the pH of the prepared collagen hydrolysate can be adjusted to 7.0 by HCl solution, and the collagen hydrolysate is concentrated to 30% of solid content by adopting evaporation and concentration equipment to prepare collagen polypeptide concentrated solution.

In some embodiments, the collagen-based adhesive is prepared by mixing the collagen hydrolysate with the glutaraldehyde according to the mass ratio of 1:0.1-0.3, adjusting the pH value to 7.2-7.5, and stirring at the temperature of 40-60 ℃ for reaction.

In this embodiment, since the collagen hydrolysate extracted from the tanning waste has a low molecular weight and a linear structure, and when the collagen hydrolysate is directly used, the bonding strength is low, and the glutaraldehyde can react with the amino group of the collagen hydrolysate to generate a cross-linked and branched structure, so that the molecular weight of the protein-based adhesive is improved, the branched structure is formed, and the bonding strength can be effectively enhanced.

In some embodiments, the step of condensing the collagen hydrolysate with oleoyl chloride to produce a protein-based surfactant comprises: mixing ethyl acetate and oleoyl chloride according to the mass ratio of 1:2 to prepare a mixed solution; mixing collagen hydrolysate with the mixed solution according to the ratio of 1: 0.1-0.15, adding strong base to maintain the pH of the condensation system at 8-9, stirring at 50-70 deg.C, and reacting to obtain protein-based surfactant.

Specifically, the protein-based surfactant is synthesized by carrying out base-catalyzed amidation reaction on oleoyl chloride and polypeptide in an organic solvent/water mixed phase, the process flow is simple, production equipment is easy to realize, condensation reaction conditions are not harsh, industrial mass production is easy to realize, and a specific reaction equation is as follows:

in this embodiment, if the condensation reaction is performed with water as a solvent, the oleoyl chloride is more prone to hydrolysis, and the reactant oleoyl chloride is consumed too much, resulting in a decrease in the condensation conversion rate; if an organic solvent (such as ethyl acetate) is added into the system, the reactant oleoyl chloride reacts at a water-organic solvent two-phase interface, so that the hydrolysis of the oleoyl chloride is reduced, the reaction selectivity is improved, and the viscosity of the reaction system is reduced. Proteolysis can generate one-NH 2 and one-COOH at the same time every cleavage of one peptide bond, and the formed polypeptide end groups have the structure of RCHNH2COOH, which can be respectively abbreviated as R-COO^- +R′NH₂ May also be abbreviated as

The protein-based surfactant prepared by the embodiment has the properties of common surfactants, namely, the wetting and leveling properties of a resin system are improved, and the protein-based surfactant can play a good lubricating role by being matched with a hot-melting component oleoyl chloride, so that the friction force of a drill point is reduced, the roughness of the hole wall can be improved, and the heat generated by friction of the drill point can be reduced.

In some specific embodiments, the composite polymer resin system is prepared by uniformly stirring 20 to 50 parts by weight of the protein-based adhesive, 2 to 8 parts by weight of the protein-based surfactant and 10 to 30 parts by weight of the water-soluble polymer resin, filtering, standing and defoaming.

In some specific embodiments, the composite polymer resin system is coated on the surface of an aluminum foil, and the aluminum foil is dried by an arch bridge type baking line, so that the environment-friendly cover plate for drilling the PCB can be prepared.

The following explains the environment-friendly PCB drilling cover plate and the preparation method thereof by specific embodiments:

example 1

(1) Preparing collagen hydrolysate:

accurately weighing a certain amount of waste leather scraps, placing the waste leather scraps in a reaction kettle, adding NaOH accounting for 8% of the mass of the leather scraps, adding water accounting for 10 times of the mass of the leather scraps, fixing the hydrolysis temperature to 80 ℃, hydrolyzing for 3 hours, carrying out the reaction under high-speed stirring, centrifuging and filtering after the reaction is finished to obtain collagen hydrolysate, wherein the reaction formula is as follows:

and (3) adjusting the pH of the hydrolysate to 7.0 by using an HCl solution, and concentrating the solution to 30% of solid content by using evaporation concentration equipment to obtain the collagen polypeptide concentrated solution.

(2) Preparation of protein-based adhesive:

and (3) placing a proper amount of collagen hydrolysate in a reaction kettle, adding glutaraldehyde with the mass being 0.17 times that of the collagen hydrolysate, adjusting the pH of a reaction system to be 7.4 by using a NaOH solution, keeping the reaction temperature at 50 ℃, and reacting for 3 hours to obtain the protein-based aqueous adhesive A1.

(3) Preparation of protein-based surfactant:

the main reaction of the step is the classical schottky-Baumann reaction, i.e. the synthesis of oleoyl chloride and polypeptide by base-catalyzed amidation reaction in an organic solvent/water mixed phase. The method has simple process flow, easy realization of production equipment, non-harsh condensation reaction conditions and easy realization of industrialized mass production, and the specific reaction equation is as follows:

and (2) placing a proper amount of collagen protein hydrolysate into a reaction kettle, continuously adding a mixed solution (mass ratio is 1:2) of ethyl acetate and oleoyl chloride with the mass being 0.12 times of that of the collagen protein hydrolysate, adding NaOH solution to neutralize HCl generated by reaction, keeping the pH value of a condensation system at about 8.5, reacting at 60 ℃ for 4 hours, and thus obtaining the protein-based surfactant B1.

(4) Preparation of the composite resin system:

sequentially putting 0.4% of sodium alginate, 9% of polyvinyl alcohol, 10% of polyethylene glycol and 1% of polyoxyethylene polyoxypropylene ether in parts by weight into 40% of distilled water at constant temperature of 25 ℃, and stirring to fully dissolve the sodium alginate, the 9% of polyvinyl alcohol and the polyethylene glycol; and then adding 36 weight percent of protein-based adhesive and 3.6 weight percent of protein-based surfactant, stirring uniformly, filtering, standing and defoaming for later use.

(5) Resin coating:

and (3) coating the composite polymer resin in the step (4) on the surface of the aluminum alloy with the thickness of 140um by a roller coating machine, wherein the thickness of the coating is 40-45um (after drying), and drying by an arch bridge type baking line to obtain the environment-friendly film-coated aluminum sheet product 1.

Example 2:

(1) preparing collagen hydrolysate:

accurately weighing a certain amount of waste leather scraps, placing the waste leather scraps in a reaction kettle, adding CaO with the mass of 10% of the waste leather scraps, adding water with the mass of 6 times of the waste leather scraps, fixing the hydrolysis temperature to 90 ℃, hydrolyzing for 5 hours, carrying out the reaction under high-speed stirring, centrifuging and filtering after the reaction is finished to obtain collagen hydrolysate, wherein the reaction formula is as follows:

(2) Preparation of protein-based adhesive:

and (3) placing a proper amount of collagen hydrolysate in a reaction kettle, adding glutaraldehyde with the mass being 0.2 times of that of the collagen hydrolysate, adjusting the pH of the reaction system to be 7.4 by using a NaOH solution, and reacting at the temperature of 50 ℃ for 3 hours to obtain the protein-based aqueous adhesive A2.

(3) Preparation of protein-based surfactant:

putting a proper amount of collagen protein hydrolysate into a reaction kettle, adding a mixed solution (mass ratio is 1:2) of ethyl acetate and oleoyl chloride with the mass being 0.14 times of that of the collagen protein hydrolysate, adding an acid-binding agent NaOH solution, neutralizing HCl generated by reaction, keeping the pH value of a condensation system at about 8.0, reacting at 60 ℃ for 4 hours, and thus obtaining the protein-based surfactant B2.

(4) Preparation of the composite resin system:

sequentially putting 0.5% carboxymethyl cellulose, 8% polyethylene glycol, 4% polyethylene oxide, 3% polyvinylpyrrolidone and 4% polyvinyl alcohol in parts by weight into constant-temperature distilled water with the temperature of 25 ℃ and the weight of 40%, and stirring to fully dissolve the materials; then adding 37 weight percent of protein-based adhesive and 3.5 weight percent of protein-based surfactant, stirring uniformly, filtering, standing and defoaming for later use.

(5) Resin coating:

Example 2

(1) Preparing collagen hydrolysate:

(2) Preparation of protein-based adhesive:

(3) Preparation of protein-based surfactant:

(5) Preparation of the composite resin system:

(5) Resin coating:

and (3) coating the composite polymer resin in the step (4) on the surface of the aluminum alloy with the thickness of 140um by a roller coating machine, wherein the thickness of the coating is 40-45um (after drying), and drying by an arch bridge type baking line to obtain the environment-friendly film-coated aluminum sheet product 2.

Example 3

(1) Preparing collagen hydrolysate:

accurately weighing a certain amount of waste leather scraps, placing the waste leather scraps into a reaction kettle, adding neutral protease accounting for 0.6 percent of the mass of the leather scraps and papain accounting for 0.4 percent of the mass of the waste leather scraps, adding water accounting for 5 times of the mass of the leather scraps, fixing the hydrolysis temperature to be 60 ℃, hydrolyzing for 4 hours, carrying out reaction under high-speed stirring, filtering hydrolysate after the reaction is finished, rapidly heating the hydrolysate to 90 ℃, and keeping the temperature for 10min to inactivate the hydrolase; and filtering the inactivated hydrolysate, and concentrating the solution to 30% of solid content by adopting evaporation concentration equipment to obtain the collagen polypeptide concentrated solution.

(6) Preparation of protein-based adhesive:

and (3) placing a proper amount of collagen hydrolysate in a reaction kettle, adding glutaraldehyde with the mass being 0.22 times that of the collagen hydrolysate, adjusting the pH of a reaction system to be 7.4 by using a NaOH solution, keeping the reaction temperature at 50 ℃, and reacting for 3 hours to obtain the protein-based aqueous adhesive A3.

(7) Preparation of protein-based surfactant:

and (2) placing a proper amount of collagen protein hydrolysate into a reaction kettle, continuously adding a mixed solution (mass ratio is 1:2) of ethyl acetate and oleoyl chloride with the mass being 0.15 times of that of the collagen protein hydrolysate, adding NaOH solution to neutralize HCl generated by reaction, keeping the pH value of a condensation system at about 8.0, reacting at 60 ℃ for 4 hours, and thus obtaining the protein-based surfactant B3.

(4) Preparation of the composite resin system:

sequentially adding 0.3% of carboxymethyl starch, 12% of polyethylene glycol, 3% of polyvinylpyrrolidone, 5% of polyacrylamide and 0.7% of polyoxyethylene polyoxypropylene ether in parts by weight into 40% of distilled water at constant temperature of 25 ℃, and stirring to fully dissolve the carboxymethyl starch, the polyethylene glycol, the polyvinylpyrrolidone, the polyacrylamide and the polyoxyethylene polyoxypropylene ether; and then adding 35% of protein-based adhesive and 4% of protein-based surfactant in parts by weight, uniformly stirring, filtering, standing and defoaming for later use.

(5) Resin coating:

and (3) coating the composite polymer resin in the step (4) on the surface of the aluminum alloy with the thickness of 140um by a roller coating machine, wherein the thickness of the coating is 40-45um (after drying), and drying by an arch bridge type baking line to obtain the environment-friendly film-coated aluminum sheet product 3.

The film-coated aluminum sheet cover plates prepared in the embodiment 1, 2 and 3 and the prior art are subjected to a 0.25mm aperture drilling test, and the drilling test results are as follows:

in conclusion, the environment-friendly PCB drilling cover plate provided by the invention comprises an aluminum foil and an environment-friendly resin layer arranged on the surface of the aluminum foil, wherein the environment-friendly resin layer is formed by reasonably matching protein-based adhesive, protein-based surfactant and water-soluble polymer resin, and the environment-friendly resin layer has moderate toughness and can play a good guiding role in the falling process of a drill point so as to improve the drilling precision; the water-soluble polymer resin and the protein-based surfactant in the environment-friendly resin layer can play roles in lubricating a drill bit, cooling a drill bit, improving the roughness of a hole wall and the like. And the environment-friendly resin layer is easy to remove the film, and most of components of the environment-friendly resin layer consist of collagen hydrolysate which is easy to biodegrade, so that the environment pollution is effectively reduced, and the environment-friendly resin layer has important significance for energy-saving and environment-friendly development.

It will be understood that the invention is not limited to the examples described above, but that modifications and variations will occur to those skilled in the art in light of the above teachings, and that all such modifications and variations are considered to be within the scope of the invention as defined by the appended claims.

Claims

1. The environment-friendly PCB drilling cover plate is characterized by comprising an aluminum foil and an environment-friendly resin layer arranged on the surface of the aluminum foil, wherein the environment-friendly resin layer is made of a composite high-molecular resin system, the composite high-molecular resin system comprises a protein-based adhesive, a protein-based surfactant and water-soluble high-molecular resin, the protein-based adhesive is prepared by performing crosslinking modification on collagen hydrolysate and glutaraldehyde, and the protein-based surfactant is prepared by performing condensation reaction on the collagen hydrolysate and oleoyl chloride; the composite polymer resin system comprises the following components in parts by weight: 20-50 parts of the protein-based adhesive, 2-8 parts of the protein-based surfactant and 10-30 parts of water-soluble polymer resin;

the step of crosslinking and modifying the collagen hydrolysate with glutaraldehyde comprises the following steps: mixing tanning waste with strong alkali solution, alkaline oxide solution or enzyme solution, and stirring at 60-100 deg.C to obtain collagen hydrolysate; mixing the collagen hydrolysate with the glutaraldehyde according to the mass ratio of 1:0.1-0.3, adjusting the pH value to 7.2-7.5, stirring at the temperature of 40-60 ℃, and reacting to obtain the protein-based adhesive;

the step of carrying out condensation reaction on the collagen hydrolysate and oleoyl chloride comprises the following steps: mixing ethyl acetate and oleoyl chloride according to the mass ratio of 1:2 to prepare a mixed solution; mixing collagen hydrolysate with the mixed solution according to the ratio of 1: 0.1-0.15, adding strong base to maintain the pH of the condensation system at 8-9, stirring at 50-70 deg.C, and reacting to obtain protein-based surfactant.

2. The environment-friendly PCB drilling cover plate according to claim 1, wherein the water-soluble polymer resin is one or more of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyacrylamide, polyvinylpyrrolidone, carboxymethyl starch, sodium alginate and carboxymethyl cellulose.

3. The cover plate for drilling of an environment-friendly PCB according to claim 1, wherein the thickness of the environment-friendly resin layer is 20-70 um.

4. The environment-friendly PCB drilling cover plate according to claim 1, wherein the thickness of the aluminum foil is 50-200 um.

5. The preparation method of the environment-friendly PCB drilling cover plate is characterized by comprising the following steps:

providing collagen hydrolysate, wherein the collagen hydrolysate comprises collagen hydrolysate;

coating the composite polymer resin system on the surface of an aluminum foil and drying to obtain the environment-friendly PCB drilling cover plate;

the step of crosslinking and modifying the collagen hydrolysate and the glutaraldehyde comprises the steps of mixing the collagen hydrolysate and the glutaraldehyde according to the mass ratio of 1:0.1-0.3, adjusting the pH value to 7.2-7.5 and stirring at the temperature of 40-60 ℃;

the step of condensing the collagen hydrolysate and the oleoyl chloride comprises the following steps: mixing ethyl acetate and oleoyl chloride according to the mass ratio of 1:2 to prepare a mixed solution; mixing collagen hydrolysate with the mixed solution according to the ratio of 1: 0.1-0.15, adding strong base to maintain the pH of the condensation system at 8-9, and stirring at 50-70 deg.C.

6. The method for preparing an environment-friendly PCB drilling cover plate according to claim 5, wherein the step of mixing the protein-based adhesive, the protein-based surfactant and the water-soluble polymer resin to prepare the composite polymer resin system comprises: