A high-water-resistance spray-free black bathroom molded resin composition and a preparation method and application thereof

Abstract

The present application relates to the field of high polymer composite material, especially to a high water-resistant spray-free black bathroom mold pressing resin composition and its preparation method and application; the resin composition of the present application provides excellent molecular level hydrolysis resistance by adding neopentyl glycol unsaturated polyester resin, SiO2 hard core forms nano physical barrier to block moisture penetration, carboxyl-terminated butadiene-acrylonitrile rubber (CTBN) soft shell toughening releases internal stress + hydrogen bond strengthens interface to prevent micro-crack water penetration, and the triple protection significantly improves the cold and hot impact resistance of SMC products; the present application adds black paste to firmly anchor the black pigment in the resin network, and the surface of the mold pressing product is uniform and deep black without the need for spraying; the resin composition of the present application has suitable viscosity and stable thickening characteristics, the obtained SMC sheet has wide mold pressing active window, and the product has the advantages of high surface quality, excellent mechanical strength, good dimensional stability and the like, and fully meets the production and application requirements of high-end bathroom products.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials, and more particularly to a highly water-resistant, paint-free black molding resin composition for bathroom fixtures, its preparation method, and its application. Background Technology

[0002] Sheet molding compounds (SMCs) are widely used in the automotive, construction, and sanitary ware industries due to their high mechanical strength, good dimensional stability, and ease of molding complex components. In the high-end sanitary ware sector, consumers have extremely high requirements for the long-term durability of products (especially heat resistance and moisture resistance).

[0003] Traditional SMC products currently face the following challenges: Insufficient water resistance: Moisture easily penetrates the resin matrix, leading to plasticization and hydrolysis, causing product expansion, deformation, reduced strength, and surface blistering; Deterioration of appearance: To achieve a black appearance, traditional processes often use subsequent spraying, and the coating is prone to peeling and scratching in humid and hot environments; Process and environmental pressures: The spraying process increases energy consumption, VOC emissions, and production costs, which is not in line with the trend of green manufacturing.

[0004] Therefore, developing a paint-free SMC resin composition that integrates an inherently highly water-resistant resin matrix and a highly efficient physical water-blocking barrier is key to achieving long-lasting durability and green manufacturing of black bathroom products. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a paint-free black molding resin composition for bathroom products, which achieves a synergistic effect of internal toughening and external hydrophobicity, resulting in molded products with superior water resistance, a durable and deep black appearance, and excellent impact resistance, thus meeting the stringent requirements of bathroom products for durability, aesthetics, and environmental protection. This invention also includes the preparation method and application of the composition.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention is to provide a highly water-resistant, paint-free black molding resin composition for bathroom fixtures, comprising, by weight: 60-85 parts of water-resistant unsaturated polyester resin, 100-200 parts of inorganic filler, 3-6 parts of carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles, 15-35 parts of low-shrinkage additive, 0.8-2.5 parts of initiator, 3-8 parts of internal release agent, 2-7 parts of thickener, 5-25 parts of color paste, and 1-2 parts of polymerization inhibitor.

[0008] Preferably, the water-resistant unsaturated polyester resin includes neopentyl glycol-type unsaturated polyester resin.

[0009] Preferably, the low-shrinkage additive comprises: polystyrene;

[0010] The inorganic filler includes: 800-mesh calcium carbonate;

[0011] The initiator includes: tert-butyl peroxide / 2-ethylhexanoate;

[0012] The internal release agent includes: zinc stearate PLB;

[0013] The thickener includes: magnesium oxide paste;

[0014] The polymerization inhibitor includes p-benzoquinone.

[0015] The second aspect of the present invention is to provide a method for preparing the above-mentioned paint-free black bathroom molding resin composition, the steps of which include: sequentially adding the low-shrinkage additive, the initiator, the internal release agent and the polymerization inhibitor to the water-resistant unsaturated polyester resin, performing a first stirring, adding the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles for a first dispersion treatment, then adding the color paste and the inorganic filler for a second stirring, cooling after stirring and adding the thickener for a second dispersion treatment, thereby obtaining the paint-free black bathroom molding resin composition.

[0016] Preferably, the water-resistant unsaturated polyester resin is prepared by reacting propylene glycol, neopentyl glycol, adipic acid, and maleic anhydride.

[0017] Preferably, the preparation steps of the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles include:

[0018] S1. Disperse nano-silica in ethanol, add silane coupling agent to react, and after the reaction is completed, perform washing and drying treatments in sequence to obtain double bond functionalized nano-silica f-SiO2.

[0019] S2. The f-SiO2 is dispersed in toluene, and carboxyl-terminated butadiene-acrylonitrile rubber and initiator AIBN are added to react. After the reaction is completed, the mixture is centrifuged, washed with acetone and vacuum dried in sequence to obtain the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles CSR-SiO2.

[0020] More preferably, in step S1, the reaction temperature is 70-80℃ and the reaction time is 4-8h; in step S2, the reaction is carried out under nitrogen protection, the reaction temperature is 80-90℃ and the reaction time is 6-10h.

[0021] A third aspect of the present invention is to provide a highly water-resistant black sheet molding compound, which is made from the above-mentioned paint-free black bathroom molding resin composition.

[0022] A fourth aspect of the present invention is to provide a method for preparing the above-mentioned high water-resistant black sheet molding compound, the steps of which include: placing the paint-free black bathroom molding resin composition on the lower support film of an SMC unit, uniformly sprinkling reinforcing fibers in the paint-free black bathroom molding resin composition, covering it with the support film, and obtaining the high water-resistant black sheet molding compound after roller pressing, impregnation and curing.

[0023] The fifth aspect of the present invention is to provide a highly water-resistant bathroom product, which is made from the above-mentioned paint-free black bathroom molding resin composition or from the above-mentioned highly water-resistant black sheet molding compound.

[0024] Preferably, the highly water-resistant bathroom product includes at least one of a bathtub, an integrated shower tray, or a bathroom vanity.

[0025] The sixth aspect of the present invention is to provide a method for preparing the above-mentioned highly water-resistant sanitary ware product, the steps of which include: cutting and peeling the highly water-resistant black sheet molding compound, placing it in a mold preheated to 140-155°C, and heating it at 45-60 kg / cm². 2 The product is molded under pressure, and after demolding and trimming, the highly water-resistant sanitary ware product is obtained.

[0026] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0027] The resin composition of this invention provides excellent molecular-level hydrolysis resistance (first layer of protection) through the addition of neopentyl glycol unsaturated polyester resin, the SiO2 hard core forms a nano-physical barrier to block water penetration (second layer of protection), and the carboxyl-terminated butadiene nitrile rubber (CTBN) soft shell toughens and releases internal stress, while hydrogen bonding strengthens the interface and prevents water seepage through microcracks (third layer of protection). This triple protection significantly improves the thermal shock resistance of SMC products. Furthermore, the addition of black pigment in this invention firmly anchors the black pigment within the resin network, resulting in a uniform, deep black surface on the molded product, eliminating the need for spraying. This color exhibits excellent resistance to migration and fading in humid and hot environments. The resin composition of this invention has suitable viscosity, stable thickening properties, and good wettability to glass fibers. The resulting SMC sheet has a wide molding activity window, and the products possess advantages such as high surface quality, excellent mechanical strength, and good dimensional stability, fully meeting the production and application requirements of high-end bathroom products. Detailed Implementation

[0028] 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.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0030] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0031] Example

[0032] This embodiment provides a highly water-resistant black sheet molding compound and its preparation method, the steps of which include:

[0033] 25 parts of low-shrinkage additive, 1.0 part of initiator, 4.0 parts of internal release agent, and 1 part of polymerization inhibitor were added sequentially to 85 parts of water-resistant unsaturated polyester resin. The mixture was stirred at a low speed of 300-500 rpm until homogeneous. Then, 5 parts of carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles were added and dispersed for 50 min. Next, 5 parts of black pigment and 100 parts of 800-mesh calcium carbonate were added and stirred at a medium speed of 800-1000 rpm. After stirring, the mixture was cooled and 2.0 parts of thickener were added. The mixture was then dispersed at 800 rpm for 15 min to obtain the paint-free black bathroom molding resin composition. The paint-free black bathroom molding resin composition was placed on the lower support film of an SMC unit. Reinforcing fibers were evenly sprinkled into the paint-free black bathroom molding resin composition, and the support film was covered. After roller pressing, impregnation, and curing, the highly water-resistant black sheet molding compound was obtained.

[0034] The water-resistant unsaturated polyester resin is prepared by reacting 50 parts of propylene glycol, 70 parts of neopentyl glycol, 20 parts of adipic acid and 120 parts of maleic anhydride at 205°C.

[0035] The preparation steps of the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles include:

[0036] S1. Disperse 10 parts of nano-silica in 200 parts of ethanol, add 10 parts of silane coupling agent, react at 70°C for 8 hours, and after the reaction is completed, perform washing and drying treatments in sequence to obtain double bond functionalized nano-silica f-SiO2.

[0037] S2. Disperse 10 parts of the f-SiO2 in 100 parts of toluene, add 15 parts of carboxyl-terminated butadiene-acrylonitrile rubber and 0.5 parts of initiator AIBN, react at 80°C for 10 h under nitrogen protection, and after the reaction is completed, perform centrifugation, acetone washing and vacuum drying in sequence to obtain the carboxyl-terminated butadiene-acrylonitrile rubber modified nano silica core-shell particles CSR-SiO2.

[0038] This invention uses neopentyl glycol-type unsaturated polyester resin. The molecular center of neopentyl glycol is a quaternary carbon atom, and the two methyl groups attached to it provide a significant steric hindrance effect. This shielding effect can effectively protect adjacent ester bonds and greatly reduce the sensitivity of ester bonds to hydrolysis in humid environments.

[0039] This invention also employs carboxyl-terminated nitrile butadiene rubber modified with nano-silica core-shell particles (CSR-SiO2). The hard core layer of nano-silica (SiO2) acts as a rigid supporting framework, forming a nanoscale physical barrier within the resin matrix. This extends the penetration path of water molecules, effectively slowing down the rate and time of water penetration into the deeper parts of the material, thus enhancing the material's resistance to penetration from a physical structural perspective. The soft shell layer, composed of carboxyl-terminated nitrile butadiene rubber (CTBN), contains polar carboxyl-terminated groups. As pre-formed elastomer particles dispersed within the resin matrix, the soft shell layer absorbs and disperses internal stress through deformation under repeated impacts from hot and cold water, preventing the initiation of microcracks. The carboxyl-terminated groups (-COOH) of the shell layer are strongly polar groups that can form hydrogen bonds with ester groups and hydroxyl groups in unsaturated polyester resin and amino / epoxy groups in the coupling agent on the glass fiber surface. Although this hydrogen bonding is weaker than chemical bonding, it forms dense physical cross-linking points within the material, significantly enhancing the interfacial bonding force between the resin and filler, and between the resin and fiber, effectively resisting the interfacial penetration of water molecules.

[0040] Comparative Example 1

[0041] This comparative example provides a method for preparing a black sheet molding compound, in which the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles are replaced with conventional silica, and the rest are the same as in Example 1.

[0042] Comparative Example 2

[0043] This comparative example provides a method for preparing a black sheet molding compound, in which the water-resistant unsaturated polyester resin is replaced with a conventional unsaturated polyester resin, and all other aspects are the same as in Example 1.

[0044] Detection Examples

[0045] The performance of the black sheet molding compounds of the Examples and Comparative Examples 1-2 were tested respectively, and the results are shown in Table 1.

[0046] Table 1

[0047]

[0048] As shown in the table, after hot and cold water impacts, the color stability (low color difference) and mechanical property retention of the SMC products using the technical solution of this invention are not significantly different from those before the hot and cold water impacts. This fully verifies the effectiveness and advancement of the synergistic modification of neopentyl glycol resin and CSR-SiO2 barrier, combined with interface-enhanced coloring technology.

[0049] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A highly water-resistant, paint-free, black molding resin composition for bathroom fixtures, characterized in that, By weight, the components include: 60-85 parts of water-resistant unsaturated polyester resin, 100-200 parts of inorganic filler, 3-6 parts of carboxyl-terminated butadiene nitrile rubber modified nano silica core-shell particles, 15-35 parts of low-shrinkage additive, 0.8-2.5 parts of initiator, 3-8 parts of internal release agent, 2-7 parts of thickener, 5-25 parts of color paste, and 1-2 parts of polymerization inhibitor.

2. The paint-free black molding resin composition for bathroom fixtures according to claim 1, characterized in that, The water-resistant unsaturated polyester resin includes: neopentyl glycol type unsaturated polyester resin.

3. A method for preparing a paint-free black molding resin composition for bathroom fixtures as described in any one of claims 1-2, characterized in that, The steps include: sequentially adding the low-shrinkage additive, the initiator, the internal release agent, and the polymerization inhibitor to the water-resistant unsaturated polyester resin, performing a first stirring, adding the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles for a first dispersion treatment, then adding the color paste and the inorganic filler for a second stirring, cooling after stirring, and adding the thickener for a second dispersion treatment to obtain the paint-free black bathroom molding resin composition.

4. The preparation method according to claim 3, characterized in that, The water-resistant unsaturated polyester resin is prepared by reacting propylene glycol, neopentyl glycol, adipic acid and maleic anhydride.

5. The preparation method according to claim 3, characterized in that, The preparation steps of the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles include: S1. Disperse nano-silica in ethanol, add silane coupling agent to react, and after the reaction is completed, perform washing and drying treatments in sequence to obtain double bond functionalized nano-silica f-SiO2. S2. The f-SiO2 is dispersed in toluene, and carboxyl-terminated butadiene-acrylonitrile rubber and initiator AIBN are added to react. After the reaction is completed, the mixture is centrifuged, washed with acetone and vacuum dried in sequence to obtain the carboxyl-terminated butadiene-acrylonitrile rubber modified nano-silica core-shell particles CSR-SiO2.

6. The preparation method according to claim 5, characterized in that, In step S1, the reaction temperature is 70-80℃ and the reaction time is 4-8h; in step S2, the reaction is carried out under nitrogen protection, the reaction temperature is 80-90℃ and the reaction time is 6-10h.

7. A highly water-resistant black sheet molding compound, characterized in that, It is prepared from the paint-free black molding resin composition for bathroom fixtures as described in any one of claims 1-2.

8. A method for preparing a high water-resistant black sheet molding compound as described in claim 7, characterized in that the step... include: The paint-free black bathroom molding resin composition is placed on the lower support membrane of the SMC unit, and reinforcing fibers are evenly sprinkled in the paint-free black bathroom molding resin composition. After covering with the support membrane, the high water-resistant black sheet molding compound is obtained after roller pressing, impregnation and curing.

9. A highly water-resistant sanitary ware product, characterized in that, It is made from the paint-free black bathroom molding resin composition according to any one of claims 1-2 or from the high water-resistant black sheet molding compound according to claim 7.

10. A method for preparing a highly water-resistant sanitary ware product as described in claim 9, characterized in that, The steps include: After cutting and peeling the high water-resistant black sheet molding compound, it is placed in a mold preheated to 140-155℃ and subjected to a pressure of 45-60 kg / cm². 2 The product is molded under pressure, and after demolding and trimming, the highly water-resistant sanitary ware product is obtained.

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