JPS6256192B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel pressure-sensitive adhesive composition, and more particularly to a pressure-sensitive adhesive composition containing a novel hydrogenated hydrocarbon resin. Traditionally, in the field of pressure sensitive adhesives and hot melt adhesives, products using rosin-based resins that rely on natural raw materials, such as rosin and rosin ester, have been used as tackifiers, but rosin-based resins has drawbacks such as unstable supply and high prices, and recently various petroleum-based hydrocarbon resins have been developed to replace them, one of which is cyclopentadiene such as cyclopentadiene and dicyclopentadiene. Hydrocarbon resins obtained by thermally polymerizing monomers have been developed, and adhesive compositions using them have been proposed. However, as the technology of adhesives and adhesives has become more sophisticated and their applications have become more diverse, more performance than ever before has become required. In addition to the three adhesive elements, aging resistance such as thermal stability and weather resistance is now required, and aging resistance is also required in the field of hot melt adhesives. For this reason, there has recently been a demand for tackifiers with excellent compatibility with base materials and aging resistance, and various attempts have been made to improve these properties. It is known that hydrogenation is also used in the case of resins to improve their aging resistance (UK patent no.
1317846 etc.). However, the hydrogenated cyclopentadiene resin obtained in this way has improved aging resistance and excellent adhesive performance compared to unhydrogenated resin, but it is not suitable for rubber or ethylene-vinyl acetate copolymer. It has some difficulty in compatibility with other substances, and its tackifying performance cannot always be said to fully meet market demands. Therefore, the present inventors conducted intensive studies to improve the shortcomings of cyclopentadiene resins and meet recent market demands. By copolymerizing a monovinyl-substituted aromatic hydrocarbon and then partially hydrogenating it, a hydrocarbon resin with unprecedented performance can be obtained, and by blending this into a base material, an excellent pressure-sensitive adhesive can be obtained. They discovered that a composition can be obtained and completed the present invention. An object of the present invention is to provide an adhesive that has excellent aging resistance such as thermal stability and weather resistance in addition to the three adhesive elements of tackiness, adhesion and holding power. The object of the present invention is to provide an adhesive composition comprising (a) a base material selected from rubber or a thermoplastic polymer and (b) a tackifier, in which the tackifier is a cyclopentadiene monomer and a monovinyl substituted A hydrogenated product of a thermal copolymer of aromatic hydrocarbons, containing 80 to 50% by weight of units derived from a cyclopentadiene monomer and then hydrogenated in the polymer chain and monovinyl-substituted aromatics. A bromine number of 0 to 3 containing 20 to 50% by weight of units derived from hydrocarbons and subsequently hydrogenated, a degree of aromatic ring hydrogenation of the units [] of 0 to 80% and a softening point of 60 to 160°C. This is achieved by a pressure-sensitive adhesive composition that is a hydrogenated hydrocarbon resin having the following properties. In the present invention, the adhesive includes pressure sensitive adhesives, hot melt adhesives, and the like. The base material in the present invention may be any material commonly used as a base material for pressure-sensitive adhesives. For example, when the pressure-sensitive adhesive is a pressure-sensitive adhesive, examples of the base material include natural rubber, polyisoprene rubber, Examples of base materials for hot melt adhesives include styrene-butadiene copolymer rubber and thermoplastic polymers such as polyethylene, ethylene-vinyl acetate copolymers, and atactic polypropylene. The hydrogenated hydrocarbon resin used as a tackifier in the present invention is obtained by preparing a monomer mixture of a cyclopentadiene monomer and a monovinyl-substituted aromatic hydrocarbon by a known method (for example, as disclosed in U.S. Pat. No. 2,689,232). 240-300°C, preferably 250-290°C in the absence of a radical initiator
It can be obtained by hydrogenating a resin with a softening point of 60 to 160°C obtained by thermal polymerization. The cyclopentadiene monomers used herein include cyclopentadiene, lower alkyl-substituted cyclopentadiene such as methyl-substituted and ethyl-substituted cyclopentadiene, and lower diels such as dimers, trimers, and coduplexes thereof. -Alder adducts are included, and monovinyl-substituted aromatic hydrocarbons include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, and the like. Of course, in addition to the cyclopentadiene monomer and the monovinyl-substituted aromatic hydrocarbon, copolymerizable comonomers such as indene, methylindene, and coumaron may coexist within the range that does not essentially impair the effects of the present invention. You may do so. In the present invention, hydrogenation of such hydrocarbon resins can be carried out using known methods such as nickel, palladium,
Hydrogenation is carried out using a catalyst such as cobalt, platinum, or rhodium in the presence or absence of a diluent at a temperature of 150 to 300°C. The hydrogenated hydrocarbon resin used in the present invention is derived from a cyclopentadiene monomer in the polymer chain, and then hydrogenated units []80 to 50% by weight, preferably 75 to 60% by weight and monovinyl Units derived from substituted aromatic hydrocarbons and subsequently hydrogenated [ ] 20-50% by weight, preferably 25
-40% by weight, bromine number 0-3, degree of aromatic ring hydrogenation of unit [ ] 0-80%, preferably 0-80%
50%, Gardner chromaticity 1 or less and softening point 60-160
It is a hydrogenated hydrocarbon resin with a temperature of ℃. The above "degree of aromatic ring hydrogenation" indicates the degree of hydrogenation of the aromatic ring derived from the monovinyl-substituted aromatic hydrocarbon, and was calculated based on the following formula according to the quantitative method of infrared absorption analysis. It is something. Degree of hydrogenation of aromatic ring (%) = D ₁ -Dx/D ₁ -D ₂ ×100 D; Absorbance = log (I ₀ /I) *The absorbance is calculated from the peak of the substituted aromatic ring at 900 cm ⁻¹ . * I ₀ ; Intensity of incident light I; Volume concentration * D ₁ : Absorbance when not hydrogenated D ₂ ; Absorbance when completely hydrogenated Dx: Absorbance at any degree of hydrogenation In the present invention, this aroma Ring hydrogenation degree is 0-80%
The lower the value, the better.If the value exceeds 80%, the rubber or This is not preferred because the compatibility with thermoplastic polymers is significantly reduced. On the other hand, unsaturated bonds other than aromatic rings need to be almost completely hydrogenated, and if the bromine number exceeds 3, the aging resistance, which is the main effect of the present invention, decreases. Furthermore, the hydrogenated hydrocarbon resin used in the present invention is
It is necessary to contain 20 to 50% of units derived from monovinyl-substituted aromatic hydrocarbons in the polymer chain; if it is less than 20%, the compatibility with the base material will be poor, and if it exceeds 50%. Thermal stability and weather resistance are significantly reduced. When the adhesive of the present invention is used in a pressure-sensitive adhesive, it is usually blended in a ratio of 30 to 250 parts by weight, preferably 50 to 200 parts by weight, of hydrogenated hydrocarbon resin to 100 parts by weight of rubber. It is prepared by At this time, the rubber and the hydrogenated hydrocarbon resin may be mixed by mechanical means such as a roll or Banbury, but it is usually carried out in a solvent that dissolves both the rubber and the resin. As the solvent, aliphatic, aromatic, alicyclic hydrocarbons and halogenated hydrocarbons such as pentane, hexane, heptane, benzene, toluene, xylene, cyclohexane, and chlorobenzene can be used, but the solvent is not particularly limited. The order of dissolving may be a method of adding the resin to the rubber solution, but since this method has the disadvantage of high solution viscosity, it is advantageous to dissolve the hydrogenated hydrocarbon resin in advance and then dissolve the rubber. Of course,
Both can be dissolved at the same time, or both can be mixed in a solution state. At this time, commonly used compounding agents such as process oil, anti-aging agent, and filler may be mixed. Mixing of rubber and resin in a solvent is usually carried out at room temperature;
There are no particular restrictions. A solution containing a mixture of rubber and resin is mixed with paper,
Tapes can be made by gluing it onto base materials such as cloth or plastic film and drying it. The pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets thus obtained exhibit excellent performance in terms of adhesive strength, adhesion strength, and holding power, as well as excellent performance in terms of aging resistance. The hot melt adhesive of the present invention usually contains 5 to 300 parts by weight of hydrogenated hydrocarbon resin per 100 parts by weight of the base material.
It is preferably obtained by blending in a proportion of 50 to 200 parts by weight. Of course, in addition to these, waxes such as paraffin wax, microcrystalline wax and polyethylene wax, antioxidants, plasticizers and fillers may be added as desired. The hot melt adhesive thus obtained has extremely excellent performance in both aging resistance and adhesive strength. The present invention will be explained in more detail with reference to Examples below. Note that parts and percentages in Examples and Reference Examples are based on weight unless otherwise specified. Reference Example 1 Dicyclopentadiene, styrene, and xylene were charged into an autoclave equipped with a stirrer in the proportions shown in Table 1, and heated gradually under a nitrogen atmosphere while stirring. After reaching 255°C, the mixture was allowed to react for 4 hours. Unreacted monomers, low polymers, and reaction solvents were removed by distillation to obtain four types of transparent hydrocarbon resins.

[Table] 300 parts of the hydrocarbon resin thus obtained, 200 parts of cyclohexane, and 7.5 parts of a hydrogenation catalyst (stabilized Nickel N-113; manufactured by JGC Chemical) were charged into an autoclave and under the conditions shown in Table 2. A hydrogenation reaction was performed, and after the reaction, the catalyst and solvent were removed from the reaction mixture to obtain a hydrogenated resin. The properties of this resin were measured by a predetermined method, and the results are shown in Table 2.

[Table] From these results, the hydrogenated hydrocarbon resin used in the present invention is compatible with natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and styrene-vinyl acetate copolymer (EVA). It can be seen that it also has excellent thermal stability and weather resistance. but,
For resins with low styrene content (hydrogenated resins
CH) has poor compatibility with SBR and EVA, and conversely, a resin with a high styrene content (hydrogenated resin DH) shows good compatibility but has poor thermal stability and weather resistance. Furthermore, when the aromatic ring is excessively hydrogenated (hydrogenated resin BH-6), the compatibility with SBR and EVA is also poor. Example 1 100 parts of natural rubber (Pale Crepe, ML-4=60) or SBR (SBR#1011, manufactured by Gutsudoritsuchi Chemical Co., Ltd.), 80 parts of hydrogenated hydrocarbon resin with a degree of aromatic ring hydrogenation of 50%, and 1020 parts of toluene. After preparing a mixed solution, this solution was applied to a 1 mm thick polyester film to a thickness of 30μ to make an adhesive tape, and its adhesive strength, adhesion strength, holding power, and weather resistance were evaluated. The properties and thermal stability were measured. In addition, the adhesive strength was determined by the J.Dow method [Proc.Inst.Rub.Ind.
, 1.105 (1954)], a 10 cm long adhesive tape was pasted on the slope of a stainless steel plate with an inclination of 30 degrees.
1/32 inch to 1 inch in diameter from 10 cm above the slope
Stainless steel balls of 32 different sizes up to inches are rolled at an initial speed of 0 and the size of the largest diameter ball that stops on the adhesive tape is indicated, and the adhesive strength is JIS Z.
-1522, adhesive tape was attached to a stainless steel plate polished with No. 280 water-resistant abrasive paper with a width of 25 mm and a length of 100 mm, at a speed of 200 mm/min at 25 °C.
Measured by peeling in a 180 degree direction, and the holding force is JIS Z
-25 on a similarly treated stainless steel plate according to -1524.
Adhesive tape was pasted so that the area of mm x 10 mm was in contact with each other, a load of 500 g was applied at 40°C, and the time until the adhesive tape slipped off was measured. In addition, weather resistance tests are performed by back irradiating ultraviolet rays using a fade meter, and the time required for the adhesive to seep out to the back side of the base material is measured.Furthermore, thermal stability tests are performed by testing adhesive tapes at 70°C in an air atmosphere. The adhesive strength was measured by the time taken to cause cohesive failure. The results are shown in Table-3.

[Table] This result shows that the pressure sensitive adhesive using the hydrogenated hydrocarbon resin of the present invention exhibits excellent performance in both natural rubber and SBR systems.
On the other hand, when a hydrogenated hydrocarbon resin with a low styrene content is used (formulation 1), the adhesion is inferior, whereas when a hydrogenated hydrocarbon resin with a high styrene content is used (formulation 4) However, it has poor weather resistance and thermal stability. Example 2 A test was conducted in exactly the same manner as in Example 1, except that various hydrogenated hydrocarbon resins having different degrees of aromatic ring hydrogenation were used, and the performance was evaluated. The results are shown in Table 4.

[Table] From these results, we can see that when using a resin with an insufficient degree of hydrogenation (formulation 5), the weather resistance and thermal stability are inferior, and when using an excessively hydrogenated resin (formulation 10) has poor adhesion and significantly lower compatibility with SBR. Example 3 40 parts of EVA (vinyl acetate content 28%, melt index 150), 40 parts of hydrogenated hydrocarbon resin with a degree of aromatic ring hydrogenation of 50%, and paraffin wax (melting point 145)
〓) A mixture obtained by melt-kneading 20 parts at 180℃,
Using an applicator, apply the film at 180℃ to an aluminum foil with a thickness of 0.1mm and a width of 25mm to a film thickness of 50μ, and then heat-press the two aluminum pieces at 140℃ for 1.5 seconds to create a test piece. , about this specimen
A 90 degree peel test was conducted according to ASTM D1876-61T to measure the peel strength. The thermal stability of the formulation is expressed by the Gardner color after being left in a perfect oven at 180°C in an air atmosphere for 24 hours. The time until gel formation was measured. The results are shown in Table-5.

[Table] This result shows that the hot melt adhesive using the hydrogenated hydrocarbon resin of the present invention has excellent adhesive strength and thermal stability. Example 4 A test was conducted in exactly the same manner as in Example 3, except that various hydrogenated hydrocarbon resins having different degrees of aromatic ring hydrogenation were used, and the performance was evaluated. The results are shown in Table-6.

[Table] From these results, it can be seen that when using a resin with a small degree of hydrogenation (formulation 15), the thermal stability is poor, and when using a resin with a high degree of hydrogenation (formulation 15), the thermal stability is poor.
20), it can be seen that the adhesive strength is significantly inferior.

Claims (1)

[Claims] 1. An adhesive composition comprising (a) a base material selected from rubber or a thermoplastic polymer and (b) a tackifier, wherein the tackifier is a cyclopentadiene monomer and a monovinyl-substituted aromatic hydrocarbon. 80 to 50% by weight of units derived from cyclopentadiene monomers and then hydrogenated in the polymer chain and derived from monovinyl-substituted aromatic hydrocarbons. bromine number 0 to 3, containing 20 to 50% by weight of units [ ] which are then hydrogenated, and a degree of hydrogenation of the aromatic ring of units [] 0 to 80%.
and a hydrogenated hydrocarbon resin having a softening point of 60 to 160°C.