CN105440911A - Low temperature crosslinked high molecular composite material used for MDF sheet material, and preparation method thereof - Google Patents

Abstract

The invention relates to the field of chemical coatings, in particular to a polymer composite material coated on the outer surface of an MDF board to protect and decorate the MDF board and a preparation method thereof. The components and mass percentages in the composite material are: 30-33% of polyester resin, 30-33% of epoxy resin, 30-37% of pigment and filler, 1.6-3.5% of auxiliary agent, 0.8-1.2% of curing accelerator %, according to mass percentage, after mixing the components, they are melted and extruded through an extruder to mix, and the extruded mixed material is cooled, crushed and sieved to obtain the product. The polymer composite paint prepared by the invention has excellent storage stability, and after storage at 38°C for 2 months, the gelation time of the product basically does not change; the curing condition is 130°C/15min, the curing temperature is low, and the production efficiency is high.

Description

A low-temperature crosslinked polymer composite material for MDF boards and its preparation method

technical field

The invention relates to the field of chemical coatings, in particular to a polymer composite material coated on the outer surface of an MDF board to protect and decorate the MDF board and a preparation method thereof.

Background technique

At present, the surface treatment process of MDF boards can be divided into three steps: surface machining, veneer decoration, and painting. Among them, paint or UV-curable paint is generally used for finishing. The process of spraying paint is: batch putty→grinding→painting (repeat the whole process if the surface is defective), the process cycle is at least 4 days, the labor efficiency is low, VOC emissions are generated, and the environment is polluted. , affecting the health of workers. However, UV-curable coatings are only suitable for plane construction, and cannot be cured for various shapes and edges that cannot be irradiated by light, so the application is limited. There are also some low-temperature powder coatings on the market that are used on MDF boards, but due to the curing accelerator, this type of product is easy to yellow during the baking process, and is not suitable for the production of light-colored products, and its storage stability is poor. Stored at ℃ for 2 months, the gel time of the product will be significantly shortened, which affects the normal use of the product.

Contents of the invention

In order to solve the above technical problems, the present invention provides a polymer composite material for coating on the surface of MDF boards. The polymer composite material has a low film forming temperature, that is, 130°C/15min curing, and there is no VOC emission during the construction process. , is an environmentally friendly product, the product is produced with assembly line construction, after baking and solidification, the product can be cooled to room temperature before the next assembly process, labor production efficiency is fast, and can be made into various colors and textures.

In the polymer composite material of the present invention, each component and its mass percentage are: 30-33% of polyester resin, 30-33% of epoxy resin, 30-37% of pigment and filler, 1.6-3.5% of auxiliary agent, curing Accelerator 0.8～1.2%,

Among them, the polyester resin is a carboxyl-terminated polyester resin polymerized from polyhydric alcohol and polycarboxylic acid, its acid value is 65-75mgKOH/g, and its Tg is 52-56°C.

Epoxy resin is the curing agent. The epoxy resin is a bisphenol A type epoxy resin formed by polymerization of epichlorohydrin and bisphenol A through a two-step method. Its epoxy equivalent is 780-850g/eq, and its softening point is 92～102℃, organic chloride ion content≤0.5%, inorganic chloride ion content≤300ppm,

The average particle size of the filler is ≤10 μm, specifically one or more of barium sulfate, kaolin or calcium carbonate, and the pigment is titanium dioxide, lithopone, carbon black, red powder, phthalocyanine blue, malachite green or even light yellow,

Auxiliaries include leveling agent, dispersant, degassing agent, loosening agent, sand texture agent, wherein, leveling agent includes acrylate copolymer, dispersant includes copolymer of methacrylic acid and styrene, and degassing agent includes benzoin or amide wax, the loosening agent includes fumed silica or alumina C, the sanding agent includes polytetrafluoroethylene wax powder,

The curing accelerator is 2MA-OK or phenylcarbamoyl imidazole (structural formula is as follows). Using the structural characteristics of these two curing accelerator products, the storage stability of the polymer composite material before curing is improved, so that it can be stored below 80 ° C. There is basically no reaction, but it effectively reduces the curing temperature when the composite material is formed into a film,

(X is H).

The present invention also provides a method for preparing the above-mentioned polymer composite material for coating on the surface of MDF boards: according to the mass percentage, put each component into a mixing tank for mixing, and pass the mixed material through an extruder Melting extrusion mixing, cooling the extruded mixed material, crushing the material with a crusher, finely pulverizing and grading with an air classifying mill, and finally grading and sieving with a rotary sieve to obtain the product.

The beneficial effect of the present invention is that: the polymer composite paint prepared by the present invention basically has no chemical reaction below 80°C, and has excellent storage stability. After being stored at 38°C for 2 months, the gelation time of the product basically does not change; the product It adopts high-voltage electrostatic spraying on the MDF board that has been machined or veneered, and is cured by infrared rays and hot air circulation. The curing condition is 130°C/15min. The curing temperature is low and the production efficiency is high. It is not easy to produce yellow during the curing process. change, no VOC emissions (at the same time, the formaldehyde content in the MDF board can be removed by baking at 130 ° C), and the cured board can be directly installed in the next process, saving time.

The present invention adopts carboxyl-terminated polyester resin and bisphenol A type epoxy resin, and under the action of curing accelerator 2MA-OK or anilcarbamoyl imidazole, the epoxy group reacts with the carboxyl group of the polyester resin, and cross-links to form Membrane, cross-linked polymer composite impact strength can reach 50kg/cm, flexibility 1mm, adhesion 0 grade, organic composite has excellent physical and mechanical properties and aging resistance, simple preparation process, can significantly improve labor production Efficiency, suitable for industrial production.

Description of drawings

Fig. 1 is the process flow diagram of the preparation method of the polymer composite material in the present invention.

detailed description

In each of the following examples, the polyester resins are carboxyl-terminated polyester resins formed by the polymerization of polyhydric alcohols and polycarboxylic acids. The acid value of the polyester resins is 65 to 75 mgKOH/g, and the Tg is 52 to 56° C.; the curing agent used is Epoxy resin, the epoxy equivalent is 780-850g/eq, the softening point is 92-102°C, the content of organic chloride ions is ≤0.5%, and the content of inorganic chloride ions is ≤300ppm; Coloring pigments containing heavy metals or rutile titanium dioxide.

Example 1

A polymer composite material for coating on the surface of MDF boards, which has the following formula (the components are parts by mass): 33 parts of polyester resin (HH-2562), 33 parts of E-12 epoxy resin (GES904) 23 parts of NR950 titanium dioxide, 7.6 parts of barium sulfate, 1.2 parts of 2MA-OK, 1.2 parts of leveling agent, 0.7 parts of dispersant, and 0.3 parts of benzoin degasser.

Example 2

A polymer composite material for coating on the surface of MDF boards, with the following formula (the components are parts by mass): 30 parts of polyester resin (HH-2562), 30 parts of E-12 epoxy resin (GES904) 23 parts of NR950 titanium dioxide, 14 parts of barium sulfate, 1.2 parts of anilbamoyl imidazole, 0.2 parts of sanding agent, 1.3 parts of polyethylene wax powder, and 0.3 parts of benzoin degasser.

Comparative Example 1

In embodiment 1, the curing accelerator is replaced by 2-methylimidazole or 2-ethylimidazole, and other components and contents remain unchanged (the content of comparative example 1 is roughly the same as that of the original embodiment 1, only the curing accelerator species is wherein Changes were made to account for the effect of curing accelerators on product manufacturing and storage stability).

Comparative Example 2

In embodiment 2, curing accelerator is replaced by 2-phenylimidazoline, and other components and content are constant (comparative example 2 is roughly the same as former embodiment 2 content, only wherein curing accelerator kind has been changed, with Describe the effect of curing accelerators on product production and storage stability).

The polymer composite material preparation method that is used to be coated on the surface of MDF sheet material in above-mentioned each embodiment, comparative example is as follows:

According to the number of parts by weight, put each component into the mixing tank and mix for 5 minutes, melt and extrude the mixed material through an extruder (118 ° C ~ 122 ° C) and mix, cool the extruded mixed material, and use a crusher The material is crushed to less than 2.5mm in thickness and less than 20mm in length and width, then finely crushed and classified by an air classifying mill, and finally classified and sieved by a rotary sieve to obtain the product with a mesh number of 180 mesh. The curing process and each performance data of each embodiment, comparative example gained product are as follows:

Through comparing the data in the above table, it can be seen that although only the kind of curing accelerator has been changed in comparative example 1 and comparative example 2, it has a great influence on the final performance, such as the ease of production (referring to extrusion here). Difficulty of operation: the present invention needs to be melt-extruded at about 120°C. In Comparative Examples 1 and 2, due to the high activity of the composite material, it is easy to react during the extrusion process, resulting in part of the coating being solidified in advance to form Waste product, affects normal production, causes waste; And this phenomenon does not exist in embodiment 1,2.), anti-yellowing property, storage stability, the outward appearance etc. after long-time storage all have bigger influence. It can be seen that under the formulation conditions of this application, selecting a suitable curing accelerator can greatly improve the performance; in addition, the addition of sanding agent can change the appearance of the product and make the product have a frosting effect.

Claims (10)

1. A polymer composite material for coating on the surface of MDF boards, characterized in that: said composite material includes polyester resin, epoxy resin, pigment, filler, auxiliary agent and curing accelerator. 2. The polymer composite material for coating on the surface of MDF boards as claimed in claim 1, characterized in that: each component and mass percentage in the composite material are 30-33% polyester resin , Epoxy resin 30-33%, pigment and filler 30-37%, additive 1.6-3.5%, curing accelerator 0.8-1.2%. 3. The polymer composite material for coating on the surface of MDF boards according to claim 1 or 2, characterized in that: the curing accelerator is 2MA-OK or anilbamoyl imidazole. 4. as claimed in claim 1 or 2, is used to be coated on the macromolecule composite material of MDF sheet material surface, it is characterized in that: described polyester resin is the carboxyl-terminated polyester resin that polyhydric alcohol and polycarboxylic acid polymerize , its acid value is 65-75mgKOH/g, and its Tg is 52-56°C. 5. The polymer composite material for being coated on the surface of MDF boards as claimed in claim 1 or 2, characterized in that: the epoxy resin is formed by two-step polymerization of epichlorohydrin and bisphenol A The prepared bisphenol A epoxy resin has an epoxy equivalent of 780-850g/eq, a softening point of 92-102°C, an organic chloride ion content of ≤0.5%, and an inorganic chloride ion content of ≤300ppm. 6. The polymer composite material for being coated on the surface of MDF board as claimed in claim 1 or 2, characterized in that: said pigment is titanium dioxide, lithopone, carbon black, scarlet powder, phthalocyanine blue , malachite green or even light yellow. 7. The polymer composite material for coating on the surface of MDF boards as claimed in claim 1 or 2, characterized in that: the filler is one or more of barium sulfate, kaolin or calcium carbonate, and the average particle size Diameter ≤ 10μm. 8. The polymer composite material for being coated on the surface of MDF board as claimed in claim 1 or 2, characterized in that: said auxiliary agent comprises leveling agent, dispersant, degassing agent, loosening agent, sand Texture agent. 9. the preparation method that is used to be coated on the polymer composite material of MDF plate surface as claimed in claim 2, is characterized in that: described preparation method is, by mass percentage, passes through extruder after each component is mixed Melting, extruding and mixing, cooling, crushing and sieving the extruded mixed material to obtain the product. 10 . The method for preparing the polymer composite material coated on the surface of the MDF board according to claim 9 , wherein the mesh size of the sieve used for sieving is 160 mesh to 200 mesh. 11 .