Composite tombstone and preparation method thereof

Abstract

The invention discloses a preparation method of a composite tombstone, which comprises the following steps: firstly, performing twin-screw extrusion on unsaturated polyester resin, silane coupling agent modified quartz powder and auxiliaries at 110-120 DEG C, and performing vacuum devolatilization to prepare a resin matrix; dispersing the glass fiber and the PET fiber in the matrix through a three-section type dipping tank to obtain a modified bulk material; then pouring the agglomerate into an electroforming nickel-based stone texture imitating mold, controlling the temperature of a feeding area at 125-135 DEG C, controlling the temperature of a forming area at 140-145 DEG C and controlling the temperature of a cooling area at 75-80 DEG C, and carrying out stepped pressure forming; and finally, laser engraving characters, spraying fluorocarbon transparent paint containing nano silicon oxide, and carrying out a salt spray test. The gravestone is hollow and filled with a degradable foaming material, and a stainless steel threaded sleeve is pre-buried at the bottom; according to the composite system, the density of the tombstone is reduced to 1.5-1.8 g / cm < 3 >, the bending strength exceeds 100 MPa, the hollow structure is filled with the degradable material, the impact resistance is improved, the modified filler is resistant to ultraviolet, and uniform dispersion is ensured through the process.

Description

Technical Field

[0001] The present invention relates to a tombstone, in particular to a composite tombstone and a preparation method thereof. Background Art

[0002] At the beginning of the 20th century, tombstones were mainly made of natural stone, and craftsmen relied on chisels and grinding wheels for manual processing. Although the texture was heavy, the processing efficiency was low. In the 1970s, mechanized cutting technology became popular, and marble tombstones were mass-produced. However, the solid structure caused the weight of a single piece to exceed 300kg, and transportation accidents occurred frequently. At the beginning of the 21st century, stone mining was restricted, and after 10 years of service, 80% of outdoor tombstones had surface weathering cracks.

[0003] With the continuous development of the times, traditional stone tombstones are no longer able to meet modern needs. The manufacturing of tombstones has begun to shift towards lightweight and long-lasting materials. However, existing tombstones made of new materials not only have poor weather resistance but are also prone to cracking and fading after long-term outdoor use. Furthermore, tombstone processing relies on traditional techniques, which are inefficient and difficult to create complex shapes. Summary of the Invention

[0004] The present invention overcomes the deficiencies of the prior art and provides a composite tombstone and a preparation method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a composite tombstone, comprising the following steps:

[0006] S1. According to the mass ratio, 50%-70% of unsaturated polyester resin, 10%-30% of modified filler, and 1%-5% of additive are twin-screw extruded at 110°C-120°C, and vacuum devolatilization is performed to obtain a resin matrix;

[0007] S2, then evenly dispersing 20%-40% of glass fiber and 5%-15% of PET fiber in the resin matrix through a three-stage impregnation tank to prepare a modified pellet;

[0008] S3. Pour the modified mass into a mold and set the mold temperature to three temperature zones, i.e., 125°C to 135°C in the feeding zone, 140°C to 145°C in the molding zone, and 75°C to 80°C in the cooling zone; a stepwise pressurization method is used to shape the modified mass to obtain a composite tombstone;

[0009] S4. Use fiber laser to engrave text on the surface of the composite tombstone, spray fluorocarbon transparent paint at the same time, and conduct change test through salt spray test.

[0010] In a preferred embodiment of the present invention, the modified filler is quartz powder modified by a silane coupling agent, and 0.3% to 0.5% of nano-titanium dioxide and 0.1% to 0.3% of a hindered amine light stabilizer are added to the modified filler.

[0011] In a preferred embodiment of the present invention, the volume fraction ratio of the glass fiber to the PET fiber is 1:3-4, and the PET fiber is polyethylene terephthalate.

[0012] In a preferred embodiment of the present invention, in the step-by-step pressurization method, the step-by-step change trend of the pressure value is 0 45MPa~55MPa 75MPa~85MPa 40MPa~55MPa, holding time 280s~300s.

[0013] In a preferred embodiment of the present invention, in the stepped pressurization method, the holding time of the stepped loading is extended to 300s~600s according to the complexity of the tombstone structure, and the pressure fluctuation range in the holding stage is ≤±2MPa.

[0014] In a preferred embodiment of the present invention, the mold is an electroformed nickel-based imitation stone texture mold with a coating thickness of 0.25mm-0.35mm, and the imitation stone texture includes any one or more combinations of granite, marble or sandstone.

[0015] In a preferred embodiment of the present invention, the protective coating is a composite coating of fluorocarbon transparent paint and nano-silicon oxide, wherein the mass proportion of nano-silicon oxide is 2% to 5%, and the coating thickness can be adjusted to 30 according to the use environment of the tombstone. ~50 .

[0016] In a preferred embodiment of the present invention, the interior of the composite tombstone is hollow, the hollow portion is filled with a degradable foam material, and a stainless steel threaded sleeve is embedded in the bottom of the tombstone.

[0017] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0018] (1) Through the composite system of unsaturated polyester resin, glass fiber, and PET fiber, the density of the tombstone is reduced from 2.7g / cm³ of natural stone to 1.5-1.8g / cm³, a reduction of 30%-45%. At the same time, the bending strength is also improved accordingly, exceeding the 100MPa of marble. This is because the glass fiber provides rigid support and the PET fiber enhances toughness through molecular chain entanglement, thus forming a mechanical structure that is both rigid and flexible. At the same time, the hollow structure further reduces weight, and the filling of biodegradable foam material forms a buffer layer, which improves the impact resistance of the tombstone and avoids the risk of cracking during transportation and installation.

[0019] (2) Nano-titanium dioxide in the modified filler forms a UV shielding network, reflecting more than 90% of ultraviolet rays; hindered amine light stabilizers capture free radicals and inhibit the oxidative degradation of the resin.

[0020] (3) Twin-screw extrusion combined with vacuum devolatilization process achieves uniform dispersion of the resin matrix, with a devolatilization efficiency of 99%, avoiding strength attenuation caused by residual bubbles; the three-stage impregnation tank makes the fiber dispersion uniformity reach 98%, ensuring the isotropy of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments described in the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0022] Figure 1 It is a flow chart of the preparation method of the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0025] like Figure 1 As shown, a composite tombstone and a preparation method thereof include the following steps:

[0026] S1. Preparation of the resin matrix: Mix, by mass, 50%-70% unsaturated polyester resin, 10%-30% modified filler (quartz powder modified with a silane coupling agent, supplemented with 0.3%-0.5% nano-titanium dioxide and 0.1%-0.3% hindered amine light stabilizer), and 1%-5% additives. Extrude these materials through a twin-screw extruder at 110°C-120°C and perform vacuum devolatilization to remove volatile substances to produce the resin matrix.

[0027] S2. Preparation of modified pellets: Mix 20%-40% glass fiber with 5%-15% PET fiber (polyethylene terephthalate), with the volume ratio of glass fiber to PET fiber being 1:3-4. The mixed fibers are evenly dispersed in a resin matrix through a three-stage impregnation tank to fully bond the fibers to the resin matrix, thereby producing a modified pellet.

[0028] S3. Composite tombstone molding: Use an electroformed nickel-based imitation stone texture mold with a coating thickness of 0.25mm to 0.35mm. The imitation stone texture can include any combination of granite, marble, or sandstone. The mold must be preheated before use to ensure uniform temperature.

[0029] The modified pellets are poured into a preheated mold. The mold temperature is set to three zones: 125°C–135°C in the feeding zone, 140°C–145°C in the molding zone, and 75°C–80°C in the cooling zone. A stepwise pressure application process is employed to shape the modified pellets within the mold. The pressure values ​​vary from 0, 45MPa–55MPa, 75MPa–85MPa, and 40MPa–55MPa, with a holding time of 280–300 seconds. For tombstones with complex structures, the holding time can be extended to 300–600 seconds, with pressure fluctuations of ≤±2MPa during this period. After the tombstone cools to a desired temperature within the mold, it is removed from the mold.

[0030] S4. Surface treatment and protective coating: Use fiber laser to engrave text on the surface of the composite tombstone to add personalized elements to the tombstone. Spray a composite coating of fluorocarbon transparent paint and nano-silicon oxide on the surface of the engraved tombstone, in which the nano-silicon oxide accounts for 2% to 5% by mass. The coating thickness can be adjusted to 30 to 50 mm according to the use environment of the tombstone. , to provide excellent protective performance and beautiful appearance. The coated tombstones were subjected to salt spray tests to test their corrosion resistance and the stability of the protective coating.

[0031] S5. Hollow Portion Filling and Embedded Parts Installation: The hollow portion of the tombstone is filled with biodegradable foam material to reduce its weight and improve its thermal insulation performance. A stainless steel threaded sleeve is embedded in the bottom of the tombstone to facilitate subsequent installation and fixing.

[0032] Example 1

[0033] The resin matrix is ​​prepared by mixing 60% unsaturated polyester resin, 25% quartz powder treated with a silane coupling agent, 0.4% nano-titanium dioxide, 0.2% modified filler (hindered amine light stabilizer), and 3% additives. These raw materials are thoroughly mixed in a twin-screw extruder at 115°C and then vacuum-devolatilized to produce the resin matrix.

[0034] 30% glass fiber and 10% PET fiber are then evenly dispersed into the resin matrix through a three-stage impregnation tank to create a modified pellet. During this process, the volume ratio of glass fiber to PET fiber is precisely controlled at 1:3.5 to ensure optimal strength and toughness for the tombstone.

[0035] The modified mass is poured into a pre-prepared electroformed nickel-based imitation marble texture mold with a coating thickness of 0.3mm, allowing the tombstone to accurately simulate the natural texture and feel of marble in appearance, making it almost indistinguishable from real marble.

[0036] The mold temperature is set to three zones: the feeding zone temperature is 130°C, the molding zone temperature is 142°C, and the cooling zone temperature is 78°C. During the molding process of the modified pellets, a step-by-step pressurization method is adopted, and the step-by-step change of the pressure value is 0 50MPa 80MPa 50MPa, the holding time is 300s, and the pressure fluctuation range during the holding stage is strictly controlled within ±1.5MPa to ensure the quality and stability of the tombstone.

[0037] The finished composite tombstone is hollow inside and filled with biodegradable foam, which not only reduces its weight but also improves its thermal insulation properties. A stainless steel threaded sleeve is also embedded in the bottom of the tombstone to facilitate subsequent installation and fixing.

[0038] In terms of tombstone surface treatment, fiber laser was used to engrave text on the tombstone surface, and the engraved text was clear and beautiful. Afterwards, a layer of fluorocarbon transparent paint was sprayed on the tombstone surface, and nano-silicon oxide with a mass percentage of 3% was added to form a composite coating. The coating thickness was adjusted to 40 To improve the weather resistance and corrosion resistance of the tombstone. In order to verify the performance of the coating, a salt spray test was also carried out to test the changes. The results showed that the coating has excellent performance. After the experimental conditions were 5% NaCl solution, 35℃±2℃, and continuous spraying for 480 hours, the surface coating showed no obvious changes and no corrosion.

[0039] Compared with traditional natural marble tombstones, this composite tombstone has multiple advantages. In terms of weight, the density of the composite tombstone is 1.8g / cm³, which is significantly lighter than the density of marble tombstones at 2.7g / cm³, making it easier to transport and install.

[0040] In terms of weather resistance, composite tombstones are far more weather-resistant than marble tombstones because they are added with ingredients such as nano-titanium dioxide and hindered amine light stabilizers, and are protected by a composite coating of fluorocarbon transparent paint and nano-silicon oxide. They can withstand erosion from various harsh climatic conditions.

[0041] Composite tombstones can mimic the textures and colors of various stone materials, making them more aesthetically pleasing. They are also relatively inexpensive, costing only 65% ​​of marble, making them more suitable for modern consumer needs. Finally, the biodegradable foam filling inside composite tombstones is environmentally friendly and decomposes naturally upon disposal, aligning with the concept of sustainable development.

[0042] Example 2

[0043] S1. Use o-phthalate UPR-196 with a viscosity of 500~700 and an acid value of 28~36mgKOH / g. Preheat in a 60℃ water bath for 30 minutes before use to reduce the viscosity and facilitate mixing.

[0044] Silane coupling agent modified quartz powder, with a particle size of D50=5, was modified with γ-methacryloxypropyltrimethoxysilane. The modification process was as follows: quartz powder and coupling agent were mixed in a mass ratio of 100:1.5, treated at 80°C for 2 hours in a high-speed mixer at a speed of 1500 r / min, and then dried to a moisture content of <0.1%; nano-titanium dioxide, with a particle size of 20 nm, was mechanically mixed evenly with the modified quartz powder with a hindered amine light stabilizer in a formula ratio of 0.3%~0.5% nano-TiO2 and 0.1%~0.3% HALS.

[0045] The additives include 1.5% methyl ethyl ketone peroxide, 1% cobalt cyclohexane, and 1% mold release agent zinc stearate, which are mixed according to the mass ratio and set aside.

[0046] A Nanjing Jieente JWS-35 twin-screw extruder was used with a length-to-diameter ratio of L / D = 40:1. The screw element combination was a conveying section + mixing section + exhaust section. The extrusion temperature was controlled in zones: 110°C in zone one, 115°C in zone two, and 120°C in zone three. The screw speed was 200 r / min, the pressure of the vacuum devolatilization system was maintained at -0.095 MPa, the devolatilization time was 15 minutes, and the extrudate was water-cooled and granulated to obtain resin matrix particles with a diameter of 3 mm.

[0047] S2. Preparation of modified pellets: select alkali-free glass fiber roving with a single filament diameter of 9 mm, treated with a silane coupling agent, and having a sizing agent content of 0.8%. Cut into 5-10 mm short fibers before use.

[0048] Polyethylene terephthalate, melt flow rate 25g / 10min, 15dtex*38mm short fiber, surface plasma treated with power 500W and treatment time 30s to improve compatibility with resin.

[0049] A three-stage fiber impregnation device is set up. The first section is the resin pre-impregnation zone with a temperature of 60°C and a molten resin matrix. The second section is the fiber dispersion zone equipped with a stirring paddle with a rotation speed of 80r / min. The third section is the degassing zone with a vacuum degree of -0.08MPa.

[0050] According to the volume ratio of glass fiber to PET fiber of 1:3.5, the fibers are evenly put into the first section impregnation tank, the flow rate of the resin matrix is ​​controlled by a metering pump, the fibers and the resin are fully mixed in the second section tank, and after degassing in the third section, granulation is carried out by a twin-screw extruder to obtain a modified agglomerate with a particle size of 5 mm. The uniformity of fiber dispersion in the agglomerate is tested by an optical microscope at 100 times magnification, and the fiber agglomerate size is required to be less than 0.5 mm.

[0051] S3 is made by electroforming process, with nickel plating thickness of 0.3mm and error of ±0.02mm. The imitation stone texture is transferred by laser engraving master mold, with texture depth of 0.15mm. It can simulate granite (coarse sand texture), marble (fine texture) or sandstone (porous texture). The mold should be preheated in a 120℃ oven for 2 hours before use, and the surface should be wiped with acetone to remove oil stains.

[0052] A 2,000-ton servo hydraulic press is used, equipped with a three-zone temperature control system: the feeding zone is 130°C, with an error of ±2°C, using an electric heating plate and a heating rate of 5°C / min; the forming zone is 142°C, with an error of ±1°C, using an oil heating circulation system and a holding time of 10 minutes; the cooling zone is 78°C, with an error of ±3°C, using a water cooling pipe and a cooling rate of 8°C / min.

[0053] Step-by-step pressurization parameters: 0→50MPa, pressure rise time 15s, pressure holding 60s; 50→80MPa, pressure rise time 20s, pressure holding 120s; 80→50MPa, pressure reduction time 10s, pressure holding 120s; total pressure holding time 300s, pressure fluctuation range ≤±1.5MPa, real-time monitoring by pressure sensor.

[0054] Adjustments for tombstones with complex structures (such as those with embossed patterns): the holding time is extended to 450s, and the pressurization stage is divided into five levels: 0→30→50→70→80→50MPa, to avoid material shortages caused by uneven fiber flow.

[0055] The mold is cooled to below 50℃ and demoulded. The surface of the tombstone is lightly polished with 800-grit sandpaper to remove burrs, and then aged in a 60℃ oven for 24 hours to eliminate internal stress.

[0056] S4. Select IPG YLS-2000 fiber laser with a wavelength of 1064nm, a power of 200W, an engraving speed of 500mm / s, an engraving depth of 0.3mm, and a text line width of 0.2mm. Design the engraving pattern using CAD software and import it into the laser control system for execution.

[0057] PPG fluorocarbon coating was selected with a solid content of 45%, 3% nano-silicon oxide was added, and the particle size was 50 nm. A high-speed disperser was used with a speed of 3000 r / min and dispersion for 30 minutes to prepare a composite coating.

[0058] Use an air spray gun with a pressure of 0.4MPa and a spraying distance of 20cm. Spray in two layers, with each layer having a thickness of 15~20 and a total thickness of 35~40. After spraying, cure at 80℃ for 2 hours.

[0059] A Q-FOG CCT-1100 salt spray cabinet was used. Test conditions: 5% NaCl solution, pH 6.5-7.2, temperature 35°C, continuous spraying for 480 hours. Following the ASTM B117 standard, the surface coating was inspected for signs of blistering, flaking, or rust, with a color difference ΔE less than 1.5.

[0060] S5. The interior of the tombstone features a honeycomb hollow structure with a wall thickness of 20mm. The hollow cavity dimensions are adjusted to the tombstone specifications. For example, for a standard tombstone measuring 1200mm × 600mm × 50mm, the hollow cavity accounts for 60%. The filling is a biodegradable polylactic acid / starch-based foam with a density of 30kg / m³ and a degradation cycle of 5 years, complying with GB / T 19277.1. The filling is performed by injecting liquid foam using a high-pressure foaming machine with a 15x expansion ratio and a curing time of 20 minutes.

[0061] The stainless steel threaded sleeve is embedded M16×100mm, with 4 embedded pieces distributed at the four corners of the bottom of the tombstone, with an embedded depth of 80mm. It is fixed with epoxy resin glue, curing conditions: 25℃×24 hours, and the pull-out strength is ≥15MPa.

[0062] Example 3

[0063] Unsaturated polyester resin 50%, modified quartz powder 30%, modified quartz powder includes adding 0.5% nano-TiO2 + 0.3% HALS, and additives 5%.

[0064] The fiber ratio is 20% glass fiber and 15% PET fiber, with a volume ratio of 1:4. The mold texture is simulated sandstone, and the electroformed nickel plating thickness is 0.25mm. The molding pressure is 0→45MPa→75MPa→40MPa, with a holding time of 280s. The coating thickness is 50. After 720 hours of salt spray testing, there is no surface change. The density is 1.7g / cm³ and the flexural strength is 180MPa, which is 100MPa better than natural marble.

[0065] Example 4

[0066] Select unsaturated polyester resin 70%, modified quartz powder 10%, and additive 1%.

[0067] The fiber ratio is 40% glass fiber and 5% PET fiber, with a volume ratio of 1:3; the molding temperature is 125℃ in the feeding zone, 140℃ in the molding zone, and 75℃ in the cooling zone; the hollow filler is a biodegradable foam material with a density of 25kg / m³; the tombstone density is 1.5g / cm³, which is 45% lighter than a marble tombstone, and the compressive strength is 150MPa, meeting the GB / T19933.1 standard.

[0068] The above description is based on the ideal embodiment of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the content of the specification and must be determined according to the scope of the claims.

Claims

1. A method for preparing a composite tombstone, characterized in that: The following steps are involved: S1. According to the mass ratio, 50%-70% of unsaturated polyester resin, 10%-30% of modified filler, and 1%-5% of additive are twin-screw extruded at 110°C-120°C, and vacuum devolatilization is performed to obtain a resin matrix; S2, then evenly dispersing 20%-40% of glass fiber and 5%-15% of PET fiber in the resin matrix through a three-stage impregnation tank to prepare a modified pellet; S3. Pour the modified mass into a mold and set the mold temperature to three temperature zones, i.e., 125°C to 135°C in the feeding zone, 140°C to 145°C in the molding zone, and 75°C to 80°C in the cooling zone; a stepwise pressurization method is used to shape the modified mass to obtain a composite tombstone; S4. Use fiber laser to engrave text on the surface of the composite tombstone, spray fluorocarbon transparent paint at the same time, and conduct change test through salt spray test.

2. The method for preparing a composite tombstone according to claim 1, characterized in that: The modified filler is quartz powder modified by a silane coupling agent, and 0.3% to 0.5% of nano titanium dioxide and 0.1% to 0.3% of a hindered amine light stabilizer are added to the modified filler.

3. The method for preparing a composite tombstone according to claim 1, characterized in that: The volume fraction ratio of the glass fiber to the PET fiber is 1:3-4, and the PET fiber is polyethylene terephthalate.

4. The method for preparing a composite tombstone according to claim 1, wherein: In the step-by-step pressurization method, the step-by-step change trend of the pressure value is 0 45MPa~55MPa 75MPa~85MPa 40MPa~55MPa, holding time 280s~300s.

5. The method for preparing a composite tombstone according to claim 1, characterized in that: In the stepped pressurization method, the holding time of the stepped loading is extended to 300s~600s according to the complexity of the tombstone structure, and the pressure fluctuation range in the holding stage is ≤±2MPa.

6. The method for preparing a composite tombstone according to claim 1, characterized in that: The mold adopts an electroformed nickel-based imitation stone texture mold, the coating thickness is 0.25mm~0.35mm, and the imitation stone texture includes any one or more combinations of granite, marble or sandstone.

7. The method for preparing a composite tombstone according to claim 1, characterized in that: The protective coating is a composite coating of fluorocarbon transparent paint and nano silicon oxide, wherein the mass proportion of nano silicon oxide is 2% to 5%, and the coating thickness can be adjusted to 30 according to the use environment of the tombstone. ~50 .

8. The method for preparing a composite tombstone according to claim 1, wherein: The interior of the composite tombstone is hollow, the hollow part is filled with degradable foam material, and a stainless steel threaded sleeve is pre-embedded in the bottom of the tombstone.

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