JPS60226578A - Hot-melt type adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition of excellent low-temperature tack, good in balance between retention and adhesive force, suitably applicable to corrugated boards, by incorporating tackifying resin and/or softening agent in a blend of two sorts of black copolymers each made up of conjugated diene block and aromatic vinyl block in specific proportions. CONSTITUTION:The objective composition can be obtained by incorporating 100pts.wt. of a blend made up of (A)50-95wt% of a block copolymer having a structure of formula (B-A)n-B (n is 2-10; B is conjugated diene block, A is aromatic vinyl block), containing 5-45wt% of aromatic vinyl compound, also with a weight ratio: (total amount of the B minus both terminal B)/(total amount of the B) of 0.4-0.98 and (B) 5-50wt% of a second copolymer having a structure of formula A-B (A is aromatic vinyl block; B is conjugated diene block), containing 5-45wt% of aromatic vinyl compound with (C) 20-200pts.wt. of a tackifying resin and (D) 0-200pts.wt. of a softening agent. USE:Various adhesive tapes, labels such as for use in frozen foods, cold districts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a hot-melt adhesive that uses a block copolymer consisting of a conjugated diene block and an aromatic vinyl block, and has excellent low-temperature tack and cardboard properties, as well as excellent retention and adhesion. This relates to hot melt adhesives with excellent force balance.

Compared to conventional solvent-based adhesives and emulsion-based adhesives, hot-melt adhesives have the characteristics of being non-polluting, resource-saving, and faster to manufacture. Attention has been paid.

The main material of the hot melt adhesive is the general formula (A-B
)nA, (A-B)n, (A-B)n+, X (where A is a vinyl aromatic compound polymer block, B is a conjugated diene polymer block, X is a residue of a coupling agent, and n is A block copolymer consisting of a vinyl aromatic compound and a conjugated diene, or a mixture thereof, which is a thermoplastic diastereomer represented by I'm getting tired.

However, when looking at the tack and holding power, which are important properties of adhesives, adhesives based on these block copolymers have excellent tack but have poor holding power; However, the tack was poor, and both the tack and the holding force were poor, and the balance between the tack and the holding force was not sufficiently satisfactory. Furthermore, it has poor adhesive performance at low temperatures, causing problems in packaging and labeling frozen foods, packaging in cold regions, etc.

As a result of intensive research to solve the above drawbacks, the present inventors found that
By mixing specific types of (B-A)n-B type and A-B type block copolymers in a specific ratio, it has excellent tack and low-temperature adhesive performance, and has the ability to combine these properties with adhesion and holding power. It was discovered that a well-balanced hot melt adhesive can be obtained, and the present invention was achieved.

The present invention has a structure represented by (4) the general formula (B-A-)HB (wherein, n is 2 to 10, and B is a conjugated diene block A is an aromatic vinyl block). and the aromatic vinyl compound content is 5 to 45% by weight, preferably 0.6%.
~0.98 block copolymer with 50-95% by weight)
A block copolymer having a structure represented by the general formula AB (where A is an aromatic vinyl block and B is a conjugated diene block) and has an aromatic vinyl compound content of 5 to 45% by weight. (C) 20 to 200 parts by weight of tackifying resin and (
6) A hot melt adhesive composition containing 0 to 200 parts by weight of a softener is provided. At this point, the tack and low-temperature adhesiveness decrease, and if it still exceeds 0.98, the low-temperature adhesiveness decreases, which is not preferable.

n is 2-10, preferably 2-5. If n is less than 2, the low-temperature adhesion and tack will be poor, and if it exceeds 10, the tack at low temperature will be undesirable.

The block copolymer (4) used in the present invention has an aromatic vinyl compound content of 5 to 45% by weight, preferably 10% by weight.
~30% by weight. If the amount of the aromatic vinyl compound is less than 5 weight percent, the holding power will decrease, and if it exceeds 45 weight percent, the tack will decrease. The weight average molecular weight of block copolymer 1'A) is preferably 10,000 to 400,000, more preferably 50,000 to 250,000. 1
If it is less than 0,000, the holding power will decrease, and if it exceeds 400,000, the melt viscosity will increase, making it impractical. Block copolymer used in the present invention can be produced by the following method. . That is, ether or tertiary amine is added and polymerized in a hydrocarbon solvent, and after the polymerization reaction is substantially completed, a conjugated diene compound is polymerized, then an aromatic vinyl compound is polymerized, and finally the conjugated diene compound is polymerized. Polymerize.

The aromatic vinyl compounds used in the block copolymer used in the present invention include styrene, α-methylstyrene, p-
Methylstyrene, m-methylstyrene, 0-methylstyrene-1) tert-butylstyrene, dimethylstyrene, vinylnaphthalene, etc. can be used, and among these, styrene is preferred. Butadiene, isoprene, piperylene, etc. can still be used as conjugated diene compounds, but
Among these, butadiene and isopre are preferred. Further, a small amount of other monomers such as an aromatic vinyl compound may be present in the conjugated diene compound.

In particular, B other than both terminals is a block mainly composed of a conjugated diene compound, and may be a conjugated diene polymer block,
It may be a conjugated diene copolymer block in which a small amount of an aromatic vinyl compound is copolymerized, or a conjugated diene-aromatic vinyl taper block in which the aromatic vinyl compound content gradually increases.
It may be a conjugated diene block containing up to 10 pieces.

Hydrocarbon solvents used in the production of the block copolymer particles used in the present invention include cyclopentadiene, cyclohexane, benzene, xylene, and mixtures thereof with pentane, hexane, heptane, butane, and the like. Further, as the organic lithium compound, n-butyllithium, 5ec-butyllithium, tert-butyllithium, n-hexyllithium, 1so-hexyllithium, phenyllithium, naphthyllithium, etc. are used.

Further, the block copolymer ω) used in the present invention has an aromatic compound content of 5 to 45% by weight, preferably 10% by weight.
~30% by weight.

As A of the block copolymer (B), an aromatic vinyl compound of the block copolymer can be used, and as B, a conjugated diene compound of the block copolymer (I) can be used. Part B of the block copolymer (B) is a block mainly composed of a conjugated diene compound, and may be a conjugated diene polymer block or a conjugated diene copolymer block copolymerized with a small amount of an aromatic vinyl compound. , it may be a conjugated diene block containing 1 to 10 conjugated diene-aromatic vinyl taper blocks in which the aromatic vinyl compound content gradually increases.

If the aromatic vinyl compound content is less than 5% by weight, the adhesion retention will decrease, and if it exceeds 45% by weight, the tack will decrease. The total weight average molecular weight of the block copolymer is preferably 1,00
0 to 300,000, more preferably 5,000 to 200
,000. If it is less than 1,000, the holding power decreases,
If it exceeds 300,000, the melt viscosity becomes high and it is impractical.

The usage ratio of block copolymer (4) and block copolymer 03) used in the present invention is (A)/(B) -50 to 9
5150~5% by weight, preferably Fi70~90/30~
It is 10% by weight.

The tackifying resin (C) blended into the block copolymer (4) + (B) used in the present invention includes rosin resin, polyterpene resin, synthetic polyterpene resin, and alicyclic hydrocarbon. Resins, coumaron-based resins, phenolic resins, terpene-phenolic resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, etc. can be used. Among these, rosin resins, polyterpene resins, and alicyclic hydrocarbon resins are particularly preferred. These tackifying resins may be used alone or in combination of two or more. The blending amount of the tackifying resin is 20 to 200 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of the thermoplastic nidistomer.

If the blending amount of the tackifying resin is outside the above range, the adhesive will not have sufficient tack, adhesive strength and holding power suitable for the pressure-sensitive adhesive, and the object of the present invention will not be achieved.

Furthermore, as softeners (D), in addition to naphthenic, paraffinic, and aromatic process oils, liquid rubbers such as liquid polyisoprene rubber, liquid polyacrylate, liquid polybutene, liquid polyisoprene isobutylene rubber, liquid acrylic rubber, liquid polyester rubber, etc. Butadiene rubber and the like are used alone or in combination of two or more kinds. The amount of the softener used is 200 parts by weight or less, preferably 100 parts by weight or less, and more preferably 80 parts by weight or less, based on 100 parts by weight of the thermoplastic nidistomer.

In addition to the above, the adhesive composition of the present invention may optionally contain stabilizers such as antioxidants and ultraviolet absorbers, and inorganic photoreceptors such as calcium carbonate, Merck, clay, titanium oxide, silica, magnesium carbonate, and carbon black. Agents, coloring agents, etc. may be added.

The adhesive composition of the present invention may also contain other nidistomers, such as natural rubber, polyimprene rubber, polybutadiene rubber, styrene-butadiene rubber, and high styrene rubber, as long as the properties as a hot-melt adhesive are not lost. rubber, chloroprene rubber, EPT.

EPR, acrylic rubber, polyisoprene isobutylene rubber, etc., thermoplastics such as 1.2 polybutadiene, polybutene 1, polyethylene, ethylene vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, attack polypropylene, ionomer,
One type or two or more types of styrene resins may be mixed.

These components are mixed under heating in a general tank mixer, closed kneader, etc., in a nitrogen gas atmosphere if necessary.

The pressure-sensitive adhesive composition of the present invention exhibits the greatest economic effect when mixed and coated by the above-mentioned hot-melt method. However, it is also possible to apply the mixture using a conventional solvent-based or emulsion method. It is effective as glue, backing glue for fixing carpets, etc., and is also effective for frozen foods, adhesive tapes used in cold regions, and labels.

The present invention will be specifically explained below with reference to Examples, but the scope of the present invention is not limited by the Examples.

The block copolymers used in the following examples were produced by the following method.

(Production method of S-I single block copolymer) After charging 1600 gr of a 9/1 mixed solution of cyclohexane/n-pentane and 0.12 gr of tetrahydrofuran into a washed and dried stirrer and jacketed autoclave under a nitrogen atmosphere. , the internal temperature was set to 60°C.

Next, a hexane solution containing 0.57 g of n-butyllithium was added, and then 60 gr of styrene was added and polymerized for 60 minutes. The polymerization conversion rate of styrene was 100%.

Then, 340 gr of isoprene was added and polymerized for 60 minutes. The polymerization conversion rate of isoprene was 100%. During the polymerization, the temperature was adjusted to 60 to 70°C. After the polymerization was completed, 2.6-tert-butyl-p-cresol was added to the polymer solution, and then cyclohexane/n
- Pentane was removed by heating to obtain a block copolymer.

(Method for producing I-8-I-8-I linear block copolymer) After charging 1600 gr of cyclohexane/n-pentane-9/1 mixed solution and 0.12 gr of tetrahydrofuran into the same autoclave as above, the internal temperature was adjusted to 60°C. After adding a hexane solution containing 0.5 f of n-butyllithium, 8 gr of isoprene and 30 gr of styrene were added and polymerized for 20 minutes.

The polymerization conversion rate of isoprene and styrene was 100%. Next, 24gr of isoprene was added and polymerized for 20 minutes. The polymerization conversion rate of isoprene was 100%. Furthermore, 30 gr of styrene was added and polymerized for 15 minutes. The polymerization conversion rate of styrene was 100 Bi. Finally, 8 gr of isoprene was added and polymerized for 10 minutes. The polymerization conversion rate of isoprene was 100%.

Note that during the polymerization, the temperature was adjusted to 60 to 70°C. After the completion of polymerization, 2,6-tertbutyl-p-cresol was added to the polymer solution, and then cyclohexane/n
- Pentane was removed by heating to obtain a block copolymer.

(Production method of S-I-8 linear block copolymer) In the same autoclave as above, cyclohexane 7/n-pentane-
9/1 mixture 1600gr, tetrahydrofuran 0.1
After charging 2 gr, the internal temperature was brought to 60°C.

Next, a hexane solution containing 0.5 gr of n-butyllithium was added, and then 30 gr of styrene was added and polymerized for 20 minutes. The polymerization conversion rate of styrene was 100%. Then, 340 gr of isoprene was added and polymerized for 20 minutes.

The polymerization conversion rate of isoprene was 100%. Finally, 30 gr of styrene was added and polymerized for 20 minutes. The polymerization conversion rate of styrene was 100%.

Note that during the polymerization, the temperature was adjusted to 60 to 70°C. After the polymerization was completed, 2,6-di-tert-butyl-p-cresol was added to the polymer solution, and then cyclohexane/n-
Pentane was removed by heating to obtain a block copolymer.

(S-I-8-I Manufacturing method of linear block copolymer) After charging 1600 gr of cyclohexane 7'n-pentane-9/1 mixed solution and 0.12 gr of tetrahydrofuran into the same autoclave as described above, the internal temperature was lowered. The temperature was set to 60°C.

Next, a hexane solution containing 0.5 gr of n-butyllithium was added, and then 30 gr of styrene was added and polymerized for 20 minutes. The polymerization conversion rate of styrene was 100%. Next, isoprene 17'Ogr was added and polymerized for 20 minutes.

The polymerization conversion rate of isoprene was 100%.

This operation was further repeated once. Note that during the polymerization, the temperature was adjusted to 60 to 70°C. After the polymerization was completed, 2,6-di-tert-butyl-p-cresol was added to the polymer solution, and then cyclohexane/n-pentane was removed by heating to obtain a block copolymer.

Examples 1 and 2 Each of the formulations having the compositions shown in the table was placed in a mixing tank heated to 160°C and mixed with stirring for 60 minutes to obtain a uniform and smoothly flowing adhesive composition.

This adhesive composition was taken out in a molten state and coated onto a polyester film to a thickness of 30 microns using an applicator to prepare an adhesive tape sample.

About the adhesive tape sample with 23℃ and 0℃ tack,
Adhesive strength, retention strength, and 0°C cardboard retention strength were measured and shown in the table. The measurement method is shown in the table footnotes.

Comparative Example I An adhesive tape sample was prepared in the same manner as in Example except that only the linear block copolymer I-8-I-8-I was used.

This product has sufficient adhesion and holding power, but tack (
(23℃, 0℃) and 900 cardboard holding strength (0℃).

Comparative Example 2 An adhesive tape sample was prepared in the same manner as in Example except that S-I-8 linear block copolymer was used.

This product has sufficient holding power, but tack (23℃, o
℃) and 90 It is inferior to the cardboard holding power (0℃).

Comparative Example 3 Except for using S-I-8-I linear block copolymer,
Adhesive tape samples were prepared in the same manner as in the examples.

This thing is inferior to all qualities.

Comparative Example 4 An adhesive tape sample was prepared in the same manner as in Example, except that the 15-I single block copolymer and the 5-I-8,99 block copolymer were mixed in the proportions shown in the table.

Although this product has sufficient holding power, it is inferior in tack (0°C), adhesive strength, and 90 cardboard holding power (0°C).

Comparative Example 5 An adhesive tape sample was prepared in the same manner as in the example except that the S-I single block copolymer and the l-8-I-8-I linear block copolymer were mixed at a blending ratio exceeding the range of the present invention. Created.

This item has tack (0℃) and 90 cardboard holding power (
O tack with excellent adhesion and holding power (0°C); PSTC#60-Ring ball tack method angle 2
A steel ball with a diameter of 7716// is rolled on an inclined plate of 1.5 mm, and the distance at which it stops above the tape sample pasted on a horizontal plate is determined.

However, when measuring at an environmental temperature of 0℃, the run-up distance is 10
Crn.

Adhesive strength: JIS-Z-1522180 peel test adhesive tape sample was cut into 101III+I width and 5US
Glued to 304 plate, tensile speed 300/min.

Peel it off.

Holding power: JIS-Z-1524 Cut an adhesive tape sample into 15 mm width, adhere it to a 5US304 board with a constant area of 15 mm x 25 mm, suspend a load of 1 kg from one end of the tape, and measure the time until the adhesive surface peels off and falls. Find one.

However, the environmental temperature was 40°C.

90 Cardboard holding power: PSTC #14 adhesive tape sample was cut into 10+mm width, adhered to a cardboard board with a fixed area of 10 x 20 mm, and a load of 200 gr was suspended from one end of the tape at an angle of 90, and the adhesive surface was peeled off. Allow time for it to fall.

However, the environmental temperature was 0° C. when adhering the adhesive tape to the cardboard and when suspending the load.

Patent applicant: Japan Synthetic Rubber Co., Ltd. Agent: Patent attorney Akira Ito

Claims (1)

[Claims] (5), general formula (B-A)-B, (wherein n is 2 to 10, B is a conjugated diene block,
A is an aromatic vinyl block) with a weight ratio of 0
．． A block copolymer of 4 to 098 with a weight ratio of 50 to 95 and (B) has a structure represented by the general formula A-B (wherein A is an aromatic vinyl block and B is a conjugated diene block). C), 20 to 200 parts by weight of a tackifier resin, and 0 parts by weight of a tackifying resin, based on 100 parts by weight of a mixture consisting of 5 to 50 parts by weight of a copolymer having an aromatic vinyl compound content of 5 to 45 parts by weight.
A hot melt adhesive composition containing ~200 parts by weight.