JPH02202573A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a polyurethane-based adhesive composition, containing a specific polyol and polyisocyanate as constituent components, having form adhesive strength to metal and FRP and excellent in moisture, hot water and oil resistance. CONSTITUTION:The objective composition containing (A) a polyol having >=30mol%, preferably >=50mol% ring opening polymerization polyether structural units of epichlorohydrin in the backbone chain structural units and (B) a polyisocyanate (e.g. tolylene diisocyanate) as constituent components.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a novel product that has strong adhesive strength particularly to metals and FRP, and has excellent moisture resistance, hot water resistance, and oil resistance. The present invention relates to a polyurethane adhesive composition.

Polyurethane adhesives are suitable for metals, plastics, FRP,
It has good adhesion to most substances such as rubber, wood, and inorganic materials, and is flexible, so it is suitable for food packaging.
It is used in a wide range of industrial fields such as footwear, structural use, and wood, and the number of 7 types is expected to increase in the future.

Among these, in recent years, FRP has been rapidly applied as a structural agent liquid adhesive to the exterior panels of automobiles, vehicles, ships, etc., and polyurethane adhesives that have good adhesion to FRP are being used. Expectations are high.

[Prior art] Generally, polyurethane is based on the reaction of polyol and polyisocyanate, and each has a chemical structure of #t, a molecular weight,
By adjusting the number of functional groups, etc., they are designed and used in order to obtain the necessary physical properties for paints, adhesives, foams, etc.

In addition, polyurethane used as an adhesive basically has a main chain structure of propylene glycol as a polyol component.
Polyether polyols with a main chain having a multimer structure such as ethylene glycol, tetramethylene glycol, or caprolactone diol are used, and as a polyisocyanate component, diphenylmethane diisocyanate (
Various types are used including those having an aromatic group such as MDI).

Separate and store this image component as a main agent and hardening agent 2
The specifications are complex, but the basics include liquid type, two-part type and one-part type that use NCO-terminated prepolymers obtained by partially reacting image components in advance, and OH-terminated prepolymers. It is produced by the reaction of the above-mentioned polyol component and polyisocyanate component (Keiji Iwata, "Polyurethane Resin Handbook", Nikkan Kogyo Shimbun, pp. 438-475).

Although polyurethane adhesives obtained by these reactions have advantages, they are inferior to epoxy and acrylic adhesives, and are not fully satisfactory.

For example, polyurethane adhesives have high peel strength, but are inferior to epoxy adhesives in shear adhesive strength, and are also insufficient in moisture resistance and water resistance (especially against hot water), so they have particularly high properties. Currently, its use as a structural adhesive that requires

[Problems to be Solved by the Invention] An object of the present invention is to provide a polyurethane adhesive having excellent shear strength, moisture resistance, and water resistance.

[Means for Solving the Problems] As a result of intensive studies on the influence of the polyol component of polyurethane adhesives on adhesive strength, the present inventors have developed a method of adding polar groups to the side chains of the conventional polyether main chain. By introducing a completely new polyol component containing halogen in the side chain, we have developed an especially strong adhesive compared to polyurethane adhesives that use conventional polyol components. It has excellent adhesive strength, moisture resistance, and water resistance.
We have also developed a new urethane adhesive that has excellent oil resistance and is useful as a structural adhesive.

That is, the present invention is an adhesive composition comprising a polyurethane containing a polyol and a polyisocyanate in which ring-opening polymerized polyether structural units of epichlorohydrin account for 30 mol % or more of the main chain structural units, and a polyisocyanate.

The epichlorohydrin referred to in the present invention has the following structural formula (%) and is well known as a raw material for epoxy resins and epichlorohydrin rubber.

In particular, epichlorohydrin rubber is a polyether structure obtained by ring-opening polymerization of the epoxy group moiety of the above structural formula.

In the present invention, the polyol having a ring-opening polymerized polyether structure of epichlorohydrin refers to one whose main chain has a polyether structure formed by ring-opening polymerization of an epoxy group moiety, similar to epichlorohydrin rubber, but whose terminal end is always a hydroxyl group.

Such polyepichlorohydrin polyol, like other polyether compounds, is generally produced by ring-opening addition polymerization of epichlorohydrin using a Lewis acid as a catalyst and a low-molecular active hydrogen compound as a base to obtain the desired number of functional groups. , molecular weight polymers can be easily obtained.

The base low-molecular active hydrogen compound may be anything that reacts with epoxy groups, such as polyhydric alcohols, polyvalent amines, and polyhydric carboxylic acids, but usually low-molecular polyhydric alcohols are preferably used. Can be done.

For example, dihydric alcohols include ethylene glycol, throbylene glycol, diethylene glycol, trimethylene glycol, 1,3-butylene glycol, neopentyl glycol, 1,6-hexanediol, hisphenol A, bisphenol A ethylene glycol,
These include phlopylene gelicol adducts.

Further, examples of the trihydric alcohol include glycerin, trimethylolethane, and trimethylolpropane.

Furthermore, as alcohols with a valence of 4 or more, diglycerin,
Examples include pentaerydrift, dipentaerythritol, and nruvit. Which of these is used can be determined depending on the desired number of functional groups in the target epichlorohydrin ring-opening polymerized polyol.

Further, examples of the Lewis acid catalyst include BF.

Ether complexes, tin tetrachloride, etc. can be used.

In the present invention, not only a homopolymer of epichlorohydrin but also a copolymer in which the ring-opening polymer structure is present in the main chain at least 30 mol% or more, preferably 50 mol% or more can be used.

If this value is less than 30 mol%, the effect of improving adhesive strength will be reduced.

This value is the content in mol% of the total number of moles of structural units of the polyol material used.

Further, in the case of a copolymer, there is no particular restriction on the arrangement of the main chain structural units, and either a random copolymer or a block copolymer can be suitably used as the polyol of the present invention.

The epichlorohydrin copolymer used in the present invention is produced by the same method as described above, except that 70 mol% or less of epichlorohydrin is replaced with another epoxy compound in the epichlorohydrin homopolymer polymerization reaction. For example, if both monomers are mixed and reacted from the beginning, a random structure can be obtained.

The epichlorohydrin structural unit in the polyol polymer of the present invention has d-unit and l-unit isomers, and either isomer can be suitably used in the present invention.

Other epoxy compounds used in the copolymerization are not particularly limited as long as they are epoxy compounds such as ethylene oxide, propylene oxide, styrene oxide, allyl glycidyl ether, and phenyl glycidyl ether, but ethylene oxide and propylene oxide are particularly preferred. It can be suitably used.

When a polyol having a ring-opening polymerized polyether structural unit of epichlorohydrin used in the present invention in part or all of the main chain is used as a polyol component of a polyurethane adhesive, the molecular weight, number of functional groups, etc. of the target adhesive can be freely selected depending on the physical properties, pot life, etc., for example, the number of functional groups is 2 to 10, preferably 2 to 5, and the average molecular weight is 200 to 1oooo, preferably,
200 to 3000 can be used.

Among these, one type of epichlorohydrin ring-opening polymer may be used as the polymer component of the present invention, but in order to balance the desired properties of the adhesive, the molecular weight,
Two or more types of polyepichlorohydrin polyols having different numbers of functional groups or polyols such as polypropylene oxide, which have been conventionally used, can be suitably used in combination.

When such a polyol mixture is used, it is necessary from the viewpoint of physical properties that epichlorohydrin units should be present in the constituent units of the mixture as a whole in an amount of 30 mol % or more.

As the polyisocyanate compound used as the curing agent, all known incyanate compounds used in ordinary urethane adhesives can be used. For example, tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, liquid modified diphenylmethane diisocyanate], xylylene diisocyanate, naphthalene diisocyanate, impolone diisocyanate, hydrogenated diphenylmethane diisocyanate, polyphenylene polyphenyl polyisocyanate, triphenylmethane triisocyanate, tris (
Examples include p-incyanate phenyl)thiophosphate, an addition reaction product of polypropylene glycol or triol and tolylene diisocyanate, and an addition reaction product of trimethylolpropane and 3 mol of tolylene diisocyanate, and these can be used alone or as a mixture. The amount of these polyiso7anate compounds to be used is 0.8 to 10, preferably 1.2 to 5, in terms of molar ratio NC010H to the OH group of the polyol, similar to the formulation of ordinary urethane adhesives.

Two-component polyurethane adhesives have the above polyols and polyisocyanates as the main components, but they also contain other organic resins, pigments, curing catalysts, dehydrating agents, Additives etc. can be mixed.

Moreover, instead of directly using the polyol described above, a prepolymer chain-extended with an incyanate compound, that is, a polyurethane polyol or a polyurethane polyisocyanate, can be appropriately blended and used.

In this case, polyurethane polyisocyanate is moisture-curable by itself, and is a one-component moisture-curable type (notane-based adhesive or sealant, similar to the case of conventional polyols), but it has poor adhesive properties and water resistance. Similar to two-component polyurethane, it has excellent oil resistance.

The adhesive of the present invention can be used in various ways depending on the purpose without any change compared to conventional urethane adhesives.

For example, an adhesive composition is usually applied to the surface of the adherend and bonded together, but in order to adjust the viscosity, it is diluted with a solvent, applied with a roll coater or applicator, and then bonded after sprinkling with solvent. You can also take other methods. Further, a suitable brimer can be used depending on the base material.

The polyol claimed in the present invention is characterized by being a ring-opening polymerized polyether polyol of epichlorohydrin, but it is also possible to provide exactly the same characteristics by using epibromohydrin, which is a structural analogue of epichlorohydrin.

[Examples] The present invention will be explained in more detail below using Examples and Comparative Examples. These examples are provided for illustrative purposes and are not intended to limit the invention in any way.

Production Example 1 [Production of polyepichlorohydrin triol with a molecular weight of 400] 400 g of trimethylolpropane, 600 g of toluene,
5.6 g of B F s ether complex was charged into a 407 flask and dissolved.

While stirring this solution, add 8 ounces of epichlorohydrin to it.
80 g was added dropwise over 2 hours to cause a reaction.

At this time, if the dropping rate is increased, the reaction temperature will rise, so the temperature of the flask should be adjusted to 60°C while cooling in a water bath and adjusting the dropping rate.
I tried to keep it below ℃.

Bis-t-butylhydroxytoluene after completion of reaction: 10.
After adding 2g of the solution and neutralizing it with a 10% aqueous solution of Na2COs, toluene and water were azeotropically distilled to dehydrate and concentrate.
child .

This hot concentrated liquid was immediately filtered using a filter aid to obtain a transparent and viscous liquid 1220y. The hydroxyl value of this thing is 4
13.5, and the molecular weight calculated from this was 407. This is called polyol E-1.

The composition ratio of epichlorohydrin open deep polymerization structural units in the main chain of polyol E-1 is 100 mol%.

Production Example 2 [Production of polyepichlorohydrin triol having a molecular weight of 11000] Glycerin 276g, toluene 15009, BF.

8.4 g of ether complex was charged into 40 flasks and dissolved. While stirring this solution, add 30 ml of epichlorohydrin.
009 was added dropwise over 4 hours to react.

At the second time, the flask was cooled to maintain the reaction temperature below 60°C. Thereafter, the same procedure as in Production Example 1 was carried out to obtain 3075 g of a transparent and viscous liquid. The hydroxyl value of this thing is 16
4.2, and the molecular weight calculated from this was 1025. This is referred to as polyol E-2.

The composition ratio of epichlorohydrin ring-opening polymerized structural units in the main chain of polyol E-2 is 100 mol%.

Production Example 3 [Production of polyepichlorohydrin diol with a molecular weight of 2000] Ethylene glycol 62g, toluene 10509, BF
, 1.8 g of the ether complex was charged into a flask for 4 days and dissolved. While stirring this solution, add 2 ml of epichlorohydrin.
1509 was added dropwise over 3 hours to cause a reaction. At this time, the reaction was carried out while cooling so as to maintain the reaction temperature at 60°C or less.

The following process was carried out in the same manner as in Production Example 1 to obtain a transparent and viscous liquid 20
30g was obtained.

The hydroxyl value of this product was 55.3, and the molecular weight calculated from this was 2,030. This is referred to as polyol E-3. The composition ratio of epichlorohydrin ring-opening polymerized structural units in the main chain of polyol E-3 is 100 mol%.

Production Example 4 [Production of epichlorohydrin/propylene oxide copolymerized polyether triol with a molecular weight of 1000] Among the charges in Production Example 2, the reaction device was replaced with an autoclave equipped with a dropping device, and 3000 g of epichlorohydrin was replaced with 1650 g of epichlorohydrin and 1 propylene oxide. The preparation was carried out in exactly the same amount as in Production Example 2 except that the mixture was replaced with 847 g of oxide. The dropping time was 3.5 hours. After polymerization, the same treatment as in Production Example 1 was carried out to obtain a transparent and viscous liquid 3090y. The hydroxyl value of this product is 163.4, and the molecular weight calculated from this is 1
It was 030. This is referred to as polyol E-4.

The composition ratio of epichlorohydrin ring-opening polymerized structural units in the main chain of polyol E-4 was 55 mol%.

Examples 1 to 5 Adhesives were prepared using the polyols obtained in the above production examples and according to the formulations of the Examples and Comparative Examples shown in Table 1.

After thoroughly mixing the polyol component and the inorganic filler in advance, the mixture was further kneaded using three rolls to obtain a paste.

An inorganic moisture absorbent and a polyisocyanate compound were added to this and stirred well at room temperature to obtain an adhesive composition.

Using this adhesive composition, steel materials (JIS G-3141 5PCC) were bonded together and SMCs were bonded together, and the adhesive properties were evaluated. The results are shown in Table 2.

The test items and methods are described below.

・Substrate steel material, JIS G-31411) SPCCm plate (
Thickness t, 6 mm) was used. Pretreatment is JISK-68
48. SMC is S containing 30% glass fiber.
A flat plate with a thickness of 3 mm obtained by press-molding an MC compound was used.

- Initial adhesive strength After the curing time listed in Table 1, tensile shear joint strength (according to JISK-6850, tensile speed 5 mm 1 minute, measurement temperature 25°C), T-type peel adhesive strength (JISK-6854) compliant, pulling speed 50
mm1 minute, measurement temperature 25°C).

・Moisture deterioration resistance For those that have passed the curing time listed in Table 1,
After being exposed to 95% RH for 30 days, the tube was taken out and the tensile shear joint strength was immediately measured in the same manner as described for the initial adhesive strength.

・Hot water deterioration resistance 40% for those that have exceeded the curing time listed in Table 1
After being exposed to warm water at .degree. C. for 30 days, the tube was taken out and returned to room temperature, and the tensile shear joint strength was immediately measured in the same manner as described in the section on initial adhesive strength.

- Oil deterioration resistance JIS for those that have passed the curing time listed in Table 1
It was immersed in fuel oil B of K-6301 at 20°C for 14 days, then taken out, and the tensile shear joint strength was measured in the same manner as described in the measurement of initial adhesive strength.

(Left below) Examples 1 to 5 are examples in which a polyol having an epichlorohydrin ring-opening polymer structure was used as all or part of the polyol component of the adhesive.

In Comparative Examples 1 to 3, the same operations as in the Examples were performed except that conventionally used polyoxypropylene glycol and polyester polyol were used.

The results are shown in Tables 1 and 2.

As is clear from Table 2, in the case of the present invention using epichlorohydrin polyol, the initial adhesive strength, shear strength after hot water resistance test, shear strength after moisture resistance test, and oil resistance test are higher than when epichlorohydrin polyol is used. In contrast, Comparative Examples 1 to 4 had excellent initial adhesive strength, shear strength after hot water resistance and moisture resistance tests, shear strength after oil resistance tests, and peel strength. inferior to

[Effects of the Invention] The polyurethane adhesive composition of the present invention has excellent adhesive strength and durability such as hot water resistance, moisture resistance, and oil resistance, and can be applied as an adhesive for various structural materials. It is possible.

Claims (1)

[Claims] 1. A polyurethane adhesive composition comprising a polyol and a polyisocyanate in which ring-opening polymerized polyether structural units of epichlorohydrin account for 30 mol % or more of the main chain structural units, and a polyisocyanate.