Preparation method of a high friction coefficient rubber roller composite material

Abstract

The application relates to a preparation method of a high-friction-coefficient rubber roller composite material, and relates to a rubber roller material preparation method. 4-allyl-2-methoxy phenol and furfural are used as starting materials, an allyl phenolic aldehyde resin containing an unsaturated carbon-carbon double bond is prepared through a condensation reaction, then an allyl phenolic aldehyde resin containing an alcohol hydroxyl group is obtained under the action of an organic lithium catalyst, and finally the allyl phenolic aldehyde resin containing the alcohol hydroxyl group is crosslinked with N,N-methylene bisacrylamide crosslinking agent through reverse-phase suspension polymerization to prepare rigid nanoparticle microspheres. The obtained nanometer microspheres contain a large number of alcohol hydroxyl groups which can react with isocyanate groups, the rigid particles are added into a liquid rubber roller mixture containing polyhydric alcohol, isocyanate and a small-molecule chain extender, and a high-friction-coefficient polyurethane rubber roller can be obtained, and the application has a wide application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing a composite material for rubber rollers, and more particularly to a method for preparing a composite material for rubber rollers with a high coefficient of friction. Background Technology

[0002] Polyurethane rubber, with its stable chemical structure and excellent physical properties, is a preferred material for rubber rollers. The three-dimensional bonding of polyurethane rubber gives the rollers better high-temperature stability, stronger resistance to mechanical impact and chemical corrosion, thus making them widely applicable.

[0003] In the papermaking industry, polyurethane rollers are used to transport paper. The rollers move the paper by rubbing against the paper surface with their frosted texture. After the paper rubs against the roller surface for a long time, the texture on the roller surface will be worn down by the paper. The smoothed roller cannot effectively move the paper, so the roller needs to be replaced frequently.

[0004] Polyurethane rubber is a highly elastic material that generates friction with paper under pressure. The friction mechanism mainly involves the adhesion between the friction surfaces and the hysteresis of the rubber itself. Influencing factors include pressure, speed, temperature, surface condition, and the viscoelasticity of the rubber. The friction characteristics of polyurethane rollers differ from those of general rigid solids because rubber has a very low elastic modulus, easily forming surface contact under load. When rubber rubs against an unlubricated surface, the coefficient of friction changes with speed. At low speeds, the coefficient of friction increases, while at high speeds, it decreases. Due to varying surface conditions, friction is significantly affected by changes in adhesion factors; therefore, adhesion factors are heavily dependent on surface roughness.

[0005] Chinese patent CN202011296951.X discloses a wear-resistant rubber roller for papermaking, which uses spring pushing to ensure stable friction between the roller and paper. Chinese patent CN201820514594.1 discloses a wear-resistant rubber roller for papermaking with easily replaceable rubber layers; the first roller core is recyclable, offering good economic benefits, and the addition of a second roller core provides excellent support, improving stability during use. Chinese patent CN2020 11098604.6 discloses a wear-resistant rubber roller for papermaking that increases wear resistance by improving the support of the rubber layer at the internal gaps of the roller core. The above-disclosed technical solutions all represent improvements in the structural design of the rubber roller. In addition, the wear resistance of rubber rollers can also be improved by increasing the coefficient of friction. There are two main methods: one is to apply a coating to the surface of the rubber roller. For example, a rubber roller treated with "double coating" has a static friction coefficient of 0.35-0.5, a moisture absorption of 0.9538, a moisture release of 0.9217, and a penetration depth of 0.02-0.05 mm.

[0006] However, due to various factors, the grinding phenomenon is still quite prominent when the coated rubber rollers are put into use. The reasons include: poor matching of the usage characteristics of different types of rubber rollers and different types of coatings; monotonous surface treatment process of rubber rollers, resulting in poor rubber roller strain capacity due to the influence of temperature and humidity and the fluctuation of paper type; impurities and coating stains on the surface of rubber rollers, and uneven coating film thickness, all of which will cause uneven distribution of the friction coefficient on the surface of rubber rollers.

[0007] Another method is to add nano-inorganic particles (such as nano-silica) to the liquid polyurethane reactive monomer to improve the friction coefficient. This method is simple, but its disadvantages are also very obvious. Due to the poor bonding between polyurethane and silica, silica particles can easily peel off from the rubber roller, thus reducing the friction coefficient. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing a composite material for high-friction coefficient rubber rollers. To address the shortcomings of existing technologies where applying a "two-component coating" to the surface of polyurethane rollers results in poor compatibility with the polyurethane, leading to uneven friction coefficients, and the easy shedding of inorganic particles, resulting in short roller lifespan, this invention uses natural phenols containing allyl groups as raw materials, which are chemically cross-linked to become part of the polyurethane roller. Therefore, the high-friction coefficient polyurethane roller produced using this method maintains a stable friction coefficient even when the surface polyurethane layer is worn away by friction, as new interfaces form and microspheres are exposed.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for preparing a composite material for high-friction coefficient rubber rollers, wherein the material is prepared through the following process:

[0011] (1) 4-Allyl-2-methoxyphenol and furanaldehyde were reacted via a condensation reaction to prepare an allylphenol-formaldehyde resin containing unsaturated carbon-carbon double bonds. The reaction formula is as follows:

[0012]

[0013] (2) Under alkaline conditions, the phenolic hydroxyl groups of allyl phenolic resin react with the chlorine atoms of epichlorohydrin to prepare epoxidized allyl phenolic resin. The reaction formula is as follows:

[0014]

[0015] (3) The epoxidized allyl phenolic resin undergoes an asymmetric ring-opening reaction of epoxy groups under the catalysis of organolithium to obtain an allyl phenolic resin containing alcohol hydroxyl groups.

[0016]

[0017] (4) A cross-linked furanaldehyde / 4-allyl-2-methoxyphenolic resin nanoparticles containing alcohol hydroxyl groups were prepared by reverse-phase suspension polymerization of alcohol hydroxyl allyl phenolic resin and N,N-methylenebisacrylamide.

[0018]

[0019] The method for preparing a high friction coefficient rubber roller composite material, wherein 4-allyl-2-methoxyphenol and furanaldehyde in step (1) undergo a polycondensation reaction, and the allyl phenolic resin containing unsaturated carbon-carbon double bonds involved is an unsaturated thermoplastic phenolic resin prepared under conditions of excess phenol and acid catalysis.

[0020] The method for preparing a high-friction coefficient rubber roller composite material, wherein the organic lithium catalyst in step (3) includes one or a mixture of several of methyl lithium (CH3Li), phenyl lithium (C6H5Li), organic copper lithium ((CH3)2CuLi), and n-butyl lithium (CH3CH2CH2CH2Li); and the epoxidized allyl phenolic resin obtained in step (2) is subjected to an asymmetric epoxy group selective nucleophilic ring-opening reaction to obtain an allyl phenolic resin containing alcohol hydroxyl groups.

[0021] The method for preparing a high-friction coefficient rubber roller composite material, wherein the rigid nanoparticle microspheres in step (4) are prepared by a reverse suspension polymerization mechanism of a mixture of allyl phenolic resin containing alcohol hydroxyl groups and crosslinking agent N,N'-methylenebisacrylamide.

[0022] The method for preparing a high-friction coefficient rubber roller composite material, wherein the molar ratio of the two reactive monomers, the allyl phenolic resin containing alcohol hydroxyl groups and the crosslinking agent N,N'-methylenebisacrylamide, is 1:0.01-0.1.

[0023] The method for preparing a high-friction coefficient rubber roller composite material, wherein the dispersion medium includes alkanes, aromatics, cycloalkanes, preferably a mixture of one or more of n-hexane, toluene, and cyclohexane, and the mass ratio of the mixture to the allylphenolic resin containing alcohol hydroxyl groups is 1:0.1-0.9.

[0024] The method for preparing a high-friction coefficient rubber roller composite material includes an initiator comprising oil-soluble initiators such as azobisisobutyronitrile, benzoyl peroxide, and cumene hydroperoxide; water-soluble initiators such as ammonium persulfate, potassium persulfate; and one or a mixture of ammonium persulfate / sodium sulfite (hydrogen sulfite), persulfate / triethanolamine, and azobisisobutyramidine hydrochloride; wherein the mass ratio of the allyl phenolic resin containing alcohol hydroxyl groups to the mixture is 1:0.001-0.01.

[0025] The method for preparing a high-friction coefficient rubber roller composite material, wherein the dispersant used in the reverse suspension polymerization is a combination of one or more of polyvinyl alcohol, gelatin, and xanthan gum, and the addition amount is 0.01-0.5% of the total mass of the monomers.

[0026] The method for preparing a high-friction coefficient rubber roller composite material, wherein the reverse suspension polymerization temperature is 50-120℃, the reaction time is 2-12h, and the stirring speed is 200-1000rpm.

[0027] The method for preparing a high-friction coefficient rubber roller composite material, wherein the microspheres have a diameter between 200-300 nm, and the resulting nanoparticles are shown below:

[0028]

[0029] The advantages and effects of this invention are:

[0030] This invention uses natural phenols containing allyl groups as raw materials, instead of modifying phenols with substances such as allyl chloride (chloropropene) to obtain unsaturated phenolic resins. This results in more environmentally friendly raw materials and a simpler process. The aldehyde used is furanaldehyde prepared from corn cobs, which aligns with sustainable development principles. The prepared cross-linked furanaldehyde / 4-allyl-2-methoxyphenolic resin nanoparticles containing alcohol hydroxyl groups possess high rigidity, functioning similarly to nano-silica particles. The numerous alcohol hydroxyl groups on the surface of these microspheres are reactive and can undergo cross-linking reactions with isocyanate groups, ultimately becoming part of the polyurethane roller through chemical cross-linking. Therefore, the polyurethane high-friction roller produced using this method maintains a stable friction coefficient even when the surface polyurethane layer is worn away by friction, as new interfaces are formed and the microspheres are exposed. Attached Figure Description

[0031] Figure 1 TEM image of rigid nanoparticle microspheres made of cross-linked furanaldehyde / 4-allyl-2-methoxyphenolic resin containing alcohol hydroxyl groups;

[0032] Figure 2 This is a schematic diagram of the structure of nanospheres containing alcohol hydroxyl groups. Implementation

[0033] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0034] The improved method provided by this invention first uses 4-allyl-2-methoxyphenol and furfural as starting materials to obtain an allylphenol resin containing unsaturated carbon-carbon double bonds through a condensation reaction; the product is then reacted with epichlorohydrin to obtain an epoxidized allylphenol resin; then, under the action of an organolithium catalyst, the epoxy groups of the epoxidized allylphenol resin undergo an asymmetric ring-opening reaction to obtain an allylphenol resin containing alcohol hydroxyl groups; finally, the allylphenol resin containing alcohol hydroxyl groups is subjected to reverse-phase suspension polymerization with N,N-methylenebisacrylamide crosslinking agent to obtain crosslinked furfural / 4-allyl-2-methoxyphenol resin rigid nanoparticle microspheres with an average particle size of 200-300 nm containing alcohol hydroxyl groups. Example 1

[0035] First, in a 500mL three-necked flask equipped with a stirrer, thermometer, and spherical condenser, 164.201g of 4-allyl-2-methoxyphenol, 90.084g of furanaldehyde, and 30g of 10% formic acid were added. The mixture was reacted at 120℃ and 300rpm for 4 hours to obtain 227.248g of allylphenol resin.

[0036] Then, 135g of epichlorohydrin and 30g of 10% sodium hydroxide aqueous solution were added to 227.248g of allyl phenolic resin. The mixture was reacted at 85℃ and a stirring speed of 300rpm for 2h. The product was washed with water until neutral, then dehydrated and dried at 40℃ to obtain 337.37g of epoxidized allyl phenolic resin powder.

[0037] Next, 337.37g of epoxidized allyl phenolic resin powder was dissolved in 450mL of THF solution, and 0.35g of phenyl lithium catalyst was added at -25℃. After reacting for 3h, 319.12g of allyl phenolic resin containing alcohol hydroxyl groups was obtained after removing THF.

[0038] Finally, 319.12g of allyl phenolic resin containing alcohol hydroxyl groups, 23.151g of N,N-methylenebisacrylamide, 7.5g of benzoyl peroxide initiator, and 72g of polyvinyl alcohol (1788) with a mass concentration of 3% dispersant were added to 745g of n-hexane solution. The polymerization reaction was carried out at 90℃ for 5 h (450 rpm). The solid particles in the reaction system were separated by centrifugation, washed with water, and dried to obtain cross-linked spherical particles containing alcohol hydroxyl groups with an average particle size of 214nm. Example 2

[0039] First, 164.201 g of 4-allyl-2-methoxyphenol, 90.084 g of furanaldehyde, and 50 g of 10% formic acid were added to a 500 mL three-necked flask equipped with a stirrer, thermometer, and spherical condenser. The mixture was reacted at 90 °C and 450 rpm for 6 h to obtain 205.857 g of allylphenol resin.

[0040] Then, 175g of epichlorohydrin and 40g of 10% sodium hydroxide aqueous solution were added to 205.857g of allyl phenolic resin. The mixture was reacted at 92℃ and 400rpm for 3h. The product was washed with water until neutral, then dehydrated and dried at 40℃ to obtain 369.33g of epoxidized allyl phenolic resin powder.

[0041] Next, 369.33g of epoxidized allyl phenolic resin powder was dissolved in 560mL of THF solution, and 0.44g of n-butyllithium catalyst was added at -25℃. After reacting for 3h, 346.15g of allyl phenolic resin containing alcohol hydroxyl groups was obtained after removing THF.

[0042] Finally, 346.15g of allyl phenolic resin containing alcohol hydroxyl groups, 36.245g of N,N-methylenebisacrylamide, 8.6g of azobisisobutyronitrile initiator, and 133g of polyvinyl alcohol 1788 dispersant with a mass concentration of 3% were added to 1254g of toluene solution. The polymerization reaction was carried out at 110 °C for 7 h (400 rpm). The solid particles in the reaction system were separated by centrifugation, washed with water, and dried to obtain cross-linked spherical particles containing alcohol hydroxyl groups with an average particle size of 245nm. Example 3

[0043] First, in a 500mL three-necked flask equipped with a stirrer, thermometer, and spherical condenser, 164.201g of 4-allyl-2-methoxyphenol, 90.084g of furanaldehyde, and 35g of 10% formic acid were added. The mixture was reacted at 110℃ and 330rpm for 3 hours to obtain 236.685g of allylphenol resin.

[0044] Then, 100g of epichlorohydrin and 36g of 10% sodium hydroxide aqueous solution were added to 236.685g of allyl phenolic resin. The mixture was reacted at 85℃ and a stirring speed of 250rpm for 4h. The product was washed with water until neutral, then dehydrated and dried at 40℃ to obtain 324.22g of epoxidized allyl phenolic resin powder.

[0045] Next, 324.22g of epoxidized allyl phenolic resin powder was dissolved in 520mL of THF solution, and 0.65g of organic copper lithium catalyst was added at -25℃. After reacting for 5h, 301.23g of allyl phenolic resin containing alcohol hydroxyl groups was obtained after removing THF.

[0046] Finally, 301.23g of allyl phenolic resin containing alcohol hydroxyl groups, 26.254g of N,N-methylenebisacrylamide, 4.6g of benzoyl peroxide initiator, and 55g of polyvinyl alcohol 1788 dispersant with a mass concentration of 3% were added to 1202g of n-hexane solution. The polymerization reaction was carried out at 115 °C for 4 h (600 rpm). The solid particles in the reaction system were separated by centrifugation, washed with water, and dried to obtain cross-linked spherical particles containing alcohol hydroxyl groups with an average particle size of 244nm.

[0047] We added the particles obtained through Examples 1-3 to the same polyurethane roller formulation to produce polyurethane rollers, and compared them with blank samples.

[0048] The raw material formulation of the rubber roller is as follows: 5 parts of self-made cross-linked furanaldehyde / 4-allyl-2-methoxyphenolic resin nanospheres containing alcohol hydroxyl groups (the self-made particles of Examples 1-3 respectively); 90 parts of polyether polyol 210; 15 parts of diphenylmethane diisocyanate (MDI); 10 parts of dioctyl adipate; and 25 parts of di-o-chloroaniline methane.

[0049] The processing procedure is as follows:

[0050] (1) Dehydrate polyether polyol 210, add diphenylmethane diisocyanate (MDI), and mix and react at 120-150℃ to obtain a semi-prepolymer;

[0051] (2) The self-made filler, namely cross-linked furanaldehyde / 4-allyl-2-methoxyphenolic resin nanospheres containing alcohol hydroxyl groups, is added to dioctyl adipate for dispersion, and the dispersion is added to the semi-prepolymer obtained in step (1) for mixing.

[0052] (3) Add di-o-chloroaniline methane to the mixture in step (2) and stir until homogeneous. React for 3-5 hours and remove the mixture under vacuum of -0.1~-0.09MPa until it is bubble-free. Pour it into the mold and vulcanize for 14-20 hours before demolding.

[0053] Physical tests on the polyurethane rollers containing the materials from Examples 1-3 showed that the hardness, tensile strength, elongation at break, tear strength, stress at a given elongation, and abrasion resistance remained largely unchanged. A comparison of tensile strength and elongation at break retention after thermo-oxidative aging revealed improvements in all parameters after incorporating the materials from the examples. These data comparisons demonstrate that adding the materials prepared according to this invention to the polyurethane roller formulation has minimal impact on the rubber compound's performance, creatively solving the problem of wear-resistant coatings and silica wear-resistant fillers affecting roller performance.

[0054] The results of the study on the effects of the materials in the embodiments of the present invention on the frictional properties of polyurethane rollers show that the addition of the materials significantly increases the static friction and static friction coefficient of the polyurethane rollers, with an increase of over 30%; however, the effect on the dynamic friction and dynamic friction coefficient is relatively small, but still increases by over 10%. In summary, adding the materials of the present invention to the polyurethane roller formulation increases the overall loss factor of the product. The increased loss factor leads to increased material adhesion and hysteresis resistance, which in turn increases the frictional force and the coefficient of friction of the material.

[0055] Table 1 Comparison of blank samples and samples from Examples 1-3

[0056]

[0057] The above embodiments are merely further illustrations of the compounds of the present invention, and the scope of protection of the present invention is not limited thereto. For those skilled in the art, various additions and modifications to the present invention without departing from the technical concept described in the claims also fall within the scope of protection of the present invention. The present invention relates to a specific example, and more particularly to a specific example.

Claims

1. A method for preparing a composite material for high-friction coefficient rubber rollers, characterized in that, The material is prepared by the following process: (1) 4-Allyl-2-methoxyphenol and furanaldehyde were reacted via a condensation reaction to prepare an allylphenol-formaldehyde resin containing unsaturated carbon-carbon double bonds. The reaction formula is as follows: ； (2) Under alkaline conditions, the phenolic hydroxyl groups of allyl phenolic resin react with the chlorine atoms of epichlorohydrin to prepare epoxidized allyl phenolic resin. The reaction formula is as follows: ； (3) The epoxidized allyl phenolic resin undergoes an asymmetric ring-opening reaction of epoxy groups under the catalysis of organolithium to obtain an allyl phenolic resin containing alcohol hydroxyl groups. ； (4) A cross-linked furanaldehyde / 4-allyl-2-methoxyphenolic resin nanoparticles containing alcohol hydroxyl groups were prepared by reverse-phase suspension polymerization of alcohol hydroxyl allyl phenolic resin and N,N′-methylenebisacrylamide. 。 2. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 1, characterized in that, In step (1), 4-allyl-2-methoxyphenol and furanaldehyde undergo a polycondensation reaction, and the resulting allyl phenolic resin containing unsaturated carbon-carbon double bonds is an unsaturated thermoplastic phenolic resin prepared under conditions of excess phenol and acid catalysis.

3. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 1, characterized in that, The organolithium catalyst in step (3) includes one or a mixture of several of methyllithium (CH3Li), phenyllithium (C6H5Li), organocopper lithium ((CH3)2CuLi), and n-butyllithium (CH3CH2CH2CH2Li); the epoxidized allylphenol resin obtained in step (2) is subjected to an asymmetric epoxy group selective nucleophilic ring-opening reaction to obtain an allylphenol resin containing alcohol hydroxyl groups.

4. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 1, characterized in that, The rigid nanoparticle microspheres in step (4) are prepared by a reverse suspension polymerization mechanism of a mixture of allyl phenolic resin containing alcohol hydroxyl groups and crosslinking agent N,N'-methylenebisacrylamide.

5. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 4, characterized in that, The molar ratio of the two reactive monomers, the allylphenol resin containing alcohol hydroxyl groups and the crosslinking agent N,N'-methylenebisacrylamide, is 1:0.01-0.

1.

6. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 4, characterized in that, The dispersion medium comprises one or a mixture of alkanes, aromatics, and cycloalkanes, wherein the mass ratio of the mixture to the allylphenolic resin containing alcohol hydroxyl groups is 1:0.1-0.

9.

7. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 4, characterized in that, The initiator includes oil-soluble initiators such as azobisisobutyronitrile, benzoyl peroxide, and cumene hydroperoxide; water-soluble initiators such as ammonium persulfate, potassium persulfate, and one or a mixture of several of the following: ammonium persulfate / sodium sulfite (hydrogen sulfite), persulfate / triethanolamine, and azobisisobutyramidine hydrochloride; the mass ratio of the allylphenolic resin containing alcohol hydroxyl groups to the mixture is 1:0.001-0.

01.

8. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 4, characterized in that, The dispersant used in the reverse suspension polymerization is one or more of polyvinyl alcohol, gelatin, and xanthan gum, and the amount added is 0.01-0.5% of the total mass of the monomers.

9. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 4, characterized in that, The reverse suspension polymerization is carried out at a temperature of 50-120℃, a reaction time of 2-12h, and a stirring speed of 200-1000rpm.

10. The method for preparing a high-friction coefficient rubber roller composite material as described in claim 4, characterized in that, The diameter of the microspheres is between 200-300 nm.

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