RU2572312C2 - Method of production of end blocks for parquet - Google Patents

Abstract

FIELD: woodworking industry.

SUBSTANCE: timber, which is a waste of cleaning cutting or target timber, is cut using woodworking equipment to end or longitudinal workpieces. Using the mill the outer contour of the workpieces is imparted with a shape. Subsequently, the workpieces are fed to the impregnation bath with a solution of 30-50% concentration in acetone of low molecular weight polymer in the form of epoxy resin having a molecular weight of 600-1500 and containing the hardener as 10 wt % of hexamethylenediamine per 100 wt % of resin. After impregnation for 0.5-1.5 hours the workpieces are dried in a heat chamber at a temperature of 100-120°C for 1-3 hours until complete removal of volatile components.

EFFECT: increased physical and mechanical properties of the workpieces.

1 tbl, 6 ex

Description

The invention relates to the production of building materials, allows qualified recovery of waste wood processing and can be used in the woodworking, furniture and construction industries.

other methods

A known method of manufacturing an end piece for parquet boards or wall panels from softwood and softwood, including drying wood, obtaining blanks in the form of end blocks, shaping their outer contour and impregnating with synthetic rubber oligopiperylene with mol. m. 12000-30000 in the form of a 30-50% solution in nephras (Patent No. 2096171, application No. 94031039, RU C1, class B27M 3/04, B27K 3 / 34.1997).

Oligopiperylene rubber is a linear low molecular weight polymer whose chemical nature is determined by isoprene units, which causes the manifestation of plastoelastic properties characteristic of rubbers by oligopiperylene synthetic rubber. Due to the noted feature, despite the effect of hardening of wood, this impregnating composition has an inherent disadvantage associated with low polymer stiffness and, as a consequence, a decrease in the performance of parquet, namely, such important properties as hardness and abrasion.

A known method of manufacturing an end piece for parquet boards or wall panels from softwood and softwood, including drying wood, obtaining blanks in the form of end pieces, shaping their outer contour and impregnating with a 30-50% solution in nephras of a copolymer of butadiene oligomers with styrene with a pier. m. 3000-10000 (Patent No. 211 18928, RU, application N 97112601 2118928 C1, CL B27M 3/04, 1998).

The synthetic copolymer of butadiene oligomers with styrene is a linear low molecular weight polymer with a high content of bound styrene (≈65-75% wt.) And the presence of multiple bonds, due to which thermo-oxidative structuring occurs in the pores of wood. However, this type of structuring most effectively proceeds only on the surface of the wood blank, where there is a sufficient amount of atmospheric oxygen necessary for these purposes. At the same time, it is difficult to expect the formation of a strong “crosslinked” network both inside the polymer phase and at the border with wood substance, in the interfibrillar and intercellular spaces of wood. The presence of styrene fragments in the composition of the copolymer gives it increased rigidity, which is determined by the difficulty of rotation of individual segments of the macromolecule relative to the axis along the σ-bond due to the steric effect of the benzene ring. Therefore, this copolymer, combining high penetration due to low molecular weight, the ability to thermo-oxidative structuring due to high unsaturation, also has the effect of a stiffener due to the presence of polystyrene fragments in the macromolecule. However, these positive aspects of this modifier are an obstacle to the formation of a grafted, tightly "crosslinked" structure in the interfibrillar and intercellular spaces of wood and thereby limit the level of physico-mechanical properties of impregnated wood blanks achieved in this way.

Closest to the technical nature of the present invention is a method of manufacturing an end piece for parquet boards or wall panels from softwood and softwood, including drying wood, obtaining blanks in the form of end blocks, shaping their outer contour and impregnating with 30-50% a solution in nephras of a low molecular weight copolymer of 4-vinylcyclohexene-1 with maleic anhydride with a mol. m. 600-1500 - obtained on the basis of distillation residues from the rectification of the return solvent of butadiene rubber production (Patent No. 2327559, RU, application No. 2006136740, IPC V27M 3/04, V27K 3/34 C1, 2008).

The resulting effect from the use of this impregnating material is based on the use of a synthetic copolymer (CBM) containing anhydride reaction groups capable of transforming into carboxylic groups in the presence of moisture, which then interact with the metal cations of the desiccant complex to form a “crosslinked” copolymer-wood structure that provides fairly high indicators of end checkers.

However, the following disadvantages are inherent in this method.

Low functionality, determined by the content of a maximum of one hydroxyl and one carboxyl group per macromolecule of the CBM copolymer. That is, for two functional compounds there is a real possibility of the formation of only linear, elongated in a chain structures, between which attractive forces of an exclusively physical nature can arise without the formation of any chemical bonds, which does not provide the necessary level of structuring, including with the components of wood substance, which would provide a complex effect of increasing physical and mechanical properties combined with a high rate of water resistance.

The presence of the abovementioned functional groups (carboxyl and hydroxyl in the CBM and hydroxyl in the wood) allows us to obtain simple and ester bonds between the CBM macromolecules and between the CBM macromolecule and the wood cellulose component during their interaction. At the same time, at least half are ester bonds, which, in comparison with ether bonds, are less stable under extreme operating conditions. The main feature of ethers is their chemical inertness. Unlike esters, they do not hydrolyze and do not decompose with water to the starting alcohols. Esters are easily hydrolyzed to form acid and alcohol (saponification reaction). Recovery of esters leads to the formation of alcohols.

The negative point of this method is also the use of adsorption moisture in microcapillaries for structuring of CBM. In this case, water molecules are transferred from the bound state to the free state, which sharply increases their activity, which is manifested in the ability of the modified wood to absorb, absorb moisture from the outside, thus reducing the physicomechanical properties and mainly shape stability associated directly with water absorption and swelling.

The technical problem to which the invention is directed is to increase physical and mechanical properties, mainly the dimensional stability of blanks for parquet from softwood or softwood species.

To solve this problem, in a known method of manufacturing preforms for parquet, including drying wood, obtaining preforms, shaping their outer contour and impregnating with a low molecular weight polymer in solution, a low molecular weight epoxy resin of the EP-20 grade and a hardener hexamethylene tetraamine (HMDA) are used as a low molecular weight copolymer as a solution in acetone.

Thus, in the proposed method, by using an epoxy resin with higher functionality than CBM, the ability to purposefully carry out the process of structuring ES by introducing a certain amount of hardener (polyethylene polyamine - PEPA), eliminating the need for residual sorption moisture and transferring water from the bound to the free state is achieved higher level of physical and mechanical properties of stabilized wood for end parquet due to reduced water absorption scheniya and accordingly swelling modified preform.

The method is as follows. Timber, which is the waste of thinning or target wood, is cut with woodworking equipment into end or longitudinal workpieces, which, with the help of a milling cutter, are shaped into the outer contour. Subsequently, the workpieces enter the impregnation bath with a solution of 30-50% concentration in acetone of a low molecular weight epoxy resin with a mol. m. 600-1500, containing as a hardener 10 mass. including hexamethylenediamine (HMDA) per 100 mass. h resin. After impregnation for 0.5-1.5 hours, the preforms are dried in a heating cabinet at a temperature of 100-120 ° C for 1-3 hours until the volatile components are completely removed.

As a result, parquet blanks are obtained that have high physical and mechanical properties, in particular, increased values of water resistance, as well as hardness and abrasion.

The resulting effect from the use of this impregnating material can be explained as follows.

Form stability in the case of wood requires tight packing of oligomeric macromolecules in the capillaries of the cell, which is responsible for resizing the whole wood sample. At the stages of adsorption and desorption, water molecules, penetrating the cellular level, mainly through the end surface through numerous water-conducting capillaries of various kinds and due to the high hydrophilicity of the cellulose component, saturate the capillaries of the cell wall, leading to an increase in its size.

Therefore, only a dense packing of the oligomer, even at the cellular level, is not able to give the wood product sufficient shape stability. Only oligomers containing reactive functional groups capable of transformation reactions under certain conditions, including wood functional groups, provide the formation of a single structured, cross-linked complex of oligomer and wood based on strong covalent bonds and increase the hydrophobic properties of the resulting wood-polymer composite.

For the purpose of modifying the checker element of the end parquet, an ED-20 brand epoxy resin was used, which belongs to the most common polymers of this class - diane resins. The starting materials for the preparation of diane resins are epichlorohydrin (1) and diphenylol propane (2):

As a result of a two-stage reaction, including the stages of polycondensation and stepwise polymerization, diane resins are obtained, the structure of which can be expressed by the following formula:

where R is a radical

). В качестве отвердителей обычно применяют ди- и полиамины, ангидриды дикарбоновых кислот, фенолформальдегидные смолы и другие вещества.For hardening of ES various hardeners are used, which are binding agents. Crosslinking occurs due to the interaction of the hardener with hydroxyl (-OH) and epoxy groups (

) As hardeners, di- and polyamines, dicarboxylic acid anhydrides, phenol-formaldehyde resins and other substances are usually used.

If we pay attention to the functionality of the cellulose component of wood, the elementary link of which is presented below:

,

,

then we can assume the participation of cellulose in structural processes during the curing of ES, mainly due to the hydroxyl of the methylol (most reactive) group with the formation of the following polymer and wood structure:

In this case, participation as a hardener of hexamethylenediamine, one of the most accessible and effective structuring agents, is considered.

Thus, the epoxy resin combines high penetration due to low molecular weight, the ability to chemical structuring due to the presence of reactive functional groups in an amount of more than two and has a curing effect in the presence of a hardener - HMDA according to the above mechanism.

Example 1 (control, prototype). Pine timber was dried in batch steam chambers to a moisture content of 8%. Then, they were cut using woodworking equipment into end or longitudinal workpieces, which, with the help of a milling cutter, were shaped into the outer contour. Next, the preforms were impregnated with a 40% solution in nephras of a low molecular weight copolymer of 4-vinylcyclohexene-1 with maleic anhydride (CBM) with a mol. m. 600-1500 for 40 minutes without external pressure. Finally, the billets were dried in drying ovens at atmospheric pressure and a temperature of 110 ° C for 1.5 hours until the volatile part of the impregnating composition was completely removed.

Example 2. Timber from pine was dried in a steam-air chambers of periodic action to a moisture content of 8%. Then they were cut on woodworking equipment and with the help of a cutter they gave a certain shape to blanks with a longitudinal or transverse arrangement of fibers. Next, the workpiece is impregnated with a 25% solution of low molecular weight epoxy resin (ED-20) in mol. m. 600-1500 for 40 min at room temperature without external pressure. The final stage in the manufacture of parquet blanks was drying in ovens at atmospheric pressure and a temperature of 110 ° C for 1.5 hours until the volatile part of the impregnating composition was completely removed.

Example 3. Parquet blanks from pine with a given external contour configuration, made in accordance with the procedure described in example 2, were impregnated with a 30% solution in acetone ED-20 with mol. m. 600-1500 for 40 min at room temperature without external pressure. The drying step completes the process in accordance with the conditions set forth in Example 2.

Example 4. Billets made in accordance with the procedure described in example 2 were impregnated with a 40% solution in acetone ED-20 with a mol. m. 600-1500 for 40 min at room temperature without external pressure. Finished by drying according to the mode described in example 2.

Example 5. Billets made in accordance with the methodology of example 2, impregnated with a 50% solution in acetone ED-20 mol. m. 600-1500 for 40 min at room temperature without external pressure. Finished the production of preforms by drying according to the mode described in example 2.

Example 6. The preforms made according to example 2 were impregnated with a 55% solution in acetone ED-20 with a mol. m. 600-1500 for 40 min at room temperature without external pressure. Finished the production of preforms by drying as in example 2.

The test results of parquet blanks made according to the above examples are shown in the table.

As follows from the data presented in the table, the blanks manufactured by the proposed method significantly exceed the control samples in terms of water resistance (and therefore shape stability), and also have strength advantages. At the same time, there is a significant advantage over the prototype in such important indicators as water absorption and swelling.

The noted advantages of the proposed method are observed when using a solution of epoxy resin brand ED-20 in acetone with a concentration of 30-50% and a hardener content of hexamethylenediamine 10% by weight of the resin (corresponds to examples 3-5 in the table below).

Table Indicators Examples 1 counter (prototype) 2 3 four 5 6 one 2 3 four 5 6 7 Density, kg / m 680 660 720 750 735 670 The ultimate tensile strength along the fibers, MPa 77.4 75.7 86.5 97.4 84.3 77.1 The ultimate tensile strength along the fibers, MPa 12,2 11.3 15.8 18.3 14.5 12.0 Hardness, N / mm 79.3 75 93 98 87 77 Abrasion,% 5,0 7.0 4.3 3,1 3,7 6.2 Water absorption,% in 24 hours 11.7 13.3 10.5 8.7 11.1 12,4 Swelling after 24 hours,% 1,5 2.1 1,2 1,1 1.4 2.2

Claims (1)

A method of manufacturing end pieces for parquet from softwood and soft-leaved wood, including drying wood, obtaining blanks, shaping their outer contour and impregnating with a low molecular weight polymer in a solution, characterized in that the timber, which is the waste of thinning or target wood, is cut with woodworking equipment on end or longitudinal workpieces, which are used to shape the outer contour with a cutter, the workpieces are subsequently fed into an impregnation bath with a solution of 30-50% the concentration in acetone of a low molecular weight polymer in the form of an epoxy resin ED-20 with a molecular weight of 600-1500 and containing 10 parts by weight of hardener hexamethylenediamine HMDA per 100 parts by weight resin, after impregnation for 0.5-1.5 hours, the preforms are dried in a heating cabinet at a temperature of 100-120 ° C for 1-3 hours until the volatile components are completely removed.