JPH0146548B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention has a layer of a novel pressure-sensitive adhesive when heated, which is made of an acrylic graft polymer mixed with a hot-melt resin. This invention relates to an adhesive tape for holding an array in series. Conventional technology Electronic components with lead wires are held in a sag-like arrangement by sandwiching the lead wires between adhesive tape and non-adhesive tape, and the electronic components are automatically supplied to the manufacturing process of circuit boards, etc. A system for automatically assembling electronic parts is known
Publication No. 12368). In other words, under the control of a computer, the terminal ends of the lead wires of the electronic components arranged in a sagging pattern are cut to unravel the connected state, and the unraveled electronic components are automatically incorporated into the manufacturing process one by one to form circuit boards, etc. It is known how to assemble. In this automatic assembly system, it is required that the electronic components be attached to the adhesive tape with high precision, evenly spaced, and parallel to each other. Conventionally, adhesive tapes used in the above-mentioned automatic assembly systems for electronic components are made of pressure-sensitive adhesives that have improved creep properties by adding a heat-melting resin to ordinary pressure-sensitive adhesives that are sticky at room temperature. It was known that the layer was provided on a support tape (Japanese Patent Publication No. 13040/1983). This is because it is difficult to keep electronic parts in place with adhesive tapes made only of ordinary pressure-sensitive adhesives that are sticky at room temperature due to the large creep property of the pressure-sensitive adhesive layer. This is aimed at overcoming the problem that the automatic installation system stops because the computer cannot control the electronic computer due to positional deviation of the link. Problems to be Solved by the Invention However, in the conventional adhesive tape described above, the pressure-sensitive adhesive layer is bonded by adding a heat-melting resin having a predetermined melting point to a common pressure-sensitive adhesive. The problem was that it was difficult to obtain products with satisfactory properties because they had to strike a balance between strength and heat resistance. In other words, if the composition has an activation temperature of 100°C or less, the creep property will not be satisfactorily improved, and problems such as misalignment of electronic components and stoppage of automatic assembly systems, similar to those of previous pressure-sensitive adhesives, will occur. If this point is improved to create a composition that exhibits satisfactory creep resistance, the temperature required for its activation will be 100°C.
℃, and therefore, due to heat shrinkage, etc., the supporting tape needs to have considerable heat resistance to realize continuous connection at regular intervals, or the molten state may exceed the necessary level even after it is attached to the lead wire. Following this, there are pot-life problems that require a cooling process to prevent electronic components from shifting, and furthermore, low-temperature embrittlement is significant, and electronic components can be damaged by small impact forces when stored at temperatures below 0°C. This results in problems such as not being able to peel off, misalignment, etc., and therefore not being able to be stored at low temperatures. Means for Solving the Problems The present inventors have overcome the above problems and have
We worked hard to develop an adhesive tape for connecting electronic components that can be activated at a relatively low temperature of ℃, does not require a special process for cooling after attaching lead wires, and can be stored at low temperatures. As a result of repeated research, it was discovered that the purpose could be achieved by using a special acrylic graft polymer having a polymer with a high glass transition point in the side chain as a base polymer, and the present invention was completed. That is, the present invention comprises 50 to 99 parts by weight of an acrylic ester having an alkyl group having 1 to 12 carbon atoms, 1 to 15 parts by weight of an unsaturated carboxylic acid, and 0 to 49 parts by weight of an ethylene group-containing copolymerizable monomer. 100 parts by weight of a graft polymer whose main chain is a room-temperature sticky copolymer made from a reaction product of a reaction product with a glass transition point of 70 to 150°C, and a side chain of a polymer with a glass transition point of 70 to 150°C, is heated to a temperature of 70 to 200°C. A support tape is provided with a layer of heat-sensitive adhesive containing 50 to 200 parts by weight of a meltable resin, and is used to hold electronic components connected in a sagging arrangement via lead wires. adhesive tape. The heat-sensitive adhesive used in the present invention is a mixture of an acrylic graft polymer and a heat-melting resin. This makes it possible to temporarily fix lead wires of electronic components at room temperature before heat bonding, and is activated in a short time by heat treatment at a relatively low temperature, exhibiting sufficient adhesive properties such as wettability, and solidifying. It is possible to obtain excellent adhesive strength and creep resistance. In the present invention, the acrylic graft polymer is a copolymer of an acrylic ester having an alkyl group having 1 to 12 carbon atoms and an unsaturated carboxylic acid, or a copolymer containing an ethylene group as a third component. The main chain is a room-temperature adhesive copolymer made of a copolymer containing a polyvalent monomer, and the glass transition point is 70.
The side chain is a polymer with a temperature of ~150°C. If the glass transition point of the polymer as a side chain component is less than 70°C, the heat resistance will not be sufficiently improved, and if it exceeds 150°C, adhesive properties such as wettability will deteriorate, which is undesirable. The graft polymer can be prepared by, for example, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, or the like. In the present invention, as a copolymer for preparing the graft polymer, acrylic acid ester 50
A reaction product of 99 parts by weight, 1 to 15 parts by weight of an unsaturated carboxylic acid, and 0 to 49 parts by weight of an ethylene group-containing copolymerizable monomer is used. If the amount of the acrylic acid ester used is less than 50 parts by weight, the resulting hot pressure-sensitive adhesive will not have satisfactory adhesive properties, and if the amount of the unsaturated carboxylic acid used is less than 1 part by weight, the resulting hot pressure-sensitive adhesive will not have satisfactory adhesive properties. The adhesive strength of the hot pressure sensitive adhesive used is poor, and if it exceeds 15 parts by weight, the adhesive property is poor. In addition, if the amount of the ethylene group-containing copolymerizable monomer, which is incorporated into the main chain as necessary to adjust the balance between adhesiveness and adhesive strength, exceeds 49 parts by weight, the resulting hot pressure-sensitive adhesive The adhesion of the product decreases. As the graft polymer, a reaction product of 100 parts by weight of the aforementioned copolymer and 3 to 30 parts by weight of a polymer having a predetermined glass transition point is preferably used. If the amount of the polymer used is less than 3 parts by weight, the resulting hot pressure-sensitive adhesive will not have sufficient heat resistance, and if it exceeds 30 parts by weight, the adhesive properties may decrease. The appropriate amount of the heat-melting resin in the hot pressure-sensitive adhesive of the present invention is 50 to 200 parts by weight per 100 parts by weight of the graft polymer. If the amount is less than 50 parts by weight, the resulting adhesive may take a long time to re-solidify from heating and melting, or its adhesive strength may become weak; if it exceeds 200 parts by weight, This is undesirable because the adhesive becomes brittle and has poor wettability to the adherend. In the present invention, a thermofusible resin having a melting point of 70 to 200°C is used. If the melting point is less than 70°C, the resulting adhesive will have poor adhesive strength after solidification, and if it exceeds 200°C, a large amount of heat will be required to activate the resulting adhesive, which is undesirable. The number of carbon atoms for preparing the above copolymer is 1.
Preferred examples of acrylic esters having ~12 alkyl groups include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, butyl methacrylate, and 2-ethylhexyl acrylate.
-Ethylhexyl, isooctyl methacrylate,
Examples include esters of acrylic acid or methacrylic acid such as isononyl methacrylate. Preferred examples of unsaturated carboxylic acids include α,β-unsaturated carboxylic acids represented by acrylic acid, methacrylic acid, itaconic acid, and the like. On the other hand, preferred examples of the ethylene group-containing copolymerizable monomer used as necessary include 2-
Acrylic acid or methacrylic acid esters having a hydroxyethyl group, 2-hydroxypropyl group, 2-methoxyethyl group, or glycidyl group, ethylenic double esters represented by vinyl acetate, vinyl propionate, acrylonitrile, styrene, vinyltoluene, etc. Examples include compounds that have one bond. On the other hand, preferred examples of polymers as side chain components in the graft polymer include those consisting of methyl methacrylate, styrene, vinyltoluene, acrylic acid, methacrylic acid, and the like. Examples of thermomeltable resins that can be preferably used include phenol resins, xylene resins, polyterpene resins, coumaron indene resins, epoxy resins, and rosin resins. The adhesive tape of the present invention is one in which a support tape is provided with a layer of the above-mentioned heat-sensitive adhesive. As the supporting tape, for example, a paper material such as crepe paper or kraft paper, a plastic film or sheet, cloth, metal foil, etc. are generally used. The appropriate layer thickness of the pressure-sensitive adhesive when heated is 30 to 200 μm. Note that none of the constituent components or constituent conditions are limited to those described above. Further, each of the constituent components may be used alone or in combination of two or more. The adhesive tape of the present invention can be applied, for example, as follows, although it is not limited thereto. In other words, the terminals of the lead wires of the electronic components are temporarily fixed to the heat-sensitive adhesive layer of the adhesive tape, and the individual electronic components are aligned and positioned at equal intervals so that they are arranged in a sagging pattern. After that, a self-supporting tape-like base material such as kraft paper or cardboard with a basis weight of 100 to 300 g/m ² is attached to the hot pressure-sensitive adhesive layer via lead wires, and the adhesive layer is heated for 40 minutes. This can be carried out by heat treatment at ~80°C for 0.1 to 1 second. In this way, individual electronic components suitable for an automatic assembly system for automatically supplying electronic components to the manufacturing process of circuit boards etc. are connected in a sagging arrangement using adhesive tape.
Moreover, a product that is firmly adhesively held can be obtained. Effects of the Invention According to the present invention, since a special heat-sensitive adhesive is used, it is possible to temporarily fix electronic components via lead wires at room temperature before heat bonding, and for a short time at a relatively low temperature. To provide an adhesive tape that can firmly connect and fix electronic components in a continuous manner by heat treatment, and has excellent creep resistance to maintain the continuous state of electronic components or hold electronic components in a fixed position. Can be done. Further, the adhesive tape of the present invention has advantages such as excellent brittleness resistance at low temperatures and the ability to store the formed electronic component assembly at low temperatures. Examples Reference Example 1 100 parts of styrene was added to 70 parts of styrene in ethyl acetate containing 2 parts (by weight, same hereinafter) of 4,4'-azobis-4-cyanovaleric acid as an initiator and 5 parts of iodoacetic acid as a chain transfer agent. The reaction was carried out at ℃ for 24 hours to obtain terminal carboxylated polystyrene (weight average molecular weight about 10,000) with a glass transition point (Tg) of 100℃. Next, 100 parts of the obtained terminally carboxylated polystyrene and 4 parts of glycidyl methacrylate were reacted in xylene in the presence of hydroquinone using tri-n-butylamine as a catalyst to obtain polystyryl methacrylate. Reference Example 2 80 parts of butyl acrylate, 16 parts of ethyl acrylate and 4 parts of methacrylic acid were mixed in ethyl acetate with 2,2'-
Using 0.1 part of azobisisobutyronitrile as an initiator, the reaction was carried out at 60°C for 7 hours, and the weight average molecular weight was approx.
A solution of 800,000 polymers was obtained. Example 1 70 parts of 2-ethylhexyl acrylate, 20 parts of vinyl acetate, 10 parts of acrylic acid, and 5 parts of the polystyryl methacrylate of Reference Example 1 were mixed with 2,2'- in acetone.
Add 100 parts of terpene-modified phenol resin per 100 parts of this polymer to a solution of graft polymer (A) with a weight average molecular weight of about 700,000, which was obtained by reacting at 55°C for 10 hours with 0.2 parts of azobisisobutyronitrile as an initiator. (melting point 100°C) and 0.5 part of polyisocyanate were added and mixed, and this was applied onto crepe paper with a basis weight of 80 g/m ² so that the thickness after drying was 40 μm.
The adhesive tape of the present invention was obtained by drying at 80° C. for 5 minutes. Example 2 0.5 parts of benzoyl peroxide per 100 parts of the polymer was added to the solution of Reference Example 2, and 20 parts of methyl methacrylate (Tg of homopolymer, 105°C) was added dropwise at 70°C over 3 hours. 2 hours, 75℃
per 100 parts of the graft polymer (B) with a weight average molecular weight of about 800,000 obtained by reacting with
120 parts of phenol-modified xylene resin (melting point 80°C)
and 1 part of polyisocyanate are added and mixed,
This was applied and treated in the same manner as in Example 1 to obtain an adhesive tape of the present invention. Comparative Example 1 The solution of Reference Example 2 was mixed with 120 parts of phenol-modified xylene resin (melting point 80°C) per 100 parts of its solid content.
An adhesive tape was obtained in the same manner as in Example 1, except that a portion of polyisocyanate was added and mixed, and this was used as an adhesive component. Comparative Example 2 An adhesive tape was obtained in accordance with Example 1, except that 1 part of polyisocyanate per 100 parts of the solid content was added to the solution of Reference Example 2 and mixed, and this was used as an adhesive component. Evaluation Test An electronic component having a lead wire with a diameter of 0.5 mm bent into a U shape was placed on the adhesive surface of the adhesive tape obtained in the Examples and Comparative Examples with an interval of 5 mm, and
Temporarily fasten the ends of the lead wires over a length of 15 mm under conditions of 20°C and 65% RH so that both ends of the lead wires are aligned in parallel, and then place the lead wires on the adhesive surface. Layer cardboard tapes (width 15 mm) with a basis weight of 220 g/ ^m2 and heat them at 80℃ for 20 minutes.
A test piece was prepared by heating and pressing under the conditions of Kg/cm ² ×0.3 seconds, and was subjected to the following test. Retention performance 50g at the bent part of the lead wire at a temperature of 60℃,
After applying a load of 100g or 200g and leaving it for 2 hours, the displacement distance was examined. The results are shown in Table 1.

[Table] Adhesive Performance The force required to pull out the lead wire (at a speed of 300 mm/min) was investigated at temperatures of 0°C, 20°C, or 40°C. The results are shown in Table 2.

[Table] From Tables 1 and 2, it can be seen that according to the adhesive tape of the present invention as an example, electronic components are unlikely to be misaligned even when a load is applied, and strong force can be applied to electronic components or their It can be seen that the lead wires are retained and that low temperature storage is possible.

Claims (1)

[Scope of Claims] 1. 50 to 99 parts by weight of an acrylic ester having an alkyl group having 1 to 12 carbon atoms, 1 to 15 parts by weight of an unsaturated carboxylic acid, and 0 to 49 parts by weight of an ethylene group-containing copolymerizable monomer The main chain is a room-temperature sticky copolymer consisting of a reaction product with parts by weight, and the glass transition point is 70~
Add 50 to 200 parts by weight of a thermofusible resin with a melting point of 70 to 200°C to 100 parts by weight of a graft polymer whose side chain is a 150°C polymer.
An adhesive tape for holding electronic components connected in a sag-like arrangement via lead wires, the support tape being provided with a layer of a heat-sensitive adhesive in a proportion by weight of the adhesive. 2. The adhesive tape according to claim 1, wherein the acrylic acid ester is an ester of acrylic acid or methacrylic acid, and the unsaturated carboxylic acid is an α,β-unsaturated carboxylic acid. 3. The adhesive tape according to claim 1, wherein the ethylene group-containing copolymerizable monomer has one ethylenic double bond. 4 Copolymer 100 whose graft polymer is adhesive at room temperature
2. The adhesive tape according to claim 1, which is a reaction product of 3 to 30 parts by weight of said glass transition point polymer. 5. The adhesive tape according to claim 1, wherein the heat-melting resin is a phenol resin, a xylene resin, a polyterpene resin, a coumaron indene resin, an epoxy resin, or/and a rosin resin.