JPH08245938A - Pressure-sensitive adhesive and surface-protecting material using the same - Google Patents

Abstract

PURPOSE: To provide a pressure-sensitive adhesive having good initial adhesivity and weather resistance and free from the increase in the adhesivity with time. CONSTITUTION: This pressure-sensitive adhesive comprises (A) a polymer having isobutylene units as a main component, and (B) at least one kind of polyolefin resin selected from polyethylene, polypropylene, an ethylene-α-olefin copolymer, and a propylene-α-olefin copolymer and/or (C) at least one of polystyrene elastomer selected from styrene-butadiene-styrene, styrene-isoprene-styrene, and styrene-ethylene-styrene block copolymers. A surface-protecting material has the layer of the pressure-sensitive adhesive on a substrate. The surface-protecting material has good adhesivity when adhered, is very little in the change of the adhesivity with time after adhered, and has sufficient weather resistance for practical uses.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is used for a surface protection sheet or tape (hereinafter referred to as a surface protection material) for coated plates, metal plates, resin plates, etc. The present invention relates to a pressure-sensitive adhesive having a very small change with time in adhesive strength after laminating and having practical weather resistance, and a surface protective material using the same.

[0002]

2. Description of the Related Art Conventionally, a rubber-based adhesive such as natural rubber or polyisobutylene has been used as an adhesive used for a surface protective material of a coated plate, a metal plate, a resin plate (hereinafter, also referred to as an adherend). in use.

[0003]

However, the above-mentioned rubber-based adhesive has the following problems. That is, although the rubber-based adhesive has a smaller increase in adhesive strength than the acrylic-based adhesive, it becomes firmly adhered to the adherend with the passage of time, making the peeling work extremely difficult.
In addition, natural rubber and butyl rubber adhesives are prone to deterioration in the short term due to sunlight, etc., and when the surface protective material is exposed outdoors during transportation or construction, adhesive residue easily forms on the adherend due to deterioration. Further, the rubber adhesive has a small initial adhesive force.

As a method for improving the above-mentioned increase in adhesive strength, it is known to add various kinds of surfactants to the adhesive. Since the surfactant exerts its effect when it is present at the interface with the adherend, it is effective when the adherend is a metal plate. However, when the adherend is a coated plate coated with a paint, the molecular weight of these surfactants is as small as several tens to several hundreds. To move into the paint on the adherend. As a result, since the surfactant does not exist at the interface with the adherend, there is a problem that the sustainability for suppressing the increase in the adhesive force is lost.

Further, when a surfactant is added to a rubber adhesive having a low polarity, there is a problem that the surface of the adherend is easily contaminated due to poor compatibility.

[0006] In order to improve the above-mentioned weather resistance, addition of various antiaging agents, ultraviolet absorbers and the like have been studied, but the weather resistance characteristics required for surface protective materials are still insufficient. .

Further, as an improvement of the above-mentioned initial adhesive strength, studies have been made to reduce the polymer molecular weight of the rubber-based adhesive, but since the cohesive strength decreases, the above-mentioned problems become very remarkable. There is a problem of becoming.

An object of the present invention is to provide a pressure-sensitive adhesive which has a good initial adhesiveness, has a very small change in adhesive strength over time, and is excellent in weather resistance. Further, another object of the present invention is to have good adhesiveness at the time of laminating, and further, the change with time of the adhesive force after laminating is very small,
And to provide a surface protective material having practical weather resistance.

[0009]

[Means and Actions for Solving the Problems]
This is achieved by the pressure-sensitive adhesive and surface protective material of the present invention shown below. That is, the pressure-sensitive adhesive of the present invention comprises (1) a polymer having (A) an isobutylene unit as a main component, and (B) polyethylene, polypropylene, ethylene-
At least one polyolefin resin selected from α-olefin copolymer and propylene-α-olefin copolymer and / or (C) styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer , A styrene-ethylene-butylene-styrene block copolymer, and a styrene-ethylene-propylene-styrene block copolymer, and at least one polystyrene elastomer. (2) In the pressure-sensitive adhesive of (1), the polyolefin resin as the component (B) and the polystyrene elastomer as the component (C) are both 1 × 10 at 60 ° C.
^{It has} a dynamic shear storage elastic modulus of ⁷ dyn / cm ² or more. (3) In the pressure-sensitive adhesive of the above (1), with respect to 100 parts by weight of a polymer having an isobutylene unit as a main component (A), a polyolefin-based resin as a component (B) and /
Alternatively, (C) the polystyrene-based elastomer of
It contains 50 parts by weight.

Further, the surface protective material of the present invention has (4) an adhesive layer comprising the pressure-sensitive adhesive described in any one of (1) to (3) above on a substrate.

The above-mentioned dynamic shear storage elastic modulus was measured by using a RDSII viscoelasticity spectrometer manufactured by Rheometrics Co., Ltd., and the sample was filled in a parallel disk and was set to 1 Hz in a mode of torsion of rotation. It is the value measured by

Examples of the component (A) polymer having an isobutylene unit as a main component used in the pressure-sensitive adhesive of the present invention include polyisobutylene, a random copolymer of isobutylene and normal butylene, a copolymerization of isobutylene and isoprene. Combined (regular butyl rubber, chlorinated butyl rubber,
Brominated butyl rubber, partially crosslinked butyl rubber, etc.), or vulcanized or modified products thereof (modified with functional groups such as hydroxyl group, carboxyl group, amino group, epoxy group)
And the like, and preferably polyisobutylene and a random copolymer of isobutylene and normal butylene. The polymer having an isobutylene unit as a main component has a weight average molecular weight of 200,000 to 700,000, preferably 3
A suitable range is 0,000 to 600,000, more preferably 350,000 to 500,000.

As the polymer having an isobutylene unit as a main component, a polymer having a low molecular weight, a polymer having a high molecular weight or a combination of both can be used, but a polymer having a high molecular weight, for example, a weight average molecular weight (Mw) is 80. If more than 10,000 is used, the weather resistance becomes particularly excellent, but the initial adhesive strength tends to be small.

Here, the "main component" means that the proportion of isobutylene units in the whole polymer is 50% by weight or more, and particularly preferably 80% by weight or more.

The above-mentioned polymer having an isobutylene unit as a main component has an appropriate viscoelasticity in the room temperature region and has almost no unsaturated double bond in the molecule, and therefore has a good initial value for a pressure-sensitive adhesive. Adhesiveness and weather resistance can be imparted.

In the present invention, as the polyolefin resin as the component (B), conventionally known ones such as polyethylene, polypropylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer and the like. Can be used as appropriate. Examples of the α-olefin in the ethylene-α-olefin copolymer include homopolymers and copolymers of propylene, butene-1, 4-methylpentene-1 and the like.

Examples of the polystyrene elastomer of the component (C) include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer. Polymer (SEBS),
Styrene-ethylene-propylene-styrene block copolymer (SEPS) and the like can be mentioned, and conventionally known ones can be appropriately used.

Both the polyolefin resin as the component (B) and the polystyrene elastomer as the component (C) have a dynamic shear storage elastic modulus of 1 × 10 at 60 ° C.
It is preferably ⁷ dyn / cm ² or more. When the dynamic shear storage elastic modulus at 60 ° C. is less than 1 × 10 ⁷ dyn / cm ² , sufficient cohesive force of the adhesive cannot be obtained, and adhesive residue tends to remain and peeling work tends to be difficult. .

Further, in the adhesive, the blending ratio of the polyolefin resin as the component (B) and / or the polystyrene elastomer as the component (C) to the polymer having the isobutylene unit as the main component (A) is The component (A) 1 is not particularly limited.
It is preferable to add 2 to 50 parts by weight of the component (B) and / or the component (C) to 00 parts by weight, and more preferably 5 to 30 parts by weight. If the addition amount of the component (B) and / or the component (C) is less than 2 parts by weight, the cohesive force of the adhesive cannot be sufficiently obtained, while if it exceeds 50 parts by weight, the cohesive force of the adhesive becomes high. If it is too much, the initial adhesiveness tends to deteriorate, and good laminating properties tend not to be obtained.

In the adhesive, the above (B)
When the component and the component (C) are used in combination, the mixing ratio of the component (B) and the component (C) is not particularly limited, and can be a desired ratio that is the above total amount.

For the adhesive, various materials such as commonly used antiaging agents and ultraviolet absorbers may be used within the range not deviating from the object of the present invention.

The pressure-sensitive adhesive of the present invention is, for example, a coated plate,
It is useful as a pressure-sensitive adhesive for surface protection materials such as metal plates and resin plates.

The surface protective material of the present invention is characterized by having an adhesive layer made of the above pressure-sensitive adhesive on a substrate. Examples of the substrate include those conventionally known as a substrate for the surface protective material, preferably a plastic film such as a polypropylene film, a polyethylene film or a polyolefin resin film or a polyvinyl chloride resin film obtained by blending them. The
A polyolefin resin film is preferable.

The above-mentioned substrate may be subjected to corona treatment, undercoating treatment, back surface treatment or the like, if necessary. Further, the base material, if necessary, a slip agent,
Antistatic agents, antioxidants, etc. can also be added.

In the surface protective material, the thickness of the substrate is usually 5 to 300 μm, preferably 10 to 100 μm, and the thickness of the adhesive layer is 1 to 200 μm, preferably 1 to 50 μm. Is.

The surface protective material of the present invention is produced by forming the above pressure-sensitive adhesive layer on a substrate. Examples of the method of forming the pressure-sensitive adhesive layer include a method of melt-extruding a pressure-sensitive adhesive and a base material (for example, a polyolefin resin) in two layers, a method of laminating the adhesive on a base material, and the like. can give. For the melt two-layer extrusion, for example, a T die molding method, an air cooling type inflation, or a water cooling type inflation is adopted. Also, in the method of laminating the adhesive,
For example, a calendar system is adopted.

Since this surface protective material is formed by forming the adhesive layer having excellent adhesive properties on the base material as described above, it exhibits good adhesiveness during lamination. Further, the change with time of the adhesive force after laminating is very small, and the peeling work becomes easy. Furthermore, it has practical weather resistance and is not easily deteriorated by sunlight or the like, and even if the surface protective material is exposed outdoors during transportation, construction, etc., deterioration of the adhesive is suppressed. However, adhesive residue is unlikely to occur when the surface protective material is peeled off, and soiling of the surface of the adherend is significantly suppressed.

[0028]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 4 and Comparative Examples 1 to 7 Melt flow rate (MFR) was used as the material for forming the base material.
2.0 g / 10 min polypropylene 80 parts by weight and MFR
A blend was prepared by mixing with 20 parts by weight of polyethylene at 5.0 g / 10 minutes. On the other hand, the ingredients having the composition shown in Table 1 were mixed with a Banbury mixer under heating at 180 ° C.
The mixture was kneaded for 0 minutes to prepare a pressure-sensitive adhesive composition. The blend for forming the base material and the pressure-sensitive adhesive composition were mixed with a T-die extrusion molding machine (40 mmφ) at a resin temperature of 2
Two-layer extrusion was performed at 30 ° C. to prepare a surface protective material having a pressure-sensitive adhesive layer having a thickness of 20 μm on a substrate layer having a thickness of 40 μm.

Test and Measurement Method Each surface protective material prepared in the above Examples and Comparative Examples was laminated on a melamine-based coated plate using a laminator at a laminating pressure of 70 N / cm and a laminating speed of 5 m / min. As a sample, the following adhesive strength and weather resistance tests were conducted. Table 1 shows the results.

(1) Adhesion test A surface protective material was applied to a melamine-based coated plate, and after 30 minutes, the adhesion was measured under conditions of a peeling angle of 180 ° and a pulling speed of 0.3 m / min. Is shown in Table 1. Furthermore, after conducting a 70 ° C. heating acceleration test for 3 days, the adhesive strength was measured in the same manner as above, and this value is shown in Table 1 as the adhesive strength with time. The conditions of the above-mentioned heating promotion test correspond to being left at room temperature for about 1 year when converted by the Arrhenius equation.

(2) Weather resistance test A sample was fixed outdoors and an outdoor exposure test was conducted. The surface protective material was peeled off from each sample 30 days and 90 days after the start of the exposure, and the presence or absence of adhesive residue / contamination on the samples at that time was examined. In addition, when no adhesive residue / contamination was observed on the surface of the surface protective material, the evaluation was evaluated as ○, and when adhesive residue / contamination was observed on the surface, it was evaluated as x.

Evaluation Criteria for Comprehensive Evaluation: When the results of both of the following adhesive strength and weather resistance were satisfied, the result was ◯, and in other cases, the result was x. Adhesive strength: The initial value of the adhesive strength and the value after aging are 1.5.
Within the range of ~ 3.0N / 20mm. Weather resistance: Adhesion remains on the pasting surface and no contamination is observed at all after 30 days and 90 days.

[0034]

[Table 1]

[0035]

[Table 2]

As is clear from the above table, Examples 1 to 4
Each of the surface protective materials obtained in 1. had a good initial value of the adhesive force, and the increase in the adhesive force with time was small. Moreover, it was also excellent in weather resistance. On the other hand, in Comparative Example 7, since the molecular weight of the component (A) was as large as 800,000, the initial value of the adhesive strength was small and the adhesive strength at the time of lamination was poor. In addition, Comparative Examples 1, 2 and 4
Component (A) has a small molecular weight, but component (B) or (C)
Since no components were contained, the initial value of the adhesive strength was good, but the increase in the adhesive strength over time was large, and the weather resistance was also poor.

[0037]

EFFECT OF THE INVENTION The pressure-sensitive adhesive of the present invention has good initial adhesiveness, excellent weather resistance, and little increase in adhesive strength after aging. Therefore, the pressure sensitive adhesive is
It is useful as a pressure sensitive adhesive for surface protection materials. Since the surface protective material of the present invention has the adhesive layer formed on the substrate by using the pressure-sensitive adhesive, it has good adhesiveness at the time of laminating, and the adhesive force after laminating is increased. Since the amount is small, adhesive residue hardly occurs at the time of peeling and has practical weather resistance.
This is suitable as a surface protective material to be attached to the surface of an adherend such as a metal polishing surface, a name plate, an aluminum sash, a coating plate, a decorative plate, etc., and this surface protective material should be attached to the surface of the adherend. This makes it possible to prevent the occurrence of scratches during the processing and transportation of the adherend.

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Claims (4)

[Claims] 1. At least one selected from (A) a polymer having an isobutylene unit as a main component and (B) polyethylene, polypropylene, an ethylene-α-olefin copolymer, or a propylene-α-olefin copolymer. Polyolefin resin and / or (C) styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene A pressure-sensitive adhesive containing at least one polystyrene elastomer selected from block copolymers. 2. The polyolefin resin as the component (B) and the polystyrene elastomer as the component (C) each have a dynamic shear storage elastic modulus of 1 × 10 ⁷ dyn / cm ² or more at 60 ° C. The pressure-sensitive adhesive described. 3. 2 to 50 parts by weight of a polyolefin resin as a component (B) and / or a polystyrene elastomer as a component (C) with respect to 100 parts by weight of a polymer having an isobutylene unit as a main component as the component (A). Claim 1 containing part
The pressure-sensitive adhesive described. 4. A surface protective material having an adhesive layer made of the pressure-sensitive adhesive according to claim 1 on a base material.