A melamine resin product containing natural fiber and preparation method thereof

Abstract

The present invention relates to C08L61 / 32, and in particular to a melamine resin product containing natural fibers and a preparation method thereof. The product comprises the following raw materials: 25-35 parts of leather, 50-60 parts of melamine resin prepolymer, 3-5 parts of antioxidant, 2-3 parts of modifier, and 10-15 parts of auxiliary agent, by weight. The melamine resin meal containing natural fibers prepared by the present invention has good toughness, good impact resistance, and extremely excellent compression resistance.

Description

Technical Field

[0001] The invention relates to C08L61 / 32, and in particular to a melamine resin product containing natural fibers and a preparation method thereof. Background Art

[0002] Melamine products, also known as imitation porcelain products, have excellent properties such as lightness, beauty, low temperature resistance and non-breakability. They are widely used in restaurants, canteens and other places.

[0003] Patent CN108192279A - A method for preparing a high-temperature resistant melamine resin plastic product effectively improves its waterproof and oil-proof properties by combining cassava starch degraded by fungal α-amylase with 3-chloro-2-hydroxypropyltrimethylammonium chloride and egg yolk lecithin. However, the advantages of melamine resin itself, such as being not easy to break, lead to a lack of attention during use. Existing melamine resin plastic products can hardly meet people's usage needs.

[0004] Patent CN201610966726.X A melamine product and its preparation method are prepared by the mutual coordination of raw materials such as nano-crystalline cellulose modified melamine formaldehyde resin, α-wood pulp fiber, microcrystalline cellulose, curing agent, nano-titanium dioxide, mica powder, etc. The melamine product has the advantages of high thermal decomposition temperature and impact strength, but it is expensive and difficult to promote.

[0005] The invention provides a melamine resin product containing natural fibers and a preparation method thereof, which can further improve the impact resistance of the melamine resin product and has low cost and is suitable for large-scale production. Summary of the invention

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a melamine resin product containing natural fibers, comprising the following raw materials: by mass, 25-35 parts of leather, 50-60 parts of melamine resin prepolymer, 3-5 parts of antioxidant, 2-3 parts of modifier, and 10-15 parts of additive.

[0007] Preferably, the leather is waste animal leather, selected from one or a combination of cowhide, sheepskin, pigskin, horsehide and donkey hide.

[0008] More preferably, the leather is cowhide.

[0009] Preferably, the leather is selected from chrome tanned leather, vegetable tanned leather, oil tanned leather, aldehyde tanned leather, and combined tanned leather.

[0010] Further preferably, the leather is vegetable tanned leather, which is made with vegetable tanning agent as the main tanning agent, and the mass percentage of tannin in the vegetable tanning agent is greater than 8%.

[0011] The applicant discovered during the experiment that the vegetable tanned leather prepared by using a vegetable tanning agent with a mass percentage of tannin greater than 8% as the main tanning agent and a combined reaction with melamine resin can make the leather act as a natural dye, bring natural color to the melamine resin, and avoid the safety problems caused by chemical dyes. The possible reason is guessed to be: the vegetable tanning agent contains tannins in the plant body, and the plant polyphenols can make the primary color in the leather free, enter the melamine resin to add color to the melamine resin, and form a natural primary color, thereby avoiding the safety problems of melamine resin caused by the addition of chemical dyes. When melamine resin products are heated, the vegetable tanned leather has strong high temperature resistance and high binding stability with melamine resin. When chemical dyes are introduced, the chemical dyes have poor high temperature resistance and may be freed and precipitated after high temperature oxidation. Chemical dyes enter food and affect food safety.

[0012] Preferably, the melamine resin prepolymer includes a hydroxyl-modified melamine resin prepolymer and / or an amino-modified melamine resin prepolymer.

[0013] More preferably, the melamine resin prepolymer is a hydroxyl-modified melamine resin prepolymer.

[0014] Furthermore, the hydroxyl-modified melamine resin prepolymer is an ethylene glycol-modified melamine resin prepolymer.

[0015] Preferably, the raw materials for preparing the ethylene glycol-modified melamine resin prepolymer include: melamine resin prepolymer and ethylene glycol.

[0016] Preferably, the weight ratio of the melamine resin prepolymer to ethylene glycol is 1:(0.1-0.3).

[0017] Preferably, the preparation method of the ethylene glycol-modified melamine resin prepolymer comprises the following steps: the preparation method of the ethylene glycol-modified melamine resin prepolymer comprises the following steps: adding a melamine resin prepolymer, heating to 80-90°C, then adding a pH adjuster, adjusting the pH to 8.5-9.0, reacting for 20-30 minutes, adding ethylene glycol, reacting for 3 hours, and discharging the material to obtain the product.

[0018] Preferably, the preparation method of the melamine resin prepolymer comprises the following steps: at 80-90° C., melamine, paraformaldehyde and water are uniformly mixed in a mass ratio of 6:5:7, and then the mixture is stirred and reacted for 10-20 minutes.

[0019] Preferably, the antioxidant is selected from one or a combination of butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris[2,4-di-tert-butylphenyl]phosphite.

[0020] More preferably, the antioxidant comprises pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite. The mass ratio of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite is (3-5):(3-5).

[0021] Preferably, the modifier is selected from one or a combination of silane coupling modifiers, titanate coupling modifiers and aluminate coupling modifiers.

[0022] More preferably, the modifier is an epoxy silane coupling agent.

[0023] Preferably, the boiling point of the epoxy silane coupling agent is 300-320°C.

[0024] Preferably, the density of the epoxy silane coupling agent is 1.05-1.07 g / cm 3 .

[0025] More preferably, the epoxy silane coupling agent is trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane.

[0026] The applicant found in the experiment that the boiling point is 310°C and the density is 1.065g / cm 3 The methoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane as a modifier can increase the high temperature stability of leather in melamine resin. The possible reason is that leather fibers are prone to bending and deformation under high temperature conditions, and even carbonization occurs, which reduces the bonding performance between leather fibers and melamine resin and also affects the toughness of leather. By introducing a melamine resin with a boiling point of 310°C and a density of 1.065g / cm 3 The methoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane can form a silane protective film on the surface of the leather fiber to improve the heat resistance of the leather fiber. When under high temperature conditions, the silane protective film can play a certain isolation role and improve the high temperature resistance of the leather fiber.

[0027] The applicant further discovered that the use of methoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane as a modifier can increase the compatibility of leather fibers and melamine resins, play a connecting role between leather and melamine resins, reduce the mutual repulsion between the interfaces of leather and melamine resins, and avoid the generation of cracks when subjected to external impact. In addition, methoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane with a longer molecular chain can further reduce the rigidity of melamine resins and improve the toughness of melamine resin products.

[0028] Further preferably, the weight ratio of the leather to the melamine resin is 7:(10-15).

[0029] During the experiment, the applicant found that the bending strength of the melamine resin decreased after the introduction of leather, and the molding performance of the prepared products was significantly improved. The possible reason is speculated to be: the leather contains a large amount of protein fibers, and the amino groups in the protein fibers react with the aldehyde groups of the melamine resin to generate hydroxyl groups, which further react with the hydroxymethylated melamine molecules to consume the triazine structures in the melamine resin. As the number of triazine structures decreases, the steric hindrance between the rigid structures decreases. The reduction in rigid structures means that the melamine resin only needs to resist a smaller force to achieve bending deformation, thereby improving the molding performance of the melamine resin.

[0030] The applicant further discovered that when the weight ratio of leather to melamine resin is 7:(10-15), the melamine resin products have good thermal stability and will not bend or deform after repeated high-temperature heating. When the weight ratio exceeds the preferred ratio, the heat resistance of the melamine resin products decreases significantly, and deformation problems will occur after repeated high-temperature heating. It is speculated that the possible reason is that the number of triazine rigid structures is excessively reduced, and the amino groups in the leather are introduced into the groups of the melamine resin, resulting in a decrease in the heat resistance of the melamine resin and easy deformation problems at high temperatures.

[0031] Preferably, the auxiliary agent is selected from one or a combination of curing agent, adhesive, reinforcing agent and release agent.

[0032] Preferably, the auxiliary agent includes a curing agent, an adhesive, a reinforcing agent, and a release agent. The mass ratio of the curing agent, the adhesive, the reinforcing agent, and the release agent is (3-5): (1.5-2.5): (5-8): (1-2).

[0033] Preferably, the curing agent is an acid anhydride curing agent.

[0034] Preferably, the acid anhydride curing agent includes at least one of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, trimellitic anhydride, methylcyclohexenyltetracarboxylic dianhydride, pyromellitic dianhydride, and benzophenonetetracarboxylic dianhydride.

[0035] More preferably, the anhydride curing agent includes methylhexahydrophthalic anhydride.

[0036] Preferably, the hydroxyl value of the adhesive is 25-35 mgKOH / g.

[0037] Preferably, the average molecular weight of the adhesive is 3500-4500.

[0038] Preferably, the reinforcing agent includes at least one of calcium carbonate, magnesium oxide, zinc oxide, titanium dioxide, white carbon black, diatomaceous earth and bentonite.

[0039] More preferably, the reinforcing agent comprises white carbon black and bentonite, wherein the mass ratio of the white carbon black to the bentonite is (5-7):(2-4).

[0040] Preferably, the average particle size of the white carbon black is 1000-1500 mesh.

[0041] Preferably, the average particle size of the bentonite is 300-400 mesh.

[0042] Preferably, the bentonite includes calcium-based bentonite and / or sodium-based bentonite.

[0043] Further preferably, the bentonite comprises calcium-based bentonite.

[0044] Preferably, the release agent includes at least one of YYTM-001, HD-918-1, HD-915, HD-9185, HD-9184, HD-9182, HD-820, and 820-NC.

[0045] As a preferred embodiment, the melamine resin product containing natural fibers can be applied to daily necessities, including but not limited to tableware, electrical appliances, machinery, and building products.

[0046] A second aspect of the present invention provides a method for preparing a melamine resin product containing natural fibers, comprising the following steps:

[0047] (1) degreasing and deoiling the leather, then crushing the leather to 1-5 mm, acid-treating the crushed leather, soaking it for 1-3 hours, taking it out, grinding it to 1 mm, and then putting it into a ball mill to obtain waste leather powder particles;

[0048] (2) Mix the waste leather powder and the modifier, then add them into the melamine resin prepolymer, and then add the antioxidant and the auxiliary agent into a mixer and stir and mix for 1-2 hours to obtain the product.

[0049] Beneficial effects:

[0050] 1) The present invention provides a melamine resin product containing natural fibers and a preparation method thereof. By limiting the types and contents of the raw materials used in the preparation, the melamine resin product is not afraid of falling during use, has good toughness, good impact resistance, excellent compressive resistance, etc., and can avoid the occurrence of cracks after being dropped.

[0051] 2) The present invention adopts ethylene glycol to modify the melamine resin, especially when the weight ratio of the melamine resin prepolymer to ethylene glycol is 1: (0.1-0.3), the rigidity of the melamine resin product is reduced, the toughness is improved, the impact resistance of the melamine resin product is improved, and the generation of cracks in the melamine resin product is effectively reduced.

[0052] 3) The present invention adds a density of 1.065g / cm 3 , trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane with a boiling point of 310°C makes the leather evenly dispersed in the melamine resin prepolymer, while reducing the bending deformation of the leather fiber at high temperature and improving the high temperature stability. Especially when the weight ratio of leather to melamine resin is 1:(10-15), the processing and molding performance is improved and the deformation problem of melamine resin products at high temperature is reduced.

[0053] 4) At the same time, the present invention unexpectedly discovered that when the leather is vegetable tanned leather, it can also bring natural colors to melamine resin products, avoiding food safety issues caused by chemical dyes, making the prepared melamine resin products particularly suitable for use by young children.

[0054] 5) The melamine resin product containing natural fibers of the present invention has good heat resistance and dimensional stability. The tableware prepared therefrom will not deform after being heated at high temperatures and is particularly suitable for long-term heating in a microwave oven. DETAILED DESCRIPTION

[0055] Example

[0056] Example 1

[0057] A melamine resin product containing natural fibers comprises the following raw materials: by weight, 28 parts of leather, 56 parts of melamine resin prepolymer, 4 parts of antioxidant, 2.5 parts of modifier and 12 parts of auxiliary agent.

[0058] The leather is waste cowhide vegetable tanned leather, which is made with vegetable tanning agent as the main tanning agent. The mass percentage of tannin in the vegetable tanning agent is greater than 8%, and the leather comes from Shenzhen Deyi Technology Industry Co., Ltd.

[0059] The melamine resin prepolymer is ethylene glycol modified melamine resin prepolymer.

[0060] The raw materials for preparing the ethylene glycol-modified melamine resin prepolymer include: melamine resin prepolymer and ethylene glycol. The weight ratio of the melamine resin prepolymer to the ethylene glycol is 1:0.2.

[0061] The preparation method of the ethylene glycol-modified melamine resin prepolymer comprises the following steps: adding a melamine resin prepolymer, heating to 85° C., then adding a pH regulator (sodium hydroxide), adjusting the pH to 8.7, reacting for 25 minutes, adding ethylene glycol, reacting for 3 hours, and then discharging the material.

[0062] The preparation method of the melamine resin prepolymer comprises the following steps: the preparation method of the melamine resin prepolymer comprises the following steps: at 85° C., melamine, paraformaldehyde and water are mixed evenly in a mass ratio of 6:5:7, and then stirred and reacted for 15 minutes. The melamine is purchased from Shandong Pulis Chemical Co., Ltd.; the paraformaldehyde is purchased from Jinan Pulaihua Chemical Co., Ltd., model: industrial grade.

[0063] The antioxidant comprises pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite. The mass ratio of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite is 4:4.

[0064] The modifier is an epoxy silane coupling agent. The epoxy silane coupling agent has a boiling point of 310°C and a density of 1.065 g / cm 3 trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane.

[0065] The auxiliary agent includes a curing agent, an adhesive, a reinforcing agent, and a release agent, wherein the mass ratio of the curing agent, the adhesive, the reinforcing agent, and the release agent is 4:2:6.5:1.5.

[0066] The curing agent is methyl hexahydrophthalic anhydride.

[0067] The adhesive has a hydroxyl value of 26-32 mgKOH / g and an average molecular weight of 3600-4400, and is purchased from Nantong Arches Chemical Co., Ltd., model: PEG4000.

[0068] The reinforcing agent includes white carbon black and bentonite. The mass ratio of the white carbon black to the bentonite is 6:3. The white carbon black has an average particle size of 1250 mesh and is purchased from Rugao Feida Chemical Factory. The bentonite is calcium-based bentonite with an average particle size of 325 mesh and is purchased from Chengdu Youwute Technology Co., Ltd., model: NW-011.

[0069] The release agent was purchased from Shanghai Dongheng Chemical Co., Ltd., model: release agent HD-9182.

[0070] A method for preparing a melamine resin product containing natural fibers comprises the following steps:

[0071] (1) degreasing and deoiling the leather, then crushing the leather to 3 mm, treating the crushed leather with acid (hydrochloric acid with a pH of 6.5), soaking for 2 hours, taking it out, grinding it to 1 mm, and then putting it into a ball mill to obtain waste leather powder particles;

[0072] (2) Mix the waste leather powder and the modifier, then add them into the melamine resin prepolymer, and then add the antioxidant and the auxiliary agent into a mixer and stir and mix for 1.5 hours to obtain the product.

[0073] Example 2

[0074] A melamine resin product containing natural fibers, the specific implementation manner is the same as that of Example 1, except that the weight ratio of the melamine resin prepolymer to ethylene glycol is 1:0.3.

[0075] Example 3

[0076] A melamine resin product containing natural fibers, the specific implementation manner is the same as that of Example 1, except that the raw materials include 35 parts of leather, 60 parts of melamine resin prepolymer, 5 parts of antioxidant, 3 parts of modifier, and 15 parts of auxiliary agent.

[0077] Comparative Example 1

[0078] A melamine resin product containing natural fibers, the specific implementation manner is the same as that of Example 1, except that the modifier is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0079] Comparative Example 2

[0080] A melamine resin product containing natural fibers, the specific implementation manner is the same as that of Example 1, except that the melamine resin prepolymer is an unmodified melamine resin prepolymer.

[0081] Performance Testing

[0082] 1. Referring to GB / T 2567-1995, the materials prepared in the examples and comparative examples were cured for 7 days at 25±2°C, processed into five-notch Class A specimens (120*10*15mm), and then impact tests and compression tests were carried out in accordance with GB / T 2567-2008 to test the impact strength and compression strength of the materials.

[0083] Table 1 Performance test results

[0084]

[0085] Table 2 Partial performance test results of Example 1

[0086]

[0087] 3. The test was conducted in accordance with FDA 21CFR 177.1460-chloroform soluble extracts. The test results of Example 1 are as follows.

[0088] Table 3

[0089] time temperature result Distilled water 24hr(s) 120°F <![CDATA[<0.2mg / inch 2 ]]> 8% ethanol 24hr(s) 120°F 0.4mg / inch2 n-Heptane 0.5hr(s) 120°F <![CDATA[<0.2mg / inch 2 ]]>

Claims

1. A melamine resin product containing natural fibers, characterized in that: The raw materials include: by weight, 25-35 parts of leather, 50-60 parts of melamine resin prepolymer, 3-5 parts of antioxidant, 2-3 parts of modifier, and 10-15 parts of auxiliary agent; The leather is waste cowhide vegetable tanned leather, the vegetable tanned leather is made with vegetable tanning agent as the main tanning agent, and the mass percentage of tannin in the vegetable tanning agent is greater than 8%; The melamine resin prepolymer is an ethylene glycol-modified melamine resin prepolymer; The raw materials for preparing the ethylene glycol-modified melamine resin prepolymer include: melamine resin prepolymer and ethylene glycol, with a weight ratio of 1: (0.1-0.3); The preparation method of the ethylene glycol-modified melamine resin prepolymer comprises the following steps: adding a melamine resin prepolymer, heating to 80-90° C., then adding a pH regulator, adjusting the pH to 8.5-9.0, reacting for 20-30 minutes, adding ethylene glycol, reacting for 3 hours, and then discharging the material to obtain the product; The preparation method of the melamine resin prepolymer comprises the following steps: at 80-90° C., uniformly mixing melamine, polyformaldehyde and water in a mass ratio of 6:5:7, and then continuing to stir and react for 10-20 minutes to obtain the product; The antioxidant comprises pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl]phosphite in a mass ratio of (3-5):(3-5); The modifier is trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane; The auxiliary agent includes a curing agent, an adhesive, a reinforcing agent, and a release agent; the mass ratio of the curing agent, the adhesive, the reinforcing agent, and the release agent is 4:2:6.5:1.5; The curing agent is methyl hexahydrophthalic anhydride; The adhesive has a hydroxyl value of 26-32 mgKOH / g and an average molecular weight of 3600-4400; the reinforcing agent includes white carbon black and bentonite in a mass ratio of 6:3; the average particle size of the white carbon black is 1250 mesh; the bentonite is calcium-based bentonite with an average particle size of 325 mesh.

2. A method for preparing a melamine resin product containing natural fibers according to claim 1, characterized in that: The following steps are involved: (1) Degreasing and deoiling the leather, then crushing the leather to 1-5 mm, acid-treating the crushed leather, soaking it for 1-3 hours, taking it out, grinding it to 1 mm, and then putting it into a ball mill to obtain waste leather powder; (2) Mix the waste leather powder and the modifier, then add them into the melamine resin prepolymer, and then add the antioxidant and the additive into a mixer and stir for 1-2 hours.

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