Adhesive masses based on block copolymers of structure P(A)-P(B)-P(A) and P(B)-P(A)-P(B)

• US 8,129,470 B2
• Filed: 03/04/2002
• Issued: 03/06/2012
• Est. Priority Date: 06/20/2001
• Status: Active Grant

• Current Assignee: Tesa SE (Maxingvest AG)
• Original Assignee: Tesa AG (Maxingvest AG)
• Inventors: Dollase, Thilo, Husemann, Marc, Luhmann, Bernd
• Primary Examiner(s): MULLIS, JEFFREY C
• Application Number:
  US10/529,845
• Publication Number:
  US 20060235150A1
• Time in Patent Office: 3,655 Days
• Field of Search: 525/89
• US Class Current: 525/89
• CPC Class Codes: C08F 293/005 using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 53/00 Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes
• CPC Class Codes: C09J 153/00 Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
• CPC Class Codes: C09J 153/02 Vinyl aromatic monomers and conjugated dienes
• CPC Class Codes: Y10T 428/14 Layer or component removable to expose adhesive
• CPC Class Codes: Y10T 428/1452 Polymer derived only from ethylenically unsaturated monomer
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/24959 of adhesive layers

Abstract

A pressure-sensitive adhesive comprising a blend of at least two components, one of which comprises a block copolymer having at least the unit P(A1)-P(B1)-P(A1) and the second of which comprises a block copolymer having at least the unit P(B2)-P(A2)-P(B2); the blend forming an at least two-phase system.

Claims

1. A blend of at least two components K1 and K2, each component being based on at least one block copolymer C1 or C2 respectively,

the at least one block copolymer C1 of component K1 consisting of one or more units of P(A1)-P(B1)-P(A1), where

P(A1) independently at each occurrence represents homopolymer or copolymer blocks of monomers A1, the polymer blocks P(A1) each having a softening temperature in the range from +20°

C. to +175°

C.,

P(B1) represents a homopolymer or copolymer block of monomers B1, the polymer block P(B1) having a softening temperature in the range from −

130°

C. to +10°

C.,

the polymer blocks P(A1) and P(B1) are not homogeneously miscible with one another,

the at least one block copolymer C2 of component K2 consisting of one or more units of P(B2)-P(A2)-P(B2), where P(A2) represents a homopolymer or copolymer block of monomers A2, the polymer block P(A2) having a softening temperature in the range from +20°

C. to +175°

C.,

P(B2) independently at each occurrence represents homopolymer or copolymer blocks of monomers B2, the polymer blocks P(B2) each having a softening temperature in the range from −

130°

C. to +10°

C.,

the polymer blocks P(A2) and P(B2) are not homogeneously miscible with one another,

wherein the polymer blocks P(A1) and the polymer blocks P(A2) possess an identical homopolymer and/or copolymer composition and the polymer blocks P(B1) and the polymer blocks P(B2) possess an identical homopolymer and/or copolymer composition

and the blend forming an at least two-phase system.

2. The blend of claim 1, wherein component K1 is present in an amount m_K1 and component K2 is present in an amount m_K2, and the amount m_K2 of component K2 used in the blend to the amount m_K1 of component K1 used in the blend is up to 250 parts by weight of K2 per 100 parts by weight of K1 to produce a ratio V=m_K2/m_K1≦

2.5.

3. The blend of claim 1, wherein the blocks P(A1) are compatible with the blocks P(A2) and/or their respective corresponding polymers P′

(A1) with P′

(A2) and/or the blocks P(B1) are compatible with the blocks P(B2) and/or their respective corresponding polymers P′

(B1) with P′

(B2).

4. The blend of claim 1, wherein the average chain length LB2 of the polymer blocks P(B2) of the block copolymer C2 does not exceed the average chain length LB1 of the polymer block P(B1) of the block copolymer C1.

5. The blend of claim 1, wherein, with the symbol i representing 1 or 2, the polymer blocks P(Ai) are present as a disperse phase in a continuous matrix of the polymer blocks P(Bi), optionally as spherical or distortedly spherical domains, this condition being obtained by adjustment of the ratio V_Li of the average chain lengths LAi of the polymer blocks P(Ai) to the average chain lengths LBi of the polymer blocks P(Bi).

6. The blend claim 1, wherein the block copolymer C1 has:

a number average molecular weight M_n of between 10,000 and 600,000 g/mol,

a polydispersity D=M_w/M_n of not more than 3,

a polymer block P(A1) fraction of between 5 and 49% by weight based on the composition-of the block copolymer C1.

7. The blend of claim 1, further comprising

at least one diblock copolymer C3 of the general formula P(A3)-P(B3),

wherein the polymer blocks P(A3) independently of one another represent homopolymer or copolymer blocks of the monomers A3, the polymer blocks P(A3) each having a softening temperature in the range from +20°

C. to +175°

C.,

and wherein the polymer blocks P(B3) independently of one another represent homopolymer or copolymer blocks of the monomers B3, the polymer blocks P(B3) each having a softening temperature in the range from −

130°

C. to +10°

C.,

and/or further comprising at least one polymer P′

(A4) and/or P′

(B4),

wherein the polymers P′

(A4) represent homopolymers and/or copolymers of the monomers A4, the polymers P′

(A4) each having a softening temperature in the range from +20°

C. to +175°

C.,

wherein the polymers P′

(B4) represent homopolymers and/or copolymers of the monomers B4, the polymers P′

(B4) each having a softening temperature in the range from −

130°

C. to +10°

C.,

and wherein optionally the polymers P(A4) are miscible with the polymer blocks P(A1), P(A2) and/or P(A3) and/or the polymers P′

(A4) are miscible with the polymer blocks P(B1), P(B2) and/or P(B3).

8. The blend of claim 7, wherein the diblock copolymer has:

a molar mass M_n of between 5000 and 600 000 g/mol,

a polydispersity D=M_W/M_n of not more than 3,

a polymer block P(A3) fraction of between 3 and 50% by weight, based on the diblock copolymer composition.

9. The blend of claim 1, wherein, with the symbol i representing 1 or 2, the polymer blocks P(Bi) are selected from the group consisting of group (1) acrylic and methacrylic acid derivatives of the structure (VI)

CH₂═

CH(R¹)(COOR²) 

 

(VI)

where R¹=H or CH₃ and R²=H or linear, branched or cyclic, saturated or unsaturated carbon chains having from 1 to 30 carbon atoms,

group (2) vinyl compounds which optionally contain functional groups.

10. The blend of claim 9, wherein the polymer blocks P(Bi) represent a copolymer of from 75 to 100% by weight of monomers from group (1) and up to 25% by weight of monomers from group (2), the weight fractions adding up to 100.

11. The blend of claim 1, further comprising

an admixture of tackifier resins, at a weight fraction of up to 40% by weight based on the weight of the blend without said resins,

and/or an admixture of plasticizers, fillers, nucleators, expandants, compounding agents and/or aging inhibitors.

12. The blend of claim 1, wherein said blend is processed further from the melt and is applied to a backing.

13. A pressure-sensitive adhesive tape having a pressure sensitive adhesive comprising the blend of claim 1, the pressure-sensitive adhesive being present as a single-sided or double-sided film on a backing.

14. The blend of claim 4, wherein LB2 is at least 10% smaller than LB1.

15. The blend of claim 14, wherein LB2 is at least 20% smaller than LB1.