BRPI0720687A2 - PRODUCTION PROCESS OF A WOOD BASED PRODUCT - Google Patents

Description

Report of the Invention Patent for "WOOD-BASED PRODUCT PRODUCTION PROCESS".

The present invention relates to a process for producing a wood based product.

5 Introduction

Formaldehyde based resins such as phenol formaldehyde resin, melamine formaldehyde resin and urea formaldehyde resin are widely used as binders in the production of wood based products. Examples of such wood-based products are composite products comprising bonded layers such as plywood, laminate flooring products and veneer products used for example in furniture. Other examples are board products, such as particle, chip and fiber boards in which chips and / or wood fibers, together with a binder, are pressed to form a board.

By curing a formaldehyde-based resin, formaldehyde can be released during both wood-based product manufacturing and later during product use. The emission of formaldehyde into ambient air has been a major concern for many years for health reasons.

There is a growing demand for free formaldehyde adhesives that provide sufficient adhesion intensity and overall end product quality to make them suitable as alternatives to prior art adhesives that contain formaldehyde resin.

Water resistance and adhesion intensity are generally

Important properties that reflect quality for wood-based products. There are usually specific quality parameters required to meet an established standard for a specific end product. For example, a chipboard needs to meet certain standards in terms of, for example, internal adhesion, thickness swelling and water absorption, while a laminate flooring product needs to meet certain standards, for example in terms of delamination and fiber disruption.

As an alternative to adhesive compositions comprising polymer dispersion-based formaldehyde resin adhesives, for example, polyvinyl acetate is available. However, when obtaining compressed molding products by bonding veneer layers and pressing the structure into a certain shape, it is important to minimize the so-called rebound of the bonded structure when it is released from the mold. Polyvinyl acetate-based adhesives generally provide poor rebound results.

It is also important that a compression molded product

substantially maintain its shape during use, ie when under load. This property can be measured by a so-called "fatigue test" used, for example, in furniture products, where a compression molded product is subjected to a large number of load cycles.

As an alternative to formaldehyde based resins in wood adhesive compositions, starch adhesives have been proposed. Imam et al., "Wood Adhesive from Crosslinked Poly (vinyl alcohol) and Partially Gelatinized Starch: Preparation and Properties," Starch / Stárke 51 20 (1999) No. 6, S. 225-229, discloses an adhesive composition comprising starch and alcohol. polyvinyl, the composition also comprising a melamine resin. US 2,051,025, US 2,102,937, US 3,487,033, US 3,355,307 disclose starch-based adhesives used for the manufacture of corrugated cardboard. WO 03/069061 A1 discloses a starch-based adhesive used in the manufacture of a cardboard.

There is still a need for alternative methods of bonding wood-based materials that use starch adhesive-based adhesive.

Accordingly, the present invention provides a process for bonding wood-based materials using a starch-based adhesive composition that provides excellent bonding quality. The Invention

The present invention provides a process for producing a wood based product comprising applying a water based adhesive composition comprising non-gelatinized starch, composition 5 also comprising from about 0.1 to about 50% by weight of one or more polymers (P) containing an amino group or an amide group, on one or more pieces of a wood-based material and joining one or more pieces with one or more pieces of a material, preferably material to wood base.

Ungelatinized starch in this case means a starch

which is in an aqueous phase which has been subjected only to temperatures below 50 ° C, suitably lower than approximately 45 ° C, preferably below approximately 40 ° C and therefore not gelatinized. .

The weight ratio of starch to polymers (P) in the composition

The adhesive composition used in the process is suitably approximately 1: 2 to approximately 25: 1, preferably approximately 1: 1 to approximately 15: 1, more preferably approximately 3: 1 to approximately 8: 1.

The adhesive composition used in the process suitably

comprises from about 10 to about 50 wt.% starch, preferably about 15 to about 45 wt.%, more preferably about 20 to about 40 wt.%, more preferably about 25 to about.

35% by weight.

The adhesive composition used in the process suitably comprises from about 1 to about 40 wt% of one or more polymers (P), preferably about 1.5 to about 25 wt%, more preferably about 2

up to approximately 15% by weight.

The solids content of the adhesive composition used in the method is suitably from about 20 to about 70 wt%, preferably from about 35 to about 60 wt%, more preferably from about 40 to about 50 wt%. .

By "solids content" of the adhesive composition used in the process herein is meant the non-aqueous portion of the adhesive composition.

Examples of suitable starches in the adhesive composition used in the process are native starches and modified starches obtained, for example, from potato, corn, wheat, rice, peas etc., such as: acetylated degraded starch, starch modified starch. alkyl succinic acid, oxidized starch, hydroxypropylated starch, cationic starch, amylopectin starch, high amylose acetylated starch, tapioca starch, native potato starch, native cornstarch, native starch, starch of native rice and pea starch.

One or more polymers (P) in the adhesive composition used in the process suitably comprise monomer units containing an amine or amide group. Suitably, about 5 to about 100% of the monomer units in one or more polymers (P) contain an amino group or an amide group, preferably about 25 to about 100%, more preferably about 50 to about 50%. about 100%, even more preferably about 90 to about 100%. Most preferably, all monomer units in one or more polymers (P) contain an amino group or an amide group.

One or more polymers (P) suitably contain a primary amino group or an amide group. One or more polymers (P) preferably comprise one or more of polyvinyl amine, polyvinyl alcohol-co-vinyl amine, polyvinyl alcohol-co-vinylformamide, polyallylamine, polyethylene imine, polyamidoamine and polyvinyl formamide. More preferably, one or more polymers (P) comprise one or more of polyvinyl amine and poly (vinyl alcohol-co-vinylamine). Most preferably, the polymer (P) is polyvinyl amine.

In one embodiment, one or more polymers (P) suitably belong to the vinyl polymer group. In such a case, one or more (P) polymers preferably comprise one or more of polyvinyl amine, polyvinyl alcohol-co-vinyl amine, polyvinyl alcohol-co-vinylformamide, polyallylamine and polyvinyl. formamide. More preferably, one or more vinyl (P) polymers contain a primary amino group. More preferably, the vinyl polymer (P) is polyvinyl amine.

In one embodiment, one or more polymers (P) suitably contain pendant primary amino groups or amide groups. One or more polymers (P) preferably comprise one or more of polyvinyl amine, polyvinyl alcohol-co-vinyl amine, polyvinyl alcohol-co-vinylformamide, polyallylamine, polyethylene imine and polyvinyl formamide. More preferably, still the polymer (P) is polyvinyl amine or polyethylene imine.

Polyvinyl amine is usually obtained by hydrolysis of polyvinyl formamide to a certain degree. By "polyvinyl amine" in this case is meant a polyvinyl amine wherein the molar ratio of amine groups to formamide groups is from 5:95 to 100: 0. If the molar ratio of amino groups to formamide groups is less than 5:95, the polymer is defined as a polyvinyl formamide. The molar ratio of amino groups to groups formed on the polyvinyl amine is preferably from about 10:90 to about 20: 0, more preferably from about 50:50 to about 100: 0, more preferably about from 80:20 to about 100: 0.

Polyvinyl alcohol-co-vinyl amine is usually obtained by copolymerization of vinyl acetate and vinyl formamide followed by hydrolysis which provides a copolymer having vinyl alcohol and vinyl amine units. They may also be remaining formamide groups in the copolymer and also remaining acetate groups. The molar ratio of amine groups to formamide groups in the polyvinyl alcohol-co-vinyl amine is from 5:95 to 100: 0. If the ratio of number of amine groups to formamide groups is less than 5:95, the polymer is defined as a poly (vinyl alcohol-co-vinylformamide). The molar ratio of hydroxyl groups to acetate groups in poly (vinyl alcohol-co-vinyl amine) or poly (vinyl alcohol-co-vinyl amide) is suitably approximately 25:75 to 100: 0, preferably approximately. 75:25 to 100: 0. The molar ratio of amine and formamide groups to hydroxyl and acetate groups in poly (vinyl alcohol-co-vinyl formamide) or poly (vinyl alcohol-co-vinyl formamide) is suitably approximately 3: 97 to approximately 100: 0. preferably about 10:90 to about 100: 0, more preferably still about 25:75 to about 100: 0.

One or more polymers (P) suitably have a weight average molecular weight of from about 1,000 to about 10,000,000 g / mol, preferably about 10,000 to about 800,000 g / mol, more preferably about 20,000 to about 10,000. approximately 600,000 g / mol, more preferably still approximately 50,000 to about 500,000 g / mol.

The viscosity (Brookfield, 12 rpm, spindle 4, 20 ° C) of the adhesive composition is suitably less than 100,000 mPa * s, preferably approximately 1,000 to about 50,000 mPa * s, more preferably approximately 5,000 to about approximately 20,000 mPa * s.

The adhesive composition used in the process may also be combined with a crosslinker shortly before use. Suitable crosslinkers are those which are reactive to amino and / or hydroxyl groups. Examples of crosslinkers are: isocyanates, monomers or polymers containing adipic acid, melamine formaldehyde resin, urea formaldehyde resin, melamine salts, aldehydes such as glutaraldehyde, glyoxal and polymeric aldehydes such as dialdehyde starches and forming agents. of complexes such as zirconium salts. These may be added to either of the two components of the adhesive composition. If used, the amount of the crosslinker in a component of the adhesive composition is suitably up to about 30 wt% or about 0.1 to about 30 wt%.

The adhesive composition used in the process suitably also comprises one or more polymers (P1) containing acetoacetoxy groups. The content of acetoacetoxy groups in one or more polymers (P) is suitably from about 0.05 to about 15 mol%, preferably about 1 to about 10 mol%. One or more polymers (P1) preferably comprise acetylated acetylated polyvinyl alcohol (AAPVA).

One or more polymers (P1) suitably have a weight average molecular weight of from about 1,000 to about 5,000,000 g / mol, preferably about 10,000 to about 2000,000 g / mol.

One or more components of the adhesive composition used in the

A process comprising starch, polymer (P) and polymer (P1) respectively may also comprise additives such as viscosity adjusting agents and fillers such as kaolin, wheat flour, soy flour, nutshell flour or others known to be suitable for use in wood adhesive formulations.

The adhesive composition used in the process may also comprise inorganic or organic salts which may have originated from a solution of one or more polymers (P) or (P1) used when obtaining the starch adhesive composition adhesive. A portion of one or 20 more polymers (P) and / or (P1) may be ionically charged, preferably cationically charged. The amount of negative indicator ions of salts in the adhesive composition may be from 0 to about 10 wt% or from about 0.1 to about 5 wt% or from about 0.2 to about 1 wt%.

The adhesive composition used in the process can also be

a polymer or a copolymer (P2) of one or more ethylenically unsaturated monomers other than one or more polymers (P). The polymer or copolymer (P2) suitably does not contain any acetoacetoxy groups. The content of polymer or copolymer (P2) in the adhesive composition is suitably from about 1 to about 50 wt.%, Preferably from about 3 to about 40 wt.%, More preferably from about 5 to about. 30% by weight.

A dispersion of the polymer or copolymer (P2) may, in addition to being mixed with starch and one or more polymers (P), forming the adhesive composition, may also be used as a separate component in combination with the adhesive composition, forming a combining the adhesive composition according to the invention and dispersing the polymer or copolymer (P2) of one or more unsaturated monomers. This combination is then used in the process of the invention. In this combination, the amount of adhesive composition is suitably from about 25 to about 99 wt.%, Preferably from about 40 to about 90 wt.%, More preferably from about 50 to about 85 wt.%. in the total weight of the combination. The amount of polymer or copolymer dispersion (P2) is suitably from about 1 to about 75% by weight, preferably from about 10 to about 60% by weight, more preferably from about 20 to about 50% by weight. , based on the total weight of the combination. The content of polymer or copolymer (P2) in its dispersion is suitably from about 10 to about 90 wt%, preferably from about 25 to about 75 wt%.

Examples of suitable polymers or copolymers of one or more ethylenically unsaturated monomers are vinyl ester homopolymers such as polyvinyl acetate, vinyl ester copolymers such as ethylene vinyl acetate (EVA) copolymer or one or more vinyl acetate copolymers. more acrylic monomers such as methyl methacrylate or butyl acrylate, styrene butadiene rubber (SBR) and polyacrylates.

Generally, the inclusion of polymers or copolymers of one or more ethylenically unsaturated monomers, of the types listed above, in the starch-based adhesive used in method 30 or in combination with the starch-based adhesive can improve sizing characteristics such as fiber cracking of a plated or laminated product. In one embodiment, the process suitably comprises applying the adhesive composition to a piece of wood-based material by contacting the surface with the adhesive composition applied to a surface of another piece of wood-based material by joining together. 5 thus the pieces by forming an adhesive joint between the pieces.

In one embodiment of the process the adhesive composition is dried after application and later activated by the addition of an aqueous composition.

In one embodiment, when manufacturing laminated products, the process suitably comprises applying the adhesive composition to a surface such that the straining joint will comprise an originally applied amount of from about 0.1 to about 500 g / m2. The amount applied depends on the product to be produced: for compression molded veneers this is preferably from about 50 to about 200 g / m2, for laminate flooring material is preferably from about 100 to about 160 g / m2 and for rolled bars is preferably from about 180 to about 500 g / m2. The appropriate upper limit also depends on that type of wood-based material that is applied with the solution. The adhesive composition may be applied on one or both surfaces to be associated. If applied to both surfaces, the sum of the amounts applied to each surface will correspond to the preferred amounts for the entire specified bonding joint.

When making compression molded veneers, the method suitably comprises joining more than two pieces of wood-based materials, preferably from 2 to 15.

By wood-based material, in addition to solid wood, wood materials such as fiber, chip and chipboard materials are also included. The surfaces to be joined may be of the same or different type of wood-based material.

The wood based material may be any type and form of wood based material such as chips, fibers, sheets, blades, plates, pieces etc.

In one embodiment, the process comprises gluing pieces of wood-based materials wherein the pieces of wood-based material are wood chips, where the term "wood chips" includes, in this case. , chips, debris, flakes, sawdust particles and any finely divided wood-like material. In this case, the wood-based product is a composite product such as a chip, particle or fiber board or an oriented filament board.

The moisture content of the wood chips to be used is suitably from about 0 to about 20% by weight, preferably from about 1 to about 10% by weight, more preferably from about 1.5 to about 5% by weight. .

The weight ratio of wood chips to adhesive composition used in the process, calculated as dry weight, is suitably from about 100: 1 to about 1: 1, preferably from about 50: 1 to about 2: 1, more. preferably from about 30: 1 to about 2.5: 1, more preferably from about 15: 1 to about 3: 1.

The moisture content of the wood chip mixture and the

The adhesive position used in the process at the beginning of pressing is suitably from about 3 to about 25% by weight, preferably from about 5 to about 20% by weight, more preferably from about 6 to about 18% by weight. even more preferably from about 7 to about 15% by weight.

The application of the adhesive composition is preferably followed by pressing. The pressing suitably takes place at an elevated temperature. The pressing temperature depends on which wood product is to be manufactured, but may suitably be from about 0 to about 250 ° C and preferably from about 70 to about 200 ° C. For laminated or plated products, the pressing temperature, when no crosslinker has been added to the adhesive composition, is suitably from about 0 ° C to about 200 ° C, preferably from about 20 to about 150 ° C, up to 5 ° C. more preferably from about 50 to about 130 ° C, more preferably from about 70 to about 130 ° C. When a crosslinker has been added to the adhesive composition, the pressing temperature may sometimes be decreased depending on the efficiency of the crosslinker.

For chipboard, chipboard products

and fiber, the pressing temperature is preferably from about 100 to about 225 ° C, more preferably from about 150 to about 200 ° C. For laminate products such as plywood, laminate flooring or laminate flooring products, the pressing temperature is preferably from about 70 to about 175 ° C, more preferably from about 90 to about 160 °. Ç.

The pressing time and pressing temperature are linked so that lower pressing temperatures generally require longer pressing times. The wood-based product to be produced also determines suitable pressing temperatures and pressing times. The pressing time is suitably at least about 10 seconds, also suitably from about 10 seconds to about 60 minutes, preferably at least about 30 seconds, also preferably from about 30 seconds to about 30 minutes. more preferably still at least about 1 minute, also preferably from about 1 to about 15 minutes.

In one embodiment, the pieces of wood-based material are sheets or thin plates. In this case, the wood-based product is suitably a laminate flooring material, a plated flooring material, a furniture plated material, a wall panel, a ceiling panel, plywood or a laminated bar.

The wood-based product of the invention is suitably a laminated or plated material, such as a laminate floor or a plated material, such as laminate flooring, plated flooring, a furniture material, plywood, a wall panel, a panel for ceiling, a laminate bar or composite product such as a chipboard, a fiber board, a chip board or an oriented filament board. Preferably, it is plywood, a plated furniture material, a plated floor, a laminate floor or a chipboard 10.

The invention is also illustrated by the following non-limiting examples. Parts and percentages refer to parts by weight, respectively percent by weight, unless otherwise stated.

Examples

Example 1:

A starch-based adhesive was obtained by mixing 65.5 g of an approximately 7.5% by weight aqueous solution of polyvinyl amine (BASF Lupamin® 9095), 5.7 g of water and 32.4 g of cornstarch 20 (C * Gum NC 03432 of Cerestar, 10% moisture content) at room temperature (25 ° C). The ratio of amine group to formed group in polyvinyl amine was greater than 90:10. The weight average molecular weight of the polyvinyl amine was 340,000 g / mol. The viscosity of the composition was measured at 12,000 mPa * s at 20 ° C (Brookfield, 12 rpm, axis 4).

Example 2:

A starch-based adhesive was obtained by mixing 75 parts by weight of the adhesive composition according to Example 1 with 25 parts by weight of an acrylate / PvAc dispersion having a 50% by weight polymer content.

Example 3:

Plated products were fabricated by gluing a 0.6 mm beech top plate on one side of the 15x15 cm particle boards. The plates were applied with 3.7 g of adhesive compositions according to Examples 1 and 2 and the plates were pressed directly onto the plates for 1 minute at 90 and 130 ° C respectively. Fiber break (with slitter) was tested.

Table 1. (1 minute pressing time)

Fiber Break Temperature (%) Example 1 Example 2 Cold Warm Warm Cold 90 ° C 0 0 0-5 10 130 ° C 90-100 100 90 100 The tests were repeated, however, using a

pressing 10 minutes at 90 ° C and 5 minutes at 130 ° C respectively. The results are presented in table 2.

Table 2. (10 minutes pressing time)

Temperature Fiber Break Time (%) Example 1 Example 2 Cold Warm Warm Cold 90 ° C 10 minutes 10 10 80-90 100 130 ° C 5 minutes 90-100 100 90-100 100 Example 4:

Two products were each obtained from 13 glued beech plated using an adhesive composition according to Examples 1 and 2 respectively in combination with compression molding at 120 ° C for 8 minutes. The rebound was determined for both products. The rebound was too small for both products.

Example 5:

A chipboard was made by mixing 864 g of wood chips having a moisture content of 1.7% by weight with 216 g of an adhesive composition obtained by mixing at room temperature 131 g of an approximately 7.5% by weight aqueous solution of polyvinyl amine (BASF Lupamin® 9095), 75 g of cornstarch (Cerestar C * Gum NC 03432, 10% moisture content) and 10 g of water. Mixing was done at room temperature (22 ° C) for 5 minutes. The chip mixture was molded into a 30 x 30 cm sheet and pressed at 189 ° C for three minutes on a 16 mm thick plate. The pressure sequence was 150 kg / cm2 for 30 seconds, 40 kg / cm2 for 2 minutes and 2 kg / cm2 for the last 30 seconds. Tensile strength (internal adhesion, IB) was measured by gluing 5 x 5 cm pieces over two metal blocks and breaking them. Thickness swelling (TSW) and water absorption (ABS) were also measured. The thickness swelling was measured by determining the degree of swelling after a 5 x 5 cm piece had been immersed in water (20 ° C, 24 hours). Water absorption was measured by determining weight gain after a 5 x 5 cm piece had been immersed in water (20 ° C, 24 hours).

The IB value was 690 kPa, TSW 53% and ABS (24 hours) 121%.

Claims (13)

1. Process for producing a wood-based product comprising applying an adhesive composition containing ungelled starch in an aqueous phase, the composition also comprises from about 0.1 to about 50% by weight of one or more more polymers (P) containing an amino group or an amide group, on one or more pieces of a wood-based material and joining one or more parts with one or more other parts of a material. The process according to claim 1, wherein the amount of starch in the adhesive composition is approximately 15 to about 40 wt%. A process according to any one of claims 1-2, wherein the amount of one or more polymers (P) in the adhesive composition is from about 2 to about 25% by weight. A process according to any one of claims 1-3, wherein one or more polymers (P) belong to the group of polyvinyl amine, polyvinyl alcohol-co-vinyl amine, polyallylamine, polyethylene imine and polyvinyl formamide. A process according to any one of claims 1-4, wherein the polymer (P) is polyvinyl amine. A process according to any one of claims 1-5, wherein the adhesive composition also comprises one or more polymers (P1) containing acetoacetoxy groups. A process according to any one of claims 1-6, wherein the adhesive composition also comprises a polymer or copolymer (P2) of one or more ethylenically unsaturated monomers, different from one or more polymers (P). A process according to claim 7, wherein the polymer (P2) is a vinyl ester homopolymer or a vinyl ester copolymer. A process according to any one of claims 7-8, wherein the polymer (P2) is a vinyl acetate copolymer with one or more acrylic monomers. A method according to any one of claims 1-9, which comprises gluing pieces of wood-based materials wherein the pieces of wood-based material are sheets or thin plates. A process according to any one of claims 1-9, comprising gluing pieces of wood-based materials wherein the pieces of wood-based material are wood chips. A process according to any one of claims 1-10, wherein the wood-based product is a laminate flooring material, a plated flooring material, a furniture plated material, a wall panel, a ceiling panel. , plywood or a laminated bar. A process according to any one of claims 1-9 or 11, wherein the wood based product is a chip, particle or fiber board or an oriented filament board.