JPS5859272A - Pressure-sensitive adhesive tape and production thereof - Google Patents

Abstract

PURPOSE:To produce a pressure-sensitive adhesive tape having excellent write ability and duplicating performance and good dullness, by forming a pressure- sensitive adhesive layer on one side of a PP resin substrate and a specified rough surface layer on the other side thereof. CONSTITUTION:A pressure-sensitive adhesive layer is formed on one side of a PP resin substrate composed of 95-50wt% PP and 5-50wt% methylpentene polymer. On the other side thereof is formed a rough surface layer having no void and no crack and composed of 25-85wt% PP resin (A) having a melting point lower than that of PP in the substrate, 10-50wt% fine inorg. particles (B) having the max. particle size of about 10mu and a particle size distribution such that the max. coarseness is 10mu or below and 10-point mean coarseness is 2.0-6.0mu, and 5-45wt% at least one resin (C) selected from methylpentene polymer, PS, a polyalkyl methacrylate and a polyestes with the proviso that the amount of component C is not more than that of component A. The resulting tape is stretched at a temp. not lower than the m.p. of component A to obtain a pressure-sensitive adhesive tape in which total light transmittance is 90% or above, and the specular gloss degree of the rough surface layer is 30% or above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive tape that has excellent writing properties, copying performance, and matte properties, and a method for producing the same.

One of the application fields of adhesive tape is repair adhesive tape, which is typically used for drafting purposes.
There is a demand for excellent light transmittance (hereinafter referred to as "copyability") of the tape-attached portion required for diazotype copying (hereinafter referred to as "writing performance"). Furthermore, since the surface of the paper that is normally repaired is matte, it is required that the surface of the adhesive tape be as matte as possible (hereinafter referred to as "matte property"). Good matting properties mean low specular gloss, and because there are few specularly reflected rays at the adhesive tape attachment area, the presence of the adhesive tape is small, and for example, In order to improve the required characteristics of the above-mentioned adhesive tape for repair as well as the matte property, the present invention adds a specific thermoplastic resin to the rough surface layer of the adhesive tape for repair, thereby creating an adhesive tape for repair with excellent properties. We have found that the following can be obtained, and the main points are as follows: (1) A layer of adhesive A is applied to the inner surface of the polypropylene resin base material, and the following (from Al, (B) and (C1 components) are applied to the tatami surface. The adhesive tape has a rough surface layer having no cracks, and the total light transmittance of the tape is above θ, and the specular gloss of the rough surface layer is 30 coefficients or less. An adhesive tape characterized by:

(A) Polypropylene resin 25~ and 5 weight factor CB
) Inorganic fine particles 10 - 5% to 7% by weight of a resin selected from 7 or more types selected from 10% to 5% by weight of a resin selected from (A) component amount and below, and A),
The total of components (B) and (C) is 700% by weight, and (2) 7 types of propylene copolymers with a lower melting point than pyrene, consisting of 95 to 50 weight parts of teripropyfluoride and 5 to 50 weight parts of methylpentene polymer. Alternatively, a layer containing particles is formed by mixing two or more resins (0) in the following component amounts to form a laminate, and the laminate is stretched at a temperature equal to or higher than the melting point of the propylene copolymer (A). Features: Adhesive tape manufacturing method.

(A)...2ri~? 5 Weight Section, (B)...
... IO-50% by weight (0) ... 4t% by weight and less than the amount of component (A) However, the total of components A), (B) and (C) is 100% by weight %It is in.

The resin used for the polypropylene resin base material in the present invention is preferably ordinary isotactic polypropylene, and may also be a copolymer of propylene and α-olefin. A mixture of these is preferred.

The mixed composition is preferably in the range of 9 to 50% by weight of polypropylene and 5 to 50% by weight of methylpentene polymer.

If the methylpentene polymer is outside the specified range, the guidance requirements will be lowered.In addition, as a methylpentene polymer, those with a Picat softening point (measured value according to JIS'-7206) lower than the melting point of polypropylene are recommended in terms of transparency of the base material. preferable.

A rough surface layer is formed on the spine of the base material, which is made of a polypropylene resin containing inorganic fine particles to provide excellent writing properties, and a specific thermoplastic resin to provide matte properties.

The polypropylene resin (A) used for this rough surface layer may be one having a lower melting point than the polypropylene used as the base material, such as propylene, ethylene,
Examples include copolymers with α-olefins.

The component (A) is contained in an amount of 25 to 100% by weight, where the sum of the components (A), (B), and (C) forming the rough surface layer is ioo% by weight. If it is less than 25% by weight, void cracks are likely to occur and copying properties are poor, and if it exceeds 5% by weight, writing properties are poor.

The inorganic fine particles (B) may be those commonly used as inorganic fillers for plastics such as calcium carbonate and clay, and in the final adhesive tape, JIS B
It is preferable that the particle size is such that the maximum roughness measured at −06θl is 70μ or less, the ten point average roughness is 2.0 to 6,θμ, and the maximum particle diameter is about 70μ.

Component (B) is contained in a range of 0 to 50% by weight.

If it is less than 70% by weight, the writability will be poor, and if it exceeds 50% by weight, the copyability will be poor.

One or more of these may be used. The methylpentene polymer may be the same resin as that used for the base material. Regarding polystyrene, so-called modified polystyrene in which a small amount of carboxylic anhydride or its derivative is added can also be used. The above-mentioned component (C) is contained in a range of about 1 to about 50%. If it is less than the evening weight, the matte properties will be poor, and if it exceeds the data weight, voids and cracks will easily occur and the copyability will be poor. 1. The amount of component (C) must be less than the amount of Al component, and if the amount of component (C) exceeds the amount of component (A), voids and cracks are likely to occur.

The relationship between the amount of each component in the rough surface layer and the amount of each component in the rough surface layer is illustrated in FIG. 1, and the effective range of the present invention is indicated by the shaded area. Further, it is important that this rough layer has no voids or cracks inside, and such a rough layer can be obtained by selecting the above-mentioned component ratio and employing the stretching conditions described below.

Next, a method for manufacturing the adhesive tape of the present invention will be explained.

A particle-containing layer consisting of a propylene copolymer (A) having a lower melting point than the polypropylene of the base material, inorganic fine particles CB), and a specific thermoplastic resin (C) is formed on the above-mentioned polypropylene resin base material by coextrusion method or the like. After lamination, an adhesive is applied to the other side of the base material.

As the adhesive, it is preferable to use an acrylic acid ester adhesive with good adhesive properties and apply it without a solvent. At that time, in order to firmly adhere the base material and the adhesive, it is preferable to laminate a carboxylic acid-modified polyolefin layer on the base material in advance. Advantageously, the carboxylic acid-modified polyolefin layer is coextruded with the substrate and the particle-containing layer. After applying the adhesive, the laminate is stretched, but the stretching is lower than the melting point of the polypropylene base material, and the propylene copolymer used for the particle-containing layer (
It is necessary to stretch at a temperature higher than the melting point of A).

By stretching under these conditions, the particle-containing layer is not substantially stretched or oriented because the fluidity of the propylene copolymer (A) increases during stretching, and the (A) component and (B) component due to stretching stress are ), the generation of voids and cracks at the interface with component (C) can be prevented. On the other hand, the base material is stretched and oriented to impart the required strength and tearability. Furthermore, it is necessary to determine the stretching ratio so as to make the thickness of the particle-containing layer after stretching as small as possible. This is because in order to provide good writability without impairing copyability (the Bl component must be supported flatly so that it is not buried inside).

The thickness of the particle-containing layer after stretching is preferably equal to or less than the maximum particle size of component (B) used.

By using such conditions of stretching temperature and magnification, it is possible to carry the component (B) in a flat manner on the surface of the final adhesive tape obtained. It has a white surface that makes it easy to read written characters and provides excellent copyability with a total light transmittance of 90% or more. Since fine surface irregularities are provided, light scattering on the surface is increased, and it becomes possible to obtain an adhesive tape with good matting properties and a specular gloss of 3θ coefficient or less.

The present invention will be explained in more detail with reference to Examples below.

〔Example〕

A composition prepared by mixing isotactic polypropylene with melt index da, θ, melting point / 67C and methylpentene polymer with Vicat softening point / O θC in a weight ratio of 7:, 2j was melt extruded to make an unstretched sheet, and the unstretched sheet was prepared by melt extrusion. One side of the sheet was coated with a propylene-ethylene copolymer of molten atr, sC as the component (A), calcium carbonate with an average particle size of 3μ and a maximum particle size/θμ as the component (B), and (0
j component and MP are methylpentene polymer (abbreviated as JM'4J), polystyrene modified with carboxylic anhydride ([modified PSJ
) and polymethyl methacrylate (abbreviated as "PMMAJ") and polymethyl methacrylate (abbreviated as "PMMAJ"
) mixed in the ratio shown in Table 7,
On the other side, modified polypropylene containing 3% by weight of itaconic acid was laminated by coextrusion lamination to form a three-layer unstretched laminated sheet. Next, apply an acrylic ester adhesive to the modified propylene layer side of the unstretched laminated sheet without using a solvent.
After coating to a thickness of μ, the film was stretched 6 times vertically at a stretching temperature of /6/C.
It was stretched at a width of 3.2 times. Thereafter, heat treatment was performed at /6% C for 5 seconds to obtain an adhesive tape with a particle-containing layer having a hard layer and a total thickness of 60 μm. Table 1 shows the writability, copyability, and matte properties of the obtained adhesive tape.

For writing, write on the tape surface using a pencil with a hardness of 6H.
Items that can be easily written are marked (◎), and items that are slightly difficult to write at the upper and lower limits of practical use are marked (○).

Copyability was measured by measuring the total light transmittance of one adhesive tape according to JIS K-67/f.

Matting property was determined by measuring the specular gloss of the adhesive tape at an incident angle of 6θ degrees in accordance with JIS Z-r7'l/.

From the table -/ *Propylene-ethylene copolymer table -/, it can be seen that the adhesive tapes of Samples/~7, which are within the scope of the present invention, are excellent in writability, copyability, and matte properties.

It can be seen that samples ♂ to /θ, which have a larger amount of component (C) than the polypropylene copolymer, tend to have voids and cracks in the rough surface layer and are inferior in copyability. In addition, it can be seen that the sample // to which no specific thermoplastic resin was added had poor matting properties.

As described above, the present invention provides an adhesive tape with excellent writability, copyability, and matte property, and a method for producing the same, and is particularly valuable when used as an adhesive tape for repairs.

[Brief explanation of the drawing]

The drawing is a composition diagram illustrating the effective composition range according to the present invention. .

Claims (2)

[Claims] (1) Adhesive in which an adhesive layer is formed on one side of a polypropylene resin base material, and a rough layer made from the following components (A), ■) and (0) and substantially free of voids or cracks is formed on the other side. The tape has a total light transmittance of 2θ%.
An adhesive tape having the above characteristics and having a specular gloss of the rough surface layer of 30% or less. (A) Polypropylene resin 2j-doj1% (
B) Inorganic fine particles /θ to jθ weight h% (C) Wat/glaze or 2 or more resins selected from methylpentene polymer, polystyrene, polyalkyl methacrylate, and polyester, and (A) component A)
, (B) and (0) components total 1oo-@child% (2) Polystyrene ~! ON-% and methylpentene polymer 6-jO weight 1%, an adhesive layer is formed on one side of the base material, and on the other side, a propylene copolymer having a lower melting point than the polypropylene (A), inorganic fine particles (B), and One or two types selected from methylpentene polymer, polystyrene, polyalkyl methacrylate, and polyester
Mix more than one type of resin (C) using the following ingredient lid. A method for producing an adhesive tape, which comprises forming a layer containing particles to form a laminate, and stretching the laminate at a temperature equal to or higher than the melting point of the propylene co-oil polymer (A). (A)...25~5% by weight, (B)...
・/θ~501t%(C')...j-g! Heavy lid%
(A) component i or less, provided that t-(A), (B) and (
C) The total amount of ingredients is 1 oz amount%