JP7697252B2 - Adhesive rubber composition - Google Patents

Description

The present invention relates to an adhesive rubber composition containing a diene rubber, a C5-dicyclopentadiene copolymer resin, and a process oil, and in particular to an adhesive rubber composition that has an excellent balance of appropriate tack (initial adhesion), adhesion, and retention (retention, cohesion), and can be used as an adhesive.

Adhesives are capable of adhering (bonding) at room temperature by simply applying slight pressure for a short period of time, without the use of water, solvents, or heat. General adhesives are applied to plastic films, cellophane, paper, cloth, etc., and are processed into a variety of adhesive products for use as various adhesive tapes, adhesive labels, and adhesive sheets.

These adhesives are known to be adhesive compositions that are based on various diene rubbers and optionally contain tackifiers, crosslinking agents, stabilizers, plasticizers, etc., and petroleum resins are known as tackifiers.

The petroleum resins in this case are obtained by polymerizing unsaturated hydrocarbon-containing fractions obtained during the cracking and refining of petroleum products, and a well-known manufacturing method involves using unsaturated hydrocarbon-containing fractions as a raw material and polymerizing them in the presence of a Friedel-Crafts catalyst. The hydrocarbon-containing fractions are generally of two types, with boiling points ranging from 20 to 110°C (sometimes called C5 fractions) and 140 to 280°C (sometimes called C9 fractions). Petroleum resins obtained from C5 fractions are classified as aliphatic petroleum resins, petroleum resins obtained from C9 fractions as aromatic petroleum resins, and petroleum resins obtained by copolymerizing C5 fractions and C9 fractions as aliphatic-aromatic copolymer petroleum resins. DCPD polymers obtained by thermally polymerizing dicyclopentadiene (sometimes called DCPD) are sometimes called alicyclic petroleum resins.

Among these, adhesive compositions have been proposed that contain a styrene-isoprene-styrene type block copolymer and, as a tackifier, an aliphatic-alicyclic copolymerized petroleum resin, an aliphatic-aromatic-dicyclopentadiene copolymerized petroleum resin, or the like (see, for example, Patent Documents 1 and 2). In addition, a solvent-based natural rubber adhesive that contains a terpene resin as a tackifier resin has been proposed (see, for example, Patent Document 3).

JP 2010-132761 A JP 2018-083857 A Special Publication No. 08-009709

However, the adhesive compositions proposed in Patent Documents 1 and 2 use thermoplastic elastomers as the main base polymer, and no consideration is given to adhesive compositions using diene rubbers. The proposal in Patent Document 3 does not consider tackifier resins, particularly petroleum resins, or their effects, and there is room for improvement in the balance between color tone and adhesive properties as an adhesive.

Therefore, the present invention has been made in consideration of the above problems, and aims to provide an adhesive rubber composition having adhesiveness with an excellent balance of appropriate tack, adhesive strength, and retention, and an adhesive made from the same.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that a rubber composition containing a diene rubber, a specific amount of C5-DCPD copolymer resin, and process oil exhibits excellent adhesion properties, which led to the completion of the present invention.

That is, the present invention relates to an adhesive rubber composition that contains 70 to 130 parts by weight of C5-DCPD copolymer resin and 5 to 50 parts by weight of process oil per 100 parts by weight of diene rubber, and an adhesive comprising the same.

The present invention is described in detail below.

The adhesive rubber composition of the present invention contains 70 to 130 parts by weight of C5-DCPD copolymer resin and 5 to 50 parts by weight of process oil per 100 parts by weight of diene rubber.

The diene rubber constituting the adhesive rubber composition of the present invention is not limited as long as it is in the category of diene rubber having a carbon-carbon double bond, and examples thereof include natural rubber (sometimes referred to as NR), polyisoprene rubber (sometimes referred to as IR), polybutadiene rubber (sometimes referred to as BR), and styrene-butadiene copolymer rubber (sometimes referred to as SBR). These may be used alone or in combination. There is no particular restriction on the method of producing the diene rubber, and it may be an anionic polymer or an emulsion polymer. There is no particular restriction on the molecular weight or microstructure, and it may be terminally modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl, or the like, or epoxidized, and commercially available products may be used.

The C5-DCPD copolymer resin constituting the adhesive rubber composition of the present invention is a resin obtained by copolymerizing a C5 fraction, which is a fraction with a boiling point range of 20 to 110°C obtained by thermal decomposition of petroleum, with DCPD, which is a dicyclopentadiene. In this case, the C5 fraction can be a fraction with a boiling point range of 20 to 110°C, and the components of the C5 fraction include, for example, aliphatic compounds with a carbon number of 4 such as butene, butadiene, and isobutene; linear aliphatic compounds with a carbon number of 5 such as 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, and piperylene; 1-hexene, 2-hexene, 3-hexene, 2-methyl-1-pentene, 3-methyl-1-pentene, and 4-methyl-1-pentene. , 2-methyl-2-pentene, 3-methyl-2-pentene, 4-methyl-2-pentene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, and other linear aliphatic compounds having 6 carbon atoms; cyclic aliphatic compounds having 6 carbon atoms, such as methylcyclopentadiene; and linear aliphatic compounds having 7 carbon atoms, such as 1-heptene, 2-heptene, 3-heptene, 2-methyl-3-hexene, 4-methyl-2-hexene, and 3,4-dimethyl-2-pentene. DCPD may be dicyclopentadiene alone or a (di)cyclopentadiene fraction, which is a fraction of thermal cracking of petroleum, and may contain, for example, methyldicyclopentadiene, dimethyldicyclopentadiene, cyclopentadiene, and methylcyclopentadiene.

The C5-DCPD copolymer resin does not exclude the inclusion of C9 components in the range that does not affect the copolymerization component within the scope of the present invention, but in order to achieve particularly excellent color tone and rubber modification effects, particularly adhesive properties, it is preferable that the resin does not contain a fraction with a boiling point range of 140 to 280°C in petroleum cracking fractions (usually referred to as a C9 fraction or aromatic component fraction) as a component.

As a method for producing the C5-DCPD copolymer resin, any method that can produce a C5-DCPD copolymer resin may be used. For example, a method can be used in which a C5 fraction, DCPD, and a saturated hydrocarbon of a C5 fraction such as n-pentane are used as a solvent, and a polymerization reaction is carried out using a polymerization catalyst. The polymerization catalyst in this case is not particularly limited, and examples thereof include aluminum trichloride, aluminum tribromide, boron trifluoride or complexes thereof, and among these, alcohol and phenol complexes of boron trifluoride such as methanol, propanol, butanol, isobutanol, isopentanol, and phenol are selected because of their excellent catalytic activity. Among these, butanol, isobutanol, and isopentanol are more preferable. The complex may be used as it is, or may be prepared in-suit from boron trifluoride and alcohols or phenols immediately before use. Furthermore, the feedstock is preferably a mixture of 25 to 70% by weight of C5 fraction and 75 to 30% by weight of DCPD fraction, since a C5-DCPD copolymer resin with excellent softening point and color can be obtained. Furthermore, the polymerization temperature is not particularly limited, and is preferably 20 to 80°C, and more preferably 30 to 60°C, since it provides high polymerization activity and excellent productivity. The amount of polymerization catalyst, polymerization time, etc. can be appropriately selected depending on the temperature and the water concentration in the feedstock. In general, for example, 0.1 to 2.0% by weight of polymerization catalyst relative to the feedstock and 0.1 to 10 hours of polymerization time are preferred. There is no particular restriction on the reaction pressure, and atmospheric pressure to 1 MPa is preferred. There is no particular restriction on the atmosphere, and a nitrogen atmosphere is preferred.

The C5-DCPD copolymer resin is preferably an adhesive rubber composition with excellent tack and retention properties, and therefore has a double bond hydrogen area in the peak area measured with a proton nuclear magnetic resonance spectrometer of 6 to 13%, and more preferably 8 to 11%. The proton nuclear magnetic resonance spectrum in this case can be measured, for example, with a 400 MHz proton nuclear magnetic resonance spectrometer.

And, since it is an adhesive rubber composition having excellent adhesive performance, color tone, and thermal stability, it is preferable that the olefinic double bond / dicyclopentadiene residue double bond (area ratio) in the proton nuclear magnetic resonance spectrum is 30/70 to 75/25, particularly preferably 40/60 to 60/40, and the weight average molecular weight measured by gel permeation chromatography in accordance with JIS K-0124 (2011) using standard polystyrene as the standard substance is preferably 1200 to 2500, particularly preferably within the range of 1600 to 2100, and further the weight average molecular weight / number average molecular weight is preferably 1.5 to 2.5, particularly preferably 1.7 to 2.2. Furthermore, the bromine number measured in accordance with JIS K-2605 (1996) is preferably 40 to 55 (g-Br ₂ /100 g), and the softening point measured in accordance with JIS K-2207 (1996) (ring and ball method) is preferably 80 to 125° C.

Furthermore, since this will result in an adhesive rubber composition with excellent appearance, it is preferable that the hue (Gardner hue) measured in accordance with ASTM D-1544-63T in a 50% by weight toluene solution is 4 to 9.

The adhesive rubber composition of the present invention contains 70 to 130 parts by weight of C5-DCPD copolymer resin per 100 parts by weight of diene rubber. If the amount of C5-DCPD copolymer resin is less than 70 parts by weight, the resulting composition will have high adhesive retention and poor adhesive performance, whereas if the amount of C5-DCPD copolymer resin is more than 130 parts by weight, the resulting composition will have a poor balance between tack and retention.

The process oil constituting the adhesive rubber composition of the present invention may be any oil that falls within the category known as a process oil, such as paraffinic process oil, naphthenic process oil, aromatic process oil, liquid polybutene, modified liquid polybutene, and hydrocarbon-based synthetic lubricating oils such as ethylene-α-olefin copolymers. Among these process oils, paraffinic process oil, naphthenic process oil, and aromatic process oil are preferred, with naphthenic process oil being particularly preferred, as they result in an adhesive rubber composition with better balance.

Specific examples of paraffin-based process oils include (product names) Diana Process Oil PW-32, PW-90, PW-150, PW-380, PS-32, PS-90, PS-380, PS-430, PX-32, PX-90 (manufactured by Idemitsu Kosan Co., Ltd.), (product names) Stanol 40, 43N, 52, 69, 149, LP40, LP69, Flexon 845 (manufactured by Esso Sekiyu Co., Ltd.), (product names) Syntac PA-95, PA-100, PA-140 (manufactured by Kobe Oil Chemical Industry Co., Ltd.), and (product names) Cosmo Process 10, 40, 4 0C (manufactured by Cosmo Oil Co., Ltd.), (trade name) Lubflex 26, 100, 400 (manufactured by Shell Japan K.K.), (trade name) Kyoseki Process P-200, P-300, P-500 (manufactured by Nikko Kyoseki Co., Ltd.), and the like. Specific examples of naphthenic process oils include (trade name) Diana Process Oil NS-24, NS-100, NM-26, NM-68, NM-150, NM-280, NP-24, NU-80, NF-90 (manufactured by Idemitsu Kosan Co., Ltd.), (trade name) Esso Process Oil 725, 765 (manufactured by Esso Oil Co., Ltd.), and the like. ), (product name) Syntac N-40, N-60, N-70, N-75, N-85 (manufactured by Kobe Oil Chemical Industry Co., Ltd.), (product name) Shellflex 371JY, 371N, 451, N-40, 22, 22R, 32R, 100R, 100S, 100SA, 220RS, 220S, 260, 320R, 680 (manufactured by Shell Japan Co., Ltd.), (product name) Kyoseki Process R-50, R-200, R-1000 (manufactured by Nikko Kyoseki Co., Ltd.), and the like can be mentioned. Examples of aromatic process oils include (product name) Diana Process Oil AC-12, A Examples include C-460, AE-24, AE-50, AE-200, AH-16, and AH-58 (manufactured by Idemitsu Kosan Co., Ltd.), (product name) Esso Process Oil 110 and 120 (manufactured by Esso Sekiyu Co., Ltd.), (product name) Syntac HA-10, HA-15, HA-30, and HA-35 (manufactured by Kobe Oil Chemical Industry Co., Ltd.), (product name) Cosmo Process 40A (manufactured by Cosmo Oil Co., Ltd.), (product name) Dewtrex 729UK and 739 (manufactured by Shell Japan Co., Ltd.), and (product name) Kyoseki Process X100-A and X100 (manufactured by Nikko Kyoseki Co., Ltd.).

The adhesive rubber composition of the present invention contains 5 to 50 parts by weight of process oil per 100 parts by weight of diene rubber. If the amount of process oil is less than 5 parts by weight, the resulting composition will have poor plasticity and insufficient tack. On the other hand, if the amount of process oil is more than 50 parts by weight, the resulting composition will be overly plasticized and will have poor adhesion and retention.

Furthermore, since the adhesive rubber composition of the present invention is provided with thermal durability, it is preferable to compound an antioxidant. The compounding amount is preferably 2 parts by weight or less, and particularly preferably 1 part by weight or less, per 100 parts by weight of diene rubber. Specific antioxidants are not particularly limited as long as they are generally used as antioxidants in the field of adhesives, and an example is Irganox 1010 (trade name).

The adhesive rubber composition of the present invention has good tack, adhesion, and retention, and is also well-balanced among them. Specifically, the tack measured in accordance with JIS Z-0237 is preferably 7 ball No. or more, and more preferably 9 ball No. or more. The adhesion measured in accordance with JIS Z-0237 is preferably 10 N/25 mm or more, and more preferably 13 N/25 mm or more. Furthermore, the retention measured in accordance with JIS Z-0237 is preferably 150 minutes or more, and more preferably 200 minutes or more.

The method for producing the adhesive rubber composition of the present invention is not particularly limited as long as the adhesive rubber composition can be obtained. For example, the adhesive rubber composition can be produced by feeding each compounding component into a blade mixer equipped with a blade having a suitable shape for kneading, and then heating and kneading the components; or by continuously producing the composition using an extruder-type kneader equipped with a single or twin screw. The adhesive solution can also be produced by stirring and mixing each compounding component in the presence of a solvent such as toluene, and an adhesive emulsion can also be produced by stirring and mixing a hydrocarbon resin that has been emulsified in advance in the rubber latex.

The adhesive rubber composition of the present invention has an excellent balance of tack, adhesion, and holding power, and can be used as an excellent adhesive. It can be applied to desired substrates such as tapes, labels, and sheets using a coating machine to produce various adhesive tapes, adhesive labels, adhesive sheets, and other products.

The present invention makes it possible to provide an excellent adhesive with an excellent balance of tack, adhesion, and retention.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The analytical and test methods used in the examples and comparative examples are as follows.

The analytical method for C5-DCPD copolymer resin is shown below.

~Proton NMR (nuclear magnetic resonance spectrum) measurement~
The C5-DCPD copolymer resin was dissolved in chloroform-d (manufactured by Wako Pure Chemical Industries, Ltd.) and measured by a conventional NMR measurement method. The area ratio of the obtained spectrum was calculated based on the following calculation formula.
Double bond hydrogen area (%)=(double bond hydrogen peak area)/(total of all peak areas)×100
Olefinic double bond (area ratio)=(olefinic double bond hydrogen peak area)/(total of double bond hydrogen peak areas of olefinic and DCPD residues)×100
DCPD residue double bond (area ratio)=(DCPD double bond hydrogen peak area)/(total of olefinic and DCPD residue double bond hydrogen peak areas)×100
The peaks are as follows:
Double bond hydrogen peak: 4.4-6.3 ppm.
Olefinic double bond peak: 4.4-5.2 ppm.
DCPD residue double bond peak: 5.3-5.5 ppm.

～Number average molecular weight (Mn), weight average molecular weight (Mw) measurement～
Using polystyrene as a standard substance, measurements were performed by gel permeation chromatography in accordance with JIS K-0124 (2011).

~ Bromine number measurement ~
The measurement was performed according to a method in accordance with JIS K-2605 (1996).

～Softening point measurement～
The measurement was performed according to JIS K-2207 (1996) (ring and ball method).

～Hue measurement～
The measurement was performed in accordance with ASTM D-1544-63T as a 50% by weight solution in toluene.

The evaluation method and evaluation criteria for the adhesive properties of adhesive rubber compositions are shown below.

~Tuck~
In accordance with JIS Z-0237, a 10 cm long piece of steel balls was attached with the adhesive side facing up to a slope on a glass plate with an inclination angle of 30 degrees at 23°C, and 30 different sizes of steel balls, ranging from 3/32 inch to 1 inch in diameter, were rolled from a position 10 cm above the slope at an initial speed of 0, and the size of the largest ball that came to rest on the adhesive tape was displayed (unit: ball No. (= x 1/32 inch)).

～Adhesive power～
In accordance with JIS Z-0237, an adhesive tape measuring 25 mm wide and 100 mm long was attached to a stainless steel plate and peeled in a 180 degree direction at a speed of 300 mm/min at 23° C. to measure the peel strength (unit: N/25 mm).

～Holding power～
According to JIS Z-0237, an adhesive tape was applied to a cardboard box over an area of 25 mm x 25 mm, and a load of 1 kg was applied at 50°C to measure the time (unit: minutes) required for the adhesive tape to fall off the cardboard box.

Synthesis Example 1
A 2-liter glass autoclave was charged with a raw material oil consisting of 50% by weight of C5 fraction (containing 1.5% cyclopentadiene concentration) and 50% by weight of DCPD fraction obtained by cracking naphtha. The temperature was then adjusted to 40°C under a nitrogen atmosphere, and 1.4 parts by weight of boron trifluoride isobutanol complex was added as a Friedel-Crafts catalyst per 100 parts by weight of the raw material oil, followed by polymerization for 2 hours. The catalyst was then removed with an aqueous caustic soda solution, and the unreacted oil in the oil phase was distilled to obtain a C5-DCPD copolymer resin (referred to as resin A). The evaluation results are shown in Table 1.

Synthesis Examples 2 to 4 and 7
C5-DCPD copolymer resins (referred to as Resins B, C, D, and G) were obtained in the same manner as in Example 1, except that the weight ratios of the feedstock oil consisting of a C5 fraction (containing 1.5% cyclopentadiene) obtained by cracking naphtha and a DCPD fraction were as shown in Tables 1 and 2. The evaluation results are shown in Tables 1 and 2.

Synthesis Examples 5 to 6, Synthesis Example 8
A feed oil consisting of 55% by weight of a C5 fraction obtained by cracking naphtha and 45% by weight of a DCPD fraction was prepared as the feed oil, and C5-DCPD copolymer resins (referred to as Resins E, F and H) were obtained in the same manner as in Example 1, except that the cyclopentadiene concentration in the C5 fraction was as shown in Tables 1 and 2. The evaluation results are shown in Tables 1 and 2.

Example 1
100 parts by weight of natural rubber (RSS#3, Mooney viscosity ML ₁₊₄ 40) as a diene rubber was dissolved and mixed in toluene with 100 parts by weight of Resin A, 20 parts by weight of naphthenic process oil (product name: DIANA Process Oil NS-100, manufactured by Idemitsu Kosan Co., Ltd.), and 1 part by weight of an antioxidant (product name: Irganox 1010, manufactured by Ciba Specialty Chemicals Co., Ltd.), to obtain a tacky rubber composition solution having a non-volatile content of 23%.

The resulting adhesive rubber composition solution was applied to a 25 μm thick polyester film to a thickness of 35 μm, and the tack (initial adhesive strength), adhesive strength, and holding strength of the sheet were measured. The results are shown in Table 3.

The resulting adhesive rubber composition exhibited a well-balanced combination of tack, adhesion and retention.

Examples 2 to 12
Except for the formulation of the adhesive rubber composition as shown in Tables 3 and 4, adhesive rubber compositions were prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

The resulting adhesive composition exhibited a well-balanced combination of tack, adhesion and holding power.

Comparative Examples 1 to 5
Compositions were prepared and evaluated in the same manner as in Example 1, except that the composition formulation was as shown in Table 5. The results are shown in Table 5. In addition, in Comparative Example 3, a commercially available petroleum resin ((product name) T-REZ RA100, manufactured by ENEOS Corporation; Resin I) was used instead of Resin A.

The adhesive rubber composition of the present invention has an excellent balance of tack, adhesion, and retention, can be used as an adhesive, and is extremely useful industrially.

Claims (5)

An adhesive rubber composition comprising 70 to 130 parts by weight of a C5-dicyclopentadiene copolymer resin and 5 to 50 parts by weight of a process oil relative to 100 parts by weight of a diene rubber, wherein the diene rubber is natural rubber, the C5-dicyclopentadiene copolymer resin is a binary copolymer having a two-component constitutional unit of a C5 fraction, which is a thermal cracking fraction of petroleum, and dicyclopentadienes, and the dicyclopentadienes are either dicyclopentadiene alone or a dicyclopentadiene fraction containing methyldicyclopentadiene, dimethyldicyclopentadiene, cyclopentadiene, and methylcyclopentadiene , which are thermal cracking fractions of petroleum. The adhesive rubber composition according to claim 1, characterized in that the C5-dicyclopentadiene copolymer resin is a C5-dicyclopentadiene copolymer resin that satisfies all of the following characteristics (1) to (5):
(1) In the peak area measured by a proton nuclear magnetic resonance spectrometer, the double bond hydrogen area is 6 to 13%, and the olefinic double bond/dicyclopentadiene residue double bond (area ratio) is 30/70 to 75/25.
(2) The weight average molecular weight measured by gel permeation chromatography in accordance with JIS K-0124 (2011) using standard polystyrene as the standard substance is 1,200 to 2,500, and the weight average molecular weight/number average molecular weight is 1.5 to 2.5.
(3) The bromine number, measured in accordance with JIS K-2605 (1996), is 40 to 55 (g-Br ₂ /100 g).
(4) A softening point measured in accordance with JIS K-2207 (1996) (ring and ball method) of 80 to 125°C.
(5) A 50% by weight solution in toluene has a Gardner hue of 4 to 9 as measured in accordance with ASTM D-1544-63T. The adhesive rubber composition according to claim 1 or 2, characterized in that the C5-dicyclopentadiene copolymer resin is a polymerization catalyst type copolymer. An adhesive comprising the adhesive rubber composition according to any one of claims 1 to 3. The adhesive according to claim 4, which is a solution type further containing a solvent.