JPH04323291A - Reactive hot melt adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a reactive hot melt adhesive composition having excellent heat resistance and low toxicity. CONSTITUTION:A reactive hot melt adhesive composition consisting essentially of a curable resin composition comprising (A) a polyester which is a polyester having at least one silicon atom-containing group having a silicon atom bonded to a hydroxyl group or a hydrolyzable group and has a main chain of polymerization composed of epsilon-caprolactone and (B) a silanol condensation catalyst.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a reactive hot melt adhesive composition, and more specifically, a reactive hot melt adhesive composition that has improved heat resistance by causing a crosslinking reaction through siloxane bonds and forming a three-dimensional network structure. The present invention relates to adhesive compositions.

0002

[Prior art and problems to be solved by the invention] Generally,
Hot melt adhesives are solid at room temperature and are made of thermoplastic resins that do not contain water or solvents. By using such a hot melt adhesive, bonding can be performed quickly, and it has been adopted from the viewpoint of automation and labor saving of production lines. It is also widely accepted from the perspective of eliminating pollution.

[0003] However, the adhesion mechanism of hot melt adhesives is that they are melted by heat and solidified by cooling to exhibit adhesive properties, so their heat resistance after adhesion is limited and their range of use is limited. was.

Polyamide-based and polyester-based adhesives are currently being developed and marketed as hot-melt adhesives with improved heat resistance, but these adhesives have a melting temperature of 200 to 250°C. It is expensive and cannot be applied to adherends that are sensitive to heat. Furthermore, workability was poor due to the high viscosity.

[0005] Therefore, reactive hot melt adhesives, ie, heated and melted at a relatively low temperature, are applied to an adherend and then a crosslinking reaction is caused by an appropriate method to improve the heat resistance after adhesion. Adhesives have been developed.

One known example of a reactive hot melt adhesive is an aliphatic polyester-based prepolymer having an isocyanate group at the end (H.
F. Huber and H. Muller, A.D.
HESIVES AGES, NOVEMBER 1
987, 32). However, since the reactive hot melt adhesive has an isocyanate group, there is a problem with toxicity, which is contrary to the intention of eliminating pollution, which is a characteristic of hot melt adhesives. There are also problems with storage stability, and long-term storage is not possible.
Furthermore, the adhesive gelled during work, and although it was already on the market, it did not have sufficient performance, and its range of use was limited.

[0007] Also, as an adhesive containing a silicon atom to which a hydrolyzable group is bonded and crosslinked by siloxane bond,
H. F. Huber and H. Muller,
ADHESIVES AGES, NOVEMBER
1987, 32'' and Japanese Unexamined Patent Publication No. 172573/1987, however, since this adhesive uses isocyanate groups in the manufacturing stage, it does not have the above-mentioned problems, especially regarding toxicity. remains unresolved.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reactive hot melt adhesive composition that has excellent heat resistance and low toxicity.

That is, the reactive hot melt adhesive composition of the present invention comprises (A) a silicon atom-containing group containing a silicon atom to which a hydroxyl group or a hydrolyzable group is bonded (hereinafter referred to as "reactive silicon group");
A polyester polymer having at least one siloxane bond that can be crosslinked by forming a siloxane bond, the main chain of which contains a polymer of ε-caprolactone, and (B) a silanol condensation catalyst. The main component is a curable resin composition consisting of:

The reactive silicon group in component (A) of the composition of the present invention is not particularly limited, but representative examples include, for example, a group represented by the following general formula, chemical formula 1. Can be mentioned.

[0011]

[Chemical formula 1]

[In the formula, R1 and R2 are both an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or (R')3Si
It represents a triorganosiloxy group represented by O-, and when two or more R1 or R2 are present, they may be the same or different. Here R' is carbon number 1
~20 monovalent hydrocarbon groups, and the three R's may be the same or different. X represents a hydroxyl group or a hydrolyzable group, and when two or more X's are present, they may be the same or different. a is 0
, 1, 2 or 3, and b represents 0, 1 or 2, respectively. Also, m

[0013]

[Case 2]

b in [0014] may be different. m is 0
Indicates an integer between ~19. However, it is assumed that a+Σb≧1 is satisfied. ] The hydrolyzable group represented by X above is not particularly limited, and may be any conventionally known hydrolyzable group. Specific examples include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, and an alkenyloxy group. Among these, hydrogen atoms, alkoxy groups, acyloxy groups, ketoximate groups, amino groups, amido groups, aminooxy groups, mercapto groups and alkenyloxy groups are preferred, but alkoxy groups are preferable from the viewpoint of mild hydrolysis and ease of handling. is particularly preferred.

[0015] 1 to 3 of these hydrolyzable groups or hydroxyl groups can be bonded to one silicon atom, and (a+Σb) is 1 to 3.
Preferably, it is 5. When two or more hydrolyzable groups or hydroxyl groups exist on the same silicon atom, they may be the same or different.

There may be one silicon atom or two or more silicon atoms in the reactive silicon group, but in the case of a reactive silicon group in which silicon atoms are connected by siloxane bonds or the like, two or more silicon atoms may be present.
There may be about 0 pieces.

Note that a reactive silicon group represented by the following general formula, Chemical Formula 3, is preferred from the viewpoint of easy availability.

[0018]

[Chemical formula 3]

(In the formula, R2, cycloalkyl group such as, aryl group such as phenyl group, aralkyl group such as benzyl group, (R')3S where R' is a methyl group or phenyl group, etc.
Examples include a triorganosiloxy group represented by iO-. A methyl group is particularly preferred as R2.

[0020] At least one reactive silicon group, preferably 1.1 to 5 reactive silicon groups, should be present in one molecule of the polymer. When the number of reactive silicon groups contained in one polymer molecule is less than one, the curability becomes insufficient.

[0021] The reactive silicon group may be present at the end of the polymer molecular chain, may be present within the polymer chain, or may be present on both sides. In particular, when a reactive silicon group is present at the end of the molecular chain, the effective network chain amount of the polymer component contained in the final cured product increases, resulting in a cured product with excellent mechanical properties. It is preferable from the viewpoint that it becomes easier to obtain.

[0022] The reactive silicon group may be introduced into the above polymer by a known method. That is, for example, polycaprolactone having a functional group such as a hydroxyl group at the end is reacted with an organic compound having an active group and an unsaturated group that is reactive with this functional group, and then the resulting reaction product is Hydrosilylation may be carried out by using a hydrosilane having a hydrolyzable group.

[0023] Furthermore, by polymerizing ε-caprolactone using a diester compound having unsaturated groups at both ends such as diallylisophthalate as an initiator and carrying out a transesterification reaction, a diester compound having unsaturated groups at both ends is used as an initiator. Polycaprolactone may be synthesized and similarly hydrosilylated by the action of hydrosilane having a hydrolyzable group. Such hydrosilane is represented by the following general formula.

[0024]

[C4]

(In the formula, R3 is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and when two or more are present, they are the same and X is a hydroxyl group or a hydrolyzable group, and when two or more are present, they may be the same or different. a is 1, 2 or 3; ) Hydrosilylation reaction catalysts include, for example, H2PtCl6.6H2O, Pt metal, RhCl(PRh3)3, RhCl3, Rh/Al
2O3, RuCl3, IrCl3, FeCl3, AlC
l3, PdCl2・2H2O, NiCl2, TiCl4
Compounds such as can be used.

[0026] The hydrosilylation reaction is usually carried out at a temperature of 0 to 150
Although the reaction is carried out at 0.degree. C., a solvent such as benzene, toluene, xylene, or tetrahydrofuran may be used as necessary to adjust the reaction temperature or the viscosity of the reaction system.

The number average molecular weight of the ε-caprolactone polymer (before curing), which is the component (A), obtained as described above is 2, in order to impart sufficient mechanical strength and adhesive properties to the cured product. ,000 to 30,000, more preferably 4,000 to 20,000. If it is less than 2,000, the elongation of the cured product will be small, and breakage may occur before sufficient strength is developed. If it becomes 30,000, the crosslinking reaction will not be sufficient, sufficient mechanical strength will not be obtained, and adhesive strength will also become poor.

In order to obtain a cured product using the polymer of component (A) of the present invention, it is possible to condense hydroxyl groups or hydrolyzable groups with the silanol condensation catalyst (curing catalyst) of component (B). is necessary. Such silanol condensation catalysts include, for example, titanate esters such as tetrabutyl titanate and tetrapropyl titanate; tin carboxylates such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, tin octylate, and tin naphthenate; dibutyltin Reaction product of oxide and phthalate ester; dibutyltin diacetylacetonate; organoaluminum compounds such as aluminum trisacetylacetonate, aluminum trisethylacetoacetate, diisopropoxyaluminum ethylacetoacetate; zirconium tetraacetylacetonate, titanium Chelate compounds such as tetraacetylacetonate; lead octylate; butylamine, octylamine, laurylamine, dibutylamine, monoethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamine, cyclohexylamine,
Benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine,
diphenylguanidine, 2,4,6-tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-4-methylimidazole, 1,
8-Diazabicyclo[5.4.0]undecene-7(D
BU) or salts of these amine compounds with carboxylic acids; low molecular weight polyamide resins obtained from excess polyamines and polybasic acids; reaction products between excess polyamines and epoxy compounds; γ -A silane coupling agent having an amino group such as aminopropyltrimethoxysilane and N-(β-aminoethyl)aminopropylmethyldimethoxysilane; and other known silanol condensation catalysts such as other acidic catalysts and basic catalysts. Examples include silanol condensation catalysts. These catalysts may be used alone or in combination of two or more.

The amount of the curing catalyst (B) in the composition of the present invention is determined based on the amount of the polymer having reactive silicon groups (A).
) 100 parts by weight (hereinafter simply referred to as "parts"),
0.05 to 20 parts is preferable, and 0.1 to 10 parts is more preferable. If the amount of the curing catalyst is too small, the curing speed will be slow and the curing reaction will be difficult to proceed sufficiently, which is not preferable. On the other hand, if the amount of curing catalyst is too large,
This is undesirable because the curing speed increases, resulting in poor workability, and local heat generation and foaming occur during curing, making it difficult to obtain a good cured product.

[0030] The composition of the present invention may further contain adhesion improvers such as tackifiers and silane coupling agents, physical property modifiers, storage stability improvers, plasticizers, fillers,
Various additives such as anti-aging agents, ultraviolet absorbers, metal deactivators, anti-ozonants, light stabilizers, amine-based radical chain inhibitors, phosphorus-based peroxide decomposers, lubricants, pigments, foaming agents, etc. It may be added as appropriate.

[0031]

Effects of the Invention The reactive hot melt adhesive composition of the present invention has low toxicity and excellent heat resistance.

[0032]

EXAMPLES In order to further clarify the present invention, examples are given below.

Example 1 After purging a 5-liter stainless steel reactor (autoclave) with nitrogen gas, diallylisophthalate 85.
0 g and 3.52 ml of tetrabutoxy titanate were added. After stirring this at 170°C for 30 minutes, 3,938g of ε-caprolactone was added to 63g, 125g, 250g, 500g, 1
,000g and 2,000g were divided into 6 portions and sequentially added dropwise through a dropping funnel. Each drop interval was 6 minutes, 1
2 minutes, 25 minutes, 50 minutes, 100 minutes, and after the final drop,
The mixture was further heated and stirred at 170° C. for 200 minutes to obtain a polymer.

When the obtained polymer was analyzed by proton NMR, it was found that the average number of allyl ester groups in one molecule was 1.73.
It was confirmed that it is a polyester having individual ends. Furthermore, GPC analysis revealed that the number average molecular weight of this polymer was 10,600 in terms of polystyrene.

[0035] Subsequently, about 2 kg of the polymer in the reactor was taken out, leaving a remaining amount of 2 kg. Next, 2 liters of toluene was put into the reactor and stirred to form a homogeneous solution. The temperature inside the reactor was raised to 60° C., 0.356 ml of a 10% ethanol solution of chloroplatinic acid was added, and the mixture was stirred for 30 minutes. Next, 54.9 g of methyldimethoxysilane was added through the dropping funnel, and the mixture was reacted at 60° C. for 3 hours. Thereafter, excess methyldimethoxysilane and toluene were distilled off under reduced pressure to obtain a polyester having reactive silicon groups at the ends.

To 100 parts of the polyester polymer thus obtained, 0.2 parts of a tin octylate/laurylamine (3/0.75) mixed catalyst and 5 parts of a silane coupling agent were added as a condensation catalyst. was added, mixed at 80°C, and cooled to obtain a solid reactive hot melt adhesive composition.

[0037] The hot melt adhesive made of this composition was heated and melted to form an aluminum substrate (2.0 x 25 x 100
mm), pasted another aluminum substrate on top (adhesion margin 20 mm), and cured at 80°C for 5 days.
Both aluminum substrates were glued together.

Using a bonded aluminum substrate, -30
°C, 0 °C, room temperature (23 °C), 50 °C, 100 °C, 150
Tensile shear strength tests were conducted at temperatures of 200°C and 200°C. After holding each temperature for 30 minutes, the tensile shear strength was measured using an autograph. The results are listed in Table 1.

[0039]

[Table 1]

As is clear from Table 1, the bonded portion does not melt even at temperatures above 100° C., maintains sufficient mechanical strength, and has excellent heat resistance.

Claims (1)

[Claims] Claim 1: (A) A polyester polymer having at least one silicon atom-containing group containing a silicon atom to which a hydroxyl group or a hydrolyzable group is bonded, and which can be crosslinked by forming a siloxane bond; A reactive hot melt adhesive composition whose main components are a polyester polymer whose main chain is a polymer of ε-caprolactone, and (B) a curable resin composition containing a silanol condensation catalyst.