JPH0739570B2 - Hot melt adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hot-melt (heat melting) type adhesive composition comprising an aromatic petroleum resin as a tackifier. More specifically, it is a polymer in which an aromatic ring is bonded via a methylene group, and has an aromatic petroleum resin as an essential component, which has no double bond and no oxygen atom or practically does not contain it. The present invention relates to a hot-melt type adhesive composition obtained by blending an ethylene-based copolymer and the like.

(Prior Art) Conventionally, a thermoplastic polymer material such as ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) and ethylene-acrylate copolymer is used as a base polymer, and a natural resin such as rosin and terpene is used as a base polymer. Alternatively, a composition prepared by blending a tackifier of synthetic resin such as various petroleum resins and, if necessary, various additives such as a viscosity modifier, a filler and a plasticizer is a hot melt type coating agent, an adhesive agent. It is used in a wide range of industrial fields such as bookbinding, can making, box making, bag making, woodworking, and packaging. Hot-melt type coating agents and adhesives are solid at room temperature and are solvent-free, so the risk of fire and poisoning is low, the adhesive set time is short, and the handling is easy. It has many advantages such as helping prevent air pollution.

Hot-melt type coating agents and adhesives are 150 to 200 ° C when used
It is heated and melted to a certain degree, applied to the adherend, and solidified by compressing and cooling to develop an adhesive force, so in order to obtain a product of stable quality, it must have excellent thermal stability. I have to. Therefore, the performance required for tackifier resins is that they have excellent thermal stability, and that they have good compatibility with base polymers and other compounding agents (viscosity modifiers, fillers, plasticizers, etc.). Those having excellent adhesiveness, adjusting the adhesive temperature, adjusting the melt viscosity to improve the workability, and useful for adjusting the hot tack and the open time are preferable.

Further, there is a demand for a compound which is useful for improving flexibility, cold resistance, weather resistance, blocking property, glossiness and the like of the compound.

(Problems to be solved by the invention) As a tackifier for EVA hot-melt type coating agent / adhesive, natural resin such as rosin or terpene is adhesive, flexibility at low temperature, etc. It is widely used because of its excellent heat resistance and weather resistance. However, since the heat stability and weather resistance are not sufficient, the resulting product has poor heat stability and weather resistance, and there is a problem that the hue deteriorates. Further, since these are made from natural products, they are expensive and unstable in supply.

As synthetic tackifiers, petroleum resins such as C ₅ , C ₉ type, C ₅ -C ₉ copolymer type and dicyclopentadiene type are mainly used. Since compatibility, heat stability, weather resistance, hue and odor are not always satisfactory, products using these are also inferior in terms of heat stability, weather resistance, hue and odor. It has drawbacks. Improvement methods such as maleic acid addition treatment (for example, Japanese Examined Patent Publication No. 51-13186) and hydrogenation treatment (for example, Japanese Examined Patent Publication No. 55-35065) have been proposed for the purpose of compensating for these defects, but it is necessary to add these secondary treatments. Leads to an increase in manufacturing cost, and is not a method that industrially has the great advantage of being a low-cost petroleum resin.

Among the petroleum resins, C ₉ (aromatic) petroleum resin has a relatively low molecular weight and a high softening point, and has a low melt viscosity. It is used as a hot-melt type coating agent and a tackifier for adhesives. Although it has favorable properties, the conventional C ₉ petroleum resin does not necessarily have sufficient performance in terms of compatibility with the base polymer, thermal stability, weather resistance, etc. Is.

It is said that the cause of poor thermal stability and weather resistance is the presence of a high degree of double bonds due to the diolefins contained in the feedstock.

As a method for improving this drawback, a method of strictly controlling the boiling point range of the feedstock to suppress the mixture of diolefins (for example, Japanese Examined Patent Publication No. 50-34078, Japanese Examined Patent Publication No. 58-25705, etc.), and the diolefin in the previous stage A method of polymerizing and removing an easily polymerizable compound centered on a class (for example, JP-B-49-2344) has been proposed. However, it is difficult to completely remove diolefins by either method.

In addition, the cause of the double bond is not necessarily caused only by the diolefins in the feedstock, but the aromatic olefins which are the feedstock themselves do not double in the polymerization process, so-called transfer reaction and termination reaction. It is known to cause binding. This double bond is essentially unavoidable as long as olefins are used as feedstock, but this double bond also adversely affects thermal stability and weather resistance.

Therefore, a method of secondary hydrogenation for the purpose of reducing double bonds (for example, JP-B-55-41635, JP-B-45-17075, JP-B-54-20972, etc.) is also performed. However, the hydrogenation reaction of C ₉ type petroleum resin generally requires severe hydrogenation conditions, and thus an increase in manufacturing cost is inevitable.

(Means for Solving Problems) The present inventor has found that hot melt type coating agents using conventional C ₉ petroleum resins, thermal stability, which is a defect of adhesives, weather resistance, and compatibility with base polymers. As a result of diligent research to improve the compatibility, the use of an aromatic petroleum resin having a special structure has excellent heat stability and weather resistance,
The inventors have completed and found a hot-melt adhesive composition having an adhesive performance equal to or higher than that of a hot-melt adhesive using a synthetic tackifier.

That is, the present invention is a polymer in which an aromatic ring is bonded via a methylene group, and has no double bond and oxygen atom at all, or contains a base polymer in an aromatic petroleum resin containing no practical use. It is a hot-melt type adhesive composition obtained by

The double bond here does not include a double bond of an aromatic ring, but refers to a double bond in a side chain of an aromatic ring, a naphthene ring or paraffin.

The aromatic petroleum resin used as a tackifier in the present invention is excellent in thermal stability and weather resistance due to the structural characteristics of the aromatic petroleum resin, and is also excellent in compatibility with the base polymer. Since it can be prepared in a wide range of blending ratios, the hot-melt adhesive composition according to the present invention has superior heat stability and weather resistance compared to conventional products, and it can be prepared from natural or conventional rosin-based or terpene-based compounds. It has adhesiveness equivalent to or higher than that using a synthetic tackifier such as petroleum resin.

(Function) The aromatic petroleum resin used in the present invention can be produced as follows. First, as an aromatic raw material, toluene, xylene, ethylenebenzene, methylethylbenzene, trimethylbenzene, durene, isodurene, etc., are substituted with 1 to 4 substituents having a relatively small number of carbon atoms such as a methyl group or an ethyl group on a benzene ring. There is no particular limitation so long as it is a derivative containing various condensed polycyclic aromatic compounds such as benzene derivative and indane derivative, naphthalene and anthracene, a mixture thereof or a fraction containing a part thereof.

Even if an aromatic compound having a substituent having a relatively large number of carbon atoms such as a propyl group or a butyl group or a non-aromatic compound such as paraffin or naphthene is contained, these compounds are not reactive with formaldehyde. Since it is low or does not exist at all, it simply acts as a solvent, and the apparent resin yield is reduced, but there is no particular problem as long as the above-mentioned reactive aromatic compound is contained in the feed oil. . However, it is necessary to consider the content of the reactive aromatic compound in the feedstock when determining the molar ratio of formaldehyde to the feedstock described below. Thus, generally, toluene, reforming-type or cracking-type mixed xylene fraction, C ₉ or C ₁₀ aromatic fraction obtained from bottom oil of kiresin production or isomerization, etc. are practically preferable feedstocks. .

Formaldehyde, which is one of the starting materials, may be in any form as a starting material as long as it produces monomeric formaldehyde in the reaction system. For example, commercially available various concentrations of formalin, trioxane, and paraformaldehyde can be used. Although such a polymer or the like can be used as it is, paraformaldehyde, which does not lower the catalyst concentration (formalin reduces the catalyst concentration because it is an aqueous solution) and is easily available at a low price, is most suitable. Also,
Gaseous formaldehyde separately generated by some method may be dissolved in a feed oil, a catalyst (if liquid), a solvent, etc. and charged into the reaction system.

The catalyst is not particularly limited as long as it is an acid catalyst, and sulfuric acid, phosphoric acid,
Pyrophosphoric acid, perchloric acid, aluminum chloride, boron trifluoride, etc. can be used. Sulfuric acid is advantageous because it is cheap and easy to reuse. The solvent is not particularly necessary because an excess amount of the raw material oil acts as a solvent, but an appropriate amount of a solvent that does not participate in the reaction (eg, isoparaffin) can be added if necessary.

In order to obtain an aromatic petroleum resin containing neither oxygen atom nor double bond, the molar ratio of formaldehyde to reactive aromatic compound needs to be suppressed to 1 or less, preferably 0.8 or less. Depending on the type of aromatic compound used as the raw material, generally, the lower the molar ratio, the lower the yield of the produced petroleum resin and the lower the softening point. The content can be decreased, and the higher the molar ratio, the higher the yield and the softening point, but the higher the content of oxygen atoms. Although it is possible to produce a petroleum resin even when the molar ratio is greater than 1, the content of oxygen atoms becomes high and the catalyst separation operation becomes difficult under the practical reaction conditions described below.

The amount of the catalyst used in this reaction cannot be unconditionally specified because it is closely related to the reaction conditions, but it is generally 5 to 50% by weight, preferably 15 to 50% by weight with respect to the reactive aromatic compound in the feed oil.
35% by weight is suitable.

The reaction temperature of this reaction cannot be unconditionally specified because it depends on the type and amount of feed oil and catalyst, etc.
60 to 180 ° C, preferably 80 to 120 ° C is used.

The reaction time for this reaction cannot be specified unconditionally because it depends on the type and amount of the feed oil and catalyst, and the oxygen content of the petroleum resin produced decreases with the reaction time. Can be regarded as not containing at all,
It is used for a period of time of lowering to 1.0% by weight or less, generally 0.5 to 10 hours, preferably 2 to 5 hours.

Catalyst removal of reaction products, washing (removal of trace acidic substances),
The desired aromatic petroleum resin is obtained by removing unreacted oil, solvent (when used) and light products.

The final distillation conditions cannot be unconditionally specified because it depends on the type of feed oil and the required properties of the target aromatic petroleum resin, but it is usually under a reduced pressure of 5 mmHg or less, preferably under a reduced pressure of 2 mmHg or less. The target aromatic petroleum resin is obtained by distilling off light components at a temperature of 300 to 470 ° C or lower.

The aromatic petroleum resin thus obtained is mainly composed of an oligomer having an aromatic ring and a methylene group alternately bonded to each other and having an aromatic ring or a methyl group at a terminal, and has no double bond or oxygen atom. It has no or practically no content, so it has better thermal stability and weather resistance than conventional C ₉ petroleum resins, and has a high softening point but a conventional molecular weight.
C ₉ based low for the base polymer than petroleum resins, especially EVA
Excellent compatibility with. The bromine number is 1.
It means that it is 0 or less, and that it has no oxygen atom or contains no oxygen atom in practice, it means that oxygen content is 1.0% by weight or less.

The base polymer used in the present invention is not particularly limited as long as it is a thermoplastic resin compatible with the aromatic petroleum resin, but generally EVA, ethylene-acrylate copolymer and the like. An ethylene-based copolymer can be preferably used.

The hot-melt adhesive composition of the present invention can be produced by melt-mixing the aromatic petroleum resin and the base polymer in a blending ratio according to the purpose. The blending ratio of the aromatic petroleum resin and the base polymer is 1: 100 to 200: 100 (weight ratio), preferably 5: 100 to 80: 100 (weight ratio),
If necessary, additives such as a plasticizer, a stabilizer, a filler and a viscosity modifier can be added in an arbitrary mixing ratio. Further, this aromatic petroleum resin can be mixed with a conventional tackifier at an arbitrary mixing ratio to help improve the performance of the conventional tackifier.

(Examples) Examples will be shown below for clarifying the content of the present invention, but the present invention is not limited thereto unless it exceeds the gist.

During the implementation, the softening point and bromine number of the produced aromatic petroleum resin were measured according to JIS K-2207 and JIS K-2605, respectively.
The oxygen content was measured with an elemental analyzer. The presence of an oligomer in which aromatic rings are bound via a methylene group indicates that elemental analysis, infrared spectroscopic analysis, nuclear magnetic resonance analysis, vapor pressure equilibrium method (VP
It was confirmed by O) analysis and structural analysis by gel permeation chromatography.

For thermal stability, 50 g of the sample is placed in a glass container (30 mmφ x 100 mm) and aged in a gear oven at 150 ° C.
The appearance and viscosity changes over time were measured. As for weather resistance, we made a coating film of 80-90μm on a glass plate and observed the change in hue when exposed in a sunshine weatherometer under the conditions of temperature 63 ° C, humidity 60%, spray cycle 18 minutes / 2 hours. .

The manufacturing method and properties are shown in Reference Examples 1 to 3.

Reference Example 1. 240 g of a C ₉ aromatic fraction having a boiling point range of 150 to 180 ° C. of the reforming bottom oil of xylene in a four-necked flask equipped with a stirrer and a reflux condenser, and a commercial industrial 92% paraformaldehyde. 20 g was added, and 75 g of commercially available 75% diluted sulfuric acid was added dropwise with slow stirring. After adding sulfuric acid, adjust the reaction temperature to 100 using an oil bath.
The temperature was raised to ~ 110 ° C and the reaction was continued for 3 hours with vigorous stirring. After completion of the reaction, the mixture was cooled to room temperature, and the contents were transferred to a dropping funnel and left to stand, so that a sulfuric acid layer was separated into a lower layer, which was removed.

Subsequently, washing with water was repeated 2-3 times until the pH of the washing water showed 7. Transfer the resulting oil layer to a distillation flask, initially about 10 mm
Finally, the pressure reduction degree was raised to 1 mmHg by vacuum distillation of Hg to remove light components below 300 ° C. at atmospheric pressure to obtain 125 g of the target aromatic petroleum resin in the bottom of the kettle. The resulting softening point of the petroleum resin is 80.5 ° C., Bromine Number 0.3g Br ₂ / 100g, oxygen Motoritsu is
It was 0.1% by weight or less, and it was clarified that neither oxygen atom nor double bond was contained practically.

Regarding the heat stability and weather resistance of the obtained petroleum resin,
Shown in the table.

Reference Example 2. Using the same equipment as in Reference Example 1, reaction and removal of catalyst and washing with water under the same feed oil and under the same conditions, finally, distilling light components under atmospheric pressure reduced to 360 ° C under reduced pressure of 1 mmHg. After removal, 134 g of the target aromatic petroleum resin was obtained. The resulting softening point of the petroleum resin is 88.5 ° C., Bromine Number 0.2g Br ₂ / 100g, oxygen Motoritsu was 0.1% by weight or less.

Regarding the heat stability and weather resistance of the obtained petroleum resin,
Shown in the table.

Reference Example 3. Using the same equipment as in Reference Example 1 and using 240 g of xylene fraction as a raw material under the same conditions as in Reference Example 1, reaction, removal of catalyst and washing with water were carried out, and then a light fraction at 450 ° C. or lower at atmospheric pressure was converted. Was distilled off under reduced pressure to obtain 98.2 g of the target aromatic petroleum resin. The petroleum resin obtained had a softening point of 92.0 ° C, a bromine number of 0.2gBr ₂ / 100g, and an oxygen content of 0.1% by weight or less.

The thermal stability and weather resistance of the obtained petroleum resin are shown in Table 1.

Reference Example 4. As a representative of conventional aromatic petroleum resins, a commercially available C ₉ petroleum resin (120 grade) was selected. The softening point was 122.0 ° C, the bromine number was 28.0g Br ₂ / 100g, and the oxygen content was 2.0g.

The thermal stability and weather resistance of this resin are shown in Table 1.

Reference Example 5. A commercially available hydrogenated rosin glycerin ester and a softening point of 78 ° C were selected as representatives of conventional natural resins. The thermal stability and weather resistance of this resin are shown in Table 1.

Examples 1 to 3 and Comparative Examples 1 to 2 In order to examine the compatibility between EVA and Reference Examples 1 to 5, compatibility tests with various commercially available grades of EVA were conducted.

The test conditions are as follows: EVA / tackifier (Reference Examples 1 to 5) 50:50
(Weight ratio) was melt-mixed, applied on a glass plate, cooled, and observed at room temperature. The results are shown in Table 2.

Examples 4 to 6 and Comparative Examples 3 to 4 EVA # 250 (vinyl acetate content 28%, melt index 15), 50 g and Reference Examples 1 to 1 for the purpose of investigating the performance as a hot melt adhesive composition. 5 tackifier, 50g and 140-1
Melt mixed at 60 ° C.

Usually, paraffin wax is also added for the purpose of adjusting viscosity, but the wax is not added here in order to clarify the characteristics of the tackifier.

Further, in the practice, the melt viscosity was measured by a melt flow index method at 140 ° C, and the compatibility and odor were visually and olfactoryly observed at the time of melting at 160 ° C. Regarding the thermal stability, the state of formation of insoluble matter was observed by heating with a gear aging tester at 200 ° C for 72 hours. Peeling adhesive strength is polyester film (thickness 38
μm) was coated with an applicator so that the adhesive layer would be 0.1 mm, heat-sealed at 120 ° C. for 2 seconds at ² kg / cm ² , and peeled with both hands to determine the relative strength. Shear strength is 25mm x 25mm thick on mild steel plate
It was measured by applying a 70 μm adhesive, pressing and cooling, and then peeling off at a speed of 5 mm / min. The results are shown in Table 3.

Example 7-11 Next, for the purpose of investigating the effect of the compounding ratio, EVA # 250 (vinyl acetate content 28%, melt index 15) and the tackifier of Reference Example 1 were melt mixed at various compounding ratios and hot mixed. The basic performance as a melt-type adhesive composition was examined. The results are shown in Table 4.

(Effects of the Invention) The hot-melt adhesive composition of the present invention is a blend of an aromatic petroleum resin and a base polymer which are excellent in thermal stability, weather resistance, and compatibility with the base polymer. Excellent heat stability, weather resistance, odor and peeling adhesive strength compared to _9- based petroleum resin blends, and superior thermal stability, weather resistance, odor and shear adhesive strength compared to natural resin blends ing.

Furthermore, since the hot-melt adhesive composition according to the present invention has excellent compatibility with the aromatic petroleum resin to be used, by adjusting the base polymer compounding amount and adding a small amount of polybutene or the like for adjusting the viscosity, The viscosity can be adjusted freely.

Therefore, the hot-melt adhesive composition according to the present invention,
Furthermore, by adding fillers, plasticizers, pigments, etc. according to the end use, a high-performance hot-melt type coating / adhesive for various uses can be finished.

Claims (3)

[Claims] 1. An ethylene petroleum resin containing an aromatic petroleum resin, which is a polymer in which an aromatic ring is bound through a methylene group and has no double bond and no oxygen atom, or which is practically not contained. A hot-melt type adhesive composition, which is blended into a coalescence. 2. The hot-melt adhesive composition according to claim 1, wherein the ethylene-based copolymer is an ethylene-vinyl acetate copolymer. 3. An aromatic petroleum resin is a polymer obtained by reacting an aromatic compound or a fraction containing an aromatic compound as a main component with formaldehyde in the presence of an acid catalyst. The hot melt-type adhesive composition described.