CN115260663B

CN115260663B - Environment-friendly low-odor sealing strip and preparation method thereof

Info

Publication number: CN115260663B
Application number: CN202210963415.3A
Authority: CN
Inventors: 连千荣
Original assignee: Ningbo Ekm New Material Co ltd
Current assignee: Ningbo Ekm New Material Co ltd
Priority date: 2022-08-11
Filing date: 2022-08-11
Publication date: 2023-06-16
Anticipated expiration: 2042-08-11
Also published as: CN115260663A

Abstract

The application relates to the technical field of rubber, in particular to an environment-friendly low-odor sealing strip and a preparation method thereof. The environment-friendly low-odor sealing strip comprises the following components in parts by weight: 60-70 parts of clean carbon black, 40-50 parts of calcium carbonate, 40-50 parts of diatomite, 1-3 parts of PEG-4000, 80-90 parts of paraffin oil, 5-10 parts of active zinc oxide, 1-3 parts of stearic acid, 0.5-2 parts of sulfur, 2-7 parts of nitrosamine-free accelerator, 0.1-0.5 part of scorch retarder, 5-10 parts of calcium oxide and 3-4 parts of foaming agent; the EPDM has an ENB content of 8.0 to 10.0wt%. According to the sealing strip, the step of stopping releasing smell is added when the mixed material glue is prepared by increasing the glue discharging temperature, and then the procedure of microwave vulcanization is matched, so that the prepared sealing strip has the effects of environmental protection and low smell.

Description

Environment-friendly low-odor sealing strip and preparation method thereof

Technical Field

The application relates to the technical field of rubber, in particular to an environment-friendly low-odor sealing strip and a preparation method thereof.

Background

The sealing strip mainly plays roles of sealing, dust prevention, water prevention, shock absorption, decoration and the like, and is widely applied to industries such as automobiles, home furnishings and the like. Wherein, the automobile sealing strip is mainly prepared by vulcanizing Ethylene Propylene Diene Monomer (EPDM).

Since EPDM itself uses a catalyst in the synthesis process, catalyst residue may cause VOC (volatile organic compound) to be generated from the produced sealing tape. When the VOC in the vehicle reaches a certain concentration, discomfort such as headache, nausea and the like can be caused in a short time; in cars with exceeding VOC for a long time, the lungs, livers, kidneys and nervous system are severely damaged. In addition, the traditional accelerators used for EPDM catalysis, such as ZDBC, DPTT, TMTD and other secondary amine accelerators, can generate nitrosamine in the rubber vulcanization process, and not only has the possibility of inducing cancers, but also can lead the prepared sealing strip to have stronger smell. Therefore, the control of the VOC content in automobiles is most essential from the raw materials.

However, the odor level and VOC content of the automobile sealing strips applied in the market are high, and as the environmental protection requirements of various host factories on the automobile interior materials are further enhanced, the automobile sealing strips in the market are difficult to meet the requirements.

Disclosure of Invention

The application provides an environment-friendly low-odor sealing strip and a preparation method thereof, wherein the sealing strip adopts EPDM with low catalyst residue, and components such as clean carbon black, a vulcanization system without nitrosamine and the like are used in a matching way, so that the production of irritant VOC small molecules and nitrosamine can be effectively reduced, and the environment-friendly low-odor sealing strip has the effects of environment friendliness and low odor.

In a first aspect, the application provides an environmental protection low odor sealing strip, comprising the following components added in parts by weight per 100 parts by weight of EPDM: 60-70 parts of clean carbon black, 40-50 parts of calcium carbonate, 40-50 parts of diatomite, 80-90 parts of PEG-40001-3 parts of paraffin oil, 5-10 parts of active zinc oxide, 1-3 parts of stearic acid, 0.5-2 parts of sulfur, 2-7 parts of nitrosamine-free accelerator, 0.1-0.5 part of scorch retarder, 5-10 parts of calcium oxide and 3-4 parts of foaming agent; the EPDM has an ENB content of 8.0 to 10.0wt%.

In the sealing strip, EPDM with the ENB content of 8.0-10.0wt% is selected, and the sealing strip is based on small ENB content and low rubber vulcanization speed, and the dosage of a sulfur system is required to be increased, so that the odor in the vulcanization reaction process can be increased; the ENB content is large, the rubber vulcanization speed is high, the consumption of a vulcanization system can be reduced, but the residual ENB also generates smell, so that the EPDM with proper ENB content needs to be selected.

On the basis, because excessive sulfur can generate more pungent smell, the application uses the non-nitrosamine accelerant to replace part of sulfur, which not only can reduce the generation of carcinogens such as nitrosamine and the like, but also can reduce the consumption of sulfur as much as possible and keep the same or similar vulcanization speed of the system. Calcium oxide is added in the method, and can effectively absorb nitrosamine formed by the sizing material in the vulcanization reaction, so that the nitrosamine content in the sealing strip is reduced.

Because the carbon black surface contains functional groups of hydrogen and oxygen, sulfur, tar and other impurities, the odor and VOC content can be influenced, and the quality of an extruded product can be seriously influenced by high impurity content; in addition, polycyclic aromatic hydrocarbon (ZEK) in the carbon black has carcinogenicity, and carbonyl, aldehyde and other oxidation groups in the carbon black pollute contacted matters or working media, and the extract content is large and can migrate to the surface of a product to cause defects such as surface color and the like; therefore, the clean carbon black is selected to effectively reduce the generation of the problems.

Diatomite can be used as a reinforcing agent and a deodorizing agent in the application, and volatile organic compounds are adsorbed by utilizing the porous structure of the diatomite, so that the smell of the diatomite is reduced.

In addition, the PEG-4000 added in the method can neutralize the acidity of the filler in the rubber, so that the vulcanization speed and the crosslinking density are increased, and the demolding of the rubber material is facilitated; the paraffin oil is used as a plasticizer, so that the mixing processability can be improved; zinc oxide and stearic acid are used as active agents, so that the fluidization speed and activity of the sizing material can be improved. The scorch retarder can prevent scorch from occurring in the vulcanization process of the sizing material; the foaming agent can expand and foam the rubber material, and increase the volume of the rubber material, so that the rubber material meets the performance requirement of the sealing strip.

In conclusion, the sealing strip disclosed by the application adopts the EPDM with low catalyst residue, and the components such as clean carbon black, a vulcanization system without nitrosamine and the like are matched, so that the production of irritant VOC small molecules and nitrosamine can be effectively reduced, and the sealing strip has the effects of environmental protection and low odor.

Preferably, the nitrosamine-free accelerator is selected from one or more of accelerator ZDTP, accelerator CLD, accelerator ZBEC, accelerator ZBPD, accelerator ZAT and accelerator MBT.

Preferably, the non-nitrosamine accelerant is added into 100 parts of EPDM by weight, namely 500.2-0.8 parts of accelerant ZDTP-800.5-1.4 parts of accelerant, 700.5-1.0 parts of accelerant ZBEC-500.8-1.5 parts of accelerant ZBPD-700.5-1.5 parts of accelerant and 2.0 parts of accelerant MBT-800.5.

By adopting the technical scheme, the accelerator ZDTP (zinc dialkyl dithiophosphate), the accelerator CLD (di-caprolactam disulfide), the accelerator ZBEC (zinc dibenzyldithiocarbamate), the accelerator ZBPD (O, O-zinc dibutyl dithiophosphate), the accelerator ZAT (zinc diamine dithiophosphate) and the accelerator MBT (2-mercaptobenzothiazole) are all environment-friendly accelerators, and can not generate cancerogenic substances such as nitrosamine in the rubber vulcanization process, thus being friendly to operators and environment and having the characteristics of environmental protection and low odor.

Wherein, the accelerator ZDTP, the accelerator ZBPD and the accelerator ZAT have synergistic effect with the accelerator MBT, and the accelerator CLD can replace partial sulfur and the carcinogenic and odorous accelerator DTDM (4, 4' -dithiodimorpholine) to achieve the same vulcanization degree, in the application, the non-nitrosamine accelerator is added according to the compounding of 100 parts of the EPDM, and the adhesive with good vulcanization degree is prepared by 500.2-0.8 parts of the accelerator ZDTP-0.8 parts, 1.4 parts of the accelerator CLD-800.5-1.4 parts, 700.5-1.0 parts of the accelerator ZBEC, 1.5-1.5 parts of the accelerator ZBPD-500.8, 700.5-1.5 parts of the accelerator MBT-800.5-2.0 parts, and the adhesive with good vulcanization degree is obtained, the residual quantity of the accelerator in the adhesive is reduced, the pungent odor in the production process of the sealing strip is reduced, and the odor of the sealing strip is further reduced, thus the adhesive is further preferable as the adhesive is used in the application.

Preferably, 8-15 parts of modified lignin base material is added to 100 parts of EPDM by weight, and hydroxyl-terminated silicone oil is adsorbed on the modified lignin base material.

By adopting the technical scheme, the modified lignin base material with the preset amount of adsorbed hydroxyl-terminated silicone oil is also added into the EPDM, wherein the hydroxyl-terminated silicone oil has reactivity under the high-temperature vulcanization of the later stage of rubber, and a part of the irritant VOC small molecules such as tertiary butyl alcohol, isopropanol, acetone and the like generated in the crosslinking process of the ethylene propylene diene monomer can react with the hydroxyl-terminated silicone oil, so that the VOC small molecules are grafted onto a siloxane molecular chain, and are further discharged through vacuumizing in the high-temperature vulcanization process; the hydroxyl-terminated silicone oil which is not discharged in time can be stably adsorbed by the modified lignin base material, so that the part of the hydroxyl-terminated silicone oil is prevented from exuding outwards when the sealing strip is used in the later period, and then VOC small molecules grafted onto a siloxane molecular chain are stably locked in the rubber, thereby effectively reducing the odor of the sealing strip.

On the basis, the modified lignin base material can effectively increase the compatibility of the modified lignin base material and ethylene propylene diene monomer rubber under the assistance of hydroxyl-terminated silicone oil, so that the mechanical property of the sealing strip can be effectively improved, and the anti-aging property of the sealing strip can be effectively improved.

Preferably, the adsorption amount of the hydroxyl-terminated silicone oil is 5-8wt% of the modified lignin base material.

By adopting the technical scheme, when mixing, excessive hydroxyl-terminated silicone oil is adsorbed to separate out the hydroxyl-terminated silicone oil from the modified lignin base material, so that bubbles are easily generated in rubber, but the adsorption amount of the hydroxyl-terminated silicone oil is too small, and the VOC removal effect is limited. Therefore, experiments prove that the hydroxyl-terminated silicone oil is suitable for the adsorption amount of 5-8wt%.

Preferably, the modified lignin base material is obtained by modifying alkali lignin-chitosan composite powder through organic siloxane hydrolysate.

By adopting the technical scheme, the alkali lignin is lignin extracted from plant tissues by alkali, has small relative molecular weight and weight average molecular weight of 2000-3000 (wood sulfonate is generally 20000-50000), and the lignin needs to be compounded with chitosan, so that the small-molecular alkali lignin is helpful for harvesting a compound with smaller molecular weight, and the worth of the compound powder is ensured to have good polydispersity in rubber;

the chitosan contains amino, acetamido and hydroxyl in the molecule, so the chitosan has relatively active properties and can be modified, activated and coupled. The alkali lignin contains hydroxymethyl which can react with active hydroxyl of the organic siloxane hydrolysate, so that the compounding of the alkali lignin and chitosan is realized. The alkali lignin modified by the chitosan has better reactivity, and the residual VOC is directly grafted on the modified lignin base material through the reaction of other active hydroxyl groups of the chitosan, so that the odor of the sealing strip is effectively reduced; the organic siloxane hydrolysate can modify the alkali lignin-chitosan composite powder, so that the prepared modified lignin base material can stably adsorb hydroxyl-terminated silicone oil.

In addition, after the alkali lignin and the chitosan are compounded and modified by the organic siloxane hydrolysate, the mechanical property of the rubber can be obviously improved, and meanwhile, the alkali lignin and the chitosan have good synergistic effect, and compared with the modified alkali lignin, the alkali lignin has better effects of reducing odor, reinforcing and resisting aging.

Preferably, the preparation steps of the modified lignin base material are as follows:

adding the alkali lignin-chitosan composite powder into the organic siloxane hydrolysate, heating to 60-70 ℃, rapidly stirring and reacting for 10-12 hours, cooling, collecting the precipitate, washing and drying to obtain the alkali lignin-chitosan composite powder.

By adopting the technical scheme, the alkali lignin-chitosan composite powder is firstly prepared into the composite liquid by using deionized water, so that the alkali lignin-chitosan composite powder can be fully dispersed with the organosiloxane hydrolysate, and the alkali lignin-chitosan composite powder can be modified as much as possible by reacting for 10-12 hours at 60-70 ℃.

Preferably, the preparation method of the alkali lignin-chitosan composite powder comprises the following steps:

dissolving alkali lignin in dioxane-water solution, dissolving chitosan in acetic acid-water solution, mixing the two solutions, adding glutaraldehyde for crosslinking, collecting precipitate, washing and stoving.

By adopting the technical scheme, the alkali lignin and the chitosan can be fully dissolved in the dioxane-water solution and the acetic acid-water solution correspondingly, and the mode of independently dissolving and then mixing is favorable for stably and uniformly dispersing the alkali lignin and the chitosan in a mixed system, and the glutaraldehyde is added at the moment to promote the effective combination of the alkali lignin and the chitosan, so that the method has the characteristics of simplicity in operation and good combination effect.

Preferably, the organic siloxane hydrolysate is prepared by dissolving a silane coupling agent in ethanol water solution to prepare an organic siloxane solution with the concentration of 2-5wt% and heating and hydrolyzing the organic siloxane solution.

By adopting the technical scheme, the silane coupling agent can be dissolved in ethanol water solution, and can be hydrolyzed in a heating mode, so that the silicon-oxygen bond of the silane coupling agent is broken to generate silicon hydroxyl, and the reactivity of the silane coupling agent is ensured. Wherein, the concentration of the silane coupling agent is kept between 2 and 5wt percent, so that the silane coupling agent can be hydrolyzed as much as possible, thereby obtaining more silicon hydroxyl groups so as to participate in the reaction.

In a second aspect, the present application provides a method for preparing an environment-friendly low-odor sealing strip, comprising the steps of:

preparing a rubber compound:

a section of: mixing the raw materials of sulfur removal, nitrosamine-free accelerator, scorch retarder, calcium oxide and foaming agent in the formula, discharging rubber at 155-165 ℃, and fully stopping releasing the smell to obtain master batch;

two sections: cooling, carrying out open mill, sequentially carrying out thin pass and roll wrapping on the masterbatch, adding sulfur, a nitrosamine-free accelerator, a scorch retarder, calcium oxide and a foaming agent after the glue layer is smooth, carrying out thin pass again, carrying out tablet cooling at 80-90 ℃, and fully stopping odor release to obtain a rubber compound; microwave vulcanization: and extruding the rubber compound together to obtain the sealing strip, vulcanizing by using two sections of microwaves, and cooling to obtain the environment-friendly low-odor sealing strip.

By adopting the technical scheme, the process in the processing process of the sizing material can also produce a certain influence on the smell of the sealing strip, and therefore, the sizing material adopts high temperature (155-165 ℃) to carry out the rubber discharge, so that a part of VOC is volatilized, sulfur and an accelerator are added during open mill, the temperature is controlled to be 80-90 ℃ for the lower part, the accelerator and the VOC in the sulfur are fully volatilized, and then the full stopping and smell releasing are carried out in the mixing of the first section and the second section, wherein the smell reduction degree is smaller after the first section is stopped and released for 8h or more, the smell reduction degree is smaller after the second section is stopped and released for 3 days or more, the full stopping and smell of the first section is stopped for 8h or more, and the full stopping and smell of the second section is stopped for 3 days or more. After sufficient standing, the odor of the small molecular substances in the sizing material can be emitted as much as possible. Finally, through a microwave vulcanization mode, on one hand, the rubber material can be heated uniformly and fully to be vulcanized, and on the other hand, the rubber material can be vacuumized in an extruder to discharge small molecular substances again, so that the prepared sealing strip has the characteristics of environmental protection, low odor, excellent mechanical property and excellent ageing resistance.

In summary, the present application has the following beneficial effects:

1. the sealing strip of the application adopts EPDM with low catalyst residue, and the components such as clean carbon black, a vulcanizing system without nitrosamine and the like are matched, so that the production of irritant VOC small molecules can be effectively reduced, nitrosamine is avoided, and the sealing strip has the effects of environmental protection and low odor.

2. According to the sealing strip, the modified lignin base material adsorbed with the hydroxyl-terminated silicone oil is added, so that the smell of the sealing strip can be further reduced, and the mechanical property and the ageing resistance of the sealing strip can be effectively improved.

3. According to the method, the step of stopping releasing smell is added when the mixed glue is prepared by increasing the glue discharging temperature, and then the process of microwave vulcanization is matched, so that the smell of the sealing strip is further reduced in the process.

Detailed Description

Raw materials

Ethylene propylene diene monomer rubber: the embodiment of the application is of the model Bayer EPDGMAP 341 (Mooney viscosity 70ML ₁₊₄ 125 ℃, ethylene 50wt%, ENB content 8.0wt%, langsheng EPDM 6950 (Mooney viscosity 65 ML) ₁₊₄ 125 ℃, ethylene 44.3wt%, ENB content 9.0wt%, ekksen EPDM 8800 (Mooney viscosity 73 ML) ₁₊₄ 125℃and 53.5wt% of ethylene and 10.0wt% of ENB are exemplified. Comparative example DuPont EPDM 4750 (door)Ni viscosity 70ML ₁₊₄ 125℃and 50% by weight of ethylene and 5.0% by weight of ENB are given as examples.

Clean carbon black: in the present application, SP5000 is taken as an example, and the particle size is 60nm, and the present invention can be used as clean carbon black such as natural gas carbon black N774 which meets the ZEK-01.4-08 environmental protection regulations.

Calcium carbonate: the calcium carbonate prepared by adopting a precipitation method is preferable, and the particle size is 0.5-6 mu m.

Diatomaceous earth: the preferred model of the present application is Silitin N85, siO ₂ More than or equal to 87 percent, can be other isoporous diatomite in addition, has certain adsorption effect on volatile organic compounds and reduces the odor of the volatile organic compounds.

PEG-4000: molecular weight 3600-4400, hydroxyl value 26-32mgKOH/g, and active ingredient content 99%.

Paraffin oil: the application preferably adopts white paraffin oil with high flash point (above 300 ℃), high viscosity, light color, high saturated hydrocarbon content and zero aromatic hydrocarbon content, and can volatilize small molecular substances to generate smell, and is specifically described by taking paraffin oil PW-3801 as an example.

Active zinc oxide (active ZnO): the present application is specifically described using organozinc S70 as an example.

Stearic acid: CAS number is 57-11-4, purity is more than or equal to 99%.

Sulfur: the present application is described with reference to S-80.

Nitrosamine-free accelerator: the application is one or more selected from accelerator ZDTP (zinc dialkyl dithiophosphate), accelerator CLD (dithiocaprolactam), accelerator ZBEC (zinc dibenzyldithiocarbamate), accelerator ZBPD (zinc O, O-dibutyl dithiophosphate), accelerator ZAT (zinc diamine dithiophosphate) and accelerator MBT (2-mercaptobenzothiazole). The accelerators are environment-friendly accelerators, cannot generate cancerogenic substances such as nitrosamine and the like in the rubber vulcanization process, are friendly to operators and environment, and have the characteristics of environment friendliness and low odor. The EPDM is matched with the added nitrosamine-free accelerator per 100 parts by weight, and comprises the accelerator ZDTP-500.5-2.5 parts, the accelerator CLD-800.5-1.0 parts, the accelerator ZBEC-700.5-2.0 parts, the accelerator ZBPD-500.5-2.0 parts, the accelerator ZAT-700.5-3.0 parts and the accelerator MBT-800.5-2.5 parts.

Scorch retarder: the present application preferably employs a rubber scorch retarder of type E-80.

Calcium oxide: caO-80 with a particle size of 6-10 μm is preferably used in the present application, which is advantageous for absorbing nitrosamines formed in the vulcanization reaction.

Foaming agent: the preferred low odor blowing agent OBSH-75 of the present application and the commercially available pre-dispersed rubber microsphere blowing agent (model HDU/GE) of this company are illustrated by way of example.

Alkali lignin: CAS number is 8068-05-1, and purity is more than or equal to 99%.

Preparation example of modified lignin base Material having hydroxyl-terminated fiber adsorbed thereon

Preparation example 1

The modified lignin base material adsorbed with hydroxyl-terminated fiber adopts the following raw materials which are all commercial products, and the preparation method specifically comprises the following steps:

(1) preparing alkali lignin-chitosan composite powder:

s1, dissolving 5 times of alkali lignin in 100 times of dioxane-water solution, wherein the volume ratio of dioxane to water is 9:1, centrifuging for 10min at 2000r/min, collecting centrifugate, dropwise adding diethyl ether into the centrifugate to obtain precipitate, washing and drying the precipitate to obtain purified alkali lignin;

s2, dissolving the purified alkali lignin in the same dioxane-water solution to prepare an alkali lignin solution with the concentration of 3 wt%;

s3, dissolving chitosan in acetic acid-water solution with the concentration of 2wt% to prepare chitosan solution with the concentration of 5 wt%;

s4, mixing the alkali lignin solution prepared in the step S2 and the chitosan solution prepared in the step S3 according to the volume ratio of 2:1, adding glutaraldehyde with the concentration of 0.3wt% for crosslinking, filtering and washing at room temperature, collecting precipitate, and drying in an infrared oven until the water content is less than or equal to 0.5%, thus obtaining the alkali lignin-chitosan composite powder.

(2) Preparing an organosiloxane hydrolysate:

s5, dissolving a silane coupling agent (specifically, 3-aminopropyl triethoxysilane is taken as an example and is also called KH 550) in an ethanol water solution (ethanol: water=80:20, mass ratio) to prepare an organosiloxane solution with the concentration of 2-5wt%, and heating to 50 ℃ while vigorously stirring to perform heat preservation treatment for 24 hours to prepare an organosiloxane hydrolysate by hydrolysis.

(3) Preparing a modified lignin base material:

s6, adding the alkali lignin-chitosan composite powder prepared in the step S4 into the organosiloxane hydrolysate prepared in the step S5 according to the weight ratio of 1:10, heating to 65 ℃ (allowing fluctuation in the range of 60-70 ℃), vigorously stirring to enable hydroxymethyl in the alkali lignin to react with active hydroxyl of the organosiloxane hydrolysate for 10 hours, naturally cooling the product to room temperature, filtering, washing with 95% ethanol, and drying at 120 ℃ for 12 hours to obtain the modified lignin base material.

(4) Adsorption of hydroxyl terminated silicone oils

S7, adding hydroxyl-terminated silicone oil (taking the model HY-2520 as an example, the hydroxyl value is 50-65mgKOH/g, the molecular weight is 2000, the viscosity is 30-60cp (25 ℃), the solid content is more than or equal to 97%) into the modified lignin base material, wherein the addition amount of the hydroxyl-terminated silicone oil is 5-8wt% of the modified lignin base material, specifically taking 6wt% as an example for preparation, heating to 40 ℃, stirring uniformly, and naturally cooling to room temperature to obtain the modified lignin base material adsorbed with the hydroxyl-terminated fibers.

PREPARATION EXAMPLES 2 to 4

The concentration of the organosiloxane solution in S5 was adjusted to 1wt% in preparation example 2, 2wt% in preparation example 3, and 5wt% in preparation example 4 on the basis of the method of preparation example 1.

Preparation examples 5 to 7

The adsorption amount of hydroxyl-terminated silicone oil in S7 was adjusted based on the method of preparation example 1, preparation example 5 was adjusted to 4wt%, preparation example 6 was adjusted to 5wt%, and preparation example 7 was adjusted to 8wt%.

The present application is described in further detail below in connection with examples and comparative examples.

Examples

Example 1

The preparation method of the environment-friendly low-odor sealing strip comprises the following steps:

(1) preparing components: 100kg of Bayer EPDGMAP 341 is weighed and matched with the following components in parts by weight: clean carbon black SP500060kg, precipitated calcium carbonate 40kg, diatomite Silitin N8540kg, PEG-40001kg, paraffin oil PW-380180kg, active ZnO 5kg, stearic acid 1kg, sulfur S-800.5kg, nitrosamine-free accelerator 7kg, scorch retarder E-800.1kg, caO-805kg, and foaming agent OBSH-753kg;

wherein, the nitrosamine-free accelerator is prepared by the following components by weight: accelerator ZDTP-500.6kg, accelerator CLD-801.1kg, accelerator ZBEC-701.0kg, accelerator ZBPD-501.3kg, accelerator ZAT-701.5kg, and accelerator MBT-801.5kg.

(2) Preparing a rubber compound:

a section of: adding raw materials for removing sulfur S-80, a nitrosamine-free accelerator and CaO-80 in a formula into an internal mixer for mixing, lifting a pressing weight for exhausting gas during the mixing process to volatilize a part of micromolecular organic matters, discharging rubber at 160 ℃ (fluctuation is allowed to be within the range of 155-165 ℃ and has little influence on the performance of the rubber material), and fully stopping the odor release after 8 hours to obtain the master batch;

two sections: cooling and placing the mixture on an open mill for open mill, firstly, thinning the masterbatch for 3 times, then wrapping the masterbatch with a roller, adding sulfur S-80 and a nitrosamine-free accelerator after the glue layer is smooth, thinning the masterbatch for 5 times again, carrying out open mill for 5 minutes, and carrying out sheet cooling at 85 ℃ (fluctuation is allowed to be within the range of 80-90 ℃, the influence on the performance of the sizing material is small), and fully stopping the odor release after 3 days to obtain a rubber compound;

(3) and (3) microwave vulcanization: and co-extruding the rubber compound into the sealing strip by adopting an extruder, wherein the extrusion speed is 15m/min, vulcanizing the sealing strip by using a two-section microwave vulcanizing oven with the vulcanizing microwave power of 2.0+/-0.5 KW and 3.0+/-0.5 KW respectively, and cooling to obtain the environment-friendly low-odor sealing strip.

Examples 2 to 4

Examples 2-4 the amounts of the components were adjusted on the basis of the procedure of example 1, see in particular Table I below.

Table-component batching Table (Unit: kg) of examples 1 to 4

	Example 1	Example 2	Example 3
				Bayer EPDMAP341	100	100	100
Clean carbon black SP5000	60	65	70
				Precipitation method of calcium carbonate	40	45	50
Diatomite SilitinN85	40	45	50
				PEG-4000	1	2	3
Paraffin oil PW-3801	80	85	90
				Active ZnO	5	6	10
Stearic acid	1	2	3
				S-80 sulfur	0.5	1.2	2
Promoter ZDTP-50	0.6	0.5	0.2
				Accelerator CLD-80	1.1	0.9	0.3
Accelerator ZBEC-70	1.0	0.8	0.3
				Accelerator ZBPD-50	1.3	1.0	0.4
Accelerator ZAT-70	1.5	1.2	0.4
				Accelerator MBT-80	1.5	1.2	0.4
Scorch retarder E-80	0.1	0.3	0.5
				CaO-80	5	7	10
Foaming agent OBSH-75	3	3.2	4

Examples 4 to 5

Examples 4-5 bayer EPDMAP341 was modified based on the method of example 2. Of these, example 4 uses a model Langshen EPDM 6950 and example 5 uses a model Exxon EPDM 8800.

Comparative example

Comparative example 1

This comparative example was based on the procedure of example 1, with 7kg of the non-nitrosamine accelerator being replaced by TMTD.

Comparative example 2

This comparative example replaces bayer EPDMAP341 with dupont EPDM 4750 based on the procedure of example 1.

Comparative example 3

This comparative example was based on the procedure of example 1, without the addition of diatomaceous earth.

Performance testing

The following performance measurements were carried out on the corresponding mixtures or sealing strips of examples 1 to 5 and comparative examples 1 to 3, and the results are shown in Table II below.

1. Scorch time T5: when the Mooney viscosity value of the large rotor is reduced to the lowest point, the time corresponding to the 5 Mooney viscosity values is increased. Specifically, a Mooney viscometer is adopted for measurement, the rubber compound is parked for 2 hours under laboratory conditions, the rubber compound is cut into samples with the diameter of 45mm and the thickness of 3mm, the diameter of a large rotor is 38.10 plus or minus 0.03mm, and the test temperature is 125 plus or minus 1 ℃. The scorching time is fast, which is helpful for the good appearance surface of the product and easy shaping, but the reaction is controlled improperly and the cooked glue is easy to appear. The slow scorching time is unfavorable for obtaining good appearance surface of the product, but is beneficial to prolonging the storage time of the rubber compound and the time for maintaining the rubber in a vulcanized state, and is convenient for vulcanizing the rubber material components at different positions, so the scorching time needs to be moderate.

2. Positive vulcanization time T90 (180 ℃,5 min): the time required for the torque of the rubber to rise from the lowest value by 90 units from the start of heating was measured by using a foam vulcanizer with a Uken's test for 8g of rubber compound. Wherein, the shorter the positive vulcanization time, the faster the vulcanization speed.

3. N-nitrosamine content/. Mu.g/kg): the measurement was performed by using a gas chromatograph-thermal analysis (GC-TEA). Capillary chromatography using CP-Wax58 (25 m 0.32mm 1.2 μm); gasification chamber temperature: the initial temperature is 50 ℃, kept for 1min, and then heated to 200 ℃ at a speed of 75 ℃/min; chromatographic column temperature: the initial temperature is 40 ℃, and then the temperature is increased to 230 ℃ at the speed of 14 ℃/min; the pyrolysis chamber temperature is 500 ℃, the coupling temperature is 200 ℃, the carrier gas is helium, and the flow rate is 2.5mL/min.

Crushing the sealing strip into particles with the particle diameter of less than 3mm, weighing 5.0g into a conical flask, adding 40mL of water, placing into a shaking water bath tank, shaking and leaching for 10min at 40 ℃, transferring the solution into a cylinder with a plug, washing a sample with 10mL of water, transferring the sample into the cylinder with the plug, precisely adding 1.0mL of sodium hydroxide (1 mol/L) to a scale of 50mL, shaking and homogenizing for at least 1min, collecting dichloromethane extract by using the conical flask filled with anhydrous sodium sulfate, repeating the steps for 2 times, concentrating the dichloromethane extract to 1mL in a nitrogen blowing instrument, transferring the sample into the sample bottle, and taking 1 mu L of sample solution for sample injection to measure the content of N-nitrosamine.

4. Odor rating: cutting 20g of sealing strips, placing the sealing strips in a constant-temperature oven with the temperature of 80+/-2 ℃ for 2 hours, taking out the sealing strips, cooling to the detection room temperature of 60+/-5 ℃ before evaluation, and evaluating 10 normal-smell test volunteers according to the definition of smell grade by each sealing strip to calculate the average value of the evaluation grade. If scores differ from each other by more than 2 points for a single evaluation, the number of test volunteers should be increased to 15 for repeated measurements. Wherein, the level 1 is odorless, the level 2 is audible but not disturbing, the level 3 is obviously audible but not objectionable, the level 4 is objectionable, the level 5 is strongly objectionable, and the level 6 is intolerable.

5. Tensile strength/MPa: the test is carried out according to the standard of GB/T528-2009 test for testing tensile stress and strain properties of vulcanized rubber or thermoplastic rubber, a dumbbell-shaped test sample is adopted, and a cutter is 1 type.

6. Tensile failure rate/%: the test is carried out according to the standard of GB/T528-2009 test for testing tensile stress and strain properties of vulcanized rubber or thermoplastic rubber, a dumbbell-shaped test sample is adopted, and a cutter is 1 type.

7. Aging resistance: the tensile strength change rate (%) and the elongation at break change rate (%) of the sealing strip are measured by using a laminar air ageing oven 1 in which the air flow rate is 1m/s and the temperature is 100 ℃ for 168 hours according to the standard of GB/T3512-2014 vulcanized rubber or thermoplastic rubber hot air accelerated ageing and heat resistance test.

Table II results of the tests of the rubber compounds and the sealing tapes corresponding to examples 1 to 5 and comparative examples 1 to 3

Referring to Table II, comparing the detection results of examples 1 to 5 and comparative examples 1 to 3, it can be obtained that the accelerator, EPDM with different ENB contents, diatomite and calcium oxide in the components can directly affect the odor of the sealing strip, the EPDM with low catalyst residue is adopted in examples 1 to 5 of the application, and components such as clean carbon black and a vulcanization system without nitrosamine are matched, so that the scorching time of the prepared rubber compound is moderate (210 to 240 s), the rubber compound is beneficial to long-time parking and odor dispersion, and the obtained product has good appearance surface and is easy to shape; in addition, the rubber compound of the embodiment 1-5 has higher vulcanization speed (120-150 s) and higher vulcanization efficiency, and the obtained sealing strip has higher tensile strength and higher tensile breaking rate, and has the characteristics of environmental protection and low odor, and the N-nitrosamine content is zero. Among these, example 2 was regarded as a preferred example because of its superior performance in examples 1 to 5.

Examples 6 to 10

Examples 6-10 the components without nitrosamine accelerators were adjusted on the basis of the method of example 2, see in particular table three below.

Table III examples 2, 6-10 dosing tables without nitrosamine accelerators (unit: kg)

The compounds and sealing strips obtained in examples 6 to 10 were subjected to the corresponding performance tests according to the methods described in the performance test described above, and the test results are shown in Table IV below.

Table IV test results of the compounds and sealing strips corresponding to examples 2, 6-10

Referring to Table IV, the specific components of the non-nitrosamine accelerator are regulated in the application 6-10, wherein the non-nitrosamine accelerator is added according to the formula of adding the accelerator ZDTP-500.2-0.8 parts, the accelerator CLD-800.5-1.4 parts, the accelerator ZBEC-700.5-1.0 parts, the accelerator ZBPD-500.8-1.5 parts, the accelerator ZAT-700.5-1.5 parts and the accelerator MBT-800.5-2.0 parts into 100 parts of EPDM, so that the vulcanization operation can be controlled, proper scorching time and normal vulcanization time are ensured, and good vulcanization reaction degree is ensured, thereby obtaining a rubber compound with good appearance surface and easy shaping, avoiding the occurrence of cooked rubber, reducing the residual quantity of the accelerator in the rubber compound, further reducing the pungent smell in the production process of the sealing strip, further reducing VOC and smell in the sealing strip, and further reducing the mechanical property and the ageing resistance, and further preferably being used as the application. Among them, example 2 is a preferred example because example 2 has a moderate scorch time and a moderate forward vulcanization time, and also has more excellent mechanical properties.

Examples 11 to 20

Examples 11-20 based on the method of example 2, a modified lignin substrate having hydroxyl-terminated silicone oil adsorbed thereto was also added in a single step of preparing the mix, as described in the following Table V.

Table five cases (unit: kg) of modified lignin base material having hydroxyl-terminated silicone oil adsorbed thereto in examples 2 and 11 to 20

Comparative example 4

This comparative example was based on example 12, where equal amounts of alkali lignin, chitosan and hydroxyl-terminated silicone oil were added directly to a single step of preparing a rubber compound for mixing, corresponding to the rubber compound and sealing tape.

The compounds and sealing tapes obtained in examples 11 to 20 and comparative example 4 were subjected to the corresponding performance tests according to the methods described in the performance test described above, and the test results are shown in the following Table six.

Table six test results of compounds and sealing strips corresponding to examples 2, 11-20

Referring to Table six, in examples 11-20 of the present application, a set amount of modified lignin base material having hydroxyl-terminated silicone oil adsorbed thereto was added to EPDM, wherein the hydroxyl-terminated silicone oil had reactivity at a high temperature vulcanization at a later stage of rubber, and a part of the irritating VOC small molecules such as t-butanol, isopropyl alcohol, acetone and the like generated during the crosslinking process of EPDM could react with the hydroxyl-terminated silicone oil, so that the VOC small molecules were grafted onto the silicone molecular chain, and then discharged by vacuum pumping during the vulcanization at a high temperature. Another part of VOC can be grafted onto the modified lignin base material and be stably locked inside the rubber, thereby effectively reducing the odor of the sealing tape. On the basis, the modified lignin base material can effectively increase the compatibility of the modified lignin base material and ethylene propylene diene monomer rubber under the assistance of hydroxyl-terminated silicone oil, so that the mechanical property of the sealing strip can be effectively improved, and the anti-aging property of the sealing strip can be effectively improved.

The detection result of the combination comparative example 4 shows that the modified lignin base material obtained by modifying the alkali lignin-chitosan composite powder through the organic siloxane hydrolysate can remarkably improve the mechanical property of rubber, and meanwhile, the modified lignin base material and the modified lignin base material have good synergistic effect, and compared with a mode of using modified alkali lignin to desorb hydroxyl-terminated silicone oil and then adding chitosan, the modified lignin base material has better odor reduction and reinforcing anti-aging effects. Among them, the detection result of embodiment 12 is the best of the above embodiments, so this application regards embodiment 12 as a further preferred embodiment.

Examples 21 to 22

This example replaces the blowing agent OBSH-75 on the basis of the composition of example 12. Wherein the blowing agent of example 21 is microsphere blowing agent HDU/GE; the blowing agent of example 22 was a mixture of blowing agent OBSH-75 and microsphere blowing agent HDU/GE formulated at a weight ratio of 3:1.

The compounds and sealing tapes obtained in examples 21 to 22 were subjected to the corresponding performance tests according to the methods described in the performance test described above, and the densities of the samples were measured by a drainage method, and the test results are shown in the following Table seven.

Table seven test results of compounds and sealing strips corresponding to examples 12, 21-22

Referring to Table seven, when the foaming agent of the present application adopts a mixture of the foaming agent OBSH-75 and the microsphere foaming agent HDU/GE, the scorch time of the present application can be further prolonged, the positive vulcanization time can be shortened, and the rubber material can obtain more excellent mechanical properties and ageing resistance, so that example 23 is further preferable.

Example 23

This example provides a rubber run at 120℃during a one-stage procedure for the preparation of the compound, based on the components of example 22.

Example 24

This example was based on the composition of example 22 and was run at 70℃in a two stage process for preparing the mix.

Example 25

In this example, no off-set odor-releasing step was performed in both the first and second stage of the preparation of the mix based on the components of example 22.

Example 26

In this example, on the basis of the components of example 22, microwave vulcanization was not employed, and specifically, vulcanization was carried out by a press vulcanizer at 180℃for 12 minutes.

The weatherstrips prepared in examples 23-26 above were tested for N-nitrosamine content and odor grade performance as described in the performance test above. As a result of measurement, the N-nitrosamine contents of examples 23-26 were 0. Mu.g/kg, and the odor levels were 3.0, which was inferior to that of example 22.

Therefore, the method and the device increase the stopping and odor-diffusing step when preparing the mixed material glue by increasing the glue discharging temperature when preparing the sealing strip, and further reduce the odor of the sealing strip in terms of technology by matching with the procedure of microwave vulcanization.

In conclusion, the sealing strip can effectively reduce the generation of irritant VOC small molecules and avoid generating nitrosamine, thereby having the effects of environmental protection and low odor.

The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.

Claims

1. The environment-friendly low-odor sealing strip is characterized in that the following components in parts by weight are added in every 100 parts of EPDM: 60-70 parts of clean carbon black, 40-50 parts of calcium carbonate, 40-50 parts of diatomite, 1-3 parts of PEG-4000, 80-90 parts of paraffin oil, 5-10 parts of active zinc oxide, 1-3 parts of stearic acid, 0.5-2 parts of sulfur, 2-7 parts of nitrosamine-free accelerator, 0.1-0.5 part of scorch retarder, 5-10 parts of calcium oxide and 3-4 parts of foaming agent; the ENB content of the EPDM is 8.0-10.0wt%;

according to parts by weight, 8-15 parts of modified lignin base material is added in every 100 parts of EPDM, hydroxyl-terminated silicone oil is adsorbed on the modified lignin base material, the modified lignin base material is obtained by modifying alkali lignin-chitosan composite powder through organic siloxane hydrolysate, and the preparation steps of the alkali lignin-chitosan composite powder are as follows:

2. The environmentally friendly low odor sealing strip of claim 1, wherein: the nitrosamine-free accelerator is one or more selected from accelerator ZDTP, accelerator CLD, accelerator ZBEC, accelerator ZBPD, accelerator ZAT and accelerator MBT.

3. The environmentally friendly low odor seal of claim 2 wherein: the non-nitrosamine accelerant is added into 100 parts by weight of EPDM, wherein the non-nitrosamine accelerant comprises 0.2-0.8 part of accelerant ZDTP-50, 0.5-1.4 part of accelerant CLD-80, 0.5-1.0 part of accelerant ZBEC-70, 0.8-1.5 part of accelerant ZBPD-50, 0.5-1.5 part of accelerant ZAT-70 and 0.5-2.0 parts of accelerant MBT-80.

4. The environmentally friendly low odor sealing strip of claim 1, wherein: the adsorption quantity of the hydroxyl-terminated silicone oil is 5-8wt% of the modified lignin base material.

5. The environmentally friendly low odor sealing strip of claim 1 wherein said modified lignin base material is prepared by the steps of:

6. The environmentally friendly low odor sealing strip of claim 1, wherein: the organic siloxane hydrolysate is prepared by dissolving a silane coupling agent in ethanol water solution to prepare an organic siloxane solution with the concentration of 2-5wt% and heating and hydrolyzing the organic siloxane solution.

7. The method for producing an environmentally friendly low odor sealing tape according to any one of claims 1 to 6, comprising the steps of:

preparing a rubber compound:

two sections: cooling, carrying out open mill, sequentially carrying out thin pass and roll wrapping on the masterbatch, adding sulfur, a nitrosamine-free accelerator, a scorch retarder, calcium oxide and a foaming agent after the glue layer is smooth, carrying out thin pass again, carrying out tablet cooling at 80-90 ℃, and fully stopping odor release to obtain a rubber compound;

microwave vulcanization: and extruding the rubber compound together to obtain the sealing strip, vulcanizing by using two sections of microwaves, and cooling to obtain the environment-friendly low-odor sealing strip.