CN109021266B

CN109021266B - Preparation method of filter film

Info

Publication number: CN109021266B
Application number: CN201810719573.8A
Authority: CN
Inventors: 冯俊山; 刘冬梅; 冯笑男
Original assignee: Changchun Fengtai Automobile Rubber Industry Co ltd
Current assignee: Changchun Fengtai Technology Co.,Ltd.
Priority date: 2018-07-03
Filing date: 2018-07-03
Publication date: 2021-02-12
Anticipated expiration: 2038-07-03
Also published as: CN109021266A

Abstract

The invention relates to the field of automobile filters, in particular to a preparation method of a filter film. At least comprises the following steps: putting nitrile rubber and phenolic resin into a mixing roll, controlling the temperature at 60-100 ℃, mixing for 1-5 min, adding an auxiliary agent, continuing mixing for 1-5 min, adding a vulcanizing agent, a curing agent and a curing accelerator after the rubber material is cooled, and mixing for 1-5 min; and placing the mixed rubber material at room temperature for 6-24 hours, and vulcanizing at 220-270 ℃ for 1-3 min to obtain the filter rubber sheet.

Description

Preparation method of filter film

Technical Field

The invention relates to the field of automobile filters, in particular to a preparation method of a filter film.

Background

Since the first phenolic-nitrile rubber heat-curable adhesive Metlbond4021 was published in the united states in 1943, it has been used in aircraft construction for as long as 70 years to date in large quantities. The phenolic-nitrile rubber hot vulcanization adhesive can keep the position, and is related to other excellent properties besides low price, such as higher physical and mechanical properties in a wider temperature range for bonding various metal materials; the material has better elasticity and toughness, so that the material has better peel strength, impact strength and fatigue resistance; the heat aging and atmospheric aging performance is excellent; has the characteristics of excellent solvent resistance, salt spray resistance and the like. However, when the linear phenolic resin with good heat resistance, flame retardance, electrical insulation and mechanical properties is adopted, the resin is subjected to condensation polymerization during curing to generate small molecular substances, and a defect structure is easily generated in the material, so that the comprehensive properties of the resin such as dimensional stability, strength and the like are reduced.

In addition, although the nitrile rubber has good oil resistance, aging resistance, corrosion resistance and other properties due to the polar group cyano in the molecular chain, the compatibility between the nitrile rubber and the phenolic resin is improved due to the effect of the polar group, and the adhesive prepared by mixing has the characteristics of good cohesiveness and the like. However, the nitrile rubber has a large cyano group content, which affects the impact strength, rebound resilience, cold resistance and other properties of the adhesive, and affects the application field and the service life. Particularly for the air filter, the used adhesive takes epoxy resin as a main raw material, the adhesive is a liquid adhesive, the adhesive needs to be fully stirred before use, and the operation is carried out by adopting a dipping method, a spraying method, a brush coating method, a roll coating method, a transfer method and other methods, so the process is complicated, and the phenomena of uneven adhesive distribution, waste and the like are easy to occur; moreover, the adhesive is brittle after curing, is not impact resistant, and is easily damaged during subsequent processing, transportation and installation, resulting in a short filter life. In addition, cyano-group is easily polarized under the action of an electric field, so that the breakdown voltage of the film is reduced, the dielectric property, heat resistance and other properties of the film are reduced, and the use of the film in the automobile field is limited.

Disclosure of Invention

In order to solve the above technical problems, a first aspect of the present invention provides a method for preparing a filter film, including at least the following steps:

putting nitrile rubber and phenolic resin into a mixing roll, controlling the temperature at 60-100 ℃, mixing for 1-5 min, adding an auxiliary agent, continuing mixing for 1-5 min, adding a vulcanizing agent, a curing agent and a curing accelerator after the rubber material is cooled, and mixing for 1-5 min; and placing the mixed rubber material at room temperature for 6-24 hours, and vulcanizing at 220-270 ℃ for 1-3 min to obtain the filter rubber sheet.

As a preferable technical scheme, the acrylonitrile content in the nitrile rubber is 17-25 wt%.

As a preferred technical scheme, the nitrile rubber is organic siloxane modified nitrile rubber.

As a preferred embodiment, the organosiloxane has a branched structure.

In a preferred embodiment, the phenolic resin is a phenolic resin modified with a compound containing an isocyanate group.

As a preferred embodiment, the isocyanate group-containing compound includes a functional monomer and a crosslinking monomer.

As a preferable technical scheme, the functional monomer molecule contains a halogen group.

As a preferable technical scheme, the crosslinking monomer molecule contains unsaturated double bonds.

As a preferable technical scheme, the weight ratio of the nitrile rubber to the phenolic resin is 1: (1.5 to 3).

A second aspect of the invention provides a filter film prepared according to the method described above.

Has the advantages that: the filter film prepared by the method provided by the invention has excellent dimensional stability compared with the prior art, the shrinkage rate of the film before and after curing is low, and the product is not easy to shrink and deform during long-term use. In addition, the filter rubber sheet with good compatibility of all components can be prepared under the condition of low acrylonitrile content in the used nitrile rubber, so that the rubber sheet has the toughness of the nitrile rubber (has the characteristics of good impact strength) and the rigidity of phenolic resin (has the characteristics of good cohesiveness, heat resistance, solvent resistance, corrosion resistance and the like), and meanwhile, the defects of the nitrile rubber are overcome, so that the rubber sheet has good low-temperature impact resistance, high-temperature shear strength and high-temperature peel strength, the application field of the filter rubber sheet is widened, and the service life is prolonged. In addition, the preparation method provided by the invention is simple, easy to operate and good in market prospect, and the used raw materials and the preparation and use processes are green, environment-friendly, non-toxic and safe to use.

Detailed Description

The technical features of the technical solutions provided by the present invention are further clearly and completely described below with reference to the specific embodiments, and the scope of protection is not limited thereto.

The words "preferred", "preferably", "more preferred", and the like, in the present invention, refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

The nitrile rubber is prepared from butadiene and acrylonitrile by an emulsion polymerization method, is mainly produced by a low-temperature emulsion polymerization method, and has the advantages of excellent oil resistance, higher wear resistance and strong bonding force. But the service performance is poor under acid gasoline and high temperature environment for a long time, and the dimensional stability is poor under high temperature. The nitrile rubber has good elasticity and toughness due to the flexible linear molecular chain structure, has good resistance to media such as water, organic solvents, oil and the like due to the polar cyano group on acrylonitrile, and is relatively high in polarity, so that the compatibility between the nitrile rubber and other organic resins (phenolic resins) is improved. The more the content of acrylonitrile, the better the oil resistance, stability, tensile strength, etc. of the rubber, but the worse the cold resistance, toughness, etc., the more brittle the rubber sheet becomes after curing, and the less impact resistant it is. The conventional nitrile rubber with low acrylonitrile content has the defects that the polar groups are not enough to influence the performances of the product such as stability, strength and the like, and the low content of the polar groups can cause poor compatibility among a plurality of components in the processing process, so that the product has uneven performance and high defective rate.

In one embodiment, the acrylonitrile content in the nitrile rubber is 17-25 wt% (the acrylonitrile content refers to the weight of acrylonitrile monomers used for preparing the nitrile rubber as a percentage of the total weight of the nitrile rubber); preferably, the nitrile rubber is organosiloxane modified nitrile rubber; more preferably, the organosiloxane has a branched structure; further preferably, the organosiloxane having a branched structure is selected from one or more of vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltris (methoxyethoxy) silane, vinyltris (methoxypropoxy) silane, 3- [ bis (2-methoxyethoxy) methylsilyl ] propyl methacrylate.

The organic siloxane modified nitrile rubber can be obtained by placing unvulcanized nitrile rubber (NBR 1704 brand rubber with the acrylonitrile content of 17-20%) in a small internal mixer, adding 8 wt% of branched organic siloxane (vinyl tri (2-methoxyethoxy) silane, CAS: 1067-53-4), mixing for 5 minutes at 70 ℃, adding 0.3 wt% of azodiisobutyronitrile, reacting for 45 minutes under heat preservation, cooling and discharging.

The content of cyano-group in the nitrile rubber is reduced, the content of polar group in the rubber is reduced, the mixing capability between the nitrile rubber and the phenolic resin is inevitably hindered, and if the two main components are separated, the performances of the filter rubber sheet such as the adhesive property, the impact strength and the like can be greatly reduced. The applicant finds that the filter rubber sheet obtained by modifying the nitrile rubber by the organosiloxane and then mixing and vulcanizing the nitrile rubber with the phenolic resin has the characteristics of good adhesion, dimensional stability, high temperature resistance and the like even if other polar groups are not introduced. Meanwhile, the applicant unexpectedly discovers that when the organic siloxane with the branched structure is adopted, the obtained filter rubber sheet has very excellent high-temperature resistance, can still maintain good physical and chemical properties (such as cohesiveness, shear strength, peeling strength and the like) under a high-temperature condition, also has good low-temperature stability, can also have good impact strength under a low-temperature environment, and has the characteristics of both rigid materials and flexible materials. The applicant speculates that the possible reason is that the organosiloxane introduces a certain amount of Si-O-Si bonds to the molecular chain of the nitrile rubber, the silicon-oxygen bonds have large bond energy, are not easy to break at high temperature and have good stability. Meanwhile, in the introduction of siloxane with a branched structure, probably because entanglement among molecular chains of the branched structure is less, the viscosity of a polymer is relatively reduced, and the polymer is easy to flow and disperse.

The phenolic resin is also called bakelite, also called bakelite powder, and is prepared by polycondensation, neutralization and water washing of phenol and formaldehyde under the condition of catalyst, the specific gravity of the entity is about 1.7 on average, and the phenolic resin is easily soluble in alcohol, insoluble in water and stable to water, weak acid and weak base solution. The thermoplastic phenolic resin and the thermosetting phenolic resin can be prepared by regulating and controlling the molar ratio of the phenol to the formaldehyde and the parameters of the catalyst such as the class, the dosage and the like. The molecular chain of the linear thermoplastic phenolic resin has hydroxyl, and can be crosslinked and cured through intermolecular dehydration condensation, but small molecular compounds can be generated in the condensation curing process, so that the formed phenolic resin material is easy to shrink due to volatilization at high temperature, the dimensional stability is poor, the condensation curing process is easy to carry out particularly in a high-temperature environment, and the material has larger shrinkage and poor dimensional stability along with the process.

In the process of reducing the curing size stability of the phenolic resin, the inventor modifies the phenolic resin by adopting isocyanate ethyl acrylate (CAS: 13641-96-8) or isocyano ethyl methacrylate (CAS: 30674-80-7), introduces high-temperature reactive double bond groups on polymer molecules, replaces the traditional condensation curing mode of the phenolic resin, and crosslinks double bonds on the polymer at high temperature to cure and form the phenolic resin. Although the dimensional stability of the phenolic resin material obtained by this method is certainly greatly changed at the time of curing, the aging properties, particularly the aging properties and chemical stability under a high humidity environment, are yet to be further improved, and the applicant speculates that hydrolysis is likely to occur under a high humidity environment, particularly when the environmental temperature is relatively high, due to the introduction of an ester group into the modified phenolic resin molecule, causing a change in the dimensions of the material structure, thereby causing deterioration of the product properties.

In one embodiment, the phenolic resin is a phenolic resin modified with a compound containing an isocyanate group.

In one embodiment, the isocyanate group-containing compound includes a functional monomer and a crosslinking monomer.

In one embodiment, the functional monomer molecule contains a halogen group; preferably, the halogen group is selected from one or more of fluorine, chlorine or bromine groups; more preferably, the functional monomer molecule contains a multi-ring structure; further preferably, the polycyclic structure is selected from one or more of benzene ring, cyclopentyl group, furan group, thiophene group, morpholine group and piperidine group.

The applicant finds that a certain amount of functional monomers with polycyclic groups are introduced into the side chain of the phenolic resin molecule, so that the heat resistance of the phenolic resin film can be improved to a certain extent, and the phenolic resin film still has excellent mechanical properties at high temperature. The applicant has also found that when the functional monomer with polycyclic group also contains halogen element (especially fluorine), the performances of high temperature resistance, humidity resistance, solvent resistance and the like are improved obviously, which is probably because fluorine atom has larger electron-withdrawing effect and the bond length of C-F bond is shorter, which can form better shielding effect to C-C bond, and is beneficial to improving the performances of oil resistance, solvent resistance, high temperature resistance and the like of the phenolic resin film.

The adhesive used on the filter component is required to have higher strength, cohesiveness, flexibility, impact strength and other properties in the working environment of a three-filter component in engine equipment, so that a functional monomer capable of reacting with the hydroxyl active group on the molecular chain skeleton of the phenolic resin, such as a compound containing carboxyl, isocyanate, acyl chloride and other groups, is introduced to change the aggregation structure of the phenolic resin polymer, and improve the cohesiveness, the impact strength and other properties of the phenolic resin polymer.

In a preferred embodiment, the functional monomer is selected from the group consisting of 2-chloro-4- (trifluoromethyl) phenyl isocyanate, 3- (trifluoromethyl) -4-methylphenyl isocyanate, 5-tert-butyl-3-isoxazolyl isocyanate, 2- (2-thienyl) ethyl isocyanate, 4-isobutoxybenzyl isocyanate, 4-butyl-2-methylphenyl isocyanate, 2,6, 6-tetramethylpiperidin-4-yl isocyanate, cyclohexyl isocyanate, 4- (hexyloxy) phenyl isocyanate, 4- (octyloxy) phenyl isocyanate, 4- (trifluoromethyl) benzyl isocyanate, 3, 5-bis (trifluoromethyl) phenyl isocyanate, mixtures thereof, and mixtures thereof, One or more of 2-phenylethyl isocyanate, 5-methyl-2- (trifluoromethyl) -3-furyl isocyanate; preferably, the functional monomer is selected from one or more of 4-isobutoxy benzyl isocyanate, 4- (trifluoromethyl) benzyl isocyanate, 3, 5-bis (trifluoromethyl) phenyl isocyanate and 5-methyl-2- (trifluoromethyl) -3-furyl isocyanate; further preferably, the functional monomer is 5-methyl-2- (trifluoromethyl) -3-furyl isocyanate or 3, 5-bis (trifluoromethyl) phenyl isocyanate.

In the prior art, in order to improve the properties of the phenolic resin, such as strength, adhesion, high temperature resistance and the like, an active group with high rigidity is often introduced into a phenolic resin molecular chain, so that the mobility of the polymer molecular chain at high temperature is reduced, and the activation energy for the migration of the polymer molecular chain is improved. However, the film obtained by the method has the advantages that the flexibility of polymer molecular chains is reduced, the capability of the polymer for changing conformation is weakened, the phenolic resin becomes very brittle after being cured, the impact resistance of the material is greatly influenced, and other mechanical properties are improved by sacrificing the impact resistance of the phenolic resin material. In the invention, the applicant unexpectedly discovers that after the functional monomer with a specific functional group is adopted, the dosage of the functional monomer is regulated and controlled, and the dosage of the nitrile rubber, the curing agent, the curing accelerator and other components compounded with the phenolic resin is adopted, the filter rubber sheet has good mechanical property, and simultaneously the impact resistance of the filter rubber sheet is not reduced, so that the filter rubber sheet with good mechanical property and impact resistance is successfully obtained.

In one embodiment, the crosslinking monomer contains an unsaturated double bond in the molecule.

In addition, since the crosslinking monomer needs to be introduced into the molecular chain of the phenolic resin polymer and is mainly fixed by reacting with the hydroxyl group on the molecular chain of the phenolic resin, the molecule of the crosslinking monomer needs to have an active group capable of reacting with the hydroxyl group, such as carboxyl, isocyanate, acid chloride, and the like. In the present invention, a crosslinking monomer having an isocyanate group in the molecular chain is preferably used. Preferably, the crosslinking monomer is 2-methylpropan-2-enoyl isocyanate (CAS number: 4474-60-6) or 3-ethoxy-2-acryloyl isocyanate (CAS number: 928778-13-6).

In a preferred embodiment, the preparation method of the modified phenolic resin comprises the following steps:

(1) mixing functional monomer and dibutyltin dilaurate, adding organic solvent (such as DMF, DMSO, DMAc, trichloromethane, dichloromethane, tetrahydrofuran, hexafluoroisopropanol, etc.) for dissolving, and preparing into 0.12g/ml solution;

(2) dissolving phenolic resin in an organic solvent at 80 ℃, then dripping the solution obtained in the step (1) at the speed of 0.4ml/min, stirring for 10min, and heating to 90 ℃ for reaction for 1-2 hours;

(3) and (3) cooling the solution system obtained in the step (2) to 70 ℃, adding a crosslinking monomer, stirring for reacting for 3 hours, cooling to room temperature, concentrating, filtering, and drying to obtain the modified phenolic resin.

In one embodiment, the weight ratio of the crosslinking monomer to the functional monomer is (1-2.2): 1; preferably, the weight ratio of the crosslinking monomer to the functional monomer is 1.8: 1.

in a preferred embodiment, the weight of the functional monomer accounts for 4-10 wt% of the weight of the modified phenolic resin; preferably, it is 6 wt%.

In one embodiment, the weight ratio of nitrile rubber to phenolic resin is 1: (1.5-3); preferably, the weight ratio of the components is 1: 2.2.

the auxiliary agent comprises an anti-aging agent, an active agent, a lubricant and other conventional auxiliary agents. In the present invention, the antioxidant is not particularly limited, and examples thereof include amine-ketone compounds, imidazole compounds, amine compounds, phenol compounds, sulfur compounds, phosphorus compounds, and the like; preferably, the anti-aging agent is ODA (4,4' -dioctyl diphenylamine). The active and lubricant may be fatty acids and salts thereof, such as stearic acid and zinc stearate, and the like.

In the invention, the vulcanizing agent can be sulfur, thiuram, resin vulcanizing agent and the like; preferably, sulfur is used as the vulcanizing agent.

The promotion in the present invention is an auxiliary additive for promoting reaction curing, shortening curing time or not affecting curing performance at low temperature curing. In one embodiment of the invention, the curing accelerator is selected from one or more of fatty amine accelerator, acid anhydride accelerator, polyether amine catalyst, latent catalyst; preferably, the curing accelerator is selected from one or more of 2,4, 6-tris (dimethylaminomethyl) phenol, triethanolamine, N-dimethylaniline, 1, 8-diazabicycloundecen-7-ene, diethylthiourea, dipropanol, bis (thiocarbonyldimethylamine) disulfide, diphenylhydroxyethyl-3-quinuclidine ester, zinc diethyldithiocarbamate, N-cyclohexyl-2-benzothiazolesulfenamide, 2-mercaptobenzothiazole, dibenzothiazole disulfide; more preferably, the curing accelerator is 2-mercaptobenzothiazole and dibenzothiazyl disulfide; further preferably, the weight ratio of the 2-mercaptobenzothiazole to the dibenzothiazyl disulfide is 5: 4.

the curing agent in the present invention is a substance capable of further reacting with the phenolic resin polymer to cure and mold the phenolic resin polymer. In one embodiment, the curing agent is selected from one or more of epoxide addition polyamines, aromatic amine curing agents, dicyandiamide, aliphatic amines, imidazole derivatives. Examples of the aliphatic amine curing include vinyl triamine, aminoethyl piperazine, hexamethylenetetramine, ethylenediamine, diaminocyclohexane, triethylenetetramine, dipropylenetriamine, trimethylhexamethylenediamine, and diethylamine; examples of the aromatic amine curing agent include m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and dibenzylamine ether; preferably, the curing agent is hexamethylenetetramine.

Applicants have found that the incorporation of a certain amount of dicumyl peroxide (DCP) into the curing agent increases the degree of crosslinking of the polymer in the system, and therefore the addition of 4% by weight of dicumyl peroxide to the curing agent is combined with dicumyl peroxide to provide the hexamethylenetetramine curing agent.

In order to make the technical solution provided by the present invention clearer, the technical solution of the present invention is further explained by the following specific examples.

Examples

Example 1

Embodiment 1 provides a method for preparing a filter film, including the steps of:

putting 35g of nitrile rubber and 77g of phenolic resin into a mixing roll, controlling the temperature at 80 ℃, mixing for 1min, adding 0.6g of an anti-aging agent ODA (4,4' -dioctyl diphenylamine), 0.4g of stearic acid and 0.4g of zinc stearate, continuously mixing for 2min, discharging rubber, cooling the rubber material, then carrying out second-stage mixing, adding 0.3g of sulfur, 0.5g of 2-mercaptobenzothiazole, 0.4g of dibenzothiazyl disulfide and 5g of hexamethylenetetramine curing agent mixed with dicumyl peroxide during the second-stage mixing, and mixing for 5 min; and standing the mixed rubber material at room temperature for 12 hours, vulcanizing at 250 ℃ for 1min, discharging the rubber, forming and cutting to obtain the filter rubber sheet.

The nitrile rubber is NBR 1704 brand rubber with the acrylonitrile content of 17-20%, and is purchased from Lanzhou chemical industry company; the phenolic resin is linear bisphenol A phenolic resin which is purchased from Dongpo International trade company Limited in Jiangyun city and is of the trademark DPS-2110.

Example 2

Embodiment 2 provides a method for preparing a filter film, including the steps of:

putting 35g of nitrile rubber and 52g of phenolic resin into a mixing roll, controlling the temperature at 60 ℃, mixing for 1min, adding 0.6g of an anti-aging agent ODA (4,4' -dioctyl diphenylamine), 0.4g of stearic acid and 0.4g of zinc stearate, continuously mixing for 1min, discharging rubber, cooling the rubber material, then carrying out second-stage mixing, adding 0.3g of sulfur, 0.5g of 2-mercaptobenzothiazole, 0.4g of dibenzothiazyl disulfide and 5g of hexamethylenetetramine curing agent mixed with dicumyl peroxide during the second-stage mixing, and mixing for 1 min; and standing the mixed rubber material at room temperature for 6 hours, vulcanizing at 220 ℃ for 3min, discharging the rubber, forming and cutting to obtain the filter rubber sheet.

Example 3

Embodiment 3 provides a method for preparing a filter film, comprising the steps of:

putting 35g of nitrile rubber and 105g of phenolic resin into a mixing roll, controlling the temperature at 100 ℃, mixing for 5min, adding 0.6g of an anti-aging agent ODA (4,4' -dioctyl diphenylamine), 0.4g of stearic acid and 0.4g of zinc stearate, continuously mixing for 5min, discharging rubber, cooling the rubber material, then carrying out secondary mixing, adding 0.3g of sulfur, 0.5g of 2-mercaptobenzothiazole, 0.4g of dibenzothiazyl disulfide and 5g of hexamethylenetetramine curing agent mixed with dicumyl peroxide during the secondary mixing, and mixing for 5 min; and standing the mixed rubber material at room temperature for 6 hours, vulcanizing at 270 ℃ for 1min, discharging the rubber, forming and cutting to obtain the filter rubber sheet.

Example 4

Embodiment 4 provides a method for preparing a filter film, comprising the steps of:

The nitrile rubber is branched organosiloxane modified nitrile rubber, and the preparation method comprises the following steps:

nitrile butadiene rubber (NBR 1704 brand rubber with the acrylonitrile content of 17-20%, purchased from Lanzhou chemical industry Co.) is placed in a small internal mixer, 8 wt% of vinyl tris (2-methoxyethoxy) silane (CAS: 1067-53-4) is added, after 5 minutes of mixing at 70 ℃, 0.3 wt% of azobisisobutyronitrile is added, the mixture is reacted for 45 minutes under heat preservation, and then the mixture is cooled and discharged, thus obtaining the nitrile butadiene rubber.

The phenolic resin is modified by a compound containing isocyanate groups, and the preparation method comprises the following steps:

(1) mixing 1.02g of functional monomer and 0.03g of dibutyltin dilaurate, adding trichloromethane for dissolving, and preparing a solution of 0.12 g/ml;

(2) taking 17g of linear bisphenol A phenolic resin, dissolving the linear bisphenol A phenolic resin in 120ml of trichloromethane at the temperature of 80 ℃, then dripping the solution obtained in the step (1) at the speed of 0.4ml/min, stirring for 10min, and heating to 90 ℃ to react for 1.5 hours;

(3) and (3) cooling the solution system obtained in the step (2) to 70 ℃, adding 1.83g of crosslinking monomer, stirring for reacting for 3 hours, cooling to room temperature, concentrating, filtering, and drying to obtain the modified phenolic resin.

The functional monomer is 5-methyl-2- (trifluoromethyl) -3-furyl isocyanate (CAS: 306935-03-5); the crosslinking monomer is 3-ethoxy-2-acryloyl isocyanate (CAS number: 928778-13-6); the phenolic resin is linear bisphenol A phenolic resin which is purchased from Dongpo International trade company Limited in Jiangyun city and is of the trademark DPS-2110.

Example 5

Embodiment 5 provides a method for preparing a filter film, comprising the steps of:

(3) and (3) cooling the solution system obtained in the step (2) to 70 ℃, adding 1.02g of crosslinking monomer, stirring for reaction for 3 hours, cooling to room temperature, concentrating, filtering and drying to obtain the modified phenolic resin.

Example 6

Embodiment 6 provides a method for preparing a filter film, comprising the steps of:

(3) and (3) cooling the solution system obtained in the step (2) to 70 ℃, adding 2.24g of crosslinking monomer, stirring for reacting for 3 hours, cooling to room temperature, concentrating, filtering, and drying to obtain the modified phenolic resin.

Example 7

Example 7 provides a method for preparing a filter film, which is different from example 4 in that the organosilicon used in the modified nitrile rubber is vinyltrimethoxysilane.

Example 8

Example 8 provides a method for preparing a filter rubber sheet, which is different from example 4 in that the crosslinking monomer used in the modified phenolic resin is 2-methylprop-2-enoyl isocyanate (CAS number: 4474-60-6).

Example 9

Embodiment 9 provides a method for preparing a filter rubber sheet, which is different from embodiment 4 in that the nitrile rubber is unmodified nitrile rubber with an acrylonitrile content of 36-40%, and is purchased from Lanzhou chemical industry company under the brand name NBR 3604.

Example 10

Example 10 provides a method for preparing a filter rubber sheet, which is different from example 4 in that the functional monomer is used in an amount of 4 wt% based on the weight of the modified phenolic resin in the preparation process of the modified phenolic resin.

Example 11

Example 11 provides a method for preparing a filter paper sheet, which is different from example 4 in that the functional monomer is used in an amount of 10 wt% based on the weight of the modified phenolic resin in the preparation process of the modified phenolic resin.

Comparative example 1

Comparative example 1 provides a method for preparing a filter sheet, which is different from example 4 in that an unmodified phenol novolac-type phenol resin is used.

Comparative example 2

Comparative example 2 provides a preparation method of a filter rubber sheet, which is different from example 4 in that modified nitrile rubber with the same grade and the acrylonitrile content of 17-20% is adopted.

Comparative example 3

Comparative example 3 provides a method for preparing a filter sheet, which is different from example 4 in that the method for preparing the modified phenolic resin comprises the following steps:

(3) and (3) cooling the solution system obtained in the step (2) to 70 ℃, preserving heat, stirring for 3 hours, cooling to room temperature, concentrating, filtering and drying to obtain the modified phenolic resin.

The functional monomer is 5-methyl-2- (trifluoromethyl) -3-furyl isocyanate (CAS: 306935-03-5).

Comparative example 4

Comparative example 4 provides a method for preparing a filter sheet, which is different from example 4 in that the method for preparing the modified phenolic resin comprises the following steps:

(1) taking 17g of linear bisphenol A phenolic resin, dissolving the linear bisphenol A phenolic resin in 120ml of trichloromethane at the temperature of 80 ℃, then adding 0.03g of dibutyltin dilaurate, stirring for 10min, and heating to 90 ℃ for reaction for 1.5 hours;

(2) and cooling the system to 70 ℃, adding 1.83g of crosslinking monomer, stirring and reacting for 3 hours, cooling to room temperature, concentrating, filtering and drying to obtain the modified phenolic resin.

The crosslinking monomer is 3-ethoxy-2-acryloyl isocyanate (CAS number: 928778-13-6).

Comparative example 5

Comparative example 5 provides a method for preparing a filter rubber sheet, which is different from example 4 in that, in the preparation process of the modified phenolic resin, under the condition that the weight of the functional monomer is not changed, the weight ratio of the functional monomer to the crosslinking monomer is 1: 5.

comparative example 6

Comparative example 6 provides a method for preparing a filter rubber sheet, which is different from example 4 in that, in the preparation process of the modified phenolic resin, under the condition that the weight of the functional monomer is not changed, the weight ratio of the functional monomer to the crosslinking monomer is 1: 0.2.

comparative example 7

Comparative example 7 provides a method for preparing a filter sheet, which is different from example 4 in that the weight of the functional monomer is 4.25g during the preparation of the modified phenolic resin.

Performance testing

1. The filter rubber sheets provided herein were prepared according to the provided method, discharged into a mold of a specific size, and cured at 100 ℃ for 10min, and then vulcanized for a corresponding time according to the conditions provided in examples and comparative examples, and the average size shrinkage (%) of the resulting rubber sheets before and after vulcanization curing was measured.

2. The filter rubber sheet provided by the application is bonded on a 45# steel plate, cured for 10min at 100 ℃, thermally treated for 2min at 250 ℃, and then placed in a high-temperature test box at 200 ℃ to test the peel strength and the shear strength, wherein the peel strength test is carried out according to the method of the national standard GB/T7760-.

3. Mixing the raw materials for preparing the filter rubber sheet provided by the application by a mixing roll in a conventional manner, cutting the mixture into specific sizes, and testing the notch impact resistance of the rubber sheet provided by the application at a low temperature according to the standard GB/T1043 + 1993, wherein the testing temperature is 0 ℃.

TABLE 1 Performance test Table

As can be seen from Table 1, the filter sheets prepared according to the method of the present invention have low shrinkage before and after curing and molding, good dimensional stability, and are not prone to shrink-deformation of the darts during long-term use. Moreover, the film with good compatibility is prepared by adopting the nitrile rubber with low acrylonitrile content, so that the flexibility, corrosion resistance, stability and the like of the phenolic resin are improved, the film also has good impact strength at low temperature, and good shear strength and peel strength at high temperature, the film has the flexibility of the nitrile rubber and the rigidity of the phenolic resin, the original defects of the nitrile rubber and the phenolic resin are further overcome, and the comprehensive performance of the film is comprehensively improved.

Finally, it should be understood that the above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The preparation method of the filter film is characterized by at least comprising the following steps:

putting nitrile rubber and phenolic resin into a mixing roll, controlling the temperature at 60-100 ℃, mixing for 1-5 min, adding an auxiliary agent, continuing mixing for 1-5 min, adding a vulcanizing agent, a curing agent and a curing accelerator after the rubber material is cooled, and mixing for 1-5 min; placing the mixed rubber material at room temperature for 6-24 hours, and vulcanizing at 220-270 ℃ for 1-3 min to obtain the filter rubber sheet;

the nitrile rubber is organic siloxane modified nitrile rubber;

the organosiloxane has a branched structure;

the phenolic resin is modified phenolic resin of a compound containing isocyanate groups;

the compound containing the isocyanate group comprises a functional monomer and a crosslinking monomer;

the functional monomer molecule contains a halogen group;

the crosslinking monomer molecule contains unsaturated double bonds;

the weight ratio of the nitrile rubber to the phenolic resin is 1: (1.5-3);

the acrylonitrile-butadiene rubber contains 17-20% of acrylonitrile.

2. A filter film made according to the method of claim 1.