DE2125913A1 - Synthetic writing paper and process for its manufacture - Google Patents

Description

¹¹ Synthetic writing paper and process for its manufacture "

Priority: May 26, 1970, Japan, No. U 521/70

The invention relates to a synthetic writing or copying paper, in particular such a paper with suitable opacity and a finely roughened surface, which is' suitable for writing on with ink and other writing materials and for drawing, copying, tracing, reproducing and printing purposes or for Production of further prints from such duplicated or printed sheets is suitable.

A wide variety of requirements are placed on writing machines. The papers should be easy to write on, for example with a pencil or 1 ton of ink, they should be easy to erase and dft -

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OWQlNAt INSPECTED

reufhiu to be writable again, no increase in tension on bending parts show, reproduce the typeface well, have sufficient physical strength, dimensionally stable and be moisture-resistant and durable. Ordinary tracing paper, for example, has poor physical properties Strength, dimensional stability and moisture resistance. Synthetic polymers have been used to overcome these disadvantages already considered to be effective and it has been suggested on several occasions that to produce a matt paper film on this basis, which has sufficient writability. There were various methods of matting the paper film developed, but encountered numerous problems. Sines of the most difficult of these problems is having a sufficiently thin film can hardly be produced and that the matting process is extremely expensive, which makes the economy of producing a matt film strong is affected.

The known methods for roughening the film surface in order to give it a sufficient writability bit will be used divided into sandblasting process and chemical treatment process. The disadvantages of sandblasting are that that they are very time consuming and that the grains of sand are the Penetrate thin foil, which makes sandblasting difficult. When using chemical treatment processes in which various alkalis and organic solvents are used a paper is obtained with only a superficial roughness, which is not resistant to any

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Possessing a writing instrument of high hardness. The paper also has poor dimensional stability because of residual chemical residues and is not very durable because it discolors. Another difficulty arises with chemical treatment processes then on when the thin film is easily soluble in the treatment agent concerned.

Another method is known, according to which a finely divided inorganic material, such as silicon dioxide, is added to a linear polyester resin as a further component and the film obtained therefrom is stretched. Although the film made by this method matted the required Has surface, it has two serious disadvantages. On the one hand there is a special treatment for uniform distribution a small amount of the fine inorganic particles (Grain size is equal to a few to several tens of microns) over the entire film surface required. On the other hand, although the polyester film is generally made by melt extrusion <.. rening of the material is carried out after its drying, at subsequent Manufacture of a transparent film using a different type of resin in the same extruder mixing of the remaining inorganic material with the resin because the inorganic added to the resin; fine particles mostly both in the drying chamber and; during melt extrusion in, for example, a hopper, cylinder, The extruder filter and sieve are left behind. the Quality of the film produced in the "next process step is naturally worsened by this. In the case of the aforementioned

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. Method goes by the change of the starting material, a considerable amount of material lost and the extrusion must prior to the subsequent process step with the other from gangsmaterialart be sufficiently cleaned to a Qualitätsverechlechterung of the final product is avoided. For this purpose, the extrusion device must be out of operation

.be set, which reduces their productivity.

The object of the invention was to provide a new synthetic writing paper with improved properties, especially better surface finish and opacity, the low. thickness has, is easily extrudable and stretchable by known methods and can easily be made non-transparent and an improved, highly productive and economical process to provide for the production of such writing paper. This object is achieved by the invention.

The invention thus relates to a synthetic writing paper, which is characterized by the fact that it is made of

a) a linear polyester and

b) a high polymer acrylic polymer, styrene polymer or polycarbonate with a higher glass transition temperature than that of component a) in a proportion of 7 to 35 percent by weight on the mixture of the polymer components,

consists.

The synthetic writing paper of the invention preferably contains as component a) polyethylene terephthalate, polyethylene isophthalate or an ethylene terephthalate / ethylene isophthalate

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Copolymer and, as component b), polymethyl methacrylate, an acrylonitrile / styrene copolymer, an acrylonitrile / butadiene / styrene copolymer, polystyrene or a polycarbonate derived from 4,4'-dihydroxydiphenyl-2,2-> propane.
The writing paper according to the invention is also suitable for the other purposes described above, for example for drawing, copying or printing.

The invention also relates to a method for producing the » the aforementioned synthetic writing paper, which is characterized in that the linear polyester component (a) using the above-mentioned mixing ratio homogeneously mixed with the high polymer component (b), the resulting Polymer masse processed into a film and the film formed at a temperature above. Freezing temperature of the linear polyester, but below its melting point, biaxial

stretched and optionallya the stretched film through a thermal treatment at a temperature above the stretching * - temperature of the linear polyester, but below the melting point 'High polymer and linear polyester, imparts high temperature resistance.

The film according to the invention is preferably stretched at temperatures of 85 to 95 ⁰ C. The stretching ratio is both. The length and width are preferably 2.5 to 3.5 times the original length or width.

The freezing temperature of amorphous polyethylene terephthalate is, for example, 69 to 7O ⁰ Cj crystalline polyethylene

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terephthalate has a * freezing temperature of 81 ⁰ C.

The amount in which it is mixed with the linear polyester (a) depends on the type of high polymer (b). Even if the admixed proportion of the high polymer is low, the stretched The film is semitransparent, although it cannot be written on in this way. If too high a proportion of the high polymer is used, the film obtained breaks easily when it is 'stretched', and it is difficult to ^ Reaching degree of stretching achieved. The breaking strength of the Film is also lowered if the stretching is at a temperature lower than the glass transition temperature linear polyester is made. When the film is at a higher temperature than the melting point of the linear polyester .stretched. becomes the molecular chain of the polyester

to ' '. .mobile, "which results in the slide not oriented and none. Stretching effect is achieved.

Any known method can be used to mix the aforesaid polymeric components (a) and (b). For example, the high polymer (b) present in granulate or powder form can be mixed with a Mix the granules of the linear polyester (a) and stir the mixture to achieve a homogeneous distribution. The processing the polymer mass into a film can be made according to the conventional method for processing linear polyesters be, for example .by melt extrusion meansB a T-nozzle or an annular nozzle. The film obtained

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is then either ^ in several stages or in one Level stretched. In general, a roll stretching machine is used for this purpose applied. The stretching temperature and the degree of stretching also depend on the high polymer, whichever is the linear Polyester is added. For stretching, the conditions can be used in which a film made of a linear polyester is stretched. The writability and opacity of what is to be produced Writing paper is determined, for example, by the type of High polymers, the proportion of this polymer used, the stretching temperature, the degree of stretching and the stretching process set. The writability and opacity of the inventive Writing paper can only be achieved by stretching for the following reasons.

The glass transition temperature of amorphous polyethylene terephthalate is, as mentioned, 69 to 70 ⁰ C, to the crystalline polyalkylene terephthalate 8l ° C. If a high polymer with a higher glass transition temperature than that of polyethylene terephthalate is mixed with this, the resulting mass is processed into a film, and this film is stretched at a temperature above the glass transition temperature of polyethylene terephthalate but below its melting point, the polyethylene terephthalate assumes a rubbery state while the added high polymer is in a glassy or rubbery state depending on its type. Since the glass transition temperature of polyethylene terephthalate is lower than that of the high polymer, the polyethylene terephthalate is used in the foregoing

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Trap to a greater extent than the high polymer and in the vicinity of the high polymer acting as a nucleus, which creates irregularities on the polien surface. If both polymeric components (a) and (b) are homogeneously dispersed, the surface irregularity decreases Foil has a very fine shape, which means that an excellent matt, easy-to-write surface, a uniform thickness of that applied to the paper surface Typeface ε and a satisfactory opacity can be achieved.

The high polymer (b) can be compatible with the linear polyester (a) or incompatible, provided that it is essentially during the processing of the polymer composition into a film can be homogeneously mixed or dispersed with the linear polyester, and that the film obtained, regardless of whether it is transparent or not, is given a uniformly matted surface on stretching. However, it is desirable that the High polymer (b) is well compatible with the linear polyester (a) and that the melting points of the two polymeric components ■ 'are as close as possible to each other, as this makes the film production is facilitated.

The films obtained according to the invention are heat-shrinkable and have excellent writability and have a satisfactory opacity. To further improve the dimensional stability of the film at high temperatures, the film can be above the ■ Stretching temperature of the linear polyester and below the melting point - thermally treat the point of both the high polymer and the linear polyester.

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I ₉ . 2125013

The writing paper according to the invention is not only suitable for writing and for copying purposes, but also, for example, as decorative paper, for metal-coated papers, labels or sticky notes and as envelope paper. It is particularly noteworthy that the paper according to the invention is excellently suited as drawing paper, since it has a hardened surface simply through the combination of the aforementioned two polymeric components without the use of any inorganic filler, ] which can be written on with a pencil of relatively high hardness and with writing ink, and since it has a satisfactory opacity and, as mentioned, good physical properties such as a satisfactory breaking strength. Since the starting material for the production of the writing paper according to the invention also consists of the aforementioned linear polyester (a) and the thermoplastic high polymer (b), it is melted homogeneously into a film during melt extrusion, which enables the film to be produced just as easily as in the case of producing a film made from a single polymeric material. In the manufacture of the film, there are no difficulties whatsoever which, in the case of the addition of fine inorganic substances, are caused by the occurrence of unmelted, non-flowable materials. There are also no problems whatsoever with regard to pretreatments, such as drying, to be carried out before the production of the film.

easy . _A ^;

According to the invention / foils of the most varied types can be manufactured using a single extrusion device without having to switch from one type of polymer to another

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Difficulties arise. The film thickness can also be adjusted as desired. There will be significant improvements achieves, such as an increase in productivity, a reduction in process costs and an even supply of the market with the finished product.

The examples illustrate the invention.

Example 1

'

J Different proportions of polymethyl methacrylate are mixed with polyethylene terephthalate, and the mass obtained is melt-extruded through a T-DUse, whereby films with a thickness of 1.50 μ and different compositions are obtained. These films are heated to 90 ° C. in a biaxial stretching machine and then stretched lengthways and widthways at the same time. The stretching ratio used is; two or three times the original dimensions.

The physical properties of the films are shown in Table I.

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j 1 Tabel r 3x3 I. 3x3 j 35
I. ι i
i
3x3 78.3 i
; 2 X 2
ί
1 23 j
10 25th 2x2 24 93.2 ■ Share of the poly
! methyl methacrylic
; lats in the
^; Polymermar.se,
'Weight percent I.
44 1200 2x2 1100 47 880 to the
s hardness
"3H" Degree of stretching,
I multiple of
■ length χ multif
ches of breadth 880 62 46 48 620 53] 21 ^! Thickness after
Stretching, λχ ; 116 84.6 860 8th 70.6 Breaking strength,
kg / cm ² I.
, 80.3 86.2 105 91.6 95.3 Elongation at break, $ 88.2 to
hardness
»Ι 2Η» ^ 78.6 c up to
hardness
"3H" r "b" Ts ~
to the
Hard <
"4H" Translucent
sigkeit s-paktor, to
hardness
"3H" 94.2 Turbidity value, i » up to]
hardness
"4H" Writability
I.
i

The "writability test" is carried out using pencils manufactured under the designation "Gasteil" from AW Faber-Castell, Nuremberg. The symbols ^M 2H ^H , "3H" and "4H" represent the hardness of the pencils as internationally recognized symbols .

Example 2

It becomes an acrylonitrile / styrene copolymer using a

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_ ₁₂ _ 212-59T3

A certain mixing ratio is mixed with Polyäthylenterepfathalat, and the mass obtained is processed by melt extrusion using a T-die to give sheets with a thickness of 150 / U. The films are then stretched at 85 ⁰ C by a biaxial stretching machine at the same time the length and width according to the two- or three-times'.

The physical properties of the foils are from Table II evident.

Table II

Proportion of acrylonitrile / styrene copolymer, Weight percent of the total mass

Degree of stretching,. Multiple of length χ multiple of width

Fat after the warrior,

Ultimate Strength, kg / cm 'Elongation at Break, Percent

Light transmission factor, percent

Turbidity value, percent writability

2 χ 2 48 880 110 80, 8th 92, 5 To
hardness
"4H"

3x3

26 1210 45

84.2 90.6

to

hardness

"3H"

35

2x2

45

650

55

72.3 94.3

to

hardness

¹ MH "

3x3

25th 730 23

77.6 96.6

up to hardness "3H"

example

Ordinary quality polystyrene is processed using

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different mixing ratios mixed with polyethylene terephthalate, and the resulting mass is processed by melt extrusion using a T-die to give films with a thickness of 150 Ai . The films are covered only in the longitudinal direction by 3.5 times at 90 ⁰ C by a biaxial stretching machine.

The physical properties of the films are shown in Table III. ·.

Table III

3.5 • 10 35 Proportion of polystyrene,
! Weight percent of
j total mass 23 3.5 3.5 j Beckgracl,
I multiple of the length 1230 22nd 22nd Fat after stretching,
/ ^u 115 1170 910 Breaking Strength, kg / cm 84.3 53 32 Elongation at break, percent 81, 6 80.0 72.4 Translucency
factor, percent to
hardness
"H" "83.0 93.1 Turbidity value, percent to
hardness
"H" to
hardness
"3H" Describability
-

example

Eip flaky H, 4'-hydroxydiphenyl-2,2-propane polycarbonate

will'

When applying the mixing ratio shown in Table IV

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Holdinge mixed with polyethylene terephthalate, and the obtained In each case, the mass is processed by melt extrusion using a T-die to give films with a thickness of 150 / rev. The films are at different temperatures and using different degrees of stretching by means of a Biaxial stretching machine stretched both lengthwise and widthwise.

The "physical properties" of the films are from Table IV evident.

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Table IV

Proportion of the polycarbonate, percent by weight of the total mass

ι Keckgrad,,! Multiple of length χ multiple of width

Stretching temperature ο «

3x3

90

; Thickness of extru-; dated slide, / U

Γ breaking strength— I kg / cm ^

25th

10

20th

3x3

90

25th

ui — Lj:

30th

3x3

3x3

3x3 3x3! 2.5x2.5

—I

90

90

26th

j Elongation at break, % \ translucent ^ [_kei1isfactor, # I opacity value, '#

• roughness of the ^! Polien surface,

1010

Writability

84.3

1180 ~~ 7f

85.8 "8" 2.6 "

-4.

25th

90

90

1260 ι 1130

76

1180 the
foil
breaks

31

! during 75 des

1240

87.5j 85.0 "8575Π 89T ^

0.3

0.4

0.6

0.7

Rekkens

up to up to up to up to up to

Hardness: hardness · hardness j hardness "2B""H" j "2H" i ⁿ 3H "

Hardness, "4H" I.

50

2x2

2x2

160

48 980

74.5
~ "9373""

0.8

to"]
hardness

⁷¹ » ³ not -94V2 * ¹ , equal-

j massive

opacity

0.8

Tb is "for

Hardness j "4H"

The values listed in Table IV show that both the writability and the haze value are 10 to 35 percent by weight Polycarbonate-containing film are just as good as the values obtained according to Example 1. With a polycarbonate content of 5 percent by weight, the writability and the haze value are poor. The 50 weight percent polycarbonate The film containing it does not have a uniform opacity.

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Claims (3)

Claims 1. Synthetic writing paper, characterized that it's off a) a linear polyester and b) a high polymer acrylic polymer, styrene polymer or Polycarbonate with a higher glass transition temperature than that of component a) in a proportion of 7 to 35 percent by weight j based on the mixture of the oeiden polymeric components, consists. 2. Synthetic writing paper according to claim 1, characterized in that that it is component a) polyethylene terephthalate, Polyethylene isophthalate or an ethylene terephthalate / ethylene isophthalate copolymer and as component b) polymethyl methacrylate, an acrylonitrile / styrene copolymer, an acrylonitrile / butadiene / styrene copolymer, Polystyrene or one of 4, Jl'-dihydroxydiphenyl-2,2-propane contains derived polycarbonate. 3. A method for producing the writing paper according to claim 1 or 2, characterized in that the linear polyester component a) is mixed homogeneously with the high polymer component b) using the mixing ratio specified in claim 1, the polymer mass obtained is processed into a film and the film formed is at a temperature above the freezing temperature of the linear polyester , But below the- 109850/1827 sen melting point, biaxially stretched and optionally the stretched film by a thermal treatment at a temperature above the stretching temperature of the linear polyester, but below the melting point of the high polymer and the linear polyester, gives high temperature resistance. k * Process according to Claim 3 »characterized in that the film is stretched at temperatures of 85 to 95 ° C. W 5 · Method according to claim 3 or * l _e, characterized in that the film is stretched both lengthwise and widthwise by 2.5 to 3.5 times the original length or width. 109850/1827