Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-07-09
2001-10-23
Moore, Margaret (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S018000, C528S019000, C528S038000, C528S031000, C528S901000, C528S025000, C428S447000, C524S731000
Reexamination Certificate
active
06306999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a room temperature curable organopolysiloxane composition having rapid-curing performance and rapid adhesion development and suited as coatings on various substrates, in particular, rubber substrates.
2. Description of the Prior Art
Silicone type coating compositions have been used so that tack-free properties, lubricity and wear resistance can be imparted to the surfaces of rubber substrates or the like. In particular, diorganopolysiloxanes both-side terminated with hydroxyl groups, organopolysiloxanes and/or organoalkoxysilane containing hydrogen atoms bonded to silicone atoms (i.e., Si—H groups), and mixtures or reaction products of organopolysiloxanes containing organotin compounds, glycidoxy groups or epoxy groups such as epoxycyclohexyl groups with amino-group-containing alkoxysilanes and/or siloxanes (e.g., Japanese Patent Publications (Kokoku) No. 54-43023, No. 56-19813 and No. 56-47864) are improved in adhesion to substrates and also in wear resistance and lubricity.
However, such conventional silicone type coating compositions take fully twenty-four hours or longer until they become cured completely under room temperature conditions to develop adhesion properties, thus they have had a very poor operability. Also, when they are made into heat-curing types, they can rapidly cure and develop adhesion properties, but have had many problems such that assemblies and so forth for such heating impose a high cost and are unprofitable. Accordingly, proposed in Japanese Laying-open Patent Publication (Kokai) No. 5-279570 (JP 5-279570 A) is a room temperature curable organopolysiloxane composition containing a primary amine and a compound containing a C═O group. This composition, however, has insufficient adhesion development, lubricity and wear resistance.
Thus, it has strongly been sought to provide a material having both the rapid-curing performance (in particular, deep-curing performance) and the rapid adhesion development.
SUMMARY OF THE INVENTION
The present invention was made taking account of the above circumstances. Accordingly, an object of the present invention is to provide a room temperature curable organopolysiloxane composition with which cured films having superior tack-free properties, lubricity and wear resistance can be formed on the surfaces of various substrates, in particular, rubber substrates in higher rapid-curing performance and rapid adhesion development than ever.
To achieve the above object, the present invention provides a room temperature curable organopolysiloxane composition comprising:
(A) 100 parts by weight of a diorganopolysiloxane both-side terminated with hydroxyl groups, represented by the general formula (1):
HO(R
1
2
SiO)
n
H (1)
wherein R
1
represents a monovalent substituted or unsubstituted hydrocarbon group, and n represents an integer of 150 or more;
(B) from 1 part by weight to 30 parts by weight of an organohydrogenpolysiloxane having in one molecule at least three hydrogen atoms bonded to silicon atoms;
(C) from 5 parts by weight to 150 parts by weight of a compound selected from the group consisting of an organosilane having in one molecule at least two alkoxyl groups bonded to silicon atoms and containing at least one primary amino group bonded to a silicon atom through an alkylene group and a partial hydrolysis-condensation product thereof;
(D) from 0.1 part by weight to 15 parts by weight of a metal fatty acid salt; and
(E) an organic compound having at least one C═O group in one molecule, capable of reacting the primary amino group of the component (C) to form water; the compound being in such an amount that the C═O group is in a content of from 0.001 mole to 10 moles per mole of the primary amino group of the component (C).
The present composition may further comprise as component (F) a non-reactive diorganopolysiloxane represented by the general formula (2):
R
2
(R
2
2
SiO)
m
R
2
(2)
wherein R
2
represents a monovalent substituted or unsubstituted hydrocarbon group, and m represents an integer of 150 or more; in an amount of from 5 to 80 parts by weight based on 100 parts by weight of the component (A).
The present invention also provides an article comprising a substrate on which a cured film of the organopolysiloxane composition described above has been formed.
The present inventors have discovered that the primary amino group in the component-(C) primary-amino-group-containing organosilane and/or a partial hydrolysis-condensation product thereof reacts with the C═O group in the component-(E) C═O-group-containing organic compound at the time of mixing to form water and the water thus formed accelerates the curing reaction (curability) and development of adhesion properties of the composition, and also that the dehydration condensation reaction caused by using the component-(B) in combination cooperatively brings about an improvement in curing performance and adhesion properties. Thus, they have accomplished the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described below in detail.
The organopolysiloxane composition of the present invention is constituted of the following components (A) to (E), and may optionally further contain the following component (F).
Component (A)
The component-(A) diorganopolysiloxane both-side terminated with hydroxyl groups is a compound represented by the general formula (1) shown below, and is the main component that reacts with Si—H groups of the component-(B) and alkoxyl groups of the component-(C) to cure to form a film having especially good tack-free properties.
HO(R
1
2
SiO)
n
H (1)
Here, in the above formula, R
1
represents a monovalent substituted or unsubstituted hydrocarbon group, and may preferably be those having 1 to 8 carbon atoms, and particularly 1 to 6 carbon atoms, as exemplified by alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a benzyl group, a neopentyl group, a hexyl group, and a cyclohexyl group; an alkenyl groups such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group and a cyclohexyl group; aryl groups such as a phenyl group, a tolyl group, a xylyl group and a naphthyl group; aralkyl groups such as a styryl group, a benzyl group, a phenylethyl group and a phenylpropyl; and any of these hydrocarbon groups at least part of the hydrogen atoms of which has been substituted with a halogen atom such as a fluorine atom and a chlorine atom or with a nitrile group, e.g., a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group and a cyanoethyl group. If especially necessary in view of properties, part of R
1
(usually not more than 1 mole % of R
1
) may be a hydroxyl group or groups. Of these examples, substituted or unsubstituted alkyl groups (in particular, a methyl group) are preferred in view of the readiness for synthesis, the easiness to handle and the ability to endow the composition with good curing properties. Also, the letter symbol n, showing the degree of polymerization, is an integer of 150 or more, and may preferably selected within the range of from 150 to 20,000, and more preferably from 200 to 10,000. If n is less than 150, the film formed after curing may be brittle, and may be unable to correspond to any deformation of the substrate, resulting in a difficulty to handle. So long as the n is within the above range, the above organopolysiloxane may be used in combination of two or more types.
Component (B)
The component-(B) organohydrogenpolysiloxane used in the composition of the present invention is a compound having at least three, preferably 3 to 100 and more preferably 3 to 50 hydrogen atoms bonded to silicon atoms, and is a component that reacts with the hydroxyl groups bonded to silicon atoms in the component (A) (Si—OH groups) in the presence of the component-(D) metal fatty acid described later,
Ozai Toshiyuki
Shiono Mikio
Moore Margaret
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Shin-Etsu Chemical Co. , Ltd.
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