RU2561445C1 - Composition for production of wood chipboards - Google Patents

Abstract

FIELD: woodworking industry.

SUBSTANCE: composition comprises substances in the following ratio of components, wt %: urea-formaldehyde resin - 9.200-11.220, hardener - 0.092-0.112, the agent for forming a regular ordered structure of the cured resin - 0.449-0.920, and wood chips - the rest. For formation of regular structures of resin the native starch and/or physically modified extrusion starch-containing raw material, and/or flour, and/or dextrins, and/or alburnum and/or a mixture of alburnum with cellular potato juice is used. The native starch is selected from corn, potato, wheat, barley, rye, sorghum, tapioca, rice or pea starches. The modified raw material is a potato or corn starches. The flour is chosen from rye, wheat, corn or potato flour. The following dextrins are used: amylodextrin, erythrodextrin, achrodextrin and maltodextrin. The alburnum is a potato or corn alburnum. The viscosity of the paste is 0.55-0.65 Pa • s (14-20 s at VS4).

EFFECT: increase in the indices of strength of boards and reduction of free formaldehyde in boards.

Description

The invention relates to the woodworking industry and can be used to produce low-toxic wood materials, for example, in the production of chipboards.

The invention allows the manufacture of inexpensive, durable and environmentally friendly chipboards.

A known composition for the manufacture of chipboards, including wood chips, urea-formaldehyde resin, hardener, styrene butadiene latex, emulsifier brand OM-10, trisodium phosphate and aerosil [US Pat. RU No. 2074090, class B27N 3/04, claimed 24.11.92, No. 92008046/04, publ. 02.27.97 in Bull. No. 6].

The disadvantages of this composition are the use of expensive components - organic substances, low strength and water resistance of the plates, as well as technological difficulties associated with the complex composition (a large number of components).

Closest to the invention is a composition for the manufacture of chipboards [US Pat. RU No. 2176186, class B27N 3/02, claimed 04.08.2000 for No.2000121010 / 04, publ. November 27, 2001 to the Bul. No. 33] is a prototype comprising wood chips, urea-formaldehyde resin, a hardener and a means for forming a regular ordered structure of the cured resin. Styrene butadiene methacrylate latex (BSMK) together with Aerosil was used as a means to increase the adhesion of the resin to the surface of wood chips.

The disadvantage of this composition is the use of expensive organic substances, the low strength of the plates and the high content of free formaldehyde.

Thus, the problem to which this invention is directed is to reduce the cost of particle boards, increase the strength of the plates, and also reduce the free formaldehyde in the plates.

This is achieved in that the composition for the manufacture of chipboards, including wood chips, urea-formaldehyde resin, a hardener and a means for forming a regular ordered structure of the cured resin, characterized in that native (corn, and / or potato, and / or wheat, and / or barley, and / or rye, and / or sorghum, and / or tapioca, and / or rice, and / or pea) starch, and / or physically modif induced extruded starch-containing raw materials (potato and / or corn starch, and / or flour (rye, or wheat, or corn, or potato)), and / or dextrin (amylodextrin, and / or erythrodextrin, and / or achrodextrin, and / or maltodextrin), and / or pulp (potato and / or corn), and / or a mixture of pulp with cellular potato juice with a paste viscosity of 0.55-0.65 Pa · s (14-20 s according to VZ4), while the components of the composition taken in the following ratio, wt. %:

urea-formaldehyde resin 9,200-11,220 hardener 0,092-0,112 means for forming a regular ordered cured resin structures 0.449-0.920 wood shavings rest

A binder was prepared by mixing a urea-formaldehyde resin with a concentration of 60-67% with a 20% aqueous hardener solution (ammonium chloride). Then, a paste of modified product from starch-containing raw materials was introduced in the required amount.

Wood chipboards with a thickness of 16 mm are prepared as follows. Wood chips with a moisture content of 2.4% were mixed with a binder. After that, the chip carpet was molded and it was hot pressed at a temperature of 180 ° C for 0.5 min / mm of plate thickness at a specific pressure of 2.2 MPa.

As starch-containing raw materials use:

- corn starch according to GOST 7697;

- potato starch according to GOST 7699;

- wheat starch according to the technical regulatory legal act (TNLA);

- barley starch according to TNLA;

- rye starch according to TNLA;

- Sorghum starch according to TNLA;

- tapioca starch according to TNLA;

- rice starch according to TNLA;

- pea starch according to TNLA or others;

- starch mixtures of different ratios according to TNLA;

- starch suspension with a mass fraction of dry matter of 32-41% according to TNLA;

- rye flour in accordance with GOST 7045;

- wheat flour according to STB 1666;

- corn flour in accordance with GOST 14176;

- potato flour according to TNLA or others;

- dextrin (amylodextrin, and / or erythrodextrin, and / or achrodextrin, and / or maltodextrin) according to TNLA;

- potato pulp according to TNLA;

- corn pulp according to TNLA;

- cell potato juice according to TNLA.

Physical (extrusion) modification of starch-containing raw materials is carried out in the following ways.

Starch-containing raw materials are subjected to extrusion (thermomechanical action), pre-loading it into a loading funnel of a twin-screw extruder of the RZ-KED-88 brand or any other, at a working temperature of 140-200 ° C and the diameter of the matrix used (die) - 1-5 mm.

Then they carry out the cutting of extrusion products emerging from the extruder matrix in the form of bundles, and their reception in the collection, then using pneumatic conveying is sent to a funnel.

The obtained extrusion products are crushed on a hammer mill type KHCH-5 or similar, sieved through a borate with 0.65 mm sieve holes. Coarse fractions are supplied for re-grinding.

Before adding to the composition from the modified starch-containing raw materials, a paste is prepared with a viscosity of 0.55-0.65 Pa · s (14-20 s according to VZ4).

Physical modification of starch can also be carried out as a result of contact drying using a roller dryer. The process of obtaining physically modified starches includes the following operations: preparation of raw materials with moisturizing it, and sometimes with processing with chemical reagents; gelatinization of starch; the formation of a thin film of paste; paste drying; grinding the resulting films and sieving the powdered product. The paste is dried in a thin layer using special equipment - roller dryers. Modified starches are prepared by preliminary gelatinization of a 35-45% aqueous suspension of starch and subsequent drying of the paste in a thin layer on steam drum roller dryers at a temperature of 120-180 ° C.

A feature of physical modified starch products obtained by extrusion or by contact drying on a roller dryer is their ability to dissolve in water at room temperature, because these starch products are gelatinized (they have destroyed starch granules). To prepare a paste, a physically modified product is added to water at room temperature (20-25 ° C) and everything is thoroughly mixed.

Native starch is a natural polymer in which monomers (α-D-glucopyranose residues) are linked by α- (1 → 4) - and α- (1 → 6) -glucoside bonds, forming amylose (linear polysaccharide) and amylopectin (branched polysaccharide buildings). Starch fractions (amylose and amylopectin) are compactly packed in starch grains (or granules).

There are various methods of processing starch-containing raw materials into starch using a variety of technological schemes equipped with various types of technological equipment used for these purposes. However, regardless of the hardware design, each of these methods includes production stages that are characteristic of most modern starch production technologies: preparation of starch-containing raw materials for processing, grinding, starch separation, starch cleaning, dehydration and drying, removal of metallomagnetic impurities, packaging, packaging, labeling and transporting starch to a warehouse or consumer. At the same time, a multi-stage hydrocyclone unit is used for cleaning and dehydration in modern technologies for producing native starch, in which the operations of separating finely ground starch-containing raw materials into a starch suspension and a pulp mixture with other by-products are carried out, as well as partially thickening the starch suspension. By-products that are removed (removed) from production in potato-starch production are potato pulp and cell potato juice, and in corn-starch production are corn pulp, gluten and germ.

In preparing a means for forming a regular, ordered structure of the cured resin, native starch is used to prepare a starch paste. For this, native starch is poured into an enameled or aluminum container, then a little cold water is poured into it, and everything is well mixed until a thick sour cream consistency. Boiling water is poured into the resulting mass in a thin stream, while the mass is continuously stirred so that no lumps form in it. Boiling water is poured about 1:10 in relation to starch. After the starch has been brewed and became gelatinous and transparent, a little more boiling water is added to it to obtain a starch paste with a viscosity of 0.55-0.65 Pa · s (14-20 s according to ВЗ4).

In accordance with the properties, the following types of dextrins are distinguished:

- amylodextrin - stained with iodine solution in violet-blue color, is a white powder, soluble in 25% alcohol solution, precipitated with 40% alcohol solution, specific rotation [α] ²⁰ _D ranges from + 190 ° to + 196 °, the restoration ability is in the range of 0.6-2.0%;

- erythrodextrin — stains with red-brown iodine, dissolves in a 55% alcohol solution, precipitates with a 65% alcohol solution, it crystallizes from warm alcohol solutions as spherical crystals, specific rotation [α] ²⁰ _D + 194 °, reduction ability is 1- 3%;

- achroodextrin - not stained with iodine, soluble in a 70% alcohol solution, forms spherocrystals upon evaporation of hot alcohol solutions, specific rotation [α] ²⁰ _D + 192 °, reduction ability 10%;

- maltodextrin - does not react with iodine and is not precipitated by alcohol, specific rotation [α] ²⁰ _D +181 to + 183 °, reduction ability is 36-43%.

To obtain dextrin, dry starch is acidified with volatile acid (hydrochloric or nitric) in special technological equipment (dextrinizer) of continuous or periodic action. The acidified starch is kept in bins for 12-16 hours. After aging, the starch is pre-dried to 3% moisture and subjected to dextrinization. In this case, the starch is heated and maintained for a certain time at a temperature of 125-180 ° C, which ensures the required degree of starch degradation. Subsequently, dextrin is cooled, moistened and sieved.

Maltodextrins are obtained by partial enzymatic hydrolysis of starch using amylolytic enzyme preparations and subsequent spray drying of the resulting product.

If you use a preparation for the formation of a regular ordered structure of cured resin from dextrin, you need to add room temperature water (20-25 ° C) to the dextrin sample and mix thoroughly. The ratio of dextrin and water should be such that the final viscosity of the paste is 0.55-0.65 Pa · s (14-20 s according to VZ4).

Mash and cell potato juice are by-products of starch production. So, the dry matter composition of potato pulp is as follows,%: starch - 45-50; fiber - 25-30; soluble carbohydrates - up to 3; nitrogenous substances - 3-5; mineral substances - 5-6; other substances - up to 20, and the composition of solids of cell potato juice is as follows,%: starch - 8.3; soluble carbohydrates - 20-25; nitrogenous substances - 35-40; mineral substances - 14-15; fats - 2.8; other substances - up to 20.

You can prepare a tool for the formation of a regular ordered structure of the cured resin from a mixture of pulp with cellular potato juice. The mixture is obtained as a result of thorough mechanical mixing of the two components (pulp and cell potato juice), while the viscosity of the mixture should be 0.55-0.65 Pa · s (14-20 s according to VZ4). For better mixing, the mixture can be heated to a temperature of 70-90 ° C.

Means for the formation of a regular ordered structure of the cured resin can be prepared using our selection matrix of the component composition.

Testing of the plates for physical and mechanical properties and the content of free formaldehyde was carried out in accordance with GOST 10633, 10634, 10635, 10636 and 27678.

The physicomechanical properties of particle boards obtained with the use of modified products from starch-containing raw materials comply with the current technical regulatory legal acts. According to the content of free formaldehyde (i.e. toxicity), the resulting plates correspond to the emission class E1 in accordance with GOST 10632.

The invention is illustrated by the following examples.

Example 1

The composition contains:

urea-formaldehyde resin 9,200 hardener 0,092 means for forming a regular ordered cured resin structures - extrusion potato starch with a paste viscosity of 0.61 Pa · s 0.449 wood shavings rest

Example 2

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste physically modified corn contact starch drying on a roller dryer forming paste with a viscosity of 0.62 Pa · s 0.920 wood shavings rest

Example 3

The composition contains:

urea-formaldehyde resin 10,210 hardener 0.102 means for forming a regular ordered cured resin structures - paste a mixture of peeled rye flour with a paste viscosity of 0.63 Pa · s 0.685 wood shavings rest

Example 4

The composition contains:

urea-formaldehyde resin 9,200 hardener 0,092 means for forming a regular ordered cured resin structures - paste potato and corn extrusion mixtures 1: 1 starch with viscosity paste 0.64 Pa · s 0.449 wood shavings rest

Example 5

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste potato and corn extrusion mixtures 2: 1 starch with viscosity paste 0.64 Pa · s 0.920 wood shavings rest

Example 6

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste potato and corn extrusion mixtures starch in a ratio of 1: 2 with viscosity paste 0.64 Pa · s 0.920 wood shavings rest

Example 7

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste mixtures of dextrins (amylodextrin, erythrodextrin, achrodextrin, maltodextrin in a ratio of 1: 1: 1: 1) and native potato 1: 1 starch with viscosity paste 0.65 Pa · s 0.920 wood shavings rest

Example 8

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered hardened resin structures - paste paste pulp with cell potato juice in 1: 1 ratio with a viscosity of 0.55 Pa · s 0,900 wood shavings rest

Example 9

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste mixtures of potato pulp with corn pulp in 2: 1 ratio with a viscosity of 0.60 Pa · s 0.850 wood shavings rest

Example 10

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - pulp paste potato with a viscosity of 0.65 Pa · s 0,500 wood shavings rest

Example 11

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures forming paste with a viscosity of 0.62 Pa · s 0.920 wood shavings rest

In preparing the agent for the formation of a regular ordered structure of the cured resin, a paste 14 component mixture is used, consisting of native corn starch, extruded potato and corn starch, extrusion rye, wheat, corn and potato flour, amylodextrin, erythrodextrin, achrodextrin and maltodextrin, and corn pulp, cell potato juice in a ratio of 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1: 1. The viscosity of the paste mixture was adjusted with water to 0.55-0.65 Pa · s (14-20 s according to VZ4).

Example 12

The composition contains:

urea-formaldehyde resin 9,200 hardener 0,092 means for forming a regular ordered cured resin structures - paste mixtures of native potato and corn 1: 1 starch with viscosity paste 0.64 Pa · s 0.449 wood shavings rest

Example 13

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste mixtures of native potato and corn 2: 1 starch with viscosity paste 0.64 Pa · s 0.920 wood shavings rest

Example 14

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste native potato starch with a viscosity of 0.60 Pa · s 0.850 wood shavings rest

Example 15

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste amylodextrin with a paste viscosity of 0.65 Pa · s 0.920 wood shavings rest

Example 16

The composition contains:

urea-formaldehyde resin 11,220 hardener 0,112 means for forming a regular ordered cured resin structures - paste mixtures of dextrins (amylodextrin, erythrodextrin, achrodextrin, maltodextrin in a ratio of 1: 1: 1: 1) with a paste viscosity of 0.65 Pa · s 0.920 wood shavings rest

The invention allows to reduce the cost of particle boards, increase the strength indicators of the plates, and also reduce the amount of free formaldehyde in the plates, which is a toxic substance.

Claims (1)

Composition for the manufacture of chipboards, including wood chips, urea-formaldehyde resin, a hardener and a means for forming a regular ordered structure of the cured resin, characterized in that native corn and / or potato, and / or wheat and / or barley and / or rye and / or sorghum and / or tapioca and / or rice and / or pea starch and / or physically modified extrusion e starch-containing raw materials - potato and / or corn starch, and / or rye flour, or wheat, or corn, or potato, and / or dextrin - amylodextrin, and / or erythrodextrin, and / or achrodextrin, and / or maltodextrin, and / or potato pulp and / or corn, and / or a mixture of pulp with cell potato juice with a paste viscosity of 0.55-0.65 Pa · s (14-20 s according to B3), while the components of the composition are taken in the following ratio, wt. %:
urea-formaldehyde resin 9,200-11,220 hardener 0,092-0,112 means for forming a regular ordered cured resin structures 0.449-0.920 wood shavings rest