JPS63295690A - Polyester adhesive - Google Patents

Abstract

PURPOSE:To provide a polyester adhesive which enables high-strength and high-durability bonding with a metal by making use of a polyisocyanate compd. as a curing agent under mild conditions and which comprises as a main ingredient a product of a reaction of a thermoplastic polyester resin with a polyisocyanate compd. and an epoxy compd. CONSTITUTION:A thermoplastic polyester resin, a polyisocyanate compd., and an epoxy compd. are mixed and reacted with each other in a solution or in a molten state without use of a solvent. The reaction product is mixed with a polyisocyanate compd. as a curing agent to prepare a mixture for use as an adhesive. The mixing can be conducted at room temperature under atmospheric pressure. The adhesive thus prepared is applied to one or both of adherends and heated to 100-300 deg.C. The adherends are put on top of the other while slightly applying a pressure and then quenched, thereby completing the bonding. This adhesive exhibits excellent bonding strength and durability with respect to metals and plastics, and the bonding can be easily conducted under mild conditions as described above.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the invention (Field of industrial application) The present invention relates to a polyester adhesive that exhibits excellent properties in bonding plastics, metals, etc. The adhesive of the present invention is particularly useful for manufacturing various laminated products, and the laminated steel sheets manufactured with the adhesive of the present invention are used in a wide variety of applications, such as building materials, parts for automobiles, electrical products, etc. Therefore, the present invention is widely used in the steel industry, the civil engineering and construction industry, the automobile industry, and the like.

<Prior art> Adhesives made of polyester resin, or polyester resins containing isocyanate compounds or epoxy compounds, are used as adhesives when laminating metal plates or metal foils with plastic films, or when laminating different types of plastic films together. Polyester adhesives and the like that are simply mixed together are being considered. C Special Public Showa 4B
-57974, 48-57975).

However, as the field of use expands, adhesives with higher adhesive strength, durability, and workability are required, and conventional polyester adhesives cannot fully satisfy these demands.

In addition, PVC laminated steel sheets have conventionally been manufactured using a PVC sol coating method, but in recent years, a PVC sheet lamination method has been used to improve the aesthetic appearance of products and suitability for production lines. When making PVC laminated steel sheets using this method, two-component urethane adhesive,
Polyester adhesives or acrylic adhesives made by mixing polyester resin with a polyincyanate compound are being considered. However, the PVC laminated (M) plates manufactured by the PVC sheet lamination method using these adhesives have lower adhesive strength and adhesive durability between the PVC and steel plate than those manufactured by the PVC sol coating method. Another drawback is that the manufactured PVC laminated steel sheet is inferior in workability.

In addition, in the PVC sheet lamination method, adhesion between a PVC sheet and a steel plate requires conventional
Although this process is carried out at temperatures above 0°C, using such high temperatures will cause deterioration of the PVC during adhesion, and will also have an adverse effect on the embossed patterns on the surface of the PVC sheets, which will reduce the aesthetic appearance of the product. There is also the problem of loss.

<Problems to be Solved by the Invention> First, the purpose of the present invention is to eliminate the drawbacks in the production of PVC laminated steel sheets by the PVC sheet lamination method as shown in the above example, and to To provide an adhesive that enables bonding by heating over time, has excellent adhesive strength of the resulting bonded body and durability of the bonded part, and can manufacture a product with excellent workability. The second objective is to provide an adhesive that exhibits excellent properties by undergoing a crosslinking reaction when adhering various metals and plastics.

(b) Structure of the Invention and Means for Solving the Problems The inventors of the present invention sought to find an excellent adhesive that does not have the above-mentioned drawbacks. The present invention was based on the discovery that an adhesive containing a reaction product of
completed.

0 Thermoplastic polyester resin The thermoplastic polyester resin used in the present invention includes a tribasic acid and a glycol having 2 to 15 carbon atoms,
Examples include those obtained by appropriately selecting and combining oxyacids and polycondensing them by a conventional method.

Specific examples of tribasic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid,
Aromatic tribasic acids such as diphenyldicarboxylic acid, aliphatic tribasic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, conolilic acid, pimelic acid, speric acid, dimer acid, such as hexa Examples include alicyclic tribasic acids such as hydroterephthalic acid, hexahydroisophthalic acid, and hexahydrophthalic acid.

In addition, examples of glycol include ethylene glycol,
14-butanediol, hexamethylene glycol, neopentyl glycol, 1°4-cyclohexane dimetatool, 1,4-bisoxyethoxybenzene, bisphenol-A.

There are diethylene glycol, triethylene glycol, polyethylene glycol, etc. As oxy acids, p-
Oxybenzoic acid, '1,2-hydroxystearic acid,
Examples include p-β-oxyethoxybenzoic acid.

Furthermore, in addition to these tribasic acids, glycols, and oxyacids, thermoplastic polyester resins produced by adding, if necessary, compounds having an ester-forming group with a valence of 6 or more can also be used in the present invention. Examples of such compounds include trimethylolpropane, pentaerythritol, glycerin, trimellitic acid, and pyromellitic acid.

Among the thermoplastic polyester resins used in the present invention, preferred ones have a weight average molecular weight of 8000 to 100
Those with a melting point of preferably 60 to 250°C, more preferably 80 to 150°C, a hydroxyl value of 1.0 to 14, and a hydroxyl value of 1.0 to 14 are more preferable than oooo. Q (KOH119/l
) is preferred, and more preferably 1.4 to 8.0. As for the constituent components, those containing 20 to 100 moles of terephthalic acid residue as the acid component and 40 to 100 mole of ethylene glycol residue and neopentyl glycol residue as the polyol component are preferred. Further, although a random copolymerized thermoplastic polyester resin is usually used, a block-shaped resin can also be used.

0 Polyisocyanate compound The polyincyanate compound used to obtain the reaction product in the present invention is a compound having two or more incyanate groups in the molecule, such as 2.4-) lylene diisocyanate, 2.6- -1 lylene diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, mixtures thereof, adduct isocyanates obtained by adding these polyisocyanate compounds to polyols, or polymers of polyincyanate compounds etc. can be mentioned,
Further, a urethane prepolymer having an incyanate group as a terminal group can also be used.

On the other hand, as the polyisocyanate compound used as a curing agent, the same compounds as mentioned above can be mentioned.

However, it is not necessary that the polyisocyanate compound used to obtain the reaction product is the same as that used as the curing agent (although it is preferable that the polyisocyanate compound used as the curing agent is
It is an adduct isocyanate obtained by adding a polyisocyanate compound to a polyol, or a polymer of a polyincyanate compound.

O Epoxy compound The epoxy compound used in the present invention is a compound having an epoxy group in the molecule, and preferred compounds for the present invention have two or more epoxy groups and a molecular weight of 200 to 10.
000 compounds, and such compounds are described, for example, in "New Epoxy Resin" (edited by Hiroshi Strauchi, published by Shokodo, published in 1985). A specific example of such a compound is a bisphenol A type epoxy resin obtained by the reaction of bisphenol A and evichlorohydrin, and a commercially available product is Epicote 812.82.
0.827.828.1001.1004.1007.
1009 (both manufactured by Yuka Shell Epoxy ■). In addition, novolac-type epoxy resins obtained by the reaction of novolak etc. with evichlorohydrin, such as Epicote 154 (manufactured by Yuka Shell Epoxy ■), DER45
1,438 (all manufactured by Dow Chemical ■), Epotote YDCN701.702.703.704 (all manufactured by Tobu Kasei ■), and polyoxyalkylene type epoxy resins such as DER752,736 (all manufactured by Dow Chemical ■). Glycidylamine-based epoxy compounds obtained by the reaction of aromatic amine compounds or their hydrides with evichlorohydrin, such as Epicote 6
04 (Oilized shell epoxy ■ crack), TETRAD-X,
TETRAD-D (all manufactured by Mitsubishi Gas Chemical), GA
N, GOT (all manufactured by Nippon Kayaku ■), etc. However, the epoxy compounds used in the present invention are not limited to these, and two or more epoxy compounds can also be used in combination.Epoxy compounds with a molecular weight of 1000 to 4000 are particularly preferred as the epoxy compounds of the present invention. compound, or an epoxy compound with a molecular weight of 1000-4000 and a molecular weight of 200-4000
It is a mixture of 700 epoxy compounds.

9 Reaction product with thermoplastic polyester, polyisocyanate compound and epoxy compound is obtained by melt-mixing and reacting in solution or without using a solvent,
At this time, it is desirable to use an organometallic catalyst.

When obtaining a reaction product in such a reaction, the ratio of thermoplastic polyester resin and polyisocyanate compound is
It is preferable that the incyanate group of the polyincyanate compound is selected to be α2 to 4.0 equivalents, preferably tO to 2.5 equivalents, relative to the hydroxyl group to equivalent of the thermoplastic polyester resin. If the incyanate group is less than 0.2 equivalents, sufficient adhesive performance cannot be obtained, and if it is more than 4.0 equivalents, the molecular weight of the reaction product becomes too high, resulting in gelation and reduced workability. , good storage stability may not be obtained, and sufficient adhesion performance and processability during adhesion may be impaired. On the other hand, the amount of the epoxy compound used here is preferably 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the thermoplastic polyester resin. Here, if the amount of the epoxy compound is less than 1 part by weight, sufficient initial adhesive strength may not be obtained, and if it is more than 50 parts by weight, sufficient adhesive durability may not be obtained.

There is no particular restriction on the reaction temperature when the reaction is carried out in a solution, but it is preferably 70 to 150°C.

Moreover, the reaction time in that case is preferably (L5 to 15 hours, more preferably 2 to 8 hours).

On the other hand, when performing this reaction by melt mixing, the reaction temperature needs to be a temperature at which the thermoplastic polyester resin melts and has a viscosity that allows stirring, and although it may vary depending on the physical properties of the polyester resin, it is usually 80~600℃
, preferably 120 to 250°C. Moreover, the reaction time in this case is 0.5 to 15 hours, preferably 1 to 5 hours.

A common reactor or reaction tank is used to carry out such a reaction. For example, a reactor with a steam heating jacket, a condenser and a stirrer is used. At this time, the reaction system is preferably sealed with nitrogen.

The reaction procedure involves adding polyester resin,
The polyisocyanate compound and the epoxy compound may all be mixed together, or if the polyester resin and the polyisocyanate compound are reacted for 0.5 to 15 hours, the epoxy compound may be added in two or more portions. may be added.

For the reaction, ordinary catalysts may be used, such as tin, iron,
Any material can be used including cobalt. Typical catalysts include tin-based catalysts, such as dibutyltin malate, dibutyltin laurate malate, dibutyltin mercapto, dioctyltin dilaurate, and stannath octoate. However, in order to obtain usable stability when adding polyisocyanate when using an adhesive, it is desirable to use a catalyst that is deactivated after prepolymerization, such as stannous octoate.

0 Method of blending polyisocyanate compound into reaction product and adhesion method By blending the reaction product K obtained as described above with a polyisocyanate compound as a curing agent, it can be used as an adhesive. At this time, it is common to use a solution, but this is not always necessary.

The polyisocyanate compound used here is the compound described above, and the amount thereof is preferably 2 to 60 parts by weight, more preferably 5 parts by weight, based on 100 parts by weight of the reaction product. ~60 parts by weight.

Conventional methods can be used for blending the polyisocyanate compound into the reaction product. For example, when used as a solution, it can be mixed in a conventional stirring tank at room temperature and pressure. However, at this time, the polyisocyanate compound must be mixed uniformly.

Such formulation is preferably carried out immediately before use;
It is also possible to use a dispenser or the like to inject the two liquids from separate nozzles and mix them uniformly.

After applying the adhesive thus obtained to one or both adherends, if a solvent is used, it is dried at room temperature to 200°C, preferably 50 to 150°C. The temperature of the adherend coated with adhesive is 100 to 600℃, preferably 15℃.
The adherends are heated to a temperature of 0 to 250° C., and the adherends are brought together without applying a slight pressure, and then rapidly cooled to complete the adhesion.

Function> The adhesive of the present invention has a polyester resin as a base resin, and a polyisocyanate compound is blended at the time of use.
This is a type of adhesive that performs bonding by causing a curing reaction. However, in the present invention, by using a thermoplastic polyester resin, a reaction product of a polyisocyanate compound and an epoxy compound as the main ingredient, it is possible to use a conventional adhesive based on an unmodified polyester resin or a mere mixture thereof. It is possible to obtain an adhesive that has extremely high adhesive performance, adhesive durability, excellent workability, and storage stability that cannot be obtained with other methods.

The effects of the polyisocyanate compound and epoxy compound in the present invention are not necessarily clear, but are estimated as follows. By reacting the polyester resin and the polyisocyanate compound in advance in the reaction with the polyester resin, the unmodified polyester epoxy compound undergoes a reaction with the polyisocyanate compound or a reaction between the epoxy compounds to form a three-dimensional structure with higher density. By forming a network structure and improving the durability of the adhesive, and furthermore, by using an epoxy compound, the adhesiveness of the adhesive to metal is increased, and the adhesiveness to metal is improved. Due to these effects, the adhesive of the present invention has
When bonding metals, plastics, and glue, low-temperature heating is thought to provide strong adhesive strength and durability.

By further using a polyisocyanate compound as a curing agent in the reaction product, sufficient adhesive performance can be obtained, and unless the polyisocyanate compound is used as a curing agent, the desired effect of the present invention cannot be obtained.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the examples, parts indicate parts by weight.

Example 1 Dimethyl terephthalate 87.4 g (0.5 mol), ethylene glycol 67.0 N (12 mol), neopentyl glycol 74.9 # (0.8 mol) and tetra-n
- Add butoxytitanium α2I to the reaction vessel and add 140 to 1
The transesterification reaction was carried out at 90°C. Following this,
Add 74.8 g (0.5 mol) of isophthalic acid and add 190 ~
After carrying out the transesterification reaction at 210°C, the temperature was raised and the pressure reduced at the same time, and polymerization was carried out at a pressure of 5 m Hg and 210 to 70°C, resulting in a polymer with a molecular weight of 30,000% and a melting point of 115 to 125.
Thermoplastic polyester resin 4 having a temperature of 4.8 °C and a hydroxyl value of 4.8 was obtained.

The obtained polyester resin (A) 8ON was dissolved in a toluene-cyclohexanone mixed solvent dried using a molecular sheep. To this, diphenylmethane-4,4
'-diisocyanate (MDI) 2,1.9 (0,0
After adding O84 mol) and 2 drops of Stanus octoate, the mixture was refluxed for 3 hours under a nitrogen stream. After the reflux was completed, 20I of Epicor-1007 (epoxy resin manufactured by Yuka Shell Epoxy ■) was added, and after further refluxing for 3 hours, toluene and cyclohexanone were added to form a solution with a solid content of 60.

For 100 parts of the obtained reaction product solution, Coronate-
Add 10 parts of 2030 (polyisocyanate solution manufactured by Nippon Polyurethane Industry ■: 2.4-40% methylene chloride solution of lylene diisocyanate polymer) to a zinc-treated steel sheet so that the film thickness after drying is about 5 μm. Coated. This steel plate was heated for 30 seconds at a maximum temperature of 160°C, then a soft PVC sheet with a thickness of 02 mII was attached at 160°C, and immediately thereafter, it was rapidly cooled.

The thus obtained adhesive test piece was subjected to a 180° peeling test and an Erichsen test according to the method specified in JIS standard -6744. In addition, a similar test was conducted after immersing the adhesive test piece in boiling water for 2 hours. The results are shown in Table 1.

Example 2 Thermoplastic polyester resin (A) used in Example 1
, p was dried in toluene using Moller sheep.
Dissolved in cyclohexanone mixed solvent, MDI 2.1
i TETRAD-D (epoxy compound manufactured by Mitsubishi Gas Chemical Industry Co., Ltd.) 5.9 and 2 drops of Stanus octoate were added, and the mixture was refluxed for 6 hours under a nitrogen stream. After the reflux was completed, 10075 g of Epicor-1 was added and the mixture was refluxed for an additional 3 hours to prepare a solution with a solid content of 60%.

Coronate-205 was added to 100 parts of the obtained reaction product solution.
0 was added, and an adhesion test was conducted in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 1 Thermoplastic polyester resin GA) (7
)) Luene-cyclohexanone solution (solid content 30%) 1
Example 1 by adding 10 parts of Coronate-2030 to 00 parts.
An adhesion test was conducted in the same manner. The results are shown in Table 1.

Comparative Example 2 Thermoplastic polyester resin (A) 80 used in Example 1
Part, Epicote-100715 part and T);TRAD
-D 5 parts were dissolved in a toluene-cyclohexanone mixed solvent to form a solution with a solid content of 30. This melt fi100
10 parts of Coronet) was added to the sample, and an adhesion test was conducted in the same manner as in the example. The results are shown in Table 1.

Examples 6 to 8 Thermoplastic polyester resins (B) and (q) shown in Table 2 were synthesized under the same conditions as Example 1, and adhesives shown in Table 3 were prepared under the same conditions as Example 1.2. An adhesion test was conducted.

(C) Effects of the Invention The adhesive according to the present invention has excellent adhesive strength and durability to metals and plastics, and can be bonded easily and under mild conditions. Among these, in the production of vinyl chloride laminated steel plates, it is possible to bond by heating at a temperature of 180° C. or less and for a short time, and it is possible to produce vinyl chloride laminated steel plates with excellent appearance at low cost.

Furthermore, since the adhesive according to the present invention can be synthesized using general-purpose raw materials and ordinary equipment, it can be manufactured in large quantities at low cost, and is industrially useful. It's a big deal.

Claims (1)

[Claims] 1. A polyester adhesive characterized by having a reaction product of a thermoplastic polyester resin, a polyisocyanate compound, and an epoxy compound as a main ingredient and a polyisocyanate compound as a curing agent.