Preparation method of polyurethane adhesive dispersion liquid for artificial board production

Abstract

The invention relates to the technical field of polyurethane adhesives, in particular to a preparation method of a polyurethane adhesive (MDI) dispersion liquid for producing and processing wood artificial boards, which comprises the step of dispersing a surfactant in water to form a suspension liquid. The dispersion liquid prepared by the method can be matched with the polyurethane adhesive for use, the polyurethane adhesive is dispersed and diluted, the use amount of the polyurethane adhesive can be reduced, and meanwhile, the coating uniformity of the polyurethane adhesive is improved.

Description

Technical Field

[0001] The present application relates to the technical field of polyurethane adhesive (MDI) for wood-based panels, and in particular to a method for preparing a dispersion of polyurethane adhesive (MDI) for producing and processing wood-based panels, wherein the dispersion can be used in combination with the polyurethane adhesive. Background Art

[0002] Wood-based panels are made by mixing wood fibers or wood shavings with adhesives and hot pressing. Currently, polyurethane adhesives are commonly used to bond wood fibers or wood shavings. When applying the adhesive, pure polyurethane adhesive is directly poured into the adhesive tank and then sprayed on the surface of the wood fibers or wood shavings through an output pump.

[0003] However, the technical solution of directly spraying pure polyurethane adhesive has the following problems: Pure polyurethane adhesive itself has a very high viscosity. Even if it is sprayed and stirred, it is not easy to disperse evenly in wood units (such as wood fibers, wood shavings, etc.), which easily leads to uneven application of glue.

[0004] The use of pure polyurethane adhesive results in a relatively large amount of adhesive, which is not conducive to cost control and environmental protection. At the same time, in the prior art, in order to overcome the problem of uneven glue application, the glue application amount is often increased. Although this problem can be overcome to a certain extent, it will increase production costs and cause the density of the board to be higher than the set value.

[0005] To this end, the inventors have also proposed a dispersion liquid that can be used in conjunction with a polyurethane adhesive. When used in conjunction with the dispersion liquid, the amount of glue applied and the production cost can be reduced while ensuring the adhesive properties of the adhesive, and the uniformity of the dispersion of the adhesive can be improved. However, the prior art lacks a method for preparing the dispersion liquid. Therefore, this case proposes a method for preparing a polyurethane adhesive for the production of wood-based panels. Summary of the invention

[0006] In order to solve the above problems, the present application provides a method for preparing a polyurethane adhesive dispersion for use in the production of artificial boards.

[0007] In one aspect, the present application provides a method for preparing a polyurethane adhesive dispersion for use in the production of artificial boards, which specifically adopts the following technical solution: A method for preparing a dispersion of a polyurethane adhesive used in the production of wood-based panels comprises the steps of dispersing a surfactant in water to form a suspension.

[0008] Preferably, after the water is stabilized under the stirring speed of 100 rpm-150 rpm, the surfactant is added, and the stirring and dispersion is continued at the stirring speed of 200 rpm-250 rpm for more than 30 minutes to obtain the dispersion.

[0009] Preferably, the mass ratio of the water to the surfactant is (50-65):(1-5).

[0010] Preferably, nano silicon dioxide is added at the same time as the surface dispersant.

[0011] Preferably, the amount of nano-silicon dioxide added to the dispersion is 0.8%-2.0% of the mass of the dispersion.

[0012] Preferably, the particle size of the nano-silicon dioxide is 10nm-60nm.

[0013] As a further preference, the method further includes a step of plasticizing and modifying the nano-silicon dioxide.

[0014] As a further preference, the nano-silicon dioxide is modified by a mixture of polylactic acid and polyurethane.

[0015] As a further preference, the modification method of the nano-silicon dioxide comprises the following steps: S1. dissolving polylactic acid and polyurethane in a solvent to obtain a polylactic acid solution and a polyurethane solution; S2. The polylactic acid solution and the polyurethane solution are mixed in proportion to obtain a mixed solution; S3. Disperse the nano-silica in the mixed solution, and treat it under ultrasonic conditions for 5 min-10 min; then shake it for 3 h-5 h; S4. The solution obtained in S3 is spray-dried to obtain modified nano-silicon dioxide.

[0016] As a further preference, the mass ratio of the polylactic acid, polyurethane and nano-silicon dioxide is 1:1:(3-4).

[0017] In one aspect, the present application provides a polyurethane adhesive dispersion for the production of wood-based panels. By selecting the components of the dispersion, the polyurethane adhesive has an excellent dispersion effect and can assist the polyurethane adhesive in bonding the board.

[0018] The specific technical solutions adopted are as follows: A polyurethane adhesive dispersion for producing wood-based panels comprises water and a surfactant dispersed in the water.

[0019] Preferably, in the dispersion, the mass ratio of the water to the surfactant is (50-65):(1-5).

[0020] More preferably, the surfactant is calcium lignin sulfonate.

[0021] Preferably, the dispersion further comprises nano-silicon dioxide in an amount of 0.8%-2.0% of the mass of the dispersion.

[0022] More preferably, the particle size of the nano-silicon dioxide is 10nm-60nm.

[0023] More preferably, the nano-silicon dioxide in the dispersant is treated by plasticization modification.

[0024] More preferably, the nano-silicon dioxide in the dispersant is modified with a mixture of polylactic acid and polyurethane.

[0025] Preferably, the dispersion is used as follows: the dispersion is mixed with a pure polyurethane adhesive to obtain a polyurethane adhesive; in the polyurethane adhesive, the mass ratio of the pure polyurethane adhesive to the dispersion is (30-45):(55-70).

[0026] Preferably, the dispersion and pure polyurethane adhesive are mixed in a mixing kettle, and a unit volume of pure polyurethane adhesive is added to the mixing kettle. When the pure polyurethane adhesive is stabilized at a stirring speed of 50rpm-70rpm, the dispersion is added to the premixing device; stirring is continued at a stirring speed of 300rpm-350rpm until a polyurethane adhesive suspension is formed.

[0027] Preferably, the amount of the premixture leaving the premixing device per unit time is the same as the amount of the premixture entering the main mixing device, and the amount of the polyurethane adhesive suspension leaving the main mixing device per unit time is the same as the amount of the polyurethane adhesive suspension sprayed onto the wood particles.

[0028] Preferably, the dispersion of the present application is prepared and used immediately.

[0029] The dispersion provided in the present application is used in combination with a polyurethane adhesive to disperse and dilute the polyurethane adhesive, thereby reducing the usage of the polyurethane adhesive and increasing the uniformity of the polyurethane adhesive coating. It also further uses nano-silica / modified nano-silica to synergistically increase the bonding effect of the polyurethane adhesive on the plate, thereby ensuring that the bonding effect of the polyurethane adhesive is not reduced or even improved while reducing the usage of the polyurethane adhesive.

[0030] Furthermore, the preparation method provided in the present application can further reduce the viscosity of the polyurethane adhesive, so that the adhesive is more suitable for spraying. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application. Example

[0032] A polyurethane adhesive dispersion for producing wood-based panels, the dispersion comprising water and a surfactant dispersed in the water, wherein the water comprises 90.9 g and the surfactant comprises 9.1 g, and the surfactant is calcium lignin sulfonate. Example

[0033] A polyurethane adhesive dispersion for producing wood-based panels, the dispersion comprising water and a surfactant dispersed in the water, wherein the water comprises 98.3 g and the surfactant comprises 1.7 g, and the surfactant is calcium lignin sulfonate. Example

[0034] A polyurethane adhesive dispersion for producing wood-based panels, the dispersion comprising water and a surfactant dispersed in the water, wherein the water comprises 98.5 g and the surfactant comprises 1.5 g, and the surfactant is calcium lignin sulfonate. Example

[0035] A polyurethane adhesive dispersion for producing wood-based panels, comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the dispersion comprises 96.4 g of water, 1.6 g of a surfactant and 2 g of nano-silicon dioxide, wherein the surfactant is calcium lignin sulfonate and the particle size of the nano-silicon dioxide is 20 nm-60 nm. Example

[0036] A polyurethane adhesive dispersion for producing wood-based panels, comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the dispersion comprises 97.4 g of water, 1.6 g of a surfactant and 1 g of nano-silicon dioxide, wherein the surfactant is calcium lignin sulfonate and the particle size of the nano-silicon dioxide is 20 nm-60 nm. Example

[0037] A polyurethane adhesive dispersion for producing wood-based panels, comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the dispersion comprises 97.5 g of water, 1.7 g of a surfactant and 0.8 g of nano-silicon dioxide, wherein the surfactant is calcium lignin sulfonate and the particle size of the nano-silicon dioxide is 20 nm-60 nm. Example

[0038] A polyurethane adhesive dispersion for the production of wood-based panels, the dispersion comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the water comprises 96.4 g, the surfactant comprises 1.6 g, and the nano-silicon dioxide comprises 2 g, wherein the surfactant is calcium lignin sulfonate. The nano-silicon dioxide is modified nano-silicon dioxide obtained by the following method: S1. The polylactic acid and the polyurethane were dissolved in an acetone solvent to obtain a polylactic acid solution having a concentration of 5 mg / L and a polyurethane solution having a concentration of 5 mg / L; S2. The polylactic acid solution and the polyurethane solution were mixed in a ratio (the mass ratio of polylactic acid, polyurethane and nano-silica was 1:1:4) to obtain a mixed solution; S3. Disperse the nano-silica in the mixed solution, and treat it under ultrasonic conditions for 6 minutes; then shake it for 3 hours; S4. The solution obtained in S3 is spray-dried to obtain modified nano-silicon dioxide with a particle size controlled at 60nm-80nm. Example

[0039] A polyurethane adhesive dispersion for the production of wood-based panels, the dispersion comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the water comprises 96.4 g, the surfactant comprises 1.6 g, and the nano-silicon dioxide comprises 2 g, wherein the surfactant is calcium lignin sulfonate. The nano-silicon dioxide is modified nano-silicon dioxide obtained by the following method: S1. The polylactic acid and the polyurethane were dissolved in an acetone solvent to obtain a polylactic acid solution having a concentration of 5 mg / L and a polyurethane solution having a concentration of 5 mg / L; S2. The polylactic acid solution and the polyurethane solution were mixed in a ratio (the mass ratio of polylactic acid, polyurethane and nano-silica was 1:1:3) to obtain a mixed solution; S3. Disperse the nano-silica in the mixed solution, and treat it under ultrasonic conditions for 5 minutes; then shake it for 4 hours; S4. The solution obtained in S3 is spray-dried to obtain modified nano-silicon dioxide with a particle size controlled at 60nm-80nm. Example

[0040] A polyurethane adhesive dispersion for the production of wood-based panels, the dispersion comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the water comprises 96.4 g, the surfactant comprises 1.6 g, and the nano-silicon dioxide comprises 2 g, wherein the surfactant is calcium lignin sulfonate. The nano-silicon dioxide is modified nano-silicon dioxide obtained by the following method: S1. The polylactic acid and the polyurethane were dissolved in an acetone solvent to obtain a polylactic acid solution having a concentration of 5 mg / L and a polyurethane solution having a concentration of 5 mg / L; S2. The polylactic acid solution and the polyurethane solution were mixed in a ratio (the mass ratio of polylactic acid, polyurethane and nano-silica was 1:1:3.5) to obtain a mixed solution; S3. Disperse the nano-silica in the mixed solution, and treat it under ultrasonic conditions for 8 minutes; then shake it for 3 hours; S4. The solution obtained in S3 is spray-dried to obtain modified nano-silicon dioxide with a particle size controlled at 60nm-80nm. Example

[0041] The present embodiment provides a method for preparing a polyurethane adhesive dispersion for wood-based panel production. Water is placed in a stirring tank, a surfactant is added at a stirring speed of 100 rpm, and stirring and dispersing is continued at a stirring speed of 200 rpm for more than 30 minutes. Example

[0042] The present embodiment provides a method for preparing a polyurethane adhesive dispersion for wood-based panel production. Water is placed in a stirring tank. A surfactant and nano-silicon dioxide are added at a stirring speed of 100 rpm. The stirring and dispersion are continued at a stirring speed of 200 rpm for more than 30 minutes. Example

[0043] This embodiment provides a polyurethane adhesive suspension for the production of wood-based panels, wherein the above dispersion is mixed with pure polyurethane adhesive using the following mixing device and method, and the usage amount is: the mass ratio of the pure polyurethane adhesive to the dispersion is 40:60. The polyurethane adhesive suspensions corresponding to Examples 1-9 are respectively recorded as 1, 2, 3, 4, 5, 6, 7, 8, and 9.

[0044] Mixing method: the dispersion and pure polyurethane adhesive are mixed in a mixing kettle, a unit volume of pure polyurethane adhesive is added to the mixing kettle, and when the pure polyurethane adhesive is stabilized at a stirring speed of 50 rpm, the dispersion is added to the premixing device; stirring is continued at a stirring speed of 300 rpm until a polyurethane adhesive suspension is formed.

[0045] Application Examples The dispersions in Examples 1-9 are used in combination with a polyurethane adhesive and mixed in the manner of Example 12 to obtain a polyurethane adhesive suspension for the production of wood-based panels (specifically wood fiberboards). The obtained polyurethane adhesive suspension is sprayed on the boards to achieve bonding between the boards.

[0046] Comparative Example 1 In this comparative example, pure polyurethane adhesive is sprayed on the plate. This comparative example is denoted as A.

[0047] Comparative Example 2 A dispersion of a polyurethane adhesive for producing wood-based panels, the dispersion comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the water comprises 88.5 g, the surfactant comprises 1.5 g, and the nano-silicon dioxide comprises 10 g, wherein the particle size of the nano-silicon dioxide is 10 nm-20 nm. This comparative example is denoted as B.

[0048] Comparative Example 3 A dispersion of a polyurethane adhesive for producing wood-based panels, the dispersion comprising ionized water, a surfactant and nano-silicon dioxide dispersed in the water, wherein the dispersion comprises 96.4 g of water, 1.6 g of a surfactant, and 2 g of nano-silicon dioxide, wherein the particle size of the nano-silicon dioxide is 100 nm-150 nm. This comparative example is denoted as C.

[0049] Comparative Example 4 This comparative example provides a dispersion liquid, wherein the dispersion liquid is water. This comparative example is correspondingly recorded as D.

[0050] The polyurethane adhesive suspension or polyurethane adhesive in each embodiment and comparative example is used for the production of wood fiberboard. The amount of polyurethane adhesive suspension or polyurethane adhesive used per unit area is the same. The relevant properties of the obtained wood fiberboard are tested, and the test results are as follows.

[0051] Table 1

[0052] It can be seen from Table 1 that the polyurethane adhesive suspensions corresponding to Examples 1-9, under the premise that the usage of pure polyurethane adhesive is 40%, the strength performance of the obtained panels is better than that of Comparative Example 1 using 100% pure polyurethane adhesive. It can be seen that the use of the dispersion of the present invention can greatly reduce the usage of the polyurethane adhesive while ensuring the bonding strength.

[0053] Specifically, the nano-silica in the dispersion corresponding to Examples 7-9 uses plasticized nano-silica. When the amount of pure polyurethane adhesive used is the same, the static bending strength and internal bonding strength are better than those of Examples 4-6.

[0054] In the dispersion corresponding to Comparative Example 2, compared with Example 1, the amount of nano-silicon dioxide added is too much, which has a negative impact on the static bending strength and the internal bonding strength.

[0055] In the dispersion corresponding to Comparative Example 3, compared with Example 1, the particle size of nano-silicon dioxide is too large, which has a negative impact on the static bending strength and the internal bonding strength.

[0056] Compared with Example 1, the dispersion corresponding to Control Example 4, which only uses water as a dispersant, fails to meet the requirements of the national standard for wood fiberboard in terms of static bending strength and internal bonding strength.

[0057] The present invention also conducts an experimental analysis on the effect of the amount of the dispersion used in Example 3 of the present invention on the results. See Table 2 for some experimental data.

[0058] Table 2

[0059] As can be seen from Table 2, when the polyurethane adhesive suspension corresponding to Example 3 is used and the amount of pure polyurethane adhesive used is 30%, the strength performance of the obtained board is equivalent to that of Comparative Example 1 using 100% pure polyurethane adhesive. It can be seen that by using the dispersion of Example 1 of the present invention, the amount of pure polyurethane adhesive used can be reduced by up to 70% while ensuring that the bonding strength is equivalent to that of pure polyurethane adhesive. However, when the amount of pure polyurethane adhesive used exceeds 50%, the contribution to the internal bonding strength and static bending strength is not large.

[0060] The above description is intended to be illustrative and not limiting. Upon reading the above description, many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the appended claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the applicant has not considered the subject matter to be part of the disclosed application subject matter.

Claims

1. A method for preparing a polyurethane adhesive dispersion for use in the production of artificial boards, characterized in that: The method comprises the steps of dispersing a surfactant in water to form a suspension.

2. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 1, characterized in that: After the water is stabilized under the stirring speed of 100 rpm-150 rpm, the surfactant is added, and the stirring and dispersion is continued at the stirring speed of 200 rpm-250 rpm for more than 30 minutes to obtain the dispersion.

3. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 2, characterized in that: The mass ratio of the water to the surfactant is (50-65):(1-5).

4. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 2, characterized in that: The nano silicon dioxide is added at the same time as the surface dispersant is added.

5. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 4, characterized in that: The amount of nano silicon dioxide added to the dispersion is 0.8%-2.0% of the mass of the dispersion.

6. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 4, characterized in that: The particle size of the nano silicon dioxide is 10nm-60nm.

7. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 4, 5 or 6, characterized in that: The method also includes the step of plasticizing and modifying the nano silicon dioxide.

8. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 7, characterized in that: The nano silicon dioxide is modified by a mixture of polylactic acid and polyurethane.

9. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 8, characterized in that: The modification method of the nano silicon dioxide comprises the following steps: S1. dissolving polylactic acid and polyurethane in a solvent to obtain a polylactic acid solution and a polyurethane solution; S2. The polylactic acid solution and the polyurethane solution are mixed in proportion to obtain a mixed solution; S3. Disperse the nano-silica in the mixed solution, and treat it under ultrasonic conditions for 5 min-10 min; then shake it for 3 h-5 h; S4. The solution obtained in S3 is spray-dried to obtain modified nano-silicon dioxide.

10. The method for preparing a polyurethane adhesive dispersion for artificial board production according to claim 8, characterized in that: The mass ratio of the polylactic acid, polyurethane and nano-silicon dioxide is 1:1:(3-4).

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