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CN-122013593-A - Modified red phenolic resin impregnated paper for concrete templates and laminated plywood

CN122013593ACN 122013593 ACN122013593 ACN 122013593ACN-122013593-A

Abstract

A modified red phenolic resin impregnated paper for concrete templates is prepared through adding nano silicon dioxide 0.8-1.2wt%, nano aluminium oxide 1.5-2.0wt% and tetrapod-like zinc oxide whisker 0.5-1.0wt% into red phenolic resin glue solution, pre-dispersing for 5min by high-speed shearing at 800-1000r/min, ultrasonic dispersing for 20-30min at 300-500W, immersing wood pulp paper in glue solution, and drying at 110-120 deg.C until water content is 6-8%. The invention also discloses a red laminated plywood for the concrete formwork and a preparation process thereof, and the improvement of the comprehensive performance of the plywood is realized through surface modification, core layer structure optimization and cooperative improvement of an adhesive and the preparation process, so that the high standard requirement of the formwork in building construction is met.

Inventors

  • DU MINGYAO
  • XIA CHUNLAN

Assignees

  • 荆州市远牛木业有限公司

Dates

Publication Date
20260512
Application Date
20260304

Claims (9)

  1. 1. The preparation method is characterized in that 0.8-1.2wt% of nano silicon dioxide, 1.5-2.0wt% of nano aluminum oxide and 0.5-1.0wt% of tetrapod-like zinc oxide whisker are added into red phenolic resin glue solution, the mixture is sheared and pre-dispersed at a high speed of 800-1000r/min for 5min, and then dispersed at a power of 300-500W for 20-30min in an ultrasonic manner; Wherein the particle size of the nano silicon dioxide is 10-30nm, the particle size of the nano aluminum oxide is 50-80nm, the needle length of the tetrapod-like zinc oxide whisker is 10-20 mu m, and the needle diameter is 0.5-1 mu m.
  2. 2. The modified red phenolic resin impregnated paper for concrete forms according to claim 1, wherein the modified red phenolic resin impregnated paper has a thickness of 0.25-0.3mm and a water content of 6-8% after drying.
  3. 3. The modified red phenolic resin impregnated paper for concrete forms according to claim 1, wherein the wood pulp paper is softwood bleached kraft pulp paper having a basis weight of 120-150g/m2.
  4. 4. The laminated plywood for the concrete template comprises a surface layer, a core layer and a bottom layer, and is characterized in that, The surface layer is modified red phenolic resin impregnated paper added with nano silicon dioxide, nano aluminum oxide and tetrapod-like zinc oxide whiskers; the core layer is of a eucalyptus layer-poplar layer-eucalyptus layer symmetrical laminated structure, the eucalyptus layer is 2 layers of eucalyptus veneers, the poplar layer is 3 or 5 layers of poplar veneers, and the total number of layers of the veneers of the core layer is 7 or 9; The bottom layer is undyed phenolic resin impregnated paper; the surface layer and the core layer and the bottom layer and the core layer are bonded by adopting phenolic resin glue, the glue coating amount of the wet glue is 180-220g/m < 2 >, the veneers in the core layer are bonded by adopting melamine-phenolic resin composite glue, and the glue coating amount of the wet glue is 220-260g/m < 2 >.
  5. 5. The laminated plywood for the concrete templates, which is disclosed in claim 4, is characterized in that the preparation method of the melamine-phenolic resin composite adhesive comprises the steps of taking liquid melamine formaldehyde resin and liquid phenolic resin according to a mass ratio of 1:3-1:4, completing compounding under stirring at normal temperature of 300-400r/min, adding 2.0-3.0wt% of polyethylene glycol, 0.3-0.5wt% of hexamethylenetetramine and 0.1-0.2wt% of organic silicon defoamer into the compounded liquid, stirring and dispersing uniformly, adjusting the solid content to 40-45% by deionized water, curing at normal temperature for 30min, and filtering by 120 meshes to obtain the composite adhesive.
  6. 6. The laminated plywood for concrete forms according to claim 4, wherein the eucalyptus veneer has a water content of 8-10%, the poplar veneer has a water content of 8-10%, and the veneer grain crossing angle is 90 ° ± 5 ° at the time of core layer assembly.
  7. 7. The laminated plywood for concrete forms of claim 4, wherein the thickness of the bottom layer is 0.2-0.25mm.
  8. 8. The red laminated plywood for concrete forms according to claim 4, wherein the density of the eucalyptus veneer is not less than 650kg/m3, and the density of the poplar veneer is not less than 450kg/m3.
  9. 9. The process for preparing a laminated plywood for a concrete form according to any one of claims 4 to 8, comprising the steps of: S1, preparing a surface layer and a bottom layer, namely preparing modified red phenolic resin impregnated paper and undyed phenolic resin impregnated paper; S2, assembling a core layer, namely drying the eucalyptus veneer and the poplar veneer to have the water content of 8-10%, assembling according to a symmetrical eucalyptus layer-poplar layer-eucalyptus layer structure, coating phenolic resin glue among the surface layer, the bottom layer and the core layer, and coating melamine-phenolic resin composite glue inside the core layer; S3, sectional hot press molding: Pre-pressing at 80-90deg.C under 0.6-0.8MPa for 10-15min to primarily infiltrate the adhesive and discharge air; Gradient hot-pressing stage, namely adopting a gradient heating three-stage process, wherein the total hot-pressing time is 1.2-1.6min/mm according to the thickness of the slab: ① The core layer pre-fixing section is heated to 133-135 ℃ and the pressure is increased to 1.2-1.4MPa, and the temperature and pressure are maintained for 0.6-0.8min/mm; ② A gradient heating section for heating to 142-144 ℃ at a constant speed of 3-5 ℃ per minute, keeping the pressure at 1.2-1.4MPa, and keeping the pressure at 0.5-0.7min per mm; ③ Maintaining the temperature and curing stage at 142-144 deg.C, reducing the pressure to 0.9-1.1MPa, and maintaining the temperature for 0.2-0.3min/mm; The secondary curing stage, namely cooling to 100-110 ℃, keeping the pressure at 0.8-1.0MPa, and preserving the heat for 3-5min to realize deep combination of the surface layer, the bottom layer and the core layer; S4, post-treatment, namely cutting the product to a standard size after hot pressing, polishing corners, and sanding the surface until the flatness is less than or equal to 0.10mm/m, thereby obtaining a finished product.

Description

Modified red phenolic resin impregnated paper for concrete templates and laminated plywood Technical Field The invention relates to the technical field of resin impregnated paper, in particular to modified red phenolic resin impregnated paper for a concrete template and a laminated veneer board. Background The concrete template is an indispensable temporary support structure in building construction, and the performance of the concrete template directly influences the surface quality, the construction efficiency and the engineering cost after concrete pouring. The laminated plywood is widely applied to the field of concrete templates due to the advantages of smooth surface, convenient demoulding, reusability and the like, wherein the red laminated plywood is convenient for construction site identification and classification management due to the striking color, has certain decoration and becomes one of main stream products in the current market. However, the existing red coated plywood for the concrete template still has many defects that firstly, the surface layer red coated plywood is mainly made of common phenolic resin impregnated paper, the wear resistance and scratch resistance are poor, the surface of the template is rough and affects the surface evenness of the subsequent concrete, the repeated use times of the template are reduced, secondly, the core layer is mainly made of single poplar or eucalyptus veneers in a laminated mode, the poplar veneers are low in density and insufficient in strength, the eucalyptus veneers are poor in toughness, the single-structure core layer is easy to deform and laminate, the integral bearing capacity of the plywood is affected, thirdly, the adhesive is unreasonable in selection, the bonding strength between the surface layer, the bottom layer and the core layer is insufficient, the problem of degumming is easy to occur between veneers in the core layer, particularly the defect of poor water resistance is more prominent under a wet construction environment, fourthly, the thermal pressing parameter in the existing preparation process is unreasonable, the adhesive is not cured, the problem of layering and film covering is further aggravated, and the service life of the template is shortened. Disclosure of Invention The invention aims to overcome the defects of poor wear resistance, insufficient water resistance, easy deformation of a core layer, easy falling of a coating and short service life of a red coated plywood for a concrete template in the prior art, and provides the red coated plywood for the concrete template and a preparation process thereof. The red coated plywood for the concrete template comprises a surface layer, a core layer and a bottom layer, wherein the surface layer is modified red phenolic resin impregnated paper added with nano silicon dioxide, nano aluminum oxide and tetrapod-shaped zinc oxide whiskers, the core layer is a eucalyptus layer-poplar layer-eucalyptus layer symmetrical laminated structure, the eucalyptus layer is a 2-layer eucalyptus veneer, the poplar layer is a 3-layer or 5-layer poplar veneer, the total veneer layer of the core layer is 7 or 9-layer, the bottom layer is undyed phenolic resin impregnated paper, the surface layer is bonded with the core layer, the bottom layer is bonded with the core layer by phenolic resin adhesive, the wet adhesive coating amount is 180-220g/m < 2 >, the veneers inside the core layer are bonded by melamine-phenolic resin composite adhesive, and the wet adhesive coating amount is 220-260g/m < 2 >. The preparation method of the modified red phenolic resin impregnated paper comprises the steps of adding 0.8-1.2wt% of nano silicon dioxide, 1.5-2.0wt% of nano aluminum oxide and 0.5-1.0wt% of tetrapod-like zinc oxide whiskers into red phenolic resin glue solution, shearing and pre-dispersing at a high speed of 800-1000r/min for 5min, then dispersing at a power of 300-500W for 20-30min, immersing needle wood bleached sulfate pulp paper in glue solution, and drying at 110-120 ℃ to a water content of 6-8%, thereby obtaining the modified red phenolic resin impregnated paper, wherein the particle size of the nano silicon dioxide is 10-30nm, the particle size of the nano aluminum oxide is 50-80nm, the needle length of the tetrapod-like zinc oxide whiskers is 10-20 mu m, and the needle diameter is 0.5-1 mu m. Preferably, the wood pulp paper is needle-leaved wood bleached kraft pulp paper, the ration is 120-150g/m < 2 >, the wood pulp paper has high fiber strength and uniform water absorption, can fully adsorb modified red phenolic resin glue solution, and ensures the wear resistance and toughness of surface impregnated paper. The preparation method of the melamine-phenolic resin composite adhesive comprises the steps of taking liquid melamine formaldehyde resin and liquid phenolic resin according to a mass ratio of 1:3-1:4, completing compounding under stirring at normal temperature of 300-400r/min, adding 2.0