CN115260663A

CN115260663A - Environment-friendly low-odor sealing strip and preparation method thereof

Info

Publication number: CN115260663A
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: 2022-11-01
Anticipated expiration: 2042-08-11
Also published as: CN115260663B

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 is prepared by adding the following components in parts by weight per 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 anti-scorching agent, 5-10 parts of calcium oxide and 3-4 parts of foaming agent; the EPDM has an ENB content of 8.0-10.0wt%. According to the sealing strip, the step of placing and dispersing odor is added when the mixed glue is prepared by improving the glue discharging temperature, and the process of microwave vulcanization is matched, so that the prepared sealing strip has the effects of environmental protection and low odor.

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 a role in 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 during the synthesis, the residue of the catalyst causes VOC (volatile organic Compounds) to be generated in the produced sealing tape. When the VOC in the vehicle reaches a certain concentration, people can feel uncomfortable in a short time, such as headache, nausea and the like; the lung, liver, kidney and nervous system can be seriously injured when the car is in an overproof VOC state for a long time. In addition, the traditional accelerators used in EPDM catalysis, such as secondary amine accelerators like ZDBC, DPTT, TMTD, etc., can generate nitrosamine in the rubber vulcanization process, which not only has the possibility of inducing cancer, but also can make the sealing strip have thick odor. Therefore, the control from the raw materials is the most essential to reduce the VOC content in the automobile.

However, the automobile sealing strips used in the market have high odor grade and VOC content, with the further enhancement of the environmental protection requirement of each host factory on the automotive interior material, the automotive sealing strip in the market is difficult to meet the requirement.

Disclosure of Invention

The application provides an environmental-friendly low-odor sealing strip and a preparation method thereof, the sealing strip adopts EPDM with low catalyst residue, and is matched with clean carbon black, a nitrosamine-free vulcanization system and other components, so that the generation of irritant VOC micromolecules and nitrosamines can be effectively reduced, and the sealing strip has the effects of environmental protection and low odor.

According to a first aspect, the application provides an environment-friendly low-odor sealing strip, wherein the following components in parts by weight are added to 100 parts of EPDM: 60-70 parts of clean carbon black, 40-50 parts of calcium carbonate, 40-50 parts of diatomite, 01-3 parts of PEG-40001, 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 8.0-10.0wt%.

In the sealing strip, EPDM with the ENB content of 8.0-10.0wt% is selected, which is based on the facts that the ENB content is small, the rubber material vulcanization speed is slow, the use amount of a sulfur system needs to be increased, and further the smell in the vulcanization reaction process can be increased; the content of ENB is large, the vulcanization speed of the rubber compound is high, the dosage of a vulcanization system can be reduced, but the residual ENB can also generate odor, so that the EPDM with the proper ENB content needs to be selected.

On the basis, because the sulfur is excessive and generates more pungent odor, the nitrosamine-free accelerator is used for replacing a part of the sulfur, which not only can reduce the generation of carcinogens such as nitrosamine and the like, but also can reduce the usage amount of the sulfur as much as possible and keep the same or similar vulcanization speed of the system. Calcium oxide is added in the sealing strip, and the calcium oxide can effectively absorb nitrosamine formed by the sizing material in the vulcanization reaction, so that the content of the nitrosamine in the sealing strip is reduced.

The surface of the carbon black contains hydrogen and oxygen functional groups and impurities such as sulfur, tar and the like, so that the odor and the VOC content can be influenced, and the quality of an extruded product can be seriously influenced due to the high content of the impurities; in addition, polycyclic aromatic hydrocarbon (ZEK) in the carbon black has carcinogenicity, carbonyl, aldehyde and other oxidizing groups in the carbon black can pollute a contact object or a working medium, and the extract content can also migrate to the surface of a product to cause defects of surface flooding and the like; therefore, the application selects the clean carbon black to effectively reduce the problems.

The diatomite can be used as a reinforcing agent and a deodorant, and the porous structure of the diatomite is utilized to adsorb volatile organic compounds so as to reduce the odor of the volatile organic compounds.

In addition, the PEG-4000 added in the rubber can neutralize the acidity of the filler in the rubber, so that the vulcanization speed and the crosslinking density are increased, and the rubber material is convenient to demould; the paraffin oil is used as a plasticizer, so that the mixing processability can be improved; the zinc oxide and the stearic acid are used as active agents, so that the fluidization speed and activity of the rubber compound can be improved. The scorch retarder can prevent scorching in the vulcanization process of the rubber 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 is matched with the components such as clean carbon black and a nitrosamine-free vulcanization system, so that the generation of irritant VOC micromolecules and nitrosamines can be effectively reduced, and the sealing strip has the effects of environmental protection and low odor.

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

Preferably, the nitrosamine-free accelerator added to 100 parts of the EPDM comprises, by weight, 500.2-0.8 parts of accelerator ZDTP-500, 1.4 parts of accelerator CLD-800.5, 700.5-1.0 parts of accelerator ZBEC, 500.8-1.5 parts of accelerator ZBED, 700.5-1.5 parts of accelerator ZAT-700.5, and 800.5-2.0 parts of accelerator MBT-4736 zxft.

By adopting the technical scheme, the accelerator ZDTP (zinc dialkyldithiophosphate), the accelerator CLD (caprolactam disulfide), the accelerator ZBEC (zinc dibenzyl dithiocarbamate), the accelerator ZBPD (zinc O, zinc O-dibutyldithiophosphate), the accelerator ZAT (zinc diaminodithiophosphate) and the accelerator MBT (2-mercaptobenzothiazole) are all environment-friendly accelerators, do not generate carcinogens such as nitrosamine and the like in the vulcanization process of rubber, are friendly to operators and environment, and have the characteristics of environmental protection and low odor.

Wherein accelerator ZDTP, accelerator ZDPPD, accelerator ZAT all have a synergistic effect with accelerator MBT, accelerator CLD can replace part of sulfur and carcinogenic odorous accelerator DTDM (4,4' -dithiodimorpholine) to the same vulcanization degree, and the non-nitrosamine accelerator herein is formulated as "per 100 parts of the EPDM with accelerator ZDTP-500.2-0.8 parts, accelerator CLD-800.5-1.4 parts, accelerator ZBEC-700.5-1.0 parts, accelerator ZDPPD-500.8-1.5 parts, accelerator ZAT-700.5-1.5 parts, accelerator MBT-800.5-2.0 parts", which makes the vulcanization operation controllable, thereby obtaining a compound with a good vulcanization reaction degree, reducing the residual amount of accelerator in the compound, reducing the irritant VOC during the production of the weatherstrip, and producing the MBT and further reducing the odor of the VOC in the weatherstrip, thus further preferably reducing the odor thereof.

Preferably, every 100 parts of EPDM is also added with 8-15 parts of modified lignin base material in parts 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 hydroxyl-terminated silicone oil adsorbed is also added into the EPDM in a set amount, wherein the hydroxyl-terminated silicone oil has reaction activity under the high-temperature vulcanization of the rubber at the later stage, and irritant VOC (volatile organic compound) micromolecules such as tertiary butanol, isopropanol, acetone and the like generated in the cross-linking process of a part of the EPDM can react with the hydroxyl-terminated silicone oil, so that the VOC micromolecules are grafted to a siloxane molecular chain and are discharged by vacuumizing in the high-temperature vulcanization process; the terminal hydroxyl silicone oil which cannot be timely discharged can be stably adsorbed by the modified lignin base material, the terminal hydroxyl silicone oil is prevented from seeping outwards when the sealing strip is used in the later stage, and then VOC (volatile organic compounds) small molecules grafted to a siloxane molecular chain are stably locked inside rubber, so that the smell of the sealing strip is effectively reduced.

On the basis, the modified lignin base material can effectively increase the compatibility with ethylene propylene diene monomer under the assistance of hydroxyl-terminated silicone oil, not only can effectively improve the mechanical property of the sealing strip, but also can effectively improve the anti-aging property of the sealing strip.

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

By adopting the technical scheme, during mixing, excessive hydroxyl-terminated silicone oil is adsorbed to be separated out from the modified lignin base material, so that rubber is easy to generate bubbles, but the adsorption amount of the hydroxyl-terminated silicone oil is too small, and the VOC removing effect is limited. Therefore, a large number of experiments prove that the hydroxyl-terminated silicone oil is suitable for 5 to 8 weight percent of adsorption.

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

By adopting the technical scheme, the alkali lignin is lignin extracted from plant tissues by alkali, the relative molecular weight is small, the weight average molecular weight is 2000-3000 (lignosulfonate is generally 20000-50000), and the lignin needs to be compounded with chitosan in the application, so that the micromolecular alkali lignin is beneficial to harvesting a compound with a small molecular weight, and the worthy compound powder has good polydispersity in rubber;

the chitosan molecule contains amino, acetamido and hydroxyl at the same time, so the chitosan has more active property and can be modified, activated and coupled. The alkali lignin contains hydroxymethyl, which can react with active hydroxyl of the hydrolysate of organic siloxane, so as to realize the compounding of the alkali lignin and chitosan. The alkali lignin modified by chitosan has better reaction activity, 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 smell of the sealing strip is effectively reduced; the organic siloxane hydrolysis solution can modify the alkali lignin-chitosan composite powder, and the prepared modified lignin base material can stably adsorb the 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 the alkali lignin and the chitosan have good synergistic effect, and compared with the modified alkali lignin, the modified alkali lignin has better effects of reducing odor, reinforcing and resisting aging.

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

adding the alkali lignin-chitosan composite powder into the organic siloxane hydrolysate, heating to 60-70 ℃, rapidly stirring for reaction for 10-12h, 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 is favorably and fully dispersed with the organic siloxane hydrolysate and can be subjected to reaction for 10-12h at the temperature of 60-70 ℃ to complete modification treatment as much as possible.

Preferably, the alkali lignin-chitosan composite powder is prepared by 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 drying.

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, the alkali lignin and the chitosan can be stably and uniformly dispersed in a mixed system in a mode of being dissolved separately and then being mixed, and the alkali lignin and the chitosan can be effectively compounded by adding the glutaraldehyde.

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

By adopting the technical scheme, the silane coupling agent can be dissolved in the 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 reaction activity of the silane coupling agent is ensured. Wherein the silane coupling agent is hydrolyzed as much as possible by keeping the concentration of the silane coupling agent at 2 to 5wt%, thereby obtaining more silicon hydroxyl groups to participate in the reaction.

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

preparing a rubber compound:

a first stage: mixing the raw materials except sulfur, nitrosamine-free accelerator, scorch retarder, calcium oxide and foaming agent in the formula, discharging glue at 155-165 ℃, and fully standing to disperse odor to obtain a master batch;

and (2) second stage: cooling, open milling, sequentially passing the masterbatch through a thin tube and a roller, adding sulfur, a nitrosamine-free accelerator, a scorch retarder, calcium oxide and a foaming agent after the rubber layer is smooth, passing through the rubber layer again, slicing at 80-90 ℃, and fully standing to disperse odor to obtain a rubber compound; microwave vulcanization: and co-extruding the rubber compound to form a sealing strip, then 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 rubber material processing process can also generate certain influence on the smell of the sealing strip, therefore, the rubber is discharged at high temperature (155-165 ℃) to volatilize part of VOC, the sulfur and the accelerator are added during open mixing, the temperature is controlled to be 80-90 ℃, the accelerator and the VOC in the sulfur are also fully volatilized, and then the steps are arranged in first-stage mixing and second-stage mixing to fully park and disperse the smell, wherein the smell reduction degree is smaller after the first-stage parking for dispersing the smell for 8 hours or more, the smell reduction degree is smaller after the second-stage parking for dispersing the smell for 3 days or more, the first-stage full parking for dispersing the smell is parking for 8 hours or more, and the second-stage full parking for dispersing the smell is parking for 3 days or more. After the rubber material is fully placed, the odor of the micromolecule substances in the rubber material can be emitted as much as possible. And finally, by means of microwave vulcanization, on one hand, the rubber material can be uniformly and fully heated for vulcanization, and on the other hand, the rubber material can discharge small molecular substances again in an extruder by means of vacuumizing, so that the prepared sealing strip has the characteristics of environmental protection, low odor, excellent mechanical property and excellent aging resistance.

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

1. the sealing strip adopts EPDM with low catalyst residue, and components such as a vulcanization system of clean carbon black and no nitrosamine are used in cooperation, so that the generation of irritant VOC micromolecules can be effectively reduced, the nitrosamine is prevented from being generated, and the effects of environmental protection and low odor are achieved.

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 aging resistance of the sealing strip can be effectively improved.

3. According to the method, the step of placing and dispersing odor is added when the mixed glue is prepared by improving the glue discharging temperature, and the odor of the sealing strip is further reduced from the process by matching with the process of microwave vulcanization.

Detailed Description

Starting materials

Ethylene propylene diene monomer: the embodiment of the application takes the model as Bayer EPMAP 341 (Mooney viscosity 70 ML) ₁₊₄ 125 ℃, ethylene 50wt%, ENB content 8.0 wt%), langshan EPDM 6950 (Mooney viscosity 65 ML) ₁₊₄ 125 ℃, ethylene 44.3wt%, ENB content 9.0 wt%), exxon EPDM 8800 (Mooney viscosity 73 ML) ₁₊₄ 125 ℃, 53.5wt% ethylene, 10.0wt% ENB) as an example. Comparative example DuPont EPDM 4750 (Mooney viscosity 70 ML) ₁₊₄ 125 ℃, ethylene 50wt%, ENB content 5.0 wt%) as an example.

Clean carbon black: the application takes SP5000 as an example for explanation, the particle size is 60nm, and besides, the carbon black can also be clean carbon black such as natural gas carbon black N774 and the like which meet the ZEK-01.4-08 environmental protection regulation.

Calcium carbonate: the calcium carbonate prepared by a precipitation method is preferably adopted in the application, and the particle size is 0.5-6 mu m.

Diatomite: a preferred embodiment of the present invention is described by Silitin N85, siO ₂ Not less than 87 percent, and other diatomite with equal porosity can be used in addition, which has certain adsorption effect on volatile organic compounds and reduces the odor.

PEG-4000: the molecular weight is 3600-4400, the hydroxyl value is 26-32mgKOH/g, and the content of the effective component is 99 percent.

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, can volatilize small molecular substances to generate odor, and is specifically described by taking the paraffin oil PW-3801 as an example.

Active zinc oxide (active ZnO): the present application specifically uses organic zinc S70 as an example for explanation.

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

Sulfur: the present application will be described with reference to S-80 as an example.

Nitrosamine-free accelerator: the present application is selected from one or more of the group consisting of accelerator ZDTP (zinc dialkyldithiophosphate), accelerator CLD (caprolactam disulfide), accelerator ZBEC (zinc dibenzyldithiocarbamate), accelerator ZBPD (zinc O, zinc O-dibutyldithiophosphate), accelerator ZAT (zinc diaminodithiophosphate), accelerator MBT (2-mercaptobenzothiazole). The accelerators are environment-friendly accelerators, do not generate carcinogens such as nitrosamine and the like in the rubber vulcanization process, are friendly to operators and environment, and have the characteristics of environmental protection and low odor. The nitrosamine-free accelerator is added into 100 parts of EPDM by weight, and comprises accelerator ZDTP-500.5-2.5 parts, accelerator CLD-800.5-1.0 part, accelerator ZBEC-700.5-2.0 parts, accelerator ZDPP-500.5-2.0 parts, accelerator ZAT-700.5-3.0 parts and accelerator MBT-800.5-2.5 parts.

And (3) a scorch retarder: the rubber scorch retarder of type E-80 is preferably used herein.

Calcium oxide: the application preferably adopts CaO-80 with the grain diameter of 6-10 mu m, which is beneficial to absorbing nitrosamine formed in the vulcanization reaction.

Foaming agent: the preferred low odor blowing agent OBSH-75 and the pre-dispersed rubber microsphere blowing agent (model HDU/GE) sold by this company are exemplified.

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 with absorbed hydroxyl-terminated fibers, which is a commercially available product from the following raw materials, is prepared by the following specific steps:

(1) and preparing alkali lignin-chitosan composite powder:

s1, dissolving 5 times of alkali lignin by weight into 100 times of dioxane-water solution by weight, wherein the volume ratio of dioxane to water is 9:1, centrifuging at 2000r/min for 10min, harvesting a centrifugate, dropwise adding diethyl ether into the centrifugate to obtain a 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 2wt% acetic acid-water solution to prepare 5wt% chitosan solution;

and S4, mixing the alkali lignin solution prepared in the step S2 and the chitosan solution prepared in the step S3 according to a volume ratio of 2:1, adding glutaraldehyde with the concentration of 0.3wt% for crosslinking, performing suction filtration and washing at room temperature, collecting precipitates, placing the precipitates in an infrared oven, and drying until the water content is less than or equal to 0.5%, so as to obtain the alkali lignin-chitosan composite powder.

(2) Preparing organic siloxane hydrolysate:

s5, dissolving a silane coupling agent (specifically taking 3-aminopropyltriethoxysilane as an example, also called KH 550) in an ethanol water solution (ethanol: water =80, mass ratio) to prepare an organosiloxane solution with the concentration of 2-5wt%, specifically preparing the organosiloxane solution with the concentration of 3wt% in the preparation example, heating to 50 ℃ while violently stirring, and carrying out heat preservation treatment for 24h to hydrolyze to obtain the organosiloxane hydrolysate.

(3) Preparing a modified lignin base material:

s6, adding the alkali lignin-chitosan composite powder prepared in the step S4 into the organic siloxane hydrolysate prepared in the step S5 according to the weight ratio of 1.

(4) Adsorption end hydroxyl silicone oil

S7, adding hydroxyl-terminated silicone oil (taking the model number of HY-2520 and taking the hydroxyl-terminated silicone oil at two ends as an example, the hydroxyl value is 50-65mgKOH/g, the molecular weight is 2000, the viscosity is 30-60cp (25 ℃) and 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, the preparation example specifically takes 6wt% as an example for preparation, heating to 40 ℃, uniformly stirring, and naturally cooling to room temperature to obtain the modified lignin base material adsorbed with the hydroxyl-terminated fibers.

Preparation examples 2 to 4

In this preparation example, 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, based on the method of preparation example 1.

Preparation examples 5 to 7

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

The present application will be described in further detail with reference to examples and comparative examples.

Examples

Example 1

An environment-friendly low-odor sealing strip comprises the following preparation steps:

(1) preparing components: weighing 100kg of Bayer EPMAP 341, and mixing the following components in parts by weight: clean carbon black SP500060kg, precipitation method 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, antiscorching agent E-800.1kg, caO-805kg and foaming agent OBSH-753kg;

wherein the nitrosamine-free accelerator is prepared by mixing the following components in parts by weight: 500.6kg of accelerator ZDTP, 801.1kg of accelerator CLD, 8978 kg of accelerator ZBEC, 8978 zxft, 8978 kg of accelerator ZBPD, 501.3kg of accelerator ZAT, 701.5kg of accelerator ZAT and 801.5kg of accelerator MBT.

(2) And preparing a rubber compound:

a first stage: adding raw materials except sulfur S-80, a nitrosamine-free accelerator and CaO-80 in a formula into an internal mixer for mixing, wherein a part of micromolecular organic matters are volatilized by lifting a pressure roller and exhausting gas in the process, rubber is discharged at 160 ℃ (the fluctuation is allowed within the range of 155-165 ℃, the influence on the performance of the rubber is small), and the master batch is obtained after 8 hours of full standing and odor dissipation;

and (2) second stage: placing the rubber mixture on an open mill for open milling after cooling, firstly thinly passing the masterbatch for 3 times, then wrapping the masterbatch with a roller, adding sulfur S-80 and a nitrosamine-free accelerator after the rubber layer is smooth, thinly passing the rubber layer for 5 times again, open milling for 5min, slicing at 85 ℃ (the temperature is allowed to fluctuate within the range of 80-90 ℃, the influence on the performance of the rubber material is small), and fully standing for 3 days to disperse the odor to obtain the rubber compound;

(3) and microwave vulcanization: co-extruding the rubber compound with an extruder at an extrusion speed of 15m/min, vulcanizing with two microwave vulcanizing ovens at microwave powers 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 based on the procedure of example 1, see table one below.

TABLE A ingredient Table for examples 1-4 (unit: kg)

	Example 1	Example 2	Example 3
				Bayer EPDMAP341	100	100	100
Clean carbon black SP5000	60	65	70
				Precipitated calcium carbonate	40	45	50
Diatomaceous earth SilitinN85	40	45	50
				PEG-4000	1	2	3
Paraffin PW-3801	80	85	90
				Active ZnO	5	6	10
Stearic acid	1	2	3
				Sulfur S-80	0.5	1.2	2
Accelerant ZDTP-50	0.6	0.5	0.2
				Promoter CLD-80	1.1	0.9	0.3
Accelerating agent ZBEC-70	1.0	0.8	0.3
				Accelerating agent ZDPPD-50	1.3	1.0	0.4
Accelerant 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 adjusted based on the method of example 2. Of these, langshen EPDM 6950 was used in example 4 and Exxon EPDM 8800 was used in example 5.

Comparative example

Comparative example 1

This comparative example replaces 7kg of the nitrosamine-free accelerator with the accelerator TMTD on the basis of the procedure of example 1.

Comparative example 2

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

Comparative example 3

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

Performance testing

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

1. Scorch time T5: when the Mooney viscosity value of the large rotor is lowered to the lowest point, the time corresponding to 5 Mooney viscosity values is increased. Specifically, a Mooney viscometer is used for measurement, the rubber compound is parked for 2 hours under the laboratory condition and cut into a sample with the diameter of 45mm and the thickness of 3mm, the diameter of a large rotor is 38.10 +/-0.03 mm, and the test temperature is 125 +/-1 ℃. Wherein, the quick scorching time is beneficial to the advantages of good appearance surface of the product, easy shaping and the like, but the reaction is controlled improperly and the glue is easy to be boiled. The slow scorch time is not beneficial to obtaining a good appearance surface of the product, but is beneficial to prolonging the storage time of the rubber compound and the time for maintaining the vulcanized state of the rubber, and is convenient for vulcanizing rubber components at different parts, so that the scorch time needs to be moderate.

2. Positive cure time T90 (180 ℃,5 min): the time required from the start of heating to the rise of the torque of the compound by 90 units from the minimum value was measured using a Youke foam-vulcanization instrument with 8g of the rubber compound. Wherein the shorter the positive vulcanization time, the faster the vulcanization rate.

3. N-nitrosamine content/μ g/kg: determined by gas chromatography-thermal energy analysis (GC-TEA). Using CP-Wax58 (25 m × 0.32mm × 1.2 μm) capillary chromatography column; temperature of the gasification chamber: the initial temperature is 50 ℃, the temperature is kept for 1min, and then the temperature is increased to 200 ℃ at the speed of 75 ℃/min; temperature of the column: the initial temperature is 40 ℃, and then the temperature is increased to 230 ℃ at the speed of 14 ℃/min; the temperature of the pyrolysis chamber is 500 ℃, the coupling temperature is 200 ℃, the carrier gas is helium, and the flow rate is 2.5mL/min.

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

4. Odor grade: cutting 20g of sealing strips, placing the sealing strips in a constant-temperature oven at 80 +/-2 ℃ for constant temperature for 2h, taking out the sealing strips, cooling the sealing strips to a detection room temperature of 60 +/-5 ℃ before evaluation, allowing 10 test volunteers with normal smell to evaluate each sealing strip according to the definition of the smell grade, and calculating the average value of the evaluation grades. If the scores differ from each other by more than 2 points for a single evaluation, duplicate measurements should be made in an increase of 15 test volunteers. Wherein, grade 1 is odorless, grade 2 is smellable but not disturbing, grade 3 is obviously smellable but not objectionable, grade 4 is objectionable, grade 5 is strong objectionable, and grade 6 is intolerable.

5. Tensile strength/MPa: the measurement is carried out according to the standard of GB/T528-2009 determination of tensile stress strain performance of vulcanized rubber or thermoplastic rubber, a dumbbell-shaped sample is adopted, and a type 1 is selected as a cut-off knife.

6. Tensile failure rate/%: the measurement is carried out according to the standard of GB/T528-2009 determination of tensile stress strain performance of vulcanized rubber or thermoplastic rubber, a dumbbell-shaped sample is adopted, and a type 1 is selected as a cut-off knife.

7. Aging resistance: the tensile strength change rate (%) and the elongation at break change rate (%) of the weatherstrip were measured after treating at 100 ℃ for 168 hours by using a laminar flow air aging box of type 1, and the air flow rate was 1m/s, according to the standard of GB/T3512-2014 Hot air accelerated aging and Heat resistance test for vulcanized rubber or thermoplastic rubber.

TABLE II examination results of kneading rubbers and sealing tapes corresponding to examples 1 to 5 and comparative examples 1 to 3

Referring to the second table, when the detection results of the examples 1-5 and the comparative examples 1-3 are compared, the odor of the sealing strip can be directly influenced by the accelerator, EPDM (ethylene-propylene-diene monomer) with different ENB contents, diatomite and calcium oxide in the components, the EPDM with low catalyst residue is adopted in the examples 1-5, and clean carbon black, a nitrosamine-free vulcanization system and other components are used in a matching manner, so that the scorching time (210-240 s) of the prepared rubber compound is moderate, the long-time standing is facilitated for odor dispersion, and the obtained product has a good appearance surface and is easy to shape; in addition, the vulcanized rubber compound of the embodiments 1-5 has the characteristics of high vulcanization speed (120-150 s), high vulcanization efficiency, high tensile strength of the obtained sealing strip, high tensile fracture rate, zero N-nitrosamine content, environmental friendliness and low odor. Among these examples, example 2 is a preferred example because example 2 is excellent in performance in examples 1 to 5.

Examples 6 to 10

Examples 6-10 the composition of the nitrosamine-free accelerator was adjusted based on the procedure of example 2, see table three below.

TABLE III ingredient tables for nitrosamine-free accelerators according to examples 2, 6 to 10 (unit: kg)

The compound rubber and the sealing tape obtained in the above examples 6 to 10 were subjected to the corresponding performance tests according to the methods described in the above performance test tests, and the test results are shown in the following Table IV.

TABLE IV test results of the compounds and weatherstrips of examples 2, 6 to 10

Referring to table four, the present application 6-10 is directed to adjusting specific components of a nitrosamine-free accelerator, wherein the nitrosamine-free accelerator is formulated by "adding 500.2-0.8 parts of accelerator ZDTP, 1.4 parts of accelerator CLD-800.5-1.4 parts, 700.5-1.0 parts of accelerator ZBEC, 1.5 parts of accelerator ZBPD-500.8, 1.5 parts of accelerator ZAT-700.5, and 2.0 parts of accelerator MBT-800.5-2.0 parts per 100 parts of the EPDM," which allows the vulcanization operation to be controlled, ensures that the compound has an appropriate scorch time and positive vulcanization time, and has a good vulcanization reaction degree, thereby obtaining a compound having a good appearance, an easy setting, avoiding the occurrence of a mastic, and simultaneously reducing the residual amount of accelerator in the compound, thereby further reducing pungent odor during the production process, which produces a sealing tape having further reduced VOC and odor, and mechanical properties and excellent aging resistance, and thus further preferably selecting the present application as a sealing tape. Among them, the scorch time and the normal vulcanization time of example 2 are moderate, and at the same time, the mechanical properties are more excellent, so example 2 is a preferred example.

Examples 11 to 20

Examples 11-20 on the basis of the method of example 2, a modified lignin substrate having a hydroxyl terminated silicone oil adsorbed thereon was also added in one step of the preparation of the rubber compound, as specified in table five below.

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

Comparative example 4

In the comparative example, on the basis of example 12, the same amount of alkali lignin, chitosan and hydroxyl-terminated silicone oil was directly added to a step of preparing a rubber compound for mixing, and the rubber compound and the sealing tape were obtained correspondingly.

The compounds and sealing tapes obtained in examples 11 to 20 and comparative example 4 were tested for their respective properties according to the methods described in the above tests, and the results are shown in Table six below.

Table six test results of the kneading compounds and sealing tapes corresponding to examples 2 and 11 to 20

Referring to table six, in the examples 11 to 20 of the present application, a set amount of modified lignin base material with hydroxyl-terminated silicone oil adsorbed is added to EPDM, wherein the hydroxyl-terminated silicone oil has reactivity at a high temperature vulcanization in a later period of rubber, and a part of irritant VOC small molecules such as tert-butyl alcohol, isopropyl alcohol, acetone and the like generated in the crosslinking process of the ethylene propylene diene monomer rubber can react with the hydroxyl-terminated silicone oil, so that the VOC small molecules are grafted to a siloxane molecular chain, and are further discharged by vacuum pumping in the high temperature vulcanization process. Another portion of the VOCs can be grafted onto the modified lignin base and be stably locked inside the rubber, thereby effectively reducing the odor of the weatherstrip. On the basis, the modified lignin base material can effectively increase the compatibility with ethylene propylene diene monomer under the assistance of hydroxyl-terminated silicone oil, not only can effectively improve the mechanical property of the sealing strip, but also can effectively improve the anti-aging property of the sealing strip.

According to the detection result of the comparative example 4, the modified lignin base material obtained by modifying the alkali lignin-chitosan composite powder with the organic siloxane hydrolysate can obviously improve the mechanical property of the rubber, and simultaneously has good synergistic effect. Among them, the detection result of embodiment 12 is the best among the above embodiments, so this application regards embodiment 12 as a further preferred embodiment.

Examples 21 to 22

This example replaces blowing agent OBSH-75 with a composition based on example 12. Wherein, the foaming agent of the embodiment 21 is a microsphere foaming 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 tested for their respective properties according to the methods described in the above tests for testing the properties, and the density of the test specimens was measured by the drainage method, and the results are shown in the following Table seven.

TABLE seventhly test results of the kneading rubbers and sealing tapes corresponding to examples 12, 21 to 22

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

Example 23

This example was based on the components of example 22 and was run at 120 ℃ in the stage of the preparation of one of the rubber mixtures.

Example 24

This example is based on the components of example 22 and is sliced at 70 ℃ in the two stage preparation of the mix.

Example 25

This example does not include a step of stopping to remove odor in the first and second steps of preparing the rubber composition based on the components of example 22.

Example 26

In this example, on the basis of the components of example 22, microwave vulcanization, specifically, vulcanization was performed by a press vulcanizer at a vulcanization temperature of 180 ℃ for 12min.

The sealing tapes obtained in examples 23 to 26 were subjected to the performance tests for N-nitrosamine content and odor level in accordance with the methods described in the above-mentioned performance tests. The results of examples 23-26 were found to be inferior to example 22 in terms of the N-nitrosamine content of 0. Mu.g/kg and the odor rating of 3.0.

Therefore, the sealing strip is prepared by increasing the glue discharging temperature, adding the step of placing and dispersing smell when the mixed glue is prepared, and matching with the microwave vulcanization process, the smell of the sealing strip is further reduced in the process.

To sum up, the sealing strip of this application can effectively reduce the production of irritative VOC micro molecule, avoids producing nitrosamine to have the effect of environmental protection, low smell.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law 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 to 100 parts of EPDM (ethylene-propylene-diene monomer) 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 8.0-10.0wt%.

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

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

4. The environmentally friendly, low odor weatherstrip of claim 1, wherein: according to the weight portion, every 100 portions of EPDM is also added with 8-15 portions of modified lignin base material, and hydroxyl-terminated silicone oil is adsorbed on the modified lignin base material.

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

6. The environmentally friendly, low odor weatherstrip of claim 4, wherein: the modified lignin base material is obtained by modifying alkali lignin-chitosan composite powder by organic siloxane hydrolysate.

7. The environmentally friendly, low odor weatherstrip according to claim 6 wherein said modified lignin base is prepared by the steps of:

8. The environmentally friendly, low odor weatherstrip of claim 6 wherein said alkali lignin-chitosan composite powder is prepared by the steps of:

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

10. The method for producing the environmentally friendly and low-odor sealing tape according to any one of claims 1 to 9, comprising the steps of:

preparing a rubber compound:

a first stage: mixing the raw materials except sulfur, nitrosamine-free accelerator, scorch retarder, calcium oxide and foaming agent, discharging rubber at 155-165 ℃, and fully standing to dissipate odor to obtain masterbatch;

and (2) second stage: cooling, open milling, sequentially passing the masterbatch through a thin tube and a roller, adding sulfur, a nitrosamine-free accelerator, a scorch retarder, calcium oxide and a foaming agent after the rubber layer is smooth, passing through the rubber layer again, slicing at 80-90 ℃, and fully standing to disperse odor to obtain a rubber compound;

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