JP2023115416A - Plywood/cloth psf/paper psf complex - Google Patents

Abstract

To provide a complex that is more durable, particularly in terms of wear resistance, than coated plywood, which is used for various applications including a concrete form.SOLUTION: A complex comprises plywood, cloth PSF (phenolic resin surface film), and paper PSF, which are laminated in the stated order.SELECTED DRAWING: None

Description

The present invention relates to composites that are more durable than coated plywood used for concrete forms and the like.

A typical application of painted plywood is concrete formwork. When used as a concrete formwork, the coated plywood is reused many times without being discarded after being used only once. If the abrasion resistance is low, the surface of the coated plywood becomes rough, and when the concrete formwork is removed, it becomes impossible to obtain a clean concrete surface.
Other uses of painted plywood include flooring in temporary housing, wainscoting and floorboards in factories, interiors of livestock sheds, and temporary enclosures for painting bridges and repainting highways.
Since it is used in such a way that it is directly touched by people and is used in such a way that it is assembled and disassembled many times, further durability, especially abrasion resistance, is required.

On the other hand, PSF is an abbreviation for Phenolic resin Surface Film, which is a prepreg made by impregnating paper, cloth, or the like with phenolic resin and semi-curing it. PSF can also be adhered to an adherend by placing the PSF on some adherend and subjecting it to thermocompression molding. In the present application, prepreg made by impregnating paper with phenolic resin is referred to as paper PSF, and prepreg made by impregnating cloth with phenolic resin is referred to as cloth PSF.

JP 2000-053738 JP 2000-327797 JP 2009-091446 JP 2003-127156

Patent Document 1 is a publication relating to curable resins useful for adhesives, coating agents, binders and the like, and curable materials and molding materials using the same. The substrate is coated or impregnated with phenolic resin, and hot-pressed. Patent Document 2 is a publication relating to a molding material used for automobile interior materials, building materials, etc., an interior material using the same, and a method for producing the molding material. Fibers are impregnated with phenolic resin and hot-pressed, but as in Patent Document 1, no consideration has been given as to alternatives to coated plywood.

Patent Document 3 is a publication relating to a fiber-reinforced resin composition used for sliding members such as sliding bearings and a laminated sliding member using the same. Fibers are impregnated with resol-type phenolic resin to produce prepregs, but no consideration has been given as to alternatives to coated plywood. Patent Literature 4 is a publication relating to a method for manufacturing a fiber-based building board, in which a mixture of plant fibers and a resin binder is thermocompressed. There was room for improvement in using it as a substitute for painted plywood.

To obtain a composite having higher durability, especially higher abrasion resistance than concrete formwork and coated plywood used in various other ways.

As a result of intensive studies by the inventors, a composite was obtained in which plywood, cloth PSF, and paper PSF were laminated in this order.

It is more durable than concrete formwork and painted plywood that is used in various other ways, and because it is a composite with particularly high abrasion resistance, it can be used not only as a concrete formwork, but also as a flooring material for temporary housing, and for factory floors. It can maintain a good appearance even when it is used as the interior of a livestock building, or as a temporary enclosure for bridge painting work or expressway repainting work.

1 shows an example of a plywood/fabric PSF/paper PSF composite of the present invention.

The phenolic resin used for the cloth PSF and paper PSF of the present invention may be either resol resin or novolak resin. In the case of a resole resin, a prepreg can be obtained by carrying out aqueous polymerization, impregnating cloth or paper, and heating to 100 to 150°C. In the case of a novolak resin, a prepreg can be obtained by dissolving the novolac resin in a solvent, adding tetramethylenehexamine, impregnating cloth or paper with the solution, and heating to 100 to 150°C. From the standpoint of storage stability of the prepreg, a more suitable resin is a resol resin.

A resol-type phenolic resin is produced by reacting phenols (P) and aldehydes (F) in the presence of an alkali catalyst (C).
Phenols (P) used in the present invention include, for example, phenol, cresol, xylenol, nonylphenol, para-tertiary-butylphenol, para-secondary-butylphenol, naphthol, catechol, resorcinol, hydroquinone, methylhydroquinone, dimethylhydroquinone, and the like. is mentioned.
As the aldehydes (F), any aldehydes (F) that can be used in the production of phenolic resins can be used.
For example, formaldehyde, paraformaldehyde, trioxane (metaformaldehyde) and the like can be used alone or in combination of two or more.
The amount of the aldehydes (F) used is 0.5 to 3.5 mol, more preferably 1.0 to 3.0 mol, per 1 mol of the total amount of the phenols (P). desirable.

The catalyst (C) used in reacting the phenols (P) and the aldehydes (F) is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, hydroxide Basic catalysts such as magnesium, trimethylamine, triethylamine and tributylamine can be used as appropriate.
The method of reacting the phenols (P) and the aldehydes (F) is not particularly limited. Alternatively, a method of adding aldehydes (F) at a predetermined reaction temperature after charging phenols (P) and catalyst (C) can be mentioned.
When a large amount of catalyst (C) is used, the reaction is quite exothermic, so catalyst (C) can be charged in portions in order to prevent thermal runaway reaction.

The amount of aldehydes (F) added in the primary reaction is 100 to 170 parts by mass, more preferably 120 to 150 parts by mass with respect to 100 parts by mass of phenols (P) in the case of 47%-formaldehyde. The amount of the catalyst (C) added in the primary reaction is 1 to 20 parts by mass, more preferably 3 to 15 parts by mass for 100 parts by mass of the phenol (P) in the case of a 48% sodium hydroxide solution. The primary reaction is preferably carried out at a reaction temperature of 30 to 55°C, more preferably 35 to 50°C, by adding specified amounts of aldehydes (F), phenols (P) and catalyst (C). .

Once the temperature stabilizes, additional catalyst (C) is added to initiate secondary reactions. In the case of 48%-sodium hydroxide, the amount of the catalyst (C) added is 1 to 20 parts by mass, more preferably 3 to 15 parts by mass, per 100 parts by mass of the phenol (P). After the addition of 48%-sodium hydroxide, the secondary reaction temperature is preferably in the range of 50-90°C, more preferably 60-80°C.

After the secondary reaction is finished, urea that reacts with unreacted aldehydes (F) can be added to remove unreacted aldehydes (F). The amount of urea to be added is 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of phenols (P).

Commercially available kraft paper can be used as the paper used for the paper PSF. If the production volume is large, roll goods can also be used. A prepreg is completed by impregnating commercially available kraft paper with an aqueous resole resin solution that has already been synthesized, squeezing out excess phenolic resin aqueous solution with two rolls, and passing it through a hot furnace at 110 to 150°C.

As for the cloth used for the cloth PSF, cloth of natural materials such as cotton, hemp, silk, etc., cloth of nylon, polyamide, polyester, polyacrylonitrile, polyvinyl alcohol, polyurethane, polyolefin, and synthetic fiber can be used. Since it is impregnated with an aqueous solution of phenolic resin, more suitable materials include cotton, polyester, polyvinyl alcohol, and polyurethane.
A fabric woven from multiple materials can also be used.
A cloth PSF can be obtained in a manner similar to the method of making a paper PSF.

Commercially available plywood can be used for preparing the plywood/fabric PSF/paper PSF composite, and either softwood or hardwood can be used. A plywood having a thickness of 2.5 to 30 mm, more preferably 5 to 20 mm is preferably used. Coniferous trees are more difficult to bond than hardwoods because they contain more tar and the like.

As for the method for producing the plywood/fabric PSF/paper PSF composite, it can be laminated in this order and produced by thermocompression molding.
The pressing condition is 0.3 to 3.0 MPa, more preferably 0.5 to 2.0 MPa, the temperature condition is 100 to 150° C., more preferably 110 to 140° C., and the pressing time is 1 to 60 minutes, more preferably 5 to 50 minutes.

Synthesis of resole resin 10 kg of phenol, 14 kg of 47%-formaldehyde, 1.5 kg of water, and 0.5 kg of 48%-sodium hydroxide were weighed into a reaction vessel and heated to 40 to 45 ° C. with stirring for 1 hour. Stir to complete the primary reaction. Then 0.5 kg of 48%-sodium hydroxide was added to initiate the secondary reaction. The secondary reaction was completed by stirring for 3.5 hours so as not to exceed 80°C. Finally, 0.5 kg of urea was added and dissolved to terminate the reaction.
This resole resin had a viscosity of 109 mPa·s at 30° C. and a solid content of 53.4%.

Preparation of paper PSF Kraft paper with a width of 1200 mm is impregnated with resole resin obtained by synthesizing resole resin, passed through two rolls, squeezed out excess phenolic resin aqueous solution with two rolls, and heated in a hot furnace at 130 ° C. to make paper. A PSF prepreg was made. The line speed in the furnace was 30 m/min.
In Tables 1 to 4, these are described as paper PSF.

Fabrication of Cloth PSF Three kinds of cloth (100/0), (37/63), and (20/80) were prepared with a (cotton/polyester) ratio of 1200 mm width on a weight basis. Three types of fabric PSF prepregs were produced in the same manner as the paper PSF production method. Tables 1 to 4 show these three types as fabric PSF (C/P) = (100/0), fabric PSF (C/P) = (37/63), fabric PSF (C/P) = ( 20/80).

Preparation of plywood/fabric PSF/paper PSF composite of Example 1 In carrying out Examples 1 to 12 and Comparative Examples 1 to 12, commercially available 150 mm × 150 mm × 12 mm thick softwood plywood and hardwood plywood, 150 mm × 150 mm paper PSF, fabric PSF (C/P) = (100/0), fabric PSF (C/P) = (37/63), and fabric PSF (C/P) = (20/80) were prepared.
The plywood/fabric PSF/paper PSF composite of Example 1 was prepared by putting cloth PSF (C/P)=(100/0) on softwood plywood and placing paper PSF on top of it, and subjected to heat treatment at 130° C., 1.2 MPa, Hot compression molding was performed for 10 minutes.

Preparation of plywood/fabric PSF/paper PSF composites of Examples 2-12 and Comparative Examples 1-12 Using the materials shown in Tables 1-4, the plywood/fabric PSF/paper PSF composites of Example 1 were prepared. Plywood/fabric PSF/paper PSF composites of Examples 2 to 12 and Comparative Examples 1 to 12 were produced in a similar manner. Hardwood plywood was used for Examples 8 to 10, and softwood plywood was used for the others.
Plywood was used in all of Examples 2 to 12 and Comparative Examples 1 to 12, and the materials to be placed thereon are marked with (○) in Tables 1 to 4.
Moreover, Comparative Examples 1 to 12 are not necessarily composites of plywood/cloth PSF/paper PSF. The substrate weight (paper or cloth weight) and phenolic resin loading are also shown in Tables 1-4.

The test was conducted according to the abrasion resistance test method JIS K6902 (thermosetting resin high pressure decorative panel test method).
Tester: 5155ABRASER manufactured by TABER
Load: 500g
Sandpaper: 200MP manufactured by 3M
Rotation speed: 72

Abrasion Resistance Test Results The plywood/fabric PSF/paper PSF composite of Example 1 and the commercially available painted plywood (150 mm×150 mm×12 mm thick) as Reference Example 1 were used.
The plywood/fabric PSF/paper PSF composites were marked with the number of times the fabric under the paper was exposed. For the coated plywood, Table 5 shows the abrasion resistance test results in which the number of times the plywood substrate was exposed was entered. In addition, the test is performed with n=2.
The plywood/fabric PSF/paper PSF composite was shown to be significantly more wear resistant than the painted plywood.

JAS cold-heat cyclic (crack) test The test piece is fixed to a metal frame, left in a constant temperature chamber at 60 ± 3 ° C for 2 hours, and then left in a constant temperature chamber at -20 ± 3 ° C for 2 hours. Repeat the process twice. , until it reaches room temperature. Check the appearance (cracks) of the non-plywood side of the test piece that has returned to room temperature. Criteria for judgment are: pass (: ◯) when no cracks, swelling, or peeling is observed, and fail (: x) when cracks, swelling, or peeling is observed. The results are shown in Tables 6-9.

About 5 mL of 1% sodium hydroxide aqueous solution is dripped on the non-plywood side of the JAS alkali resistance (blister) test piece, covered with a watch glass for 48 hours, immediately washed with water, and left indoors for 24 hours. As a judgment standard, if the aqueous solution remains after 48 hours, it is accepted (: O), and if the aqueous solution does not remain, it is rejected (: x). Also, after leaving for 24 hours, if there are no cracks, blisters, peeling, significant discoloration, or change in gloss, it passes (: ○). : ×). The results are shown in Tables 6-9.

JAS alkali resistance (solution discoloration) test The same operation as in the JAS alkali resistance (swelling) test is performed. As the judgment criteria, the case where there is no discoloration of the aqueous solution is accepted (: ◯), and the case where there is discoloration of the aqueous solution is rejected (: x). The results are shown in Tables 6-9.

A metal plate having a square adhesive surface with a piece of 20 mm in the center of the non-plywood surface of the JAS plane tensile test specimen is adhered using a cyanoacrylate adhesive, and the scratches up to the plywood around the metal , and pulled at a load speed of 5,880 N or less per minute in a direction perpendicular to the bonding surface, and the maximum load at the time of separation or breaking was measured. Judgment criteria are n=2 average, 1.0 MPa or more is pass (: ◯), less than 1.0 MPa is fail (: ×). The results are shown in Tables 6-9.

Examples 1 to 12, which are composites in which plywood, cloth PSF, and paper PSF are laminated in this order, were subjected to a JAS cold-heat cycling (crack) test, a JAS alkali resistance (blister) test, a JAS alkali resistance (solution discoloration) test, and a JAS All plane tensile tests passed.

Comparative Examples 1 to 3, in which only paper PSF was laminated to plywood, failed the JAS cold-heat cycling (crack) test. Comparative Examples 4 to 6, in which only the cloth PSF was attached to the plywood, failed the JAS alkali resistance (blister) test.

Comparative Examples 7 to 9, in which the paper PSF and the paper PSF were laminated to the plywood, failed the JAS cold-heat cycle (crack) test. Comparative Examples 10 to 12, in which the fabric PSF was attached to the plywood and the fabric PSF was further attached, failed the JAS alkali resistance (swelling) test.

Claims (5)

A composite in which plywood, cloth PSF, and paper PSF are laminated in that order. The composite according to claim 1, wherein the phenolic resin of the cloth PSF and paper PSF is a resol resin, and the impregnated amount of the phenolic resin is 30 to 250 g/m2. The PSF according to claim 1 or claim 2 is a paper PSF prepreg that is semi-cured at 100 to 150 ° C. after impregnating paper with phenol resin, and after impregnating cloth with phenol resin, Composites made with fabric PSF prepreg semi-cured at 100-150°C. The composite according to any one of claims 1 to 3, wherein the plywood is softwood. The composite according to claim 1, which is obtained by stacking plywood, cloth PSF, and paper PSF in this order and then heat-pressing them at 100 to 150°C at 0.5 to 2.0 MPa for 1 to 60 minutes.