Low-VOC (volatile organic compound) rubber sealing strip and preparation method thereof

Abstract

The invention discloses a low-VOC (volatile organic compound) rubber sealing strip and a preparation method thereof in the technical field of rubber sealing materials. The rubber sealing strip is prepared from the following raw materials in parts by weight: 100 parts of EPDM (Ethylene-Propylene-Diene Monomer) raw rubber, 6.2 to 9.5 parts of VOC (Volatile Organic Compound) collecting agent, 12 to 15 parts of toughening agent, 36 to 44 parts of reinforcing agent, 1.7 to 2.2 parts of vulcanizing agent, 1.1 to 1.4 parts of accelerant, 3.5 to 4.5 parts of active agent and 0.7 to 0.9 part of anti-aging agent, the VOC collecting agent is formed by carrying out substitution reaction on chloro-n-alkyl alcohol and diallylamine, carrying out ring-opening and ring-closing reaction on epoxy chloropropane to form terminal epoxy modification, and finally carrying out ring-opening grafting on an intermediate 2 and beta-cyclodextrin. The VOC collecting agent and the EPDM matrix are co-vulcanized, an induction-adsorption-constraint collecting effect is formed in a vulcanization network, and release of VOC is effectively inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber sealing materials, and in particular to a rubber sealing strip and a preparation method thereof. Background Art

[0002] Rubber sealing strips are widely used in automotive doors and windows, building curtain walls, and household appliances. Their core functions are to provide airtightness, watertightness, and sound insulation. However, during production and use, traditional rubber materials continuously release volatile organic compounds (VOCs). These VOCs primarily include benzene derivatives (toluene, xylene), aldehydes (formaldehyde, acetaldehyde), sulfur compounds (CS2), and small molecule alkanes. These substances, primarily derived from rubber materials and processing aids, cannot be completely avoided and are harmful to human health.

[0003] Existing technologies primarily reduce VOC emissions through the following methods: 1. Pre-treating rubber raw materials, such as applying negative pressure or baking to volatilize and remove as many VOC components as possible. Chemical modification techniques, such as hydrogenation, can also be used to remove volatile substances from some additives. These methods are costly and have limitations. 2. Adsorption-blending technologies can be used to introduce adsorbents, such as activated carbon and nanocarbon materials, into the rubber material to suppress VOC release through adsorption. While these methods are effective, these adsorbents can reduce the rubber's elasticity and toughness, exacerbate permanent deformation, and worsen sealing performance. These limitations of existing technologies have severely hampered the development of low-VOC rubber sealing materials. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a low-VOC rubber sealing strip and a preparation method thereof, which solve the problems in the background technology.

[0005] The object of the present invention is achieved as follows: A low-VOC rubber sealing strip comprises the following raw materials in parts by weight: 100 parts of EPDM raw rubber, 6.2-9.5 parts of VOC collector, 12-15 parts of toughening agent, 36-44 parts of reinforcing agent, 1.7-2.2 parts of vulcanizing agent, 1.1-1.4 parts of accelerator, 3.5-4.5 parts of active agent and 0.7-0.9 parts of antioxidant.

[0006] The VOC collector is prepared by the following method: Step A1: Mix diallylamine, chloroalkyl alcohol, and tetrahydrofuran, raise the temperature to 50-65°C, add triethylamine, and stir to react for 4.5-5.5 hours. After the reaction is completed, filter while hot to remove salt, and remove tetrahydrofuran by rotary evaporation to obtain intermediate 1; Preferably, the chlorinated n-alkyl alcohol is one of 6-chloro-1-hexanol and 10-chloro-1-decanol. When the carbon chain length is modified, it matches the solubility parameter of EPDM, which is conducive to uniform dispersion. The alkyl chain of this length has a good spacing effect, reducing the steric hindrance of the terminal double bond in the VOC collector and maintaining good terminal reactivity. Furthermore, the usage ratio of diallylamine, chloro-n-alkyl alcohol, triethylamine and tetrahydrofuran is 0.1 mol: 0.1 mol: 8-11 mL: 120-180 mL, and the chloro-n-alkyl alcohol and diallylamine undergo substitution reaction.

[0007] Step A2: Intermediate 1, epichlorohydrin, pyridine, and dioxane are mixed, heated to 40-50°C, stirred, and reacted for 1.2-1.6 hours. Then, sodium hydroxide is added and the temperature is raised to 80-100°C and the reaction is continued for 2.5-3 hours. After completion of the reaction, the dioxane is removed by rotary evaporation, and the salt is removed by filtration. The substrate is washed with water, the aqueous phase is separated, and dried to obtain Intermediate 2; Furthermore, the usage 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 and the terminal alcohol hydroxyl group of intermediate 1 are ring-opened, and then the ring is closed under the action of strong alkaline sodium hydroxide to form an epoxy end-capping.

[0008] Step A3: premix β-cyclodextrin, tetrabutylammonium bromide, and dimethyl sulfoxide, then add intermediate 2 and mix, heat to 110-120°C, stir, and react for 6-8 hours. After the reaction is complete, remove dimethyl sulfoxide by vacuum rotary evaporation to obtain a VOC collector; Furthermore, the usage ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10 g: 55-70 mmol: 15-20 mg: 90-100 mL, and intermediate 2 is ring-opening grafted onto the hydroxyl groups in the β-cyclodextrin molecule.

[0009] Preferably, the toughening agent is hydrogenated paraffin oil, which is refined to reduce the VOC content in the raw material.

[0010] Preferably, the vulcanizing agent is a compound of sulfur and dicumyl peroxide, which is beneficial to the full vulcanization of the VOC collector and the rubber matrix.

[0011] A method for preparing a low-VOC rubber sealing strip comprises the following steps: mixing EPDM raw rubber and a toughening agent once, then adding raw materials other than a vulcanizing agent for a second mixing, adding the vulcanizing agent after the rubber is discharged, thinning and sheeting, and then demolding and vulcanizing after compression molding to obtain a low-VOC rubber sealing strip.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a VOC scavenger based on an organic matrix, which can effectively reduce the release of VOCs by blending with a rubber material. The VOC scavenger is prepared by a substitution reaction of a chlorinated n-alkyl alcohol and a diallylamine to form an intermediate 1, and then an epichlorohydrin and the intermediate 1 are subjected to a ring-opening and ring-closing reaction to form an end-epoxy modification to form an intermediate 2, and finally the intermediate 2 is subjected to a ring-opening grafting with beta-cyclodextrin. The molecular periphery of the VOC scavenger is a multi-branched alkyl chain structure, which is highly matched with the solubility parameter of the EPDM matrix and is easy to form a molecular-level dispersion. During the vulcanization process, the terminal double bond of the VOC scavenger is cross-linked with the EPDM matrix to form a stable anchoring dispersion, which has little effect on the stability of the vulcanization network of the EPDM matrix and compensates for the introduction of heterogeneous components. The permanent deformation defects caused by this process can maintain the stable sealing performance of the sealing strip. During the synthesis of the VOC collector, after the β-cyclodextrin and intermediate 2 are opened, a circle of hydroxyl modification is formed toward the outer end of the ring molecule, and the inner ring is a carbon-hydrogen structure, thereby forming a bicyclic structure. Since the double bond of the tertiary amine end group of the VOC collector participates in the sulfur cross-linking network, a low-energy-barrier β-cyclodextrin cavity channel is formed between the cross-linking points, inducing the directional migration of VOC molecules into the cavity. In this process, the polar molecules fall into the hydrogen bond network of the outer ring hydroxyl group to form a stable coordination. After the non-polar molecules are absorbed into the inner cavity, they are locked by the CH-π effect and steric hindrance, thereby forming an induction-adsorption-binding capture effect on the VOC molecules, effectively inhibiting the release of VOCs. DETAILED DESCRIPTION

[0013] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0014] Example 1: Preparation of low-VOC rubber sealing strips, specifically as follows: (1) Preparation of VOC collector Step A1: Diallylamine, 6-chloro-1-hexanol, and tetrahydrofuran were mixed and heated to 50°C. Triethylamine was added and 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 salt, and tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0015] Step A2: Take intermediate 1, epichlorohydrin, pyridine and dioxane, mix them, heat to 40°C, stir and react for 1.6 hours, then add sodium hydroxide and heat to 80°C and continue to react for 3 hours. The amount 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 completed, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0016] Step A3: Premix β-cyclodextrin, tetrabutylammonium bromide, and dimethyl sulfoxide, then add intermediate 2 and mix. Heat to 110°C and stir to react for 8 hours. The dosage ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide, and dimethyl sulfoxide is 10 g:55 mmol:15 mg:90 mL. After the reaction is completed, dimethyl sulfoxide is removed by vacuum rotary evaporation to obtain a VOC collector.

[0017] (2) Preparation of rubber sealing strips The raw materials were prepared according to the following weight ratios: 100 parts of EPDM raw rubber, 1703P raw rubber; 6.2 parts of VOC collector, prepared in this embodiment; 15 parts of toughening agent, 6110 type raw material hydrogenated paraffin oil; 44 parts of reinforcing agent, 800 mesh carbon black; 1.7 parts of vulcanizing agent, sulfur and dicumyl peroxide were mixed in a weight ratio of 5:1; 1.3 parts of accelerator, TMTD; 3.5 parts of activator, zinc oxide and stearic acid were mixed in a weight ratio of 1:1; 0.7 parts of antioxidant, antioxidant RD was selected; Mix EPDM raw rubber and toughening agent and mix them once at 80℃, then continue to heat up to 120℃, add raw materials other than vulcanizer and mix them twice, after mixing is completed, discharge the rubber, add vulcanizer and thinly pass it through the sheet, mold the mixed rubber, demould it and send it into the vulcanizing kettle, vulcanize it at 180℃ for 25 minutes, and you will get the low VOC rubber sealing strip.

[0018] Example 2: Preparation of low-VOC rubber sealing strips, specifically as follows: (1) Preparation of VOC collector Step A1: Diallylamine, 6-chloro-1-hexanol, and tetrahydrofuran were mixed and heated to 55°C. Triethylamine was added and 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 salt, and tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0019] Step A2: Take intermediate 1, epichlorohydrin, pyridine and dioxane, mix them, heat to 40°C, stir and react for 1.5 hours, then add sodium hydroxide and heat to 85°C and continue to react for 3 hours. The amount 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 completed, remove dioxane by rotary evaporation, remove salt by filtration, wash the substrate with water, separate the aqueous phase and dry it to obtain intermediate 2.

[0020] Step A3: Premix β-cyclodextrin, tetrabutylammonium bromide, and dimethyl sulfoxide, then add intermediate 2 and mix. Heat to 110°C and stir to react for 7.5 hours. The dosage ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide, and dimethyl sulfoxide is 10 g:60 mmol:17 mg:90 mL. After the reaction is completed, dimethyl sulfoxide is removed by vacuum rotary evaporation to obtain a VOC collector.

[0021] (2) Preparation of rubber sealing strips The raw materials were prepared according to the following weight ratios: 100 parts of EPDM raw rubber, 1703P raw rubber was selected; 7.5 parts of VOC collector, which was prepared in this embodiment; 14 parts of toughening agent, 6110 type raw material hydrogenated paraffin oil was selected; 40 parts of reinforcing agent, 800 mesh carbon black was selected; 1.9 parts of vulcanizing agent, sulfur and dicumyl peroxide were mixed in a weight ratio of 5:1; 1.4 parts of accelerator, accelerator TMTD was selected; 3.8 parts of activating agent, zinc oxide and stearic acid were mixed in a weight ratio of 1:1; 0.7 parts of antioxidant, antioxidant RD was selected; Mix EPDM raw rubber and toughening agent and mix them once at 80℃, then continue to heat up to 120℃, add raw materials other than vulcanizer and mix them twice, after mixing is completed, discharge the rubber, add vulcanizer and thinly pass it through the sheet, mold the mixed rubber, demould it and send it into the vulcanizing kettle, vulcanize it at 180℃ for 25 minutes, and you will get the low VOC rubber sealing strip.

[0022] Example 3: Preparation of low-VOC rubber sealing strips, specifically as follows: (1) Preparation of VOC collector Step A1: Diallylamine, 10-chloro-1-decanol, and tetrahydrofuran were mixed and heated to 65°C. Triethylamine was added and stirred for 4.5 hours. The ratio of diallylamine, 10-chloro-1-decanol, 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 salt, and tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0023] Step A2: Take intermediate 1, epichlorohydrin, pyridine and dioxane, mix them, heat to 50°C and stir to react for 1.2 hours, then add sodium hydroxide and heat to 100°C and continue to react for 2.5 hours. The amount 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 completed, dioxane is removed by rotary evaporation, and the salt is removed by filtration. The substrate is washed with water, the aqueous phase is separated and dried to obtain intermediate 2.

[0024] Step A3: Premix β-cyclodextrin, tetrabutylammonium bromide, and dimethyl sulfoxide, then add intermediate 2 and mix. Heat to 120°C and stir to react for 6-8 hours. The dosage ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide, and dimethyl sulfoxide is 10 g:70 mmol:20 mg:100 mL. After the reaction is completed, dimethyl sulfoxide is removed by vacuum rotary evaporation to obtain a VOC collector.

[0025] (2) Preparation of rubber sealing strips The raw materials were prepared according to the following weight ratios: 100 parts of EPDM raw rubber, 1703P raw rubber; 8.5 parts of VOC collector, prepared in this embodiment; 12 parts of toughening agent, 6110 type hydrogenated paraffin oil; 38 parts of reinforcing agent, 800 mesh carbon black; 2 parts of vulcanizing agent, sulfur and dicumyl peroxide were mixed in a weight ratio of 5:1; 1.1 parts of accelerator, TMTD; 4.2 parts of activator, zinc oxide and stearic acid were mixed in a weight ratio of 1:1; 0.8 parts of antioxidant, antioxidant RD was selected; Mix EPDM raw rubber and toughening agent and mix them once at 80℃, then continue to heat up to 120℃, add raw materials other than vulcanizer and mix them twice, after mixing is completed, discharge the rubber, add vulcanizer and thinly pass it through the sheet, mold the mixed rubber, demould it and send it into the vulcanizing kettle, vulcanize it at 180℃ for 30 minutes, and you will get the low VOC rubber sealing strip.

[0026] Example 4: Preparation of low-VOC rubber sealing strips, specifically as follows: (1) Preparation of VOC collector Step A1: Diallylamine, 10-chloro-1-decanol, and tetrahydrofuran were mixed and heated to 60°C. Triethylamine was added and stirred for 5 h. The ratio of diallylamine, 10-chloro-1-decanol, 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 salt, and tetrahydrofuran was removed by rotary evaporation to obtain intermediate 1.

[0027] Step A2: Take intermediate 1, epichlorohydrin, pyridine and dioxane, mix them, heat to 50°C, stir and react for 1.5 hours, then add sodium hydroxide and heat to 90°C and continue to react for 3 hours. The amount 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 completed, remove dioxane by rotary evaporation, filter to remove salt, wash the substrate with water, separate the aqueous phase and dry to obtain intermediate 2.

[0028] Step A3: Premix β-cyclodextrin, tetrabutylammonium bromide, and dimethyl sulfoxide, then add intermediate 2 and mix. Heat to 120°C and stir to react for 6.5 hours. The dosage ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide, and dimethyl sulfoxide is 10 g:65 mmol:20 mg:100 mL. After the reaction is completed, dimethyl sulfoxide is removed by vacuum rotary evaporation to obtain a VOC collector.

[0029] (2) Preparation of rubber sealing strips The raw materials were prepared according to the following weight ratios: 100 parts of EPDM raw rubber, 1703P raw rubber material was selected; 9.5 parts of VOC collector, which was prepared in this embodiment; 13 parts of toughening agent, 6110 type raw material hydrogenated paraffin oil was selected; 36 parts of reinforcing agent, 800 mesh carbon black was selected; 2.2 parts of vulcanizing agent, sulfur and dicumyl peroxide were selected and used in a weight ratio of 5:1; 1.2 parts of accelerator, accelerator TMTD was selected; 4.5 parts of activating agent, zinc oxide and stearic acid were selected and used in a weight ratio of 1:1; 0.9 parts of antioxidant, antioxidant RD was selected; Mix EPDM raw rubber and toughening agent and mix them once at 80℃, then continue to heat up to 120℃, add raw materials other than vulcanizer and mix them twice, after mixing is completed, discharge the rubber, add vulcanizer and thinly pass it through the sheet, mold the mixed rubber, demould it and send it into the vulcanizing kettle, vulcanize it at 180℃ for 30 minutes, and you will get the low VOC rubber sealing strip.

[0030] Comparative Example 1: A blank control was set up, and the implementation process of Example 4 was specifically referred to, but no VOC collector was added, and the rest of the implementation process was exactly the same.

[0031] Comparative Example 2, referring to the implementation process of Example 4, the VOC collector was replaced with hydroxypropyl-β-cyclodextrin in equal amount, and the rest of the implementation process was exactly the same.

[0032] Comparative Example 3, referring to the implementation process of Example 4, the VOC collector was replaced with an equal amount of 200 mesh coconut shell activated carbon, and the rest of the implementation process was exactly the same.

[0033] Samples were taken from the rubber seals prepared as described above and tested for VOC emission according to ISO 12219-3:2012 at 65°C for 72 hours. Compression set was also tested according to GB / T 7759.1-2015 at 70°C for 24 hours. The specific test results are shown in Table 1. Table 1 As can be seen from the test results in Table 1, the introduction of the VOC collector in the embodiment reduces the release of VOCs, especially significantly reduces the styrene VOC component, and has a lower impact on the compression permanent deformation of the sealing strip, thereby maintaining the sealing stability of the sealing strip.

[0034] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0035] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A low VOC rubber sealing strip, characterized in that: The raw materials include the following in parts by weight: 100 parts of EPDM raw rubber, 6.2-9.5 parts of VOC collector, 12-15 parts of toughening agent, 36-44 parts of reinforcing agent, 1.7-2.2 parts of vulcanizing agent, 1.1-1.4 parts of accelerator, 3.5-4.5 parts of active agent and 0.7-0.9 parts of antioxidant; The VOC collector is prepared by the following method: Step A1: Mix diallylamine, n-alkyl chloride, and tetrahydrofuran, raise the temperature to 50-65°C, add triethylamine, and stir for 4.5-5.5 hours to prepare intermediate 1; Step A2: Intermediate 1, epichlorohydrin, pyridine and dioxane were mixed, heated to 40-50°C and stirred for reaction for 1.2-1.6 hours, then sodium hydroxide was added and the temperature was raised to 80-100°C and the reaction was continued for 2.5-3 hours to prepare Intermediate 2; Step A3: premix β-cyclodextrin, tetrabutylammonium bromide and dimethyl sulfoxide, add intermediate 2 and mix, heat to 110-120° C. and stir to react for 6-8 hours to prepare a VOC scavenger.

2. A low VOC rubber sealing strip according to claim 1, characterized in that: The chlorinated n-alkyl alcohol is one of 6-chloro-1-hexanol and 10-chloro-1-decanol.

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

4. A low VOC rubber sealing strip according to claim 3, characterized in that: The usage 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.

5. The low VOC rubber sealing strip according to claim 1, characterized in that: The usage ratio of β-cyclodextrin, intermediate 2, tetrabutylammonium bromide and dimethyl sulfoxide is 10 g: 55-70 mmol: 15-20 mg: 90-100 mL.

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

7. The low VOC rubber sealing strip according to claim 1, characterized in that: The vulcanizing agent is a compound of sulfur and dicumyl peroxide.

8. A method for preparing a low-VOC rubber sealing strip according to any one of claims 1 to 7, characterized in that: Specifically, EPDM raw rubber and toughening agent are added for primary mixing, and then raw materials other than vulcanizer are added for secondary mixing. After the glue is discharged, the vulcanizer is added to thin the strip and the sheet is removed. After compression molding, the strip is demolded and vulcanized to obtain a low-VOC rubber sealing strip.

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