JP2568840B2 - α-cyanoacrylate adhesive composition - Google Patents

Description

The present invention relates to an α-cyanoacrylate-based adhesive,
More specifically, the present invention relates to an adhesive containing a thixotropic agent.

[Conventional technology]

Hydrophobic fine-particle silica surface-treated with a silicon compound such as polydimethylsiloxane, trialkoxyalkylsilane, hexamethyldisilazane, etc. is used as a thixotropic agent in an α-cyanoacrylate ester monomer (hereinafter referred to as α-cyanoacrylate). Techniques for blending to obtain a thixotropic paste adhesive composition are known.

[Problems to be solved by the invention]

The present inventor did not use hydrophobic particulate silica at all as a thixotropic agent, and developed an α-cyanoacrylate-based paste-like adhesive composition containing a completely new thixotropic agent different from this, and has conventionally developed Has been conducting research since. Accordingly, a problem to be solved by the present invention is to develop a new thixotropic agent for use in this kind of α-cyanoacrylate-based paste adhesive composition.

[Means for Solving the Problems] This problem is solved by using acetylated hydroxypropyl cellulose having an acetyl group content of 7% or more as a thixotropic agent.

The present inventor has been studying the use of acetylated hydroxypropyl cellulose (hereinafter abbreviated as AC-HPC) as a thixotropic agent for α-cyanoacrylate, but in this study, a 2% aqueous solution of 2% aqueous solution was used. Hydroxypropyl cellulose (hereinafter abbreviated as HPC) having a viscosity of 300-6000 cps at 20 ° C. is acetylated, and AC-HPC having an acetyl group content of 7 or more can be used as a thixotropic agent for α-cyanoacrylate. Thus, the present invention has been completed.

That is, the present invention provides a 3% aqueous solution having a viscosity at 20 ° C. of 300
An adhesive composition comprising an AC-HPC obtained by acetylating HPC of up to 6000 cps so that the acetyl group content becomes 7% or more to α-cyanoacrylate.

[Configuration and operation of the invention]

In the present invention, using the specific AC-HPC having the above-mentioned specific acetyl group content and the raw material HPC having the above-mentioned specific viscosity so as to be suitable as a stable thixotropic agent of α-cyanoacrylate. It is a big feature.

By using such a specific AC-HPC as a thixotropic agent of α-cyanoacrylate,
It can be stably compounded without impairing the original adhesive performance of cyanoacrylate. For example, it is stable without thickening or hardening at room temperature for 6 months or more.

Although the detailed reasons for exhibiting such excellent effects have not yet been fully elucidated, for example, as shown in the experimental examples described below, stable mere acetylation of HPC having a viscosity outside the above specified range is stable. Or a mere thickening effect (liquid with spinnability) can be obtained.

The AC-HPC of the present invention is obtained by acetylating HPC having a viscosity of 300 to 6000 cps at 20 ° C. in a 2% aqueous solution to have an acetyl group content of 7% or more, preferably 12% or more.

AC-HPC obtained by acetylating a 2% aqueous solution of HPC before acetylation at a temperature of 20 ° C. (hereinafter referred to as “viscosity of HPC”) of less than 300 cps has an acetyl group content as described above. Even within the specified range, to use as a thixotropic agent of α-cyanoacrylate,
It requires a compounding amount that significantly lowers the original adhesion performance of α-cyanoacrylate, and the “HPC viscosity” is 6000 cps.
Larger AC-HPCs take longer to dissolve,
In addition, the resulting paste-like composition tends to undergo a structural change with the passage of time and shift to a composition having strong spinnability.

On the other hand, when the acetyl group content of AC-HPC does not reach 7%, it is difficult to dissolve and only a composition having poor stability can be obtained. In particular, when the acetyl group content is 20% or more, the solubility in α-cyanoacrylate becomes very good, and the paste composition is easily prepared, which is particularly preferable.

When preparing the adhesive composition of the present invention, the AC-
The amount of HPC is set according to the properties of the thixotropic composition of α-cyanoacrylate,
If the amount does not reach 0.5% by weight, the structural properties are low, and the blending of 0.5% or more is desirable. The upper limit to be blended varies depending on the purpose of use of the composition to be produced, and is not particularly limited. However, if it exceeds 14%, the set time may sometimes be delayed, and is preferably 14% by weight or less, particularly preferably 3 to 8% by weight.

The AC-HPC of the present invention can be used in an organic solvent such as benzol.
And an acetylating agent such as acetyl chloride, or can be easily produced by reacting with acetic acid, glacial acetic acid, or the like to effect acetylation.

As the α-cyanoacrylate used in the present invention, various α-cyanoacrylates conventionally used for this kind of adhesive can be widely used, and more specifically, the following formula (1) (Wherein, R represents a linear or branched alkyl group having 1 to 16 carbon atoms, an allyl group, or a phenyl group having or not having a substituent). You. To explain the compound represented by the formula (1) in more detail, the alkyl group in the formula (1) may be substituted with a halogen atom or an alkoxy group. One or more substituents of the phenyl group may be substituted. Examples of the substituent at this time include a halogen atom and an alkoxy group.

The .alpha.-cyanoacrylate used as the main component of the present invention is a compound which is liable to undergo anionic polymerization, as is well known. Therefore, it is preferable to add an anionic polymerization inhibitor to the adhesive of the present invention. That is, for example, SO ₂ , N
O, NO ₂ , HCl, H ₃ PO ₄ , (C ₂ H ₅ ) O.BF ₃ , aromatic sulfonic acid, alkyl sulfonic acid, etc. One kind and, if necessary, at least one kind of radical polymerization inhibitor generally used for this kind of adhesive such as hydroquinone, catechol, pyrogallol, hydroquinone monomethyl ether and the like are added.

The amount of such a polymerization inhibitor is slightly different depending on the type of each inhibitor, but generally an anionic polymerization inhibitor is 1 to 500 p.
pm preferably 5-100 ppm, radical polymerization inhibitor 1-20
It is in the range of 00 ppm, preferably 10 to 1200 ppm.

Next, the present invention will be described with reference to experimental examples in order to make it easier to understand.

Experimental Example 1 HPC having a viscosity of 3260 cps at 20 ° C. in a 2% aqueous solution was acetylated to give an acetyl group content of about 5 to about 21 shown in Table 1.
% Of various AC-HPCs were prepared.

Each of the AC-HPCs in Table 1 above was converted to ethyl-α-cyanoacrylate (containing 30 ppm of SO ₂ and 500 ppm of hydroquinone).
Formulated in the proportions shown in the table, to prepare an adhesive composition,
The solubility, thixotropy (or pasting), stability and the like were examined. The results are shown in Table 2.

In a series of adhesive compositions obtained by appropriately mixing and dissolving various AC-HPCs shown in Table 1 with ethyl-α-cyanoacrylate so as to be 2 to 6.5% by weight, the acetyl group content was 7%. % Or more of the AC-HPC was suitable for preparing the non-spinnable paste composition of the present invention.

Experimental Example 2 HPC having a viscosity of 350 to 5600 cps at 20 ° C. of a 2% aqueous solution
Was acetylated to produce a series of various grades of AC-HPC as shown in Table 3.

Various AC-HPCs shown in Table 3 above were converted to ethyl-α-
Cyanoacrylate (SO ₂ 30 ppm, hydroquinone 500ppm
) Was observed.

 Table 4 shows the results.

AC-HPC derived from HPC having a 2% aqueous solution viscosity of 350 to 5600 cps and acetylated to have an acetyl group content of 7 to 18% is added to α-cyanoacrylate in an amount of 0.5 to 14% depending on its properties. By blending so as to be in% by weight, various adhesive compositions could be prepared from a soft paste to a hard paste depending on the purpose of use.

The paste adhesive composition shown in Table 4 was 70 ° C.
When the heat treatment is carried out at a temperature of 18 to 120 hours, the structure changes and the viscosity decreases, and the paste-like composition becomes a fluid liquid. The properties as a paste-like composition were maintained to the extent that the viscosity slightly decreased.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples. The methods for measuring various physical properties were as follows.

Set time: Material NBR, 6.2m / m O-ring. The NBR is cut vertically with a cutter, the sample is applied to one of the cut surfaces, and after a certain period of time has passed since bonding, the two hands are no longer pulled strongly and set as the set time. Remove in 5 seconds.

Tensile shear strength: JI using Shimadzu Autograph S-2000
It was measured in accordance with item 6 of SK 6861.

Storage stability: A large number of aluminum tubes having a capacity of 3 g were filled with samples, sealed and allowed to stand at room temperature, and several were opened at regular intervals to test the properties of the contents.

Example 1 AC-HPC having an acetyl group content of 18.15% (“HPC viscosity” 326)
0 cps) with ethyl-α-cyanoacrylate (SO ₂ 30 pp)
m, containing 500 ppm of hydroquinone) in an amount of 2.0 to 9.0% by weight, and dissolved under stirring at a temperature of 40 to 60 ° C. for 2 to 4 hours to prepare a series of adhesive compositions. Tested. Table 5 shows the results.

Separately, the case where polymethyl methacrylate or non-acetylated HPC was used is also shown.

When the AC-HPC of the present invention is blended with ethyl-α-cyanoacrylate in the composition so as to be 2.0 to 8.0% by weight, a slightly soft paste to a slightly soft paste which is convenient for use depending on the purpose. Various adhesive compositions can be prepared. The adhesive performance of these compositions is
There was no inferiority to that of this kind of α-cyanoacrylate adhesive, and there was no problem in stability even after being left at room temperature for 6 months.

Example 2 AC-HPC having an acetyl group content of 16.32% (“viscosity of HPC” 560)
0 cps) was added to 0.5% by weight of α-cyanoacrylate as in Example 1 and dissolved under stirring at a temperature of 50 to 60 ° C. for 40 to 60 minutes to prepare a composition. went.

The viscosity was 420 cps, but did not run down for about 10-15 seconds when a drop of the composition was pressed against a vertical glass surface. The adhesive performance showed a tensile shear strength of 165 kg / cm ² , a set time of 10 seconds, and no change over time after storage at room temperature for 6 months.

Example 3 The AC-HPC used in Example 1 was replaced with methyl-α-cyanoacrylate (containing 35 ppm of CO ₂ and 700 ppm of hydroquinone).
Was dissolved under stirring at a temperature of 60 to 65 ° C. for 2 to 3 hours to obtain a paste adhesive composition having a viscosity of 32000 cps. The adhesive performance of the composition is such that the tensile shear strength is 207 kg / c.
m ² , set time was 15 seconds, and good stability was maintained even after standing at room temperature for 6 months.

Example 4 AC-HPC having an acetyl group content of 12.61% (“HPC viscosity” 235
0 cps) was mixed with 4% by weight of methoxyisopropyl-α-cyanoacrylate (containing 20 ppm of SO ₂ and 200 ppm of hydroquinone) and dissolved under stirring at a temperature of 40 to 50 ° C. for about 3 hours,
A composition was prepared and subjected to each test.

The adhesive composition has a smooth paste having a viscosity of 22000 cps, a set time of 20 seconds, a tensile shear strength of 125 kg / cm ² , and its performance hardly changes even after being left at room temperature for 6 months. Did not.

Example 5 AC-HPC having an acetyl group content of 21.13% (“viscosity of HPC” 326
0 cps) with ethyl-α-cyanoacrylate (SO ₂ 25 pp)
m, containing 500 ppm of hydroquinone) and dissolved by stirring at room temperature for 3 to 7 hours to prepare an adhesive composition and perform each test. The composition presents a smooth paste with a viscosity of 27200 cps, a set time of 10 seconds,
The tensile shear strength was 157 kg / cm ² , and was completely stable after standing at room temperature for 6 months.

Claims (1)

(57) [Claims] 1. An acetylated hydroxypropyl cellulose obtained by acetylating a hydroxypropyl cellulose having an acetyl group content of 7% or more and a viscosity of 300 to 6000 cps at 20 ° C. in a 2% aqueous solution, α-cyanoacrylate An α-cyanoacrylate-based adhesive composition characterized by being blended with: