JPS5926203A - Surface treating method for wood - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for surface treatment of wood used for pallet deck boards, wall coverings, bridge girders, etc.

Pallets are used to transport drums, containers, etc. using pallets, and the majority of these pallets are made of wood.

Wooden pallets have the advantage of having a large coefficient of friction, making it difficult for loaded cargo to slip off, and making it easy to incinerate once they are no longer useful. This has the disadvantage that the moisture contained in the wood is excessively dissipated, causing the deck board to warp or crack, and its lifespan is only 2 to 3 years.

As an improvement on the shortcomings of wooden pallets,
Pallets made of steel-reinforced foamed plastic are commercially available. Although pallets made of steel-reinforced foamed plastic have excellent water and chemical resistance, they have problems with incineration and are expensive, so they cannot be used with chemicals such as sulfuric acid. The reality is that they are only used in special fields, such as fields, and the demand for them is sluggish.

Therefore, in order to impart water resistance to wood or prevent water from drying out, there is a method of applying paint to the wood surface, impregnating it, and heating and drying it to form a coating film (for example, Japanese Patent Application Laid-Open No. 49-1348
04 and JP-A-51-76405), a method has been proposed in which wood is impregnated with a polymerizable vinyl monomer or unsaturated polyester resin and then heated and polymerized. However, these solvent-based paints and oil-based polymerizable paints
The method using l't'n3 bodies has the disadvantage that impregnation requires a long time.

In order to overcome these drawbacks of impregnation, for example, as seen in JP-A-55-71501, sBR latex and ethylene-vinyl acetate copolymer aqueous emulsions have a minimum film-forming temperature of 0 to 0. A method has been proposed in which a wood surface is coated with an aqueous dispersion at 40 DEG C. and then dried at room temperature to form a coating film having a water vapor transmission rate of 10 to 100'/day/day. The treated wood obtained by this method has the advantage of less occurrence of drying cracks, but
When used as a pallet deck board, the mechanical strength is poor, and the coating film is easily worn away by friction with loaded cargo. Furthermore, depending on the type of rubber latex or emulsion comb or resin, there are problems such as poor coating force and poor chemical properties.

The present invention aims to provide a wood surface treatment method that completely eliminates the above-mentioned drawbacks of conventional rubber latex or resin aqueous emulsions and can form a coating film on the surface that is highly abrasion resistant and chemical resistant. The gist of this is that an aqueous dispersion containing rubber latex, a vulcanizing agent, and an aqueous resin emulsion is applied to the wood surface, dried, and then heated to cause a vulcanization reaction. , to form a coating film on the wood surface.

Wood to which the present invention can be applied include rice bran, lauan, teak, mahogany, cedar, and pine, and the shape of the wood is preferably a plate for pallet deck boards, but depending on the use, it may be prismatic. It may also be in the shape of a round bar. Generally, plate-shaped materials such as lauan, laminated wood, and rice cake are used as deck boards for pallets. The aqueous dispersion applied and impregnated onto the surface of the wood must contain at least rubber latex, a vulcanizing agent for vulcanizing the rubber in the rubber latex, and an aqueous resin emulsion.

In addition to natural rubber latex, nitrile rubber latex, and butyl rubber latex, examples of the above-mentioned rubber latex include
A rubbery copolymer of 25 to 5% by weight of aliphatic conjugated di-2F1 and other polymers, such as alkenyl aromatic monomers, ethylenically unsaturated J%L, and Aqueous dispersions can be used.

And as aliphatic conjugated diolefins, butadiene,
Isobutylene, chloroprene, etc., alkenyl aromatic monomers include styrene, divinylbenzene, methylstyrene, etc., and ethylenically unsaturated monomers include methyl acrylate, propyl acrylate, n-butyl acrylate, acrylic. t-butyl acid, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile, methacrylate trile, vinyl chloride, vinylidene chloride, vinyl acetate, acrylic acid, methacrylic acid/ethylene, etc., specifically, Styrene-butadiene copolymer latex (e.g. butadiene 33% by weight)
, copolymer latex consisting of 65% by weight of styrene and 2% by weight of acrylic acid), acrylonitrile-butadiene copolymer latex (e.g., 38% by weight of acrylonitrile, 1% by weight of acrylonitrile)
%, copolymer latex consisting of 62% by weight of Butashev), methyl methacrylate/butadiene copolymer latex (for example, copolymer latex consisting of 42% by weight of methyl methacrylate and 58% by weight of butadiene), and other polyisobutylene copolymers. Examples include synthetic rubber copolymers such as latex and polychloroprene copolymer latex.

Next, as the vulcanizing agent, sulfur, thioglycolic acid, dicumyl peroxide, quinone dioxime, maleic anhydride, zinc white, or methylolmelamine resin can be used. The amount of the vulcanizing agent added depends on the number of rubbery double bonds in the rubber latex, but it is usually 1 to 20% by weight, preferably 5 to 10% by weight of the solid content of the rubber latex. used in

Furthermore, the aqueous resin emulsion may be a homopolymer of the alkenyl aromatic monomer or ethylenically unsaturated monomer, a copolymer of two or more of these monomers, or a combination of these monomers and itaconic acid. An aqueous emulsion of a thermoplastic resin such as a copolymer with an unsaturated polybasic acid such as , maleic anhydride, or fumaric acid can be used. Specifically, c) vinyl acetate polymer emulsion, ethylene/vinyl acetate polymer emulsion,
Vinyl acetate copolymer emulsion, acrylic ester copolymer emulsion, styrene-0 acrylic ester copolymer emulsion, other acrylic ester/vinyl acetate copolymer emulsion, vinyl chloride polymer emulsion, vinyl chloride・Vinylidene chloride copolymer emulsion, styrene/n-butyl acrylate-
Examples include itaconic acid copolymer emulsion.

The rubber latex used in the present invention is heated after application and drying, and is useful for forming a coating film with high mechanical strength and a sliding effect, while the aqueous resin emulsion gives the coating film flexibility and Investigates #Ri impact resistance and weather resistance. However, if the blending ratio of rubber latex and aqueous resin emulsion is less than 3 based on the solid content weight ratio, the resulting coating film will be brittle and slippery against impact;
If it exceeds +1, the anti-slip effect will be sufficient, but the coating will be easily damaged and the weather resistance and adhesion to wood will deteriorate. Further, the concentration of the aqueous resin emulsion is 10 to 65% by weight, preferably 25 to 50% by weight in terms of solid content, and the minimum film forming temperature thereof is preferably 0 to 30°C from the viewpoint of drying properties.

When carrying out the present invention, in addition to the three main components of rubber latex, a vulcanizing agent, and an aqueous resin emulsion, titanium oxide, carbon blank, pigments such as valves, clay, fillers such as calcium carbonate, and leveling agents are used. , ultraviolet absorbers, etc. may be blended into the aqueous dispersion consisting of the above three main components, and methods for coating and impregnating the surface of the wood with this aqueous dispersion include dipping, roll, blade, and spray methods. These methods are selected depending on the shape of the wood and the amount of aqueous dispersion applied.

The amount of aqueous dispersion applied is 80~1000~ (solid content equivalent)
, preferably from 150 to 600°C, and the wood coated and impregnated with this aqueous dispersion is dried at 0 to 65°C, then heated to 100 to 170°C to perform a vulcanization reaction of the comb, and the wood surface is coated with Can form a continuous coating film. Wood with this coating formed on its surface has water resistance, impact resistance, weather resistance,
Because it has excellent abrasion resistance and high sliding friction, it is particularly effective when used as a de-push board for pallets.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 33 parts by weight of butadiene, 65 parts by weight of methyleph, 2 parts by weight of acrylic acid, 0.7 parts by weight of sodium persulfate, 100 parts by weight of ion-exchanged water, 1.0 parts by weight of sodium dodecybenzenesulfonate, and -・Dodecyl mercaptan 0.2
After emulsion copolymerizing the mixture in the heavy part in an autoclave at 80° C. for 6 hours, the pH was adjusted to 6.0 with caustic soda, and the solid content of the latex was adjusted to % by weight to obtain SBR latex. Separately, 52 parts by weight of styrene, 45 parts by weight of t-butyl acrylate, 3 parts by weight of itaconic acid, 7 parts by weight of dode.
Rubenzenesulfonic acid l@meter, persulfuric acid power') 15
A mixture of the nail part and 110 parts by weight of water was emulsion polymerized at 75°C for 2 hours and at 85°C for 3 hours to obtain a resin aqueous emulsion of about 48% by weight of styrene-t-butyl acrylate-itaconic acid copolymer. Obtained.

100 parts by weight of the aqueous resin emulsion of the above terpolymer, 100 parts by weight of the above SBR latex, and methylolmelamine resin gas Melamine M manufactured by Sumitomo Chemical ■ as a vulcanizing agent.
31F (trade name), 10 parts by weight of titanium oxide, and 0.05 parts by weight of carbon black were blended to prepare an aqueous dispersion having a minimum film forming temperature of about 18°C. Next, this aqueous dispersion was prepared into a mold with a wall thickness of 20+n+n, a length of 200 mm, and a width of 2
After applying the coating using a roll coater to form a coating film with a thickness of 300 microns on the force side of the lauan board of 001+II++, it was stored for 24 hours and dried in a constant temperature room at a temperature of 20°C and a humidity of 55RH%. , a coating film was formed on the entire surface of the lauan board, and the lauan board was heated at 130°C for 1 hour to form SB.
Vulcanization of R latex was performed. Then, the static friction coefficient of the coating film formed on the lauan board (: r x s z −
0606-1982 sliding test) was confirmed to be 0.65.

As mentioned above, a surface-treated lauan plate was used as a sample piece,
300 hours in a weather test machine (equivalent to one year of outdoor testing)
After storage for 900 hours (equivalent to 3 years of outdoor testing), the specimen was taken out and the appearance (paint film cracks,
(presence or absence of pinholes, presence or absence of warpage of lauan board), static friction coefficient, drop impact resistance (presence or absence of cracks in the coating film and lauan board when a sample piece is dropped from a height of 1 m onto the mortar surface), weather resistance After the test, the weight increase rate, etc. was determined by the water absorption test. The results are shown in Table 3 below, together with those of other examples of the present invention and comparative examples for the present invention.

Examples ■ and ■ and Comparative Examples 1 and ■ The types and amounts of Kono latex, vulcanizing agent, and aqueous resin emulsion were changed as shown in Table 1 below, and the vulcanization temperature and time were changed as shown in the same table. The rest was carried out in the same manner as in Example I to obtain a lauan plate having a coating film on the surface, and this was evaluated.

In addition, in Table 1, TSR0592
(Product name) is SBR Lovex manufactured by Japan Synthetic Rubber.
'Butakon ML-507' (trade name) is a mesyl methacrylate (42-fold)-phtadiene copolymer latex manufactured by IOI, and the EVA emulsion is vinyl acetate (40% by weight)-Eblene (60% by weight).
Aqueous resin emulsion prepared by adding 5 parts by weight of polyvinyl alcohol to a copolymer, Th, 4-Decoat T19U1
-1 (Product name) is a water-based emulsion paint manufactured by Nippon Paint ■.

Note that the car sickness increase rates shown in Tables 2 and 3 are based on the trial
The increase in Htt of sample No. 11 after being immersed in water at 5° C. for 24 hours and taken out is expressed as a 6-minute ratio.

The present invention is as described above, and as is clear from Tables 2 and 3, it has the advantage of being able to form an extremely excellent coating film on the surface of the irrigation system and significantly improving the durability of the irrigation system.Applicant: Mitsubishi Yuka Co., Ltd.

Claims (2)

[Claims] (1) After applying an aqueous dispersion containing rubber latex, a vulcanizing agent, and an aqueous resin emulsion to the wood surface, it is dried, and then heated to cause a vulcanization reaction to form a coating film on the wood surface. A method for surface treatment of wood, characterized by: (2) A method for surface treatment of a patented material, characterized in that the weight ratio of the solid content of the rubber latex in the aqueous dispersion and the solid content of the aqueous resin emulsion is V3 to h.