JPH0657812B2 - Moisture absorption / exhaust paint for wood - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a moisture-exhausting / moisture-absorbing paint for wood, which is used for wooden walls, floors, columns, furniture, crafts, miscellaneous goods, and the like.

[Conventional technology]

Conventional wood paints are mainly characterized by waterproofness, stain resistance, and surface protection, and in addition, there are only those that have combined corrosion resistance, worm corrosion resistance, etc. by using a chemical together.

[Problems to be solved by the invention]

Therefore, when a conventional paint of this type is applied or impregnated, various properties such as waterproofness are uniformly imparted and exhibited without taking into consideration the inherent properties of the woody material as the article to be coated. However, there is a problem that the function of adjusting the specific humidity of wood, that is, the so-called moisture absorption / exhaust function, is almost lost by applying the paint.

That is, when examining the properties of moisture absorption / exhaust of wood, as is well known in unpainted wood products, there are problems such as dirt, discoloration, water absorption, and easy scratching, but in addition to this, since the moisture absorption / exhaust property becomes too large, A sudden change in water content appears as a dimensional change, and there is a problem that cracking and warping occur. On the other hand, in the case of coated wood products, on the contrary, the moisture absorption / exhaust properties are impaired, which causes the generation of dew condensation on the wall material and the like, which causes a difference in humidity between the front and back during single-sided coating and causes warping and the like.

Therefore, an object of the present invention is to provide a coating material for wood which has not only the function of a general non-moisture permeable wood coating material but also an appropriate moisture absorptive and desorptive property in view of properties peculiar to wood as an object to be coated. It is in.

[Means for solving problems]

In order to solve the above problems, the present invention uses a special polymer that can be molded into a non-porous film having high moisture permeability as a base vehicle, and if necessary, mixes other vehicle, an additive such as a pigment or a diluent. Adopted the configuration.

As the special polymer, in view of its unique application to wood, a breathable polyurethane polymer that has appropriate moisture permeability to the extent that it functions to absorb and discharge moisture and has the various properties required for a coating film is adopted. To be done. That is, JIS
A water vapor permeable polymer having a water vapor transmission rate of 1,500 (g / m ² · 24 hr / 15μ) or more as measured by the method specified in Z0208 is suitable. More specifically, the moisture permeable polymer has a water vapor permeability of 1500 (g / m ² · 24hr / 15) as measured by the method specified in JIS Z0208.
It is possible to use a polyester-based or polyether-based polyurethane polymer having a size of μ) or more. Especially for example,
As the polyester-based moisture-permeable urethane polymer, the polymer described in JP-A-61-9423 has a non-porous and good moisture permeability, and also has a low water absorption swelling rate, and is excellent in terms of coating film durability and the like. There is. That is, it is a polyurethane polymer obtained by reacting a polyester polyol and an organic polyisocyanate in the presence of a chain extender. The polyester polyol has a polyoxyethylene content of 17 to 70% and a molecular weight of 500 to 3000. The molecular weight of polyethylene glycol, which is an oxyethylene unit, is 200.
It is a moisture-permeable polyurethane polymer having a polyoxyethylene content of 15 to 62% in the final polyurethane polymer. In particular, the polyester polyol is most preferably a moisture-permeable polyurethane polymer obtained by reacting polyethylene glycol and an organic dicarboxylic acid alone or a mixture of an organic dicarboxylic acid and ε-caprolactone and / or a short chain polyol.

As the polyether-based moisture-permeable urethane polymer, for example, the following, like the polyester-based polymer described above, has appropriate moisture-permeability as a lumber paint, and is excellent in terms of coating film strength as well as general paint properties. It is preferable in that it has. That is, polyethylene glycol having an average molecular weight of 200 to 600 and ethylene oxide adduct with bisphenol at both terminals or C = 3 having an average molecular weight of 500 to 3000.
Using the above polyalkyl ether polyol as a base polyol, and in the range of the polyethylene glycol content of the base polyol is 20 to 100%, polyisocyanate is reacted, and a chain extender is used if necessary,
The obtained polymer has an ethylene oxide content of 15 to 60.
It is a polyurethane polymer which has excellent properties such as high moisture permeability, low swelling property and toughness in a composition in the range of%, and can be formed into a non-porous film. Especially, the moisture vapor transmission rate is 150
0g / m ² · 24hr./20μ or more, swelling rate 10% or less, 1
A polyurethane polymer having a 00% modulus of 30 kg / cm ² or more is preferred.

As the resin containing the above-mentioned polymer as a main component, phthalic acid resin, acrylic resin, coumarone resin, nitrified cotton, drying oil (tung oil, linseed oil) and the like can be used. In addition, dyes, pigments, matting agents, preservatives, insect repellents, aging spinning agents,
Lubricants, fragrances, etc. may be mixed as additives. As the diluent, aromatic hydrocarbons, ketones, esters, alcohols and the like, and partially aliphatic hydrocarbons and the like can also be used. In particular, alcohols are preferable because they have good permeability to wood. As a coating method, various types such as brush, roller, impregnation, spraying, and boiling can be adopted.

[Action]

Since the present invention is as described above, by using a paint having a moisture permeable material, appropriate moisture absorption / exhaust properties are imparted to wood, and warpage due to a rapid change in water for the case of non-painting and cracking can be prevented, On the contrary, it has an excellent effect of preventing dew condensation and warping on a wall material such as a conventional paint.

〔Example〕

 The following polymers were synthesized as base vehicles.

First, polyethylene glycol (PEG molecular weight 400)
MEK blended in a proportion of 1 mol, bisphenol both-end ethylene oxide adduct (AE-II, manufactured by Meisei Chemical Co., Ltd.), and isophorone diisocyanate (IPDA) 2 mol.
A 30% solution was polymerized. The polymerization conditions are 65 ° C. and 5 hours. The liquid was 30% solid and had a viscosity of 5000 cps. The physical properties of the film are as follows: tensile strength 300 kg / cm ² , elongation 25%, moisture vapor transmission rate 1500 g / m ² , 24 hr. (15μ film). Subsequently, 100 g of this polymer was diluted with isopropyl alcohol (IPA) to prepare a paint having a solid content of 10%.

Next, in order to examine the coating film performance of the paints of such Examples, 5 m / m thick plywood (1
50 × 70) was coated twice at a rate of 100 g / m ² to prepare a sample. The cut was sealed with silicone sealant. For comparison, a general paint (Urethane resin varnish for wood floor made by Atom Chemical Paint) was used to prepare a sample according to a comparative example under the same conditions.

The moisture absorption / exhaust rates of the coating films of these samples were measured. The results are shown in Table 1. For the measurement method, first,
It was dried at 0 ° C. for 24 hours, its weight was measured, and then the moisture content was measured by allowing it to stand for 24 hours at a temperature of 40 ° C. and a humidity of 90% in order to check its hygroscopicity. Further, in order to measure the moisture drainage property, the sample was allowed to stand for 24 hours under the conditions of a temperature of 20 ° C. and a humidity of 55% to measure the water content.

As can be seen from Table 1, the coatings coated with the general coating have a considerably low moisture absorption amount, but the coating compositions of the examples show a moderate moisture absorption / exhaustion function close to that of the untreated coating.

Next, the dew condensation state was measured. That is, two atmospheres having a temperature of 0 ° C. and 20 ° C. and a humidity of 55%, which were partitioned by a glass plate, were created, and the sample was attached to the glass plate on the 20 ° C. side with a double-sided adhesive tape, and the condensed state of the coated surface was observed. The results are shown in Table 2.

As can be understood from Table 2, water drops were formed on the coating film surface in a short time with the general paint, but no water drop was observed even after 5 hours, and the moisture absorption / exhaust function was confirmed.

Further, the coating properties other than the moisture absorption / exhaust property were tested. The results are shown in Table 3.

[Advantages of the Invention] As described above, the present invention pays particular attention to the moisture absorption / exhaust characteristics inherent in the properties of wood, and adopts a special structure in which such characteristics are sufficiently taken into consideration to prevent warpage, cracking, and dew condensation. In addition, it was possible to provide a paint for wood, which has an extremely large moisture absorption / exhaust property and contributes to the relevant technical field, and which also has general paint characteristics.

Claims (1)

[Claims] 1. The water vapor permeability of the film measured by the method specified in JIS Z0208 is 1500 (g / m ² · 24 hr / 15μ).
A moisture-absorbing / moisture-absorbing coating material for wood comprising the above-mentioned moisture-permeable polyurethane polymer as a base vehicle, and if necessary, a phthalic acid resin or other vehicle, additives such as pigments, and diluents such as alcohol.