JP2000044892A - Alfa-cyanoacrylate adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-viscosity, gel-like α-cyano-acrylate adhesive composition, as it retains the merits of α-cyanoacrylate composition, for example, for example, the fast-setting properties and strong adhesion to a large variety of materials. SOLUTION: The objective α-cyanoacrylate adhesive composition includes (a) 100 pts.wt. of α-cyanoacrylate, (b) 3-20 pts.wt. of hydrophobic fine particles of silica that is surface-treated with hexamethylsilazane, (c) 6-12 pts.wt. of poly[alkyl (meth)acrylate] with a weight-average molecular weight of 300,000-500,000, (d) 0.01-0.5 pt.wt. of sulfur dioxide and (e) 0.01-5 pts.wt. of one or more kinds of accelerating agents selected from poly(alkylene glycol) di(meth) acrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an .alpha.-cyanoacrylate-based adhesive, and more particularly to an .alpha.-cyanoacrylate-based adhesive having relatively low fluidity and thixotropic properties even after application of the adhesive.

[0002]

2. Description of the Related Art In general, an instant adhesive containing α-cyanoacrylate as a main component has an excellent curing speed,
Because of its one-component properties and excellent adhesion to a wide range of adherend materials, it is used in a wide range of fields from industrial use to general household use. However, such an α-cyanoacrylate ester has an extremely low viscosity, so that when a porous material is adhered, there is a problem that the adhesive penetrates into such a material, making it difficult to adhere.

[0003] On the other hand, in order to improve this, fillers and the like are added to α-cyanoacrylate, and gel-like liquid properties have come to be marketed. This gel-like product has been established for use in applications such as vertical surfaces on which liquid drips, porous adhered surfaces that penetrate before bonding, and temporary fixing of parts that use a curing accelerator later. is there. As a prior art of these gel type, there is JP-B-63-37150. This uses silica powder surface-treated with polydimethylsiloxane and trialkoxyalkylsilane as a thixotropic agent, and is said to have excellent storage stability. Further, this prior art pointed out that silica powder surface-treated with hexamethyldisilazane has low thixotropic property and has a problem in storage stability.

[0004] Separately, Japanese Patent Application Laid-Open No. Sho 63-108010 proposes that the use of hydrophobic silica powder and the addition of crown ether or polyalkylene oxide prevent the precipitation of silica powder. In addition, JP-A-62-169878 and JP-A-63-97671 disclose:
An α-cyanoacrylate composition using silica powder surface-treated with hexamethyldisilazane has been proposed. Further, Japanese Patent Application Laid-Open No. 63-137979 discloses a proposal using silica and a polyol surface-treated with dimethylchlorosilane, and Japanese Patent Application Laid-Open No. 8-53651 discloses a poly (meth) acrylic acid having a weight average molecular weight of 100,000 to 300,000. An example is shown in which alkyl is used in combination with a thickening agent and a fast curing agent is used in combination with hydrophobic silica.

[0005]

In contrast to the above prior art, Japanese Patent Publication No. 37150/1988 discloses that silica powder treated with hexamethyldisilazane itself is not suitable for α-cyanoacrylate. Next, in a system to which an additive such as crown ether proposed in Japanese Patent Application Laid-Open No. 63-108010 is added, the viscosity tends to increase with time.

Next, the method of using hexamethyldisilazane pretreated in advance, which is proposed in JP-A-62-169878 or JP-A-63-97671, is complicated in the process and takes a very long time to manufacture. It is not a reasonable manufacturing method. Further, the method proposed in JP-A-63-137797 has a problem in storage stability,
It tends to separate over time.

Next, when using a thickener having a weight average molecular weight of 100,000 to 300,000 described in JP-A-8-53651,
Even so, the molecular weight of the thickener is still too low, so it is necessary to increase the addition amount, and there is a problem that the set time is delayed. Therefore, in the present invention, a curing accelerator is used to improve the quick-curing property, but if so, the storage stability may be impaired. Therefore, the object of the present invention is α-
An object of the present invention is to provide a gel-like α-cyanoacrylate adhesive composition having a high viscosity while maintaining the characteristics of the cyanoacrylate composition, that is, rapid curing properties and adhesiveness to a wide range of materials.

[0008]

According to the present invention, a) 100 parts by weight of α-cyanoacrylate; b) 3 to 20 parts by weight of hydrophobic particulate silica surface-treated with hexamethyldisilazane; 6 to 12 parts by weight of a polyalkyl (meth) acrylate having a weight average molecular weight of 300,000 to 500,000 as a tackifier; d) 0.01 to 0.5 parts by weight of sulfur dioxide; e) polyalkylene glycol di ( The above-mentioned problem has been solved by an α-cyanoacrylate adhesive composition containing 0.01 to 5 parts by weight of one or more curing accelerators selected from meth) acrylates. In other words, this patent combines the components described above,
It has been surprisingly found that a gel type instant adhesive composition having excellent properties and storage stability can be obtained.

Next, each element constituting the present invention will be described in detail. First, α-cyanoacrylate that can be used in the present invention is represented by the following formula: CH ₂ ＣC (CN) —COOR
Is an alkyl, alkenyl, aralkyl, having 20 or less carbon atoms.
Haloalkyl, cyclohexyl, aryl, alkoxyalkyl, etc.).
-Methyl, ethyl, chloroethyl of cyanoacrylic acid,
n-propyl, i-propyl, allyl, propargyl, n
-Butyl, i-butyl, methoxyethyl, ethoxyethyl, methoxyisopropyl, 2-ethylhexyl and the like. These α-cyanoacrylates are:
It is produced by a conventionally known method, for example, by depolymerizing a condensate of cyanoacetate and formaldehyde.

The hydrophobic particulate silica powder surface-treated with hexamethyldisilazane that can be used in the present invention refers to silica powder having an average particle size of about 5 to 20 nm before surface treatment, and hexamethyldisilazane. The amount of the silica powder treated on the surface was converted into a carbon content, and the average particle diameter was 5
2.6 to 5.0% by weight with respect to silica of about 9 to 9 nm, and 1.8 to 4.0% by weight with respect to silica having an average particle diameter of about 10 to 12 nm; For silica having an average particle diameter of 13 to 20 nm, 1.6 to 3.
It must be 0% by weight. If the treatment amount with hexamethyldisilazane is small for each average particle size, sufficient thixotropic property cannot be obtained, and if it is too large, the storage stability as an adhesive deteriorates. Specific examples of the silica powder that can be used in the present invention include Degussa R-
810S, RX-200, R-8 from Aerial Japan
12S, Cabotir TS-530 from Cabot Corporation, and the like.

Next, the poly (meth) used in the present invention
Alkyl acrylate is added to thicken α-cyanoacnolite. These alkyl poly (meth) acrylates are polymer compounds as described in JP-A-8-53651. For example, polyalkyl methacrylates include polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, In addition to the lower alkyl of polymethacrylic acid such as polybutyl methacrylate, copolymers of the alkyl (meth) acrylate used in the present invention with other methacrylates or acrylates may be mentioned. The esters of these copolymers may be used alone or in a combination of two or more. Specific examples include copolymers, terpolymers, tetramers, and the like. These polyalkyl acrylates need to have an average molecular weight of 300,000 to 500,000.
Preferred commercially available alkyl (meth) acrylates include, for example, Rohmtech's polymethyl methacrylate (weight-average molecular weight: 400,000 to 500,000).

When polyalkyl (meth) acrylate having a molecular weight of 300,000 or less is used, a large amount of addition is required to adjust the viscosity to 200 mPa · s or more. Cause a delay. Conversely, if a substance having a molecular weight of 500,000 or more is used,
Stringing occurs at a viscosity of 200 mPa · s. The addition amount of this polyalkyl acrylate is suitably 6 to 12 parts by weight based on 100 parts by weight of α-cyanoacrylate. If the amount is less than this, the thickening effect is not sufficient, and if it is too large, the viscosity becomes too high.

Examples of the stabilizer usable in the present invention include sulfur-containing compounds such as sulfur dioxide, sulfur trioxide, sulfur dioxide, and sulfonic acids such as paratoluenesulfonic acid and methanesulfonic acid. Particularly preferred. These stabilizers may be used in combination of two or more kinds. The amount of the stabilizer is 0.01 to 0.5 part by weight, more preferably 0.05 to 0.15 part by weight, based on 100 parts by weight of the cyanoacrylate monomer. If the amount is less than 0.01 part by weight, the storage stability is deteriorated, and if it exceeds 0.5, the polymerization rate during curing is reduced, and the physical properties of the cured product are adversely affected.

The present invention further provides, in addition to the above-mentioned stabilizers, conventionally known compounds such as NO ₂ , HCl, H ₃ P
O ₄ , acidic phosphate, carbon dioxide, boron trifluoride, ethers thereof, and the like may be used in combination. The amount added at that time is 0.01 to 0.5 part by weight based on 100 parts by weight of the cyanoacrylate monomer.

The curing accelerators that can be used in the present invention include:
Polyalkylene glycol di (meth) acrylates such as polyethylene glycol (meth) acrylate and polypropylene glycol (meth) acrylate can be used, but polyethylene glycol di (meth) acrylate is more preferable. The amount of the polymerization accelerator to be added is 0.01 to 10 parts by weight, more preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the cyanoacrylate monomer. Further, specific examples of polyethylene glycol di (meth) acrylate include the following formula (1)

[0016]

Embedded image

(N is not less than 20 and not more than 40) is suitable. When the number of n is 20 or less, the effect of the quick-curing property is small, and when the number is 41 or more, the solubility in α-cyanoacrylate is not good, so that it is not practical.

In the present invention, conventionally known curing accelerators can be used in addition to the above-mentioned curing accelerators. In particular,
Crown ethers such as 15-crown-5, 18-crown-6, silacrown ether, calixarene,
Polyalkylene oxide, polyalkylene glycol mono (meth) acrylate, polyalkylene glycol monoether mono (meth) acrylate, and the like.
If necessary, it can be added in the range of 0.01 to 2% by weight based on the cyano acrylate monomer. If the amount is outside the above range, the storage stability may be reduced or the promoting effect may not be obtained.

In the present invention, various additives conventionally known can be added. For example, a radical polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, t-butyl catechol, catechol, pyrogallol, a plasticizer such as dimethyl phthalate and dibutyl phthalate, and silica other than silica powder treated with hexamethyldisilazane Inorganics or fillers, including pigments (silica powder surface-treated with polydimethylsiloxane, trialkoxyalkylsilane, dimethylchlorosilane), pigments,
Colorants such as dyes, fragrances, solvents, strength improvers, thickeners, etc.
Depending on the purpose, the α-cyanoacrylate monomer can be appropriately added and blended within a range that does not impair the stability.

In the production procedure of the present invention, for example, after charging an α-cyanoacrylate monomer into a production vessel, adding a stabilizer and a radical inhibitor, stirring and dissolving, and slowly stirring the silica powder and the accelerator with stirring. The gel-like adhesive composition can be manufactured by adding and stirring for about 30 minutes until it is uniformly dispersed.

When silica powder is mixed in the system,
Polyalkyl (meth) acrylate (thickener) represented by poly (methyl methacrylate) is dissolved in α-cyanoacrylate in advance to avoid aggregation of silica powder during mixing and separation of silica powder over time. When the silica powder is added after thickening, the dispersibility is improved, the aggregation of the silica powders can be prevented, and the separation phenomenon over time is eliminated. At this time, the viscosity of the α-cyanoacrylate is
The pressure is preferably 200 to 600 mPa · s, and if it is 200 mPa or less, there is a risk of causing a separation phenomenon after production.
When the pressure is 0 mPa · s or more, the viscosity tends to increase with time, and the threading phenomenon tends to occur.

When the respective components of the present invention are mixed in the above-described order, impurities that adversely affect the α-cyanoacrylate contained in the silica powder treated with hexamethyldisilazane, such as ammonia and amine, are first removed. In addition, since a stabilizer such as sulfur dioxide mixed with α-cyanoacrylate blocks these, even if silica is subsequently added, the stability is not impaired.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLES 1-4 AND COMPARATIVE EXAMPLES 1-6 The α-cyanoacrylate adhesive compositions according to the present invention, Examples 1-4 and Comparative Examples 1-6 were produced with the formulations shown in Tables 1 and 2 below. did.

[0024]

[Table 1]

[0025]

[Table 2]

The manufacturing procedure is as follows. First, α-cyanoacrylate is collected in a stirring vessel, and appropriate amounts of hydroquinone and sulfur dioxide are added as stabilizers. Next, after adding a thickener (PMMA: polymethyl methacrylate) with stirring, the mixture is stirred at a temperature of 40 ° C to 70 ° C until dissolved. Next, after cooling to 40 ° C. or lower, a curing accelerator and various silica powders are added with stirring, and the mixture is stirred for 30 minutes. The results at this time are shown in Tables 3 and 4.

[0027]

[Table 3]

[0028]

[Table 4]

The types of silica powder used in Examples 1 to 4 and Comparative Examples 1 to 6 are as shown in Table 5.

[0030]

[Table 5]

[0031]

Examples 5 to 9 With the formulations shown in Table 6, adhesive compositions according to the present invention in which the kind of α-cyanoacrylate was changed, and Examples 5 to 9 were produced. Table 6 shows the results.

[0032]

[Table 6]

[0033]

Examples 10 and 11 and Comparative Examples 7 to 11 The adhesive compositions according to the present invention (Examples 10 and 11 and Comparative Example 7) were prepared by changing the type and amount of the curing accelerator in the formulations shown in Table 7. ~ 1
1) was manufactured. Table 7 shows the results.

[0034]

[Table 7]

[0035]

Example 12 and Comparative Examples 12 to 15 Adhesive compositions according to the present invention (Example 12 and Comparative Examples 12 to 15) were prepared according to the formulations shown in Table 8 except that the amount of the stabilizer was changed. Table 8 shows the results.

[0036]

[Table 8]

[0037]

Comparative Examples 16 to 20 Comparative examples 16 to 20 were prepared by changing the molecular weight and the amount of polyalkyl (meth) acrylate added according to the formulation shown in Table 9. Table 9 shows the results.

[0038]

[Table 9]

As described above, it can be seen that good results are obtained when silica powder treated with hexamethyldisilazane in a specific range is used. On the other hand, if the silica surface treatment amount of hexamethyldisilazane used is insufficient silica powder, the thixotropic property cannot be sufficiently exhibited after the production, and the viscosity is low, so that the gel-like composition is not complete. From the results of the 70 ° C. heating acceleration test, it can be seen that the viscosity increases with time. Furthermore, when silica powder having a large apparent specific gravity is used, separation and precipitation of silica are observed.

When an appropriate amount of a curing accelerator is added, the set time is relatively short, and the increase in viscosity in the 70 ° C. acceleration test is small. Also, when polyethylene glycol dimethacrylate is used, those having a low molecular weight do not have much effect of accelerating the curing rate, and those having a high molecular weight have a problem in solubility at the time of addition. In addition, crown ether and polyethylene glycol monomethacrylate,
Although the effect of accelerating hardening can be obtained, thickening after 70 ° C. acceleration is severe.

When silica powder treated with hexamethyldisilazane in a specific range is used, the viscosity increase after 70 ° C. acceleration is greater than when other silica powder is used. Further, it can be seen that when a stabilizer other than sulfur dioxide is used, the effect of stabilizing the composition of the present invention is hardly obtained.

When the amount of the poly (meth) acrylate is larger than the specified amount, stringing occurs. When the amount is small, separation of silica powder occurs after 70 ° C. acceleration. Also,
If the polyalkyl (meth) acrylate has a large molecular weight, stringing tends to occur, and if the molecular weight is small, separation of silica powder occurs.

[0043]

The composition of the present invention can be used as a gel-like instant adhesive having a moderate viscosity and thixotropic properties and excellent adhesive performance, especially a high curing speed and excellent storage stability. It can be used in a wide range of fields from general household use to industrial use as a gel-like instant adhesive that has solved conventional problems such as poor curing, gelation during storage, stringing and the like.

Claims (4)

[Claims] 1. An α-cyanoacrylate-based adhesive composition containing the following a) to e) as main components. a) 100 parts by weight of α-cyanoacrylate b) 1 to 20 parts by weight of hydrophobic fine-particle silica powder surface-treated with hexamethyldisilazane c) 5 to 20 alkyl polyacrylates having a weight average molecular weight of 300,000 to 500,000 Parts by weight d) 0.01 to 0.5 parts by weight of sulfur dioxide e) 0.01 to 5 parts by weight of one or more curing accelerators selected from polyalkylene glycol di (meth) acrylates 2. The silica powder surface-treated with hexamethylene disilazane, wherein the silica powder before the surface treatment has an average particle size of about 5 to 20 nm, and the surface of the silica powder is treated with hexamethyldisilazane. When the amount is converted into a carbon content, the content is 2.6 to 5.0% by weight with respect to the silica powder having an average particle size of 5 to 9 nm, and the silica powder having an average particle size of about 10 to 12 nm is used. For 1.8 to
4.0% by weight, and the average particle size is 13 to 20 n.
The α-cyanoacrylate adhesive composition according to claim 1, wherein the amount is 1.6 to 3.0% by weight based on the silica powder of m. 3. The α according to claim 1, wherein said polyalkyl acrylate is polymethyl (meth) acrylate.
-A cyanoacrylate adhesive composition. 4. The α-cyanoacrylate adhesive composition according to claim 1, wherein the polyalkylene glycol di (meth) acrylate has the following formula (1). Embedded image (N is 20 or more and 40 or less.)