JP2565723B2 - Cement-based base material coating method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for coating a cement-based substrate.

Conventional technology Cementitious base materials, which have been said to have semi-permanent durability until now, have become clear that the performance of concrete, especially reinforced concrete structures, is not as high as expected. It's been a long time since I was done.

The initial deterioration phenomenon of concrete structures, which is seen in cracking and salt damage, and the neutralization, which can be called aging phenomenon, are very serious problems for concrete structures that have characteristics as durable consumer materials.

The deterioration condition of concrete is greatly affected by the environmental conditions in which the concrete is used and the quality of the concrete, but the deterioration mechanism of the concrete structure, which was recently revealed, is not determined by the deterioration of the concrete itself, It is said to be dominated by corrosion.

On the other hand, the basic performance required for protective materials as a measure against deterioration of concrete structures is that oxygen, humidity, moisture such as rainwater and chloride in the air are according to "Guideline for Countermeasures against Salt Damage of Road Bridges (Draft) -Commentary". Prevents invasion of harmful substances such as (chlorine ions) from the outside, has sufficient adhesion to concrete, behaves as one with concrete, has sufficient elongation ability, and follows a few cracks It is to be.

Also, the surface of concrete is not simple, and what causes various problems is that concrete is a porous material in nature and has considerable heterogeneity. Moreover, the water content of concrete has a great influence on the adhesive strength with the protective material, and the water content measured by the surface moisture meter is 8%.
Even if it is specified as below, it is unexpectedly difficult to set it to 8% or less, and it is one of the necessary conditions as a material property that construction can be performed in the presence of a small amount of water.

Several proposals have already been made as a protective material against the environmental factors that impair durability such as those mentioned above.

1. Protection with organic penetrating waterproofing agent 2. Protection with inorganic penetrating waterproofing agent 3. Coating protection with synthetic resin 4. Protection with resin mortar (polymer cement) or waterproof mortar 5. Protection with synthetic resin lining 1,2 However, since it has a high moisture permeability (breathability), its function is poor in sustainability, and there is variation in neutralization of concrete, or little effect is observed.

Depending on the synthetic resin, the coating of 3 has the ability to prevent neutralization, and it has exerted its function by devising the construction method such as multi-layer spraying. Although it has adhesiveness, it does not have the ability to follow the cracks of the concrete surface layer, As with the flat portion, it is difficult to apply a thick coating to the corner portion (edge), and there is a problem in film thickness management.

Although the organic / inorganic mortar of No. 4 has a good adhesive force, there is a limit to the crack followability of the concrete surface layer similarly in the work with skill.

Since the lining resin of No. 5 is an epoxy resin, its adhesive strength is outstanding, but when it becomes a wet state due to poor water resistance when it becomes a resin with elongation, the adhesive strength deteriorates extremely and peels off. Also, there is a problem in workability due to the high viscosity (3,000 cps. Or more).

Problems to be Solved by the Invention The present inventors
As a result of intensive studies over a long period of time, measures against the conflicting performance of blocking the durability factors such as moisture, oxygen, and chlorine ions, while maintaining the adhesive strength with the cement-based base material, while maintaining the adhesive strength It was found that the method of lining a specific unsaturated polyester resin with a glass mat for a water-resistant and alkali-resistant permeable and reactive sealer is extremely reliable, and based on this finding, the present invention was completed. I arrived.

MEANS FOR SOLVING THE PROBLEMS The present invention is to apply an isocyanate compound having a molecular weight of 200 or less per NCO group as a primer to a cement-based base material, and then to improve the physical properties of a chopped strand glass mat and a cured product. The present invention relates to a method for coating a cement-based base material, which comprises forming a lining layer using an unsaturated polyester resin having a strength of 0.5 kg / mm ² or more, a tensile elastic modulus of 50 kg / mm ² or less, and a tensile elongation of 30% or more.

Examples of the cement-based base material in the present invention include concrete, mortar, slate, foam concrete,
Examples include calcium silicate board, calcium charcoal board, gypsum board, and asbestos board.

Examples of the primer used in the present invention include isocyanate compounds having a molecular weight of 200 or less per NCO group. This isocyanate compound is active NCO in the molecule
It is a monomer having two or more groups and a low molecular weight polymer derived therefrom or a mixture thereof. When the isocyanate compound is liquid, it can be used as it is, but when it is dissolved in an organic solvent and made into a solution, it has a low viscosity, and when it is applied to the surface of the cement-based substrate, it deeply and rapidly penetrates into the porous capillary of the substrate. Permeates and diffuses into the capillary and immediately reacts with water in the capillaries, water-soluble bases such as cement hydrate, and unstable unhydrated materials on the capillary wall to form hydrophobic stable solids in the capillaries. . As a result, the porous voids become oleophilic and are filled with a stable and water-resistant solid material, and the filled depth reaches a few cm of the inner surface of the substrate in proportion to the coating amount.

Examples of the isocyanate compound used in the present invention include, for example, tolylene diisocyanate (2,4 / 2,6 = 6,5
/ 35), Tolylene diisocyanate (2,4 / 2,6 = 80/2
0), tolylene diisocyanate (2,4 = 100), diphenylmethane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-
Isocyanate monomers such as tolylene diisocyanate dimer, metaxylene diisocyanate, hexamethylene-1,6-diisocyanate and polyallyl polyisocyanate can be mentioned.

When an isocyanate compound having a molecular weight of more than 200 per NCO group is used, it is not good in terms of water resistance and adhesiveness with a protective material.

When the isocyanate compound is used by dissolving it in an organic solvent, as the organic solvent, aromatic hydrocarbons such as benzene and toluene, which do not react with isocyanate groups, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, ethyl acetate, Examples include esters such as butyl acetate and glycol ether esters, halogenated hydrocarbons such as dichloromethane, dichloroethane, and trichloroethylene, dimethylformamide, and isophorone. The amount of the isocyanate compound used in the solution depends on the type of the isocyanate compound and the solvent, but is usually about 50 to 800 g /. You may add a catalyst to the said solution as needed.

The amount of isocyanate compound applied varies depending on the type and surface condition of the cement-based base material, but is usually about 200 g / m ²
It is about 500 g / m ² .

Examples of application means include spray application, brush application, and roller brush application.

Isocyanate compound is applied to the surface of cement-based substrate,
After curing, a lining layer is made using chopped strand glass mat and a specific unsaturated polyester resin.

The specific unsaturated polyester resin used in the present invention is a mixed solution of an unsaturated polyester and a vinyl monomer. This unsaturated polyester is a thermosetting type resin obtained by polycondensation or addition polymerization of unsaturated dibasic acid and glycol or alkylene oxide,
Part of the unsaturated acid may be replaced with a saturated dibasic acid.

Examples of unsaturated dibasic acids include maleic anhydride,
Fumaric acid, itaconic acid, etc. are the saturated dibasic acids,
For example, phthalic anhydride, isophthalic acid, terephthalic acid,
Adipic acid and the like, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol and the like, and alkylene oxides such as propylene oxide and the like.

Examples of the vinyl monomer include styrene, vinyltoluene, α-methylenestyrene, methylmethacrylate and the like. To this resin, a peroxide for curing at room temperature such as methyl ethyl ketone peroxide and a curing accelerator such as cobalt soap are added.

Among the unsaturated polyester resins obtained by using these compounds, as a resin that can be used in the present invention, the physical properties of the unsaturated polyester resin cured product (hereinafter referred to as resin cured) have a tensile strength of 0.5 kg / mm. ² or more, preferably 1.0
kg / mm ² or more, tensile elastic modulus 50 kg / mm ² or less, preferably 30
It is necessary to have kg / mm ² or less and tensile elongation of 30% or more, preferably 50% or more.

When the tensile strength and elongation are smaller than the above values and cracking occurs in the cement-based base material, the lining layer does not follow the cracking and peels from the interface of the cement-based base material, or the lining layer breaks. The protective function of the cement-based base material is impaired.

Here, the physical properties of the cured resin are as follows: a casting plate with a thickness of 3 m / m is cured at room temperature and left overnight, then at 60 ° C for 1 hour, then 100 ° C
A sample is prepared by post-curing for 3 hours at JIS 6911 for bending test and JIS 691 for tensile test.
Measured according to 1.

There are various types of glass fibers as a reinforcing material, but in the present invention, there is sufficient adhesive strength as a lining layer, delamination is less likely to occur, and there is water resistance that does not result in water (water), A chopped strand glass mat with constant tensile strength in all directions is used. Although the glass cloth (blanket plain weave) has high strength, it has directional strength and further has poor adhesive strength.
The chopped strand glass mat is ideal for impregnating and defoaming unsaturated polyester resin.

The chopped strand glass mat is used in an appropriate amount, but usually one chopped strand glass mat of about 450 g / m ² is used. The amount of resin used during lining is about 1.0 to 2.0 kg / mm ² . The thickness of the lining layer is about 0.7 to 1.5 m / m.

Examples of the lining means include means for applying a resin with a roller brush or spray and then impregnating and defoaming the resin with a roller or the like.

When the lining layer is formed in this way and left at room temperature, the composite of the unsaturated polyester resin and the chopped strand glass mat in the lining layer is cured and the lining layer and the cement compound-based substrate treated with the isocyanate compound are firm. Glued to.

EFFECT OF THE INVENTION According to the present invention, the isocyanate compound as a primer is deeply penetrated into the cement-based base material to form a body waterproof layer on the surface of the base material by impregnation, and the elution of the alkaline component inside the base material is suppressed, It has the function of maintaining the adhesive strength.

Further, the lining layer using a specific unsaturated polyester resin having a low elastic modulus and a high elongation rate is firmly bonded to the cement-based base material through an isocyanate compound,
Has high zero span strength. Therefore, the followability when the base material is cracked is good, and the lining layer is not cracked.

The method of the present invention is a seamless lining using a chopped strand glass mat, there is no problem in work even in a complicated shape, a construction using a cement-based substrate (eg,
It is possible to work not only on the outer surface of buildings, highways, bridges, floors, water tanks, etc., but also on the ceiling surface. It is also an excellent method at a relatively low cost.

 Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 A concrete commercial sidewalk board concrete according to JIS A5304 was coated with an isocyanate compound and lined with an unsaturated polyester resin, left to cure at room temperature for 1 week, and then immersed in water at room temperature. One year after the immersion, it was taken out and the adhesive strength and the adhesive state of the lining layer were examined.

The isocyanate compounds used were Takenate 300C (molecular weight per NCO group is 135) and Takenate P-402 (molecular weight per NCO group is 389) manufactured by Takeda Pharmaceutical Co., Ltd., unsaturated polyester for the lining layer. The resin is Polymer 8414AP manufactured by Takeda Pharmaceutical Company Limited.
The physical properties of the cured resin of 8414AP are as follows: Tensile strength 1.0 kg / mm
² , the tensile elastic modulus was 20 kg / mm ² , and the tensile elongation was 50%. FRP
The thickness of the lining layer was about 1 m / m.

From the results of the test (Table 1), from the broken state of the sample and the retention of the adhesive strength, No.2 and No.4, that is, the combination of the isocyanate compound having a molecular weight of 200 or less per NCO group and the chopped strand glass mat was selected. The lining was good.

Example 2 The surface (150 x 600 mm) in the longitudinal direction of JIS A5307 commercial concrete boundary block B was coated under the conditions shown in Table-2. After standing at room temperature for 7 days, a bending test was performed by the method of JIS A5307.6 with the lining layer on the tensile side (lower surface).

The results are shown in Table-2.

The polymer 3517 used for the lining is manufactured by Takeda Pharmaceutical Co., Ltd., and the physical properties of the cured resin are tensile strength 3.2 kg /
mm ² , tensile elastic modulus 104 kg / mm ² , and tensile elongation 23%.
When the adhesive strength of the lining layer is small, the breakage point due to bending differs from the breakage point of the concrete base material. That is, it shows that the concrete and the lining layer do not behave integrally, and the followability of the lining layer when the crack in the concrete occurs is not sufficient.

No. 2 sample from the test results, namely Polymer 8414
It turns out that the combination of and chopped strand glass mat is the best.

Example 3 After cutting an asbestos board (thickness of 5 mm), two cut surfaces were brought into contact with each other, and a coating treatment was performed thereon. After curing, a tensile test was performed using this sample to estimate the zero span strength. Among the resins used, Polymal 6305 is an unsaturated polyester resin manufactured by Takeda Pharmaceutical Co., Ltd. The physical properties of the cured resin are: tensile strength 7.2 kg / mm ² , tensile elastic modulus 330 kg /
mm ² and tensile elongation were 4.3%.

The test results are shown in Table-3. No. 1 and No. 5, that is, the combination of polymer 8414 and chopped strand glass mat was the best from the viewpoint of the breaking condition of the sample and the elongation at break.

Example 4 The isocyanate compound A used in Example 1 was brush-painted on the surface of the outdoor cast concrete at a rate of 250 g / m ² and 3
After standing for 1 hour, add chopped strand glass mat 1
The layer was lined with a polyester resin. The ratio of resin to glass is 77:23 (weight ratio), and the resin is polymeric 8
This was done using 414 and Polymer 3276. The lining area is 10m long and 0.3m wide.

At the time of construction, the lengthwise end of the mat was bent at a right angle along the edge of the groove, and the other end remained flat so that the lining layer could move during contraction. The polymer 3276 used here is an unsaturated polyester resin manufactured by Takeda Pharmaceutical Co., Ltd. The physical properties of the cured resin are specific tensile strength of 6.1 kg / mm ² , specific elastic modulus of 300 kg / mm ² , and elongation of 2.9%. Is.

As a result of observing the lining surface exposed to wind and rain, the lining layer using 3276, which has a large elastic modulus and a small elongation, peeled from the end of the flat surface 9 months after the construction.

On the other hand, the construction surface of 8414 has no abnormality such as peeling after 3 years.

Claims (1)

(57) [Claims] 1. A cement-based substrate is coated with an isocyanate compound having a molecular weight of 200 or less per NCO group as a primer, and then the physical properties of the chopped strand glass mat and the cured product are a tensile strength of 0.5 kg / mm ^2. As described above, a method for coating a cement-based substrate, which comprises forming a lining layer using an unsaturated polyester resin having a tensile elastic modulus of 50 kg / mm ² or less and a tensile elongation of 30% or more.