SK304791A3 - Method of lamination of pressed pieces of composite mixtures of wood flour and pvc - Google Patents

Abstract

The invention concerns a method of lamination, in which extruded boards of thickness from 2,5 to 10 mm, profiles both hollow and full, from composite mixtures of 20 to 60 weight parts of a wood flour, of 80 to 40 weight parts of polyvinylchloride with a polymerization degree of from 600 to 1000, of 3 to 20 weight parts of current processing polyvinylchloride additives, are continually laminated by on-rolling of comercionally available polyvinylchloride foils. A field of an adventagenous application of such foils lays in an arranging technique of exhibition grounds, fairs, in a scene decoration, in a housing, furniture, shipbuilding and automobile industry.

Description

BACKGROUND OF THE INVENTION Field of the Invention: Process for lamination of extruded fumes from wood flour-polyvinyl chloride

The invention relates to a process for the continuous lamination of wood flour-PVC composite boards extruded by extruders. Laminates produced by this process and exhibit improved appearance and strength parameters, reduced flammability and minimal water retention.

BACKGROUND OF THE INVENTION

Several industrial processes are known for the production of laminated board products using the waste processing of the paper, textile or wood-processing industry. new material, mostly flat shape · ¥ the next stage of the production process, the boards are laminated by hot pressing with a thin decorative and / or insulating layer, mostly paper-impregnated again with thermosetting resins · So produced laminates used mainly in furniture and housing industry are characterized by rich variability however, they are flammable, water-absorbent, wholly solid and therefore unsuitable for use in humid environments and outdoors. ¥ in many cases they release formaldehyde, which has recently led to restrictions on their use in the furniture and housing industry ·

Thin-film plastics with or without an adhesive layer are also used for laminating wood veneers or boards. · For technological processes of this type, the laminating film is bonded to the wood substrate by hot pressing (eg German Patent 3,516,645 or Japanese Patents 58 185 247 and 59 51 910). Boards and veneers modified according to these laaining procedures over non-laminated panels have increased water resistance and improved aesthetic appearance. However, due to the high content of natural wood, they are flammable, especially when the laminating film is not of PVC but of polyolefin.

Thermoplastics such as polypropylene, polyethylene and PVC have also proven themselves in the preparation of composite processing mixtures containing pulp waste materials of various origins and grain, processable by pressing, rolling, spraying and extrusion into products representing natural wood. The water resistance of these materials is also higher than that of natural wood.

Among these thermoplastic pulp dust composites, PVC-wood flour composites are particularly promising in terms of suppressed flammability. The mechanical and processing properties of the PVC-wood meal composite mixtures are widely variable not only because of the variability of the ratio of the above-mentioned basic components, but also for the rich choice of quality and quantity of processing additives to be added to the processing mixtures.

The patent literature describes a large amount of a mixture with a wide variety of claimed benefits of processing and use. Japanese Patent 57,190,039 discloses that for a mixture of 19 parts by weight of wood meal or rice husks in 100 masses. parts of PVC found improved machinability of products than PVC products without fillers, while maintaining good processability of the mixtures. Further specification is given in Japanese patent 59 53 546, according to which, after previous granulation, a mixture of 100 masses is processed by extrusion. PVC parts of polymerization stage 800 with 60 parts by weight of wood dust and with an organotin stabilizer system in the presence of epoxidized soybean oil and stearic acid on a 3 mm thick wood-faced plate with a smooth surface. Another Japanese patent no. 84,152,387 discloses a composite blend of PVCiABS:

Wood flour in a 20:20:60 ratio, roll workable with good toughness, flexural modulus = 8.6 GPa and Vicat softening point 113 ° C.

Another focus is the processing mixture according to Japanese Patent Nos. 61 233 061 and no. 61,236,858; consisting of 100 masses. PVC parts, 20 masses. parts of dioctyl phthalate, 3 wt. parts of a water-absorbing gel, 5.5 wt. 20 parts by weight of stabilizing additives. parts of wood dust. This injectable compound 3 gives products useful for decorating automotive and home interiors with reduced gloss, soft touch and woody appearance.

Japanese company KANEGAFUCHI through Japanese patents no. 62 64 837, 62 64 838, 62 64 839, 62 64 840 protects rolling and stamping mixtures with high impact resistance, wood appearance and feel. The essence of these mixtures is a combination of PVC, wood flour and wood flour inoculated with vinyl chloride or methyl methacrylate, when used? Ca-Zn, and Ba-Zn stabilizers and other stabilizing additives. The benefit of these inventions is that the cellulose chains grafted with vinyl chloride or methyl methacrylate improve the compatibility of wood powder and PVC.

A further degree of technical improvement of composite material products is achieved by laminating them. German patent no.

No. 239,629 discloses a process wherein a 2.9 mm thick board consisting of isotactic polypropylene with 38% by weight wood flour is laminated by pressing a 0.9 mm thick softened PVC film with 39% DOP 1 content. wherein the adhesive layer used is a sprayed polyurethane rubber. The laminate resulting from this procedure is not delaminated even at 90 ° C and is recommended for automotive interiors.

Laminate of isotactic polypropylene filled with wood flour in a ratio of 62 masses. discloses parts of the German patent No. According 3,136,297th this patent, the film is applied to the PVC layer of adhesive 400 microns (PVC - tetrahydrofuran - DGP) and sprinkled with P using wood _meals with granularity <400 _{d (mu} m in an amount of 129 g / m · The treated film is then bonded to the backing layer of filled polypropylene by pressing at 200 ° C.

However, despite the thin coating of PVC, wood flour polypropylene composites remain highly flammable and laborious to manufacture. In addition, processing of isotactic polypropylene requires temperatures above 200 ° C, but at these temperatures, wood dust already decomposes considerably, resulting in a black-brown coloration of the composite product produced.

- 4 Podjrtalg ^ invention

A method of laminating wood flour-PVC composite extrudates consisting of 40 to 80 masses. parts of suspension and / or emulsion polyvinyl chloride having a polymerization degree of 800 to 1000, 20 to 60 parts by weight of wood flour prepared with urea-formaldehyde or phenol-formaldehyde resin and from 3 to 20 parts by weight. The parts of the processing additives are carried out in such a way that the extrudate emerging from the extruder die at a temperature of 165 to 185 ° C is continuously laminated by rolling a 0.2 to 0.8 mm thick film of a composition of 90 to 97 masses. parts of suspension polyvinyl chloride having a polymerization degree of 600 to 1000, 0.01 to 10 wt. parts of a plasticizer of polyvinyl chloride, 1 to 4 wt. parts of tin and / or calcium zinc or lead PVC stabilizer, 0.5 to 1.0 wt. parts of PVC internal grease, 0.02 to 5 wt. parts of pigments and fillers on a connected three-cylinder apparatus having a temperature of 100 to 120 ° C with a cylinder diameter of more than 400 mm.

The extrudates wood flour composites - laminated PVC according to the invention over traditional particleboard exhibit variability of appearance properties, low flammability, minimum water absorption, increased flexural modulus and tensile dobrou.rázovou _n and flexural strength

Wood flour-PVC composite compositions of the above-mentioned composition for the production of laminable extrudates are prepared in two-stage high-speed mixers (eg of the HENSCHEL, PAPENMEIES, TRUSIOMA, etc.) equipped with venting of the volatile fractions ensuring autogenous heat development in high-speed. the low-speed mixer cooling stage. Such a mixing device will provide a homogeneous, free-flowing, agglomerate of the composite mixture (wood flour - PVC - grease

- stabilizers - fillers - pigments), characterized by a reduced content of moisture, formaldehyde and other volatile substances and a low susceptibility to the separation of wood particles from PVC grains during in-house transport.

For the extrusion of laminated wood-PVC composites suitable for lamination, twin-screw extruders with conical as well as worms intended for processing hard PVC blends, preferably equipped with a decompression vacuum zone to extract residual volatiles (moisture and formaldhes) present in the composite may be advantageously used. processing can withstand

The extrusion temperature mode is selected according to the composition of the processing mixture, the type of extruder and extruder in the range of 145 to 185 ° C. The optimum linear melt flow rate at the exit of the screening tool is influenced by the articulation of the profile and the plasticization efficiency of the extruder used, typically in the range of 0.7 to 1.2 m / min.

The actual lamination process according to our invention immediately follows the process of extrusion of the composite mixture, utilizing the heat of the melt exiting the screening tool (die) of the extruder. In contrast to conventional laminating processes used by pressing pre-prepared plates in large-scale presses, the process introduced by us brings great energy savings and reduces manufacturing effort.

For the lamination of composite board products, a three-cylinder device with a cylinder diameter of more than 400 mm is used, whose temperature, peripheral speed and interfacial distance are precisely adjustable. The lamination process consists in that together with the hot melt of the composite mixture, laminating foils 0.2 to 0.5 mm thick are fed into the triple roll from the top and bottom of the incoming composite melt wood flour - PVC, and the pressure and temperature agglomeration unit connects all three layers in one reinforced composite laminate. Commercially available polyvinyl chloride films of hard, softened and modified (e.g. DUKOFOL) stabilized with tin, lead, or even calcium-zinc stabilizers selected according to the intended use of the produced laminate are useful for lamination. The temperature of the laminating rolls is adjusted so as to achieve sufficient adhesion of the film to the surface of the composite plate, but the film must not adhere to the surface of the laminating rolls due to high temperatures.

Closure of the air bubbles between the laminating film and the composite plate is prevented by appropriately adjusting the inlet angle between the plane of the film and the plane of the composite melt drawn into the rolling device, the formation of transversal and longitudinal wrinkles can be prevented by the braking mechanism stretching the laminating film. exceeding £ 3 from the original width.

- 6 The laminate produced according to this procedure at the correct setting of temperatures, peripheral speeds and raedzios distances of the rollers is characterized by dimensional tolerances of thickness below + 0.05 mm and a great balance of mechanical properties over the entire surface of the laminate produced ·

The laminate emerging from the three-cylinder is evenly drawn off, air-cooled and automatically sawn to the desired dimensions.

More detailed information on the method of laminating extrudates of wood meal-PVC composite blends is given in the example section of this document

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Preparation of composite mixture:

In the hot part of the two-stage mixer equipped with the exhaust gas exhaust, the individual components of the composite mixture are gradually metered in operation:

24.7 kg wood flour with grain below 800 µm

84.0 kg of suspension PVC with polymerization degree of 880 2.6 kg of 3PbO, PbSO4-based lead stabilizer and lead stearate 0.6 kg pentaerythritol distearate 0.6 kg montan wax 0.8 kg calcium stearate 0.7 kg polyacrylate flow modifier 0.8 kg titanium dioxide 2.2 kg float chalk

3.0 kg dioctyl phthalate

Stirring is continued until the temperature of the mixture has autogenously increased to 155 ° C. Formaldehyde and water vapor release from the wood flour in the hot part of the mixer is sucked out of the working area by the ventilation device. · By reaching the set mixing temperature, the hot mixture enters the cold part of the mixer and cools at low speed.

- 11 <f _f = 41 MPa S _f = 3400 MPa • _n = 5.6 kJ / * ²

The areal thickness distribution had a relative standard deviation of 0.049.

Boards of such properties are advantageously used in the furniture and housing industry for the production of low-flammable parts by frequent contact with water.

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Claims (1)

PATENT CLAIMS FROM Process for laminating wood flour - PVC composite extruded compositions consisting of 40 to 80 parts by weight of a poly (vinyl chloride) suspension and / or emulsion having a polymer from the starting step of 600 to 1000, 20 to 60 parts by weight. parts of wood flour prepared with urea-formaldehyde or phenol-formaldehyde resin and up to 3 to 20 parts by weight of processing additives, characterized in that the extrudate exiting the extruder die at a temperature of 165 to 185 ° C is continuously laminated by rolling 0.2 to 0.8 mm thick film of a composition of 90 to 97 parts by weight · parts of a suspended polyvinyl chloride polymer having a polymerization of 600 to 1000, 0.01 to 10 parts by weight · parts of a plasticizer of polyvinyl chloride, 1 to 4 parts · parts of a tin and / or calcium zinc or lead stabilizer of polyvinyl chloride; 5 to 1.0 parts by weight of an internal lubricant of polyvinyl chloride, 0.02 to 5 parts by weight. parts of pigments and fillers on a connected three-cylinder device with a cylinder temperature of 100 to 120 ° C with a cylinder diameter of more than 400 m.