Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1989-11-22
1992-03-03
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 98, 525271, 5253323, 5253331, 5253333, 525370, C08F29704, C08L 906
Patent
active
050934309
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a block copolymer composition which is suitable for adhesive compositions. The invention also relates to an adhesive composition containing said block copolymer composition. The invention further relates to a process for the preparation of said block copolymer composition.
Generally, adhesives are used for forming the adhesive layers of adhesive tape, such as graft tape, labels and adhesive sheets. Suitable such adhesives are those that are moderately flowable when subjected to hot melt and which consequently can be applied as such onto a substrate as an adhesive layer, without the need of an organic solvent.
Such hot melt adhesives are known, for instance from Japanese Patent Specifications 50-56426 and 54-33536, but these known adhesives do not quite possess the tack and at the same time the retention force that are required of the layer of an adhesive sheet.
Research into such problems has resulted in a hot melt adhesive with excellent properties, prepared by using a block copolymer with a special structure which is coupled with an at least bifunctional halogenated silicon compound and a halogenated tin compound. The present invention offers block copolymer compositions which are useful as hot melt adhesives whose tack, bonding strength, retention strength and blocking resistance when applied in adhesive tape are all excellent. Accordingly, the invention provides a block copolymer composition which comprises the following components: by the general formula I molecular weight in the range of from 10,000 to 30,000 and B.sub.1 a conjugated diene polymer block having a molecular weight in the range of from 25,000 to 100,000, 1.sub.1 is an integer in the range of from 1 to 3, m is an integer in the range of from 2 to 4 and Y.sub.1 represents a halogenated silicon compound residue; by the general formula II molecular weight in the range of from 10,000 to 30,000 and B.sub.2 a conjugated diene polymer block having a molecular weight that is at least 1.2 times as high as that of the conjugated diene polymer block B.sub.1 in the general formula I, 1.sub.2 is an integer in the range of from 1 to 6, n is an integer in the range of from 2 to 4 and Y.sub.2 represents a halogenated tin compound residue; and the general formula III molecular weight in the range of from 10,000 to 30,000 and B.sub.2 a conjugated diene polymer block having a molecular weight that is at least 1.2 times as high as that of the conjugated diene polymer block B.sub.1 in the general formula I, and 1.sub.3 is an integer in the range of from 1 to 6.
The invention further provides a process for the preparation of a block copolymer composition according to the present invention which process is characterized in that the process is carried out in the presence of a hydrocarbon solvent and using an organic lithium compound as polymerization initiator, and in that the preparation comprises the following consecutive steps: polymer block A as defined in the general formula I having a molecular weight in the range of from 10,000 to 30,000 is obtained, diene polymer block B.sub.1 as defined in the general formula I and having a molecular weight in the range of from 25,000 to 100,000 is obtained,
Adding a halogenated silicon compound and coupling in the range of from 10 to 60% of the total block copolymer formed in step 1 with formation of the residue Y.sub.1 in the general formula I;
Adding a conjugated diene compound again and polymerizing until the conjugated diene polymer block B.sub.2, as defined in the general formula II and having a molecular weight in the range of from 30,000 to 300,000 is obtained; and
After step 3 adding a halogenated tin compound and coupling the aromatic vinyl compound-conjugated diene block copolymer formed in the afore-mentioned steps with formation of the residue Y.sub.2 in the general formula II.
The components used to prepare the block copolymer compositions of the present invention are the following.
The aromatic vinyl compound used in the present invention may be, for example, styrene, .alpha.-met
REFERENCES:
patent: 4397994 (1983-08-01), Takeuchi
patent: 4845165 (1989-07-01), Halasa
Ito Hisaharu
Miyachi Takumi
Sakagami Toshinori
Toyama Yasuo
Jagannathan Vasu S.
Marquis Melvyn I.
Shell Internationale Research Maatschappij B.V.
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