Flame-retardant resin composition and printed circuit board prepared from same

Abstract

The invention relates to the technical field of printed circuit boards, in particular to flame-retardant resin and a printed circuit board prepared from the flame-retardant resin. The preparation method comprises the following steps: enabling unsaturated double bonds of 10-undecylenic acid to react with P-H bonds of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and enabling carboxyl on the 10-undecylenic acid to react with pentaerythritol through esterification reaction, so as to obtain the flame-retardant polyol. The preparation method comprises the following steps: preparing a flame-retardant polyurethane prepolymer by taking polytetrahydrofuran ether glycol and isophorone diisocyanate as raw materials and flame-retardant polyol as a chain extender, and mixing the flame-retardant polyurethane prepolymer with epoxy resin to obtain mixed resin; mixing the mixed resin, acetone, butyl glycidyl ether, KH560 and a curing agent to obtain a flame-retardant resin composition, coating glass fiber cloth with the flame-retardant resin composition, covering copper foil after semi-curing, and performing hot-pressing curing to obtain a copper-clad plate; and finally, manufacturing a circuit pattern on the copper-clad plate, and etching to obtain the printed circuit board.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit boards, in particular to a flame retardant resin composition and a printed circuit board prepared therefrom. Background Art

[0002] Epoxy resin is a high molecular polymer that has strong metal adhesion and chemical corrosion resistance after curing, and has outstanding advantages in the preparation of printed circuit boards. However, epoxy resin also has disadvantages, such as being flammable and brittle after curing. In order to meet safety standards, flame retardants are usually added to improve its flame retardant properties.

[0003] According to the application method, flame retardants can be divided into additive flame retardants and reactive flame retardants. Additive flame retardants are easy to use and can be directly mixed with resins or rubber materials for processing. Reactive flame retardants are generally used as reactive monomers and need to be bonded to polymer chains through chemical bonds. Therefore, they have little effect on the performance of the manufactured products and have a long-lasting flame retardant effect. According to the composition, additive flame retardants mainly include inorganic flame retardants, halogen flame retardants, phosphorus flame retardants and nitrogen flame retardants. Reactive flame retardants often contain organic halogens and organic phosphorus monomers with reactive functional groups.

[0004] In traditional printed circuit boards, bromides are often used as flame retardants. However, when such flame retardants are decomposed and burned at high temperatures, they release a large amount of toxic and harmful gases and smoke. These toxic substances not only cause damage to the skin and internal organs, but also cause deformities and carcinogenesis in organisms. With the increasing demand for environmental protection, it is very necessary to modify epoxy resins, prepare a halogen-free flame retardant resin composition, and apply it to the production of printed circuit boards. Summary of the invention

[0005] The object of the present invention is to provide a flame retardant resin composition and a printed circuit board prepared therefrom, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solution: a flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0007] Step 1: Take 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10-undecenoic acid, disperse them in xylene, heat to 130-150° C., react for 5-8 hours, add pentaerythritol, keep the temperature for 1-2 hours, and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0008] Step 2: After dehydrating and cooling the raw materials at 100-120° C., isophorone diisocyanate is added to polytetramethylene glycol 2000, and the mixture is reacted at 80-90° C. in a nitrogen environment for 2-3 hours, and dimethylolpropionic acid, flame retardant polyol, and catalyst dibutyltin dilaurate are continuously added, and the mixture is heated to 80-90° C. and reacted for 2-3 hours to obtain a flame retardant polyurethane prepolymer;

[0009] Step 3: Mixing epoxy resin and flame retardant polyurethane prepolymer by weight percentage to obtain a mixed resin; mixing the mixed resin, acetone, butyl glycidyl ether, and KH560, stirring at a stirring rate of 800 to 1000 rpm for 10 to 30 minutes, adding a curing agent to obtain a flame retardant resin composition; coating the flame retardant resin composition on a glass fiber cloth, semi-curing at 100 to 120° C. for 5 to 10 minutes, covering copper foil on the semi-cured flame retardant resin composition, hot pressing and curing at 180 to 200° C. and 2 to 2.8 MPa to obtain a copper clad laminate;

[0010] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0011] Furthermore, in step 1, the molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-undecenoic acid and pentaerythritol is 1:1:(1-1.2).

[0012] Furthermore, in step 2, the amounts of the components used, by weight, are 120 to 150 parts of polytetramethylene ether glycol 2000, 80 to 105 parts of isophorone diisocyanate, 1.2 to 1.6 parts of dimethylol propionic acid, 25 to 30 parts of flame retardant polyol, and 0.8 to 1.2 parts of catalyst dibutyltin dilaurate.

[0013] Furthermore, in step 3, the contents of the components in the mixed resin are, by weight percentage, 85-93% epoxy resin and 7-15% flame retardant polyurethane prepolymer.

[0014] Furthermore, in step 3, the contents of the components in the flame retardant resin composition are, by weight, 100 to 120 parts of the flame retardant resin composition, 28 to 35 parts of acetone, 12 to 16 parts of butyl glycidyl ether, 6 to 8 parts of KH560, and 8 to 15 parts of the curing agent.

[0015] Furthermore, in step 3, the curing agent is any one of ethylenediamine, hexamethylenediamine, diethylenetriamine, maleic anhydride, and tetraethylenepentamine.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention prepares a flame retardant resin composition, firstly reacts the unsaturated double bond of 10-undecenoic acid with the PH bond of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and then reacts the carboxyl group of 10-undecenoic acid with pentaerythritol through an esterification reaction to obtain a flame retardant polyol. Since the flame retardant polyol contains multiple hydroxyl groups, it can be used as a chain extender to react with an isocyanate group, thereby being introduced into a polyurethane prepolymer to improve the flame retardant properties of the polyurethane prepolymer.

[0017] On the one hand, compared with short-chain olefinic acids such as acrylic acid, 10-undecenoic acid has a longer molecular chain segment, which can increase the molecular chain length of the flame retardant polyol. The long-chain flame retardant polyol molecules are inserted into the polyurethane molecular chain as chain extenders, which can increase the degree of freedom of the molecular chain, making it easier to deform and bend, and more flexible. On the other hand, since the biphenyl ring on the molecular structure of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide has a large steric hindrance, if the molecular chain of the olefinic acid is short, after 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide reacts with the unsaturated double bond, it will affect the efficiency of the esterification reaction between the carboxyl group and the hydroxyl group of pentaerythritol, thereby reducing the yield of the flame retardant polyol.

[0018] A flexible flame-retardant polyurethane prepolymer is blended with an epoxy resin to obtain a mixed resin, wherein the isocyanate group in the flame-retardant polyurethane prepolymer reacts with the hydroxyl group in the epoxy resin, and the epoxy resin is modified by chemical bonding. The modified epoxy resin has good flame retardant effect and toughness. In addition, it should be noted that the amount of flame-retardant polyurethane prepolymer in the mixed resin is not the more the better, and too high an amount will also reduce the mechanical properties of the cured material. Therefore, the performance is best when its total mass accounts for 7 to 15% of the flame-retardant resin composition. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Materials used in the present invention and their sources: polytetramethylene glycol 2000 comes from Deyitai New Materials, model DYT-005; epoxy resin is epoxy resin E51, comes from Baling Petrochemical, model CYD-128; curing agent is ethylenediamine, comes from Alpha Chemical.

[0021] Embodiment 1: A flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0022] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 130° C., react for 5 hours, add 1 mol of pentaerythritol, keep the temperature for 1 hour and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0023] Step 2: After dehydrating and cooling the raw materials at 100° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 80° C. in a nitrogen environment for 2 h, and 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added. 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 80° C. and reacted for 2 h to obtain a flame retardant polyurethane prepolymer;

[0024] Step 3: 85% epoxy resin and 15% flame retardant polyurethane prepolymer are mixed by weight to obtain a mixed resin; 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560 are mixed, stirred at a stirring rate of 800rpm for 10min, and 15g of a curing agent is added to obtain a flame retardant resin composition; the flame retardant resin composition is coated on a glass fiber cloth, semi-cured at 100°C for 5min, a copper foil is covered on the semi-cured flame retardant resin composition, and hot pressed and cured at 180°C and 2MPa to obtain a copper clad laminate;

[0025] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0026] Embodiment 2: A flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0027] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 140° C., react for 6 hours, add 1 mol of pentaerythritol, keep the temperature for 1.5 hours and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0028] Step 2: After dehydrating and cooling the raw materials at 110° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 85° C. in a nitrogen environment for 2.5 h, 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added, 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 85° C. and reacted for 2.5 h to obtain a flame retardant polyurethane prepolymer;

[0029] Step 3: 85% epoxy resin and 15% flame retardant polyurethane prepolymer are mixed by weight to obtain a mixed resin; 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560 are mixed, stirred at a stirring rate of 900rpm for 20min, and 15g of a curing agent is added to obtain a flame retardant resin composition; the flame retardant resin composition is coated on a glass fiber cloth, semi-cured at 115°C for 10min, copper foil is covered on the semi-cured flame retardant resin composition, and hot pressed and cured at 190°C and 2.5MPa to obtain a copper clad laminate;

[0030] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0031] Embodiment 3: A flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0032] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 145° C., react for 8 hours, add 1 mol of pentaerythritol, keep the temperature for 2 hours and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0033] Step 2: After dehydrating and cooling the raw materials at 120° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 90° C. in a nitrogen environment for 3 h, and 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added. 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 90° C. and reacted for 3 h to obtain a flame retardant polyurethane prepolymer;

[0034] Step 3: 85% epoxy resin and 15% flame retardant polyurethane prepolymer are mixed by weight to obtain a mixed resin; 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560 are mixed, stirred at a stirring rate of 1000rpm for 30min, and 15g of a curing agent is added to obtain a flame retardant resin composition; the flame retardant resin composition is coated on a glass fiber cloth, semi-cured at 120°C for 10min, copper foil is covered on the semi-cured flame retardant resin composition, and hot pressed and cured at 200°C and 2.8MPa to obtain a copper clad laminate;

[0035] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0036] Embodiment 4: A flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0037] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 130° C., react for 5 hours, add 1 mol of pentaerythritol, keep the temperature for 1 hour and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0038] Step 2: After dehydrating and cooling the raw materials at 120° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene ether glycol 2000, and the mixture was reacted at 90° C. under a nitrogen environment for 2 h, and 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added. 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 85° C. and reacted for 3 h to obtain a flame retardant polyurethane prepolymer;

[0039] Step 3: 88% epoxy resin and 12% flame retardant polyurethane prepolymer are mixed by weight to obtain a mixed resin; 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560 are mixed, stirred at a stirring rate of 850rpm for 30min, and 15g of a curing agent is added to obtain a flame retardant resin composition; the flame retardant resin composition is coated on a glass fiber cloth, semi-cured at 120°C for 5min, a copper foil is covered on the semi-cured flame retardant resin composition, and hot pressed and cured at 200°C and 2.6MPa to obtain a copper clad laminate;

[0040] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0041] Embodiment 5: A flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0042] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 150° C., react for 8 hours, add 1 mol of pentaerythritol, keep the temperature for 1 hour and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0043] Step 2: After dehydrating and cooling the raw materials at 110° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 85° C. in a nitrogen environment for 2.5 h, 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added, 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 88° C. and reacted for 2 h to obtain a flame retardant polyurethane prepolymer;

[0044] Step 3: Mix 90% epoxy resin and 10% flame retardant polyurethane prepolymer by weight to obtain a mixed resin; mix 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560, stir at a stirring rate of 1000rpm for 30min, add 15g of curing agent to obtain a flame retardant resin composition; apply the flame retardant resin composition on a glass fiber cloth, semi-cure at 110°C for 10min, cover the semi-cured flame retardant resin composition with copper foil, and hot press and cure at 200°C and 2.5MPa to obtain a copper clad laminate;

[0045] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0046] Embodiment 6: A flame retardant resin composition and a printed circuit board prepared therefrom, comprising the following steps:

[0047] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 135° C., react for 8 hours, add 1 mol of pentaerythritol, keep the temperature for 1 hour and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0048] Step 2: After dehydrating and cooling the raw materials at 105° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 90° C. in a nitrogen environment for 3 h, and 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added. 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 90° C. and reacted for 3 h to obtain a flame retardant polyurethane prepolymer;

[0049] Step 3: Mix 93% epoxy resin and 7% flame retardant polyurethane prepolymer by weight to obtain a mixed resin; mix 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560, stir at a stirring rate of 1000rpm for 25min, add 15g of curing agent to obtain a flame retardant resin composition; apply the flame retardant resin composition on a glass fiber cloth, semi-cure at 120°C for 10min, cover copper foil on the semi-cured flame retardant resin composition, and hot press and cure at 200°C and 2.8MPa to obtain a copper clad laminate;

[0050] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0051] Comparative Example 1: The epoxy resin is not modified with flame retardant polyurethane, and the other parameters are the same as those in Example 1.

[0052] Step 1: 110 g of epoxy resin, 34 g of acetone, 15 g of butyl glycidyl ether, and 8 g of KH560 were mixed, stirred at a stirring rate of 800 rpm for 10 min, and 15 g of curing agent was added to obtain a resin composition; the resin composition was coated on a glass fiber cloth, semi-cured at 100° C. for 5 min, copper foil was covered on the semi-cured resin composition, and hot pressed and cured at 180° C. and 2 MPa to obtain a copper clad laminate;

[0053] Step 2: Make a circuit pattern on the copper clad board, and electroplate copper and tin layers in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0054] Comparative Example 2: Acrylic acid was used instead of 10-undecenoic acid to prepare a flame retardant polyol, and the other parameters were the same as those in Example 2.

[0055] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of acrylic acid, disperse them in xylene, heat to 140° C., react for 6 hours, add 1 mol of pentaerythritol, keep the temperature for 1.5 hours and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0056] Step 2: After dehydrating and cooling the raw materials at 110° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 85° C. in a nitrogen environment for 2.5 h, 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added, 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 85° C. and reacted for 2.5 h to obtain a flame retardant polyurethane prepolymer;

[0057] Step 3: 85% epoxy resin and 15% flame retardant polyurethane prepolymer are mixed by weight to obtain a mixed resin; 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560 are mixed, stirred at a stirring rate of 900rpm for 20min, and 15g of a curing agent is added to obtain a flame retardant resin composition; the flame retardant resin composition is coated on a glass fiber cloth, semi-cured at 115°C for 10min, copper foil is covered on the semi-cured flame retardant resin composition, and hot pressed and cured at 190°C and 2.5MPa to obtain a copper clad laminate;

[0058] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0059] Comparative Example 3: The content of the flame retardant polyurethane prepolymer in the mixed resin was increased, and the other parameters were the same as those in Example 3.

[0060] Step 1: Take 1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1 mol of 10-undecenoic acid, disperse them in xylene, heat to 145° C., react for 8 hours, add 1 mol of pentaerythritol, keep the temperature for 2 hours and evaporate the water generated by the reaction to obtain a flame retardant polyol;

[0061] Step 2: After dehydrating and cooling the raw materials at 120° C., 105 g of isophorone diisocyanate was added to 120 g of polytetramethylene glycol 2000, and the mixture was reacted at 90° C. in a nitrogen environment for 3 h, and 1.6 g of dimethylol propionic acid and 30 g of flame retardant polyol were added. 1.2 g of catalyst dibutyltin dilaurate was added dropwise to the mixed system, and the mixture was heated to 90° C. and reacted for 3 h to obtain a flame retardant polyurethane prepolymer;

[0062] Step 3: Mix 72% epoxy resin and 28% flame retardant polyurethane prepolymer by weight to obtain a mixed resin; mix 110g of the mixed resin, 34g of acetone, 15g of butyl glycidyl ether, and 8g of KH560, stir for 30min at a stirring rate of 1000rpm, add 15g of curing agent to obtain a flame retardant resin composition; apply the flame retardant resin composition on a glass fiber cloth, semi-cure for 10min at 120°C, cover copper foil on the semi-cured flame retardant resin composition, and hot press and cure at 200°C and 2.8MPa to obtain a copper clad laminate;

[0063] Step 4: Make a circuit pattern on the copper clad board, and electroplate a copper layer and a tin layer in the circuit pattern area in sequence, burn off the tin layer to expose the electroplated copper layer; etch off the exposed copper layer, and then remove the tin layer to obtain a printed circuit board.

[0064] Experiment: Performance tests were performed on Examples 1 to 6 and Comparative Examples 1 to 3, wherein:

[0065] Flame retardancy test method: The flame retardant resin composition is cured to form a sample strip of 12 cm × 1 cm × 0.5 cm, which is burned with an open flame and the limiting oxygen index is tested;

[0066] Tensile strength and elongation at break test method: Use HY-5080 universal tensile testing machine for testing, and the test speed is 50mm / min.

[0067] project Limiting oxygen index / % Tensile strength / MPa Elongation at break / % Example 1 33 38 30.4 Example 2 33 39 32.2 Example 3 33 38 30.8 Example 4 31 37 28.2 Example 5 29 37 27.9 Example 6 27 36 27.3 Comparative Example 1 24 30 21.8 Comparative Example 2 27 31 22.4 Comparative Example 3 35 33 25.5

[0068] Conclusion: The data of Examples 1 to 6 show that the flame retardant resin composition prepared by the present invention has good performance and can be used to prepare printed circuit boards. The data of Example 1 and Comparative Example 1 show that compared with a single epoxy resin, the flame retardant resin composition prepared by the present invention has a good flame retardant effect, and at the same time, the mechanical properties after curing are better, which improves the shortcomings of poor toughness and brittleness of epoxy resin after curing; the data of Example 2 and Comparative Example 2 show that compared with acrylic acid, the use of 10-undecenoic acid can introduce long chains into the polyurethane prepolymer, thereby improving the flexibility of the prepolymer, further realizing the modification of the epoxy resin, and improving its mechanical properties. In addition, since 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide contains a biphenyl structure, and the acrylic acid molecular chain segment is short, after the two react, the carboxyl group of acrylic acid is difficult to react with pentaerythritol, resulting in a decrease in the yield of flame retardant polyols and a decrease in the flame retardant effect; the data of Example 3 and Comparative Example 3 show that when the amount of polyurethane prepolymer in the flame retardant resin composition is too high, the mechanical properties of the resin after curing are reduced.

[0069] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a flame retardant resin composition, Features: The following steps are involved: Step 1: After dehydrating and cooling the raw materials at 100-120° C., isophorone diisocyanate is added to polytetramethylene glycol 2000, and the mixture is reacted at 80-90° C. in a nitrogen environment for 2-3 hours, and dimethylolpropionic acid, flame retardant polyol, and catalyst dibutyltin dilaurate are continuously added, and the mixture is heated to 80-90° C. and reacted for 2-3 hours to obtain a flame retardant polyurethane prepolymer; Step 2: Mixing the epoxy resin and the flame retardant polyurethane prepolymer by weight to obtain a mixed resin; Step 3: Mix the mixed resin, acetone, butyl glycidyl ether and KH560, stir at a stirring rate of 800 to 1000 rpm for 10 to 30 minutes, add a curing agent, and obtain a flame retardant resin composition.

2. A method for preparing a flame retardant resin composition according to claim 1, Features: In step 1, the preparation method of flame retardant polyol is as follows: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10-undecenoic acid are dispersed in xylene, heated to 130-150° C., reacted for 5-8 hours, pentaerythritol was added, the reaction was kept warm for 1-2 hours, and the water generated by the reaction was evaporated to obtain flame retardant polyol.

3. A method for preparing a flame retardant resin composition according to claim 2, Features: The molar ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-undecenoic acid and pentaerythritol is 1:1:(1-1.2).

4. The method for preparing a flame retardant resin composition according to claim 1, Features: In step 1, the amount of each component, by weight, is 120-150 parts of polytetramethylene ether glycol 2000, 80-105 parts of isophorone diisocyanate, 1.2-1.6 parts of dimethylol propionic acid, 25-30 parts of flame retardant polyol, and 0.8-1.2 parts of catalyst dibutyltin dilaurate.

5. The method for preparing a flame retardant resin composition according to claim 1, Features: In step 2, the contents of the components in the mixed resin are, by weight percentage, 85-93% epoxy resin and 7-15% flame retardant polyurethane prepolymer.

6. The method for preparing a flame retardant resin composition according to claim 1, Features: The content of each component in the flame retardant resin composition, by weight, is 100 to 120 parts of the flame retardant resin composition, 28 to 35 parts of acetone, 12 to 16 parts of butyl glycidyl ether, 6 to 8 parts of KH560, and 8 to 15 parts of curing agent.

7. The method for preparing a flame retardant resin composition according to claim 1, Features: The curing agent is any one of ethylenediamine, hexamethylenediamine, diethylenetriamine, maleic anhydride and tetraethylenepentamine.

8. A flame retardant resin composition prepared by the method according to claims 1 to 7.

9. A printed circuit board prepared from the flame retardant resin composition according to claim 8, Features: The method for preparing a printed circuit board comprises the following steps: coating a flame retardant resin composition on a glass fiber cloth for semi-curing; coating a copper foil on the semi-cured flame retardant resin composition, and hot pressing and curing to obtain a copper clad laminate; making a circuit pattern on the copper clad laminate, and electroplating a copper layer and a tin layer in the circuit pattern area in sequence, and ablating the tin layer to expose the electroplated copper layer; etching the exposed copper layer, and then removing the tin layer to obtain a printed circuit board.

10. A printed circuit board prepared from the flame retardant resin composition according to claim 8, Features: The semi-curing temperature is 100-120°C, and the semi-curing time is 5-10 minutes; the hot pressing temperature is 180-200°C, and the pressure is 2-2.8MPa.