Aqueous bonding composition

Abstract

Disclosed is an aqueous bonding composition comprising: (A) a saccharide; (B) a phosphate; and (C) at least one neutralizing agent selected from ammonia and an amine compound having at least one hydroxyl group. The aqueous bonding composition is excellent in balance among bending strength, bending strength under wet condition, water-absorption thickness expansion coefficient and peeling strength and scarcely causes metal to rust. The aqueous bonding composition can be usefully used to produce a wood-based material.

Claims

1. A wood-based material coated with an aqueous bonding composition consisting of: (A) 20-95 parts by weight of a non-reducing disaccharide or a non-reducing trisaccharide; wherein the non-reducing disaccharide is selected from the group consisting of sucrose, lactose, maltose, trehalose, turanose, and cellobiose; and the non-reducing trisaccharide selected from the group consisting of raffinose, melezitose, and maltotriose; (B) 1-50 parts by weight of a phosphate, and (C) 0.5-50 parts by weight of at least one neutralizing agent selected from ammonia, 2-amino-2-methylpropanol, diethanolamine and/or N,N-dimethylaminoethanol, and one or more of a preservative, a mildew-proofing agent, a rust preventative, an organic thickener, and an inorganic thickener selected from clay and silica; based on 100 parts by weight of the total amount of the components (A) to (C), wherein the water-absorption thickness expansion coefficient (%) of the aqueous bonding composition is 12 or less, measured in accordance with JISA5908:2003.

2. The wood-based material of claim 1, wherein the aqueous bonding composition has a pH in a range of 7 to 9.

3. The wood-based material of claim 1, wherein the non-reducing disaccharide or trisaccharide is selected from the group consisting of sucrose, trehalose, and maltotriose.

4. The wood-based material of claim 1, wherein the aqueous bonding composition consists of (A) 60-85 parts by weight of the non-reducing disaccharide or trisaccharide; (B) 5-25 parts by weight of the phosphate; and (C) 2-25 parts by weight of the at least one neutralizing agent, and one or more of a preservative, a mildew-proofing agent, a rust preventative, an organic thickener, and an inorganic thickener selected from clay and silica.

Description

EXAMPLES

(1) The present invention will be described below by way of Examples and Comparative Examples. It should be noted, however, these Examples are intended to describe the present invention and the present invention is not limited thereto.

(2) First, the following components were prepared as components of an aqueous bonding composition. Trade name and manufacturer's name are shown in parentheses. Parts are by weight.

(3) <(A) Saccharide>

(4) (A-1) Sucrose (Wako Pure Chemical Industries, Ltd.)

(5) <(B) Inorganic Acid Ammonium Salt>

(6) (B-1) Ammonium Dihydrogen Phosphate (Wako Pure Chemical Industries, Ltd.)

(7) <(C) Neutralizing Agent>

(8) (C-1) Ammonia (25% Ammonia Water, Wako Pure Chemical Industries, Ltd.)

(9) (C-2) 2-Amino-2-Methylpropanol (Wako Pure Chemical Industries, Ltd.)

(10) (C-3) Diethanolamine (Wako Pure Chemical Industries, Ltd.)

(11) (C-4) Triethanolamine (Wako Pure Chemical Industries, Ltd.)

(12) (C′-5) Sodium Hydroxide (Wako Pure Chemical Industries, Ltd.)

(13) An aqueous bonding composition of Example 1 was produced in the following manner.

Example 1: Production of Aqueous Bonding Composition

(14) 78.0 Parts of (A-1) sucrose (Wako Pure Chemical Industries, Ltd.) and 19.5 parts of (B-1) ammonium dihydrogen phosphate (Wako Pure Chemical Industries, Ltd.) were dissolved in 92.5 parts of distilled water. To this aqueous solution, 2.5 parts of (C-1) ammonia (containing 2.5 parts of ammonia and 7.5 parts of water because of using 10.0 parts of 25% ammonia water, Wako Pure Chemical Industries, Ltd.) was added. After stirring at normal temperature, an aqueous bonding composition of Example 1 was obtained. The composition of the aqueous bonding composition of Example 1 is shown in Table 1.

(15) <Measurement of pH>

(16) The pH of the aqueous composition of Example 1 was measured at 23° C. using a pH meter (Model HM-25R (trade name) manufactured by DKK-TOA CORPORATION). As a result, the pH was 7.0. The results are shown in Table 1.

(17) <Rust Test>

(18) The aqueous bonding composition (40 g) of Example 1 was charged in a 100 mL glass container with a lid. A commercially available iron nail having a length of 70 mm degreased with isopropanol was put in the aqueous adhesive composition. After being left to stand at 23° C. for 7 days, generation of rust was observed.

(19) A: Rust was not generated for 7 days.

(20) B: Rust was generated within 3 to 7 days.

(21) C: Rust was generated within 1 to 3 days.

(22) D: Rust was generated within 1 day.

Examples 2 to 6 and Comparative Examples 7 to 10: Production of Aqueous Bonding Compositions

(23) The composition of each of aqueous bonding compositions of Examples 2 to 6 and Comparative Examples 7 to 10 is shown in Tables 1 to 2.

(24) In the same manner as in Example 1, except that the components (A), (B), and (C) used in Example 1 were changed to components shown in Tables 1 to 2 and amounts thereof, the aqueous bonding compositions of Examples 2 to 6 and Comparative Examples 7 to 10 were produced.

(25) In the same manner as in Example 1, the pH was measured and also the rust test was performed. The results are shown in Tables 1 to 2.

(26) TABLE-US-00001 TABLE 1 (Examples) Composition 1 2 3 4 5 6 (A) (A-1) 78.0 77.4 75.5 68.6 66.6 60.9 (B) (B-1) 19.5 19.3 18.9 17.2 16.7 15.2 (C) (C-1) 2.5 3.3 5.6 (C-2) 13.9 (C-3) 16.7 (C-4) 23.8 (C′-5) Water 100 100 100 100 100 100 pH 7.0 9.0 9.9 8.3 8.4 8.1 Rust test B A A A A A

(27) TABLE-US-00002 TABLE 2 (Comparative Example) Composition 7 8 9 10 (A) (A-1) 74.3 100 80.0 (B) (B-1) 18.6 100 20.0 (C) (C-1) (C-2) (C-3) (C-4) (C′-5) 7.1 Water 100 100 500 100 pH 8.5 6.8 3.3 3.3 Rust test A B D D

(28) Using the above-mentioned aqueous bonding compositions of Examples 1 to 6 and Comparative Examples 7 to 10, wood-based materials (particle boards) of Examples 11 to 16 and Comparative Examples 17 to 20 were produced.

Example 11: Production of Wood-Based Material

(29) Wood-based fibers of coniferous tree, which passed through a 60 mesh sieve, were used as a wood-based element (raw material). The aqueous adhesive composition of Example 1 was uniformly applied onto 76 parts of the wood-based element using a spray so that the solid content became 24 parts. The coated wood-based element was dried in an oven at 80° C. for 2 hours. After press molding at a heating platen temperature of 170° C. under a pressure of 4 MPa for 9 minutes, a wood-based material (particle board) having a thickness of 9 mm and a density of 0.8 g/cm.sup.3 of Example 11 was produced. The raw materials and manufacturing conditions of the wood-based material of Example 11 are shown in Table 3.

Examples 12 to 16 and Comparative Examples 17 to 20: Production of Wood-Based Materials

(30) Raw materials used to produce particle boards of Examples 12 to 16 and Comparative Examples 17 to 20, amounts thereof, and press molding conditions are shown in Tables 3 to 4.

(31) In the same manner as in Example 11, except that the aqueous adhesive composition used in Example 11, the amount thereof, the amount of the wood-based element, and the press molding conditions (heating platen temperature, pressure, and molding time) were changed to the values shown in Tables 3 to 4, wood-based materials (particle boards) of Examples 12 to 16 and Comparative Examples 17 to 20 were produced. Other conditions such as size and density of each particle board are the same as those of the particle board of Example 11.

(32) Regarding the particle board thus obtained, each water-absorption thickness expansion coefficient (%) was measured in accordance with JISA5908:2003.

(33) The “water-absorption thickness expansion coefficient (%)” is preferably 12 or less.

(34) The above-mentioned particle board corresponds to a “non-polished board” of a “base particle board” disclosed in JISA5908:2003.

(35) TABLE-US-00003 TABLE 3 (Example) Wood-based material 11 12 13 14 15 16 Composition Wood-based Parts by 76 76 76 76 76 76 element weight Bonding (Example) 1 2 3 4 5 6 composition Parts by 24 24 24 24 24 24 weight Molding Temperature ° C. 170 170 170 170 170 170 conditions Time Minutes 9 9 9 9 9 9 Pressure MPa 4 4 4 4 4 4 Performances Water-absorption thickness 12.0 11.3 11.2 11.9 10.5 14.8 expansion coefficient (%)

(36) TABLE-US-00004 TABLE 4 (Comparative Example) Wood-based material 17 18 19 20 Composition Wood-based Parts by 76 72 94 80 element weight Bonding (Comparative 7 8 9 10 composition Example) Parts by 24 28 6 20 weight Molding Temperature ° C. 170 170 170 170 conditions Time Minutes 9 9 9 9 Pressure MPa 4 4 4 4 Performances Water-absorption thickness Collapse Collapse Collapse 20.4 expansion coefficient (%) *Collapse: The wood-based material was broken so that it became difficult to maintain the whole form during the evaluation.

(37) As shown in Tables 3 and 4, each of the wood-based materials of Examples 11 to 16, produced using the aqueous bonding compositions of Examples 1 to 6, has a small water-absorption thickness expansion coefficient. Furthermore, each of the aqueous bonding compositions of Example 1 to 6 can prevent the nail from rusting. Therefore, the bonding compositions according to the present invention can be suitably used (or applied) to a wood-based element so as to produce a wood-based material.

(38) As shown in Table 4, the wood-based materials of Comparative Examples 17 to 20 produced by using the aqueous bonding compositions of Comparative Examples 7 to 10 are inferior in water-absorption thickness expansion coefficient. Furthermore, the aqueous bonding compositions of Comparative Examples 9 and 10 cannot prevent the nail from rusting because of the low pH.

(39) These results revealed that the aqueous bonding composition comprising the above-mentioned three components (A) to (C) is useful for bonding a wood-based element (raw material) and an excellent wood-based material can be molded by molding a wood-based element using the same.

(40) The present invention can provide an aqueous bonding composition which is useful for bonding a wood-based element. A wood-based material can be suitably produced by molding a wood-based element using the aqueous bonding composition according to the present invention.