparative Example 1: A blank control was set up. The implementation process was exactly the same as in Example 4, but without the addition of VOC collectors.

[0054] Comparative Example 2 follows the same procedure as Example 4, except that the VOC collector is replaced with an equal amount of hydroxypropyl-β-cyclodextrin, and the rest of the procedure is exactly the same.

[0055] Comparative Example 3 follows the same implementation process as Example 4, except that the VOC collector is replaced with an equal amount of 200-mesh coconut shell activated carbon, and the rest of the implementation process is exactly the same.

[0056] Samples were taken from the rubber sealing strips prepared above, and the VOC release content was tested according to ISO 12219-3:2012 standard at 65℃ for 72 hours; the compression set was tested according to GB / T 7759.1-2015 standard at 70℃ for 24 hours; the specific test results are shown in Table 1.

[0057] Table 1

[0058]

[0059] As shown in Table 1, the introduction of VOC collectors in the examples reduced the release of VOCs, especially the styrene VOC component, and had a lower impact on the compression set resistance of the sealing strip, thus maintaining the sealing stability of the sealing strip.

[0060] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A low-VOC rubber sealing strip, characterized in that, The ingredients, by weight, include the following: 100 parts EPDM raw rubber, 6.2-9.5 parts VOC collector, 12-15 parts toughening agent, 36-44 parts reinforcing agent, 1.7-2.2 parts vulcanizing agent, 1.1-1.4 parts accelerator, 3.5-4.5 parts activator, and 0.7-0.9 parts antioxidant; The VOC collector is prepared by the following method: Step A1: Mix diallylamine, chloroalkyl alcohol and tetrahydrofuran, heat to 50-65℃, add triethylamine and stir for 4.5-5.5 h to prepare intermediate 1; wherein, the chloroalkyl alcohol is one of 6-chloro-1-hexanol and 10-chloro-1-decanol; Step A2: Mix intermediate 1, epichlorohydrin, pyridine and dioxane, heat to 40-50℃ and stir for 1.2-1.6h, then add sodium hydroxide and heat to 80-100℃ and continue the reaction for 2.5-3h to prepare intermediate 2; Step A3: Premix β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide, then add intermediate 2 and mix. Heat to 110-120℃ and stir for 6-8 hours to prepare a VOC collector. The ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10g:55-70mmol:15-20mg:90-100mL.

2. The low-VOC rubber sealing strip according to claim 1, characterized in that, The ratio of diallylamine, chloroalkyl alcohol, triethylamine and tetrahydrofuran is 0.1 mol: 0.1 mol: 8-11 mL: 120-180 mL.

3. The low-VOC rubber sealing strip according to claim 2, characterized in that, The ratio of intermediate 1, epichlorohydrin, pyridine, sodium hydroxide and dioxane is 0.1 mol: 0.1 mol: 6-8 mL: 12-15 g: 150-200 mL.

4. The low-VOC rubber sealing strip according to claim 1, characterized in that, The toughening agent is hydrogenated paraffin oil.

5. A low-VOC rubber sealing strip according to claim 1, characterized in that, The vulcanizing agent is a combination of sulfur and dicumyl peroxide.

6. A method for preparing a low-VOC rubber sealing strip according to any one of claims 1-5, characterized in that, Specifically, the process involves: mixing EPDM raw rubber and toughening agent once, then adding raw materials other than vulcanizing agent for a second mixing, then adding vulcanizing agent after discharge, thinning and sheeting, molding, and then demolding and vulcanizing to obtain a low-VOC rubber sealing strip.

Images