JPS60158282A - Heat-sensitive adhesive - Google Patents

Abstract

PURPOSE:To provide a heat-sensitive adhesive exhibiting excellent adhesion under mild bonding conditions, consisting of a modified ethylene/vinyl acetate/carbon monoxide copolymer modified by grafting an alpha,beta-ethylenically unsaturated carboxylic acid or anhydride onto said copolymer. CONSTITUTION:A heat-sensitive adhesive consists of a modified copolymer obtd. by grafting an alpha,beta-ethylenically unsaturated carboxylic acid or anhydride [e.g. (meth)acrylic acid or maleic anhydride] onto a copolymer composed of 40- 60wt% ethylene, 15-60wt% vinyl acetate and 3-30wt% CO. This adhesive can be applied to various substrates such as PE, PS and polyester films and sheets, aluminum foil, paper, wood, etc. under wide bonding conditions (temp., pressure, time, etc.) and under mild bonding conditions and can retain high-level adhesion over a long period of time irrespective of the type of the substrates.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heat-sensitive adhesives. More specifically, the present invention relates to a heat-sensitive adhesive made of a new material that exhibits excellent adhesive properties under mild bonding conditions.

Recently, synthetic resin bases such as polyethylene, polypropylene, gelystyrene, hard, semi-hard or soft polyvinyl chloride, ethylene-vinyl alcohol 424 combination, polyester, and polyamide are being used in the fields of automobiles, electrical parts, building materials, packaging materials, etc. A large amount of laminates are used, such as laminates of smooth substrates such as metal substrates such as wood, aluminum plates, and steel plates, or laminates of these smooth substrates and porous substrates such as paper, wood, and synthetic resin foam. has been done.

Among these laminates, heat-sensitive adhesives are still used to bond base materials that are relatively easy to adhere to, but flat? #When using polyolefin, soft yXIJm vinylated vinyl-vinyl alcohol copolymer, polyester, polyamide, etc. as a base material, there are not many heat-sensitive adhesives that exhibit sufficient adhesive strength for adhesion of these materials. Currently, it is unavoidable to surface-treat the base material and then use a solvent-based adhesive to adhere it.

In addition, improvements have been made to heat-sensitive adhesives themselves in areas other than adhesive properties, such as improving bonding conditions such as temperature, pressure, and time, in order to prevent deterioration of the base material and the generation of odors during bonding. He is praised for his gentle nature. Furthermore, from the viewpoint of application to various industrial fields, high levels of adhesiveness such as weight resistance and durability are required.

The heat-sensitive adhesives currently used industrially include α
There are polyolefins graft-modified with β-unsaturated carboxylic acids or their acid anhydrides, which are effectively used for various purposes, but are effective adhesives for soft polyvinyl chloride, polystyrene, polypropylene, etc. Yes, there is no sentence.

A method using ethylene-vinyl acetate-carbon oxide copolymer has also been proposed for bonding various types of polyvinyl chloride, including soft vinyl vinyl, to other substrates (1). 165,427), this adhesive also does not reach the adhesive strength level required for various uses.

As a result of various studies in search of a heat-sensitive adhesive that exhibits excellent adhesive properties under mild bonding conditions, the present inventors discovered that α,β-ethylenic properties of a new material, ethylene-vinyl acetate-e-carbon copolymer, It has been found that graft modified products of unsaturated carboxylic acids or their acid anhydrides are extremely effective. Therefore,
The present invention relates to a heat-sensitive adhesive comprising such a graft modified product.

The ethylene-vinyl acetate-carbon oxide copolymer used for graft modification has a weight of approximately 40% ethylene.
~80%, preferably about 60-70%, vinyl acetate about 15-60%, preferably about 20-30%, and carbon oxide about 3-30%, preferably about 5-15% %, and other comonomers may be copolymerized as necessary.

If the ethylene content is less than this, extrusion moldability during thermal bonding,
When used as a film-type adhesive, the extrusion moldability of the film is poor, and on the other hand, if the ethylene content is higher than this, the target adhesive strength level cannot be obtained. If the content of vinyl acetate and carbon monoxide is less than this, it will not be possible to obtain the level of adhesive strength required for self-adhesion, and if it is more than this, heat resistance will be deteriorated.

Examples of the α,β-unsaturated carboxylic acid or its acid anhydride to be graft copolymerized to the ethylene-vinyl acetate-carbon oxide copolymer include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, Examples include hymic acid, crotonic acid, α-chloroacrylic acid, maleic anhydride, itaconic anhydride, himic anhydride, etc.
Especially acrylic acid, methacrylic acid, maleic anhydride:
Ai is preferred.

Graft modification is carried out by adding ethylene-vinyl acetate to an α,β-unsaturated carboxylic acid or other acid anhydride in the presence of a radical generator such as an organic peroxide.
[This is carried out by reacting with a carbonaceous copolymer by a solution method, a melt method, etc.

The α,β-unsaturated luponic acid or its acid anhydride is graft copolymerized in such a proportion that it accounts for about 0.01 to 5% of the resulting graft modified product. If the amount of grafting is less than this, the desired adhesive strength cannot be obtained, whereas if it exceeds about 5%, the adhesive strength tends to increase and reaches saturation. is sufficient. Also, it has a melt flow rate of about 0.1 to 5009 ZlO min! Yes. If the melt flow rate is less than @1 crab, the fluidity will be low and it will not be suitable for contact with Ne at low temperature and low pressure.On the other hand, if it is more than this, the L cohesive force will decrease and the adhesive force will also decrease.

The obtained graft modified product can be used alone, and within the I, Z range that does not impair its adhesiveness or moldability (color synthetic resins, such as ethylene-vinyl acetate copolymer, ethylene-acrylic- It can be used by blending with copolymers, ethylene-methacrylic acid copolymers, ethylene-vinyl acetate-carbon oxide copolymers, ethylene-α-olefin copolymers, etc.

When blending an ethylene-vinyl acetate-a-carbon copolymer, a more highly graft-modified product is blended and the blend is adjusted to a graft amount of about 0.01 to 5 weight. be able to.

In addition to these, heat stabilizers, thickeners, lubricants, fillers, colorants, etc. may also be added as appropriate.

Examples of base materials to which the heat-sensitive adhesive of the present invention can be effectively applied include polyethylene, propylene, polystyrene, vinyl chloride resins, ethylene-vinyl alcohol copolymers, diesters, polyamides, and ethylene-vinyl alcohol copolymers.
Films, sheets, etc. of vinyl acetate copolymers, polyacrylic acid copolymers, ethylene-acrylic ester copolymers, ethylene-methacrylic acid ester copolymers, ethylene-methacrylic ester copolymers, ionomer resins, etc. molded products, aluminum foil, copper foil, steel plates, paper, wood, synthetic resin foams, nonwoven fabrics, etc.

The above-mentioned vinyl chloride resins include hard polyvinyl chloride, 7-talate esters, adipate esters, phosphate esters, polyesters, and soft or Semi-rigid polyvinyl chloride, ethylene-vinyl acetate copolymer or vinyl chloride graft copolymer to polyacrylic acid ester, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-acrylic/L -acid ester copolymers, vinyl chloride-methacrylic acid ester copolymers, etc. are used.

Application of the heat-sensitive adhesive to these substrates is carried out, for example, by the following method.

(1) Heat-fusion method A method in which a heat-sensitive adhesive film formed by an inflation method, a T-die method, etc. is sandwiched between base materials and then thermocompressed, or at least one of the base materials is coated with a coextrusion method or extrusion coating. (2) Sandwich lamination method A method of laminating the base materials through a molten layer of heat-sensitive adhesive using the T-Guy method (2) 8) Co-extrusion method When the base material can be extruded, the entire structure N, including the heat-sensitive adhesive, is adhesively laminated by extrusion molding (4) Hot-melt heat-sensitive adhesive is added as necessary. A hot melt adhesive formulation containing viscosity modifiers such as wax, adhesives, etc.
A method of applying heat-sensitive adhesives to a base material using a hot-melt gun, etc., and adhering them under pressure.The adhesive conditions for heat-sensitive adhesives include temperature, pressure, time, etc., but deformation of the base material or adhesive resin layer, From the viewpoints of prevention of deterioration and odor generation, formation of a uniform adhesive resin layer, productivity, etc., it is desired that sufficient adhesive strength be obtained under mild adhesive conditions. With conventionally used heat-sensitive adhesives, such as polyolefins graft-modified with α,β-ethylenically unsaturated carboxylic acids or their acid anhydrides, if these adhesive conditions are made mild, the adhesive strength will decrease. Although it can be seen quite a lot,
As shown in the following examples, the heat-sensitive adhesive according to the present invention exhibits almost no or only slight decrease in adhesive strength even under mild adhesive conditions.

Therefore, when the heat-sensitive adhesive according to the present invention is applied to various substrates, bonding conditions such as temperature, pressure, and time can be selected from a wide range. The effect is that a high level of adhesion can be maintained for a long period of time regardless of the condition.

Next, the present invention will be described in detail with reference to examples.

Example 1 Ethylene-vinyl acetate-carbon oxide copolymer (ethylene 62.5% z1 vinyl acetate 28.5% by weight, -carbon oxide 9.0% by weight; melt flow rate 35 by measuring method described below) 100 parts ( 1 part of maleic anhydride and 0.2 parts of an 80% mineral spirit solution of 1,1-bis(tert-butylperoxy)Schiff-tetrahexane were homogenized by tri-blending in advance. Add this to an extruder (screw diameter 30mm, L/D -32) for about 5K1.
The temperature at the middle part of the extruder was set at 200℃.
Graft modification was performed while maintaining the The obtained maleic anhydride graft modified product had a grafting rate (by titration method) of 0.3% by weight (maleic anhydride reaction rate of about 30%),
Mel) 7 a-rate (, TIS K-6760
(2190°C, 2160 g) had a value of about 30.

In order to examine the adhesion of this maleic anhydride graft modified product with various resins, press sheets with a thickness of 1 gm were prepared for each of the graft modified product and various resin base materials, and then these two press sheets were bonded together. Press fusion was performed. Press fusion is performed at a constant temperature of 200°C.
Preheat for 3 minutes - degas and pressurize for 3 minutes (9.8 MPa)
It was done in that order.

Further, similar press fusion was performed on the aluminum base material.

The interlayer adhesive strength of these 81 layers was measured as follows.

Width of test piece: 15++un Measuring device: Autograph P-100 manufactured by Shimadzu Corporation Measuring temperature: 23°C Measuring method: Peel a specified distance using a solvent, or use a predetermined length of release paper between the layers before heat fusing. 200 m.
The results obtained by measuring the adhesive force by T-peel pulling at an IJ1 tension rate of 7 minutes are shown in Table 1 below.

Example 2 100 parts of the ethylene-vinyl acetate-carbon oxide copolymer used in Example 1jlJ1, 2 parts of acrylic acid, and 0.1 part of tert-butyl peroctoate were triblended in advance and homogenized. The mixture was fed into the extruder No. 1 at a feed rate of about 6 Ky/hour, and the graft modification was carried out while maintaining the temperature at the middle part of the extruder at 170°C. The obtained acrylic acid graft modified product had a grafting rate of 0.4% (direct acrylic acid reaction rate of about 20%) and a melt flow rate of about 20.

The adhesion of this acrylic acid graft modified product to various substrates was measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Comparative Example 1 The adhesion of the ethylene-vinyl acetate-carbon oxide copolymer used in Example 1 to various substrates was measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Comparative Example 2 The adhesion of maleic anhydride graft-modified polyolefin (Mitsui Petrochemicals Atmer NK 050) to various resin substrates was measured in the same manner as in Example 1, and the results are shown in Table IK below.

However, the meanings of the symbols written together with the interlayer adhesive strength (V158 width) are as follows.

0: Resin cutting or destruction Table 1 Base material Key 1 '11M2, groaning, pressing.

Polyamide (copolymerized nylon) 1570"' 242
00420"'
XF) CA”1M4FR1Wah-*vyay, aps
25) 15""'Soft polyvinyl chloride (DOP 5
0 phr ) 7770° --0 Hard aluminum (thickness 30 μm) 1920s 1110s 180s
Example 3 The ethylene-vinyl acetate-carbon oxide copolymer maleic anhydride graft modified product of Example 1 was transferred to an extruder (screw diameter 20 m, II/D-20) at a rate of about 2.5 Kf/
By supplying at a supply rate of 11 mm and extruding it from a T-die attached to the tip, a 1-shaft fishing rod with a thickness of approximately 100 μm is produced.
A film of rn was molded.

This film was coated with a polyethylene (Mitsui Polychemical product Mirason M-16SP) sheet with a thickness of IIIm and a soft polyvinyl chloride (DOP 50 phr) sheet.
) The material was sandwiched between sheets, and press fusion was performed in the same manner as in Example 1. However, the fusion temperature is 130℃, 150℃
℃, 180℃ or 200℃.

Comparative Example 3 In Example 3, instead of the maleic anhydride graft modified film, a film of its unmodified copolymer was used.

The interlayer adhesive strength of the press-fused laminates obtained in Example 3 and Comparative Example 3 was measured, and the results are shown in Table 2 below. In addition, in all of the measurement samples, peeling was observed at the interface on the polyethylene sheet side.

Table 2 130℃ 7509A5 width 100 gA5 throat width 15
0 920 100 180 850 100 200 830 100 Example 4 In Example 3, the thickness of the molded film was 1
wm saponified ethylene-vinyl acetate copolymer sheet (Kuraray product "EVAL IF-]ri" sheet and ionomer resin (Tamabosu polychemical product Himilan H-165)
2) It was sandwiched between sheets and press fusion was performed at a fusion temperature of 200°C.

The press-fused laminate has an interlayer adhesion strength of 1150971
With a width of 58, peeling was observed in the measurement sample at the interface on the ionomer resin sheet side.

Comparative Example 4 In Example 4, instead of the maleic anhydride graft modified film, a film of its unmodified copolymer was used. The press-fused laminate has an interlayer adhesion strength of 530
At a width of 9/15 rm, peeling was observed in the measurement sample at the interface on the saponified ethylene-vinyl acetate copolymer sheet side.

Example 5 The film formed in Example 3 was coated with 30 μm thick aluminum foil and 200 μm thick soft polyvinyl chloride h (
DOP 50 phr) films and heat-sealed at a predetermined temperature under conditions of a pressure of 0.29 MPa and a time of 5 seconds using a double-sided heating type heat sealer with a sealing width of 15 m.

Interlayer adhesion was measured for the heat-sealed laminate;
The results are shown in Table 3 below. In addition, the measurement sample includes
Peeling was observed at the interface on the aluminum foil side.

Comparative Example 5 In Example 5, the same heat sealing was performed using an unmodified film of the maleic anhydride graft modified film instead of the maleic anhydride graft modified film. The interlayer adhesion of the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition, in the measurement sample, peeling was observed at the interface on the aluminum foil side.

Comparative Example 6 In Example 5, using the maleic anhydride graft modified polyolefin film used in Comparative Example 2,
A similar heat seal was performed. The interlayer adhesion of the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition, in the measurement sample, peeling was observed at the interface on the soft polyvinyl chloride film side.

Comparative Example 7 In Example 5, instead of the maleic anhydride graft modified film, a maleic anhydride graft modified product (grafting rate 0. 60 parts by weight of 6-layer lid%) and 60 parts by weight of ethylene-vinyl acetate copolymer (embossed polychemical product F<
A similar heat seal was performed using a film formed from a melt blend with 40 parts Flex 450). The interlayer adhesion for the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition, in the measurement sample, peeling was observed at the interface on the aluminum foil side.

Table 3 100℃ 160 gA5 fighting width 30 Ruri 5 ■ width 01
15 ■ Width 60 45 ■ Width 130 160 40 0
110 150 190 110 0 140 180 330 150 0 160 200 460 180 6 200 Example 6 In Example 5, the heat sealing temperature was kept constant at 180° C., and heat sealing was performed by varying the pressure and time. The interlayer adhesion for the heat-sealed laminates was measured and the results are shown in Table 4 below. In addition, in the measurement sample, peeling was observed at the interface on the aluminum foil side.

Table 4 Pressure (MPa) Time @) Interlayer adhesive strength (9ASm width)
0.15 2 230 #8 340 0.29 2 290 330 1/8 340 From the results of Examples 5 and 6 above, it was determined that the maleic anhydride graft modified product of ethylene-vinyl acetate-carbon oxide copolymer was used as an adhesive. It can be seen that when used, stable and good adhesive strength can be obtained even under mild adhesive conditions such as temperature, pressure, and time.

Example 7 The film of the maleic anhydride grafted modified ethylene-vinyl acetate-carbon oxide copolymer molded in mA' Example 3 was extruded at a T-die exit temperature of 188°C, and was rolled in a chill roll while in a molten state. soft polyvinyl chloride CDOP 50 from both sides as it is guided between the
phr) film and a foamed polyethylene sheet (Toshi Products Plit?i foaming ratio 20, thickness 3mm, surface untreated) were inserted, and the adhesive layer of the graft modified material was inserted.
The two base materials were crimped together and then wound up at a winding speed of about 5 m/min to perform sir-lamination.

Regarding this sandwich laminate, its interlayer adhesion strength,
That is, the interlayer adhesive strength between the adhesive layer and the soft polyvinyl chloride layer or the foamed polyethylene layer was measured, and the results are shown in Table 5 below.

In addition, if soft polyvinyl chloride layered with a liquid plasticizer is used as at least one of the base materials, the liquid plasticizer such as DOP contained therein will coat the surface of the soft polyvinyl chloride resin. A troublesome phenomenon is generally observed in which the initial adhesive strength decreases over time and at the interface with many adhesive resins, but when the pressure-sensitive adhesive of the present invention is used, the adhesive Even in a test of leaving the adhesive in an atmosphere at 50° C., which was a test to accelerate the decrease in strength over time, no decrease in the initial adhesive strength was observed even after approximately 3 months had elapsed.

Example 8 100 parts of ethylene-vinyl acetate-carbon oxide copolymer (66% by weight of ethylene, 24% by weight of vinyl acetate, 10% by weight of -carbon oxide; Melt 70-Re) 35), 0.5 parts of maleic anhydride part and 0.0 parts of tert-butyl peroctoate.
After pre-triblending 0.5 parts, this was fed to an extruder (screw diameter 30 cm, L/D-36) at a feed rate of about 5 parts, while maintaining the temperature at the middle part of the extruder at 170°C. , graft modification was performed. The obtained graft modified product had a graft ratio of 0.1 weight i1t% (maleic anhydride reaction rate of about 20%) and a melt flow rate of about 30.

Regarding this maleic anhydride graft modified product, Example 7
Film molding and sand lamination were carried out in the same manner as above. The interlayer adhesive strength of this sandwich laminate was measured, and the results are shown in Table 5 below.As can be seen from this, the adhesive strength decreases over time.
No defects were observed even after 3 months in an atmosphere of 50°C.

Comparative Example 8 In Example 7, film forming (T-die exit temperature 187° C.) and sand lamination were performed using the unmodified maleic anhydride graft modified product instead of the maleic anhydride graft modified product. The interlayer adhesive strength of this sandwich laminate was measured, and the results are shown in Table 5 below.

Comparative Example 9 In Example 8, film forming (T-die exit temperature 187° C.) and sand lamination were performed using the unmodified maleic anhydride graft modified product instead of the maleic anhydride graft modified product. The entire interlayer adhesion strength of this sandwich laminate was measured, and the results are shown in Table 5 below.

Table 5 Note: X to B = Partially peeled off, remaining part cut or destroyed the base material Comparative Example 10 In Example 7, in place of the maleic anhydride graft modified product of the ethylene-vinegar 9-vinyl-carbon oxide copolymer Using various synthetic resins, film molding and sand lamination were performed using T-die exit temperatures depending on the resins. The interlayer adhesive strength of these sandwich laminates was measured over time under a 501: atmosphere, and the results are shown in Table 6 below.

(Synthetic resins used) I: Ethylene-acetic vinyl copolymer (embossed polychemical product Evaflex 150) 1i2 Anhydrous maleic graft modified product of the above copolymer 1 (grafting rate 0.5Ui1%) ■: Maleic anhydride-styrene co-graft modified product to the above copolymer (maleic anhydride graph) ratio 0.5
Poor bL%, styrene grafting rate 15% by weight) ■: Maleic anhydride graft modified product (grafting rate 0.1% by weight) to crystalline ethylene-α-olefin copolymer (Tamashi Petrochemical Products 77-8) ) ■:: Plastic urethane (Japan Elastran product Elastran El 585 FNAT) ■: Bolière ± Lu? Lyester resin (Toyo Products product Hytrel n)
To 2551) ■: Bolyether polyester resin (Dupont product Dipax 5050) ■: Polyterbolyester alJη (Dupont product GuiPax 722) In these cases, not only is a bonding temperature of 20°C or higher required, but also However, since the interlayer adhesive strength deteriorates significantly over time between the softened polyvinyl chloride layer and the adhesive layer, it cannot be said that sufficient adhesive performance is stably obtained.

Representative Patent Attorney Yoshi 1) Toshio Procedural Amendment (1. July 30, 1980 Commissioner of the Japan Patent Office Gakudono Shiga 1 Display of Case) 1978 Patent Application No. 13015 2 Title of Invention Heat-sensitive adhesive 3 Relationship with the case of the person making the amendment Patent applicant name Mitsui Polychemical Co., Ltd. 4 Agent (105) Address 501 Ato Building, 1-2-7 Shiba Daimon, Minato-ku, Tokyo
"Or these copolymers and polyvinyl chloride (2°
) Correct "adhesion" on page 8, line 12 to "coextrusion".

(3) Correct "rm/min" on page 11, line 12 to "Irm+o/min".

(4) Insert "adhesive" before "resin" on page 11, number 12.

(5) Insert "J" after "copolymer" on page 14, line 3.

(6) Delete "many" in line 12 of page 20.

(7) Insert "to investigate" after "decrease" on page 20, line 15.

(8) On page 20, line 16, ``to'' is corrected to ``deno j.''

(9) rXJ in the Comparative Example 8 column of Table 5 on page 22 (2 locations)
is corrected to Ir x ” s Jl.

(10) On page 26, lines 3 and 4, ``Because it is significant,'' is corrected to ``It is extremely important, and because the adhesive strength of the foamed polyethylene layer/adhesive layer is small.''

Claims (1)

[Claims] 1. α of ethylene-vinyl acetate-carbon oxide co-hybrid,
Heat-sensitive adhesive consisting of β-ethylenically unsaturated carboxylic acid or its acid anhydride graft modified product 0 2, ethylene about 40-80Jnj 1%, vinyl acetate about 1
The heat-sensitive adhesive according to claim 1, comprising a graft modified copolymer having a composition of 5 to 60% by weight and about 3 to 30% by weight of carbon monoxide.