A production method for producing particleboard using formaldehyde-free adhesive

[ Application Number] CN201510465451.7 [Application Date] 2015-08-03

[Publication Number] CN106393383A [Publication Date] 2017-02-15

[Applicant] Wanhua Eco-friendly Board Industry Co., Ltd. [Address] No. 5, Xinghuo Street, Science and Technology Park, Changping District, Beijing 102200, China

[Inventors] Gao Youqing; Liu Zhigang

[Country/Province Code] 11

[Abstract] This invention provides a method for producing particleboard using formaldehyde-free adhesive, mainly including: particle preparation, adhesive application, laying, pre-pressing, and post-treatment steps. Specifically, it uses MDI as the main adhesive and sodium lignosulfonate, polyvinyl alcohol, soybean glue, or starch glue as auxiliary adhesives. Compared with existing technologies, this invention has the following advantages: 1. It solves the problem of using aluminum pads or mesh belts for blank conveying when producing single-layer and multi-layer particleboard using formaldehyde-free adhesive. 2. It solves the problem of blank conveying failure when producing particleboard using formaldehyde-free adhesive in continuous flat-press production lines. 3. It eliminates the need for blank conveying equipment, reducing the lateral density and thickness deviation of the product, and improving product quality and stability. 4. It reduces the blank thickness before hot pressing, shortens the product closing time, and improves production efficiency. 5. It reduces the thickness of the sanding layer, increases the sanding line speed, and reduces product production costs.

[Claim 1] A method for producing particleboard using formaldehyde-free adhesive, comprising the steps of particle preparation, adhesive application, laying, pre-pressing, hot pressing, and post-treatment, characterized in that: Particle preparation: After wood is shaving, it is prepared into particle form using equipment such as a shaving machine and a ring sander, and the particles are divided into surface particles and core particles according to their shape and size. Particle drying: According to the production process requirements, the moisture content of the surface particles is controlled within 3-10% (preferably 5-7%, more preferably 6%); the moisture content of the core particles is controlled within 2-9% (preferably 4-6%, more preferably 4.5%). Adhesive application: The main adhesive MDI is applied first to meet the bonding strength requirements of the board. The amount of the main adhesive applied to the surface layer is 3.5-6.5% (preferably 5-6%, more preferably 5.5%) of the weight of the surface wood chips, and the amount of the main adhesive applied to the core layer is 3.0-5.5% (preferably 3.8-4.8%, more preferably 4.4%) of the weight of the wood chips. An auxiliary adhesive (specifically, biomass adhesives such as polyvinyl alcohol, sodium lignosulfonate, soybean glue, and starch glue) is then applied to enhance the wet strength of the board blank to meet the requirements of board conveying during board production. The application ratio of the auxiliary adhesive is 5-20% (preferably 12-17%, more preferably 15%), and the concentration is 2-40%. Laying: The laying step involves laying the glued surface and core layer wood chips. The surface layer wood chips are used on both surfaces of the board blank using a graded laying machine, requiring each surface layer to account for 50% of the weight of the surface wood chips. The core layer wood chips are used on the core layer of the board blank using a mechanical laying machine. Pre-compression: After laying, the slabs undergo pre-compression, with a compression rate generally controlled at 30%–80% (preferably 55%–65%, more preferably 60%) and a springback rate of 5%–30% (preferably 8%–15%, more preferably 10%). Hot pressing: The laid slabs are sent to a multi-layer flatbed press or a continuous flatbed press for hot pressing. The hot pressing temperature is 170–240℃ (preferably 185–195℃ for multi-layer flatbed presses and 210–220℃ for continuous flatbed presses), the hot pressing pressure is 3–4 MPa (preferably 3.5–3.9 MPa, more preferably 3.7 MPa), and the hot pressing cycle is 6–20 seconds/mm (preferably 12–17 seconds/mm, more preferably 14 seconds/mm). Post-processing steps: The product undergoes cooling, edge trimming, homogenization, and sanding to complete the surface appearance quality treatment.