JPH0196079A - Coating of cementitious base material - Google Patents

Abstract

PURPOSE:To form a water-proof layer on the surface of a base material and to prevent crack generation in a lining layer by applying a specified isocyanate compd. to a cementitious base material as primer, then forming a lining layer with a specified unsatd. polyester resin. CONSTITUTION:An isocyanate compd. having <=200 mol.wt. per one NCO group is applied to a cementitious base material as primer. Then, chopped strand glass mat and an unsatd. polyester resin having >=0.5kg/mm<2> tensile strength, <=50kg/mm<2> modulus of tensile elasticity, and >=30% elongation, after curing, are used for the prepn. of a lining layer. By this method, firm bonding of the lining layer to the cementitious base material which has been treated with the isocyanate compd. is formed as curing of a compound body of the chopped strand glass mat with the unstad. polyester resin proceeds.

Description

[Detailed description of the invention] sail 1 yu 11 prefecture rihi 1 The present invention relates to a method for coating cement-based substrates.

Conventional technology Until now, cement-based base materials, which were said to have semi-permanent durability, and especially reinforced concrete structures, have been found to not have the performance that was expected, and the durability of concrete is being questioned once again. It's been a long time since that happened.

Initial deterioration phenomena of concrete structures, such as cracks and salt damage, and carbonation, which can be called aging phenomena, are very serious problems for concrete structures, which are characterized as durable consumer materials.

The state of deterioration of concrete is greatly affected by the environmental conditions in which concrete is used and the quality of concrete.
It has recently been revealed that the deterioration mechanism of concrete structures is not determined by the deterioration of the concrete itself, but is controlled by the corrosion of the reinforcing steel.

On the other hand, the basic performance required of protective materials to prevent deterioration of concrete structures is based on the ``Guidelines for Salt Damage Countermeasures for Road Bridges (Draft)''.
・According to the same explanation, ■Prevents the intrusion of harmful substances from the outside, such as oxygen in the air, humidity, water such as rainwater, and chloride (chlorine ions), and ■Has sufficient adhesion to concrete. , it behaves as one with the concrete, has sufficient elongation ability, and can follow the slightest cracks.

Moreover, the surface of concrete is not simple (and this causes various problems because concrete is an inherently porous material and has considerable heterogeneity. Furthermore, the water content of concrete The condition has a great effect on the adhesive strength with the protective material, and even if the moisture content is specified to be 8% or less by a surface moisture meter, it is extremely difficult to keep it below 8%, and there may be some This is one of the necessary material properties as it can be applied even in the presence of moisture.

Several proposals have already been made as protective materials against the durability-inhibiting environmental factors that invade from the outside.

1. Protection by organic penetrating waterproofing agent 2. Protection by inorganic penetrating waterproofing agent 3. Coating protection by synthetic resin 4. Protection by resin mortar (polymer cement) or waterproof mortar 5. Protection by synthetic resin lining 1.2 The work is quite good, but because of the high moisture permeability (air permeability), the sustainability of the function is poor, and there are variations in concrete neutralization suppression, or there is almost no effect.

Coating No. 3 has the ability to prevent carbonation depending on the synthetic resin, and is effective through construction methods such as multi-layer spraying, and although it has adhesive strength, it lacks the ability to follow cracks in the concrete surface layer, and it is difficult to prevent protruding corners. As with flat areas, it is difficult to coat thickly on some corners (erra'), making it difficult to control the film thickness.

The organic/inorganic mortar in No. 4 has good adhesion, but as with No. 3, it requires skill and has a limited ability to follow cracks in the concrete surface layer.

The lining resin in No. 5 is Evokin-based, so its adhesive strength is excellent, but resin with a high elongation rate has poor water resistance, so when it gets wet, the adhesive strength deteriorates dramatically and it may peel off. Also, there is a problem in workability due to the high viscosity (3,000 cps or more).

The present inventors blocked durability-inhibiting factors such as water, moisture, oxygen, and chloride ions from entering from the outside of the cement base.
Moreover, as a result of intensive long-term research on countermeasures for the conflicting performance of maintaining adhesion to cement base materials and crack followability, we identified a penetrating 1-reactive sealer with excellent water resistance and alkali resistance. It was discovered that the method of lining an unsaturated polyester resin with a glass mat is extremely reliable, and based on this knowledge, the present invention was completed.

Means for Solving the Problems The present invention involves coating a cement base material with an isocyanate compound having a molecular weight of 200 or less per NCO group as a primer, and then applying a chopped strand glass mat and a cured product. The physical properties are tensile strength 0.5kg/mm”
The above describes a method for coating a cement base material, which is characterized in that a lining layer is formed using an unsaturated polyester resin having a tensile modulus of 50 kg/mm'' or less and a tensile elongation of 30% or more.

Examples of the cement base material in the present invention include concrete, mortar, slate, foamed concrete, calcium silicate board, 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 has active N in its molecule.
These are monomers having two or more CO groups, low molecular weight polymers derived therefrom, or mixtures thereof. If the isocyanate compound is in liquid form, 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 applied to the surface of a cementitious base material, it quickly penetrates deeply into the porous capillaries of the base material. It penetrates and diffuses into the capillary and immediately reacts with the water in the capillary, water-soluble bases of cement hydrate, and unstable unhydrated substances on the capillary wall to form a stable hydrophobic solid in the capillary. . As a result, the porous voids become lipophilic and are filled with stable, water-resistant solids.
The filled depth is proportional to the amount of coating, and the number of inner surfaces of the base material c
It extends to m.

Examples of isocyanate compounds used in the present invention include tolylene diisocyanate (2,472,6
=65/35), l=lylene diisocyanate (2,4
/2.6=80/20),) lylene diisocyanate (
2,4=100), diphenylmethane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane~
4,4'-diisocyanate.

Isocyanate monomers such as 2.4-4 lylene diisocyanate dimer, meta-xylene diisocyanate, hegyamethylene, 6-diisocyanate, and polyallyl polyisocyanate are mentioned.

When an isocyanate compound having a molecular weight per NCO group exceeding 200 is used, it is not good in terms of water resistance, adhesion to a protective material, etc.

When using an isocyanate compound dissolved in an organic solvent, the organic solvent should be one that does not react with the isocyanate group.
For example, aromatic hydrocarbons such as benzene and toluene, acetone, and methyl ethyl ketone.

Examples include ketones such as methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate, butyl acetate, and glycol ether esters, halogenated hydrocarbons such as dichloromethane, dichloroethane, and trichloroethylene, dimethylformamide, and isophorone. The amount of isocyanate compound used in the solution depends on the type of isocyanate compound and solvent, but is usually about 50
It is about 800g/Q. A catalyst may be added to the above solution if necessary.

The amount of isocyanate compound applied varies depending on the type of cement base material and surface condition, but it is usually about 200g/approx.
m" to about 500 g/m".

Application methods include, for example, spray application, one brush application,
Examples include roller brush painting.

After applying an isocyanate compound to the surface of the cement base material and curing it, a lining layer is created 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 unsaturated polyester and vinyl monomer. This unsaturated polyester is a thermosetting resin obtained by condensation polymerization or addition polymerization of an unsaturated dibasic acid and glycol or alkylene oxide, and a portion of the unsaturated acid may be replaced with a saturated dibasic acid. .

Examples of unsaturated dibasic acids include maleic anhydride, fumaric acid, and itaconic acid; examples of saturated dibasic acids include phthalic anhydride and isophthalic acid.

Examples of glycols include terephthalic acid and adipic acid, and examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol,
Examples of the alkylene oxide include dipropylene glycol, butylene glycol, and neopentyl glycol. Examples of the alkylene oxide include propylene oxide.

Examples of vinyl monomers include styrene, vinyltoluene, α-methylstyrene, and methyl methacrylate. 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 using these compounds, the resin that can be used in the present invention is a cured unsaturated polyester resin (hereinafter referred to as cured resin) with a tensile strength of 0.5 kg. /mm' or more, preferably 1.0kg7mm'' or more, tensile modulus 50kg
/mm! It is necessary to have a tensile elongation of preferably 30 kg/mm' or less and a tensile elongation of 30% or more, preferably 50% or more.

If the tensile strength and elongation are smaller than the above values, if cracks occur in the lined cement base material, the lining layer may not follow the cracks and may separate from the interface of the cement base material, or the lining layer may rupture. The protective function of the cementitious base material is impaired.

Here, the physical properties of the tree tie compound are determined by curing a 3 m/m thick cast plate at room temperature, then leaving it overnight at 60°C. A sample was prepared by further post-curing at 100°C for 3 hours, and the bending test was conducted according to JIS6911. The tensile test was also measured according to Jl5691■.

There are various types of glass fibers used as reinforcing materials.
The present invention uses chopped strand glass as a lining layer, which has sufficient adhesive strength, is resistant to delamination, has water resistance that does not cause drainage, and has constant tensile strength in all directions. A mat is used. Although glass cloth (Kuchinukihira IO) has great strength,
The strength is directional and the adhesive strength is poor. Chopped strand glass mats are also ideal for impregnating and defoaming unsaturated polyester resins.

The chopped strand glass mat is used in an appropriate amount, but usually about 450 g/m'' chopped strand glass mat is used.

The amount of resin used during lining is approximately 1-0 to 2.0 kg.
/ml11! That's about it. Further, the thickness of the lining layer is about 0.7 to 1.5 m/m.

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

If the lining layer is made in this way and left at room temperature, the composite of the unsaturated polyester resin and chopped strand glass mat in the lining layer will harden, and the lining layer and the isocyanate compound treated cement base material will harden. is firmly adhered.

Effects of the Invention According to the present invention, the isocyanate compound as a primer deeply penetrates and impregnates the cement base material to form a waterproof layer on the surface layer of the base material, suppressing the elution of alkaline components inside the base material, It has the function of maintaining adhesive strength.

Furthermore, the lining layer made of a specific unsaturated polyester resin with a low modulus of elasticity and high elongation is firmly adhered to the cement base material via an isocyanate compound, and has high zero span strength. Therefore, it has good followability when the base material cracks, and cracks do not occur in the lining layer.

The method of the present invention is seamless lining using chopped strand glass mat, and there is no problem in working even with complex shapes. It is possible to work not only on the outside surfaces of the walls (e.g.), but also on the ceiling surfaces. It is also an excellent method at relatively low cost.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Example I J 15A5304 designated commercial sidewalk board concrete was coated with an isocyanate compound and lined with an unsaturated polyester resin, left to harden for one week at room temperature, and then immersed in water at room temperature. After one year of immersion, it was taken out and the adhesive strength and state of the lining layer was examined.

The isocyanate compound used was manufactured by Takeda Pharmaceutical Co., Ltd.
Takenate 300C (molecular weight per NCO group: 135) and Takenate P-402 (molecular weight per NCO group: 389).

The unsaturated polyester resin of the lining layer is Polymer 8414AP manufactured by Takeda Pharmaceutical Company Limited.

In addition, the physical properties of the cured resin of 8414AP include tensile strength of 1
．． 0kg/mm", tensile modulus of elasticity 20kg/mm".

The tensile elongation was 50%. The thickness of the FRP lining layer was approximately 1 m/m.

According to the test results (table), No. 2, based on the fracture state of the sample and retention of adhesive strength. The lining of No. 4, a combination of an isocyanate compound having a molecular weight per NCO group of 200 or less and chopped strand glass mat, was good.

Example 2 A JISA5307 commercially available concrete commercially available concrete boundary block surface (150 x 600 mm) was coated under the conditions shown in Table 2. After being left at room temperature for 7 days, the lining layer was placed on the tension side (lower surface) and JISA5307.6
A bending test was conducted using the method.

The results are shown in Table-2.

Polymer 35I7 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”, tensile modulus 10, kg/
mm2. The tensile elongation was 23%. If the adhesive strength of the lining layer is small, the fracture location due to bending will be different from the fracture location of the concrete base material. In other words, the concrete and the lining layer do not behave as one, indicating that the lining layer does not have sufficient followability when cracks occur in the concrete.

From the test results, sample No. 2, i.e. Polymer 8
It was found that the combination of 414 and chopped strand glass mat was the best.

Example 3 After cutting an asbestos board (5 mm thick), the two cut surfaces were brought together and a coating was applied thereon. After curing, a tensile test was conducted using this sample to estimate the zero span strength. Among the resins used, Polymer 6305 is an unsaturated polyester resin manufactured by Shikinichi Yakuhin Kogyo Co., Ltd., and the physical properties of the cured resin are as follows: tensile strength 7.2 kg/mm', tensile modulus 330 kg/++++++ .

The tensile elongation was 4.3%.

The test results are shown in Table-3. Fracture condition of sample.

In terms of elongation at break, No. 1, No. 5, ie, the combination of Polymer 8414 and chopped strand glass mat, were the best.

Example 4 Isocyanate compound A used in Example 1 was applied with a brush to an outdoor cast concrete surface at a rate of 250 g/m'', and after being left for 3 hours, one layer of chopped strand glass mat and polyester resin were applied. The ratio of resin to glass was 77:23 (weight ratio), and Polymer 8414 and Polymer 3276 were used as the resins.

The area of the lining is 10 m long and 0.3 m wide.

During installation, the lengthwise edge of the mat was bent at right angles along the edge of the groove, while the other edge remained flat to allow movement of the lining layer during shrinkage.

Polymer 3276 used here is manufactured by Shikinichi Yakuhin Kogyo Co., Ltd.
The physical properties of the cured resin are tensile strength 6.1 kg/n+m' and tensile modulus 30.
0 kg/mm” and elongation rate of 2.9%.

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

On the other hand, there are no abnormalities such as peeling on the construction surface of 8414 even after three years.

(Margin below) Table 2 [Cracks due to lining disease and self-cleaning properties determined by bending test] A...Takenate 300C (solid content 15%) S.
... Polymer 8414 I] ... Polymer 3517 M ... Chikopdo strand glass mat (450g
/al') C...Glass cloth plain weave (300g/m) Relative deflection at maximum load (XIO-3mm) Relative deflection when approximately 50Kgf is reached after maximum load (X10-' mm) Calculated value from the final deflection A...The lining layer breaks at the same point as the concrete breakage point...The lining layer peels off and breaks at a different point from the concrete.

Claims (1)

[Claims] Molecular weight per NCO group in cement base material is 200
The following isocyanate compound is applied as a primer, and the physical properties of the chopped strand glass mat and cured product are tensile strength of 0.5 kg/mm^2 or more, tensile modulus of 50 kg/mm^2 or less, and tensile elongation of 30%.
A method for coating a cement base material, characterized by forming a lining layer using the above unsaturated polyester resin.