A transparent ABS / PMMA composite sheet and preparation method thereof

Abstract

The present application discloses a transparent ABS / PMMA composite sheet and a preparation method thereof, and relates to the field of composite sheets. The transparent ABS / PMMA composite sheet comprises a PMMA layer and an ABS layer, wherein the thickness ratio of the PMMA layer to the ABS layer is 1:(6.5-8); the raw material for preparing the PMMA layer comprises a transparent PMMA resin, and the raw material for preparing the ABS layer comprises a transparent ABS resin, an antioxidant and an anti-ultraviolet agent, and the weight ratio of the transparent ABS resin, the antioxidant and the anti-ultraviolet agent is 100:(0.8-1.2):(1-2). The present application can obtain an ABS / PMMA composite sheet for a mobile phone shell that has high transparency, good bending resistance and is easy to form by compounding the PMMA layer with the ABS layer.

Description

Technical Field

[0001] The present application relates to the field of composite sheets, and in particular to a transparent ABS / PMMA composite sheet and a preparation method thereof. Background Art

[0002] In today's rapidly developing smartphone market, the choice of mobile phone casing materials is crucial to the product's appearance, touch, durability and overall performance. Transparent PMMA resin has become one of the preferred materials for mobile phone casings due to its excellent transparency, weather resistance and chemical resistance. However, PMMA resin is brittle, has poor bending resistance and suffers from high loss during the molding process, which limits its application in mobile phone casing manufacturing. Summary of the invention

[0003] In order to improve the problems of poor bending resistance and poor formability of PMMA in the related art, the present application provides a transparent ABS / PMMA composite sheet and a preparation method thereof.

[0004] In the first aspect, the present application provides a transparent ABS / PMMA composite sheet adopting the following technical solution:

[0005] A transparent ABS / PMMA composite sheet comprises a PMMA layer and an ABS layer, wherein the thickness ratio of the PMMA layer to the ABS layer is 1:(6.5-8); the raw material for preparing the PMMA layer comprises a transparent PMMA resin, and the raw material for preparing the ABS layer comprises a transparent ABS resin, an antioxidant and an anti-ultraviolet agent, and the weight ratio of the transparent ABS resin, the antioxidant and the anti-ultraviolet agent is 100:(0.8-1.2):(1-2).

[0006] Transparent PMMA resin has excellent transparency, weather resistance and chemical stability, and is often used as a raw material for preparing mobile phone shells. However, the disadvantage of transparent PMMA resin is that it is brittle and easy to break, and has a large loss during the molding process. To solve this problem, the present application provides a transparent ABS / PMMA composite sheet, including a PMMA layer and an ABS layer. The PMMA layer has the advantages of excellent transparency, weather resistance and chemical stability of transparent PMMA resin, and the main raw material used in the ABS layer is transparent ABS resin. Transparent ABS resin is acrylonitrile-butadiene-styrene copolymer. Compared with transparent PMMA resin, it has the characteristics of good bending resistance. The present application can obtain a mobile phone shell ABS / PMMA composite sheet with high transparency, good bending resistance and easy molding by compounding the PMMA layer with the ABS layer.

[0007] In some specific embodiments, the raw materials for preparing the ABS layer also include terminal allyl epoxy polyether, aminosilane coupling agent modified nano-silica, styrene-N-phenylmaleimide copolymer and initiator, and the weight ratio of the transparent ABS resin, terminal allyl epoxy polyether, aminosilane coupling agent modified nano-silica, styrene-N-phenylmaleimide copolymer and initiator is 100: (4.8-5.5): (1.2-1.6): (0.5-1): (0.1-0.2).

[0008] The heat resistance of the ABS layer is relatively poor compared to that of the PMMA layer. In order to improve the heat resistance of the ABS layer, the ABS layer of the present application further adds terminal allyl epoxy polyether, aminosilane coupling agent modified nano-silica, and styrene-N-phenylmaleimide copolymer to modify the transparent ABS resin.

[0009] Among them, aminosilane coupling agent modified nano-silica and styrene-N-phenylmaleimide copolymer are used together to improve the heat resistance of the ABS layer. On the one hand, it can prevent the addition of too much styrene-N-phenylmaleimide copolymer from affecting the transparency of the ABS layer, and on the other hand, it can prevent the addition of too much aminosilane coupling agent modified nano-silica from affecting the dispersibility.

[0010] In addition, adding terminal allyl epoxy polyether to the transparent ABS resin for grafting reaction can further improve the dispersibility of aminosilane coupling agent modified nano-silica in the transparent ABS resin. At the same time, the terminal allyl epoxy polyether has good flexibility and will not significantly affect the toughness of the ABS / PMMA composite sheet, which is conducive to obtaining an ABS / PMMA composite sheet with good heat resistance, good bending resistance and good product stability.

[0011] In some specific embodiments, the terminal allyl epoxy polyether is at least one of terminal allyl epoxy polyoxyethylene ether, terminal allyl epoxy polyoxypropylene ether, and terminal allyl epoxy polyoxyethylene polyoxypropylene ether.

[0012] In some specific embodiments, the raw materials for preparing the PMMA layer also include modified nano-silica, and the weight ratio of the transparent PMMA resin to the modified nano-silica is 100:(0.5-1), wherein the raw materials for preparing the modified nano-silica include γ-(methacryloyloxy)propyltrimethoxysilane, methyl methacrylate, a peroxide initiator and nano-silica, and the weight ratio of γ-(methacryloyloxy)propyltrimethoxysilane, methyl methacrylate, a peroxide initiator and nano-silica is (4-6):(12-15):(0.5-1):5.

[0013] In the present application, the PMMA layer is also modified by adding γ-(methacryloyloxy)propyltrimethoxysilane and methyl methacrylate to modify the nano-silica to obtain modified nano-silica. The modified nano-silica has good dispersibility in the PMMA layer, and can further increase the hardness of the PMMA layer and improve the scratch resistance of the PMMA layer.

[0014] In some specific embodiments, the raw material for preparing the modified nano-silica further includes glycidyl methacrylate, and the weight ratio of glycidyl methacrylate to nano-silica is (4.8-5.6):5.

[0015] When preparing modified nano-silica, adding glycidyl methacrylate can improve the composite stability between the PMMA layer and the ABS layer, which is beneficial to further improve the bending resistance of the ABS / PMMA composite sheet.

[0016] In some specific embodiments, the preparation method of the modified nano-silica comprises the following steps:

[0017] S11, adding γ-(methacryloyloxy)propyltrimethoxysilane and nano-silica to a solvent, then heating to 70-75° C., stirring for reaction for 2-3 hours, then centrifugation, washing, and drying to obtain pre-modified nano-silica;

[0018] S12. Add peroxide initiator and methyl methacrylate into the solvent, stir and dissolve evenly, then add pre-modified nano-silica, and then heat to 85-90° C., stir and react for 3-4 hours, and then centrifuge, wash and dry to obtain modified nano-silica.

[0019] When preparing modified nano-silica, the nano-silica is first pre-modified with γ-(methacryloyloxy)propyltrimethoxysilane, and then the γ-(methacryloyloxy)propyltrimethoxysilane is grafted on the nano-silica, and then reacted with methyl methacrylate under the action of a peroxide initiator. Through the copolymerization reaction of methyl methacrylate and γ-(methacryloyloxy)propyltrimethoxysilane, polymethyl methacrylate is grafted on the nano-silica, which is beneficial to improving the dispersibility of the modified nano-silica in the PMMA layer.

[0020] In some specific embodiments, in step S12, glycidyl methacrylate is added before adding and modifying the nano-silica.

[0021] When preparing modified nano-silica, adding glycidyl methacrylate can improve the composite stability between the PMMA layer and the ABS layer, which is beneficial to further improve the bending resistance of the ABS / PMMA composite sheet.

[0022] In some specific embodiments, the antioxidant includes a primary antioxidant and a secondary antioxidant, and the weight ratio of the primary antioxidant to the secondary antioxidant is (1.5-2):1; wherein the primary antioxidant is at least one of antioxidant 1010 or antioxidant 1076, and the secondary antioxidant is at least one of antioxidant 168 and antioxidant DLTDP.

[0023] In the present application, the antioxidant is preferably a composition in which the weight ratio of the main antioxidant to the auxiliary antioxidant is (1.5-2):1, which is beneficial to improving the thermal stability of the ABS layer.

[0024] In some specific embodiments, the anti-ultraviolet agent is at least one of the anti-ultraviolet agent UV-P, the anti-ultraviolet agent BHT, and the anti-ultraviolet agent TBHQ.

[0025] In the second aspect, the present application provides a method for preparing a transparent ABS / PMMA composite sheet using the following technical solution:

[0026] A method for preparing a transparent ABS / PMMA composite sheet comprises the following steps:

[0027] After drying the raw materials for preparing the ABS layer, extrusion granulation is performed at a temperature of 245-255°C to obtain ABS masterbatch;

[0028] After drying the raw materials for preparing the PMMA layer, extrusion granulation is performed at a temperature of 245-255°C to obtain PMMA masterbatch;

[0029] After melting the ABS masterbatch and the PMMA masterbatch at 250-260° C. to obtain the ABS layer melt and the PMMA layer melt, the ABS layer melt and the PMMA layer melt are distributed to the die head for double-layer composite co-extrusion, followed by plasticization, calendering, pulling and cooling to obtain a transparent ABS / PMMA composite sheet.

[0030] Before preparing the transparent ABS / PMMA composite sheet, the raw materials of the ABS layer and the PMMA layer are first mixed evenly or reacted to prepare ABS masterbatch and PMMA masterbatch, which is beneficial to obtaining a transparent ABS / PMMA composite sheet with stable product performance. In addition, the ABS masterbatch and the PMMA masterbatch are prepared into a transparent ABS / PMMA composite sheet by melt co-extrusion, which is beneficial to improving the production efficiency of the transparent ABS / PMMA composite sheet.

[0031] In summary, this application at least includes the following beneficial technical effects:

[0032] (1) The present application provides a transparent ABS / PMMA composite sheet, comprising a PMMA layer and an ABS layer. The PMMA layer has the advantages of excellent transparency, weather resistance and chemical stability of transparent PMMA resin, while the main raw material used in the ABS layer is transparent ABS resin, which is acrylonitrile-butadiene-styrene copolymer. Compared with transparent PMMA resin, transparent ABS resin has the characteristics of good bending resistance. The present application can obtain an ABS / PMMA composite sheet for mobile phone shells that has high transparency, good bending resistance and is easy to form by compounding the PMMA layer with the ABS layer.

[0033] (2) The PMMA layer is modified by adding appropriate amounts of γ-(methacryloyloxy)propyltrimethoxysilane and methyl methacrylate to modify the nano-silica to obtain modified nano-silica, and the ABS layer is modified by using terminal allyl epoxy polyoxyethylene ether, amino silane coupling agent modified nano-silica, and styrene-N-phenylmaleimide copolymer to modify the transparent ABS resin to obtain the ABS masterbatch. Under the premise of maintaining the good transparency of the transparent ABS / PMMA composite sheet, the heat yellowing resistance of the transparent ABS / PMMA composite sheet can be effectively improved.

[0034] (3) The PMMA layer is modified by adding appropriate amounts of γ-(methacryloyloxy)propyltrimethoxysilane, glycidyl methacrylate, and methyl methacrylate to modify the nano-silica to obtain modified nano-silica. The ABS layer is modified by using terminal allyl epoxy polyoxyethylene ether, amino silane coupling agent modified nano-silica, and styrene-N-phenylmaleimide copolymer to modify the transparent ABS resin to obtain an ABS masterbatch. Under the premise of maintaining the good transparency and heat resistance of the transparent ABS / PMMA composite sheet, the bending resistance of the transparent ABS / PMMA composite sheet can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of a transparent ABS / PMMA composite sheet according to an embodiment of the present application.

[0036] 1. PMMA layer; 2. ABS layer. DETAILED DESCRIPTION

[0037] The present application is further described below in conjunction with specific experiments.

[0038] Preparation Example

[0039] [Preparation Example 1]

[0040] Modified nano silicon dioxide, the preparation raw materials include 4kg gamma-(methacryloyloxy)propyltrimethoxysilane, 12kg methyl methacrylate, 0.5kg benzoyl peroxide, 5kg nano silicon dioxide and 100kg ethanol.

[0041] The preparation method of modified nano silicon dioxide comprises the following steps:

[0042] S11, adding γ-(methacryloyloxy)propyltrimethoxysilane and nano-silica to 40% by weight of ethanol, then heating to 70° C., stirring and refluxing for 3 hours, then centrifugally separating, washing, and drying to obtain pre-modified nano-silica;

[0043] S12, adding benzoyl peroxide and methyl methacrylate to 60% of the weight of ethanol, stirring and dissolving evenly, adding pre-modified nano-silica, and then heating to 85° C., stirring and reacting for 4 hours, and then centrifuging, washing, and drying to obtain modified nano-silica.

[0044] [Preparation Example 2]

[0045] Modified nano silicon dioxide, the preparation raw materials include 6kg gamma-(methacryloyloxy)propyltrimethoxysilane, 15kg methyl methacrylate, 1kg benzoyl peroxide, 5kg nano silicon dioxide and 100kg ethanol.

[0046] The preparation method of modified nano silicon dioxide comprises the following steps:

[0047] S11, adding γ-(methacryloyloxy)propyltrimethoxysilane and nano-silica to 40% by weight of ethanol, then heating to 75° C., stirring and refluxing for 2 hours, then centrifugally separating, washing, and drying to obtain pre-modified nano-silica;

[0048] S12. Add benzoyl peroxide and methyl methacrylate to 60% of the weight of ethanol, stir and dissolve evenly, add pre-modified nano-silica, then heat to 90° C., stir and react for 3 hours, then centrifuge, wash and dry to obtain modified nano-silica.

[0049] [Preparation Example 3]

[0050] The modified nano-silica is different from [Preparation Example 1] in that the raw materials for preparing the modified nano-silica also include 5.2 kg of glycidyl methacrylate. In step S12, benzoyl peroxide, glycidyl methacrylate, and methyl methacrylate are added to 60% by weight of ethanol, stirred and dissolved evenly, and then the pre-modified nano-silica is added. The temperature is then raised to 85° C. and stirred for reaction for 4 hours. The mixture is then centrifuged, washed, and dried to obtain the modified nano-silica.

[0051] [Preparation Example 4]

[0052] The difference between the modified nano-silica and [Preparation Example 1] is that the raw materials for the preparation of the modified nano-silica also include 5.2 kg of methacrylic acid. In step S12, benzoyl peroxide, methacrylic acid, and methyl methacrylate are added to 60% by weight of ethanol, stirred and dissolved evenly, and then the pre-modified nano-silica is added, and then the temperature is raised to 85°C, stirred and reacted for 4 hours, and then centrifuged, washed, and dried to obtain modified nano-silica.

[0053] Example

[0054] [Example 1]

[0055] A transparent ABS / PMMA composite sheet, referring to Figure 1 , including a PMMA layer 1 and an ABS layer 2, the thickness of the PMMA layer 1 is 23 μm, and the thickness of the ABS layer 2 is 177 μm. Among them, the PMMA layer 1 is made of transparent PMMA resin, and the transparent PMMA resin is selected from Rohm Chemical 8N. The ABS layer 2 is made of a composition of transparent ABS resin, an antioxidant and an anti-ultraviolet agent, and the weight ratio of the transparent ABS resin, the antioxidant and the anti-ultraviolet agent is 100:0.8:2, and the transparent ABS resin is selected from LG Chemical TR556, the antioxidant is a composition of antioxidant 1010 and antioxidant 168, the weight ratio of antioxidant 1010 and antioxidant 168 is 1.5:1, and the anti-ultraviolet agent is anti-ultraviolet agent UV-P.

[0056] In this embodiment, the preparation method of the transparent ABS / PMMA composite sheet comprises the following steps:

[0057] After drying the transparent ABS resin, antioxidant and anti-ultraviolet agent respectively, the mixture is uniformly mixed according to the ratio, and then extruded and granulated at a temperature of 245°C to obtain ABS masterbatch;

[0058] After the transparent PMMA resin is dried, it is extruded and granulated at a temperature of 245°C to obtain PMMA masterbatch;

[0059] After the ABS masterbatch and the PMMA masterbatch are melted at 250°C to obtain the ABS layer 2 melt and the PMMA layer 1 melt, the ABS layer 2 melt and the PMMA layer 1 melt are distributed to the die head according to the ratio for double-layer composite co-extrusion, followed by plasticization, calendering, pulling and cooling to obtain a transparent ABS / PMMA composite sheet.

[0060] [Example 2]

[0061] A transparent ABS / PMMA composite sheet, referring to Figure 1, including a PMMA layer 1 and an ABS layer 2, the thickness of the PMMA layer 1 is 26μm, and the thickness of the ABS layer 2 is 174μm. Among them, the PMMA layer 1 is made of transparent PMMA resin, and the transparent PMMA resin is 8N from Rohm Chemical. The ABS layer 2 is made of a composition of transparent ABS resin, an antioxidant and an anti-ultraviolet agent, and the weight ratio of the transparent ABS resin, the antioxidant and the anti-ultraviolet agent is 100:1.2:1, and the transparent ABS resin is LG Chemical TR556, the antioxidant is a composition of antioxidant 1076 and antioxidant DLTDP, the weight ratio of antioxidant 1076 and antioxidant DLTDP is 2:1, and the anti-ultraviolet agent is anti-ultraviolet agent TBHQ.

[0062] In this embodiment, the preparation method of the transparent ABS / PMMA composite sheet comprises the following steps:

[0063] After drying the transparent ABS resin, antioxidant and anti-ultraviolet agent respectively, the mixture is uniformly mixed according to the ratio, and then extruded and granulated at a temperature of 255°C to obtain ABS masterbatch;

[0064] After the transparent PMMA resin is dried, it is extruded and granulated at a temperature of 255°C to obtain PMMA masterbatch;

[0065] After the ABS masterbatch and the PMMA masterbatch are melted at 260°C to obtain the ABS layer 2 melt and the PMMA layer 1 melt, the ABS layer 2 melt and the PMMA layer 1 melt are distributed to the die head according to the ratio for double-layer composite co-extrusion, followed by plasticization, calendering, pulling and cooling to obtain a transparent ABS / PMMA composite sheet.

[0066] [Example 3]

[0067] A transparent ABS / PMMA composite sheet, which is different from [Example 1] in that the PMMA layer 1 and the ABS layer 2 are prepared using different raw materials.

[0068] In this embodiment, the PMMA layer 1 is made of transparent PMMA resin and modified nano-silica, the weight ratio of transparent PMMA resin to modified nano-silica is 100:0.5, the transparent PMMA resin is Rohm Chemical 8N, and the modified nano-silica is the modified nano-silica prepared in [Preparation Example 1].

[0069] The ABS layer 2 is prepared from a composition of transparent ABS resin, terminal allyl epoxy polyoxyethylene polyoxypropylene ether, amino silane coupling agent modified nano silica, styrene-N-phenylmaleimide copolymer, initiator, antioxidant and anti-ultraviolet agent, and the weight ratio of the transparent ABS resin, terminal allyl epoxy polyoxyethylene ether, amino silane coupling agent modified nano silica, styrene-N-phenylmaleimide copolymer, initiator, antioxidant and anti-ultraviolet agent is 100:4.8:1.2:1:0.1:0.8:2. The transparent ABS resin is LG Chemical TR556, the terminal allyl epoxy polyoxyethylene polyoxypropylene ether has the structural formula of CH2=CHCH2O(PO)10(EO)5CH2(CHCH2)O, the aminosilane coupling agent modified nano-silica is prepared by stirring and reacting nano-silica and aminosilane coupling agent KH550-ethanol solution (the mass concentration of aminosilane coupling agent KH550 is 1%) at a weight ratio of 1:10 at 70°C, and then centrifugally drying the obtained product, the styrene-N-phenylmaleimide copolymer is selected from Nippon Electric Chemical MS-NI, the initiator is benzoyl peroxide, the antioxidant is a combination of antioxidant 1010 and antioxidant 168, the weight ratio of antioxidant 1010 to antioxidant 168 is 1.5:1, and the anti-ultraviolet agent is anti-ultraviolet agent UV-P.

[0070] In this embodiment, the preparation method of the transparent ABS / PMMA composite sheet comprises the following steps:

[0071] After drying transparent ABS resin, terminal allyl epoxy polyoxyethylene ether, aminosilane coupling agent modified nano-silica, styrene-N-phenylmaleimide copolymer, initiator, antioxidant and anti-ultraviolet agent respectively, uniformly mix according to the proportion, and then extrude and granulate at a temperature of 245° C. to obtain ABS masterbatch;

[0072] After the transparent PMMA resin and modified nano-silica are dried, they are evenly mixed according to a ratio, and then extruded and granulated at a temperature of 245°C to obtain PMMA masterbatch;

[0073] After the ABS masterbatch and the PMMA masterbatch are melted at 250°C to obtain the ABS layer 2 melt and the PMMA layer 1 melt, the ABS layer 2 melt and the PMMA layer 1 melt are distributed to the die head according to the ratio for double-layer composite co-extrusion, followed by plasticization, calendering, pulling and cooling to obtain a transparent ABS / PMMA composite sheet.

[0074] [Example 4]

[0075] A transparent ABS / PMMA composite sheet, which differs from [Example 3] in that:

[0076] In the PMMA layer 1, the weight ratio of the transparent PMMA resin to the modified nano-silica is 100:1, and the modified nano-silica is the modified nano-silica prepared in [Preparation Example 2].

[0077] In the ABS layer 2, the weight ratio of transparent ABS resin, terminal allyl epoxy polyoxyethylene ether, aminosilane coupling agent modified nano-silica, styrene-N-phenylmaleimide copolymer, initiator, antioxidant and anti-ultraviolet agent is 100:5.5:1.6:0.5:0.2:1.2:1.

[0078] [Example 5]

[0079] A transparent ABS / PMMA composite sheet, which differs from [Example 3] in that:

[0080] In the ABS layer 2, no terminal allyl epoxy polyoxyethylene polyoxypropylene ether was added.

[0081] [Example 6]

[0082] A transparent ABS / PMMA composite sheet, which differs from [Example 3] in that:

[0083] In the ABS layer 2, the aminosilane coupling agent modified nano-silica is replaced by an equal amount of γ-(methacryloyloxy)propyltrimethoxysilane modified nano-silica, and the γ-(methacryloyloxy)propyltrimethoxysilane modified nano-silica is selected from nano-silica and γ-(methacryloyloxy)propyltrimethoxysilane-ethanol solution (the mass concentration of γ-(methacryloyloxy)propyltrimethoxysilane is 1%) in a weight ratio of 1:10, stirred and reacted at 70°C, and then centrifuged to obtain a product.

[0084] [Example 7]

[0085] A transparent ABS / PMMA composite sheet, which differs from [Example 3] in that:

[0086] In the PMMA layer 1, the modified nano-silica is the modified nano-silica prepared in [Preparation Example 3].

[0087] [Example 8]

[0088] A transparent ABS / PMMA composite sheet, which differs from [Example 3] in that:

[0089] In the PMMA layer 1, the modified nano-silica is the modified nano-silica prepared in [Preparation Example 4].

[0090] Comparative Example

[0091] [Comparative Example 1]

[0092] A transparent ABS / PMMA composite sheet, which is different from [Example 1] in that: the thickness of the PMMA layer 1 is 100 μm, and the thickness of the ABS layer 2 is 100 μm.

[0093] Performance testing

[0094] 1. Light transmittance and haze: Tested in accordance with GB / T 2410-2008 “Determination of light transmittance and haze of transparent plastics”.

[0095] 2. Heat resistance: 10 transparent ABS / PMMA composite sheets in each embodiment and comparative example were randomly selected and heat treated at 60°C for 48 hours. The yellowness index of the transparent ABS / PMMA composite sheets before and after the heat treatment was tested by the transmission measurement method in GB / T 39822-2021 "Determination of the yellowness index of plastics and its change value". The difference between the average yellowness index of the transparent ABS / PMMA composite sheet after the heat treatment and the average yellowness index of the transparent ABS / PMMA composite sheet before the heat treatment was recorded.

[0096] 3. Anti-bending performance: Two groups of transparent ABS / PMMA composite sheets in each embodiment and comparative example were randomly selected, each group including 10 transparent ABS / PMMA composite sheets, one group was bent 90°, and the other group was bent 135°, wherein the greater the bending degree, the easier it is to break, and the morphology of each group of samples was recorded.

[0097] Table 1

[0098]

[0099]

[0100] Table 2

[0101]

[0102] According to Example 1 and Comparative Example 1 and in combination with the test data in Tables 1-2, it can be seen that in the transparent ABS / PMMA composite sheet, when the thickness of the PMMA layer 1 accounts for too large a proportion, the bending resistance of the transparent ABS / PMMA composite sheet is significantly reduced, which is not conducive to the flexible use and winding of the transparent ABS / PMMA composite sheet.

[0103] According to Example 1 and Example 3-4 and in combination with the test data in Table 1-2, it can be seen that when the PMMA layer 1 is modified by adding an appropriate amount of γ-(methacryloyloxy)propyltrimethoxysilane and methyl methacrylate to modify the nano-silica to obtain the modified nano-silica, and the ABS layer 2 is modified by using terminal allyl epoxy polyoxyethylene ether, amino silane coupling agent modified nano-silica, and styrene-N-phenylmaleimide copolymer to modify the transparent ABS resin to obtain the ABS masterbatch, the heat yellowing resistance of the transparent ABS / PMMA composite sheet can be effectively improved while maintaining the good transparency of the transparent ABS / PMMA composite sheet, which is conducive to obtaining an ABS / PMMA composite sheet with good heat resistance.

[0104] According to Example 3 and Example 5-6 and combined with the test data in Table 1-2, it can be seen that when the ABS masterbatch used in the ABS layer 2 is not added with terminal allyl epoxy polyoxyethylene polyoxypropylene ether or aminosilane coupling agent modified nano-silica and replaced with an equal amount of amino-free γ-(methacryloyloxy)propyltrimethoxysilane modified nano-silica, the light transmittance of the transparent ABS / PMMA composite sheet decreases and the haze increases. The reason is that the dispersion of the aminosilane coupling agent modified nano-silica in the ABS layer 2 is uneven. At the same time, compared with Example 3, the heat resistance of the transparent ABS / PMMA composite sheet is reduced.

[0105] According to Example 3 and Examples 7-8, the modified nano-silica added to the PMMA layer 1 of the three are different, among which, Example 7 further adds glycidyl methacrylate to modify the nano-silica on the basis of Example 3, and Example 8 adds methacrylic acid to modify the nano-silica on the basis of Example 3. Combined with the test data in Table 1-2, it can be seen that the transparent ABS / PMMA composite sheet in Example 7 can resist 135° bending without breaking, indicating that the better the anti-bending performance of the transparent ABS / PMMA composite sheet in Example 7, the reason may be that after adding glycidyl methacrylate, the bonding strength between the PMMA layer 1 and the ABS layer 2 is higher and more resistant to bending.

[0106] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A transparent ABS / PMMA composite sheet, characterized in that: It comprises a PMMA layer (1) and an ABS layer (2), wherein the thickness ratio of the PMMA layer (1) to the ABS layer (2) is 1:(6.5-8); The raw materials for preparing the PMMA layer (1) include a transparent PMMA resin and modified nano-silica in a weight ratio of 100:(0.5-1), wherein the raw materials for preparing the modified nano-silica include glycidyl methacrylate, γ-(methacryloyloxy)propyltrimethoxysilane, methyl methacrylate, a peroxide initiator and nano-silica in a weight ratio of (4.8-5.6):(4-6):(12-15):(0.5-1):5; when preparing the modified nano-silica, the nano-silica is first pre-modified with γ-(methacryloyloxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane is grafted onto the nano-silica, and then methyl methacrylate, glycidyl methacrylate and γ-(methacryloyloxy)propyltrimethoxysilane on the surface of the modified nano-silica are copolymerized; The raw materials for preparing the ABS layer (2) include transparent ABS resin, terminal allyl epoxy polyether, aminosilane coupling agent modified nano-silica, styrene-N-phenylmaleimide copolymer, initiator, antioxidant and anti-ultraviolet agent in a weight ratio of 100: (4.8-5.5): (1.2-1.6): (0.5-1): (0.1-0.2): (0.8-1.2): (1-2).

2. A transparent ABS / PMMA composite sheet according to claim 1, characterized in that: The terminal allyl epoxy polyether is at least one of terminal allyl epoxy polyoxyethylene ether, terminal allyl epoxy polyoxypropylene ether, and terminal allyl epoxy polyoxyethylene polyoxypropylene ether.

3. The transparent ABS / PMMA composite sheet according to claim 1, characterized in that: The preparation method of the modified nano silicon dioxide comprises the following steps: S11, adding γ-(methacryloyloxy)propyltrimethoxysilane and nano-silica to a solvent, then heating to 70-75° C., stirring for reaction for 2-3 hours, then centrifugation, washing, and drying to obtain pre-modified nano-silica; S12. Add peroxide initiator, methyl methacrylate and glycidyl methacrylate into the solvent, stir and dissolve evenly, then add pre-modified nano-silica, and then heat to 85-90° C., stir and react for 3-4 hours, and then centrifuge, wash and dry to obtain modified nano-silica.

4. The transparent ABS / PMMA composite sheet according to claim 1, characterized in that: The antioxidant includes a primary antioxidant and a secondary antioxidant, and the weight ratio of the primary antioxidant to the secondary antioxidant is (1.5-2):1; wherein the primary antioxidant is at least one of antioxidant 1010 or antioxidant 1076, and the secondary antioxidant is at least one of antioxidant 168 and antioxidant DLTDP.

5. The transparent ABS / PMMA composite sheet according to claim 1, characterized in that: The anti-ultraviolet agent is at least one of the anti-ultraviolet agent UV-P, the anti-ultraviolet agent BHT and the anti-ultraviolet agent TBHQ.

6. A method for preparing a transparent ABS / PMMA composite sheet according to any one of claims 1 to 5, characterized in that: The following steps are involved: After drying the raw materials for preparing the ABS layer (2), extrusion granulation is performed at a temperature of 245-255° C. to obtain ABS masterbatch; After drying the raw materials for preparing the PMMA layer (1), extrusion granulation is performed at a temperature of 245-255° C. to obtain PMMA masterbatch; After the ABS masterbatch and the PMMA masterbatch are melted at 250-260° C. to obtain the ABS layer (2) melt and the PMMA layer (1) melt, the ABS layer (2) melt and the PMMA layer (1) melt are distributed to a die head for double-layer composite co-extrusion, followed by plasticization, calendering, pulling, cooling and shaping, to obtain a transparent ABS / PMMA composite sheet.

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