KR100222907B1 - Composite board and method of manufacture - Google Patents

Abstract

The present invention relates to a composite plate produced by recycling waste paper and cardboard and a method for producing the composite plate. This composite plate contains recycled waste paper and thermosetting polyisocyanate resin in the form of particles or fibers.

Description

[Name of invention]

Composite plate and manufacturing method thereof

[Technical Field]

This application is a continuation of US patent application Ser. No. 07 / 765,822, filed Sep. 26, 1991.

The present invention provides a practical and environmentally acceptable method for recycling large quantities of waste paper and cardboard. In particular, the present invention relates to commercially useful composite plates produced by recycling waste paper and paperboard, methods for producing composite plates, and articles of manufacture thereof.

[Background]

The supply of natural wood fibers is limited and has been reduced. Federal timber yields in the northwestern United States, estimated in 1991, are about 20 from those in 1990. To 40 It is estimated to decrease.

In particular, the ever-increasing amount of waste disposal in cities is a serious environmental problem. Lack of landfills and air pollution as a result of incineration require urgent development of alternative treatment methods.

Incidentally, environmentally satisfactory recycling technologies are needed to alleviate the waste disposal problem and to ease the demand for natural wood products.

Particle plates, medium density fiberboards, hard fiberboards, and other composites based on wood are widely used. Techniques for producing such composites based on wood are also developing. However, practical and environmentally acceptable methods for producing useful composites made entirely from waste paper or paperboard have not been developed before the present invention.

U.S. Patent No. 4,111,730 describes several advantages of waste paper recycling. To prepare cardboard products, waste paper is cut into thin pieces, adjusted to a low moisture content, mixed with thermosetting elements or phenol-formaldehyde resins, compressed into mat and cured. This composite product is 10-12 Moisture Content of 0.3044-1.2014g / Density, and 0.635 to 3.81 It may have a thickness of. Containing phenol-formaldehyde resins makes environmentally undesirable cardboard products.

100 Deppe's "The Utilization of Wastepaper and Refuse Fiber Material for Particle Board and MDF" Proceedings of the Nineteenth Washington State University International Particle Board / Composite Materials Symposium. 1985).

U. S. Patent No. 3,718, 536 describes a particle plate composed of pieces of paper coated with a thermoplastic resin. Thermoplastic binders, such as polyethylene or polychlorophyllene, are added to thermoplastic coated paper operations to facilitate composite plate production.

Various composite plates have been formulated with wood particles or fibers with isocyanate binders. See Polyurethanes Forest Products Technical Paper 9919 (published by ICI Polyurethane Forest Products Group, West Groveford, West Groveford, 08066, NJ). U. S. Patent No. 4,311, 554 describes a nonflammable particle plate comprising a mixture of binders which may be wood particles, minerals and isocyanate adhesives.

Summary of the Invention

The present invention provides an effective, environmentally acceptable, formaldehyde-free method of transforming waste paper or cardboard into useful composite board products. From about 0.04806 to about 0.09611 g / according to the invention Particles having a bulk density of about 0.01602 g / About 5 weights to provide a fiber having a bulk density of Water content of about 0.01602 to about 0.6407 g / Waste paper having a bulk density of is purified.

The purified particles or fibers are mixed with a water soluble emulsification of a thermoset isocyanate resin, for example polymeric diphenylmethane polyisocyanate such as Rubinate MF-178, available from Imperial Chemical Industries (ICI). Wax emulsions may be included in the resin emulsion to improve the water resistance of the final product. The mixture is 100 Preferably about 8 weights of solids To about 12 weight Water and about 2 weight To about 4 weight Contains resin of 100 0.5 weight in solids To about 2 weight It may also contain a wax. The bulk density is slightly higher than the bulk density of the refined particles or fiber material before mixing.

The product comprising the mixed resin is molded into a mat. The mat formed from the resin mixed with the paper particles is advanced in a cowl or cowless system. It is preferable to advance the mat formed from the refined waste paper or cardboard fiber on a cowley system.

About 280 after trimming if necessary or desirable To about 320 The mat is compressed under pressure not to exceed 1000 psi for about 1 to 20 minutes at a temperature of. The composite plate product of the extrusion step is cooled, adjusted and preferably trimmed.

The final paper grain or fiberboard product after standardization is about 0.8009-1.2014 g / Density, internal bond and fiber strength of at least 80 psi, elastic modulus of at least 300,000 psi, and fracture coefficient of at least 3000 psi. After 24 hours immersion test, the composite product weighs 25 Water absorption of less than 15 Has a thickness swelling degree of less than.

The composite plate can have any desired thickness. Typical composite plate thickness is about 0.3175 To about 2.54 to be. Multiple thin plates can be combined to provide a stronger and thicker end product. Formaldehyde-free composite plate products of the present invention are National Particleboard Associations for products comparable to ANSI-208.1 (Particle Plate) and ANSI-208.2 (Middle Density Fiberboard (MDF)) Building Code requirements. Meet or exceed the qualifications for an association. The composite also fulfills the description of the outer shell of a flat door.

Detailed description of the invention

The method of the present invention involves some or all of the following sequential steps. (i) preparation of raw materials for refining (e.g. newsprint, waste paper, corrugated or non-corrugated cardboard, kraft paper), (ii) purification, (iii) mixing the purified product with a thermosetting isocyanate resin, (iv) mat molding (v) mat compression, and (vi) cooling where appropriate, and (vii) final preparation. Preferably, quality control is performed throughout the process.

[Preparation for Purification]

Prior to purification, impurities such as scrub and metal materials are removed from the waste paper stock to protect the device and preserve the quality of the product.

[refine]

In the manufacture of paper particle boards, only a single step or one machine may be required to cut the raw material in order to obtain a suitable particle size. The bulk density of the purified particle product is preferably about 0.04005 to 0.09611 g / to be. Hammer cutters or machines of equal function can also be used.

Preferably, two purification steps are used to make the fibers from the paper stock. In a first step, a 뼘 size material is prepared, preferably about 0.04806 g / Has a bulk density of. The provision of a machine by Shrsd-Tech or SSI Shrdding System produces a satisfactory first stage product. The product of the second purification step is preferably about 0.01281-0.02563 g / It has a bulk density of. The second purification can be performed with a machine provided by Andritz or Sprout Bauer.

[mix]

Purified particles or fiber products are mixed with a suitable thermosetting isocyanate resin. Preferably, the resin is used in the form of a water-soluble emulsion in order to increase the amount of resin and to promote the dispersion of the resin on the surface of paper particles or fibers. Preference is given to polymeric methylene diisocyanate (PMDI) and diphenylmethane diisocyanate (MDI) resins capable of aqueous emulsification. Such resins are commercially available from ICI polyurethanes, such as rubinates 178 and 184. Rubinate 178 is suitable for use in aqueous emulsification. Rubinate 184 is used directly.

The advantages of these isocyanates when comparing urea formaldehyde and phenol-formaldehyde in the production of wood particleboard are described in the ICI Polyurethanes Forest Products Technical Papers. These advantages include faster production rates, lower pressure temperatures, elimination of formaldehyde emissions, smaller amounts and longer shelf life of the binder.

Mixing is preferably controlled by a feedback system that determines the amount of added resin as a function of the dry basis moisture content and the weight of the purified product. Resin The aqueous resin emulsion is preferably dispersed by atomization of air, airless or spinning disc heads. The wax emulsion will preferably be added at the same time as the number. The wax functions as a moisture inhibitor and thus controls linear expansion. Waxes useful for the purposes of the present invention can be obtained from ICI, Bordon or Hercules.

The product in the mixing step is preferably about 8 weights To about 12 weight Moisture content of 100 About 2 weight in solids To about 4 weight Resin content, and 100 About 0.5 to 2 weight in solids Has a wax content of.

[Mat Molding]

The papermaking particles or fiber resin mixture are molded into a pressed mat. Preferably a meter is used to ensure that the even mat is uniformly placed at the bottom.

After the mat forming process, any of the three methods can be used to produce the final composite plate product. The mat may be molded on the cowl that is held in the pressing step. Optionally, the mat can be molded on the cowl and prepressurized at ambient temperature providing sufficient mat preservation to perform removal from the cowl and transport to the press. In a preferred practice, a cowlis system is used to form a continuous mat on a belt moving from the mat forming machine to the press through a preliminary process to provide mat preservation.

In producing a composite plate from purified newspaper fibres, a cowley type is preferable. The vacuum mat molding machine precipitates the purified fibers onto the forming screen. The mat is then passed through a Shave-off head and then a precompressor. The shave-off head may be provided with a mat weight sensor and a moisture meter, and there may be a weight scale for adjusting the mat weight. After passing through the precompressor, the mat edges are cut and subsequent mats can be separated into individual bats by a cutter saw. Too heavy or too light mats can be reintroduced and recycled.

[Mat Compression]

The mat formed into a mixture of papermaking particles or fibers with a resin and wax is pressed to provide the composite sheet product of the present invention. Specific compression cycles, techniques, temperatures and pressures will be a function of the particular laminate product to be manufactured.

It is preferably coated with a platen or cowl with a release agent.

100 in the preferred practice of the present invention for most composite plate products About 2 weight in solids To about 4 weight A mat containing a resin of about 280 at a maximum pressure of about 1000 psi for about 1 to 20 minutes. To about 320 Compress appropriately at temperature. Mat is about 0.3175 to about 2.54 Thickness, 7 weight To about 12 weight A composite plate product having a water content of at least about 90 psi, internal particles or fibers and resin bonds, and a coefficient of fracture of at least 300 psi is provided. 25 weight of composite board after immersion test for 24 hours Water absorption of less than 15 It has a thickness swelling degree of less than and an elastic modulus of 300,000 psi.

[Cooling and Final Manufacturing]

Compressed composite plates can be stored to adapt to ambient temperature and moisture. Final production includes trimming, sizing and finishing of the surface application.

These composite products can be plywooded and available individually. Among other products, the composite and laminates are useful as substrates for furniture, door refining, molds for cement, exterior panels for foam-filled panels, and building substrates.

Example 1

This example is about 0.317 from newspaper paper fibers. The practice of the present invention for producing a dry fibrous plate of dry thickness is shown.

About 2.54 And about 0.08009-0.1602 g / containing particles of larger size. In order to provide a product with a bulk density of, newspaper paper was put into the first step of purification in a disc cutting mill. The second step of purifying these particles, usually in a hemer-crusher, is about 0.01602 g / The product with a bulk density of was calculated. After storage, 50 wt.% Of the product of the second purification step It was mixed with an aqueous emulsion containing polymeric diphenylmethane diisocyanate (ICI rubinate MF-178) and an aqueous emulsion of wax used specifically by air spraying. Mixed material is about 10 weight Moisture content of and 100 3.0 weight in solids Has a resin content of.

The mixed product was molded into a mat on a vacuum screen. Transfer the forming mat to the cowl, approx. 300 at a maximum input of 900 psi It was pressed for 1 minute 40 seconds at a temperature of and cooled. The final composite sheet product weighs about 7 Of water content, about 0.3175 Thickness, about 1.0893 g / Has a density of at least 200 psi, internal resin fiber bonding, a rupture coefficient of at least 6000 psi, and an elastic modulus of at least 700,000 psi. 25 hours of water absorption after immersion test Thickness swelling was less than 15 wt. Was less. These physical properties indicate that the composite plate product conforms to the specifications for the outer plate of plain text.

Example 2

This embodiment is described in Example 1 0.3175 The practice of the present invention for making plywood from composite product is described.

Completed 0.3175 Adapt the composite panel to the ambient relative humidity. Cold set plywood binder is added to the upper and lower rollers.

Only the top side of the selected panel will have the binder applied. For example, if a four-layer plywood was made, only three of the four panels would have a binder, and the fourth panel without the binder would be placed on top of the other three. This process is repeated until the holding rack is filled. The panel is then transferred to a low pressure compressor (up to 100 psi) and held under pressure for 20 minutes.

Claims (15)

In the composite plate consisting essentially of refined papermaking paper fibers and thermosetting polyisocyanate resin, the composite plate is 0.635 to 2.54 Thickness of 0.8009-1.2014g / Density, at least 190 psi of internal particles or fiber-to-resin, at least 3000 psi failure coefficient, at least 300,000 psi modulus, and 24 hours of immersion test 25 Water absorption of less than 15 A composite plate, having a thickness swelling degree of less than. The composite plate according to claim 1, wherein the composite plate essentially comprises purified papermaking particles and a thermosetting polyisocyanate resin. The composite plate according to claim 1, wherein the composite plate essentially comprises purified papermaking fibers and a thermosetting polyisocyanate resin. 4. The composite plate according to claim 3, wherein the refined papermaking fiber is reduced by refining its fibrillar omission. The composite plate according to claim 3, wherein the refined papermaking fiber is purified newspaper paper fiber. In the composite plate comprising essentially a fiber and a thermosetting polyisocyanate resin prepared by refining newspaper, the composite plate is 0.635 to 2.54 Thickness of 0.8009-1.2014 g / Density, at least 190 psi of internal particles or fiber-to-resin, at least 3000 psi of fracture modulus, and 24 hours after immersion test 25 Water absorption of less than 15 A composite plate, having a thickness swelling degree of less than. The composite plate according to claim 6, wherein the resin is diphenylmethane diisocyanate resin. The composite plate according to claim 6 or 7, wherein the fibers are in the form of fibrils for producing newspaper paper. 5 weight To 10 weight In the method for producing a composite plate from waste paper having a moisture content of (i) 0.01602 to 0.08009 g / The waste paper was purified to produce particles or fiber products having a bulk density of: (ii) 8 weights To 12 weight Moisture content of 100 2 weight in solids To 4 weight Mixing the particle or fiber product with an aqueous emulsion of a thermosetting polyisocyanate resin to produce a mixed product having a resin content of: (iii) forming the mixed product into a mat and (iv) producing a composite plate. 280 to reach maximum pressure less than 1000 psi for 20 minutes To 320 Comprising the step of compacting the mat at a temperature of the manufacturing method of the composite plate. The method of claim 9, wherein the purified papermaking product of step (i) is about 0.01602 g / Method for producing a composite plate, characterized in that the fiber product obtained by purifying newspaper paper to produce a purified product having a bulk density of. The method of claim 10, wherein the fibers in the fiber product are in the form of fibrils for producing newspaper paper. The method according to claim 9, wherein the aqueous emulsion of the synthetic resin of step (ii) comprises a wax, and the mixed product is 100 0.5 in solids To 2 Method for producing a composite plate, comprising the wax of. 10. The method of claim 9, wherein the mat formed in step (iii) is vacuum formed on a forming screen and passed through a preliminary compressor. The method of claim 9, wherein the purified papermaking product of step (i) has an average of 0.635 to 2.54 Method for producing a composite plate, characterized in that the particle product having a particle size of. 10. The method of claim 9, wherein the composite plate prepared by step (iv) comprises at least 190 psi of internal particles or fiber-to-resin bonds, a fracture modulus of at least 3000 psi, after a 24-hour immersion test. Water absorption of less than 15 A method for producing a composite plate, characterized by having a thickness swelling degree of less than.