CN110655620A - Aqueous hyperbranched polyacrylate emulsion, preparation method and application thereof - Google Patents

Abstract

The invention discloses a water-based hyperbranched polyacrylate emulsion, a preparation method and application thereof. The emulsion prepared by the invention has good water solubility, stability in water environment, small particle size, low viscosity and simple preparation process, is not easy to settle, and can be used for modifying wood, effectively reducing the water absorption of target wood and improving the stability of the target wood.

Description

Aqueous hyperbranched polyacrylate emulsion, preparation method and application thereof

Technical Field

The invention relates to the technical field of wood processing, in particular to aqueous hyperbranched polyacrylate modifier emulsion, a preparation method and application thereof.

Background

Wood is a biomass material with a porous structure, and the chemical composition of the wood contains hydrophilic substances such as cellulose and hemicellulose, so that the wood has strong water absorption and is easily damaged by the environment and microorganisms to cause biological deterioration. In addition, the wood has the reasons of large structural variability, loose material surface, poor dimensional stability and the like, so that the utilization of the wood is limited to a great extent, and people also research methods for improving the performance of the wood.

The traditional wood modification technology has two types: one is to compress the wood under high temperature and high humidity conditions to stabilize the dimension of the wood and achieve densification effect, thereby improving the dimension stability, surface hardness and strength of the wood, however, the wood modified by the method often has great resilience, and the inherent defects of the wood still appear in the high temperature and high humidity use environment. The other technology is to utilize the inherent permeability of wood to permeate the modifier into the wood to reduce the moisture absorption and water absorption performance of the wood, so as to improve the dimensional stability, decay resistance and the like of the wood. Currently, wood modification techniques favor the latter.

The polyacrylate is a high molecular compound polymerized by acrylic acid or acrylate monomers, has strong reactivity, and can perform ester exchange reaction with hydroxyl on the surface of wood to form hydrogen bond and covalent bond. The polyacrylate emulsion is prepared by polymerizing acrylate monomer emulsion, has good water dispersibility, and can be used for impregnation modification of wood. And the polyacrylate can also form a layer of compact hydrophobic film after being cured, and the compact hydrophobic film is coated on the surface of the wood cell wall to form hydrophobization. However, the emulsion has larger particle size and higher viscosity, and the impregnation treatment is easy to generate a screen effect, so that a large amount of polyacrylate is agglomerated on the surface of the wood and is difficult to penetrate into the wood, and the treatment effect on the wood is poor. Straw fibers treated with an aqueous polyacrylate emulsion, such as Kuang et al (Carbohydrate Polymers, 2010, 927-one 933), found that a significant amount of polyacrylate was only on the fiber surface and had difficulty entering the interior of the wood.

Hyperbranched polymer is a dendritic polymer with a highly branched structure. Compared with linear polymers, the hyperbranched polymer has the advantages of more molecular branch points, less molecular chain winding, difficult crystallization, high solubility and small influence on system viscosity, and the molecules can have a plurality of functional group end groups, so that the modified hyperbranched polymer can endow more performances to the material.

Therefore, the aqueous hyperbranched polyacrylate modifier emulsion which has good water solubility, stability in water environment, difficult sedimentation, small particle size and low viscosity, is simple in preparation process, can effectively reduce the water absorption of target wood and improve the stability of the target wood, and the preparation method and the application thereof are urgently needed in the market.

Disclosure of Invention

The invention aims to provide the aqueous hyperbranched polyacrylate emulsion which has good water solubility, stability in water environment, small particle size, low viscosity and simple preparation process, is not easy to settle, effectively reduces the water absorption of target wood and improves the stability of the target wood.

Another aspect of the invention is to provide a preparation method of the aqueous hyperbranched polyacrylate emulsion.

Still another aspect of the present invention is to provide the use of such aqueous hyperbranched polyacrylate emulsions.

In order to achieve the purpose, the invention adopts the following technical scheme: the aqueous hyperbranched polyacrylate emulsion for wood comprises, by weight, 0.9-1.1 parts of diethanolamine, 1-1.5 parts of a polymerization monomer, sufficient methanol, 5-6 parts of glycidyl methacrylate, 0.9-1.1 parts of an N, N-dimethylethanolamine catalyst, 60-70 parts of methyl methacrylate, 70-80 parts of butyl acrylate, 4-6 parts of acrylic acid, 3-4 parts of a persulfate initiator, 10-22 parts of an anionic surfactant, 10-25 parts of a nonionic surfactant, sufficient deionized water, 7-10 parts of a pH regulator, 2-6 parts of a protective colloid, and 9-10 parts of an inhibitor; the polymerizable monomer is specifically one of methyl methacrylate and methyl acrylate, and is not mixed with methyl methacrylate described later.

In the aqueous hyperbranched polyacrylate emulsion, the anionic surfactant is specifically one or a mixture of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sulfosuccinic acid monoester disodium salt;

in the aqueous hyperbranched polyacrylate emulsion, the nonionic surfactant is specifically one or more of alkylphenol ethoxylates NP-10 to NP-20;

in the aqueous hyperbranched polyacrylate emulsion, the protective colloid is specifically one or more of polyethylene glycol with molecular weight of 400-4000 or polyvinyl alcohol 1788;

in the aqueous hyperbranched polyacrylate emulsion, the inhibitor is specifically one or more of ethylene glycol, propylene glycol or glycerol;

in the aqueous hyperbranched polyacrylate emulsion, the pH regulator is specifically one of ammonia water or sodium bicarbonate;

the preparation method of the aqueous hyperbranched polyacrylate emulsion for wood comprises the following steps:

1) dissolving diethanolamine in sufficient methanol, injecting into a glass container with a stirring paddle, a thermometer and a condensing tube, then adding a polymerization monomer into the diethanolamine-methanol solution, stirring at the normal temperature at the stirring speed of 180-240r/min for 2-4 hours to uniformly mix, then placing the glass container into an oil bath pot, reacting at 60 ℃ for 1 hour, then heating to 100 ℃ for 2 hours, heating to 120 ℃ for 2 hours, then heating to 150 ℃ for final reaction for 2-6 hours until a brown yellow viscous hyperbranched base polymer is obtained;

2) reducing the temperature of the hyperbranched substrate polymer obtained in the step 1) to 80 ℃, adding a mixed solution of glycidyl methacrylate and an N, N-dimethylethanolamine catalyst, stirring at a stirring speed of 180-;

3) preparing an anionic surfactant and a nonionic surfactant into an aqueous solution with the mass fraction of 20%, and preparing a protective colloid into an aqueous solution with the mass fraction of 8%; mixing the grafted hyperbranched substrate polymer with methyl methacrylate, butyl acrylate and acrylic acid, adding an anionic surfactant, a nonionic surfactant, deionized water, a pH regulator and a protective colloid, and stirring at a high speed of 1000r/min and 800-;

4) preparing a persulfate initiator into an aqueous solution with the mass fraction of 10%; adding 1/8 parts by weight of the pre-emulsion obtained in the step 3) into deionized water and the residual surfactant, heating the water bath to 72-78 ℃, adding 1/3 parts by weight of persulfate initiator, and stirring at a stirring speed of 180-;

5) adding an inhibitor into the seed liquid, simultaneously dropwise adding the residual 7/8 pre-emulsion and 2/3 persulfate initiator, completing dropwise adding within 2 hours, then keeping the temperature, increasing the rotating speed to 200-300r/min, continuing to react for 2 hours, heating to 81-85 ℃, reacting for 1.5-3 hours, cooling to room temperature, and filtering with gauze to obtain the blue-emitting aqueous hyperbranched polyacrylate emulsion.

The application of the aqueous hyperbranched polyacrylate emulsion in wood modification comprises the following steps:

1) preparing the aqueous hyperbranched polyacrylate emulsion into an emulsion with solid content of 1-8% by using water;

2) putting the wood into an anhydrous impregnation tank for vacuum treatment, wherein the vacuum degree is 0.01MPa, the treatment time is 0.5-2 hours, then stopping the vacuum treatment, adding the water-based hyperbranched polyacrylate emulsion with the solid content of 1-8% into the impregnation tank, completely immersing the wood, and then continuously vacuumizing for 4-8 hours.

3) And after the impregnation is finished, taking the wood out of the tank, drying the wood for 10 to 20 hours at the temperature of between 40 and 60 ℃, and further drying the wood for 2 to 6 hours at the temperature of 103 ℃ to finish the modification of the needed wood.

Compared with the prior art, the invention has the following advantages: (1) the invention utilizes Michel addition reaction to synthesize aqueous hyperbranched polyacrylate polymer with terminal hydroxyl, then the aqueous hyperbranched polyacrylate polymer reacts with epoxy group of glycidyl methacrylate to graft C-C double bond to the terminal of the hyperbranched polymer, and the aqueous hyperbranched polyacrylate emulsion is prepared by further adopting free radical emulsion addition polymerization. (2) The aqueous hyperbranched polyacrylate emulsion prepared by the invention has the characteristics of good water solubility, water stability and the like, is not easy to settle, has small particle size and low viscosity, and can be used for wood impregnation modification. (3) The preparation method of the aqueous hyperbranched polyacrylate modifier emulsion is relatively simple in process, and the modified wood can effectively reduce water absorption, improve dimensional stability, mechanical strength and the like. (4) The aqueous hyperbranched polyacrylate modifier emulsion prepared by the invention can be used for the dipping and spraying modification treatment of veneers, wood fibers and the like. (5) The aqueous hyperbranched polyacrylate modifier prepared by the invention can also be compounded with other wood modifiers, such as paraffin waterproof agent, CCA wood preservative and the like. Therefore, the invention has the characteristics of good water solubility, stability in water environment, difficult sedimentation, small particle size, low viscosity, simple preparation process, effective reduction of the water absorption of the target wood and improvement of the stability of the target wood.

Drawings

FIG. 1: photographs of the aqueous hyperbranched polyacrylate emulsions of examples 1 to 4.

FIG. 2: results of the measurement of the wet-swelling property of wood of examples 1 to 4 and comparative example 1.

Detailed Description

The present invention will be further described with reference to specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the present invention.

Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

Example 1

The raw materials for preparing the hyperbranched polyacrylate emulsion comprise: diethanolamine, methyl acrylate, methanol, glycidyl methacrylate, N-dimethylethanolamine, methyl methacrylate, butyl acrylate, acrylic acid, ammonium persulfate, Sodium Dodecyl Sulfate (SDS), nonylphenol polyoxyethylene ether (NP-10) polyvinyl alcohol 1788, ethylene glycol, sodium bicarbonate and deionized water;

(1) preparation of aqueous hyperbranched polyacrylate modifier emulsion

Completely dissolving diethanolamine in methanol, adding into a three-neck flask with a stirring paddle, a thermometer and a condenser, adding methyl acrylate, stirring at 180r/min at normal temperature for 2 hours to mix uniformly, wherein the molar ratio of diethanolamine to methyl acrylate is 1: 1. And then placing the three-neck flask into an oil bath kettle, reacting for 1 hour at 60 ℃, heating to 100 ℃ for 2 hours, heating to 120 ℃ for 2 hours, heating to 150 ℃ for 3 hours, and obtaining brown yellow viscous hyperbranched substrate polymer liquid.

Taking 18g of hyperbranched substrate polymer liquid, cooling to 80 ℃, adding 6g of glycidyl methacrylate and 2g of N, N-dimethylethanolamine, and stirring at the rotating speed of 180r/min for 2 hours to obtain the grafted hyperbranched substrate polymer liquid.

5g of SDS and 10g of NP-10 were mixed in advance to prepare a 20 mass% aqueous surfactant solution, 3.5g of ammonium persulfate to prepare a 10 mass% aqueous solution, and 2g of polyvinyl alcohol 1788 to prepare an 8 mass% aqueous solution.

Adding 65g of methyl methacrylate, 75g of butyl acrylate, 5g of acrylic acid and all of the grafted hyperbranched base polymer liquid, 2/3 g of surfactant aqueous solution, all of polyvinyl alcohol aqueous solution, 8g of sodium bicarbonate and 100g of deionized water into a three-neck flask, and stirring at a high speed of 800r/min in a 52 ℃ water bath for 10min to obtain a pre-emulsion.

And (3) taking 1/8 pre-emulsion, adding 45g of deionized water and the rest 1/3 aqueous solution of surfactant, heating to 75 ℃, adding 1/3 aqueous solution of ammonium persulfate, and reacting for 30min at the speed of 180r/min to obtain seed liquid.

Adding 10g of ethylene glycol into the seed liquid, increasing the rotating speed to 240r/min, simultaneously dropwise adding the rest pre-emulsion and the initiator aqueous solution, completing dropwise adding within 2 hours, keeping the temperature and the rotating speed for continuously reacting for 2 hours, then heating to 82 ℃, reacting for 1.5 hours, cooling to room temperature, and filtering with gauze to obtain the blue-emitting aqueous hyperbranched polyacrylate modifier emulsion with the solid content of 34.4%.

(2) Impregnation treatment of wood

Putting the wood into an impregnation tank for vacuum treatment (no water is in the impregnation tank), wherein the vacuum degree is 0.01MPa, the vacuum treatment time is 30min, stopping vacuum, adding a water-based hyperbranched polyacrylate emulsion modifier with the solid content of 4% (diluted by deionized water) into the impregnation tank, completely immersing the wood, and continuously vacuumizing for 8 hours. After completion of impregnation, the wood was taken out of the pot, dried at 40 ℃ for 20 hours, and further dried at 103 ℃ for 2 hours.

Example 2

The reagents were the same as in example 1 except that methyl methacrylate, sodium persulfate as the initiator, Sodium Dodecylbenzenesulfonate (SDBS) and disodium sulfosuccinate monoester (a-501) in a mass ratio of 1: 1 as the anionic surfactant, NP-15 as the nonionic surfactant, polyethylene glycol 400 as the protective colloid, propylene glycol as the inhibitor, and ammonia as the pH adjuster were used in the synthesis of the hyperbranched base polymer liquid.

(1) Preparation of aqueous hyperbranched polyacrylate modifier emulsion

Completely dissolving diethanolamine in methanol, adding into a three-neck flask with a stirring paddle, a thermometer and a condenser, adding methyl methacrylate, stirring at normal temperature at the rotating speed of 200r/min for 3 hours to uniformly mix, wherein the molar ratio of the diethanolamine to the methyl methacrylate is 1: 1.5. And then placing the three-neck flask into an oil bath kettle, reacting for 1 hour at 60 ℃, heating to 100 ℃ for 2 hours, heating to 120 ℃ for 2 hours, heating to 150 ℃ for 4 hours, and obtaining brown yellow viscous hyperbranched substrate polymer liquid.

Taking 15g of hyperbranched substrate polymer liquid, cooling to 80 ℃, adding 4g of glycidyl methacrylate and 1.5g of N, N-dimethylethanolamine, and stirring at the rotating speed of 200r/min for 4 hours to obtain the grafted hyperbranched substrate polymer liquid.

3g of SDBS, 3g A-501 and 11g of NP-15 were mixed in advance to prepare a 20 mass% aqueous surfactant solution, 4g of sodium persulfate was prepared to prepare a 10 mass% aqueous solution, and 3g of polyethylene glycol 400 was prepared to prepare an 8 mass% aqueous solution.

70g of methyl methacrylate, 70g of butyl acrylate, 6g of acrylic acid, all the grafted hyperbranched base polymer liquid, 2/3 g of surfactant aqueous solution, all the polyethylene glycol 400 aqueous solution, 10g of ammonia water and 80g of deionized water are added into a three-neck flask, and stirred at a high speed of 1000r/min in a 55 ℃ water bath for 15min to obtain the pre-emulsion.

And (3) taking 1/8 pre-emulsion, adding 65g of deionized water and the rest 1/3 surfactant aqueous solution, heating to 75 ℃, adding 1/3 sodium persulfate aqueous solution, and reacting for 30min at the speed of 200r/min to obtain seed liquid.

Adding 10g of propylene glycol into the seed liquid, increasing the rotating speed to 260r/min, simultaneously dropwise adding the rest pre-emulsion and the initiator aqueous solution, completing dropwise adding within 2 hours, keeping the temperature and the rotating speed for continuously reacting for 2 hours, then heating to 85 ℃, reacting for 3 hours, cooling to room temperature, and filtering with gauze to obtain the blue-emitting aqueous hyperbranched polyacrylate modifier emulsion with the solid content of 35.2%.

(2) Modified impregnation treatment wood

Putting the wood into an impregnation tank for vacuum treatment (no water is in the impregnation tank), wherein the vacuum degree is 0.01MPa, the vacuum treatment time is 30min, stopping vacuum, adding a water-based hyperbranched polyacrylate emulsion modifier with the solid content of 2% (diluted by deionized water) into the impregnation tank, completely immersing the wood, and continuously vacuumizing for 4 hours. After completion of impregnation, the wood was taken out of the pot, dried at 60 ℃ for 10 hours, and further dried at 103 ℃ for 6 hours.

Example 3

The reagents were the same as in example 1 except that methyl methacrylate, a nonionic surfactant NP-20, a protective colloid polyethylene glycol 4000 and an inhibitor glycerol were used in the hyperbranched base polymer liquid synthesis process.

(1) Preparation of aqueous hyperbranched polyacrylate modifier emulsion

Fully dissolving diethanolamine in methanol, adding the methanol into a three-neck flask with a stirring paddle, a thermometer and a condenser, adding methyl methacrylate, stirring at the normal temperature of 240r/min for 4 hours to uniformly mix the methyl methacrylate and the diethanolamine at the molar ratio of 1: 1.2. And then placing the three-neck flask into an oil bath kettle, reacting for 1 hour at 60 ℃, heating to 100 ℃ for 2 hours, heating to 120 ℃ for 2 hours, heating to 150 ℃ for 3 hours, and obtaining brown yellow viscous hyperbranched substrate polymer liquid.

And (3) taking 20g of hyperbranched substrate polymer liquid, cooling to 80 ℃, adding 10g of glycidyl methacrylate and 3g of N, N-dimethylethanolamine, and stirring at the rotating speed of 240r/min for 4 hours to obtain the grafted hyperbranched substrate polymer liquid.

6g of SDS and 15g of NP-20 were mixed in advance to prepare a 20 mass% aqueous solution of a surfactant, 4g of ammonium persulfate to prepare a 10 mass% aqueous solution, and 3g of polyethylene glycol 4000 to prepare an 8 mass% aqueous solution.

Adding 60g of methyl methacrylate, 80g of butyl acrylate, 6g of acrylic acid and all of the grafted hyperbranched base polymer liquid, 2/3 of surfactant aqueous solution, all of polyethylene glycol 4000 aqueous solution, 12g of sodium bicarbonate and 120g of deionized water into a three-neck flask, and stirring at a high speed of 900r/min in a 50 ℃ water bath for 30min to obtain a pre-emulsion.

Adding 85g of deionized water and the rest 1/3 of surfactant aqueous solution into 1/8 of pre-emulsion, heating to 75 ℃, adding 1/3 of ammonium persulfate aqueous solution, and reacting for 30min at the speed of 240r/min to obtain seed liquid.

Adding 15g of glycerol into the seed liquid, increasing the rotating speed to 300r/min, simultaneously dropwise adding the rest pre-emulsion and the initiator aqueous solution, completing dropwise adding within 2 hours, keeping the temperature and the rotating speed for continuously reacting for 2 hours, then heating to 85 ℃, reacting for 2 hours, cooling to room temperature, and filtering with gauze to obtain the blue-emitting aqueous hyperbranched polyacrylate modifier emulsion with the solid content of 33.1%.

(2) Modified impregnation treatment wood

Putting the wood into an impregnation tank for vacuum treatment (no water is in the impregnation tank), wherein the vacuum degree is 0.01MPa, the vacuum treatment time is 30min, stopping vacuum, adding a waterborne hyperbranched polyacrylate emulsion modifier with the solid content of 6% (diluted by deionized water) into the impregnation tank to completely immerse the wood, and then continuously vacuumizing for 6 hours. After completion of impregnation, the wood was taken out of the pot, dried at 60 ℃ for 15 hours, and further dried at 103 ℃ for 4 hours.

Example 4

The reagents were the same as in example 1 except that methyl methacrylate, Sodium Dodecyl Sulfate (SDS) and disodium sulfosuccinate monoester (A-501) were used in a mass ratio of 1: 1.2 as the anionic surfactant, polyethylene glycol 2000 was used as the protective colloid, and propylene glycol was used as the inhibitor during the synthesis of the hyperbranched base polymer liquid.

(1) Preparation of aqueous hyperbranched polyacrylate modifier emulsion

Completely dissolving diethanolamine in methanol, adding into a three-neck flask with a stirring paddle, a thermometer and a condenser, adding methyl methacrylate, stirring at 220r/min at normal temperature for 3 hours to mix uniformly, wherein the molar ratio of diethanolamine to methyl methacrylate is 1: 1.2. And then placing the three-neck flask into an oil bath kettle, reacting for 1 hour at 60 ℃, heating to 100 ℃ for 2 hours, heating to 120 ℃ for 2 hours, heating to 150 ℃ for 4 hours, and obtaining brown yellow viscous hyperbranched substrate polymer liquid.

Taking 16g of hyperbranched substrate polymer liquid, cooling to 80 ℃, adding 9g of glycidyl methacrylate and 1g of N, N-dimethylethanolamine, and stirring at the rotating speed of 220r/min for 3 hours to obtain the grafted hyperbranched substrate polymer liquid.

5g of SDS, 6g A-501 and 10g of NP-20 were mixed in advance to prepare a 20 mass% aqueous solution of a surfactant, 3.5g of ammonium persulfate to prepare a 10 mass% aqueous solution, and 5g of polyethylene glycol 2000 to prepare an 8 mass% aqueous solution.

70g of methyl methacrylate, 75g of butyl acrylate, 5g of acrylic acid and all of the grafted hyperbranched base polymer liquid, 2/3 g of surfactant aqueous solution, all of polyethylene glycol 2000 aqueous solution, 6g of sodium bicarbonate and 110g of deionized water are added into a three-neck flask, and stirred at a high speed of 800r/min in a 50 ℃ water bath for 30min to obtain a pre-emulsion.

And (3) adding 40g of deionized water and the rest 1/3 of aqueous solution of surfactant into 1/8 of pre-emulsion, heating to 75 ℃, adding 1/3 of aqueous solution of ammonium persulfate, and reacting for 30min at the speed of 220r/min to obtain seed liquid.

Adding 12g of glycerol into the seed liquid, increasing the rotating speed to 280r/min, simultaneously dropwise adding the rest pre-emulsion and the initiator aqueous solution, completing dropwise adding within 2 hours, keeping the temperature and the rotating speed for continuously reacting for 2 hours, then heating to 85 ℃, reacting for 3 hours, cooling to room temperature, and filtering with gauze to obtain the blue-emitting aqueous hyperbranched polyacrylate modifier emulsion with the solid content of 32.8%.

(2) Modified impregnation treatment wood

Putting the wood into an impregnation tank for vacuum treatment (no water is in the impregnation tank), wherein the vacuum degree is 0.01MPa, the vacuum treatment time is 30min, stopping vacuum, adding a water-based hyperbranched polyacrylate emulsion modifier with the solid content of 8% (diluted by deionized water) into the impregnation tank to completely immerse the wood, and then continuously vacuumizing for 7 h. After completion of impregnation, the wood was taken out of the pot, dried at 50 ℃ for 18 hours, and further dried at 103 ℃ for 3 hours.

Comparative example 1

The experimental procedure was the same as in example 1 except that deionized water was used for the impregnation treatment of the wood.

And (3) performance testing:

detection of performance of aqueous hyperbranched polyacrylate modifier emulsion

The aqueous hyperbranched polyacrylate modifier emulsions of examples 1 to 4 were tested in terms of appearance, solid content, viscosity, average particle size, storage stability, and water dilutability 5, and the results are shown in Table 1.

The solid content determination method comprises the following steps: 5g of each of the emulsions obtained in examples 1 to 4 were taken, and put into an oven at 103 ℃ to be dried to constant weight, and the solid content was obtained by calculating the mass percentage of the dried residue to the total amount.

The viscosity was measured using a rotational viscometer.

The average particle size was measured using a Delsa Nano model C laser particle sizer.

TABLE 1 emulsion Property measurements

The test results show that examples 1 to 4 are all yellowish homogeneous emulsions which are bluish, have particle sizes of between 100 and 250nm and viscosity values of between 80 and 120 mPas, and still maintain good storage stability and water dilutability and are easy to disperse.

Second, measurement of Wet swelling Property of treated Material

Examples 1 to 4 and comparative example 1 were subjected to a wood swelling property test with reference to the national standard "method for measuring wood swelling property" (GB/T1934.2-2009), and the results are shown in FIG. 2.

The results show that compared with the comparative example 1, the water absorption expansion rates of the examples 1 to 4 are all reduced, the dimensional stability of the wood is obviously improved, and the dimensional stability of the wood can be improved after the aqueous hyperbranched polyacrylate modifier emulsion enters the wood for curing.

Thirdly, measuring the bending strength and the bending elastic modulus of the treated material

Examples 1 to 4 and comparative example 1 were subjected to bending strength and bending modulus tests with reference to national standards "method for testing bending strength of wood" (GB/T1936.1-2009) and "method for testing bending modulus of elasticity of wood" (GB/T1936.2-2009), and the results are shown in table 2.

TABLE 2 compressive strength of wood along grain and transverse grain

The results show that the bending strength and the bending elastic modulus of the wood are both obviously improved compared with those of the comparative example 1, and the synthesized aqueous hyperbranched polyacrylate modifier emulsion can enter the wood more easily and can play a role in crosslinking after being cured, so that the bending strength and the bending elastic modulus of the wood are improved.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. The water-based hyperbranched polyacrylate emulsion is characterized in that raw materials of the water-based hyperbranched polyacrylate emulsion comprise, by weight, 0.9-1.1 parts of diethanolamine, 1-1.5 parts of a polymerization monomer, sufficient methanol, 5-6 parts of glycidyl methacrylate, 0.9-1.1 parts of an N, N-dimethylethanolamine catalyst, 60-70 parts of methyl methacrylate, 70-80 parts of butyl acrylate, 4-6 parts of acrylic acid, 3-4 parts of a persulfate initiator, 10-22 parts of an anionic surfactant, 10-25 parts of a nonionic surfactant, sufficient deionized water, 7-10 parts of a pH regulator, 2-6 parts of a protective colloid and 9-10 parts of an inhibitor; the polymerizable monomer is specifically one of methyl methacrylate and methyl acrylate, and is not mixed with methyl methacrylate described later.

2. The aqueous hyperbranched polyacrylate modifier emulsion of claim 1, wherein: the anionic surfactant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sulfosuccinic acid monoester disodium salt.

3. The aqueous hyperbranched polyacrylate modifier emulsion of claim 1, wherein: the nonionic surfactant is specifically one of alkylphenol ethoxylates NP-10 to NP-20.

4. The aqueous hyperbranched polyacrylate modifier emulsion of claim 1, wherein: the protective colloid is specifically one of polyethylene glycol with molecular weight of 400-4000 or polyvinyl alcohol 1788.

5. The aqueous hyperbranched polyacrylate modifier emulsion of claim 1, wherein: the inhibitor is one of ethylene glycol, propylene glycol or glycerol.

6. The aqueous hyperbranched polyacrylate modifier emulsion of claim 1, wherein: the pH regulator is ammonia water or sodium bicarbonate.

7. The process for the production of an aqueous hyperbranched polyacrylate emulsion according to any of claims 1 to 6, characterized by comprising the steps of:

1) dissolving diethanolamine in sufficient methanol, injecting into a glass container with a stirring paddle, a thermometer and a condensing tube, then adding a polymerization monomer into the diethanolamine-methanol solution, stirring at the normal temperature at the stirring speed of 180-240r/min for 2-4 hours to uniformly mix, then placing the glass container into an oil bath pot, reacting at 60 ℃ for 1 hour, then heating to 100 ℃ for 2 hours, heating to 120 ℃ for 2 hours, then heating to 150 ℃ for final reaction for 2-6 hours, and obtaining brown yellow viscous hyperbranched base polymer liquid;

2) cooling the hyperbranched substrate polymer obtained in the step 1) to 80 ℃, adding a mixed solution of glycidyl methacrylate and an N, N-dimethylethanolamine catalyst, stirring at a stirring speed of 180-;

3) preparing an anionic surfactant and a nonionic surfactant into an aqueous solution with the mass fraction of 20%, and preparing a protective colloid into an aqueous solution with the mass fraction of 8%; mixing the grafted hyperbranched substrate polymer with methyl methacrylate, butyl acrylate and acrylic acid, adding an anionic surfactant, a nonionic surfactant, deionized water, a pH regulator and a protective colloid, and stirring at a high speed of 1000r/min and 800-;

4) preparing a persulfate initiator into an aqueous solution with the mass fraction of 10%; adding 1/8 parts by weight of the pre-emulsion obtained in the step 3) into deionized water and the residual surfactant, heating the water bath to 72-78 ℃, adding 1/3 parts by weight of persulfate initiator, and stirring at a stirring speed of 180-;

5) adding an inhibitor into the seed liquid, simultaneously dropwise adding the residual 7/8 pre-emulsion and 2/3 persulfate initiator, completing dropwise adding within 2 hours, then keeping the temperature, increasing the rotating speed to 200-300r/min, continuing to react for 2 hours, heating to 81-85 ℃, reacting for 1.5-3 hours, cooling to room temperature, and filtering with gauze to obtain the blue-emitting aqueous hyperbranched polyacrylate modifier emulsion.

8. Use of an aqueous hyperbranched polyacrylate modifier emulsion according to any one of claims 1-6 in wood modification, comprising the steps of:

1) preparing the aqueous hyperbranched polyacrylate modifier emulsion into an emulsion with solid content of 1-8% by using water;

2) putting the wood into an anhydrous impregnation tank for vacuum treatment, wherein the vacuum degree is 0.01MPa, the treatment time is 0.5-2 hours, then stopping the vacuum treatment, adding the aqueous hyperbranched polyacrylate modifier emulsion with the solid content of 1-8% into the impregnation tank, completely immersing the wood, and then continuously vacuumizing for 4-8 hours.

3) And after the impregnation is finished, taking the wood out of the tank, drying the wood for 10 to 20 hours at the temperature of between 40 and 60 ℃, and further drying the wood for 2 to 6 hours at the temperature of 103 ℃ to finish the modification of the needed wood.

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