CN112223462B

CN112223462B - Treatment method for preventing wood from cracking through penetration and solidification

Info

Publication number: CN112223462B
Application number: CN202011096290.6A
Authority: CN
Inventors: 朱国礼
Original assignee: Hunan Da'an Wood Industry Co ltd
Current assignee: Anhua Zhendong Wood Industry Co ltd
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2022-03-22
Anticipated expiration: 2040-10-14
Also published as: CN112223462A

Abstract

The invention belongs to the technical field of wood treatment, and particularly relates to a treatment method for preventing wood from cracking through penetration and solidification. The specific technology is as follows: firstly, cutting wood into a board with a certain thickness, permeating calcium ions in advance, and then permeating silicate ions to enable silicate and the calcium ions which are permeated in advance to generate a calcium silicate condensate in an internal gap of the wood, so that the calcium silicate is solidified in fiber gaps, knot defect gaps and wormhole micropore gaps of the wood after the calcium silicate is leveled and shaped, the wood is densified, and the wood is prevented from being deformed and cracked. Calcium silicate is formed in the wood gaps through infiltration and solidification, and the calcium silicate is used as an inorganic substance, has good stability and cannot deform due to moisture and heating, so that the wood is stable and does not crack. Further, wood is coated by compounding the water-based wood wax oil and the polytetrafluoroethylene emulsion, and the wood wax oil is permeable into the wood, so that the wood is favorably prevented from being water; the polytetrafluoroethylene emulsion not only has the bonding film-forming property, but also makes the wood waterproof and crack-proof by matching with the water-based wood wax oil.

Description

Treatment method for preventing wood from cracking through penetration and solidification

Technical Field

The invention belongs to the technical field of wood treatment, and particularly relates to a treatment method for preventing wood from cracking through penetration and solidification.

Background

With the rapid development of architectural decoration industry, wooden furniture manufacturing industry, cultural and educational office supplies and the like, the demand for wooden furniture is rapidly developed. The wood product industry in China is from the primary processing of logs to the perfection of various industrial chains such as artificial boards, laminated wood and the like, and an independent industrial system is formed at present. In order to meet the huge market demand, composite wood, artificial board, laminated wood and the like are adopted to replace the original wood for furniture at present. However, the environmental and health problems are also raised. Thus, people prefer to use raw wood furniture. However, because the raw wood grows naturally, the raw wood has more defects, such as knots, discoloration, wormholes, cracks and the like, which influence the use of the raw wood, and waste is caused during the material selection. Because the wood mainly comprises wood fiber, gum and water, the fiber density of the wood is different according to different varieties of trees, for example, the hard wood has a longer growth period, is hard and has high fiber density and is easy to crack; the soft wood has short growth period, soft wood, low fiber density and easy deformation. The swelling and drying shrinkage of wood and various deformations such as warping and cracking caused by non-uniform dimensional changes are the most difficult problems in wood processing and utilization. In addition, the presence and variation of moisture is also a cause of dimensional instability of the wood. The problem of easy cracking and deformation of wood causes the furniture made of the primary wood to have warping, deformation and cracking, thereby causing the household quality to be reduced and the quality to be unstable.

Conventionally, in order to prevent wood cracking, various technical means are employed: (1) the drying technology comprises the following steps: the moisture content of the wood is controlled between 8 percent and 12 percent by adopting drying, so that the moisture content of the wood is controlled at a level which is adaptive to the local average air humidity, the excessive exchange of the air and the moisture in the wood is reduced, a relative balance is kept, and the wood is not easy to crack and deform. However, this is only a relative balance, and the moisture content of wood changes with the external environment and humidity, so that warpage cracking inevitably occurs. (2) Adopting a high-temperature technology: the high-temperature treatment is adopted, the high-temperature heat treatment of the wood refers to the heating treatment of the wood at the temperature of 160-230 ℃, and some chemical properties and physical properties of the heat-treated wood are permanently changed. The change of the properties is caused by the pyrolysis of hemicellulose, and the heat-treated wood has reduced drying shrinkage and wet swelling caused by different humidity, deepens the color and is difficult to control the deformation. (3) Mechanical anti-cracking technology: the ends of the dried wood are tied by iron wires, anti-cracking rings, combined nail plates and the like are used, and the wood is forced not to expand and contract by a mechanical method, so that the cracking of the wood can be avoided, but the processing and the use of furniture are seriously influenced. (4) The waterproof coating brushing technology comprises the following steps: the end part and the surface of the wood are coated with the waterproof paint, so that the evaporation strength of the surface of the wood is reduced, the gradient of the water content inside and outside the wood can be reduced, and the cracking of the wood can also be reduced. The method prevents cracking only during the preservation stage, but cracking inevitably occurs when the wood is processed into furniture.

The technology only prevents the cracking of the wood from the appearance, but the wood is finally changed into a thin plate material and processed into furniture, the environmental humidity of the furniture is changed, and the furniture is also deformed and even cracked.

In view of the problem that the wood still cracks after being processed into furniture, the existing better wood processing technology is to immerse the wood into a waterproof agent, so that the waterproof agent fully permeates the wood, the surface layer is waterproof to be changed into integral waterproof, and even if the furniture is processed into a thin plate, the wood has good anti-cracking and anti-deformation characteristics due to excellent waterproof performance. However, when the wood treated in the above way is processed, because the wood has fiber structures in different directions, the stress difference of the surface, the inner layer, the end part and the annual ring part is huge, the wood has anisotropy, and under the condition of the same temperature and humidity change, the stress of each part is different, even the wood fully subjected to waterproof treatment generates surface crack, internal crack, end crack and wheel crack due to the structural stress in different directions, so that deformation and cracking are caused; particularly, when the plate with the pith is dried, severe splitting is easy to occur. In addition, the prepared furniture is also cracked due to stress difference under the influence of defects such as wood knots and wormholes. This drawback seriously affects the quality of the furniture. In order to obtain high-quality wooden furniture, the texture of the same board is required to be the same as much as possible according to the texture of wood so as to prevent cracking, and defects such as knots and insect eyes are required to be selected to avoid, so that a great amount of waste is caused.

Disclosure of Invention

The characteristic that the wood is easy to crack easily leads to the buckling deformation of furniture, while the prior art mainly focuses on controlling moisture, but because the wood has fiber structures in different directions, the stress difference of the surface, the inner layer, the end part and the annual ring part is huge, and the cracking of the wood is difficult to be effectively prevented only by controlling the moisture. In view of the above, the present invention provides a treatment method for preventing wood cracking by penetration curing.

A treatment method for preventing wood from cracking through penetration and solidification is characterized by comprising the following specific treatment methods:

step 1: changing wood into a board, drying until the moisture content is 8-10%, and then immersing the board in a saturated calcium chloride solution for 1-2 h; then taking out the plate, naturally standing for 30-60min until no obvious liquid exists on the surface of the plate, further immersing the plate into a sodium silicate solution to enable the sodium silicate solution to fully permeate the plate, controlling the immersion time to be 0.5-1h, and taking out the plate;

step 2: conveying the plate treated in the step 1 to a leveling clamping plate, flatly placing the plate between the leveling clamping plates, applying pressure of 2-3MPa for shaping and leveling, simultaneously heating the leveling clamping plate at a constant temperature of 60-80 ℃, generating calcium silicate from calcium ions and silicate ions permeated in the plate for curing, and leveling at the constant temperature for 2-3h to obtain a pretreated plate;

and 3, uniformly mixing the water-based wood wax oil and the polytetrafluoroethylene emulsion in a mass ratio of 3:1 to obtain a waterproof agent, spraying the waterproof agent on the pretreated board obtained in the step 2, enabling the waterproof agent to penetrate the board, and ventilating and naturally drying to obtain the anti-cracking wood board.

Preferably, the wood in the step 1 is one of pine, spruce, birch and poplar; the wood is changed into the board with different thicknesses, which is beneficial to the penetration of saturated calcium chloride solution, in particular, the wood is changed into the board with the thickness less than 5 cm; the plate is too thick to allow the saturated calcium chloride solution to effectively permeate inside.

Drying the wood to generate water-absorbing micropores, which is beneficial to the subsequent penetration of calcium chloride solution; drying to a low water content will cause the drying crack of wood, while a high water content will not facilitate the penetration of calcium chloride solution. Preferably, the drying in step 1 controls the moisture content to be 9%.

Preferably, the mass concentration of the sodium silicate solution in the step 1 is 15-20%; the sodium silicate is an inorganic adhesive, and silicate radicals and pre-permeated calcium ions generate a calcium silicate condensate through the permeation of the sodium silicate, so that the calcium silicate is solidified in fiber gaps, knot defect gaps and wormhole micropore gaps of the wood after the leveling and shaping, the wood is densified, and the wood is prevented from being deformed and cracked. Calcium silicate is formed in the wood gaps through infiltration and solidification, and the calcium silicate is used as an inorganic substance, has good stability and cannot deform due to moisture and heating, so that the wood is assisted to be stable and does not crack. In addition, calcium silicate is an inorganic substance, has no volatile matter left in the wood, and is a healthy and environment-friendly substance; meanwhile, the basic cutting, planing, milling, drilling and other processing of the wood can be met. More beneficial is that the wood cured by calcium silicate is compact and has heavy hand feeling, which is beneficial to improving the quality of furniture.

Preferably, the flat clamping plates in step 2 are steel clamping plates, the plates are clamped between the steel clamping plates, the plates are flattened by pressurizing, and silicate radicals and calcium ions penetrating into the plates are further solidified to form calcium silicate through constant temperature treatment, so that flat and solidified plates are obtained.

Preferably, the aqueous wood wax oil in step 3 is prepared by emulsifying linseed oil, castor oil, soybean oil and carnauba wax, and commercially available aqueous wood wax oil can also be purchased. The wood waterproof paint has good permeability to wood, and can permeate into the wood, so that the wood is beneficial to water resistance; the polytetrafluoroethylene emulsion is 12% emulsion in mass concentration, has good bonding film forming property and good hydrophobicity, and is matched with aqueous wood wax oil to further treat wood so as to prevent water and cracking of the wood.

The deformation and cracking of the wood are not only influenced by moisture, but also are fundamentally anisotropic, and the stress difference is large at different parts of the wood, so that the deformation and cracking are caused; as is well known to those skilled in the art, wood is a fibrous flexible material and is easily deformed; and the fiber compactness of the wood is not easy, even if the same tree is used, the fiber compactness of the root, the middle part and the top is greatly different, and the wood is easy to crack especially for knots, wormholes and the like with defects. In order to solve the problem in wood processing, the creative practice of the invention utilizes the penetration and solidification of inorganic matters in wood so as to stabilize the structure of the wood and obviously reduce deformation cracking in order to obtain high-quality furniture. Specifically, firstly, wood is cut into a board with a certain thickness, calcium ions are permeated in advance, then silicate ions are permeated, and silicate ions and the calcium ions which are permeated in advance generate a calcium silicate condensate in an internal gap of the wood, so that the calcium silicate is solidified in a fiber gap, a knot defect gap and a wormhole micropore gap of the wood after the leveling and shaping, the wood is densified, and the wood is prevented from being deformed and cracked. Calcium silicate is formed in the wood gaps through infiltration and solidification, and the calcium silicate is used as an inorganic substance, has good stability and cannot deform due to moisture and heating, so that the wood is stable and does not crack. Further, wood is coated by compounding the water-based wood wax oil and the polytetrafluoroethylene emulsion, and the wood wax oil is permeable into the wood, so that the wood is favorably prevented from being water; the polytetrafluoroethylene emulsion not only has the bonding film-forming property, but also has good hydrophobicity, and the wood is waterproof and crack-resistant by matching with the water-based wood wax oil.

Compared with the prior art of preventing wood from cracking, the processing method for preventing wood from cracking through penetration and solidification has the outstanding characteristics and remarkable progress that:

(1) the wood treated by the method is stable in curing and insensitive to external temperature and moisture, and the problem that the cracking is difficult to fundamentally solve by single waterproof treatment is solved.

(2) The invention can improve the compactness of the wood, thereby improving the quality of the wood.

(3) The invention can bond and solidify the defects of knots, wormholes and the like of the wood by permeating and solidifying the inorganic substance, weaken the defects and prevent cracking.

(4) The treatment method for preventing the wood from cracking has the advantages of simple and easily-controlled process and low cost, and is suitable for batch industrial treatment of the wood.

Drawings

The technical scheme of the invention is further explained by combining the accompanying drawings as follows:

FIG. 1 is a schematic process flow diagram of the treatment method for preventing wood cracking by penetration curing according to the present invention; wherein:

1-the sheet is immersed in a saturated calcium chloride solution;

2-immersing the plate into a sodium silicate solution;

3-shaping and flattening;

4-spraying a waterproof agent;

and 5-natural drying.

FIG. 2 is a cross-sectional view of a pine board treated in example 1, showing good compaction, no warping, and no cracking.

FIG. 3 is a cross-sectional view of an untreated pine board reference sample of comparative example 3, with cracking occurring in the middle.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the present invention will be clearly and completely described below with reference to the embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person skilled in the art without any inventive step based on the technical idea of the present invention shall fall within the scope of protection of the present invention.

Example 1

Step 1: changing pine wood into a plate with the thickness of 4cm, drying until the moisture content is 8%, and then immersing the plate in a saturated calcium chloride solution for 1 h; then taking out the plate, naturally standing for 60min until no obvious liquid exists on the surface of the plate, further immersing the plate into a sodium silicate solution with the mass concentration of 20% to ensure that the sodium silicate solution fully permeates the plate, controlling the immersion time to be 0.5h, and taking out the plate;

step 2: conveying the plate treated in the step 1 to a steel leveling clamping plate, flatly placing the plate between the leveling clamping plates, applying pressure of 3MPa to carry out shaping leveling, simultaneously heating the leveling clamping plates at a constant temperature of 80 ℃, generating calcium silicate solidification by calcium ions and silicate ions permeated in the plate, and carrying out constant temperature leveling for 2h to obtain a pretreated plate;

and 3, uniformly mixing the water-based wood wax oil and 12% of polytetrafluoroethylene emulsion in a mass ratio of 3:1 to obtain a waterproof agent, spraying the waterproof agent on the pretreated board obtained in the step 2, enabling the waterproof agent to penetrate the board, and ventilating and naturally drying to obtain the anti-cracking wood board.

Example 2

Step 1: changing pine wood into a plate with the thickness of 4cm, drying until the moisture content is 10%, and then immersing the plate in a saturated calcium chloride solution for 2 hours; then taking out the plate, naturally standing for 60min until no obvious liquid exists on the surface of the plate, further immersing the plate into a sodium silicate solution with the mass concentration of 20% to ensure that the sodium silicate solution fully permeates the plate, controlling the immersion time to be 1h, and taking out the plate;

step 2: conveying the plate treated in the step 1 to a leveling clamping plate, flatly placing the plate between the leveling clamping plates, applying pressure of 2MPa to carry out shaping leveling, simultaneously heating the leveling clamping plate at a constant temperature of 60 ℃, generating calcium silicate solidification by calcium ions and silicate ions permeated in the plate, and carrying out constant temperature leveling treatment for 3 hours to obtain a pretreated plate;

Example 3

Step 1: changing pine wood into a plate with the thickness of 3cm, drying until the moisture content is 10%, and then immersing the plate in a saturated calcium chloride solution for 1 h; then taking out the plate, naturally standing for 30min until no obvious liquid exists on the surface of the plate, further immersing the plate into a sodium silicate solution with the mass concentration of 20% to ensure that the sodium silicate solution fully permeates the plate, controlling the immersion time to be 0.5h, and taking out the plate;

step 2: conveying the plate treated in the step 1 to a leveling clamping plate, flatly placing the plate between the leveling clamping plates, applying pressure of 2MPa to carry out shaping leveling, simultaneously heating the leveling clamping plate at a constant temperature of 60 ℃, generating calcium silicate solidification by calcium ions and silicate ions permeated in the plate, and carrying out constant temperature leveling treatment for 2h to obtain a pretreated plate;

step 3, uniformly mixing the water-based wood wax oil and 12% of polytetrafluoroethylene emulsion in a mass ratio of 3:1 to obtain a waterproof agent, and mixing the waterproof agent with the polytetrafluoroethylene emulsion in a mass ratio of 1 to 3

Comparative example 1

Step 1: changing pine wood into a plate with the thickness of 8cm, drying until the moisture content is 8%, and then immersing the plate in a saturated calcium chloride solution for 1 h; then taking out the plate, naturally standing for 60min until no obvious liquid exists on the surface of the plate, further immersing the plate into a sodium silicate solution with the mass concentration of 20% to ensure that the sodium silicate solution fully permeates the plate, controlling the immersion time to be 0.5h, and taking out the plate;

Comparative example 1 only pine was treated with a panel having a thickness of 8cm by using the same treatment process as in example 1, and calcium ions and silicate were not sufficiently permeated into the interior of the wood due to its relatively thick thickness, so that cured calcium silicate was not effectively formed in the deep layer of the wood. The density increase was not significant.

Therefore, when the board is specifically processed, the board cannot be made too thick in order to allow calcium ions and silicate ions to sufficiently permeate the board. It is desirable to treat thick boards by extending the soaking time, but excessive softening of the board surface can occur if the soaking time is too long. Therefore, the method of the invention preferably treats the plate with the thickness less than 5cm, and the soaking time is controlled within 2 h.

Comparative example 2

step 2: and (3) conveying the plate treated in the step (1) to a steel leveling clamping plate, flatly placing the plate between the leveling clamping plates, applying pressure of 3MPa to carry out shaping leveling, simultaneously heating the leveling clamping plates at a constant temperature of 80 ℃, generating calcium silicate solidification by calcium ions and silicate ions permeated in the plate, and carrying out constant temperature leveling treatment for 2h to obtain the anti-cracking treated plate.

Comparative example 2 no auxiliary treatment of wood with aqueous wood wax oil and polytetrafluoroethylene emulsion was used.

Comparative example 3

Pine is changed into a plate with the thickness of 4cm, and the plate is dried until the moisture content is 8 percent and is used as a reference sample.

The same batch of hard pine wood was selected for the pine wood used in the experiments of the present invention, and the density of the treated board is shown in table 1.

The pine boards treated in examples 1-3 and comparative examples 1-3 were immersed in water for 30min, and then dried in a drying oven at a high temperature of 70 ℃ for 2h, and the warping and cracking of the pine boards were observed as shown in table 1. FIG. 2 is a cross-section of a pine board treated in example 1, which shows good compactness, no warpage and no cracking; FIG. 3 is a cross-section of an untreated pine board reference sample of comparative example 3, with cracking occurring in the middle.

Table 1:

through tests, the density of the pine board treated by the technology is higher than that of a pine board which is not infiltrated with cured calcium silicate, and the compactness is increased. And no warping and cracking phenomenon is caused after the water soaking and heating. The untreated control 3 reference exhibited warpage and cracking.

Claims

1. A treatment method for preventing wood from cracking through penetration and solidification is characterized by comprising the following specific treatment methods:

step 1: changing wood into a board with the thickness of less than 5cm, drying until the moisture content is 8-10%, and then immersing the board in a saturated calcium chloride solution for 1-2 h; then taking out the plate, naturally standing for 30-60min until no obvious liquid exists on the surface of the plate, further immersing the plate into a sodium silicate solution to enable the sodium silicate solution to fully permeate the plate, controlling the immersion time to be 0.5-1h, and taking out the plate; the wood is one of pine, spruce, birch and poplar;

step 3, uniformly mixing the water-based wood wax oil and the polytetrafluoroethylene emulsion in a mass ratio of 3:1 to obtain a waterproof agent, spraying the waterproof agent on the pretreated board obtained in the step 2, enabling the waterproof agent to penetrate the board, and ventilating and naturally drying to obtain an anti-cracking wood board; the aqueous wood wax oil is prepared by emulsifying linseed oil, castor oil, soybean oil and carnauba wax;

the mass concentration of the sodium silicate solution in the step 1 is 15-20%;

and the mass concentration of the polytetrafluoroethylene emulsion in the step 3 is 12%.

2. The method for treating wood cracking by penetration curing according to claim 1, wherein: the flat clamping plate in the step 2 is a steel clamping plate.