酚醛樹脂（phenolic resin）

1、酚醛樹脂（phenolic resin）1. introduction:Phenolic resin is the worlds first found and thermosetting synthetic resin industry, as raw materials, synthesis process and convenient, has the mechanical strength and good heat resistance, has excellent mechanical properties and electrical properties, has the ch

2、aracteristics of high temperature creep resistance heat resistance, flame retardant, it is still widely used in plastics, friction material, adhesive, coating, casting resin, foam and other fields. However, with the rapid development of industrial economy, more and more requirements for the properti

3、es of phenolic resin have been put forward. The reaction mechanism, structure and properties of phenolic resin are still deeply studied. Many achievements have been made in toughening, reinforcing and modifying of phenolic resin. A variety of phenolic composite materials have also been listed as hum

4、an engineering plastics series. Phenolic hydroxyl groups and methylene groups in phenolic resin structure are easily oxidized, so that their heat resistance is affected, and phenolic resin is brittle after curing. Therefore, until now, how to improve phenolic resin and apply it to industry is still

5、an important topic.2. technology development:The development of bakelite, after all to the modification of phenolic resin modified phenolic resin, now mainly in the following aspects: 1. using natural plant oil modified phenolic resin; 2. using thermal plastic resin modified phenolic resin; 3. low m

6、olecular chemical modified phenolic resin; modified phenolic resin 4. thermosetting resin; 5. rubber modified phenolic resin; 6. nano material toughened phenolic resin; 7. thermotropic liquid crystal toughened phenolic resin.2.1 natural vegetable oil modified phenolic resinThe natural plant oil modi

7、fied phenolic resin is chemically modified, flexible long chain molecular structure in vegetable oil containing double bond or conjugated triple bond, by double or triple bond phenolic resin synthesized in the reaction process, the flexible long chain into rigid phenolic molecule chain, play in the

8、role of toughening, thereby improving the phenolic resin brittle.2.1.1 cashew nut shell oil modified phenolic resinCashew nut shell oil is a by-product of cashew processing, and it is a very rich biological resource. Compared with phenol, cashew nut shell oil is much cheaper. From the structure of m

9、ain components can be seen, the characteristics of cashew oil both phenolic compounds, aliphatic compounds and flexible, with the modified phenolic resin, heat resistance and toughness were significantly improved and modified products used for friction materials, friction performance, flexible film

10、formed on the surface of carbonization process of friction easy to fall off, the friction and heat state of the material surface evenly, ensure stable friction properties. A cashew oil modified phenolic resin was synthesized by Novalac Liu Xuemei, the middle shell oil content is continuous, notched

11、impact strength and flexural strength of cashew oil modified phenolic resins and molding materials were increased by 10.7% and 14.8%. This is because the long alkane chain structure of cashew shell oil in existence, the equivalent in phenolic resin matrix are introduced in the flexible chain, to the

12、 toughening effect of phenolic resin, so as to increase the notched impact strength of molding materials prepared and bending strength.2.1.2 tung oil modified phenolic resinWhen tung oil reacted with phenol, tung oil became positive ion under the action of acid catalyst, and then reacted with phenol

13、 instead of phenol. When the ratio of phenol / tung oil is greater than 6, the interpenetrating network of phenolic resin modified by tung oil and tung oil is obtained, thus improving the toughness of phenolic resin. Shang Shibin with tung oil, bismaleimide maleic anhydride, reaction with phenolic r

14、esin, prepared Eleostearic Acid Anhydride imide phenolic resin by thermal analysis method of tung oil anhydride imide resin at 170 degrees bake for 4 h, the measured temperature index of up to 165.8 DEG C, indicating a good heat-resistant resin. Li Chao of tung oil / phenolic resin and nano SiO2 / 2

15、 phenolic / tung oil modified phenolic resin were studied. The results show that the decomposition temperature in 420 degrees Celsius above their initial heat, nano SiO2 / tung oil / phenolaldehyde system heat resistance is better than that of phenolic / tung oil, and 600 C, the former than the latt

16、er in each a focus on the loss of heat temperature has increased by 30 to 50 DEG C. A friction material made of this tung oil modified phenolic resin,Not only the friction coefficient of low temperature (100200 DEG C) remains at 0.45 0.51, but also the friction coefficient at high temperature (20030

17、0 DEG C) is up to 0.38 0.51, and the friction factor recovery performance is good, and can be maintained at more than 0.40.2.1.3 Catalpol modified phenolic resinThe phenolic resin modified by catalpa oil is a kind of resin which reacts the excess phenol with vegetable oil under acidic conditions, an

18、d then reacts with formaldehyde under alkaline condition to produce the resin. The principle is similar to that of Tung oil. It was found that the toughness and heat resistance of phenolic resin modified by catalpa oil were improved.2.1.4 linseed oil modified phenolic resinLinseed oil is eighteen ca

19、rbon three acid esters of glycerol, 3 non conjugated double bonds in the molecule, in the presence of acid and linseed oil non conjugated three ene of nuclear phenol alkylation reaction, obtained linseed oil modified phenolic resin, improve the toughness of resin. Study on phenolic resin modified by

20、 linseed oil on Yuan Xinhuas show in 320 600 DEG C linseed oil modified phenolic resin was 53.11%, while the ordinary phenolic resin 73.51% weight loss; the peak temperature of thermal decomposition, common phenolic resin 400 425 and 540 600 DEG C, and linseed oil modified is 440 470 C and 600 to 66

21、0 DEG C. Linseed oil modified phenolic resin for testing wear properties and mechanical properties of friction material showed that the modified resin adhesion and toughness are improved, the friction coefficient of the material is large and stable, low wear rate, impact strength, hardness, can be u

22、sed as matrix resin for high performance friction materials.2.2 thermoplastic resin modified phenolic resinThe blending of thermoplastic resin with phenolic resin is a simple and easy way to strengthen and toughen. Thermoplastic resins for strengthening and toughening include polyether, polyamide, p

23、olyvinyl alcohol and polyvinyl acetals.2.2.1 polyether modified phenolic resinGe Dongbiao et al modified phenolic resins with a series of different molecular weight polyethylene glycol (PEG) and active polyethers. The tensile strength and elongation at break of PEG modified phenolic resin begin to i

24、ncrease with the increase of molecular weight of PEG. When the molecular weight is 1000, the peak value is reached, and then decreases with the increase of molecular weight of PEG. For the same molecular weight PEG and active polyether, the tensile strength and elongation at break of the modified po

25、lyether are better than those of the corresponding PEG modification. Among them, the tensile strength and elongation of PEG1000 modified phenolic resin 11.546MPa and 2.358% respectively; the tensile strength and elongation of 1000 active polyether modified phenolic resin 19.032MPa and 3.779% respect

26、ively. In addition, the effect of toughening modification of active polyether is better than that of carboxyl terminated nitrile rubber. This is mainly because the hydroxyl of -NCO based active polyether resin reaction more easily and makes the introduction of flexible ether phenolic resin chain net

27、work system, and the reaction probability of hydroxy carboxyl and hydroxyl of PEG1000 resin and carboxyl terminated nitrile rubber in the very small, tend to be more physical modification.2.2.2 polyamide modified phenolic resinPolyamide has good toughness and mechanical properties. It can be co cure

28、d with phenolic resin or form a partially interpenetrating network structure to improve mechanical properties of the resin. Gao Yuejing, with three yuan of nylon modified phenolic resin was found in modified phenolic resin system, nylon as dispersed phase, phenolic resin as continuous phase copolyme

29、rization of dispersion phase particle size distribution was narrow, the mechanical properties of plastic is much better than that of blends of plastic material. The impact strength of modified nylon resin modified by unmodified resin, blending three yuan nylon and copolymerization three yuan is 57 K

30、J/m2, 47.1 KJ/m2 and 112 KJ/m2 respectively. The properties of copolymer modified resins are best due to the formation of graft phase copolymers during the synthesis and curing of modified resins. In addition, the phenolic resin toughened with nylon 3 has obtained good results. The nylon 3 molecule

31、contains amide groups which react with hydroxymethyl groups in the phenolic resin, thereby improving the impact toughness and adhesion of the phenolic resin, and maintaining the advantages of the phenolic resin. The impact strength of the resin before and after modification is 3.5 to 4.5KJ/m2 and 51

32、2 KJ/m2 respectively, and the tensile strength is 7 to 11MPa and 15 to 20MPa respectively.2.2.3 polyvinyl alcohol modified phenolic resinIn the curing process of phenolic resin, if the PVA is added, the hydroxyl groups on the polyvinyl alcohol will react with the hydroxymethyl group of the phenolic

33、polymer to form the graft copolymer. Jiang Detang in the development of a new HF- I modified epoxy resin, adding polyvinyl alcohol modifier. The results show that the addition of modifier to improve resin adhesion, improve the brittleness of phenolic resin, reduce the curing rate, thereby reducing t

34、he molding pressure, the toughening effect of phenolic resin on. However, the amount of use should not be too high, otherwise it will affect its strength.2.2.4 polyvinyl butyral modified phenolic resinThe phenolic resin modified with polyvinyl alcohol acetal is a modified phenolic resin which is app

35、lied earlier in industry. Under heating conditions, hydroxyl groups in polyvinyl acetals can undergo dehydration reactions with hydroxyl groups in phenolic resins to form graft or block copolymers. Polyvinyl alcohol acetal can improve the brittleness of phenolic resin, improve adhesion and mechanica

36、l properties, and reduce molding pressure. However, because of the introduction of longer fat chains in the structure of phenolic resins, heat resistance is affected. In order to improve the heat resistance, the polyvinyl alcohol acetal with higher heat resistance is often used, and a certain propor

37、tion of organosilicon monomer is added.2.3 low molecular chemical modified phenolic resin2.3.1 dicarboxylic acid modified phenolic resinThe molecular weight of the polymer molecules can also be used to improve the brittleness of resole resin (DA4), adipic acid, suberic acid (DA6), sebacic acid (DA8)

38、 and twelve alkyl acid (DA10) can be used to improve the brittleness of resole resin. A study found that the elasticity of dicarboxylic acid and resole resin in curing process in the reaction of ester bond formation, and also can be formed in the dibasic acid ester bond of carboxyl and hydroxyl meth

39、yl reaction into phenolic resin in brittle tensile strength of modified resin, toughness and fracture elongation increased with the increase of DA8 content, but the content in per gram of resin DA8 is over 0.014mol the performance decreased. Indicating the incorporation of flexible groups containing

40、 dibasic acid can improve the brittleness of resin. The performance of the modified resin decreased after the content of DA8 exceeded 0.014mol, indicating that more DA8 would lead to a decrease in the properties of the resin, or an unreacted DA8 would become defective in phase separation. When the p

41、henolic resin was modified with DA6 with the best molecular chain length, the tensile strength of the resin increased by 54% and the toughness increased by 64%.2.3.2 halogenated phenolic resin modified by cyanogenLinear phenolic resins can react with cyanogen halides to form phenolic three - triazin

42、e resins. Novolac resin first with cyanogen bromide and three yuan amine reaction of Novolac Cyanate Ester and Novolac Cyanate Ester in the heat under the action of the cyclization reaction of three, eventually forming three phenolic cyanate resin mesh structure. Phenol three Benzoxazine Resin has t

43、he following characteristics: the solubility of melt viscosity and gel time length, thermal oxidative stability, long-term in a low boiling solvent high low, under different curing conditions of Tg can reach 399 DEG C, polyimide system elongation and fracture mechanics with high performance, low tox

44、icity, low the flame retardancy and smoke rate. At the same time, the network structure of phenolic three triazine contains tenacity ether bond, so it has better toughness after modification.2.3.3 molybdenum modified phenolic resinMolybdenum phenolic resin (Mo2PF) is a modified phenolic resin in whi

45、ch the metal element molybdenum is chemically bonded to the main molecular chain of the phenolic resin by chemical reaction. Is the reaction by molybdate and phenol in the presence of catalyst into molybdate benzene ester, phenyl ester and molybdate addition reaction and condensation reaction with f

46、ormaldehyde, generation of phenolic resin, after cooling is a green solid, with the increase of molybdenum content in the resin resin, the initial decomposition temperature rise. Liu Xiaohong et al made aluminum phenolic resin with aluminum modifier, phenol and formaldehyde as main raw materials. Th

47、e metal molybdenum could enter the molecular chain of phenolic resin, and the great bonding O - MO - O bond could connect the benzene ring to improve the heat resistance. The thermal decomposition temperature of modified phenolic resin prepared by this method can reach 522 DEG C, and the weight loss

48、 is only 17.5% at 600 centigrade,Other properties are comparable to that of ordinary phenolic resins. In addition, the in situ polymerization method was used to improve the heat resistance, impact properties and tensile properties of the molybdenum phenolic resin /TiO2 nanocomposite by filling and m

49、odifying the surface treated nano TiO2. Zhang Shuangqing with phenol and formaldehyde in the first synthesis of hydroxymethyl phenol, and molybdic acid and hydroxymethyl by esterification reaction to obtain a new thermosetting phenolic resin and its carbon residue rate was 56.31%, the rate of 13 per

50、centage points higher than the average carbon residue of thermosetting phenolic resin.2.3.4 boron modified phenolic resinThe modification of phenolic resin with boron compounds, the change of its structure, the formation of B - O bond with higher bond energy and the formation of boron - containing t

51、hree - direction crosslink structure are one of the effective methods to improve its heat resistance. Che Jianfei by in situ synthesis method with TiO2 nanoparticles added to the boron phenolic resin, can significantly improve the heat resistance and toughness, when 5% TiO2 was added, the initial de

52、composition temperature is increased by about 150 degrees, the impact strength increased 231%. In addition, the processing technology of modified phenolic resin was also improved obviously. The introduction of boron is also beneficial to improve the flame retardancy of phenolic resin. Modified pheno

53、lic resin with boric acid and Aman Chang 16, the product still has a solid residue 75.3% in 700.8 DEG, 900 DEG C without decomposition residue is still above 64%, far higher than similar foreign products (700 C solid residue 63%). The flexural strength, flexural modulus and impact strength of the co

54、mposites obtained by Qiu Jun and other carbon fiber composite boron phenolic resins have been greatly improved. Tung oil, high performance double boron modified phenolic resin was synthesized by two steps such as Wang Manli, used it as a non asbestos braided brake belt has good friction performance

55、of matrix resin, reached the level of similar foreign products.2.3.5 amine modified phenolic resinIs the main aromatic amine compounds and total phenol and formaldehyde condensation reaction in the presence of catalyst, introducing aromatic amine unit structure and good heat resistance in the struct

56、ure of the phenolic resin, aromatic amines are commonly used melamine and melamine methylol compound and aniline. Amine modified phenolic resin, the heat resistance is improved, thermogravimetric analysis results show that aniline modified phenolic resin thermal decomposition temperature is 410 DEG

57、C, melamine modified resin is 438 DEG, 380 DEG C than the pure phenolic resin to improve its heat resistance is high, reason is the introduction of a more stable heterocyclic the construction and curing resin crosslinking density increased. The prepared friction material has good friction property a

58、t high temperature, and it is a common modification method.2.3.6 silicone modified phenolic resinSilicone modified phenolic resin has high heat resistance, thermal stability, toughness and other excellent properties, the modified method is: the phenolic resin is reacted with organosilicon compounds

59、containing alkoxy groups, forming a three-dimensional network structure containing silicon oxygen bond, there is a competitive reaction from poly phenolic reaction process, so two kinds of reactivity is the key to the success of the modified. Allyl phenolic resin reacted with organosilicon compound to form organosilicon modified phenolic resin with excellent heat resistance. The tribological properties of the