JP2997482B2 - Pressure sensitive adhesive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive obtained by curing a specific composition and having both flexibility, high elongation and tensile strength.

[Prior Art and Problems to be Solved by the Invention] Several methods for obtaining a tape-shaped or sheet-shaped pressure-sensitive adhesive having relatively high adhesive strength have been conventionally known.
For example, a method of thickening the pressure-sensitive adhesive layer is known,
Since the thickness of the adhesive layer is limited, the adhesive strength is also limited.

In addition, when a thick foam is used as the base material, the adhesiveness of the pressure-sensitive adhesive becomes relatively good, but in the case of the most common urethane foam or polyethylene foam, it is preferable to have a relatively high shear adhesive force. If the peel adhesive strength is not sufficient and a relatively high peel adhesive strength is provided, there is a limit to the shear adhesive strength as a pressure-sensitive adhesive, and a relatively high peel adhesive strength and a relatively high shear adhesive strength are combined. However, there is a problem in that it is not easy to obtain a material having satisfactory characteristics.

In order to solve such a problem, a pressure-sensitive adhesive containing a specific type of air bubbles at a specific ratio has been obtained (Japanese Patent Laid-Open No. 58-12 / 1983).
No. 5776). However, this pressure-sensitive adhesive material has a pressure-sensitive adhesive property by foaming a composition which becomes a state having pressure-sensitive adhesive property when polymerized and then put on a substrate, and polymerized on site before the foam disappears. It has the drawback of having to be in a state, which is quite special in terms of both form and manufacturing.

Although pressure-sensitive adhesive tapes containing glass microbubbles employing ultraviolet polymerization instead of the air bubbles (JP-A-53-141346 and JP-A-62-34976) have also been practiced, a sufficient amount of black pigment is used. When added, UV rays are blocked and polymerization is inhibited, so that it is difficult to obtain a product having a dark appearance desired by the market.

[Means for Solving the Problems] The present invention relates to a tape-shaped or sheet-shaped pressure-sensitive adhesive having flexibility, relatively high adhesive strength, and a colored composition including black in appearance. An object of the present invention is to provide a pressure-sensitive adhesive which is easy and relatively inexpensive.

That is, in the present invention, in a pressure-sensitive adhesive obtained by crosslinking and curing a composition containing a liquid rubber-based organic polymer as a main component at room temperature, the thickness of the pressure-sensitive adhesive is 0.5 mm or more. It is a pressure-sensitive adhesive characterized by the following.

The rubber-based organic polymer referred to in the present invention becomes a rubbery state after curing and has flexibility. It should be noted that having flexibility in the present specification means that the elasticity at ordinary temperature is 5 × 10 ⁷ dyn / c, although the elasticity at ordinary temperature is, of course, bendable with very little finger force at ordinary temperature.
m ² or less.

The rubber organic polymer is preferably in a liquid state. However, when the polymer itself is not in a liquid state, it may be turned into a liquid state by using a solution, a plasticizer or the like. The main chain of the rubber-based organic polymer is not particularly limited as long as the cured product is an organic polymer that becomes a rubber-like material, but a polyalkylene oxide such as polypropylene oxide is preferable. Further, as a reactive group for crosslinking and curing, for example, a reactive silicon group, a hydroxyl group, an isocyanate group, a glycidyl group, an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, an amino group, an amide group,
An organic polymer which has at least one carboxyl group, mercapto group or the like in a molecule and is liquid at normal temperature can be used. From the viewpoint of the flexibility of the cured substrate, a rubber-based organic polymer having at least one reactive silicon group in a molecule and being liquid at room temperature (hereinafter, also referred to as a rubber-based organic polymer (A)) is preferable. .

The reactive silicon group contained in the rubber-based organic polymer (A) is a well-known group, and has a hydroxyl group or a hydrolyzable group bonded to a silicon atom to form a siloxane bond. Has the characteristic that it can be crosslinked.

Examples of such reactive groups include those of the general formula: (In the formula, X is a hydroxyl group or a hydrolyzable group, and when two or more are present, they may be the same or different. R ¹ is a monovalent monovalent having 1 to 20 carbon atoms. A hydrocarbon group, or (R ') ₃ SiO- (where R' has 1 to 20 carbon atoms)
And three R's may be the same or different), and when two or more R ¹ are present, they are They may be the same or different. a is 0, 1,
2 or 3 and b is 0, 1 or 2, provided that 1 ≦
a + mb and m Need not be the same. m is 0 or 1 to 19
It is. ) Is shown.

Preferred reactive silicon groups have the general formula: (Wherein X is the same as above, and R ² has 1 to 18 carbon atoms)
Wherein n is 1, 2 or 3. ).

Specific examples of the hydrolyzable group include, for example, generally known groups such as a hydrogen atom, a halogen atom, an alkoxy group, and an acyloxy group. Among these, an alkoxy group is particularly preferable because it has mild hydrolyzability and is easy to handle.

Specific examples of R ¹ , R ² and R ′ include an alkyl group such as a methyl group and an ethyl group, a cycloalkyl group such as a cyclohexyl group, an aryl group such as a phenyl group, an aralkyl group such as a benzyl group, and a trimethylsiloxy group. Is raised. Further, it may be a hydrocarbon group in which some hydrogen atoms are substituted. Of these, a methyl group is particularly preferred.

One molecule of the rubber organic polymer (A) contains at least one, preferably 1.2 to 6 reactive silicon groups. If the number of reactive silicon groups contained in one molecule is less than one, curing will be insufficient, which is not preferable. Also, 6
If the number exceeds the number, the cured product becomes insufficient in flexibility.

In the rubber-based organic polymer (A), the reactive silicon group is preferably present at a molecular terminal. When a reactive silicon group is present at the molecular end, the molecular weight between cross-linking points becomes large, so that there is an advantage that a cured product having flexibility and high elongation can be easily obtained.

The molecular weight of the rubber-based organic polymer (A) is preferably about 500 to 50,000, particularly preferably about 1,000 to 20,000, because the rubber-based organic polymer (A) is preferably liquid at room temperature.

As a component that can be used other than the specific rubber-based organic polymer constituting the composition for a base material, there is a tackifier resin used for adjusting the flexibility of the base material and increasing the strength. There is no particular limitation on the tackifier resin, and any commonly used tackifier resin can be used.

Specific examples of such a tackifier resin include, for example,
Examples include phenol resins, modified phenol resins, terpene-phenol resins, petroleum resins, rosin ester resins, low molecular weight polystyrene resins, terpene resins, and the like. These may be used alone or as a mixture of two or more. Among these, phenol resin-based and phenol-containing resin-based resins are particularly preferred because they easily exhibit flexibility, high elongation and high strength.

When used together with the rubber organic polymer (A), the amount of the tackifier resin used is preferably 10 to 140 parts by weight, more preferably 20 to 80 parts by weight, per 100 parts by weight of the rubber organic polymer (A). If the amount exceeds 140 parts by weight, a high elastic modulus is obtained, and rubber-like properties cannot be sufficiently obtained.

A curing catalyst is a component used together with the specific rubber-based organic polymer constituting the base material composition. The curing catalyst acts on the rubber-based organic polymer used in the present invention to crosslink and cure, thereby producing a stable base composition. The curing catalyst used together with the rubber-based organic polymer (A) is not particularly limited, and a commonly used silanol condensation catalyst is used.

Specific examples of such a curing catalyst include, for example, titanates, tin carboxylate salts, organic zirconium compounds, reactants of dibutyltin oxide and phthalate esters, chelate compounds, lead octylate, amine compounds, Acidic phosphates, saturated or unsaturated polycarboxylic acids or anhydrides thereof, reactants of amine compounds with acidic phosphates, reactants of amine compounds with saturated or unsaturated polycarboxylic acids or anhydrides, Other well-known silanol catalysts, such as an acidic catalyst and a basic catalyst, are mentioned.

Specific examples of the titanates include tetrabutyl titanate and tetrapropyl titanate.

Specific examples of the tin carboxylate include dibutyltin laurate, dibutyltin maleate, dibutyltin acetate, tin octylate, tin naphthenate and the like.

Specific examples of the organic zirconium compound include zirconium tetraisopropoxide and zirconium tetrabutoxide.

Specific examples of the chelate compound include aluminum trisacetylacetonate, aluminum trisethylacetoacetate, and organic aluminum compounds such as diisopropoxyaluminum ethylacetoacetate;
Examples include dibutyltin diacetylacetonate, zirconium tetraacetylacetonate, and titanium tetraacetylacetonate.

Specific examples of the amine compound include butylamine,
Laurylamine, dibutylamine, dilaurylamine,
Examples include dimethylbutylamine, dimethyllaurylamine, monoethanolamine, triethylenetriamine, guanidine, 2-ethyl-4-methylimidazole, 1,8-diazabicyclo (5,4,0) undecene-7 (DBU) and the like.

Further, the acidic phosphate ester, Is a phosphoric acid ester containing a moiety of, for example, (Wherein d is 1 or 2, R ³ represents an organic group) and the like, and specifically, (CH ₃ O) ₂ -P (O) —OH, (CH ₃ O) _{3 O) -P (O) -} (OH) 2, (C 2 H 5 O) 2 -P (O) -OH, (C 2 H 5 O) -P (O) - (OH) 2, [( _{CH 3) 2 CHO] 2 -P} (O) -OH, (CH 3) 2 CHO-P (O) - (OH) 2, (C 4 H 9 O) 2 -P (O) -OH, (C _{4 H 9 O) -P (O} ) - (OH) 2, (C 8 H 17 O) 2 -P (O) -OH, (C 8 H 17 O) -P (O) - (OH) 2, _{(C 10 H 21 O) 2} -P (O) -OH, (C 10 H 21 O) -P (O) - (OH) 2, (C 13 H 27 O) 2 -P (O) -OH, _{(C 13 H 27 O) -P} (O) - (OH) 2, (HO-C 6 H 12 O) 2 -P (O) -OH, (HO-C 6 H 12 O) -P (O) _{- (OH) 2, [(} CH 2 OH) (CHOH) O] 2 -P (O) -OH, [(CH 2 OH) ( CHOH) O] -P (O) - (OH) 2, [(CH 2 OH) (CHOH) C 2 H 4 O] 2 -P (O) -OH, [(CH 2 OH) (CHOH) C 2 _{H 4 O] -P (O)} - (OH) 2, and the like, such as.

Among these, aluminum trisacetylacetonate, aluminum trisethylacetoacetate,
Organic aluminum compounds such as diisopropoxyaluminum acetoacetate, zirconium tetraacetylacetonate, zirconium tetraisopropoxide,
An organic zirconium compound such as zirconium tetrabutoxide, an organic titanium compound such as tetrabutyl titanate, tetrapropyl titanate, titanium tetraacetylacetonate, a divalent organic tin compound such as tin octylate, etc. It is preferable in that it has good releasability from paper or silicon release paper which is generally used as a separator.

The amount of these curing catalysts used depends on the amount of the rubber-based organic polymer (A).
0.1 to 10 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight. If the amount is less than 0.1 part by weight, the catalytic effect is not sufficient, and if it exceeds 10 parts by weight, the curing is too fast, and the workability of coating on the support deteriorates.

As other components to be used, a filler can be used for adjusting the physical properties of the base material and the viscosity of the base material composition used for cost reduction, and a solvent can be used.

Specific examples of the filler include, for example, silica fine powder, calcium carbonate, clay, talc, titanium oxide, zinc white, diatomaceous earth, barium sulfate, carbon black,
Examples include a micro hollow body.

Examples of the inorganic spherical minute hollow body include a glass spherical minute hollow body, a silica balloon, a fly ash balloon, and a shirasu balloon. Specific examples of such an inorganic spherical minute hollow body include a glass spherical hollow body such as Karoon manufactured by Nippon Sheet Glass Co., Ltd., Scotchlite manufactured by Sumitomo 3M Limited, and Cellstar Z-28 manufactured by Asahi Glass Co., Ltd. Examples of the silica balloon include Q-CEL manufactured by Asahi Glass Co., Ltd., and examples of the shirasu balloon include Winlight manufactured by Ichi Kasei Co., Ltd., and Sankilite manufactured by Sanki Kogyo. Examples of the organic spherical minute hollow body include a phenol resin balloon “UCAR” manufactured by Union Carbide. These may be used alone or as a mixture of two or more. Further, those obtained by treating the surfaces of these spherical minute hollow bodies with a silane compound, polypropylene glycol or the like can also be used.

The amount of these inorganic and organic spherical minute hollow bodies used is
When used together with the rubber organic polymer (A), the amount is preferably 3 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the rubber organic polymer (A). If the amount is less than 3 parts, the weight cannot be sufficiently reduced, and if it exceeds 50 parts, the elongation and strength of the substrate are undesirably reduced. These minute hollow bodies are used to reduce the weight and cost of the substrate without significantly impairing the flexibility, elongation and strength of the substrate.

In addition, antioxidants, ultraviolet absorbers, pigments, surfactants, and the like are used according to the respective purposes, but are not limited thereto.

In the present invention, in mixing the rubber-based organic polymer with other components, a Banbury mixer, a kneader, a roll, a mixer such as a planetary mixer may be used, and when a tackifying resin is used, Can be easily mixed by previously crushing into a fine powder state of about 1 to 100 μm. The fine powder of the tackifier resin does not necessarily have to be in a homogeneously dissolved state before coating, and may be present in the rubber-based organic polymer in a non-uniformly dispersed state as small particles.

The production of a cured sheet from the curable composition prepared as described above is usually achieved by applying the composition to a silicon release paper or the like, drying and curing.

The coating method is not particularly limited, and the curable composition may be applied using a usual coater. After coating, drying
The curing step is carried out, and the drying and curing conditions are from room temperature to 150 ° C. for about 0.5 to 30 minutes.

The thus obtained pressure-sensitive adhesive of the present invention has an elastic modulus at room temperature of 1 × 10 ⁸ dyn / cm ² or less, particularly 5 × 10 ⁷ dyn / cm ^2.
yn / cm ² or less, has favorable adhesive properties such as high flexibility, high peel adhesive strength, and high shear adhesive strength, and is easy to mix in color including black in appearance, and relatively inexpensive. Therefore, it can be suitably used for applications such as assembling and fixing automobile products (for example, bonding of side moldings, emblem moldings, weather strips, etc.), electric products, indoor furniture, display boards, building materials, and the like. The industrial value is very high.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

Examples 1 to 17 An average of three dimethoxysilyl groups per molecule: A polymer comprising propylene oxide having an average molecular weight of 9600 (hereinafter referred to as a propylene oxide-based polymer (a)) having an average of 1.5 dimethoxysilyl groups per molecule: (Hereinafter referred to as a propylene oxide-based polymer (b)), a fine powder of an adhesive resin, diphenylsilanediol as a silicon compound, and a hindered phenol-based antioxidant (Ouchi Nocrack NS-6, manufactured by Shinko Chemical Co., Ltd., carbon black powder, and a decomposable foaming agent (AIBN) were weighed in the amounts shown in Table 1 and kneaded and mixed with three paint rolls. A 50% toluene solution of aluminum trisethyl acetoacetate was added as a curing catalyst in the amount shown in Table 1 and mixed to homogenize, followed by defoaming under reduced pressure. The obtained curable composition was applied to silicon release paper (EK-130R manufactured by Souken Kako Co., Ltd.) using a doctor blade so as to have the thickness shown in Table 1, and then at 120 ° C. A heat-curing treatment was performed for 10 minutes to obtain a pressure-sensitive adhesive (double-sided adhesive tape) of the present invention.

The adhesive properties of the obtained double-sided adhesive tape were measured by the following method. The results are shown in Table 1.

180 ° peel strength 2.25μm thick polyester film backed width 2.
A 5 cm double-sided adhesive tape piece was prepared and bonded to a stainless plate polished with # 280 abrasive paper. After leaving this at room temperature for one day, it was heated at 23 ° C for 30
The 180 ° peel strength was measured at a tensile strength of 0 mm / min.

Shear adhesive strength Aluminum plate 2mm thick, 2.5cm wide, 8cm long (JIS H4000; A
1050P) A portion of about 3.2 cm ² at the end of the adherend was bonded with a double-sided adhesive tape. After leaving this at room temperature for one day, the tensile shear adhesive strength was measured at 23 ° C. and 70 ° C. atmosphere at a tensile speed of 300 mm / min using an autograph manufactured by Shimadzu.

Adhesiveness on a curved surface A double-sided tape backed by an aluminum tube having a size of 15 mm × 120 mm and a thickness of 0.2 mm was bonded to an aluminum tube having an outer diameter of 80 mm in a direction perpendicular to the direction of the tube. This was left in an atmosphere of 23 ° C. for 10 days, and the length (mm) of the terminal portion where the natural peeling was performed was measured.

Tack Measured using a J.Dow type rolling ball tack method.
The run distance was 10 cm, the inclination angle was 30 degrees, the temperature was 23 ° C., and the maximum diameter of the stationary ball (× 1/32 inch) was displayed.

Tensile properties Dumbbells (JIS No. 3) were punched out, pulled at 23 ° C and 300 mm / min, and the modulus at 100% deformation, strength at break, and elongation at break were determined.

Comparative Examples 1 to 3 Double-sided adhesive tapes were prepared in the same manner as in Example 1 except that the tape was coated so as to have the thickness shown in Table 2 in Example 1. Table 2 shows the adhesive properties of the obtained tapes.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09J ^7/ 00-7/04

Claims (1)

(57) [Claims] (A) a compound having a hydroxyl group or a hydrolyzable group bonded to a silicon atom and having at least one silicon-containing group capable of crosslinking by forming a siloxane bond in a molecule having a molecular weight of 500 to 50,000. A propylene oxide organic polymer which is liquid at room temperature, (B) a curing catalyst, and (C) a curable composition mainly composed of 10 to 140 parts by weight of a phenolic resin per 100 parts by weight of the propylene oxide organic polymer. A pressure-sensitive adhesive characterized in that the thickness of the pressure-sensitive adhesive obtained by curing is 0.5 mm or more.