JPH07119395B2 - Pressure-sensitive adhesive composition and cured product thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition, and more particularly to an elastic pressure-sensitive adhesive composition that can be cured at room temperature or higher.

<< Prior Art >> Conventionally, for silicone pressure-sensitive adhesives, 1) it has a sufficiently low working viscosity, 2) it can be cured at room temperature, and 3) it gives not only wet adhesion but also dry adhesion. However, it is required to have various properties such as 4) hardening to become a long-life product, and 5) not disintegrating under humid conditions, but satisfying all of these properties is required. It was difficult.

Therefore, the inventors of the present invention have made extensive studies to satisfy all the above requirements, and have found a composition that can satisfy the above various conditions, and have reached the present invention.

<< Problems to be Solved by the Invention >> Therefore, an object of the present invention is to provide a room-temperature-curable pressure-sensitive adhesive having a sufficiently low working viscosity and capable of imparting not only wet tackiness but also dry tackiness. It is intended to provide a pressure-sensitive adhesive composition and a cured product thereof, which is a composition that does not disintegrate after curing even under wet conditions and has a long life.

The above objective of the present invention is to provide at least R ₃ SiO _1/2 units and
_Consisting essentially of SiO _4/2 units, R ₃ for each SiO _4/2 unit
An organosiloxane polymer having a molar ratio of SiO _1/2 units of 0.6 to 1.2 and having a hydroxysilyl group of less than 0.7% by weight: 100 parts by weight, a molecular chain terminal having an alkoxy group, an alkenyloxy group, an iminoxy group, an acyloxy group. , An average formula blocked with a silyl group having a functional group of aminoxy group or amine group The organopolysiloxane having ## STR3 ## is used in a range in which the molar ratio of the silanol (Si--OH) contained in the polymer of the component to the terminal group X of the component is 1 <(Si--OH) / X <10. And a condensation catalyst: 0.01-3 parts by weight of a homogeneous mixture.

In the formula of the resinous organosiloxane copolymer of the first component, each R is independently methyl, ethyl, propyl,
Such as an alkyl group such as isopropyl and hexyl, a cycloalkyl group such as cyclohexyl, an alkenyl group such as vinyl, allyl and peropenyl, and an aryl group such as phenyl.
A monovalent hydrocarbon group having 1 to 6 carbon atoms, or a chloromethyl group or 3,3,3-trifluoropropyl group in which a part or all of the hydrogen atoms of these groups are substituted with a halogen atom or the like. And other substituted monovalent hydrocarbon groups. The R groups may be the same or different.

Such a copolymer is substantially free of volatile components obtained by co-hydrolyzing and condensing a hydrolyzable triorgano-substituted silane with an R-group-free hydrolyzable silane in an organic solvent. , A material known in the technical field of organosilicon chemistry. The organic solvent is preferably one capable of dissolving the resin copolymer, and typical organic solvents include toluene, xylene, methylene chloride, naphtha mineral spirit and the like. In the present invention, instead of these organic solvents, low molecular weight siloxane and 50-2,00 at 25 ° C are used.
A second component organopolysiloxane having a viscosity of 0 cSt may be used.

The organopolysiloxane of the second component has an end blocked with a silyl group having a hydrolyzable functional group of any of an alkoxy group, an alkenyloxy group, an iminoxy group, an acyloxy group, an aminoxy group, and an amino group. formula Among them, the organopolysiloxanes of (3) and (4) are preferably those blocked with a silyl group having an alkoxy group.

R'in the above formulas are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms or a halogen-substituted hydrocarbon group, and specific examples thereof include alkyl such as methyl, ethyl, propyl and butyl. Groups, cycloalkyl groups such as cyclohexyl, alkenyl groups such as vinyl and allyl, aryl groups such as phenyl, or chloromethyl, chloropropyl, 1-substituted with all or part of the hydrogen atoms of these groups by halogen atoms. Chloro-2-methylpropyl, 3,3,
A group such as 3-trifluoropropyl may be mentioned. The R'groups may be the same or different, but are preferably methyl groups. Examples of the terminal group X include alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, methoxyethoxy, ethoxyethoxy, alkenyloxy groups such as vinyloxy, isopropenyloxy, isobutenyloxy, dimethylketoxime, methylethylketoxime, Iminooxy groups such as cyclohexanoxime, acetoxy groups, propionyloxy groups, acyloxy groups such as butyryloxy groups, N, N-dimethylaminoxy, N, N-diethylaminoxy and other aminoxy groups,
Examples thereof include hydrolyzable functional groups such as amino groups such as N, N-diethylamino and butylamino. Also, a is 0
Or 1.

The viscosity of the second component, an organopolysiloxane, is determined by n representing the number of repeating diorganosiloxane units in the above general formula, but it is preferable to select n that gives a viscosity of 300,000 cSt or less at 25 ° C. Particularly preferred is a fluid having a viscosity of 50 to 10,000 cSt at 25 ° C.

The amount of the second component used is ≡Si, which is the end group of the second component.
Silanol group (≡SiOH) contained in the first component for X
When the molar ratio is less than 1, the pressure-sensitive adhesive property is reduced although it becomes a rubber when cured. On the other hand, when the molar ratio is 10 or more, curing hardly occurs. SiOH / X <10, preferably 4 ≦ ≡SiOH / X ≦ 8.

The third component condensation catalyst is a metal of a carboxylic acid such as zinc octoate, lead 2-ethylhexanoate, dibutyltin diacetate, dibutyltin dilactate, stannous octoate, zinc naphthenate and ferrous octoate. It is selected from the group consisting of salts. The amount of the catalyst used is 0.01 to 3 parts by weight based on 100 parts by weight of the resin copolymer as the first component.

A dimethylpolysiloxane fluid end-capped with trimethylsilyl groups or a low molecular cyclic siloxane may be added to the composition of the present invention for the purpose of adjusting the viscosity. When adding it, it is effective to use one with a viscosity of 10-1,000 cSt at 25 ° C.

When using the composition of the present invention, an organic catalyst may be further added, but when curing, especially when curing by heating, waviness may occur due to evaporation of the solvent, so use with caution. is necessary.

Other materials known in the pressure sensitive adhesive industry, such as plasticizers, co-solvents, other silicone or organic pressure sensitive adhesives, etc., can be added to the composition of the present invention as needed. . Examples of organic pressure sensitive adhesives include natural rubber, styrene butadiene rubber, acrylonitrile rubber,
Examples thereof include polyurethane rubber and polyisobutylene. They have a dry tack on their own or develop such a tack by the addition of plasticizers.

The composition of the present invention comprises a water-soluble hydrocolloid such as guar gum, karaya gum, locust been gum, pectin, or mixtures thereof for imparting wet tack and water absorbency. May be included. Furthermore, hydrocolloids diluted with various solvents may be used for the purpose of accelerating curing, or may include reinforcing fillers or extending fillers such as fumed silica, precipitated silica, diatomaceous earth or pigments for the purpose of strengthening or extending. .

In preparing the pressure-sensitive adhesive composition of the present invention, the organopolysiloxane as the second component and the condensation catalyst as the third component need to be mixed at the time of use, and the components may be mixed in any order. Good. This is because the curing reaction starts when the organopolysiloxane fluid of the second component and the condensation catalyst of the third component coexist.

That is, since the condensation catalyst can be pre-mixed with the components other than the organopolysiloxane as the second component, when used, the components other than the condensation catalyst are uniformly mixed and then condensed with this mixture. Ideally, the mixture containing the catalyst is homogeneously mixed.

<< Advantages of the Invention >> The pressure-sensitive adhesive composition of the present invention has good workability because the viscosity of the composition can be adjusted to an appropriate level, and also has wet viscosity and dry tackiness. Since it can also be applied, its application range can be expanded more than ever before. Further, the cured product does not collapse even under wet conditions and has a long life.

<Examples> The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

All parts in the examples mean parts by weight.

Example 1 1,000 cP at 25 ° C. with the end blocked with a trimethoxysilyl group
To 100 parts of dimethylpolysiloxane polymer having a viscosity of trimethylsiloxy units ((CH ₃ ) ₃ SiO _1/2 units) and SiO _4/2 units, (CH ₃ ) ₃ SiO _1/2 / SiO _{4 / 2}
As shown in Table 1, a resinous siloxane copolymer having a molar ratio of 0.74, a silanol group content of 0.06 mol / 100 g, and a solid content of 60 wt% was dissolved in toluene.
A predetermined amount within the range of 100 parts to 600 parts was weighed and uniformly stirred and mixed, and then 0.1 part of dibutyldimethoxytin was added to 100 parts of the above mixture and further stirred uniformly.

Pour this on a frame of 25 mm × 100 mm × 2 mm, and carry out 7 at 20 ° C and 55RH%.
After curing for a day, the PET film was laminated with a load of 2 kg and left for 20 minutes or more. 300 mm / 1 in 180 degree direction
Peel force was measured at the rate of minutes.

The results are as shown in Table 1.

Example 2. 1,000 cP at 25 ° C. with the end blocked with a trimethoxysilyl group
To 100 parts of a dimethylpolysiloxane polymer having a viscosity of 200 parts, 200 parts of a resinous siloxane copolymer dissolved in toluene so as to have a solid content of 60% by weight was weighed and homogenized. After stirring to 100 parts of the above mixture dimethyldioctoxytin 0.1-0.9.
A predetermined amount was added within the range of parts, and the mixture was further uniformly mixed with stirring. Table 2 shows the measurement results obtained by curing this under the same conditions as in Example 1.

The results in Table 2 demonstrate that the adhesion is highly dependent on the amount of catalyst used.

Claims (2)

[Claims] 1. From an R ₃ SiO _1/2 unit (in the formula, each R independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms) and an SiO _4/2 unit. An organosiloxane polymer which becomes essentially and has a molar ratio of R ₃ SiO _1/2 units to each SiO _4/2 unit of 0.6-1.2 and having less than 0.7% by weight of hydroxysilyl groups: 100 parts by weight, average formula (In the formula, R'independently represents a monovalent hydrocarbon group having 1 to 6 carbon atoms or a halogen-substituted hydrocarbon group, and X is an alkoxy group, an alkenyloxy group, an iminoxy group, an acyloxy group, an aminoxy group, an amino group. An organopolysiloxane having at least one group selected from the group, a being 0 or 1 and n having an average value such that the organopolysiloxane has a viscosity of 50 to 300,000 cSt at 25 ° C.). The molar ratio of the silanol (Si-OH) contained in the polymer of the above component to the terminal group X of the component is 1 <
A pressure-sensitive adhesive composition containing (Si—OH) / X <10, and a condensation catalyst: 0.01-3 parts by weight. 2. A cured product obtained by curing the composition according to claim 1.