Method for manufacturing composite board using high oil content wax and the composite board made using high oil content wax

A quality composite board can be manufactured by combining natural fibrous material, resin and a waxy hydrocarbonaceous material wherein the waxy hydrocarbonaceous material is a natural, synthetic or petroleum wax containing from greater than 30 wt % to up to 98 wt % oil content.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to manufactured composite board products
 wherein the composite board product is a compressed, heat treated mixture
 of natural fibrous material, resin and wax.
 2. Related Art
 Manufactured composite board products, typically wafer board, hard board,
 oriented strand board, particle board, medium density fiberboard, etc.,
 have been produced for many years and their method of manufacture is well
 known in the industry.
 Typically such board products are produced by using a natural fibrous
 material as the primary component which is then sprayed, dipped or
 otherwise combined with a minor amount of resin and slack wax, formed into
 sheets and subjected to pressure and heat to yield finished, thin,
 generally stiff sheets of manufactured board materials.
 U.S. Pat. No. 4,404,252 describes a surface stabilized waferboard having at
 least one surface rendered water resistant and stabilized against water
 loss.
 In the process of that patent a wafer board is produced by bonding together
 wood wafers, adhesive resin and wax in a hot press, the water resistance
 and surface stabilization of at least one surface being accomplished by
 bonding a layer of porous paper to at least one surface of the wafer board
 while the wood wafers are being bonded together in the hot press. The wax
 employed in producing the wafer board is an aliphatic petroleum product
 referred to generally as a slack wax and is used in an amount in the range
 of 1 to 2 wt % of the wafer board, based on the oven dry weight of the
 wafer board.
 While not so recited in the literature the slack wax generally used in the
 production of manufactured wafer or fiber board is typically 30 grade
 slack wax (550 N) which typically has an oil content in the range 18-28 wt
 %, more usually 18-21 wt % oil. A 10 grade slack wax (150 N) has also been
 used and it has a typical oil content in the range 12-28 wt %, more
 usually 14-21 wt %.
 "The Effect of Wax Type and Content on Waferboard Properties" Hsu, et al,
 International Particleboard/Composite Materials Symposium, 1990, pp.
 85-93, discusses and addresses the effect of wax content and oil content
 in wax on the physical properties of waferboard. The paper addresses
 waferboard swelling in response to from zero to 4.5% wax content as well
 as waferboard swelling and internal bond strength in response to from 0 to
 30 wt % oil content in the wax used in the production of the waferboard.
 DESCRIPTION OF THE INVENTION
 The present invention is a manufactured board product comprising natural
 fibrous material, resin and a hydrocarbonaceous material comprising one or
 more natural, synthetic or petroleum waxy material containing from more
 than 30 wt % oil to up to 98 wt % oil. The present invention also relates
 to an improved method for producing a manufactured board product
 comprising combining natural fiber material, resin and oily
 hydrocarbonaceous material, forming the mixture into a layer and
 subjecting the layer to heat and pressure, the improvement comprising
 using as the oil hydrocarbonaceous material a natural, synthetic or
 petroleum wax containing greater than 30 wt % to up to 98 wt % oil.

DETAILED DESCRIPTION OF THE INVENTION
 Manufactured composite board products are described comprising natural
 fibrous material, resin and an oily hydrocarbonaceous material comprising
 any natural, synthetic, or petroleum wax containing greater than 30 wt %
 up to 98 wt % oil.
 Natural fibrous material, preferably porous material, includes wood chips,
 wafers, saw dust, wood fibers, cotton or other plant fibers, straw, bamboo
 cellulose, paper, acetate, etc. The fibrous material generally constitute
 about 90% to 98% of the final board product.
 Resins used in the production of manufactured board materials are well
 known to those skilled in the production of manufactured board products.
 Representatives of such resins are synthetic thermosetting resins produced
 by the poly condensation of formaldehyde or a formaldehyde donor with
 other suitable compounds. Examples of suitable adhesive resins include
 phenol formaldehyde, urea formaldehyde and melamine formaldehyde resins.
 Phenol formaldehyde resins are typically the condensation products of a
 phenol compound, e.g., an arythytroxide such as phenol, cresols, xylenols
 or resorcinol with a formaldehyde or a formaldehyde donor compound such as
 paraformaldehyde or methylene tetramine.
 Other adhesives have been or are being considered for use or are in use in
 the production of manufactured board products and include tannins,
 isocyanates, sulfite liquor and admixtures of kraft tannins or sulfite
 liquor and phenol formaldehyde resins. Other resins can be used at the
 discretion and choice of the practitioner to satisfy his compositional or
 economic requirement.
 The above is presented solely as non-limiting examples. Other adhesive
 resins common in the manufactured board product industry may also be used
 without limitation and the choice of the adhesive resin is left of the
 practitioner's particular needs or preferences.
 The waxy hydrocarbonaceous material comprises one or more natural,
 synthetic or petroleum waxes containing greater than 30 wt/o to up to 98
 wt % oil, preferably about 35 wt % to 95 wt % oil, more preferably about
 40 wt % to 90 wt % oil, most preferably about 40 wt % to 85 wt % oil.
 Natural waxes include bees wax, scale insect waxes, animal waxes, such as
 woolwax, spermaceti, marine oil waxes, plant waxes such as palm tree
 waxes, candelilla wax, retamo wax, flax wax, cotton wax, lemp wax,
 sugarcane wax, esparto wax, sorghum-grain wax, ricebran wax, leaf blade
 wax, root wax, cranberry wax, fruit cuticle waxes, vegetable waxes, etc.,
 as well as fossil waxes such as monton wax, ceresin, peat wax, alpco wax,
 paraffin wax from shale oils or brown coal.
 Synthetic waxes include waxes made by Fisher-Tropsch process from synthesis
 gas. Other synthetic waxes include polyethylene wax, ethylene copolymer
 wax, carbo waxes.
 Petroleum waxes include waxes recovered by, e.g., the solvent dewaxing of
 waxy hydrocarbon oil streams as part of the petroleum refinery process
 including slack waxes and also includes hydrocracked waxes. Other
 petroleum waxes include waxy petroleum stocks such as waxy distillates,
 raffinates, petrolatum, microcrystalline waxes, etc.
 These waxes can be used individually or as mixtures of waxes and in
 combination with one or more grades of oil. The waxy hydrocarbonaceous
 material used in the present invention is marked by an oil content higher
 than that commonly accepted in the manufactured composite board product
 industry as associated with the term "slack wax".
 Whereas the "slack waxes" traditionally used have had an oil content in the
 12-28 wt %, more usually 14-21 wt % range for 10 grade slack wax and in
 the 18-28 wt %, more usually 18-21 wt % range for 30 grade slack wax, the
 waxy hydrocarbonaceous material used in the present invention has an oil
 content of more than 30 wt % and up to 98 wt %, as previously recited.
 The oil can be any natural or synthetic oil including the oil inherently
 present in a waxy oil stream as a result of adjusting the severity of any
 dewaxing or deoiling process practiced, and can include one or more
 deliberately added oil fractions derived from such sources as petroleum
 oils, e.g., naphthenic and paraffinic oils, tar sand oils, shale oils,
 coal oils, oils produced via Fischer-Tropsch processes, isomerized oil,
 isomerized wax oil, hydrocracked oil, as well as such natural oils as
 those derived from plant and animal sources such as corn oil, palm oil,
 peanut oil, olive oil, cotton seed oil, soy oil, whale oil, fish oil,
 tallow oil, etc.
 The recited oil content can be achieved by adding one or more waxes to one
 or a mixture of a dewaxed or low wax content oil as or by adding one or
 more oils to one or a mixture of low oil content work. For example, in the
 case of slack waxes a useful waxy hydrocarbonaceous material can be
 obtained by not deoiling the slack wax as vigorously or extensively as
 hereto for has been normally practiced. Alternatively, oil can be added in
 an appropriate amount to wax to achieve the desired oil content.
 Conversely wax can be added in an appropriate amount to wax free or low
 wax content oil to achieve a blended product having an oil content in the
 recited range. Waxy hydrocarbonaceous material useful in the present
 invention can also include waxy liquid hydrocarbon streams per se such as
 waxy raffinate recovered from the solvent extraction of aromatic
 hydrocarbons from petroleum distillate fractions, as well as waxy
 distillates themselves the desired oil content being obtained by
 controlling the extent of any dewaxing step.
 The wax and oil can be of the same or different grades. Thus, using slack
 wax as an example, a slack wax of any suitable grade with an oil content
 of about 18 wt % can have admixed with it from at least 12 wt % to 70 wt %
 grade 10 to bright stock oil. Thus, a 10 grade slack wax can be combined
 with a grade 10 to bright stock grade oil, or mixture of oils. The same
 holds true for natural and synthetic waxes. Any such wax or mixture of
 such waxes can be combined with any grade oil to produce the waxy
 hydrocarbonaceous material containing more than 30 wt % to up to 98 wt %
 oil.
 Conversely a wax raffinate can be similarly employed provide the oil
 content is more than 30% oil.
 Wax content and oil content are as determined at 20.degree. C. (ASTM 3235).
 Thus, if at 20.degree. C. a material has no visible or recoverable solid
 wax, for the purposes of this specification it is of zero wax content.
 As envisioned herein, the oil can be present with or added to the wax as
 such or can contain minor amounts of additives which do not interfere with
 the production of the manufactured board products. Thus, the waxy
 hydrocarbonaceous material, being a mixture of wax and oil, can contain
 minor amounts of, for example anti-oxidants, antiwear materials,
 detergents, dispersants, pour point dispersants, corrosion inhibitors,
 dyes, fungicides, insecticides, etc. Such additives can be added to the
 waxy hydrocarbonaceous material, or can be present in or added to the
 separate oil fraction which is added to the wax to bring the oil content
 into the recited range.
 It has been discovered that manufactured composite board product made using
 the waxy hydrocarbonaceous material as defined herein at least meets, and
 with respect to some measurement criterion exceeds, the swell and water
 absorption performance characteristics of board product made using the
 traditional slack wax of 18-28 wt % oil content.
 Experimental
 Typical 30 grade slack waxes were blended with an additional 40 and 70 vol
 % of a 30 grade base oil. Data from these blends were carefully compared
 to the typical result using the straight 30 grade wax (oil content of
 about 22 vol %) in the production of manufactured composite board product.
 Initial results demonstrate superior thickness swell and water absorption
 properties with the use of the high oil content waxy hydrocarbonaceous
 material, Table 1. The manufactured boards of Table 1 were made using
 phenol formaldehyde powder resin on both the faces and in the core of the
 boards.
 Additional examples were run to evaluate high oil content wax in the
 production of manufactured board material using different adhesive system.
 In the examples of Table 2, MDI (a polymeric diphenylmethyl dissocyanate)
 was used in the core and liquid phenol formaldehyde (typically consisting
 of approximately 50% water) was applied to the face of the manufactured
 boards.
 The results in Table 2 show that regardless of the adhesive system
 employed, the use of the high oil content wax results in the production of
 manufactured board material at least equivalent in quality to board
 manufactured using conventional slack wax.
 TABLE 1
 Thickness Edge H.sub.2 O
 Swell Swell Absorption
 (24 hours) (24 hours) (24 hours)
 1. reference wax 17.5 31.0 31.0
 (30 grade slack wax)
 (.about.22 vol % oil)
 dosage:
 1%/1% face/core application
 2. reference wax + 40% more 17.2 30.3 27.9
 30 grade oil (.about.53 vol % oil)
 dosage:
 1%/1% face/core application
 3. reference wax + 70% more 16.9 30.9 30.1
 30 grade oil (.about.77 vol % oil)
 dosage:
 1%/1% face/core application
 Data from 2 and 3 produce data similar or better than 1 (which represents
 typical industry standard).
 TABLE 2
 HIGH OIL CONTENT WAX DATA
 Thickness
 Water
 Total Total % Internal Swell
 Edge Swell Absorption
 Exp. Oil Oil Wax Bond 2 hr. 24
 hr. 2 hr. 24 hr. 2 hr. 24 hr.
 # Composition Vol % Wt % Face/Core psi % % %
 % % % Comments
 The following data provides comparison of conventional 30 grade slack wax
 vs. conventional
 slack wax with increased oil content
 1 30 grade slack wax 22 17.6 1.0/1.0 65.8 5.0 14.9
 10.0 27.1 10.3 26.9 reference (base case)
 wax with MDI core
 2 30 grade slack wax 22 17.6 2.0/2.0 54.4 4.9 12.9
 8.5 22.6 9.7 23.5 reference (base case)

dosages
 Most comparisons are done with the 1.0/1.0 dosage which is typical of
 industry.
 Higher dosages were studied to assess any potential benefits.
 Significance of "% number" for Thickness Swell, Edge Swell and Water
 Absorption: a variation of greater than "2%" indicates a difference.
 Based on comparison of Face/Core dosages, an increase to 2.0/2.0 with a
 total oil volume of 92%, may generate data equal to Exp. #1.
 Wt % Total Oil - calculated by converting Vol % Total Oil by 0.8 (typical
 wax/oil density).
 Experiments 11 through 14 demonstrates the potential of varying wax and oil
 grades
 11 60% 60 grade slack wax + 53 42.4 1.0/1.0 57.7 6.7
 20.2 13.6 32.6 14.3 36.8 different oil/wax
 40% 30 grade oil
 grades
 12 60% 60 grade slack wax + 53 42.4 2.0/2.0 52.4 5.5
 16.7 11.5 29.5 12.0 30.8 different oil/wax
 40% 30 grade oil
 grades
 13 60% 30 grade slack wax + 53 42.4 1.0/1.0 59.5 5.2
 16.9 12.2 31.2 10.9 29.5 different oil/wax
 40% 60 grade oil
 grades
 14 60% 30 grade slack wax + 53 42.4 2.0/2.0 52.9 4.8
 14.2 9.2 27.7 9.3 23.5 different oil/wax
 40% 60 grade oil
 grades
 Most comparisons are done with the 1.0/1.0 dosage which is typical of
 industry.
 Higher dosages were studied to assess any potential benefits.
 Significance of "% number" for Thickness Swell, Edge Swell and Water
 Absorption: a variation of greater than "2%" indicates a difference.
 Wt % Total Oil - calculated by converting Vol % Total Oil by 0.8 (typical
 wax/oil density).