JP2893124B2 - Adhesive composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color tone and transparency based on a block copolymer composition having a specific structure, which is coupled with a specific bifunctional diepoxy compound. The present invention relates to a pressure-sensitive adhesive composition having excellent thermal stability, (color tone and odor upon heating) and holding power, and excellent balance between tackiness and melt viscosity.

(Prior art) In recent years, solvents used in solvent-type adhesives have serious problems in terms of environmental pollution, fire, and working environment. From the viewpoint, hot-melt adhesives have come to be widely used, and monoalkenyl aromatic compound-conjugated diene-based block copolymers have been widely used as base polymers for hot-melt adhesives. ing.

However, a pressure-sensitive adhesive composition comprising a monoalkenyl aromatic compound-conjugated diene-based block copolymer is generally inferior in thermal stability, and furthermore, the holding power, the balance between tackiness and melt viscosity are insufficient, These improvements are desired.

As methods for improving these, JP-A-64-81877 and "Adhesion" (Vol. 32, No. 1, p. 27 (1988)) disclose a pressure-sensitive adhesive composition comprising a triblock copolymer and a diblock copolymer. Is disclosed. Further, JP-A-61-261310 and JP-A-63-248817 disclose specific bifunctional coupling agents (aliphatic monoesters, dihalogen compounds).
Discloses a pressure-sensitive adhesive composition comprising a block copolymer obtained by coupling.

(Problems to be Solved by the Invention) However, the improvement effect is insufficient with the method disclosed above, and the present invention is excellent in color tone / transparency and thermal stability, and furthermore, has a high holding power, tackiness and melt viscosity. The object of the present invention is to provide a pressure-sensitive adhesive composition having an excellent balance.

(Means for Solving the Problems) The present inventors have conducted intensive studies in order to develop the above-mentioned preferred pressure-sensitive adhesive composition, and as a result, coupled with a specific bifunctional diepoxy compound to obtain a specific structure. It has been found that a pressure-sensitive adhesive composition containing a monoalkenyl aromatic compound-conjugated diene-based block copolymer composition having the formula (1) is suitable for the purpose, and based on this finding, the present invention has been completed.

That is, the present invention provides: (a) polymerizing a block copolymer composed of a polymer block mainly composed of at least one monoalkenyl aromatic compound and a polymer block mainly composed of a conjugated diene; The peak molecular weight in gel permeation chromatography (GPC) is 1 × 10 ⁴ to 50 × 10 ⁴ in terms of standard polystyrene, and the total amount of all monoalkenyl aromatic compounds in the block copolymer is 10
A living polymer that is ~ 50% by weight and a general formula: Wherein R is Wherein R ₁ and R ₂ are hydrogen or an alkyl group having 1 to 20 carbon atoms, or a phenyl group, R ₃ is an alkylene group having 2 to 20 carbon atoms, and n is an integer of 0 to 10. There, a single n _o body diepoxy compound content is indicated by the a] 95 wt% or more, or, (mixture or a mixture of different groups each other in the same group comrades) mixtures thereof
A linear block copolymer composition obtained by subjecting the compound to a coupling reaction, wherein the coupled component in the linear block copolymer composition is 30% by weight or more.
(B) 20 to 400 parts by weight of a tackifying resin, and (c) 0 to 200 parts by weight of a softening agent, based on 100 parts by weight. .

 Hereinafter, the present invention will be described in detail.

The component (a) constituting the present invention is obtained by polymerizing a block copolymer composed of at least one polymer block mainly composed of a monoalkenyl aromatic compound and a polymer block mainly composed of a conjugated diene. The peak molecular weight of the polymer in gel permeation chromatography (GPC) is 1 × 10 ⁴ to 50 × 10 ⁴ in terms of standard polystyrene, and the total amount of all monoalkenyl aromatic compounds in the block copolymer is , 10-50
It is obtained by coupling a living polymer in weight% with a specific bifunctional diepoxy compound.

Examples of the monoalkenyl aromatic compound used in the component (a) include monomers such as styrene, p-methylstyrene, tertiary butylstyrene, α-methylstyrene, and 1,1-diphenylethylene. Among them, styrene is preferred. These monomers may be used alone or in combination of two or more.

On the other hand, examples of the conjugated diene include simple compounds such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, and phenyl-1,3-butadiene. And 1,3
-Butadiene and isoprene are preferred. These monomers may be used alone or in combination of two or more.

(A) As a mode of living polymer in the component, for example, the general _{formula: (A-B) m -Li} , (B-A-B) m -Li, (A-B-A) m -Li ( wherein In the formula, A is a polymer block mainly composed of a monoalkenyl aromatic compound, B is a copolymer block mainly composed of a conjugated diene, and m is 1
-5) are used alone or in combination.

Further, the polymer block mainly composed of a monoalkenyl aromatic compound refers to a homopolymer block of a monoalkenyl aromatic compound or a monoalkenyl aromatic compound-conjugated diene copolymer containing more than 50% by weight of a monoalkenyl aromatic compound. The term "polymer block containing a conjugated diene" means a conjugated diene homopolymer block or a conjugated diene-monoalkenyl aromatic compound copolymer block containing more than 50% by weight of a conjugated diene. When each block is a copolymer, the arrangement of the monoalkenyl aromatic compound and the conjugated diene may be uniform or non-uniform (taper type or the like).

In addition to the coupling reaction of the living polymer represented by the above general formula, living polymers having different composition ratios (structures) may be separately adjusted according to the purpose, and the coupling reaction may be performed. Living polymers having different compositions (structures) may be adjusted by additional addition polymerization of an organolithium compound or the like, and a coupling reaction may be performed. Further, the living polymer represented by the above general formula may be subjected to a coupling reaction with a (co) polymer living polymer mainly composed of an alkenyl aromatic compound or a (co) polymer living polymer mainly composed of a conjugated diene.

In the present invention, the peak molecular weight of the block copolymer immediately before coupling by GPC is 1 × 10 ⁴ to 50 × 10 ⁴ , preferably 3 × 10 ⁴ to 30 × 1 in terms of standard polystyrene.
0 is ⁴ . When the peak molecular weight is less than 1 × 10 ⁴ , the holding power of the pressure-sensitive adhesive composition is remarkably impaired, and when it exceeds 50 × 10 ⁴ , the melt viscosity of the pressure-sensitive adhesive composition is remarkably increased, thereby impairing processability.

In the component (a), the total amount of all the monoalkenyl aromatic compounds in the block copolymer immediately before the coupling and the linear block copolymer composition after the coupling reaction is 10 to 10%.
It is selected in the range of 50% by weight, preferably 15-40% by weight. If the total amount is less than 10%, the holding power of the pressure-sensitive adhesive composition is significantly impaired, and if it exceeds 50%, the tackiness of the pressure-sensitive adhesive composition is impaired.

The diepoxy compound used in the component (a) includes a general formula; Wherein R is Wherein R ₁ and R ₂ are hydrogen or an alkyl group having 1 to 20 carbon atoms, or a phenyl group, R ₃ is an alkylene group having 2 to 20 carbon atoms, and n is an integer of 0 to 10. There, a single n _o body diepoxy compound content is indicated by the a] 95 wt% or more, or, (mixture or a mixture of different groups each other in the same group comrades) mixtures thereof
Indicated by

(I) Specific examples of the group include: And the like, but are not limited thereto.

As a specific example of the group (II), And the like.

(II) Specific examples of the group include: And the like, but are not limited thereto.

The n number of the diepoxy compound used in the present invention is 0 to 10
And preferably an integer of 0-5, more preferably 0-3. When the number of n exceeds 10, the retention of the pressure-sensitive adhesive composition tends to be insufficiently improved.
Similarly, n _o-isomer content is insufficient improvement retention of the pressure-sensitive adhesive composition is less than 95 wt%.

On the other hand, n _o-isomer content is crystalline increases as it approaches the 100% by weight (particularly (I) group), it becomes difficult to handle.

Therefore, when the diepoxy compound used in the present invention is a group (I), bisphenol F type and bisphenol AD type are preferable from the viewpoint of handleability. Most preferred is the use as a mixture of different or heterogeneous groups.

As a specific example, And the like, but are not limited thereto.

The composition ratio of the mixture is such that the amount of each component is 1 to 99% by weight, preferably 20 to 80% by weight, more preferably 40 to 60% by weight (the total amount of each component is 100% by weight). Is selected.

In the diepoxy compound used in the present invention, the total chlorine content (by-product or residual) derived from epichlorohydrin, which is one of the starting materials, is preferably 1% by weight or less, and particularly preferably 0.5% by weight or less. preferable. If the total chlorine content exceeds 1% by weight, the heat stability of the pressure-sensitive adhesive composition tends to be impaired.

The coupled component in the component (a) of the present invention needs to be 30% by weight or more, and if it is less than 30% by weight, the holding power of the pressure-sensitive adhesive composition is impaired.

Further, the decomposition temperature of the component (a) by differential thermal analysis (DTA) is not particularly limited, but is preferably 175 ° C. or higher from the viewpoint of thermal stability of the pressure-sensitive adhesive composition.

Similarly, the microstructure of the diene portion of the component (a) is not particularly specified, but the 1,4 conjugate may be 50% or more (preferably 65% or more, more preferably 80% or more). It is preferable from the viewpoint of holding power of the pressure-sensitive adhesive composition.

Further, the linear block copolymer (composition) subjected to the coupling reaction treatment of the component (a) was modified with a hydrogenated linear block copolymer and further with a modifier such as maleic anhydride. A linear block copolymer is also included.

Next, the type of the component (b) constituting the present invention is not particularly limited, and (hydrogenated) rosin-based resin, terpene-based resin,
Known tackifying resins such as coumarone-based resins, phenolic resins, terpene-phenolic resins, aromatic hydrocarbon resins, and aliphatic hydrocarbon resins, and these tackifying resins may be used in combination of two or more. It is possible.

The amount used is 20 parts by weight per 100 parts by weight of component (a).
It is used in the range of 400400 parts by weight, preferably in the range of 50 to 350 parts by weight. If the amount is less than 20 parts by weight, it is difficult to impart a tacky feeling to the pressure-sensitive adhesive composition.
If the amount exceeds 0 parts by weight, the holding power of the pressure-sensitive adhesive composition is reduced, and in any case, the pressure-sensitive adhesive properties tend to be impaired.

As the component (c) constituting the present invention, known naphthene-based and paraffin-based process oils and their mixed oils are used. An aroma system is not preferred because the color tone and heat stability of the pressure-sensitive adhesive composition are impaired.

The amount used is in the range of 0 to 200 parts by weight with respect to the component (a), and if it exceeds 200 parts by weight, the holding power of the pressure-sensitive adhesive composition tends to be significantly impaired.

Further, in the pressure-sensitive adhesive composition of the present invention, if necessary,
Stabilizers such as antioxidants and light stabilizers can also be added.

Examples of the stabilizer include 2,6-di-t-butyl-4.
-Methylphenol, n-octadecyl-3- (4'-
Hydroxy-3 ', 5'-di-tert-butylphenyl) propionate, 2,2'-methylenebis (4-methyl-6-
t-butylphenol), 2,2'-methylenebis (4-
Ethyl-6-t-butylphenol), 2,4-bis [(octylthio) methyl] -o-cresol, 2-t
-Butyl-6- (3-t-butyl-2-hydroxy-5
-Methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- [1- (3,5-di-t-
Hindered phenolic antioxidants such as amyl-2-hydroxyphenyl) ethyl] phenyl acrylate: dilauryl thiodipropionate, lauryl stearyl thiodipropionate, pentaerythritol-tetrakis (β-lauryl thiopropionate) Sulfur antioxidants: Tris (nonylphenyl) phosphite, Tris (2,
Examples thereof include phosphorus-based antioxidants such as 4-di-t-butylphenyl) phosphite.

Examples of the light stabilizer include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole,
-(2'-hydroxy-3 ', 5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-
Benzotriazole UV absorbers such as 3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, benzophenone UV absorbers such as 2-hydroxy-4-methoxybenzophenone, and hindered amine light stabilizers Can be mentioned.

In addition to the above stabilizers, the pressure-sensitive adhesive composition of the present invention may optionally contain pigments such as red iron oxide and titanium dioxide; waxes such as paraffin wax, microcrystalline wax, and low molecular weight polyethylene wax; amorphous polyolefin, ethylene-ethyl Polyolefin or low molecular weight vinyl aromatic thermoplastic resin such as acrylate copolymer; natural rubber; polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, isoprene-isobutylene rubber , Polypentena rubber, and synthetic rubbers other than the present invention, such as styrene-butadiene-based block copolymers and styrene-isoprene-based block copolymers.

The above-mentioned adhesive composition is prepared by a known mixer, kneader or the like by a method of uniformly mixing under heating.

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but these examples do not limit the present invention.

 In addition, various measurements followed the following method.

Measurement of physical properties of linear block copolymer composition; Total styrene content: Calculated from the absorption intensity at 262 nm using an ultraviolet spectrophotometer (Hitachi UV 200).

Peak molecular weight and composition ratio: GPC [The apparatus is manufactured by Waters, and the column is a combination of two ZORBAX PSM 1000-S manufactured by DuPont and PSM 60-S in total. Tetrahydrofuran was used as the solvent, and the measurement conditions were a temperature of 35 ° C., a flow rate of 0.7 ml / min, a sample concentration of 0.1% by weight, and an injection amount of 50 μm.].

The peak molecular weight is a value converted from the following standard polystyrene (manufactured by Waters) calibration curve.

1.75 × 10 ⁶ , 4.1 × 10 ⁵ , 1.12 × 10 ⁵ , 3.5 × 10 ⁴ , 8.5 × 1
0 ³ Decomposition start temperature: Using DTA (DTA40, manufactured by Shimadzu Corporation), ASTM D3
Based on 418-82, the extrapolated temperature _Tf was determined to be the decomposition disclosure temperature.

The sample used was a film (thickness: about 0.3 mm) press-formed at 110 ° C for about 5 seconds.
Minutes.

Measurement of Physical Properties of diepoxy compounds; n number and n _o-isomer content: GPC [apparatus is Waters, column manufactured by Showa Denko of Shodex K801, K802, a total of three combinations of K803, the detector R1, UV (254 nm) was used. Chloroform was used as the solvent, and the measurement conditions were a temperature of 35 ° C and a flow rate of 1.0 ml / mi.
n, sample concentration 0.1 wt%, the analysis of the n number and n _o-isomer content than the chromatogram of the injection volume 40μ is] was performed.

Measurement of Physical Properties of Pressure-Sensitive Adhesive Composition: Taken out in a molten state, coated on a polyester film to a thickness of 50 μm with an applicator, prepared a pressure-sensitive adhesive tape sample, and measured tackiness and holding power by the following methods.

Feeling of tackiness: ○, △, and × (○ is the most sticky and excellent) were ranked according to the touch finger.

Holding force: The holding force is 25m on a stainless steel plate according to JIS Z-1524.
Paste the adhesive tape so that the area of mx 25mm is in contact, 8
At 0 ° C., a load of 1 kg was applied, and the time until the adhesive tape came off was measured.

Melt viscosity: The melt viscosity of the adhesive composition was measured at 180 ° C. with a Brookfield viscometer.

Thermal Stability: The thermal stability of the adhesive composition was measured by placing it in a gear oven at 190 ° C. and aging for 24 hours, and then examining the odor and color tone.

As for the odor, according to the sensory test, ○, △, × (○
Is the least irritating odor).

Examples 2 and 3 Comparative Examples 1 to 4 After sufficiently replacing the stainless steel reactor equipped with a jacket and a stirrer with nitrogen, 5720 g of cyclohexane, 1 g of tetrahydrofuran and 240 g of styrene were charged, and warm water was passed through the jacket. To set the contents to about 70 ° C.

Thereafter, an n-butyllithium cyclohexane solution (1.4 g in pure content) was added to initiate polymerization of styrene. Ten minutes after the styrene was almost completely polymerized, 560 g of butadiene (1,3-butadiene) was added to continue the polymerization, and 15 minutes after the butadiene was almost completely polymerized and reached a maximum temperature of about 95 ° C. , Add a coupling agent (kind and amount,
(Shown in Table 1). Fifteen minutes after the addition of the coupling agent, 0.4 g of water was added. Immediately after charging the styrene, the system was continuously stirred with a stirrer.

Thereafter, the solution of the linear block copolymer composition was withdrawn, and 2,6-di-t-butyl-4-methylphenol 6.4
g, 4 g of tris (nonylphenyl) phosphite, and the solvent was removed by steam-stripping the obtained solution, followed by dehydration and drying with a hot roll (120 ° C.) to obtain a linear block copolymer. A composition was obtained.

150 g of the linear block copolymer composition thus obtained was mixed at 180 ° C for 2 hours and 1 hour at the compounding ratio shown in Table 3.
Was melt-kneaded in a container equipped with a stirrer to obtain a hot melt type adhesive composition.

 Table 1 shows the physical properties of these adhesive compositions.

Examples 1 and 4 A linear block copolymer composition and an adhesive composition were prepared in the same manner as in Examples 2 and 3, except that the amount of styrene, the amount of butadiene (total monomer 800 g), and the amount of the coupling agent were changed. I got
Table 1 shows the physical properties of these pressure-sensitive adhesive compositions.

Comparative Example 5 After sufficiently replacing the stainless steel reactor equipped with a jacket and a stirrer with nitrogen, 5720 g of cyclohexane, 1 g of tetrahydrofuran and 120 g of styrene were charged, and warm water was passed through the jacket to set the content at 70 ° C.

Thereafter, an n-butyllithium cyclohexane solution (0.7 g in pure content) was added to initiate polymerization of styrene. Ten minutes after the styrene was almost completely polymerized, 560 g of butadiene (1,3-butadiene) was added and the polymerization was continued. Then, 120 g of styrene was added again to continue the polymerization. After the styrene was almost completely polymerized, the polymerization was held for 15 minutes to complete the polymerization, and 0.2 g of water was added to inactivate.
Immediately after charging the first styrene, the system was continuously stirred with a stirrer during this period.

Thereafter, a linear block copolymer composition and a pressure-sensitive adhesive composition were obtained in the same manner as in Examples 2 and 3.

 Table 1 shows the physical properties of this pressure-sensitive adhesive composition.

Table 1 shows that Examples 1 to 4 are superior in (color tone), transparency and thermal stability in comparison with Comparative Examples 1 to 4. In addition, it can be seen that Examples 1 to 4 are excellent in melt viscosity and tackiness in comparison with Comparative Example 4, and surprisingly, the holding power is greatly improved.

Examples 5 and 6 A linear block copolymer composition and a pressure-sensitive adhesive were prepared in the same manner as in Examples 2 and 3, except that the amount of n-butyllithium (1.0 g in pure content) and the amount of coupling agent were changed. A composition was obtained. Table 2 shows the physical properties of these pressure-sensitive adhesive compositions.

Comparative Example 6 A linear block copolymer composition and a pressure-sensitive adhesive composition were obtained in the same manner as in Comparative Example 3, except that the addition amount of n-butyllithium (1.0 g in pure content) and the addition amount of a coupling agent were changed. Was.
Table 2 shows the physical properties of this pressure-sensitive adhesive composition.

Table 2 shows that Examples 5 and 6 are superior to Comparative Example 6 in color tone / transparency and thermal stability, and are also superior in melt viscosity and holding power.

(Effect of the Invention) Since the pressure-sensitive adhesive composition of the present invention is excellent in color tone / transparency, thermal stability and holding power, balance between tackiness and melt viscosity, it is particularly useful as a hot melt pressure-sensitive adhesive for sanitary materials. It is.

Furthermore, various adhesive tapes, labels, pressure-sensitive thin plates, pressure-sensitive sheets, back glue for fixing various lightweight plastic molded products,
It can be widely used as various adhesives, such as carpet fixing back glue and tile fixing back glue, and its industrial significance is great.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-81844 (JP, A) JP-A-1-289857 (JP, A) JP-A 52-20491 (JP, A) JP-A 62-88 1774 (JP, A) JP-A-54-10396 (JP, A) JP-A-61-26647 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08F 297/04 C09J 153 / 02 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] (A) polymerizing a block copolymer composed of at least one polymer block mainly composed of a monoalkenyl aromatic compound and a polymer block mainly composed of a conjugated diene; The peak molecular weight in gel permeation chromatography (GPC) is 1 × 10 ⁴ to 50 × 10 ⁴ in terms of standard polystyrene, and the total amount of all monoalkenyl aromatic compounds in the block copolymer is 10 to 10 50% by weight of a living polymer and a general formula: Wherein R is Wherein R ₁ and R ₂ are hydrogen or an alkyl group having 1 to 20 carbon atoms, or a phenyl group, R ₃ is an alkylene group having 2 to 20 carbon atoms, and n is an integer of 0 to 10. There, n number of the compounds of 0 (hereinafter, referred to as n _o body) alone diepoxy compound content is indicated by the a] 95 wt% or more, or a mixture thereof (mixture or different groups of the same group comrades Mixture of comrades)
A linear block copolymer composition obtained by a coupling reaction between the linear block copolymer composition 10 and the linear block copolymer composition, wherein the coupled component in the linear block copolymer composition is 30% by weight or more.
A pressure-sensitive adhesive composition comprising: (b) 20 to 400 parts by weight of a tackifying resin; and (c) 0 to 200 parts by weight of a softener, based on 0 parts by weight.