A phenolic resin emulsion and its preparation method and application

Abstract

The present invention provides a phenolic resin emulsion, which is composed of 10 to 70 wt% of phenolic resin nanoparticles, 25 to 85 wt% of a solvent, and 0.5 to 10 wt% of an emulsifier. The present invention also provides a preparation method of the phenolic resin emulsion and its application. The preparation method comprises the following steps: (1) polymerizing an alkylphenol-modified phenolic resin prepolymer under the action of a catalyst; (2) mixing the phenolic resin prepolymer with a solvent and an emulsifier for emulsification to obtain a phenolic resin prepolymer emulsion; and (3) adding a curing agent to the phenolic resin prepolymer emulsion obtained in step (2) to carry out a curing reaction to obtain a phenolic resin emulsion (thermosetting phenolic resin nanoparticle emulsion). The method provided by the present invention is simple and convenient, and the prepared phenolic resin nanoparticles have surface effects such as a small size effect, a quantum effect, an unsaturated bond effect, and an electron tunneling effect. Therefore, when used in the rubber reinforcement process, the interaction between the phenolic resin nanoparticles and the rubber molecules is strengthened, effectively improving the reinforcement effect.

Description

Technical Field

[0001] The invention belongs to the field of polymer nanomaterials and relates to a phenolic resin emulsion and a preparation method and application thereof. Background Art

[0002] When rubber materials are used, reinforcing fillers such as carbon black and white carbon black are generally added to improve the mechanical properties of the rubber. The particle size and particle size distribution, structural morphology and surface chemical properties of the filler are the main factors affecting the performance of the filler on the rubber. Generally speaking, the smaller the particle size of the filler, the larger the specific surface area, the stronger the surface effect, the stronger the ability to restrict the movement of rubber macromolecules, and the greater the reinforcing effect on the rubber. The reinforcing agents currently used in the rubber industry are mostly inorganic mineral fillers, which have a high density, generally 1.7g / cm 3 This significantly increases the density of the reinforcing agent-filled rubber material. For the tire industry, lightweighting tires can reduce vehicle energy consumption, contributing to environmental protection and resource conservation. The development of rubber fillers and reinforcing agents requires high reinforcement, high dispersibility, low density, and low price. Developing organic polymer nanomaterials and applying them to rubber reinforcement is one effective approach.

[0003] Phenolic resin is the earliest industrialized synthetic resin with a history of 100 years. It is widely used due to its readily available raw materials, convenient synthesis and the ability of the cured resin to meet many usage requirements. In recent years, the application of phenolic resin in the rubber industry has received increasing attention, for example, as a tire bead rubber reinforcement agent. Currently, phenolic resin is mostly used for rubber reinforcement using linear phenolic resin and curing agent at the same time. The phenolic resin cross-links with the rubber to form an interpenetrating network, thereby achieving a reinforcement effect. Based on phenolic resin, the preparation of long-chain alkylphenol-modified phenolic resin nanomaterials and the development of new organic polymer fillers are of great significance for improving tire fatigue resistance, wear resistance and other properties, as well as lightweighting tires.

[0004] Chinese patent application number 201310404099.7 discloses a phenolic resin emulsion modified with a water-soluble long-chain alkylphenol. This phenolic resin emulsion is prepared by mixing a hydroxyl-containing aromatic compound, a long-chain alkylphenol, an aldehyde compound, and an aqueous thickener in the presence of an alkaline catalyst and a boron-containing compound, and then polymerizing the mixture to produce the phenolic resin emulsion. This phenolic resin emulsion uses water as a solvent, making it difficult to use directly in rubber processing, as is the case with carbon black and silica.

[0005] Chinese patent application number 201010230480.2 discloses an anhydrous phenolic resin and a preparation method thereof. The preparation method of the phenolic resin comprises the following steps: a) adding phenol and aldehyde in a certain molar ratio to a reactor, and then adding an acidic catalyst for polymerization to obtain the phenolic resin; b) dehydrating the phenolic resin obtained in step a under normal pressure and dissolving it in an organic solvent; and c) adding a curing agent to the phenolic resin solution in step b and mixing the mixture to obtain an anhydrous phenolic resin solution. The phenolic resin in the prepared anhydrous phenolic resin solution is not cross-linked and solidified into nanoparticles, and therefore does not exhibit the surface effects of nanomaterials (such as small size effects, quantum effects, unsaturated bond effects, electron tunneling effects, etc.). However, the surface effects of nanomaterials can enhance the interaction between the phenolic resin and the rubber macromolecules, thereby enhancing the reinforcing effect of the phenolic resin. Summary of the Invention

[0006] The present invention addresses the deficiencies of the prior art and provides a method for synthesizing an organic emulsion of phenolic resin nanoparticles with good synthetic stability and high solid content. The method has the advantages of being simple to operate, safe, efficient, and low-cost, and is particularly suitable for large-scale industrial production, with broad industrial application prospects.

[0007] The synthetic alkylphenol-modified phenolic resin prepolymer of the present invention forms phenolic resin prepolymer emulsion (phenolic resin prepolymer latex particles) with solvent, emulsifying agent mixed emulsification.This mainly is, the alkylphenol-modified phenolic resin prepolymer, it is polarity / non-polar block copolymer, has self-assembly ability in solvent, adds a small amount of emulsifying agent and can form phenolic resin prepolymer emulsion (phenolic resin prepolymer latex particles).And phenolic resin prepolymer latex particles has then reduced the voluntary crosslinking effect between the phenolic resin particle, promptly controlled the growth of phenolic resin particle diameter, increased the stability of phenolic resin prepolymer emulsion again.Further crosslinked by solidifying agent again, form stable phenolic resin emulsion, that is, thermosetting phenolic resin nano particle emulsion, wherein, comprise thermosetting phenolic resin nano particle, the particle diameter of described thermosetting phenolic resin nano particle causes physical and chemical property sudden change to nanoscale, thereby strengthens the physical interaction of phenolic resin emulsion and rubber matrix, produces reinforcing effect. Therefore, the phenolic resin emulsion prepared by the present invention can improve the modulus, strength and elongation of the rubber compound when used in rubber reinforcement, thereby improving the fatigue and wear properties of the rubber.

[0008] The present invention provides a phenolic resin emulsion, which is composed of the following components: 10-70 wt% of phenolic resin nanoparticles, 25-85 wt% of a solvent, and 0.5-10 wt% of an emulsifier; preferably, the emulsion comprises 10-70 wt% of cardanol phenolic resin nanoparticles, 25-85 wt% of environmentally friendly aromatic oil, and 0.5-10 wt% of Tween 60 and Span 60.

[0009] As the preferred technical solution:

[0010] In the phenolic resin emulsion as described above, the phenolic resin nanoparticles are alkylphenol-modified phenolic resin nanoparticles; the particle size of the phenolic resin nanoparticles is 5 to 1000 nm, preferably 10 to 100 nm.

[0011] In the phenolic resin emulsion as described above, the solvent is a non-polar organic solvent selected from one or a combination of naphthenic oil, toluene, xylene, trimethylbenzene, ethylbenzene, environmentally friendly aromatic oil, paraffin oil, etc.; preferably, naphthenic oil, aromatic oil and paraffin oil.

[0012] The alkylphenol-modified phenolic resin as described above, wherein the alkylphenol is one or more alkylphenols containing an alkyl group of 4 to 32 carbon atoms or an unsaturated alkyl group; preferably, it is an alkylphenol containing an alkyl group of 8 to 16 carbon atoms or an unsaturated alkyl group; further preferably, it is one or more of heptylphenol, octylphenol, nonylphenol, decylphenol, cardanol, etc.; further preferably, it is cardanol.

[0013] In the alkylphenol-modified phenolic resin as described above, the emulsifier is one or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant; preferably, it is an anionic surfactant.

[0014] Wherein, the cationic surfactant is one or more of alkyl dimethyl ammonium salt, alkyl trimethyl ammonium salt, alkyl dimethyl benzyl ammonium salt, etc.; preferably, it is alkyl dimethyl benzyl ammonium salt.

[0015] The anionic surfactant is one or more of dodecylbenzenesulfonic acid (LAS), sodium alcohol sulfate (AES), sodium ethoxylated fatty acid methyl ester sulfonate (FMES), sodium secondary alkyl sulfonate (SAS), alcohol ether carboxylate (AEC), alcohol ether phosphate (AEP), etc.; preferably, it is dodecylbenzenesulfonic acid.

[0016] Wherein, the nonionic surfactant is one or more of alkyl glucoside (APG), fatty acid glyceride, fatty acid sorbitan (Span), polysorbate (Tween), etc.; preferably, it is fatty acid sorbitan (Span) and polysorbate (Tween).

[0017] The amphoteric surfactant is one or more of dodecylaminopropionic acid, alkyldimethylsulfoethyl betaine, alkyldimethylsulfopropyl betaine, dodecylethoxysulfobetaine, etc.; preferably, it is dodecylaminopropionic acid.

[0018] Further preferably, the emulsifier is one or more of Span 40, Span 60, Span 65, Span 80, Tween 60, and Tween 80.

[0019] The present invention also provides a method for preparing a phenolic resin emulsion. In the presence of a catalyst, phenol, alkylphenol and formaldehyde react to obtain a phenolic resin prepolymer; then an emulsifier and a solvent are added and emulsified to obtain a phenolic resin prepolymer emulsion; finally, a curing agent is added and cured to obtain the phenolic resin emulsion.

[0020] The preparation method of the phenolic resin emulsion of the present invention specifically comprises the following steps:

[0021] (1) Under the action of a catalyst, phenol, alkylphenol and formaldehyde undergo a phenolic polycondensation reaction to obtain a phenolic resin prepolymer.

[0022] (2) Then, an emulsifier and a solvent are added to the phenolic resin prepolymer to emulsify it to obtain a phenolic resin prepolymer emulsion.

[0023] (3) Adding a curing agent to the phenolic resin prepolymer emulsion prepared in step (2) to carry out a curing reaction to obtain a phenolic resin emulsion.

[0024] In step (1), the catalyst is an acidic catalyst selected from one or more of oxalic acid, sulfuric acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, phosphoric acid, hydrochloric acid, etc.; preferably, it is oxalic acid.

[0025] In step (1), the alkylphenol is one or more alkylphenols containing an alkyl group of 4 to 32 carbon atoms or an unsaturated alkyl group; preferably, it is an alkylphenol containing an alkyl group of 8 to 16 carbon atoms or an unsaturated alkyl group; further preferably, it is one or more of heptylphenol, octylphenol, nonylphenol, decylphenol, cardanol, etc.; further preferably, it is cardanol.

[0026] In step (1), the molar ratio of phenol to alkylphenol is 1:(0.25-9); preferably, 1:2.

[0027] In step (1), the molar ratio of the phenol to the formaldehyde solution is 1:(0.5-0.9); preferably, 1:0.7.

[0028] Wherein, the phenol refers to phenol and alkylphenol.

[0029] In step (1), the acidic catalyst accounts for 0.5-10% of the total mass of phenol and alkylphenol; preferably, 5%.

[0030] In step (1), the phenol-formaldehyde polycondensation reaction is carried out at 70-100°C; preferably, at 100°C.

[0031] In step (1), the phenol-formaldehyde polycondensation reaction time is 1-3 hours; preferably, 1 hour.

[0032] In step (1), the phenol-formaldehyde polycondensation reaction is preferably carried out in a four-necked flask equipped with a condensing and stirring device.

[0033] The step (1) of the present invention further comprises a reduced pressure distillation step after the phenol-formaldehyde polycondensation reaction, wherein the conditions of the reduced pressure distillation are: a distillation temperature of 180° C. and a vacuum degree of -99 KPa.

[0034] In step (2), the emulsifier is one or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant; preferably, it is an anionic surfactant.

[0035] Wherein, the cationic surfactant is one or more of alkyl dimethyl ammonium salt, alkyl trimethyl ammonium salt, alkyl dimethyl benzyl ammonium salt, etc.; preferably, it is alkyl dimethyl benzyl ammonium salt.

[0036] The anionic surfactant is one or more of dodecylbenzenesulfonic acid (LAS), sodium alcohol sulfate (AES), sodium ethoxylated fatty acid methyl ester sulfonate (FMES), sodium secondary alkyl sulfonate (SAS), alcohol ether carboxylate (AEC), alcohol ether phosphate (AEP), etc.; preferably, it is dodecylbenzenesulfonic acid.

[0037] Wherein, the nonionic surfactant is one or more of alkyl glucoside (APG), fatty acid glyceride, fatty acid sorbitan (Span), polysorbate (Tween), etc.; preferably, it is fatty acid sorbitan (Span) and polysorbate (Tween).

[0038] The amphoteric surfactant is one or more of dodecylaminopropionic acid, alkyldimethylsulfoethyl betaine, alkyldimethylsulfopropyl betaine, dodecylethoxysulfobetaine, etc.; preferably, it is dodecylaminopropionic acid.

[0039] Further preferably, the emulsifier is one or more of Span 40, Span 60, Span 65, Span 80, Tween 60, and Tween 80.

[0040] In step (2), the solvent is a non-polar organic solvent selected from one or a combination of cycloalkane oil, toluene, xylene, trimethylbenzene, ethylbenzene, environmentally friendly aromatic oil and paraffin oil; preferably, cycloalkane oil, aromatic oil and paraffin oil.

[0041] In step (2), the emulsifier accounts for 0.5-10% of the total mass percentage of the phenolic resin emulsion system; preferably, it is 5%.

[0042] The phenolic resin emulsion system includes phenolic resin nanoparticles, a solvent and an emulsifier.

[0043] In step (2), the emulsification method is one or more of mechanical stirring, ultrasound and shearing methods; preferably, the emulsification method is shearing method.

[0044] In step (2), the percentage of the solvent in the total mass of the phenolic resin emulsion system is 25-85%; preferably, it is 50%.

[0045] The phenolic resin emulsion system includes phenolic resin nanoparticles, a solvent and an emulsifier.

[0046] In step (3), the curing agent is one or more of paraformaldehyde, hexamethylenetetramine, hexamethoxymethylmelamine, etc.; preferably, it is hexamethoxymethylmelamine.

[0047] In step (3), the mass percentage of the curing agent to the phenolic resin prepolymer is 0.5-20%; preferably, it is 10%.

[0048] In step (3), the temperature of the curing reaction is 100-200°C; preferably, 150°C.

[0049] In step (3), the curing reaction time is 1-5 hours; preferably, 3 hours.

[0050] The invention also provides a phenolic resin emulsion prepared by the method.

[0051] The invention also provides application of the phenolic resin emulsion in rubber reinforcement.

[0052] According to the characteristics of alkylphenol-modified phenolic resin prepolymer, only when the molecular weight of the phenolic resin prepolymer and the proportion of alkylphenol to phenolic resin are appropriate, and appropriate organic solvents, emulsifiers and emulsification conditions are selected, can a good phenolic resin prepolymer emulsion be formed. On this basis, an appropriate curing agent is selected to continue the curing reaction with the phenolic resin, so that the resin will not agglomerate during the curing process and small and uniform phenolic resin nanoparticles can be obtained.

[0053] The alkylphenol-modified phenolic resin prepared and synthesized by the present invention is a linear phenolic resin, which is a thermoplastic resin with a low molecular weight. Hexamethylenetetramine, paraformaldehyde, hexamethoxymethyl melamine and other curing agents are mixed with the phenolic resin prepolymer and heated. The curing agent active groups continue to react with the unreacted ortho- and para-active sites of the phenolic resin, thereby converting the linear phenolic resin from a thermoplastic to a thermosetting resin. Further polycondensation is performed to obtain an insoluble and infusible solidified product. The curing reaction mechanism of the hexamethoxymethyl melamine and phenolic resin prepolymer is shown in the following formula:

[0054]

[0055] Beneficial effects:

[0056] The phenolic resin emulsion prepared by the present invention comprises phenolic resin nanoparticles, and its particle diameter is 5-1000nm, has surface effects such as small size effect, quantum effect, unsaturated bond effect, electron tunneling effect. Therefore, when being applied to rubber reinforcement, can strengthen the interaction force between rubber molecules, effectively improve reinforcement effect. The present invention selects alkylphenol modified phenol formaldehyde resin prepolymer for use, mainly because it is a polar / non-polar block copolymer, only needs to add a small amount of emulsifier, self-emulsification forms latex particles in non-polar organic solvent. Long-chain alkylphenol makes phenolic resin nanoparticles and rubber matrix possess good compatibility, promotes the interaction between filler and rubber matrix, and helps phenolic resin particles to keep good dispersed state in matrix. When selecting rubber process oil (naphthenic oil, environmentally friendly aromatic oil or paraffin oil) as organic solvent, it is not necessary to remove rubber process oil, and the emulsion prepared can be directly used, on the one hand prevents phenolic resin nanoparticles from self-agglomerating before use, on the other hand reduces production cost, energy conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a particle size distribution diagram of the phenolic resin nanoparticles prepared in Example 2 of the present invention measured using dynamic light scattering, wherein the horizontal axis is a log function, with values ​​between 1 and 10, and each scale mark represents 1; and values ​​between 10 and 100, and each scale mark represents 10. DETAILED DESCRIPTION

[0058] The present invention will be further described in detail with reference to the following specific examples and accompanying drawings. The protection content of the present invention is not limited to the following examples. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be thought of by those skilled in the art are included in the present invention and are protected by the appended claims. The process, conditions, reagents, experimental methods, etc. for implementing the present invention, except for the contents specifically mentioned below, are all common knowledge and common common sense in the art and are not particularly limited in the present invention.

[0059] Reference Example 1

[0060] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0061] 1) Phenol was added to a four-necked flask equipped with a condenser and a stirring device under the action of a hydrochloric acid acid catalyst (0.5% by weight of the phenol), and a formaldehyde aqueous solution was added dropwise at a phenol:formaldehyde molar ratio of 1:0.7. The mixture was refluxed at 100° C. and stirred for 1 hour, and then distilled under reduced pressure to obtain a phenolic resin prepolymer.

[0062] (2) Add 10% of Span 40 and 50% of non-polar organic solvent aromatic oil to a four-necked flask for shear emulsification to obtain a phenolic resin prepolymer emulsion.

[0063] (3) Add hexamethoxymethyl melamine (10% by weight of the phenolic resin prepolymer) to the phenolic resin prepolymer emulsion prepared in step (2), and then perform a curing reaction at 150° C. for 3 h to obtain a phenolic resin emulsion.

[0064] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is greater than 1000 nm.

[0065] Reference Example 2

[0066] A preparation method of phenolic resin, comprising the following steps:

[0067] Under the action of hydrochloric acid acid catalyst accounting for 0.5% of the mass of phenol, phenol and cardanol are added in a four-necked flask with a condensation and stirring device in a mass ratio of 1:0.5, and formaldehyde aqueous solution is added dropwise in a molar ratio of phenol to aldehyde of 1:0.7. The mixture is refluxed at 100°C and stirred for 1 hour, and phenolic resin is obtained by vacuum distillation.

[0068] Example 1

[0069] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0070] (1) In the presence of a dodecylbenzenesulfonic acid catalyst (1% by mass of the total mass of phenol and cardanol), phenol and cardanol were added into a four-necked flask equipped with a condenser and a stirring device in a mass ratio of 1:9, and a formaldehyde aqueous solution was added dropwise in a molar ratio of phenol to aldehyde of 1:0.9. The mixture was refluxed at 100°C and stirred for 1 hour, and a phenolic resin prepolymer was obtained by distillation under reduced pressure.

[0071] (2) Add 10% of the total mass of Span 60 and 85% of the non-polar organic solvent aromatic oil into a four-necked flask and perform shear emulsification to obtain a phenolic resin prepolymer emulsion.

[0072] (3) Adding 5% by weight of hexamethoxymethyl melamine to the phenolic resin prepolymer emulsion prepared in step (2) and then curing the mixture at 150° C. for 3 h to obtain a phenolic resin emulsion.

[0073] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is about 5 nm.

[0074] Example 2

[0075] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0076] 1) In the presence of 5% oxalic acid as an acidic catalyst based on the total mass of phenol and cardanol, phenol and cardanol were added in a four-necked flask equipped with a condenser and a stirring device in a mass ratio of 1:2, and a formaldehyde aqueous solution was added dropwise in a molar ratio of phenol to aldehyde of 1:0.7. The mixture was refluxed at 100° C. and stirred for 1 hour, and then distilled under reduced pressure to obtain a phenolic resin prepolymer.

[0077] (2) Add 10 wt% of Tween 60 and 50 wt% of non-polar organic solvent aromatic oil to a four-necked flask, perform shear emulsification, and obtain a phenolic resin prepolymer emulsion.

[0078] (3) Add hexamethoxymethyl melamine (10% by weight of the phenolic resin prepolymer) to the phenolic resin prepolymer emulsion prepared in step (2), and then perform a curing reaction at 150° C. for 3 h to obtain a phenolic resin emulsion.

[0079] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is about 10 nm.

[0080] Example 3

[0081] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0082] 1) In the presence of 1% oxalic acid as an acidic catalyst based on the total mass of phenol and cardanol, phenol and cardanol were added in a four-necked flask equipped with a condenser and a stirring device in a mass ratio of 1:0.25, and a formaldehyde aqueous solution was added dropwise in a molar ratio of phenol to aldehyde of 1:0.5. The mixture was refluxed at 100° C. and stirred for 1 hour, and then distilled under reduced pressure to obtain a phenolic resin prepolymer.

[0083] (2) 4% of the total mass of the emulsion system, 1% of Tween 60, and 50% of the non-polar organic solvent aromatic oil were added to a four-necked flask and shear emulsified to obtain a phenolic resin prepolymer emulsion.

[0084] (3) Adding hexamethoxymethyl melamine accounting for 20% of the mass of the phenolic resin prepolymer to the phenolic resin prepolymer emulsion prepared in step (2), and then curing the mixture at 200° C. for 3 h to obtain the phenolic resin emulsion.

[0085] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is about 100 nm.

[0086] Example 4

[0087] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0088] 1) In the presence of an oxalic acid catalyst (10% by mass of the total mass of phenol and nonylphenol), phenol and nonylphenol were added in a four-necked flask equipped with a condenser and a stirring device at a mass ratio of 1:9, and a formaldehyde aqueous solution was added dropwise at a molar ratio of phenol to aldehyde of 1:0.7. The mixture was refluxed at 100° C. and stirred for 1 hour, and then distilled under reduced pressure to obtain a phenolic resin prepolymer.

[0089] (2) Add 0.5% of dodecylbenzenesulfonic acid and 50% of non-polar organic solvent aromatic oil to a four-necked flask, perform shear emulsification, and obtain a phenolic resin prepolymer emulsion.

[0090] (3) Adding 5% by weight of hexamethylenetetramine to the phenolic resin prepolymer emulsion prepared in step (2), and then curing the mixture at 150° C. for 3 h to obtain a phenolic resin emulsion.

[0091] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is about 1000 nm.

[0092] Example 5

[0093] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0094] 1) Phenol and cardanol were added to a four-necked flask equipped with a condenser and a stirring device in a mass ratio of 1:2 under the action of an acidic catalyst of p-toluenesulfonic acid accounting for 2% of the total mass of phenol and cardanol, and a formaldehyde aqueous solution was added dropwise in a molar ratio of phenol to aldehyde of 1:0.5. The mixture was refluxed at 100° C. and stirred for 1 hour, and then distilled under reduced pressure to obtain a phenolic resin prepolymer.

[0095] (2) Add 2% of the total mass of Span 80 and 50% of the non-polar organic solvent naphthenic oil into a four-necked flask, stir and emulsify to obtain a phenolic resin prepolymer emulsion.

[0096] (3) Adding 5% by weight of hexamethylenetetramine to the phenolic resin prepolymer emulsion prepared in step (2), and then curing the mixture at 150° C. for 3 h to obtain a phenolic resin emulsion.

[0097] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is about 500 nm.

[0098] Example 6

[0099] A preparation method of a phenolic resin emulsion, comprising the following steps:

[0100] 1) In the presence of 1% oxalic acid as an acidic catalyst based on the total mass of phenol and cardanol, phenol and cardanol were added in a four-necked flask equipped with a condenser and a stirring device in a mass ratio of 1:2, and a formaldehyde aqueous solution was added dropwise in a molar ratio of phenol to aldehyde of 1:0.7. The mixture was refluxed at 100° C. and stirred for 1 hour, and then distilled under reduced pressure to obtain a phenolic resin prepolymer.

[0101] (2) Add 5% of Span 40 and 25% of xylene, which account for 5% of the total mass of the emulsion system, into a four-necked flask and perform ultrasonic emulsification to obtain a phenolic resin prepolymer emulsion.

[0102] (3) Adding 0.5% of paraformaldehyde by weight of the phenolic resin prepolymer to the phenolic resin prepolymer emulsion prepared in step (2) and then performing a curing reaction at 100° C. for 3 h to obtain a phenolic resin emulsion.

[0103] The particle size of the phenolic resin nanoparticles in the prepared phenolic resin emulsion is about 800 nm.

[0104] Example 7 Rubber Product Application

[0105] The rubber formula is shown in Table 1. In the first step, rubber, carbon black, phenolic resin emulsion (the phenolic resin emulsion obtained in Example 6 is distilled to remove xylene and used), resin curing agent, rubber processing oil, zinc oxide, sodium stearate and antioxidant are mixed in an internal mixer and kneaded to obtain a rubber.

[0106] In the second step, the first-stage rubber is mixed with an accelerator and sulfur to obtain the final rubber.

[0107] In the third step, the rubber is vulcanized at 150°C for 30 minutes. The mechanical properties are tested according to GB / T 528-2009 and GB / T531.1-2008, and the hardness is tested according to GB / T 531.1-2008. The rubber is hot-air aged at 100°C for 24 hours. The vulcanization performance is tested using an Alpha Technologies MDR Rheometer, referring to the standards GB / T 16584-1996 and GB / T1233-2008, at 150°C for 40 minutes.

[0108] Table 1. Rubber application test formula

[0109]

[0110] The rubber performance test results are as shown in Table 2. By comparing, it is found that the unmodified phenolic resin emulsion sample prepared by Reference Example 1 has a poor reinforcing effect when applied to rubber reinforcement, and both ultimate strength and elongation at break are lower, particularly the elongation at break after aging is below 300%, which is almost indistinguishable from the blank sample. Reference Example 2 is an alkylphenol-modified phenolic resin that is not precured. After being added to the rubber, the post-curing crosslinking is performed, and the rubber product hardness, initial modulus, ultimate strength and elongation at break obtained by the result are much lower than the blank sample, indicating that the phenolic resin that is not precured does not play a reinforcing or toughening effect on rubber. The phenolic resin prepolymer emulsion prepared by Examples 1-5 of the present invention forms a phenolic resin emulsion by cross-linking curing, and is then applied to rubber reinforcement. The result shows that mechanical property significantly improves, and the elongation at break after aging is all above 300%. In particular, the particle size of the phenolic resin nanoparticles prepared in Example 2 of the present invention is about 10 nm, and the obtained rubber performance is the best. In addition, the phenolic resin emulsion prepared in Example 6 of the present invention needs to remove xylene before use. Because xylene is not a rubber operating oil, it may cause particle agglomeration and cannot achieve a good reinforcement effect when used in rubber reinforcement. This indirectly illustrates the superiority of using operating oil series solvents.

[0111] The data of experimental results and Table 2 show that the phenolic resin emulsion prepared by the present invention has improved the toughness of the rubber material, thereby strengthened the physical interaction between the phenolic resin nanoparticles and the rubber matrix, and produced a better reinforcing effect. Therefore, the phenolic resin nanoparticle emulsion prepared by the present invention can improve the modulus, strength, and elongation of the rubber material when used for rubber reinforcement, and then improve the fatigue and wear properties of the rubber.

[0112] Table 2. Rubber compound properties

[0113]

[0114] The protection content of the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention and are protected by the appended claims.

Claims

1. A phenolic resin emulsion, characterized in that The phenolic resin emulsion consists of the following components: 1) 10-70 wt% of phenolic resin nanoparticles; the phenolic resin nanoparticles are alkylphenol-modified phenolic resin nanoparticles; the particle size of the phenolic resin nanoparticles is 5-1000 nm; 2) 25-85 wt% of a solvent; the solvent is a non-polar organic solvent selected from one or a combination of naphthenic oil, toluene, xylene, trimethylbenzene, ethylbenzene, environmentally friendly aromatic oil, and paraffin oil; 3) 0.5-10 wt% of an emulsifier; the emulsifier is one or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant; Wherein, the preparation of the phenolic resin emulsion comprises the following steps: (1) In the presence of an acidic catalyst, phenol, alkylphenol and formaldehyde undergo a phenolic polycondensation reaction to obtain a phenolic resin prepolymer; wherein the molar ratio of the phenol to the alkylphenol is 1:(0.25-9); The step (1) further comprises a reduced pressure distillation step after the phenol-formaldehyde polycondensation reaction, wherein the conditions of the reduced pressure distillation are: distillation temperature 180° C., vacuum degree -99 KPa; (2) then adding an emulsifier and a solvent to the phenolic resin prepolymer for emulsification to obtain a phenolic resin prepolymer emulsion; the emulsification method is one or more of mechanical stirring, ultrasonic and shearing methods; (3) Adding a curing agent to the phenolic resin prepolymer emulsion prepared in step (2) to obtain the phenolic resin emulsion through a curing reaction.

2. The phenolic resin emulsion according to claim 1, wherein The alkylphenol is one or more alkylphenols containing 4-32 carbon atom alkyl groups or unsaturated alkyl groups.

3. A method for preparing the phenolic resin emulsion according to claim 1, characterized in that: The following steps are involved: (1) In the presence of an acidic catalyst, phenol, alkylphenol and formaldehyde undergo a phenolic polycondensation reaction to obtain a phenolic resin prepolymer; wherein the molar ratio of the phenol to the alkylphenol is 1:(0.25-9); Step (1) further comprises a step of reduced pressure distillation after the phenol-formaldehyde polycondensation reaction, wherein the conditions of the reduced pressure distillation are: distillation temperature 180° C., vacuum degree -99 KPa; (2) then adding an emulsifier and a solvent to the phenolic resin prepolymer to emulsify it to obtain a phenolic resin prepolymer emulsion; The solvent is a non-polar organic solvent selected from one or a combination of naphthenic oil, toluene, xylene, trimethylbenzene, ethylbenzene, environmentally friendly aromatic oil, and paraffin oil; the emulsification method is one or more of mechanical stirring, ultrasonic and shearing methods; (3) adding a curing agent to the phenolic resin prepolymer emulsion prepared in step (2) to carry out a curing reaction to obtain the phenolic resin emulsion; The curing agent is one or more of paraformaldehyde, hexamethylenetetramine, and hexamethoxymethyl melamine; the mass percentage of the curing agent in the phenolic resin prepolymer is 0.5-20%.

4. The method according to claim 3, wherein In step (1), the alkylphenol is one or more alkylphenols containing an alkyl group with 4 to 32 carbon atoms or an unsaturated alkyl group; and / or the acidic catalyst is one or more of oxalic acid, sulfuric acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, phosphoric acid, and hydrochloric acid; and / or the acidic catalyst accounts for 0.5-10% of the total mass of phenol and alkylphenol; and / or the molar ratio of phenol to formaldehyde is 1:(0.5-0.9); and / or the temperature of the phenol-formaldehyde polycondensation reaction is 70-100°C; and / or the time of the phenol-formaldehyde polycondensation reaction is 1-3h.

5. The method according to claim 3, wherein In step (2), the emulsifier is one or more of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.

6. The method according to claim 3, wherein In step (2), the emulsifier accounts for 0.5-10% of the total mass percentage of the phenolic resin emulsion system; and / or the solvent accounts for 25-85% of the total mass percentage of the phenolic resin emulsion system.

7. The method according to claim 3, wherein In step (3), the temperature of the curing reaction is 100-200° C.; and / or the time of the curing reaction is 1-5 hours.

8. Use of the phenolic resin emulsion according to claim 1 in rubber reinforcement.

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