JPS5913555B2 - Heat-resistant curable formulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to certain adhesive and sealant compositions Σ having improved high temperature strength properties and improved resistance to thermal decay.

Adhesive and sealing materials based on acrylate and methacrylate monomers that can be polymerized by free radical initiation are known.

Similarly, anaerobic formulations are known (see, for example, US Pat. Nos. 5,289,5950, 3,043,82,0 and 3,218,305). Anaerobic formulations are liquid in the presence of air, but harden to form a strong bond when the air is removed, such as in the assembly of nuts and bolts to which they are applied. It is characterized by the ability to Although standard acrylate formulations and anaerobic arylate formulations are useful in many applications,
Its use is limited because its adhesive strength decreases at high temperatures, for example, above 25'F.

4 The present invention provides an adhesive sealing material that has significantly improved strength at high temperatures and improved resistance to thermal decay. This formulation consists of the following mixture: is a radical selected from the group consisting of m
is an integer at least equal to 1, n is an integer at least equal to 1, p is 0 or 1)]) Additive selected from the group consisting of A monomer selected from the group consisting of dimethacrylate, and an acrylic ester corresponding to the following formula. In the above formula, R is a group consisting of hydrogen, hydroxy alkyl of 1 to 4 carbon atoms, and lower The selected radicals, R' are hydrogen, halogen and 1-4
radicals selected from groups consisting of lower alkyl carbon atoms,
Bi is a radical selected from the group consisting of hydrogen, -0H, and m is an integer at least equal to 1, such as from 1 to 8 or more, including from 1 to about 4.

n is an integer at least equal to 1, such as from 1 to 20 or more. p is O or 1. )) Additives selected from the group consisting of: R and R' in the above are selected from the groups consisting of alkyl, cycloalkyl, aralkyl, alkaryl. The process of sealing or adhering surfaces involves applying a compound and curing the formulation by placing both surfaces in abutting relationship.

One type of monomer suitable for the practice of this invention includes acrylic esters having the general formula:

In the above formula, R is hydrogen, lower alkyl of 1 to 4 carbon atoms,
a radical selected from hydroxyalkyl of 1 to 4 carbon atoms, and a group consisting of, R' is a radical selected from a group consisting of hydrogen, halogen, and lower alkyl of 1 to 4 carbon atoms, Bi is hydrogen, -0H, and a radical selected from the group consisting of, m is an integer of at least 1, e.g. Either: 0, 10 The polymerized polyacrylic esters used according to the above general formula according to the present invention are, for example, as follows,
Non-limiting examples include: diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, di(pentamethylene glycol) dimethacrylate , tetraethylene diglycerol diacrylate, diglycerol tetramethacrylate,
Tetramethylene dimethacrylate, ethylene dimethacrylate, neopentyl glycol diacrylate and trimethylol propane triacrylate.

Among the above monomers, triethylene glycol dimethacrylate and polyethylene glycol dimethacrylate are preferred.
It is dimethacrylate. However, the most preferred class of monomers for the practice of this invention is ethoxylated bisphenol A dimethavrylate having the structural formula:

Another important component of the formulation is an additive that falls into one of the structures below.

The nature of R and R' is not important for the purposes of this invention;
It can be any organic radical that does not contain groups that adversely affect the desired polymers described herein.

Most commonly, R and R/ are selected from the groups consisting of alkyl, cycloalkyl, aralkyl, aralkyl,
Any of these may be very large radicals containing, for example, up to about 200 carbon atoms or more, preferably from 6 to about 100 carbon atoms, and most preferably from 6 to about 50 carbon atoms. Thermal oxidative decay resistance is R or R'
has been found to be improved when is aromatic.

However, this is generally not necessary for the improvements implemented in the present invention. Of course, both R and R' can be composed of relatively complex components, but must not contain any functionality that would interfere with the performance of the additive with respect to its intended purpose. The effective concentration range for this additive is from about 1% to about 50%, preferably from about 5% to about 35%, of the total formulation by weight.
shall be. Generally, the above formulations are easily cured by application of moderate heat.

Additionally, these formulations can be made anaerobic by including a peroxy initiator of free radical polymerization, which is a preferred embodiment of the present invention.

Several initiators of this type are known in the field of anaerobic technology. Examples include hydroperoxides such as cumene hydroperoxide, paratantane hydroperoxide, tert-butyl hydroperoxide, etc., and peracid esters which are hydrolyzed to form peroxides such as tert-butyl benzoate. The amount of such peroxy compounds can range from about 0.1 to about 10% by weight of the total formulation, preferably from about 1 to about 5%. It is advantageous to also include promoters of anaerobic polymerization.

Accelerators of this type include the various sulfimides (benzoic sulfimides) and secondary
, tertiary organic amines, etc. These may be used in concentrations ranging from about 0.1 to about 5%, preferably from about 1 to about 2%, of the total formulation by weight. In addition, thickeners, plasticizers, and the like are known in this field, and it is advantageous to include them if they are functionally preferable.

However, it must not interfere with the function of the additive with respect to its intended purpose. Of course, this can be determined by a simple experiment. The additives of the present invention improve at least three properties of the cured formulation, and the degree and nature of the improvement will likely vary depending on the particular monomer used.

Improvements include increased resistance to adhesion degradation due to oxidative effects that occur at elevated temperatures, increased bond or seal strength at elevated temperatures, and often improved cure strengths obtained at room temperature curing conditions. The exact nature of the mechanism of this improvement is not fully understood. While not wishing to be bound by any particular theory, it is believed that the additives of the present invention copolymerize with the monomers, thereby terminating the molecular "chatter" action that is thought to be a feature of thermal decomposition.
The improvement in hot strength is thought to be due to the increase in glass transition temperature brought about by the above-mentioned copolymerization. The following examples illustrate the invention without limiting it.

The percentages below are by weight based on the entire formulation. Example 1 An anaerobic composition was prepared by blending bisphenol A dimethacrylate with the following substances: Example: A sample corresponding to 30% of the additive in Appendix Table... was heated at 400°F for 2 hours.
Tested after aging for a week.

The test was conducted at 40'F, Break/Prevai
The l intensity was 180/235. The examples also demonstrate improved heat decay resistance, with Example H demonstrating the improved strength at high temperatures that is characteristic of the formulations of the invention.

M The above formulation was applied to steel pins and collars, which were then assembled and cured at room temperature for 24 hours to develop sufficient adhesive strength.

The samples were then aged at 450 degrees Fahrenheit for the period shown in Appendix 1. Next, it was allowed to cool to room temperature, and the pin was pushed out from the brim using an InstrOn tester. Attached Table 1 shows the results in terms of shear strength (Psi), showing a favorable improvement in heat aging resistance. A composition similar to Example 1 was prepared.

However, only Keramid6Ol was used as an additive, and the mono was polyethylene glycol dimethacrylate having a molecular weight of about 330.

Nuts and bolts made of 1/4-20 steel were joined using the formulation shown in the attached table. The samples were aged for a period of 400 minutes as indicated in the appendix, but as before, one test was carried out at room temperature. The previous table is “B”
The leak/prevai strength is expressed in foot-pounds. ``Break'' strength is the torque required to create the initial movement between the nut and bolt. 6 Prevai strength is the torque required to return the nut 180 degrees beyond the breaker point. .

A formulation according to claim 1, characterized in that:

(4) A formulation according to claim 1, characterized in that it contains a promoter of free radical polymerization.

(5) A formulation according to claim 2, characterized in that the monomer is ethoxylated bisphenol A.

(6) The formulation according to claim 2, characterized in that the monomer is polyethylene glycol dimethacrylate.

(7) The formulation according to claim 2, characterized in that the additive has the following formula:

(8) A formulation according to claim 2, characterized in that the initiator is cumene hydroperoxide.

(9) Applying the formulation of claim 1 to either of the surfaces, abutting the surfaces, and curing the formulation to have improved thermal properties between the interference-fit abutting surfaces. How to apply a seal.

(c) Applying the formulation of claim 2 to either of the surfaces, abutting the surfaces, and curing the formulation to provide improved thermal properties between the interference-fit abutting surfaces. How to apply a seal.

Claims (1)

[Scope of Claims] 1 (a) Ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate,
and acrylic acid esters corresponding to the following formulas ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the above formula, R is hydrogen, lower alkyl of 1 to 4 carbon atoms, 1 to 4 carbon atoms) Atomic hydroxy alkyl, and ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ Represents a radical selected from the group consisting of hydrogen, halogen, and lower alkyl of 1 to 4 carbon atoms, and R'' represents hydrogen , -OH and ▲Mathematical formulas, chemical formulas, tables, etc.▼ is a radical selected from the groups consisting of, where m is an integer at least equal to 1, n is an integer at least equal to 1, and p is 0 or 1). , (b) an additive selected from the group consisting of the following formula ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ (R and R' in the above formula are selected from the groups consisting of alkyl, cycloalkyl, aralkyl, alkaryl) Room temperature curing anaerobic with improved thermal properties compound. 2 (a) Ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate,
and monomers selected from groups consisting of acrylic esters corresponding to the following formulas, ▲ mathematical formulas, chemical formulas, tables, etc. ▼ (R in the above formula is hydrogen, lower alkyl of 1 to 4 carbon atoms, 1
A radical selected from the groups consisting of ~4 carbon atoms hydroxyalkyl, and ▲ mathematical formulas, chemical formulas, tables, etc. ▼ where R' is hydrogen,
It is a radical selected from a group consisting of halogen and lower alkyl of 1 to 4 carbon atoms, and R'' is a radical selected from a group consisting of hydrogen, -OH and ▲There are numerical formulas, chemical formulas, tables, etc. m is an integer at least equal to 1, n is an integer at least equal to 1, p is 0 or 1) (b) Additive selected from the group consisting of the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (above R and R′ of the formula are selected from the group consisting of alkyl, cycloalkyl, aralkyl, alkaryl) and (c)
A curable anaerobic adhesive sealant consisting of a mixture of peroxy initiators for free radical polymerization and capable of curing at room temperature when oxygen is substantially excluded.