Low-resistance resin applied to steel mesh printing

Abstract

A preparation method of the low-resistance resin comprises the following steps: (1) adding 22-26 parts by weight of monohydroxy acrylate, 15-20 parts by weight of butanol and 0.1-1 part by weight of a catalyst into a constant-pressure dropping funnel, slowly dropping into 43-45 parts by weight of isocyanate in a temperature range of 40-45 DEG C, and after the reaction reaches a theoretical reaction degree, adding a catalyst into the constant-pressure dropping funnel to react for 1-2 hours, thereby obtaining the low-resistance resin applied to steel mesh printing. Stopping the reaction; (2) adding 20-30 parts by weight of an unsaturated monomer and 0.5-1.5 parts by weight of a polymerization inhibitor into a product obtained after the reaction in the step (1), measuring the content of isocyanate groups, and stopping the reaction when the content is less than 2%; and (3) testing a product obtained after the reaction in the step (2), determining the solid content of the product, and adding 5-15 parts by weight of an active monomer diluent and 7-10 parts by weight of natural graphite according to the solid content to obtain the low-resistance resin applied to steel mesh printing.

Description

Technical Field

[0001] The invention belongs to the technical field of low-resistance resins, and in particular relates to a low-resistance resin used for steel screen printing. Background Art

[0002] In SMT (Surface Mount Technology), stencil printing is often used to precisely apply solder paste or red glue to the pads of a circuit board for subsequent installation of SMT components. Low-resistance resin refers to a resin material with conductivity that can provide a certain degree of conductivity while maintaining the physical properties of the resin. This material can be used where a certain degree of conductive connection is required but solder paste is not suitable, such as in some applications on flexible circuit boards (FPCs), or as a conductive path on a circuit board.

[0003] The current resins used for steel screen printing on the market have high resistivity and unsatisfactory tensile strength. Therefore, there is an urgent need for a low-resistance resin used for steel screen printing. Summary of the invention

[0004] The object of the present invention is to provide a low-resistance resin for use in stencil printing.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 22-26 parts by weight of monohydroxy acrylate, 15-20 parts by weight of butanol, and 0.1-1 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 43-45 parts by weight of isocyanate at a temperature range of 40-45°C. The dripping should be completed in 0.5-1 hour. Adjust the temperature of the oil bath to 30-50°C, react for 1-2 hours, measure the isocyanate content every hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 20 to 30 parts by weight of an unsaturated monomer and 0.5 to 1.5 parts by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 40 to 45° C. for 10 to 12 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5-15 parts by weight of active monomer diluent and 7-10 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0006] Furthermore, the isocyanate is selected from one or more of xylene diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

[0007] Furthermore, the isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.3-1.6:0.5-0.7.

[0008] Furthermore, the monohydroxy acrylate is one or more of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

[0009] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.3-1.6:0.2-0.4:1.

[0010] Furthermore, the catalyst is one of triethylamine, stannous octoate and organic bismuth.

[0011] Furthermore, the polymerization inhibitor is one of p-hydroxyanisole, hydroquinone, p-benzoquinone and phenothiazine.

[0012] Furthermore, the unsaturated monomer is selected from one or more of methyl methacrylate, isobornyl methacrylate and styrene.

[0013] Furthermore, the unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.5-0.8:1:1.3-1.6.

[0014] Furthermore, the active monomer diluent is one or more of trimethylolpropane triacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate.

[0015] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: the main feature of steel screen printing is that the product particle size is fine enough, and the mesh of the steel screen is lower than that of the traditional silk screen, which requires better wettability to the conductive agent material. The present invention uses HEMA to drip XDI and TMXDI, controls the reaction at one end, and uses methanol to react at the other end, controls the structural content of HEMA at both ends to be less than 4%, and obtains a synthetic structure; uses two or three of a variety of conventional monomers such as MMA, IBOMA, styrene, BA, etc., with 5% of the above synthetic structure, and polymerizes under the action of an initiator. Appropriate pressure is required during the polymerization process to ensure that the reaction proceeds; at the same time, the catalyst is added and the pressure distillation method is used for post-processing to ensure that only a trace amount of monomer remains in the system.

[0016] The polydispersity coefficient of the product prepared by the present invention, i.e., the ratio of Mw to Mn, is less than 1.15; the conventional uncontrolled distribution should be around 1.7. The present invention controls the narrow molecular weight distribution through process, and has good steel mesh printability. At the same time, the XDI and TMXDI structures introduced in the system have better effects in wetting silver powder and silver-coated copper powder; further improving the printing effect of the steel mesh, so that the linearity after printing is narrow, uniform and will not break. It solves the problem that during the long-term printing stage, conventional types of resins will have two extreme situations due to poor uniformity of molecular weight distribution and poor wetting with powder. Either the printed grid lines are uneven and the line width is very wide, or the printing grid is blocked and the printing line is broken after 2 hours of printing; compared with conventional materials, due to the narrow line width, the line type is triangular, and the wettability with powder is good, the line resistance and contact resistance are about 40% lower than those of traditional materials.

[0017] The present invention uses a reasonable ratio of the raw materials to form a uniform cross-linked network in the preparation process of the resin, and because it contains conductive fillers (conductive particles), the resin has a lower resistance. In addition, by optimizing the ratio of each component, the resin can have a higher tensile strength and other excellent physical properties while ensuring good conductivity. DETAILED DESCRIPTION

[0018] 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.

[0019] Example 1 This embodiment provides a low-resistance resin for steel screen printing, and the preparation method includes the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0020] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.4:0.6.

[0021] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.5:0.3:1.

[0022] The catalyst is triethylamine.

[0023] The polymerization inhibitor is p-hydroxyanisole.

[0024] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.7:1:1.5.

[0025] The reactive monomer diluent is trimethylolpropane triacrylate.

[0026] Example 2 This embodiment provides a low-resistance resin for steel screen printing, and the preparation method includes the following steps: (1) Add 22 parts by weight of monohydroxy acrylate, 15 parts by weight of butanol, and 0.1 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 43 parts by weight of isocyanate at a temperature range of 40°C. The dripping is completed in 0.5 hours. Adjust the temperature of the oil bath to 30°C, react for 1 hour, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 20 parts by weight of an unsaturated monomer and 0.5 parts by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 40° C. for 10 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 parts by weight of active monomer diluent and 7 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0027] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.3:0.5.

[0028] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.3:0.2:1.

[0029] The catalyst is triethylamine.

[0030] The polymerization inhibitor is p-hydroxyanisole.

[0031] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.5:1:1.3.

[0032] The reactive monomer diluent is trimethylolpropane triacrylate.

[0033] Example 3 This embodiment provides a low-resistance resin for steel screen printing, and the preparation method includes the following steps: (1) Add 26 parts by weight of monohydroxy acrylate, 20 parts by weight of butanol and 1 part by weight of catalyst into a constant pressure dropping funnel, and slowly drip into 45 parts by weight of isocyanate at a temperature range of 45°C. The dripping is completed in 1 hour. Adjust the temperature of the oil bath to 30-50°C. After reacting for 2 hours, measure the isocyanate content every 1 hour. When the reaction reaches the theoretical reaction degree, stop the reaction. (2) adding 30 parts by weight of an unsaturated monomer and 1.5 parts by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 45° C. for 12 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 15 parts by weight of active monomer diluent and 10 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0034] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.6:0.7.

[0035] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.6: 0.4:1.

[0036] The catalyst is triethylamine.

[0037] The polymerization inhibitor is p-hydroxyanisole.

[0038] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.8:1:1.6.

[0039] The reactive monomer diluent is trimethylolpropane triacrylate.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that the isocyanate is different.

[0041] A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0042] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1:1.

[0043] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.5:0.3:1.

[0044] The catalyst is triethylamine.

[0045] The polymerization inhibitor is p-hydroxyanisole.

[0046] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.7:1:1.5.

[0047] The reactive monomer diluent is trimethylolpropane triacrylate.

[0048] Comparative Example 2 The difference between this comparative example and Example 1 is that the monohydroxy acrylate is different.

[0049] A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0050] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.4:0.6.

[0051] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1:1:1.

[0052] The catalyst is triethylamine.

[0053] The polymerization inhibitor is p-hydroxyanisole.

[0054] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.7:1:1.5.

[0055] The reactive monomer diluent is trimethylolpropane triacrylate.

[0056] Comparative Example 3 The difference between this comparative example and Example 1 is that the saturated monomer is different.

[0057] A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0058] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.4:0.6.

[0059] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.5:0.3:1.

[0060] The catalyst is triethylamine.

[0061] The polymerization inhibitor is p-hydroxyanisole.

[0062] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 1:1:1.

[0063] The reactive monomer diluent is trimethylolpropane triacrylate.

[0064] Comparative Example 4 The difference between this comparative example and Example 1 is that the isocyanate is different.

[0065] A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0066] The isocyanate is xylene diisocyanate.

[0067] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.5:0.3:1.

[0068] The catalyst is triethylamine.

[0069] The polymerization inhibitor is p-hydroxyanisole.

[0070] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.7:1:1.5.

[0071] The reactive monomer diluent is trimethylolpropane triacrylate.

[0072] Comparative Example 5 The difference between this comparative example and Example 1 is that the monohydroxy acrylate is different.

[0073] A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0074] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.4:0.6.

[0075] The monohydroxy acrylate is hydroxyethyl (meth)acrylate.

[0076] The catalyst is triethylamine.

[0077] The polymerization inhibitor is p-hydroxyanisole.

[0078] The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.7:1:1.5.

[0079] The reactive monomer diluent is trimethylolpropane triacrylate.

[0080] Comparative Example 6 The difference between this comparative example and Example 1 is that the unsaturated monomer is different.

[0081] A low-resistance resin for steel screen printing, the preparation method comprising the following steps: (1) Add 24 parts by weight of monohydroxy acrylate, 17 parts by weight of butanol, and 0.6 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 44 parts by weight of isocyanate at a temperature range of 42°C. The dripping is completed in 0.8 hours. Adjust the temperature of the oil bath to 40°C, react for 1.6 hours, measure the isocyanate content every 1 hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 25 parts by weight of an unsaturated monomer and 1 part by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 42° C. for 11 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5 to 15 parts by weight of active monomer diluent and 8 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

[0082] The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.4:0.6.

[0083] The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.5:0.3:1.

[0084] The catalyst is triethylamine.

[0085] The polymerization inhibitor is p-hydroxyanisole.

[0086] The unsaturated monomer is methyl methacrylate.

[0087] The reactive monomer diluent is trimethylolpropane triacrylate.

[0088] Performance Testing The same volume of the low-resistance resins prepared in the above Examples 1-3 and Comparative Examples 1-6 was taken for performance testing. The specific test data are shown in Table 1.

[0089] Table 1 Performance test results

[0090] It can be seen from Table 1 that the resin described in the present invention has an excellent low resistance effect.

[0091] Comparing Example 1 with Comparative Examples 1 and 4, it can be seen that the ratio of the isocyanate described in the present invention can significantly reduce the resistance effect. Comparing Example 1 with Comparative Examples 2 and 5, it can be seen that the monohydroxy acrylate of the present invention significantly improves the tensile strength effect; comparing Example 1 with Comparative Examples 3 and 6, it can be seen that the saturated monomers described in the present invention have a certain influence on the comprehensive properties of the resin. The present invention uses a reasonable ratio of the raw materials to form a uniform cross-linked network during the preparation process, and at the same time, due to the presence of conductive fillers (natural graphite), the resin has a lower resistance. In addition, by optimizing the ratio of each component, it is possible to have a higher tensile strength and other excellent physical properties while ensuring that the resin has good conductivity. The above results show that the technical solution of the present invention can obtain a resin with a lower resistance effect.

[0092] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-resistance resin for screen printing, characterized in that: The preparation method comprises the following steps: (1) Add 22-26 parts by weight of monohydroxy acrylate, 15-20 parts by weight of butanol, and 0.1-1 parts by weight of a catalyst into a constant pressure dropping funnel, and slowly drip into 43-45 parts by weight of isocyanate at a temperature range of 40-45°C. The dripping should be completed in 0.5-1 hour. Adjust the temperature of the oil bath to 30-50°C, react for 1-2 hours, measure the isocyanate content every hour, and stop the reaction when the reaction reaches the theoretical reaction degree. (2) adding 20 to 30 parts by weight of an unsaturated monomer and 0.5 to 1.5 parts by weight of a polymerization inhibitor to the product after the reaction in step (1), reacting at 40 to 45° C. for 10 to 12 hours, measuring the isocyanate group content, and stopping the reaction when the content is less than 2%; (3) Test the product after the reaction of step (2), determine the solid content of the product, add 5-15 parts by weight of active monomer diluent and 7-10 parts by weight of natural graphite according to the solid content, and obtain a low-resistance resin for steel screen printing.

2. The low-resistance resin for screen printing according to claim 1, characterized in that: The isocyanate is selected from one or more of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate.

3. The low-resistance resin for screen printing according to claim 2, characterized in that: The isocyanate is a mixture of xylene diisocyanate, toluene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1.3-1.6:0.5-0.

7.

4. The low-resistance resin for screen printing according to claim 1, characterized in that: The monohydroxy acrylate is one or more of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

5. The low-resistance resin for screen printing according to claim 4, characterized in that: The monohydroxy acrylate is a mixture of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate in a weight ratio of 1.3-1.6:0.2-0.4:

1.

6. The low-resistance resin for screen printing according to claim 1, characterized in that: The catalyst is one of triethylamine, stannous octoate and organic bismuth.

7. The low-resistance resin for screen printing according to claim 1, characterized in that: The polymerization inhibitor is one of p-hydroxyanisole, hydroquinone, p-benzoquinone and phenothiazine.

8. The low-resistance resin for screen printing according to claim 1, characterized in that: The unsaturated monomer is selected from one or more of methyl methacrylate, isobornyl methacrylate and styrene.

9. The low-resistance resin for screen printing according to claim 8, characterized in that: The unsaturated monomer is a mixture of methyl methacrylate, isobornyl methacrylate and styrene in a weight ratio of 0.5-0.8:1:1.3-1.

6.

10. The low-resistance resin for screen printing according to claim 1, characterized in that: The active monomer diluent is one or more of trimethylolpropane triacrylate, dipropylene glycol diacrylate and tripropylene glycol diacrylate.

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