JPS6026435B2 - α↓-How to apply primer for cyanoacrylate adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of applying a primer to a surface to be adhered prior to adhesion with a Q-cyanoacrylate adhesive.

-R represents a saturated or unsaturated aliphatic group, alicyclic group, or aromatic group.

) Q-cyanoacrylate (hereinafter referred to as ACA) immediately undergoes anionic polymerization due to moisture in the atmosphere and on the surface of the adhered layer, forming a strong two-dimensional linear body within a few seconds to a few minutes. This linear polymer is widely used as an instant adhesive because it forms strong hydrogen bonds with the surface of the layer to be adhered.

However, ACA has an extremely low viscosity, and while this property has the advantage of improving its spread on flat surfaces such as metals and glass, it becomes a factor that prevents good adhesion to porous articles. Furthermore, even if the surface is smooth and has been sealed, such as the surface of wood that has been sanded with paper, if the surface to be adhered is acidic, sufficient adhesion will not be achieved. One suggestion to address the above drawbacks is to add a synthetic polymer that is compatible with ACA.

However, such additives are essentially foreign substances,
This has the disadvantage of weakening the adhesive strength of ACA or shortening its shelf life. Moreover, it has no effect on improving adhesion to acidic surfaces. For this reason, the use of gaseous curing accelerators such as volatile amines or liquid curing accelerators prepared by dissolving organic amines, organometallic compounds, and other basic substances in a solvent has recently been proposed, but in the case of the former, Most of the gas used is wasted and evaporates, resulting in extremely large losses. In addition, since gas is invisible to the naked eye, unevenness tends to occur when the injection area is wide. Furthermore, the influence of the vaporized gas on the health of workers cannot be ignored. On the other hand, in the latter case, it is necessary to wait for the solvent to dry after applying the accelerator solution to the surface to be bonded.
It is difficult to apply to assembly line work. Moreover, the dry solvent used here is harmful to the human body, and there is a risk of inhalation, and there is also a great risk of fire and explosion. Furthermore, curing accelerators such as amines are also generally harmful to the human body. In addition to the above-mentioned gaseous or liquid curing accelerators, a solid undercoat (primer) prepared by mixing and molding a magnetization accelerator powder and a filler powder has also been proposed.

This primer is, for example, a chalk-like rod-shaped body,
It is used by rubbing it on the surface to be adhered. However, it takes a lot of time to apply to a large area, and it cannot be applied to minute concave areas. Therefore, a method has been used in which the primer is applied in spots to a part of the part to be adhered, rather than to the entire surface, to cause rapid curing, and the remaining part is gradually cured, but this method is not suitable for wood, etc. In addition to the significant delay in curing due to the reasons mentioned above, generally unsatisfactory results were obtained due to the penetration of ACA into the interior of the wood. The present invention improves the above-mentioned drawbacks of solid primers and significantly improves the coating efficiency of the primer.
The purpose is to enable application to the side surfaces of protrusions, etc., and to obtain adhesive states having various characteristics as described below, if desired. The gist of the present invention is that the primer for the ACA adhesive is applied in powder form to the surface to be adhered by placing it in a porous bag or using a puff.

The term "primer" here basically refers to a curing accelerator for ACA, but for the purposes of the invention, it is not limited thereto, and may also include a mere filler, a filler, an impact-resistant agent, a hardening agent, and a conductive agent. , release agents, softeners, etc. Of course, these various primer substances may be used in combination as necessary. The above various primers are preferably made into fine powder (usually 100 mesh or less, preferably 20 mesh or less).
0 mesh or less) in a porous bag or container, and is applied to the surface to be adhered by tapping or rubbing it with a puff.

Suitable porous bags are thin, twisted woven bags made of natural or synthetic fibers, or flat bags made of non-woven fabric, but of course they do not have to be flat. It is convenient if the bag is provided with a finger strap like those found on commercially available cosmetic puffs. In any case, the primer application work using this method is extremely efficient, and in an experiment conducted by the inventor, it was possible to apply a primer on a square plywood board of 1 x lm using a bag of primer of 8 x 6 & force x 1 skin. The time required to apply the sand was on average about 1 minute and 3 times, which is less than 1/7 of the time required when using a chalk-like solid primer, and there was no uneven application as seen with the latter. almost never occurred. Furthermore, the primer scatters from the bag or puff in the form of particles and reliably adheres to the inside of minute concavities or the corners of convex portions, so that the adhesive strength is relatively improved. According to the method of the present invention, adhesion can be accelerated by selecting the type of brimer, or the adhesion can be completed by sealing the supported surface, or various properties can be imparted to the adhesive layer.

These blimmer substances are generally classified as follows. Curing accelerator: Any agent that initiates or accelerates the anionic polymerization of ACA can be used as a curing accelerator. The main curing accelerators are as follows. (A-1) Alkali metal or alkali metal hydroxide: sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide, etc.

Barium hydroxide can also be used, but should be avoided as it is highly toxic.

(A-2) Salts of alkali metals or alkali metals and other metals: soda carbonate, potassium carbonate, sodium bicarbonate IJ
um, basic magnesium carbonate, sodium borate, tribasic calcium phosphate, tribasic magnesium phosphate, sodium silicate (water glass), basic lead carbonate, etc.

(A-3) Alkali metal or alkali metal halide: sodium chloride, potassium chloride, calcium chloride, etc.

(A-4) Metal oxides: magnesium oxide, zinc oxide, etc.

(A-5) Amines: lower aliphatic amines, lower alkanolamines, aromatic, alicyclic amines, araliphatic amines, etc.

(A-6) Acid amides: lower aliphatic acid amides (formamide, acetamide, dimethylacetamide, malonamide, etc.) (A-7) Nitrogen-containing heterocompounds: pyridine, piveridine, morpholine, piperazine, etc.

(A-8) Organic acid salts of alkali metals or alkali metals or polymers thereof: sodium higher alkylbenzenesulfonate, sodium formate, sodium acetate, calcium acetate, acrylic acid or sodium polyacrylate, etc.

(A-9) Quaternary ammonium compound: cetyldimethylammonium chloride, alkylpyridinium halide, etc.

(A-10) Metal alcoholates: sodium ethylate, potassium methylate, etc.

B) Eye-filling agent: An eye-filling agent that, when applied to a surface to be adhered, has the effect of filling and flattening holes, cracks, gaps, etc. existing on the surface, is generally used as a filler.

Most mineral powders are suitable for this purpose, but acidic powders,
Those with too low specific gravity, those that are toxic, and those that corrode or alter the surface to be adhered are not preferred. Below are examples of fillers that are considered suitable. Calcium carbonate, calcium sulfate, silica, titanium oxide, alumina, calcium sulfite, carbon black, glass, diatomite, bentonite, aluminum hydroxide, etc.

Note that some fillers also act as curing accelerators for ACA, and their use not only simplifies the formulation of the primer, but also increases the concentration of the curing accelerator in the primer. So it's convenient.

Examples of suitable substances that have both curing accelerating and sealing properties include the following. Calcium hydroxide, magnesium hydroxide, calcium phosphate, magnesium phosphate, magnesium carbonate, basic magnesium carbonate, magnesium oxide, zinc oxide, sodium silicate, basic lead carbonate, sodium carboxymethyl cellulose,
Sodium alginate Incidentally, the inventors have discovered that the buds of grains, such as pork buds of rice sugar, have an excellent hardening accelerating ability in addition to the sealing ability.

In addition to being completely non-toxic, the spout has the property of adhering to the coated surface and has the effect of inhibiting the penetration of ACA, so it is suitable as a primer for wood and the like. In addition, among the curing accelerators belonging to the above A-5 and A-7 groups, there are those that are liquid themselves at room temperature, and these include, for example, silica,
It is necessary to adsorb it to an adsorbent filler such as diatomite, alumina, or carbon black. 'C} Hardening agents: Aluminum, copper, iron, emery powder, carborundum, etc.: These increase the hardness of the adhesive layer, so they are used when high mechanical strength, abrasion resistance, etc. are desired for the adhesive eyebrows. However, it may also be used to increase the adhesive film hardness of ACAs that form relatively flexible films, such as butyl Q-cyanoacrylate.

(2) Filler: All of the fillers mentioned above can be used as fillers, but fine particles of plastic, such as polymethyl methacrylate, polystyrene, etc., are advantageously used to impart transparency to the adhesive layer.

'E) Impact resistance agent: Fine powder of elastic rubber, polyurethane elastomer, etc. gives impact resistance and flexibility to the adhesive layer, and
It has the effect of greatly improving the stiffness of the adhesive layer, which is considered to be a drawback of CA.

[R Conductive agent: Since the fine powders of copper, aluminum, etc. described above impart conductivity to the adhesive layer, adhesion using these as a primer is useful as a substitute for solder.

Furthermore, if iron powder is used instead of steel powder or the like, the object to be adhered can be weakly heated using Joule heat. 'q Release agent: wood, starch, soluble starch, gelatin, sodium alginate, etc.

Wood flour weakens the adhesive strength, and starch, texturin,
Soluble starch, gelatin, and sodium alginate dissolve when immersed in water or boiled, so they are useful when using ACA for purposes such as temporary adhesion. Note that blowing agents such as ammonium carbonate can also be used in the same manner. As described above, the present invention dramatically improves the efficiency of coating work of primer for ACA adhesive, and at the same time, it is possible to impart various physical and chemical properties to the adhesive layer. This has the significance of significantly expanding the range of application of the agent.

The mode of carrying out the invention will be described below with reference to Examples. However, it is needless to say that the examples are merely for illustrative purposes, and
It is not intended to limit the spirit of invention. Example 1 Fine zinc oxide powder (200 mesh) and calcium carbonate fine powder (200 mesh) were mixed in equal amounts and placed in a non-woven fabric bag (8 bags x 6 bags x 1 bag). It was applied to one side of a square lauan veneer the size of a desk using a combination of tapping and rubbing.

The test was repeated 1q times and the average time required was measured. Items with uneven coating that are visible to the naked eye will be rejected. As a control, add 200 g of the above mixed powder for 10 g.
% polyvinyl alcohol aqueous solution, warm-kneaded, molded in a chalk mold, and air-dried for 3 days, and the same test was conducted using a chalk-like primer obtained.

The results were as shown in Table 1 below. As shown in Table 1, that is, the above table, in the control method using a chalky primer,
It took more than seven times as long as the present invention, and moreover, half of the tests were rejected.

The results of this experiment show that the present invention is particularly effective when applying a primer to a large surface to be adhered.
Examples 2 to 14 Fine rice bran powder (200 mesh) was mixed with 5 × 5 × 0.5
Place it in a skin-sized non-woven fabric bag and apply it to the adhered surface of the following adhered materials in the same manner as in the previous example, then apply and adhere ACA (R = ethyl), and check the set time and tensile strength. It was measured.

The results are shown in Table 2 below. Table 2 *Base material destruction Rudder base - Part As mentioned above, the invention significantly streamlines the blimmer treatment of bonded materials and at the same time increases the treatment effect, so it is possible to expand the scope of application of Q-cyanoacrylate. has a remarkable effect.

Claims (1)

[Claims] 1. A method for applying a primer for an α-cyanoacrylate adhesive, in which the primer for an α-cyanoacrylate adhesive is placed in powder form in a porous bag or applied to a surface to be adhered using a puff.