CN115124971A

CN115124971A - Wood adhesive

Info

Publication number: CN115124971A
Application number: CN202110312094.6A
Authority: CN
Inventors: 朱一民
Original assignee: Dairen Chemical Corp; Chang Chun Petrochemical Co Ltd; Chang Chun Plastics Co Ltd
Current assignee: Dairen Chemical Corp; Chang Chun Petrochemical Co Ltd; Chang Chun Plastics Co Ltd
Priority date: 2021-03-24
Filing date: 2021-03-24
Publication date: 2022-09-30

Abstract

The invention provides a wood adhesive, which comprises a first component and a second component. The first component comprises gamma-polyglutamic acid, the molecular weight of the gamma-polyglutamic acid is 50000-2000000, the second component comprises quaternary ammonium salt polymer, the quaternary ammonium salt polymer is polymerized by diethylenetriamine, and the weight ratio of the first component to the second component is 1: 2-2: 1. Therefore, the wood adhesive is obtained by mixing the gamma-polyglutamic acid and the quaternary ammonium salt polymer, has no formaldehyde release and biodegradability, is beneficial to environmental protection and has cost benefit.

Description

Wood adhesives

Technical Field

The present invention relates to a wood adhesive (adhesive), and more particularly to a wood adhesive prepared from biomass raw materials.

Prior Art

The natural adhesive has the characteristics of high bonding speed, long storage time, convenient operation and low price, most of the natural adhesives are water-soluble or hot-melt adhesives, have the characteristics of no toxicity or low toxicity, do not pollute the environment and play an important role.

Under the current circumstances of high environmental protection, development and utilization of renewable resources to produce natural Adhesives are gradually regarded as important, while the usage amount of wood Adhesives accounts for more than half of all Adhesives, but more than 80% of wood Adhesives adopt Urea-formaldehyde Resin (Urea-formaldehyde Resin) and phenolic Resin (phenolic Resin) and the Resin hardening mechanism releases formaldehyde gas, which seriously pollutes the environment and endangers human health, so the current research direction gradually turns to the development of formaldehyde-free wood Adhesives.

In view of the above, how to prepare natural wood adhesives by using alternative raw materials is a goal of the related practitioners in the hope of achieving the grade of formaldehyde-free gas emission.

Disclosure of Invention

An object of the present invention is to provide a wood adhesive which uses gamma-polyglutamic acid as a main raw material, so that it can eliminate the problem of toxic formaldehyde released from the wood adhesive, and has biodegradability, which is advantageous for environmental protection and cost efficiency.

One embodiment of the present invention provides a wood adhesive comprising a first component and a second component. The first component comprises gamma-polyglutamic acid, the molecular weight of the gamma-polyglutamic acid is 50000-2000000, the second component comprises quaternary ammonium salt polymer, the quaternary ammonium salt polymer is polymerized by diethylenetriamine, and the weight ratio of the first component to the second component is 1: 2-2: 1.

The wood adhesive according to the previous embodiment, wherein the first component may include gamma-polyglutamic acid at a concentration of 5 wt% to 15 wt%, and the second component may include quaternary ammonium salt polymer at a concentration of 6 wt% to 18 wt%.

The wood adhesive according to the previous embodiment, wherein the weight ratio of the first component to the second component may be 1: 2.

The wood adhesive according to the previous embodiment, wherein the quaternary ammonium salt polymer is obtainable by polymerizing diethylenetriamine with adipic acid and then reacting with epichlorohydrin, and has a repeating unit represented by formula (I):

the wood adhesive according to the aforementioned embodiment may further include at least one of an inorganic substance and an organic filler.

The wood adhesive according to the previous embodiment, wherein the inorganic substance may include a flame retardant, and the organic filler may include at least one of flour, starch, and wood chips.

The wood adhesive according to the previous embodiment, wherein the maximum breaking strength of the wood adhesive may be 80kgf to 85 kgf.

The wood adhesive according to the previous embodiment, wherein the maximum breaking strength of the wood adhesive after being soaked in water may be 70kgf to 80 kgf.

Therefore, the wood adhesive is prepared by taking the gamma-polyglutamic acid as a main raw material and mixing the gamma-polyglutamic acid with the quaternary ammonium salt polymer, has no formaldehyde release and biodegradability, and can be applied to the aspects of high polymers, wood products, furniture, decoration or buildings in chemical processes.

Brief description of the drawings

In order to make the aforementioned and other objects, features, and advantages of the invention, as well as others which will become apparent, reference is made to the following description taken in conjunction with the accompanying drawings in which:

fig. 1A is a stress-strain diagram showing examples 1 to 3 and comparative examples 1 to 3;

fig. 1B is a stress-strain diagram illustrating examples 1 to 3;

FIG. 2A is a graph showing the stress strain before and after soaking in water of comparative example 1;

FIG. 2B is a graph showing the stress strain before and after soaking in water of comparative example 2;

FIG. 2C is a graph showing the stress strain before and after soaking in water in example 1;

FIG. 2D is a graph showing the stress strain before and after soaking for example 2;

FIG. 2E is a graph showing the stress strain before and after soaking for example 3; and

fig. 3 is a graph showing the weight versus time for example 3 and comparative example 3.

Detailed description of the preferred embodiments

Embodiments of the invention are discussed in more detail below. However, this embodiment may be an application of various inventive concepts, which may be embodied within various specific ranges. The specific embodiments are for purposes of illustration only and are not to be construed as limiting the scope of the disclosure.

In the present invention, the range represented by "one numerical value to another numerical value" is a general expression avoiding all numerical values in the range from being enumerated in the specification. Thus, recitation of a range of values herein is intended to encompass any value within the range and any smaller range defined by any value within the range, as if the range and smaller range were explicitly recited in the specification. For example, a range of "0.1 wt% to 1 wt%" encompasses a range of "0.5 wt% to 0.8 wt%", regardless of whether other values are recited in the specification.

Wood adhesives

The invention provides a wood adhesive, which comprises a first component and a second component, wherein the first component comprises gamma-polyglutamic acid, the second component comprises quaternary ammonium salt polymer, and the weight ratio of the first component to the second component is 1:2 to 2:1, preferably, the weight ratio of the first component to the second component can be 1: 2.

In detail, the first component may include gamma-polyglutamic acid at a concentration of 5 wt% to 15 wt%, the second component may include quaternary ammonium salt polymer at a concentration of 6 wt% to 18 wt%, and the first component and the second component may be separately stored and mixed until use, but the present invention is not limited thereto.

In the present invention, the first component is a main agent, which contains gamma-polyglutamic acid (gamma-PGA) having a molecular weight of 50000 to 2000000 and having a structure represented by formula (A):

wherein n is an integer.

The difference between γ -PGA and carboxymethyl cellulose used in the prior art is that γ -PGA is synthesized by biofermentation, the preparation reaction conditions are mild and the process time is short, while carboxymethyl cellulose is prepared by degreasing and bleaching cellulose, treating with sodium hydroxide to become alkali cellulose, and then reacting with chloroacetic acid, which is long in process time, still needs petrochemical process to generate waste salt, and the market price of γ -PGA is lower than that of carboxymethyl cellulose. Therefore, the wood adhesive with gamma-PGA as core of the present invention has the advantages of simple and rapid process and effectively reduced factory cost.

In general protein materials, amino acids are bonded to each other by an α -protein bond (α -peptide bond), and therefore, all of them are hydrolyzed by proteases (proteases). However, since amino acids bonded by a γ -protein bond (γ -peptide bond) are not hydrolyzed by general proteases except γ -GTP (γ -glutamyl transpeptidase), γ -PGA has a certain antibacterial property and is less putrescible.

In the invention, the second component is a wet strength enhancer, the quaternary ammonium salt polymer contained in the wet strength enhancer is polymerized by diethylenetriamine, and the quaternary ammonium salt polymer has a repeating unit shown in a formula (I):

according to the above, the quaternary ammonium salt polymer represented by formula (I) is polyamide-epichlorohydrin resin (PAE resin), which is obtained by polymerizing diethylenetriamine (diethylenetriamine) and adipic acid (adipic acid), and then reacting with epichlorohydrin. The PAE resin is water-soluble cation thermosetting resin, has the characteristics of strong humidification effect, small using amount, convenient use, easy recovery of damaged materials, no toxicity, wide applicable pH value range, easy adsorption of cellulose, lignin and wood surface fibers and the like, and is the most widely applied wet strength agent at present. The reaction formula of the quaternary ammonium salt polymer shown in the formula (I) is shown in the table I, wherein m is an integer.

The mechanism of action of wet strength enhancers is the formation of a crosslinked network at the fiber interface, respectively crosslinks between polymer molecules and between polymer and fiber. The cross-linking among the polymer molecules is that part of high molecular polymer of the wet strength resin is deposited among the fibers, a staggered chain structure is generated around the fibers, the movement among the fibers is limited, the swelling and water absorption of the fibers are prevented, the stretching deformation of paper sheets is reduced, and the like, so that the wet strength of the adhesive is increased. Taking PAE resin as an example, the PAE resin can form a structure shown as a formula (I-1) after self-crosslinking between molecules:

wherein R' is a quaternary ammonium salt polymer.

In addition, the crosslinking between the polymer and the fiber is a co-crosslinking effect, and the wet strength agent is added into the cellulose derivative and the lignin to permeate to the surface and the interior and is condensed into the high molecular polymer. The wet strength agent resin can form new bonding bonds (covalent bonds, hydrogen bonds and the like) with partial hydroxyl groups between adjacent fibers, wherein the formation of a covalent bonding crosslinking network such as a subunit ether bond and the like is most critical for increasing the wet strength of the paper, because the wet strength agent resin is a water-resistant chain bond and has the insoluble and infusible properties. In addition, part of the wet strength agent resin is distributed on the surface of the fiber, and the resin has the properties of durability and insolubility in water after being matured, so that the adhesive has good wet strength. In the case of PAE resins, they crosslink with hydrocarbon groups on wood or γ -PGA to form-O-bonds, as shown in formula (I-2):

wherein R' is gamma-PGA or cellulose, etc.

The wood adhesive of the present invention may further comprise various additives, such as at least one of inorganic or organic fillers. For example, the inorganic material may include a flame retardant, and the organic filler may include at least one of flour, starch, and wood chips, and these additives may be added to the first component or the second component, or may be added after the wood adhesive is mixed.

The present invention is further illustrated by the following specific examples to facilitate one of ordinary skill in the art in a complete utilization and practice of the invention without undue experimentation, and these examples should not be construed as limiting the scope of the invention but as merely providing illustrations of how to practice the materials and methods of the invention.

Preparation method of wood adhesive

The wood adhesives of examples 1-3 of the present invention were prepared according to the ingredients and ratios of table two. Firstly, mixing gamma-PGA and deionized water, stirring and mixing at a constant temperature of 50 ℃ for 24 hours at 250ppm while preparing to form a 10 wt% gamma-PGA solution (namely, a first component), then mixing PAE resin and deionized water, stirring and mixing at 250ppm for 24 hours to form a 12 wt% PAE solution (namely, a second component), and finally, uniformly mixing the first component and the second component in different proportions to obtain the wood adhesive of the invention.

Mechanical Strength and Water resistance test

Two wood boards were bonded with the wood adhesives of examples 1 to 3, wherein the bonding area was 2.54 × 2.54 square centimeters, and after drying at 60 ℃ for 8 hours, the mechanical strength of each example was tested. Then, the cured wood adhesive was dropped into clean water at 25 ℃ for 2 hours, and then taken out and naturally air-dried to perform a mechanical strength test to investigate how moisture in the environment affects the mechanical strength of the cured wood adhesive.

Referring to fig. 1A and 1B, fig. 1A shows stress strain diagrams of examples 1 to 3 and comparative examples 1 to 3, and fig. 1B shows stress strain diagrams of examples 1 to 3, wherein comparative example 1 is an adhesive of brand name KS Bond, comparative example 2 is an adhesive of brand name PowerBon, and comparative example 3 is an adhesive of 1:1 mixture of carboxymethyl cellulose and PAE resin. In addition, the analysis in fig. 1A and 1B shows the maximum breaking strength of examples 1 to 3 and comparative examples 1 to 3, and the measurement results are shown in table three below.

As can be seen from the above results, the fracture strength of the commercially available adhesives of comparative examples 1 to 2 was about 75kgf, while that of comparative example 3 was 86kgf, and based on this data, the fracture strength of example 3 of the present invention was 83kgf, which is the best adhesive performance.

Referring to fig. 2A, 2B, 2C, 2D and 2E, fig. 2A shows stress-strain diagrams before and after soaking of comparative example 1, fig. 2B shows stress-strain diagrams before and after soaking of comparative example 2, fig. 2C shows stress-strain diagrams before and after soaking of example 1, fig. 2D shows stress-strain diagrams before and after soaking of example 2, and fig. 2E shows stress-strain diagrams before and after soaking of example 3. From the analysis of fig. 2A to 2E, the maximum breaking strength before and after soaking of examples 1 to 3 and comparative examples 1 to 2 can be obtained, and the measurement results are shown in table four below.

As can be seen from the above results, the commercial adhesive of comparative example 2 and examples 1 to 3 of the present invention all have a slightly decreased strength, which may be caused by moisture evaporating from the surface of the wood due to the action of drying the wood after it is wetted, and the decrease in the thickness of the water film in the cells may cause the mechanical properties to be weakened, and the bond between the adhesive and the wood may be broken by the moisture, resulting in the mechanical strength to be weakened. Example 3 of the present invention, although somewhat degraded, did not perform as a whole as compared to commercially available adhesives.

Biodegradability test

After example 3 and comparative example 3 were put in an oven, they were heated at 60 ℃ for 8 hours to remove excess water, and then buried in culture soil at 37 ℃ and a pot of clear water was put in this environment to maintain the moisture content in the space, and the dry weight was measured on different days (when measured, they were put in an oven to be dried) to observe the weight change, and the biodegradability of the wood adhesive was investigated.

Referring to FIG. 3, a graph of weight versus time for example 3 and comparative example 3 is shown, wherein the initial weight for example 3 is 4.802 grams and the initial weight for comparative example 3 is 2.438 grams. As can be seen from the results of fig. 3, the weight loss of example 3 after 22 days was greater than that of comparative example 3, and it can be understood that the wood adhesive of the present invention has biodegradability due to the γ -PGA, and thus can be expanded to various applications.

In addition, the results of comparing the wood adhesive of the present invention with other adhesives are shown in the following table five, in which comparative example 4 is an adhesive made of soy protein powder, and comparative example 5 is a urea-formaldehyde resin adhesive. The results in table five show that the wood adhesive of the invention has no formaldehyde gas release, low cost and good water resistance, and importantly, the preparation process is simple and quick, and can effectively reduce the factory cost, unlike the prior art that the adhesive of the soybean protein powder has the problems of grain robbing with terrestrial organisms and quick decay.

In summary, the biomass material used in the wood adhesive of the present invention is γ -PGA, and the adhesive obtained by mixing the γ -PGA with the quaternary ammonium salt polymer has advantages of no formaldehyde gas release, low cost, good water resistance, simple and fast process, biodegradability, no biological robbing with the earth, no odor problem due to fast decay, and is beneficial to environmental protection and economic advantages compared to the adhesive in the prior art.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Description of the symbols

Is free of

Claims

1. A wood adhesive, characterized in that it comprises:

-a first component comprising gamma-polyglutamic acid having a molecular weight of 50000 to 2000000; and

-a second component comprising a quaternary ammonium salt polymer, the quaternary ammonium salt polymer being polymerized from diethylenetriamine;

wherein the weight ratio of the first component to the second component is between 1:2 and 2: 1.

2. The wood adhesive of claim 1, wherein the first component comprises gamma-polyglutamic acid at a concentration of 5 wt% to 15 wt%.

3. The wood adhesive of claim 1, wherein the second component comprises the quaternary ammonium salt polymer in a concentration of 6 wt% to 18 wt%.

4. The wood adhesive of claim 1, wherein the weight ratio of the first component to the second component is 1: 2.

5. The wood adhesive of claim 1, wherein the quaternary ammonium salt polymer is obtained by polymerizing diethylenetriamine with adipic acid, followed by reaction with epichlorohydrin, and the quaternary ammonium salt polymer has a repeating unit represented by formula (I):

6. the wood adhesive of claim 1, further comprising at least one of an inorganic substance and an organic filler.

7. The wood adhesive of claim 6, wherein the inorganic substance comprises a flame retardant.

8. The wood adhesive of claim 6, wherein the organic filler comprises at least one of flour, starch, and wood chips.

9. The wood adhesive of claim 1, wherein the maximum breaking strength of the wood adhesive is 80kgf to 85 kgf.

10. The wood adhesive according to claim 1, wherein the maximum breaking strength of the wood adhesive after water immersion is 70kgf to 80 kgf.