A mobile phone back cover laminate with improved puncture resistance and its preparation method

Abstract

This invention relates to the field of electronic product casing technology, specifically to a mobile phone back cover laminate with improved puncture resistance and its preparation method. The mobile phone back cover laminate comprises, from the inside out, a glass fiber prepreg layer, a puncture-resistant layer, another glass fiber prepreg layer, a base layer, a pad printing layer, an encapsulation layer, and a protective layer. The puncture-resistant layer and the glass fiber prepreg layer are cured together with epoxy resin. The epoxy resin comprises the following components by weight: 30-50 parts polyamide-modified epoxy resin, 20-40 parts phenoxy resin, 45-65 parts bisphenol A type epoxy resin, 10-15 parts isocyanate-modified epoxy resin, 6-12 parts dicyandiamide, and 5-10 parts epoxy accelerator.

Description

Technical Field

[0001] This invention relates to the field of electronic product casing technology, specifically to a mobile phone back cover laminate with improved puncture resistance and its preparation method. Background Technology

[0002] The back cover of a mobile phone is an accessory that provides some protection for the phone's internal structure. Among the many materials used for mobile phone back covers, fiberglass is widely used due to its excellent strength and rigidity. However, as an inorganic fiber bundle material, fiberglass is generally quite brittle, resulting in poor drop resistance.

[0003] To address this issue, other puncture-resistant materials are typically laminated with glass fiber. Existing fiber materials with good puncture resistance include ultra-high molecular weight polyethylene (UPE), Kevlar, and poly(p-phenylenebenzodioxazole) (PBO). UPE and PBO exhibit excellent puncture resistance, but their poor interfacial properties can easily lead to delamination in the composite material. Furthermore, laser processing results in long processing times and blackening of the cut edges, affecting the aesthetics and performance of the finished product. Kevlar's yellow color presents certain limitations in practical applications, and UPE can easily cause a decrease in the bending performance of the phone's back cover during use.

[0004] The emergence of Cordura not only improves the puncture resistance of sheet materials, but also does not reduce the bending performance of mobile phone back covers. Its original white color has a wide range of applications. After multiple tests, the material can be processed using CNC machine tools and has a certain ability to cover fabric textures without producing stripes like those of other materials.

[0005] Therefore, we propose a mobile phone back cover laminate with improved puncture resistance and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a mobile phone back cover laminate with improved puncture resistance and its preparation method, so as to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A mobile phone back cover laminate with improved puncture resistance, wherein the mobile phone back cover laminate comprises, from the inside out, a fiberglass prepreg layer, a puncture-resistant layer, another fiberglass prepreg layer, a base layer, a pad printing layer, an encapsulation layer, and a protective layer, wherein the puncture-resistant layer and the fiberglass prepreg layer are cured together with epoxy resin.

[0008] Furthermore, the glass fiber prepreg layer is composed of glass fiber cloth impregnated with epoxy resin.

[0009] Furthermore, the preparation method of the epoxy resin solution is as follows: Step A: Under nitrogen protection, acrylic rosin is heated and melted, and magnolol diglycidyl ether is added under the catalysis of triethylamine. The reaction is carried out at 120-130℃ for 6-8 hours to obtain a hydroxyl-containing epoxy compound. Step B: Under nitrogen protection, amino-terminated polydimethylsiloxane, terephthaloyl chloride and chloroform are mixed evenly, triethylamine is added, and the mixture is reacted in an ice bath for 2-4 hours. Then, a hydroxyl-containing epoxy compound is added, and the mixture is reacted at room temperature for 3-5 hours. After extraction and drying, polyamide-modified epoxy resin is obtained. Step C: Mix polyamide-modified epoxy resin, phenoxy resin, bisphenol A type epoxy resin, isocyanate-modified epoxy resin, dicyandiamide and epoxy accelerator evenly to obtain epoxy resin solution.

[0010] Further, the epoxy resin adhesive comprises the following components by weight: 30-50 parts of polyamide-modified epoxy resin, 20-40 parts of phenoxy resin, 45-65 parts of bisphenol A type epoxy resin, 10-15 parts of isocyanate-modified epoxy resin, 6-12 parts of dicyandiamide, and 5-10 parts of epoxy accelerator.

[0011] Furthermore, in step A, the molar ratio of rosin acrylate and magnolol diglycidyl ether is 1:2.

[0012] Furthermore, the preparation method of the magnolol diglycidyl ether is as follows: Under nitrogen protection, magnolol, epichlorohydrin and benzyltriethylammonium chloride were mixed evenly and reacted at 80-90℃ for 3-5 hours. The temperature was then lowered to 40-50℃, sodium hydroxide solution was added, and the reaction was continued for 1-3 hours. After filtration, washing and drying, magnolol diglycidyl ether was obtained.

[0013] Further, the mass ratio of magnolol, epichlorohydrin, benzyltriethylammonium chloride and sodium hydroxide solution is 1:(2+3):(0.05+0.08):(0.5+1.0), and the concentration of sodium hydroxide solution is 30-40 wt%.

[0014] Furthermore, in step B, the amount of triethylamine used is 1-3% of the total mass of rosin acrylate and magnolol diglycidyl ether.

[0015] Further, in step B, the molar ratio of amino-terminated polydimethylsiloxane to terephthaloyl chloride is 1:(2.0-2.2).

[0016] Furthermore, in step B, the amount of triethylamine used is 3-5% of the total mass of the amino-terminated polydimethylsiloxane and terephthaloyl chloride.

[0017] Furthermore, in step B, the molar ratio of the hydroxyl-containing epoxy compound and terephthaloyl chloride is 1:(0.5-1.0).

[0018] Furthermore, the epoxy accelerator is 2-ethyl-4-methylimidazole.

[0019] Furthermore, the puncture-resistant layer is composed of Cordura fiber woven fabric impregnated with epoxy resin.

[0020] Furthermore, the connecting layer is one of epoxy resin adhesive layer, polyurethane adhesive layer, and acrylic adhesive layer.

[0021] Furthermore, the pad printing layer is one of a textured epoxy resin layer, a polyurethane layer, or an acrylic layer.

[0022] Furthermore, the encapsulation layer is one of a transparent epoxy resin layer, a polyurethane layer, or an acrylic layer.

[0023] Furthermore, the protective layer is one of acrylic resin, polyurethane, glass, and acrylic.

[0024] A method for preparing a mobile phone back cover laminate with improved puncture resistance includes the following steps: Step S1: Apply epoxy resin solution evenly to the surface of glass fiber cloth and dry it at 110-120℃ for 10-20 minutes to obtain a glass fiber prepreg layer; Step S2: Apply epoxy resin solution evenly to the surface of Cordura fiber woven fabric and dry at 110-120℃ for 10-20 minutes to obtain a puncture-resistant layer; Step S3: The fiberglass prepreg layer, the puncture-resistant layer, and the fiberglass prepreg layer are stacked in sequence, and the laminate is obtained by hot pressing. Step S4: Sequentially apply the underlayer, pad printing layer, encapsulation layer, and protective layer to the laminate to obtain the mobile phone back cover laminate.

[0025] In the above technical solution, the puncture-resistant layer is made of Cordura fiber woven fabric, and the puncture-resistant layer and the glass fiber prepreg layer are cured together with epoxy resin. A base layer, a pad printing layer, an encapsulation layer, and a protective layer are sequentially arranged on the laminate. This improves the structure of the electronic product back cover, resulting in better toughness, stronger impact resistance, and better post-processing. The base layer acts as a connector, ensuring the pad printing layer is firmly cured onto the laminate. The encapsulation layer encapsulates the pad printing layer within the base layer, preventing interference between different layers. The protective layer has excellent wear resistance, extending the lifespan of the electronic product back cover.

[0026] Furthermore, the thickness of the glass fiber prepreg layer and the puncture-resistant layer is 0.03mm-0.20mm.

[0027] Furthermore, the temperature of the hot pressing process is 160-180℃, and the pressure is 5-10MPa.

[0028] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention relates to a mobile phone back cover laminate with improved puncture resistance and its preparation method. Under the same thickness test conditions, the puncture strength of pure Cordura fiber is better than that of pure glass fiber, and the puncture performance is better. In addition, it is lighter than aramid in terms of density. Compared with the traditional four-layer glass fiber board structure, this solution innovatively uses Cordura fiber with high puncture resistance as the middle layer to prepare a sandwich structure of "single-layer glass fiber + Cordura + single-layer glass fiber", which greatly improves the puncture force and the bending strength is relatively similar.

[0029] 2. The present invention relates to a mobile phone back cover laminate with improved puncture resistance and its preparation method. Using epichlorohydrin and the hydrophobic bio-based compound magnolol as raw materials, a bio-based epoxy resin containing a biphenyl structure, namely magnolol diglycidyl ether, is obtained, which can effectively improve the heat resistance and mechanical strength of the resin system. By controlling the molar ratio of acrylic rosin to magnolol diglycidyl ether to 1:2, a ring-opening reaction occurs to generate hydroxyl groups, resulting in a hydroxyl-containing epoxy compound. Simultaneously, a cyclic terpene structure is introduced to increase the rigidity and polarity of the resin, thereby improving the adhesion, cohesion, and heat resistance of the epoxy resin adhesive. An aromatic polyamide containing hydrophobic siloxane segments and an epoxy structure was synthesized via a one-pot polycondensation method using amino-terminated polydimethylsiloxane (ATPDMS) and hydroxyl-containing epoxy compounds. This polyamide exhibits excellent compatibility with Cordura fibers, ensuring superior interfacial compatibility and bonding strength between the Cordura fibers and the resin matrix, thus fully leveraging the high puncture strength of Cordura. The epoxy resin adhesive in this invention is prepared from polyamide-modified epoxy resin, phenoxy resin, bisphenol A type epoxy resin, isocyanate-modified epoxy resin, dicyandiamide, diaminophenyl sulfone, and an epoxy accelerator, exhibiting excellent heat resistance and adhesion. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In this embodiment, the phenoxy resin (brand name SFD-30AMX40) was purchased from Suzhou Senfida Chemical Co., Ltd.; the bisphenol A epoxy resin (brand name E-51) was purchased from Baling Petrochemical, model CYD-128; the isocyanate-modified epoxy resin (brand name Asahi Kasei A-IME AER4152); the acrylic rosin was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd.; the amino-terminated polydimethylsiloxane (model A850310) was purchased from Shanghai Maclean; the Cordura fiber woven fabric (Cordura 1000D nylon, thickness 0.1mm) was purchased from Dongguan Tongli Textile Co., Ltd.; the fiberglass cloth (alkali-free glass untwisted roving, thickness 0.1mm) was purchased from Taizhou Zhong Sheng Fiberglass Products Co., Ltd.; the underlayer was PU502; the pad printing layer was a textured epoxy resin adhesive layer, Loctite EA 3423 epoxy resin adhesive; and the encapsulation layer was a transparent epoxy resin adhesive layer, model LOCTITE EA. E-30CL; Protective layer: Acrylic resin, model FD-508PA, purchased from Suzhou Kostar Electronic Materials Co., Ltd.

[0032] Unless otherwise specified, all the following quantities are parts by weight.

[0033] Example 1: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: Step S1: Apply epoxy resin solution evenly to the surface of the fiberglass cloth (coating amount on one side is 150g / m²). 2 The fiberglass prepreg layer is obtained by drying at 110℃ for 20 minutes. Step S2: Apply epoxy resin solution evenly to the surface of Cordura fiber woven fabric (coating amount on one side is 150g / m²). 2 The puncture-resistant layer is obtained by drying at 110℃ for 20 minutes. Step S3: The fiberglass prepreg layer, the puncture-resistant layer, and the fiberglass prepreg layer are stacked in sequence, and the laminate is obtained by hot pressing (temperature 160℃, pressure 10MPa). Step S4: Sequentially apply the underlayer, pad printing layer, encapsulation layer, and protective layer to the laminate to obtain the mobile phone back cover laminate; The preparation method of epoxy resin solution is as follows: Step A: Under nitrogen protection, rosin acrylic acid was heated and melted. Magnolol diglycidyl ether was added under the catalysis of triethylamine, and the reaction was carried out at 120°C for 6 hours to obtain a hydroxyl-containing epoxy compound. The molar ratio of rosin acrylic acid to magnolol diglycidyl ether was 1:2, and the amount of triethylamine used was 1% of the total mass of rosin acrylic acid and magnolol diglycidyl ether. Step B: Under nitrogen protection, amino-terminated polydimethylsiloxane, terephthaloyl chloride, and chloroform were mixed evenly, triethylamine was added, and the mixture was reacted in an ice bath for 2 hours. Then, a hydroxyl-containing epoxy compound was added, and the mixture was reacted at room temperature for 3 hours. After extraction and drying, polyamide-modified epoxy resin was obtained. The molar ratio of amino-terminated polydimethylsiloxane to terephthaloyl chloride was 1:2, and the amount of triethylamine used was 3% of the total mass of amino-terminated polydimethylsiloxane and terephthaloyl chloride. The molar ratio of the hydroxyl-containing epoxy compound to terephthaloyl chloride was 1:0.5. Step C: Mix 30 parts of polyamide-modified epoxy resin, 20 parts of phenoxy resin, 45 parts of bisphenol A type epoxy resin, 10 parts of isocyanate-modified epoxy resin, 6 parts of dicyandiamide and 5 parts of epoxy accelerator evenly to obtain epoxy resin solution.

[0034] Example 2: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: Step S1: Apply epoxy resin solution evenly to the surface of the fiberglass cloth (coating amount on one side is 150g / m²). 2 The fiberglass prepreg layer is obtained by drying at 115℃ for 15 minutes. Step S2: Apply epoxy resin solution evenly to the surface of Cordura fiber woven fabric (coating amount on one side is 150g / m²). 2 The puncture-resistant layer is obtained by drying at 115℃ for 15 minutes. Step S3: The fiberglass prepreg layer, the puncture-resistant layer, and the fiberglass prepreg layer are stacked in sequence, and the laminate is obtained by hot pressing (temperature 170℃, pressure 8MPa). Step S4: Sequentially apply the underlayer, pad printing layer, encapsulation layer, and protective layer to the laminate to obtain the mobile phone back cover laminate; The preparation method of epoxy resin solution is as follows: Step A: Under nitrogen protection, rosin acrylic acid was heated and melted. Magnolol diglycidyl ether was added under the catalysis of triethylamine, and the reaction was carried out at 125°C for 7 hours to obtain a hydroxyl-containing epoxy compound. The molar ratio of rosin acrylic acid to magnolol diglycidyl ether was 1:2, and the amount of triethylamine used was 2% of the total mass of rosin acrylic acid and magnolol diglycidyl ether. Step B: Under nitrogen protection, amino-terminated polydimethylsiloxane, terephthaloyl chloride, and chloroform were mixed evenly, triethylamine was added, and the mixture was reacted in an ice bath for 3 hours. Then, a hydroxyl-containing epoxy compound was added, and the mixture was reacted at room temperature for 4 hours. After extraction and drying, polyamide-modified epoxy resin was obtained. The molar ratio of amino-terminated polydimethylsiloxane to terephthaloyl chloride was 1:2.1, and the amount of triethylamine used was 4% of the total mass of amino-terminated polydimethylsiloxane and terephthaloyl chloride. The molar ratio of the hydroxyl-containing epoxy compound to terephthaloyl chloride was 1:0.8. Step C: Mix 40 parts of polyamide-modified epoxy resin, 30 parts of phenoxy resin, 55 parts of bisphenol A type epoxy resin, 12 parts of isocyanate-modified epoxy resin, 10 parts of dicyandiamide and 8 parts of epoxy accelerator evenly to obtain epoxy resin solution.

[0035] Example 3: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: Step S1: Apply epoxy resin solution evenly to the surface of the fiberglass cloth (coating amount on one side is 150g / m²). 2 The fiberglass prepreg layer is obtained by drying at 120°C for 10 minutes. Step S2: Apply epoxy resin solution evenly to the surface of Cordura fiber woven fabric (coating amount on one side is 150g / m²). 2 The puncture-resistant layer is obtained by drying at 120℃ for 20 minutes. Step S3: The fiberglass prepreg layer, the puncture-resistant layer, and the fiberglass prepreg layer are stacked in sequence, and the laminate is obtained by hot pressing (temperature 180℃, pressure 5MPa). Step S4: Sequentially apply the underlayer, pad printing layer, encapsulation layer, and protective layer to the laminate to obtain the mobile phone back cover laminate; The preparation method of epoxy resin solution is as follows: Step A: Under nitrogen protection, rosin acrylic acid was heated and melted. Magnolol diglycidyl ether was added under the catalysis of triethylamine, and the reaction was carried out at 130°C for 8 hours to obtain a hydroxyl-containing epoxy compound. The molar ratio of rosin acrylic acid to magnolol diglycidyl ether was 1:2, and the amount of triethylamine used was 3% of the total mass of rosin acrylic acid and magnolol diglycidyl ether. Step B: Under nitrogen protection, amino-terminated polydimethylsiloxane, terephthaloyl chloride, and chloroform were mixed evenly, triethylamine was added, and the mixture was reacted in an ice bath for 4 hours. Then, a hydroxyl-containing epoxy compound was added, and the mixture was reacted at room temperature for 5 hours. After extraction and drying, polyamide-modified epoxy resin was obtained. The molar ratio of amino-terminated polydimethylsiloxane to terephthaloyl chloride was 1:2.2, and the amount of triethylamine used was 5% of the total mass of amino-terminated polydimethylsiloxane and terephthaloyl chloride. The molar ratio of the hydroxyl-containing epoxy compound to terephthaloyl chloride was 1:1. Step C: Mix 50 parts of polyamide-modified epoxy resin, 40 parts of phenoxy resin, 65 parts of bisphenol A type epoxy resin, 15 parts of isocyanate-modified epoxy resin, 12 parts of dicyandiamide and 10 parts of epoxy accelerator evenly to obtain epoxy resin solution.

[0036] Comparative Example 1: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: The preparation method of epoxy resin solution is as follows: 40 parts of honokiol diglycidyl ether, 30 parts of phenoxy resin, 55 parts of bisphenol A epoxy resin, 12 parts of isocyanate modified epoxy resin, 10 parts of dicyandiamide and 8 parts of epoxy accelerator were mixed evenly to obtain epoxy resin solution. Compared with Example 2, Comparative Example 1 replaced the polyamide-modified epoxy resin with the same mass of honokiol diglycidyl ether, and the other steps were the same as in Example 2.

[0037] Comparative Example 2: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: The preparation method of epoxy resin solution is as follows: Step A: Under nitrogen protection, rosin acrylic acid was heated and melted. Magnolol diglycidyl ether was added under the catalysis of triethylamine, and the reaction was carried out at 125°C for 7 hours to obtain a hydroxyl-containing epoxy compound. The molar ratio of rosin acrylic acid to magnolol diglycidyl ether was 1:2, and the amount of triethylamine used was 2% of the total mass of rosin acrylic acid and magnolol diglycidyl ether. Step B: Mix 40 parts of hydroxyl-containing epoxy compound, 30 parts of phenoxy resin, 55 parts of bisphenol A type epoxy resin, 12 parts of isocyanate modified epoxy resin, 10 parts of dicyandiamide and 8 parts of epoxy accelerator evenly to obtain epoxy resin solution. Compared with Example 2, Comparative Example 2 replaced the polyamide-modified epoxy resin with the same mass of hydroxyl-containing epoxy compound, and the other steps were the same as in Example 2.

[0038] Comparative Example 3: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: Step C: Mix 10 parts of polyamide-modified epoxy resin, 30 parts of phenoxy resin, 55 parts of bisphenol A type epoxy resin, 12 parts of isocyanate-modified epoxy resin, 10 parts of dicyandiamide and 8 parts of epoxy accelerator evenly to obtain epoxy resin solution. Compared with Example 2, Comparative Example 3 reduced the amount of polyamide-modified epoxy resin added, while the other steps were the same as in Example 2.

[0039] Comparative Example 4: A method for preparing a mobile phone back cover laminate with improved puncture resistance, comprising the following processes: Step S1: Apply epoxy resin solution evenly to the surface of the fiberglass cloth (coating amount on one side is 150g / m²). 2 The fiberglass prepreg layer is obtained by drying at 115℃ for 15 minutes. Step S2: The fiberglass prepreg layer, fiberglass prepreg layer, and fiberglass prepreg layer are stacked in sequence and the laminate is obtained by hot pressing (temperature 170℃, pressure 8MPa). Step S4: Sequentially apply the underlayer, pad printing layer, encapsulation layer, and protective layer to the laminate to obtain the mobile phone back cover laminate; Compared with Example 2, Comparative Example 4 replaced the puncture-resistant layer with a glass fiber prepreg layer, while the other steps were the same as in Example 2.

[0040] experiment: The laminates obtained in Examples 1-3 and Comparative Examples 1-4 were used to prepare samples, and their properties were tested and the test results were recorded: 1. Impact compressive strength test: The specimens were subjected to impact compressive strength test in accordance with GB / T 21239-2022 standard; 2. Water absorption test: Prepare a 50mm×10mm sample, record the mass m1 before soaking, soak it in deionized water for 24h at a test temperature of 25℃, remove it and wipe off the surface moisture, record the mass m2 after soaking, and calculate the water absorption rate.

[0041] The test results are shown in Table 1.

[0042] Table 1 Example 1 345 0.34 Example 2 353 0.30 Example 3 350 0.32 Comparative Example 1 315 0.53 Comparative Example 2 326 0.57 Comparative Example 3 331 0.45 Comparative Example 4 304 0.38 Based on the data in the table above, the following conclusions can be clearly drawn: Compared with Examples 1-3, the products obtained in Comparative Examples 1 and 2 showed a decrease in post-impact compressive strength and hydrophobicity, indicating that the polyamide-modified epoxy resin prepared in this invention, compared with honokiol diglycidyl ether, introduces hydrophobic siloxane segments and a polyamide structure, resulting in better compatibility and effectively improving the hydrophobic and mechanical properties of the material. Compared with hydroxyl-containing epoxy compounds, the polyamide-modified epoxy resin prepared in this invention has a better modification effect, thereby improving the interfacial compatibility between glass fiber cloth and Cordura woven fabric.

[0043] Compared with Examples 1-3, the product obtained in Comparative Example 3 showed a decrease in both post-impact compressive strength and hydrophobicity. This indicates that reducing the amount of polyamide-modified epoxy resin will decrease the performance of the material. This shows that the performance of the epoxy resin solution prepared by the present invention is affected by its component ratio. By selecting the component ratio within the range described above, a material with better overall performance can be prepared.

[0044] Compared with Examples 1-3, the product obtained in Comparative Example 4 showed a decrease in post-impact compressive strength, indicating that Cordura fiber woven fabric has better impact resistance than glass fiber cloth.

[0045] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A mobile phone back cover laminate with improved puncture resistance, characterized in that: The mobile phone back cover laminate consists of, from the inside out, a fiberglass prepreg layer, a puncture-resistant layer, another fiberglass prepreg layer, a base layer, a pad printing layer, an encapsulation layer, and a protective layer. The puncture-resistant layer and the fiberglass prepreg layer are cured together with epoxy resin. The preparation method of the epoxy resin solution is as follows: Step A: Under nitrogen protection, acrylic rosin is heated and melted, and magnolol diglycidyl ether is added under the catalysis of triethylamine. The reaction is carried out at 120-130℃ for 6-8 hours to obtain a hydroxyl-containing epoxy compound. Step B: Under nitrogen protection, amino-terminated polydimethylsiloxane, terephthaloyl chloride and chloroform are mixed evenly, triethylamine is added, and the mixture is reacted in an ice bath for 2-4 hours. Then, a hydroxyl-containing epoxy compound is added, and the mixture is reacted at room temperature for 3-5 hours. After extraction and drying, polyamide-modified epoxy resin is obtained. Step C: Mix polyamide-modified epoxy resin, phenoxy resin, bisphenol A type epoxy resin, isocyanate-modified epoxy resin, dicyandiamide and epoxy accelerator evenly to obtain epoxy resin solution. The epoxy resin adhesive comprises the following components by weight: 30-50 parts of polyamide-modified epoxy resin, 20-40 parts of phenoxy resin, 45-65 parts of bisphenol A type epoxy resin, 10-15 parts of isocyanate-modified epoxy resin, 6-12 parts of dicyandiamide, and 5-10 parts of epoxy accelerator.

2. The mobile phone back cover laminate with improved puncture resistance according to claim 1, characterized in that: The fiberglass prepreg layer is composed of fiberglass cloth impregnated with epoxy resin.

3. The mobile phone back cover laminate with improved puncture resistance according to claim 1, characterized in that: In step A, the molar ratio of rosin acrylate and magnolol diglycidyl ether is 1:

2.

4. A mobile phone back cover laminate with improved puncture resistance according to claim 1, characterized in that: The puncture-resistant layer is composed of Cordura fiber woven fabric impregnated with epoxy resin.

5. A mobile phone back cover laminate with improved puncture resistance according to claim 1, characterized in that: The pad printing layer is one of the following: a textured epoxy resin layer, a polyurethane layer, or an acrylic layer.

6. A mobile phone back cover laminate with improved puncture resistance according to claim 1, characterized in that: The encapsulation layer is one of a transparent epoxy resin layer, a polyurethane layer, or an acrylic layer.

7. A method for preparing a mobile phone back cover laminate with improved puncture resistance according to any one of claims 1-6, characterized in that: Includes the following steps: Step S1: Apply epoxy resin solution evenly to the surface of glass fiber cloth and dry it at 110-120℃ for 10-20 minutes to obtain a glass fiber prepreg layer; Step S2: Apply epoxy resin solution evenly to the surface of Cordura fiber woven fabric and dry at 110-120℃ for 10-20 minutes to obtain a puncture-resistant layer; Step S3: The fiberglass prepreg layer, the puncture-resistant layer, and the fiberglass prepreg layer are stacked in sequence, and the laminate is obtained by hot pressing. Step S4: Sequentially apply the underlayer, pad printing layer, encapsulation layer, and protective layer to the laminate to obtain the mobile phone back cover laminate.